WO2016165779A1 - Élément palier à coulissement hydrodynamique - Google Patents

Élément palier à coulissement hydrodynamique Download PDF

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Publication number
WO2016165779A1
WO2016165779A1 PCT/EP2015/058436 EP2015058436W WO2016165779A1 WO 2016165779 A1 WO2016165779 A1 WO 2016165779A1 EP 2015058436 W EP2015058436 W EP 2015058436W WO 2016165779 A1 WO2016165779 A1 WO 2016165779A1
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WO
WIPO (PCT)
Prior art keywords
sliding
texture
hydrodynamic
bearing member
sliding bearing
Prior art date
Application number
PCT/EP2015/058436
Other languages
English (en)
Inventor
Staffan Johansson
Original Assignee
Volvo Truck Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Volvo Truck Corporation filed Critical Volvo Truck Corporation
Priority to PCT/EP2015/058436 priority Critical patent/WO2016165779A1/fr
Publication of WO2016165779A1 publication Critical patent/WO2016165779A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/02—Sliding-contact bearings for exclusively rotary movement for radial load only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/12—Sliding-contact bearings for exclusively rotary movement characterised by features not related to the direction of the load
    • F16C17/18—Sliding-contact bearings for exclusively rotary movement characterised by features not related to the direction of the load with floating brasses or brushing, rotatable at a reduced speed
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/103—Construction relative to lubrication with liquid, e.g. oil, as lubricant retained in or near the bearing
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2240/00—Specified values or numerical ranges of parameters; Relations between them
    • F16C2240/40—Linear dimensions, e.g. length, radius, thickness, gap
    • F16C2240/42—Groove sizes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2240/00—Specified values or numerical ranges of parameters; Relations between them
    • F16C2240/40—Linear dimensions, e.g. length, radius, thickness, gap
    • F16C2240/44—Hole or pocket sizes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2360/00—Engines or pumps
    • F16C2360/22—Internal combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C9/00—Bearings for crankshafts or connecting-rods; Attachment of connecting-rods
    • F16C9/02—Crankshaft bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C9/00—Bearings for crankshafts or connecting-rods; Attachment of connecting-rods
    • F16C9/04—Connecting-rod bearings; Attachments thereof

Definitions

  • a hydrodynamic sliding bearing member A hydrodynamic sliding bearing member
  • the invention relates to a hydrodynamic sliding bearing member having a first sliding surface and configured for being slidably arranged in a circumferential direction relative to a second sliding surface of a second sliding member via a viscous fluid.
  • the invention also relates to a hydrodynamic sliding bearing arrangement such as a journal bearing, a main bearing, a connecting rod bearing, comprising a hydrodynamic sliding bearing member.
  • the invention relates to an internal combustion engine for a vehicle comprising a hydrodynamic sliding bearing member. Moreover, the invention relates to a vehicle comprising a hydrodynamic sliding bearing member.
  • the invention can be applied in heavy-duty vehicles, such as trucks, buses and construction equipment. Although the invention will be described in relation to a truck, the invention is not restricted to this particular vehicle, but may also be used in other type of vehicles such as cars, industrial construction machines, wheel loaders, etc. The invention may also be applied in any other type of mechanical devices that employ journal bearings.
  • Tribology refers to the science of friction, lubrication and wear.
  • a significant part of the total friction losses in engines are found in sliding bearing arrangements, such as journal bearings, main bearings or connecting rod bearings of a vehicle.
  • a fluid film such as a viscous fluid should separate the sliding surfaces of the bearing.
  • One significant function of the viscous fluid is to provide protection for moving parts, thereby reducing friction and wear of the machine.
  • the viscous fluid may typically also contribute to cooling, debris removal and prevention of corrosion.
  • the sliding surfaces may be formed by, for instance, a shaft and a shell of the arrangement.
  • a fluid film can be generated using both, or one of, hydrodynamic pressure build-up caused by the motion of the sliding surfaces, and, hydrostatic pressure caused by an oil pump delivering oil pressure directly to the component.
  • lubrication reduces friction between the two surfaces in relative motion.
  • the type of lubrication i.e. the lubrication regime, is commonly categorised as boundary lubrication, mixed lubrication or hydrodynamic lubrication.
  • the hydrodynamic pressure in the lubricant keeps the sliding surfaces of the bearing and shaft separated from each other.
  • the hydrodynamic pressure is caused by the sliding motion. Accordingly, and in basic terms, the thickness of the film exceeds the combined roughness height of the surfaces.
  • Wear is generally not as severe in the hydrodynamic lubrication regime as in the boundary and mixed lubrication regime. This is partly due to that little, or no, direct metal-to-metal contact occurs in the hydrodynamic lubrication regime.
  • journal bearing arrangements such as journal bearings are relatively inexpensive compared to other bearings with a similar load rating.
  • a sliding bearing arrangement can be as simple as two smooth surfaces with seals to retain the viscous fluid.
  • a journal bearing is typically uncomplicated to manufacture, easy to assemble and disassemble, has low weight and capable of handling large transients in acceleration and load.
  • the arrangement gives large frictional losses, in particular compared to e.g. rolling element bearings.
  • the journal bearing has significantly larger mating surface areas, i.e. sliding surface areas, compared to a rolling element bearing.
  • the sliding velocity is typically much higher for a journal bearing compared to a rolling element bearing.
  • a large contact area in combination with a high sliding speed gives high viscous frictional losses for journal bearings, i.e. high shearing of the fluid film.
  • hydrodynamic journal bearings are critical power transmission components that are carrying increasingly high loads because of the increasing power density in the vehicles. In order to reduce the friction losses in sliding bearing
  • US 2005/0175263 A1 discloses a sliding device comprising a first sliding member and a second sliding member that are slidably arranged and supported through a viscous fluid.
  • at least one pit on at least one of the first and second sliding members in order to generate a viscous fluid flow.
  • the positioning and/or the geometry of texture patterns and texture elements may have different effects depending on whether the sliding bearing arrangement operates in the boundary, mixed or the hydrodynamic lubrication regime. That is, the overall design of a journal bearing operating in the hydrodynamic lubrication regime may not be the same as in the boundary and/or mixed lubrication regime. On the contrary, if a texture pattern and/or texture elements intended for the hydrodynamic lubrication regime were used for the boundary lubrication regime, this type of pattern and/or elements would likely contribute to an increase in friction and possibly cause the system to seizure. To this end, research and development activities relating to sliding bearing arrangements operating in the hydrodynamic lubrication regime are generally demanding and complex assignments that require extensive knowledge of combustion engines and combustion engine components.
  • the object is achieved by a
  • hydrodynamic sliding bearing member according to independent claim 1 . Further optional features of the invention are recited in the dependent claims.
  • hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction and in an axial direction, and configured for being slidably arranged in the circumferential direction C relative to a second sliding surface of a second sliding member via a viscous fluid to permit the hydrodynamic sliding bearing member to operate under hydrodynamic lubrication.
  • the first sliding surface has a texture pattern, which comprises at least one texture element.
  • the texture element has a trailing region defined by a trailing surface extending from the first sliding surface to a bottom surface of the texture element.
  • a first section of the trailing surface is adapted to define a converging gap with the sliding surface of the second sliding member and extends a distance from the first sliding surface in a radial direction, which is smaller than 50% of the texture element depth.
  • a texture element shape that is both capable of increasing the hydrodynamic pressure generation, by utilising an optimal design at the trailing side of the texture, and, at the same time reducing the viscous film shear losses compared to a texture element shape having a leading surface (leading region) and a trailing surface (trailing region) that each forms a right angle with respect to the sliding surface, i.e. a texture shape having an essentially rectangular shaped cross section as seen in the circumferential direction and the radial direction.
  • the converging gap is configured to generate an increase in hydrodynamic pressure, which results in that the viscous film thickness separating the two active surfaces is increased. Due to an increase in the viscous film thickness, the hydrodynamic friction is reduced, thus reducing the viscous film shear losses, while minimizing any possible contribution from boundary friction.
  • the shape of the texture element can be improved according to example embodiments in order to gain an increase in the hydrodynamic pressure generation, while reducing the viscous film shear losses and enabling an increased fluid film thickness thus decreasing the likelihood of material-to- material friction and subsequent increase in contact friction and wear.
  • the example embodiments of the invention are capable of increasing the hydrodynamic pressure generation, while reducing the viscous film shear losses, it is believed that a reduction of the fuel consumption is possible due to that there is correlation between a reduction of the viscous losses and a reduction of fuel consumption.
  • the term "converging gap” refers to the geometry of the first section of the texture element, which upon a sliding motion of the first sliding surface relative to the second sliding surface generates a hydrodynamic pressure in the viscous fluid film in conjunction with the opposite second sliding surface of the second sliding member.
  • the example embodiments of the invention provides a texture element shape having an optimized surface for generating a hydrodynamic pressure in a viscous fluid film confined between the sliding surfaces of the bearing arrangement, i.e. between two solid surfaces with a relative sliding motion. Accordingly, the example embodiments are configured to utilize the hydrodynamic effect of the viscous fluid in the converging gap as defined by the first section in conjunction with the second sliding surface in order to minimize the frictional forces between the first sliding bearing member and the second sliding bearing member.
  • first section of the trailing surface of the texture element forms the converging gap with the sliding surface of the second sliding member during operation, i.e. when the first sliding surface is sliding relative to the second sliding surface so as to operate under hydrodynamic lubrication.
  • the first section of the trailing surface is configured to form a converging gap with the sliding surface of the second sliding member during operation of the hydrodynamic sliding bearing member. That is, the first section of the trailing surface is configured to form a converging gap with the sliding surface of the second sliding member during operation of the hydrodynamic sliding bearing arrangement.
  • the configuration of the first section of the trailing surface may be designed in several different ways in order to define (form) a converging gap with a sliding surface of a second sliding member as will be described further herein.
  • the distance may even be smaller than 50% of the texture element depth.
  • the distance from the first sliding surface in the radial direction may be smaller than 40% of the texture element depth.
  • the distance from the first sliding surface in the radial direction may be smaller than 25 % of the texture element depth.
  • the distance from the first sliding surface in the radial direction may be smaller than 10 % of the texture element depth.
  • the distance from the first sliding surface in the radial direction R may be smaller than 5 % of the texture element depth.
  • the distance from the first sliding surface in the radial direction is at least more than 0 % of the depth of the texture element depth.
  • the distance from the first sliding surface in the radial direction is at least more than 2 % of the depth of the texture element depth.
  • the distance from the first sliding surface in the radial direction is at least more than 2 % of the depth of the texture element depth, but smaller than 50% of the texture element depth. In another example, the distance from the first sliding surface in the radial direction is at least more than 5 % of the depth of the texture element depth, but smaller than 30% of the texture element depth.
  • first section of the trailing surface may typically have an extension in the circumferential direction which is larger than 5% and smaller than 50% of the length of the texture element in the circumferential direction.
  • the first section of the trailing surface may typically have an extension in the circumferential direction which is larger than 10% and smaller than 50% of the length of the texture element in the circumferential direction.
  • the first section of the trailing surface may typically have an extension in the circumferential direction which is larger than 15% and smaller than 50% of the length of the texture element in the circumferential direction.
  • the first section may also have an axial extension, which is tapering along the circumferential direction in a direction away from a leading edge of the texture element.
  • Other shapes of the first section are also conceivable as described herein.
  • the tapered first section defines a convex curvature, as seen in the axial direction A and in the circumferential direction C.
  • the degree of the curvature of the tapered first section of the trailing surface is greater than a curvature of the leading edge of the texture element.
  • the degree of the curvature of the tapered first section is similar to the curvature of the leading edge of the texture element.
  • the tapered first section comprises two radial extending parts which are linearly tapering along the circumferential direction in a direction away from the leading edge of the texture element.
  • the first section may have an axial extension which is constant along the circumferential direction in a direction away from the leading edge of the texture element.
  • the trailing surface may in some example embodiments further be defined by a second section.
  • the trailing surface is generally defined by the first section and the second section.
  • the second section of the trailing surface extending from the bottom surface has a normal with a different direction than a normal of the first section.
  • said second section of said trailing surface extending from the bottom surface is arranged to extend essentially perpendicular from said bottom surface.
  • the second section may be inclined with respect to the bottom surface by an angle between 45 - 90 degrees, as long as the first section is adapted to form the converging gap with the second sliding surface upon operation of the hydrodynamic sliding bearing member (arrangement).
  • first section and the second section are typically connected at a transition point.
  • the first section of the trailing surface may be adapted in several different ways in order to define (form) a converging gap with a sliding surface of a second sliding member as will be described further herein.
  • the texture element has a cross sectional shape extending in the circumferential direction and a radial direction, said first section of the trailing surface being arranged to deviate from said first sliding surface by an angle a c .
  • the first section of the trailing surface is adapted to define a converging gap with a sliding surface of a second sliding member by means of having the first section of the trailing surface arranged to deviate from the first sliding surface by an angle a c .
  • the first sliding surface here refers to the plateau area of the first sliding surface.
  • the texture element has a cross sectional shape extending in the circumferential direction and a radial direction, the first section of the trailing surface being arranged to deviate from the plateau area of the first sliding surface by the angle a c .
  • the angle a c may be between 0.1 - 5 degrees. In this way, there is provided a texture element shape configured to provide an optimal build-up of
  • angle a c may be set to another angle depending on the selection of manufacturing method having specific limitations. Also, operation conditions, sliding velocities, contact conditions oil film thickness and application of the texture element and the hydrodynamic sliding bearing member may cause a c to be selected in a different interval then specified herein.
  • the angle a c is about 0.5 degrees. In another example, the angle a c is about 0.3 degrees. Still preferably, the angle a c may be between 1 - 3 degrees. Thus, it should be conceivable that the value of the angle a c may be different for different bearing members and installations.
  • a minimum depth of the texture elements should be above 10 ⁇ , as further described herein.
  • the texture element has a cross sectional shape extending in the circumferential direction and the radial direction, said first section of the trailing surface being arranged to deviate from said first sliding surface by an angle a c , and wherein the first section is a straight wall surface as seen in the cross section extending in the circumferential direction and a radial direction.
  • a texture element having a trailing region, as seen in the sliding direction along the circumferential direction, said trailing region having a trailing surface defined by a first inclined section and a second section.
  • the second section extends perpendicular from the bottom surface of the texture element to the first inclined section, wherein said second section has a length smaller than said texture element depth, in which the depth is defined by the distance between the sliding surface and the bottom surface of the texture element, as seen in radial direction.
  • the first inclined section extends from the transition point to the sliding surface of the hydrodynamic sliding bearing member, wherein the first inclined section forms the angle a c with the sliding surface of the hydrodynamic sliding bearing member.
  • the first section of the trailing surface is adapted to define (form) a converging gap with a sliding surface of a second sliding member by a curved wall surface.
  • the first section is a curved wall surface as seen in a cross section extending in the circumferential direction and a radial direction.
  • the first section extends to the second section of the trailing surface, as mentioned herein. In this way, there is provided a texture element shape configured to provide an optimal build-up of hydrodynamic pressure.
  • the first section of the trailing surface is adapted to define (form) a converging gap with a sliding surface of a second sliding member by having a step shaped first section.
  • said first section is a step shaped section being defined by a first step surface extending essentially perpendicular from said sliding surface and a second step surface extending essentially perpendicular from said first surface to a second section.
  • the texture element is defined by a leading region having a leading surface extending from said bottom surface to said first sliding surface by an angle of between 45 - 90 degrees.
  • the texture element is defined by a leading region having a leading surface extending essentially perpendicular from said bottom surface to said first sliding surface.
  • the bottom surface may be essentially parallel to said sliding surface.
  • texture element in which the bottom surface is essentially parallel to the sliding surface it is ensured that texture depth is sufficient along the tangential texture element length (length of the texture element in the circumferential direction), thus maintaining the desired fluid film thickness within the texture and thus not increasing the viscous shear losses.
  • a length of said bottom surface has an extension in the circumferential direction which is larger than 50 % and smaller than 85% of the length of the texture element in the circumferential direction. Still preferably, a length of said bottom surface has an extension in the circumferential direction which is larger than 60 % and smaller than 75% of the length of the texture element in the circumferential direction.
  • the first sliding surface has opposite boundaries, as seen in the axial direction, wherein an area density of the texture element decreases towards at least one of the axial boundaries, as seen from a centre of the first sliding surface in the axial direction.
  • a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction and in an axial direction, and configured for being slidably arranged in the circumferential direction relative to a second sliding surface of a second sliding member via a viscous fluid to permit the hydrodynamic sliding bearing member to operate under hydrodynamic lubrication.
  • the first sliding surface has opposite boundaries, as seen in the axial direction.
  • the first sliding surface has a texture pattern, which comprises at least one texture element.
  • an area density of the texture element decreases towards at least one of the axial boundaries, as seen from a centre of the first sliding surface in the axial direction.
  • the texture pattern may comprise a plurality of texture elements.
  • an area density of the texture elements decreases towards at least one of the axial boundaries, as seen from a centre of the first sliding surface in the axial direction.
  • the first sliding surface has a texture pattern, wherein the area density of the texture element(s) decreases towards at least one of the axial boundaries, as seen from a centre of the first sliding surface in the axial direction A, it becomes possible to provide a hydrodynamic sliding bearing member which is capable of further reducing frictional losses in the hydrodynamic lubrication regime, while reducing lubrication leakages at the axial boundary of the hydrodynamic sliding bearing member.
  • the inventor has recognized that a significant part of the total friction losses in an internal combustion engine and its components are viscous friction losses, and has observed that a reduction of the viscous losses is beneficial for reduction of fuel consumption.
  • the texture element(s) is configured to generate a decrease in the average shear force of the sliding surfaces of the bearing member (or bearing arrangement) at the locations of the texture element(s) in order to minimize hydrodynamic (viscous) friction losses
  • hydrodynamic sliding bearing member has the potential to lower the hydrodynamic friction losses without any significant increase of the mechanical friction losses.
  • one advantage by the provision that the area density of the texture elements (or the at least one texture element) decreases towards at least one of the axial boundaries, as seen from a centre of the first sliding surface in the axial direction, is that the present invention contributes to reduce the risk of having a lubrication leakage at the axial boundary of the hydrodynamic sliding bearing member, thus decreasing the risk of material-to-material contact.
  • the term "material” should be distinguished from the film separating the two members (first sliding bearing member and second sliding bearing member), thus the term “material” here typically refers to the solid parts (most commonly metal) of the component. An increased amount of material-to-material contact is considered to increase the boundary friction.
  • a leakage of lubrication at the axial boundary typically has a negative impact on the possibility of generating a hydrodynamic pressure at the hydrodynamic sliding bearing member.
  • the hydrodynamic friction is significantly reduced. In other words, leakage causes a decreased build-up of hydrodynamic pressure, thus increasing friction.
  • the texture arrangement is optimized for a
  • hydrodynamic sliding bearing member in terms of hydrodynamic friction losses.
  • a further benefit of providing the textured pattern with texture element(s) according to the above arrangement is that wear on sliding surfaces may be reduced because wear particle debris can be retained in the texture elements of the textured pattern.
  • This type of wear is often denoted three-body abrasion.
  • Three-body abrasion can be described with foreign (wear) particles entering the fluid film that separates two surfaces or are generated in material-to-material contact of the two surfaces; in this context, having foreign particles between two mating surfaces increases friction.
  • the concentration of foreign particles can increase over time; both because particles can continuously be generated from contact between the mating surfaces and also because foreign particles can remain in the contact zone a significant amount of time, thus allowing for a
  • concentration of particles in the contact with time may cause the number of foreign particles that enter a tribological contact to be greater than the amount of particles that exit the tribological contact.
  • embodiments of the invention can be used in various hydrodynamic sliding bearing arrangements, such as main bearings, journal bearings, connecting rod bearings etc.
  • the invention is mainly applied for hydrodynamic sliding bearing arrangements, such as journal bearings etc., which have a transient behaviour during each revolution.
  • the present invention is particularly useful for components (surfaces) that are rotatably (and slidably) arranged or configured to support a rotational motion in contrast to surfaces or components that are subjected to a reciprocating motion, such as a piston and cylinder liner.
  • the term “slidably” or “slidably arranged” may herein refer to interacting surfaces in relative motion.
  • the texture pattern is applied for parts of the hydrodynamic sliding bearing member which have an excess of fluid film thickness on a part or the completed circumference surface having the smallest separation during operation.
  • the amount of texture elements should be correlated to the amount of excess fluid film thickness.
  • the texture elements are applied to decrease the contact area of the sliding (mating) surfaces and to decrease the total shear resistance of the fluid, thus decreasing friction.
  • the shear resistance or drag losses within texture elements can be considered to be insignificant if the texture element depth is sufficiently large. In simple terms, without being bound by any theory, the shear resistance is to be considered as inversely proportional to the fluid film thickness in the texture elements.
  • the fluid film thickness in texture elements should here be compared with an untextured surface and the typical fluid film thickness separating (untextured) components.
  • a typical minimum fluid film thickness separating (untextured) components may be in the order of 1 -5 ⁇ . However, this range of the thickness is dependent on a multitude of parameters. Given that the fluid film thickness is 5 ⁇ , for a texture element with 100 ⁇ depth, the shear resistance within texture elements is approximately decreased with 95 % in the textures compared to the typical fluid film thickness separating the untextured components.
  • the excess fluid film thickness can be utilized to decrease the frictional losses for a hydrodynamic sliding bearing member and a hydrodynamic sliding bearing arrangement operating in the hydrodynamic lubrication regime.
  • the present invention provides the effect of reducing frictional losses in the hydrodynamic regime in an optimal manner, and without any significant increase of the mechanical friction losses.
  • the hydrodynamic sliding bearing member extends in the axial direction A, the circumferential direction C and a radial direction R.
  • the texture element extends in the axial direction A, the circumferential direction C and the radial direction R of the hydrodynamic sliding bearing member.
  • textured pattern is expressly defined for purposes of the example embodiments of the present invention as a regular, repeated pattern of distinct elements (typically in the form of depressions) such as depressions in the form of closed voids or grooves in the surface.
  • the substantial remainder of the surface may be defined by one or more plateaus.
  • the texture pattern may in some example embodiments refer to one single texture element, in which the area density of the texture element is decreasing towards the axial boundary(s). It should be noted that surface irregularities can also exist on the plateau surface area, however, said irregularities are of a
  • the textured pattern can be provided in any suitable way, such as by being machined via a milling, turning, or drilling operation, via chemical etching, water-jet cutting, abrasive blasting, or hydro-erosive grinding, or some combination of such operations. Other types of production methods than those listed above may also be used to produce texture elements.
  • the texture pattern comprises a set of axial rows of texture elements arranged in succession along the circumferential direction C, wherein the texture elements of at least one axial row are offset from the texture elements of another axial row, as seen in the axial direction A, so that a circumferential segment of the first sliding surface intersects at least one texture element in a substantial part of the first sliding surface.
  • the circumferential segment extends in the circumferential direction.
  • the circumferential segment typically extends across the entire circumferential length of the hydrodynamic sliding bearing member.
  • An advantage of this arrangement of the axial rows of texture elements is that the possibility of entrapment of wear particles is significantly improved since there is no path that is not obstructed by a texture element for the particles to travel a significant distance in the circumferential direction of the first sliding surface.
  • an area density of the texture element(s) decreases towards at least one of the axial boundaries, as seen from a centre of the first sliding surface in the axial direction A may refer to a given area of the first sliding surface, i.e. for a given surface element of the first sliding surface.
  • the provision that an area density of the texture element(s) decreases towards at least one of the axial boundaries, as seen from a centre of the first sliding surface in the axial direction A may refer to the entire area of the sliding surface.
  • the area density of the texture element(s) decreases towards at least one of the axial boundaries, as seen from the centre of the first sliding surface in the axial direction A, by decreasing at least one of an axial length E A and circumferential length E c of each texture element per unit area towards the axial boundary, as seen from the centre of the first sliding surface in the axial direction A.
  • This type of texture pattern is typically less complicated to design and
  • this type of texture pattern may reduce the risk of having leakages at the axial boundaries in a simple, yet efficient manner.
  • this type of texture pattern may reduce the risk of having leakages at the axial boundaries even further.
  • each texture element has an extension in the axial direction A, an extension in the circumferential direction C and an extension in the radial direction R of the hydrodynamic sliding bearing member.
  • a minimum axial length of the texture element may ordinarily be equal to or above 300 ⁇ .
  • a minimum circumferential length of the texture element may ordinarily be equal to or above 300 ⁇ .
  • an axial length and/or circumferential length of 300 ⁇ is to be regarded merely as an example of when the effects of the invention may be particularly significant.
  • the effects may still obtained by a length of the texture elements outside this value.
  • the axial length E A of the texture elements may typically be at least equal to or above 300 ⁇ .
  • the circumferential length E c of the texture elements may be at least equal to or above 300 ⁇ . This size of the texture element ensures that the boundary effects do not become too large so as to reduce the effects of the exemplary embodiments as mentioned above.
  • Boundary effects can be described with the following: When an arbitrary location on a mating surface starts to transvers a texture element, the shear friction losses do not decrease instantly. The generation of hydrodynamic pressure decreases much more rapidly for said motion than the shear friction losses. This means that if the texture elements are of too short elongation in the direction of motion, the relative decrease in generation of hydrodynamic pressure will be comparatively significantly larger than the decrease in shear friction loss, which will eventually increase the amount of material-to- material contact increasing boundary friction. If the textures are sufficiently large, boundary effects are reduced to an extent that is no longer significant.
  • the axial length E A of the texture elements may be between substantially 300 - 10 000 ⁇ .
  • the circumferential length E c of the texture elements may still preferably be between substantially 300-10 000 ⁇ .
  • the axial length E A of the texture elements may be between substantially 1 000 - 10 000 ⁇ .
  • the circumferential length E c of the texture elements may still preferably be between substantially 1 000 - 10 000 ⁇ .
  • the axial length E A of the texture elements may be between substantially 2 000 - 10 000 ⁇ .
  • the circumferential length E c of the texture elements may still preferably be between substantially 2 000 - 10 000 ⁇ .
  • the depth of the texture element(s) should typically be above 10 ⁇ .
  • a depth of the texture elements may ordinarily be between substantially 20 - 200 ⁇ .
  • a minimum depth of the texture element(s) may be substantially equal to 35 ⁇ . While it is presently believed that providing texture elements or depressions with depths less than 35 ⁇ , such as around 20 ⁇ , may, in some circumstances provide beneficial results, in some circumstances textures or depressions with depths around 30 ⁇ may actually increase friction, and it is presently believed that texture elements or depressions of at least 35 ⁇ and, likely, substantially greater than 35 ⁇ will provide most beneficial results.
  • the hydrodynamic sliding bearing member comprises a texture pattern having a plurality of the texture elements, wherein the depth of the texture elements is between about 20 - 200 ⁇ . Still preferably, the depth of the texture elements should be between about 35 - 200 ⁇ . Still preferably, a minimum depth of the texture elements may be equal to or greater than 35 ⁇ . According to one example embodiments, the hydrodynamic sliding bearing member comprises a texture pattern having one texture element, wherein the depth of the texture element is between about 20 - 200 ⁇ . Still preferably, the depth of the one texture element should be between about 35 - 200 ⁇ . Still preferably, a minimum depth of the one texture element may be equal to or greater than 35 ⁇ .
  • the area density of the texture elements decreases towards at least one of the axial boundaries, as seen from the centre of the first sliding surface in the axial direction A, by decreasing the quantity of texture elements towards at least one of the axial boundaries, as seen from the centre of the first sliding surface in the axial direction A.
  • decreasing the area density may either be linear or non-linear. That is, in some example embodiments, the quantity of texture elements towards at least one of the axial boundaries is decreasing linearly, as seen from the centre of the first sliding surface in the axial direction A. In other example
  • the quantity of texture elements towards at least one of the axial boundaries may be decreasing non-linearly, as seen from the centre of the first sliding surface in the axial direction A.
  • the quantity of texture elements and how the quantity of the texture elements should decrease towards the axial boundary, i.e. from a texture element at the centre of the first sliding surface to a texture element at the axial boundary is typically selected in view of the dimensions and shapes of the sliding bearing member and the texture elements, type of installation and purpose, as well as type of texture pattern.
  • the area density of the texture element(s) decreases towards both of the axial boundaries, as seen from the centre of the first sliding surface in the axial direction A.
  • a depth of the texture element(s) forming the textured pattern decreases towards at least one of the axial boundaries, as seen from the centre of the first sliding surface in the axial direction A.
  • the texture elements should be sufficiently deep so that the viscous film shear force within the texture elements is negligible, texture boundary effects excluded.
  • Negligible viscous film shear force is here defined as that the viscous film shear force in texture elements, texture boundary effects not included, should typically be less than 5 % compared to the viscous film shear force acting between the plateaus of the two surfaces.
  • the depth of the texture element(s) forming the textured pattern may be kept constant towards at least one of the axial boundaries, as seen from the centre of the first sliding surface in the axial direction A.
  • the depth of the texture element(s) forming the textured pattern may be kept constant towards both axial boundaries, as seen from the centre of the first sliding surface in the axial direction A.
  • an outer region of the first sliding surface adjacent an axial outer boundary is free from texture elements.
  • axial leakage has an effect on the hydrodynamic pressure build-up along all of the axial length L c . Since the effect is largest at the axial boundaries, the risk is further improved by providing a region of no texture elements adjacent and around the axial boundaries to counteract the leakage in an efficient manner.
  • the term "outer region" may refer to 5 % of the total area of the first sliding surface as seen in the axial distance.
  • the extension of the outer region may be between 0.1 - 10 % of the total axial length of the sliding surface.
  • the extension of the outer region may be between 0.1 - 5 % of the total axial length of the sliding surface.
  • the textured pattern comprises a plurality of texture elements in the form of depressions. It is to be noted that texture elements or depressions may also herein be denoted as closed voids. In one example, the textured pattern comprises one texture element in the form of a groove. In addition, it should be readily appreciated that the texture elements are typically configured for containing viscous fluid.
  • the depth of the texture element may be defined as the depth in the radial direction, and further defined as the distance from the sliding surface to the bottom surface of the texture element.
  • the texture element may typically be regarded as depressions rather than that the plateau areas that are areas that extrude from the bottom surface of the texture element.
  • the shapes of the texture elements may be provided in several different forms.
  • the shape as seen in the axial direction and the circumferential direction may resemble a part of a rectangle.
  • other shapes are conceivable such as a part of a circle, or part of an ellipse, or the like.
  • the shape as seen in the axial direction and the circumferential direction is an ellipse.
  • a cross sectional shape of the texture element may here also refer to the cross sectional shape of the texture element, as seen in the sliding direction and the radial direction.
  • an area between two adjacent texture elements may form a plateau area.
  • each of the plateau areas of the first sliding surface of the hydrodynamic sliding bearing member may be provided with a machined roughness (sometimes also denoted as a machined roughness pattern).
  • the direction of the machined roughness may extend essentially along the entire axial length of the first sliding surface.
  • the direction of the machined roughness may be orthogonal to the sliding direction (circumferential direction).
  • the generation of the hydrodynamic pressure may increase even if a certain type of texture elements have a negative impact on the generation of the hydrodynamic pressure.
  • the machined roughness may for instance refer to arithmetical mean roughness.
  • the surface area of the plateau area may be between about 20-95 percent of a total area of the first sliding surface.
  • the area of the sliding surface not being occupied by the texture elements may refer to the plateau area.
  • the plateau area may also herein be denoted as a non-textured surface area, or simply as a plateau.
  • a textured area of the texture pattern may be between about 5-80 percent of a total area of the first sliding surface.
  • a textured area of the texture pattern between about 5-80 percent of a total area of the first sliding surface provides a sufficiently large area with zero friction and an improved utilization of the non-linear behavior of film thickness and oil film pressure which generates the largest possible relative average film thickness.
  • the textured area of the texture pattern is between 30 - 50 percent. In this manner, the greatest possible reduction in friction is provided, while retaining the tribological contact in the hydrodynamic lubrication regime.
  • the texture elements are typically arranged in a set of rows, as mentioned above, wherein at least one of the rows is located offset from another row, or several other rows.
  • At least a part of the plurality of the texture elements of the texture pattern is arranged in succession in a given area along the axial direction A.
  • at least a part of the plurality of the texture elements of the texture pattern is further arranged in succession in a given area along the circumferential direction C.
  • At least a part of the plurality of the texture elements of the texture pattern is arranged in a grid pattern extending in succession along the axial direction A and the circumferential direction C.
  • the texture elements are spaced from one another along the axial direction A by at least 100 ⁇ .
  • the distance is measured between a centre region of one texture element and a centre region of another texture element.
  • the area density of the texture elements is further varied along the circumferential direction C.
  • the area density can be varied in similar manner as mentioned above with respect to decreasing area density towards the axial boundary.
  • the area density of the texture elements may be varied along the circumferential direction C by decreasing at least one of the axial length E A and the circumferential length E c of each texture element per unit along the length of the first sliding surface as seen circumferential direction C of the first sliding surface.
  • the area density of the texture elements may be varied along the circumferential direction C by increasing at least one of the axial length E A and the circumferential length E c of each texture element per unit along the length of the first sliding surface as seen circumferential direction C of the first sliding surface.
  • the area density of the texture elements may be varied along the circumferential direction C by decreasing the quantity of texture elements along the length of the first sliding surface as seen circumferential direction C of the first sliding surface.
  • the area density of the texture elements may be varied along the circumferential direction C by increasing the quantity of texture elements along the length of the first sliding surface as seen circumferential direction C of the first sliding surface. It should be readily appreciated that decreasing or increasing the area density along the circumferential direction C may either be linear or non-linear.
  • decreasing or increasing the depth, quantity, or any one of the lengths of the element along the circumferential direction C may also either be linear or non-linear.
  • the texture element when the texture pattern comprises one single texture element, is an elongated continuous groove extending about the circumferential direction C and along the axial direction A as a spiral.
  • the length of the texture element can be greatly bigger than the circumferential length of the hydrodynamic sliding bearing member.
  • One advantage with this type of texture element is that the texture pattern becomes less complicated to produce on the sliding surface.
  • the texture pattern comprises a plurality of texture elements being uniformly distributed across the first sliding surface.
  • the invention also relates to a connecting rod of an internal combustion engine, which comprises a hydrodynamic sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions.
  • the connecting rod big end comprises the hydrodynamic sliding bearing member.
  • the connecting rod small end may comprise the hydrodynamic sliding bearing member.
  • the invention also relates to a journal bearing, which comprises a hydrodynamic sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions.
  • the invention also relates to a main bearing, which comprises a hydrodynamic sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions.
  • the invention also relates to a connecting rod bearing of an internal combustion engine, which comprises a hydrodynamic sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions.
  • the connecting rod bearing is arranged in the connecting rod big end.
  • the connecting rod bearing may be arranged in the connecting rod small end.
  • the invention also relates to hydrodynamic sliding bearing arrangement comprising a first sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions, and further a second sliding bearing member having a second sliding surface.
  • the first sliding bearing member is centred around the second sliding bearing member so that the hydrodynamic sliding bearing arrangement is configured to support a rotational motion between the first sliding bearing member and the second sliding bearing member. Further, as mentioned above, the first sliding bearing member is configured for being slidably arranged in the circumferential direction relative to the second sliding surface of the second sliding member via the viscous fluid to permit the hydrodynamic sliding bearing arrangement to operate under hydrodynamic lubrication.
  • the first sliding surface of the first sliding member is an inner circumferential surface and the second sliding surface of the second sliding bearing member is an outer circumferential surface. Further, the first sliding member is centred around the second sliding member so that the inner circumferential surface is allowed to slide about the outer circumferential surface via the viscous fluid upon rotation of the second sliding member relative to the first sliding member.
  • the inner circumferential surface is allowed to slide about the outer circumferential surface along the circumferential direction C.
  • centred around sometimes may refer to that the first sliding member is coaxially arranged about the second sliding member.
  • centred around may refer to the term “coaxially arranged” throughout the description.
  • the provision “upon rotation of the second sliding member relative to the first sliding member” may refer to that the first sliding member rotates, while the second sliding member is stationary.
  • the provision “upon rotation of the second sliding member relative to the first sliding member” may refer to that the first sliding member is stationary, while the second sliding member rotates.
  • the provision “upon rotation of the second sliding member relative to the first sliding member” may refer to that the first sliding member rotates and the second sliding member rotates.
  • the first sliding member may have a sliding velocity that is smaller than the velocity of the second sliding member.
  • the first sliding member may sometimes also be a part of the journal shaft, i.e. the inner sliding bearing member of the
  • the first sliding bearing member comprises an upper shell and a lower shell defining the first sliding surface, in which the upper and lower shells are arranged in a bearing housing.
  • the hydrodynamic sliding bearing arrangement further comprises the viscous fluid.
  • the viscous fluid is typically located in-between the first sliding bearing member and the second sliding bearing member.
  • the viscous fluid is typically a lubrication oil, which is well known to use in e.g. piston machines.
  • the thickness of the viscous fluid may vary according to operation conditions etc. However, the minimum thickness of the viscous fluid may be between about 1 - 5 ⁇ , as defined by the smallest distance between a non-textured surface area of the first sliding surface and a non-textured surface area of the second sliding surface. However, it should be readily appreciated that this may also be dependent on a multitude or other parameters.
  • the invention also relates an internal combustion engine for a vehicle, which comprises a hydrodynamic sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions, wherein the first sliding surface of the hydrodynamic sliding bearing member is an inner surface of a main bearing and the second sliding surface of the second sliding bearing member is a journal shaft surface.
  • the invention also relates to an internal combustion engine for a vehicle, comprising a hydrodynamic sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions, and further comprising a journal shaft and a connecting rod.
  • the connecting rod typically comprises a shaft extending between a connecting rod small end (i.e. a piston pin end) having a piston pin opening for receiving a piston pin and a connecting rod big end having a journal shaft opening for receiving a crankshaft journal.
  • the first sliding surface of the hydrodynamic sliding bearing is an inner surface of the journal shaft opening and the second sliding surface is a journal shaft surface, thereby supporting a rotational motion between the connecting rod and the journal shaft.
  • the invention also relates to a vehicle comprising a hydrodynamic sliding bearing member according to the first aspect and/or example embodiments as mentioned above with respect to the first aspect of the inventions.
  • the invention also relates to a vehicle comprising a hydrodynamic sliding bearing arrangement according to the example embodiments as mentioned above with respect to the first aspect of the inventions and/or with respect to the example embodiments of the bearing arrangement, as described above.
  • the invention will be described in relation to a truck, the invention is not restricted to this particular vehicle, but may also be used in other type of vehicles such as buses, construction equipment, cars, industrial construction machines, wheel loaders, etc.
  • the invention may not be restricted to vehicles, but may also be used in other type of mechanical devices which utilise journal bearings.
  • the exemplified tribological contacts operate in the hydrodynamic lubrication regime, meaning that surfaces are separated by the viscous fluid essentially at all times and no occurrence of material-to-material contact is likely to occur during normal operation of the hydrodynamic sliding bearing member.
  • the description of complete separation may sometimes only to be recognised as an aid in clarifying the example embodiments, thus it should be readily appreciated that a real tribological contact of two mating surfaces may experience some material-to-material contact both because a small number of the asperities extending furthest from the surfaces might come into contact and also that three-body particles in the separating film might cause material-to-material contact.
  • Fig. 1 is a perspective view of a vehicle in the form of a truck, which is provided with a hydrodynamic sliding bearing arrangement comprising a hydrodynamic sliding member according to an example embodiment of the present invention
  • Fig. 2a schematically illustrates an exploded view of an example embodiment of parts of an internal combustion engine for a vehicle comprising a hydrodynamic sliding bearing member according to an example embodiment of the present invention
  • Fig. 2b schematically illustrates the example embodiment of the internal combustion engine in fig. 2a in an assembled configuration, in which the internal combustion engine comprises a hydrodynamic sliding bearing member according to an example embodiment of the present invention
  • Fig. 2c is a perspective view of a crankshaft of an internal combustion engine including a hydrodynamic sliding bearing member according to an example embodiment of the present invention, in which the hydrodynamic sliding bearing member is arranged on said crankshaft;
  • Fig. 2d is a perspective view of a hydrodynamic sliding bearing arrangement in the form of a main bearing comprising a hydrodynamic sliding bearing member according to an example embodiment of the present invention, in which the texture pattern is provided on an inner sliding surface of the main bearing;
  • Fig. 2e is a perspective view of an example embodiment of a connecting rod comprising a hydrodynamic sliding bearing member according to an example embodiment of the present invention, in which the texture pattern is provided on any one of the connecting rod big end inner surface and the connecting rod small end inner surface;
  • Fig. 2f schematically illustrates a cross sectional view of the example embodiment of the connecting rod in fig. 2d according to the present invention
  • Fig. 2g is a perspective view of a hydrodynamic sliding bearing arrangement in the form of a main bearing comprising a hydrodynamic sliding bearing member according to another example embodiment of the present invention, in which the texture pattern is provided on an inner sliding surface of the main bearing;
  • Fig. 3 schematically illustrates a cross sectional view of an example embodiment of a hydrodynamic sliding bearing arrangement according to the present invention;
  • FIG. 4a - 4h schematically illustrate various example embodiments of a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction and in an axial direction, in which the first sliding surface has a texture pattern comprising a plurality of texture elements according to the invention, further, the hydrodynamic sliding bearing member is illustrated from a centre of the circumference corresponding to zero degrees, said surface extends between ⁇ 180 degrees;
  • Fig. 4i schematically illustrates an example embodiment of a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction and in an axial direction, in which the first sliding surface has a texture pattern comprising one texture element according to the invention, further, the hydrodynamic sliding bearing member is illustrated from a centre of the circumference corresponding to zero degrees, said surface extends between ⁇ 180 degrees;
  • Fig. 5a schematically illustrates a more detailed view of an example embodiment of the present invention, e.g. the example embodiment in fig. 4a;
  • Fig. 5b is a top view of an example embodiment of a texture element of the texture pattern according to the invention, e.g. a texture element as illustrated in fig. 5a;
  • Figs. 5c and 5d are perspective views of various example embodiments of the texture element, e.g. a texture element as illustrated in fig. 5b, in which a trailing region of the texture element is illustrated as seen in an axial direction, a circumferential direction and a radial direction;
  • Fig. 5e is a cross sectional view of one example embodiment of the texture element in e.g. fig. 5b and 5c, in which the cross sectional view illustrates the cross sectional shape of the texture elements along a circumferential direction and a radial direction;
  • Fig. 5b is a top view of an example embodiment of a texture element of the texture pattern according to the invention, e.g. a texture element as illustrated in fig. 5a
  • Figs. 5c and 5d are perspective views
  • FIG. 5f is a cross sectional view of another example embodiment of the texture element in fig. 5b, in which the cross sectional view illustrates the cross sectional shape of the texture elements along a circumferential direction and a radial direction
  • Fig. 5g is a cross sectional view of yet another example embodiment of the texture element in fig. 5b, in which the cross sectional view illustrates the cross sectional shape of the texture elements along a circumferential direction and a radial direction;
  • Figs. 5h and 5i are perspective views of further example embodiments of the texture element, e.g. a texture element as illustrated in fig. 5b, in which a trailing region of the texture element is illustrated as seen in an axial direction, a circumferential direction and a radial direction;
  • Figs. 6a - 6b schematically illustrates cross sectional views of various example
  • hydrodynamic sliding bearing member may sometimes be denoted as the sliding bearing member, sliding member or simply as the bearing member.
  • hydrodynamic sliding bearing arrangement may sometimes be denoted as the sliding bearing arrangement, sliding arrangement or simply as the bearing arrangement.
  • Fig. 1 is a perspective view of a vehicle 1 .
  • the vehicle includes an internal combustion engine 100 with a hydrodynamic sliding bearing member (although not shown in fig. 1 ) according to an example embodiment of the present invention.
  • hydrodynamic sliding bearing member is here typically a journal bearing or a part of journal bearing.
  • the hydrodynamic sliding bearing member may typically be a part of a hydrodynamic sliding bearing arrangement.
  • the hydrodynamic sliding bearing arrangement and/or the hydrodynamic sliding bearing member can be an integral part of a journal bearing, main bearing, connecting rod, connecting rod big end or connecting rod small end, as will be further described herein.
  • the hydrodynamic sliding bearing member may be a separate part forming the hydrodynamic sliding bearing arrangement in cooperation with another engine component, such as parts of the crankshaft and the connecting rod, as further described herein.
  • the hydrodynamic sliding bearing arrangement, the hydrodynamic sliding bearing member and possible installations of the components in a combustion engine of a vehicle are described in further detail with reference to figs. 2a - 2g, 3, 5a - 5i, and 6a - 6b.
  • the texture pattern of the example embodiments are described with particular reference to figs. 4a - 4i and 5a - 5i.
  • the vehicle 1 in fig. 1 is a truck, and the following example embodiments of the invention are described based on an exemplary truck to illustrate the configuration of hydrodynamic sliding bearing arrangement and the hydrodynamic sliding bearing member of the invention.
  • the vehicle may be a car, industrial construction machine, wheel loader and the like, as one skilled in the art will recognise.
  • the exemplary embodiments may be applied in any other type of mechanical devices that employ journal bearings, for instance a stationary application.
  • one example advantage of the example embodiments of the present invention is to reduce fuel consumption by reducing hydrodynamic friction losses in the internal combustion engine of the vehicle in an optimal way.
  • a vehicle 1 in the form of a truck which is provided with a hydrodynamic sliding bearing arrangement 10 comprising a hydrodynamic sliding member 20 according to an example embodiment of the present invention.
  • the hydrodynamic sliding bearing arrangement 10 and the hydrodynamic sliding member 20 are arranged in an internal combustion engine 100 of the vehicle 1 .
  • the internal combustion engine can work, for instance, according to the four-stroke and/or two-stroke principle; however, additional modes of operation can exist.
  • the combustion engine 100 may be a compression ignition, spark ignition engine or a piston compressor.
  • the internal combustion engine 100 in fig. 1 is designed to work according to the diesel process.
  • the engine 100 may generally comprise a cylinder and a piston, which
  • one end of the cylinder cavity is closed by an engine cylinder head.
  • the piston is provided in its upper surface with a piston bowl, which forms a combustion chamber together with an inner surface of the cylinder head and walls of the cylinder.
  • a combustion interface is formed between the combustion chamber and the cylinder head.
  • one or more induction ports may be arranged. The connection between a respective induction port and the cylinder can be opened and closed with an induction valve disposed in each induction port.
  • one or more exhaust ports are further arranged in the cylinder head.
  • the engine In order to inject fuel into a combustion chamber of a combustion engine cylinder of the internal combustion engine, the engine typically comprises an injector. However, it should be readily appreciated that the engine 100 may include a plurality of injectors for injecting fuel into a combustion chamber of a combustion engine cylinder.
  • Fig. 2a schematically illustrates an exploded view of an example embodiment of parts of an internal combustion engine for a vehicle comprising a hydrodynamic sliding bearing member according to an example embodiment of the present invention
  • Fig. 2b schematically illustrates the internal combustion engine in fig. 2a in an assembled configuration.
  • the internal combustion engine 100 here includes at least a set of pistons 19 connected to a set of connecting rods 15,
  • each piston 19 is connected to the connecting rod at the connecting rod small end 16.
  • each connecting rod 15 is connected via the connecting rod big end to a crankshaft 18.
  • the crankshaft is then connected to the engine block by one or several main bearings 14, as further described herein.
  • This type of engine configuration is well known in the art and thus not further described herein.
  • the internal combustion engine may include one or several bearings and/or bearing members.
  • the bearing is a hydrodynamic sliding bearing arrangement.
  • some of the current components of the combustion engine may include one or several bearing member(s) to form a bearing arrangement upon rotation of the components relative to each other.
  • an inner surface of a connecting rod big end and an outer surface of crankshaft journal shaft may form a simple sliding bearing arrangement.
  • the hydrodynamic sliding bearing member 20 according to the present invention can be installed as a separate or integral part in a hydrodynamic sliding bearing arrangement 10, for instance as a journal bearing 12.
  • the hydrodynamic sliding bearing member 20 according to the present invention can be installed as a separate or integral part in the connecting rod 15.
  • the hydrodynamic sliding bearing member 20 is installed, or incorporated, in the connecting rod small end 16 to form a connecting rod small end bearing 16'.
  • the hydrodynamic sliding bearing member 20 is installed, or incorporated, in the connecting rod big end 17 to form a connecting rod big end bearing 17'.
  • the hydrodynamic sliding bearing member 20 may be installed as a separate part or integral part of a main bearing 14.
  • the hydrodynamic sliding bearing member 20 is the main bearing.
  • journal bearings connecting rods, connecting rod end bearings, and main bearings etc. are well known in the art, and the wide variation of types of such components will not be further described herein, although one skilled in the art will not have difficulty in applying the disclosed technique to such components as may be required.
  • the hydrodynamic sliding bearing member 20 and the hydrodynamic sliding bearing arrangement 10 can be installed in an internal combustion engine of a vehicle.
  • Figs. 2c to 2g provide some examples and further details on engine components which can include the hydrodynamic sliding bearing member 20 and the hydrodynamic sliding bearing arrangement 10.
  • Fig. 2c is a perspective view of the crankshaft of the internal combustion engine as shown in figs. 2a and 2b.
  • the crankshaft 18 is typically supported by one or several main bearings 14.
  • the function of a main bearing is mainly to support the rotational motion of the crankshaft. That is, the main bearing should typically hold the crankshaft in place and prevent the forces created by the piston and transmitted to the crankshaft by the connecting rods from dislodging the crankshaft, instead forcing the crank to convert the reciprocating movement into rotation.
  • the main bearing is usually a journal bearing.
  • each main bearing may comprise two bearing halves. In other words, each bearing forms a half-circle. Each single bearing may thus be pressed into each of the journals of crankshaft until the bearing click into place.
  • fig. 2d is a perspective view of a hydrodynamic sliding bearing arrangement in the form of a main bearing comprising a hydrodynamic sliding bearing member according to an example embodiment of the present invention, in which a texture pattern 40 is provided on an inner sliding surface 22 of the main bearing.
  • the main bearing 14 may form a hydrodynamic sliding bearing arrangement with the journal of the crank shaft 18.
  • a hydrodynamic sliding bearing arrangement 10 comprising a first sliding bearing member 20, which has a first sliding surface 22 (inner sliding surface) and a second sliding member 30, which has second sliding surface 32.
  • the first sliding member 20 is centred about the second sliding member 30 so that the hydrodynamic sliding bearing arrangement 20 is configured to support a rotational motion between the first sliding member 20 and the second sliding member 30.
  • the first sliding bearing member 20 is co-axially centred about the second sliding bearing member 30 so that the hydrodynamic sliding bearing arrangement 20 is configured to support a rotational motion between the first sliding member 20 and the second sliding member 30
  • a viscous fluid is contained between the surfaces 22 and 32.
  • the viscous fluid is contained between the surfaces by 5 means of a seal (not shown) extending around the circumferential boundaries of the members 20 and 30.
  • a seal (not shown) extending around the circumferential boundaries of the members 20 and 30.
  • Such constructions of sealing between sliding surfaces are well known in the art, and therefore not further described herein. Accordingly, in the example embodiment when the first sliding surface 22 of the first sliding bearing member 20 is an inner circumferential surface, the first sliding member 20 is configured to be centred about
  • the second sliding bearing member 30 so that the inner circumferential surface is allowed to slide about the second sliding surface 32, which here corresponds to an outer circumferential surface of the second sliding member, via the viscous fluid 60 upon rotation of the second sliding member 30 relative the first sliding member 20.
  • the inner circumferential surface is allowed to slide about the outer
  • the viscous fluid 60 is here located in-between the first sliding bearing member 20 and the second sliding bearing member 30.
  • the hydrodynamic sliding bearing member 20 is configured for being slidably arranged in the circumferential direction C relative to the second sliding surface
  • the hydrodynamic sliding bearing member 20 to operate under hydrodynamic lubrication. That is, the first sliding surface 22 of the hydrodynamic sliding bearing member 20 is configured for being slidably arranged in the circumferential direction C relative to a second sliding surface 32 of a second sliding member 30 via a viscous fluid 60 to permit the
  • hydrodynamic lubrication refers to that hydrodynamic pressure is generated by the viscous fluid and the sliding motion so that the sliding surfaces are maintained
  • hydrodynamic sliding bearing member permits the hydrodynamic sliding bearing member to operate under hydrodynamic lubrication refers to that the hydrodynamic pressure caused by the sliding motion maintains the sliding surfaces essentially separated from each other.
  • each main bearing here includes a hydrodynamic sliding bearing
  • the first sliding surface 22 has a texture pattern 40, which comprises at least one texture element 42.
  • the texture element 42 has a trailing region 50 defined by a trailing surface 52 extending from the first sliding surface 22 to a bottom surface 56 of the texture element 42.
  • a first section 59 of the trailing surface 52 is adapted to define a converging gap G with a sliding surface 32 of a second sliding member 30 and extends a distance E RB from the first sliding surface 22 in a radial direction R, which is smaller than 50% of the texture element depth E R . It is to be noted that the first sliding surface extends around the texture element and thus both outside the trailing region 50 and outside the leading region 54.
  • an internal combustion engine 100 for a vehicle 1 comprising a hydrodynamic sliding bearing member 20 as described herein with respect to the various example embodiments, wherein the first sliding surface 22 of the hydrodynamic sliding bearing member 20 is an inner surface of a main bearing 14 and the second sliding surface 32 of the second sliding bearing member is a journal shaft surface, e.g. the crank shaft 18.
  • an internal combustion engine 100 for a vehicle 1 comprising a hydrodynamic sliding bearing arrangement 10 as described herein with respect to the various example embodiments, wherein the hydrodynamic sliding bearing arrangement 10 includes the hydrodynamic sliding bearing member 20 with the first sliding surface 22 and the second sliding bearing member 30 with the second sliding surface 32. Further, the hydrodynamic sliding bearing member 20 is slidably arranged about the second sliding bearing member 30. In addition, the hydrodynamic sliding bearing member 20 is connected to the engine block. Moreover, the second sliding bearing member 30 is connected to the crank shaft 18. In this manner, the hydrodynamic sliding bearing arrangement 10 is arranged to support a rotational motion of the crank shaft relative to the engine block.
  • the main bearing may also be provided as a bearing half.
  • the main bearing forms a half-circle.
  • the half-cricle main bearing is typically arranged about the crankshaft at an appropriate distance along the crank shaft as seen in the axial direction.
  • fig. 2g is a perspective view of a hydrodynamic sliding bearing arrangement in the form of a main bearing comprising a hydrodynamic sliding bearing member according to an example embodiment of the present invention, in which a texture pattern 40 is provided on an inner sliding surface 22 of the main bearing.
  • the texture pattern 40 comprises one texture element 42 which extends about the
  • the hydrodynamic sliding bearing member 20 may also be installed in a connecting rod 15, as shown in figs. 2e and 2f.
  • Fig. 2e shows a perspective view of a connecting rod comprising the hydrodynamic sliding bearing member according to an example embodiment of the present invention.
  • the texture pattern 40 is provided on both the inner surface 22 of the connecting rod big end 17 and the inner surface 22' of the connecting rod small end 16.
  • the texture pattern 40 may only be arranged on the connecting rod big end.
  • the texture pattern 40 may only be arranged on the connecting rod small end.
  • Fig. 2f schematically illustrates a cross sectional view of the example embodiment of the connecting rod in fig. 2e according to example embodiments of the present invention.
  • the axial width of the upper part and the lower part of the small end bearing are different, the upper part of the hydrodynamic sliding bearing member arranged on the connecting rod small end 16, which sits closest to the cylinder head is significantly less wide (refer to the axial dimension) compared to the lower part of said hydrodynamic sliding bearing member that sits closest to the crank shaft.
  • This reduction can be completed due to that it is the lower part of the hydrodynamic sliding bearing member that needs to cope with the combustion gas pressure resulting in a contact pressure acting on the lower part of the hydrodynamic sliding bearing member.
  • the upper part of the hydrodynamic sliding bearing member may only need to account for the contact pressure generated from inertia forces which are typically lower than the contact pressure resulting from the combustion phase.
  • the axial width of the hydrodynamic sliding bearing member is here designed according to the contact pressure. It is to be noted that if this would not have been the case as eg. the small end bearing would have a contact width this would mean that a certain part of the axial width of the upper area of the hydrodynamic sliding bearing member would be superfluous. Since friction loss is related to the area of the hydrodynamic sliding bearing member said superfluous area would generate additional friction compared to the hydrodynamic sliding bearing member having optimised axial width.
  • the texture pattern as described herein according to example embodiments offers the reduction in area, but also, the reduction of friction by using the texture pattern can be achieved much more efficient than merely reducing the area.
  • the hydrodynamic sliding bearing arrangement is formed by the inner surface 22 of the connecting rod big end 17, corresponding to the first sliding surface, and the outer surface 32 of the journal (shaft) of the crankshaft 18 (shown in e.g. fig. 2a), corresponding to the second sliding surface.
  • the first sliding bearing member 20 is a part of the connecting rod
  • the second sliding bearing member 30 is the crankshaft.
  • the hydrodynamic sliding bearing arrangement may be formed by the inner surface 22' of the connecting rod small end 16, corresponding to the first sliding surface, and an outer surface of a piston pin of the piston 19 (shown in e.g. fig. 2a), corresponding to the second sliding surface.
  • first sliding member 20' is here a part of the connecting rod, while the second sliding member is the piston pin.
  • the first sliding surface 22 or 22' of the first sliding member 20 or 20' is thus an inner
  • first sliding member 20 or 20' is configured to be centred around the second sliding member so that the inner circumferential surface is allowed to slide about the second sliding surface (the outer circumferential surface of the second sliding member), via a viscous fluid 60 upon rotation of the first sliding member 20 or 20' relative to the second sliding member 30 or 30'.
  • an internal combustion engine 100 for a vehicle comprising a hydrodynamic sliding bearing member 20 according to the example embodiments described herein, a journal shaft (crankshaft or piston pin)) and a connecting rod.
  • the connecting pin comprises a shaft extending between a connecting rod small end defining a piston pin opening for receiving the piston pin and a connecting rod big end defining a journal shaft opening for receiving the crankshaft journal.
  • the first sliding surface of the hydrodynamic sliding bearing member 20 is here an inner surface of the journal shaft opening and the second sliding surface is here a journal shaft surface (crankshaft outer surface).
  • the hydrodynamic sliding bearing member is configured for supporting a rotational motion between the connecting rod and the journal shaft (crankshaft).
  • first sliding surface of the hydrodynamic sliding bearing member may be an inner surface of the piston pin opening and the second sliding surface may be piston pin surface (piston pin outer surface).
  • the hydrodynamic sliding bearing member is configured for supporting a rotational motion between the connecting rod and the piston pin.
  • the hydrodynamic first sliding bearing member 20 is a separate part of the connecting rod, which is inserted into the connecting rod big end or the connecting rod small end.
  • the hydrodynamic first sliding bearing member may be attached to the connecting rod by a suitable process, as is well known in the art, so that the first sliding member essentially becomes an integral part of the connecting rod.
  • the hydrodynamic first sliding bearing member 20 forms a hydrodynamic sliding bearing arrangement 10 together with a part of the crankshaft, as mentioned above. That is, the crankshaft is here the second sliding bearing member having a second sliding bearing surface.
  • a connecting rod bearing comprising the hydrodynamic first sliding bearing member and a part of the crankshaft.
  • the hydrodynamic first sliding bearing member 20 forms a hydrodynamic sliding bearing arrangement 10 together with a part of the piston pin, as mentioned above. That is, the piston pin is here the second sliding bearing member having a second sliding bearing surface.
  • a connecting rod bearing comprising the hydrodynamic first sliding bearing member and a part of the piston pin.
  • a connecting rod bearing of an internal combustion engine 100 comprising a hydrodynamic first sliding bearing member 20 according to any one of the example embodiments described hereinafter.
  • the connecting rod bearing may for instance be installed into the connecting rod big end.
  • the connecting rod bearing may be installed into the connecting rod small end.
  • the hydrodynamic sliding bearing member may in some example embodiments be built into the object of use, e.g. the connecting rod.
  • This type of bearing configuration may sometime be denoted as an integral bearing.
  • Integral bearings are usually made from cast iron or hardened steel.
  • the term "integral” may refer to that the bearing configuration is a part of the shaft or part of the connecting rod.
  • an integral bearing may be less expensive but it cannot be replaced.
  • the hydrodynamic sliding bearing member may be provided in the form of a bushing, which is an independent bearing member that is inserted into a housing to provide the first sliding bearing surface.
  • Such constructions of bearing arrangement are well known in the art, and may include solid sleeve, split and clenched bushings.
  • the hydrodynamic sliding bearing member may in some example embodiments be a two-piece bearing member, also known as full bearings. This type of bearing arrangement is particularly useful as a main bearing for a crankshaft.
  • a two-piece hydrodynamic sliding bearing member comprises two halves.
  • a hydrodynamic sliding bearing arrangement comprising a hydrodynamic sliding bearing member having a first sliding surface, in which the hydrodynamic sliding bearing member (sometimes denoted as the first sliding bearing member) comprises an upper shell and a lower shell defining the first sliding surface. Further, the upper and lower shell may typically be arranged in a bearing housing. As is well known in the art, there are various systems used to keep the shells located. Thus this part of the construction is not further described herein.
  • the hydrodynamic sliding bearing arrangement may typically comprise the viscous fluid 60.
  • a thickness h of the viscous fluid 60 is between about 0.1 - 6 ⁇ , as defined by a distance between a non-textured surface area of the first sliding surface and a non-textured surface area of the second sliding surface.
  • thickness h of the viscous fluid 60 may also refer to the separating distance between the first member 20 and the second member 30.
  • the thickness may vary depending on the lubrication regime.
  • fig. 3 there is depicted a cross sectional view of an example embodiment of a hydrodynamic sliding bearing arrangement according to the present invention. Accordingly, it is to be noted that fig. 3 may represent a cross sectional view of any one of the example embodiments described above with reference to the main bearing, journal bearing, connecting rod, connecting rod bearing and/or the hydrodynamic sliding bearing arrangement. Fig. 3 shows a simple construction of the bearing
  • the first hydrodynamic sliding bearing member 20 having the first sliding bearing surface 22.
  • the first hydrodynamic sliding bearing member 20 is here formed by a part of journal shaft, e.g. the connecting rod 15 or the crankshaft.
  • the first hydrodynamic sliding bearing member 20 with the first sliding bearing surface 22 extends in the circumferential direction C and in the axial direction A.
  • the first sliding bearing surface 22 of the sliding bearing member 20 is configured for being slidably arranged in the circumferential direction C relative to a second sliding surface 32 of a second sliding member 30 via the viscous fluid 60.
  • the first sliding bearing surface 22 moves upon rotation in the circumferential direction C over a stationary surface on a thin fluid film (viscous fluid 60).
  • the direction of the rotation is illustrated by ⁇
  • the direction of the rotation as illustrated by ⁇ typically corresponds to the sliding direction as shown in Figs. 5a - 5i, i.e. a sliding motion along the
  • the moving surface first sliding bearing surface 22
  • the stationary surface second sliding surface 32
  • the hydrodynamic sliding bearing member 20 is permitted to operate under hydrodynamic lubrication.
  • the second hydrodynamic sliding bearing member 30 is permitted to operate under hydrodynamic lubrication.
  • the hydrodynamic sliding bearing arrangement 10 is permitted to operate under hydrodynamic lubrication.
  • hydrodynamic lubrication one surface floats over the other surface due to that a hydrodynamic film is formed by the geometry, the surface motion and the fluid viscosity which in combination contribute to an increase in the fluid pressure being sufficiently high to support the load. Further, the increased fluid pressure forces the surfaces apart and prevents surface contact.
  • the pressure in the oil film is maintained by (1 ) the rotation of the journal (e.g. the crankshaft) and (2) the hydrostatic pressure generated in the oil pump and fed to the bearing. It should be readily conceivable that the latter is not present in all types of hydrodynamic bearing arrangements. Instead the bearing may have splash lubrication / oil mist. To this end, the configuration is used to provide load support for a number of applications such as a rotating shaft, as mentioned above.
  • first sliding surface may alternatively be defined by the journal shaft, while the second sliding surface 32 may be defined by the inner surface of the first sliding member, e.g. the connecting rod or the crankshaft depending on the installation of the configuration.
  • the first sliding surface 22 has opposite boundaries 26, 28 (not shown in fig. 3), as seen in the axial direction A, and a texture pattern 40 (not shown in fig. 3).
  • the texture pattern here comprises a plurality of texture elements 42.
  • the texture pattern in some example embodiments comprises at least one texture element.
  • One example of a texture pattern comprising one texture element is described in relation to fig. 2g.
  • the positioning and/or the geometry of the texture pattern and the texture elements in the hydrodynamic lubrication regime may not be the same as in the boundary and/or mixed lubrication regime.
  • this type of pattern and/or elements would likely contribute to an increase in friction and possibly cause the system to seizure.
  • the fluid film thickness can be considered to be the same as the texture element depth, because the contact between first sliding surface and the second sliding surface is near or fully- flooded.
  • the increase in metal to metal contact for the textured surfaces is understood to be due to a decrease in the build-up of hydrodynamic pressure. There are two causes for loss of hydrodynamic pressure: (1 ) because of leakage of fluid into the texture element; and (2) because less surface area is available for the generation of hydrodynamic pressure.
  • the following illustrative example may be used to further describe the correlation between the disclosed techniques of texture pattern, as described in relation to figs. 4a - 4i, 5a - 5i, and 6a - 6b, and the effect of reducing friction losses in the hydrodynamic lubrication regime.
  • the phenomena of decreasing viscous losses in tribological contact that encompass surface textures are related to the correlation between separation (distance) of mating surfaces and the generation of hydrodynamic pressure. This will be further described by means of an example to a surface having a texturing area density of 50 %, which means that 50 % of the surface area will consist of textures, while the remaining 50 % will be the area between the textures, herein referred as the plateau area or non- textured area. Further, in this example, it is assumed that the exemplified tribological contacts operate in the hydrodynamic lubrication regime, meaning that surfaces are separated by the viscous fluid essentially at all times and no occurrence of material-to- material contact.
  • the film thickness is here one of the key parameters (sliding velocity and viscosity are generally considered as the other two key parameters for determining the operating characteristics of tribological contacts) for determining the frictional response in the hydrodynamic lubrication regime.
  • the film thickness commonly denoted with h, is regarded as inversely proportional to shear (friction) force.
  • the hydrodynamic pressure (lift) generated from the textures and also the friction (drag) from the textures will be insignificant, due to that the film thickness separating the surfaces can be regarded as infinite within the texture. If the contribution of hydrodynamic pressure (lift) and friction (drag) are zero, it may be concluded that for the example with the surface having an area density of texturing of 50 %, it is believed that 50 % of the friction would be removed from the textured area, while the area of the plateau areas would have to carry twice the amount of fluid film pressure. If this doubling of fluid film pressure would generate a doubling of friction for the plateau area surface, the total friction for the textured surface in this example would be the same as for a smooth surface. However, it has been found that this is not applicable for the example, rather it has been concluded that textures that encompass correct dimensioning may be used to decrease friction in the hydrodynamic lubrication regime, as further described hereinafter.
  • the purpose of the exemplary embodiments as described herein is to decrease the friction losses in mechanical contacts.
  • the purpose of the texture pattern can be described as optimising the area of a supporting surface in a mechanical design. In practice, this means removing the surface when it is not needed to generate the required supporting function, for this type of circumstances the redundant surface generates increased friction losses.
  • texture elements decrease the plateau-to-plateau film thickness, it may not be beneficial to add a texture element on a part of a component for which the separating film thickness is low, e.g. a position of a bearing that experiences high or severe contact load, low sliding speed, low viscosity (in this case equals to high temperature) or increase or decrease of any other parameter that may increase the contact severity.
  • a texture element on a part of a component for which the separating film thickness is low, e.g. a position of a bearing that experiences high or severe contact load, low sliding speed, low viscosity (in this case equals to high temperature) or increase or decrease of any other parameter that may increase the contact severity.
  • a texture element on a part of a component for which the separating film thickness is low, e.g. a position of a bearing that experiences high or severe contact load, low sliding speed, low viscosity (in this case equals to high temperature) or increase or decrease of any other parameter that may increase the contact severity.
  • the example embodiments of the invention provides the technical effect of providing a hydrodynamic sliding bearing member which is capable of further reducing frictional losses in the hydrodynamic lubrication regime.
  • the inventor has recognized that a significant part of the total friction losses in an internal combustion engine and its components are
  • one example advantage with the example embodiments of the invention is to provide a first sliding surface with a texture pattern having at least one texture element shape, as described in relation to figs. 5a to 5i, which is capable of increasing the hydrodynamic pressure generation.
  • This type of texture element shape has a trailing region defined by a trailing surface extending from the first sliding surface to a bottom surface of the texture element.
  • a first section of the trailing surface is adapted to define a converging gap with a sliding surface of a second sliding member and extends a distance from the first sliding surface in a radial direction, which is smaller than 50% of the texture element depth.
  • the following description with reference to the example embodiments shown in figs. 4a - 4i and 6a - 6b will provide some examples on how the texture element may be arranged in a texture pattern on the first sliding surface (and/or the second sliding surface) to allow for an even further decrease in hydrodynamic friction.
  • the texture pattern facilitates a global increase in the fluid film between the sliding surfaces of the bearing member (or bearing arrangement) at the locations of the texture elements in order to minimize hydrodynamic (viscous) friction losses.
  • the term "global” typically refers to an increase in oil film thickness between textures and plateau of opposing surface and oil film thickness between the plateaus of the two surfaces, i.e. it takes into account bot the contact within and outside the texture elements. For positions in which texture elements are introduced, the fluid film between the plateaus of the two surfaces might decrease.
  • Figs. 4a to 4i schematically illustrate various example embodiments of a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction and in an axial direction, in which the first sliding surface has a texture pattern comprising a plurality of texture elements according to the invention.
  • textured pattern is expressly defined for purposes of the present invention as a regular, repeated pattern of distinct elements (typically in the form of depressions) such as depressions in the form of closed voids or grooves in surface 22, the substantial remainder of the surface 22 being defined by what shall be referred to here as one or more plateaus 46.
  • Other, more irregular and generally more microscopic depressions may define other, more irregular and generally more microscopic plateaus as is well known in the art, however, depressions and plateaus of that type are not of substantial interest with respect to this aspect of the present invention.
  • the textured pattern 40 can be provided in any suitable way.
  • the texture elements are machined by a suitable method, such as by being machined via a milling, turning, or drilling operation, via chemical etching, water-jet cutting, abrasive blasting, or hydro- erosive grinding, or some combination of such operations.
  • each of the plateau areas of the first sliding surface of the hydrodynamic sliding bearing member may be provided with a machined roughness.
  • the machined roughness may extend essentially along the entire axial length of the first sliding surface.
  • the machined roughness may for instance refer to arithmetical mean roughness or other parameters as defined in ISO 4287:1997 and similar standards.
  • FIG. 4a there is depicted an example embodiment of a
  • the hydrodynamic sliding bearing member 20 has a first sliding surface 22 extending in a circumferential direction C and in an axial direction A.
  • the first sliding bearing member is illustrated in a plane view (corresponding to the plane A-C) although the circumferential direction C refers to the circumference of the first sliding member.
  • the first sliding surface here has a length L A in the axial direction A and a length L c in the circumferential direction C.
  • the first sliding member 20 typically has a circular cross sectional shape as seen in a plane perpendicular to the axial direction A, and illustrated in e.g. fig. 3, it is also readily understood that the length L c of the first sliding bearing member 20 in the circumferential direction C typically corresponds to the circumference of the first sliding bearing member as seen in the circumferential direction C.
  • the length L c of the first sliding bearing member 20 in the circumferential direction C may be defined by a closed circle of 360 degrees.
  • the first sliding member 20, as shown in fig. 4a and figs. 4b - 4i extends from -180 degrees to 180 degrees (as seen in the circumferential direction).
  • the first sliding bearing member 20 also has a centre region defined by the centre line T.
  • the first sliding bearing member 20 may have an outer region 24, and an intermediate region in-between the centre region and the outer region, as seen in the axial direction A.
  • the centre region in this example embodiment, and in other example embodiments herein, is illustrated by the centre line T
  • the centre region may in some examples correspond to a region of about 5 - 10 % of the length L A , as seen in the axial direction A.
  • the outer region 24 may in some examples correspond to a region of about 0.1 - 10 % of the length L A , as seen in the axial direction A.
  • the extension of the outer region may be between 0.1 - 5 % of the total axial length of the first sliding surface 22.
  • the hydrodynamic sliding bearing member 20 is configured for being slidably arranged in the circumferential direction C relative to the second sliding surface 32 of a second sliding member 30 (not shown in fig. 4a) via a viscous fluid 60 to permit the hydrodynamic sliding bearing member (or bearing arrangement) to operate under hydrodynamic lubrication. That is, the first sliding surface 22 of the hydrodynamic sliding bearing member 20 is configured for being slidably arranged in the circumferential direction C relative to a second sliding surface 32 of a second sliding member 30 via a viscous fluid 60 to permit the hydrodynamic sliding bearing arrangement to operate under hydrodynamic lubrication.
  • the first sliding surface 22 has opposite boundaries 26, 28, as seen in the axial direction A, and a texture pattern 40 comprising a plurality of texture elements 42.
  • the opposite boundaries 26, 28 extend along the circumferential direction, respectively.
  • an area density of the texture element(s) 42 decreases towards an axial boundary 26, 28, as seen from a centre of the first sliding surface 22 in the axial direction A. That is, the texture elements are distributed so that the area density is regarded as decreasing towards each boundary.
  • the centre of the first sliding surface here refers to the centre line T.
  • the area density of the texture element(s) 42 is uniformly distributed across the sliding surface 22, as illustrated in fig. 4c. That is, the texture elements are distributed so that the area density is maintained at a constant level towards each boundary.
  • the texture pattern is in this example embodiment distributed across essentially the entire length L A and the length L c .
  • the area density of the texture elements can be decreased in several different ways. In some example embodiments, e.g. as shown in fig.
  • the area density of the texture elements 42 decreases towards the axial boundaries
  • the area density of the texture elements 42 may decrease towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A, by only decreasing the axial length E A of each texture element per unit area towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the area density of the texture elements 42 may decrease towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A, by only decreasing the circumferential length E c of each texture element per unit area towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • each texture element may vary depending on the size, installation and use of the first sliding bearing member.
  • the axial length E A of the texture elements is typically at least above 300 ⁇ .
  • the circumferential length E c of the texture elements is typically at least above 300 ⁇ .
  • the axial length E A of the texture elements is between about 300-
  • the circumferential length E c of the texture elements is between about 300 - 10 000 ⁇ .
  • the axial length E A of the texture elements may decrease linearly from 10 000 ⁇ to 300 ⁇ , as seen from the centre of the first sliding surface to an outer boundary 26, 28.
  • the axial length E A of the texture elements may decrease non-linearly from 10 000 ⁇ to 300 ⁇ , as seen from the centre of the first sliding surface to an outer boundary 26, 28.
  • the axial length E A of the texture elements may decrease linearly from 10 000 ⁇ to 1 000 ⁇ , as seen from the centre of the first sliding surface to an outer boundary.
  • the axial length E A of the texture elements may decrease non-linearly from 10 000 ⁇ to 1 000 ⁇ , as seen from the centre of the first sliding surface to an outer boundary.
  • the circumferential length E c of the texture elements for a given circumferential segment D (extending along the circumferential direction C) at a given axial distance from the centre of the first sliding surface is kept constant along the entire length L c (the extension of the first sliding surface in the circumferential direction C).
  • the circumferential length Ec of the texture elements for a given circumferential segment D (extending along the circumferential direction C) at a given axial distance from the centre of the first sliding surface is varied along the length L c .
  • a plurality of the texture elements of the texture pattern may typically, although not strictly necessary, be arranged in succession in a given area along the axial direction A.
  • a plurality of the texture elements of the texture pattern may typically, although not strictly necessary, be further arranged in succession in a given area along the circumferential direction C.
  • a plurality of the texture elements of the texture pattern are arranged in a grid pattern extending in succession along the axial direction A and the circumferential direction C.
  • the distances between the texture elements in the axial direction A and the circumferential direction C may vary according to various conditions of the hydrodynamic sliding bearing member, and are typically selected in view of the shape, geometry, effect, and installation of the member. As an example, however, the texture elements are here spaced from one another along the axial direction A by at least 100 ⁇ . In addition, or alternatively, the texture elements are here spaced from one another along the circumferential direction C by at least 100 ⁇ . However, if the texture elements are in the form of squares (quadratic or rectangular), as seen in the axial and the circumferential directions, the distance between the texture elements may even be less than 100 ⁇ .
  • the texture pattern 40 here comprises a set of axial rows of texture elements 47 A - 47 N arranged in succession along the circumferential direction C, as shown in fig. 5a, which is a detailed view of e.g. the example embodiment in fig. 4a.
  • the texture elements 42 of at least one axial row 47b are offset from the texture elements of another axial row 47a as seen in the axial direction A so that a circumferential segment D of the first sliding surface 22 intersects at least one texture element in a substantial part of the first sliding surface.
  • the texture elements 42 are here arranged in succession in axial rows 47 A - 47 N along the circumferential direction C. Further, the texture elements 42 of at least one axial row, e.g. the axial row 47 b , are offset from the texture elements of another axial row, e.g. the axial row 47 a , as seen in the axial direction A so that a circumferential segment D of the first sliding surface 22 intersects at least one texture element in a substantial part of the first sliding surface. In this manner, the texture elements are arranged so that wear particles transported along the circumferential direction, due to the sliding direction of the hydrodynamic sliding bearing member, would be entrapped by at least one texture element independently on the path of the particle across the axial direction A.
  • every second axial row 47 B is offset with an equal distance from an adjacent axial row 47 A, 47 c .
  • the texturing may also be oriented in an angled manner, although not shown in the figures.
  • the texture pattern 40 may comprise a set of axial rows of texture elements 47 A - 47 N arranged in succession along the circumferential direction C, wherein each axial row of the texture elements of the set of axial rows of texture elements 47 A - 47 N is inclined with respect to a line parallel to the axial direction A.
  • each axial row of the texture elements may be inclined by 70 degrees with respect to a line parallel to the axial direction A.
  • the angle of inclination may vary depending on dimensions, installation and application. In some example embodiment, the angle of inclination may be between 5 - 80 degrees. Still preferably, in some example embodiment, the angle of inclination may be between 50 - 70 degrees.
  • the texturing may also consist of continuous grooves with its longest length extending in the axial or the circumferential direction.
  • the texture element is a groove extending along the entire circumferential direction, as shown in fig. 4g or fig. 4h.
  • the texture element in the form of a groove may only extend over a substantial length of the length of the sliding surface in the circumferential direction.
  • fig. 4g schematically illustrates another example embodiment of a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction C and in an axial direction A, in which the first sliding surface 20 has a texture pattern 40 comprising a plurality of texture elements according to example embodiments.
  • This example embodiment is similar to the example embodiment as described in relation to fig. 4a besides that the texture elements 42 are provided in the form of grooves extending along the entire circumferential direction C.
  • the texture elements are inclined with respect to the centre T.
  • the texture pattern in this example embodiment extends essentially along the entire axial direction A and the entire circumferential direction C.
  • the area density of the texture elements 42 decreases by decreasing the axial length E A of each texture element per unit area towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the circumferential length E c essentially corresponds to the length of the sliding surface 22.
  • the area density of the texture elements 42 decreases by decreasing the quantity of texture elements towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A. As shown in fig. 4g, this further means that the distance E D between two adjacent texture elements increases as seen from the centre of the first sliding surface 22 in the axial direction A. It should be readily appreciated that the area density of the texture elements 42 may in some examples only decrease by decreasing the quantity of texture elements towards the axial boundaries 26, 28 or by decreasing the axial length E A of each texture element per unit area towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the area density of the texture elements 42 may decrease towards only the axial boundary 26, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the other half of the first sliding surface is free from texture pattern (texture elements), i.e. the half of the surface defined by the region between the centre region T and the axial boundary 28.
  • the texture elements are provided in the form of grooves, each groove extending a substantial length in the circumferential direction of the first sliding surface.
  • substantial length may refer to 30 - 100 % of the entire length of the first sliding surface in the circumferential direction.
  • substantial length may refer to 50 - 90 % of the entire length of the first sliding surface in the circumferential direction
  • each texture element is inclined with respect to the centre T of the circumferential direction of the first sliding surface.
  • the example embodiment in fig. 4g may incorporate any one of the features and/or effects as mentioned in relation to fig. 4a.
  • Fig. 4h schematically illustrates another example embodiment of a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction C and in an axial direction A, in which the first sliding surface 20 has a texture pattern 40 comprising a plurality of texture elements according to example embodiments.
  • This example embodiment is similar to the example embodiment as described in relation to fig. 4g besides that the texture elements 42 are provided in the form of two set of grooves extending along the entire circumferential direction C.
  • Each set of the texture elements are inclined with respect to the centre T.
  • each set of texture elements are arranged so that the texture elements from the first set of texture elements intersect the texture elements from the second set of the texture elements.
  • the texture pattern in this example embodiment extends essentially along the entire axial direction A and the entire circumferential direction C.
  • the area density of the texture elements 42 decreases by decreasing the axial length E A of each texture element per unit area towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the circumferential length E c essentially corresponds to the length of the sliding surface 22.
  • the area density of the texture elements 42 decreases by decreasing the quantity of texture elements towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A. As shown in fig. 4g, this further means that the distance E D between two adjacent texture elements in the same set of texture elements increases as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the area density of the texture elements 42 may decrease towards only the axial boundaries 26, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the other half of the first sliding surface is free from texture pattern (texture elements), i.e. the half of the surface defined by the region between the centre region T and the axial boundary 28.
  • the example embodiment in fig. 4h may incorporate any one of the features and/or effects as mentioned in relation to fig. 4a and fig. 4g.
  • the area density may vary along the circumferential direction C.
  • the area density may be lower in some regions than in other regions as seen along the circumferential direction C.
  • the texture element is provided in the form of a texture element extending in circular manner about the circumferential direction C and along the axial direction A. That is, the texture element 42 is here an elongated continuous groove extending about the circumferential direction C and along the axial direction A as a spiral. In this manner, the length of the texture element can be greatly bigger than the circumferential length of the hydrodynamic sliding bearing member 20.
  • One advantage with this type of texture element is that the texture pattern becomes less complicated to produce on the sliding surface 22.
  • a hydrodynamic sliding bearing member 20 having a first sliding surface 22 extending in a circumferential direction C and in an axial direction A.
  • the sliding bearing member 20 is configured for being slidably arranged in the circumferential direction C relative to a second sliding surface of a second sliding member (although not shown in fig. 2g and fig. 4i) via a viscous fluid to permit the hydrodynamic sliding bearing member 20 to operate under hydrodynamic lubrication.
  • the first sliding surface 22 has opposite boundaries 26, 28, as seen in the axial direction A.
  • the texture pattern 40 here comprises one texture element 42, wherein an area density of the texture element 42 decreases towards the axial boundaries 26, 28, as seen from a centre of the first sliding surface 22 in the axial direction A.
  • the texture element here resembles a helix or spiral, i.e. a curve in the tree-dimensional space, extending around the circumferential length of the sliding surface 22 and towards the axial boundaries 26, 28.
  • the spiral-shaped texture element is shown in fig. 4i, which shows the first sliding surface in an unfolded
  • the texture pattern including one texture element here resembles the texture pattern in fig. 4g, although it should be understood that the texture element is in this example embodiment one single continuous groove.
  • the texture element is here illustrated as a straight groove on a plane (surface 22), and when that plane is wrapped around a cylindrical surface of any kind, especially a right circular cylinder, the texture element resembles the shape of a curve of a screw, as shown in fig. 2g.
  • hydrodynamic sliding bearing member 20 as e.g. described above, wherein the texture element 42 is an elongated continuous groove extending about the circumferential direction C and along the axial direction A as a spiral.
  • the groove typically has a number of revolutions, with the distance between them increasing as the groove approaches the axial boundary.
  • the area density of the texture elements 42 decreases by linearly or non-linearly increasing the angle of the inclination of the texture element.
  • the angle of inclination may sometimes also be denoted the pitch of the texture element, i.e. the width of one complete turn of the texture element around the circumferential direction.
  • the distance E D between two points of texture elements at a given circumferential length increases along the axial direction A, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • An advantage of this arrangement is that the possibility of entrapment of wear particles is significantly improved since there is no path that is not obstructed by a texture element for the particles to travel a significant distance in the circumferential direction of the first sliding surface. In other words, there is a least one texture element to entrap the wear particle independently on the current travelling path of the wear particles across the axial direction. Thus, it becomes possible to further increase the efficiency of entrapping wear particles.
  • the example embodiment in fig. 4i may incorporate any one of the features and/or effects as mentioned in relation to fig. 4a.
  • the depth of the texture elements forming the textured pattern also decreases towards at least one of the axial boundaries, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the depth of the texture elements forming the textured pattern may be kept constant along the axial direction A.
  • the depth of the texture elements is further described and illustrated in figs. 6a and 6b hereinafter.
  • Figs. 6a and 6b illustrate a cross sectional view along the cross section Q-Q in e.g. fig. 4f, and as seen in the axial direction A and the radial direction R.
  • the texture pattern extends essentially along the entire axial direction A and the circumferential direction C of the hydrodynamic sliding bearing member 20. That is, the texture elements of the texture pattern are distributed essentially along the entire first sliding surface 22. In this manner, the effects of the texture pattern as described above can be utilized to decrease hydrodynamic frictions losses over essentially the entire first sliding surface 22.
  • the distribution of the texture pattern can be limited to the main regions of the first sliding surface, i.e. the centre region and an intermediate region (i.e. the intermediate region refers to a region located between the centre region and an outer region).
  • a first sliding surface 22 wherein an outer region 24 of the first sliding surface 22 adjacent an axial boundary 26, 28 is free from texture elements.
  • the outer region 24 refers to a region extending along the circumferential direction C, an in the axial direction A.
  • the outer region is arranged adjacent the axial boundary 26.
  • the outer region is arranged adjacent the axial boundary 28.
  • a distance or region of zero texture elements around the axial boundary may counteract the leakage in an efficient manner.
  • the extension of the outer region may be between 0.1 - 10 % of the total axial length of the sliding surface 22. Still preferably, the extension of the outer region may be between 0.1 - 5 % of the total axial length of the sliding surface 22.
  • FIG. 4b schematically illustrates another example embodiment of a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction and in an axial direction, in which the first sliding surface has a texture pattern comprising a plurality of texture elements according example embodiments.
  • This example embodiment is similar to the example embodiment as described in relation to fig. 4a besides that the distribution of the texture pattern 40 is limited along the circumferential direction C.
  • the texture pattern in this example embodiment extends essentially along the entire axial direction A, but only a part in the circumferential direction C of the hydrodynamic sliding bearing member 20. That is, the texture elements of the texture pattern are distributed essentially along the entire first sliding surface 22, while the texture elements of the texture pattern are distributed essentially between - 60 degrees to 60 degrees along the circumferential direction C of the first sliding surface 22.
  • the first sliding surface 22 is free from texture element in a region that amounts to 120 degrees of the extension of the first sliding surface, which typically corresponds to 30 - 35 % of the first sliding surface, as seen in the circumferential direction C.
  • the hydrodynamic sliding bearing member is configured to provide a region that better withstands points of high contact pressure since the first sliding surface has an area of no texture pattern, thus allowing the surface to distribute the force at this non-textured area of the first sliding surface.
  • the first sliding surface is configured according to contact pressure.
  • the example embodiment in fig. 4b may incorporate any one of the features and/or effects as mentioned in relation to fig. 4a.
  • Fig. 4c schematically illustrates another example embodiment of a hydrodynamic sliding bearing member having a first sliding surface 22 extending in a circumferential direction C and in an axial direction A, in which the first sliding surface has a texture pattern 40 comprising a plurality of texture elements 42 according to example
  • This example embodiment is similar to the example embodiment as described in relation to fig. 4a and fig. 4b besides that the distribution of the texture pattern 40 is uniformly distributed across the first sliding surface 22, i.e. along the axial direction A and the circumferential direction C.
  • a hydrodynamic sliding bearing member 20 wherein the texture pattern 40 comprises a plurality of texture elements 42 being uniformly distributed across the first sliding surface 22.
  • the texture elements are spaced apart from each other with a constant distance and that the sizes of the texture elements (axial length and circumferential length) are kept constant along the axial direction and the circumferential direction.
  • the texture pattern in this example embodiment extends over the entire surface 22 as seen in the entire axial direction A and in the circumferential direction C of the hydrodynamic sliding bearing member 20.
  • the texture elements of the texture pattern may be distributed essentially between - 60 degrees to 60 degrees along the circumferential direction C of the first sliding surface 22. Accordingly, the first sliding surface 22 may be free from texture element in a region that amounts to 120 degrees of the extension of the first sliding surface, which typically corresponds to 30 - 35 % of the first sliding surface, as seen in the circumferential direction C.
  • the first sliding surface is provided with a uniformly distributed texture pattern on at least a substantial part of the first sliding surface, as further described herein in relation to fig. 4a.
  • the texture pattern may be arranged essentially along the entire extension of the surface as seen in the
  • the example embodiment in fig. 4c may incorporate any one of the features and/or effects as mentioned in relation to fig. 4a, and/or in fig. 4b.
  • the area density of the texture elements 42 decreases towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A, by decreasing the quantity of texture elements towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the area density of the texture elements decreases towards both of the axial boundaries, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • fig. 4d schematically illustrates a hydrodynamic sliding bearing member 20 having a first sliding surface 22 extending in the circumferential direction C and in the axial direction A, in which the first sliding surface has a texture pattern comprising a plurality of texture elements according to example embodiments.
  • This example embodiment is essentially similar to the example embodiment as described in relation to fig. 4a besides that area density of the texture elements 42 decreases by decreasing the quantity of texture elements towards the axial boundaries 26, 28, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the area density of the texture elements 42 decreases towards only the axial boundaries 26, as seen from the centre of the first sliding surface 22 in the axial direction A by decreasing the quantity of texture elements towards only the axial boundaries 26, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the other half of the first sliding surface is free from texture pattern (texture elements), i.e. the half of the surface defined by the region between the centre region T and the axial boundary 28.
  • the size and shape of the texture elements are here essentially kept constant across the axial direction A and the circumferential direction C, except for the area in the centre of the sliding surface which is zero degrees in said figure. However, the size and shape may vary across any one of the axial direction A and the circumferential direction C.
  • the example embodiment in fig. 4d may incorporate any one of the features and/or effects as mentioned in relation to fig. 4a.
  • the texture pattern may optimally, although not strictly required, comprise a set of axial rows of texture elements 47 A - 47 N arranged in succession along the circumferential direction C. Further, as illustrated, the texture elements 42 of at least one axial row 47b are offset from the texture elements of another axial row 47a as seen in the axial direction A so that a circumferential segment D of the first sliding surface 22 intersects at least one texture element in a substantial part of the first sliding surface.
  • Fig. 4e schematically illustrates another example embodiment of a hydrodynamic sliding bearing member having a first sliding surface extending in a circumferential direction and in an axial direction, in which the first sliding surface has a texture pattern comprising a plurality of texture elements according to example embodiments.
  • This example embodiment is similar to the example embodiment as described in relation to fig. 4d besides that the distribution of the texture pattern 40 is limited along the circumferential direction C.
  • the texture pattern in this example embodiment extends essentially along the entire axial direction A, but only a part in the circumferential direction C of the hydrodynamic sliding bearing member 20. That is, the texture elements of the texture pattern are distributed essentially along the entire first sliding surface 22, while the texture elements of the texture pattern are distributed essentially between - 60 degrees to 60 degrees along the circumferential direction C of the first sliding surface 22.
  • the first sliding surface 22 is free from texture element in a region that amounts to 120 degrees of the extension of the first sliding surface, which typically corresponds to 30 - 35 % of the first sliding surface, as seen in the circumferential direction C.
  • the hydrodynamic sliding bearing member is configured to provide a region that better withstands points of high severity, e.g. high contact pressure since the first sliding surface has an area of no texture pattern, thus allowing the surface to distribute the force at this non-textured area of the first sliding surface.
  • the first sliding surface may be better configured according to contact pressure.
  • the example embodiment in fig. 4e may incorporate any one of the features and/or effects as mentioned in relation to fig. 4d, and/or fig. 4a.
  • Fig. 4f schematically illustrates another example embodiment of a hydrodynamic sliding bearing member having a first sliding surface extending in the circumferential direction and in the axial direction, in which the first sliding surface has a texture pattern comprising a plurality of texture elements according to example embodiments.
  • This example embodiment is essentially a combination of the texture pattern in the example embodiment in fig. 4a and the example embodiment in fig. 4d. In other words, as shown in fig.
  • the example embodiment in fig. 4f may incorporate any one of the features and/or effects as mentioned in relation to fig. 4a and/or fig. 4d.
  • the example embodiments of the hydrodynamic sliding bearing member may be installed in any one of constructions described above. That is, the hydrodynamic sliding bearing member may be a part of a journal bearing, a main bearing, a connecting rod, a connecting rod bearing, a hydrodynamic sliding bearing arrangement or the like.
  • the hydrodynamic sliding bearing member 20 may contribute to any one of the functions and the advantages as described with respect to the example embodiment in figs. 1 to 3.
  • the area density of the texture elements 42 decreases towards the axial boundary 26, as seen from the centre of the first sliding surface 22 in the axial direction A, for instance by decreasing the axial length E A and the circumferential length E c of each texture element per unit area towards the axial boundary 26, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the circumferential length E c of the texture elements for a given circumferential segment D (extending along the circumferential direction C) at a given axial distance from the centre of the first sliding surface is kept constant along the entire length L c (the extension of the first sliding surface in the circumferential direction C).
  • the circumferential length E c of the texture elements for a given circumferential segment D (extending along the circumferential direction C) at a given axial distance from the centre of the first sliding surface is varied along the length L c .
  • fig. 5a shows an example of a texture pattern 40, which here comprises a set of axial rows of texture elements 47 A - 47 N arranged in succession along the circumferential direction C. Further, the texture elements 42 of every second axial row 47b, 47d etc. are offset from the texture elements of the axial row 47a, as seen in the axial direction A.
  • a circumferential segment D of the first sliding surface 22 intersects at least one texture element in a substantial part of the first sliding surface.
  • a circumferential segment D refers to a segment of the first sliding surface extending essentially along the entire circumferential direction C.
  • the term "substantial" here typically refers to the entire area or the first sliding surface. That is, the term substantial may refer to 100 % of the first sliding surface.
  • the term substantial typically refers to the entire area or the first sliding surface. That is, the term substantial may refer to 100 % of the first sliding surface.
  • the term substantial typically refers to 100 % of the first sliding surface.
  • the term substantial
  • substantially may refer to the area of the first sliding surface besides the outer region 24 of the first sliding surface. That is, the term substantial may here refer to 95 - 100 % of the first sliding surface.
  • the sliding surface comprises a texture pattern
  • non-textured area may typically be provided in the form of an essentially smooth surface area.
  • An area between two adjacent texture elements forms a plateau area 46.
  • the area of the plateau area is between about 20-95 percent of a total area of the first sliding surface.
  • a textured area of the texture pattern may be between about 5-80 percent of a total area of the first sliding surface.
  • the textured area of the texture pattern is between about 20-50 percent of a total area of the first sliding surface
  • figs. 6a to 6b depict cross sectional views of various example embodiments of an inner first sliding surface of a hydrodynamic sliding bearing member according to any one of the example embodiments described above.
  • figs. 6a and 6b may reflect a cross sectional view along the cross section Q-Q in e.g. fig. 4f, as seen in the axial direction A and the radial direction R.
  • the depth of a texture element is here denoted by the reference E R , since the depth typically refers to the extension of the texture element 42 in the radial direction of the first sliding bearing member 22.
  • hydrodynamic friction may further be efficiently reduced by decreasing both the area density and the texture depth as seen from the centre of the first sliding surface 22. This is shown in fig. 6a, in which a depth E R of the texture elements 42 forming the textured pattern 40 decreases towards at least one of the axial boundaries, as seen from the centre of the first sliding surface 22 in the axial direction A.
  • the depth of the texture elements forming the textured pattern decreases towards at least one of the axial boundaries, it becomes possible to further reduce the risk of having fluid leakage at the axial boundary. This is due to that an increased depth will increase the leakage at the axial boundary, thus decreasing the hydrodynamic pressure and thus increasing friction.
  • the depth of the texture elements and the relationship between a texture element at the centre of the first sliding surface and a texture element at the axial boundary is typically selected in view of the dimensions and shapes of the sliding bearing member and the texture elements as well as type of texture pattern.
  • the texture elements should be sufficiently deep so that the viscous film shear force within the texture elements is negligible, texture boundary effects excluded.
  • Negligible viscous film shear force is here defined as that the viscous film shear force in texture elements, texture boundary effects not included, should be less than 5 % compared to the viscous film shear force acting between the plateaus of the two surfaces.
  • the depth of the texture elements should typically be above 10 ⁇ . However, a depth of the texture elements may ordinarily be between substantially 20-200 ⁇ . In some example embodiments, a minimum depth of the texture elements may be substantially equal to 35 ⁇ . While it is presently believed that providing texture elements or depressions with depths less than 35 ⁇ , such as around 20 ⁇ , may, in some circumstances provide beneficial results, in some circumstances textures or depressions with depths around 30 ⁇ may actually increase friction, and it is presently believed that texture elements or depressions of at least 35 ⁇ and, likely, substantially greater than 35 ⁇ will provide most beneficial results.
  • the hydrodynamic sliding bearing member comprises a texture pattern having a plurality of the texture elements, wherein the depth of the texture elements is varied from 200 ⁇ at the centre of the first sliding surface 22, as seen in the axial direction A, to 20 ⁇ at the axial boundary of the first sliding surface.
  • the example embodiments of the hydrodynamic sliding bearing member may be installed in any one of constructions described above. That is, the hydrodynamic sliding bearing member may be a part of a journal bearing, a main bearing, a connecting rod, a connecting rod bearing, a
  • hydrodynamic sliding bearing member 20 may contribute to the functions and the advantages as described with respect to the example embodiment in figs. 1 to 3.
  • the hydrodynamic first sliding member is arranged on the shaft, i.e. the inner sliding member of the hydrodynamic sliding bearing arrangement.
  • the texture pattern 40 comprising the plurality of texture elements may be arranged on the journal shaft or the like. That is, the texture pattern 40 comprising the plurality of texture elements may be arranged on the outer circumferential surface of the journal shaft, which is arranged inside of the inner circumferential surface of the other bearing member.
  • the first sliding surface 22 of the first sliding member 20 may refer to an outer circumferential surface arranged within a second sliding member.
  • the outer circumferential surface here first sliding surface 22
  • the inner circumferential surface the second sliding surface of the second sliding member
  • the texture patter 40 may be arranged on both the first sliding member 20 and the second sliding member 30.
  • This type of example embodiment may include any one of the features and functions as described above in relation to the figures.
  • a bearing arrangement may be provided which includes a first sliding member 20 having a texture pattern according to the example embodiments as described herein and a second sliding member 30 having a texture pattern according to the example embodiments as described herein.
  • the by the provision "upon rotation of the first sliding member 20 relative to the second sliding member 30" may refer to that the first sliding member rotates, while the second sliding member is stationary.
  • the provision “upon rotation of the first sliding member 20 relative to the second sliding member 30" may refer to that the first sliding member is stationary, while the second sliding member rotates.
  • the provision “upon rotation of the first sliding member 20 relative to the second sliding member 30" may refer to that the first sliding member rotates and the second sliding member rotates.
  • a further benefit of providing the textured pattern according to the example embodiments herein is that wear on the surfaces 22 and 32 can be reduced because debris can be retained in the textured pattern (texture elements).
  • the surface texturing of the surface(s) could, however, in some circumstances, increase the wear levels due to the fact that there will be less fluid film (and probably more mechanical contact) separating the surfaces. However, it is also possible that the wear levels could decrease.
  • a significant wear mechanism for components as mentioned and described herein is three- body-abrasion. It is expected that sufficiently deep elements, as mentioned herein, could trap wear particles and decrease wear of the surfaces 22 and 32.
  • the sliding direction S here refers to the rotational direction of the second sliding bearing member 30 typically being arranged inside the circumference of the hydrodynamic (first) sliding bearing member 20.
  • the second sliding bearing member 30 is typically configured to rotate inside the hydrodynamic (first) sliding bearing member 20.
  • hydrodynamic sliding bearing member 20 is in these example embodiments considered essentially stationary, while the second sliding bearing member 30 slides in the sliding direction S inside the hydrodynamic (first) sliding bearing member 20, thus the hydrodynamic (first) sliding bearing member 20 is slidably arranged relative the second sliding bearing member 30.
  • the sliding direction S thus here corresponds to the circumferential direction C. That is, the sliding direction S here refers to the rotational direction of the second sliding bearing member 30.
  • the second sliding bearing member 30 is arranged inside the circumference of the hydrodynamic (first) sliding bearing member 20.
  • the sliding direction S here refers to the rotational direction of the second sliding bearing member 30, said second sliding bearing member 30 being slidably arranged inside the circumference of the hydrodynamic (first) sliding bearing member 20.
  • the cross sectional shape of the texture element in the circumferential direction C and in the radial direction R may here also refer to the cross sectional shape of the texture element 42, as seen in the sliding direction S and the radial direction R.
  • the cross sectional shape of the texture element in the circumferential direction C and the radial direction R it is to be noted that several different shapes are conceivable depending on the effect, design, installation and working condition of the hydrodynamic sliding bearing member and the hydrodynamic sliding bearing arrangement.
  • Fig. 5b together with fig. 5c and 5e illustrate one example embodiment of the invention.
  • Fig. 5b is a top view of the example embodiment of the texture element of the texture pattern according to the invention, e.g. a texture element as illustrated in fig. 5a, in which the shape of the texture element is illustrated along the axial direction A and the circumferential direction C.
  • Fig. 5c is a perspective view of the example embodiment of the texture element of the texture pattern according to the invention
  • fig. 5e is a cross sectional view of the example embodiment of the texture element, in which the shape of the texture element is illustrated along the circumferential direction C and the radial direction R.
  • a hydrodynamic sliding bearing member 20 having a first sliding surface 22 extending in the circumferential direction C and in the axial direction A, and configured for being slidably arranged in the circumferential direction C relative to a second sliding surface 32 of a second sliding member 30 via a viscous fluid to permit the hydrodynamic sliding bearing member to operate under hydrodynamic lubrication.
  • the first sliding surface 20 has a texture pattern 40, which comprises at least one texture element 42.
  • the texture element 42 has a trailing region 50 defined by a trailing surface 52 extending from the first sliding surface 22 to the bottom surface 56 of the texture element 52.
  • a first section 59 of the trailing surface 52 is adapted to define a converging gap G with a sliding surface 32 of a second sliding member and extends a distance E RB from the first sliding surface in the radial direction R, which is smaller than 50% of the texture element depth E R .
  • first sliding surface typically refers to the plateau area 46 of the first sliding surface 22.
  • the first section 59 of the trailing surface 52 is adapted to define a converging gap G with a sliding surface 32 of a second sliding member and that the first section 59 extends a distance E RB from the first sliding surface in the radial direction R, which is smaller than 50% of the texture element depth E R , there is provided a texture element which is capable of increasing the hydrodynamic pressure generation thus increasing the fluid film thickness separating the two active surfaces (first sliding surface and second sliding surface), thus reducing the viscous film shear losses.
  • This type of configuration of the texture element shape further contributes to maintain the contact in the hydrodynamic lubrication regime, while minimizing any possible contribution from boundary friction.
  • the term “converging gap” refers to the geometry of the first section of the trailing surface (trailing region) of the texture element, which upon a sliding motion of the first sliding surface relative to the second sliding surface generates a hydrodynamic pressure in the viscous fluid film in conjunction with the opposite second sliding surface of the second sliding member.
  • the example embodiments of the invention provides a texture element shape having an optimized surface for generating a hydrodynamic pressure in a viscous fluid film confined between the sliding surfaces of the bearing arrangement, i.e. between two solid surfaces with a relative sliding motion.
  • the example embodiments are configured to utilize the hydrodynamic effect of the viscous fluid in the converging gap as defined by the first section in conjunction with the second sliding surface in order to minimize the frictional forces between the first sliding bearing member and the second sliding bearing member.
  • first section 50 of the trailing surface forms the converging gap G with the sliding surface 32 of the second sliding member during operation, i.e. when the first sliding surface is sliding relative to the second sliding surface so as to operate under hydrodynamic lubrication.
  • the first sliding surface is sliding relative to the second sliding surface due to a rotation of the second sliding bearing member 30 relative to the first sliding bearing member 20.
  • the first section of the trailing surface is configured to form a converging gap with the sliding surface of the second sliding member during operation of the hydrodynamic sliding bearing member. That is, the first section of the trailing surface is configured to form a converging gap with the sliding surface of the second sliding member during operation of the hydrodynamic sliding bearing arrangement.
  • the first section of the trailing surface forms the converging gap with the sliding surface of a second sliding member when the first sliding surface and the second sliding surface are sliding relative to each other in the circumferential direction C.
  • the first section of the trailing surface forms the converging gap with the sliding surface of a second sliding member when the first sliding surface and the second sliding surface are sliding relative to each other in the circumferential direction C due to a rotation of the second sliding member relative to the first sliding bearing member.
  • the converging gap further extends the distance E RB from the first sliding surface in the radial direction R, which is smaller than 50% of the texture element depth E R .
  • the shape of the texture element may typically resemble an ellipse, as is also shown in the previous figures.
  • the texture element has a length E A in the axial direction A and a length E c in the circumferential direction C (see fig. 5a).
  • the shape of the texture element 42 may form another shape than an ellipse, as is further described in relation to figs. 5d, 5h and 5i.
  • the shape of the texture element as seen in the axial direction A and in the circumferential direction C may be provided in several different geometries as long as the effects of the example embodiments can be provided by the texture element shape.
  • the texture element may be defined by a leading region 54 and the trailing region 50. Accordingly, the texture element may have a leading region and a trailing region with respect to the sliding direction of the opposite sliding bearing member, e.g. the second sliding bearing member 30.
  • the leading region may herein be defined by the leading edge 54 (sometimes also referred to as the leading surface).
  • the trailing region may e.g. correspond to the region 50 in the example embodiments as shown in fig. 5b - 5i.
  • the trailing region 50 may typically constitute 30 % or less of the total area of the texture element as seen in the axial direction A and the circumferential direction C.
  • the trailing region 50 may typically constitute 20 % or less of the total area of the texture element as seen in the axial direction A and the circumferential direction C. Still preferably, the trailing region 50 may typically constitute 10 % or less of the total area of texture element as seen in the axial direction A and the circumferential direction C. It should be conceivable that the trailing region is at least above 0 % of the total area of the texture element as seen in the axial direction A and the circumferential direction C.
  • the texture element is here defined by a circumferential centre line Z (as shown in e.g. fig. 5b). Fig.
  • 5b also show a plurality of cross section views J-J, M-M and l-l, which may have a cross sectional shape along the circumferential direction C and the radial direction R according to any one of the example embodiments described in relation to 5e - 5g.
  • a texture element 42 having a trailing region 50, as seen in the sliding direction S along the circumferential direction C, wherein the trailing region 50 has a trailing surface 52 defined by the first section 59 and a second section 58.
  • first section of the trailing surface is adapted to define the converging gap G with the sliding surface of a second sliding member (not shown in figs. 5c and 5 e).
  • first section 59 extends a distance E RB from the first sliding surface in the radial direction R, which is smaller than 50% of the texture element depth E R .
  • the distance E RB may even be smaller than 50% of the texture element depth E R .
  • the distance E RB from the first sliding surface 22 in the radial direction R may be smaller than 40% of the texture element depth E R .
  • the distance E RB from the first sliding surface 22 in the radial direction R may be smaller than 25 % of the texture element depth E R .
  • the distance E RB from the first sliding surface 22 in the radial direction R may be smaller than 10 % of the texture element depth E R .
  • the distance E RB from the first sliding surface 22 in the radial direction R may be smaller than 5 % of the texture element depth E R .
  • the distance E RB may be 20 ⁇ and the texture element depth E R may be 40 ⁇ . In another example, the distance E RB may be 30 ⁇ and the texture element depth E R may be 50 ⁇ . However, other values on the distances are conceivable according to the example embodiments as described herein.
  • the distance E RB from the first sliding surface 22 in the radial direction R is at least above 0 % of the depth of the texture element depth E R .
  • the distance from the first sliding surface in the radial direction is at least more than 2 % of the depth of the texture element depth.
  • the distance from the first sliding surface in the radial direction is at least more than 2 % of the depth of the texture element depth, but smaller than 50% of the texture element depth. In another example, the distance from the first sliding surface in the radial direction is at least more than 5 % of the depth of the texture element depth, but smaller than 30% of the texture element depth.
  • first section 59 of the trailing surface 52 here typically has an extension E C B in the circumferential direction C which is larger than 5% and smaller than 50% of the length of the texture element 42 in the circumferential direction C.
  • the length of the texture element 42 in the circumferential direction C is here denoted by the reference E C .
  • the first section of the trailing surface may typically have an extension in the circumferential direction which is larger than 1 0% and smaller than 50% of the length of the texture element in the circumferential direction.
  • the first section of the trailing surface may typically have an extension in the circumferential direction which is larger than 15% and smaller than 50% of the length of the texture element in the circumferential direction.
  • the extension E C B is a part of the entire length E C of the texture element in the circumferential direction C
  • the first section 59 also has an axial extension E A1 .
  • the first section 59 is tapering along the circumferential direction C in a direction away from the leading edge 54 of the texture element 42.
  • Other shapes of the first section are also conceivable as described in relation to figs. 5h and 5i.
  • the tapered first section 59 here defines a convex curvature 82, as seen in the axial direction A and in the circumferential direction C.
  • the degree of the curvature of the tapered first section 59 is similar to the curvature of the leading edge 54 of the texture element 42.
  • the curvature of the tapered first section 59 here refers to the curvature of the first section as indicated by reference 82, while the curvature of the leading region is here indicated by e.g. leading edge 84.
  • the extension of the curvature of the first section in the radial direction is typically defined by the extension of the first section in radial direction R
  • the extension of the curvature of the leading region is typically defined by the extension of the leading region in the radial direction R, which thus typically extends to the bottom surface 56 of the texture element.
  • the bottom surface of the remaining texture element here resembles a truncated ellipse.
  • the degree of the curvature of the tapered first section 59 may differs from the curvature of the leading edge 54 of the texture element 42, as shown in fig. 5d.
  • the degree of the curvature of the tapered first section 59 of the trailing region 50 is greater than a curvature of the leading edge 54 of said texture element 42.
  • the curvature of the tapered first section 59 here refers to the curvature of the first section as indicated by reference 82, while the curvature of the leading region is here indicated by e.g. leading edge 84.
  • the extension of the curvature of the first section in the radial direction is typically defined by the extension of the first section in radial direction R
  • the extension of the curvature of the leading region is typically defined by the extension of the leading region in the radial direction R, which thus typically extends to the bottom surface 56 of the texture element.
  • the bottom surface of the remaining texture element here resembles a truncated ellipse.
  • the trailing surface 52 here also defines a second section 58 extending from the bottom surface 56.
  • the second section 58 of the trailing surface 52 extending from the bottom surface 56 has a normal with a different direction than a normal of the first section 59.
  • the second section 58 of the trailing surface 52 extending from the bottom surface 56 is arranged to extend essentially perpendicular from the bottom surface 56.
  • the second section 58 of the trailing surface 52 extending from the bottom surface 56 in some example embodiments may be inclined in relation to the bottom surface 56 as long as the first section is capable of forming a converging gap with the second sliding surface during operation of the hydrodynamic sliding bearing arrangement, as described above.
  • the angle between the second section and the bottom surface may typically be 90 degrees it is to be noted that in some example embodiments, the inclination between the second section and the bottom surface may be arranged by an angle between 45 - 90 degrees, as long as the first section of the trailing region is capable of defining a converging gap as explained above.
  • the transition from the first section 59 to the second section 58 is defined by a transition point T P .
  • the first section 59 and the second section 58 are typically connected at a transition point T P .
  • the trailing surface 52 defines a first section extending from the sliding surface 22 to the transition point T P and the second section 58 extending from the bottom surface 56 to the transition point T P .
  • the distance E RB may be defined by a distance between the first sliding surface 22 and the transition point T P , as measured in the radial direction R.
  • the texture element 42 in this example embodiment has a cross sectional shape extending in the circumferential direction C and a radial direction R, wherein the first section 59 of the trailing surface 52 is arranged to deviate from the first sliding surface 22 by an angle a c .
  • the first section of the trailing surface is adapted to define a converging gap with a sliding surface of a second sliding member by means of having the first section of the trailing surface arranged to deviate from the first sliding surface by an angle a c .
  • the angle a c is between 0.1 - 5 degrees. In this way, there is provided a texture element shape configured to provide an optimal buildup of hydrodynamic pressure.
  • the angle a c is about 0.5 degrees.
  • the angle a c is about 0.3 degrees.
  • the angle a c may be between 0.3 - 3 degrees.
  • the angle a c may be between 1 - 3 degrees. It is to be noted that the angle a c in fig. 5e is depicted slightly bigger than the above range in order to allow for an illustration of the dimensions, and thus only provide a schematic view of the configuration and the angle.
  • angle a c may be set to another angle depending on the selection of manufacturing method having specific limitations. Also, operation conditions, sliding velocities, contact conditions oil film thickness and application of the texture element and the hydrodynamic sliding bearing member may cause a c to be selected in a different interval then specified herein.
  • the first sliding surface here refers to the plateau area of the first sliding surface.
  • the texture element has a cross sectional shape extending in the circumferential direction and the radial direction, the first section of the trailing surface being arranged to deviate from the plateau area of the first sliding surface by the angle a c .
  • a minimum depth of the texture elements should be above 10 ⁇ , as further described herein.
  • the first section may be designed in several different ways to form the converging gap G 5 with the second sliding surface 32 (as shown in e.g. fig. 3).
  • the first section 59 is here a straight wall surface as seen in the cross section extending in the circumferential direction C and a radial direction R. Further, the straight wall surface is arranged to deviate from the first sliding surface 22 by the angle a c .
  • the texture element has a cross sectional shape extending in the
  • the first section 59 of the trailing surface 52 being arranged to deviate from the first sliding surface 22 by the angle a c , and wherein the first section 59 is a straight wall surface as seen in the cross section extending in the circumferential direction C and the radial direction R.
  • the trailing surface 52 defines a second section 58 and a first inclined section 59. Furthermore, the trailing surface 52 defines a second section 58 and a first inclined section 59. Furthermore, the
  • the second section 58 has a length E RC smaller than the depth E R , in which the depth E R is defined by the distance between the sliding surface 22 and the bottom surface of the texture element 56, as seen in the radial direction R. Only as an example, the distance of E RC may be
  • the distance E RC is determined by the
  • first inclined section 59 extends from the second section 58 to the sliding surface 22 of the hydrodynamic sliding bearing member 20, wherein the first inclined section 59 forms the angle a c with the sliding surface 22 of the hydrodynamic
  • the angle a c is permitted to be significantly smaller than a right angle of a conventional texture element shape, i.e. a texture element having a right angle between the sliding surface and the trailing surface. .
  • the angle a c is typically between 0.1 - 5 degrees. In this manner, it becomes possible to provide a texture element shape that is capable of increasing the hydrodynamic pressure generation, thus reducing the viscous film shear losses and maintaining the contact in the hydrodynamic lubrication regime.
  • fig. 5e illustrates an example embodiment of a sliding surface 22 comprising a texture pattern 40 having a plurality of texture elements 42 (although only one element is shown in the figure), wherein each texture element 42 extends in the axial direction A and the circumferential direction C and has a depth E R in the radial direction R, where the depth is defined by the distance between the sliding surface 22 and the bottom surface 56 of the texture element 42. Further, each texture element 42 has the trailing region 50 as seen in the sliding direction S along the circumferential direction C, the trailing region 50 having the trailing surface 52 defined by the second section 58 and the first section 59.
  • the second section 58 extends essentially perpendicular from the bottom surface 56 of the texture element to the first section 59 of the trailing region 50, wherein the second section 58 has a length E RC smaller than the depth E R , and the first section 59 extends from the second section 58 to the sliding surface 22 of the hydrodynamic sliding bearing member 20.
  • the second section 58 extends essentially perpendicular from the bottom surface 56 of the texture element to the transition point T P , as defined by the intersection between the second section 58 and the first section 59 of the trailing region 50.
  • the first section 59 forms the angle a c with the sliding surface 22 of the hydrodynamic sliding bearing member 20.
  • first section of the trailing surface is adapted to define the converging gap with the sliding surface of the second sliding member by means of having the first section of the trailing surface arranged to deviate from the first sliding surface by the angle a c .
  • the angle between the bottom surface 56 and the second section 58 is depicted as a right angle, however, this angle may slightly vary depending on the installation and type of texture element and texture pattern etc. In addition, due to operation conditions as well as manufacturing condition, this type of angle may slightly vary from a right angle as conceived by the skilled person. Thus, the figures are only to be considered as schematic figures with respect to right angles, dimensions and scale.
  • This example embodiment as described in relation to figs. 5b, 5c and 5e may, as mentioned above, be a part of any one of a main bearing, journal bearing or connecting rod bearing of an internal combustion engine of a vehicle, as described in relation to the figures 1 , 2a - 2g, 3, 4a - 4i, 5a and 6a - 6b, or any other type of bearing in a mechanical device such as a bushing.
  • this example embodiment of the texture element shape may be arranged in any one of the texture patterns as described in relation to figs. 4a - 4i and 6a - 6b.
  • the first example embodiment as shown in e.g. fig. 5e may be selected, while for other applications it may be more optimal to select any one of the example embodiments as described in relation to fig. 5f or 5g etc.
  • the first section of the trailing surface may be adapted in several different ways in order to define (form) a converging gap with a sliding surface of a second sliding member as will be described further herein.
  • the first section 59 may be a curved wall surface as seen in a cross section extending in the circumferential direction C and the radial direction R.
  • Fig. 5g is a cross sectional view of yet another example embodiment of the texture element in fig. 5b, in which the cross sectional view illustrates the cross sectional shape of the texture elements along a circumferential direction and a radial direction.
  • the first section 59 of the trailing surface 52 is adapted to define (form) the converging gap G with the sliding surface of the second sliding member by a curved wall surface.
  • the first section is a curved wall surface as seen in a cross section extending in the circumferential direction and a radial direction.
  • the first section extends to the second section of the trailing surface, as mentioned herein. In this way, there is provided a texture element shape configured to provide an optimal build-up of hydrodynamic pressure.
  • a hydrodynamic sliding bearing member 20 having a first sliding surface 22 extending in the circumferential direction C and in the axial direction A, and configured for being slidably arranged in the circumferential direction C relative to a second sliding surface 32 of a second sliding member 30 via a viscous fluid to permit the hydrodynamic sliding bearing member to operate under hydrodynamic lubrication.
  • the first sliding surface 20 has a texture pattern 40, which comprises at least one texture element 42.
  • the texture element 42 has a trailing region 50 defined by a trailing surface 52 extending from the first sliding surface 22 to the bottom surface 56 of the texture element 52.
  • a first section 59 of the trailing surface 52 is adapted to define a converging gap G with a sliding surface 32 of a second sliding member and extends a distance E RB from the first sliding surface in the radial direction R, which is smaller than 50% of the texture element depth E R .
  • the first section is a first curved section 59.
  • the texture element 42 has a trailing region 50, as seen in the sliding direction S along the circumferential direction C.
  • the trailing region 50 has a trailing surface 52 defined by the second section 58 and the first curved section 59.
  • the second section 58 extends essentially perpendicular from the bottom surface of the texture element 56 to the first curved section 59 of the trailing surface 52.
  • the second section 58 has a length E RC smaller than the depth E R , in which the depth E R is defined by the distance between the sliding surface 22 and the bottom surface of the texture element 56, as seen in the radial direction R.
  • the first curved section 59 extends from the second section 58 to the sliding surface 22 of the hydrodynamic sliding bearing member 20, wherein the curvature of the first curved section 59 is convex, as shown in fig. 5g.
  • the curvature may even be concave.
  • the radius of the curvature may be selected according to the contact condition and application of the texture element and the hydrodynamic sliding bearing member.
  • the radius of the curvature may vary according to general design of the bearing, operating conditions such as load and sliding speed etc.
  • a minimum depth of the texture elements should be above 10 ⁇ .
  • This example embodiment may, as mentioned above, also be a part of any one of a main bearing, journal bearing or connecting rod bearing of an internal combustion engine of a vehicle, as described in relation to the figures 1 , 2a - 2g, 3, 4a - 4i, 5a and 6a - 6b, or any other type of bearing in a mechanical device such as a bushing.
  • this example embodiment of the texture element shape may be arranged in any one of the texture patterns as described in relation to figs. 4a - 4i and 6a - 6b. As mentioned above, there are typically no generic values for the above parameters since the values of each parameter depends on the specific bearing operation and installation etc.
  • the first section 59 may be a step shaped section being defined by a first step surface 59a extending essentially perpendicular from the sliding surface 22 and a second step surface 59b extending essentially perpendicular from the first surface 59a to the second section 58.
  • Fig. 5f is a cross sectional view of yet another example embodiment of the texture element in fig. 5b, in which the cross sectional view illustrates the cross sectional shape of the texture elements along the circumferential direction C and the radial direction R.
  • the first section 59 of the trailing surface is adapted to define (form) the converging gap G with the sliding surface of the second sliding member by a step shaped section.
  • the first section of the trailing surface 52 is adapted to define (form) the converging gap G with the sliding surface of the second sliding member 30 by having a step shaped first section 59.
  • said first section is a step shaped section being defined by a first step surface 59a extending essentially perpendicular from the sliding surface 22 and a second step surface 59b extending essentially perpendicular from the first step surface 59a to a second section 58.
  • a hydrodynamic sliding bearing member 20 having a first sliding surface 22 extending in the circumferential direction C and in the axial direction A, and configured for being slidably arranged in the circumferential direction C relative to the second sliding surface 32 of the second sliding member 30 via a viscous fluid to permit the hydrodynamic sliding bearing member to operate under hydrodynamic lubrication.
  • the first sliding surface 20 has a texture pattern 40, which comprises at least one texture element 42.
  • the texture element 42 has the trailing region 50 defined by the trailing surface 52 extending from the first sliding surface 22 to the bottom surface 56 of the texture element 52.
  • first section 59 of the trailing surface 52 is adapted to define the converging gap G with the sliding surface 32 of the second sliding member and extends the distance E RB from the first sliding surface in the radial direction R, which is smaller than 50% of the texture element depth E R .
  • the texture element 42 here has a trailing region 50, as seen in the sliding direction S along the circumferential direction C, wherein the trailing region 50 has a trailing surface 52 defined by a second section 58, the first step surface 59a and the second step surface 59b. Furthermore, the second section 58 extends essentially perpendicular from the bottom surface of the texture element 56 to the second step surface 59b of the trailing surface 52. To this end, the second section 58 extends essentially perpendicular from the bottom surface of the texture element 56 to the transition point T P .
  • the second step surface 59b is
  • the second step surface 59b is parallel to the bottom surface 56 and the sliding surface 22. Furthermore, the second step surface 59b extends from the second section 58 to the first step surface 59a of the trailing surface 52. In this example embodiment, the first step surface 59a is perpendicular arranged to the second step surface 59b. In addition, the first step surface
  • This type of shape of the trailing edge of the texture element may also be referred to as the Rayleigh step.
  • This example embodiment may, as mentioned above, be a part of any one of a main bearing, journal bearing or connecting rod bearing of an internal combustion engine of a vehicle, as described in relation to the figures 1 , 2a - 2g, 3, 4a - 4i, 5a and 6a - 6b,
  • this example embodiment of the texture element shape may be arranged in any one of the texture patterns as described in relation to figs. 4a - 4i and 6a - 6b.
  • Fig 5d is a perspective view of another example embodiment of the texture element, e.g. a texture element as illustrated in fig. 5b, in which a trailing region of the texture element is illustrated as seen in the axial direction A, the circumferential direction C and the radial direction R.
  • the degree of the curvature of the tapered first
  • This example embodiment of the texture element shape may be arranged in any one of the texture patterns as described in relation to figs. 4a - 4i and 6a - 6b.
  • the first section of the trailing region 50 may be designed according to any one of the
  • the shape of the texture element 42 may form another shape than an ellipse, as is further described in relation to figs. 5h and 5i.
  • the shape of the texture element as seen in the axial direction A and in the circumferential direction C may be provided in several different geometries as long as the effects of the example embodiments can be provided by the texture element shape.
  • Fig. 5h is a perspective view of another example embodiment of the texture element, e.g. a texture element as illustrated in fig. 5b, in which a trailing region of the texture element is illustrated as seen in an axial direction, a circumferential direction and a radial direction.
  • the first section 59 has an axial extension E A1 which is constant along the circumferential direction C in a direction away from the leading edge 54 of the texture element.
  • this example embodiment of the texture element shape may be arranged in any one of the texture patterns as described in relation to figs. 4a - 4i and 6a - 6b.
  • the first section of the trailing region 50 may be designed according to any one of the example embodiments as described in relation to figs. 5e - 5g etc.
  • Fig. 5i is a perspective view of another example embodiment of the texture element, e.g. a texture element as illustrated in fig. 5b, in which a trailing region of the texture element is illustrated as seen in an axial direction, a circumferential direction and a radial direction.
  • the tapered first section 59 comprises two radial extending parts which are linearly tapering along the circumferential direction C in a direction away from the leading edge 54 of the texture element 42.
  • the first section 59 here resembles a triangle as seen in the axial direction A and in the circumferential direction C.
  • this example embodiment of the texture element shape may be arranged in any one of the texture patterns as described in relation to figs. 4a - 4i and 6a - 6b.
  • the first section of the trailing region 50 may be designed according to any one of the example embodiments as described in relation to figs. 5e - 5g etc.
  • the texture element 42 may be defined by the leading region having a leading surface 54 extending from the bottom surface 56 to the first sliding surface 22 by an angle a L of between 45 - 90 degrees.
  • the angle a L is herein defined by the angle between the bottom surface and the leading surface 54 (extending between the first sliding surface 22 and the bottom surface 56).
  • the texture element 42 is here defined by a leading region having a leading surface 54 extending essentially perpendicular from said bottom surface 56 to said first sliding surface 22.
  • the bottom surface 56 is typically essentially parallel to the sliding surface 22.
  • a texture element having a bottom surface being essentially parallel to the sliding surface provides that the depth of the texture element along the tangential texture element length (length of the texture element in the circumferential direction) can be sufficiently deep for a substantial part of the texture element length, thus maintaining the desired fluid film thickness within the texture and thus not increasing the viscous shear losses.
  • a length of the bottom surface 56 here has an extension E c in the circumferential direction C which is larger than 50 % and smaller than 85% of the length of the texture element 42 in the circumferential direction C.
  • the cross sectional shape in the axial direction A and circumferential direction C may be a rectangle, circle, triangle, or any other suitable shape.
  • the cross sectional shape is essentially an ellipse, extending in the axial direction A and in the circumferential direction C.
  • the texture elements may each have one of a substantially circular, oval, or elliptical shape.
  • texture elements can have other shapes, such as triangular, grooves, square, rectangular, diamond, etc.
  • texture element shapes may include open or closed voids. That is, any one of the texture elements may have a cross-sectional shape in the form of a square, rectangle, circle, or ellipse.
  • the various example embodiments of the texture element and the converging gap may typically be utilized for at least a substantial part of all texture elements of the sliding surface(s). Still preferably, the various example embodiments of the texture element and the converging gap may typically be utilized for all texture elements of the sliding surface(s).
  • one example advantage with the example embodiments of the invention is to provide a first sliding surface with a texture pattern having at least one texture element shape, as described in relation to figs. 5a to 5i, which is capable of increasing the generation of hydrodynamic pressure.
  • This type of texture element shape has a trailing region defined by a trailing surface extending from the first sliding surface to a bottom surface of the texture element.
  • a first section of the trailing surface is adapted to define a converging gap with a sliding surface of a second sliding member and extends a distance from the first sliding surface in a radial direction, which is smaller than 50% of the texture element depth.
  • the texture pattern 40 may be arranged on both the first sliding member 20 and the second sliding member 30.
  • This type of example embodiment may include any one of the features and functions as described above in relation to the figures.
  • a bearing arrangement may be provided which includes a first sliding member 20 having a texture pattern according to the example embodiments as described herein and a second sliding member 30 having a texture pattern according to the example embodiments as described herein.
  • the provision “upon rotation of the first sliding member 20 relative to the second sliding member 30" may refer to that the first sliding member rotates, while the second sliding member is stationary.
  • the provision “upon rotation of the first sliding member 20 relative to the second sliding member 30" may refer to that the first sliding member is stationary, while the second sliding member rotates.
  • the provision “upon rotation of the first sliding member 20 relative to the second sliding member 30" may refer to that the first sliding member rotates and the second sliding member rotates.
  • the area density of the texture elements is further varied along the circumferential direction C.
  • the area density can be varied in similar manner as mentioned above with respect to decreasing area density towards the axial boundary.
  • the area density of the texture elements may be varied along the circumferential direction C by decreasing at least one of the axial length E A and the circumferential length E c of each texture element per unit along the length of the first sliding surface as seen circumferential direction C of the first sliding surface.
  • the area density of the texture elements may be varied along the circumferential direction C by increasing at least one of the axial length E A and the circumferential length E c of each texture element per unit along the length of the first sliding surface as seen circumferential direction C of the first sliding surface.
  • the area density of the texture elements may be varied along the circumferential direction C by decreasing the quantity of texture elements along the length of the first sliding surface as seen in the circumferential direction C of the first sliding surface.
  • the area density of the texture elements may be varied along the circumferential direction C by increasing the quantity of texture elements along the length of the first sliding surface as seen in the circumferential direction C of the first sliding surface.
  • the depth of the texture elements may be varied along the circumferential direction C by increasing or decreasing the depth of the texture elements along the length of the first sliding surface as seen in the circumferential direction C of the first sliding surface.
  • decreasing or increasing the area density or increasing or decreasing the texture depth may either be linear or non-linear as a function of axial dimension and circumferential dimension.
  • the hydrodynamic sliding bearing member 20 may be incorporated in a hydrodynamic sliding bearing arrangement 10, so that the hydrodynamic sliding bearing member 20 is a first sliding member according.
  • the hydrodynamic sliding bearing arrangement 10 further comprises the second sliding member 30 having the second sliding surface 32.
  • the first sliding member 20 is centred around the second sliding member 30 so that the hydrodynamic sliding bearing arrangement is configured to support a rotational motion between the first sliding member and the second sliding member.
  • the first sliding surface 22 of the first sliding member 20 is an inner circumferential surface and the second sliding surface 32 of the second sliding bearing member 30 is an outer circumferential surface.
  • the first sliding bearing member 20 is further centred around the second sliding bearing member 30 so that the inner circumferential surface is allowed to slide about the outer circumferential surface of the second sliding member, via the viscous fluid 60 upon rotation of the second sliding member 30 relative to the first sliding member 20.
  • the construction may optionally, although not strictly required, be further configured to form a sealed
  • one example advantage of the example embodiments of the hydrodynamic sliding bearing member, and the hydrodynamic sliding bearing arrangement is to reduce fuel consumption by reducing hydrodynamic friction losses in the internal combustion engine of the vehicle in an optimal way.
  • hydrodynamic sliding bearing members in figs. 2a - 6b are merely general schematic representations of a hydrodynamic sliding bearing member, and intended to show the underlying principle of the inventive concept. Accordingly, the components may include further features, functions and sub-components not shown in the figures.

Abstract

L'invention concerne un élément palier à coulissement hydrodynamique (20) ayant une première surface de coulissement (22) s'étendant dans une direction circonférentielle (C) et dans une direction axiale (A), et conçue pour être agencée coulissante dans la direction circonférentielle (C) par rapport à une seconde surface de coulissement (32) d'un second élément de coulissement (30) par l'intermédiaire d'un fluide visqueux (60) afin de permettre à l'élément palier à coulissement hydrodynamique (20) de fonctionner dans une condition de lubrification hydrodynamique. La première surface de coulissement (22) présente un motif de texture (40), qui comprend au moins un élément de texture (42) ayant une région de fuite (50) définie par une surface de fuite (52) s'étendant depuis ladite première surface de coulissement (22) vers une surface inférieure (56) dudit élément de texture (42). De plus, une première section (59) de la surface de fuite (52) est conçue pour délimiter un espace convergent (G) avec la surface de coulissement du second élément de coulissement (30) et s'étend sur une distance (ERB) de la première surface de coulissement (22) dans une direction radiale (R), qui est inférieure à 50 % de la profondeur de l'élément de texture (ER).
PCT/EP2015/058436 2015-04-17 2015-04-17 Élément palier à coulissement hydrodynamique WO2016165779A1 (fr)

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PCT/EP2015/058436 WO2016165779A1 (fr) 2015-04-17 2015-04-17 Élément palier à coulissement hydrodynamique

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JP2019027524A (ja) * 2017-07-31 2019-02-21 大同メタル工業株式会社 半割軸受およびすべり軸受
CN114962455A (zh) * 2022-04-01 2022-08-30 上海大学 一种应用鲨鱼皮织构化表面的径向滑动轴承
CN116181803A (zh) * 2023-03-08 2023-05-30 西南石油大学 一种提高压裂泵滑动轴承润滑能力的轴瓦梯度表面织构

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US5265964A (en) * 1990-03-02 1993-11-30 Smith International, Inc. Lubricant system for a rotary cone rock bit
US5725314A (en) * 1995-12-06 1998-03-10 Ingersoll-Rand Company Hydrodynamic bearing
EP0982507A1 (fr) * 1998-03-10 2000-03-01 Sumitomo Electric Industries, Ltd. Structure de palier a gaz sous pression dynamique
US20020018604A1 (en) * 2000-06-23 2002-02-14 Georg Weissbacher Hydrodynamic plain bearing and method of lubricating and cooling the bearing
US20050175263A1 (en) * 2004-02-05 2005-08-11 Nissan Motor Co., Ltd. Sliding device
US20110162614A1 (en) * 2010-01-07 2011-07-07 Lapp Michael T Profiled connecting rod bore with micro-dimples

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Publication number Priority date Publication date Assignee Title
DE2847246A1 (de) * 1978-10-31 1980-05-08 May Michael G Hubkolbenbrennkraftmaschine
US5265964A (en) * 1990-03-02 1993-11-30 Smith International, Inc. Lubricant system for a rotary cone rock bit
US5725314A (en) * 1995-12-06 1998-03-10 Ingersoll-Rand Company Hydrodynamic bearing
EP0982507A1 (fr) * 1998-03-10 2000-03-01 Sumitomo Electric Industries, Ltd. Structure de palier a gaz sous pression dynamique
US20020018604A1 (en) * 2000-06-23 2002-02-14 Georg Weissbacher Hydrodynamic plain bearing and method of lubricating and cooling the bearing
US20050175263A1 (en) * 2004-02-05 2005-08-11 Nissan Motor Co., Ltd. Sliding device
US20110162614A1 (en) * 2010-01-07 2011-07-07 Lapp Michael T Profiled connecting rod bore with micro-dimples

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2019027524A (ja) * 2017-07-31 2019-02-21 大同メタル工業株式会社 半割軸受およびすべり軸受
CN114962455A (zh) * 2022-04-01 2022-08-30 上海大学 一种应用鲨鱼皮织构化表面的径向滑动轴承
CN116181803A (zh) * 2023-03-08 2023-05-30 西南石油大学 一种提高压裂泵滑动轴承润滑能力的轴瓦梯度表面织构
CN116181803B (zh) * 2023-03-08 2023-09-22 西南石油大学 一种提高压裂泵滑动轴承润滑能力的轴瓦梯度表面织构

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