EP3508714A1 - Piston for a combustion engine - Google Patents

Abstract

The invention relates to a piston (10) for an internal combustion engine. The piston (10) has an inner piston cooling passage (20) for cooling the piston (10). The piston (10) has an inlet channel (16) which opens into an inlet (28) of the piston cooling channel (20), wherein a flow cross section of the inlet channel (16) in a direction to the inlet (28) of the internal piston cooling channel (20 ) is at least partially, in particular funnel-shaped, tapered and the inlet channel (16) in addition to conveying a cooling fluid flow to the inlet (28) of the inner piston cooling channel (20) is formed. The invention makes it possible to ensure adequate cooling of the piston (10) even at high piston speeds.

Description

The invention relates to a piston for an internal combustion engine.

For cooling a piston of an internal combustion engine, a piston may have an internal piston cooling channel. The piston cooling passage may have an inlet at a bottom of the piston. Through the inlet, cooling fluid, for example, oil injected from a cooling fluid injection nozzle in a direction toward the inlet, may enter the piston cooling passage. The cooling fluid may exit the piston cooling passage through an outlet at the bottom of the piston.

From the DE 197 36 135 C1 a liquid-cooled piston for internal combustion engines is known, which has an at least partially annular segment-shaped cooling channel. The cooling channel is formed below a piston crown in a piston upper part. The cooling channel has openings for the inlet and outlet of the cooling liquid. The openings are formed with a drogue.

From the EP 2 348 207 A2 Furthermore, a piston is known in which an inlet channel for a piston cooling channel is arranged completely in a piston shaft of a piston. The inlet channel has a funnel-shaped inlet region.

In particular, at high speeds of the piston, it may happen that the degree of capture of the inlet of the cooling fluid channel is sometimes significantly reduced. That is, the relative proportion of the cooling fluid entering the inner cooling fluid passage of the piston decreases.

The invention is based on the object to improve a cooling fluid supply to a piston cooling channel. In particular, sufficient cooling fluid should be supplied to the piston cooling channel of the piston even at high piston speeds.

The object is solved by the features according to the independent claim. Advantageous developments are specified in the dependent claims and the description.

The piston is suitable for an internal combustion engine (eg reciprocating internal combustion engine). The piston has an inner piston cooling channel for cooling the piston. The piston has an inlet channel, which opens into the piston cooling channel on. A flow cross section the inlet channel tapers in a direction to the inlet of the inner piston cooling channel at least in sections, in particular funnel-shaped. The inlet passage is in addition to promoting (eg, enhancing, increasing) cooling fluid flow (eg, reducing cooling fluid friction losses) to the inlet of the internal piston cooling passage.

In particular, the cooling fluid may be oil.

For example, in addition to the at least partial taper, the inlet channel may include means (eg, surface treatment, coating, and / or flow guide member (s)) for promoting cooling fluid flow to the piston cooling channel.

Thus, a sufficient cooling of the piston can preferably be ensured even at high piston speeds. The tapered inlet passage intensively directs injected cooling fluid to the inlet of the piston cooling passage. Thus, the cooling fluid passes in terms of quantity reinforced in the cooling fluid channel and can better carry away the heat load occurring and thus reduce a temperature of the piston. Furthermore, preferably by the specific design of the inlet channel, for example by reducing cooling fluid friction losses, a flow of cooling fluid through the inlet channel into the inlet of the cooling fluid channel can be promoted.

In particular, the inlet channel may be arranged below an underside of the piston. For example, the inlet channel can be arranged directly below an inlet of the piston cooling channel.

It is possible that the inlet of the piston cooling channel opens in a lower side of the piston.

For example, the cooling fluid channel may be annular and / or may have a plurality of subchannels. It is possible that the cooling fluid channel is arranged below a piston crown in a piston upper part.

Suitably, the piston cooling channel may have an outlet. For example, the outlet may be arranged with respect to a center axis of the piston opposite to the inlet of the cooling fluid channel.

In a particularly preferred embodiment, the inlet channel for conveying the cooling fluid flow in the inlet channel is at least partially surface-treated, in particular for reducing a surface roughness. Preferably, the inlet channel may be polished his. This cooling fluid friction losses can be reduced in the inlet channel and thus a cooling fluid flow can be increased in the cooling fluid channel.

In particular, a peripheral surface of the inlet channel may be surface-treated at least in sections, in particular for reducing a surface roughness of the peripheral surface. For example, the peripheral surface may be at least partially polished.

In a further particularly preferred embodiment, the inlet channel for conveying the cooling fluid flow in the inlet channel is coated with a flow resistance-reducing and / or a surface roughness-reducing coating. In particular, the coating may be applied by thermal spraying. Hereby, cooling fluid friction losses in the inlet channel can be reduced and thus a cooling fluid flow into the cooling fluid channel can be increased.

In particular, a circumferential surface of the inlet channel may be coated at least in sections.

In a further particularly preferred embodiment, the inlet channel for conveying the cooling fluid flow in the inlet channel comprises at least one flow guide element for guiding the cooling fluid in a direction to the inlet of the inner piston cooling channel. Through the guide, the cooling fluid can be directed to the inlet of the inner piston cooling channel. The cooling fluid can flow faster into the cooling fluid channel. A cooling fluid flow into the cooling fluid channel can be increased.

In a further development, the at least one flow guide element is designed as a groove in a peripheral surface of the inlet channel. Alternatively or additionally, the at least one flow guide element is designed as a projection, in particular as a guide fin, on a peripheral surface of the inlet channel.

Suitably, the groove and / or the protrusion may be rounded (eg with a radius between 0.1 mm and 5 mm) or square (eg rectangular, trapezoidal, etc.). For example, the groove and / or the projection may have a width between 0.1 mm and 5 mm. In particular, a side surface of an angular groove and / or an angular projection may include an angle in a range between 0 ° and 90 ° with a normal of the peripheral surface.

Suitably, the at least one flow guide element may have a height or depth in a range between 0.1 mm and 5 mm.

In one embodiment, the at least one flow guide element extends in a direction toward the inlet of the inner piston cooling channel. It is also possible for the at least one flow-guiding element to extend in a straight-line and / or at least partially helical manner at least in sections. Thus, the cooling fluid can be supplied in a straight line or helical to the inlet of the inner cooling fluid channel.

In a further embodiment, the at least one flow guide element has a plurality of, in particular symmetrical, flow guide elements arranged around a circumference of the inlet channel.

In particular, the at least one flow guide element can be pressed, cut or incorporated in a peripheral surface of the inlet channel.

In one embodiment, the inlet channel is at least partially formed by a drogue, which is connected to an underside of the piston.

In a development, the drogue is integrally formed integrally with the underside of the piston or formed separately and connected to the bottom, in particular detachably connected.

In a further embodiment, the drogue and the underside of the piston are made of the same material or of different materials. This can be used, for example, cost-effective materials and / or easily moldable or machinable materials for the drogue.

For example, the drogue may have a height greater than 0 mm and / or less than 60 mm, in particular in a range between 5 mm and 40 mm.

In one embodiment, the drogue is at least partially formed by a piston skirt. For example, the piston skirt form a wall segment of the drogue, which is connected to a further, formed separately from the piston skirt wall segment of the drogue.

In a further embodiment, the inlet channel tapers at least in sections at an angle greater than 0 ° and / or less than 45 °, in particular between 5 ° and 30 ° a longitudinal axis of the inlet channel. Alternatively or additionally, the inlet channel opens rounded into the inlet of the piston cooling channel, in particular with a radius greater than 0 mm and / or smaller than 30 mm, preferably between 5 mm and 20 mm.

The invention also relates to a cooling fluid injector configured to inject the cooling fluid with a swirl (eg, helical flow and / or rotation about an axis of the cooling fluid jet). The swirl can stabilize the cooling fluid jet injected in a direction toward an underside of a piston. The thus stabilized cooling fluid jet is less affected by spray and Panschfluid in crankcase. Thus, the cooling fluid flow supplied to a cooling fluid passage of the piston can be increased in volume.

In an embodiment, the cooling fluid injector may be included in a device having a piston as disclosed herein. The cooling fluid injector may be directed to an inlet port of the inlet channel.

In particular, the cooling fluid injection device may be attached to a crankcase of the internal combustion engine, in particular fixed. It is possible for the cooling fluid injector to be fluidly connected to a cooling fluid pump that delivers cooling fluid to the cooling fluid injector.

In a development, the cooling fluid injection device has an injection nozzle with at least one swirl element, in particular a helical groove and / or a helical projection which is designed to impart a twist to the cooling fluid.

In particular, the at least one swirl element can be pressed, cut or incorporated in a channel of the injection nozzle.

The invention is also directed to a motor vehicle, in particular a utility vehicle, having a piston as disclosed herein or a device as disclosed herein.

For example, it is also possible to use the piston and / or the device as disclosed herein for passenger cars, large engines, off-highway vehicles, stationary engines, marine engines, and so on.

Figur 1

eine schematische Ansicht einer Unterseite eines Kolbens gemäß einem Ausführungsbeispiel;

Figur 2

eine Schnittansicht durch den beispielhaften Kolben und eine Kühlfluideinspritzeinrichtung;

Figur 3

eine Schnittansicht durch einen Kolben gemäß einem weiteren Ausführungsbeispiel und eine Kühlfluideinspritzeinrichtung;

Figur 4

eine schematische Ansicht einer Unterseite eines Kolbens gemäß einem weiteren Ausführungsbeispiel;

Figur 5

eine Schnittansicht durch den beispielhaften Kolben von Figur 4 und eine Kühlfluideinspritzeinrichtung;

Figur 6

eine schematische Ansicht einer Unterseite eines Kolbens gemäß einem weiteren anderen Ausführungsbeispiel;

Figur 7

eine Schnittansicht durch den beispielhaften Kolben von Figur 6 und eine Kühlfluideinspritzeinrichtung;

Figur 8

einen Ausschnitt einer Schnittansicht durch einen beispielhaften Fangtrichter;

Figur 9

einen Ausschnitt einer Schnittansicht durch einen weiteren beispielhaften Fangtrichter;

Figur 10

einen Ausschnitt einer Schnittansicht durch einen weiteren beispielhaften Fangtrichter; und

Figur 11

einen Ausschnitt einer Schnittansicht durch einen weiteren beispielhaften Fangtrichter.

The preferred embodiments and features of the invention described above can be combined with one another as desired. Further details and advantages of the invention will be described below with reference to the accompanying drawings. Show it:

FIG. 1

a schematic view of an underside of a piston according to an embodiment;

FIG. 2

a sectional view through the exemplary piston and a cooling fluid injector;

FIG. 3

a sectional view through a piston according to another embodiment and a cooling fluid injector;

FIG. 4

a schematic view of an underside of a piston according to another embodiment;

FIG. 5

a sectional view through the exemplary piston of FIG. 4 and a cooling fluid injector;

FIG. 6

a schematic view of an underside of a piston according to another other embodiment;

FIG. 7

a sectional view through the exemplary piston of FIG. 6 and a cooling fluid injector;

FIG. 8

a detail of a sectional view through an exemplary drogue;

FIG. 9

a detail of a sectional view through another exemplary drogue;

FIG. 10

a detail of a sectional view through another exemplary drogue; and

FIG. 11

a section of a sectional view through another exemplary drogue.

The embodiments shown in the figures are at least partially identical, so that similar or identical parts are provided with the same reference numerals and to the explanation of which reference is also made to the description of the other embodiments or figures in order to avoid repetition.

The FIG. 1 shows purely schematically an underside of a piston 10. The piston 10 may in an internal combustion engine, for example, a motor vehicle, in particular commercial vehicle, includes his. The commercial vehicle may preferably be a truck or a bus.

The piston 10 has two piston pin bosses 12, 14. The piston pin bosses 12, 14 serve to receive a piston pin (not shown). The piston pin connects the piston 10 articulated, in particular pivotally, with a connecting rod (not shown).

The piston 10 also has an inlet channel 16. The inlet channel 16 opens into an inlet 28 of an internal piston cooling channel 20 (see FIG. 2 ). The inlet channel 16 and an outlet 18 of the piston cooling channel 20 may be arranged opposite each other with respect to a central longitudinal axis of the piston 10. Intake passage 16 is configured to supply a cooling fluid, for example, oil, to an inlet 28 of inner piston cooling passage 20. The piston cooling passage 20 extends inside the piston 10. Cooling fluid in the piston cooling passage 20 cools the piston 10 during operation from the inside. In order to ensure sufficient cooling of the piston 10 at different piston speed, sufficient cooling fluid must be supplied via the inlet channel 16 to the piston cooling channel 20. The outlet 18 serves to discharge the cooling fluid from the piston cooling passage 20, for example into a crank chamber of the internal combustion engine.

The FIG. 2 shows an eccentric section through the piston 10 in the region of the inlet channel 16. As shown, the inlet channel 16 is partially formed in a drogue 22. The drogue 22 is formed on an underside 24 of the piston 10. It may also be possible to manufacture the drogue 22 as a separate component and, for example, releasably connect it to a bottom 24 of the piston 10. The drogue 22 may be made of the same material as the piston 10 or of another material. The drogue 22 may be partially formed by a portion of a piston shaft 26.

The drogue 22 may for example have an axial extent parallel to the piston center axis or height H of less than 60 mm, in particular in a range between 5 mm and 40 mm. The height H may be measured from the bottom 24 of the piston 10.

An inlet opening of the inlet channel 16 has a larger flow cross-section than an outlet opening of the inlet channel 16. The inlet channel 16 opens with its outlet opening into an inlet 28 of the piston cooling channel 20. The inlet channel 16 tapers in FIG Catching horn 22 in a direction to the piston cooling passage 20. In particular, the inlet channel 16, as shown, funnel-shaped. In particular, a peripheral surface 30 may include an acute angle (taper angle) α with a central longitudinal axis of the intake port 16. The taper angle α can in particular be greater than 0 ° and less than 45 °, in particular between 5 ° and 30 °.

The enlarged inlet opening of the inlet channel 16 allows an increased degree of capture of cooling fluid injected from a cooling fluid injector 32 in a direction toward the drogue 22. In addition, the drogue 22 protects cooling fluid within the intake passage 16 from splash and swirl fluid, for example, oil thrown from the crankshaft toward the piston 10, for example. Thus, the cooling fluid within the inlet channel 16 is less affected.

The FIG. 3 shows an alternative embodiment in which the drogue 22 'is formed so that the inlet channel 16 opens along its entire circumference with a radius R in the inlet 28 of the piston cooling passage 20. The radius R may for example be less than 30 mm, in particular between 5 mm and 20 mm. The drogue 22 'of the embodiment according to FIG. 3 may have a height corresponding to the height H of the drogue 22 of the embodiment FIG. 2 equivalent. Alternatively or additionally, the drogue 22 'of the embodiment according to FIG. 3 a taper angle corresponding to the taper angle α of the embodiment FIG. 2 equivalent.

In particular, the present application is directed to promoting a flow of cooling fluid within the intake passage 16 in a direction toward the piston cooling passage 20. To accomplish this, the inlet channel 16 and / or the cooling fluid injector 32 may be specially configured as described below by way of example.

For example, to reduce cooling fluid friction within the intake passage 16, the surface of the peripheral surface 30 of the intake passage 16 may be treated. In particular, the treatment may cause a reduction in surface roughness of the peripheral surface 30. Thus, the surface of the peripheral surface 30 can be smoothed and thus a cooling fluid friction of cooling fluid flowing along the peripheral surface 30 in a direction to the piston cooling passage 20 can be reduced. For example, the peripheral surface 30 may be polished at least in sections.

For example, it is also possible that the peripheral surface 30 of the inlet channel 16 is at least partially coated to reduce cooling fluid friction within the inlet channel 16. For example, the peripheral surface 30 may be coated with a coating which reduces the flow resistance of the cooling fluid and / or reduces a surface roughness of the peripheral surface 30. The coating may be, for example, a paint. It is also possible that the coating is applied, for example, by thermal spraying.

The FIGS. 4 and 5 show a further embodiment for conveying the cooling fluid flow in the inlet channel 16. Here, the inlet channel 16 a plurality of flow guide elements 34. The flow guide elements 34 are arranged symmetrically around a circumference of the inlet channel 16, for example. The flow guide elements 34 are straight. The flow guide elements 34 may extend completely or in sections between an inlet opening of the inlet channel 16 and an outlet opening of the inlet channel 16, which opens into the inlet 28. The flow guide elements 34 may help to guide the cooling fluid injected into the inlet channel 16 in a direction toward the inlet 28. It is also possible that more or less than the illustrated flow guide elements 34 are provided.

Like in the FIG. 8 is shown, the flow guide elements 34 may be formed as, in particular rounded depressions / grooves in the peripheral surface 30. As shown in FIG. 9, the flow guide elements 34 can alternatively or additionally also be formed as, in particular rounded, projections on the peripheral surface 30. A radius K of the flow guide elements 34 may be, for example, between 0.1 mm and 5 mm.

It is also possible that the flow guide elements 34 as rectangular, in particular rectangular or trapezoidal, recesses in the peripheral surface 30 (see FIG. 10 ) and / or as angular, in particular rectangular or trapezoidal, projections on the peripheral surface 30 (see FIG. 11 ) are formed.

The flow guide elements 34 designed as depressions and / or projections may have, for example, a width B of between 0.1 mm and 5 mm, for example as shown in FIGS FIGS. 10 and 11 is shown.

The side walls of the angular flow guide elements 34 (see FIGS. 10 and 11 ) may include an angle β with a normal of the peripheral surface 30 which is, for example, greater than or equal to 0 ° and / or less than or equal to 90 °.

As in the FIGS. 8 to 11 is shown, the flow guide elements 34, 36 have a height or depth V, which is for example in a range between 0.1 mm and 5 mm.

The FIGS. 6 and 7 show another further embodiment for promoting the cooling fluid flow through the inlet channel 16. The inlet channel 16 has a plurality of flow guide elements 36. The flow guide elements 36 are arranged symmetrically around a circumference of the inlet channel 16, for example. The flow guide elements 36 are helically (helically) formed about a central longitudinal axis of the inlet channel 16. The flow guide elements 36 may extend completely or in sections between an inlet opening of the inlet channel 16 and an outlet opening of the inlet channel 16, which opens into the inlet 28. Similar to the flow guide elements 34 according to the embodiment of the FIGS. 4 and 5 For example, the flow guide elements 36 may help to direct the cooling fluid injected into the inlet channel 16 in a direction toward the inlet 28. It is also possible that more or less than the illustrated flow guide elements 36 are provided.

The flow guiding elements 36 may be in the form of, in particular rounded or angular, recesses in the peripheral surface 30 (see FIG FIGS. 8 and 10 ) and / or as, in particular rounded or angular, projections or protrusions on the peripheral surface 30 (see FIGS. 9 and 11 ) be formed.

In the Figures 5 and 7 are the flow guide elements 34 and 36 in combination with the drogue 22 ', with reference to the FIG. 3 described. It is of course also possible, the flow guide elements 34 and 36, for example, in the drogue 22, with reference to the FIG. 2 was described to integrate.

It is also possible to promote the cooling fluid flow in the inlet channel 16 by combining a surface treatment, a coating, at least one flow guide elements 34 and / or at least one flow guide elements 36.

Alternatively or additionally to the promotion of the flow of cooling fluid in the inlet channel 16, the cooling fluid injector 32 may also be specially designed, as in FIGS FIGS. 2, 3 . 5 and 7 is shown by way of example. The cooling fluid injector 32 may include an injector 38. The injection nozzle 38 may be formed so that upon injection of the cooling fluid, a swirl is imparted to the cooling fluid. As a result, the injection jet can be stabilized and less susceptible to distractions caused by splash and panschfluid. In particular, the injection nozzle 38 may be provided with at least one helically shaped swirl element 40 in order to impart a swirl to the cooling fluid during injection. The swirl elements 40 may be formed, for example, as depressions and / or as protrusions in the injection nozzle 38.

The invention is not limited to the preferred embodiments described above. Rather, a variety of variants and modifications is possible, which also make use of the inventive idea and therefore fall within the scope. In particular, the invention also claims protection of the subject matter and the features of the subclaims independently of the claims referred to. In particular, the features of independent claim 1 are independently disclosed. In addition, the features of the dependent claims are also disclosed independently of all the features of independent claim 1 and, for example, independently of the features relating to the presence and / or the configuration of the piston, the cooling fluid channel and / or the inlet channel of independent claim 1. In particular, the design of the cooling fluid injector is also disclosed regardless of the presence and / or configuration of the piston.

LIST OF REFERENCE NUMBERS

10

piston

12

Piston pin boss

14

Piston pin boss

16

inlet channel

18

outlet

20

Piston cooling channel

22

drogue

24

bottom

26

piston shaft

28

inlet

30

peripheral surface

32

Cooling fluid injection device

34

Flow guide element

36

Flow guide element

38

injection

40

swirl element

α

taper angle

β

Flow element angle

B

width

H

height

K

radius

R

radius

V

Height / depth

Claims (15)

Piston (10) for an internal combustion engine, comprising: an inner piston cooling passage (20) for cooling the piston (10); and an inlet channel (16) which opens into an inlet (28) of the piston cooling channel (20), wherein a flow cross-section of the inlet channel (16) in a direction to the inlet (28) of the inner piston cooling channel (20) at least partially, in particular funnel-shaped, is tapered and the inlet channel (16) is additionally designed to convey a cooling fluid flow to the inlet (28) of the internal piston cooling channel (20). A piston (10) according to claim 1, wherein: the inlet channel (16) is at least partially surface-treated, in particular for reducing a surface roughness, preferably polished. A piston (10) according to claim 1 or claim 2, wherein: the inlet channel (16) is coated with a flow resistance-reducing and / or a surface roughness-reducing coating, in particular by thermal spraying. Piston (10) according to one of the preceding claims, wherein: the inlet channel (16) has at least one flow guide element (34; 36) for guiding the cooling fluid in a direction to the inlet (18) of the piston cooling channel (20). A piston (10) according to claim 4, wherein: the at least one flow guide member (34; 36) is formed as a groove in a peripheral surface (30) of the inlet duct (16); and or the at least one flow guide element (34; 36) is designed as a projection, in particular as a guide fin, on a peripheral surface (30) of the inlet channel (16). A piston (10) according to claim 4 or claim 5, wherein: the at least one flow guide member (34; 36) extends in a direction toward the inlet (28) of the inner piston cooling passage (20); and or the at least one flow-guiding element (34; 36) extends in a straight-line and / or at least partially helical manner at least in sections. A piston (10) according to any one of claims 4 to 6, wherein: the at least one flow guide element (34; 36) has a plurality of, in particular symmetrically, flow guide elements (34; 36) arranged around a circumference of the inlet channel (16). Piston (10) according to one of the preceding claims, wherein: the inlet channel (16) is at least partially formed by a drogue (22) which is connected to a bottom (24) of the piston (10). A piston (10) according to claim 8, wherein: the drogue (22) integrally formed integrally with the underside (24) of the piston (10) or formed separately and with the bottom (24), in particular releasably connected. A piston (10) according to claim 8 or claim 9, wherein: the drogue (22) and the bottom (24) of the piston (10) are made of the same material or different materials; and or the drogue (22) has a height (H) greater than 0 mm and / or less than 60 mm, in particular in a range between 5 mm and 40 mm. A piston (10) according to any one of claims 8 to 10, wherein: the drogue (22) is at least partially formed by a piston skirt (26). Piston (10) according to one of the preceding claims, wherein: the inlet channel (16) tapers at least in sections at an angle (α) greater than 0 ° and / or less than 45 °, in particular between 5 ° and 30 °, to a longitudinal axis of the inlet channel (16); and or the inlet channel (16) rounded in the inlet (28) of the piston cooling channel (20) opens, in particular with a radius (R) greater than 0 mm and / or smaller than 30 mm, preferably between 5 mm and 20 mm. Device having a piston (10) (in particular) according to one of the preceding claims; and a cooling fluid injector (32) directed to an inlet port of the inlet passage (16) and configured to inject the cooling fluid with a swirl. Apparatus according to claim 13, wherein: the cooling fluid injection device (32) has an injection nozzle (38) with at least one swirl element (40), in particular a helical groove and / or a helical projection, which is designed to impart a twist to the cooling fluid. Motor vehicle, in particular commercial vehicle, with a piston (10) according to one of claims 1 to 12 or a device according to claim 13 or 14.

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