DE102018100336A1 - Piston for an internal 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 of 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. 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 °, to 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 injection device, which is adapted to the Cooling fluid with a swirl (eg helical flow and / or rotation about an axis of the cooling fluid jet) to inject. 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.

• 1 eine schematische Ansicht einer Unterseite eines Kolbens gemäß einem Ausführungsbeispiel;
• 2 eine Schnittansicht durch den beispielhaften Kolben und eine Kühlfluideinspritzeinrichtung;
• 3 eine Schnittansicht durch einen Kolben gemäß einem weiteren Ausführungsbeispiel und eine Kühlfluideinspritzeinrichtung;
• 4 eine schematische Ansicht einer Unterseite eines Kolbens gemäß einem weiteren Ausführungsbeispiel;
• 5 eine Schnittansicht durch den beispielhaften Kolben von 4 und eine Kühlfluideinspritzeinrichtung ;
• 6 eine schematische Ansicht einer Unterseite eines Kolbens gemäß einem weiteren anderen Ausführungsbeispiel;
• 7 eine Schnittansicht durch den beispielhaften Kolben von 6 und eine Kühlfluideinspritzeinrichtung;
• 8 einen Ausschnitt einer Schnittansicht durch einen beispielhaften Fangtrichter;
• 9 einen Ausschnitt einer Schnittansicht durch einen weiteren beispielhaften Fangtrichter.
• 10 einen Ausschnitt einer Schnittansicht durch einen weiteren beispielhaften Fangtrichter; und
• 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:

• 1 a schematic view of an underside of a piston according to an embodiment;
• 2 a sectional view through the exemplary piston and a cooling fluid injector;
• 3 a sectional view through a piston according to another embodiment and a cooling fluid injector;
• 4 a schematic view of an underside of a piston according to another embodiment;
• 5 a sectional view through the exemplary piston of 4 and a cooling fluid injector;
• 6 a schematic view of an underside of a piston according to another other embodiment;
• 7 a sectional view through the exemplary piston of 6 and a cooling fluid injector;
• 8th a detail of a sectional view through an exemplary drogue;
• 9 a section of a sectional view through another exemplary drogue.
• 10 a detail of a sectional view through another exemplary drogue; and
• 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 1 shows purely schematically a bottom of a piston 10 , The piston 10 can be included in an internal combustion engine, for example, a motor vehicle, in particular commercial vehicle. The commercial vehicle may preferably be a truck or a bus.

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

The piston 10 also has an inlet channel 16 on. The inlet channel 16 flows into an inlet 28 an internal piston cooling channel 20 (please refer 2 ). The inlet channel 16 and an outlet 18 of the piston cooling channel 20 may be opposite each other with respect to a central longitudinal axis of the piston 10 be arranged. The inlet channel 16 is to formed, a cooling fluid, for example oil, to an inlet 28 the internal piston cooling channel 20 supply. The piston cooling channel 20 extends inside the piston 10 , Cooling fluid in the piston cooling channel 20 cools the piston 10 during operation from the inside. To ensure adequate cooling of the piston 10 At different piston speeds, ensure sufficient cooling fluid is available through the inlet port 16 to the piston cooling channel 20 be supplied. The outlet 18 serves to drain the cooling fluid from the piston cooling channel 20 , For example, in a crank chamber of the internal combustion engine.

The 2 shows an eccentric section through the piston 10 in the area of the inlet channel 16 , As shown, the inlet port is 16 partly in a drogue 22 educated. The drogue 22 is at a bottom 24 of the piston 10 formed. It may also be possible to use the drogue 22 as a separate component to manufacture and, for example, detachable with a bottom 24 of the piston 10 connect to. The drogue 22 can be made of the same material as the piston 10 or made of a different material. The drogue 22 may be sections of a section of a piston stem 26 be formed.

The drogue 22 For example, 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 can starting from the bottom 24 of the piston 10 be measured.

An inlet opening of the inlet channel 16 has a larger flow area than an outlet opening of the inlet channel 16 , The inlet channel 16 opens with its outlet opening in an inlet 28 of the piston cooling channel 20 , The inlet channel 16 tapers in the drogue 22 in a direction to the piston cooling channel 20 , In particular, the inlet channel 16 , as shown, funnel-shaped. In particular, a peripheral surface 30 an acute angle (taper angle) α with a central longitudinal axis of the inlet channel 16 lock in. The taper angle α may 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 coming from a cooling fluid injector 32 in one direction to the drogue 22 is injected. In addition, the drogue protects 22 Cooling fluid within the inlet channel 16 before injection and panschfluid, for example oil, for example, from the crankshaft in the direction of the piston 10 is thrown. Thus, the cooling fluid within the inlet channel 16 less influenced.

The 3 shows an alternative embodiment in which the drogue 22 ' is designed so that the inlet duct 16 along its entire circumference with a radius R in the inlet 28 of the piston cooling channel 20 empties. 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 3 may have a height that is the height H the funnel 22 of the embodiment according to 2 equivalent. Alternatively or additionally, the drogue 22 ' of the embodiment according to 3 have a taper angle, the taper angle α of the embodiment according to 2 equivalent.

The present application is particularly directed to controlling a flow of cooling fluid within the intake passage 16 in a direction to the piston cooling channel 20 to promote. To achieve this, the inlet duct 16 and / or the cooling fluid injector 32 be specially designed, as described below by way of example.

For example, a cooling fluid friction within the intake passage 16 can reduce the surface area of the peripheral surface 30 of the intake channel 16 be treated. In particular, the treatment may be to reduce a surface roughness of the peripheral surface 30 effect. This allows the surface of the peripheral surface 30 be smoothed and thus a cooling fluid friction of cooling fluid, along the peripheral surface 30 in a direction to the piston cooling channel 20 flows, be reduced. For example, the peripheral surface 30 be at least partially polished.

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

The 4 and 5 show a further embodiment for promoting the cooling fluid flow in the inlet channel 16 , Here is the inlet channel 16 several flow guide elements 34 on. The flow guide element 34 are around a circumference of the inlet channel 16 for example, arranged symmetrically. The flow guide elements 34 are straightforward. The flow guide elements 34 can be completely or partially between an inlet opening of the inlet channel 16 and an outlet port of the intake passage 16 that in the inlet 28 flows out. The flow guide elements 34 can help in the intake channel 16 injected cooling fluid in a direction to the inlet 28 respectively. It is also possible that more or less than the illustrated flow guide elements 34 are provided.

Like in the 8th is shown, the flow guide elements 34 as, in particular rounded depressions / grooves in the peripheral surface 30 be educated. Like in the 9 is shown, the flow guide elements 34 alternatively or additionally as, in particular rounded, projections on the peripheral surface 30 be educated. A radius K the flow guide elements 34 For example, it can be between 0.1 mm and 5 mm.

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

The formed as depressions and / or projections flow guide elements 34 can, for example, a width B between 0.1 mm and 5 mm, as exemplified in the 10 and 11 is shown.

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

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

The 6 and 7 show another alternative embodiment for promoting the cooling fluid flow through the inlet channel 16 , The inlet channel 16 has several flow guide elements 36 on. The flow guide elements 36 are around a circumference of the inlet channel 16 for example, arranged symmetrically. The flow guide elements 36 are helical (helical) about a central longitudinal axis of the inlet channel 16 educated. The flow guide elements 36 can be completely or partially between an inlet opening of the inlet channel 16 and an outlet opening of the inlet channel 16 in the inlet 28 flows out. Similar to the flow guide elements 34 according to the embodiment of the 4 and 5 can the flow guide elements 36 help in the intake channel 16 injected cooling fluid in a direction to the inlet 28 respectively. It is also possible that more or less than the illustrated flow guide elements 36 are provided.

The flow guide elements 36 can as, in particular rounded or angular, recesses in the peripheral surface 30 (please refer 8th and 10 ) and / or as, in particular rounded or angular, projections or projections on the peripheral surface 30 (please refer 9 and 11 ) be formed.

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

It is also possible to control 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 to promote.

Alternatively, or in addition to the promotion of cooling fluid flow in the inlet channel 16 may also be the cooling fluid injector 32 be specially trained, as in the 2 . 3 . 5 and 7 is shown by way of example. The cooling fluid injector 32 can an injector 38 respectively. The injector 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 with at least one helically shaped swirl element 40 be provided to impart a swirl on the cooling fluid during injection. The twist elements 40 For example, as depressions and / or as protrusions in the injection nozzle 38 be educated.

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 subclaims independent of all 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 disclosed. 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

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19736135 C1 [0003]
• EP 2348207 A2 [0004]

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). Piston (10) after Claim 1 in which: the inlet channel (16) is surface-treated at least in sections, in particular for reducing a surface roughness, preferably polished. Piston (10) after Claim 1 or Claim 2 wherein: the inlet channel (16) is coated with a drag 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). Piston (10) after 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). Piston (10) after 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 rectilinear and / or at least partially helical manner at least in sections. Piston (10) according to one of Claims 4 to 6 in that: 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). Piston (10) after Claim 8 wherein: the drogue (22) is integrally formed integrally with the underside (24) of the piston (10) or formed separately and connected to the underside (24), in particular releasably connected. Piston (10) after Claim 8 or Claim 9 wherein: the drogue (22) and the bottom (24) of the piston (10) are made of the same 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. Piston (10) according to 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. Device after Claim 13 wherein: the cooling fluid injector (32) comprises an injector (38) having at least one swirl element (40), in particular a helical groove and / or a helical projection adapted to impart a twist to the coolant 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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