DE102012210530A1 - Slide bearing for connecting rod of internal combustion engine mounted in e.g. passenger cars, has lower shell that includes bearing metal layer which has lower hardness than bearing metal layer of upper shell - Google Patents

Abstract

The slide bearing (1) has a semi-cylindrical upper shell (10) and a semi-cylindrical lower shell (20), that includes a steel back and a bearing metal layer, respectively. A groove is formed centrally at the inner surface of the upper shell. The bearing metal layer of the lower shell has a lower hardness than the bearing metal layer of the upper shell. The bearing metal layer of the lower and upper shells is comprised of an aluminum alloy and a copper alloy. The alloys are incorporated with a softening component and a hardening component, respectively.

Description

The invention relates to a connecting rod sliding bearing for an internal combustion engine according to the preamble of claim 1.

Such Pleuelgleitlager, which are used for internal combustion engines in cars, trucks, motorcycles, but also in stationary engines, ships, locomotives, construction and agricultural machinery, have diameters ranging from 25 mm to 600 mm, in car and truck applications mainly from 35 mm-170 mm. The Pleuelgleitlager consist of an upper shell and a lower shell, which is called the upper shell that shell, which faces the Pleuelkörper.

The two bearing shells are usually made of a steel backing with at least one bearing metal layer. Here, a distinction is made between three-component bearings with the layer structure steel bearing metal layer overlay and two-component bearing with the layer structure steel bearing metal layer.

With the conversion of the highly loaded three-material bronze bearings to lead-free materials, the embedding capacity for foreign particles was partially lost, since lead was significantly responsible for this property and can no longer be used.

Embedding capability is understood to mean the ability of the bearing metal and the sliding layer to embed hard particles, such as machining chips or corundum, in the bearing while maintaining the operability of the bearing and avoiding seizure and wear.

Bearing shells with lubricating oil grooves are used in crankshaft bearings in the upper shell.

At the time of initial operation of an internal combustion engine, foreign particles such as chips or corundum remaining in the oil supply path of the sliding bearings (main oil passage in the engine block and the oil supply holes of the crankshaft) tend to enter the lubricating oil, which is the circumferential groove of the crankshaft main bearings is fed. The foreign particles are usually metal working chips, which are formed during the cutting of the oil path, or molding sand, which is used in the casting process or corundum, which is used for example as blasting and the like.

The foreign particles from the main oil passage pass through the oil supply groove of the main bearing into the oil supply holes of the crankshaft. From there, you will be flushed into the connecting rod bearings with the oil flow that supplies the connecting rod bearings. The rotation of the crankshaft and the deformation of the connecting rod - triggered by the translational-rotational movement of the same and the high mass forces of the piston group (piston with ring package, piston bushings, piston pin and connecting rod) at high speeds - allow the entry of foreign particles in the connecting rod bearing, even if whose smallest cross-section is larger than the bearing clearance.

Since the outlet of the oil supply hole rotates in the connecting rod bearing, the entry point of the particles is not determined in the connecting rod bearing in the circumferential direction. In the axial direction, the particle enters the connecting rod bearing at the point at which the oil outlet bore of the crankshaft is located. As a rule, the particles are deformed or split on entry into the connecting-rod bearing and then embedded as a whole or in parts in the sliding layer and in the bearing metal. This can be done both in the upper and in the lower shell and leads to damage to the bearing shell. Depending on the selected material, this damage leads to failure. Due to the high load, in particular conrod bearing upper shells use materials whose embedding capacity is so low that failure is very likely to occur.

The poorer embedability of the lead-free bronze alloys leads to higher failure rates of the sliding bearings by the foreign particles. Although bimetal-aluminum plain bearings are better suited, since the tin contained in the aluminum alloys provides similar embedment, as previously the lead in the bronze bearings. However, such steel-aluminum bearings are only limited load capacity. Therefore, in many engines only three-component bronze bearings are still used.

The DE 10 2010 022 512 A1 deals with this problem with crankshaft bearings. Along the entire axial length of at least one of the two circumferential end surfaces of one of the semi-cylindrical bearings which is in the same direction as the rotational direction of the crankshaft, an axial groove is provided between the circumferential end surface and an opposite circumferential end surface of the other semi-cylindrical bearing. The axial groove is defined by an inclined surface which extends over the entire axial width of the sliding bearing. The circumferential oil groove and the axial groove communicate with each other, and the depths of the circumferential groove in the connection portion and the axial groove in the one of the circumferential end surfaces are different from each other. The groove bottom of the circumferential groove is arranged in a position which is shifted to the side of the inner circumferential bearing surface of the groove bottom of the axial groove. The cross-sectional area of the circumferential oil groove is larger in the connection area than the cross-sectional area of the axial groove.

With this axial groove, the foreign particles should be removed from the camp. However, this embodiment of the bearing has several disadvantages. The grooves must be larger than the foreign particles, because otherwise they can not be removed from the plain bearing. This significantly reduces the bearing surface of the plain bearing, wherein the grooves also significantly affect the hydrodynamics in plain bearings. The load capacity of such a warehouse is significantly reduced. Due to the axial discharge groove also a lot of oil is lost from the bearing, which must be nachgefördert via the oil pump. This runs counter to efforts to reduce oil pump losses.

The object of the invention is to propose a connecting rod bearing for an internal combustion engine, in which foreign particles are effectively switched off, without them having to be discharged.

This object is achieved with the features of claim 1.

It is provided that the depth T of the groove of the upper shell is 0.05 to 0.2 mm and the width B> T and that the bearing metal layer of the lower shell has a lower hardness than the bearing metal layer of the upper shell. The embedding capacity of the lower shell is therefore greater than that of the upper shell.

It has been found that by combining the groove in the upper shell, which may have the more critical material, which may be lead-free bronze, for example, in the conrod bearing shell, foreign particles can be effectively eliminated with the embedding-friendly material of the lower shell.

The groove cross-section defined by B and T is preferably chosen such that it is generally larger than the cross-sectional dimensions of most foreign particles. If foreign particles are flushed into the connecting rod bearing via the oil flow, they can remain in this groove and do not penetrate into the bearing gap between crankshaft lifting pin and connecting rod bearing shell. The foreign particles can also be transported by the rotation and the inflowing oil from the upper shell into the lower shell. There, the embedding takes place in the material, which is due to its lower hardness compared to the upper shell capable of doing so without the camp fails.

Foreign particles, whose cross-sectional dimensions are larger than the groove cross-section, are embedded in the region of the groove despite the groove present in the upper shell. The material of the bearing metal layer and / or the sliding layer of the upper shell, which raises the foreign particles in the embedding, remains largely in the groove and does not run against the shaft and thus can not lead to failure.

In the solution according to the invention is a substantially smaller in cross-section and in particular flatter groove in the circumferential direction of the upper shell, as is the case with bearings for z. B. crankshafts is the case. The groove may well be smaller than the particles, it preferably has to provide only space for material thrown up by the particles. The particles are either embedded in this groove or pulled through this and then embedded in the lower shell.

Through the groove, the bearing surface of the bearing shell is reduced and also the pressure mountain in the oil film is impaired, which allows the hydrodynamic operation of the bearing. Therefore, it is necessary to choose the groove cross section as small as possible.

Preferably, the groove depth T is 0.05 to 0.1 mm. The groove width B is preferably 0.5 to 5 mm, more preferably 1.5 to 2.5 mm.

The hardness of the bearing metal layer of the lower shell is preferably ≦ 70 HB. HB refers to the Brinell hardness. It has been shown that the required embedding capacity for the foreign particles is particularly well ensured with these hardness values.

Preferably, the hardness of the bearing metal is ≤ 60 HB. The embedding capacity is thereby further improved.

Preferably, the bearing metal layer of the lower shell is made of an aluminum alloy or a copper alloy in which at least one plasticizing component is contained. With the softening component and its proportion, the hardness of the alloy is preferably adjustable to a value below 70 HB.

The Al alloy preferably has at least one plasticizing component from the group Sn, Bi.

The bearing metal of the lower shell preferably comprises an aluminum-tin alloy. The tin content influences the hardness and represents a soft phase. Both improve the embedability. Added to this are the good sliding properties of the tin. These properties enable the embedding of particles without bearing failure. Bi has similar properties to Sn.

Preferably, the tin content in the Al-Sn alloy is in the range of 4% to 30% by weight.

Preferably, the content of Bi is in the range of 1 to 10% by weight.

Further alloying elements of the Al alloy may be Cu, Si, Mn, Ni, Fe, Ti, Cr, V and / or Zr.

All alloys preferably have a hardness ≤ 70 HB. A particularly preferred alloy for the bearing metal layer is AlSn20CuMn, which has a hardness of 45 HB. Al bismuth alloys have a hardness of 45 HB.

The Cu alloy of the bearing metal layer of the lower shell preferably has at least one plasticizing component from the group Bi, graphite.

The components improve the sliding properties and embedability.

Preferably, the proportion of Bi at 1 to 10 wt .-% or that of graphite is up to 15 wt .-%.

Further alloying elements are preferably Sn, Ni, Al and / or fillers, such as. B. hexagonal BN, preferably in proportions up to max. 2 wt .-% are included. These alloying elements have the advantage that they improve the sliding properties of the bearing metal.

All alloys have a hardness ≤ 70 HB.

The bearing metal layer of the upper shell is preferably made of an Al alloy or a Cu alloy in which at least one curing component is contained. With the hardening component and the proportion, the hardness of the alloy is preferably adjustable to a value> 70 HB, in particular 80 HB.

Preferred alloys for the bearing metal layer of the upper shell are heavy-duty aluminum compounds. These usually have a low tin content <10% and the hardening component, whereby their embedding capacity is similarly impaired as that of lead-free copper alloys.

The Al alloy preferably contains at least one curing component from the group Zn, Si, Mn, Cu, Mg.

Further alloying elements of the Al alloy may be Fe, Cr, V, Zr, which are preferably present in proportions of a few tenths of a percent. These alloy components have the advantage that they can lead to a further increase in strength.

All alloys preferably have a hardness> 70 HB.

Preferred alloys are AlSi1MgMn having a hardness of about 80-90 HB and AlZn4.5Mg1 having a hardness of about 90-95 HB.

The Cu alloy preferably contains at least one curing component from the group Sn, Ni, Zn, Al, Si, Mn, Fe. Further alloy components of the Cu alloy may be Cr and Zr, which are preferably present in proportions of a few tenths of a percent. These alloy components have the advantage that they lead to an increase in strength.

All alloys preferably have a hardness of> 70 HB.

Preferred alloys are CuSn8Ni with a hardness of about 120 HB, CuSn6Bi3.5 with a hardness of about 110 HB, CuNi2Si1 with a hardness of 105 HB.

Preferably, the lower shell and / or the upper shell on the bearing metal layer on a sliding layer. The sliding layer itself has no influence on the embedding ability, since it is essentially determined by the bearing metal layer. The sliding layer may preferably be made of a Sn-Cu alloy, a Bi-Cu alloy, an Sn layer, an Al alloy or a Consist of polymer material. As a polymer material is PAI (polyamide-imide) with fillers such. B. hexagonal BN preferred. The sliding layer applied to the bearing metal layer is preferably a galvanic coating, a polymer coating or a PVD (Plasma Vapor Deposition) layer.

The groove provided in the upper shell must be positioned in such a way that it is centered on the oil outlet bore in the crankshaft crankpin.

Although the length of the groove over the circumference of the upper shell can be interpreted differently, it is preferred, in particular for manufacturing reasons, to provide a groove in the upper shell which sweeps over a center angle α of 180 °. If necessary, the foreign particles reach up to the partial surface of the upper shell and are then embedded in the lower shell.

The lower shell according to one embodiment has no groove. Such a groove is not required because the bearing metal has the required embedding capacity for the foreign particles.

According to a further embodiment, the lower shell also has on the inner surface a groove which extends over the entire inner circumference of the lower shell. This groove thus extends over a circular arc with the center angle β of 180 °. This groove in the lower shell adjoins the two ends of the groove of the upper shell, so that a closed annular groove is formed. Preferably, the groove of the lower shell has the same cross-sectional dimensions as the groove in the upper shell. This embodiment has the advantage that the foreign particles can be deposited in the groove and not even reach the sliding surfaces of the lower shell. This is particularly advantageous if the concentration of foreign particles should be high.

Preferably, the lower shell has at least one partial groove, which adjoins the groove of the upper shell and the length of a circular arc with the center angle β in the range of> 0 ° to <180 °, preferably from 1 ° to 90 °, and in particular of 1 ° to 30 ° corresponds. The partial groove has the advantage that the foreign particles are introduced into the lower shell before embedding in the lower shell a longer distance and can be distributed in this way better in the lower shell, which is also at higher foreign particle concentration advantage.

In the installed position of the connecting rod bearing, the partial groove is preferably arranged in the flow direction behind the groove of the upper shell. It can also be provided two sub-grooves, so that each groove end of the upper shell continues in a partial groove of the lower shell.

In addition, this embodiment reduces the damage to the lower shell in the embedding, since the foreign particles embed in the groove outlet forming part of the groove and there can still displace material, without this being raised too much. This embodiment is even more robust than the first embodiment.

According to a further embodiment, the groove of the upper shell extends only over a portion of the inner periphery of the upper shell, which corresponds to a circular arc with the center angle α in the range of 30 ° to <180 °, preferably from 90 ° to 170 °.

The groove preferably ends spaced on both sides in each case to the relevant partial surface of the upper shell. This embodiment is advantageous if the oil leakage is to be reduced. The recessed end opposite the two faces of the groove has the advantage that no fluid connection of the groove can be done with any existing exposure or Teilflächenfase, so that the associated oil leakage is avoided. However, the foreign particles can damage the sliding surface between Nutauslauf and exposure. However, since this is only a small damaged area and the foreign particles would probably also embed in the area in which there is still a residual groove depth, the damage to the bearing is much lower than when embedding in the sliding surface of the upper shell in the load area.

In addition, in contrast to the first embodiment, the reduction of the aerofoil fraction with a continuous groove over the entire inner circumference in the upper shell is less serious.

In the shortened groove of this embodiment, a groove end may preferably also extend up to the partial surface and, more preferably, be combined with a partial groove in the lower shell.

Preferably, the groove ends of the upper shell or the respective ends of the sub-grooves of the lower shell are formed such that the groove base rises and merges substantially continuously into the inner surface of the respective bearing shell.

The shape of the groove can basically be chosen arbitrarily. For manufacturing reasons, however, a radius contour is preferred.

Preferably, the groove cross-section is circular, arcuate, rectangular or trapezoidal. The groove cross-section can also be ellipsoidal, oval, hexagonal and with and without rounded edges. This applies to the upper and / or lower shell.

The preferred manufacturing method for the groove consists in impressing either in the blank cut or in a forming station when pressing the bearings. Alternatively, the groove can be machined even after the forming.

Preferably, none of the plain bearing shells on a transverse groove. An axial or whatever groove for discharging the foreign particles from the connecting rod bearing is not provided. The negative effect of such axial groove on the hydrodynamics and on the oil pump performance is thereby avoided.

Exemplary embodiments of the invention will be explained below.

Show it:

1 the side view of a connecting rod with upper shell and lower shell,

2 a connecting rod sliding bearing according to a first embodiment,

3a , b is a section through the upper shell of the sliding bearing according to 2 along the line AA for two embodiments,

4 a connecting rod sliding bearing according to another embodiment,

5 a Pleuelgleitlager according to another embodiment, and

6 a Pleuelgleitlager according to another embodiment.

in the 1 is a connecting rod 1 with a connecting rod bearing 3 and connecting rod eye 4 represented, which is an upper shell 10 and a lower shell 20 having. The upper shell 10 is the connecting rod body 2 facing. The two bowls 10 . 20 bump with their faces 30 together.

In the 2 is the arrangement of upper shell 10 and lower shell 20 shown in perspective according to a first embodiment. It can be seen that the upper shell 10 a groove 14 in its inner surface 16 has, which extends over the entire inner circumference and thus at both ends in the faces 30 opens. The groove 14 describes a circular arc with the center angle α of 180 °. The depth T of the groove is 0.1 mm and the width B is 0.5 mm.

The lower shell 20 is a smooth shell and has accordingly no groove. The material of the bearing metal layer 22 and the lower shell 20 has a hardness <70 HB and thus the required embedding capacity for foreign particles. A sliding layer is on the lower shell 10 not provided.

The bearing metal of the bearing metal layer 12 and the upper shell 10 can be selected according to the load of the connecting rod and therefore have a hardness greater than 70 HB. In addition, the upper shell points 10 on the bearing metal layer 12 still a sliding layer 13 on.

In the 3a and b is a cross section taken along the line AA of FIG 2 shown. The upper shell 10 consists of a steel beam 11 , a bearing metal layer 12 , z. B. a sintered layer 12 a Cu alloy with a hardening component, and a galvanized sliding layer 13 ,

The depth T of the round groove is for example 0.1 mm and is thus exclusively in the bearing metal layer 12 introduced (see 3a ). In the case of a coated shell 10 is the groove 14 with the sliding layer 13 covered, as the groove 14 preferably before applying the sliding layer 13 is introduced.

The groove 14 but could also after applying the overlay 13 and in this case is not covered with overlay material (see 3b ).

The in the 3a Dimensions shown are not to scale.

in the 4 a further embodiment is shown in which the groove 14 in the upper shell 10 describes a circular arc with a center angle α of 140 °. This ends the groove 4 at both ends of the groove 15 at a distance in front of the partial surfaces 30 , The Nutende 15 is V-shaped in plan view. The groove bottom rises continuously to the inner surface 16 at. This groove formation results when the groove is produced by plunge milling. This is the preferred method. There are also other manufacturing methods such as circular milling, embossing, curling, erosion or laser machining possible. These can lead to other groove geometries.

In the 5 a further embodiment is shown in which the groove 14 at its two ends by a partial groove 25 in the lower shell 20 has been extended. The center angle β with respect to the partial groove 25 is in the embodiment shown here in each case about 10 °. On one of the two sub-grooves 25 can be omitted in particular if they are not in the flow direction of the lubricating oil to the groove 14 followed.

In the 6 a further embodiment is shown, in which also the lower shell 20 a groove 24 with identical dimensions as the groove 14 having. The midpoint angles α and β are each 180 °.

LIST OF REFERENCE NUMBERS

1

pleuel

2

connecting rod

3

connecting rod bearing

4

connecting rod

10

Upper shell

11

steel backing

12

Bearing metal layer

13

Overlay

14

groove

15

groove end

16

palm

20

subshell

22

Bearing metal layer

24

groove

25

partial groove

26

palm

30

subarea

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 102010022512 A1 [0011]

Claims (25)

Connecting rod sliding bearing ( 1 ) for an internal combustion engine with a semi-cylindrical upper shell ( 10 ) and with a semi-cylindrical lower shell ( 20 ), whereby both shells ( 10 . 20 ) a steel backing ( 11 ) and at least one bearing metal layer ( 12 . 22 ), and wherein the upper shell ( 10 ) one centered on the inner surface ( 16 ) groove ( 14 ) having depth T and width B, characterized in that the depth T of the groove ( 14 ) Is 0.05 to 0.2 mm, and the width B> T, and that the bearing metal layer ( 22 ) of the lower shell ( 20 ) has a lower hardness than the bearing metal layer ( 12 ) of the upper shell ( 10 ). Pleuelgleitlager according to claim 1, characterized in that the depth T is 0.05 to 0.1 mm. Pleuelgleitlager according to one of claims 1 or 2, characterized in that the width B is 0.5 to 5 mm. Pleuelgleitlager according to claim 3, characterized in that the width B is 1.5 to 2.5 mm. Pleuelgleitlager according to one of claims 1 to 4, characterized in that the hardness of the lower shell ( 20 ) ≤ 70 HB. Pleuelgleitlager according to claim 5, characterized in that the hardness of the lower shell ( 20 ) ≤ 60 HB. Pleuelgleitlager according to one of claims 1 to 6, characterized in that the bearing metal layer ( 22 ) of the lower shell ( 20 ) consists of an Al alloy or a Cu alloy, in which at least one plasticizing component is contained. Pleuelgleitlager according to claim 7, characterized in that the Al alloy of the lower shell ( 20 ) contains at least one plasticizing component from the group Sn, Bi. Pleuelgleitlager according to claim 7, characterized in that the Cu alloy of the lower shell ( 20 ) contains at least one plasticizing component from the group Bi, graphite. Pleuelgleitlager according to one of claims 1 to 9, characterized in that the bearing metal layer ( 12 ) of the upper shell ( 10 ) consists of an Al alloy or a Cu alloy, in which at least one curing component is contained. Pleuelgleitlager according to claim 10, characterized in that the Al alloy of the upper shell ( 10 ) contains at least one curing component from the group Zn, Si, Mn, Cu, Mg. Pleuelgleitlager according to claim 10, characterized in that the Cu alloy of the upper shell ( 10 ) contains at least one curing component from the group Ni, Sn, Zn, Al, Si, Mn, Fe. Pleuelgleitlager according to one of claims 1 to 12, characterized in that the lower shell ( 20 ) and / or the upper shell ( 10 ) has a sliding layer on the bearing metal layer. Pleuelgleitlager according to claim 13, characterized in that the sliding layer consists of a Sn-Cu alloy, a Bi-Cu alloy, Sn, an Al alloy or a polymer material, such as PAI with filler. Pleuelgleitlager according to one of claims 1 to 14, characterized in that the upper shell ( 10 ) and / or the lower shell ( 20 ) is / are lead-free. Pleuelgleitlager according to one of claims 1 to 15, characterized in that the groove ( 14 ) of the upper shell ( 10 ) over the entire inner circumference of the upper shell ( 10 ). Pleuelgleitlager according to one of claims 1 to 16, characterized in that the lower shell ( 20 ) in the inner surface ( 26 ) a groove ( 24 ) having. Connecting rod bearing according to claim 17, characterized in that the groove ( 24 ) over the entire inner circumference of the lower shell ( 20 ). Pleuelgleitlager according to claim 17, characterized in that the groove ( 24 ) of the lower shell ( 20 ) at least one partial groove ( 25 ), which conforms to the groove ( 14 ) of the upper shell ( 10 ) and their length corresponds to a circular arc with a center angle β in the range of> 0 ° to <180 °. Pleuelgleitlager according to claim 19, characterized in that the length of the partial groove ( 25 ) corresponds to a circular arc with the center angle β in the range of 1 ° to 90 °. Pleuelgleitlager according to one of claims 1 to 20, characterized in that the groove ( 14 ) of the upper shell ( 10 ) over a portion of the circumference of the upper shell ( 10 ) whose length corresponds to a circular arc with center angle α in the range of 30 ° to <180 °. Pleuelgleitlager according to one of claims 1 to 21, characterized in that the Cross section of the groove ( 14 ) is round, rectangular or trapezoidal. Pleuelgleitlager according to one of claims 1 to 22, characterized in that the shells ( 10 . 20 ) have no transverse groove. Connecting rod with a Pleuelgleitlager according to claims 1 to 23. Use of a Pleuelgleitlagers according to one of claims 1 to 23 for internal combustion engines in passenger cars and trucks.

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