CN110714975A

CN110714975A - Crankshaft assembly for internal combustion engine

Info

Publication number: CN110714975A
Application number: CN201910628994.4A
Authority: CN
Inventors: K.伯恩斯特德特
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2018-07-13
Filing date: 2019-07-12
Publication date: 2020-01-21
Anticipated expiration: 2039-07-12
Also published as: CN110714975B; DE102018117028A1

Abstract

The invention relates to a crankshaft assembly for an internal combustion engine, comprising a housing-fixed bearing carrier and a crankshaft having at least one main journal which is rotatably mounted on the bearing carrier by means of a bearing shell which is fixed on the bearing carrier and forms a bearing gap with the main journal, wherein the bearing carrier has an oil supply channel which is connected to a through-opening which radially extends through the bearing shell, and wherein an oil collector chamber which is bounded axially outwards by an oil separation wall is arranged on both sides axially outside the bearing gap and is connected to at least one oil discharge channel in the bearing carrier. The invention is distinguished in that the bearing support has a circumferential annular groove on both sides axially outside the bearing gap and the main journal has a circumferential annular base on both sides axially outside the bearing gap, wherein the axially outer groove wall of the annular groove and the base wall of the associated annular base each form a section of the respective oil barrier wall separated from one another by the sealing gap.

Description

Crankshaft assembly for internal combustion engine

Technical Field

The invention relates to a crankshaft assembly for an internal combustion engine, comprising a housing-fixed bearing carrier and a crankshaft having at least one main journal which is rotatably mounted on the bearing carrier by means of a bearing shell which is fixed on the bearing carrier and forms a bearing gap with the main journal, wherein the bearing carrier has an oil supply channel which is connected to a through-hole which radially penetrates the bearing shell, and wherein an oil collector chamber which is bounded axially outwards by an oil separation wall is arranged on both sides axially outside the bearing gap and is connected to at least one oil drain channel in the bearing carrier.

Background

Such a crankshaft assembly for an internal combustion engine is known from DE 102007023107 a 1.

The crankshaft of advanced internal combustion engines is typically mounted in a bearing support of the engine housing via plain bearings. The bearing shell, which is typically formed from two half-shells, which are half-curved, is fixed in this case to the bearing support. The main journal of the crankshaft is slidably supported at the inner side of the bearing shell. A narrow bearing gap is formed between the main journal and the bearing shell, in which lubricating oil is pressed during operation. For this purpose, the oil is guided to the outside of the bearing shell via a supply channel in the bearing support. The bearing shell has one or more through-holes, through which lubricating oil penetrates into the bearing gap and in this case a lubricating film can be formed, which is required for low-friction mounting. The through-hole is arranged approximately in the axial middle of the bearing shell, so that the oil flowing in after presses the oil located in the bearing gap axially outwards on both sides, so that a continuous oil exchange is obtained. The oil escaping from the bearing gap is centrifuged by centrifugal acceleration of the rotating shaft into the crankcase, where it can reach in particular the running surface of the cylinder wall. This makes it possible to introduce into the combustion chamber, which adversely affects the development of pollutants.

In order to avoid uncontrolled centrifugal separation of the oil from the bearing gap into the crankcase, the printed literature of the type mentioned above proposes a specific design of the bearing shell. It widens axially beyond the bearing gap on both sides on its radially outer side, that is to say on the side facing the bearing support, and the axially outer side is bent in the form of a radially inwardly directed annular wall. The annular wall projects over a small sealing gap at the main journal, so that an oil collector chamber is created between the core region of the bearing shell and the annular wall, which is bounded by the annular wall as oil barrier, the wall of the axial outer portion of the core region of the bearing shell, the widening of the bearing seat side of the bearing shell and the portion of the main journal which projects beyond the bearing gap. The oil leaving the bearing gap is captured in this oil collector chamber and can be drained via an oil drain channel arranged in the lower region of the bearing support, for example, by being drained in a gravity-driven manner to an oil reservoir, in particular an oil sump, or drawn off in the context of dry sump lubrication. For this purpose, a cavity in the bearing block is arranged centrally below the bearing shell and the bearing shell is gripped on both sides on its radial outer side, so that a connection to the oil collector chamber is produced.

This arrangement has several disadvantages. On the one hand, such bearing shells are expensive to construct and the delicate components that are involved are not subject to damage during transport and assembly. In addition, the bearing capacity of the bearing is weakened by the cavity in the bearing seat. And finally in the case of the production of the bearing shell, the sealing gap between the oil separating wall and the main journal must be designed to be relatively large on account of the relatively large tolerances, so that the shut-off action sought is adversely affected. The overall arrangement is therefore already rather weak, since the sealing gap is arranged in the straight extension of the bearing gap, so that oil accelerated axially in the bearing gap can penetrate into the sealing gap in a straight path.

Disclosure of Invention

The object of the invention is to improve a crankshaft arrangement of this type in such a way that a better shut-off action is obtained against oil escaping into the crankcase with easier manufacturability and improved load-bearing capacity of the bearing.

This object is achieved in combination with the features of the preamble of claim 1 in that the bearing support has a circumferential annular groove on both sides axially outside the bearing gap and the main journal has a circumferential annular base on both sides axially outside the bearing gap, wherein the axially outer groove wall of the annular groove and the base wall of the associated annular base each form a separate section of the respective oil barrier wall by the sealing gap.

The core of the invention is that the oil collector chamber is realized only in the structure of the bearing support and the main journal, so that no changes at the bearing shell have to be carried out. The latter can instead be manufactured in normal mass-produced pieces. The bearing supports and the bearing regions of the main journals must, on the other hand, be subjected to highly precise finishing in each case, so that the construction according to the invention, that is to say the creation of the annular grooves and the annular journals, does not represent an essential additional expenditure in this context. Since the processing in this region is also always carried out with the highest degree of accuracy, the sealing gap obtained according to the invention can be designed extremely narrowly without changing the manufacturing tolerances over the entire process. This results in an improved sealing action and thus in a reduction of the oil leaving the crankcase.

The annular groove according to the invention forms the largest volume part of the oil collector chamber. In this region, an axially outer oil collector wall is formed by an axially outer groove wall of the annular groove. However, the oil collector wall extends still further radially inward up to the main journal. In this radially inner region, it is formed by a base wall of the base according to the invention, which preferably extends axially outwards up to the respective associated crank web (Wange) of the crankshaft, but nevertheless extends axially outwards beyond the annular groove. The resulting sealing gap then extends neither at the radially outer edge of the oil separating wall nor at the radially inner (as in the prior art) edge of the oil separating wall, but rather between the two limits, i.e. at the level of the boundary surface between the annular base and the edge of the annular groove, which is preferably approximately at the level of the boundary surface between the bearing shell and the bearing seat. This is not an area where oil trapped in the oil collector cavity can clog. In addition to the narrower design of the sealing gap already described above, this reduction in the stagnation pressure of the oil which is located at its inlet then also leads to a reduction in the oil which leaves the crankcase.

Furthermore, the oil collector chambers formed on both sides of the bearing shell are directly accessible by simple bores in the bearing support, so that the load-bearing capacity of the bearing is not adversely affected by the introduction of oil ducts.

Different variants are conceivable with regard to the relative profile of the annular groove and the annular base. In a particularly simple embodiment, it is provided that the axially outer groove wall of the annular groove is aligned with the base wall. The groove wall and the base wall thus form a substantially annular oil-separating wall with a sealing gap arranged approximately in between. In the case of this embodiment, the sealing gap is a sealing gap which extends straight in longitudinal section and which extends between an axially outer groove shoulder of the annular groove and a base shoulder of the annular base. The oil flowing along the oil separation wall has a movement component which is oriented almost exclusively perpendicular to the sealing gap, which makes its penetration into the sealing gap significantly more difficult.

The same sealing gap shape can also be achieved when the outer groove wall of the annular groove is not aligned with the base wall, but instead the annular base projects axially inward beyond the outer groove wall of the annular groove. The edge between the base wall and the base shoulder forms a centrifugal nose, which centrifugally separates the oil that comes to it into the annular groove away from the seal gap inlet by means of the centrifugal force of the rotating crankshaft. This means a further reduction in the amount of oil that seeps through the sealing gap.

The preferred relative profiles of the annular groove with the annular seat projecting axially inwardly and the annular seat nevertheless allow for another seal gap shape. In particular, it can be provided that, in the region of the groove wall of the annular base which projects beyond the axial outer portion of the annular groove, an annular projection which projects radially outward is arranged on the base shoulder thereof. This is based on the fact that its larger radius relative to the base shoulder acts as a more effective centrifuge nose which centrifuges oil flowing along the base wall into the annular groove. On the other hand, the axially outer wall of the annular projection forms an additional, substantially radially oriented sealing gap section together with the axially outer groove wall. In other words, in this embodiment it is then preferably provided that the sealing gap is a sealing gap which is bent in longitudinal section and has at least two regions which are at an angle to one another,

its first extending between an axially outer groove wall of the annular groove and an axially outer projection wall of the annular projection, and

its second groove shoulder axially external to the annular groove and the base shoulder of the annular seat.

The sealing gap thus folded with the substantially radial and substantially axial sealing gap sections, i.e. the (simple) labyrinth seal, has a further improved sealing action in contrast to the previously mentioned straight sealing gap. The exit of oil into the crankcase can be almost completely prohibited in this way.

As already mentioned above, the oil collector chamber is accessible via a simple bore in the bearing block, in particular in the region thereof below in the installed state. In order to avoid any weakening of the bearing block, it is preferably provided here that each of the two oil collector chambers is connected to its own oil guide channel in the bearing block. These oil conducting channels can be arranged completely axially outside the bearing gap, so that the load-bearing capacity of the bearing is not negatively influenced in any way.

Drawings

Other features and advantages of the present invention will be apparent from the following detailed description and the accompanying drawings.

Wherein:

figure 1 shows a cross-section of a first embodiment of a crankshaft assembly according to the invention,

FIG. 2 shows a cross-sectional view of a second embodiment of a crankshaft assembly according to the present invention, an

Fig. 3 shows a cross-sectional view of a third embodiment of a crankshaft assembly according to the invention.

The same reference numbers in the drawings identify the same or similar elements.

List of reference numerals

10 crankshaft assembly

12 crankshaft

12112 Main journal

14 bearing shell

14114 vias in

16 bearing support

16116 oil transfer passages

16216 oil drain passage

18 bearing clearance

20 oil collector cavity

22 annular groove

22122 axially outer groove wall

22222 axially outer groove shoulder

24 ring base

24124 base wall

24224A base shoulder

243242 projection

26 sealing the gap

26126 radial seal gap region

26226.

Detailed Description

Fig. 1 to 3 each show a sectional view through a crankshaft assembly 10 according to the invention and should first be discussed together as much as possible. Reference is then made to the individual figures for characterizing embodiments.

The crankshaft 12 is mounted in a sliding manner in the region of its main journal 121 in a bearing support 16, which is fastened to an internal combustion engine housing, which is not shown in greater detail. The sliding bearing is realized by means of a bearing shell 14, which is fastened to a bearing support 16 and forms a bearing gap 18 with respect to the main journal 121.

The bearing support 16 carries an oil supply channel 161 which ends in the through-opening 141 of the bearing shell 14. On this path, oil can be pressed under pressure from an oil reservoir, not shown, into the bearing gap 18 and in this case form the sliding film required for low-friction mounting. Here, as is shown by the arrows in the drawing, the oil flows through the bearing gap 18 from the axial interior to the both sides axially exterior, where it exits from the bearing gap. In order to avoid uncontrolled centrifugal separation of the exiting oil into the crankcase 20, an annular oil collector chamber 20 is arranged adjacent to the exit point, in which the oil collects in order to be discharged or drawn off via a coupled oil drain channel 162 which passes through the lower region of the bearing block 16 in the installed position and is preferably available for a new pump cycle. The present invention is characterized by a particular profile of the oil collector chamber 20.

To form each oil collector chamber 20, an annular groove 22 is introduced into the axially inner face of the bearing support 16 axially outside the bearing gap 18. Additionally, also axially outside the bearing gap 18, the main journal 121 is provided with an annular seat 24. The axially outer groove wall 221 forms together with the base wall 241 of the annular base 24 an axially outer limitation of the oil collector chamber 20, that is to say an effective oil barrier. The (axially outer) groove shoulder 222 of the annular groove 22 and the base shoulder 242 of the annular base form a sealing gap or at least a section of a sealing gap. Different variants of the relative arrangement of the annular groove 22 and the annular base 24 and the resulting sealing gap shape are the subject of different embodiments of fig. 1 to 3.

In the case of the embodiment of fig. 1, the axially outer groove wall 221 and the base wall 241 are aligned with one another. The resulting oil barrier wall is then a substantially straight, radially oriented annular wall, the radially outer region of which (formed by the groove wall 221) and the radially inner region of which (formed by the seat wall 241) are separated by an annular, axially extending sealing gap 26 formed between the groove shoulder 222 and the seat shoulder 224. The oil exiting from the bearing clearance 18 flows against the base wall 241 where its generally axial movement is deflected into a generally radial movement. When it reaches the seal gap 26, its axial motion component is substantially completely eliminated. The stagnation pressure existing at the entrance of the sealing gap 26 is therefore small. At most very little oil reaches the crankcase through the sealing gap 26.

In the case of the embodiment of fig. 2, the axially outer groove wall 221 and the base wall 241 are aligned with one another. Instead, the base 24 projects axially inwardly beyond the axially outer groove wall 221. The oil rising at the base wall 241 is thus centrifuged into the groove 22 by the centrifugal force of the rotating main journal 121 before it reaches the inlet of the sealing gap 26, when it reaches the base edge. In this way, the stagnation pressure prevailing at the inlet of the sealing gap 26 is reduced again, which again reduces the amount of oil leaving the crankcase.

Figure 3 shows another modification of the process. Here, the base 24 projects axially inwardly from the axially outer groove wall 221. A projection 243 is provided on the projecting part of the base shoulder 242, radially outwardly, i.e. extending into the groove 22. The axially outer projection wall thereof forms together with the axially outer groove wall 221 a radially oriented sealing gap section 261 which forms together with an axial sealing gap section 262 formed between the base shoulder 242 and the axially outer groove shoulder 222 the sealing gap 26.

In the case of this embodiment, the centrifugal nose effect (schleudenaseffekt), which has already been explained above in the context of fig. 2, is then combined with the configuration of the labyrinth seal, i.e. the seal gap 26, which is formed by the seal gap regions 261,262 which are at an angle to one another. In the case of this embodiment, it seems to be completely impossible to let the oil out into the crankcase. Instead, the oil is discharged in a targeted manner virtually completely via the oil discharge channel 162.

Of course, the embodiments discussed in the specific description and shown in the drawings are merely illustrative embodiments of the invention. Given the benefit of this disclosure, those skilled in the art are given a wide range of modification possibilities.

Claims

1. A crankshaft assembly (10) for an internal combustion engine, comprising a housing-fixed bearing support (16) and a crankshaft (12) with at least one main journal (121) which is rotatably supported at the bearing support (16) by means of bearing shells (14) which are fixed at the bearing support (16) and form a bearing gap (18) with the main journal (121),

wherein the bearing support (16) has an oil supply channel (161) which is connected to a through-opening (141) which extends radially through the bearing shell (14), and wherein an oil collector chamber (20) which is bounded axially outwards by an oil separating wall is arranged on both sides axially outside the bearing gap (18) and is connected to at least one oil drain channel (162) in the bearing support (16),

it is characterized in that the preparation method is characterized in that,

the bearing support (16) has a circumferential annular groove (22) on both sides axially outside the bearing gap (18),

and the main journal (121) has a circumferential annular base (24) on both sides axially outside the bearing gap (18),

wherein the axially outer groove wall (221) of the annular groove (22) and the base wall (241) of the associated annular base (24) each form a section of the respective oil separation wall separated from one another by a sealing gap (26).

2. The crankshaft assembly (10) as in claim 1, wherein axially outer groove walls (221) of the annular groove (22) are aligned with the base wall (241).

3. The crankshaft assembly (10) as in claim 1, wherein the annular seat (24) projects axially inwardly beyond a groove wall (221) of an axially outer portion of the annular groove (22).

4. The crankshaft assembly (10) as in any of the preceding claims, wherein the seal gap (26) is a seal gap (26) extending straight in longitudinal cross-section, extending between an axially outer groove shoulder (222) of the annular groove (22) and a base shoulder (242) of the annular base (24).

5. The crankshaft assembly (10) as in claim 3, wherein a radially outwardly projecting annular projection (243) is arranged on its base shoulder (242) in the region of the annular base (24) projecting beyond the axially outer groove wall (221) of the annular groove (22).

6. The crankshaft assembly (10) according to claim 5, characterized in that the sealing gap (26) is a sealing gap (26) bent in a longitudinal section with at least two areas (261,262) at an angle to each other,

-a first (261) thereof extending between an axially outer groove wall (221) of the annular groove (22) and an axially outer projection wall of the annular projection (243), and

-a second (262) thereof extends between an axially outer groove shoulder (222) of the annular groove (22) and a base shoulder (242) of the annular base (24).

7. The crankshaft assembly (10) as in any of the preceding claims, wherein each of the two oil collector pockets (20) is connected with its own oil drain channel (162) in the bearing block (16).