WO2008120227A1

WO2008120227A1 - Thrust bearing for crankshaft

Info

Publication number: WO2008120227A1
Application number: PCT/IN2008/000178
Authority: WO
Inventors: Narendra Kumar Jain; Hemant Ambadas Malekar; Kedar Digambar Gokhale
Original assignee: Tata Motors Limited
Priority date: 2007-03-29
Filing date: 2008-03-24
Publication date: 2008-10-09
Also published as: ZA200906750B

Abstract

The invention relates to thrust washers (2) used in an internal combustion engine to provide axial support of the crankshaft, wherein only lower thrust washers (2) on both sides of the main bearing cap (1) are provided, and upper thrust washers on both sides of the main bearing wall (3) of the crankcase are eliminated. Undercuts (5) on both sides of the main bearing cap (1) along its internal diameter are provided to accommodate the thrust washers (2). The difference in width of main bearing wall (3) and machined width of main bearing cap (1) prevents movement of the thrust washers (2) along with the crankshaft. Various ways of mounting two thrust washers (2) are also devised in this invention.

Description

THRUST BEARING FOR CRANKSHAFT

FIELD OF INVENTION

This invention relates to an Internal Combustion (IC) Engine intended for cost effectiveness through elimination of non value adding components and simplification of the manufacturing processes. It deals more particularly with the provision of axial thrust bearing for crankshaft and its locking arrangement which results in simplified machining and assembly of crankcase.

BACKGROUND OF INVENTION

In an Internal Combustion Engine, the crankshaft is supported laterally on main journal bearings and axially on thrust bearings housed at one of the main bearing wall [8] in the crankcase and corresponding main bearing cap [7]. Fig.3 Shows a conventional crankcase where two half round thrust washers [9, 10] are used on each side of the said thrust main bearing wall [8] and corresponding main bearing cap [7]. The machining of seating surfaces for these thrust washers on main bearing wall as well as on main bearing cap is done on assembly of crankcase with main bearing caps. The two upper thrust washers fit in the crankcase on each side of the main bearing wall, and two lower thrust washers fit on the each side of thrust main bearing cap.

In the above said conventional arrangement with two semicircular thrust washers on each side, often the initial thrust support is provided either by upper or lower washer due to the difference in their thickness.

Further, the thrust washers for main bearing cap and main bearing wall are of different shape / profile to prevent them from rotating along with the crankshaft^ This arrangement increases the requirement of variety of thrust washers, complexity in crankcase machining and engine assembly time thereby increases the overall cost of unit.

GB 806373 describes a crankshaft bearing assembly comprising a thrust washer extending around more than a semi-circle for part of it to be held in a recess in the block and bearing cap. Locking tongues are provided to prevent rotation of the washers with the crankshaft and corresponding notch is provided in the bearing cap, which makes the system more complex.

OBJECTS OF INVENTION

The main object of this invention is to provide an internal combustion engine with improved thrust bearing which provides necessary and sufficient bearing area to address the axial thrust loads.

Yet another object of this invention is to provide an internal combustion engine with reduced number of parts, reduced machining and reduced time for assembly.

Yet another object of this invention is to provide an internal combustion engine which is simple in construction and cost effective.

STATEMENT OF INVENTION

An internal combustion engine comprising mainly of crankcase, cylinder head, piston, connecting rod, and crankshaft, said crankcase is provided with at least two main bearing caps wherein thrust washers are provided only on both sides of at least one main bearing cap corresponding to the thrust main bearing wall. Internal combustion engine wherein said thrust washers are provided on suitable^ undercut along the internal diameter of main bearing cap. Internal combustion engine in which width of main bearing wall at the mating surface of main bearing wall and main bearing cap is more than the width of main bearing cap to prevent the movement of thrust washers along with crankshaft.

Internal combustion engine wherein said thrust washer is provided with a projection at outer profile and said main bearing cap is provided with a corresponding cavity to ensure poka-yoke.

Internal combustion engine wherein said thrust washers on both sides of main bearing cap are assembled with the corresponding lower main bearing shell and fitted in the main bearing cap.

Internal combustion engine wherein thrust washers on both side of main bearing cap are integrated with the corresponding lower main bearing shell and fitted in the main bearing cap.

Internal combustion engine wherein one of the thrust washers is fitted on the rear face of rearmost main bearing wall of the crankcase and the other thrust washer is fitted in the undercut provided on front side of the corresponding main bearing cap.

Internal combustion engine wherein one of the thrust washers is fitted on the rear face of rearmost main bearing wall and the other thrust washer is fitted on the front face of the front main bearing wall of the crankcase and using common main bearing caps for all main bearings.

BRIEF DESCRIPTION OF INVENTION

This invention relates mainly to the thrust washers used in an internal combustion engine to provide axial support to the crankshaft wherein only lower thrust washers on both the sides of main bearing cap are provided and upper thrust washers on both sides of main bearing wall in crankcase are eliminated. Undercut on both sides of main bearing cap along its internal diameter are provided to accommodate thrust washers. The difference in the width of main bearing wall and machined width of main bearing cap prevents the thrust washer movement along with the crankshaft.

DETAILED DESCRIPTION OF INVENTION

Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.

Figure 1 shows the sectional view of the crankcase of internal combustion engine in accordance with this invention.

Figure 2 shows the detailed view of section A-A marked in Figure 1.

Now referring to Figure 1 wherein thrust washers [2] are fitted on suitable undercuts along the internal diameter of main bearing cap [1] on both sides and are provided to support the crankshaft axially. In accordance with this invention, only the lower thrust washers are provided on both sides of the main bearing cap and the upper thrust washers in corresponding main bearing wall of crankcase are eliminated and the width of main bearing wall [3] at the mating surface of main bearing wall [3] and main bearing cap [1] is more than the machined width of main bearing cap [1] to prevent the movement of thrust washers [2] along with the crankshaft, when the engine is running.

The thrust washer [2] is made up of steel backing having bearing metal cladding on the bearing surface. The bearing surface is provided with recess [2a] for enabling the lubricating oil to return back to oil sump. The steel backing seats on the main bearing cap [1] and the bearing surfaces support the crankshaft thrust collar. To ensure (Poka-Yoke) the correct assembly of thrust washers [2] on to the main bearing cap, a projection [2b] is provided on one side of thrust washers [2] which fits in the corresponding cast cavity provided in the main bearing cap [I].

Now referring to Figure 2 wherein the section A-A is shown in detail. The undercut [5] on both sides of bearing cap [1] is shown wherein the thrust washers [2] are fitted. The difference [6] in machined width at the mating face of main bearing wall [3] and main bearing cap [1] make thrust washers [2] to lock against the main bearing wall [3] thereby preventing movement of thrust washers [2] along with crankshaft.

With this arrangement, the machining on assembly of crankcase and main bearing caps for thrust washer seating is eliminated. The main bearing caps can be machined separately for the undercut. Further, different thrust washers are not used on the main bearing wall [3] of the crankcase [4], hence this arrangement reduces requirement of number of parts and variety of thrust washers. This results in reduction in both, the machining time and assembly time and thereby subsequent reduction in overall cost.

The thrust washers on both sides of main bearing cap can be assembled by means of riveting or crimping with the corresponding lower main bearing shell in order to make a single unit and this assembly can be fitted in the main bearing cap.

The thrust washers on both side of main bearing cap can be further integrated with the corresponding lower main bearing shell and this integrated bearing can be fitted in the main bearing cap.

One of the thrust washers can be fitted on the rear face of rearmost main bearing wall of the crankcase and the other thrust washer can be fitted in the undercut provided on front side of the corresponding main bearing cap. One of the thrust washers can be fitted on the rear face of rearmost main bearing wall and the other thrust washer can be fitted on the front face of the front main bearing wall of the crankcase and using common main bearing caps for all main bearings

The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

Claims

1. An internal combustion engine comprising mainly of crankcase, cylinder head, piston, connecting rod, and crankshaft, said crankcase is provided with at least two main bearing caps wherein thrust washers are provided only on both sides of at least one main bearing cap corresponding to the thrust main bearing wall.

2. Internal combustion engine as claimed in claim 1 wherein said thrust washers are provided on suitable undercut along the internal diameter of main bearing cap.

3. Internal combustion engine as claimed in claims 1 and 2 wherein width of main bearing wall at the mating surface of main bearing wall and said main bearing cap is more than the width of main bearing cap to prevent the movement of thrust washers along with the crankshaft.

4. Internal combustion engine as claimed in claims 1 to 3, wherein said thrust washer is provided with a projection at outer profile and said main bearing cap is provided with a corresponding cavity to ensure poka-yoke.

5. Internal combustion engine as claimed in claims 1 to 4, wherein said thrust washers on both sides of main bearing cap are assembled and/or integrated with the corresponding lower main bearing shell and the assembly and/or integrated bearing is fitted in the main bearing cap.

6. Internal combustion engine as claimed in claims 1 to 4, wherein one of the thrust washers is fitted on the rear face of rearmost main bearing wall of crankcase and the other thrust washer is fitted in the undercut provided on front side of the corresponding main bearing cap.

7. Internal combustion engine as claimed in claims 1 to 4, wherein one of the thrust washers is fitted on the rear face of rearmost main bearing wall and the other thrust washer is fitted on the front face of the front main bearing wall of the crankcase and using common main bearing caps for all main bearings.

8. Internal combustion engine as claimed in claims 1 to 7, wherein the thrust bearing surface is provided with one or more recesses for oil return.

9. Vehicle fitted with internal combustion engine as claimed in claims 1 to 8.

10. An internal combustion engine substantially as herein described with reference to figs. 1 and 2 of the accompanying drawings.