Crankshaft bearing for an internal combustion engine

Crankshaft bearings suitable for a reciprocating piston-type internal combustion engine having multiple cylinders are arranged in a housing made of a light metal alloy and include bearing bores for a crankshaft crank pins of a crankshaft. The bores having first and second bearing sections with first and second thrust bearings extending across a longitudinal plane of the crankshaft on both sides of a bearing parting plane. The second thrust bearings are part of a crankshaft bearing bridge connected to a crankcase. At least a portion of two thrust bearings of the crankshaft bearing bridge having neighboring or adjoining bore halves of the bearing bores is supported by connecting elements. The thrust bearings of the internal combustion engine open into longitudinal walls of the crankshaft bearing bridge with local widened areas in between.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of German Application No. 10 2004 061 684.1-13, filed Dec. 22, 2004, the disclosure of which is expressly incorporated by reference herein. This application is also related to U.S. application Ser. No. 11/313,754 (028987.56989US) in the name of Paul et al. filed concurrently herewith.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention relates to a crankshaft bearing for a reciprocating, piston-type, internal combustion engine having multiple cylinders arranged in a housing made of a light metal alloy, including bearing bores for crank pins of a crankshaft and first and second bearing sections with first and second thrust bearings running across a longitudinal plane of the crankshaft on both sides of a bearing parting plane, said second thrust bearings being part of a crankshaft bearing bridge connected to a crankcase.

A crankshaft bearing for an internal combustion engine is shown in DE 34 26 208 C1. A crankcase and a bearing crown attached thereto, forming part of a crankshaft bearing bridge, are made of a light metal alloy. The bearing crowns are configured as a cast sheathing for ferrometallic cores, with the cores contributing to an increase in rigidity of the bearing crowns and/or the crankshaft bearing bridge and also reducing the noise-producing bearing play between the bearing bore and the bearing pin of a crankshaft.

DE 43 30 565 C1 describes a crankshaft bearing which is provided in a housing made of a light metal alloy in an internal combustion engine and includes a bearing bore for a crank pin. With this crankshaft bearing, a device is effective in reducing the increased bearing play between the bearing bore and crank pin. This device is configured as a ring-like compensator element which operates between the bearing bore and the crank pin and is made of a material having a relatively large coefficient of thermal expansion.

Furthermore, bearing bridges for internal combustion engines are described in DE 22 57 651 and EP 0 038 560, where neighboring thrust bearings are supported only by longitudinal walls and/or longitudinal side members.

An object of the present invention is to provide a crankshaft bearing bridge for an internal combustion engine which is characterized by a high strength and low-noise bearing of the crankshaft with a simple design.

According to the present invention, this object can be achieved by providing that at least a portion of neighboring bore halves of the second thrust bearings of the crank shaft bearing bridge having bearing bores are supported by connecting elements, and the second thrust bearings of the internal combustion engine open into longitudinal walls of the crankshaft bearing bridge with local widened areas in between.

The main advantages achieved with the present invention include the fact that, due to the particular structural configuration of the crankshaft bearing bridge made of a light metal alloy, the bridge is advantageously and especially rigid and strong with a low weight. The rigid frame structure with the connecting elements between the thrust bearings of the crankshaft bearing bridge can be implemented with a low complexity without additional equipment that would cause bimetal effects. The connecting elements and/or the walls forming them not only act as an oil plane but also these connecting elements are arranged in such a way that they result in relatively large ventilation cross-sections, thereby reducing pump losses. Furthermore, this frame structure in combination with the thermally treated thrust bearings made of the light metal alloy contributes to a uniform, controlled increase in the bearing bore over the operating temperature of the internal combustion engine, i.e., this at least reduces the ovalization of said bearing bore, which would otherwise be the case.

DETAILED DESCRIPTION OF THE DRAWINGS

An internal combustion engine1of the reciprocating piston-type having multiple cylinders is configured for installation in a motor vehicle (not shown) and includes two cylinder rows2,3in a V-shaped arrangement in which the pistons4,5operate. The pistons4,5are connected by respective connecting rods6,7to a crankshaft8which rotates in the direction of arrow A and is accommodated by crankshaft bearings9. The crankshaft bearings9are arranged in a housing10made of a light metal alloy and have bearing bores11for crank pins12of the crankshaft8. In addition, a first bearing section13and a second bearing section14with first thrust bearings15and second thrust bearings16,17,18,19and20(FIG. 2) are provided on both sides of a bearing parting plane B-B. The first thrust bearings15are integrated into a crankcase15′ configured above the parting plane B-B, whereas the second thrust bearings16,17,18,19and20are part of a crankshaft bearing bridge21, also known as a “bed plate.”

The second thrust bearings16,17,18,19and20extend across a central longitudinal plane C-C of the crankshaft8and are equipped with bore halves22of the bearing bores11. Neighboring (or adjoining) thrust bearings16and17,17and18,18and19,19and20are supported by connecting elements23, and at least the thrust bearings17through19(which may also be referred to as bearing crowns) open into longitudinal walls25,26of the crankshaft bearing bridge21through local Y-shaped widened areas24. In other words, the side walls27,28of the thrust bearing17, for example, become wider with legs29,30toward the longitudinal walls25,26of the crankshaft bearing bridge21.

FIG. 2shows that the thrust bearings16,17,18,19and20, the connecting elements23and the longitudinal walls25,26of the crankshaft bearing bridge21are combined structurally to result in a rigid frame structure. For example, connecting element23, which is provided between the two neighboring thrust bearings16,17, has two element walls31,32(FIG. 3) that are separate from one another and are relatively thin walled and profiled. The element wall32has a curved arc which guides the oil lubricant, and the element wall31has an approximately horizontal T shape which increases its strength, where the free ends33,34of the respective element walls31,32act as oil planes for connecting rods6,7moving between the thrust bearings16,17, for example, their stripper contours are labeled as Ak1and Ak2. In addition, as seen inFIG. 3, the element walls31,32are configured and arranged to yield relatively large ventilation cross-sections35,36(arrows Pf1and Pf2) between the respective longitudinal walls25,26.

FIG. 6shows how the strength properties of the thrust bearings16,17,18,19and20are optimized by a targeted temperature treatment thereof. The strength properties are influenced in a positive sense by controlled cooling (directed solidification of the light metal melt) of the crankshaft bearing bridge21at the time of manufacture, namely by applying first cooling elements37and second cooling elements38, for example., to the side walls27,28and/or four halves22of the thrust bearings16,17,18,19and20. The first and second cooling elements37,38are made of a ferromagnetic material, with the first cooling elements37being plates which are attached to the side walls27,28on both sides of the thrust bearings. For example, bearing17. However, the second cooling elements38are designed as cylinders having a circular cross-section and are provided with the shape of the bore halves22of the thrust bearings16,17,18,19and20.

Relief recesses39are integrated into the thrust bearings16,17,18,19and20of the crankshaft bearing bridge21(FIG. 5). These relief recesses are provided beneath the bore halves22in the thrust bearings. The relief devices39, the size of which can be determined empirically or by calculation, are a U-shaped cross-section and extend between through-bores40and41which serve to accommodate fastening screws. The crankshaft bearing bridge21is held in position on the crankcase15′0of the internal combustion engine1by these fastening screws.