Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
1999-10-07
2001-05-15
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C123S1950HC
Reexamination Certificate
active
06231240
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a crankshaft bearing for an internal combustion engine including a bearing base portion integrally formed with the crankcase and a bearing cover mounted thereon, and including an insert of a material having a small heat expansion coefficient.
DE 195 45 000 C1 discloses a crankshaft bearing in a crankcase of an internal combustion engine having several bearing blocks each of which comprises a bearing base portion integrally formed with the crankcase and a bearing cover mounted on the bearing base portion. The crankshaft is received between the bearing base portion and the bearing cover. The bearing base portion and the bearing cover both consist of a light metal alloy such that they have a relatively low weight, but high strength and rigidity. The bearing cover includes an insert, which extends around the crankshaft and consists of an iron-metallic material, which has a low heat expansion coefficient as compared to the light metal alloy whereby the hot bearing play normally occurring in the area of the crankshaft bearing is reduced. The insert of iron metal which is cast into the bearing cover has a high heat conductivity and transfers the friction heat generated in the bearing in the area of the bearing blocks to the surrounding light metal housing. Because of the firm interconnection between insert and bearing cover, temperature stresses are generated in the bearing cover and the insert as a result of the different heat expansion coefficients of light metal and iron metal. The crankshaft bearing can be negatively affected thereby. In the worst case, the temperature stresses may lead to a failure of a component.
It is the object of the present invention to provide a crankshaft bearing, which has a low weight and high rigidity such that bearing play variations resulting from heat expansions are minimized. It is another object of the invention to reduce the noise generated by an engine.
SUMMARY OF THE INVENTION
In a bearing for a crankshaft of an internal combustion engine having a crankcase including a bearing base portion with a bearing cover mounted thereon and both the bearing base portion and the bearing cover consisting of a light metal alloy, the bearing cover has removably mounted therein, adjacent the crankshaft, an insert consisting of a bearing material which has a lower coefficient of thermal expansion than the light metal alloy of which the base bearing portion and the bearing cover consist.
In contrast to known arrangements, the insert is not cast into the bearing cover but is removably mounted thereto. As a result, some relative movement between the insert and the bearing cover is possible whereby different heat expansions of the insert and the bearing cover can be accommodated to some degree so that temperature stresses in the interface areas between the insert and the bearing cover are reduced.
It is another advantage of the arrangement according to the invention that manufacturing and assembly of the bearing is facilitated. The insert can be manufactured separately and then be inserted into the bearing cover, which subsequently can be mounted onto the bearing base together with the insert. With the separate manufacture of the insert and the bearing cover the two manufacturing steps are independent of each other. The time required for the manufacture and the manufacturing costs are reduced.
It is also possible to utilize the whole width of the bearing base to accommodate the insert permitting the use of the arrangement also with compact engines having narrow bearing bases.
In an advantageous embodiment, the insert is provided with stepped side walls through which bearing mounting bolts may extend in order to firmly mount the insert onto the bearing base on the crankcase. The stepped arrangement also has the advantage that a firm engagement is provided with the bearing cover but temperature caused expansions are permitted in the interface area between the insert and the bearing cover. In addition, the stepped side walls permit additional fixing of the insert during machining providing for improved manufacturing accuracy.
For a firm crankshaft support, preferably four bearing bolts extend through the insert. In a preferred embodiment, the four bearing bolts interconnect the insert with the crankcase so as to strengthen the jointure between the insert and the bearing cover and to increase the overall rigidity of the bearing. This arrangement also has the advantage that the bearing cover and the insert can be assembled in one step by which they are bolted together and the mounting bolts are accessible from outside the bearing.
In another advantageous embodiment (FIG.
4
), the insert is somewhat spaced from the bearing cover so that a gap is formed between the outside of the insert and the inside of the bearing cover which reduces heat and noise transfer from the insert to the bearing cover. In this case, an uncoupling of heat and noise from the bearing housing is provided for in an optimal manner.
As material to be used for manufacturing the insert any material could be considered which provides for the required strength for supporting the crankshaft and, at the same time, has a relatively small heat expansion coefficient. Those materials are particularly iron containing materials such as cast iron or compound materials.
Further advantages of the invention and suitable embodiments will be described below on the basis of the accompanying drawings.
REFERENCES:
patent: 3304134 (1967-02-01), Allen
patent: 4037888 (1977-07-01), Mirjanic
patent: 4729352 (1988-03-01), Fukuo et al.
patent: 5024189 (1991-06-01), Ushio et al.
patent: 5222467 (1993-06-01), Sasada
patent: 195 45 000 (1997-04-01), None
Brenker Gunter
Brutsch Edgar
Muller Frank
Niklas Robert
Treyz Willy
Bach Klaus J.
Daimler-Chrysler AG
Hannon Thomas R.
LandOfFree
Crankshaft bearing for an internal combustion engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Crankshaft bearing for an internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crankshaft bearing for an internal combustion engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2481867