Turbocharger bearing housing with cast-in pipes

Abstract

Conventionally, turbocharger bearing housings are cast, and then oil passageways are drilled or bored into the casting. As a result, bores are limited to straight lines extending from drill access points. Greater design flexibility is provided by pre-staging in a mold a collection of metal pipes which will define one or more of oil, air and water galleries, and then casting a bearing housing around the pipes. This provides almost unlimited freedom in shaping and locating the oil bores and other features.

Claims

1. A method of manufacturing a turbocharger bearing housing, the method comprising: preparing a pipe bundle (71, 74, 77, 78) including at least a first pipe directly supplying a turbine-end journal bearing and at least a second pipe directly supplying a compressor-end journal bearing, and casting the bearing housing (60) around the pipe bundle to form a bearing housing within which said first and second pipes are encased and respectively positioned for supplying said turbine-end journal bearing and compressor-end journal bearing.

2. The method according to claim 1, wherein said pipe bundle further comprises a thrust bearing oil feed pipe.

3. The method according to claim 1, wherein said pipe bundle defines a turbine-end journal bearing oil feed pipe, a compressor-end journal bearing oil feed pipe, and a thrust bearing oil feed pipe.

4. The method according to claim 1, wherein said turbocharger bearing housing includes bores for receiving compressor side and turbine side journal bearings and a foot adapted to mating engagement with an engine mount, further comprising at least one pipe which extends from the foot to a connection point above the journal bearings bores, at which connection point it is fluidly coupled to said turbine-end journal bearing oil feed pipe, said compressor-end journal bearing oil feed pipe, and a thrust bearing oil feed pipe.

5. The method as in claim 4, wherein said connection point serves as an oil reservoir.

6. The method as in claim 4, wherein said pipe bundle further comprises a drain pipe for draining the bearing housing through said foot.

7. The method according to claim 1, wherein at least one pipe of said pipe bundle defines an air gallery.

8. The method according to claim 1, wherein at least one pipe of said pipe bundle defines a water gallery.

9. A turbocharger bearing housing comprising: a pipe bundle (71, 74, 77, 78) made of a first metal and including at least a first pipe directly supplying a turbine-end journal bearing and at least a second pipe directly supplying a compressor-end journal bearing, and a bearing housing structure (60) comprised of a second metal cast around the pipe bundle to form a bearing housing within which said first and second pipes are encased and respectively positioned for supplying said turbine-end journal bearing and compressor-end journal bearing.

10. The turbocharger bearing housing according to claim 9, wherein said pipe bundle further comprises a thrust bearing oil feed pipe.

11. The turbocharger bearing housing according to claim 9, wherein said pipe bundle defines a turbine-end journal bearing oil feed pipe, a compressor-end journal bearing oil feed pipe, and a thrust bearing oil feed pipe.

12. The turbocharger bearing housing according to claim 9, wherein said turbocharger bearing housing includes a bore for receiving compressor side and turbine side journal bearings and a foot adapted to mating engagement with an engine mount, further comprising at least one pipe which extends from the foot to a connection point above the journal bearings bores, at which connection point it is fluidly coupled to said turbine-end journal bearing oil feed pipe, said compressor-end journal bearing oil feed pipe, and a thrust bearing oil feed pipe.

13. The turbocharger bearing housing as in claim 12, wherein said connection point serves as an oil reservoir.

14. The turbocharger bearing housing as in claim 12, wherein said pipe bundle further comprises a drain pipe for draining the bearing housing through said foot.

15. The turbocharger bearing housing as in claim 9, wherein at least one pipe of said pipe bundle defines an air gallery.

16. The turbocharger bearing housing as in claim 9, wherein at least one pipe of said pipe bundle defines a water gallery.

17. A method of manufacturing a turbocharger bearing housing, the method comprising: preparing a pipe bundle (71, 74, 77, 78) including at least a first metal pipe directly supplying a turbine-end journal bearing and at least a second metal pipe directly supplying a compressor-end journal bearing, and casting the bearing housing (60) around the pipe bundle to form a bearing housing within which said first and second metal pipes are encased and respectively positioned for supplying said turbine-end journal bearing and compressor-end journal bearing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is illustrated by way of example and not limitation in the accompanying drawings in which like reference numbers indicate similar parts, and in which:

(2) FIG. 1 depicts a section of a typical turbocharger bearing housing assembly;

(3) FIG. 2 depicts a section view of a typical turbocharger journal bearing oil feed boring scheme;

(4) FIGS. 3A,B depicts two half section views showing the inventive cast-in pipes;

(5) FIG. 4 depicts a view of the pipe bundle; and

(6) FIGS. 5A,B depict section views showing the pipe scheme for a bottom-fed bearing housing.

DETAILED DESCRIPTION OF THE INVENTION

(7) In a first embodiment of the invention, a pre-fabricated bundle of pipes is staged in a mold and the bearing housing (60) is cast around these pipes, thus providing smooth bore, curved internal oil galleries without the need for the complicated, difficult, expensive machining of the typical bearing housing oil delivery bores. This also means that pressure drops due to acute changes in flow direction and sharp edges are kept to a minimum.

(8) Pipes may be joined (typically cast or welded) together to form the pipe bundle. The joints must be sufficiently robust so as to stay together through the casting process when the molten cast iron is introduced into the mold so that the pieces are not dislodged from one another; and the joint must be tight enough that the molten cast iron does not leak into the inside of the pipe bundle.

(9) The pipes may be made of any metal that does not melt through during the iron casting process, and is preferably steel. The steel used in the pipe bundle should be low carbon (<0.1%), which makes it sufficiently ductile and quite malleable, so it is easy to manipulate into the pipe bundle architecture with gentle curves. Similar to the manner in which chaplets are used in the cast iron casting process, the pipe bundle must be oxidation free and may be coated with a thin layer of a foundry dressing, tin, or copper to ensure maximum fusion with the incoming cast iron. Because the pipe bundle is full of air (since it is fabricated simply of pipe, which has an outer casing but air in the middle) the bundle must be securely constrained in the cores for the bearing housing so that it does not float in the molten iron into an undesirable position.

(10) The melting point of grey iron is from 1150 C. to 1200 C., and the melting point of ductile cast iron is 1148 C. The melting point of low carbon steel is from 1371 C. to 1410 C., so low carbon steel makes a good fusion, or welded, joint when molten grey or ductile iron is introduced around it. To produce good fusion, the melting point of the pipe bundle must be greater than that of the incoming cast iron, so, by using low carbon steel for the pipes and cast iron for the bearing housing base metal, these conditions are met.

(11) In a first embodiment of the invention, as depicted in FIGS. 1, 3A and 3B, pipes (74, 77) shaped to fluidly connect the turbine-end journal bearing (33) and the compressor-end journal bearing (34) with the oil inlet (71) are fabricated and joined together. A pipe shaped to fluidly connect the thrust bearing (35) with the oil inlet (71) is also joined to the oil inlet. In FIG. 4, a pipe bundle consisting of the aforementioned pipes is depicted as a single entity. Each of the fluidly connecting pipes (71, 74, 77 and 78) has affixed to it a blanking and positioning cap, respectively (101, 102, 103, 104). The function of the caps is to prevent any molten cast iron from entering the pipe bundle and also to locate and constrain the pipe bundle in the cores for the casting of the bearing housing. This assembly of pipes is physically placed in the mold for a bearing housing, and molten cast iron is poured around the pipe bundle, encapsulating it.

(12) When the bearing housing is machined, the caps are machined off, leaving smooth-bore oil galleries fluidly connecting the various bearings with the oil inlet.

(13) In a variation to the first embodiment of the invention, as depicted in FIGS. 5A and 5B, a bottom fed bearing housing has an oil pressure feed pipe (83) fluidly coupling the foot (70) of the bottom of the bearing housing with a reservoir (82) near the top of the bearing housing. The reservoir (82) is fluidly coupled to the turbine-end journal bearing (33), the compressor-end journal bearing (34), and the thrust bearing (35). FIG. 5B is a section along plane B-B, cutting the vertical pipe from the lower surface (70) of the bearing housing through a reservoir (82). This section (B-B) is depicted in FIG. 5A. The function of the reservoir is to retain some oil when the engine is shut off and to provide space for the various pipes to intersect. The system of a bottom fed bearing housing need not have the reservoir (82), in which case it could have the feeder pipe (83), from the bottom of the bearing housing, fluidly couple directly into one of the other pipes (74,77,78) as long as the feeder pipe (83) is still fluidly coupled to the three bearings (33, 34, 35).

(14) Now that the invention has been described,