GB2427248A

GB2427248A - Turbocharger apparatus having a bearing housing with an integral heat shield

Info

Publication number: GB2427248A
Application number: GB0611622A
Authority: GB
Inventors: Malcolm George Leavesley
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-16
Filing date: 2006-06-12
Publication date: 2006-12-20
Anticipated expiration: 2026-06-12
Also published as: GB2427248B; GB0611622D0

Abstract

Turbocharger apparatus (1) comprising a compressor, a turbine (18), a compressor housing (14), a compressor housing inlet (20) for enabling air to be conducted to the compressor, a compressor housing outlet (21) for enabling air to exit the compressor housing (14), a turbine housing (16) which surrounds the turbine (18), a turbine housing inlet (28) for enabling exhaust gases from an engine to be conducted to the turbine in order to rotate the turbine (18), a bearing assembly (15) for permitting rotation of the compressor and the turbine (18), a bearing housing (7B), and a heat shield (5) for protecting the bearing assembly (15) from heat from the exhaust gases, characterised in that the heat shield (5) is formed as an integral part of the bearing housing (7B).

Description

TURBOCHARGER APPARATUS HAVING A

BEARING HOUSING WITH AN INTEGRAL HEAT SHIELD

This invention relates to turbocharger apparatus and, more especially, this invention relates to turbocharger apparatus having a bearing housing with an integral heat shield.

Turbocharger apparatus for super-charging internal combustion engines is well known. The known turbocharger apparatus usually comprises a compressor, a turbine, a compressor housing, a compressor housing inlet for enabling air to be conducted to the compressor, a compressor housing outlet for enabling air to exit the compressor housing, a turbine housing which surrounds the turbine, a turbine housing inlet for enabling exhaust gases from an engine to be conducted to the turbine in order to rotate the turbine, a bearing assembly for permitting rotation of the compressor and turbine, and a separately formed heat shield for protecting the bearing assembly from heat from the exhaust gases.

During operation of the turbocharger apparatus, heat from exhaust gases is able to travel by heat transfer around to the bearing assembly.

Turbocharger apparatus currently being developed is required to work in ever higher temperature ranges, and heat transfer to the bearing assembly becomes more of a problem. In addition, in the known turbocharger apparatus, the presence of the separate heat shield tends to prevent a required very accurate clearance between the heat shield and the turbine wheel.

It is an aim of the present invention to reduce the above mentioned problems.

Accordingly, in one non-limiting embodiment of the present invention there is provided turbocharger apparatus comprising a compressor, a turbine, a compressor housing, a compressor housing inlet for enabling air to be conducted to the compressor, a compressor housing outlet for enabling air to exit the compressor housing, a turbine housing which surrounds the turbine, a turbine housing inlet for enabling exhaust gases from an engine to be conducted to the turbine in order to rotate the turbine, a bearing assembly for permitting rotation of the compressor and the turbine, a bearing housing, and a heat shield for protecting the bearing assembly from heat from the exhaust gases, characterised in that the heat shield is formed as an integral part of the bearing housing The formation of the heat shield as an integral part of the bearing housing enables the above mentioned heat soak to the bearing assembly to be reduced because the bearing housing with the integral heat shield can be such as to cause the heat to travel from the heat shield area around outer edges of the bearing housing such that when the heat meets the outer edges of the bearing housing, outside air tends to cool the single unit of the bearing housing and the integral heat shield. This cooling helps to prevent heat travelling around the bearing housing and back down the sealing and bearing area of the bearing assembly.

The formation of the bearing housing and the heat shield as a single integral unit also allows for the bore within the bearing housing, which is for the bearings, to be perfectly machined inline with the heat shield section of the bearing housing. This allows for a very accurate heat shield section where the turbine wheel rotates. This in turn allows for a smaller gap between the heat shield section of the bearing housing and the turbine, thereby preventing hot gases from bypassing the turbine and the heat shield. The alignment of the bearing assembly and the heat shield in the turbocharger apparatus of the present invention is more accurate than in the known turbocharger apparatus where a separately formed heat shield is used. This is because the heat shield section in the present application cannot misalign with the bearing housing, and therefore a constant tolerance between the bearing housing and heat shield sections may be achieved. In the known turbocharger apparatus, the separately formed heat shield is usually produced by metal stamping. The metal stamping tends to leave very small burrs around the edges of the stamping. These small burrs act to prevent perfectly square clamping of the bearing assembly into the turbine housing. Turbocharger apparatus of the present invention is able to overcome this problem because the bearing assembly and the heat shield are formed as a single unit and the clamping areas are able to be machined.

With the turbocharger apparatus of the present invention, a single unit of the bearing housing and the integral heat shield is able to be such that it needs minimal extra machining after initial formation. Also, the machining may be such as to allow for an accurate end face of the heat shield section of the bearing housing, such as to allow guide vanes to be held if desired against the heat shield section of the bearing housing, thereby to allow for an accurate gas flow around the end section of the guide vanes.

The turbocharger apparatus of the present invention additionally advantageously allows for reduced manufacturing costs. This is because there is a reduction in the number of parts within the turbocharger apparatus of the present invention as compared with known turbocharger apparatus.

Extra machining of the single unit formed by the bearing housing and the integral heat shield is minimal. Assembly time of the individual components of the turbocharger apparatus is reduced because the bearing housing and the heat shield are formed as a single unit. The formation of the bearing housing and the heat shield as a single unit allows for the turbocharger apparatus to be manufactured more accurately than the above mentioned known turbocharger apparatus, thereby allowing for a more constant product to be produced.

Preferably, the heat shield is formed as an integral part of the bearing housing by casting. Other manufacturing methods may be employed.

The turbocharger apparatus may be one in which the integrally formed heat shield and bearing housing comprises a hollow section behind the heat shield area such that heat from the heat shield section of the bearing housing has to travel around the outer diameter of the bearing housing before being able to travel to the bearing assembly, and thereby prevents heat soak.

The turbocharger apparatus may be one in which the turbine rotates in a recess area in the heat shield part of the bearing housing and thereby allows for an accurate gas flow onto the turbine.

The turbocharger apparatus may be one in which the integrally formed heat shield and bearing housing are subsequently machined to cause a bore in the bearing housing to be in alignment with the recess area in which the turbine rotates so as to have a minimum tolerance between the heat shield part of the bearing housing and the turbine in order to prevent gas leakage between the turbine and the heat shield part.

The turbine may rotate in the recess area in the heat shield part of the bearing housing in order to allow for an accurate gas flow onto the vane area of the turbine.

The turbocharger apparatus may be one in which the integrally formed heat shield and bearing housing are subsequently machined to provide an accurate end face of the heat shield section of the bearing housing such as to allow guide vanes to be held against the heat shield section of the bearing housing, thereby to allow for an accurate gas flow around the end section of the guide vanes.

The turbocharger apparatus may be one in which the bearing assembly is an air bearing assembly or an oil feed bearing assembly.

The turbocharger apparatus may include a sealing ring mounted in the bore of the heat shield section.

The turbocharger apparatus may be one in which a cooling chamber is formed between the heat shield section and an inner wall section of the bearing housing.

The turbocharger apparatus may be one in which cooling air passes from an air bearing area of the air bearing assembly through a bore in the bearing housing section in order to cool the turbine wheel shaft and a cooling chamber section of the bearing housing, whereby heat transfer between the heat shield section of the bearing housing and the air bearing system is prevented.

The turbocharger apparatus may be one in which a cooling chamber between the bearing housing and heat shield sections is such that the cooling chamber under vacuum allows exhaust gases that may manage to pass the sealing system to be taken out of the cooling chamber, whereby the exhaust gases are prevented from entering into the air bearing section of the bearing housing.

The turbocharger apparatus may be one in which the air bearing assembly has air bearings which are under air pressure, and in which air bypass is controlled into the cooling chamber such that a vacuum may be used within a cooling chamber such to prevent side pressure on the sealing ring such to prevent the sealing ring from being pushed away from a location face.

The turbocharger apparatus may be one in which an air pipe is fitted or formed between the heat shield section and bearing housing section, whereby air is able to be drawn under vacuum into a cooling chamber, or whereby air pressure is able to be introduced into the cooling chamber.

The turbocharger apparatus may be one in which machining of the bores of the bearing housing and the sealing area in the heat shield section is such that the bores are in alignment.

The turbocharger apparatus may include a labyrinth-type sealing system. The labyrinth-type sealing system may be used instead of a sealing ring.

The turbocharger apparatus may be one in which air pressure is used in a cooling chamber in order to cool firstly the area between the bearing housing and heat shield sections, and secondly the turbine wheel shaft, and in which air is allowed to enter into the air bearing section of the bearing housing.

The turbocharger apparatus may be one which is in the form of a variable turbine area turbocharger.

The turbocharger apparatus may be used in conjunction with a twin or single turbocharger system.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 is a sectional side view of first turbocharger apparatus of the present invention; Figure 2 is a part sectional side view of second turbocharger apparatus of the present invention; and Figure 3 shows third turbocharger apparatus of the present invention.

Referring to Figure 1, there is shown first turbocharger apparatus 1.

The turbocharger apparatus 1 comprises a three part housing assembly having a compressor housing 7A, a bearing housing 7B and a turbine housing 7C. The turbocharger apparatus 1 also comprises a turbine 18 and a compressor (not shown). The compressor is mounted for rotation on a common shaft 32. The common shaft 32 may be part of the turbine 18.

The turbocharger apparatus 1 also comprises a compressor housing 14. The compressor housing 14 has a compressor housing inlet 20 for enabling air to be conducted to the compressor. The compressor housing 14 also has a compressor housing outlet 21 for enabling air to exit from the compressor housing 14. The turbocharger apparatus 1 further comprises a bearing assembly 15. The bearing assembly 15 has bearing 22. The bearing assembly 15 enables rotation of the compressor and the turbine 18.

The bearing assembly 15 has a sealing ring 4. The sealing ring 4 is mounted on the turbine 18. The sealing ring 4 prevents oil leakage from the bearing assembly 15. The sealing ring 4 also prevents hot gases entering into the bearing section of the bearing assembly 15.

The bearing assembly 15 has the bearing housing 7B. A heat shield is formed as an integral part of the bearing housing 7B. Thus the heat shield 5 is formed as an integral part of the bearing assembly 15. The heat shield 5 is formed as an integral part of the bearing housing 7B by the process of casting. Thus the bearing housing 7B and the heat shield 5 form a single cast unit. This single cast unit allows for a bore 23 within the bearing housing 7B to be machined perfectly in line with the heat shield section 24 of the bearing housing. This allows for a very accurate heat shield section where the turbine 18 rotates. This in turn allows for a smaller tolerance between the heat shield section 24 of the bearing housing and the turbine wheel 18.

The turbocharger apparatus 1 is such that the turbine 18 rotates in a recess in the heat shield area 24. This allows exhaust gases to be guided accurately onto the vane area 38 of the turbine 18. This prevents hot exhaust gases from an engine entering between the turbine 18 and the heat shield section 24 of the bearing housing.

The single cast bearing housing and the heat shield are cast such that heat formed on the heat shield section 5 from the exhaust gases has to travel from the heat shield section 5, around the outer edges 19 of the bearing housing 7B. This allows outside air to cool the casting, and thus helps to prevent heat travelling around the bearing housing casting and back down to the sealing ring 4 of the bearing assembly 15, thereby preventing heat transfer which is also known as heat soak.

The bearing assembly has an oil inlet 40 for allowing oil to lubricate the bearings and the turbine shaft 32. The bearing assembly has a oil outlet 41.

The turbocharger apparatus 1 also comprises a turbine housing 16 which surrounds the turbine 18. The turbine housing 16 receives exhaust gases from the engine (not shown) before the exhaust gases are conducted to the turbine 18. The turbine housing 16 has an inlet 28 for enabling exhaust gases to enter into a chamber 30 of the turbine housing 16, thereby I0 enabling the exhaust gases to be conducted to the turbine 18 in order to rotate the turbine 18. The turbine housing 16 has an outlet 34. The turbine housing 16 also has an end cover 35 for enabling assembly of the turbocharger apparatus 1. The end cover 35 is held in position by bolts 31.

The turbocharger apparatus 1 further comprises a variable turbine area. The variable turbine area is provided by a piston 70. The piston 70 is a slidable piston which is slidable between the chamber 30 and the turbine 18. The piston 70 is able to control the gap over the turbine 18 in order to control the speed of the turbine 18.

The sliding movement of the piston 70 is controlled by moving a lever 42. The lever 42 is connected to a rod (not shown). The rod is allowed to rotate within the bush 43. The rod is connected to part of a control system for controlling the sliding movement of the sliding piston 70. The lever 42 has a connection pin 44 for allowing connection to a control unit (not shown) of the control system.

The slidable piston 70 has an end 27 formed to have a flange 47.

The flange 47 may have slots (not shown). The slots may be formed in the flange 47 in order to allow guide vanes 17 to slide through the slots. The guide vanesl7 allow for an accurate gas flow to be directed onto the turbine 18 and the flange 47, for maintaining an accurate gas flow throughout the flow range of the turbocharger apparatus 1.

The guide vanes 17 are held against the heat shield section 5 of the bearing housing 15. This allows for an accurate gas flow around the end section 3 of the guide vanes 17.

As shown in Figure 1, the compressor housing 14 is held in position by bolts 48. The bearing assembly 15 is held by clamp plates 45 and bolts 46. The clamp plates 45 and the bolts 46 secure the bearing assembly 15 to the turbine housing 16, and also prevent gas leakage between clamping areas of the turbine housing and the bearing assembly.

Referring now to Figure 2 there is shown second turbocharger apparatus 2. Figure 2 illustrates in detail how a single cast bearing housing and heat shield is allowed to maintain a more constant tolerance between the bore 23 of the bearing housing and section 24 of the heat shield section of the bearing housing. This is effected by machining the single unit, so allowing a smaller tolerance between the turbine 18 and the heat shield section 24. This helps to prevent gas leakage between the turbine 18 and the heat shield section of the bearing housing.

Figure 2 also shows in detail how exhaust gases are guided onto the vane area 38 of the turbine 18. The turbine 18 is allowed to rotate in a recess in the heat shield area 24. This prevents exhaust gases from tending to work between the turbine 18 and the heat shield section of the bearing housing.

The integrally cast bearing housing and heat shield are such as to allow a more constant product to be produced than would be the case if the heat shield were produced as a separate component. Production of a more constant product allows for the provision of a more constant tolerance between the bearing housing and the heat shield sections, thereby preventing misalignment of parts within the turbocharger apparatus.

Figure 2 also shows how the integrally cast bearing housing and heat shield are able to be cast such that heat formed on the heat shield section 5 from hot exhaust gases has to travel from the heat shield section 5 around the outer edges 19 of the bearing housing. This allows outside air to cool the casting, and so helps to prevent heat travelling around the bearing housing casting and back down the sealing area 4 of the bearing assembly 15, thereby preventing heat soak.

Figure 2 is such that it shows the turbocharger apparatus without a variable turbine area without guide vanes, and the clamping of the bearing assembly to the turbine housing being done with a clamping ring 50.

Figure 3 shows turbocharger apparatus 8 having a bearing housing 37 and an integral heat shield section 85. An air pipe 74 is provided for allowing an air supply to an air bearing system (not shown). The air supply is for causing rotation of a turbine wheel 10 and a compressor wheel (not shown).

The bearing housing has an integral heat shield 85. A sealing ring 17 is mounted within a bore 12 of the heat shield section of the bearing housing with integral heat shield. The bearing housing 37 is such that a cooling chamber 25 is formed between the heat shield section 85 and an inner wall section 11 of the bearing housing with integral heat shield, such that air is able to be taken under vacuum or pressure between a bore 57 in the bearing housing 37 and the turbine wheel shaft 54 in order to cool the shaft 54. The air taken under vacuum and/or pressure into the cooling chamber is such as to prevent heat transfer between the heat shield section 85 of the bearing housing 37 and an air bearing system (not shown).

The cooling chamber 25 is also able to prevent exhaust gases that may bypass the sealing ring 17 on the turbine side of the turbocharger apparatus 8 from entering into an air bearing system such that gases may be taken out of the bearing housing through the cooling chamber 25 under vacuum through a pipe 51.

If desired, the amount of air bypassing the bore 57 into the cooling chamber 25 is able to be controlled by a clearance gap between the shaft 54 and the bore 57, the control being such as always to allow a vacuum within the cooling chamber 25.

The bearing housing with integral heat shield is able to be machined such that the sealing bore 12 and the inner bores for the bearing system are able to be machined perfectly in line. This alignment of the bores would be very difficult to achieve if a separate heat shield were to be used.

The bearing housing with integral heat shield is such that the turbine wheel 10 is able to be allowed to rotate within a recess 52 within the heat shield section 85 of the bearing housing. This allows an accurate gas flow onto the turbine wheel 10 and helps to prevent gases flowing between the back face 55 of the turbine wheel and the heat shield section of the bearing housing.

The bearing housing with integral heat shield may use air bearings.

The air bearings may allow easy assembly into turbocharger apparatus having a variable turbine area 58.

The air supply may be under pressure or vacuum, or it may be a system of both pressure and vacuum. Thus, for example, the air supply may be supplied under pressure into pipe 74 into an air bearing system, and then bypassed through the bore 57. The air bypass may be controlled by the size of the clearance gap between the bore 57 and the shaft 54. The control of the air may be such as to allow a vacuum situation in the cooling chamber 25 through the pipe 51. This allows a situation whereby cooling air is allowed to bypass in order to cool the shaft 54 and allow cooling air into the chamber 25. Also, the vacuum is allowed within the chamber 25 in order to prevent a pressure on the side of the sealing ring 17 such as to prevent the sealing ring 17 from being pushed away from a small step in the bore 12 in which the sealing ring 17 is located. The sealing ring 17 locates against the small step with the step thus setting the position of the sealing ring 17.

The vacuum also allows a situation whereby exhaust gases that may manage to pass by the sealing ring 17 are taken out of the bearing housing through the cooling chamber 25 and out through the pipe 51, in order to prevent exhaust gases entering the air bearing system.

If air pressure is used throughout the air supply, then a labyrinth type sealing system may be used in place of the sealing ring 17, in order to prevent a pushing action on the sealing ring.

If desired, a vacuum may be used throughout the air bearing system and the cooling system.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only and that modifications may be effected.

Claims

1. Turbocharger apparatus comprising a compressor, a turbine, a compressor housing, a compressor housing inlet for enabling air to be conducted to the compressor, a compressor housing outlet for enabling air to exit the compressor housing, a turbine housing which surrounds the turbine, a turbine housing inlet for enabling exhaust gases from an engine to be conducted to the turbine in order to rotate the turbine, a bearing assembly for permitting rotation of the compressor and the turbine, a bearing housing, and a heat shield for protecting the bearing assembly from heat from the exhaust gases, characterised in that the heat shield is formed as an integral part of the bearing housing.

2. Turbocharger apparatus according to claim I in which the heat shield is formed as an integral part of the bearing housing by casting.

3. Turbocharger apparatus according to claim I or claim 2 in which the integrally formed heat shield and bearing housing comprises a hollow section behind the heat shield area such that heat transfer from the heat shield section of the bearing housing has to travel around the outer diameter of the bearing housing before being able to travel to the bearing assembly and thereby prevent heat soak.

4. Turbocharger apparatus according to any one of the preceding claims in which the turbine rotates in a recess area in the heat shield part of the bearing housing.

5. Turbocharger apparatus according to claim 4 in which the integrally formed heat shield and bearing housing is subsequently machined to cause a bore in the bearing housing to be in alignment with the recess area in which the turbine rotates so as to have a minimum tolerance between the heat shield part of the bearing housing and the turbine in order to prevent gas leakage between the turbine and the heat shield part.

6. Turbocharger apparatus according to claim 4 or claim 5 in which the turbine rotates in the recess area in the heat shield part of the bearing housing in order to allow for an accurate gas flow onto the vane area of the turbine.

7. Turbocharger apparatus according to any one of the preceding claims in which the integrally formed heat shield and bearing housing are subsequently machined to provide an accurate end face of the heat shield section of the bearing housing such as to allow guide vanes to be held against the heat shield section of the bearing housing, thereby to allow for an accurate gas flow around the end section of the guide vanes.

8. Turbocharger apparatus according to any one of the preceding claims in which the bearing assembly is an air bearing assembly.

9. Turbocharger apparatus according to any one of the preceding claims and including a sealing ring mounted in the bore of the heat shield section.

10. Turbocharger apparatus according to the preceding claims and including a cooling chamber formed between the heat shield section and an inner wall section of the bearing housing.

II. Turbocharger apparatus according to claim 8 in which cooling air passes from an air bearing area of the air bearing assembly through a bore in the bearing housing section in order to cool the turbine wheel shaft and a cooling chamber section of the bearing housing, whereby heat transfer between the heat shield section of the bearing housing and the air bearing system is prevented.

12. Turbocharger apparatus according to claim 8 in which a cooling chamber between the bearing housing and heat shield sections is such that the cooling chamber under vacuum allows exhaust gases that may manage to pass the sealing system to be taken out of the cooling chamber, whereby the exhaust gases are prevented from entering into the air bearing section of the bearing housing.

13. Turbocharger apparatus according to claim 8 in which the air bearing assembly has air bearings which are under air pressure, and in which air bypass is controlled into a cooling chamber such that a vacuum may be used within the cooling chamber such to prevent side pressure on the sealing ring such to prevent the sealing ring from being pushed away from a location face.

14. Turbocharger apparatus according to claim 8 in which an air pipe is fitted or formed between the heat shield section and bearing housing section, whereby air is able to be drawn under vacuum into a cooling chamber, or whereby air pressure is able to be introduced into the cooling chamber.

15. Turbocharger apparatus according to any one of the preceding claims in which machining of the bores of the bearing housing and the sealing area in the heat shield section is such that the bores are in alignment.

16. Turbocharger apparatus according to claim 8 and including a labyrinth type sealing system.

17. Turbocharger apparatus according to claim 8 in which air pressure is used in a cooling chamber in order to cool firstly the area between the bearing housing and heat shield sections, and secondly the turbine wheel shaft, and in which air is allowed to enter into the air bearing section of the bearing housing.

18. Turbocharger apparatus according to any one of the preceding claims and in the form of a variable turbine area turbocharger.

19. Turbocharger apparatus according to any one of the preceding claims when used in conjunction with a twin or single turbocharger system.

20. Turbocharger apparatus according to any one of claims 1 - 7 in which the bearing assembly is an oil fuel bearing assembly.

21. Turbocharger apparatus substantially as herein described with reference to the accompanying drawings.