US20070092387A1

US20070092387A1 - Oil discharge assembly for a turbocharger

Info

Publication number: US20070092387A1
Application number: US11/256,451
Authority: US
Inventors: Daniel Ward
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2005-10-21
Filing date: 2005-10-21
Publication date: 2007-04-26

Abstract

A turbocharger assembly (100) includes an insert (200) having an outer axially extending lip (204) and an inner axially extending lip (208). The outer lip (204) is radially spaced from the inner lip (208), and the inner lip (208) has a radially outwardly extending tip (212). The inner lip (208) can define an annular drainage channel (216). The insert (200) is positioned in the turbocharger assembly (100) so as to engage a thrust collar (124) and a thrust bearing (140). The insert (200), the thrust collar (124) and the thrust bearing (140) can cooperatively define an oil collection chamber (240). The oil collection chamber (240) is in fluid communication with an oil release interface defined between the thrust collar (124) and the thrust bearing (140). Pressurized oil discharged from the oil release interface is centrifugally propelled toward a radially outer region of the oil collection chamber (240) and can gravitationally collect in the drainage channel (216), which can direct the oil out of the turbocharger assembly (100).

Description

FIELD OF THE INVENTION

The invention relates in general to turbochargers and, more particularly, to preventing oil leakage into the compressor of a turbocharger.

BACKGROUND OF THE INVENTION

Turbochargers can have a turbine wheel that is connected by a shaft to a compressor wheel. The turbine wheel is driven by exhaust gas exiting an internal combustion engine. The rotation of the turbine wheel is communicated to the compressor wheel by the shaft. The compressor wheel is used to increase the pressure of intake air prior to mixing with fuel and combustion in the engine. The speeds at which the shaft, turbine wheel and compressor wheel are rotated is very high, and can be in excess of 250,000 rpm. Therefore, bearings used to support the shaft must be lubricated with pressurized oil. During normal operation of the turbocharger, pressure within the compressor is sufficient to retard the flow of oil from the area of the bearings into the compressor. However, during certain operational states, pressure is reduced in the compressor and pressurized oil can be drawn into the compressor area where the oil will contaminate the intake air.
This lubricant is ultimately emitted into the environment via the exhaust, contributing to emissions that may not be in compliance with the increasingly stringent emissions standards that turbocharged vehicles are required to meet. Further, such emissions can potentially harm certain downstream components (i.e., catalytic converters). However, it is a challenge to prevent the flow of lubricant into the compressor, considering that lubricating oil is pumped in under pressure, at a high flow rate, to lubricate and remove heat from a turbine shaft rotates at high speeds.
One example of such a system for containing the flow of lubricant into the compressor is shown in FIG. 1. The system includes a turbocharger 10 that has a turbine wheel 14, a compressor wheel 18, and a connecting shaft 22. A first journal bearing 26 and a second journal bearing 28 can be provided to support the shaft 22. An oil intake 30 communicates with oil passages 34, 38 to deliver oil to the first journal bearing 26 and the second journal bearing 28. Additionally, a thrust collar 40 is fixed to and rotates with the shaft 22. The thrust collar 40 includes a first radially outwardly extending wall 44 and a second radially outwardly extending wall 48 (FIG. 2). A thrust bearing 50 has a radially inner end 54 that rests in an annular channel formed by the first radially outwardly extending wall 44 and second radially outwardly extending wall 48 of the thrust collar 40. The thrust bearing 50 controls axially directed movement of the shaft 22 as well as radial shaft vibration.
Lubrication is provided by oil passageway 60 which receives oil from the oil intake 30. Oil escaping from the interface between the first radially outwardly extending wall 44 and the thrust bearing 50 is prevented from reaching the compressor wheel 18 by the provision of a seal assembly including an oil deflector 64 and an insert 68. The deflector 64 has an irregular form to facilitate the drainage of oil. Oil passing the deflector 64 is contacted by an oil thrower 72. The oil thrower 72 is connected to the shaft 22 and rotates therewith. Oil is thrown by the thrower 72 into the chamber 76 where it contacts a deflecting surface 80. The deflecting surface 80 collects the oil and the oil flows gravitationally to the outlet 84.
However, this configuration is mechanically complicated because it introduces an additional component (the oil deflector 64) to the assembly. Further, oil can become stuck between two surfaces due to surface tension and capillary action, preventing the oil from draining due to gravity and potentially blocking the drainage of other oil. Any oil trapped in the area increases the likelihood that it will be drawn into the compressor. Despite the tortuous path created by the presence of the insert 68, the oil deflector 64 and the oil thrower 72, the oil can nevertheless flow past the interstices between the insert 68 and the oil thrower 72 to reach the compressor wheel 18.
The prior art is replete with additional systems for preventing lubricant flow into the compressor. For instance, many references are directed to systems with double ring seals. Some references use pressurized gas or venting to air in combination with the seals to prevent undesired migration of the lubricant. Examples of such systems are disclosed in U.S. Pat. Nos. 3,825,311; 4,196,190; 5,076,765; and 5,890,881 as well as in International Publication No. WO2004/063535 and European Patent Specification No. EP0941431. However, these systems can be overly complicated, unreliable, expensive to incorporate and thus not universally adopted, and liable to wear out. Thus, there is a need for a turbocharger assembly that can minimize such concerns.

SUMMARY OF THE INVENTION

A turbocharger assembly according to aspects of the invention includes a thrust collar, a thrust bearing and an insert. The thrust collar has a first radially outwardly extending wall and a second radially outwardly extending wall. The first and second radially outwardly extending walls are axially spaced such that an annular channel is defined therebetween. The first radially outwardly extending wall has a proximal face and a distal face. Likewise, the second radially outwardly extending wall has a proximal face and a distal face. The annular channel is formed in part by the distal face of the first radially outwardly extending wall and the proximal face of the second radially outwardly extending wall.
A thrust bearing has a first axial face and a second axial face. The thrust bearing further has a radially outer end and a radially inner end. At least a portion of the thrust bearing including the radially inner end is received in the annular channel.
The insert has an outer axially extending lip and an inner axially extending lip. The outer lip is radially spaced from the inner lip. The inner lip has a radially outwardly extending tip. The inner lip defines an annular drainage channel. The insert annularly surrounds a portion of the thrust collar such that the tip of the inner lip directly engages the proximal face of the first radially outwardly extending wall and such that the outer lip directly engages the first axial face of the thrust bearing proximate the radially outer end.
An oil collection chamber is defined at least in part by the drainage channel of the insert, the first radially outwardly extending wall of the thrust collar and the first axial face of the thrust bearing. The chamber is in fluid communication with an oil release interface defined between the first radially outwardly extending wall and the thrust bearing. Thus, pressurized oil discharged from the oil release interface is permitted to be centrifugally propelled toward a radially outer region of the oil collection chamber and to collect in the oil collection chamber for subsequent drainage.
The insert can include a deflecting surface. The deflecting surface can form a part of the oil collection chamber. The deflecting surface can be angular, or it can be substantially curvilinear.
The first radially outwardly extending wall can have an associated diameter and the radially outwardly extending tip can have an associated second diameter. In one embodiment, the second diameter can be greater than the first diameter. In another embodiment, the second diameter can be less than the first diameter. In such case, the first radially outwardly extending wall can be at a first diameter at the proximal face and at a second diameter at the distal face. The first diameter can be greater than the second diameter such that a sharp edge is formed at the proximal face.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a prior art turbocharger.
FIG. 2 is an enlarged cross-sectional view of an oil deflector assembly in the turbocharger of FIG. 1.
FIG. 3 is a cross-sectional view of a turbocharger with an oil discharge assembly according to aspects of the invention.
FIG. 4 is a schematic diagram illustrating an oil discharge assembly according to aspects of the invention.
FIG. 5A is a perspective view of an insert according to aspects of the invention.
FIG. 5B is a perspective view, broken away partially in cross-section, of the insert of FIG. 5A.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are directed to an oil discharge assembly for a turbocharger. Aspects of the invention will be explained in connection with one possible oil discharge assembly, but the detailed description is intended only as exemplary. Embodiments of the invention are shown in FIGS. 3-5B, but the present invention is not limited to the illustrated structure or application.
Referring to FIGS. 3-4, aspects of the invention relate to a turbocharger 100. The turbocharger 100 has a turbine housing 101, a compressor housing 102 and a center or bearing housing 103. The turbocharger 100 can include a turbine wheel 104 and a compressor wheel 108 that are connected by a shaft 112. The compressor wheel 108 can be provided in a compressor assembly 110. The shaft 112 is supported by a first journal bearing 116 and a second journal bearing 120.
The turbocharger 100 can further include a thrust collar 124. The thrust collar 124 can be generally cylindrical with a first radially outwardly extending wall 130 and a second radially outwardly extending wall 134. The first radially outwardly extending wall 130 has a proximal face 131 and a distal face 133. The second radially outwardly extending wall 134 has an proximal face 135 and a distal face 137. It should be noted that the terms “proximal” and “distal,” as used herein, are intended to mean relative to the compressor assembly 110. The first and second radially outwardly extending walls 130, 134 are axially spaced such that an annular channel 160 is formed therebetween. The annular channel 160 can be defined in part by the distal face 133 of the first radially outwardly extending wall 130 and the proximal face 135 of the second radially outwardly extending wall 134.
The assembly further includes a thrust bearing 140. The thrust bearing 140 has a first axial face 144 and a second axial face 148. The thrust bearing 140 has a radially outer end 152 and a radially inner end 156. At least a portion of the thrust bearing 140, including the radially inner end 156, is received in the annular channel 160.
Pressurized oil is provided through an oil intake 170 and through a passageway 174 to the thrust bearing 140. Oil is transported through a passageway 178 to the first journal bearing 116 and through a passageway 182 to the second journal bearing 120. Oil making its way toward the compressor 110 is blocked by an insert 200. The insert 200 is generally annular and has an outer axially extending lip 204 and an inner axially extending lip 208. The inner lip 208 has a radially outwardly extending tip 212 such that the inner lip 208 defines an annular drainage channel 216. The insert 200 can be made of any suitable material, such as iron.
The insert 200 annularly surrounds the thrust collar 124. A portion of the outer lip 204 of the insert 200 can directly engage the housing 102. A portion of outer lip 204 can directly engage the first face 144 of the thrust bearing 140 proximate the radially outer end 152. The inner lip 208 of the insert 200 can directly engage the thrust collar 124. The tip 212 of the inner lip 208 can directly engage the proximal face 131 of the first radially outwardly extending wall 130 of the thrust collar 124. In one embodiment, the diameter of the outwardly extending tip 212 can be greater than the diameter of the first radially outwardly extending wall 130 of the thrust collar 124, as shown in FIG. 3. Alternatively, the diameter of the outwardly extending tip 212 can be less than the diameter of the first radially outwardly extending wall 130 of the thrust collar 124. In such case, the first radially outwardly extending wall 130 can be angled relative to the centerline of the shaft 112 or otherwise to horizontal so as to form a sharp edge. FIG. 4 shows an embodiment in which a sharp edge 138 is formed when the diameter of the first radially outwardly extending wall 130 can be greater at the proximal face 131 than the distal face 133.
An oil collection chamber 240 is defined at least in part by the drainage channel 216 of the insert 200, the first radially outwardly extending wall 130 of the thrust collar 128 and the first axial face 144 of the thrust bearing 140. The chamber is in fluid communication with an oil release interface between the distal face 133 of the first radially outwardly extending wall 130 and the first axial face 144 of the thrust bearing 140.
Oil discharged from the oil release interface is centrifugally propelled from the interface as generally indicated by arrow 250. In cases where the first radially outwardly extending wall 130 provides a sharp edge 138, as described above, the oil can be broken apart by the edge 138 as it is propelled outward. The oil can be propelled toward a radially outer region of the oil collection chamber 240 as indicated by arrow 251. The oil can strike a deflecting surface 206 of the insert 200 and can follow the path of arrows 252-255 to the drainage channel 216. The deflecting surface 206 can be contoured to generally direct the oil downward. In one embodiment, the deflecting surface 206 can be substantially curvilinear or otherwise smooth, as shown in FIG. 3. Alternatively, the deflecting surface 216 can be angular, as shown in FIG. 4. In such case, the deflecting surface 206 can include an upper deflecting surface 205, a downwardly angled surface 207, a proximal wall 209 that can be substantially vertical, a base 211, and a distal wall 213 (which is an outer surface of the tip 212). Oil collected in the drainage channel 216 can flow gravitationally to an outlet 270, where the oil can be returned to a sump or reservoir or otherwise exits the turbocharger assembly 100.
According to aspects of the invention, it is preferred for the oil collection chamber 240 to be as large as possible. The larger the chamber 240, the more difficult it is for oil to stick between two surfaces of the chamber 240. Thus, the likelihood that the oil will drain out of the oil collection chamber 240 can be increased.
There is shown in FIG. 5 an insert 200 in accordance with aspects of the invention. The insert 200 can include a first radially outwardly extending wall 203 and a second radially outwardly extending wall 205. The walls 203 and 205 form a groove 209 capable of receiving sealing structure, such as an o-ring seal 215 (FIG. 3), for sealing to housing 102. Similarly, sealing structure, such as o- ring seals 217 and 219, can be provided to seal the thrust collar 124 to the insert 200 (FIG. 3).
The foregoing description is provided in the context of one possible oil discharge assembly for a turbocharger. Thus, it will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the invention as defined in the following claims.

Claims

1. A turbocharger assembly comprising:

a thrust collar (124) having a first radially outwardly extending wall (130) and a second radially outwardly extending wall (134), the first and second radially outwardly extending walls (130, 134) being axially spaced such that an annular channel (160) is defined therebetween, the first radially outwardly extending wall (130) having a proximal face (131) and a distal face (133), the second radially outwardly extending wall (134) having a proximal face (135) and a distal face (137), wherein the annular channel (160) is formed in part by the distal face (133) of the first radially outwardly extending wall (130) and the proximal face (135) of the second radially outwardly extending wall (134);

a thrust bearing (140) having a first axial face (144) and a second axial face (148), the thrust bearing (140) further having a radially outer end (152) and a radially inner end (156), at least a portion of the thrust bearing (140) including the radially inner end (156) being received in the annular channel (160); and

an insert (200) having an outer axially extending lip (204) and an inner axially extending lip (208), the outer lip (204) being radially spaced from the inner lip (208), the inner lip (208) having a radially outwardly extending tip (212), wherein the inner lip (208) defines an annular drainage channel (216), the insert (200) annularly surrounding a portion of the thrust collar (124) such that the tip (212) of the inner lip (208) directly engages the proximal face (131) of the first radially outwardly extending wall (130) and such that the outer lip (204) directly engages the first axial face (144) of the thrust bearing (140) proximate the radially outer end (152),

wherein an oil collection chamber (240) is defined at least in part by the drainage channel (216) of the insert (200), the first radially outwardly extending wall (130) of the thrust collar (124) and the first axial face (144) of the thrust bearing (140), the chamber (240) being in fluid communication with an oil release interface between the first radially outwardly extending wall (130) and the thrust bearing (140),

whereby pressurized oil discharged from the oil release interface is permitted to be centrifugally propelled toward a radially outer region of the oil collection chamber (240) and to collect in the oil collection chamber (240) for subsequent drainage.

2. The turbocharger assembly of claim 1 wherein the insert (200) includes a deflecting surface (206), wherein the deflecting surface (206) forms a part of the oil collection chamber (240), wherein the deflecting surface (206) is angular.

3. The turbocharger assembly of claim 1 wherein the insert (200) includes a deflecting surface (206), wherein the deflecting surface (206) forms a part of the oil collection chamber (240), wherein the deflecting surface (206) is substantially curvilinear.

4. The turbocharger assembly of claim 1 wherein the first radially outwardly extending wall (130) has an associated diameter and the radially outwardly extending tip (212) has an associated second diameter, wherein the second diameter is greater than the first diameter.

5. The turbocharger assembly of claim 1 wherein the first radially outwardly extending wall (130) has an associated diameter and the radially outwardly extending tip (212) has an associated second diameter, wherein the second diameter is less than the first diameter.

6. The turbocharger assembly of claim 5 wherein the first radially outwardly extending wall (130) is at a first diameter at the proximal face (131) and at a second diameter at the distal face (133), wherein the first diameter is greater than the second diameter, whereby a sharp edge (138) is formed at the proximal face (131).