GB2054055A

GB2054055A - Turbocharger having turbine wastegate valve

Info

Publication number: GB2054055A
Application number: GB8022516A
Authority: GB
Original assignee: IHI Corp
Current assignee: IHI Corp
Priority date: 1979-07-14
Filing date: 1980-07-09
Publication date: 1981-02-11
Also published as: FR2461810A1; GB2054055B; DE3025137A1; IT8023405A0; IT1131557B; JPS5615424U; JPS5827061Y2

Abstract

The turbine of the turbocharger has a circular exhaust pipe connection (10). One part (8) of the cross-section of which receives the exhaust gases discharged from the turbine, through an opening (3), while the other part (9) of the cross-section receives exhaust gases which have bypassed the turbine through a bypass passage (4), controlled by a wastegate valve (5). <IMAGE>

Description

SPECIFICATION Turbochargers having turbine wastegate valves This invention relates to turbochargers.

A turbocharger normally comprises a turbine and a rotodynamic compressor, whose rotors are mounted on a common shaft, so that the turbine drives the compressor. In a typical application of a turbocharger, the turbocharger is used to improve the performance of an internal combustion engine; the engine exhaust is connected to drive the turbine, while the compressor compresses air (or fuel-air mixture) for supply to the engine at superatmospheric pressure.

Under some conditions, the amount of energy contained in the engine exhaust gases may be so high as the drive the turbocharger at an unnecessariiy high speed. For this reason, a bypass passage may be provided, through which a part of the engine exhaust gases may be bypassed around the turbine. A so-called wastegate valve may be provided to control the flow through the bypass passage.

The present invention is concerned with the provision of flow paths from both the outlet of the turbine and the bypass passage to a single exhaust system.

According to one aspect of the present invention, an exhaust bypass passage in a turbocharger is formed in parallel with a main exhaust passage at the exhaust side of a turbine casing and an integral, annular exhaust-pipe connection is formed on the exhaust end of the turbine casing, said connection functioning as an outlet of the main exhaust passage as well as an outlet of the exhaust bypass passage.

According to a second aspect of the invention, a turbocharger has a turbine housing having a generally circular exhaust discharge connection, part of whose cross-section is occupied by a turbine discharge passage, while a further part of the cross-section of the discharge connection is occupied by the discharge of a bypass passage which leads from an inlet space of the turbine.

The invention may be carried into practice in various ways, but one specific design of turbocharger exhaust housing embodying the invention will now be described by way of example, together with (for comparison) two designs of turbocharger exhaust housing not embodying the invention. In the accompanying drawings: Figure 1 is an elevation of a first design of turbocharger exhaust housing, not embodying the invention, looking towards the flange by which an exhaust pipe may be connected to receive exhaust gases from the turbine of the turbocharger; Figure 2 is a section, taken on a vertical plane perpendicular to the plane of Figure 1, showing certain internal details of the exhaust housing; Figures 3 and 4 are views, similar to Figures 1 and 2, showing a second design of turbocharger exhaust housing not embodying the invention; and Figures 5 and 6 are views, also similar to Figures 1 and 2, showing a design of turbocharger exhaust housing embodying the invention.

In Figure 2, the rotor of the turbine of the turbocharger is shown in chain-dotted line, and is housed within a turbine housing. The exhaust gas flow leaving the turbine is indicated by an arrow c, and passes first through an opening in the turbine housing, and then through a passage in an exhaust housing which is bolted to the turbine housing.

This passage is of circular cross-section, and terminates, at the right-hand side of Figure 2, with a circular joint face a. The joint face a has three lugs by which an exhaust pipe can be bolted to the exhaust housing.

In addition, the turbine housing and exhaust housing of Figures 1 and 2 have bypass passages through which a part of the gases which would otherwise drive the turbine may be diverted around the turbine, as indicated by an arrow b in Figure 2. A wastegate valve, operated by a linkage shown diagrammatically in Figures 1 and 2, controls the flow through the bypass passages.

The part of the bypass passage which is formed in the exhaust housing opens into the main, circular exhaust passage, in a direction at right angles to the length of the main passage. As a result, the momentum of the flow in the bypass passage does nothing to assist the flow in the main passage, while the disturbance of the flow in the main passage which it creates actually results in a rise in the turbine back pressure, so that the turbine performance may be degraded. The engine back pressure may also be increased, degrading the performance of the engine itself.

Figures 3 and 4 show part of a turbocharger which has some similarities to that shown in Figures 1 and 2. In particular, the exhaust housing of the turbocharger has a circular passage dfor the gases discharged from the turbine. The turbine housing and the exhaust housing again have bypass passages, shown at e, through which a part of the engine exhaust gases may be diverted around the turbine. These bypass passages are also circular in cross-section; the turbine discharge passage d and the bypass passage open, separately, on to a common joint face a, which is provided with bolting lugs for the connection of a downstream part of the exhaust system. This downstream part would receive the exhaust gas flows from both passages, and merge them into a single flow. Since the two flows are travelling in much the same direction, the bypass flow does not have any adverse effect on the main flow.However, the part of the exhaust system which has to mate with the joint face a is complicated in shape, so that costs and weight are increased.

Figures 5 and 6 illustrate part of a turbocharger embodying the present invention. This turbocharger includes a turbine rotor 2 (shown in chain dotted line), which is housed within a turbine housing (only part of which is shown). The exhaust gases passing through the turbine leave the turbine housing 1 through a circular opening 3, which leads the exhaust gas into an exhaust housing 6 bolted to the turbine housing 1. The turbine housing 1 also has a circular bypass passage 4, by which exhaust gases can be diverted from the flow upstream of the turbine to a bypass passage 9 in the exhaust housing 6. A wastegate valve 5 controls this bypass flow; as can be seen from Figure 6,the valve 5 is housed within and carried by the exhaust housing 6, although the seat for the valve is formed by the turbine housing 1.The two passages 8 and 9 within the exhaust housing 6 change in crosssection towards the downstream end of the housing 6, so that, together, they occupy a circular area. At the downstream end of the housing 6, this circular area is surrounded by a joint face 10, having bolted lugs 1 Oa to allow it to be connected to a plain circular exhaust pipe 11 (shown in chain-dotted line in Figure 6). Within the exhaust housing 6, the two passages 8 and 9 are separated by a partition 7, but this partition does not extend downstream of the joint face 10. Thus, as will be seen, the flows in the two passages 8 and 9 will come into contact with one another when they are flowing in the same direction, so that the momentum of the bypassed flow assists the exhaust flow leaving the turbine rotor 2, and thereby tends to reduce the turbine back pressure.

This is achieved without the use of any exhaust pipe fittings of special shape downstream of the exhaust housing 6.

Claims

1. A turbocharger wherein an exhaust bypass passage is formed in parallel with a main exhaust passage at the exhaust side of a turbine casing and wherein an integral, annular exhaust-pipe connection is formed on the exhaust end of the turbine casing, said connection functioning as an outlet of the main exhaust passage as well as an outlet of the exhaust bypass passage.

2. A turbocharger which has a turbine housing having a generally circular exhaust discharge connection, part of whose cross-section is occupied by a turbine discharge passage, while a further part of the cross-section of the discharge connection is occupied by the discharge of a bypass passage which leads from an inlet space of the turbine.

3. A turbocharger as claimed in Claim 2, which includes a wastegate valve arranged to control the flow of gass through the bypass passage.

4. A turbocharger as claimed in Claim 2 or Claim 3, in which the circular exhaust discharge connection is formed as part of a separate component, attached to a main part of the turbine housing, the turbine discharge and the bypass passage leading into the said separate component through separate openings.

5. A turbocharger as claimed in Claims 3 and 4, in which the wastegate valve has a movable valve closure member, which is carried on the said separate component.

6. A turbocharger as claimed in any of Claims 2 to 5, in which the turbine discharge passage and the bypass passage are separated by a partition upstream of the exhaust discharge connection, which partition extends substantially up to the exhaust discharge connection.

7. A turbocharger as claimed in any of Claims 2 to 6, in which the turbine discharge passage and the bypass passage extend substantially parallel to one another immediately upstream of their union.

8. A turbocharger having a wastegate valve, and an exhaust connection substantially as herein described, with reference to Figures 5 and 6 of the accompanying drawings.