GB2575979A

GB2575979A - Valve assembly

Info

Publication number: GB2575979A
Application number: GB1812369.5A
Authority: GB
Inventors: Paul Higgins Ian; Parry Christopher; Alexander Mcewen James
Original assignee: Cummins Turbo Technologies Ltd
Current assignee: Cummins Turbo Technologies Ltd
Priority date: 2018-07-30
Filing date: 2018-07-30
Publication date: 2020-02-05
Anticipated expiration: 2038-07-30
Also published as: GB2575979B; GB201812369D0

Abstract

A valve assembly, especially for a turbine wastegate assembly, comprising a valve housing 190 and a valve member 136. The valve member and valve shaft are rotatably mounted in a first translational position in the valve housing and adapted for engaging and sealing a valve seat surrounding the second port. The valve housing comprises a first section 191 and a second section 192 that are attachable to each other, wherein the valve shaft is rotatably mountable in the second section of the valve housing and the first and second sections are movable, relative to each other, between an open configuration in which the valve member and valve shaft are movable in a substantially straight line substantially parallel to the shaft axis (A) to the first translational position from a second translational position external to said second section of the valve housing.

Description

VALVE ASSEMBLY

The present invention relates to a valve assembly and particularly, but not exclusively, to a turbine wastegate assembly and to a twin entry turbine balancing valve assembly. It also relates to a turbine with a wastegate assembly and to a twin entry turbine with a balancing valve assembly. The present invention also relates to a method of assembly and disassembly of a valve assembly and particularly, but not exclusively, to a method of assembly and disassembly of a turbine wastegate assembly and to a method of assembly and disassembly of a twin entry turbine balancing valve assembly.

A turbomachine comprises a turbine. A conventional turbine comprises an exhaust gas driven turbine wheel mounted on a rotatable shaft within a turbine housing connected downstream of an engine outlet manifold. Rotation of the turbine wheel drives either a compressor wheel mounted on the other end of the shaft within a compressor housing to deliver compressed air to an engine intake manifold, or a gear which transmits mechanical power to an engine flywheel or crankshaft. The turbine shaft is conventionally supported by journal and thrust bearings, including appropriate lubricating systems, located within a bearing housing.

Turbochargers are well known devices for supplying air to the intake of an internal combustion engine at pressures above atmospheric pressure (boost pressures). Turbochargers comprise a turbine having a turbine housing which defines a turbine chamber within which the turbine wheel is mounted; an annular inlet passageway defined between opposed radial walls arranged around the turbine chamber; an inlet chamber arranged around the inlet passageway; and an outlet passageway extending from the turbine chamber. The passageways and chambers communicate such that pressurised exhaust gas admitted to the inlet chamber flows through the inlet passageway to the outlet passageway via the turbine and rotates the turbine wheel.

Turbines may be of a fixed or variable geometry type. Variable geometry turbines differ from fixed geometry turbines in that the size of the annular inlet passageway can be varied to optimise gas flow velocities over a range of mass flow rates so that the power output of the turbine can be varied to suite varying engine demands. In this case, the annular inlet passageway is defined between opposed radial surfaces of respective radial walls of a movable annular nozzle ring and a fixed annular “shroud”.

For instance, when the volume of exhaust gas being delivered to the turbine is relatively low, the velocity of the gas reaching the turbine wheel is maintained at a level which ensures efficient turbine operation by reducing the size of the annular inlet passageway. Turbochargers provided with a variable geometry turbine are referred to as variable geometry turbochargers.

It is known to improve turbine performance by providing vanes, referred to as inlet guide vanes, in the annular inlet passageway. The inlet guide vanes define a plurality of radial vane passages which deflect gas flowing through the inlet passageway towards the direction of rotation of the turbine wheel.

Inlet guide vane arrangements in variable geometry turbochargers can take different forms. In one type, the inlet guide vanes are fixed to the radial wall of the movable annular nozzle ring and extend into the annular inlet passageway and through vane slots provided in the fixed shroud to accommodate movement of the nozzle ring. In an alternative arrangement, the inlet guide vanes are provided on the fixed shroud and the vane slots are provided in the nozzle ring to accommodate movement of the nozzle ring.

The radial wall of the nozzle ring is typically provided, at opposed radial ends, with radially inner and outer axially extending walls or flanges which extend into an annular cavity behind the radial wall of the nozzle ring. The cavity is formed in a part of the turbocharger housing (usually either the turbine housing or the turbocharger bearing housing) and accommodates axial movement of the nozzle ring. The flanges may be sealed with respect to the cavity walls to reduce or prevent leakage flow around the back of the nozzle ring.

In one arrangement of a variable geometry turbine the nozzle ring is supported on rods extending parallel to the axis of rotation of the turbine wheel and is moved by an actuator which axially displaces the rods. Nozzle ring actuators can take a variety of forms, including pneumatic, hydraulic and electric and can be linked to the nozzle ring in a variety of ways. The actuator will generally adjust the position of the nozzle ring under the control of an engine control unit (ECU) in order to modify the airflow through the turbine to meet performance requirements.

There is a constant requirement to increase the flow capacity of a turbine whilst improving its efficiency. One approach to meeting this need is to fit the turbine with a valve controlled bypass port referred to as a “wastegate” which can be controlled to vary the flow capacity of the turbine whilst enabling control of the turbocharger boost pressure and/or shaft speed.

The wastegate comprises a valve member, typically a poppet type valve or a flap type valve, that is controlled to open and close a wastegate port. The valve member is mounted to an end of a valve shaft such that rotation of the valve shaft causes rotation of the valve member between open and closed positions. The valve member is located within a wastegate housing and the valve shaft passes from the valve member through an aperture in the housing, to a second end located outside of the housing. An actuator shaft is connected, at one end, to the valve shaft such that reciprocal linear motion of the actuator shaft rotates the valve shaft. The other end of the actuator shaft is attached to a wastegate actuator, typically in the form of a pneumatic motor controlled by an engine control unit (ECU).

As the engine speed increases, the valve member is controlled to open the wastegate port when the pressure of the boost air increases towards a predetermined level, thus allowing some of the exhaust gas to bypass the turbine wheel. This serves to increase the flow capacity of the turbine whilst limiting the turbocharger speed. Typically the wastegate port opens into a bypass passageway which diverts the bypass gas flow to the turbine outlet or vents it to atmosphere.

The wastegate is often provided at a position adjacent to the inlet volute of the turbine. The wastegate housing comprises a main section and a cover plate. The cover plate is arranged to direct the bypassed exhaust gas to the turbine outlet. The cover plate is removably attached to the main section and can be removed to expose an open face of the main section to allow access for maintenance purposes, for example to replace the valve member.

At present there is a compromise between the angle of the actuator shaft, and therefore the position of the wastegate actuator, and the ability to assemble the wastegate. In order to be able to assemble the wastegate, it is necessary that there is sufficient clearance, between surrounding components of the turbine, to allow the valve and valve shaft to be inserted into the wastegate housing, through the open face of the main section of the wastegate housing (when the cover plate is not in place) and rotatably mounted therein. Due to the limited clearance provided by surrounding components of the turbine, this severely limits the range of possible positions of the wastegate, as well as the orientation of the actuator shaft and hence the actuator position.

Similar problems occur with other types of valve assembly, such as a balancing valve assembly of a twin entry turbine.

It is an object of the invention to overcome or mitigate the above problems.

It is also an object of the present invention to provide an improved or alternative valve assembly. It is also an object of the invention to provide a turbine comprising an improved or alternative valve assembly.

It is a further object of the present invention to provide an improved or alternative method of assembly of a valve assembly. It is also an object of the present invention to provide an improved or alternative method of assembly of a turbine.

It is a further object of the invention to provide a valve assembly design principle which permits a valve assembly to be constructed with flexibility in how the components of the valve assembly are relatively located, thereby permitting a customization of the valve assembly for particular application.

According to a first aspect of the present invention there is provided a valve assembly comprising:

a housing defining first and second ports and a passage fluidly connecting the first and second ports;

a valve housing;

a valve member;

a valve shaft coupled to the valve member and having a shaft axis;

an actuator coupled to the valve shaft to rotate the valve shaft about the shaft axis;

the valve housing comprising a first section and a second section that are attachable to each other, the first and second sections having respective mating surfaces that are in contact when the first and second sections are attached to each other;

wherein the valve member and valve shaft are rotatably mountable to the second section of the valve housing in a first translational position, the actuator being operative, when the valve member and the valve shaft are in the first translational position, to rotate the valve shaft about the shaft axis, whereby the valve shaft rotates the valve member between a first rotational position in which it substantially seals the second port, and a second rotational position in which it allows fluid to flow through the second port, the first and second sections of the valve housing are movable, relative to each other from an open configuration to a closed configuration in which the respective mating surfaces are in contact, and in the open configuration, the valve member and valve shaft are movable together to the first translational position in a substantially straight line which is substantially parallel to the shaft axis, from a second translational position in which the valve member and valve shaft are external to said second section of the valve housing.

In the second translational postion, the valve member and valve shaft are external to the second portion of the valve housing in the sense that the valve member and valve shaft are outside the convex hull of the second section of the valve housing. Here the term “convex hull” is used to mean the smallest convex volume which can be drawn around the second section of the valve housing.

This is advantageous in that it allows the valve member, and valve shaft, to be assembled within the valve housing by insertion of the valve member, and valve shaft, into the valve housing, in a direction substantially parallel to the shaft axis. This is advantageous in that when the valve assembly is being installed as part of a larger apparatus, for example when it is being installed as a wastegate in a turbine, it allows for the valve assembly to be assembled in a relatively large number of different positions and orientations. This provides for flexibility in the overall design of the apparatus. For example where the valve assembly is a wastegate valve assembly, where the valve shaft is rotatable by an actuator coupled to the shaft by an actuator shaft, this allows for a relatively large number of different orientations of the actuator shaft and therefore allows for a relatively large number of different positions of the actuator. This provides greater flexibility to the overall possible configurations of the turbine. Similar advantages arise with different types of valve assembly.

Optionally, the valve shaft is mountable in the first translational position to a first wall of said second section of the housing rotatably about the shaft axis, and, once mounted, the shaft axis does not intercept an opposed second wall of the second section of the housing. That is, there is a clearance between the shaft axis and a surface of an opposed second wall of said second section of the housing.

The mating surface of said second section of the valve housing may extend substantially in a plane. The plane may be substantially flat and inclined relative to the shaft axis such that it crosses the shaft axis.

The shaft axis may be inclined at a non-zero angle relative to its orthogonal projection on said plane. In this respect, the orthogonal projection of the shaft axis on the plane is a line on the plane oriented such that at each point along the line, a normal to the plane intersects the shaft axis.

The shaft axis may be inclined at an angle relative to its orthogonal projection on said plane, in the range 10 to 20 degrees.

The shaft axis may be inclined at a non-zero angle relative to the normal to the plane. The shaft axis may be inclined at an angle relative to the normal to the plane, in the range 70 to 80 degrees.

More generally, consider the convex hull of the mating surface of the second section of the valve housing. If the mating surface of the second section of the valve housing lies entirely on a plane (i.e. it is flat), then the convex hull is a 2-dimensional shape on the plane. However, if the mating surface of the second section of the valve housing does not lie on a plane, then the convex hull of the mating surface is a 3dimensional volume.

In either case, the shaft axis preferably intercepts the convex hull of the mating surface of the second section of the valve housing at an inclined angle (i.e. an angle less than 90 degrees and greater than 0 degrees), such as an angle in the range 10 to 20 degrees.

It will be appreciated that the mating surface of said first section of the valve housing may have a complementary shape to that of the mating surface of the second section of the valve housing (i.e. the section of the valve housing in which the valve member is rotatably mounted).

The mating surfaces of the first and second sections of the valve housing may be arranged such that when the first and second sections of the valve housing are in the open configuration, the mating surfaces are partially in contact (e.g. along a line). Alternatively, the mating surfaces of the first and second sections of the valve housing may be arranged such that when the mating surfaces are in the open configuration, the mating surfaces are substantially not in contact.

The valve member and valve shaft operate together as a flap valve.

Optionally, when the first and second sections are in the closed configuration, the valve housing defines a passage fluidly connecting the second port to an outlet of the valve housing.

The valve shaft may be coupled to the valve member by the valve member being mounted on the valve shaft, for rotation with the valve shaft about the shaft axis.

The actuator may be coupled to the valve shaft by an actuator shaft, wherein the actuator is arranged to move the actuator shaft in a direction along an axis of the actuator shaft such that said movement rotates the valve shaft about its axis. A lever arm may be mounted to the valve shaft, to rotate with the valve shaft, with the actuator shaft attached to a section of the lever arm offset from the shaft axis such that said movement of the actuator shaft rotates the valve shaft about its axis.

The valve shaft may pass through a bore in said second section of the valve housing wherein the actuator shaft and/or lever arm is disposed externally to said second section of the valve housing.

The actuator may be any suitable actuator including a pneumatic, hydraulic or electrical actuator.

In a second aspect, the present invention proposes a valve assembly comprising:

a valve housing;

a valve member;

a valve shaft coupled to the valve member and having a shaft axis;

the valve housing comprising a first section and a second section that are attached to each other and together define a chamber containing the valve member, the first and second sections having respective mating surfaces that are in contact;

wherein the valve member and valve shaft are rotatably mounted to the second section of the valve housing, the actuator being operative to rotate the valve shaft about the shaft axis, whereby the valve shaft rotates the valve member between a first rotational position in which it substantially seals the second port, and a second rotational position in which it allows fluid to flow through the second port, and wherein the shaft axis does not intercept the second section of the valve housing.

More particularly, the shaft axis does not intercept the second section of the valve housing in any position which is further along the shaft axis than a position at which the valve shaft is connected to the second section of housing, in the direction from that position towards a position where the valve shaft is connected to the valve member.

Optionally, the first and second sections of the valve housing are fixedly (that is, permanently rather than releasably) connected together, for example by welding.

According to a third aspect of the present invention there is provided a turbine comprising:

a turbine housing having an inlet and an outlet;

a turbine wheel mounted in the turbine housing between the inlet and outlet, for rotation about a rotational axis;

wherein the turbine comprises a valve assembly according to the first or second aspect of the invention, with the first and second sections of the valve assembly being attached to each other.

The normal direction to the convex hull of the mating surface of the second section of the valve assembly (e.g. at an interception point with the shaft axis and/or at an interception point with the rotational axis), may be inclined to the rotational axis defined by the turbine housing. The normal direction and the rotation axis may, for example, have an angle between them of at least 10 degrees, at least 30 degrees, at least 50 degrees or at least 60 degrees. The angle may however be no more than 80 degees, no more than 60 degrees or no more than 40 degrees.

The turbine housing may comprise first and second sections that are attachable to each other and have respective mating surfaces that are in contact when the first and second sections are attached to each other and wherein the mating surfaces of the first and second sections of the turbine housing are arranged such that the first and second sections of the turbine housing are movable, relative to each other, between open configuration and a closed configuration in which the mating surfaces of the turbine housing are in contact. When the turbine housing is in the open configuration, and when the first and second sections of the valve housing are in the open configuration, the valve member and valve shaft are movable to to the first translational position from the second translational position along said substantially straight line, and the second translational position is external to said first and second section of the turbine housing in the sense defined above.

Consider the respective convex hulls of the mating surfaces of the first and second sections of the turbine housing. Note that the mating surfaces of the first and second sections of the turbine housing may be planar, in which case the corresponding convex hull is a two-dimensional shape. Alternatively, the mating surfaces may be non-planar, in whiihc case the corresponding convex hull is a threedimensional shape. In any case, the convex hull of each of the mating surfaces of the sections of the turbine housing preferably intercepts the rotational axis at at least one location where the normal to the convex hull is inclined to the rotational axis (e.g. the normal and the rotational axis are at an angle of at least 10 degrees and at most 80 degrees).

Permitting the mating surfaces of the turbine sections to be inclined to the rotational axis gives the designer of the turbine housing additional design freedom. This freedom make it easier to design the turbine housing in a customized manner appropriate for a given application.

If the mating surfaces of the first or second section of the turbine housing are each planar, they may extend substantially in the same plane as that defined by the mating surface of the first or second section of the valve housing respectively. Alternatively, the mating surface of the first or second section of the turbine housing may extend in a different plane to that defined by the mating surface of the first or second section of the valve housing respectively.

The first and second sections of the turbine housing may be integrally formed with the first and second sections of the valve housing respectively. Alternatively, the first and second sections of the turbine housing may be formed separately to, and attached to, the first and second sections of the valve housing respectively.

The first or second section of the turbine housing may form the inlet of the turbine housing and the second or first section of the turbine housing may form the outlet of the turbine housing respectively.

When the first and second section of the turbine housing are in the open configuration, respective clearances exist between the shaft axis and opposed surfaces of said first and second sections of the turbine housing respectively.

The mating surface of said first or second section of the turbine housing may extend substantially in a plane (in this case, the convex hull of the mating surface is a two-dimensional area). The plane may be substantially flat and inclined relative to the shaft axis such that it crosses the shaft axis.

The shaft axis may be inclined at a non-zero angle relative to its orthogonal projection on said plane. In this respect, the orthogonal projection of the shaft axis on the plane is a line on the plane oriented such that each point along the line, a normal to the plane intersects the shaft axis.

The shaft axis may be inclined at a non-zero angle relative to the normal to the plane.

The shaft axis may be inclined at an angle relative to its orthogonal projection on said plane, in the range 10 to 30 degrees. Preferably, the shaft axis is inclined at an angle, relative to its orthogonal projection on said plane, of 20 degrees.

The shaft axis may be inclined at a non-zero angle relative to the normal to the plane. The shaft axis may be inclined at an angle relative to the normal to the plane, in the range 60 to 80 degrees.

It will be appreciated that the mating surface of each of said first or second section of the turbine housing may have a complementary shape to that of the mating surface of the other of the first or second section of the turbine housing.

The mating surfaces of the first and second sections of the turbine housing may be arranged such that when the mating surfaces are in the open configuration, the mating surfaces are partially in contact or are substantially not in contact.

The turbine may be a single entry turbine. In this regard, the inlet may comprise a single annular inlet passageway.

Alternatively, the turbine may be a twin entry turbine, such as a double flow turbine or a twin flow turbine. In this regard, the inlet may comprise first and second annular inlet passageways that respectively fluidly connect first and second turbine inlet ports to the turbine wheel, wherein the first port of the valve assembly is in fluid communication with the first and/or second annular inlet passageways.

The turbine may be a variable geometry turbine. In this respect, optionally the annular inlet passageway is defined by opposed first and second wall members, wherein the first and/or second wall members are movable relative to each other along the turbine axis to vary the size of the inlet passageway.

A plurality of guide vanes may be disposed within the annular inlet passageway so as to deflect gas flowing through the inlet passageway onto the turbine wheel.

One of the first or second wall members may be a nozzle ring provided with a plurality of guide vanes distributed circumferentially about the nozzle ring that are receivable in the annular inlet passageway, and the other of the wall members may be an annular wall of a shroud provided with a plurality of slots, wherein each slot is arranged to receive a respective guide vane of the nozzle ring as the shroud and nozzle ring are moved axially relative to each other.

Alternatively, the turbine may be a fixed geometry turbine.

In a first possibility, the inlet may comprise a substantially annular inlet passageway, with the first port of the valve assembly being in fluid communication with the inlet passageway and the second port being in fluid communication with an outlet such that gas passing along the passageway from the first port to the second port, and to the outlet, bypasses the turbine wheel.

In this regard, the valve assembly may form a wastegate of the turbine.

The outlet that the second port is fluidly connected to may be the outlet of the turbine housing. Alternatively, or additionally, the outlet that the second port is fluidly connected to may be separate to the outlet of the turbine housing.

The turbine outlet may extend in the direction of the turbine axis.

In a second possibility the inlet comprises first and second inlet ports fluidly connected to the turbine wheel by first and second annular inlet passageways respectively, with the first port of the valve assembly being in fluid communication with the first inlet passageway and the second port being in fluid communication with the second inlet passageway.

In this regard, the valve assembly may form a balancing valve assembly of the turbine.

The turbine may be a double flow turbine or a twin flow turbine.

According to a fourth aspect of the invention there is provided a method of assembling a valve assembly according the first or second aspects of the invention, wherein the method comprises moving the valve member and valve shaft to the first translational position from the second translational position external to said second section of the valve housing, by moving the valve member and valve shaft in a substantially straight line substantially parallel to the shaft axis.

According to a fifth aspect of the invention there is provided a method of assembling a turbine, said turbine comprising:

a turbine housing having an inlet and an outlet;

a turbine wheel mounted in the turbine housing between the inlet and outlet, for rotation about an axis;

wherein the turbine comprises a valve assembly according to the firstaspect of the invention.

and wherein the method comprises moving the valve member and valve shaft from the second translational position, to the first translational position by moving the valve member and valve shaft in a substantially straight line substantially parallel to the shaft axis.

The method may comprise moving the first and second sections of the valve housing from the open configuration to the closed configuration after moving the valve member and valve shaft from the second translational position external to said second section of the valve housing to the first translational position.

The turbine housing may comprise first and second sections that are attachable to each other and have respective mating surfaces that are in contact when the first and second sections are attached to each other in a closed configuration, and wherein the mating surfaces of the first and second sections of the turbine housing are arranged such that the first and second sections of the turbine housing are movable, relative to each other, to an open configuration in which, when the first and second sections of the valve housing are in the open configuration, the valve member and valve shaft are movable from the second translational position external to said second section of the turbine housing to the first translational position in a substantially straight line parallel to the shaft axis.

The method may comprise moving the first and second sections of the turbine housing, and the first and second sections of the valve housing, from their open configuration to their closed configuration after moving the valve member and valve shaft from the second translational position external to said second section of the turbine housing to the first translational position.

Any of the features of any of the above aspects of the invention may be combined with any other feature of any of the above aspects of the invention, in any combination.

A specific embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic cross-section through a portion of a known turbocharger;

Figure 2 shows a perspective view of a known turbocharger including a slightly different turbine to the turbine of the turbocharger shown in figure 1;

Figure 3 shows a front perspective view of the known turbocharger shown in figure 2;

Figure 4 shows an axial cross-sectional view of the turbocharger shown in figures 2 and 3;

Figure 5 shows an axial cross-sectional view of a turbocharger including a turbine slightly different to the turbine of the turbocharger shown in figures 2 to 4;

Figure 6 shows a perspective view of a turbine comprising a valve assembly according to a first embodiment of the present invention, where first and second sections of the turbine housing and valve housing are in a closed configuration;

Figure 7 shows a perspective view of a second section of a turbine housing and valve housing of the turbine shown in figure 6, where the first and second sections are in an open configuration;

Figure 8 shows a side perspective view of the section of the turbine housing shown in figure 7;

Figure 9 shows a rear perspective view of the sections of the turbine housing and valve housing shown in figure 8;

Figure 10 shows a perspective view of the second section of the turbine housing shown in figure 7;

Figure 11 shows another perspective view of the second section of the turbine housing shown in figure 7;

Figure 12 shows the turbine of Figure 6, with the first and second sections of the turbine housing and valve housing in the open configuration;

Figure 13 shows the first section of the turbine housing and valve housing of Figure 6;

Figure 14 shows a perspective view of a turbine comprising a valve assembly according to a second embodiment of the present invention, where first and second sections of the turbine housing and valve housing are in an open configuration;

Figure 15 shows a second perspective view of the turbine of Figure 14, where the first and second sections of the turbine and the valve housing are in the open configuration;

Figure 16 shows another perspective view of the turbine of Figure 14, where the first and second sections of the turbine and the valve housing are in the closed configuration;

Figure 17 shows another perspective view of the turbine of Figure 14, where the first and second sections of the turbine and the valve housing are in the closed configuration;

Figure 18 shows a perspective view of a section of a turbocharger comprising a valve assembly according to a third embodiment of the present invention, and

Figure 19 shows a perspective view of a section of a housing of the valve assembly shown in figure 18.

Figure 1 shows a schematic cross-section through a known turbocharger. The turbocharger comprises a turbine 1 joined to a compressor 2 via a central bearing housing 3.

The turbine 1 comprises a turbine wheel 4 mounted for rotation, about a turbocharger axis 99, within a chamber defined by a turbine housing 5.

The turbine housing 5 comprises an inlet volute 19 to which gas from an internal combustion engine (not shown) is delivered. The inlet volute 19 defines an annular inlet passageway 9 located annularly around the turbine wheel 4. The turbine housing 5 further comprises an axially extending outlet 20 which defines an outlet passageway 10 that extends axially from, and fluidly connects, the turbine wheel 4 to an outlet port 57.

In use, the exhaust gas flows from the annular inlet passageway 9 to the outlet passageway 10 via the annular inlet passageway 9 and the turbine wheel 4.

The compressor 2 comprises a compressor wheel 6 mounted for rotation, about the turbocharger axis 99, within a chamber defined by a compressor housing 7.

The compressor housing 7 has an inlet 21 that defines an axially extending air intake passage 11 which extends from, and fluidly connects, an inlet port 22 to the compressor wheel 6.

The compressor housing further comprises an outlet volute 23 that defines an annular outlet volute passage 12 that is arranged annularly around the compressor chamber. The outlet volute passage 12 is in fluid communication with a compressor outlet 25.

The turbine wheel 4 and compressor wheel 6 are mounted on opposite ends of a common turbocharger shaft 8 which extends through the central bearing housing 3.

The turbocharger shaft 8 rotates on journal bearings 13 and 14 housed towards the turbine end and compressor end respectively of the bearing housing 3. The compressor end bearing 14 further includes a thrust bearing 15 which interacts with an oil seal assembly including an oil slinger 16. Oil is supplied to the bearing housing from the oil system of the internal combustion engine via oil inlet 17 and is fed to the bearing assemblies by oil passageways 18. The oil fed to the bearing assemblies may be used to both lubricate the bearing assemblies and to remove heat from the bearing assemblies.

In use, the turbine wheel 4 is rotated by the passage of exhaust gas from the annular inlet passageway 9 to the outlet passageway 10. Exhaust gas is provided to the annular inlet passageway 9 from an exhaust manifold (also referred to as an outlet manifold) of the engine (not shown) to which the turbocharger is attached. The turbine wheel 4 in turn rotates the compressor wheel 6 which thereby draws intake air through the compressor inlet port 22 and the air intake passage 11 and delivers boost air to an inlet manifold of the engine via the outlet volute passage 12 and the outlet 25.

The annular inlet passageway 9 is defined by a portion of the turbine housing 5 which includes a turbocharger mounting flange 27 at the end of the annular inlet passageway 9 remote from the turbine wheel 4.

Figures 2 to 4 show various schematic views of portions of a known turbocharger 30 which includes a turbine 32 of a slightly different embodiment to that of Figure 1. The turbocharger 30 includes all of the features of the turbocharger described above in relation to Figure 1. The same numbering is used within Figures 2 to 4 for features of the turbocharger 30 shown in Figures 2 to 4 which are equivalent to features shown in the turbocharger of Figure 1.

In addition to the features of the turbine shown in Figure 1, in the turbine shown in Figures 2 to 4 the inlet volute 19 is a twin entry inlet volute defining first and second annular inlet passageways 9, 9’ that fluidly connects first and second turbine inlet ports (not shown) to the turbine wheel 4. In the currently described turbine, the twin entry volute is a twin flow volute. Alternatively, the twin entry volute may be a double flow volute. Twin flow and double flow volutes are known in the art and so will not be described in any more detail here.

The turbine housing 5 defines a first port 81 that opens into the second annular inlet passageway 9’ and a second port 82 that opens into the outlet passageway 10. The first and second ports 81, 82 are fluidly connected by a wastegate passage 34 (indicated schematically in dashed lines) which extends between the first and second ports 81, 82, and fluidly connects the second annular inlet passageway 9’ to the outlet passageway 10.

The turbine shown in Figures 2 to 4 also includes a valve assembly in the form of a wastegate assembly 85.

The wastegate assembly 85 includes a wastegate valve comprising a movable valve member 36 and a valve seat 38.

The valve member 36 is rotatably mounted within a wastegate outlet 26. A radially inner surface of the wastegate outlet 26 defines a wastegate outlet passage 28 that extends in the axial direction. The wastegate outlet passage 28 is radially adjacent to the outlet passageway 10 and is fluidly connected to the outlet passageway 10 by a partially circumferentially extending opening 31 provided at a radially inner side of the wastegate outlet passage 28.

The valve member 36 in this known turbocharger is of a flap type, comprising a substantially circular disc. The valve seat 38 is an annular region of a surface of the turbine housing 5 that surrounds the second port 82. The valve seat 38 is configured to be contactable with a surface of the valve member 36 in order to produce a substantially gas-tight seal between the valve seat 38 and the valve member 36 (as described in more detail below).

The wastegate valve has an open state, in which the valve member 36 is in a first rotational position, in the form of an open configuration (Figure 4 shows the valve member 36 in a partially open configuration), in which gas may pass from the second inlet passageway 9’ to the outlet passageway 10 via the wastegate passage 34 and the wastegate outlet passage 28, thereby bypassing the turbine wheel 4.

In use, as engine speed increases, the valve member 36 is moved to its open configuration when the pressure of the boost air increases towards a pre-determined level, thus allowing some of the exhaust gas to bypass the turbine wheel 4. This serves to increase the flow capacity of the turbine whilst limiting the turbocharger speed.

The wastegate valve also has a closed state, in which the valve member 36 is in a second rotational position, in the form of a closed configuration (as shown in Figure 3), in which the wastegate valve member 36 contacts, and substantially seals against, the valve seat 38. When the valve member 36 is in this rotational position, gas is substantially prevented from passing between the second inlet passageway 9’ to the outlet passageway 10 via the wastegate passage 34.

The valve member 36 is mounted to a valve shaft 39 having a longitudinal axis A. The valve shaft 39 is rotatably mounted to rotate about its longitudinal axis A. The valve member 36 is mounted to the valve shaft 39 such that it rotates with the valve shaft 39. The valve shaft 39 and valve member 36 are arranged such that rotation of the valve shaft 39 moves the valve member 36 between its open and closed rotational positions.

The valve member 36 is movable from its open rotational position to its closed rotational position (and vice-versa) by an actuation assembly 70. The actuation assembly 70 comprises an actuator 56 coupled to the valve shaft 39 by an actuator shaft 54 and a lever arm 46.

A first end of the actuator shaft 54 is connected to the actuator 56 and a second end 55 of the actuator shaft 54 is attached to a first end of an elongate lever arm 46. A second end of the lever arm 46 is mounted to a first end of the valve shaft 39 external to, and adjacent to, the wastegate outlet 26 of the turbine housing 5. In this regard, the valve shaft 39 is received within a bore provided at the second end of the lever arm 46 and is rotationally fixed relative to the lever arm 46 such that rotation of the lever arm 46 about the shaft axis (A) acts to rotate the valve shaft 39 about the shaft axis (A).

The valve shaft 39 passes through the valve shaft bore 40 that extends through the wall of the wastegate outlet 26.

The valve member 36 is mounted to a second end of the valve shaft 39 such that rotation of the valve shaft 39 about its axis (A) rotates the valve member 36 about said axis (A) between its open and closed rotational positions.

The actuator 56 is a pneumatic actuator and is arranged to move the actuator shaft 54 in a linear direction along the longitudinal axis of the actuator shaft 54. This acts to rotate the lever arm 46, and therefore the valve shaft 39 about the shaft axis (A), thereby moving the valve member 36 between its open and closed rotational positions. Such an actuation assembly is well known in the art and will not be described in any further detail here.

Referring to Figure 5 there is shown a turbocharger 50 which includes a turbine 51 slightly different to that of Figure 1. The turbocharger 50 includes all of the features of the turbocharger described above in relation to Figure 1. The same numbering is used within Figure 5 for features of the turbocharger 50 which are equivalent to features shown in the turbocharger of Figure 1.

The turbine 51 differs from the turbocharger of Figure 1 in that it is a variable geometry turbine. In this respect, the inlet passageway 9 is defined on one side by the face 73 of a radial wall of a movable annular wall member 74, commonly referred to as a “nozzle ring”, and on the opposite side by an annular shroud plate 75 which forms the wall of the inlet passageway 9 facing the nozzle ring 74. The shroud plate 75 covers the opening of an annular chamber 76 in the turbine housing 1.

The nozzle ring 74 is movable in the axial direction, relative to the axially fixed shroud plate 75 so as to vary the width of the inlet passageway 9 to optimise gas flow velocities over a range of mass flow rates so that the power output of the turbine 51 can be varied to suit varying engine demands. For instance, when the volume of exhaust gas being delivered to the turbine 51 is relatively low, the velocity of the gas reaching the turbine wheel 4 is maintained at a level which ensures efficient turbine operation by reducing the size of the annular inlet passageway 9.

The nozzle ring 74 supports an array of equi-angularly spaced inlet vanes 47 each of which extends axially across the inlet passageway 9. The vanes 47 are orientated to deflect gas flowing through the inlet passageway 9 towards the direction of rotation of the turbine wheel 4.

When the nozzle ring 74 is proximate to the annular shroud plate 75, the vanes 47 project through suitably configured slots 87 in the shroud plate 75, into the chamber 76.

An actuator (not shown) is operable to control the position of the nozzle ring 74 via an actuator output shaft (not shown), which is linked to a stirrup member 77. The stirrup member 77 in turn engages axially extending guide rods 78 that support the nozzle ring 74. Accordingly, by appropriate control of the actuator (which may for instance be pneumatic, hydraulic or electric), the axial position of the guide rods 78 and thus of the nozzle ring 74 can be controlled. It will be appreciated that details of the nozzle ring mounting and guide arrangements may differ from those illustrated.

The nozzle ring 74 has axially extending radially inner and outer annular flanges 79 and 80 that extend into an annular cavity provided in the turbine housing 5 and the bearing housing 3. Inner and outer sealing rings 84, 86 are provided to seal the nozzle ring 74 with respect to inner and outer annular surfaces of the annular cavity respectively, whilst allowing the nozzle ring 74 to slide within the annular cavity in an axial direction. The inner sealing ring 84 is supported within an annular groove formed in the radially inner annular surface of the cavity and bears against the inner annular flange 79 of the nozzle ring 74. The outer sealing ring 86 is supported within an annular groove formed in the radially outer annular surface of the cavity and bears against the outer annular flange 80 of the nozzle ring 74. It will be appreciated that the inner and/or outer sealing rings could be mounted in a respective annular groove in the nozzle ring flanges rather than as shown.

Alternatively, or additionally, the shroud plate 75 may be movable in the axial direction 99 to vary the width of the inlet passageway 9.

In this turbine, the inlet port 81 of the wastegate passage 34 is located at the shroud plate side of the annular chamber 76. The slots 87 in the shroud plate 75 provide a leakage path for flow to pass from the inlet passageway 9 to the chamber 76. The chamber 76 forms the wastegate passage 34. As with the turbine of Figures 2 to 4, the second port 82 is selectively opened and closed by the rotatable valve member 36.

Referring now to Figures 6 to 13, there is shown a turbine 132 according to a first embodiment of the second aspect of the invention. The turbine 132 comprises a valve assembly, in the form of a wastegate assembly 185, according to a first embodiment of the first aspect of the invention.

The turbine 132 is substantially the same as the turbine described in relation to Figures 2 to 4 except for the differences described below. The same numbering is used in Figures 6 to 13, as in Figures 2 to 4, but incremented by 100, to denote equivalent features.

The turbine housing 105 comprises first and second sections 151, 152. The first section 151 comprises the inlet volute 119 and an upstream portion of the outlet 120. The second section 152 forms a downstream section of the outlet 120. As shown most clearly in Figure 12, the inlet volute 119 has two turbine inlet ports 101, 102, that are fluidly connected to the turbine wheel (not shown) by first and second annular inlet passageways 109, 109’ respectively. The outlet passageway 110 is defined by the second section 152 of the turbine housing 105. The first and second sections 151, 152 of the turbine housing 105 are axially adjacent to each other in the direction of the turbocharger axis 99.

The first and second sections 151, 152 are attachable to each other. In this respect, an upstream end of the second section 152 is attachable to a downstream end of the first section 151.

When the first and second sections 151, 152 are attached to each other, in a closed configuration (as shown in Figure 6), respective mating surfaces 15T, 152’ of the first and second sections 151, 152 are in contact with each other. The mating surfaces 15T, 152’ are in contact along an interface which defines a plane 163. The interface plane 163 is a substantially flat plane.

A valve member 136 and a valve shaft 139 are mounted within a valve housing 190.

The valve shaft 139 is rotatable about its longitudinal axis A, to move the valve member 136 between an open rotational position, and a closed rotational position in which the valve member 136 blocks a valve seat 138. The valve housing 190 comprises a first section 191 in the form of a main body and a second section 192 in the form of a cover. The first section 191 of the valve housing 190 is integrally formed with the first section 151 of the turbine housing 105. The second section 192 is integrally formed with the second section 152 of the turbine housing 105.

The second section 192 is disposed axially adjacent to, and downstream of, the first section 191. The second section 192 is attachable to the first section 191 so as to cover the first section 191. Typically, in use, the second section may be permanently connected to the first section 191, for example by welding. However, alternatively the second section 192 may be releasably attachable to the first section 191 so as to selectively cover, or allow access within, the first section 191. This is to allow access to the valve, for example during maintenance, to allow replacement of the valve member 136, valve shaft 139 and valve seat 138 (if this is a removable part).

When the first and second sections 191, 192 are in the closed configuration, they together define the wastegate outlet passage.

When the second section 192 is attached to the first section 191, respective mating surfaces 191’, 192’ of the first section 191 and second section 192 are in contact with each other. The mating surfaces 19T, 192’ are in contact along an interface which defines an interface plane 193 (see Figure 6). The interface plane 193 is a substantially flat plane.

The interface planes 163, 193 are substantially aligned with each other and are substantially parallel such that they form a common interface plane 200. In this respect, referring to Figure 7, the mating surfaces 192’, 152’ of the second sections 192, 152 of the valve housing 190 and of the turbine housing 105 respectively are substantially contained within the interface plane 200.

The valve shaft 139 passes through a valve shaft bore 140 in a first side wall 301 of the second section 192 of the valve housing 190 (see figure 7). As with the embodiment of figures 2 to 4, a first end of the actuator shaft 154 is connected to the actuator 156 and a second end of the actuator shaft 154 is attached to a first end of an elongate lever arm 146. A second end of the lever arm 146 is mounted to a first end of the valve shaft 139 external to, and adjacent to, the second section 192 of the valve housing 190. In this regard, the first end of the valve shaft 139 is received within a bore provided at the second end of the lever arm 146 and is rotationally fixed relative to the lever arm 146 such that rotation of the lever arm 146 about the shaft axis (A) rotates the valve shaft 139 about the shaft axis (A). The valve member 136, in the form of a flap valve member, is mounted to the second end of the valve shaft 139 such that rotation of the valve shaft 139 about its axis (A) rotates the valve member 136 about said axis (A) between its open and closed rotational positions.

Accordingly the valve member 136, and the valve shaft 139, are rotatably mounted in the second section 192 of the valve housing 190.

The mating surfaces 192’, 152’ of the second sections 192, 152 of the valve housing 190 and of the turbine housing 105 respectively are substantially flat, and lie in an interface plane 200 which is inclined relative to the shaft axis (A) and crosses the shaft axis (A).

Referring to Figure 7, the shaft axis (A) is inclined at an angle (a) of 20 degrees relative to its orthogonal projection (P) on said interface plane 200. In this respect, the orthogonal projection (P) of the shaft axis (A) on the plane 200 is a line oriented such that each point along the line, a normal to the plane 200 intersects the shaft axis (A).

The shaft axis A intersects the plane 200 at a point substantially midway along the axial length of the second section 192 of the valve housing 190.

Similarly, the respective mating surfaces 15T, 191’ of the first section 151 of the turbine housing 105 and the first section 191 of the valve housing 190 substantially extend within a plane that is substantially parallel to the plane 200.

When the first and second sections 151, 152, of the turbine housing 105, and the first and second sections 191, 192 of the valve housing 190 are attached to each other, in the closed configuration, their respective mating surfaces 15T, 152’, 19T, 192’ are in contact along said respective planes 163, 193.

The first and second sections 151, 152, of the turbine housing 105, and the first and second sections 191, 192 of the valve housing 190 are movable from the closed configuration (shown in Figure 6) to an open configuration (shown in Figure 7, 8, 9, 10 and 11 - with the first sections 151, 191 of the turbine housing 105 and valve housing 190 omitted for illustrative purposes - and in Figure 12). When the first and second sections 151, 152, of the turbine housing 105, and the first and second sections 191, 192 of the valve housing 190, are in the open configuration, they are axially spaced from each other such that their respective mating surfaces 15T, 152’, 19T, 192’ are not in contact with each other.

Due to the angle of the interface 200 plane formed by the mating surface 192’ of the second section 192 of the valve housing 190, relative to the shaft axis (A), when the first and second sections 191, 192 of the valve housing 190 are in the open configuration the valve member 136, and the valve shaft 139, are movable (translatable) from their rotatably mounted position (“first translational position”) in the second section 192 of the valve housing 190, to a second translational position position external to said second section 192 by being moved in a substantially straight line, that is substantially parallel to the shaft axis (A). It will be appreciated that the valve shaft 139, and the valve member 136, are movable from their rotatably mounted first translational position in the second section 192 of the valve housing 190, to the second translational position external to said second section 192 by being moved only in said substantially straight line.

Similarly, due to the angle of the interface 200 plane formed by the mating surface 152’ of the second section the turbine housing 152, relative to the shaft axis (A), when the first and second sections 151, 152 of the turbine housing 105 are in the open configuration (which they will be in when the first and second sections 191, 192 of the valve housing 190 are in the open configuration, by virtue of the first and second sections 191, 192 of the valve housing 190 being integrally formed with the first and second sections 151, 152 of the turbine housing 105 respectively), the valve member 136, and the valve shaft 139, are movable from the second section 192 of the valve housing 190, to a second translational position external to the second section 152 of the turbine housing 105 by being moved (translated) in a substantially straight line, that is substantially parallel to the shaft axis (A). It will be appreciated that the valve shaft 139, and the valve member 136, are movable from their rotatably mounted first translational position in the second section 192 of the valve housing 190, to a second translational position external to said second section 152 of the turbine housing 105 by being moved only in said substantially straight line.

Accordingly, when the first and second sections 191, 192 of the valve housing 190, and the first and second sections 151, 152 of the turbine housing 105 are in the open configuration, the valve member 136, and the valve shaft 139, are movable from their rotatably mounted first translational position in the second section 192 of the valve housing 190, to a second translational position external to the second section 152 of the turbine housing by being moved in a substantially straight line, that is substantially parallel to the shaft axis (A).

Similarly, in a reverse manner, when the first and second sections 191, 192 of the valve housing 190, and the first and second sections 151, 152 of the turbine housing 105 are in the open configuration, the valve member 136, and the valve shaft 139, are movable from a second translational position external to the second section 152 of the turbine housing to their rotatably mounted first translational position in the second section 192 of the valve housing 190, by being moved in a substantially straight line, that is substantially parallel to the shaft axis (A). It will be appreciated that the valve shaft 139, and the valve member 136, are movable from a second translational position external to said second section 192 of the valve housing 190, to their rotatably mounted first translational position in the second section 192 of the valve housing 190, by being moved only in said substantially straight line.

It will be appreciated that when the first and second sections 191, 192 of the valve housing 190, and the first and second sections 151, 152 of the turbine housing 105 are in the open configuration, the opposed mating surfaces 151’, 152’, 191’, 192’ are axially spaced sufficiently from each other that there is a sufficient clearance between the mating surfaces 151’, 152’, 191’, 192’ to allow the valve member 136, and the valve shaft 139, to pass from said external second translational position to said internal first translational position (or vice versa) in substantially straight line, that is substantially parallel to the shaft axis (A).

The clearance may be defined between said opposed mating surfaces 15T, 152’, 19T, 192’ of the first and second sections of the valve and turbine housings. Alternatively, where the first and second sections are moved away from each other such that they are remote from each other, the clearance may be defined solely by the mating surfaces 192’, 152’ of the second section 192, 152 of the valve housing 190 and turbine housing 105 (or by the mating surfaces 191’, 151 ’ of the first section 191, 151 of the valve housing 190 and turbine housing 105 if the valve member 136 is rotatably mounted in the first section of the housing 105 (see below)).

In this respect, as stated above, the valve shaft 139 is rotatably mounted to the first side wall 301 of the second section 192 of the valve housing 190 and said clearance is defined by a section of the mating surface 152’ of the second section 152 of the turbine housing 105 disposed at an opposite end of said second section 152 to the first side wall 301.

In order to assemble the wastegate assembly 185, the first and second sections 191, 192 of the valve housing 190, and the first and second sections 151, 152 of the turbine housing 105 are arranged in the open configuration.

The valve shaft 139 (and the valve member 136 which is mounted on the valve shaft 139) is then moved from a second translational position external to the second section 152 of the turbine housing 105 to its rotatably mounted first translational position, in which it is received within the valve shaft bore 140, by being moved in a substantially straight line, that is substantially parallel to the shaft axis (A). It will be appreciated that the valve shaft 139 is only moved in said substantially straight line from said external second translational position to its rotatably mounted first translational position. The first and second sections 151, 152 of the turbine housing 105 are then moved from the closed configuration to the open configuration.

The first and second sections 191, 192 of the valve housing 190, and the first and second sections 151, 152 of the turbine housing 105 are then moved from the open configuration to the closed configuration.

Similarly, in order to disassemble the wastegate assembly 185, the first and second sections 191, 192 of the valve housing 190, and the first and second sections 151, 152 of the turbine housing 105 are moved from the closed configuration to the open configuration.

The valve shaft 139 (and the valve member 136 which is mounted on the valve shaft 139) is then moved from its rotatably mounted first translational position to a second translational position external to the second section 152 of the turbine housing 105 by being moved in a substantially straight line, that is substantially parallel to the shaft axis (A). It will be appreciated that the valve shaft 139 is only moved in said substantially straight line from its rotatably mounted first translational position to said external second translational position.

Being able to rotabably mount, the valve shaft 139 and valve member 136, in/from the second section 192 of the valve housing 190 and the second section 152 of the turbine housing 105 by moving them only a substantially straight line, that is substantially parallel to the shaft axis (A) is advantageous in that it allows the wastegate assembly 185 to be assembled in a relatively large number of different positions and orientations. The ease with which the wastegate value member 136 and valve shaft 139 can be inserted into the valve housing 190, and the fact that the the mating surfaces 151’, 152’, 19T, 192’ are inclined to the rotational axis of the turbine, provide flexibility in the overall design of the turbine 132 and therefore of the turbocharger as a whole. They allow for a relatively large number of different possible orientations of the actuator shaft 154 and therefore allows for a relatively large number of different possible positions of the actuator 156. This provides greater flexibility to the overall possible configurations of the turbine 132, as well as of the turbocharger as a whole.

Turning to Figs. 14-17, there is shown a turbine according to a second embodiment of the invention. Features of the second embodiment corresponding to features of the first embodiment are given corresponding reference numerals, but incremented by 100 (and incremented by 200 relative to features of the turbocharger shown in figures 1 to 5). In this embodiment, the first section 251 of the turbine housing 205 is the one defining the outlet passageway 210, while the second section 252 of the turbine housing 205 is the one defining the inlet volute 219. The inlet volute 219 has two turbine inlet ports 201, 202. The first and second sections 251, 252 of the turbine assembly have respective mating surfaces 251 ’, 252’.

The valve housing 290 comprises a first section 291 having a mating surface 29T, and a second section 292 having a mating surface 292’. The second section 292 of the valve housing 290 houses a valve member 236 which is a portion of a wastegate assembly 285. The wastegate assembly 285 is controlled by an actuator shaft 254.

As in the first embodiment of the invention, when the turbine is in the open configuration shown in Figs. 14 and 15, the valve member 236 may be removed from the second section 292 of the valve housing 290, and from the second section 252 of the turbine housing 205, by a motion in a straight line parallel to an axis A which lies along an axis of a valve shaft (not shown) supporting the valve member 236 and coupled to the actuator shaft 254.

In the first two embodiments of the invention, the valve assembly is a wastegate assembly 185, 285. Similar advantages arise with different types of valve assembly. In this regard, referring to Figures 18 and 19 there is shown a section of a turbocharger comprising a valve assembly according to a third embodiment of the present invention. The turbo charger as shown in figures 18 and 19 comprises a turbine 332, that is identical to the turbine 132, shown in figures 6 to 13 except for the differences described below. Corresponding features are given corresponding reference numerals, but incremented by 200 (and incremented by 300 relative to features of the turbocharger shown in figures 1 to 5).

The turbine of this embodiment differs from that shown in figures 6 to 13, and that of figures 14 to 17, in that the valve assembly 385 forms a balancing valve assembly 385, as opposed to a waste gate assembly 185, 285.

In this respect, the turbine inlet comprises first and second inlet ports 301,302, that are fluidly connected to the turbine wheel (not shown) by first and second annular inlet passageways 309, 309’ respectively.

The turbine housing 305 defines a first port (not shown) that opens into the first inlet passageway 309, and a second port (not shown) that opens into the second annular inlet passageway 309’. The first and second ports are fluidly connected by a balancing passage (not shown) which extends between the first and second ports.

The valve assembly 385 comprises a balancing valve comprising a valve member 336, in the form of a flap valve member, and a valve seat (not shown). The valve seat is an annular region of the surface of the turbine housing 305 that surrounds the second port. The valve seat is configured to be contactable with the surface of the valve member 336, in order to produce a substantially gas-type seal between the valve seat and the valve member 336.

The valve member 336 is movable between an open rotational position and a closed rotational position so to allow or prevent gas passing through the second port, and therefore through the balancing passageway. Accordingly, the valve member 336 is movable so as to vary the amount of flow that may pass from the first inlet passageway 309, to the second inlet passageway, 309’ or vice-versa.

The valve member 336 is mounted to a valve shaft 339, having a longitudinal axis A. The valve shaft 339 is rotatably mounted to rotate about its longitudinal axis A. The valve member 336 is mounted to the valve shaft 339 such that it rotates with the valve shaft 339. The valve shaft 339 and the valve member 336 are arranged such that rotation of the valve shaft 339 moves the valve member 336 between its open and closed rotational positions.

The valve member 336 is movable from its open rotational position to its closed rotational position (and vice-versa) by an actuation assembly 370. The actuation assembly 370 comprises an actuator 356, coupled to the valve shaft 339 by an actuator shaft 354 and a lever arm 346.

As with the preceding embodiments, the valve member 336 and the valve shaft 339 are mounted within a valve housing 390. The valve housing 390 comprises a first section 391 and a second section 392.

A first end of the actuator shaft 354 is connected to the actuator 356 and the second end of the actuator shaft 354 is attached to a first end of an elongate lever arm 346. A second end of the lever arm 346 is mounted to a first end of the valve shaft 339.

The valve shaft 339 is received within a bore provided at the second end of the lever arm 346 and is rotationally fixed relative to the lever arm 346 such that rotation of the lever arm 346 about the shaft axis (A) acts to rotate the valve shaft 339 about the shaft axis (A).

The valve shaft 339 passes through a valve shaft bore 340 that extends through a side wall of the second section 392 of the valve housing 390.

The second section 392 is attachable to the first section 391 so as to selectively cover the first section 391. When the second section 392 is attached to the first section 391, respective mating surfaces 39T, 392’ of the first and second sections

391, 392 are in contact with each other. The mating surfaces 39T, 392’ are in contact along an interface which defines an interface plane 393. The interface plane 393 is a substantially flat plane. The interface plane 393 is inclined relative to the shaft axis (A) such that it crosses the shaft axis (A). As in the preceding embodiment, the shaft axis (A) is inclined at an angle (a) relative to its orthogonal projection (P) on the interface plane 393.

The orientation of the shafts axis (A) and the interface plane 393 is as described for the preceding embodiment. In this regard, due to the angle of the interface plane 393 relative to the shaft axis (A), when the first and second sections 391,392 of the valve housing 390 are in the open configuration the valve member 336 and the valve shaft 339 are movable from the first translational position in which they are rotatably mounted to the second section 392 of the valve housing 390, to a second translational position external to the second section 392 by being moved in a substantially straight line, that is substantially parallel to the shaft axis (A). It will be appreciated that the valve shaft 339 and the valve shaft member 336 are movable from their rotatably mounted first translational position in the second section 392 of the valve housing 390 to a second translational position external to the second section 392 by being moved only in said straight line. The valve member 336 and valve shaft 339 are also movable in the opposite sense, i.e. from a second translational position external to the second section 392 to the rotatably mounted first translational position. This arrangement is as described for the preceding embodiment and will not be described in any further detail here.

The described and illustrated embodiments are to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the scope of the inventions as defined in the claims are desired to be protected.

For example, in the described embodiments the interface plane 200 is substantially flat. Alternatively, the interface plane 200 may be curved or partly curved along its length. The mating surfaces 15T, 152’, 191 ’, 192’, 251 ’, 252’, 291 ’, 292’, 391 ’, 392’ of the first and second sections 151, 152, 191, 192, 251,252, 291,292, 391,392 of the valve housing 190, 290 and turbine housing 105, 205, 305 may have a stepped shape.

In such cases, the mating surface of the second section of the valve housing, rather than defining a plane, would define a convex hull which intercepts the shaft axis. The shaft axis would preferably be inclined at an angle to the convex hull of the mating surface of the second section of the valve housing at at least one of the two points where it intersects the convex hull.

Similarly, the mating surfaces of each section of the turbine housing would define a respective convex hull which intersects the rotational axis. At at least one intersection point, the rotational axis would preferably be inclined at an angle to the respective convex hulls of the mating surfaces of the sections of the turbine housing. Typically, the shaft axis, if it intersects with the respective convex hulls of the mating surfaces sections of the turbine housing, would be inclined to them also at the intersection point.

In the described embodiments, when the first and second sections 151, 152, 251, 252 of the turbine housing 105, 205, 305, and the first and second sections 191,192, 291,292, 391, 392 of the valve housing 190, 290, 390, are in the open configuration, they are axially spaced from each other such that their respective mating surfaces 15T, 152’, 19T, 192’, 25T, 252’, 29T, 292’, 39T, 392’ are not in contact with each other. Alternatively, when said sections are in the open configuration, they may be partially in contact. For example, the respective mating surfaces 15T, 152’, 19T, 192’, 25T, 252’, 29T, 292’, 39T, 392’ of the first and second sections of the valve and turbine housing may be slid relative to an open configuration in which the mating surfaces are still partly in contact but there is sufficient clearance to allow the valve member 136, 236, 336, and the valve shaft 139, 339, to pass from said internal first translational position to said external second translational position (or vice versa) in a substantially straight line, that is substantially parallel to the shaft axis (A).

The actuator may be of any suitable type, including a pneumatic, hydraulic or electrical actuator.

The wastegate assembly 185 of the first or second embodiment may be used in a variable geometry turbine, such as that shown in Figure 5, using the described variable geometry arrangement.

In the described embodiments, the valve assembly is used with a twin entry volute.

Alternatively, the valve assembly may be used with a single entry volute, i.e. where the turbine comprises a single annular inlet passageway.

Claims

1. A valve assembly comprising:

a valve housing defining first and second ports and a passage fluidly connecting the first and second ports;

a valve member;

a valve shaft coupled to the valve member and having a shaft axis;

wherein the valve member and valve shaft are rotatably mountable to the second section of the valve housing in a first translational position, the actuator being operative, when the valve member and the valve shaft are in the first translational position, to rotate the valve shaft about the shaft axis, whereby the valve shaft rotates the valve member between a first rotational position in which it substantially seals the second port, and a second rotational position in which it allows fluid to flow through the second port, the first and second sections of the valve housing are movable, relative to each other, from an open configuration to a closed configuration in which the respective mating surfaces are in contact, and in the open configuration, the valve member and valve shaft are movable together to the first translational position in a substantially straight line which is substantially parallel to the shaft axis, from a second translational position in which the valve member and valve shaft are external to said second section of the valve housing.

2. A valve assembly according to claim 1 in which the first and second sections of the valve housing are releasably attachable to each other in the closed configuration.

3. A valve assembly according to claim 1 or claim 2 wherein the valve shaft is mountable in the first translational position to a first wall of said second section of the housing rotatably about the shaft axis, and there is a clearance between the shaft axis and a surface of an opposed second wall of said second section of the housing.

4. A valve assembly according to any preceding claim in which, when the first and second sections are in the closed configuration, the valve housing defines a passage fluidly connecting the second port to an outlet of the valve housing.

5. A valve assembly comprising:

a valve member;

a valve shaft coupled to the valve member and having a shaft axis;

wherein the valve member is rotatably mounted to the second section of the valve housing, the actuator being operative to rotate the valve shaft about the shaft axis, whereby the valve shaft rotates the valve member between a first rotational position in which it substantially seals the second port, and a second rotational position in which it allows fluid to flow through the second port, and wherein the shaft axis does not intercept the second section of the valve housing.

6. A valve assembly according to any preceding claim wherein the mating surface of said second section of the valve housing extends substantially in a plane, and said plane intercepts said shaft axis.

7. A valve assembly according to claim 5 or 6 wherein the shaft axis is inclined at a non-zero angle relative to its orthogonal projection on said plane, preferably in the range 10 to 20 degrees.

8. A valve assembly according to any of claims 5 to 7 in which the mating surface of said second section of the valve housing defines a convex hull, and the shaft axis intersects with said convex hull at an angle in the range 10 to 80 degrees.

9. A valve assembly according to any preceding claim wherein the actuator is coupled to the valve shaft by an actuator shaft, the actuator being arranged to move the actuator shaft in a direction along an axis of the actuator shaft such that said movement rotates the valve shaft about its axis.

10. A valve assembly according to claim 9 wherein the valve shaft passes through a bore in said second section of the valve housing and wherein the actuator shaft is disposed externally to said second section of the valve housing.

11. A turbine comprising:

a turbine housing having an inlet and an outlet;

the inlet comprising a substantially annular inlet passageway;

wherein the turbine comprises a valve assembly according to any preceding claim, with the first and second sections being attached to each other;

the first port of the valve assembly being in fluid communication with the inlet passageway and the second port being in fluid communication with an outlet such that gas passing along the passageway from the first port to the second port, and to the outlet, bypasses the turbine wheel.

12. A turbine according to claim 11 in which a normal direction to the convex hull of the mating surface of the second section of the valve assembly, at the interception point of the convex hull with the shaft axis, is at an angle to the rotational axis which is greater than zero degrees and less than 90 degrees.

13. A turbine according to claim 11 or 12 wherein the turbine housing comprises first and second sections that are attachable to each other and have respective mating surfaces that are in contact when the first and second sections are attached to each other and wherein the mating surfaces of the first and second sections of the turbine housing are arranged such that the first and second sections of the turbine housing are movable, relative to each other, to an open configuration in which, when the first and second sections of the valve housing are in the open configuration, the valve member is movable to a second translational position external to said first and second section of the turbine housing along said substantially straight line.

14. A turbine according to claim 13 wherein the mating surface of said first or second section of the turbine housing has a convex hull which intercepts the rotational axis at an angle which is greater than zero degrees and less than 90 degrees.

15. A turbine according to claim 13 or 14 wherein the mating surface of said first or second section of the turbine housing extends substantially in a plane.

16. A turbine according to claim 15, wherein the valve assembly is according to claim 7, and wherein the mating surface of the first or second section of the turbine housing extends substantially in the same plane as that defined by the mating surface of the second section of the valve housing.

17. A turbine according to any of claims 11 to 16 wherein the first or second section of the turbine housing forms the inlet of the turbine housing and the second or first section of the turbine housing forms the outlet of the turbine housing respectively.

18. A turbine according to any of claims 11 to 17 wherein when the first and second sections of the turbine housing are in the open configuration, respective clearances exist between the shaft axis and opposed surfaces of the first and second sections of the turbine housing.

19. A turbine according to any of claims 11 to 18 in which the inlet comprises a substantially annular inlet passageway, the first port of the valve assembly being in fluid communication with the inlet passageway and the second port being in fluid communication with an outlet such that gas passing along the passageway from the first port to the second port, and to the outlet, bypasses the turbine wheel.

20. A turbine according to any of claims 11 to 19 in which the inlet comprises first and second inlet ports fluidly connected to the turbine wheel by first and second annular inlet passageways respectively;

the first port of the valve assembly being in fluid communication with the first inlet passageway and the second port being in fluid communication with the second inlet passageway.

21. A method of assembling a valve assembly according to any of claims 1 to 10, wherein the method comprises moving the valve member from the second translational position to the first translational position by moving the valve member in a substantially straight line substantially parallel to the shaft axis.

22. A method of assembling a turbine, said turbine comprising:

a turbine housing having an inlet and an outlet;

a turbine wheel mounted in the turbine housing between the inlet and outlet, for rotation about an axis; and a valve assembly according to any of claims 1 to 4;

the method comprising moving the valve member and valve shaft from the second translational position to the first translational position in said substantially straight line parallel to the shaft axis.

23. A method according to claim 22 wherein the turbine housing comprises first and second sections that are attachable to each other and have respective mating surfaces that are in contact when the first and second sections of the turbine housing are attached to each other in a closed configuration, the method comprising, prior to said step of moving the valve member, moving the first and second sections of the turbine housing, relative to each other, to an open configuration,and preferably comprising, subsequent to said step of moving the valve member, moving the first and second sections of the turbine housing, and the first and second sections of the valve housing from their open configuration to their closed configuration.

24. A method according to any of claims 22 to 23 wherein:

the inlet comprises a substantially annual inlet passage; and

5 the first port of the valve assembly is in fluid communication with the inlet passageway and the second port is in fluid communication with an outlet such that gas passing along the passageway from the first port to the second port, and to the outlet, bypasses the turbine wheel.

25. A method according to any of claims 22 to 23, wherein the inlet comprises 10 first and second inlet ports, and is fluidly connected to the turbine wheel by first and second annular inlet passageways respectively;