The present invention relates to valves and, more particularly, to torque motor actuated throttle valves.

Valves, such as throttle valves, are often employed to regulate fluid flow streams in engines. Such valves may be utilised in the exhaust system of an engine where the flapper element of the throttle valve is subjected to considerable fluid forces and elevated temperatures. Engines inherently vibrate and subject the throttle valve as a whole to varying thermal loads.

Throttle valves of the type described above are typically actuated by a torque motor. The torque motor is provided with an output shaft which requires alignment with and connection to a shaft of the throttle valve which carries the flapper element. It will be appreciated that vibration, dynamic loading and thermal loading can affect the alignment and connection of the shafts, in use. It will also be appreciated that each shaft requires to be supported by separate bearing arrangements located within the torque motor and throttle valve respectively.

According to the present invention there is provided a combined torque motor and throttle valve assembly, the throttle valve including a housing having a bore extending therethrough and a flapper element rotatably mounted within the bore, and the torque motor including a stator having a coil and a core, wherein the core has opposing ends which are positioned respectively proximal and distal to the bore, wherein the torque motor and throttle valve share a common shaft which extends from the torque motor and through the bore of the housing and to which shaft the flapper element is fixed for rotation, and wherein the shaft is supported at opposing ends by two bearings comprising a first bearing located on a first side of the bore within the torque motor and at the end of the core distal to the bore, and a second bearing located within the housing on the opposing side of the bore to the first bearing. The present invention provides a combined torque motor and throttle valve assembly having a single common shaft which is supported at opposing ends by only two bearings. The single common shaft may comprise a single piece shaft. The use of a single piece shaft seeks to overcome the alignment issues mentioned above in relation to the connection of a torque motor shaft to a throttle valve shaft. The present invention has a reduced complexity and increased robustness when compared to prior art systems where the torque motor and throttle valve have separate shafts that require alignment and connection during assembly of the torque motor and throttle valve combination.

The first bearing is adapted to accommodate both axial and radial loads. The first bearing may, for example, be a single row angular contact bearing. The radial load on the first bearing is generated by forces acting upon the flapper element of the throttle valve.

The second bearing is adapted to accommodate radial loads. The second bearing may, for example, be a needle roller bearing. The radial load on the second bearing is also generated by forces acting upon the flapper element of the throttle valve. The first bearing may be located in a seat provided within the core of a stator of the torque motor. The first bearing may be located between the core component and the rotor of the torque motor and may further ensure the correct separation distance between the rotor and the stator. It will thus be understood that the axial load on the first bearing is generated by magnetic forces attracting the rotor of the torque motor to the stator. This magnetic attraction has the advantage of resisting vibration loads that are experienced by the torque motor and throttle valve assembly, in use. The need to spring load the shaft to resist such vibration loads is thus removed.

The stator of the torque motor includes a coil and a core, wherein the core is a multi- component core. The core may comprise three components. The core may comprise a central core component and opposing outer core components which, when assembled, partially surround the coil. In an alternative embodiment the core may comprise two components. In such an embodiment the core may comprise a central core component and a combined base and outer core component. The coil is preferably a substantially rectangular when viewed in plan and as such has two opposing long sides and two opposing short sides. In such an embodiment each long side of the coil is sandwiched between the central core component on one side and an outer core component on the other side. Each short side of the coil is however only bounded on one side by the central core component while the opposing side is exposed.

The shaft is further provided with a return spring assembly which is located housing on the opposing side of the bore to the location of the torque motor. An embodiment of the present invention will now be described with reference to the accompanying drawings in which:

Figure 1 shows an exploded view of a combined torque motor and throttle valve assembly according to the present invention; and

Figure 2 shows a cross-sectional view of the assembly of figure 1.

Referring to the figures there is shown a combined torque motor and throttle valve assembly generally designated 10. The assembly 10 comprise a torque motor generally designated 12 and a throttle valve generally designated 14.

The throttle valve 14 includes a housing 16 having an inlet aperture 18, an outlet aperture 20 and a substantially circular bore 22 extending between the apertures 18,20. The housing 16 may be formed by extrusion. The throttle valve 14 further includes a substantially circular flapper element 24 which, in use, is mounted for rotation within the bore 22 of the housing 16. The flapper element 24 is mounted for rotation about an axis that is perpendicular to the longitudinal centreline axis of the bore 22. The manner in which the flapper element 24 is mounted for rotation will be described in greater detail below. The housing 16 is further provided with an external mounting face 26 to which the torque motor 12 is mounted. The mounting face 26 is provided with a through aperture 28 which extends from the exterior of the housing 16 to the bore 22. The mounting face aperture 28 is aligned with a further through aperture 30 of the housing 16. The further through aperture 30 extends from the bore 22 to the exterior of the housing 16 on the opposite side of the housing 16 to the mounting face 26. The through apertures 28,30 are aligned along the rotational axis of the flapper element 24. The further through aperture 30 of the housing 16 extends to the exterior of the housing 16 through a substantially circular projection 32 of the housing 16.

The housing 16 is additionally provided with a plurality of mounting apertures 34. The mounting apertures 34 are aligned parallel to the bore 22 and, in use, allow the assembly 10 to be connected by the use of appropriate fasteners to conduits which extend on opposing sides of the housing 16. In the embodiment shown the housing 16 is provided with four mounting apertures 34. It will be appreciated that a greater or lesser number of apertures 34 may be provided depending upon the intended manner in which the assembly 10 is to be integrated into a larger fluid management system. It will further be appreciated that other arrangements for the connection of the assembly 10 to a larger fluid management system may be provided.

The torque motor 12 includes a base plate 36, a cover 38, a rotor generally designated 40 and a stator generally designated 42.

The stator 42 includes an iron core 44 and an annular coil 46. The core 44 is of a three piece construction and comprises a central core component 44a and two outer core components 44b, 44c. The coil 46 is supported on an annular coil carrier 48. The coil and coil carrier 46,48, when viewed in plan, have a generally rectangular shape having two long sides and two short sides. The centre aperture 50 of the coil carrier 48 is correspondingly rectangular in shape. The core 44 has opposing ends 43,45 which are respectively proximal and distal to the bore 22 of the housing 16. Each core component 44a,44b,44c is provided with a projection 52a,52b,52c which is received in a correspondingly shaped aperture 54a,54b,54c of the base plate 36. In the embodiment shown the central core component 44a is provided with a circular projection 52a which is received in a circular aperture 54a of the base plate 36. The outer core components 44b, 44c are provided with lozenge shaped projections 52b, 52c which are received in respective lozenge shaped apertures 54b, 54c of the base plate 36. The circular aperture 54a of the plate 36, in use, aligns with the aforementioned through aperture 28 of the housing 16. The lozenge shaped apertures 52b, 52c of the base plate 36, in use, align with blind threaded holes 56 provided in the external mounting face 26 of the housing 16.

The central core component 44a is further provided with a shaft bore 58 and a body portion 60 having a cross-sectional shape which corresponds to the rectangular centre aperture 50 of the coil carrier 48. On the opposing side of the central core component 44a to the circular projection 52a and surrounding the shaft bore 58 there is provided a part-circular recess defining a bearing seat 62. Extending on opposing sides of the bearing seat 62 there are provided a pair of substantially flat surfaces 64,66 each of which, when viewed in plan, has the shape of an annular sector. The bearing seat 62 is provided on the end 45 of the core 44 that is distal to the bore 22.

Each outer core component 44b,44c is provided with a through aperture 68 which extends through the lozenge shaped projection 52b, 52c. The through aperture 68 is dimensioned to receive a threaded fastener 70 therethrough. The threaded fasteners 70 are receivable in the blind threaded holes 56 of the housing 16 to retain the outer core components 44b,44c in association with the base plate 36, and further to retain the torque motor 12 as a whole to the throttle valve 14.

On the opposing side of each outer core component 44b, 44c to the lozenge shaped projection 52b, 52c there is provided a substantially flat surface 72 which, when viewed in plan, has the shape on an annular sector.

Assembly of the stator 42 requires the rectangular body portion 60 of the central core component 44a to be fitted through the correspondingly shaped centre aperture 50 of the coil carrier 48. The central core component 44a and outer core components 44b, 44c can then be fitted to the base plate 36 by locating the core component projections 52a,52b,52c in their respective apertures 54a,54b,54c of the base plate 36. It will be appreciated that in the assembled state of the stator 42 the longer sides of the coil 46 are shrouded by the core components 44a,44b,44c and base plate 36 whereas the shorter sides of the coil 46 are exposed. It will also be appreciated that in the assembled state of the stator 42 the annular sector shaped surfaces 64,66,72 of the core components 44a,44b,44c are aligned around the bearing seat 62 to define a flat annular surface.

In an alternative embodiment of the present invention the outer core components 44b,44c may be formed integrally with the base plate 36, for example by a metal casing procedure. In such an embodiment the core 44 is thus of a two piece construction which comprises a central core component 44a and an outer core and base plate component.

The rotor 40 includes a rotor disc 74, a shaft 76 and an annular magnet 78. The rotor disc 74 is fixed to an end 80 of the shaft 76. The annular magnet 78 is fixed to the side of the rotor disc 74 which, in use, faces the stator 42. The rotor disc 74 is provided with a further annular magnet 82 on the opposite side to that which the previously described annular magnet 78 is fixed. The further annular magnet 82 aligned concentrically with the centreline axis of the shaft 76 and is utilised to determine the rotational position of the shaft 76. In use, the shaft 76 extends through both the torque motor 12 and throttle valve 14. Thus a single, common shaft 76 is utilised to mount the flapper element 24 within the bore 22 of the housing 16 and define the axis upon which it is rotatable, and to transmit drive from the torque motor 12 to the flapper element 24. In the embodiment shown the shaft 76 is a single piece shaft. The shaft 76 is mounted for rotation within the assembly 10 by only two bearings comprising a first bearing 84 and a second bearing 86. The first bearing 84 is located between the rotor disc 74 and the central core component 44a. The second bearing 86 is located within the substantially circular projection 32 of the housing 16 which extends from the opposite side of the housing to the mounting face 26. It will be appreciated that the shaft 76 is supported only at opposing ends by the bearings 84,86 and is not supported by an intermediate bearing located at or near the mid-point of the shaft 76. The first bearing 84 is a single row angular contact bearing which is able to resist both radial and axial loads. In use, radial loading of the shaft 76 is experienced as a result of forces acting upon the flapper element 24, while axial loading results from the magnet forces attracting the rotor 40 to the stator 42. The first bearing 84 is located within the bearing seat 62 of the central core component 44a and further acts to maintain desired spacing between the annular magnet 78 of the rotor disc 74 and the core 44.

The second bearing 86 is a needle roller bearing which is required only to resist radial loading of the shaft 76 is experienced as a result of forces acting upon the flapper element 24.

As can be readily seen from the cross-sectional view, the end 88 of the shaft 76 which is distal to the rotor disc 74 extends beyond the projection 32 of the housing 16. This feature enables a return spring assembly, generally designated 90, to be located at the distal end 88 of the shaft 76 and remote from the torque motor 12. The return spring assembly 90 includes a spring carrier 92 and a helical spring 94. The spring carrier 92 is fixed to the distal end 88 of the shaft 76 and the helical spring 94 is received within an annular recess 96 of the housing projection 32. The distal end 88 of the shaft 76 and return spring assembly 90 are enclosed by an end cap 98 which is fitted to the housing projection 92. It will further be noted that the distal end 88 of the shaft 76 projects beyond the spring carrier 92 and into the space enclosed by the end cap 98. The clearance space between the distal end 88 of the shaft 76 and the end cap 98 can accommodate thermal expansion of the shaft 76, in use.

The flapper element 24 is fixed for rotation with the shaft 76 by any suitable means. The flapper element 24 may, for example, be fixed to the shaft 76 in the manner described in WO 2014/085326. The shaft 76 is further provided with a pair of shaft seals 100, 102. A first shaft seal 100 is located within the through aperture 28 of the housing mounting face 26 and is retained between the housing 16 and the projection 52a of the central core component 44a. The second shaft seal 102 is retained in the projection 32 of the housing 16 between the second bearing 86 and the housing 16.

The cover 38 of the torque motor 12 is further provided with an end cap 104. Within the end cap 104 there is provided a PCB 106 to which power connectors 108 of the coil 46 are located. The PCB 106 is in turn connected to a connector block 110 of the cover 38 and to which a power and control lead 112 is connected. Sealing gaskets 114, 116 are provided between the end cap 104 and cover 38, and cover 38 and base plate 36 respectively.