Abstract
A rotary piston and cylinder device (1) comprising a rotor (2), a stator (4) and a rotatable shutter (3), the rotor comprising a piston (5) which extends from the rotor into a working chamber, the rotor and the stator together defining a working chamber, the shutter arranged to extend through the working chamber and forming a partition therein, and the shutter comprising a slot which allows passage of the piston therethrough, a bearing (20) which mounts the rotor relative to the stator, the rotor comprising a formation (12; 30) which extends substantially axially away from the chamber, and the formation being radially outward of the bearing and extending around the axis of rotation, and the formation comprising a surface which at least in part defines a space between the rotor and the stator, and at least part of that space and/or the formation overlaps in an axial direction with the bearing.
Claims
1. A rotary piston and cylinder device comprising a rotor, a stator and a rotatable shutter, the rotor including a piston which extends from the rotor into a working chamber, the rotor and the stator together defining the working chamber, the rotatable shutter arranged to extend through the working chamber and forming a partition therein, and the rotatable shutter including a slot which allows passage of the piston therethrough, a bearing which mounts the rotor relative to the stator, the rotor including a formation which extends substantially axially away from the working chamber, and the formation being radially outward of the bearing and extending around the axis of rotation, and the formation including a surface which at least in part defines a space between the rotor and the stator, and at least part of that space and/or the formation overlaps in an axial direction with the bearing.
2. The rotary piston and cylinder device as claimed in claim 1 in which the formation comprises an annular or cylindrical formation.
3. The rotary piston and cylinder device as claimed in claim 2 in which the annular or cylindrical formation is provided rearwardly of the working chamber.
4. The rotary piston and cylinder device as claimed in claim 2 in which the annular or cylindrical formation comprises a land.
5. The rotary piston and cylinder device as claimed in claim 4 in which the land provides a locating surface for a seal, or a surface which serves to act with the seal.
6. The rotary piston and cylinder device as claimed in claim 2 in which the annular or cylindrical formation comprises a flange or a lip.
7. The rotary piston and cylinder device as claimed in 6 in which the annular or cylindrical formation comprises a portion which, in use, is operative to serve as a lubricant flinger or lubricant distributor.
8. The rotary piston and cylinder device as claimed in claim 1 which comprises a lubricant collection chamber, which is defined at least in part by an annular groove or channel, extending about the axis of rotation.
9. The rotary piston and cylinder device as claimed in claim 1 which comprises a fluid seal arranged in communication with the space.
10. The rotary piston and cylinder device as claimed in claim 9 in which the fluid seal is located outwardly with respect to the axis of rotation and spaced from the bearing in a direction from the axis.
11. The rotary piston and cylinder device as claimed in claim 9 in which the fluid seal is substantially in its entirety, offset from the bearing in a radial sense relative to the axis of rotation of the rotor.
12. The rotary piston and cylinder device as claimed in claim 9 in which the bearing is arranged in communication with the space.
13. The rotary piston and cylinder device as claimed in claim 9 in which the fluid seal and the bearing are located rearwardly of, or behind, or to a side of, when viewed in axial cross-section, from the working chamber.
14. The rotary piston and cylinder device as claimed in claim 9 in which the fluid seal and the bearing are located, at least in part, at different axial positions or regions relative to the extent of the axis of rotation of the rotor.
15. The rotary piston and cylinder device as claimed in claim 9 wherein the fluid seal comprises multiple fluid seals.
16. The rotary piston and cylinder device as claimed in claim 9 in which the fluid seal is arranged to substantially maintain an oil-air barrier.
17. The rotary piston and cylinder device as claimed in claim 9 in which the space comprises a labyrinth seal.
18. The rotary piston and cylinder device as claimed in claim 9 in which the bearing and the fluid seal are located between opposing surfaces of the rotor and the stator.
19. The rotary piston and cylinder device as claimed in claim 1 in which the space is arranged to contain a lubricant.
20. The rotary piston and cylinder device as claimed in claim 1 in which the space is defined at least in part by an annular groove.
Description
BRIEF DESCRIPTION OF DRAWINGS
(1) Various embodiments of the invention will now be described, by way of example only, with reference to the following drawings in which:
(2) FIG. 1 is a front simplified perspective view of a rotary piston and cylinder device
(3) FIG. 2, is a rear simplified perspective view of a rotary piston and cylinder device,
(4) FIGS. 3 to 15 each show partial longitudinal cross-sections of various embodiments of a rotary piston and cylinder device, which are based on the type of rotary piston and cylinder device disclosed in FIGS. 1 and 2, and
(5) FIG. 16 shows a cross-section of a further embodiment,
(6) FIG. 17 shows a further embodiment of a different rotary piston and cylinder device, and
(7) FIG. 18 shows yet a further embodiment of a different rotary piston and cylinder device.
DETAILED DESCRIPTION
(8) Reference is made to FIGS. 1 and 2 which shows a rotary piston and cylinder device 1 which comprises a rotor 2, a stator 4, and a shutter disc 3. The stator, although not shown in FIGS. 1 and 2 for ease of representation, but shown in part in the further Figures, comprises a formation, such as a housing or casing, which is maintained relative to the rotor, and surface of the stator facing the surface 2a of the rotor, together define a cylinder space or working chamber, shown generally as 100. The stator 4 may further comprise a second portion which is located to the other side of the rotor, and so the stator portions together enclose the rotor therebetween. (It will be noted that part of the stator which encloses the working chamber is omitted from the drawings for reasons of simplification.) Integral with the rotor and extending from the surface 2a there is provided a piston 5. A slot 3a provided in the shutter disc 3 is sized and shaped to allow passage of the blade therethrough. Rotation of the shutter disc 3 is geared to the rotor by way of a transmission assembly (not shown) which comprises gearing which is arranged to ensure that the timing of the rotor remains in synchrony with the shutter disc.
(9) In use of the device, a circumferential surface 30 of the shutter disc faces the surface 2a of the rotor so as to provide a seal therebetween, and so enable the shutter disc to functionally serve as a partition within the annular cylinder space.
(10) The geometry of the surface 2a of the rotor is governed by the curved circumferential surface of the rotating shutter disc. Since the disc (preferably) penetrates/intersects only one side of the (annular) chamber, the axes of the disc and rotor will not generally intersect.
(11) The rotor and the stator are configured to provide the annular cylinder space with an inlet port and an outlet port (not referenced) for the particular fluid.
(12) The rotor 2 further comprises a rearwardly extending portion 2b, which is located rearwardly of the cylinder space. The rearward portion 2b may be thought of as a shaft, which is arranged to transmit torque to or from the rotor, in use.
(13) As will be described below, a seal separates the bearings from the rotor on the side of the chamber. This may serve to separate the bearing lubricant from the working fluid (for example air) or the bearing lubricant from the rotor itself or the working fluid (possibly corrosive gas) from the bearings, and the embodiments below disclose an advantageous way of arranging the seal and the bearing.
(14) In the specific description of the embodiments which follow, the same reference numerals are used where the same or substantially the same feature, or equivalent feature (from either a functional and/or structural perspective) is referred to.
(15) With reference now to FIG. 3, there is shown a partial cross-sectional view of a rotary piston and cylinder device, which comprises a fluid or lubricant seal 10 and a bearing 20, which rotationally mounts the rotor 2 to the stator 4, and which can be said to occupy an interface region between the rotor 2 and the stator 4. As can be seen, the seal 10 is located at a radially outermost position as compared to the bearing 20, which is located radially inwardly, both radial positions determined relative to an axis of rotation A-A of the rotor 2. This general characteristic of offsetting, spacing or clearance in a radial sense between the bearing 20 and the seal 10 is common to the embodiments which follow, and all serve to illustrate some of the ways in which this principle can beneficially be realised.
(16) The device further comprises an annular wall 30 which is located rearwardly of the cylinder space 100. The annular wall 30 provides a land or surface on which the seal 10 is located, or a surface with which or on which the seal acts, and is also radially spaced from the bearing. It will be appreciated that the seal 10 is of substantially annular or circular form. Whilst it is primarily intended that the annular wall 30 is formed integrally with the rotor at the time of manufacture, in some embodiments, it may be a separate component which is affixed to the (major portion) of the rotor during a post-manufacture assembly process (and in relation to which one of the embodiments which follows relates).
(17) Further in relation to the embodiment shown in FIG. 3 the annular wall 30 can be seen to extend from a rearward portion 12 of the rotor.
(18) The convoluted and tortuous configuration of a space 40, which is defined between the rotor and the stator, is such as to add additional sealing or fluid control between the bearing 20 and the fluid seal 10. Part of the space 40 is defined by the formation 30. The space advantageously serves to minimise the fluid which moves or flows towards the seal 10. It will be appreciated that the principal purpose of the seal 10 is to prevent the ingress or passage of fluid into the space 50, which may be filled with air or other working fluid, and which lies at an opposite side of the seal 10. Both the seal 10 and the bearing 20 are in communication with the intermediate space 40.
(19) As shown in broken line in FIG. 3, there is at least partial axial overlap between the seal 10 and the bearing 20, and indeed axial overlap between a portion of the space 40 and the bearing 20.
(20) FIG. 3a shows a variant embodiment to that of FIG. 3, in which an additional fluid restriction feature 10a is included in the space 40. The restriction may comprise a fluid seal or an oil shield.
(21) Reference is now made to FIG. 4 shorter (in an axial direction) seal 110 is provided. The seal 110 could be re-positioned all the way axially away from the working chamber (left in FIG. 4) so that it does not overlap the bearing 20 axially but that it is substantially over-hung (with respect to the bearing) and giving a path to the space that over-laps the bearing.
(22) Reference is now made to FIGS. 5 and 6 in which what may be termed an intermediate region comprises the space 40 as well as a fluid collection sub chamber 45 which is in part defined by a curved or shaped groove as seen in the cross sectional views of FIGS. 5 and 6, formed in the stator. It is also to be noted that in FIG. 5 the fluid seal 110 is now set axially forwardly (relative to the above described embodiment and towards the working chamber 100) so that the radially outer surface or land of the annular wall 130 is clear of the fluid seal 110. The bearing 20 and the seal 110 are located with respect to different positions along the axis A-A. The land 130, the path 40 and space 45, (at least in part) axially overlap the bearing. Those axially overlapping features could be considered as parts of the overall sealing system or sealing arrangement.
(23) In the variant but related embodiment shown in FIG. 6 this includes an annular wall 230 which is provided with a lip or flange feature 35. The feature 35 serves as an oil flinger, slinger or thrower in order to direct/distribute oil into the curved or shaped groove recess 45. The recess, or sub-chamber 45, may be considered as part of the intermediate space 40. It will be appreciated that the lip of flange feature 35 may, during the assembly of the rotary piston and cylinder device, be a separate component which is attached to the rotor during assembly.
(24) FIGS. 6a to 6d show further embodiments which include a labyrinth seal is included. In FIG. 6a, the labyrinth seal 110a is formed as being integral with the stator 4. In FIG. 6b, a labyrinth seal 110b is formed as being integral with the rotor 2. In FIG. 6c, a labyrinth seal 110c is provided as a separate component which is secured to the rotor 2, and in FIG. 6d, a labyrinth seal 110d is a separate component which is secured to the stator 4. Note that in all of FIGS. 6a to 6d, the labyrinth seal is axially offset from the bearing 20. However, part of the annular wall/land 230, and part of the intermediate space, nevertheless overhangs the bearing.
(25) Turning to FIG. 7 in this embodiment two fluid seals 10 and 15 are shown. The seal 10 may be a lubricant seal, such as an oil seal, and is spaced apart by an intermediate space 40a from a working fluid or air seal 15. This serves to further enhance the desired separation of lubricant from working fluid or air along the interface region of the device. The fluid seal 10 is located on the land i.e. the radially outer surface of the annular wall 30.
(26) In the embodiment shown in FIG. 8 the annular seal 230 is provided with a flange or lip, serving as an oil flinger in use at its rearmost end.
(27) FIG. 9 shows an embodiment which being somewhat conceptually similar to the embodiment described above comprises two fluid seals, 10 and 15, which may be an oil seal and an air seal respectively, with an intermediate space 40a separating the two seals.
(28) With reference to FIG. 10 there is again shown an embodiment in which two fluid seals, 10 and 15 are employed and being spaced apart by an intermediate space 40a. In this instance the space 40a is arranged to form a tortuous path thus assisting in inhibiting or preventing the ingress of oil towards the air seal 15.
(29) Turning to the embodiment shown in FIG. 11 this may be viewed as a hybrid of some of the previously described embodiments which as can be seen includes two fluid seals 10 and 15 arranged in series and separated by an intermediate space 40a. The intermediate space 40a and the intermediate space 40 both arranged to have a tortuous path and relative to each and associated with each of the oil seal 10 and the air seal 15 there is provided a fluid collection sub-chamber 45. It will be seen from FIG. 11 that the extent of this sub-chamber is positioned further radially outwardly than the corresponding radial position of its associated seal. This again assists with minimising any ingress or transgression of fluid towards or from the space 50.
(30) Reference is made to FIGS. 12 and 13 in which in both cases the intermediate space 40 is substantially radially disposed as is the oil seal 110. However the air space 50 of each differs in that the air space shown in FIG. 12 comprises a convoluted or tortuous arrangement of the space which comprises part 50a which is adjacent to the opposite side of the oil seal 110. Whereas in FIG. 13 the air space 50 does not include such an axially extending configuration and rather is disposed radially and adjacent to the oil seal 110. As can be seen, both the intermediate space and the seal partially axially overlap the bearing.
(31) FIG. 14 shows yet a further embodiment in which the intermediate space allows for smoother curvature (in cross-section) on the bounding rotor surface, which may be described as a curved groove, which reduces the stress concentrations therein, increasing fatigue life of the part. This embodiment also includes an annular/cylindrical formation 4c of the rotor which is located radially outwardly of the bearing 20.
(32) In FIG. 15 an embodiment is shown in which the annular wall feature is provided by a component 530. This component 530 is a separate component to the rotor at the time of manufacture and during an assembly process is attached to the portion 12 of the rotor. This may facilitate the manufacture of the rotor. The component 530 includes features and formation which allows location of it to the rotor and can be secured in place by a suitable fastening, so as to be able to cooperate and engage with a portion of the part 12, which may be a formed shoulder, of the rotor.
(33) FIG. 16 shows an embodiment which illustrates an example of the presence of a drain or outlet 150 to the oil collection chamber 45. Vents, such as air vents, may be also incorporated in a similar fashion in any of the previous embodiments, such as between the air and oil seals.
(34) Advantageously, in respect of the above described embodiments, by arranging the seal and the bearing elements spaced apart from one another in a radial sense, allows for the bearing to be positioned closer to (the side of) the working chamber 100, in an axial direction. This is achieved by the presence of the annular formation of the rotor, which conveniently provides a land or surface for the seal, as well assisting in defining the space between rotor and stator, which defines a circuitous path between bearing and seal. In prior art devices, the bearing and seal are typically axially spaced along the shaft, in an axial direction, substantially at the same radial position from the axis of rotation. In the above embodiments, it has been realised that there can be substantial benefit from placing at least one or more of the bearings between the rotor and stator as close axially to the working chamber as possible. This novel arrangement advantageously reduces bearing loads.
(35) Furthermore, the embodiments described above are novel arrangements in which the bearing and seal are spaced, at least in part, in a radial direction and in which in some cases part of the sealing system over-hangs either the bearing or a further seal. This can facilitate or avoid machining and manufacturing challenges (in terms of machine tool access/assembly etc) over the traditional arrangement, in addition to the advantage of reducing bearing loads.
(36) Related to this, and perhaps viewed from a different perspective, is that the annular wall feature allows an increase in the available sealing area, without this resulting in having to locate the bearing further away from the chamber, and the disadvantages which would result from that.
(37) Reference is made to FIG. 17, which shows a different type of rotary piston and cylinder device 600, which incorporates a further type of bearing and sealing arrangement as described above. The device 600 comprises a rotor, comprising a rotor surface 602a, a stator 4a and 4b, a rotatable shutter 603, a piston (not illustrated) which extends from the rotor surface, the rotor surface and the stator together defining an annular working chamber 650, and the piston, in use, arranged to rotate, through the annular chamber. A slot or aperture 603a is provided in the shutter 603. A characteristic of this type of device is that the rotor surface 602a is directed generally outwardly around the axis of rotor of the rotor 602. Moreover, the rotor surface could be termed as being Moreover, the rotor surface could be termed as being orientated at an incline with respect to a plane substantially perpendicular to the axis of rotation of the rotor, which plane extends through a mid-region of the rotor surface, and the rotor surface is directed generally away from the axis of rotation of the rotation of the rotor, or with respect to the axis of rotation of the rotor. The device 600 comprises two axially spaced bearing arrangements 620 to allow rotation of the rotor as supported by the stator. One of the bearing arrangements 620 is provided with an associated seal 610. As can be seen in FIG. 17, the seal 610 is radially spaced outward from the bearing 620. The rotor 602 comprises an annular/cylindrical wall/formation 630, which extends axially. The wall 630 provides a land or surface on which the seal 610 can be mounted or can act in conjunction with. The wall 630 could be said to extend rearwardly (of the rotor). The device 600 further comprises a port 608, incorporated into the stator.
(38) Reference is made to FIG. 18 which shows yet a further type of rotary piston and cylinder device 700, which comprises a rotor 702, comprising a rotor surface 702a, a stator 4a and 4b, a rotatable shutter 703, a piston (not illustrated) which extends from the rotor surface, the rotor surface and the stator together defining an annular working chamber 750, and the piston, in use, arranged to rotate, through the annular chamber. A slot or aperture 703a is provided in the shutter 703. A characteristic of this type of device is that the rotor surface 702a is directed generally outwardly around the axis of rotor of the rotor 702. Moreover, the rotor surface could be termed as being orientated at orthogonally with respect to a plane substantially perpendicular to the axis of rotation of the rotor, which plane extends through a mid-region of the rotor surface, and the rotor surface is directed generally away from the axis of rotation of the rotation of the rotor, or with respect to the axis of rotation of the rotor. The rotor surface 702a may be described as substantially diablo shape, in which the concave profile of the rotor surface is rotated around the axis of rotation of the rotor. The device 700 comprises two axially spaced bearing arrangements 720 to allow rotation of the rotor as supported by the stator. One of the bearing arrangements 720 is provided with an associated seal 710. As can be seen in FIG. 17, the seal 710 is radially spaced outward from the bearing 720. The rotor 702 comprises an annular/cylindrical wall/formation 730, which extends axially. The wall 730 provides a land or surface on which the seal 710 can be mounted or can act in conjunction with. The wall 730 could be said to extend rearwardly (of the rotor).
