GB2383609A

GB2383609A - Air motor

Info

Publication number: GB2383609A
Application number: GB0125041A
Authority: GB
Inventors: George Robert Silk
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-18
Filing date: 2001-10-18
Publication date: 2003-07-02
Anticipated expiration: 2021-10-18
Also published as: GB0125041D0; GB2383609B

Abstract

The invention is an air motor designed to address two problems, icing-up due to throttling the incoming air and difficulty dismantling for repair and overhaul due to an integral gearbox. To reduce icing-up, a motor 10 with a chamber formed by a cylinder 66 which is fixed to the casing and has a radial air inlet port arrangement 68 and a radial air exhaust port arrangement 70, 72, by providing a rotatable valve sleeve 80 with radial apertures for adjustably throttling the exhaust port; and secondly, in a motor with a casing having an air entry port 94 and air exit ports 106 and 112 in one of its ends, by providing a plate valve 116, 118 rotatable in the casing for adjustably throttling the exit port 106. In a motor with a speed-reduction gearbox 12, the motor and the gearbox are self contained and connected together by a quick release clamp 24.

Description

"Air Motor." This invention relates to an air motor comprising a sliding-vaned rotor rotateable by compressed air in an eccentric cylindrical chamber within a casing.

Hitherto, such air motors have suffered from several disadvantages. Due to speed control having been effected by throttling the air entry port, they have been prone to icing-up due to internal expansion of the incoming air lowering the temperature of the outgoing air. They have incorporated an integral speed-reduction gearbox, and they have been difficult to take apart for repair and overhaul.

The objects of the present invention are to overcome or ameliorate the aforesaid disadvantages.

According to one aspect of the invention, in an air motor comprising a sliding-vaned rotor rotateable by compressed air in an eccentric cylindrical chamber within a casing, said chamber being formed by a cylinder fixed to the casing and provided with radial air inlet and exhaust port arrangements, means are provided for adjustably throttling the exhaust port arrangement.

The means for adjustably throttling the exhaust port arrangement preferably comprise a sleeve co-axially and closely surrounding the cylinder, said sleeve being rotateable relative to the cylinder and also being provided with radial air inlet and exhaust port arrangements, the exhaust port arrangement in the sleeve being capable of

adjustably throttling the exhaust port arrangement in the cylinder.

Preferably, the exhaust port arrangement in the sleeve comprises at least one radial aperture which is large enough to uncover the whole exhaust port arrangement in the cylinder.

Preferably, also, the sleeve is rotateable by means of a spindle journalled radially in and projecting from the casing and having at its inner end a toothed pinion engaging gear teeth formed on an end face of the sleeve.

Preferably, the exhaust port arrangement in the cylinder comprises a zone containing a multiplicity of radial holes.

Preferably, also, the casing includes end plates and is fastened together by a plurality of axially-extending set-screws which are removeable from one of its ends.

According to another aspect of the invention, in an air motor comprising a sliding-vaned rotor rotateable by compressed air in an eccentric cylindrical chamber within a casing, said casing having air entry and exit ports in one of its ends, means are provided for adjustably throttling the exit port.

The means for adjustably throttling the exit port preferably comprise a plate valve rotateable in the casing.

Preferably, the plate valve comprises a central disc from which there projects radially a sector adapted to throttle the exit port adjustably, the plate valve being

rotateable by means of a spindle journalled in and projecting axially from the casing and having at its inner end a toothed pinion engaging gear teeth formed on the periphery of the disc.

Preferably, also, an additional unthrottled exit port is also provided in said one end of the casing.

The unthrottled exit port may be provided with a silencing element.

According to a further aspect of the invention, in an air motor comprising a sliding-vaned rotor rotateable by compressed air in an eccentric cylindrical chamber within a casing, said motor being provided with a speed-reduction gearbox, the motor and the gearbox are each self-contained and are adapted to be releaseably connected together.

The motor and the gearbox are preferably adapted to be connected together by a quick release clamp.

Preferably, the clamp has a plurality of segments each having a circumferential groove in its inner periphery, said segments being releaseably secured around two abutting circumferential flanges on the motor and the gearbox respectively with the flanges engaging in the grooves.

Preferably, also, both side faces of the grooves taper towards their bases, and the non-abutting faces of the flanges have a corresponding taper towards their tips.

Preferably, the clamp has three segments one of which is hinged at its ends to the adjacent ends of the other two segments and the other ends of said other two segments being adapted to be releaseably clamped together.

The invention will now be described, by way of example, with reference to the accompanying drawings, of which :- Figure 1 is an exploded perspective view of a preferred embodiment of an air motor and its gearbox; Figure 2 is a similar view of a modified embodiment thereof, identical components not being given reference numerals ; Figure 3 is an elevation of the gearbox end of both embodiments; Figure 4 is a section on the line 4-4 in Figure 3 of the modified embodiment; Figure 5 is a perspective view of both embodiments showing the motor and its gearbox disconnected from each other, with an exploded view of a clamp which releaseably connects them together; and Figure 6 is a section on the line 6-6 in Figure 4 showing variation in exhaust timing in both embodiments.

Referring now to Figures 1,3, 5 and 6 of the drawings, a self-contained air motor indicated generally at

10 is provided with a self-contained speed-reduction gearbox indicated generally at 12. The gearbox 12 employs any suitable arrangement of epicyclic gearing to drive an output shaft 14, and has a case 16 with an integral flange 18. The motor 10 has a casing indicated generally at 20 with a similar integral flange 22, and the motor 10 and gearbox 12 are adapted to be connected together by a quick release clamp indicated generally at 24. The clamp 24 has three segments 26 one of which is connected at its ends by hinge pins 28 to the adjacent ends of the two other segments, the other ends of said two other segments being adapted to be releaseably clamped together by a tangential bolt 30 and a nut 32. Each of the segments 26 has a circumferential groove 34 in its inner periphery, said segments being releaseably secured around the flanges 18 and 22 when said flanges are brought into abutting relationship and the air motor's output shaft 36 makes driving engagement with the epicyclic gearing. The flanges 18 and 22 engage in the grooves 34, and in order to exert a high clamping force both side faces of said grooves taper towards their bases while the non-abutting faces of said flanges have a corresponding taper towards their tips. The casing 20 includes end plates 38 and 40, the flange 22 being formed integrally on the end plate 38, and said casing is fastened together by three axially-extending setscrews 42. The clamp 24 enables the motor 10 and gearbox 12 to be quickly separated either for the substitution of a

basically similar gearbox providing a different speed reduction ratio or for the purpose of repair and overhaul.

The set-screws 42 enable the motor 10 to be quickly disassembled for servicing.

The motor 10 comprises a rotor 50 with five circumferentially-spaced axially-extending radial slots 52 in which vanes 54 are slideably confined. The rotor 50 is journalled at one end in a bearing 56 housed in the end plate 38 and at the other end in a bearing 58 housed in a member 60 forming part of the casing 20, and is rotateable between end plates 62 by compressed air in an eccentric cylindrical chamber within a main body 64 of the casing 20. Said chamber is formed by a cylinder 66 fixed to the casing 20 and provided with a radial air inlet port arrangement comprising a zone 68 containing a multiplicity of radial holes, and a radial air exhaust port arrangement comprising zones 70 and 72 each containing a multiplicity of radial holes. The zones 68,70 and 72 are spaced apart circumferentially so as to be respectively aligned radially with an inlet manifold 74, a first exhaust manifold 76 and a second exhaust manifold 78 formed by axial channels in the eccentric inner periphery of the body 64 as shown in Figure 6. Means for adjustably throttling the exhaust port arrangement comprise a sleeve 80 co-axially and closely fitting between the outer periphery of the cylinder 66 and the inner periphery of the body 64, said sleeve being rotateable relative to said cylinder and also being

provided with radial air inlet and exhaust port arrangements. The inlet port arrangement comprises a pair of axially-spaced radial apertures 82 which are together large enough to cover more than the whole of the zone 68, and the exhaust port arrangement comprises a pair of axially-spaced radial apertures 84 which are together large enough to cover the zone 70 and a pair of axially-spaced radial apertures 86 which are together large enough to cover the zone 72. The circumferential spacing of the apertures 82,84 and 86 corresponds to that of the zones 68,70 and 72. The sleeve 80 constitutes a sleeve valve and is rotateable by means of a spindle 88 journalled radially in and projecting from the body 64 and having at its inner end a toothed pinion 90 which engages gear teeth formed on an end face 92 of the sleeve 80. Compressed air is supplied to the inlet manifold 74 through an air entry port 94 in the end plate 40, an axially aligned port 96 in a seal plate 98 disposed between the end plate 40 and the member 60, and an axially aligned port 100 in said member.

Similarly, air is exhausted from the first exhaust manifold 76 through axially aligned ports 102 and 104 formed respectively in the member 60 and the seal plate 98 and through an aligned air exit port 106 formed in the end plate 40, and from the second exhaust manifold 78 through axially aligned ports 108 and 110 formed respectively in the member 60 and the seal plate 98 and through an aligned additional air exit port 112 formed in the end plate 40.

The size and disposition of the apertures 82 is such that rotation of the sleeve 80 does not cause throttling of the zone 68.

Means for adjustably throttling the exit port 106 comprise a plate valve rotateable within a recess 114 in the inner face of the end plate 40. Said valve comprises a central disc 116 from which there projects radially a sector 118. The recess 114 has the same shape as the plate valve, but its sector portion occupies twice the angle subtended by the sector 118 and encompasses the exit port 106 at one of its circumferential ends. The plate valve is rotateable to throttle the exit port 106 adjustably by means of a spindle 120 journalled in and projecting axially from the end plate 40 and having at its inner end a toothed pinion 122 which engages gear teeth 124 formed on the periphery of the disc 116. The additional air exit port 112 is not throttled.

Throttling of the exhaust port arrangement in the cylinder 66 significantly reduces the risk of icing-up because it permits the air supplied to the air entry port 94 of the motor 10 not to be throttled in contradistinction to the normal practice hitherto, with a consequent reduction in internal expansion and cooling. Severe throttling of the exhaust port arrangement will somewhat reduce the speed of the motor but this is far preferable to icing-up which can stop the motor. The principal mode of

speed control is by throttling the exit port 106, and this also significantly reduces the risk of icing-up.

In a modification shown in Figures 2 and 4 of the drawings, the plate valve 116,118 and its associated recess 114 and spindle 120 are omitted, and silencing elements 126 are provided in the exit ports 106 and 112.

Said silencing elements are conventional cartridges of porous sintered brass. The motor/gearbox combination is otherwise unchanged.

In another modification not illustrated, one such silencing element is provided in the unthrottled exit port 112 of the preferred embodiment.

In a further modification not illustrated, the sleeve 80 and its associated spindle 88 are omitted, whilst retaining the plate valve 116, 118 for throttling the exit port 106. In this event the cylinder 66 is made a close fit in the inner periphery of the body 64.

In yet another modification not illustrated, air is arranged to exit laterally from radial ports in the outer periphery of a sleeve fixed around the casing 20 instead of axially from the end plate 40, and silencing elements of porous sintered brass are provided in said ports.

Claims

Claims :-

1. An air motor comprising a sliding-vaned rotor rotateable by compressed air in an eccentric cylindrical chamber within a casing, said chamber being formed by a cylinder fixed to the casing and provided with radial air inlet and exhaust port arrangements, wherein means are provided for adjustably throttling the exhaust port arrangement.

2. An air motor according to claim 1, wherein the means for adjustably throttling the exhaust port arrangement in the cylinder comprise a sleeve co-axially and closely surrounding the cylinder, said sleeve being rotateable relative to the cylinder and also being provided with radial air inlet and exhaust port arrangements, the exhaust port arrangement in the sleeve being capable of adjustably throttling the exhaust port arrangement in the cylinder.

3. An air motor according to claim 2, wherein the exhaust port arrangement in the sleeve comprises at least one radial aperture which is large enough to uncover the whole exhaust port arrangement in the cylinder.

4. An air motor according to claim 2 or claim 3, wherein the sleeve is rotateable by means of a spindle journalled radially in and projecting from the casing and having at its inner end a toothed pinion engaging gear teeth formed on an end face of the sleeve.

5. An air motor according to any one of the preceding claims, wherein the exhaust port arrangement in the cylinder comprises a multiplicity of radial holes.

6. An air motor according to any one of the preceding claims, wherein the casing includes end plates and is fastened together by a plurality of axially-extending setscrews which are removeable from one of its ends.

7. An air motor comprising a sliding-vaned rotor rotateable by compressed air in an eccentric cylindrical chamber within a casing, said casing having air entry and exit ports at one of its ends, wherein means are provided for adjustably throttling the exit port.

8. An air motor according to claim 7, wherein the means for adjustably throttling the exit port comprise a plate valve rotateable in the casing.

9. An air motor according to claim 8, wherein the plate valve comprises a central disc from which there projects radially a sector adapted to throttle the exit port adjustably, the plate valve being rotateable by means of a spindle journalled in and projecting axially from the casing and having at its inner end a toothed pinion engaging gear teeth formed on the periphery of the disc.

10. An air motor according to any one of claims 7 to 9, wherein an additional unthrottled exit port is also provided in said one end of the casing.

11. An air motor according to claim 10, wherein the unthrottled exit port is provided with a silencing element.

12. An air motor according to any one of claims 7 to 11, wherein the casing includes end plates and is fastened together by a plurality of axially-extending set-screws which are removeable from one of its ends.

13. An air motor comprising a sliding-vaned rotor rotateable by compressed air in an eccentric cylindrical chamber within a casing, said motor being provided with a speed-reduction gearbox, wherein the motor and the gearbox are each self-contained and are adapted to be releaseably connected together.

14. An air motor according to claim 13, wherein the motor and the gearbox are adapted to be connected together by a quick-release clamp.

15. An air motor according to claim 14, wherein the clamp has a plurality of segments each having a circumferential groove in its inner periphery, said segments being releaseably secured around two abutting circumferential flanges on the motor and the gearbox respectively with the flanges engaging in the grooves.

16. An air motor according to claim 15, wherein both side faces of the grooves taper towards their bases, and the non-abutting faces of the flanges have a corresponding taper towards their tips.

17. An air motor according to any one of claims 14 to 16, wherein the clamp has three segments one of which is hinged at its ends to the adjacent ends of the two other segments

and the other ends of said two other segments being adapted to be releaseably clamped together.

18. An air motor according to any one of claims 13 to 17, wherein the casing includes end plates and is fastened together by a plurality of axially-extending set-screws which are removeable from one of its ends.

19. An air motor constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated by, the accompanying drawings.