WO1994021543A1

WO1994021543A1 - Controllable rotatable elements

Info

Publication number: WO1994021543A1
Application number: PCT/GB1994/000459
Authority: WO
Inventors: Richard Joseph Taberner; Christopher Clive Gort Gregory
Original assignee: Conveyor Roller Controls Limited
Priority date: 1993-03-13
Filing date: 1994-03-09
Publication date: 1994-09-29
Also published as: GB9305203D0; GB2275977A; ZA941712B; AU6286094A

Abstract

A controllable rotatable element, such as a conveyor roller, comprising a hollow member capable of rotation relative to a controlling member and fluid pressure-responsive friction means for resisting relative rotation between them so as to transmit driving or braking torque, has sealing means rendering an interior part of the hollow member substantially fluid-tight, the sealing means including a pressure-responsive friction element connected in fluid-tight relation non-rotatably to one member and making sealing contact with the other member, the pressure-responsive friction element being arranged to make frictional contact with a surface of the other member when fluid under pressure is admitted to the interior of the hollow member.

Description

CONTROLLABLEROTATABLE ELEMENTS

TECHNICAL FIELD

In British Patent Application No. 9305203.3 there was described a braked rotatable element, such as a conveyor roller, comprising a hollow member rotatable with respect to a stationary member, sealing means rendering the interior of the hollow member substantially fluid-tight, a fluid-conveying passage from the exterior to the interior of the hollow member for admitting fluid under pressure to the interior of the hollow member and braking means connected non-rotatably to one of the said members and arranged to make frictional contact with the other member or a part connected therewith when fluid under pressure is admitted to the interior of the hollow member. It was explained that the hollow member could be a sleeve carried on two spaced bearings coaxial with the sleeve, with fluid-pressure responsive braking means connected to one part of one of the bearings and arr anged to make frictional contact with the complementary part of the bearing and/or with a member connected to it when fluid under pressure is admitted to the interior of the sleeve so as to apply a braking force thereto.

It is now appreciated that similar arrangements could provide for the control of relative rotation between two elements which are both rotatable, in the manner of a clutch. For example, if the stationary member mentioned above was replaced by a driving member, rotatable about the same axis as the hollow member, then by admitting fluid under pressure to the interior of the hollow member it would be possible to transmit drive from the driving member to the hollow member and to vary the drive by varying the pressure of the fluid.

Both braked and driven rotatable elements have many applications in mechanisms. For example, in roller conveyors used to assist the movement of goods, which comprise a succession ot parallel rollers mounted in a framework so that goods placed on the rollers can readily be moved along the framework, it may be desirable to have one or more braked rollers and/or one or more driven rollers to regulate the speed at which the goods travel. Commonly such conveyors are inclined so that goods will travel along them under the effect ol gravity. Braked rollers may be required in such a case to prevent goods reaching excessive speeds. If conveyors are inclined upwardly then driven rollers may be required to cause goods to travel along them. BACKGROUND ART

British Patent Specification No. 532.689 refers to a brake, more especially for aircraft, ol the kind in which an expartsible annular envelope composed ot flexible material is interposed between a pair of non-rotatable annular brake discs which, when the brake is off, are arranged to slide axially upon a fixed support, said envelope being adapted to expand when fed with pressure fliud and force said discs axially apart into frictional engagement with a corresponding pair ol mutually facing surfaces rotating with the wheel requiring to be braked. In the Specification a brake of that kind is described which is incorporatd in a flanged tyre nm. wherein one of the rotating surfaces engageable by a brake disc is formed upon a member which carries one of the flanges and is readily removable from another member which provides the other rotating surface and carries the other nm flange.

DISCLOSURE OF THE INVENTION

According to this invention a controllable rotatable element comprises a hollow member capable of rotation relative to a controlling member, sealing means rendering an interior part of the hollow member substantially fluid-tight, the sealing means including pressure-responsive friction means connected in fluid-tight relation non-rotatably to one of the said members and making sealing contact with the other of the said members, a fluid-conveying passage for admitting fluid under pressure to the said interior part , the pressure-responsive friction means being arranged to make frictional contact with a surface ol the other member when fluid under pressure is admined to the interior of the hollow member so as to resist relative rotation between the two members.

The pressure-responsive friction means is preferably an annular element coaxial with respect to the said relative rotation with a marginal region making sealing contact with the said other member. Conveniently it may be moulded in rubber or flexible plastics material and it may have on one surface a coating of frictional material to make frictional contact with the said surface of the other member. The rubber or plastics matenal may be reinforced or stiffened by a fabric or metal insert. Preferably the annular pressure-responsive frict ion element is connected in fluid-tight relation non-rotatably to an inner part of one of the said members and us outer margin makes sealing contact with the other member. However, its outer margin could be connected to one member and its inner margin could make sealing contact with the other. In a preferred construction an annular pressure-responsive friction element surrounds and is connected in sealing relation to the controlling member and its outer marginal region makes sealing contact with an internal surface of the hollow member, conveniently a cylindrical surface of the hollow member. Inwardly of the said marginal region is an annular band of frictional material to make frictiona l contact with the said surface of the other member, conveniently an annular surface perpendicular to the said cylindrical surface. The controlling member may be stationary or it may be rotatable about the same axis as the hollow member. If it is stationary then the frictional contact between the friction element and the said surface of the other member will apply a braking restraint to the hollow member which may be varied by varying the pressure of the fluid. If it is rotatable then the contact could transmit driving torque from the controlling member to the hollow member or vice versa. The sealing means may comprise two confronting annular pressure-responsive friction elements defining the said interior part between them The hollow member may be a roller of a roller conveyor or a part of such a roller or it may be connected to such roller. The controlling member may be a shaft of such a roller, when the fluid-conveying passage may be formed in the shaft. Alternatively the controlling member may be a sleeve-like member rotatably mounted or intended to be so mounted on a shaft with the hollow member mounted on the sleeve-like member. A part of the sleeve-like member may carry a sprocket, pulley or other driving means. The hollow member may be an end member to be assembled with parts of a conventional conveyor roller in place of one conventional end member.

The fluid may be air.

Further according to the invention a controllable rotatable element comprises a sleeve earned on two spaced end members coaxial with the sleeve, each end member comprising an inner part and an outer part rotatable relative to the inner part about a common axis and connected to the sleeve, sealing means for rendering the interior of the sleeve between the end members substantially fluid-tight , a fluid-conveying passage for admitting fluid under pressure to the interior of the sleeve and fluid-pressure responsive friction means connected non-rotatably to one of the said parts of one of the end members and arranged to make frictional contact with the complementary part of the said one end member and/or with a member connected to the complementry part when fluid under pressure is admitted to the interior of the sleeve.

With this arrangement the sleeve is normally rotatable freely about its axis relative to the inner parts of the end members but the relative rotation can be controlled or prevented by admitting fluid under pressure through the fluid-conveying passage to its interior. The controlling torque will be proportional to the pressure of the fluid and may thus readily be controlled and released when desired by releasing the fluid pressure. Still further according to the invention a controllable rotatable element comprises a sleeve, having a drivable part and a bearing part , rotatably mounted on a shaft and an outer member rotatably mounted on the bearing part of the sleeve, the outer member having a hollow interior part including an annular surface substantially perpendicular to the shaft, a fluid-tight seal mounted on the shaft and contacting the outer member in sealing relation to close and seal the hollow interior and an annular pressure-responsive friction element mounted on and sealed to the sleeve in the hollow interior with its periphery in sealing contact with the outer member, the friction element having an annular friction surface facing the said annular surface and arranged to contact that surface when fluid under pressure is admitted to the hollow interior. The drivable part may be a sprocket or a pulley or other means for driving or resisting rotation of the sleeve. The outer member may be an end of or for a conveyor roller, the other end of which may conveniently be mounted on a bearing carried by the shaft.

The fluid-conveying passage may be connected externally to a vessel containing fluid in which the pressure of the fluid is controlled as desired. It may include valve means tor regulating the flow of fluid . There may be a second passage for allowing fluid to escape from the interior of the sleeve. If the fluid is air the second passage may be vented to the atmosphere, with a control valve to allow the air to escape when desired.

By including one or more rollers embodying the invention in a roller conveyor it is possible to regulate or control the movement of goods along the conveyor. If the roller or rollers is/are arranged 10 be braked or driven then goods can be caused to move along the conveyor without relying on gravity or external forces and can be slowed or stopped when desired. The invenuon includes such a conveyor.

DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example by the accompanying drawings, in which :

Figure 1 is an axial cross-section of a braked conveyor roller, and

Figure 2 is an axial cross section of a conveyor roller which may be driven or braked.

The roller shown in Figure 1 comprises a hollow tube or sleeve 1 mounted on a shaft 2 by two spaced end members 3. Each end member comprises an inner part 4 and an outer part 5 rotatable relative to the inner part 4 about the axis of the shaft 2, anti-friction balls 6 being mounted between the inner and outer parts of each end member and being held in position by a cage assembly 7 in conventional manner. The ends of the sleeve 1 are a close fit on the outer parts 5 and are swaged on to them, O-ring seals 8 being fitted between the sleeve 1 and each outer part to ensure fluid-tight joints. Each outer part 5 has a cylindrical flange 9 extending inwardly from its outer edge, for a purpose which will be described.

The shaft 2 is of hexagonal cross-section and the inner parts 4 of the end members 3 have complementary hexagonal bores so as to fit closely on the shaft 2 and be non-rotatable in relation to it. A pressure-responsive frictional element, in the forn of a diaphragm 10 of rubber or like resilient and flexible material, is bonded to the inside surface of each inner part 4 and has a hexagonal central aperture designed to fit the shaft 2 in sealing relation. Each diaphragm 10 extends radially outwardly so as to lie close to the inner surface of the respective outer part 5 and the radially inner surface of the flange 9. Its surface which confronts those surfaces has a coating 11 of wear-resistant frictional material which normally makes light rubbing contact with those surfaces when the sleeve 1 is rotated relative to the shaft 2. Thus the interior of the sleeve 1 is rendered substantially fluid-tight.

A passage from the exterior to the interior of the sleeve 1 is provided by an axial bore 12 extending from one end of the shaft 2 to a position within the sleeve 1 where it jo ins a radial bore 13. Air or other fluid under pressure may be admitted to the interior of the sleeve 1 through this passage. It will be appreciated that any increase ot pressure m the interior of the sleeve will force the diaphragms 10 axially outwardly so as to increase the contact between the confronting faces ot the wear-resistant frictional coatings 11 and the outer parts 5 of the end members 3 and their flanges 9. This will cause frictional resistance to rotation of the sleeve 1 relative to the shaft, braking the sleeve 1 if it is rotating. Further increase of the pressure will increase the frictional resistance or braking force.

To provide braking in a roller conveyor the shall 2 i s mounted between supporting frame members 14, parallel to the shafts (not shown) carrying conventional rollers. If the outer end of the axial bore 12 is connected to a source of compressed air through a control valve then air under pressure can be admitted to the interior of the sleeve when desired to effect braking of the sleeve 1 and thus of any object travelling over it along the conveyor. If the control valve also includes a vent passage which can be opened selectively, the air may be released when desired to reduce the pressure and so reduce the braking effect . Alternatively a separate vent passage may be provided, with an independent control valve. If a non-return valve, for example a tyre valve, is fitted to the outer end of the bore 12 then the pressure inside the sleeve 1 may be increased to a certain value so as to provide a constant braking effect whether the sleeve is rotating or not.

Instead of the stationary shaft 2, the tube or sleeve 1 and end members 3 could be mounted on a drivable shaft carried in appropriate bearings in a conveyor assembly. Then drive could be transmitted from the shaft to the tube or sleeve by supplying compressed air to the interior.

The conveyor roller 15 shown in Figure 2 comprises a tube 16 swaged to end members 17 and 18. The end member 17 is of a conventional type, mounted on a bearing 19 on a shaft 20. The other end member 18 is mounted on a bearing 21 on a driving or braking sleeve 22 which is itself mounted on bearings 23 on the shaft 20. Thus the roller 15 and the sleeve 22 are each independently rotatable and thus relatively rotatable with respect to one another about the axis of the shaft 20. The sleeve 22 comprises a drivable part 24 having sprockets 25 for engagement by roller chains (not shown) and a bearing part 26 providing a seating for the bearing 21 which carries the end member 18. The end member 18 has a hollow interior part formed by a recess 27 in its side which is innermost in the roller 15. The open end of the recess 27 is closed and sealed by a sealing ring 28 which is a substantially air-tight fit on the shaft 20. An annular pressure-responsive friction element 29 is mounted on and sealed to the end of the bearing part 26. Its outer diameter is such that its edge makes sealing contact with the cylindrical surface of the recess 27 so as to close and seal the hollow interior part of the end member 18. The friction element 29 has an annular friction coating 30 which confronts and normally makes light rubbing contact with the annular surface of the recess 27. A gap 31 between the end of the bearing part 26 and the sealing ring 28 provides a passage for compressed air to enter the hollow interior part . The shaft 20 has an axial bore 32 from its end carrying the sleeve 22, the open end of which is threaded to receive a pipe fitting for the supply of compressed air. A radial bore 33 communicates with the bore 32 and is positioned to be within the bearing part 26 which has an inner diameter greater than the diameter of the relevant part of the shaft 20 so that compressed air can flow through the bores 32 and 33 into the cylindrical space between the shaft and the part 26 and thus through the gap 31 into the hollow interior part A seal 34 mounted in the sleeve 22 inwardly of the inner bearing 23 prevents the outward escape of compressed air.

In a conveyor assembly, the shaft 20, which is stationary , is mounted between the side members 35, 36 which conventionally carry the bearings lor the other rollers of the convevor (not shown). Of course, a conveyor may include more than one roller 15 distributed amongst the conventional rollers as necessary.

When compressed air is supplied to the bore 32 it forces the annular friction coating 30 of the friction element 29 against the annular surface of the recess so as to resist relative rotation between the roller 15 and the sleeve 22. If the sleeve 22 is driven then drive is transmitted from the sleeve to the roller. On the other hand, if the sleeve is braked or held stationary then rotation of the roller will be resisted. Thus the roller 15 can be either driven or braked as desired by dnving or braking the sleeve 22.

In a modification , instead of having a conventional end member 17 at one end, a roller could have two end members like the member 18, each rotatable on a sleeve like the sleeve 22. One of the sleeves could be driven continu ously and by supplying compressed air to that sleeve drive could be transmitted to the roller. The other sleeve could be fixed so that by supplying compressed air to that sleeve the roller could be braked. Thus rotation or braking of the roller could be controlled as desired by means of two air valves.

A sub-assembly comprising a sleeve similar to 22 with its bearings and an end member similar to 18 could be marketed for use as a replacement for an end member and bearing of a conventional conveyor roller.

Whilst in the embodiments described the friction elements 10 and 29 operate mainly axially, it will be understood that radially-operating friction elements could be employed without departing from the invention .

Claims

1. A controllable rotatable element comprising a hollow member (18) capable of rotation relative to a controlling member (22) and fluid pressure-responsive friction means (29) for resisting relative rotation between them, characterized by sealing means (28, 29) rendering an interior part of the hollow member (18) substantially fluid-tight, the said sealing means including a pressure-responsive friction element (29) connected in fluid-tight relation non-rotatably to one of the said members (22) and making sealing contact with the other of the said members (18), a fluid-conveying passage (31, 32, 33) for admitting fluid under pressure to the said interior part, the pressure-responsive friction element (29) being arranged to make frictional contact with a surface (30) of the other member when fluid under pressure is admitted to the interior of the hollow member so as to resist relative rotation between the two members.

2. A controllable rotatable element as claimed in Claim 1 charactrized in that the pressure-responsive friction means (29) is an annular element coaxial with respect to the said relative rotation with a marginal region making sealing contact with the said other member.

3. A controllable rotatable element as claimed in Claim 2 characterized in that the annular pressureresponsive friction element (29) surrounds and is connected in sealing relation to a part of the controlling member (22) and its outer marginal region makes sealing contact with an internal surface (27) of the hollow member (18).

4. A controllable rotatable element as claimed in Claim 3 characterized in that the annular pressure- responsive friction element (29) has, inwardly of the said marginal region, an annular band of frictional material to make frictional contact with an internal surface (30) of the hollow member.

5. A controllable rotatable element as claimed in Claim 1 characterized in that the sealing means comprises two confronting annular pressure-responsive friction elements defining the said interior part between them.

6. A controllable rotatable element as claimed in any of Claims 1 to 5 characterized in that the hollow member is a roller for a roller conveyor or a part of such a roller.

7 A roller conveyor including a roller as claimed in Claim 6.

8. A controllable rotatable element comprising a tube ( 1 ) earned on two spaced end members coaxial with the tube, each end member comprising an inner part 4) and an outer part (5) rotatable relative to the inner part (4) about a common axis and connected to the tube (1) , characterized by sealing means (10) for rendering the interior of the tube (1) between the end members substantially fluid-tight, a fluid-conveying passage (12, 13) for admitting fluid under pressure to the interior of the tube (1) and fluid-pressure responsive friction means (10) connected non-rotatably to one of the said inner and outer parts of one of the end members and arranged to be deformed by fluid pressure in the interior to make frictional contact with the complementary part of the said one end member and/or with a member connected to the complementry part, whereby relative rotation between the tube (1 ) and the inner parts (4) may be resisted.

9. A controllable rotatable element comprising a sleeve (22) havin g a drivable part and a bearing part (26) , rotatably mounted on a shaft (20) and an outer member ( 18) rotatably mounted on the bearing part (26) of the sleeve (22), characterized in that the outer member (18) has a hollow interior part including an annular surface (30) substantially perpendicular to the shaft (20), a fluid-tight seal (29) mounted on the shaft and contacting the outer member in sealing relation to close and seal the hollow interior and an annular pressure-responsive friction means(29) mounted on and sealed to the sleeve (26) in the hollow interior with its periphery in sealing contact with the outer member (18), the friction means (29) having an annular friction surface facing the said annular surface (30) and arranged to contact that surface when fluid under pressure it admitted to the hollow interior part.

10. A controllable rotatable element as claimed in Claim 8 or Claim 9 characterized in that the hollow member is a roller for a roller conveyor or a part of such a roller.

11. A roller conveyor including a roller as claimed in Claim 10.