GB1602850A - Friction clutches - Google Patents

Description

(54) IMPROVEMENTS IN OR RELATING TO FRICTION CLUTCHES (71) We, JOSEPH RHODES LIMITED, formerly of Belle Vue, Wakefield, West Yorkshire, WF1 5EQ, a British company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the methodsby which it is to be performed, to be particularly described in and by the following statement: - This invention relates to clutches and particularly to clutches for driving equipment where rapid starting and stopping of moving parts are required, such as power presscs, and heavy forging machines.

Pneumatic clutches for such equipment are known in which a piston and cylinder arangement is provided on the end of a crank shaft or driving shaft and air pressure is used to move the piston in a direction from the cylinder towards the crank shaft or driving shaft so that pressure is applied to the friction plates to couple the clutch members together. In this way rotational movement may be transmitted from a flywheel to the crank shaft or the driving shaft. Such clutches suffer from the disadvantage that, the air pressure being limited, the piston and cylinder components of the clutch have to be large in order to obtain the required operating force and therefor the inertia of the system is relatively high. The result is that there is a certain amount of slipping betwen the clutch members and therefore the time taken to stop and start the crank shaft or the driving shaft is relatively high.

Hydraulic clutches have been proposed but in general these have been mere substitutes for pneumatic clutches and the inertia of the moving parts has still been very high.

According to the present invention there is provided a hydraulically actuated for mounting beyond the end of a shaft clutch including first and second annular, coaxially arranged clutch members, in which the first clutch member is for attachment to a shaft and the second clutch member is for attachment to drive means, a cylinder mounted for sliding movement relative to a static piston, the piston and cylinder being arranged beyond the end of said shaft, and coaxially with respect to the clutch members and said shaft and clutch coupling means, attached to said cylinder, for releasably coupling together the first and second clutch members.

Accordingly in a hydraulically actuated clutch in accordance with the present invention the normal arrangment of a static cylinder and moving piston. have been reversed and this makes it possible to produce a clutch which is hydraulically operated and which has a small diameter and consequently a low inertia compared with previously known hydraulic clutches.

The above-mentioned annular clutch members still surround the shaft, such as the crank shaft or main shaft, which is to be driven. The piston and cylinder will be coaxial with this shaft and are preferably located close to one end thereof.

Due to the high pressure of the oil serving as the hydraulic fluid the diameter of the piston can be kept small compared with that of a corresponding pneumatic clutch of the same capacity.

Preferably the clutch coupling means include a plurality of pins or the like extending between said first and second clutch members and parallel to the iongitudinal axis thereof, the pins being rigidly attached to the cylinder for movement therewith.

Preferably the clutch includes brake means which are arranged to be engaged simultaneously with the release of the clutch members. More preferably the brake means include a stationary member and means attached to the cylinder for movement therewith to releasably engage the stationary member with the shaft or member attached thereto. This arrangement of the clutch may be such that rnovement of the cylinder in a direction away from the end of the shaft causes the clutch members to be coupled together and at the same time releases the brake means, and movement of the cylinder in the opposite director releases the clutch members and simultaneously engages the brake means.

The above-mentioned pins or the like can be arranged for rotation of the first clutch member so that they transmit rotational movement of the flywheel to the shaft as well as transferring the force of the movement of the cylinder to a gripping force between the clutch members.

The pins can be arranged to extend through the cylinder to the outer face thereof and adjustment means can be provided at the ends of the pins to compensate for wear at the friction plates. Furthermore the use of a plurality of pins arranged in a circle about the shaft enables a robust connection to be established between the clutch members when they are coupled together.

An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawing which is a longitudinal section through a hydraulically actuated clutch in accordance with the present invention.

Referring to the drawing a hydraulically actuated clutch in accordance with the present invention is for transmitting drive between a flywheel 2, as shown in the upper half of the drawing, or a spurwheel 38, shown as an alternative in the lower half of the drawing. Flywheel 2 or spurwheel 38 is mounted for rotation on a sleeve 45 by means of bearings 43, to which oil may be supplied by hydraulic nipple 1, connector 39 and tubing 41. Sleeve 45 surrounds a portion of shaft 51 which is to be driven. Shaft 51 may be a crank shaft or main shaft. Reference will be made hereinafter to flywheel 2 although it will be appreciated that such references could be replaced by reference to spurwheel 38.

Shaft 51 includes an end portion 53 of slightly reduced diameter to which is keyed, by means of separate wedge ring locking assemblies 29, inner clutch body 31 and outer clutch body 28, which together form the first clutch member.

Secured within bores in flywheel 2 and extending therefrom are a plurality of flywheel pins 30. These pins 30 are equally spaced apart about the end portion 53 of shaft 51 and the inner and outer clutch bodies 31 and 28. There may for instance be six or twelve such pins. Located on the pins 30 are two annular plates 10 which are arranged coaxially with respect to shaft 51. There is a rigid combination between plates 10 and flywheel 2 via pins 30 and the combination of plates 10 and pins 30 comprise the second clutch member.

Means for releasably coupling together the clutch members including a plurality of clutch body pins 13. These pins are peripherally spaced apart about the clutch body and there may for instance be six or twelve such pins. Each pin extends between an annular flange portion 55 of inner clutch body 31, through a reaction plate 57, which is integral with outer clutch body 28, to a cylinder 25 which will be described below. Each pin 13 has a largest diameter portion 59 located within flange portion 55 and inner clutch body 31 and an intermediate diameter portion 61 which extends between flange portion 55 close to the outer edge of reaction plate 57.

Extending outwardly from portion 61 there is a smallest diameter portion 63, the end of which is provided with a screw thread.

Between flange portion 55 and reaction plate 57 and mounted for movement on pins 13 is an annular centre plate 9. Also mounted on pins 13 is pressure plate 8 but this plate is rigidly attached to pins 13 by means of set screws 7. As shown in the drawing, friction linings 65 are provided on the facing surface of pressure plate 8 and centre plate 9 and also on the facing surface centre plate 9 and reaction plate 57. The combination of pins 13, pressure plate 8 and centre plate 9 together with the friction linings 65 comprise the clutch coupling means.

The clutch is also provided with a piston 27 and a cylinder 25, these members being arranged coaxially with and at the end of shaft 51. The cylinder 25 forms the end cover of the clutch and is located on the end of the clutch by means of the pins 13 with which there is a screw thread connection. Nuts and lock nuts 15 provided on the outer end of each pin 13 enables the clutch to be adjusted to compensate for wear of the friction linings.

Piston 27 has a substantially circular piston face 71 although there is a central recess 73 which faces a corresponding recess 75 in the inner wall of cylinder 25 there being disposed on a spring 18 between the recesses. Spring 18 biases piston 27 away from cylinder 25 and, during operation of the clutch, keeps the piston in a fixed position at the end of shaft 51. Extending from the outer wall of recess 75 across the hub portion 77 of cylinder 25 is a bore 80. Fitted in the outer end of this bore is a connector which is provided with a rotating gland 19 through which hydraulic fluid may be passed via bore 80 to the space between piston face 71 and the inner circular wall of cylinder 23.

The inner cylindrical wall of the cylinder is provided with an annular recess in which is fitted an O-ring seal 16. This is the only oil seal which is required in this hydraulic clutch since the piston 27 is substantially a solid cylindrical body slidable within the cylinder 25.

Piston 27 is provided with an annular flange 79 which extends radially outwardly into the space between cylinder 25 and reaction p]ate 57 of outer clutch body 28.

Passing from flange 79 are a plurality of spring studs 24 which are rigidly attached to outer clutch body 28 and equally spaced apart about flange 79. These spring studs extend from flange portion 79 through corresponding bores in the cylinder 25 to spring nuts 20 which are spaced from washers 23 on the outer wall of cylinder 25 by means of springs 22. Thus the cylinder 25 is slidable on the spring studs 24 and the springs 22 are arranged to urge cylinder 25 in a direction towards shaft 51.

The outer facing surface of reaction plate 57 of outer clutch body 28 and the inner facing surface of cylinder 25 are each provided with annular friction Jinings 12. Located between the friction linings 12 is an annular portion of a brake plate 11. Brake plate 11 is rigidly attached to the frame of the machine, of which the clutch forms a part, by means of brake anchor pins 4. In operation flywheel 2 rotates at constant speed and, in order to engage the clutch, hydraulic fluid is fed to the space between piston face 71 and cylinder 25. The cylinder is urged in a direction away from shaft 51, thereby moving therewith both the pins 13 and pressure plate 8. Accordingly plates 10 are squeezed between friction linings 65 and drive is transmitted from the flywheel through the clutch members to shaft 51.

On release of hydraulic pressure, cylinder 25 is urged in a direction towards shaft 51 by means of springs 22 and the movement of the attached pins 13 in this direction releases the pressure of plates 10. Simultaneously the brake plate 11 is squeezed between friction linings 12 provided on cylinder 25 and reaction plate 57, so that the rotation of the first clutch member and shaft 51 is immediately stopped. The cycle can then be repeated and in fact as many as thirty or forty stops and starts per minute can be accomplished even when the clutch forms part of very large presses or other machines.

In the above described embodiment the piston 27 is held to the end of shaft 51 by means of spring 18. Alternatively or in addition the piston may be secured to outer clutch body 28 by means of screws passing through flange portion 79 or there can be a rigid attachment between spring studs 24 and flange 79 of piston 27, rather than the non-rigid location in the above described embodiment.

The above described arrangement for applying pressure between the cylinder 25 and plates 10 by means of headed pins 13 in tension is particularly convenient for providing gripping pressure from an outward cylinder movement without accordingly increasing the overall central diameter. Since the pins 13 pass through the clutch body they serve the additional purpose of transmitting the rotary motion.

The inertia of the clutch is kept to a minimum by having a central piston and cylinder arrangement with a circular piston face. The use of pins 30 for transmitting torque enables a very robust arrangement to be achieved which will withstand the shock of repeated engagements of the clutch. The use of plates or gear teeth, as used in known clutches, would probably result in the break up of these items since the torque exerted by a typical clutch in accordance with the present invention is about 15,0001bus. For the same clutch the torque exerted by the brake is about 2,500 lbs. The hydraulic pressure may be about 1,000 lbs./sq. in. and this compares with an air pressure of about 60 lbs./sq. in.

which is used with pneumatic clutches.

The use of friction linings and large plates such as those described above means that a hydraulic clutch in accordance with the present invention has good heat dissipation characteristics. Further the heat dissipation is assisted since the clutch plates are rotating all the time.

WHAT WE CLAIM IS: - 1. A hydraulically actuated clutch for mounting beyond the end of the shaft including first and second annular, coaxially arranged clutch members, in which the first clutch member is for attachment to the shaft and the second clutch member is for attachment to drive means, a cylinder mounted for sliding movement relative to a static piston, the piston and cylinder being arranged beyond the end of the shaft and coaxially with respect to the clutch members and said shaft, and clutch coupling means, attached to said cylinder, for releasably coupling together the first and second clutch members.

2. A hydraulic clutch according to claim 1 wherein the clutch coupling means include a plurality of pins or the like extending between said first and second clutch members and parallel to the longitudinal axis thereof, the pins being rigidly attached to the cylinder for movement therewith.

3. A hydraulic clutch according to claim 1 or claim 2 wherein the clutch includes brake means which are arranged to be

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. reaction p]ate 57 of outer clutch body 28. Passing from flange 79 are a plurality of spring studs 24 which are rigidly attached to outer clutch body 28 and equally spaced apart about flange 79. These spring studs extend from flange portion 79 through corresponding bores in the cylinder 25 to spring nuts 20 which are spaced from washers 23 on the outer wall of cylinder 25 by means of springs 22. Thus the cylinder 25 is slidable on the spring studs 24 and the springs 22 are arranged to urge cylinder 25 in a direction towards shaft 51. The outer facing surface of reaction plate 57 of outer clutch body 28 and the inner facing surface of cylinder 25 are each provided with annular friction Jinings 12. Located between the friction linings 12 is an annular portion of a brake plate 11. Brake plate 11 is rigidly attached to the frame of the machine, of which the clutch forms a part, by means of brake anchor pins 4. In operation flywheel 2 rotates at constant speed and, in order to engage the clutch, hydraulic fluid is fed to the space between piston face 71 and cylinder 25. The cylinder is urged in a direction away from shaft 51, thereby moving therewith both the pins 13 and pressure plate 8. Accordingly plates 10 are squeezed between friction linings 65 and drive is transmitted from the flywheel through the clutch members to shaft 51. On release of hydraulic pressure, cylinder 25 is urged in a direction towards shaft 51 by means of springs 22 and the movement of the attached pins 13 in this direction releases the pressure of plates 10. Simultaneously the brake plate 11 is squeezed between friction linings 12 provided on cylinder 25 and reaction plate 57, so that the rotation of the first clutch member and shaft 51 is immediately stopped. The cycle can then be repeated and in fact as many as thirty or forty stops and starts per minute can be accomplished even when the clutch forms part of very large presses or other machines. In the above described embodiment the piston 27 is held to the end of shaft 51 by means of spring 18. Alternatively or in addition the piston may be secured to outer clutch body 28 by means of screws passing through flange portion 79 or there can be a rigid attachment between spring studs 24 and flange 79 of piston 27, rather than the non-rigid location in the above described embodiment. The above described arrangement for applying pressure between the cylinder 25 and plates 10 by means of headed pins 13 in tension is particularly convenient for providing gripping pressure from an outward cylinder movement without accordingly increasing the overall central diameter. Since the pins 13 pass through the clutch body they serve the additional purpose of transmitting the rotary motion. The inertia of the clutch is kept to a minimum by having a central piston and cylinder arrangement with a circular piston face. The use of pins 30 for transmitting torque enables a very robust arrangement to be achieved which will withstand the shock of repeated engagements of the clutch. The use of plates or gear teeth, as used in known clutches, would probably result in the break up of these items since the torque exerted by a typical clutch in accordance with the present invention is about 15,0001bus. For the same clutch the torque exerted by the brake is about 2,500 lbs. The hydraulic pressure may be about 1,000 lbs./sq. in. and this compares with an air pressure of about 60 lbs./sq. in. which is used with pneumatic clutches. The use of friction linings and large plates such as those described above means that a hydraulic clutch in accordance with the present invention has good heat dissipation characteristics. Further the heat dissipation is assisted since the clutch plates are rotating all the time. WHAT WE CLAIM IS: -

1. A hydraulically actuated clutch for mounting beyond the end of the shaft including first and second annular, coaxially arranged clutch members, in which the first clutch member is for attachment to the shaft and the second clutch member is for attachment to drive means, a cylinder mounted for sliding movement relative to a static piston, the piston and cylinder being arranged beyond the end of the shaft and coaxially with respect to the clutch members and said shaft, and clutch coupling means, attached to said cylinder, for releasably coupling together the first and second clutch members.

2. A hydraulic clutch according to claim 1 wherein the clutch coupling means include a plurality of pins or the like extending between said first and second clutch members and parallel to the longitudinal axis thereof, the pins being rigidly attached to the cylinder for movement therewith.

3. A hydraulic clutch according to claim 1 or claim 2 wherein the clutch includes brake means which are arranged to be

engaged simultaneously with the release of the clutch members.

4. A hydraulic clutch according to claim 3 wherein the brake means include a stationary member and means attached to the cylinder for movement therewith to releasably engage the stationary member with the shaft or member attached thereto.

5. A hydraulically actuated clutch substantially as herein described.

6. A hydraulically actuated clutch substantially as described herein with ^erence to the accompanying drawing.