Patent GB-850359-A (GB)
Title: Improvements in or relating to safety clutches
IPC: F16D43/204
Filed: 1958-06-25
Abstract: 850,359. Overload release clutches. STIE. BER, O. June 25, 1958 [June 25, 1957], No. 20423/58. Class 80 (2). An overload release clutch has driving and driven dog members radially movable relative to each other on overload, the dog members on both the driving and driven clutch members being radially movable by centrifugal force against spring bias when the clutch rotates, camming surfaces tending to move the dog members on the driven clutch member radially inwards. In one form, a driving clutch member 1 carries axially projecting clutch dogs 8 on masses 4 biased radially inwards by springs 5 but moved outwards against the spring bias, as shown in the upper half of the Figure, by centrifugal force. The clutch dogs 8 coact with rollers 6 on similar masses 4 radially movable by centrifugal force against the bias of springs 5 in a driven clutch member 2. When the clutch is at rest, both sets of masses 4 are at their radially innermost positions, and the dogs engage the rollers 6. As the speed of rotation of the clutch increases, the sets of masses 4 move radially outwards together until they reach the outermost position shown in the upper half of the Figure. On overload, the clutch dogs 8 cam the rollers 6 and the masses 4 in the driven clutch member 2 radially inwards. The driven clutch member 2 comes to rest, with its masses 4 in their radially innermost positions, while the driving clutch member 1 continues to rotate with its masses 4 and clutch dogs 8 in their radially outermost positions. On removing the overload and stopping rotation of the driving clutch member 1, the masses 4 therein are moved radially inwards by their springs 5 to reengage the clutch. The clutch dogs 8 are formed with camming surfaces so shaped that they coact with the rollers 6 to transmit a higher torque when starting the clutch before disengagement due to overloading takes place, than when rotating at speed. The cam surfaces may comprise two relatively inclined surfaces, Fig. 2 (not shown), inclined to the direction of rotation, or may comprise a smoothly curved surface, Fig. 4 (also not shown). In the form shown in Fig. 1, the maximum torque transmitted when the clutch is rotating before disengagement is caused by overload varies with the speed of rotation. In a modification, the masses 4, Fig. 3, on the driven clutch member 2 are biased radially inwards by their springs 5 and a second mass 4a engages the masses 4 through a spring. The arrangement is such that the overload required to cause clutch disengagement remains substantially constant, independent of the speed of rotation of the clutch. 850,398. Gearing for stopping and starting machinery. FICHTEL & SACHS A.G. Dec. 6, 1957 [March 16, 1957], No. 38080/57. Class 80 (2). A clutch in a motor-car is automatically disengaged during a ratio shift by operation of the gear lever, the speed of re-engagement following establishment of a ratio shift being increased by depressing the accelerator pedal providing that the car is not slowing down, in which case a movable weight, such as a pendulum or the like, overrides the rapid clutch engagement produced by accelerator pedal depression and ensures a cushioned take-up of drive. In one form, movement of the ratio shift lever energizes a solenoid 9, Fig. 4, to attract an armature 10 thereby opening a valve 11 to connect a pipe 4 leading to a clutch disengaging servomotor and a pipe 13 communicating with the inlet manifold of the internal combustion engine driving the car. On completion of a ratio shift, the solenoid 9 is de-energized, and the valve 11 is returned to its closed position by a spring 12. The pipe 4 and the servomotor are then connected to atmospheric pressure through a hole 15 and a pressure-regulating valve 16, which is closed by its spring 17 when sufficient air has entered the pipe 4, &c. to raise the pressure in the clutch servomotor by a predetermined amount. Air continues to seep slowly through a bleed hole 18 to give a gradual completion of clutch engagement. If, following establishment of a ratio, the accelerator pedal of the car is depressed, the inlet manifold pressure rises and acts through a pipe 8, 21 upon a diaphragm 19 which is therebiased rightwards of the Figure by a spring 22 to engage a stem 20 with the pressure relief valve 16, which is accordingly again opened to give rapid completion of clutch engagement. If, however, the motor car is slowing down, a ball 23 rolls along in a hole 24 to close the passage 21, so that the diaphragm 19 and stem 20 do not move and clutch engagement is accordingly completed only by the slow seeping of air through the bleed hole 18. Jerking of the motor car when the accelerator pedal is depressed following a ratio downshift is thereby overcome. In a modification, the main clutch is disengaged electromagnetically by supplying current through resistors 26 ... 29, Fig. 6, from a sliding contact on a rod 30 fast with a piston 31 in a cylinder 32 connected via a pipe 34 to the inlet manifold. A spring 35 biases the piston 31 to the right-hand position whereby only a small resistance is introduced into the clutch circuit, so that the clutch engages rapidly. If the accelerator pedal is not depressed, the piston 31 is moved to the left by the depression in the inlet manifold and greater resistance is introduced into the clutch control circuit to give cushioned engagement. If the accelerator pedal is now suddenly depressed, the piston 31 moves rapidly to the right to cut out the resistors 26 ... 29 and rapid clutch engagement is effected. If, however, the car is slowing down, then a ball 36 rolls along to close a hole 33 in the connection to the inlet manifold so that depression of the accelerator pedal, with increasing pressure in the inlet manifold, will not affect the position of the piston 31 and the rod 30, and rapid clutch engagement is prevented. In an. other form, energization of a solenoid 37, Fig. 7, during a ratio shift connects a pipe 38 to which compressed air is supplied, to a pipe 39 leading to the clutch servomotor. Following a ratio shift, the solenoid 37 is de-energized and the valve 40 returns to the position shown. Compressed air in the pipe 39 &c. then escapes through an adjustable bleed hole 44 to the atmosphere for gradual clutch re-engagement. If the accelerator pedal is depressed, a rod 45 is withdrawn from a passage 46 through which air escapes for quick re-engagement of the clutch. If the car is slowing down, a pendulum 47 pivoting at 48 closes the hole 46 and rapid reengagement of the clutch is not effected with accelerator pedal depression. As a further modification, the pendulum may act directly on a control member, for example a diaphragm.