Patent GB-1449543-A (GB)
Title: Automatic clutch control system
IPC: F16D48/06
Filed: 1974-01-08
Abstract: 1449543 Clutch control FORD MOTOR CO Ltd 8 Jan 1974 00735/74 Heading F2C A motor vehicle clutch control system comprises a comparator 38 which compares a desired clutch position signal 39 produced by means responsive to throttle pedal position or engine speed with an actual clutch position signal 20 and produces a clutch control signal to effect movement of the clutch towards the desired position. Electronic circuit.-Potentiometers 21, 26 produce signals proportional to the actual clutch engagement and throttle pedal position. The former signal is applied directly to the comparator 38 whilst the latter signal is added at 47 to a signal 45 porportional to the clutch position when just disengaged and applied through a limiter 49, which limits the maximum rate of increase of the desired clutch engagement signal, to the comparator 38. The comparator 38 produces a signal which controls the markspace ratio of a pulse generator 32. The markspace ratio is increased when the desired clutch signal exceeds the actual clutch signal and is reduced when the actual clutch signal exceeds the desired clutch signal. The output of the pulse generator 32 is applied through AND gates 35, 36 and OR gate 37 to the input 29 of a clutch actuating circuit. The gate 35 is enabled when the throttle pedal is depressed beyond a predetermined position by a signal 52 from a detector 50. The AND gate 36 is enabled by a signal from an inverter 69 when a clutch disengage signal is not present on a line 67. When a signal is present on the line 29 for a predetermined time a gate 40 is opened and triggers a gate 42 to apply a fully engaged clutch signal from the potentiometer 21 to a line 43. A subtracting circuit 44 subtracts a signal proportional to the clutch disengaging movement from the fully engaged clutch signal to provide the clutch disengaged signal 45. The clutch disengaged signal 45 thus varies with clutch wear. Voltages 54, 55 respectively proportional to clutch output speed and engine speed are applied to a comparator 56 which, when the voltages are equal, applies an output 57 through an OR gate 73 to an AND gate 51. The engine speed responsive voltage and a road speed responsive voltage are applied to detectors 58, 60 which, when the engine speed exceeds 400 r.p.m. and the road speed exceeds 2 k.p.h. apply signals 59, 61 to an AND gate 62 which is thus enabled and applies a signal through an OR gate 63 to the AND gate 51. Enabling of the AND gate 51 supplies a signal to a switch 65 which disconnects the adding circuit 47 from the desired clutch position signal line 39 and connects an adding circuit 66 thereto. A ramp generator 70 supplies sufficient voltage to the adding circuit 66 to maintain the clutch fully engaged. In addition the signal 64 from the AND gate 51 is applied through an OR gate 53 to the AND gate 35 which is thus maintained enabled irrespective of the position of the throttle pedal to permit engine braking. Clutch disengagement during ratio shift on an associated change speed gear is effected by applying a signal to the line 67 whereupon the inverter 69 no longer applies a signal to the AND gate 36 which is thus disenabled for clutch disengagement. When the signal on the line 67 is removed for clutch re-engagement the AND gate 36 is re-enabled and the ramp generator 70 restarted to provide a clutch engaging signal which increases at a predetermined rate. During clutch disengagement for ratio shift the AND gate 51 is maintained enabled through holding circuits 71, 74. A signal is supplied to a clutch engage line 68 to engage the clutch when the associated change speed gear is in neutral for synchronizing purposes. The clutch actuating circuit includes electronic switches 27, 28 which respectively supply positive or negative voltages to a clutch control winding 16. The switches 27, 28 are respectively actuated by the marks and spaces of the pulse generator 32. When the switch 27 is "on" the clutch moves towards engagement whilst when the switch 28 is "on" the clutch moves towards disengagement. Hydraulic circuit.-The clutch control winding (16) actuates a valve (13) which supplies and vents a clutch actuating cylinder (12). When the valve (13) connects the cylinder (12) to a pressure liquid supply (14) the clutch is disengaged and on venting the cylinder (12) the clutch re-engages.