IMPROVEMENTS IN WHEEL SLIP SENSING ARRANGEMENTS

摘要

1285775 Aritiskid braking systems ROBERT BOSCH GmbH 26 Nov 1969 [27 Nov 1968 (2)] 57847/69 Heading F2F [Also in Division G1] In a wheel slip sensing arrangement in which is obtained a pulse train the pulse frequency of which is dependent upon the angular velocity of the wheel, a monostable multivibrator 31, Fig. 2, having its ON period varied in accordance with the average value of the angular velocity, has its output applied to one input of a NOR circuit 29 to the other input of which is applied a signal indicative of the pulse train whereby a signal is produced by the NOR circuit when the period between the pulses of the pulse train exceeds a predetermined level. Positive pulses from pulse generator 18 coupled to the vehicle axle 13 are applied to the input of monostable circuit 28, one output of which is applied directly to NOR gate 29 and the other output of which is applied to trigger monostable 31 the relaxation period of which is controlled in accordance with the average value of the output from monostable 28 obtained from integrator 32. During admissible variations in the rotational speed of wheel 11 during breaking the relaxation time of monostable 31 is immediately followed by a pulse from the monostable 28 so that NOR gate 29 is not activated. If the wheel begins to lock the pulses from monostable 31 are such as not to fill the intervals between the pulses of monostable 28, Fig. 5 (not shown), so that NOR gate 29 is activated and the output pulse is applied to brake cylinder 15 to reduce the breaking force. In an alternative embodiment, Fig. 6 (not shown), the output from the pulse generator is applied to a bi-stable multivibrator the outputs of which are fed directly to the input of a NOR gate and via a monostable circuit and integrator to a second monostable whose output is applied to the other input of the NOR gate. The pulse generator 18 may be of the variable reluctance type, electromagnetic or light.