Hydraulic drive with proportional valves controlling the feed and discharge

摘要

The invention relates to a hydraulic drive with proportional valves controlling the feed and discharge, in which a volume sensor with a pair of round gearwheels as measurement mechanism is arranged in at least one working conduit of the drive. The tooth movements of the gearwheels are sensed in contactless fashion by means of detectors. Electric pulses are emitted in each case for discrete partial quantities corresponding to the geometrical tooth volume. Also provided is an electronic control system which is provided with a pulse counter and via which the proportional valves are controllable as a function of the number of pulses and/or pulse frequency. With the hydraulic drive, motion sequences with an acceleration ramp and a deceleration ramp are performed. Contactless control of the beginning of the deceleration ramp is effected. For this purpose, a number of pulses corresponding to the oil volume to be fed into the drive during the descent of the deceleration ramp as a function of the working speed and the angle of the deceleration ramp is added in the counter of the electronic system to the actual number of pulses emitted by the volume sensor. That is to say, a preliminary addition of the number of pulses corresponding to this quantity of oil is effected. After the number of pulses corresponding to the total travel has been reached, the drive is switched over to deceleration. The deceleration ramp is then traversed under the control of the proportional valve as a function of the angle of the deceleration ramp. <IMAGE>