Control system for dental drill hose pump - has timer to control reversing of drive motor on switch off to prevent liquid leakage and contamination

摘要

The pump for a dental drill has a control system for the pump motor which operates so that after the motor has been switched off, it is driven in the opposite direction for a short time. This prevents leakage each time the pump is used, thus preventing contamination of the eouipment. The pump can be turned through a half rotation after switching off. The pump is reversed at a fixed speed independently of the speed of rotation in the other direction, this being controlled by a foot pedal. A timing device is triggered by starting signals when the pump motor is switched off and output signals are obtained for a determined period of time which operate a relay controlling the direction of rotation of the motor and also a switch for the motor power supply.