Improvements in control devices

摘要

1,136,078. Securing knobs on spindles. SATCHWELL CONTROLS Ltd. 28 March, 1966 [29 March, 1965], No. 13284/65. Heading F2U. [Also in Division H1] In a central heating or air-conditioning system of a building in which the temperature of a heatexchange fluid is varied by an electronic central circuit to counteract the effects of variations in the external ambient temperature, the minimum or maximum desired temperature of the fluid and the ratio between change in the ambient temperature and change in the temperature of the fluid may be preset by a device comprising two movable control members and associated indicating means, one of the control members being used to set the desired minimum and the other the desired maximum temperature of the fluid, and a differential gear between them being arranged to control the temperaturechange ratio. Variable resistor 10 is operated by scale-carrying knob 11, to which it is connected by hollow spindle 12, and determines the minimum temperature of the heating water. Teeth 14 on knob 11 engage two planet pinions 15, which also engage teeth 22 on freelymounted scale-carrying knob 21. Rotation of pinions 15, through a difference in the rotation of knobs 11 and 21, causes spindle 18 to rotate, changing the value of variable resistor 23. Resistor 23 determines the temperature-change ratio by being, for example, part of a bridge in an electronic control circuit. In use knob 21 is rotated to set the desired maximum temperature of the water, knob 11 being held stationary by friction, and knob 11 is rotated to set the desired minimum temperature (with knob 21 held frictionally by clip 24). The rotation of spindle 18 which results operates resistor 23, and adjusts the temperaturechange ratio.