Patent GB-1399242-A (GB)
Title: Position controller
IPC: G05D3/12
Filed: 1971-12-30
Abstract: 1399242 Control of electroc motors ALLEN WEST HOLDING CO Ltd 8 June 1972 [31 March 1971 30 Dec 1971] 8290/71 and 60685/71 Heading H2J [Also in Division F2] A motor-operated device has a movable member which is moved by the motor to one of a number of specific positions to provide on/off control of the supply of a substance or energy form along at least two channels or paths, the member controlled by a position controller having:- a plurality of sensers, each associated with a respective channel or path and thereby with the position of the movable member, each sensor having first and second states dependent on the actual position of the movable member and thereby on the actual state of supply along the channel or path associated with the sensor, and first and second conditions dependent on the desired positions of the member and thereby on the desired state of supply along the channel or path; a selector member or members moving relative to the sensors and in a fixed relationship with the movable member, the selector member(s) being arranged to change the respective sensors from the first state to the second state and vice-versa in accordance with the movement of the member and thereby as the actual state of supply along the associated channel or path is changed; means for converting each respective sensor from the first condition to the second condition and vice versa in accordance with the desired position of the movable member and thereby with the desired state of supply along the associated channel or path; each sensor being arranged such that (1) if it is in its first condition and is put into its second state by the associated selector member, the sensor provides energization of the motor, (2) if it is in its first condition and is put into its first state by the associated selector member, the sensor does not provide energization of the motor, (3) if it is in its second condition and is put into its first state by the associated selector member, the sensor provides energization of the motor and (4) if it is in its second condition and is put into its second state by the associated selector member, the sensor does not provide energization of the motor; a locator member moving in a fixed relationship with the selector member(s) and an associated locator device which is arranged to energize the motor except at specific positions corresponding to said desired positions of the member, to allow the sensors to determine whether the motor is energized or not and whether the position controller stops the motor with the movable member in a desired position or allows the motor to continue moving the member. The motor is preferably electric and may drive a valve member, in which case the channels or paths are conduits for fluid flow, or drive a switching member turning on and off individual colours and colour combinations in stage or film lighting or switching on and off high voltage electricity circuits, in which case the channels or paths are conductors for electricity. The sensors may be hydraulic or pneumatic circuits but are preferably electric and include manually or automatically operated switches, in which case the selector member or members comprise one or more cams. The described embodiments relate to the control of the multi-way valves described in Specification 1,399,241 and 1,399,243. In Fig. 7, an electric motor 3 drives the rotary member of a three-way eight position valve (not shown) and is controlled by cams la, 1b, 1c, 4 and 5 also driven by the motor and by switches 2a, 2b, 2c, 6 and 7 actuated by respective cams and switches 8a, 8b, 8c actuated by thermostats (not shown). Each cam la, 1b, 1c constitutes a selector member, each pair of switches 2a, 8a; 2b, 8b; 2c, 8c a sensor, the cam 4 the locator member and the switch 6 the locator device. The switch 7 may control an output 00 connected to the circulating pump and solenoid-controlled main burner valve of a central heating system, in which case the switches 8a, 8b, 8c are the thermostats in three different rooms heated by the system. During a typical cycle of operations initiated by change-over of one of the switches 8a, 8b, 8c, the motor 3 will be energized through one or more of the sensors 2a, 8a; 2b, 8b; 2c, 8c or through the switch 6, until opening of the latter coincides with all the sensors being open. Such a cycle is described for a particular disposition of three ports in the valve body and rotary member, Figs. 2a and 2b (not shown), providing a single "no flow" position immediately before the "all ways open" position the cams la, 1b, 1c having the same shape and being mutually displaced to correspond to respective ones of the three ports in the valve body. Other arrangements of ports in the valve body and rotary member are described, Figs. la, 1b; 3a, 3b ... 6a, 6b (not shown), the last three having no "no flow" position. Cams la, 1b, 1c may be combined to form a single cam actuating switches 2a, 2b, 2c disposed around it and such a modification is used in Fig. 8, whose single selector cam 11 actuates switches 17a, 17b, 17c which form respective sensors with relays 15a, 16a; 15b, 16b; 15c, 16c controlled by thermostats 14a 14b, 14c in central heating circuits 13a, 13b, 13c controlled by a valve 9 similar to that associated with Fig. 7. Cam 12 and switch 18 constitute the locator member and device. A typical operation of the motor 10 is described for closure of the thermostat 14a, Fig. 9 (not shown), together with the control of output 0 (energizing the pump or heater of the central heating system) in accordance with the position of the valve and the state of the switches 14, 17. In another embodiment, Fig. 10 (not shown), the arrangement of Fig. 7, is modified to control a two-way valve of the type in Fig. 4a and 4b (not shown). Other modifications and optional features are:- (1) the use of a brake to stop the motor after de-energization, (2) the replacement of the camoperated switches by multi-contact rotary switches, (3) the use of mechanical or electrical devices to indicate the valve position and (4) the addition of further controls (e.g. time, manual or frost thermostats) to the sensors.