IE930264A1 - Valve control systems - Google Patents

Abstract

A valve control system 1 typically for a three-port valve 2 for controlling a domestic hot water/central heating system, comprises a motor M for driving the valve 2 and a plurality of microswitches MS1, MS2, MS3 operable, by means of cams, associated with the valve, for controlling the position of the valve 2 and the illumination of two neon lamps NLA, NLB which provide an indication of the position of the valve 2.

Description

Valve Control Systems I FKoUz ' Thio imrention relates to valve control systems and more especially to such systems for use with motor driven multi-way fluid flow control valves.

A typical example of the use of a motor driven multi-way fluid flow control valve is in the control of a hot water and central heating system in which a three-port valve is provided to control flow of hot water from a boiler into either a hot water system or a central heating system or into both systems. Three types of motor driven three-port valves are commonly in use for this purpose.

A first type of valve is a rotating one which has a valve closure member in the form of a shoe which is spring loaded against the valve chamber and one of the ports. With this type of valve, a cam is fitted to a motor driven spindle connected to the valve closure member (shoe), the cam being arranged to actuate microswitch contacts to stop the shoe in the required position. Energy to operate the valve is provided by means of an electrical motor which is usually synchronous. This moves the valve shoe in one direction to open one port and close another. Energy to the valve closure member is provided by spring means (usually a torsion spring).

A second type of valve is one which has a ball or paddle which blocks the domestic hot water port or the central heating supply port. This member is spring loaded against one of the ports in the un-energised position and is electrically loaded against the other port, the motor moving the paddle or shoe to open one port and block off the other port. When the electrical supply is removed the valve member returns to its original position by spring means (usually coil 2. springs).

A third type of valve is one which has a shoe arrangement like the first type described. With this type a cam is fitted to a spindle with one or more radially located shoe(s). The spindle rotates these shoes in one preset direction. The cam activates microswitch contacts which stop the shoes in the desired position. To take up the original position the shoes do not return by spring means, like the first and second types described. Instead the shoes rotate by means of a mechanical arrangement connected to an electric motor in one fixed direction until the original position is reached. Again the cam opens microswitch contacts to stop the shoes in the desired position.

Normally the operation of the motor is controlled by two on/off thermostats, one being used to sense the temperature of the hot water system and the other sensing the temperature of rooms where the radiators are located. If one of these thermostats calls for heat, it switches on the boiler and pump and directs the hot water to either the domestic hot water system or the central heating system. When both thermostats call for heat simultaneously the valve member moves to a central position which allows hot water to be diverted to both heating circuits (as in the case of a mid-position three-port valve). Valves are also available where the flow is diverted to either heating circuit but not both simultaneously. These valves are usually termed diverter valves.

A problem arises with the various valve types which have been described in that it is very difficult to determine in which position the valve is set. Some valves similar to the second type described above provide a mechanical indicating system by means of a 3. lever which moves as the valve operates. This mechanical system is disadvantageous in that it is not easily adaptable to the first and third valve types described above, and the indicator is difficult to see, especially if the valves are located in dark, out of the way places.

It is an object of the present invention to provide a valve control system having an improved indicating system.

According to the present invention there is provided a valve control system for a domestic hot water and central heating system comprising an electric motor for driving a fluid flow control valve having at least three positions, switch means associated with said valve and operable to control the position thereof, and electrical illumination means operated by said switch means for affording an indication of the position of said valve, in which said valve comprises a first output port for connection to a domestic hot water system, a second output port for connection to a central heating system and a valve control member which is rotatable to open said first output port, said second output port or both of said ports, said electrical illumination means comprising a first electrical lamp which is illuminated when said first output port is open, and a second electrical lamp which is illuminated when said second output port is open, both said first and second electrical lamps being illuminated when both of said output ports are open.

By providing illuminated signals indicative of the position of the valve, the disadvantages of the prior known mechanical systems are overcome.

In carrying out the invention it may be arranged that said switch means comprises a plurality of ί. electrical switches and cam means associated with said valve for operating said switches.

It may be arranged that such a system comprises a hot water thermostat device to which an electrical supply terminal is connected, said thermostat device connecting said electrical supply terminal to one of said electrical switches for controlling the illumination of said first electrical lamp, and a central heating thermostat device to which an electrical supply terminal ig connected, said second electrical lamp being connected to said central heating thermostat device for controlling its illumination.

An exemplary embodiment of the invention will now be described reference being made to the accompanying drawings, in which Figs. 1 to 3 depict schematic circuit diagrams of a valve control system in accordance with the present invention in each of three different operating modes.

In Fig. 1 of the drawings there is shown a valve control system 1 for controlling the operation of a three-port valve 2 which is used to control the flow of hot water via an input port (not shown) to either a hot water system, via a port A, or to a central heating system, via port B, or to both such systems. The valve 2 is of the first type referred to above and includes a valve shoe 3 which is mounted on a spindle (not shown) and is rotatable to control the flow of hot water to one or other or both of the poj*ts A and B as will be described. The spindle of the valve 2 is driven by an electrically energised motor M, which is preferably a synchronous motor, which forms part of the valve control system 1. The spindle of the valve 2 is also provided with three cam members (not shown) in well known manner, which actuate corresponding microswitches .

MS1, MS2 and MS3 which also form part of the valve control system 1.

The valve control system 1 of Fig. 1 operates under the control of two on/off thermostat controls, a domestic hot water (DHW) control 4 which senses the temperature of the domestic hot water supply, and a central heating (CH) control 5 which senses the temperature of a room in which a central heating radiator is located. There may be more than one CH control 5. The DHW control 4 and the CH control 5 are each connected to the live L terminal of a mains supply, the neutral of which is connected to an input N of the valve control system 1.

Fig. 1 depicts the circuit arrangement which pertains when the DHW control 4 has operated, which requires hot water to be supplied to port A of the valve 2, in which position the valve shoe 3 blocks the entrance to port B of the valve 2. In this configuration the live L terminal is connected via the ON terminal of DHW control 4 to a conventional hot water boiler and pump unit 6, which supplies pumped hot water to the inlet port (not shown) of the valve 2, and also to microswitch MS3 which, via a terminal 3" thereof, connects the live L terminal to one side of a neon light NLB, the other side of which is connected via a resistor RB to the neutral N terminal of the mains supply. This causes the neon light NLB to light up to indicate that the valve 2 is operating in the domestic hot water mode.

Fig. 2 depicts the circuit arrangement which pertains when both the DHW control 4 and the CH control 5 have operated, thereby requiring hot water to be supplied to both of the ports A and B of the valve 2, in which position the valve shoe 3 adopts a mid35 position in which both of the ports A and B are open. 6.

In this configuration, DHW control 4 is ON and connects the live L terminal to the boiler and pump unit 6, which pumps hot water to the valve 2, and also, via the microswitch MS3 connects the live L terminal to the neon light NLB which is caused to be illuminated. The CH control 5 is also ON and connects the live L terminal to one side of a neon light NLA, the other side of which is connected via a resistor RA to the neutral N terminal of the mains supply. The neon light NLA is thus caused to be illuminated. The CH control 5 also connects the live L terminal to the "2" terminal of microswitch MS1 and through the "1 terminal thereof to the motor M (which will be in the position shown in Fig. 1). The motor M is therefore energised to cause the valve shoe 3 thereof to rotate. As the valve shoe 3 approaches the mid-position shown in Fig. 2, the microswitch MS1 is caused to be operated by its respective cam associated with the valve 2. The electrical supply to the motor M via microswitch MS1 is broken but power to the motor M is maintained via microswitch MS2 and via diode D and resistor R which produce half-wave rectification of the supply signal to the motor M which affords sufficient power to the motor M to hold the valve shoe 3 in the mid-position against the action of a return spring (not shown). The arrangement is maintained in this mid-position whilst the DHW control 4 and the CH control 5 are both ON, the neon lights NLA and NLB also both being illuminated.

Fig. 3 depicts the circuit arrangement which pertains when the DHW control 4 is OFF and the CH control 5 is ON, thereby requiring hot water to be supplied only to port B of the valve 2, in which position the valve shoe 3 closes the port A thereof.

In this configuration DHW control 4 is OFF and the microswitches MS1, MS2 and MS3 are initially as shown 7. in Fig. 1. With DHW control 4 OFF, the live L terminal is connected to the "3" terminal of microswitch MS1. With CH control 5 ON, the live L terminal is connected to the neon light NLA which is therefore illuminated, and via the "2" and 1 terminals of microswitch MS1 is connected to the motor M. The motor M is therefore energised and causes the valve shoe 3 to be rotated against the action of the return spring (not shown). When the valve shoe 3 reaches its mid-position (Fig. 2) microswitch MS1 operates as already described but energisation of the motor M is maintained through the "1M and 3 terminals of the microswitch MS1. Continued energisation of the motor M causes the valve shoe 3 to be rotated to the position shown in Fig. 3 where port A is closed. As the valve shoe approaches this position microswitches MS2 and MS3 are operated by their respective cams. Operation of microswitch MS2 causes the boiler and pump unit 6 to be operated and operation of microswitch MS3 prevents neon light NLB from being illuminated. Thus, in the position depicted in Fig. 3 only neon light NLA is illuminated corresponding to the CH control 5 being ON. When the CH control is turned OFF, i.e. when the central heating demand has been satisfied, the energisation of the neon light NLA and of the boiler and pump unit 6 will cease, but energisation of the motor M will be maintained until the next demand is made on the DHW control 4.

From the valve control system which has been described, it will be appreciated that the position of the valve 2 is indicated by the illumination of one or other or both of the neon lamps NLA and NLB. It will be appreciated that the system which has been described has been given by way of example only and may be modified to suit any particular application and particular control valve used.

Claims (5)

1. A valve control system for a domestic hot water and central heating system comprising an electric motor for driving a fluid flow control valve having at 5 least three positions, switch means associated with said valve and operable to control the position thereof, and electrical illumination means operated by said switch means for affording an indication of the position of said valve, in which said valve comprises a 10 first output port for connection to a domestic hot water system, a second output port for connection to a central heating system and a valve control member which is rotatable to open said first output port, said second output port or both of said ports, said 15 electrical illumination means comprising a first electrical lamp which is illuminated when said first output port is open, and a second electrical lamp which is illuminated when said second output port is open, both said first and second electrical lamps being 20 illuminated when both of said output ports are open.

2. A system as claimed in claim 1, in which said switch means comprises a plurality of electrical switches and cam means associated with said valve for operating said switches. 25

3. * A system as claimed in claim 2, comprising a hot water thermostat device to which an electrical supply terminal is connected, said thermostat device connecting said electrical supply terminal to one of said electrical switches for controlling the 30 illumination of said first electrical lamp.

4. A system as claimed in claim 2 or claim 3, comprising a central heating thermostat device to which an electrical supply terminal is connected, said second electrical lamp being connected to said central heating 9. thermostat device for controlling its illumination.

5. A valve control system substantially as hereinbefore described with reference to accompanying drawings.