GB2262588A - Fluid temperature controller - Google Patents

Abstract

A fluid temperature control apparatus comprises a temperature sensor 12 in an outlet 18 and a controller 10 which, in response to variations in signals received from the sensor 12, causes valves 14, 16 in hot and cold inlets respectively to move simultaneously in opposite senses in order to obtain a temperature correction. An adjustment of flow rate may be effected by simultaneous movement of the valves 14, 16 in the same sense. <IMAGE>

Description

FLUID TEMPERATURE CONTROLLER The present application relates to a fluid temperature controller and more especially, in its preferred aspect to a controller for thermostatically controlling the temperature of outlet water for use in a domestic shower or otherwise.

Previously it has been known to control water flow and temperature by a manually operated system such as two separate valves or taps, one for each of a hot water supply and a cold water supply. Alternatively, it has been known to use a single, more complicated, control valve for controlling hot and cold water supplied which may have thermostatic temperature control in which a valve position is controlled directly by a limital or other temperature responsive unit.

However, systems using these thermostatic devices can suffer from slow response times, given a change in water pressure on one of the water supplies, although a thermostatic system will ultimately restore the desired outlet temperature, larger temperature fluctuations than are desirable can occur in the process.

It is an object of the invention to provide an improved temperature control system which is easy to use and provides quick and accurate correction of any temperature fluctuations.

According to the present invention there is provided a domestic shower controller comprising a hot water inlet and a cold water inlet, a servo for each inlet valve for powering movement of the respective inlet valves between open and closed positions, a common outlet for water received from the two inlet valves, a temperature sensor for sensing the temperature of water in said outlet, and a controller for controlling operation of said servo of each inlet valve in response to a signal received from said sensor to adjust said valves to provide a required temperature at said outlet, said controller being such as normally simultaneously to cause movement of both inlet valves in opposite senses in order to obtain a temperature correction.

Hence, the present invention may rapidly compensate for variations in inlet temperatures and pressures to maintain a substantially constant outlet temperature.

Further, this can be achieved whilst still maintaining a substantially steady outflow rate.

The present invention will be more clearly understood from the following description, given by way of example only, with reference to the accompanying drawings, in which: Figure 1 diagramatically illustrates a domestic shower controller apparatus embodying the present invention when passing cold water only; Figure 2 illustrates the apparatus when passing mixed hot and cold water; and Figure 3 illustrates the apparatus when passing hot water only.

Referring to the Figures, a controller 10, which is shown powered by a mains electric power supply, is connected to two motors 6, 8 each operating one of the hot and the cold control valves 14, 16. Additionally, the controller 10 is connected to a temperature sensor 12 positioned in the water outlet 18.

To control the system, the controller 10 is provided with control switches and a display. Since the controller 10 is ideally placed in a bathroom, it preferably has touch sensitive control pads and is in a water resistant casing. A control panel of the controller is provided with up and down pads for raising or lowering the outlet water temperature in discrete steps and a display which comprises a numeric display but which preferably comprises a series of light emitting diodes which give an indication of the temperature by means of the number of l.e.d.s shining.

Hence, in operation, the temperature sensor 12 provides a low voltage signal to the controller 10 representative of the temperature of the outflowing water.

This signal is compared by the controller 10 to that required by the user of the system, i.e. that communicated by the control panel. Hence, according to whether the sensed temperature of the outflowing water is higher or lower than that desired, the controller 10 provides controls the two motors 6, 8 to actuate the control valves 14, 16 accordingly. Preferably the motors are stepped, motors which may either operate with a separate power supply with actuation controlled by signals received from the controller or the controller may itself provide the power impulses to the motors.

As illustrated in Figure 1, for the coldest setting of the outflowing water, the hot water valve 14 is shut and the cold water valve 16 is fully open. Accordingly, as shown in Figure 3, for the hottest outflowing water, the cold water valve 16 is shut and the hot water valve is fully open.

In Figure 2, an intermediate temperature setting is illustrated in which both of the valves 14, 16 are partially open. Given this situation, if the temperature sensor 12 detects a drop in temperature, the controller 10 simultaneously controls the hot water valve 14 and the cold water valve 16 in opposed senses slightly to open and to close respectively. By moving the two valves 14, 16 in opposition by the same amount it is thereby possible to maintain a steady through-flow of water. Hence, accordingly, should the temperature sensor 12 measure an increase in outflcwing water temperature, the hot water valve 14 is controlled to close by the same amount as the cold water valve 16 is controlled to open. Hence, the system provides an almost instantaneous way of controlling the mixture of hot and cold water according to a measured outflowing water temperature.Unlike previous thermostatic devices, it does not rely on a thermostatic control device itself to change temperature but instead gives a substantially immediate response.

Valves 14,16 can also be used to control the total through-flow of water and this may be achieved by controlling them to move in the same direction. Hence, when less outflowing water is required, both valve 14 and valve 16 should be controlled to close slightly and, when more outflowing water is required, both valves 14, and valve 16 should be controlled to open slightly. However, in some circumstances it may be desirable to provide a separate control for volume throughput and simply use the valves 14 and 16 for temperature control.

The valves 14, 16 may be of any type suitable for effectively maintaining a variable through-flow of water and while ideally they may be such that their through flow of fluid changes linearly across their range from fully closed to fully open, this is by no means essential providing that the controlled steps of movement in response to temperature changes are sufficiently small.

The present invention is equally applicable to other embodiments such as a system where the controller 10 is powered by a low voltage power supply or merely receives its power via the motors 6,8 which may be connected to a mains supply.

Alternatively, the controller may be positioned remote from the bathroom, for instance with the motors 6,8, and, hence, a control unit, not illustrated, may be provided remote from the controller and conveniently positioned in the bathroom. The control unit ideally communicates to the controller by means of low voltage signals to ensure the safety of the user.

As to the control panel, any other types of switches or the like may be provided, as well as other forms of display. Furthermore, the control of the water temperature by the control panel and controller 10 may be of a continuously variable type although in that case one may need to provide a feed back signal from each valve to the controller in order that the controller will be aware of the setting of the valves at any particular moment.

Finally, the controller 10 or the control unit may be provided with a memory such that pre-set temperatures and volume throughflow may be instantaneously selected.

The valves 14, 16 may be controlled to move in discrete steps. However, even where the required temperature is chosen in discrete steps, it may be preferred to control valves 14, 16 in a continuously variable manner or in discrete steps of smaller size than needed for the required movement of changes in temperature.

Accordingly, any suitable means such as a motor, stepping motor or solenoid may be used to move the valves.

In order to achieve a required flow of outlet water a flow rate sensor may be provided in the water outlet 18, connected to the controller 10, to provide a control signal thereto. Hence, in such a closed loop system, a drop or rise in the outflowing water below a desired flow will cause the controller 10 to control the valves 14, 16 accordingly.

Alternatively or additionally, it may be desired to provide a valve in the water outlet 18 by means of which the outflow of water may be controlled or shut off. This valve may be, for example, held open by an energised solenoid, such that given a power failure or fault in the system, it would automatically return to its shut position.

Alternatively or additionally such a valve may be manually controllable or the powered valves 14,16 may be manually actuated to a shut off position.

Lastly, as above, to improve the safety of the system, valves 14, 16 maybe such that given a power or system failure, they should return to their shut positions.

Alternatively or additionally, they may be manually controllable to override their controlling motors.

Preferably also, they should be designed such that they will automatically close to prevent a reverse flow of water, e.g. hot water flowing back into the cold water system due to a drop in pressure of the cold water system.

Claims (9)

1. A fluid temperature control apparatus comprising an inlet valve for hot fluid and an inlet valve for cold fluid, a servo for each inlet valve for powering movement of the respective inlet valves between open and closed positions, a common outlet for fluid received from the two inlet valves, a temperature sensor for sensing the temperature of fluid in said outlet, and a controller for controlling operation of said servo of each inlet valve in response to a signal received from said sensor to adjust said valves to provide a required temperature of fluid at said outlet, said controller being such as normally simultaneously to cause movement of both inlet valves in opposite senses in order to obtain a temperature correction.

2. Apparatus according to claim 1, wherein the inlet valves are operable in discrete steps between their open and closed positions.

3. Apparatus according to claim 1 or 2, wherein the controller is adapted to control total volume throughput of fluid whilst maintaining the temperature of the output at a required level by simultaneous adjustment of the inlet valves in the same sense.

4. Apparatus according to any preceding claim, wherein a separate manual control valve is provided to ensure the possibility of turning off fluid flow, in the event of an electrical power failure.

5. Apparatus according to any preceding claim, wherein a manual control of the individual valves is provided to ensure the possibility of turning off fluid flow in the event of an electrical power failure.

6. Apparatus according to any one of claims 1 to 3, wherein a solenoid controlled valve is provided for automatically switching of water flow in the event of disconnection of electric power.

7. Apparatus according to any preceding claim further comprising a volume throughput sensor in said outlet connected to said controller.

8. Apparatus according to any preceding claim, wherein the controller is a sealed unit with touchsensitive controls.

9. A domestic shower control apparatus constructed and arranged to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.