GB2341792A

GB2341792A - Shower assembly

Info

Publication number: GB2341792A
Application number: GB9918400A
Authority: GB
Inventors: Christopher Terrell
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-08-07
Filing date: 1999-08-05
Publication date: 2000-03-29
Anticipated expiration: 2019-08-05
Also published as: GB9918400D0; GB9817091D0; GB2341792B

Abstract

A personal shower receives hot water (306) and cold water (307). Hot and cold water are mixed in a mixing chamber (311) to provide an outlet (101) of warm water at a selected temperature. A manual control (301) initiates the flow of water whereafter further manual operation of said control defines a temperature setting by means of a potentiometer (315). A control circuit (313) receives an output from the potentiometer (315) and from a temperature sensor (314) in order to control a servomotor (316) which in turn adjusts valves (309, 310) for the hot and cold water supplies. A solid state circuit (308) is configured to produce power for the control circuit from the temperature differential between the hot and cold water supplies.

Description

TER-PI5-GB 2341792 Personal Shower Assembly The present invention relates

to a shower assembly including connecting means configured to be connectable to a water supply. The present invention also relates to a shower assembly including connecting means configured to be connectable to a cold water supply and connectable to a hot water supply.

Shower systems are known in which hot and cold water are received to produce a mixture of a suitable temperature for the purposes of personal showering. A problem with known mechanical systems is that they tend to exhibit an inherent delay. For safety reasons, the temperature of the water must not exceed a predetermined maximum, therefore thermostatic based systems tend to produce a water mix that is too cold until the appropriate thermostatic adaptations have taken place.

A solution to the problem of mechanical/thermal inertia present in mechanical thermostatic systems is to replace these with electronically controlled systems. However, a problem with electronic systems is that they require a reliable power source in order to be operational which creates problems in that it is highly undesirable to connect shower systems to a mains electricity supply if electricity is not required for the purpose of heating the water.

According to a first aspect of the present invention, there is provided apparatus for personal showering, comprising means for receiving a hot water supply, means for receiving a cold water supply, mixing means for mixing hot and cold water from said supplies, control means for adjusting the mixing of hot and cold water, and solid state circuitry configured to produce power for said control means from the temperature differential between said TER-P15-GB 2 hot and cold water supplies.

Preferably, the solid state device includes thermoelectric cooling circuits operating in reverse and a plurality of said circuits may be mounted in a housing. Preferably, electrical outputs from said devices are connected in series, whereas said devices are preferably thermally connected in parallel.

Each device is preferably housed within a respect cavity and each of said cavities may have a baffle to enhance water flow.

According to a second aspect of the present invention, there is provided a method of controlling the output temperature of water from a personal shower system, comprising the steps of releasing a mechanical valve so as to allow the flow of hot water and the flow of cold water into a mixing chamber; deriving electrical power from solid state circuitry configured to be heated on one side by said hot water supply and configured to be cooled on an opposing side by said cold water supply; powering control circuitry; measuring the temperature of the output mixed water; and adjusting electrically controlled valves in response to said measured temperature.

The invention will now be described by way of example only, with reference to the accompanying Figures, of which:

Figure I shows a shower cubicle in a non-operational condition; Figure 2 shows the shower cubicle of Figure 1 in an operational condition; Figure 3 shows a flow control system for the shower identified in Figure 2; Figure 4 details a thermoelectric generator of the type shown in Figure 3; Figure 5 shows a cross-section of the generator identified in Figure 4; Figure 6 details gate valves used in the assembly shown in Figure 3; TER-P15-GB 3 Figure 7 shows a schematic representation of control circuitry of the type used in the system shown in Figure 3; Figure 8 shows a schemafic representation of an alternative embodiment.

A shower cubicle is shown in Figure 1 in which water flows from a shower head 101 after manual operation of a water tap 102. Water is collected in water tray 103 and surroundings are protected from water spray by cubicle walls 104.

The shower cubicle of Figure 1, after manual operation of the tap 102, is shown in Figure 2. Water flows to the shower head 101 via hot and cold water pipes and a mixing chamber, which facilitates the mixing of hot and cold water. The temperature of water 201 emerging from the shower head 101 is displayed on a liquid crystal display (LCID) 202 mounted on a front plate 203 of a flow control system. The temperature of the issuing water may be adjusted by further operation of the tap 102.

The flow control system for the shower of Figure 2, is shown in Figure 3. Tap 102 consists of a handle 301, connected to a ceramic disc 302. The disc contains two slots 303 which allow the flow of water from hot and cold supplies when aligned with openings 304. Hot and cold water enters the system via pipes 306 which are connected by pipe connectors 307 to a thermoelectric generator unit 308. The water first passes through the thermoelectric generator unit 308 and then through gate valves 309 and 310.

Gate valve 309 is in the closed posifion and allows only a minimal flow of hot water through the opening 305. Gate valve 310 is wide open, allowing a fast flow of hot water through the opening 304. The water from both openings enters a mixing chamber 311 before passing through a pipe 312 and emerging at the shower head 101.

TER-P1 5-GB 4 The temperature of the water passing through the pipe 312 is monitored by a control unit 313 by means of a thermistor 314 attached to the pipe 312. The control unit provides an indication of the measured temperature by means of the LCID 202 mounted on the front plate 203.

If the water is not at the required temperature, the temperature is adjusted by manually rotating the handle 301. Manual operation of handle 301 adjusts the setting of a potentiometer 315, which is monitored by the control unit 313. The potentiometer is mounted on the rear of the front plate 203 and is located around the handle 301. In response to the setting of the potentiometer and to the temperature of the thermistor 314, the control unit provides a voltage to a servo-motor 316. The servo-motor is designed for low energy consumption and is of a type used in portable personal tape/disc players. The voltage applied to the servo-motor causes said motor to rotate a shaft 317. The sense of rotation of the shaft 317 is determined by the polarity of the applied voltage. The voltage polarity is dependent upon the temperature and hence resistance of the thermistor and the resistance setting of the potentiometer. The rotation of the shaft 317 causes movement of the gate valves and thereby changes the rate of flow of hot and cold water.

By this means the ratio of hot to cold water is changed and hence the temperature of the emerging water is adjusted.

The temperature of the emerging water is determined by the position of the gate valves, and the electrically operated gate valves are adjusted in response to the adjustment of the potentiometer, which is performed by manually operating the tap.

When a difference in temperature between the hot and cold water is sufficiently large, the electrical power required for the operation of the control unit and the servo-motor is provided by the thermoelectric generator unit 308.

TER-P15-GB For example, a temperature difference of 200C is sufficient for this purpose.

The output from the thermoelectric generator unit is supplied to the control unit by wires 318. A battery 319 is connected to the wires 318 in parallel with the thermoelectric generator unit 308 and when the temperature difference between the water supplies is small, the battery provides sufficient power to energise the control unit and the servo-motor.

The thermoelectric generator unit 308, shown in Figure 3, is shown in the exploded view of Figure 4. The purpose of the unit is to convert a portion of the heat contained within the hot water to electrical energy.

The unit consists of two similar blocks 401 and 402, rigidly attached to each other by means of screws 403. Hot water flows into the block 401, through opening 404 and enters a first of four similar cavities 405, 406, 407 and 408. It then leaves the cavity 405 via pipe 409 and enters the second cavity 406. The hot water then passes through the cavities 407 and 408 before leaving the unit via pipe 410.

A baffle 411, ensures that the whole of the water in the cavity 405 is flushed through and so is regularly replenished. In particular the baffle will tend to stop eddy pools establishing, which would reduce the efficiency of the generator unit. Similar baffles in cavities 406, 407 and 408 have similar effect in those cavities.

In a similar manner, the block 402 has cold water passing through it and has four similar cavities to those in block 401.

Four similar thermoelectric generators 412, 413, 414 and 415 are sandwiched between the two blocks 401 and 402 and are located between the two sets of cavities. Four'Urings 416 are located around the perimeter of the cavities and form a seal between the thermoelectric generators and the block 401. The seals, thus formed, prevent hot water escaping from the TER-P15-G8 6 generator unit or into the block 402. Four similar 'O'rings (not shown) are located around the perimeter of the cavities in the block 402 and prevent leakage of cold water in a similar way.

The thermoelectric generators are connected in series by wires 423 and wires 318 provide a means of supplying the output of the generator unit to the control unit 313.

The thermoelectric generator unit 308, shown in Figure 4, is shown in cross-sectional view of Figure 5. The two blocks 401 and 402 are separated by the thermoelectric generator 412. The blocks are made from polypropylene but other materials suitable for use in domestic water systems may be used.

The thermoelectric generator 412 is a DuraTEC Thermoelectric Cooler, supplied by Marlow Industries, Inc. of Dallas, Texas, USA. It consists of several N-type and P-type pellets 502 connected electrically in series and thermally in parallel, sandwiched between two ceramic plates 503 and 504.

In normal operation, the Thermoelectric Cooler is supplied with a voltage and the electrical power consumed is used to pump heat from one side of the device to the other. By this means the device is used as an electrically powered cooler. However, in the present invention, the device is used in an alternative, reverse mode. That is, some of the heat in the hot water contained in cavity 405 passes through the thermoelectric generator, into the cold water contained in the cavity 501 and in so doing generates electrical energy.

The opening 404, through which water enters the cavity 405, may be seen in Figure 5, along with the baffle 411. A similar opening 505 may also be seen, through which cold water enters the cavity 501, along with a baffle 506. 'O'rings 416 and 507 form water tight seals between the blocks and the TER-P15-G8 7 sides of the generator 412.

The gate valves 309 and 310 shown in Figure 3 are shown in detail in Figure 6. A drive gear wheel 601 is axially mounted on, and rotates in co operation with the shaft 317. A slave gear wheel 602 is driven by gear 601, such that an anticlockwise rotation of gear 601 will cause a clockwise rotation of the gear 602. The gear wheel 602 is axially mounted on, and drives, a shaft 603. A gate 605 is located within the valve body 606 and partially obscures an aperture 607. The gate 605 is configured to engage a threaded portion 608 on the shaft 603, such that, if the shaft 603 is rotated clockwise the gate 605 is lifted and the aperture 607 becomes less obscured. By similar means, if shaft 317 is rotated anticlockwise a gate 609 is moved downward and further obscures an aperture 610. Cold and hot water passes through the apertures 607 and 610 respedvely, so the described rotations would tend to reduce the flow of hot water and increase the flow of cold water. In a similar manner, the rate of flow of hot water may Ge increased and the rate of flow of cold water decreased by an anticlockwise rotation of shaft 603 and clockwise rotation of shaft 317.

A rotating seal assembly 611 is located around shaft 603 and prevents water escaping from the gate valve 310. The seal assembly 611 is designed to cause minimal resistance to rotation due to low friction between its components. As a consequence the power lost in the seal assembly is also low compared to other similar seals. A description of the seal used is provided in UK Patent Application No. 99 17 169.6. A similar rotating seal (not shown) is provided around shaft 317 for similar purposes.

A schematic representation of control circuitry contained within unit 313 is detailed in Figure 7. Outputs from thermistor 314 are effectively connected in a bridge configuration with balancing resistors 701 and 702. As TER-P15-GB 8 shown in Figure 7, this provides inputs to a differential operational amplifier 703 configured to produce an output under conditions where the thermistor 314 detects a temperature different from that selected by the potentiometer 315. This output is then supplied to drive servo-motor 316 which in turn results in an appropriate adjustment to valves 309 and 310.

An alternative embodiment is shown in Figure 8 in which gate valves 309 and 310 of the type shown in Figure 3 are replaced by butterfly valves 801 and 802. Valves 803 and 804 represent the same valve as valve 801 but at different orientations. Similarly, valves 805 and 806 also represent different orientations of valve 802.

Valve 801 is present within a hot water supply 807 which would initially be in a closed orientation, as shown at 801, primarily for safety reasons.

Consequently, water flow would be initiated from cold supply 808 with valve 802 being in its open orientation. A thermoelectric generator 809 is located between the hot water supply 807 and the cold water supply 808, configured to produce an output which increases monotonically with temperature differential. A processing unit 810 also receives an input from a thermistor 811 and from a potentiometer 812. The electrical connections within processing unit 810 are substantially similar to those shown in Figure 7.

Consequently, if the output water mix is too cold, a positive signal is supplied to a servomotor 813 resulting in activation of the valves such that they initially rotate to positions 803/805 and then further to positions 804/806. This results in an increased flow of hot water which may in turn may result in the mixed water reaching a temperature that is too high. Under these conditions, a negative signal is supplied to servomotor 813 resulting in the valve orientations adopting positions similar to those shown at 803/805. These transitions occur gradually until an equilibrium is reached resulting in the TER-P15-GB 9 mixed water delivered to the shower head 815 being of the desired temperature.

TER-P15-GB

Claims

1. Apparatus for personal showing, comprising means for receiving a hot water supply, means for receiving a cold water supply, mixing means for mixing hot and cold water from said supplies, control means for adjusting the mixing of hot and cold water, and solid state circuitry configured to produce power for said control means from the temperature differential between said hot and cold water supplies.

2. Apparatus according to claim 1, wherein said solid state device includes thermoelectric cooling circuits operating in reverse.

3. Apparatus according to claim 2, wherein a plurality of said solid state devices are mounted in a housing.

4. Apparatus according to claim 3, wherein electrical outputs from said devices are connected in series.

5. Apparatus according to claim 3, wherein said devices are thermally connected in parallel.

6. Apparatus according to claim 3, wherein each of said devices is housed within a respective cavity.

7. Apparatus according to claim 6, wherein each of said cavities has a baffle to enhance water flow.

TER-P15-GB

8. Apparatus according to any of claims 1 to 7, including means sensitive to output water temperature.

9. Apparatus according to claim 8, wherein said means sensitive to output water temperature is a thermistor.

10. Apparatus according to any of claims 1 to 9, wherein temperature is controlled by electrical control apparatus.

11. Apparatus according to claim 10 when dependent on claim 8, wherein said electrical control apparatus is connected in a bridge circuit with said apparatus sensitive to output water temperature.

12. Apparatus according to claim 11, wherein an output from said bridge circuit is supplied to an operatonal amplifier.

13. Apparatus according to claim 12, wherein an output from said operational amplifier drives a servomotor.

14. Apparatus according to claim 13, wherein said servomotor operates mechanical valves to adjust the flow of hot and cold water.

15. Apparatus according to claim 14, wherein said valves are gate valves.

16. A method of controlling the output temperature of water from a personal shower system, comprising the steps of TER-PI5-GB 12 releasing a mechanical valve so as to allow the flow of hot water and the flow of cold water into a mixing chamber, deriving electrical power from solid state circuitry configured to be heated on one said by said hot water supply and configured to be cooled on an opposing side by said cold water supply; powering control circuitry; measuring the temperature of the output mixed water; and adjusting electrically controlled valves in response to said measured temperature.

17. A method according to claim 16, including manual adjustment means configured to specify an output temperature.

18. A method according to claim 17, wherein said manual adjustment means co-operates with said mechanical valve, wherein the opening of said mechanical valve and the adjustment of said adjustment means can be carried out by a shared operation.

19. A method according to claim 18, wherein said shared operation comprises the process of rotating a handle.

20. A method according to any of claims 16 to 19, wherein said solid state circuitry includes thermoelectric cooling circuits operating in reverse.