NZ543986A - Fluid mixing device having movable disk with plurality of sets of apertures - Google Patents

Abstract

A fluid control device (10) for mixing of fluids, suited for delivery of water at controlled temperature and flow rate, is disclosed. The device has first and second fluid inlets and an outlet for delivery of a resultant mixture at controlled parameters. The fluid control device includes a stationary disk (21) and a moveable disk (23) in contact with the stationary disk, where the moveable disk has a plurality of sets of apertures for flow through the disks of the first and second fluids to a mixing chamber (24) and a set of plurality of apertures for flow of mixed fluid through the disks to the outlet. A moving means provides selective movement of the moveable disk to control the flow of fluid.

Description

( No: 543986 Date: 7 December 2005 NEW ZEALAND Patents Act 1953 COMPLETE SPECIFICATION IMPROVEMENTS IN FLUID CONTROL DEVICES v - WE, THE INNOVATION FACTORY LIMITED a New Zealand company of 50 George Street, Palmerston North, New Zealand do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- 2 TITLE OF THE INVENTION IMPROVEMENTS IN FLUID CONTROL DEVICES BACKGROUND TO THE INVENTINON This invention relates to improvements in fluid control devices.

The present invention more particularly concerns an electronic remotely controlled mixing valve that is suited for (but not exclusively so) delivery of water at controlled temperature and flow rate. The mixing valve can have application in domestic use, such as a bathroom, institutional use such as rest homes, hospitals and other medical and in aged care facilities. However, it can be suitable for use in industrial applications such as mixing chemicals or a chemical with water.

Control devices or mixing vaive devices for mixing hot and cold water and supplying the resultant mixture to a single outlet at controlled temperature and flow rate are known. There are many designs of mixing valves, which to varying degrees of success provide for the mixing of hot and cold water flows (possibly at different pressures) so as to provide a controlled temperature and flow rate at an outlet.

It is known that the control of the mixing valve be carried out electronically. In many such arrangements, however, there is a high degree of complexity. For example, the mixing valve may include many moving parts. This can include a plurality of motors. Consequently, not only are such valves of costly construction but can be ineffective or inefficient in operation. The many moving parts can lead to issues such as difficulties in sealing and suffer from the wearing of components.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fluid control device for mixing of fluids that is able to be controlled electronically without incorporating the complexity of moving parts typically associated with known mixing devices.

INTELLECTUAL PROPERTY OFFICE OF N.Z. 2 6 SEP 2008 RECEIVED 3 According to one broad aspect of the invention there is provided a fluid control device for mixing of fluids the device being of a type having first and second inlets which can, in use, be respectively connected to first and second fluid supply lines, and an outlet for delivery of a resultant mixture at controlled parameters, the fluid control device including a stationary disk, a moveable disk in contact with the stationary disk, the moveable disk having a plurality of sets of apertures for flow through the disks of the first and second fluids to a mixing chamber and a set of plurality of apertures for flow of mixed fluid through the disks to said outlet, there being moving means for selective movement of the moveable disk to control the flow of fluid to regulate parameters thereof.

In the preferred form of the invention the disks are of ceramic construction. Preferably each plurality of apertures for the first and second fluids provides three apertures each representing a certain flow rate there through. The three apertures can respectively provide full flow, substantially 60% of full flow and substantially 30% of full flow.

According to the preferred form of the invention the moving means is a stepper motor coupled to the moveable disk.

Preferably the stepper motor is actuated by an electronic control means which is controlled remotely from a user interface. More preferably input from the user interface to the electronic control means is by radio frequency signals.

Preferably a position sensor is coupled to the electronic control means to sense the angular position of the moveable disk. The position sensor can be a photo-interrupter. / 4 In the preferred form of the invention a solenoid valve is provided with the outlet of the mixing device and is controllable by the electronic control means.

In a preferred form of the invention the first fluid is hot water and the second fluid is cold water.

According to the preferred form of the invention the electronic control means is coupled to temperature sensors located to sense the temperature of the hot water and the temperature of the mixed water.

BRIEF DESCRIPTION OF THE DRAWINGS In the following more detailed description of the invention according to one embodiment reference will be made to the accompanying drawings in which:- Figure 1 is a perspective view of fluid control device for mixing of fluids the device incorporating the invention, Figure 2 is an exploded view of the mixing device, Figure 3 is a perspective exploded view of disk elements that form part of the internal workings of the mixing device.

Figure 4 is a perspective illustration of a form of the user interface, Figure 5 is a perspective illustration of a second form of the user interface, and Figure 6 is basic circuit diagram of the electronic control of the mixing device.

SPECl774 OCTOBER 2005 DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION While the present invention has application to mixing of different fluids the following description will, byway of example, describe the device in the context of mixing hot and cold water.

The water mixing device to which the present invention is applied in one embodiment is thus of a type that incorporates a pair of inlets one of which is adapted for connection to a hot water supply line and the other is adapted for connection to a cold water supply line. The manner in which the mixing device 10 is connected to hot and cold water supply lines is in accordance with normal plumbing/connection techniques and, therefore, further description is not required for the purposes of the present invention.

The mixing device preferably has a single outlet through which water from the hot and cold water inlets, after having passed through a mixing chamber, can issue at a controlled temperature and flow rate.

As will hereinafter be described the water mixing device 10 is adjustable from a user interface 11 which may be separately positioned away from the mixing device 10. This is preferably achieved by the use of wireless transmission means, e.g. radio frequency transmission, from the user interface 11 to the electronic control of the mixing device 10. Thus the user interface 11 can be positioned "separately" from the plumbing of the mixing valve 10 and the water outlet to which it is connected whether this be a showerhead, faucet or the like.

Referring to Figures 1 and 2 the inlets for the cold and hot water are indicated by reference numerals 13a and 13b respectively. These are formed in the body 14 of the valve 10 and are connected to flow passages 15a and 15b which open into the SPECl774 OCTOBER 2005 n 6 floor 16 of a well 17. This so called well 17 is formed by a peripheral wall 18. An outlet flow passage 19 extends from the floor 1 6 of the well 1 7 to the outlet 20.

Located within the wefl 17 is a disk element 21 which in the preferred form of the invention is a ceramic disk. This sits in the well 17 and is held stationary by, for example, a pin (not shown) engaging in an opening 23 in the disk 21. One or more seals are provided (not shown) to seal the stationary ceramic disk in the well 1 7. The seals provide a seal between the interface of the disk 21 and the floor 16 and provide sealed connections between the flow passages 15-15b with corresponding openings 22a and 22b in the stationary disk 21. f v..

In face to face contact with the stationary disk 21 there is a moving disk 23. Once again in the preferred form of the invention this is a ceramic disk.

As will hereinafter be described the fluid circuit in the mixing device consists of the two inlets 13a and 13b, the flow passages 1 5a and 1 5b in communication with the inlet passages 22 and 22b in the stationary ceramic disk 21 apertures (hereinafter described) in the moving disk 23 a mixing chamber 24 and then back through the moving ceramic disk 23 to outlet passage 19 and the outlet 20. Depending on the position of moving disk 23 fluid passes through the disks 21 and 23 into the mixing ( ■ K chamber 24 where an even temperature profile is created then returns through the moving and stationary disks 23 and 21 to the outlet 20.

In the preferred form of the invention the outlet 20 passes to or has associated therewith a normally-closed solenoid valve 35 (Figure 6) which, as described later, provides for fail-safe operation.

The ceramic disks 21 and 23 and a liner 26 fit within the well 17 and are covered by a lid 27. Fitted to the lid 27 is a stepper motor 28. A motor shaft 29 extends from the stepper motor 28 to a connection with the moving ceramic disk 23. In the SPECl 774 OCTOBER 2005 7 illustrated form of the invention a squared end of the shaft 29 (which can be formed by a separate connector piece) engages in a square opening 30 in the centre of the moving ceramic disk 23.

The control means which includes an electronics control circuit is (see Figure 6) incorporated in a suitable waterproof enclosure located externally of the mixing device 10 and is connected to the stepper motor 28. The control circuit is arranged to control a motor drive circuit 34 of the stepper motor 28 and thereby control the output of the mixed water. The moveable ceramic disk 23 can be rotated through 360° by the stepper motor 28.

Extending through the thickness of the moving ceramic disk 23 are three sets of a plurality of apertures 31a-31c; 32a-32c and 33a-33c respectively as is shown in Figure 3. Each of the apertures in each of sets 31a-31c and 32a-32c extends for approximately 120° relative to the centre of the ceramic disk 23. Each of the three apertures in set 32a-32c represents a certain flow rate e.g. the smaller aperture providing 30% of maximum ftow, the intermediate sized aperture 60% of maximum flow and the third aperture represents maximum flow. The set of apertures 3Ia-31c and the set 32a-32c provide for cold and hot inlet flow respectively and the third set of equal sized apertures 33a-33c provide outlet flow.

Consequently, as the moving disk 23 is moved within the well 1 7, the relationship between the inlet apertures 31 a-31 c and 32-32c causes the ftow ratio between cold and hot water to be altered and thus effects temperature change in the mixed water in chamber 24. The hot and cold water thus passes through the ceramic disks 21 and 23 into the mixing chamber 24 where mixing in the mixing chamber ensures a uniform temperature before the water mixture exits to the outlet 20 via the apertures 33a-33c (as the case may be) and the stationary ceramic disk 21.

SPECl 774 OCTOBER 2005 8 The mixing chamber 24 is arranged to cavitate the water in the mixing chamber so that the hot and cold water is thoroughly mixed.

The stepper motor 28 can be a conventional four phase stepping motor with an angular positioning resolution of 0.8°. A separate home sensor 36 consisting of a photo-interrupter connected to the electronic control circuit ensures that the exact angular position of the shaft 29 can always be determined. In this way the setting of the moving disk 23 relative to the stationary disk 21 can always be known.

The electronic control circuit includes a microprocessor 37 which is suitably programmed to control the water mixing device 10.

The electronic control circuit receives inputs (by e.g. radio frequency signals) from the user interface 11 via antenna 38 and communications circuit 44. It also takes inputs from a number of sensors 39-42 including the home sensor 36 referred to above. These include temperature sensors 39 and 40 which control the outlet temperature.

In the preferred form of the invention there are two temperature sensors 39 and 40, one measuring the temperature of the flow at the hot inlet 13b and one at the outlet 20. The software of the microprocessor 37 monitors both temperature sensors 39 and 40 and operates two control loops designed to prevent temperature overshoot while maximising response time achieving a damp perfect closed loop control loop with superior accuracy to that of single control loop systems that are presently known. In this manner it is possible to control the temperature at the outlet of the mixing device to within 2°C.

The technique of measuring the hot inlet temperature as well as measuring water temperature passing through the outlet (which has been thoroughly mixed in the chamber 24) and using both measurements in separate feed back control systems SPEC 1774 OCTOBER 2005 9 provides for rapid response to changes with minimal overshoot. This, therefore, optimises the Nyquist stability criteria.

As previously mentioned a solenoid valve 35 can be associated with the outlet 20. This solenoid valve can be controlled by the electronic control circuit to provide a fail-safe operation. Thus, for example, in the event of the control system not being able to control the temperature of the flow to outlet 20 this will be sensed and upon being detected the solenoid valve 35 will move to its normally closed position so as to shut down the flow from the mixing device 10.

A watch dog action (via watch dog circuit 44) is obtained by the current driving the mixing device coming from a circuit which needs to be constantly pulsed by the software system, if the pulses are interrupted or stopped due, for example, to the software stopping because of disturbances, the current is interrupted and the solenoid valve 35 will close.

In the preferred form of the invention the electronic circuitry has power saving capability, where after pull-in, current is reduced to a maintaining value.

The user interface 11 can take on different forms but principally it will be constructed in a manner which is watertight so as to prevent water/moisture from entering into an area containing electronics and cause corrosion that may effect the operation of control elements. Thus, in a preferred form, the user interface 11 can include a housing 50 within which the electronics componentary can be located. Mounted on the housing 50 will be hinged or otherwise moveable panels or control elements 51 that are operatively coupled to microswitches or other switches/sensors within the housing.

Inside the housing there is contained an antenna and associated communication electronics circuiting which is in turn coupled to a microprocessor. The arrangement SPEC]774 OCTOBER 2005 is such that a user by manipulating the control elements 51 control the flow and temperature of water through the mixing device.

To achieve the waterproofing required the user interface housing is preferably covered by a membrane covering. This can be a transparent pre-printed silicon skin vacuum drawn over the interface unit.

As shown in Figure 4 the interface 1T can have two control elements 51a and 51 b for selecting control of temperature. One element 51a can be pressed for control of the hot water and the other 51b for control of the cold water. The other control elements 51c and 51d can be used for increase and decrease respectively of the temperature. The other two control elements function such as on/off 51 e and 51 f can be used to adjust flow.

Thus a user can, for example, push the hot button 51a and then push 51c to increase temperature or 51 d to decrease temperature. If flow rate is to be adjusted the other control elements 51 e and 51 f can be used to increase or decrease the flow rate.

A further form of user interface is shown at Figure 5. Like elements of construction carry the same reference numerals. In this version indicator lights 52 in the form of led's are located in the waisted position 53 of the housing 50. One bulbous end of the housing has control elements 51a and 51b while the other end has the control elements 51 for the additional functions.

A further sensor that can be connected to the electronic control circuit is sensor 41 adapted to sense a full vessel, such as a basin, tub, bath or the like. In such an arrangement the sensor 41 can be a capacitance sensor programmed to detect the level of water and act as a fill detector or an overflow sensor as required.

SPECl774 OCTOBER 2005 A further advantage of the water mixing device according to the present invention is that the electronic control circuit can also be programmed to time the period the mixing device allows water to flow. The user interface can be provided with means for adjusting this time period. This, for example, enables a caregiver to only allow a certain duration of water flow to take place.

The electronic control circuit can also incorporate a sound generating means 43, generally a chime, which can be programmed to alert users of situations, such as a pre-determined temperature being reached from a cold start, or a sink, tub or like vessel being full, or a fixed time having elapsed since flow commenced.

The power requirement for the electronic control circuit is, in the preferred form, provided by 12 volts. This wil! normally be provided by an economically plug pack which has the additional advantage of achieving safety certifications where local requirements dictate the use of safety extra low voltage.

The water mixing device according to the present invention enables, by way of the configuration and shape of the apertures in the disks and the use of only one moving disk permits control of flow rate and temperature with a minimum of moving parts and only one driving means (i.e. motor). This overcomes the complexity of known control mixing valves having two or more motors.

The radio frequency link between the user interface and the electronic control system provides for complete flexibility is to the physical location of the parts of the system i.e. user interface and mixing valve. This can also minimise installation costs and lead to elimination of problems of sealing cable entries and exits from wet areas.

The technique of measuring the hot inlet temperature and the temperature of the water passing from the outlet (i.e. water that has been thoroughly mixed in the SPEC 1774 OCTOBER 2005 12 chamber) enables for precise measurement allowing for rapid response to changes with minimal overshoot.

SPEC 1774 OCTOBER 2005 13

Claims (15)

WHAT WE CLAIM IS:-

1. A fluid control device for mixing of fluids the device being of a type having first and second inlets which can, in use, be respectively connected to first and second fluid supply lines, and an outlet for delivery of a resultant mixture at controlled parameters, the fluid control device including a stationary disk, a moveable disk in contact with the stationary disk, the moveable disk having a plurality of sets of apertures for flow through the disks of the first and second fluids to a mixing chamber and a set of plurality of apertures for flow of mixed fluid through the disks to said outlet, there being moving means for selective movement of the moveable disk to control the flow of fluid to regulate parameters thereof.

2. The device of claim 1 wherein the disks are of ceramic construction.

3. The device of claim 1 or 2 wherein each plurality of apertures for the first and second fluids provides three apertures each representing a certain flow rate there through.

4. The device of claim 3 wherein the three apertures respectively provide full flow, substantialiy 60% of full flow and substantially 30% of full flow.

5. The device of any one of claims 1 to 4 wherein the moving means is a stepper motor.

6. The device of claim 5 wherein the stepper motor is coupled to the moveable disk.

7. The device of claim 5 or 6 wherein the stepper motor is actuated by an electronic control means which is controlled remotely from a user interface. /f r , 5 JUL m \ 14

8. The device of claim 7 wherein the input from the user interface to the electronic control means is by wireless communication.

9. The device of claim 8 wherein the wireless communication is by radio frequency signals.

10. The device of any one of claims 7 to 9 wherein a position sensor is coupled to the electronic control means to sense the angular position of the moveable disk.

11. The device of claim 1 0 wherein the position sensor is a photo-interrupter.

12. The device of any one of claims 7 to 11 wherein a solenoid valve is provided with the outlet of the mixing device and is controllable by the electronic control means.

1 3. The device of any one of claims 1 to 1 2 wherein the first fluid is hot water and the second fluid is cold water.

14. The device of any one of claims 7 to 12 wherein the electronic control means is coupled to temperature sensors located to sense the temperature of the hot water and the temperature of the mixed water.

15. A fluid control device substantially as herein described with reference to the accompanying drawings. THE INNOVATION FACTORY LIMITED By its Attorney DON HOPKJNS & ASSOCIATES i PER: f]