IE940121A1

IE940121A1 - Mixer

Info

Publication number: IE940121A1
Application number: IE940121A
Authority: IE
Inventors: Martin Weaver; Iain Graham
Original assignee: Caradon Mira Ltd
Priority date: 1993-02-13
Filing date: 1994-02-09
Publication date: 1994-08-24
Also published as: GB2275097B; GB2275097A; GB9302917D0; GB9402273D0

Abstract

A valve for mixing hot and cold water, particularly in a shower unit, has a shuttle valve 1 controlling the relative proportions of admixed hot and cold water that is adjustable by change in length of an actuator rod 25 of a wax filled thermostat 17 to maintain constant a selected water temperature above a pre-determined value in a thermostatic mode of operation, with the actuator rod 25 being isolated for adjustable selection of water temperature below the pre-determined value in a non-thermostatic mode of operation. Changeover between the non-thermostatic and thermostatic modes of operation is provided by a cap member 34 arranged to move axially and so transmit angular adjustment of a temperature control spindle 26 to either the thermostat body 17 in the non-thermostatic mode or the actuator rod 25 in the thermostatic mode of operation, when the rod is extended with rise in temperature above the predetermined value.

Description

This invention rela 940121 . mixer APPLICATION No..................···—· es to mixers for water supply installations, particularly but not exclusively, for mixing hot and cold water for ablutionary showers for domestic applications.

It is already known to provide mixers with a thermostat that is 5 responsive to the water temperature in a mixing chamber to adjust a valve controlling the relative proportions of hot and cold water admitted to the mixing chamber so as to maintain substantially constant a selected water temperature.

With this arrangement, changes in the temperature and/or pressure of 10 one or both water supplies are automatically compensated by adjustment of the valve to avoid any sudden unexpected change in the water temperature.

Typically the user rotates a temperature control member such as a knob or lever to adjust the valve until the desired water temperature is obtained and any variation in the selected temperature is compensated by the thermostat.

It is desirable for smooth selection of temperature over a range sensitive to the user that small changes in the angular position of the control member do not produce large changes in the selected water temperature which the user may not expect.

This restricts the temperature range which can be obtained for a given angular adjustment of the control member without adversely affecting the sensitivity of the water temperature to rotation of the control member.

The present invention has been made from a consideration of this problem.

According to the present invention there is provided a mixer for a water supply installation comprising valve means for controlling admixture of hot and cold water in accordance with adjustable selection of the mixed water temperature wherein the valve means is thermostatically controlled for selection of mixed water temperatures above a predetermined value and non-thermostatically controlled for selection of mixed water temperatures below the predetermined value.

Advantageously, the mixed water temperature is selected by rotation of control means with the angular adjustment per unit temperature change being higher for the thermostatic control of the valve than for the non35 thermostatic control of the valve. In this way, the temperature range may be OPEN T0 Pu; v JPECTION It v ·-> SECTION 2d RULE 23 JNL. .940121 increased without affecting adversely the sensitivity of the valve to angular adjustment of the control means at higher temperatures.

Preferably, the angular adjustment of the control means per unit temperature change in the thermostatic mode is at least twice that in the non-thermostatic mode. For example, the angular adjustment of the control means per unit temperature change may be approximately 12° in the thermostatic mode and approximately 4° in the non-thermostatic mode.

Advantageously, the control means is operably connected to a thermostat associated with the valve means for adjustable selection of the water temperature in the non-thermostatic and thermostatic modes.

Preferably, thermostatic control is provided by response of the thermostat to the water temperature and non-thermostatic control is provided by isolating response of the thermostat to the water temperature.

The thermostat conveniently comprises a hollow body filled with a thermally responsive material that acts on actuator means for adjusting the axial length thereof in response to the water temperature for adjusting the valve means to maintain constant a selected water temperature in the thermostatic mode of operation with the actuator means being isolated in the non-thermostatic mode of operation.

Preferably, the valve means is operatively associated with the thermostat body, and angular adjustment of the control means is transmitted to either the thermostat body for adjusting the valve means in the nonthermostatic mode or the actuator means for adjusting the valve means in the thermostatic mode.

Advantageously, coupling means is provided for selectively transmitting angular adjustment of the control means to the actuator means in the thermostatic mode and to the thermostat body by-passing the actuator means in the non-thermostatic mode.

The valve means may comprise a shuttle valve supported on the thermostat body for axial movement between opposed hot and cold seats associated respectively with hot and cold water inlet chambers for controlling the relative proportions of admixed hot and cold water, and the shuttle valve is preferably biased by an overload spring retained by a collar or sleeve associated with the thermostat body and providing a seating for the coupling means in the non-thermostatic mode. ι i f t94 0 1? 1 Advantageously, the coupling means includes a cap member that seats on the collar in the non-thermostatic mode and is lifted clear of the collar by engagement with the actuator means in the thermostatic mode. For example, the actuator means may comprise a rod or piston arranged coaxially within the collar.

Preferably, the cap member is engaged by a grub screw arranged for axial movement in response to angular adjustment of the control means for adjustable selection of the water temperature, and the grub screw is conveniently adjustable for setting the maximum water temperature.

Advantageously, the thermostat is supported by an axially movable flow guide arranged coaxially with the shuttle valve for directing water flow over the thermostat body and communicating with an outlet for connection to an ablutionary appliance, and the flow guide is preferably biased by a return spring in opposition to the overload spring for maintaining engagement between the coupling means and either the thermostat body or the actuator means.

Other features, benefits and advantages of the invention will be understood from the following description of an exemplary embodiment with reference to the drawings, wherein:FIGURE 1 is a part sectional view of a mixer embodying the invention shown in the non-thermostatic mode; FIGURE 2 is a part sectional view similar to Figure 1 showing the mixer in the thermostatic mode; FIGURE 3 is a part sectional view similar to Figures 1 and 2 showing the transition of the mixer between the thermostatic and non-thermostatic modes; FIGURE 4 is a part sectional view similar to Figures 1,2 and 3 showing the mixer in a temperature overshoot condition; and FIGURE 5 is a graph showing the temperature change with rotation of the control member in the non-thermostatic and thermostatic modes.

With reference to Figures 1 to 4 of the drawings, a hollow cylindrical shuttle valve 1 is shown mounted in a counterbore 2 at one end of a tubular portion 3 of a hollow mixer body 4.

The counterbore 2 terminates in an internal shoulder providing a hot seat 5 for one end of the shuttle valve 1. An opposed cold seat 6 for the other end of the shuttle valve 1 is provided by an internal flange of a member 7 secured to the mixer body 4 and sealed by an O-ring 8.

The shuttle valve 1 is sealed intermediate its ends by an external Oring 9 separating inlet chambers 10,11 communicating with respective inlets (not shown) for hot and cold water and is axially movable between the opposed seats 5,6 for controlling admixture of hot and cold water in nonthermostatic and thermostatic modes of operation described later herein.

The shuttle valve 1 has an internal vented support 12 which seats on one side of an external flange 13 intermediate the ends of a wax filled thermostat 14 under the biasing of an overload spring 15 retained by a collar or sleeve 16 screwed to the thermostat body 17.

A tubular flow guide 18 is slidably mounted in the other end of the tubular portion 3 of the mixer body 4 coaxial with the shuttle valve 1 and seats against the other side of the flange 13 under the biasing of a return spring 19 in opposition to the overload spring 15.

The flow guide 18 is arranged to direct water flow from the inlet chambers 10,11 over a temperature responsive end section 20 of the thermostat 14, and the ratings of the springs 15,19 is such that the shuttle valve 1 and thermostat body 17 are coupled for movement of the shuttle valve 1 between the valve seats 5,6 and uncoupled for additional movement of the thermostat body 17 under temperature overshoot conditions when the shuttle valve 1 engages the hot water seat 6 as shown in Figure 4 to prevent the mechanism being damaged.

The flow guide opens to an outlet chamber 21 provided by a bonnet member 22 secured to the mixer body 4 and sealed by an O-ring 23, and the outlet chamber 21 communicates with an outlet 24 from the mixer body 4 for connection to an ablutionary appliance such as a shower (not shown).

A cylindrical actuator rod 25 is slidably mounted in the other end of the thermostat 14 and change in volume of the wax filler in response to temperature change of the mixed water is transmitted to the actuator rod 25 for adjusting the projecting length thereof.

A rotatable temperature control spindle 26 has an external axial spline formation 27 at one end for mounting a temperature control member (not shown) such as a knob or lever for adjustable selection of the mixed water temperature. Separate flow control means (not shown) such as a ceramic tap mechanism operable by a flow control member is provided 94012 1 4 s upstream or downstream of the shuttle valve for on/off and adjustable selection of flow rate. The flow and temperature control members may be arranged for concentric control of flow and temperature.

The other end of the spindle 26 is formed with an internally threaded counterbore 28 threadably engaged by a drive nut 29 slidably mounted on a hexagonal upstand 30 of cold seat member 7 such that drive nut 29 is located against rotation and is caused to move axially on rotation of the control spindle 26.

The drive nut 29 is provided with a grub screw 31 having a smooth cylindrical extension 32 at the inner end that is sealed relative to the cold seat member 7 by a pair of O-rings 33 and engages a cap member 34 of inverted cup-shape to transmit selectively axial movement of the drive nut 29 on rotation of the control spindle 26 to the thermostat body 17 or actuator rod 25 in non-thermostatic and thermostatic modes of operation described later herein.

The other end of the grub screw 31 is accessible from the outer end of the spindle 26 via a through bore 35 opening to the counterbore 28 for adjusting axially the position of the grub screw 31 during manufacture and/or on site during installation to pre-set the maximum water temperature that can be selected.

The grub screw 31 has an external collar 36 to limit the range of adjustment inwards to prevent the mechanism being overloaded and outwards to prevent a water leak by engagement with the drive nut 29 and an internal shoulder 37 of the bore 35 respectively.

In operation of the mixer above-described, the cap member 34 seats on the collar 16 when the sensed water temperature is less than a predetermined value as shown in Figure 1, and is raised clear of the collar 16 by engagement with the actuator rod 29 when the sensed water temperature exceeds the predetermined temperature as shown in Figure 2.

Thus, for selection of water temperatures from full cold up to the predetermined temperature, axial movement of the drive nut 29 on rotation of the control spindle 26 is transmitted via the grub screw 31 and cap member 27 directly to the thermostat body 17 for adjusting the position of the shuttle valve 1 to control the relative proportions of hot and cold water flowing over the temperature responsive end section 20 of the thermostat 14. 4 0 1 2 1 '' As a result, the actuator rod 25 is effectively isolated so that change in length thereof caused by expansion/contraction of the wax filler in response to the sensed water temperature does not alter the position of the shuttle valve 1. That is to say, the shuttle valve 1 is non-thermostatically controlled and the water temperature may vary from that selected due to changes in the temperature and/or pressure of one or both supplies.

For selection of water temperatures above the pre-determined temperature, axial movement of the drive nut 29 on rotation of the control spindle 26 is transmitted indirectly to the thermostat body 17 via the grub screw 31, cap member 34 and actuator rod 25 for adjusting the position of the shuttle valve 1 to control the relative proportions of hot and cold water flowing over the temperature responsive end of the thermostat.

As a result, the actuator rod 25 is live so that change in length thereof caused by expansion/contraction of the wax filler in response to the sensed water temperature causes the shuttle valve 1 to move to alter the relative proportions of admixed hot and cold water. That is to say the shuttle valve 1 is thermostatically controlled to adjust automatically to maintain constant the selected water temperature.

The changeover between the non-thermostatic and thermostatic modes of operation at the pre-determined temperature is shown in Figure 3 where the cap member 34 is seated on the collar 16 and is engaged by the actuator rod 25. The temperature at which the actuator rod 25 engages the cap member 34 can be altered to provide any desired transition between the non-thermostatic and thermostatic modes of operation by selection and fitment of cap members 34 of different depth d.

Under temperature overshoot conditions, the increase in length of the actuator rod 25 in response to expansion of the wax filler causes the shuttle valve 1 to engage the hot seat 6 to shut-off hot water flow and the ratings of the springs 15,19 is such that the shuttle valve 1 and thermostat body 17 are uncoupled to allow further travel of the thermostat body 17 and flow guide 18 as shown in Figure 4 to prevent the mechanism being damaged.

By this invention, the range of water temperatures that can be selected for a given angular adjustment of the control member can be increased as compared with a fully thermostatically controlled mixer by arranging that the angular adjustment of the control member to obtain a unit temperature change for non-thermostatic selection of the water temperature ! 940121 is substantially lower than that for thermostatic selection of the water temperature. Furthermore, such increased temperature range is obtained without adversely affecting smooth temperature selection at the higher thermostatically controlled water temperatures sensitive to the user.

Thus, as shown in Figure 5, for total angular adjustment of the control member through 270°, the first 130° of rotation provides non-thermostatic selection of water temperature from 5°C to 35°C corresponding to angular adjustment of the control member of approximately 4° per unit temperature change, and the remaining 140° of rotation provides thermostatic selection of water temperature from 35°C to 47° corresponding to angular adjustment of the control member of approximately 12° per unit temperature change.

In comparison, the minimum extrapolated water temperature that can be selected in a fully thermostatically controlled mixer having the same 12° angular adjustment per unit temperature change is 25°C as shown by the broken line in Figure 5.

It will be understood that the invention is not limited to the embodiment above-described and that the concept of changing over between non-thermostatic and thermostatic control may be employed in other types of mixer in which a thermostat having a length adjustable actuator is employed to control a proportioning valve for hot and cold water.

Furthermore, for a given thermostat the cap member may be chosen to provide any desired changeover temperature between non-thermostatic and thermostatic control of the shuttle valve.

Alternatively or additionally, the response of the length adjustable actuator may be adapted to provide any desired transition temperature between non-thermostatic and thermostatic modes of operation.

Also, the angular movement of the control knob per unit temperature change in the non-thermostatic and/or thermostatic modes may be altered as desired as may the total angular movement of the control knob.

Claims

1 9 4 0 1 2 1 18. A mixer according to any one of the preceding Claims including flow control means arranged for separate control of flow rate. 19. A mixer for a water supply installation substantially as hereinbefore described with reference to the accompanying drawings.

1. A mixer for a water supply installation comprises valve means for controlling admixture of hot and cold water in accordance with adjustable selection of the mixed water temperature wherein the valve means is thermostatically controlled for selection of mixed water temperatures above a predetermined value and non-thermostatically controlled for selection of mixed water temperatures below the predetermined value.

2. A mixer according to Claim 1 including rotatable control means for adjustable selection of the water temperature with angular adjustment of the control means per unit temperature change in the thermostatic mode being greater than in the non-thermostatic mode.

3. A mixer according to Claim 2 wherein the angular adjustment of the control means per unit temperature change in the thermostatic mode is at least twice that in the non-thermostatic mode.

4. A mixer according to Claim 2 or Claim 3 wherein the angular adjustment of the control means per unit temperature change is approximately 12° in the thermostatic mode and approximately 4° in the nonthermostatic mode. 5. A mixer according to any one of Claims 2 to 4 wherein the control means is operably connected to a thermostat associated with the valve means for adjustable selection of the water temperature in the nonthermostatic and thermostatic modes. 6. A mixer according to Claim 5 wherein thermostatic control is provided by response of the thermostat to the water temperature and non-thermostatic control is provided by isolating response of the thermostat to the water temperature. 7. A mixer according to Claim 5 or Claim 6 wherein the thermostat comprises a hollow body filled with a thermally responsive material that acts on actuator means for adjusting the axial length thereof in response to the water temperature for adjusting the valve means to maintain constant a selected water temperature in the thermostatic mode of operation with the actuator means being isolated in the non-thermostatic mode of operation. 8. A mixer according to Claim 7 wherein the valve means is operatively associated with the thermostat body, and angular adjustment of the control means is transmitted to either the thermostat body for adjusting the valve means in the non-thermostatic mode or the actuator means for adjusting the valve means in the thermostatic mode. 9. A mixer according to Claim 8 including coupling means for selectively transmitting angular adjustment of the control means to the actuator means in the thermostatic mode and to the thermostat body bypassing the actuator means in the non-thermostatic mode. 10. A mixer according to Claim 9 wherein the valve means comprises a shuttle valve supported on the thermostat body for axial movement between opposed hot and cold seats associated respectively with hot and cold water inlet chambers. 11. A mixer according to Claim 10 wherein the shuttle valve is biased by an overload spring retained by a collar or sleeve associated with the thermostat body and providing a seating for the coupling means in the nonthermostatic mode. 12. A mixer according to Claim 11 wherein the coupling means includes a cap member that seats on the collar in the non-thermostatic mode and is lifted clear of the collar by engagement with the actuator means in the thermostatic mode. 13. A mixer according to Claim 12 wherein the actuator means comprises a rod or piston arranged coaxially within the collar. 14. A mixer according to Claim 12 or Claim 13 wherein the cap member is engaged by a grub screw arranged for axial movement in response to angular adjustment of the control means for adjustable selection of the water temperature. 15. A mixer according to Claim 14 wherein the grub screw is adjustable for setting the maximum water temperature. 16. A mixer according to any one of Claims 11 to 15 wherein the thermostat body is supported by an axially movable flow guide arranged coaxially with the shuttle valve for directing water flow over the thermostat body and communicating with an outlet for connection to an ablutionary appliance. 17. A mixer according to Claim 16 wherein the flow guide is biased by a return spring in opposition to the overload spring for maintaining engagement between the coupling means and either the thermostat body or the actuator means.

5. 20. A water supply installation including a mixer according to any one of the preceding Claims.