WO2010112868A1

WO2010112868A1 - Thermostatic control device for burning gas appliances

Info

Publication number: WO2010112868A1
Application number: PCT/GB2010/000659
Authority: WO
Inventors: Scott Michael Allen
Original assignee: Diamond H Controls Limited
Priority date: 2009-04-01
Filing date: 2010-04-01
Publication date: 2010-10-07
Also published as: GB2469091A; GB0905642D0

Abstract

A thermostatic control device (100) for the regulation of gas flow within a gas appliance comprises a cylindrical plug (110) axially moveable within a gas flow bore to provide at least ON/OFF gas flow control between a gas inlet (115) and a main outlet (152) and a supplementary outlet (142). Thermal regulation of the main outlet is provided by a diaphragm actuated valve (109) adjustable by rotation of the cylindrical plug (110). Regulation of the supplementary outlet (142) is provided by control flats (137) disposed on the cylindrical plug (110) which is again rotated to bring control flats (137) into and out of proximity to the supplementary outlet (142).

Description

THERMOSTATIC CONTROL DEVICE FOR BURNING GAS APPLIANCES

Field of the Invention

The present invention relates to thermostatic control devices, particularly thermostatic temperature control devices for domestic gas appliances. The invention more particularly relates to thermally operated gas valves which include a temperature-sensing probe coupled to a bellows or diaphragm, the movement of which urges a valve actuator into and out of a sealed position with respect to a valve seat to regulate the flow of gas to an outlet, thereby regulating the operating temperature of gas appliances, particularly domestic gas appliances such as cookers, heating systems and boilers, gas fires and the like.

Background to the Invention

There are a number of thermally operated gas valves commercially available, however, in the field of thermal control of domestic heating systems or boilers and cooking appliances, a familiar type of control is traditionally used. Such controls have a rotatable spindle for setting the operational temperature and a temperature sensor within or adjacent the boiler, oven or like appliance. The temperature sensor comprises a phial of expansible fluid which communicates with a sealed unit located within the body of the control device via a capillary system, the sealed unit comprising a diaphragm connected to an actuator. Normally, the actuator comprises or is connected to a valve disc adapted to sealingly engage a valve seat defining an aperture and to prevent gas flow therethrough. Temperature changes sensed by the phial produce a change in the volume of the filling liquid or a pressure change in the filling gas or vapour. These expansion movements are communicated via the capillary system to the diaphragm where they are converted to a linear movement within the body of the control device causing the valve disc to move into and out of proximity to the valve seat.

It will be understood by the skilled addressee that a reference to a temperature sensor or probe is intended to include other comparable means for effecting a temperature dependent linear movement at a diaphragm or equivalent means known in the ait. In the description which follows, reference to a hydraulic or fluid filled temperature sensor is not intended to be in any way limiting or to exclude other systems capable of effecting temperature dependent linear movement.

Exemplifying of prior art thermostatic control devices is a thermally operated gas valve such as that produced by the present Applicant (Diamond H Controls Limited, 1100 Series gas thermostat controls). As described in more detail hereinbelow, the controls provide an "ON/OFF" function by locating a cylindrical machined brass plug within the main gas flow bore of the control housing and moving the plug into and out of sealing engagement with a series of O-ring seals located in the wall of the bore. The function of controlling appliance temperature, for example, oven or grill temperature is achieved by using a modulating valve disc that moves into an out of proximity to a valve seat face in the body of the control housing the movement of which being controlled by a diaphragm disc which is connected via the capillary system to the temperature sensing probe located within an oven cavity, for example.

The above arrangement is reliable but has perceived limitations, particularly in respect of being adaptable to regulate or control more than one gas output, for example, both oven and grill gas outputs or to provide a flame supervision feature which would shut off the gas flow to a burner in the event of the flame being extinguished. Further exemplifying of the prior art are thermally operated gas valves of the type described in detail hereinbelow having an ON/OFF function again operated via a spindle but connected to a tapered machined plug within the main gas flow path which must also be tapered to correspond to the curved surface of the tapered plug. To provide the ON/OFF function gas flow paths are machined into the plug which when rotated into alignment with inlet and outlet paths formed in the body, allow gas to flow through the control. When a plain curved surface region is rotated into alignment with the gas inlet path, gas flow is prevented by the sealing interface of plug and bore. It will be appreciated that to effect such a seal, the metal surfaces must be finished to a very fine smoothness and that the angles of plug and bore must be perfectly matched to provide the required metal-to-metal gas seal.

Although the above arrangement allows for adaptation for a second gas outlet path, the machinery of the plug and corresponding bore using materials which allow for fine and enduring surfaces means that the components are relatively expensive and are not tolerant of imperfections in less expensive materials.

As with all control devices, size of the housing and available space within appliance is always as consideration and both of the prior art controls referred to generally above have disadvantages associated with size compared to functionality, component count, adaptability and cost which are apparent to those skilled in the art.

Calibration of sensors due to manufacturing inconsistencies, the sensitivity of known sensors and the components to which they are connected also increase the end costs to the user. Devices which are self-calibrating or those which are manufactured to have specific fixed response characteristics are desirous but often unrealisable. Most typically, calibration of the thermostatic control is made either via a calibration screw on the diaphragm actuator or at the point where the capillary system interfaces with the control housing. It is an object of the present invention to seek to alleviate the disadvantages associated with such prior art thermostatic control devices and to provide an improved thermostatic control device for gas appliances.

It is a particular object of the invention to provide improved ON/OFF reliability and to provide improved functionality using non-tapered components.

It is a further object of the invention to provide a thermostatic gas control device having improved functionality and adaptability with reduced overall component count for improved reliability and decreased cost.

It is a yet further object of the present invention to provide a thermostatic control device having flame supervision function which shuts off gas flow in the event of a flame being extinguished.

Summary of the Invention

Accordingly, the present invention provides a thermostatic control device for the regulation of gas flow to a gas appliance, the device comprising:

a housing;

a resiliency deformable member in operable connection to a temperature sensor;

a valve actuator moveable under the influence of the deformable member in response to temperature changes at the sensor;

a profiled plug member rotatably and axially moveable within a gas flow bore within the housing, the gas flow bore including inlet and outlet ports in the curved walls thereof; and

a rotatable user control spindle in communication with and adapted to move the plug member within the bore, wherein the plug member and the gas flow bore are profiled to define gas flow paths between inlet and outlet ports and wherein the plug member comprises a cylindrical body adapted sealingly and slideably to fit within the gas flow bore so as to direct gas from an inlet port to one of a plurality of outlet ports.

The plug member includes a ramped or helical groove which is engaged by a fixed pin within the bore to effect axial movement upon rotation of the spindle.

The groove is profiled and the plug positioned within the bore so that the OFF position corresponds to the mid-point in the range of axial movement of the plug so that anti-clockwise rotation of the spindle causes axial movement of the plug in one direction and clockwise rotation of the spindle causes axial movement in the opposite direction, from the central or mid-point OFF position, to provide two discrete ranges of control and a second controlled gas outlet.

Advantageously, the cylindrical plug member includes retaining lands for a plurality of O-rings seals, the seals engaging the curved walls of the bore to define said gas flow paths.

Conveniently, the plug includes a plurality of flow control flats to provide regulation of gas flow upon rotation of the user control spindle to a second controlled gas outlet.

The plug is a profiled cylindrical element upon which there is formed lands for 0- rings, flow control flats and the groove to effect axial movement. By selecting a cylindrical element and using a plurality of O-ring seals engaging with the gas flow bore to form the gas paths, the perceived disadvantages of prior art arrangements, including particularly the disadvantages associated with the tapered plug element valve construction and the manufacturing tolerances required, are substantially eliminated.

At one end, the plug element is driven by the spindle which engages a keyed receiver in the plug member. Advantageously, the keyed receiver is adapted to receive slidingly a shaped end of the spindle so that axial movement of the plug member is not transmitted to the spindle.

This arrangement is particularly preferred by appliance designers and users as it eliminates the axial movement of a spindle-mounted control knob to and from a mounting plate or face as the control knob is rotated which normally results in a visible gap between the knob and the mounting plate or face.

At the opposite end of plug element, a lead screw, engaged in a keyed receiver of the plug element, is slidingly received therein to eliminate the axial movement of the plug element, thereby isolating the diaphragm actuator from the axial movement of the plug member which otherwise would be transmitted through the lead screw.

Conveniently, the resiliently deformable member comprises a diaphragm having a profiled diaphragm head adapted to engage the lead screw.

In a preferred arrangement, the lead screw has an externally threaded end which mates with an internally threaded cylindrical portion of the diaphragm head, so that the axial position of the lead screw is determined by the depth of threaded reception within said threaded portion of the diaphragm head.

Advantageously, the depth of threaded reception of the lead screw within the diaphragm head is determined by the rotational adjustment of the user control spindle.

The above arrangement facilitates temperature regulation whereby the degree of deformation of the diaphragm required to move the valve actuator to close the outlet valve and thereby shut off primary gas flow to the burner is user settable.

Advantageously, calibration of the device is achieved by adjusting the depth of engagement between the lead screw and the diaphragm head, thereby eliminating the need for a conventional calibration screw mechanism. User settings are selected by means of a control knob secured on the control spindle to which a stop pin is fixed, the stop pin abutting a control surface in the housing to limit rotation of the control spindle.

Ideally, a first range of control is from 0 to 230 degrees in one direction of rotation and a second range of control is from 0 to 60 degrees in the opposite direction.

Brief Description of the Drawings

The invention will now be described more particularly with reference to the accompanying drawings which show, by way of example only, one embodiment of thermostatic control device in accordance with the invention. In the drawings:

Figures Ia and Ib are a sectional side elevation and a part-sectioned end elevation of a prior art thermostatic gas valve with temperature sensor;

Figures 2a to 2c are first and second side elevations of a plug element for locating within the main gas flow bore of the gas valve of Figures Ia and Ib and a schematic representation of a ramped or helical groove cut into the plug element to facilitate axial movement of the plug within the bore, respectively;

Figures 3a and 3b are a sectional side elevation of a further prior art thermostatic gas valve having a tapered conical main gas flow bore and corresponding tapered plug having a gas flow path machined into the curved surface thereof;

Figure 4 is a sectional side elevation of a theπnostatic gas valve in accordance with the invention;

Figures 5a to 5c are sequential rotated side views of a cylindrical plug adapted to fit sealingly within a main gas flow bore of the gas valve of Figure 4;

Figure 6 is a detailed sectional view of the cylindrical plug positioned within the main gas flow bore illustrating surface interaction and sealing O-rings; Figure 7 is a detailed sectional view of the diaphragm, diaphragm actuator, lead screw and thermostatically operated valve of the gas valve of Figure 4;

Figure 8 is a sectional side elevation of the valve in a closed or "OFF" position;

Figure 9 is a sectional side elevation of the valve in a first open position, also referred to hereinafter as the "OVEN ON" position, and

Figure 10 is a sectional side elevation of the valve in a second open position, also referred to hereinafter as the "GRILL ON" position.

Detailed Description of Preferred Embodiments

Referring to the drawings and initially to Figures Ia and Ib and Figures 2a to 2c, a device currently marketed by the present Applicant is representative of the prior ait and shows a thermostatic gas valve control device generally denoted 10, which comprises a main housing 11 within which there is defined a main gas flow bore connecting a gas inlet 12 to a controlled gas outlet 13. Control of the gas flow is effected firstly by a machined plug 15 and secondly by a regulating valve disc 18. The valve disc 18 is moved into and out of engagement with a valve seat under the influence of a diaphragm assembly 20. The diaphragm assembly 20 comprises a diaphragm 22 in sealed communication with a thermal sensor 24 which include a phial of expansible fluid, such as hydraulic liquid known in the art. The liquid is constrained within a capillary system so that thermal expansion of the hydraulic liquid is converted to movement at the valve disc through the diaphragm 22 and diaphragm actuator.

In the upper part of the housing 11, a first gas flow bore 27 is provided and allows gas to flow from the inlet port 12 towards a second gas flow bore 28 of smaller internal diameter to that of the first. The second bore 28 leads to an outlet chamber 30 from which a gas outlet path leads to the outlet port 13. Defined between the second bore and the chamber is the valve seat against which the valve disc 18 is operably biased. The valve control is provided by locating a machined brass plug 15, as illustrated more particularly in Figures 2a and 2b, which has a profile corresponding to the first 27 and second 28 gas flow bores. The plug 15 has a first larger diameter section which includes a keyed receiver 32 for engaging a user control spindle 35 (as shown in Figures Ia and Ib) and a second smaller diameter section which also has a keyed receiver 37 for engaging with a lead screw 39 forming part of the valve/diaphragm actuator. The plug 15 is fitted with two rubber O-ring seals 41,42 retained in lands formed within the curved surface of the first and second sections. The upper seal 41 prevents gas escaping past the plug, leading to atmosphere, and the lower O-ring 42 forms a seal with the second gas flow bore

28, that is, the smaller diameter section of the main gas path bore, preventing gas flow to the outlet 13.

The brass plug 15 has a ramped groove 45 machined into the larger diameter section between the upper seal 41 and the transition from the larger diameter section to the smaller diameter section. The groove 45 is engaged by a fixed pin

(not shown) secured within the valve body. To turn the gas flow ON, the plug 15 is rotated anti-clockwise via the user control spindle 35. As the plug is rotated, it is driven upwardly in the axial direction to the full extent allowable by the profile of the ramp in the groove 45, which is illustrated in Figure 2c, so that the plug lifts from an "OFF" position, where a gas flow seal O-ring 37 of the plug sealingly engages the second bore 28, to an "ON" position where the lower part of the plug lifts from the second bore 28 and gas can flow from the gas inlet 12 towards the outlet chamber 30.

Within 55° of rotation, the plug 15 moves its full axial extent and the lower seal 41 is extracted from the smaller diameter section of the gas path bore, thus breaking the seal and allowing the gas to flow into the outlet chamber 30 and on to the outlet port 13. Turning the spindle 35 clockwise, towards the OFF position, rotates the plug 15 and causes it to move downwardly with respect to the fixed pin located in the groove 45. The lower O-ring 41 is forced back into the second gas flow bore 28 thereby blocking the gas path to the outlet port 13.

The temperature control of the appliance, for example, the temperature required in an oven cavity, is achieved by using a modulating valve disc 18 that moves towards or away from a valve seat at the interface between the smaller diameter section of the main gas flow bore and the outlet chamber 30. The movement of this disc 18 and its proximity to the valve seat regulates the flow of gas allowed to pass through the outlet port 13 and on to a gas burner, thereby controlling the heat output of the burner. The valve disc movement is controlled by the diaphragm 22 which is connected via the capillary system to the temperature sensing probe 24, normally located within the oven cavity. Expansion of hydraulic fluid within the temperature probe is translated into movement of the diaphragm 22, which moves the valve disc 18. To select the required oven cavity temperature, the user spindle

35 is rotated to the appropriate angle or user setting. This rotation is transferred via the plug 15 to the lead screw 39 onto which the valve disc 18 is mounted. By rotating the lead screw 39, the proximity of the valve disc 18 to the valve seat can be set, allowing gas to flow to the burner. When the temperature in the cavity increases, the hydraulic fluid (usually oil) in the temperature probe 24 expands, moving the diaphragm and bringing the valve disc into closer proximity to the valve seat thereby reducing the gas flow to the burner and regulating its output. If the temperature within the cavity fall, the oil contracts and the diaphragm will move in the opposite direction, increasing the gap between valve disc and valve seat, allowing more gas to flow and increasing once more the output of the burner to maintain oven cavity temperature.

The relationship between the expansion rate of the oil and the pitch of the lead screw thread defines the size of the temperature range that can be controlled over the allowed rotation of the spindle 35. The initial position of the lead screw is set in a calibration process to define a spindle angle at a given temperature.

Another known thermostatic control device generally denoted 50 and representative of the prior art is illustrated in Figures 3a and 3b. This device uses the same regulation mechanism as described above in that a cavity located temperature sensor 54 is coupled to a diaphragm 55 via a capillary system 56 to move a valve disc 58 into and out of proximity with a valve seat to regulate gas flow to an oven outlet 60 feeding a burner in the oven cavity. The control device 50 has three housing sections secured together in sealing connection. The top section 62 engages a user control spindle 65 and includes a biasing spring to retain a tapered plug 70 within a centre section 72 of the housing which has a gas inlet (not shown) and a supplementary gas outlet 74. A bottom section 75 of the housing retains the diaphragm assembly, valve disc 58 and the capillary system 56 and defines the main gas outlet 60. The mechanism used to provide ON/OFF control is realised using the tapered plug 70 located in a corresponding tapered main gas flow bore within the centre section 72 of the housing. The surface of the tapered bore and the tapered plug are highly finished and must have perfectly matched taper angles, necessitating the use of high grade materials such a polished brass or extruded aluminium, rather than die-cast aluminium such as that used for the top 62 and bottom 75 sections. The plug 70 is held in the bore by the biasing spring to form a metal to metal gas seal. The rotary movement of the plug is effected by rotating the user spindle 65 which engage a spindle drive 77 cut into the plug. No axial (linear) movement of the plug is allowed, as to do so would affect the gas seal. Gas flow paths 78 are cut into the curved surface 79 of the plug 70 so that when the plug is rotated, a slot or hole aligns with an inlet port and an outlet path allowing gas to flow, thereby creating an ON position. A slotted lead screw drive 80, similar in profile to that of the spindle drive 77, is provided at the lower end of the plug 70 to isolate axial movement of a lead screw 81.

When the plug is rotated so that a plain curved surface of the plug aligns with the inlet port, the gas flow is sealed OFF. By providing multiple outlets and corresponding gas paths 78 in the plug, ON/OFF control to multiple burners is facilitated and an element of regulation of gas flow to the supplementary gas outlet representing, for example a grill outlet 74, can be incorporated by vaiying the area of alignment between the gas path slot 78 and the inlet path 74 or the outlet path as the plug is rotated.

Referring now to Figures 4 to 10 and particularly to Figure 4, a preferred embodiment of the thermostatic control device of the invention, generally denoted 100 comprises a housing having a bottom section 104 defining a regulated gas outlet for an oven; a middle section 105, defining a gas inlet; and a top section

106, defining a supplementary gas outlet for a grill. The device 100 has multiple gas paths and includes a diaphragm assembly 108 for actuating a regulating valve 109, a profiled plug member 110 rotatably and axially moveable within a gas flow bore within the housing and a rotatable user control spindle 112 in communication with and adapted to move the plug member 110 within the bore. The bore includes gas flow apertures and slots to define paths in the curved wall thereof to facilitate flow of gas from a single gas inlet port 115 to a plurality of gas outlets.

Movement of the plug member, together with grooves, lands and control flats provided thereon, define the gas flow paths between the inlet and outlet ports.

The series of gas thermostats made available by the present embodiment of the invention provides additional functionality in comparison to the Applicant's prior art gas thermostats and allows for standard manufacturing tolerances rather than the high tolerances necessary for the tapered plug arrangements. In addition to the ON/OFF functions and the temperature controlled gas flow modulation as described above, variants of the present embodiment also provide ON/OFF control function and flow regulation for a second gas outlet, for example, a grill burner. The design also incorporates the option of an integral flame supervision device which will shut off the gas flow to the burner in the event of the flame being extinguished. Flame supervision is effected by placing a magnet unit valve 120 within the inlet gas flow path and maintaining this in an open position via a magnet unit actuating pin 122 under the influence of an actuating lever 124. Theπnocouples monitoring the presence of a flame at the oven and grill burners connect to the control device 100 via corresponding receivers 125.

The range of thermostatic gas flow control devices encompass the following variations:

1. Oven thermostat with controlled grill outlet and flame supervision for two burners;

2. Oven thermostat with controlled grill outlet and flame supervision for one burner;

3. Oven thermostat with controlled grill outlet without flame supervision; 4. Oven thermostat only with flamed supervision for oven burner; and

5. Oven thermostat only without flame supervision.

The plug member 110, as illustrated in Figures 5a to 5c, is a profiled cylindrical element upon which there is formed lands for O-rings, flow control flats and a ramped or helical groove to effect axial movement by engaging a fixed pin in the main gas bore of the housing. By selecting a cylindrical element and using a plurality of O-ring seals engaging with the gas flow bore to form the gas paths, the perceived disadvantages of the prior art arrangement, including particularly the disadvantages associated with the tapered plug element valve construction and the manufacturing tolerances required, are substantially eliminated.

The plug member 110 is fitted with three rubber O-ring seals 131,132,133 retained in lands formed within the curved surface of the cylindrical plug 110. The upper seal 131 prevents gas escaping past the plug and out to atmosphere. The middle O-ring seal 132 effects an ON/OFF control to the supplementary gas outlet, which in the present embodiment is described in relation to a grill burner.

By engaging with the walls of the main gas flow bore, incoming gas is prevented from passing into preformed gas paths, which will be described in more detail hereinbelow. The upper 131 and middle 132 O-rings co-operate to constrain the flow of gas from the gas inlet 115 to the grill outlet in a GRILL ON position. The lower seal 133 effects ON/OFF control to the main gas outlet which is connected via the bottom housing section 104 to an oven burner in the current embodiment. In common with the middle O-ring seal 132, the lower seal 133 prevents incoming gas from passing into gas paths formed in the curved walls of the main gas flow bore to effect an oven seal.

A ramped groove 135 is formed in a lower section of the brass plug 110 to provide a linear or axial movement of the plug when the user control spindle is rotated. To enable the device to include a second controlled outlet, the groove on the plug has been designed to give twice the axial movement of the Applicants' prior art design. Along with the changes to the groove size, the OFF position has been designed to be at a point when a fixed drive pin in the body is at the mid- point of the ramped groove. This format allows the plug to be moved in an upward or downwards direction from the central OFF position depending on the direction of rotation of the control spindle to provide two discrete ranges of control and a second control gas outlet. The additional movement of the plug is combined with the addition of a third O-ring seal on the plug. This seal engages with a stepped section in the top of the main bore to provide the open/close sealing mechanism for the additional outlet. Therefore rotating the plug in an anti-clockwise direction from the OFF position will force the plug to move axially upwards and open the seal to the oven outlet (as with the prior art control device). Rotating the plug in a clockwise direction will force the plug to move downwards and open the seal to the grill outlet. If regulation of the flow to the grill outlet is required, this can be achieved by means of flats 137 machined into the diameter of the plug 110, as illustrated in Figure 5c. The flats 137 machined into the plug diameter will reduce the gas flow restriction encountered between the curved surfaces of the plug 110 and gas flow bore, allowing greater flow passed the plug.

This can be used to regulate the flow in conjunction with the alignment of one of the flats 137 with respect to the outlet aperture as the plug 110 is rotated.

The plug 110 is also provided with so-called "bearing diameters" 138 at the upper and lower ends thereof to provide a means of controlling any lateral movement of the plug during rotation. Within the lower bearing diameter, at least one slot 139 is provided to allow gas flow to pass from the inlet port 1 15 around the plug to the thermostatically controlled valve disc 109 and on to the outlet port for the oven burner when the plug is moved to the ON position.

The rotational drive from the spindle 112 to the plug 1 10 is transmitted via a sliding square drive 140 which engages corresponding slots with the upper part of the plug so that the linear or axial movement of the plug is not transferred to the spindle. This allows the spindle to remain in the same plane during rotational operation. A corresponding set of slots 143 is provided within the lower part of the plug, as shown in Figure 6, to facilitate independent axial movement between the plug and a lead screw 145 of the valve actuator mechanism.

Figure 6 also shows the interaction of the various surfaces of the plug 110 with and against the internal profile of the main gas bore. In this detailed view, the control device 100 is OFF and gas from the inlet 115 cannot pass towards the oven regulating valve disc 109 and oven outlet or towards the grill outlet aperture 142 formed in the main gas bore. The lower oven outlet O-ring seal 133 and the middle grill outlet O-ring seal 132 effectively constrain gas flow against mains pressure.

The operation of the diaphragm and the positioning of valve disc with respect to valve seat is substantially as described with respect to the Applicant's prior art thermostatic gas valve and is included herein by reference.

More particularly however and as illustrated in Figure 7, rotational drive from the spindle 112 is transmitted via the plug 110 to the lead screw 145 to provide axial movement of the valve disc 109 with respect to the valve seat to set the temperature at which thermostatic regulation acts to restrict the flow of gas to the oven burner. At one end of the lead screw 145, a sliding square drive is provided to eliminate unrelated axial movement of the lead screw 145 with respect to the plug member 110. At the other end of the lead screw a threaded portion 146 engages a corresponding threaded diaphragm head receiver 148 and the depth to which it is retained is determined by the rotational adjustment of the user control spindle 112 and the pitch of the threaded portion 146.

Figure 8 shows the control device 100 in an OFF position where the plug is centrally positioned within its axial range and the drive pin 150 engages the ramped groove 135 at its mid-point. As detailed in Figure 6, both the oven outlet 152 and the grill outlet 142 are isolated from the gas at the inlet 115 by the action of the oven seal 133 and the grill seal 132, respectively.

In Figure 9, the user control spindle 112 (not shown in Figures 8 to 10) has been rotated anti-clockwise, forcing the plug 110 to move axially upwards within the bore by virtue of the drive pin 150 engaging the profiled groove 135. The oven seal 133 moves out of control with the main gas flow bore walls and a gas path 155 to the oven outlet 152 is opened. Gas flow slots 156 are provided in the lower section of the bore to prevent flow restriction encountered at the bearing 138 of the plug 110.

Finally, with reference to Figure 10, when the user control spindle 112 is turned clockwise, the plug 110 is forced from its existing position, whether that is from an OFF position, as illustrated in Figure 8, or an OVEN ON position, as shown in Figure 9, and moves axially downwards under the influence of the drive pin 150 within the profiled groove 135. From the central or mid-point OFF position, the plug movement extracts the grill seal 132 from the restricted diameter of the main gas flow bore and thus forms a gas path 158 to the grill outlet 142. Further rotation of the plug 110 brings the control flats 137 into play operably to restrict or allow gas to flow from the inlet 115 to the grill outlet 142 and on to the grill burners.

Although the above detailed description has been directed exclusively to control of domestic ovens and grills, it is to be understood that no such limitation should be taken or assumed. The control device 100 and modifications within the overall disclosure of the invention can be applied to the ON/OFF control and regulation of any gas or like media application.

In the light of this disclosure, modifications of the described embodiment, as well as other embodiments, will now become apparent to persons skilled in this art.

It will of course be understood that the invention is not limited to the specific details described herein, which are given by way of example only, and that various modifications and alterations are possible within the scope of the appended claims.

Claims

CLAIMS:

1. A thermostatic control device for the regulation of gas flow within a gas appliance, the device comprising:

a housing;

a resiliency deformable member in operable connection to a temperature sensor;

a rotatable user control spindle in communication with and adapted to move the plug member within the bore,

wherein the plug member and the gas flow bore are profiled to define gas flow paths between inlet and outlet ports and wherein the plug member comprises a cylindrical body adapted sealingly and slideably to fit within the gas flow bore so as to direct gas from an inlet port to one of a plurality of outlet ports.

2. A thermostatic control device as claimed in Claim 1, in which the plug member includes a ramped or helical groove which is engaged by a fixed pin within the bore to effect axial movement upon rotation of the spindle.

3. A thermostatic control device as claimed in Claim 2, in which the groove is profiled and the plug positioned within the bore so that the OFF position corresponds to the mid-point in the range of axial movement of the plug.

4. A thermostatic control device as claimed in Claim 3, in which anti- clockwise rotation of the spindle causes axial movement of the plug in one direction and clockwise rotation of the spindle causes axial movement in the opposite direction, from the central or mid-point OFF position, to provide two discrete ranges of control and a second controlled gas outlet.

5. A thermostatic control device as claimed in any one of the preceding claims, in which the cylindrical plug member includes retaining lands for a plurality of O-rings seals, the seals engaging the curved walls of the bore to define said gas flow paths.

6. A thermostatic control device as claimed in any one of the preceding claims, in which the plug includes a plurality of flow control flats to provide regulation of gas flow upon rotation of the user control spindle to a second controlled gas outlet.

7. A thermostatic control device as claimed in any one of the preceding claims, in which the plug member is driven at one end by the spindle which engages a keyed receiver in the plug member.

8. A thermostatic control device as claimed in Claim 7, in which the keyed receiver is adapted to receive slidingly a shaped end of the spindle so that axial movement of the plug member is not transmitted to the spindle.

9. A thermostatic control device as claimed in any one of the preceding claims, in which a lead screw, engaged in a keyed receiver of the plug member, is slidingly received therein to eliminate the axial movement of the plug member, thereby isolating the valve actuator from axial movement of the plug element which otherwise would be transmitted through the lead screw.

10. A thermostatic control device as claimed in any one of the preceding claims, in which the resiliently deformable member comprises a diaphragm having a profiled diaphragm head adapted to engage the a lead screw operably connected to the plug member.

11. A thermostatic control device as claimed in Claim 9 or Claim 10, in which the lead screw has an externally threaded end which mates with an internally threaded cylindrical portion of the diaphragm head, so that the axial position of the lead screw is determined by the depth of threaded reception within said threaded portion of the diaphragm head.

12. A thermostatic control device as claimed in Claim 11, in which the depth of threaded reception of the lead screw within the diaphragm head is determined by the rotational adjustment of the user control spindle.

13. A thermostatic control device as claimed in any one of Claims 10 to 12, in which calibration of the device is achieved by adjusting the depth of engagement between the lead screw and the diaphragm head, thereby eliminating the need for a conventional calibration screw mechanism.

14. A thermostatic control device as claimed in any one of the preceding claims, in which user settings are selected by means of a control knob secured on the control spindle to which a stop pin is fixed, the stop pin abutting a control surface in the housing to limit rotation of the control spindle.

15. A thermostatic control device as claimed in any one of the preceding claims, in which rotation of the control spindle has a range of from 0 to 300 angular degrees.

16. A thermostatic control device as claimed in Claim 15, in which a first range of control is from 0 to 230 degrees in one direction of rotation and a second range of control is from 0 to 60 degrees in the opposite direction.

17. A thermostatic control device substantially as herein described, with reference to and as shown in Figures 4 to 10 of the accompanying drawings.

18. A plug member for a thermostatic control device substantially as herein described, with reference to and as shown in Figures 5a to 5c of the accompanying drawings.