Patent Application
20160348908
The present invention relates to a valve and a system for controlling a gas burner.
Gas control valves are used in domestic applications to control the flow rate of gas to an appliance such as a domestic gas fire so as to provide a variable size gas flame. These valves typically incorporate means for flame ignition and a thermo-electric flame failure device for cutting off the gas supply when no flame is present.
Gas control valves typically regulate the flow of gas to the gas burner using a motor to open and close a valve seat formed in a delivery duct. The present invention provides an improved valve for controlling a gas burner.
According to a first aspect of the invention, there is provided a gas valve for controlling flow of gas to a gas burner, the valve comprising: a valve body having a gas inlet, a main gas outlet and a bore, the bore having an interior surface a part of which defines a gas flow cavity, the gas inlet and the main gas outlet being in communication with the gas flow cavity; and a valve spindle arranged to move into and out of the gas flow cavity, an exterior portion of the valve spindle forming a flow control surface and defining a gap having a volume between the flow control surface and the interior surface of the gas flow cavity, wherein relative movement of the flow control surface and the gas flow cavity varies the volume of the gap and is adapted to regulate a flow of gas from the gas inlet to the main gas outlet.
The valve spindle may further include means for receiving a first seal in which a first seal is disposed. Such a first seal may be adapted to form a seal between the valve spindle and the interior surface of the gas flow cavity to prevent the flow of gas over the flow control surface. In other words, since the gap between the flow control surface and interior surface of the gas flow cavity will always have a non-zero volume, flow of gas from a first axial end of the flow control surface, over a length of the flow control surface and then over a second distal axial end of the flow control surface is prevented by pushing the first seal against the interior surface of the gas flow cavity.
The means for receiving the first seal may be a circumferential groove formed in an exterior/outer surface of the valve spindle.
At least one of the flow control surface and the interior surface of the gas flow cavity may be tapered. The at least one of the flow control surface and the interior surface of the gas flow cavity may be frusto-conical. In particular, the flow control surface may frusto-conical and the interior surface of the gas flow cavity may have a uniform circular diameter.
The frusto-conical surface may be inclined to an axis of the valve spindle at an angle of between 2.5° and 10°.
The bore may have a longitudinal axis and the relative movement of the flow control surface and the gas flow cavity may be along the axis.
The gas valve may further comprise a linear motor for propelling the valve spindle along the axis. The linear motor and the valve spindle may each be provided with cooperating threaded portions for attaching the motor to the valve spindle. The linear motor may mounted at a first end of the longitudinal bore.
The valve spindle may be provided with a second seal to prevent flow of gas to the motor.
The first seal may be adapted to cooperate with the interior surface of the gas flow cavity to prevent flow of gas from the gas inlet to the main gas outlet.
The valve body may further comprise a pilot gas outlet in communication with the bore.
The valve body may further comprise a low rate cross drilling bore between the gas flow cavity and the main gas outlet, for providing gas flow to provide a low rate flame.
The gas valve may further comprise means for adjusting the flow rate through the low rate cross drilling bore.
The means for adjusting the flow rate through the low rate cross drilling bore may be a low rate adjuster screw which projects into the low rate cross drilling bore.
The gas valve may further comprise a flame safety device for sealing the gas flow cavity to prevent flow of gas from the gas inlet to the main gas outlet.
The flame safety device may be mounted at a second opposed end of the longitudinal bore.
According a second aspect of the invention there is provided a gas fire system, comprising: a gas valve as described above; a spark generator for igniting a gas flowing out of the gas valve; a microprocessor-based controller for controlling the operation of the valve spindle and the spark generator; and a user interface for providing instructions to the controller.
The user interface may be one of a wired and wireless user interface.
According to a further aspect of the invention, there is provided a gas valve for controlling flow of gas to a gas burner, the valve comprising: a valve body having a gas inlet, a main gas outlet and a bore, the bore having an interior surface a part of which defines a gas flow cavity, the gas inlet and the main gas outlet being in communication with the gas flow cavity; and a valve spindle arranged to move into and out of the gas flow cavity, an exterior portion of the valve spindle forming a flow control surface and defining a gap having a volume between the flow control surface and the interior surface of the gas flow cavity, wherein relative movement of the flow control surface and the gas flow cavity varies the volume of the gap and is adapted to regulate a flow of gas from the gas inlet to the main gas outlet, the valve spindle further comprising a seal which is distinct from the exterior surface of the valve spindle and which is adapted to cooperate with the interior surface of the gas flow cavity to prevent flow of gas from the gas inlet to the gas outlet.
According to a further aspect of the invention, there is provided a gas valve for controlling flow of gas to a gas burner, the valve comprising: a valve body having a gas inlet, a main gas outlet and a bore, the bore having an interior surface a part of which defines a gas flow cavity, the gas inlet and the main gas outlet being in communication with the gas flow cavity; and a valve spindle arranged to move into and out of the gas flow cavity, an exterior portion of the valve spindle forming a flow control surface and defining a gap having, in use, a positive volume between the flow control surface and the interior surface of the gas flow cavity, wherein relative movement of the flow control surface and the gas flow cavity varies the volume of the gap and is adapted to regulate a flow of gas from the gas inlet to the main gas outlet.
According to a further aspect of the invention, there is provided a gas valve for controlling flow of gas to a gas burner, the valve comprising: a valve body having a gas inlet, a main gas outlet and a bore, the bore having an interior surface a part of which defines a gas flow cavity, the gas inlet and the main gas outlet being in communication with the gas flow cavity; and a valve spindle arranged to move into and out of the gas flow cavity, an exterior portion of the valve spindle forming a flow control surface and defining a gap having a volume between the flow control surface and the interior surface of the gas flow cavity, wherein relative movement of the flow control surface and the gas flow cavity varies the volume of the gap and is adapted to regulate a flow of gas from the gas inlet to the main gas outlet and wherein in use the flow control surface does not come in contact with the interior surface of the gas flow cavity.
The invention will now be described by way of example with reference to the drawings, in which:
The gas burner 102 is shown in
The valve body 202 is shown in greater detail in
With reference to
The front part 228 of the motor 204 comprises portions of reducing diameter, namely a shoulder 232, a neck 234, a motor spindle 236 and a threaded end portion 238. As stated above, the motor 204 is a linear motor such that the motor spindle 236 and threaded end portion 238 reciprocate relative to the shoulder 232 and neck 234 with a stroke of around 14 mm between the fully extended and fully retracted positions. When the motor 204 is fully contracted, as is described below with reference to
The valve spindle 206 is shown in greater detail in
The valve spindle 206 has two circumferential grooves in its outer surface. A main seal circumferential groove 246 is disposed towards the open end 248 of the valve spindle 206. This circumferential groove 246 receives a main seal 250, shown in
Returning to
The dimensions and shape of the frusto-conical flow control surface 262 depend on the type of gas used in the gas valve 104. For example, where the gas valve 104 is to be used with natural gas the angle θ at which the flow control surface 262 is inclined relative to an axis of the valve spindle 206 is 5°. Where the gas valve 104 is to be used with liquefied petroleum gas (LPG) the angle θ is set to 2.5°. As is described below, the shape of the flow control surface 262 is set so as to regulate the gap between the flow control surface 262 and an inner circumferential surface 298 of the longitudinal bore 202 in a portion C of the valve body 202. By moving the flow control surface 262 in and out of this portion C of the longitudinal bore 212 the volume of the gap is varied to control the flow rate of gas through this gap.
It will be understood by a person skilled in the art that the inclination angle θ can be set at angles other than 2.5° and 5° as described above, since the flow rate of gas between the flow control surface 262 and the inner wall 298 of the longitudinal bore 212 of the section C can be controlled by adjusting the length and shape of the flow control surface 262 and the inner surface 298 of the longitudinal bore 212. The tapered circular exterior of the flow rate surface 262 and the corresponding circular bore inner surface 298 provide the advantage that the orientation of the valve spindle 206 relative to the valve body 202 does not affect the performance of the flow control surface 262. This is particular useful since the valve spindle 206 is screwed to the motor spindle end portion 238 of the linear motor 204, hence the final rotational orientation of the valve spindle 204 is immaterial to its performance.
Whereas the flow control surface 262 of the valve spindle 206 described above has a circular exterior of varying diameter along its longitudinal axis, having full rotational symmetry around its axis, in other embodiments the valve spindle may have a non-round exterior shape. Rather, the exterior surface of the valve spindle can be shaped to cooperate with the interior surface of the longitudinal bore so as to vary the volume of the gap between the flow control surface and the bore interior surface in a suitable manner to vary gas flow through this volume as the flow control surface reciprocates within the cavity defined by the interior surface of the longitudinal bore. Hence, in other embodiments the flow control surface and the inner bore surface may be shaped other than round, for example oval, triangular, rectangular, pentagonal, hexagonal or other regular or irregular polygonal shape, as long as the reciprocating movement of the flow control surface into the longitudinal bore varies the volume of the gap between these portions and consequently the flow rate of gas over these portions.
With reference to
The longitudinal bore 212 is divided into four sections as shown in
The second section B has a reduced diameter of around 15 mm and is dimensioned to accommodate the main seal 250 of the valve spindle 206, which is arranged to reciprocate within the second section B. As can be seen in
The third section C has a further reduced diameter of around 7 mm and is in communication with a low rate cross-drilling bore 269 and the pilot gas outlet 270. The low rate cross-drilling bore 269 is in communication with a low rate adjuster screw receiving bore 286 and the main gas outlet 268. The low rate adjuster screw receiving bore 286 is threaded. This third section C acts as a flow control bore. A front portion 272 of the valve spindle, which includes the cross port seal 256, is arranged to reciprocate within the third section C so as to control a flow of gas to the main gas outlet 268, the low rate cross-drilling bore 269 and the pilot gas outlet 270.
The fourth section D, which runs from and has a larger diameter than the third section
C to the end 216 of the valve body 202 is dimensioned to receive the electromagnet 208 and the magnet nut 210. The fourth section D is in communication with the gas inlet 266 and receives the electromagnet 208 and the magnet nut 210. The distal portion 271 of the fourth section D is internally threaded to cooperate with the external thread of the magnet nut 210. This fourth section D acts as a flame safety device bore.
The electromagnet 208 serves as a flame safety device (FSD). The FSD comprises a body 274 and a piston 276. The piston 276 comprises a reciprocating shaft 278. A return spring 280 is disposed around the shaft 278 and a rubber seal 282 is disposed at a distal end of the shaft 278. When current is supplied to the FSD 208 to energise an electromagnet (not shown) within the body 274, the piston 276 is latched in position. The current is typically provided to the FSD from a thermocouple, as is described below. When the piston 276 is pushed into the body 274 against the force of the spring 280 the application of current to the electromagnet holds the piston 276 stationary against the biasing force of the spring 280. In this contracted position the seal 282 is spaced from an end 284 of the longitudinal bore 212 in the third section C of the valve body 202, to allow unrestricted flow of gas from the fourth section D to the third section C (the flow control bore) of the longitudinal bore 212. When the flow of current is removed from the FSD 208 the spring 280 urges the FSD piston 276 and seal 282 away from the piston body 274 so as to abut the end 284 of the longitudinal bore 212 in the third section C of the valve body 202, which acts as a seat 284 for the seal 282. When the seal 282 abuts the seat 284, the longitudinal bore 212 in the third section C (the flow control bore) of the valve body 202 is sealed to prevent flow of gas out of the valve body 202.
The FSD 208 is held in place within the valve body 202 by means of the magnet nut 210, which is screwed into the end 216 of the valve body 202. An aperture 285 is provided in the magnet nut 210 to provide access to the electromagnet 208, for example by a thermocouple connector.
The gas valve 104 shown in
The gas valve 104 further comprises two ball seals 320 which are used to seal cross-drilled holes. The valve body 202 further comprises two mounting feet 294.
The operation of the gas valve 104 is now described with reference to
In
In order to operate the gas burner 102 the seal 282 must be moved away from the end 284 of the third section C (the flow control bore) of the longitudinal bore 212. This is performed by fully extending the linear motor 204, so that the valve spindle 206 and the motor spindle 236 are at their rightmost position. This is shown in
Once the flame safety device 208 has been latched open the motor spindle 236 is partially retracted into the neck 234 of the linear motor 204 so that the motor spindle 236 protrudes from the neck 234 by around 11 mm, as shown in
In order to increase the size of the flame beyond a pilot light, the valve spindle 206 is moved further to the left, towards the linear motor 204, so that the cross port seal 256 moves beyond the low rate cross-drilling bore 269, as shown in
To increase the size of the flame further, the valve spindle 206 is moved closer to the linear motor rear part 230, as shown in
The main seal 250 on the valve spindle 206 prevents gas from escaping through the linear motor 204 and between the motor 204 and the first end 214 of the valve body 202.
Since the cross port seal 256 is no longer within the third section C of the longitudinal bore 212, gas is able to flow from the third section C of the longitudinal bore 212 into the second section B thereof (the main flow bore). The gas flow rate from the third section C to the second section B is regulated by the position of the flow control surface 262 within the third section C. In particular, the interior walls 298 of the third section C define a main gas flow cavity through which gas is able to pass and the flow control surface 262 of the valve spindle 206 partially fills this cavity to restrict gas flow from the third section C to the second section B so as to force the gas to flow between the flow control surface 262 and the interior wall 298 of bore 212. By varying the extent to which the flow control surface 262 is disposed within the cavity the gas flow rate is varied.
To increase the size of the flame further, the valve spindle 206 is moved closer to the motor rear part 230 with a separation of around 2.8 mm, to increase a volume of the gap between the flow control surface 262 and the inner circumferential wall 298 of the longitudinal bore 212 in the third section C (the flow control bore) of the bore 212, as shown in
In
Finally, in
It will be apparent to a person skilled in the art that the gap between the flow control surface 262 and the inner circumferential wall 298 of the longitudinal bore 212 always maintains a positive/non-zero volume. This is because there is never full circumferential contact between the flow control surface 262 and the inner circumferential wall/inner surface 298 of the longitudinal bore 212. Rather, the gas flow path from the gas inlet 266 to the main gas outlet 268 is closed by means of the cross port seal 256, which can be positioned to abut the inner surface 298 of the longitudinal bore 212. Furthermore, the flow control surface 262 is arranged not to come into contact with the inner surface 298 of the longitudinal bore 212 in order to prevent wear to this part 262, thereby maintaining the integrity of the flow control surface 262 and the required flow control accuracy.
An advantage of the present invention is that due to the frusto-conical shape of the flow control surface 262, the linear reciprocating motion of the valve spindle 206 accurately controls the flow of gas to the main gas outlet 268 and consequently the size of the gas flame. The accurate positioning of the valve spindle 206 and its flow control surface 262 is controlled by the micro-processor based controller 106, as is described below.
The microprocessor-based controller/electronic control board (ECB) 106 controls the operation of the gas valve 104 based on inputs received from one or both of the user interfaces 110, 112. The ECB 106 also controls the spark generator 108. Since a mains power supply is not always found near to a domestic gas fire, the ECB is powered by a battery pack 120 comprising commonly available cells, such as a 9V PP3 battery. The power source 120 provides power for ECB functionality, spark generation and motor operation.
In particular, the ECB 106 provides positional instructions to the linear motor 204 in order to propel the valve spindle 206 to vary the gas output conditions. The ECB 106 further provides operational output sequences providing safety lockouts, audible warning tones and monitoring of current and voltage levels from the power source 120 and thermocouple inputs.
The ECB 106 also monitors the power source 120 for a critical level. If the voltage and/or current falls below this predetermined level a ‘low power lock out’ occurs. This initiates preventing further operation and unsafe operation of the gas valve 104. Similarly, disconnection of the power source 120 during operation of the gas valve 104 results in shut down of the system 100 into a safe condition, by releasing the flame safety device 208.
The ECB 106 is provided with an earth lead (not shown). This earthed connection helps prevent anomalies occurring during system 100 usage. The earth lead connects to a terminal on the ECB 106 and to the chassis of the appliance 102 to which the system 100 is to be installed.
Since the electrical components of the system 100 are battery powered, it is important to efficiently use the available electrical power. The ECB 106 has a power saving ‘sleep’ mode, which limits the activity of the ECB to a minimum ensuring maximum energy efficiency.
A ‘cold start’ initiation sequence has been incorporated to overcome problems with control valve operation at low ambient temperature conditions, e.g., early in the morning. An additional allocation of power is provided to the control valve motor 204 to ensure operation and to increase system efficiency. Once the ambient temperature increase, generally, less power is required for the start-up initiation sequences.
The ECB 106 has an on-board spark generator 108 that provides the capability to ignite the gas. The spark generator 108 is utilised on the ignition stage of the start-up sequence. Once the ECB 106 has detected that the gas is lit the spark generator 108 ceases to operate, further improving the energy efficiency of the system 100. This is performed by using a thermocouple in the gas flame. Once the gas is lit the temperature of thermocouple rises and a current is generated in the thermocouple. If the flame is extinguished or fails to ignite, the current monitoring of the ECB 106 will detect this and trip the FSD 208 causing it to drop out and close seal 282 against the end 284 of the longitudinal bore 286 in the third section C of the valve body 202, as shown in
Two user interface are provided, namely a local user interface 110 which is wiredly connected to the ECB 106 and a remote user interface 112 which is wirelessly connected to the ECB 106, the latter being the primary interface. The method of wireless transmission is infra-red (IR) for which a corresponding receiver 114 connected to the ECB 106 is required. Alternate transmission technology, including radio frequency, may be used. The skilled person will understand that wireless technologies other than IR and RF technologies may be used.
‘Down’ 708. Single button presses or combinations of buttons 702, 704, 706, 708 are required to convey the required command to the ECB and control valve. For example, to start the system 100 a combination of the ‘Max’ 702 and ‘Min’ 704 buttons are pressed for three seconds or a similar predetermined period of time. This dual button requirement also provides a child lock safety feature incorporated into the handset design to prevent accidental start up. The local user interface 110 may have the same buttons.
The operation of the system 100 is described below. The flame of the gas burner 102 is ignited as follows. One or more buttons 702, 704 on the remote 112 or local 100 user interface are pressed to send a signal to the ECB 106. The ECB 106 then sends a signal to the linear motor 204 to drive the end 254 of the valve spindle 206 forward against the FSD piston 276 as shown in
Once the flame in the gas burner has been established the user controls the flame height by pressing buttons 702, 704, 706, 708 on the user interface 110, 112 to move the valve spindle 206 as shown in
If the ‘Max’ button 702 is pressed the valve spindle 206 is moved all the way to the left as shown in
When the user has finished using the system 100, the ‘off’ function can be activated whereby the system 100 will stop gas flow into the appliance and leave the appliance in a safe condition as shown in
Various modifications will be apparent to those in the art and it is desired to include all such modifications as fall within the scope of the accompanying claims.
For example, in the embodiment described above the flow control surface 262 is frusto-conical and the gas flow cavity defined by the interior wall 298 of the longitudinal bore 212 in the third section C has a uniform diameter. In other embodiments the flow control surface may have a uniform diameter and the wall of the gas flow cavity may be tapered, having a frusto-conical shape. Alternatively, both of the flow control surface and the interior wall of the bore 212 may have a frusto-conical shape. Similarly where the flow control surface has a non-round exterior surface and the interior surface of the bore has a corresponding non-round surface, the flow control surface may have a uniform diameter and the interior surface of the bore may have a tapered diameter or both of the flow control surface and the interior surface of the bore may be tapered. In all cases the skilled person will understand that the corresponding surfaces of the flow control surface and the interior of the bore should be shaped so that relative motion of the flow control surface and the interior of the flow control bore varies the volume of the gap between these surfaces and regulates the flow of gas through the gap.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1402099.4 | Feb 2014 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/GB2015/050350 | 2/9/2015 | WO | 00 |
