GB2233756A

GB2233756A - Ignition control for gas heating appliance

Info

Publication number: GB2233756A
Application number: GB8915488A
Authority: GB
Inventors: William Easby; David Waring
Original assignee: Robinson Willey Ltd
Current assignee: Robinson Willey Ltd
Priority date: 1989-07-06
Filing date: 1989-07-06
Publication date: 1991-01-16
Anticipated expiration: 2009-07-06
Also published as: GB2233756B; GB8915488D0

Abstract

A flame failure valve (11) is connected in gas series with a variable flow valve (12). Control rod (24) when manually pushed engages the flame failure valve (11) to open it. At the same time abutment (29) operates microswitch (33) to start ignition sparks and valve (12) is placed by lever (32) in an ignition position. When ignition is established, rod (24) is lifted, allowing the ignition sparks to cease while a "flame present" signal holds the flame failure valve open. To shut the appliance off, rod (24) is lifted so that abutment (29) operates microswitch (39), interrupting the "flame present" signal and so causing the flame failure valve to close. <IMAGE>

Description

CONTROLS FOR GAS HEATING APPLIANCES.

This invention relates to controls for gas heating appliances having flame failure devices comprising valves which require the application of external forces to open them, but which may thereafter be maintained open by "flame present" signals from flame sensors. Such controls will be described hereinafter as gas heater controls of the kind described.

The invention provides a gas heater control of the kind described having a variable flow valve in gas series with the flame failure valve and a common manual control, operation of which to an 'ignition' setting applies the force required to open the flame failure valve, places the variable flow valve at an 'ignition' flow rate and initiates spark ignition.

The said common manual control may be moved between a number of settings including said 'ignition' setting by a sliding adjustment.

The control may comprise a control rod movable axially between said settings and carrying means for operating said flame failure valve, said variable flow valve and said spark ignition means. The relative positions of these operating means is determined so that the abovementioned ignition settings are attained.

Preferably said variable flow valve has no OFF position in use, there being further means operated by the common manual control to turn the heater off. Said further means may comprise a switch which interrupts the "flame present" signal and thus causes the flame failure valve to close. The flame failure valve is thus caused to act as an ON/OFF valve.

A specific embodiment of the invention is shown in the accompanying drawings, in which: Figure 1 is a diagrammatic layout of a gas heater control system, Figure 2 is a section through a valve seat member of the control system of Figure 1, and Figure 3 is a scrap section (not to scale) through a valve head member of the control system of Figure 1.

A control system for a gas-fired heater has two valves (11, 12) connected in gas series through which gas has to flow before being supplied to a gas burner on line (14). Valve (11) is a flame failure valve, movable between an open position when a flame is present and a closed position when a flame is absent. Valve (12) varies the flow rate of the gas and thus the heat output of the heater.

A temperature probe (15) of the thermocouple kind is located adjacent the gas burner so that a high temperature is sensed when there is a gas flame. The electrical signal from the probe (15) is directed through an electric switching control (16) to energize an electro-magnet (17) which operates to attract an armature (18). Valve head (19), secured to move with the armature, opens or closes against a seat to control gas flow in supply line (20) leading to the valve (12).

A push rod (21) acting directly or indirectly on valve head (19) is located to be engaged by a tag (22) on the bottom end of a vertical main control rod (24). The top end of control rod (24) carries a manual slider knob (25) which extends through a vertical slot (26) in a casing wall (27) of the heater. When the knob (25) is pushed right to the bottom of the slot (26), tag (22) engages push rod (21) and opens the valve (11) so that a supply of gas reaches the valve (12) and the burner.

At the same time, another tag (29) engages a microswitch (33) which causes sparks from an ignition system (not shown) to ignite the gas at the burner. After a brief period of time (e.g. 3 seconds), the sensor (15) detects the presence of the flame and energizes electromagnet (17). This magnet is sufficiently strong to hold the armature and valve head in the open position when the knob (25) is released and pressure on tag (22) removed. Thus the valve (11) is fully opened and remains fully open so long as a flame is detected.

Main control rod (24) also engages a slot in a valve control lever (32), the other end of which is located to rotate a valve control spindle (31) [Figure 3] of the flow rate control valve (12). Spindle (31) carries a valve head (35) [Figure 3] which rotates on a valve seat (36) [Figure 2]. The valve seat (36) provides a non-circular surface having, as shown, a "butterfly" shaped opening (37). The head (35) has a series of holes or slots (39) which become aligned with a wing of the opening (37) as the head is rotated by lever (32). Thus The vertical movement of control rod (24) causes different holes to be aligned with opening (37) and varies the gas flow. The movement of the control rod is limited so that the head (35) is never in use in a position in which the gas flow is fully cut off. Valve (12) does not operate as an ON/OFF valve, only to vary gas flow.When the flame failure valve (11) is over-ridden, as described above, to provide for ignition of the heater, the valve (12) is positioned to allow a lowflow start up gas flow.

On release of the knob (25), the tags (29) and (22) cease pressing on microswitch (32) and the valve head (19). The ignition sparks thus cease and, if ignition has been established, valve (11) remains open, while valve (12) provides for a low heat output. To increase the heat output, the slider knob (25) is pushed up the slot (26), rotating the valve head (35) so that increasing hole areas are aligned with the opening (37).

In order to shut off the heater, the knob (25) is pushed up to the topmost position of the slot (26), so that tag (29) engages another microswitch (39). This is connected to switching control (16) so that when operated it cuts off the signal from probe (15). The electromagnet is then de-energized and the valve head (19) returns to the closed position. It will be seen that subsequent release of knob (25) is not accompanied by opening of the valve (11), because it can only be opened from its shut position by pressure on push rod (21). Even if the probe (15) continues to sense a high temperature and to energize the electro-magnet on release of microswitch (39), the valve will not open.

An electricity supply for operation of the electrical controls may be from a dry battery or from a mains connection. There may also be a safety feature (not shown) to lock the slider against inadvertant movement so that the knob has to be urged inward of the casing before it can be moved vertically.

The valve (11) may be formed in an integral housing with a secondary flow valve (not shown) which supplies gas to another burner providing decorative, semi-aerated flames. Another slider knob and control rod may be connected to operate the secondary flow valve.

Claims

CLAIMS:

1. A gas heater control of the kind described having a variable flow valve in gas series with the flame failure valve, and a common manual operator, movement of which to an "ignition" setting applies the force required to open the flame failure valve, places the variable flow valve at an "ignition" flow rate and initiates spark ignition.

2. A gas heater control as claimed in claim 1, wherein said common manual operator may be moved between a number of settings including said "ignition" setting, and one or more different flow rate settings in which said force opening the flame failure valve is released.

3. A gas heater control as claimed in claim 1 or claim 2, wherein the manual operator is movable by a sliding adjustment.

4. A gas heater control as claimed in claim 3, wherein said manual operator comprises a control rod movable axially and carrying means for operating said flame failure valve, said variable flow valve and said spark ignition means.

5. A gas heater control as claimed in claim 4, wherein said means for operating said flame failure valve comprises an "ignition" abutment aligned with a push rod which acts directly or indirectly cn a valve head of the flame failure valve.

6. A gas heater control as claimed in claim 4 or claim 5, wherein said means for operating said variable flow valve comprises a lever connected at one end to the control rod and at the other end to the variable flow valve.

7. A gas heater control as claimed in claim 6, wherein said variable flow valve has a head rotatable by said lever between positions in which openings of varying cross-sectional areas in the head are introduced into the gas stream, thereby varying the gas flow.

8. A gas heater control as claimed in any of claims 4 to 7, in which said means for operating spark ignition means comprises an abutment aligned with a microswitch to operate it when the control rod is in the "ignition" setting.

9. A gas heater control as claimed in any of claims 4 to 8, in which abutment is also aligned with an on/off microswitch, said control rod having an "off" setting at which said microswitch is operated.

10. A gas heater control as claimed in claim 9, wherein said on/off microswitcn is connected when operated to interrupt said "flame present" signal so that the flame failure valve closes.

11. A gas heater control substantially as described hereinbefore with reference to the drawings.