GB1566782A

GB1566782A - Flame failure device

Info

Publication number: GB1566782A
Application number: GB712377A
Authority: GB
Original assignee: TI Domestic Appliances Ltd
Current assignee: TI Domestic Appliances Ltd
Priority date: 1977-02-21
Filing date: 1977-02-21
Publication date: 1980-05-08

Description

(54) FLAME FAILURE DEVICE (71) We, TI DOMESTIC APPLIANCES LIMITED, of Radiation House, North Circular Road, London, N.W.10, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to an improvement in or modification of the flame failure device described and claimed in claim 1 of U.K. patent application No. 43197/74 (Serial No. 1,486,317).

The present invention provides a flamefailure device comprising: a heat-resistant, temperature-sensitive member to be directly heated by a flame and so arranged that the member will expand or contract along a generally rectilinear axis as it is heated or ccoled; a mount to which one portion of the temgerature-sensitive clamber is secured and relá;.ve to which another portion of the terrSperature-sensitive member will move as the temperature-sensitive member is heated or cooled;; a main valve for controlling supply of fuel to a burner and having a fuel inlet, a fuel outlet, a chamber having a diaphragm defining a wall of the chamber, a main-valve member operatively connected to the diaphragm and movable therewith, and passage means for restricted fuel flow to the chamber, and a pilot valve connected to the chamber of the main valve for controlling the opening and closing of the main valve and having a fixed valve member fixed relative to the mount and a movable valve member movable relative to the fixed valve member and operated by an elongate member arranged alongside the heatsensitive member, the elongate member and movable valve member being arranged to move so as to close the pilot valve when the heat-sensitive member is heated and to open the pilot valve on cooling of the heat-sensitive member, the main valve being arranged to open when the pilot valve is closed and to close when the pilot valve is open.

Preferably, the temperature-sensitive member is of tubular configuration and the elongate member is arranged therein.

The invention will now be described with reference to a pilot valve shown in longitudinal section by way of example in the accompanying drawing.

The main valve (not shown) may be exactly as shown in Figure 1 of U.K. patent application No. 43 197/74 (Serial No. 1,486,317). In the accompanying drawing a heat-resistant.

temperature sensitive member is in tiie form of a hollow tube 1 which is mounted, e.g. by welding, on .,- . en of a valve par 2 of a pilot valve. The valve part 2 is externally screwthreaded and f ts inside a correspondingly screw-threade support part 3 of the pilot valve.

As can be seen from the drawing, the valve part 2 has an internal bore 4 whi, . is stepped to provide a fixed valve member in the form of a seat 5. The wider part 6 of the oore 4 contains a movable valve member in the form of a ball 7 and a spring 8 which urges the ball towards the seat 5. When the ball 7 contacts the seat 5 it closes the wider part 6 of the bore from the narrower part 9 of the bore.

The tube 1 contains a rod 10 of non heatsensitive material, e.g. of fused silica, and has an abutment at one end in the form of an adjustable screw 11. The tube 1 also has a vent n The support 3 has a bore 13 aligned with the bore 4 and is internally screw-threaded to receive a connection to the main valve.

When the tube 1 is heated by a flame (not shown) it expands so that the rod 10 is pushed beyond the seat 5 into the narrower bore 9 by means of the spring 8 via the ball 7 until the ball contacts the seat 5. The pilot valve is closed and gas cannot flow from the main valve. The pressure build up resulting from fuel flowing from the fuel inlet of the main valve, through the path for restricted fuel flow to a chamber having a diaphragm defining a wall of the chamber, displaces the diaphragm to open the main valve and allow gas to pass from the fuel inlet to the fuel outlet of the main valve as described in U.K. patent Application No. 43 197/74 (Serial No.

1,486,317).

If the flame is extinguished for any reason the tube 1 contracts until the screw 11 abuts the rod 10 to move it along the narrower bore 9, past the seat 5 and into the wider bore 6 thus forcing the ball 7 away from the seat 5 against the bias of the spring 8. Gas entering the chamber of the main valve from the fuel inlet can now flow through the bore 13, bore 4, tube 1 and vent 12. The resulting drop of pressure in the chamber moves the diaphragm to close the main valve. The main valve cannot be reopened until the flame is relit.

WHAT WE CLAIM IS: 1. A flame-failure device comprising: a heat-resistant, temperature-sensitive member to be directly heated by a flame and so arranged that the member will expand or contract along a generally rectilinear axis as it is heated or cooled; a mount to which one portion of the temperature-sensitive member is secured and relative to which another portion of the temperature-sensitive member will move as the temperature-sensitive member is heated or cooled; a main valve for controlling supply of fuel to a burner and having a fuel inlet, a fuel outlet.

a chamber having a diaphragm defining a wall of the chamber, a main-valve member operatively connected to the diaphragm and movable therewith, and passage means for restricted fuel flow to the chamber, and a pilot valve connected to the chamber of the main valve for controlling opening and closing of the main valve and having a fixed valve member fixed relative to the mount and a movable valve member movable relative to the fixed valve member and operated by an elongate member arranged alongside the heatsensitive member, the elongate member and movable valve member being arranged to move so as to close the pilot valve when the heatsensitive member is heated and to open the pilot valve on cooling of the heat-sensitive member, the main valve being arranged to open when the pilot valve is closed and to close when the pilot valve is open.

2. A flame-failure device as claimed in claim 1, wherein the temperature-sensitive device is of tubular configuration and the elongate member is arranged therein.

3. A flame-failure device as claimed in Claim 1 or 2, wherein the elongate member is a rod, and the temperature-sensitive member has an abutment which moves the rod on cooling of the heat-sensitive member.

4. A flame-failure device as claimed in claim 3, wherein the position of the abutment is adjustable.

5. A flame-failure device as claimed in claim 4, wherein the abutment is an adjustable screw.

6. A flame-failure device as claimed in claim 1, 2, 3 or 4, wherein the movable member is aball.

7. A flame-failure device as claimed in claim 6, wherein the ball is urged towards the fixed valve member by means of a spring.

8. A flame-failure device as claimed in any one of the preceding claims wherein the mount and fixed valve member are formed on a single member.

9. A flame-failure device as claimed in claim 2, or in any one of the claims 3 to 8 dependent on claim 2, wherein the hollow, tubular temperature-sensitive member has a vent to allow gas entering the pilot valve from the chamber to escape.

10. A flame-failure device as claimed in any one of the preceding claims, wherein the elongate member is formed from non heatsensitive material.

11. A flame-failure device substantially as herein described with reference to the accompanying drawing.

12. An appliance having a flame failure device as claimed in any one of the preceding

Claims

claims.