GB1581133A

GB1581133A - Gas-fired domestic ovens

Info

Publication number: GB1581133A
Application number: GB1517276A
Authority: GB
Original assignee: Glynwed Domestic & Heating App
Current assignee: Glynwed Domestic & Heating App
Priority date: 1977-07-13
Filing date: 1977-07-13
Publication date: 1980-12-10

Description

(54) IMPROVEMENTS IN GAS-FIRED DOMESTIC OVENS (71) We, BRIAN HARDING, a British subject, of 28 Arlington Road, West Bromwich, West Midlands B71 1AD, and GLYN WED DOMESTIC AND HEATING APPLIANCES LIMITED, a British Company, of Headland House, Sheldon, Birmingham, 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 improvements in gas-fired domestic ovens of the kind in which gas can be supplied to a burner in the oven for normal cooking purposes through a thermostatically-controlled valve, and gas can also be supplied to the same or a different burner in the oven through a restrictor means constructed and arranged to restrict the flow of gas to the last-mentioned burner to a value for sustaining a slow cooking flame capable of heating and maintaining the oven at a temperature below 100"C. Such domestic ovens are hereinafter referred to as "of the kind described".

Gas cookers are available having electric clocks that can be set to start or stop the oven burner to which gas is supplied through a thermostatically-controlled valve at a preset time. Often, however, the user finds it difficult to understand the procedure for automatic oven setting, and sometimes forgets finally to switch on the knob controlling the thermostat of the control valve.

Also difficulties arise in using town or coal gas since the full gas pressure cannot be taken through a valve controlled by the electric clock. These difficulties do not arise with natural gas.

The present invention consists in a domestic oven of the kind described which is fired with natural gas and wherein the thermostatically controlled valve is located in series between the gas supply and a second valve controlled by an oven-programming clock, and a third programme selector valve is connected into the line between the thermostatically-controlled valve and the second valve.

This simplifies the programming of the oven since the timing sequence and the programme selection are controlled by separate valves.

Preferably the restrictor means is located in a line leading from the selector valve to a point downstream of the second valve. The line thus by-passes the second valve and the restrictor means can be brought into operation as an alternative to or in addition to the supply through the second valve by suitable manipulation of the selector valve. Consequently a slow cooking flame may be available during an automatic cycle either exclusively or can continue at the termination of an automatic cycle, after the second valve has closed, so as to maintain cooked food warm.

Preferably the cooker is provided with electrically-responsive light emitting means for indicating what particular oven programme has been selected. For example different light emitting means may be energised according to the setting of the oven, for example whether on a slow cooking "S" setting, or on a normal burner setting, and whether the oven is set for manual or automatic operation.

An embodiment of the invention will now be described by way of example with refernce to the accompanying drawings in which: Figure 1 shows diagrammatically a gas supply for a burner of a domestic oven fired with natural gas; Figure 2 is a diagram of an electrical circuit of the oven; Figure 3 is a diagram of an electrical switching arrangement, and Figures 4 to 8 are typical arrangements of a programme selector valve for the burner.

Referring to Figure 1, natural gas is supplied to a burner 1 of a domestic oven through a thermostatically-controlled valve 2, and the gas passes from the valve to the burner through a second valve 3 controlled by an electric clock 4. A third, manuallyoperable, programme selector valve 5 is disposed in the line between the thermostatically-controlled valve 2 and the clock-controlled valve 3. Restrictor means 6 for sustaining a slow cooking flame on the burner is disposed in a by-pass line 7 connecting the programme selector valve 5 to the supply line to the burner on the downstream side of the clock-controlled valve.

The restrictor means 6 comprises a solenoid-operated valve constructed and arranged so that no gas will pass through the valve in the first stage of a cycle in which the burner is operating normally during an automatic cycle, and it allows a restricted supply of gas to pass through the by-pass line 7 the burner 1 for slow cooking when the clockcontrolled valve closes. The restrictor means may be of any other convenient form, if desired. It may, for example, comprise a restriction in the line which provides a metered flow of gas.

The programme selector valve 5, shown in Figures 4 to 8, has an inlet A from the main line from the thermostatically controlled valve 2 and outlets B and C respectively to the main line to the clock-controlled valve 3 and to the by-pass line 7 to the restrictor means 6. The valve can be operated to select connection of the inlet A to outlet B, or to outlet C or to both outlets B and C, when the oven is operating normally or on an autopreset programme. In Figure 4 the inlet A is shown connected to both outletsBandCfor direct manual control of the burner with the clock-controlled valve open and not acted upon by the clock. The position shown in Figure 5 is selected when the last-mentioned valve is operating automatically under the control of the clock, the inlet A in this instance being connected only to outlet B.In Figure 6 the inlet A is shown connected only to outlet C, this position being selected manually when the clock-controlled valve is open and not acted upon by the clock.

Figure 7 shows the inlet A connected to both outlets but when the clock-controlled valve has been shut-off after operating automatically under the control of the clock, so that only the by-pass line 7 is open to the burner for slow cooking in the oven after the normal cooking cycle. Finally, Figure 8 shows the setting which is required to provide an automatic pre-set cycle in which a period of high temperature cooking under the control of the clock is to be followed by slow cooking, the inlet A being connected to both outlets B and C during the high temperature cooking though the valve is at a different angular setting from that shown in Figure 4 for the direct manual control of the burner.

Before the gas finally reaches the burner 1 it passes through a thermo-electric flame failure device 8, Figure 1, comprising a valve which, whilst the burner is ignited, is held open by a solenoid energised by the small current produced by a heat responsive probe 9 at the burner.

In the electrical circuit shown in Figure 2, a switch D on the oven thermostat control knob must be closed to provide the indicator circuit, and a switch E on the clock is set according to whether the oven is to operate under manual or automatic control. A switch F, which may be a limit or rotary switch, on the programme selector valve 5 operates to illuminate different light sources and combinations of light sources according to the setting of the valve. Figure 3 shows the different positions of the switch F and the light sources which are illuminated in the positions. As will be seen, when position (1) of the switch is selected for normal cooking under manual control of the oven, a "COOK" light source G is illuminated. At position (2) of switch F, which it occupies when slow cooking under manual control is required a "SLOW COOK" light source H is illuminated.When the oven is set for automatic control and slow cooking and boost are required the switch is set at position (3) which causes "SLOW COOK" and "BOOST" light sources I and J respectively to be illuminated. Position (4) of the switch is occupied when automatic normal cooking followed by slow cooking is selected. In this last position an "AUTO-HOLD" light source K is illuminated and a "HOLD" light L in a line to the solenoid M which operates the valve of the restrictor means 6 and to a limit switch N on the clock which is closed for the automatic setting. In addition whilst the normal cooking cycle is in progress a "COOK" light source 0 is also illuminated.

When automatic normal cooking without subsequent slow cooking is selected the switch is at position (5) and an "AUTO" light source P is illuminated. Whilst cooking is taking place the "COOK" light source 0 is again illuminated.

The various indicator light sources are conveniently neon lamps.

It will be understood that many other arrangements are possible for indicating selected settings of the selector valve 3.

The slow cooking provision is described in the Complete Specifications of our Patent Applications Nos. 8621/76 and 8622/76 (Serial Nos. 1569761 and 1569762).

WHAT WE CLAIM IS: 1. A domestic oven of the kind described which is fired with natural gas and wherein the thermostatically controlled valve is located in series between the gas supply and a second valve controlled by an oven-programming clock, and a third programme selector valve is connected into the line between the thermostatically-controlled valve and the second valve.

2. A domestic oven according to Claim 1 wherein the restrictor means is located in a line which by-passes the second valve and leads from the programme selector valve to a point downstream of the second valve.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. disposed in a by-pass line 7 connecting the programme selector valve 5 to the supply line to the burner on the downstream side of the clock-controlled valve. The restrictor means 6 comprises a solenoid-operated valve constructed and arranged so that no gas will pass through the valve in the first stage of a cycle in which the burner is operating normally during an automatic cycle, and it allows a restricted supply of gas to pass through the by-pass line 7 the burner 1 for slow cooking when the clockcontrolled valve closes. The restrictor means may be of any other convenient form, if desired. It may, for example, comprise a restriction in the line which provides a metered flow of gas. The programme selector valve 5, shown in Figures 4 to 8, has an inlet A from the main line from the thermostatically controlled valve 2 and outlets B and C respectively to the main line to the clock-controlled valve 3 and to the by-pass line 7 to the restrictor means 6. The valve can be operated to select connection of the inlet A to outlet B, or to outlet C or to both outlets B and C, when the oven is operating normally or on an autopreset programme. In Figure 4 the inlet A is shown connected to both outletsBandCfor direct manual control of the burner with the clock-controlled valve open and not acted upon by the clock. The position shown in Figure 5 is selected when the last-mentioned valve is operating automatically under the control of the clock, the inlet A in this instance being connected only to outlet B.In Figure 6 the inlet A is shown connected only to outlet C, this position being selected manually when the clock-controlled valve is open and not acted upon by the clock. Figure 7 shows the inlet A connected to both outlets but when the clock-controlled valve has been shut-off after operating automatically under the control of the clock, so that only the by-pass line 7 is open to the burner for slow cooking in the oven after the normal cooking cycle. Finally, Figure 8 shows the setting which is required to provide an automatic pre-set cycle in which a period of high temperature cooking under the control of the clock is to be followed by slow cooking, the inlet A being connected to both outlets B and C during the high temperature cooking though the valve is at a different angular setting from that shown in Figure 4 for the direct manual control of the burner. Before the gas finally reaches the burner 1 it passes through a thermo-electric flame failure device 8, Figure 1, comprising a valve which, whilst the burner is ignited, is held open by a solenoid energised by the small current produced by a heat responsive probe 9 at the burner. In the electrical circuit shown in Figure 2, a switch D on the oven thermostat control knob must be closed to provide the indicator circuit, and a switch E on the clock is set according to whether the oven is to operate under manual or automatic control. A switch F, which may be a limit or rotary switch, on the programme selector valve 5 operates to illuminate different light sources and combinations of light sources according to the setting of the valve. Figure 3 shows the different positions of the switch F and the light sources which are illuminated in the positions. As will be seen, when position (1) of the switch is selected for normal cooking under manual control of the oven, a "COOK" light source G is illuminated. At position (2) of switch F, which it occupies when slow cooking under manual control is required a "SLOW COOK" light source H is illuminated.When the oven is set for automatic control and slow cooking and boost are required the switch is set at position (3) which causes "SLOW COOK" and "BOOST" light sources I and J respectively to be illuminated. Position (4) of the switch is occupied when automatic normal cooking followed by slow cooking is selected. In this last position an "AUTO-HOLD" light source K is illuminated and a "HOLD" light L in a line to the solenoid M which operates the valve of the restrictor means 6 and to a limit switch N on the clock which is closed for the automatic setting. In addition whilst the normal cooking cycle is in progress a "COOK" light source 0 is also illuminated. When automatic normal cooking without subsequent slow cooking is selected the switch is at position (5) and an "AUTO" light source P is illuminated. Whilst cooking is taking place the "COOK" light source 0 is again illuminated. The various indicator light sources are conveniently neon lamps. It will be understood that many other arrangements are possible for indicating selected settings of the selector valve 3. The slow cooking provision is described in the Complete Specifications of our Patent Applications Nos. 8621/76 and 8622/76 (Serial Nos. 1569761 and 1569762). WHAT WE CLAIM IS:

1. A domestic oven of the kind described which is fired with natural gas and wherein the thermostatically controlled valve is located in series between the gas supply and a second valve controlled by an oven-programming clock, and a third programme selector valve is connected into the line between the thermostatically-controlled valve and the second valve.

3. A domestic oven according to Claim 2

wherein the programme selector valve is operable to supply gas to the second valve and/or the restrictor means.

4. A domestic oven according to any preceding claim wherein the restrictor means comprises a solenoid-operated valve.

5. A domestic oven according to any of Claims 1 to 3 wherein the restrictor means comprises a restriction in a gas supply line which provides a metered flow of gas.

6. A domestic oven according to Claim 2 or Claim 3 wherein a flame failure device is provided downstream of that point to which the by-pass line leads.

7. A domestic oven according to any preceding claim wherein electrically-responsive light emitting means are provided for indicating programme settings of the oven.

8. A domestic oven according to Claim 7 wherein the light emitting means are controlled by switch means responsive to settings of the programme selector valve.

9. A gas-fired domestic oven incorporating a gas supply system substantially as described herein with reference to and as illustrated by the accompanying drawings.