Method of operating a gas burner of a gas cooking appliance and gas burner and gas cooking appliance

Abstract

A gas burner (2) including a gas injector (3), a gas supply line (4) connected to the gas injector (3) so as to feed gas to the gas injector (3), and a single automatic gas valve (5) installed in the gas supply line (4) upstream the gas injector (3) so as to control gas supply to the gas injector (3). During ordinary operational modes, the single automatic gas valve always is in an open status not exceeding a preset upper opening limit. During temporary boost operational modes the automatic gas valve is in an open state exceeding the upper opening limit.

Claims

1. A method of operating a gas burner of a gas cooking appliance, the cooking appliance comprising: a gas injector, a gas supply line connected to the gas injector so as to feed gas to the gas injector, and a single automatic gas valve installed in the gas supply line upstream from the gas injector so as to control gas supply to the gas injector; the method comprising, during ordinary operational modes, maintaining the single automatic gas valve always in an opened state not exceeding a preset upper opening limit, wherein during a temporary boost operational mode the automatic gas valve is in an opened state exceeding the upper opening limit, and wherein the boost operational mode is blocked for a fixed first time period after igniting the gas burner.

2. The method according to claim 1, wherein the gas injector has a predefined and fixed maximal gas flow rate, and wherein during the boost operational mode, the overall gas flow rate is limited by the fixed maximal flow rate of the gas injector.

3. The method according to claim 1, wherein setting the respective operational modes of the automatic gas valve is carried out by an electronic control unit.

4. The method according to claim 1, wherein the gas burner is operable in said ordinary operational modes with a continuous power having an upper power limit corresponding to said upper opening limit, and wherein in the temporary boost operational mode, the power of the gas burner is temporarily raised by a certain percentage of the upper power limit.

5. The method according to claim 4, wherein the continuous upper power limit is about 4 kW.

6. The method according to claim 1, wherein a maximal duration of the boost operational mode is restricted to a fixed second time period.

7. The method according to claim 1, wherein two successive boost operational modes require an intermediate ordinary operational mode at least of a fixed third time period.

8. The method according to claim 1, wherein the gas burner in a further operational mode is powered in an intermittent mode successively alternating between ordinary operational and boost operational modes.

9. A gas burner comprising: a gas injector with a fixed maximal gas flow rate; a single automatic gas valve; a gas supply line at least connecting a gas output of the automatic valve to a gas input of the gas injector, wherein a maximal gas flow rate of the automatic valve is larger than the maximal flow rate of the gas injector; and an electronic control unit adapted to control open and closing positions of the automatic gas valve wherein during ordinary operational modes, the single automatic gas valve is always in an opened state not exceeding a preset upper opening limit, and wherein during a temporary boost operational mode the automatic gas valve is in an opened state exceeding the upper opening limit, wherein the boost operational mode is blocked for a fixed first time period after igniting the gas burner.

10. A gas cooking appliance comprising at least one gas burner according to claim 9.

11. The method according to claim 4, wherein the certain percentage is 25% of the upper power limit.

Description

(1) Embodiments of the invention will now be described in connection with the annexed figures, in which

(2) FIG. 1 shows a schematic design of a proposed gas burner;

(3) FIG. 2 shows a chart of a first operational mode; and

(4) FIG. 3 shows a chart of a second operational mode.

(5) The invention will be described in connection with selected embodiments of a gas burner, wherein the selected embodiments shall not be construed as limiting the scope of the invention.

(6) If not otherwise stated like elements are denoted by like reference signs throughout the figures. The figures may not be true to scale, and scales of different figures may be different.

(7) FIG. 1 shows a schematic design of a gas cooking appliance 1 according to the invention. The gas cooking appliance 1 comprises a gas burner 2 with a gas injector 3. The gas injector 3 is connected via a single stranded gas supply line 4 to an automatic gas valve 5. It shall be noted, that the gas cooking appliance 1 may comprise more than just one gas burner 2. In particular, the gas cooking appliance 1 may comprise two, three or four gas burners 2 as shown and described in connection with FIG. 1.

(8) Going now into details of the gas burner 2, a gas outlet of the automatic gas valve 5 is connected to a gas inlet of the gas injector 3 via a single gas supply line, in particular a single stranded gas supply line. This in particular shall mean that the ducting via the automatic gas valve 5 is the only possibility to feed or supply gas to the gas injector 3 or gas burner 2. There are no bypass gas lines or additional bypass gas valves allowing gas supply to the gas burner 2.

(9) A gas supply line connected to the automatic gas valve 5 for the purpose of feeding gas from a reservoir to the automatic gas valve 5 in the present case is also implemented as a single stranded gas supply line. However, it is possible that several gas supply lines are provided for supplying gas to the automatic gas valve 5. For the present embodiment it is of importance, that the connection between the single automatic gas valve 5 and the single gas injector 3 is implemented as a single gas supply line 4. This in particular has the advantage, that all operational modes of the gas burner 2 can be set, adjusted or controlled by adequately setting the state of the automatic gas valve 5.

(10) For setting respective operational modes of the automatic gas valve 5, the automatic gas valve 5 is connected to a control unit 6. The control unit 6 is adapted to set respective suitable opening states of the automatic gas valve 5. If required, an actuator (not shown) may be provided, adapted to actively set respective operational modes of the automatic gas valve 5.

(11) The control unit 6 in particular is adapted such that any of the above identified methods can be conducted.

(12) One exemplary method or operational mode that may be executed with the present gas burner 2 is schematically shown in the chart of FIG. 2.

(13) In the chart shown in FIG. 2 the course of flame level L is plotted against time t. After ignition (t=0), the gas burner 2 is operated at flame level L9, which corresponds to an ordinary operational mode of the gas burner 2. The other flame levels L1 to L8 also correspond to respective discrete ordinary operational modes of the gas burner 2. The flame level L9 in the present case is the highest flame level available for ordinary operational modes and the highest flame level in which the gas burner 2 can be operated continuously.

(14) After a first time period T1, which may be a preset period of time, the gas burner 2 is switched to a boost operational mode with a respective boost flame level LB. The boost flame level LB is higher than the maximal flame level L9. The boost flame level LB may be 125% of L9. The flame level L9 may for example correspond to an output power of 4 kW. In this case, the 125% boost output power is about 5 kW. Note that operation in boost mode in particular shall mean to operate the gas burner 2 at a power level higher than 100% of the possible continuous power output.

(15) The boost flame level LB is maintained for a second time period T2. The second time period T2 may be a maximal, preset time period allowed for the gas burner 2 to be operated in boost mode. Using the boost function, heating up of the cold gas burner 2 or reheating the gas burner 2 to a desired heat level can greatly be speeded up. The second time period may for example lie in the range of about 3 minutes.

(16) In the boost mode, the automatic gas valve 5 is driven to the fully opened state. As the maximal gas flow rate of the automatic gas valve 5 is larger than that of the gas injector 3, the overall gas flow rate is fixed by the maximal flow rate of the gas injector 3. Setting the absolute, maximal gas flow rate by properties of the gas injector 3 may simplify operation and control of the gas burner flame levels.

(17) After the boost operational mode in the second time period T2, in particular after the maximal allowable boost time, the control unit 6 drives the automatic gas valve 5 to a lower flame level, such as flame level L4 for example, in which for the duration of a third time period T3 an ordinary cooking operation may be performed. After the third time period T3, i.e. after having finished the cooking operation, the automatic gas valve 5 may be driven to flame level 0, corresponding to the off state of the gas burner 2.

(18) As may be recognized, the boost functionally as proposed herein can be implemented in an easy way and without great effort, in particular constructional effort. Further, comparatively short response times and uncomplicated, in particular software-based, control of the automatic gas valve 5 is possible.

(19) FIG. 3 shows a further operational mode of the gas burner 2. In this operational mode, the gas burner 2 is operated in an intermittent mode. In this mode, an initial ordinary operational mode at flame level L9 over a fourth time period T4 is followed by a boost operational mode over the time period T2. This sequence of non-boost and boost operational mode is repeated several times, and finally the flame level is set to flame level L0 in which the automatic gas valve 5 is closed. In this operational mode, the gas burner 2 can be operated with slightly enhanced power output, i.e. with a power output slightly above the nominal continuous power output.

(20) The boost mode may be conducted over the time period T2, which may be the maximal allowable time for boost operation. It shall be noted, that any other time intervals may be utilized. In between two boost operational modes, conventional or ordinary operational modes are carried out. The ordinary operational modes are adjusted and adapted such that overheating of the gas burner 2 despite operation in boost mode for an elongated period can be prevented. For operating the gas burner 2 in the intermittent mode, as shown in FIG. 3, the automatic gas valve 5 may be switched between the fully opened state and the partially closed state corresponding to the flame level L9. It shall be noted that other flame levels may be used in intermittent mode, in particular in dependence of the intended overall output power and allowable boost time and thermal loads.

(21) In all, it can be seen that the proposed gas burner 2 can be operated and controlled in a comparatively simple and easy way. Further, the gas burner 2 can be implemented with corresponding low constructional effort.

LIST OF REFERENCE NUMERALS

(22) 1 gas cooking appliance 2 gas burner 3 gas injector 4 gas supply line 5 automatic gas valve 6 control unit L flame level t time T1 first time period T2 second time period T3 third time period T4 fourth time period