Description
Gas burner assembly and gas cooking appliance
The present invention is related to a gas burner assembly and a gas cooking appliance comprising a respective gas burner assembly.
Some types of gas burner appliances are implemented to comprise several gas burners that are operable by separate power control tabs. Under certain conditions, such for example in case that the gas burners are arranged in a common cooking compartment or chamber, it can be advantageous to allow only operation of one of the gas burners at a time. This may for example be required to avoid exceedance of the maximal heating power output of the burners arranged within the common compartment. It is an object of the invention to provide a comparatively cost efficient, cheap and simple way or possibility to operate a gas burner assembly according to the advantageous way as described beforehand. In particular, comparatively cost efficient, cheap and simple possibilities shall be provided to operate a gas burner such that only one of the gas burners can be operated at a time.
This object in particular is solved by claims 1 and 10. Advanta¬ geous embodiments and variants in particular result from the de- pendent claims, and may also result from the following detailed description of the invention.
According to claim 1, a gas burner assembly is provided which comprises a first gas burner and second gas burner. Each of the first and second gas burner in particular may comprise a gas control tab for setting or adjusting an operational burner power level of the first or second control tab. The control tab may be connected via a shaft with a gas supply valve adapted to supply gas to a respective gas burner in ac¬ cordance with the control tab setting. Each gas supply valve may comprise a thermocouple flame supervision device or sensor ar¬ rangement adapted to shut off the gas supply valve in in absence of a flame or in case that a respective gas burner fails to gen¬ erate adequate heating power.
The thermocouple flame supervision device may comprise a thermo¬ couple generating a thermoelectric voltage in case that gas is burnt at the respective gas burner and generates heat, i.e. in case that a flame as a result of the control tab setting and ig¬ nition is present. In case that there is no flame and no gas is burnt, no thermoelectric voltage is generated. The absence of a thermoelectric voltage may be used as a trigger signal to shut off the gas supply valve for safety reasons.
The proposed gas burner arrangement further comprises an elec¬ tric interlock mechanism. The electric interlock mechanism is adapted and configured to disable operation of the second gas burner in case that the first gas burner is in operation, i.e. in an ON-state.
The electric interlock mechanism comprises an electric switching unit for electrically interrupting and closing an electric con- trol or signal line of a thermocouple flame supervision device of the second gas burner.
Further, the switching unit is mechanically coupled to a gas control tab of the first gas burner such that the switching unit interrupts the control line, in particular interrupts conductiv¬ ity of the control line, in any ON-position of the control tab, i.e. in any position of the control tab corresponding to a posi¬ tive burner power and/or corresponding to an activated state of the respective gas burner.
Further, the mechanical coupling between the switching unit and the control tab is such that the switching unit closes the con¬ trol line, or establishes electric conductivity of the control line, in the OFF-position of the control tab, i.e. in the posi¬ tion of the control tab corresponding to Zero burner power of the OFF-state of the respective gas burner.
In particular it may be realized that the functioning of the electric interlock mechanism based on a combined mechanical and electrical interaction between the gas control tab for setting a gas burner power, the switching unit, which is coupled to the control tab, and the thermocouple control line, which is inter¬ connected with the switching unit, are effective in solving the underlying problem.
Using a mechanical and electrical coupling between the control tab and thermocouple flame supervision device as proposed by the invention has turned out to be a comparatively powerful, yet easy and cheap possibility to implement an electric interlock mechanism, which is configured to allow operation of only one gas burner at a time. The invention in particular is applicable to embodiments in which both the first and second gas burner comprise a control tab for setting the respective gas burner power. It shall be mentioned, that the tab may also be adapted to manually trigger an igniting action for igniting gas supplied to a corresponding gas burner. In embodiments, the electric switching unit may comprise a pair of switching contacts electrically intercoupled with or into the control line of the thermocouple flame detection device. The in- tercoupling between the control line and the switching contacts may be such that in case that the switching contacts are in con¬ tact with each other, the control line can conduct electricity, and in case that the switching elements are disconnected from each other, the control line is interrupted, i.e. electric con¬ ductivity is disabled.
Further, the switching unit may comprise a switching element that may be mechanically coupled to a shaft of the control tab related to power setting control of the first gas burner. The shaft in particular may be configured and connected to the con- trol tab such that the control tab is able to be rotated around the shaft for setting a certain burner power level. The shaft hence is a kind of pivotal support for the control tab, and may be mechanically connected to the gas supply valve of the first gas burner so as to set the valve position in accordance with the selected burner power level.
The mechanical coupling in the proposed embodiment may be such that the switching element interrupts the control line by, in particular electrically, disconnecting the switching contacts from each other in rotational positions of the shaft correspond¬ ing to any ON-position of the control tab. Interrupting the control line will disable thermoelectric voltage generated by the thermocouple of the flame supervision device to be transmitted to the gas supply valve, and this, according to the intended function of the supervision device, will shut-off the second gas burner. Therefore, as soon as the first control tab is set or positioned in a configuration corresponding to an activated state of the first gas burner, the second gas burner is deac¬ tivated, or, if activated, if may be shut-down. Further, the mechanical coupling may be such that the switching element closes the thermocouple control line or circuit by, in particular electrically, connecting the switching contacts or bringing the switching contacts into electrical contact with each other for or in case of rotational positions of the shaft corresponding to the OFF-position of the control tab.
The OFF-position shall, as already mentioned, correspond to the OFF-position of the gas burner, i.e. to the Zero power level.
Using such a combined mechanical and electrical combination leads to a comparatively robust and reliable configuration of the electric interlock mechanism. Beyond that, a respective electric interlock mechanism can be implemented with compara¬ tively simple mechanical and electrical components, and thus may be implemented in a comparatively cost efficient way.
In further embodiments of the gas burner assembly, the shaft may comprise a radially protruding section, which in particular may be implemented to be rotatable in concert or together with the shaft, i.e. the protrusion may rotate in concert with the shaft.
The protruding section may comprise a circumferential contour configured and designed to cooperate with a switching plunger of the switching element. The cooperation as well as the design of the protruding section, and the design, position, and orientation of the plunger may be such that the switching element is moved via the plunger between the opened and closed position to interrupt and close, i.e. connect and disconnect, the control line in accordance with the ON-position and OFF-position of the control tab. The proposed mechanical interaction using a circumferential con¬ tour cooperating with a plunger of the switching element constitutes a comparatively robust and reliable mechanism, which in particular can be implemented with conventional mechanical and electrical component parts.
In further embodiments, the radially protruding section may be implemented as or by means of an eccentric or cam wheel attached to the shaft. The attachment may be such that in the OFF- position of the control tab an apex of a cam or eccenter of the cam wheel or eccentric wheel faces and acts on the switching plunger. The action of the apex on the plunger or action between the apex and the plunger may be such that the switching element is in the closed position in case that the corresponding or re- lated control tab is the OFF-position . This means that the con¬ trol line of the thermocouple flame supervision of the second device is active, i.e. electrically conducting, and that the second gas burner can be activated or operated. In further embodiments, the eccentric wheel or cam wheel may comprise an axial hub, in particular an axial through hole. The shaft of the control tab in these embodiments may be inserted into the shaft, which in particular shall mean that the shaft may be pushed through the hub and/or the eccentric or cam wheel may be pushed over the shaft. Preferably, the hub and shaft are attached to each other in a torsion-proof manner via a shaft- hub-connection. The proposed configuration in particular is suitable to use standard component parts, or even component parts as already used in known gas burner control units. Hence a comparatively easy and cost efficient implementation of the in¬ vention may be possible. The eccentric wheel or cam wheel may be made from a plastic ma¬ terial. However, also other materials may be considered such as metals like aluminum and the like. In embodiments of the invention, each of the first and second gas burner may comprise a gas control tab for setting the power level of the first and second gas burner, respectively. Each gas control tab may be coupled, via a respective shaft, to a gas supply valve adapted to supply gas to the gas burner in accord- ance to a set power level. An application of the invention to gas burner assemblies using separate control tabs for the first and second gas burner represents a comparatively efficient way to implement an electric interlock mechanism to respective ap¬ pliances .
In variants, in particular of the aforementioned embodiment, the electric interlock mechanism may further be adapted to disable operation of the first gas burner, in particular transfer it to the OFF-position, in case that the second gas burner is in oper- ation, i.e. in the ON-position. In particular in this case, a further switching unit may be mechanically coupled to the shaft of the control tab of the second gas burner and electrically in- tercoupled with a further control line of a further thermocouple flame supervision device of the first gas burner such that the further switching unit interrupts the further control line in any ON-position of the control tab of the second gas burner and closes or connects the further control line in the OFF-position of the control tab of the second gas burner. In particular in this configuration, only a single one of the gas burners can be operated at a time, and activation of one of the gas burners will result in deactivation or shut-down of the respective other gas burner. Hence, a comparatively secure electric interlock mechanism can be implemented. The invention in particular may be applied to gas burner assemblies in which an oven gas burner and a grill gas burner accommodated in a common cooking compartment are used or implemented as the first and second gas burners. In particular with such de- vices and arrangements of gas burners, problems may arise with limiting the sum of the heating powers of the gas burners. The invention as described herein may solve this problem in particu¬ lar in providing a possibility to limit limiting the operation of the gas burners to one at a time. Here, the invention estab- lishes a comparatively effective, robust and reliable solution.
According to claim 10, a gas cooking appliance is provided, which comprises a gas burner assembly as described above, in or according to any embodiment and variant thereof. As to ad- vantages, reference is made to the description above.
The gas cooking appliance in particular may comprise or be re¬ lated to a cooking and/or baking gas burner assembly, in partic¬ ular of domestic, household or industrial type, preferably adapted for treatment, baking, cooking and the like of food and foodstuff .
Embodiments of the invention will now be described in connection with the annexed figures, in which:
FIG 1 schematically shows details of the electric and me¬ chanic configuration and constitution of a gas burner assembly; FIG 2 shows a gas control tab together with a switching
unit ;
FIG 3 shows a detail of the switching unit in a first con¬ figuration; and FIG 4 shows a detail of the switching unit in a second con¬ figuration
FIG 1 schematically shows details of the electric and mechanic configuration and constitution of a gas burner assembly 1.
The gas burner assembly 1 comprises a first gas burner 2 and a second gas burner 3, which are represented by different geomet¬ ric figures in FIG. 1. The gas burners may be of different type, as mentioned further above. But it is also possible that the gas burners are of the same type.
The gas burner assembly 1 further comprises an electric inter¬ lock mechanism, which will be described in more details further below, and which is adapted block one of the gas burners in case that the other one of the gas burners is in the ON-state. In more details, the interlock mechanism blocks or disables the first gas burner 2 in case that the second gas burner 3 is in or is transferred to the active, i.e. ON-state, which also applies vice versa.
The ON-state in particular shall mean a state in which the gas burner is operating, and/or in which at least a power level is set and the gas burner is ready for being ignited.
The first gas burner 2 comprises a first control tab 4a rotata- bly suspended on a first shaft 5a which is mechanically coupled to a first gas supply valve 6a. The first gas supply valve 6a is connected to the first gas burner 2 via a first gas supply line 7a adapted to feed gas to the first gas burner 2.
The first gas burner 2 further comprises a first thermocouple flame supervision device which in the present case is schemati- cally represented by its (first) control line 8a in a dotdashed drawing line. The first flame supervision device comprises a thermocouple (not explicitly shown) arranged at the first gas burner 2.
During operation of the first gas burner 2 heat is generated which causes the thermocouple to generate a thermoelectric volt¬ age. The thermoelectric voltage is fed back to the first gas supply valve 6a, which is kept open as long as thermoelectric voltage is generated. In case that the thermoelectric voltage ceases or drops to Zero, which is indicative of an absence of a burning flame at the first gas burner 2, the first gas supply valve 6a is closed or shut so as to avoid undesirable escape of gas .
The interlock mechanism further comprises a first switching unit 9a which is mechanically coupled to the first shaft 5a.
In a similar constitution as compared to the first gas burner 2, the second gas burner 3 comprises a second control tab 4b rotat- ably suspended on a second shaft 5b which is mechanically cou¬ pled to a second gas supply valve 6b. The second gas supply valve 6b is connected to the second gas burner 3 via a second gas supply line 7b adapted to feed gas to the second gas burner 3.
The second gas burner 3 further comprises a second thermocouple flame supervision device which in the present case is schemati¬ cally represented by its control line 8b as a dotdashed drawing line. Except that the second thermocouple flame supervision de¬ vice is coupled to the second gas burner 3, the function of it is essentially the same as that of the first thermocouple flame supervision device, and its function is not described in detail again . The interlock mechanism further comprises a second switching unit 9b mechanically coupled to the second shaft 5b. The first and second switching units 9a and 9b, respectively are electrically interconnected via two first 10a and two second 10b electric branch lines 10 into the second control line 8b and in¬ to the first control line 8a. In more detail, the first switching unit 9a is connected by one of the first branch lines 10a to a first free end 11 at an elec¬ trical disconnection of the second control line 8b, and is con¬ nected by the other one of the first branch lines 10a to a sec¬ ond free end 12 at the electrical disconnection of the second control line 8b.
Further, the second switching unit 9a is connected by one of the second branch lines 10b to a first free end 11 at an electrical disconnection of the first control line 8a, and is connected by the other one of the second branch lines 10b to a second free end 12 at the electrical disconnection of the first control line 8a.
FIG 2 shows a gas control tab 4 which may correspond essentially to either one of the first and second control tabs 4a and 4b. The control tab 4 is supported on the shaft 5 to be rotatably around the longitudinal axis of the shaft 5. The actual power setting of the control tab 4 is indicated via a vertical arrow given at the top of the control tab 4. In the present case, the power setting of the control tab 4 is "Zero" which corresponds to the OFF-state of the gas burner. By rotating the control tab 4 in clockwise or counter-clockwise direction the power levels I to III can be set by the control tab 4. Note that the indicated power levels are only schematic and examples, and may vary in number and appearance, in particular design. The shaft 5 is me¬ chanically coupled to the gas supply valve 6 in order to trans¬ mit, via the shaft 5, the power setting to the gas supply valve 6 and to set a corresponding valve position.
From FIG 2 the mechanical coupling between the switching unit 9 and the shaft 5 can be seen in more details. The shaft 5 com¬ prises a cam 13 that is attached and anti-turn locked to the shaft 5. The cam 13 in the OFF-state of the control tab 4 coop- erates with a plunger 14 of a switching element 15 of the switching unit 9. The plunger 14 is held to be moveably in axial direction in the switching element, which motional degree of freedom is indicated by a double arrow. In the configuration as shown in FIG. 2, the plunger 14 is pushed inwards by the cam 13 such that switching contacts 16 are brought in contact, which means that the switching element 15 is closed.
As can be derived from FIG 2, rotating the control tab 4 out of the position as depicted in FIG 2 will also rotate the cam 13, which will allow the plunger 14 to be moved out, and which will open the switching element 15 by electrically disconnecting the switching contacts 16. Therefore, in any ON-position or ON-state of the control tab 4, the switching element 15 is open. Note that the plunger 14 may be biased by a spring force to be urged outwards, i.e. to disconnect the switching contacts 16 in case that no counter-force acts on the plunger 14.
FIG 3 and FIG 4 show details of the switching unit 9 in a first and second configuration.
FIG 3 corresponds to the situation in FIG 2. The control tab 4 is positioned or turned into the OFF-state such that the cam 13, via the plunger 14, closes the switching element 15, i.e. brings the switching contacts 16 in electric contact.
FIG 4 corresponds to a situation in which the control tab 4 is moved out of or from the OFF-state into an ON-state, which in the present case may be power level III, for example. In any ON- state of the control tab 4, the cam will enable the plunger 14 to move outwards, i.e. to be released. As a consequence, the switching contacts 16 will be disconnected, and the switching element will be in the open state, and electrical contact be¬ tween the switching contacts 16 will be interrupted.
The switching contacts 16 of the switching element 15 are re¬ spectively electrically connected to one of the first electric branch lines 10a in case that the first switching unit 9a is considered, and are respectively connected to one of the second electric branch lines 10b in case that the second switching unit 9b is considered. Note, that the first electric branch lines 10a are connected to first and second free ends 11, 12 of the second control line 8b, and that the second electric branch lines 10b are connected to the first and second free ends 11, 12 of the first control line 8a.
In FIG 4, the cam is implemented as a cam wheel 17 with an axial hub and positioned on or pushed over the shaft 5. As can be seen from FIG 4, the cam wheel 17 is attached to the shaft 5 in a torsion-proof manner by a shaft-hub-connection.
The cam 13 as shown in FIG 3 may for example be an integrated part of the shaft 5, or also implemented as a cam wheel. As can be deduced from the above description, the electric in¬ terlock mechanism functions or acts as follows:
If, for example the first control tab 4a of the first gas burn- ers 2 is in the OFF-state, the second control line 8b of the second gas burner 3 is closed and the thermocouple flame super¬ vision device of the second gas burner functions in the ordinary and normal mode. This means, that the second gas burner 3 can be activated and freely operated in all power levels.
However, if in this situation the fist control tab 4a is also moved into an ON-state, the joint mechanical action of the cam 13 and plunger 14 will open, i.e. interrupt, the second control line 8b. This in turn will have the effect that no thermoelec- trie voltage is delivered to the second gas supply valve 6b,
Missing thermoelectric voltage will lead to a closure or shut¬ down of the second gas supply valve 6b in accordance with the ordinary operation and functioning of the thermocouple flame su¬ pervision device. The same applies mutatis mutandis if the fist gas burner 2 is ON and it is tried to activate the second gas burner 3.
As can be seen, by the modified construction of the thermocouple flame supervision device as proposed herein, an electric inter- lock mechanism can be implemented that allows operation of only one gas burner at a time, which may greatly contribute to opera¬ tional safety. Further, it can be seen that the proposed solu¬ tion can be implemented in a comparatively easy and cost effi¬ cient, yet robust and functionally reliable way. List of reference numerals
1 gas burner assembly
2 first gas burner
3 second gas burner
4a, b. first and second control tab
5a, b first and second shaft
6a, b first and second gas supply valve
7a, b first and second gas supply line
8a, b first and second control line
9a, b first and second switching unit
10a, b first and second electric branch line
11 first free end
12 second free end
13 cam
14 plunger
15 switching element
16 switching contacts
17 cam wheel