EP1588099B1 - Gas cooker - Google Patents

Abstract

A control system for adjusting the heat output of at least one gas burner. The control system including at least one control organ in a gas main line feeding the gas burner for adjusting the gas throughput supplied to the gas burner nozzle. The control system further including at least one secondary line in parallel with the control organ with a shut-off organ for opening and closing the secondary line. The secondary line having a lower flow resistance than the flow resistance in the control organ line.

Description

The present invention relates to a gas hob. The gas hob has at least one gas burner and a control arrangement for setting a heating power of the gas burner. Furthermore, the control arrangement has at least one control element arranged in a gas main line to the gas burner, which adjusts a gas flow guided to a burner nozzle, and at least one auxiliary line running parallel to the control element with associated shut-off device for opening and closing the secondary line.

Out EP 0 818 655 a generic gas hob is known which has a valve control arrangement in a gas supply to a gas burner. In the valve control arrangement, the gas supply line branches into a number of parallel-connected partial gas lines, which are connected to the burner nozzle. In each partial gas line, a switching valve for switching on and off of the partial gas flow flowing through it and a throttle element for throttling the partial gas flow flowing through it are arranged. By combining certain switching elements switched on and off, a defined reduction of the gas flow can be carried out. When all throttle elements are open, the maximum gas flow is achieved.

The object of the present invention is to provide a gas hob with at least one gas burner whose control arrangement enables reliable burner operation.

The object is achieved by a gas cooking point with the features of claim 1. According to the characterizing part of claim 1, the at least one secondary line connected in parallel with a control element has a flow resistance limiting the gas flow rate in the secondary line. This is smaller than the flow resistance formed by the burner nozzle. A pressure drop in the gas flow through the secondary line is therefore greatly reduced. The greatly reduced pressure drop when the bypass is open leads to an improved primary air intake in the area of the Burner nozzle. The flame formation at the gas burner is therefore much more reliable at high gas flow rates.

The flow resistance in the secondary line can be determined in different ways. In a manufacturing technology simple realization of the invention, the decisive, the gas flow rate limiting flow resistance is determined by the smallest passage cross-section in the secondary line. The smallest passage cross section in the secondary line is thus dimensioned larger than the passage cross section of the burner nozzle.

It is advantageous if in a hotplate operation, the secondary line is open only for setting the maximum gas flow rate. The secondary line is therefore not used for setting partial gas flow rates. In this case, the flow resistance in the bypass may be reduced to a negligible extent with respect to the flow resistance in the gas main. Irrespective of whether the control element arranged in the gas main line is open or closed, the maximum gas throughput always occurs when the secondary line is open.

The control arrangement may preferably have a number of control lines connected in parallel to one another with corresponding control or regulating members. These branch off from the gas main line and can each guide a partial gas flow rate to the burner nozzle. Compared to conventional gas cocks, no hysteresis effects arise with such a control arrangement. The parallel control lines allow a much more accurate adjustment of the partial gas flow rate. The maximum gas flow rate is established when all control lines of the control arrangement are open. In this case, however, the pressure loss in the control arrangement is substantially greater than when using a conventional, fully open gas cock. As a result of the secondary line according to the invention, the pressure loss at maximum gas throughput can be effectively reduced, in particular in the case of this control arrangement.

As a shut-off or control organs in each case a switching valve with associated control throttle can be provided in the control lines. The control throttle serves the limitation the gas flow rate to a partial gas flow rate. In contrast to a proportional valve with continuous adjustment, the switching valve has only a closed and an open position.

To reduce the flow resistance in the secondary line, the number of fittings in the secondary line, such as the number of shut-off, control or regulating organs, limited to only one unthrottled obturator.

For reasons of space, it is advantageous if the control lines are combined in a housing, for example a valve block. Advantageously, the secondary line can be integrated in the housing of the control arrangement. A factory mounting of the controls or throttle elements is simplified when the throttle elements are removably inserted into mounting holes of the control lines of the housing of the control arrangement.

In a production technology particularly simple manufacturing process of the control arrangement, a conventional valve block is first prepared with a number of control lines. In the control lines - with the exception of at least one control line - throttle elements are used. The unthrottled control line forms the secondary line according to the invention.

Instead of a throttle element, the mounting opening of the unthrottled control line to be closed by a non-throttling closure element. Alternatively it can be mounted in the unthrottled control lines of the valve block, a throttle element whose passage cross-section is larger than the passage cross-section of the burner nozzle. From a manufacturing point of view, it is particularly advantageous if the assembly opening in the unthrottled control line is completely dispensed with in the production of the valve block.

Fig. 1

ein schematisiertes Blockschaltbild mit einem Gasbrenner einer Gaskochstelle und einer Steueranordnung;

Fig. 2

eine Durchflusscharakteristik der in der Fig. 1 gezeigten Steueranordnung;

Fig. 3

einen Ventilblock der Steueranordnung in einer Seitenansicht;

Fig. 4

der Ventilblock der Steueranordnung in einer Seitenschnittdarstellung;

Fig. 5

eine Schnittdarstellung entlang der Linie A-A aus der Figur 4; und

Fig. 6

eine Schnittdarstellung entlang der Linie B-B aus der Figur 4.

Hereinafter, an embodiment of the invention with reference to the accompanying figures will be described. Show it:

Fig. 1

a schematic block diagram with a gas burner of a gas hob and a control arrangement;

Fig. 2

a flow rate characteristic in the Fig. 1 shown control arrangement;

Fig. 3

a valve block of the control arrangement in a side view;

Fig. 4

the valve block of the control arrangement in a side sectional view;

Fig. 5

a sectional view taken along the line AA from the FIG. 4 ; and

Fig. 6

a sectional view taken along the line BB from the FIG. 4 ,

In the FIG. 1 is a highly schematic diagram of a belonging to a gas burner gas burner 1 shown. This is connected via a main line 3 with a gas pipeline network. In the main line 3, a control arrangement 5 is arranged. By means of the control arrangement 5, a gas flow rate to the gas burner 1 is set in accordance with a desired heat output of the gas burner 1. Not shown are the usual for the gas hob security elements, such as a thermocouple and an associated solenoid valve for safety shutdown of the gas burner when extinguishing a flame.

The control arrangement 5 has three control lines 7, 9, 11 connected in parallel and a secondary line 13 connected in parallel thereto. Both the control lines 7, 9, 11 and the secondary line 13 branch off from the main line 3 and then reunite to a burner feed line 15. This opens into a burner nozzle 14. In each of these lines 7, 9, 11, 13 is one electrically actuated magnetic switching valve 17 is arranged. The magnetic switching valves 17 are switchable from a closed position into an open position and can be activated via signal lines 19 by means of an electronic control device 21. Via the control device 21, a user can set heating power levels of the gas burner 1. As later from the FIG. 2 is described, is set in accordance with the selected Heizleistungsstufe a partial gas flow rate Q ₁ to Q ₇ to the maximum gas flow rate Q ₈ .

The control device 21 can control the magnetic switching valves 17 independently of each other. The arranged in the control lines 7, 9, 11 solenoid valves 17 are throttle elements 23, 25, 27 connected downstream. The Indian FIG. 6 indicated diameter d _{1 of} each throttle element 23, 25, 27 determines its passage cross-section. The diameters d ₁ in the control lines 7, 9, 11 are designed to be substantially smaller than a passage cross-section of the burner nozzle 14. Thus, in the present case, the diameter of the burner nozzle 14 in about 0.5 mm. The throttle diameter d _{1 of} the throttle elements 23, 25, 27 is between 0.1 and 0.3 mm.

In contrast to the control lines 7, 9, 11, the secondary line 13 is unthrottled. As a result, the flow resistance in the unthrottled secondary line 13 is reduced as much as possible. Opposite the control lines 7, 9, 11, the pressure loss through the opened secondary line 13 is negligible. When the secondary line 13 is open, the maximum gas throughput Q _{8 is} therefore passed through the secondary line 13 without any significant pressure loss. To reduce the flow resistance of the passage cross section in the secondary line 13 is dimensioned substantially larger than the passage cross section of the burner nozzle 14th

The passage cross sections of the throttle elements 23, 25, 27 are designed factory. In the present case, about 65% of the maximum gas flow rate is conducted to the burner nozzle 14 when the control lines 7, 9, 11 are open. In this case, the first throttle element 23 allows about 20%, the second throttle element 25 about 24% and the third throttle element 27 about 30% of the maximum gas flow rate. By means of the three control lines 7, 9, 11 resulting combinations of the open and closed positions of the solenoid valves 17 in the three control lines eight (ie, 2 ³ ) Heizleistungsstufen with the different partial gas flow rates 0 and Q ₁ to Q _7th The heating power levels are adjustable by means of the electronic control device 21. The partial gas flow rates Q ₁ to Q ₇ go from in the FIG. 2 shown flow characteristic of the control assembly 5. If the user selects the eighth heating power stage, then the electronic control device 21 opens the solenoid valve 17 in the secondary line 13. As a result, the maximum gas flow rate Q ₈ to the burner nozzle 14 is set.

According to the flow characteristics in the FIG. 2 increase the partial gas flow rates Q ₁ to Q _{7 of} the heating power levels 1 to 7 almost linearly to about 62%. After the solenoid valve 17 is connected in the secondary line 13 in the open position, a disproportionate Heizleistungssprung of Q ₇ takes place up to the maximum gas flow rate Q _8th The disproportionate increase from the partial gas flow rate Q ₇ to the maximum gas flow rate Q ₈ results in an approximately exponential profile of the flow characteristic. Such an exponential course is particularly advantageous in terms of application technology.

In the following FIGS. 3 to 6 the structural design of the control arrangement 5 is explained. As a result, both the control lines 7, 9, 11 and the secondary line 13 are integrated in a housing 33 shaped as a compact valve block. The valve block 33 made of plastic has on one side a semi-circular in side view inlet port 35. This sits positively on an outer circumference of the pipe designed as a main line 3. By means not shown retaining clips, the main line 3 is gas-tight pressed to the inlet port 35. Opposite the inlet port 35, an outlet port 37 is formed on the valve block 33. In the outlet port 37, the burner supply line 15 is inserted gas-tight. Furthermore, according to the FIG. 3 four solenoid valve heads 39 of the solenoid valves 17 are mounted in the valve block 33. On the opposite side, the throttle element 23, 25, 27 shown inserted into the valve block.

In the FIG. 4 the valve block 33 is shown in a side sectional view. The region of the inlet connection 35, 37 is shown in a first sectional plane X. Parallel to this, in a second sectional plane Y, the central area of the valve block 33 between the inlet and outlet ports 35, 37 is shown. In a third sectional plane Z of the region of the outlet port 37 is shown. From the FIG. 4 shows that in the valve block 33 to each other opposite horizontal blind holes 41, 43 extend. These each open into the inlet port 35 and into the outlet port 37 of the valve block 33 and are aligned parallel to each other. The control lines 7, 9, 11 connect the inlet bag bore 41 with the outlet bag bore 43.

In detail, each of the control lines 7, 9, 11 has a valve channel 45. The valve channel 45 extends perpendicular to the horizontal blind holes 41, 43. A channel end of the valve channel 45 opens into a circular recess 51, which in Valve block 33 is incorporated. The circular recess 51 forms a valve seat for a valve plate 53 of the solenoid valve head 39, as shown in the FIG. 4 indicated by dashed lines. In the recessed valve seat 51 opens according to the FIGS. 5 and 6 In addition, a first passage channel 55 with a small diameter, which leads to the inlet bag bore 41. At the same time, the valve channel 45 is connected to the outlet bag bore 43 via a second passage 57. Each of the control lines 7, 9, 11 extending between the blind bores 41, 43 is consequently formed by the first passage 55, the valve passage 45 and the second passage 57.

In the closed position of the solenoid valves 17, the valve plate 53 of the solenoid valve heads 39 is located on the recessed valve seat 51. Thus, the valve channel 45 of the corresponding control line is closed, whereby the control line is closed as such. In the open position of the solenoid valve 17, the valve plate 53 is out of engagement with the valve seat 51. In this case, the corresponding control line is open.

Opposite the recessed valve seat 51 opens each of the valve channels 45 in a mounting hole 59. In the mounting hole 59, the throttle elements 23, 25, 27 can be mounted, as shown in the FIG. 6 is indicated. According to the FIG. 6 the throttle element 25 is designed as an insert nozzle. This can be screwed into the mounting opening 59 of the valve channel 45.

Based on FIG. 5 the configuration of the secondary line 13 in the valve block 33 is explained below. As the control lines 7, 9, 11 and the secondary line 13 extends within the valve block 33. The secondary line 13 is formed according to the control lines through the first passageway 55, the valve channel 45 and the second passageway 57. In contrast to the control lines, however, the secondary line 13 is unthrottled. That is, that no insert nozzle 25 is arranged in the secondary line 13. As a result, the largest possible passage cross section in the secondary line 13 is achieved. In the secondary line 13 of the gas flow rate limiting flow resistance is formed by the first passageway 55. The diameter d _{2 of} the passage channel 55 is about 1.5 to 2 mm. Thus, the diameter d _{2 of} the first passageway 55 is considerably larger than the diameter of the burner nozzle 14. Instead of an insert nozzle is according to the FIG. 5 in the mounting opening 59 of the secondary line 13, a closure element 61 is inserted. This closes the mounting opening 59, without throttling the secondary line 13. Alternatively, the closure member 61 may be omitted when the factory production of the valve block 33 is completely dispensed with the mounting hole in the secondary line 13. In this case, the secondary line 13 is closed in the region of the mounting holes 59 in the valve block 33, without the secondary line 13 is throttled.

With the present control arrangement 5, it is also possible, by cyclically switching on and off of the solenoid valves 17 of the control lines 7, 9, 11 to achieve small continuous heating powers on the gas burner 1. It is advantageous that in the control arrangement 5, a re-ignition at each preset heating power can be done very reliable.

Claims (13)

1. Gas cooking point with at least one gas burner (1) and a control arrangement (5) for setting a heat output of the gas burner (1), which control arrangement comprises at least one control element (23, 25, 27), which is arranged in a gas main line (3, 15) to the gas burner (1) and which sets a gas throughput (Q₁ to Q₈) to be conducted to a burner nozzle (14), and at least one secondary line (13), which extends parallel to the control element, for the burner nozzle (14) with an associated blocking element (17) for opening and closing the secondary line (13), characterised in that the flow resistance, which limits the gas throughput, in the secondary line (13) is formed to be lower than the flow resistance formed by the burner nozzle (14).
2. Gas cooking point according to claim 1, characterised in that the flow resistance limiting the gas throughput is formed by the smallest passage cross-section in the secondary line (13).
3. Gas cooking point according to claim 1 or 2, characterised in that the smallest passage cross-section in the secondary line (13) is formed to be larger than the passage cross-section of the burner nozzle (14).
4. Gas cooking point according to any one of the preceding claims, characterised in that the secondary line (15) is opened at least at the time of the setting of a maximum gas throughput (Q₈).
5. Gas cooking point according to claim 4, characterised in that the secondary line (13) is closed at the time of setting of a part gas throughput (Q₁ to Q₇) and is opened only when the maximum gas throughput (Q₈) is set.
6. Gas cooking point according to any one of the preceding claims, characterised in that the blocking element (17) for opening and closing the secondary line (13) is constructed as an unthrottled switching valve.
7. Gas cooking point according to any one of the preceding claims, characterised in that the control arrangement (5) comprises a number of control elements (23, 25, 27), which are connected in parallel and which are provided in control lines (7, 9, 11) branching off from the main line (3, 15).
8. Gas cooking point according to claim 7, characterised in that the control lines (7, 9, 11) and the secondary line (13) are formed in a common housing (33).
9. Gas cooking point according to one of claims 7 and 8, characterised in that the control and secondary lines (7, 9, 11, 13) each have a mounting opening (59) for insertion of the control elements (23, 25, 27).
10. Gas cooking point according to claim 9, characterised in that the mounting opening (59) of the secondary line (13) is closed by, for example, a closure element (61).
11. Gas cooking point according to any one of the preceding claims, characterised in that the control arrangement (5) is so designed that the part gas throughputs (Q₁ to Q₇) up to approximately 60% of the maximum gas throughput (Q₈) increase at a substantially constant first gradient.
12. Gas cooking point according to claim 11, characterised in that the part gas throughputs (Q₁ to Q₇) from approximately 60% of the maximum gas throughput (Q₈) to the maximum gas throughput (Q₈) increase at a second gradient greater than the first gradient.
13. Gas cooking point according to any one of the preceding claims, characterised in that when the maximum gas throughput (Q₈) is set the main line, particularly the control lines (7, 9, 11) branching off the main line (3, 15), is or are open.

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