WO2009040243A2

WO2009040243A2 - Gas cooktop

Info

Publication number: WO2009040243A2
Application number: PCT/EP2008/061911
Authority: WO
Inventors: Christophe Cadeau; Emmanuel Mastio; Martin Oberhomburg
Original assignee: BSH Bosch und Siemens Hausgeräte GmbH
Priority date: 2007-09-21
Filing date: 2008-09-09
Publication date: 2009-04-02
Also published as: WO2009040243A3; CN102066841A; CN102066841B

Abstract

The gas cooktop is equipped with a first gas supply line to a gas burner, the gas flow rate of which can be controlled using an on-off valve, and with a control unit for alternately opening and closing the on-off valve in at least one temperature regulation operating mode. A further gas supply line to the gas burner is provided, which is particularly equipped with a throttle unit, the further gas supply line being set up such that a gas flame on the gas burner is not extinguished in the temperature regulation operating mode when the on-off valve is closed.

Description

description

Gas Cooking

The invention relates to a gas hob, a method for controlling the temperature in gas cooking and a use of the method.

JP 1291018 A describes a gas hob with a Gasbren- ner and a gas supply to the gas burner, which with a

Gas valve is equipped. A temperature sensor is used to detect a cooking temperature at the gas cooking point and is connected to a control device which is set up to control the gas valve. When a cookware is to be heated to the predetermined cooking temperature, the controller controls the cooking temperature by turning off the burner when the temperature is exceeded. Upon subsequent cooling below a lower temperature threshold, the burner is ignited again. The disadvantage here is that comparatively much carbon monoxide (CO) is produced. In addition, there is a loss of efficiency with regard to the amount of gas to be applied.

JP 2230023 A describes a gas hob, in which a regulation of a cooking temperature is achieved by means of a controllable proportional valve. The proportional valve is controlled such that, depending on a temperature detected by a temperature sensor cooking temperature, the intensity of the gas flame is alternately increased and decreased, but it is not turned off. As a result, release of a larger amount of CO is avoided. The disadvantage here is that a proportional valve is comparatively complicated and expensive.

The object of the invention is to provide a possibility for simple and inexpensive temperature control at a gas Cook parts provide at the same time low CO emissions.

This object is achieved by a gas cooking station with according to claim 1, a method according to claim 7 and a use of the method according to claim 10. Advantageous embodiments are in particular the dependent claims.

The gas hob, in particular gas stove, has for this purpose a first gas supply line to a gas burner, whose gas flow is controllable by means of an on / off valve, and a control device for selectively opening and closing the on / off valve in at least one temperature control mode. Furthermore, a further gas supply to the gas burner is present, which is equipped with a throttle device, wherein the throttle device is arranged so that in the temperature control mode with a closed on / off valve, a gas flame at the gas burner does not go out.

The throttling device may be any device which can significantly restrict a gas flow, such as a valve, in particular a proportional valve, or a pipe constriction. By means of the activation or deactivation of the temperature control mode, an operator can set or issue an automatic temperature control at the cooking zone, in particular for cooking, frying, frying etc. at a substantially constant temperature of the cookware or the food contained therein. If the temperature control mode is deactivated, it is possible, for example, to cook with a customary manual setting of the gas flow adjustment elements, typically the gas adjustment toggle.

The above gas hob has the advantage that instead of an expensive proportional valve, a low-cost on / off valve is used and still the gas flame always burns, which keeps the CO emissions low. For this purpose, the gas cooking point or the gas stove advantageously has a temperature sensor and a control device connected to the temperature sensor for regulating a gas flow rate to the gas burner by switching the gas burner on and off

On / off valve in at least the temperature control mode.

In other words, the gas hob has two gas supply lines connected in parallel with one another. In a gas supply lines, the on / off valve is arranged, which for temperature control, for. B. is dependent on a temperature detected by the temperature sensor compared to a target temperature, alternately opened and closed. In the other of the gas supply lines, a throttle device is arranged, which allows a throttled gas flow regardless of the respective current switching state of the on / off valve. In this way it can be ensured that a sufficient gas flow always flows to the burner for obtaining a particularly small gas flame.

This device can be embodied particularly simply by arranging the on / off valve in parallel and a gas throttle, which can in particular be operated independently of other other user-controllable control and throttle devices.

However, it may be preferred if the throttle device comprises a - in normal operation - operator-operable gas valve, z. B. the conventional gas tap whose flow opening is adjusted by means of the usual control knob. Alternatively or additionally, a motor-controlled gas valve can be used. The associated gas supply branch corresponds with the use of the gas tap thus the usual gas supply in manual mode. This version has the advantage that for automatic temperature control only a small constructive modification of conventional gas stoves or gas hobs is needed.

Alternatively, it may be preferred if the throttle device comprises a non-operator-operable throttle valve and additionally an operator-actuable gas valve is connected in series both to the first gas supply line and to the further gas supply line, that is upstream or downstream. This can u. a. a simple structure and possibly achieve a different control characteristic.

The non-operator operable throttle valve is preferably as a not in normal operation, but z. B. ex works or by an installer in the maintenance operation, depending on a locally customary gas pressure or gas type adjustable gas valve designed. Alternatively, a non-adjustable gas throttle may be provided, which is then preferably dimensioned so that it keeps the flame alive even at different gas pressures and / or gas types. This may possibly result in a higher consumption.

In addition, a gas cooker with additionally a mode setting element for selectively switching on or off the control mode, wherein the control device is adapted to hold the on / off valve with the temperature control mode is in a predetermined position, which is the usual manual adjustment of the gas flow allowed to the burner. For example, in the variant described above, the on / off valve in parallel with the user-operable gas valve when the temperature control mode is switched off, the on / off valve permanently off, so locked. By contrast, in the variant described above, the on / off valve connected in series with the user-operable gas valve when the temperature control mode is switched off permanently switches the on / off valve open. Furthermore, a presence of a temperature setting element for setting a setpoint temperature at the gas hob or on the cookware is preferred. Preferably, the temperature adjustment element comprises the operator-actuated gas flow adjustment element. As will be explained in more detail below, the gas supply characteristic can firstly be changed directly and without further elements (in particular, the height of the gas stream in the temperature control mode to the burner), and secondly, for example, from the detection of the rotational position of the control knob on the target temperature to be controlled be concluded of the control loop.

Preferably, the gas stove or the gas hob on other display elements for displaying the set temperature or temperature level.

For accurate and fast responding temperature control during the temperature control mode, the maximum gas flow through the further gas supply line is less than through the first gas supply line and is preferably not more than about 2/3 of the gas flow through the first gas supply line, preferably more than 50%, more preferred not more than 30%, in particular preferably more than 20%. Especially preferred is a ratio of about 1/4%.

During the temperature control mode, a maximum gas flow through the additional gas feed, which corresponds to a heat output of at least 400 W, is sufficient, which is sufficient for a typical standard burner for operation on the smallest flame. Then, a gas flow through the first gas supply line is preferred, which corresponds to about 1600 W, resulting in a total gas flow with a capacity of about 2000 W. In the method for controlling the temperature in gas cooking, a cooking temperature is controlled by alternately opening and closing an on / off valve, which is arranged at a first gas supply to the gas burner. In this case, when the on / off valve is closed, a gas stream sufficient at least for obtaining a gas flame burning on it is supplied via a further gas line connected in parallel, in particular throttled, to the first gas supply line.

Preferably, gas is supplied to the gas burner via the first gas supply line through a throttle device for throttling a gas flow rate. The cooking temperature is preferably detected by means of a temperature sensor that touches the cookware. The gas flow rate to the gas burner is preferably regulated by means of a control device connected to the temperature sensor.

A nominal gas cooking point temperature is preferably set by adjusting an operator-controllable gas valve (ie, adjusting a gas passage opening of the gas valve), in particular the rotary knob typically present. This eliminates the need for a separate control element, which increases clarity and saves costs. The setpoint temperature can be adjusted, for example, depending on a rotational position of the setting element.

It is furthermore advantageous if the height of the gas stream which is sufficient at least for obtaining a gas flame burning at the gas burner is set by the operator-controllable gas valve.

For this purpose, the control device may preferably open the on / off valve when it falls below the measured temperature or a value associated therewith below a lower threshold value, and when the measured temperature or a value associated therewith is exceeded, an on-off valve is opened Threshold close the on / off valve. In general, all suitable control methods known to those skilled in the art can be used.

Particularly advantageous is the use of such a method for operating a gas hob described above.

Reference to the following embodiments, the invention will be explained schematically in more detail. Insofar as identical components or method steps can be used in various embodiments, identical reference symbols are used and a repeated description of such aspects is omitted. Show it:

1 schematically shows components of a gas hob of a gas range for controlling a cooking temperature;

FIG. 2 shows a plot, not true to scale, of a detected temperature and a gas flow rate to a burner over time for a device according to FIG

FIG. 1;

3 shows schematic circuit elements on a gas stove for

Setting a desired cooking temperature and control mode; and

4 shows a modified compared to FIG 1 embodiment.

1 shows a gas hob with a gas burner 1, on which a cookware 2, sketched as an example

Pan, can be heated. To heat the pan 2, a gas flame 3 burns on the gas burner 1. A gas supply to the gas burner 1 takes place starting from a gas connection 4 via gas lines and interposed valves and throttle devices. In known manner, the gas connection 4, a safety valve 5 is connected downstream, which the gas supply from the gas connection 4 completely releases or completely blocks. The safety valve 5 is controlled in the usual manner by a control device 6.

From the gas connection 4 or the downstream safety valve 5, a first gas supply line 7 branches off to the gas burner 1, which has an on / off valve 8. The on / off valve 8 can be controlled by means of the control device 6 in such a way that it selectively opens or closes the first gas supply line 7 unthrottled or only slightly throttling. From the gas connection 4, a further gas feed line 9 branches off parallel to the first gas feed line 7 to the gas burner 1. The further gas supply line 9 has a throttle device in the form of a known operator-controllable gas cock 10. Optionally, this may be an additionally motorized gas cock, which is adjustable by the control device 6, z. B. via a stepper motor. The two parallel gas supply lines 7, 9 unite in front of the gas burner 1 again.

The gas burner 1 also has a temperature sensor 11 which detects a cooking temperature T on the cookware 2. Preferably, the temperature sensor 11 touches the cookware 2 at the top in order to capture as accurately as possible the temperature prevailing on or in the cookware 2 (on the food). But there are also other temperature measurement methods used, for. B. based on infrared. The detected by the temperature sensor 11 gas cooking temperature T is transmitted via a suitable connection to the control device 6. There, the detected temperature T can also be further processed or adapted (eg calibrated), for. B. by means of conventional characteristics, optionally depending on the type and / or the model of the cookware. 2

In addition to the cooking temperature T, the control device 6 additionally receives a setpoint temperature set by an operator of the gas hob. In an optionally switchable and If the cooking temperature T is below an upper threshold value (which, for example, may also correspond to the setpoint temperature), the control device 6 opens the on-set temperature range On the one hand, an unthrottled, comparatively high gas flow mea is released through the first gas feed line 7 to the gas burner 1, and a comparatively considerably smaller, throttled gas flow md is guided through the second gas feed line 9 to the gas burner 1. This results in a booster-like effect because the instantaneous gas pressure drop within the gas tap 10 is higher than the gas pressure drop within the on / off valve 8.

Upon reaching or exceeding the upper threshold value, the control device 6 closes the on / off valve 8, so that the gas supply is interrupted by the first gas supply line 7 and only the throttled gas flow md is maintained by the second gas supply line 9. In the temperature control mode, the gas tap 10 is thus adjusted so that the gas flow flowing through it md maintains the flame 3, but considerably smaller than the gas flow, the first gas supply 7. If the detected temperature falls below a lower temperature threshold, the on / off Valve 8 is opened again by means of the control device 6. For controlling the on / off valve 8, the control device 6, for example, an electrical control signal r or alternatively, for example, use a mechanical control signal.

When the temperature control mode is switched off, the on / off valve 8 is closed, so that a gas flow only takes place through the gas tap 10 or through the further gas supply line 9. 2 shows diagrammatically a dependence of a total gas flow rate mges to the burner of the gas hob according to FIG. 1 as a function of a detected temperature T on the cookware over the time t in s. In the beginning, a high quantity of gas mges = mea + md flows when the on / off valve is switched on. As soon as the cooking temperature T reaches or exceeds the upper threshold value tho, the control device closes the on / off valve so that the gas flow mea is interrupted by the first gas feed line. The gas flow rate is thereby reduced to the gas flow rate md through the further gas supply line. The height of the gas flow rate md is determined by the setting of the throttle device in the further gas supply line. In this case, the throttle device is adjusted so that the gas flow rate md is at least so great that the gas flame at the gas burner does not extinguish.

With increasing time t, the cooking temperature T decreases accordingly, since the gas quantity md is insufficient to keep the cookware or the food at the setpoint temperature Ts. When the lower threshold value thu is reached or fallen below, the control device therefore opens the on / off valve again, so that the gas flow rate mges to the gas burner 1 is increased again to mges = mea + md, as a result of which the temperature on the cookware rises or falls again the setpoint Ts increases. By continuously opening and closing the on / off valve, the gas flow rate is thus switched between the reduced gas flow rate md and a maximum gas flow rate mges that can be passed through the throttle device and the on / off valve, so that the

Cooking temperature T is controlled in a temperature band between the upper threshold tho and the lower threshold thu to the set temperature Ts.

In particular, when using a gas tap as the throttle device, the reduced gas flow rate md dependent optionally be set higher from a desired cooking temperature or cooking level by the operator than is at least necessary for obtaining the gas flame. If the gas tap is turned on, thus increasing the possible gas flow through the further gas supply line, md and consequently also mges increase. The increased gas flow allows higher temperatures on the cookware.

However, for a good control dynamics, the difference between the gas quantity mea through the first gas feed line and the gas quantity md through the further gas feed line should be sufficiently high. In the case shown, md is about 25% (corresponding to about 400 W) of mea = mges - md (corresponding to about 1600 W).

Alternatively, variants may also be provided in which the gas quantity md through the further gas supply line is equal to or higher than a gas quantity mea through the first gas supply line when the on / off valve is open. However, such a control would be less sensitive and associated with very high gas volumes and thus cooking temperatures.

The setpoint temperature or an upper threshold value tho can be designed, for example, as a function of a switching position of the operator-controllable gas valve, for example, as shown in FIG. B. a rotational position of a rotary knob, which is transmitted to the control device. Alternatively or additionally, a separate adjustment may be provided, for example by a rotary knob provided for this purpose or an adjustment key, which transmits a corresponding switching signal to the control device as a separate actuating element after activation or deactivation of the control mode.

3 shows by way of example switching and display elements of a gas hob according to FIG. 1 with a temperature setting element 12, an on / off switch 13 and display elements 14. In one possible operating sequence, first of all the operation of a gas stove or one or all of the associated gas hobs is changed from a manual operating mode to the temperature control operating mode by actuating the on / off switch 13. Thereafter, by means of the temperature setting element 12 (here in the form of a rotary switch), the setpoint temperature Ts on the cookware is determined between a minimum adjustable temperature Tmin and a maximum adjustable temperature Tmax. Accordingly, the on / off gas valve is clocked. The setpoint temperature Ts is displayed here display elements 14 in three stages between a minimum adjustable temperature Tmin, a mean temperature and a maximum adjustable temperature Tmax.

Alternatively, more or less than three stages may be used, or the set temperature may be continuously adjusted. Alternatively, the temperature levels may be displayed instead of light indicators by means of scales of the rotary switch (eg., 60 ° instead of Tmin [z. B. for cooking] 100 ⁰ C in egg ner intermediate position [z. B. boil] and 180 ⁰ C instead of Tmax [eg for frying]). Alternatively, the setpoint temperature, for example, by alphanumeric displays, eg. As LCDs are displayed.

If the gas tap is used as the temperature setting element 12, as the set temperature is raised, the potential gas flow rate for setting a higher temperature level is additively increased at the same time. This has the advantage that a dynamic timing or on / off switching of the on / off valve is maintained and a switch can be saved.

Alternatively, this can be adjusted by the control device for adjusting the gas flow through the gas tap, z. B. by means of a stepper motor. This allows a particularly accurate temperature control. 4 shows a further embodiment in which, as in FIG 1 in the first gas supply line 7, an on / off valve 8 is present. However, now the throttle device in the second gas supply line 15 is not configured as a user-adjustable gas tap but as a simple, not adjustable by the operator in normal operation throttle valve 16. The setting of the throttle valve 16 is rather carried out in particular ex works or at a first installation of the gas hob or a gas hob having gas stove. The throttle valve 16 is thereby adjusted so that a gas flow rate md is passed through the further gas supply line 15, which can maintain a gas flame 3 on the gas burner 1 taking into account the locally prevailing gas pressure and / or the type of gas used, in particular can maintain substantially minimal.

In this embodiment, the gas tap 10 is connected upstream of both the throttle valve 16 and the on / off valve 8 or, in other words, both the first gas feed line 7 and the second further gas feed line 15. Thereby, a gas flow mges is divided by the gas tap 10 behind this on the first gas supply line 7 and on the other gas supply line 15.

In the temperature control mode, the on / off valve 8 is alternately opened and closed by the control device 6 as in the embodiment of FIG. When the temperature control mode is switched off (conventional manual operation), on the other hand, the on / off valve 8 is set in a continuously open state in order to guide a gas flow flowing through the gas tap 10 as freely as possible through the first gas supply line 7 to the gas burner 1. In the embodiment according to FIG. 4, an adjustment of the set cooking temperature Ts can be done analogously by means of the operating and display elements according to FIG. 3 and regulated as described for FIG.

In the event that the adjusting element 11 does not comprise the gas cock 10, it is advantageous if the gas cock 10 is set to maximum (manual or controlled by a stepper motor on the gas tap), since this ensures that the heating power provided is sufficient to to reach or exceed the target temperature.

For the alternative case that the gas cock 10 is used at the same time for setting the target temperature, both the gas flow rate mea by the first gas supply line 7 and the gas amount md are then proportionally increased by the further gas supply line 15, resulting in a different control characteristic. Here, too, it should be ensured that the heating power provided is sufficient to reach or exceed the setpoint temperature.

Of course, the invention is not limited to the embodiments shown. Thus, the temperature control mode can also be performed independently of the gas tap, z. B. only using the on / off valve and a not adjustable by an operator in normal operation throttle, z. B. a narrowed piece of pipe. Then, the temperature control will essentially only occur via the clocking or on / off position of the on / off valve. Instead of the gas cock, for example, another, z. B. motorized adjustable gas valve can be used. Although for the purpose of simple description of mainly 'cooking', 'cooking area', etc. is mentioned, any known to those skilled in food heating is included, for example, roast, fry, cook and so on. LIST OF REFERENCE NUMBERS

1 gas burner

2 pot

3 gas flame

4 gas connection

5 safety valve

6 control device

7 first gas supply line

8 on / off valve

9 additional gas supply lines

10 user-friendly gas valve

11 temperature sensor

12 temperature setting element

13 activation switch

14 indicator

15 first gas supply line

16 Throttling valve mea Gas flow rate through the first gas feed line md Gas flow rate through the additional gas feed line mges Gas flow rate

Tmax maximum adjustable gas cooking setpoint temperature

Tmed Medium adjustable gas hob set temperature

Tmin Minimum adjustable gas hob set temperature r Control signal tho upper threshold thu lower threshold

T cooking temperature

Ts gas hob set temperature

Claims

claims

1. Gas hob with

a first gas supply line (7) to a gas burner (1) whose gas flow (mea) is controllable by means of an on / off valve (8),

- A control device (6) for selectively opening and closing the on / off valve (8) in at least one temperature control mode, characterized in that

- A further gas supply line (9, 15) to the gas burner (1) is present, in particular with a throttle device

(10; 16) is equipped,

- Wherein the further gas supply line (9; 15) is arranged so that in the temperature control mode with the closed

On / off valve (8) does not extinguish a gas flame (3) on the gas burner (1).

2. Gas hob according to claim 1, characterized in that the throttle device comprises an operator-adjustable gas passage adjusting element, in particular gas cock (10).

3. Gas hob according to claim 1, characterized in that

- The throttle device comprises a non-operator-controllable throttle valve (16) and that

- An operator-controllable gas valve (10) is connected in series both to the first gas supply line (7) and to the further gas supply line (15).

4. Gas cooking point according to claim 2 or 3, characterized in that it is equipped with a temperature setting element (12) for setting a setpoint temperature value, wherein the temperature setting element (12) comprises the operator-controllable gas valve (10).

5. Gas hob according to any preceding claim, characterized in that in the temperature control mode, a gas flow (mea) through the first gas supply line (7) is higher than a gas flow (md) through the further gas supply line (9;

6. Gas hob according to claim 5, characterized in that the gas flow (md) through the further gas supply line (9; 15) is not more than about 50% of the gas flow (mea) through the first gas supply line (11; 11 *), preferably not more than about 30%, especially about 25%, in particular about 400 W.

7. A method for controlling the temperature in gas cooking, characterized in that - a cooking temperature (T) by alternately opening and

Closing of an on / off valve (8) is arranged, which is arranged at a first gas supply line (12; 12 *) to the gas burner (1), - wherein with the on / off valve (8) closed the gas burner (1) a at least for obtaining a gas stream (md) sufficient to burn gas burner (1) via a gas line (9; 15) connected in parallel, in particular throttled, to the first gas supply line (7).

8. The method according to claim 7, characterized in that a gas cooking point set temperature (Ts) by adjusting an operator-controllable gas valve (10) is set.

9. The method according to claim 7 or 8, characterized in that by the operator-controllable gas valve (10) the height of at least to obtain a gas burner (1) burning gas flame (3) sufficient gas flow (md) is adjusted.

10. Use of a method according to one of claims 7 to 9 for operating a gas hob according to one of claims 1 to 6.