FR2779214A1 - Gas flow regulator for gas cooker - Google Patents

Abstract

The regulator has for each burner a motorised valve (9) connected in the supply (7,10) to the burner. The valve body (19) has a passage (20) communicating with the supply line (7) with an outlet orifice (25). An electrically operated stepper motor (21) displaces a slide (28) fitted inside the passage (20). The slide terminates in a needle (31) that determines the gas flow.

Description

The present invention relates to a device for regulating the gas flow

  brought to a burner, for a gas cooking appliance, such

than domestic cooktop.

  In a gas cooking appliance, usually comprising several burners, the flow of combustible gas supplied to each burner should be regulated to adapt this flow to the size of the burner and to the type of cooking carried out. It is also necessary to adjust the flow rate according to the nature of the gas used, such as butane, propane or methane, which are supplied under different pressures and which still have other

  properties (fluidity, calorific value, ...) variable from one gas to another.

  In addition to traditional solutions for purely manual and mechanical adjustment of the gas flow rate supplying a burner, regulating devices are already known which use solenoid valves. More particularly, solutions have been proposed which use solenoid valves with variable duty cycle, or proportional solenoid valves. In the case of a solenoid valve with variable duty cycle, this has an electromagnetic coil supplied by electrical pulses of fixed frequency, but of variable duration as a function of an input signal, representative of the desired gas flow rate. In the case of a proportional solenoid valve, a variable voltage in the coil, and representative of the desired gas flow, generates a displacement

  of a mobile nucleus of variable value, which we want to control.

  These two known solutions require, once the desired gas flow rate has been reached, maintaining the electrical supply of the solenoid valves, whether these are of variable or proportional duty cycle. We are therefore in the presence of a "dynamic" operation, which not only requires a permanent electrical supply and generates mechanical wear, but also is disadvantageous in terms of precision, in particular for low flow rates.

gas.

  One way to improve the flow regulation provided by such solenoid valves, to satisfy the user, would be to add a closed loop control system, which would adjust the value of the gas flow rate passing through the solenoid valve at all times. a set value, imposed by the user. Such a system would complicate and increase the cost of the device, without however remedying all of its

  disadvantages, in particular those linked to its "dynamic" operation.

  The present invention aims to remedy all the drawbacks previously exposed, by providing a precise and economical solution for regulating the flow of gas, particularly well.

  adapted to the requirements of gas cooking appliances.

  To this end, the invention essentially relates to a device for regulating the gas flow rate, for a gas cooking appliance, which comprises for each burner a motorized tap, mounted between a fuel gas supply pipe and a gas connected to the burner concerned, the motorized valve comprising a hollow body, the recess of which is in communication with the gas supply pipe and has a gas outlet orifice extended by the gas pipe connected to the burner, a slide being mounted movable in translation inside the aforementioned recess, and being coupled to a stepping electric motor moving said slide in a controlled manner, this slide carrying at one end a needle located in correspondence with the outlet orifice of the '' recess, and able to be engaged more or less deeply in the outlet, depending on the position of the slide

  controlled by the electric stepper motor.

  Thus, the invention proposes a new solution which can be described as "static", in the sense that, in order to fix or modify the flow of gas supplied to the burner in question, the motor is electrically supplied by making it perform a certain number of steps which corresponds to the flow (or variation of flow) requested, in order to bring the needle into an appropriate position relative to the outlet orifice, position to which a value of the flow corresponds. Once this position (therefore also this flow rate value) is reached, the engine is stopped and the valve is in a static state, except for the gas which circulates in the conduits and is consumed in the burner. This operating principle is therefore radically opposed to the known solutions, mentioned above, which use

  solenoid valves requiring permanent power supply.

  The solution proposed by the invention also has the advantage of being remarkably precise, thanks to the use of a stepping electric motor, and by providing that the output shaft of this motor is linked in rotation to a fine and precise pitch drive screw, engaged with a

  complementary tapping formed in the slide which carries the needle.

  This configuration makes it possible to control small movements in translation of the slide, with a significant reduction, therefore to control small variations in flow, with the following advantageous consequences: - The technical solution adopted (electric stepper motor + drive screw) eliminates the need for a speed reducer, hence simplification, economy and

space saving.

  - The intrinsic precision of the proposed device makes it possible to control the flow of gas in an open loop, without feedback, which leads to simplification

and additional savings.

  - The motorized tap allows precise control of low gas flow rates, desirable for low-power burners and for certain types of cooking (simmering). - Thanks to an appropriate profile of its needle, the motorized tap is able to regulate the flow of various gases, in particular butane, propane and methane, which can come from any source (collective distribution network, tank, gas bottle), without make no changes to this faucet itself. Note, however, that, depending on the gas used, the same needle will work in different zones, so that during a gas change, the user will not only have to change the gas injectors, but also act on a selector or the like , for

  inform the control electronics of the type of gas used.

  In an advantageous embodiment, the slide and its needle are provided to ensure, in an end of travel position

  from this slide, a complete closure of the gas outlet orifice.

  In this case, preferably, an annular seal is mounted around the needle, at the base thereof, so as to ensure the tight sealing of said gas outlet orifice, in the end position considered of the slide. Thus, the same motorized valve ensures not only the regulation of the gas flow rate during use of the burner, but also the function of closing member, when the burner is stopped. Overall, the invention thus provides a simple, precise, compact and economical solution, making it possible to equip more or less numerous burners with gas cooking appliances, while satisfying

  fully meet the needs of the users of these devices.

  It will also be noted that, in the application of the invention to a gas cooking appliance with multiple burners, the motorized taps associated respectively with the different burners are advantageously attached directly to a gas supply conduit common to all the burners , so as to obtain an aligned and grouped arrangement, and to

  simplify electrical and gas circuits.

  The invention will be better understood anyway, and others

  characteristics will be highlighted, using the description which

  follows, with reference to the appended schematic drawing representing, by way of example, an embodiment of this device for regulating the gas flow rate, for a gas cooking appliance: FIG. 1 is an overall view, very schematic, a domestic hob equipped with the device which is the subject of the invention Figure 2 is a general perspective view of a motorized tap of this device; Figure 3 is a longitudinal sectional view of the valve of Figure 2, with indication of two needle positions Figure 4 is a sectional view of this valve, similar to

  Figure 3, but illustrating a third position of the needle.

  FIG. 1 represents a domestic cooktop, with four "fires", equipped with four gas burners 1, 2, 3 and 4, supplied from a gas source not illustrated, by a common gas inlet 5 leading to at least one safety valve 6. Downstream of the safety valve 6, there is provided a gas supply pipe or "ramp" 7, common to all the burners 1 to 4. The gas supply pipe 7 has four lateral gas outlets 8, which respectively supply four identical motorized taps 9. Each motorized tap 9 has a gas outlet 10, connected by a gas conduit 11 to one

of the four burners 1 to 4.

  The hob also includes an electrical control and safety part, which includes: - a control keyboard 12, - an electronic "management" unit 13, - an electronic igniter 14, common to all the burners, electrically connected to the management unit 13 as well as ignition electrodes 15 associated respectively with the four burners 1 to 4, - flame monitoring devices 16, associated respectively with the four burners 1 to 4 and connected to the management unit 13, with the possibility (not shown) of an additional connection to each of the taps 9 to supply a small safety valve provided for each tap, - an electrical connection 17 between this management assembly 13 and the safety valve 6, and - four electrical connections 18, connecting the management assembly 13 respectively to the four motorized taps 9, of which

  each one is associated with one of the burners 1 to 4.

  The invention relates, more particularly, to the structure and operation of motorized taps 9, one of which is represented by

  in more detail in Figures 2 to 4.

  The motorized tap 9 has a hollow body 19, which is attached to the gas supply duct 7. The body 19 has a lateral bore, communicating directly with the gas supply duct 7 and thus materializing the lateral gas flow 8 of the supply duct 7. The bore 8 opens laterally into a cylindrical recess 20 of the body 19. An electric stepping motor 21 is fixed, by means of screws 22, to one end of the body 19. The output shaft 23 of the motor 21 is disposed along the central axis 24 of the cylindrical recess, and projects inside this recess 20. On the side opposite the motor 21, the body 19 has a calibrated outlet orifice 25, of circular section , centered on the axis 24 and communicating the recess 20 with a bent tubular connector, materializing the gas outlet 10 of the valve 9

  (extended by the gas pipe 11 leading to the corresponding burner).

  On the output shaft 23 of the motor 21 is fitted the enlarged end 26 of a drive screw 27, having a fine and precise pitch, which is arranged along the axis 24 inside the recess 20 The drive screw 27 is engaged with a threaded slide 28, mounted displaceable in translation inside the recess 20, and immobilized in rotation; for this purpose, the slide 28 has externally a longitudinal groove 29 in which the tip of a lateral screw 30 is engaged,

  which passes through a threaded hole in the body 19.

  At its end furthest from the motor 21, the slide 28 is extended by a needle 31, located on the central axis 24 of the recess

  , in correspondence with the outlet 25.

  It will also be noted that, in the example shown, the motorized tap 9 attached to the gas supply duct 7 is assembled to this duct 7 by a jumper 32, fixed by means of screws 33 on the body 19 of the tap 9. Finally various O-rings or other seals are provided, comprising in particular: a seal 34 mounted between the duct 7 and the body 19 of the valve 9, at the level of the lateral gas outlet 8; a seal 35 interposed between the electric motor 21 and the body 19 of the valve 9; a seal 36 inserted between the head of the lateral screw 30 and the body 19 of the valve 9. A last O-ring 37 can be mounted around the needle 31, at the base

  of the latter, that is to say at its connection to the remainder of the slide 28.

  The rotation of the output shaft 23 of the motor 21 is accompanied by

  of an identical rotation of the drive screw 27, which causes

  even the displacement in translation, along the axis 24, of the slide 28 immobilized in rotation. Depending on the position of the slide 28, the needle 31 is more or less close to the outlet orifice 25, or introduced more or less deeply through this outlet orifice 25. According to the axial position of the needle 31, a gas flow more or less important passes through the valve 9, from its inlet (lateral drilling 8) to the gas outlet 10. To obtain the desired gas flow rate, and possibly modify this flow rate, the motor 21 is electrically supplied, by imposing on it a certain number of steps which corresponds to the desired flow rate, or to the variation

debit to obtain.

  To illustrate this operation, FIG. 3 indicates in solid lines a first position of the needle 31 distant from the orifice 25 and corresponding to the maximum gas flow rate, and in dashed lines a second position of the needle 31, partially engaged in the orifice 25 and corresponding to an intermediate gas flow. FIG. 4 shows a third position, in which the needle 31 is pressed as far as possible into the orifice 25; in this latter position, the O-ring 37 seals all around the orifice 25, which prevents any gas outlet, the valve 9 thus serving as a closing member preventing any arrival of

gas to the corresponding burner.

  The motorized taps 9, respectively associated with the different burners 1 to 4, are all controlled from the control keyboard 12 and from the electronic management unit 13, by means of the electrical connections 18 which supply the stepping motors.

  not respective 21 of these valves 9.

  It goes without saying that the invention is not limited to the sole embodiment of this device for regulating the gas flow rate, for a gas cooking appliance, which has been described above by way of example; on the contrary, it embraces all of the variant embodiments and applications respecting the same principle, whatever the constructive details of the motorized taps, the number of burners, and the additional equipment, in particular safety equipment, a safety solenoid valve can be associated with each motorized tap 9, therefore

  each of the burners 1 to 4, so as to meet the standards in force.

Claims (9)

  1 - Device for regulating the flow of gas supplied to a burner, for a gas cooking appliance, characterized in that it comprises for each burner (1 to 4) a motorized tap (9), mounted between a flue fuel gas supply (7) and a gas pipe (11) connected to the burner concerned, the motorized tap (9) comprising a hollow body (19), the recess (20) of which is in communication (at 8) with the gas supply duct (7) and comprises a gas outlet orifice (25) extended by the gas duct (11) connected to the burner, a slide (28) being mounted displaceable in translation inside the recess (20), and being coupled to a stepping electric motor (21) moving said slide (28) in a controlled manner, this slide (28) carrying at one end a needle (31) located in correspondence with the orifice of outlet (25) from the recess (20), and able to be engaged more or less deeply in the orifice outlet (25), depending on the position of the slide   (28) controlled by the electric stepping motor (21).   2 - Device for regulating the gas flow rate according to claim 1, characterized in that the output shaft (23) of the stepping electric motor (21) is linked in rotation to a drive screw (26, 27) fine and precise pitch, engaged with a complementary tapping formed   in a slide (28) which carries the needle (31).   3 - Device for regulating the gas flow rate according to claim 1 or 2, characterized in that the slide (28) has a longitudinal groove (29), in which is engaged the tip of a lateral screw (30) which passes through a tapped hole in valve body (19)   motorized (9), so as to immobilize in rotation this slide (28).   4- Device for regulating the gas flow according to one   any one of claims 1 to 3, characterized in that the slide   (28) and its needle (31) are provided to ensure, in an end-of-travel position of this slide (28), a complete sealing of the gas outlet orifice (25), so that the motorized tap (9) not only regulates the gas flow, but also the organ function closing.   5 - Device for regulating the gas flow rate according to claim 4, characterized in that an annular seal (37) is mounted around the needle (31), at the base thereof, so as to ensure the sealing off said gas outlet orifice (25), in the   considered end position of the slide (28).   6- Gas flow regulation device according to one   any one of claims 1 to 5, characterized in that it is applied to   a gas cooking appliance with multiple burners (1 to 4), and in that the motorized taps (9) associated respectively with the different burners (1 to 4) are directly connected to a gas supply duct (7)   common to all burners (1 to 4).   7 - Device for regulating the gas flow rate according to claim 6, characterized in that the body (19) of each motorized tap (9) has a lateral bore (8) opening into its recess (20), and communicating directly with the leads gas supply (7).   8- Device for regulating the gas flow rate according to claim 6 or 7, characterized in that the motorized taps (9), associated respectively with the different burners (1 to 4), are all controlled from a control keyboard ( 12) and an electronic management assembly (13), via electrical connections (18)   which feed the respective stepping motors (21) of these valves (9).   9- Device for regulating the gas flow according to one   any one of claims 1 to 8, characterized in that a   safety solenoid valve is associated with each motorized tap (9).