FR2800154A1 - DEVICE FOR CONTROLLING THE OPENING OF A TAP FOR CONTROLLING THE GAS FLOW OF A BURNER - Google Patents

Abstract

The invention relates to a device for controlling the opening of a valve (RBT) for controlling the gas flow rate of a burner. According to the invention, the device comprises for each valve, a solenoid valve (4) comprising in particular a electromagnet (41) with a coil (43) at the given number of turns, a sealing pad (42) of sufficient size to allow the closure of the outlet passage (21) of the outlet conduit (2) of the valve, said pad being driven axially by the electromagnet. The size of said solenoid valve is such that it can be housed in an existing reception housing (5) of said valve. Furthermore the device comprises electronic means (6) for controlling the said solenoid valve (s) making it possible to supply the winding of each solenoid valve a given peak current. According to the invention, the number of turns and the peak current are such that the product of the two is sufficient so that the electromotive force applied by the electromagnet can cause the displacement of said pad (42) and the opening of the passage of outlet (21).

Description

The invention relates to a device for controlling the opening of a tap.

  to control the gas flow from a burner. The invention applies in particular in the field of household appliances to gas burners for domestic use, used for example in gas ovens for stoves, or on hobs, either independent or integrated in stoves. Most gas burners operate with a gas flow control valve, accessible to a user. Figure 1 shows a diagram of a tap. The RBT tap comprises in particular a gas inlet pipe 1, a gas outlet pipe 2 to the burner BRL 10 corresponding to said tap, this pipe having an outlet passage 21, the diameter of which, fixed, determines the maximum flow rate of gas in the burner. The tap further comprises a movable part 3, called a “turning”, for example in the shape of a cone with a slot of variable section, and which is rotated in front of an orifice of fixed diameter, thus making it possible to adjust the flow of gas. Usually the turn is driven

  mechanically by a joystick accessible to a user.

  Generally, the valve also comprises an electromagnetic safety element, for example a solenoid valve 4, making it possible to close the outlet passage 21, in the case, for example, of an untimely extinction of the burner flame. This solenoid valve, for example, is formed of an electromagnet 41, driving a sealing pad 42, and connected to a flame detection system, for example a thermocouple TC located in the flame F of the burner. When the flame goes out, the current itc delivered by the thermocouple in the electromagnet is no longer sufficient to maintain the sealing pad 42 and the latter closes the outlet passage 21. The security element 4 is placed in a reception housing 5 of the tap, and the dimensions of these different parts are standard, varying

little from one supplier to another.

  When the BRL burner is ignited, the safety element must be disengaged to allow the opening of the outlet passage 21. The disengagement is usually done by mechanical pressure of the user on the lever, causing a mechanism of pressing on the sealing pad 42, thus allowing the valve to open. When the flame is lit, the flame detection system supplies the electromagnet with an itc current which makes it possible to maintain the sealing pad, so that it is maintained

open passage 21.

  However, it is planned to replace the manually driven turning point of certain taps with motorized turning points, driven for example by geared motors, and the control of which is ensured by a. electronic user control. In particular in this type of valve, the mechanical disengagement of the safety element in place is not

no more possible.

  The invention provides a device for electronic control of the opening of the tap which, according to an example of an application, makes it possible to control, in taps with motorized rotary valves, the disengagement of

the security element.

  For this, the invention relates to a device for controlling the opening of at least one tap for controlling the gas flow rate of a burner, said tap comprising in particular a gas inlet pipe, a gas outlet pipe towards the burner, said outlet duct having an outlet passage of predetermined fixed diameter, and a housing for receiving an electromagnetic safety element for closing said outlet passage, the control device being characterized in that it comprises - for each tap, a solenoid valve comprising in particular an electromagnet with a coil with the given number of turns, a sealing pad of sufficient size to allow the closing of said outlet passage, driven axially by the electromagnet, and a spring for recalling said pad enabling said outlet passage to be kept in the closed position, the size of said solenoid valve being such that it can be accommodated in the compartment ment of said valve, - electronic control means of said solenoid valve (s) making it possible to supply in the winding of each solenoid valve a given peak current, and characterized in that said number of turns and said peak current are such that the product of the two is sufficient for the electromotive force applied by the electromagnet to cause displacement

  of the patch and the opening of the outlet passage.

  The device according to the invention thus makes it possible to electronically control in burners with motorized rotary valves the ignition of the burner by controlling the opening of the gas outlet passage in the valve. However, it offers many other possibilities, such as the management of certain simmer-type functions, timer, re-ignition, etc., both in manually operated ball valves and in those with motorized ball valves. It has the advantage, moreover, of using a solenoid valve of size comparable to the electromagnetic safety elements of the prior art, which makes it possible not to change the structure of existing taps, nor to add elements

  additional electromagnetic outside the tap.

  Other advantages and characteristics of the invention will appear

  on reading the description which follows, illustrated by the figures which

  represent: - Figure 1, an example of a gas flow control valve according to the prior art (already described); - Figure 2, a diagram of an example of a control device according to the invention; - Figure 3, an embodiment of a solenoid valve according to the invention - Figure 4, an embodiment of the electronic control means of the device according to the invention; - Figure 5, a timing diagram illustrating according to an example, the

  operation of the device according to the invention.

  In these figures, the homologous elements are identified by

identical references.

  FIG. 2 represents a diagram of an example of a control device according to the invention. It is the control of at least one RBT valve for controlling the gas flow of a BRL burner. In FIG. 2, a single tap is shown, but the device according to the invention can be applied to the control of several taps each corresponding to a burner. The burners are for example mounted on a hob, either independent, or integrated in a stove. They can also be gas oven burners, boiler burners, and in general, any type of gas burner whose gas flow control is ensured by a tap. As in FIG. 1, the valve comprises in particular a gas inlet pipe 1, a gas outlet pipe 2 to the burner BRL, said pipe having an outlet passage 21 of predetermined fixed diameter and

  for example a turning point for controlling the gas flow rate (not shown).

  The tap also includes a reception housing 5 allowing

  receive any electromagnetic safety element.

  According to the invention, the control device comprises, for each tap, a solenoid valve 4 whose size allows it to be housed in the reception housing 5. The solenoid valve 4 comprises in particular an electromagnet 41 and a sealing pad 42, of sufficient size to allow the closure of the outlet passage 21. The sealing pad is driven axially by the electromagnet. The solenoid valve 4 also comprises a return spring for the pad 42 (not shown in FIG. 2), making it possible to maintain the outlet passage 21 in the closed position when

  no force is applied by the electromagnet.

  An exemplary embodiment of a solenoid valve for a device according to the invention is shown diagrammatically in FIG. 3. This is in this example

  of a solenoid valve comprising an electromagnet 41 called 'U-shaped'.

  The electromagnet comprises a double coil 43 with the total number of turns given and an armature 44, the sealing pad 42 being connected by an axis to said armature. Of course, other types of electromagnets are possible, such as for example cylindrical electromagnets. FIG. 3 also shows the return spring (noted 46) of the sealing pad 42, making it possible to keep the outlet passage 21 in the closed position when no force is applied to the frame by the electro magnet. The spring 46 presses on the sealing pad 42 and on the

  structure of the electromagnet placed around the winding.

  According to the invention, the device further comprises electronic control means (denoted 6 in FIG. 2) of the solenoid valve of each tap. These means make it possible to supply a given peak current in the winding of each solenoid valve. This peak current, as well as the number of turns in the winding are dimensioned so that the product of the peak current with the number of turns (given in Ampere-turns) is sufficient for the electromotive force applied to allow the displacement of the sealing pad 42 and the outlet passage opening 21. These control means will be described in more detail below. Advantageously, the user can have access to all or part of the functionalities of these control means, allowing him by

  example of electronically controlling the ignition of a burner.

  Thus, the solenoid valve of the control device according to the invention is specifically dimensioned. According to one example, in the field of household appliances, for example in the field of gas burners for cooktops or gas ovens, the return force of the spring is typically of the order of Newton for an outlet passage 21 of diameter of about 6 mm. The spring is sized to meet safety standards on the gas network. The electromotive force applied to the electromagnet must be sufficient to overcome the return force of the spring. The applicant has shown that in this example, with a U-shaped electromagnet of a type comparable to those used in the safety elements of the prior art, and the armature of which must move by a distance d of approximately 1 , 5 mm, the product of the number of turns by the peak current must be around a thousand ampere-turns. To do this, the number of turns of the winding is for example around a thousand. This number is much higher than the number of turns conventionally encountered in a safety element also having a U-shaped electromagnet (in fact, in this type of electromagnet, the number of turns is ten on each coil). To respect the space constraints, the applicant proposes in this example, a winding whose cross section of the wire has a diameter substantially less than a tenth of a millimeter, which is substantially an order of magnitude less

  to what is done in a classic security element.

  Advantageously, the control means 6 (see FIG. 2) include means 61 for controlling the quantity of energy delivered in the winding of each solenoid valve when the peak current is supplied. In fact, the section of the wire being reduced, the resistivity is very high and safety means must be put in place to limit the power dissipated in the winding as a function of time. FIG. 4 illustrates an exemplary embodiment of the control means illustrating these control means. They are for example formed by a capacitor C in which is accumulated the energy necessary for the displacement of the sealing pad of a solenoid valve. The charging circuit of the capacitor C is formed in the example of FIG. 4 by a voltage generator U0 connected to the terminals of the capacitor via a network comprising in parallel a first resistor Ri (making it possible to maintain the currents of capacity leakage) and a second resistor R2 in series with a first switch CT ,. By switch is meant any type of switch, mechanical or electrical (switch formed by a transistor). The CT switch, closes briefly (for a duration approximately equal to three times the product of the value of R2 by that of the capacitance of the capacitor, ie typically 1 second) to accelerate the charging of the capacitor C, for example from 0 to 50 V, then R1 maintains this charge. This operation is done automatically, for example when the hob or oven is switched on, or after a first burner has been lit. Thus, the capacitor is recharged immediately and ready to discharge again in the winding of a solenoid valve. One could provide a capacitor of this type per solenoid valve but in practice, only one capacitor is really necessary for all of the solenoid valves corresponding to the burners, because the user generally ignites the burners one after the other.

others, not simultaneously.

  The control means furthermore comprise, according to this example, and for each burner, means 62 for transferring the energy accumulated in the capacitor to the winding 43 of the solenoid valve of the burner tap, in order to move the disc of sealing of the solenoid valve and allow the opening of the outlet passage of said valve. For example, as illustrated in FIG. 4, the transfer means are ensured by means of a switch CT2. The capacitor C in fact discharges into the winding 43 of the solenoid valve via the switch CT2, generating a current ib in the winding. There is one switch per solenoid valve. The CT2 switch is for example controlled by the user

  when the latter wants to light the corresponding burner.

  The electronic control means furthermore comprise, for each solenoid valve, means 63 for supplying a holding current in the winding of the solenoid valve, making it possible to maintain the sealing pad so as to keep the outlet passage open. 21 from the corresponding tap. In the example of FIG. 4, the means for supplying the holding current are produced by an energy source U1 connected to the terminals of the coil via a resistor R3 in series with a third switch CT3. The switch CT3 closes for example substantially at the same time as the switch CT2, making it possible to immediately ensure the holding current. When the capacitor C has discharged in the solenoid valve coil, the switch CT2 opens (and the capacitor can be charged again) while the switch CT3

remains closed.

  The closing of the switch CT3 can be for example

  controlled by the user when he wants to close the burner.

  According to a variant (illustrated in FIG. 2), the electronic control means further comprise electronic measurement 64 of a signal emitted by a flame detection system, for example a thermocouple TC placed in the flame F of each burners. The measured signal is sent, for example, to the means 63 for supplying the holding current of the tap corresponding to the burner, allowing, in the event of untimely extinction of the flame, stopping the supply of the holding current and closing the tap outlet passage. For example, the measured signal allows the opening of the switch CT3, in the example of the

figure 4.

  In practice, the control means 6 comprise a sequential management of the various switches, for example by means of a state machine, or a microcontroller with a sequencing program. The user then acts on these control means by

triggering a sequence.

  FIG. 5 illustrates by a timing diagram giving the current ib in the winding as a function of time t, an example of operation of the device according to the invention incorporating control means of the type of those described in FIG. 4. When switching on voltage, CT1 closed briefly, allowing the capacitor to charge. At time to, the user

  decides to light a burner, and orders the closing of switch CT2.

  The capacitor discharges into the winding 43, causing a peak current ip in the winding, which allows the displacement of the armature of the corresponding valve, and the opening of the outlet passage. In parallel, CT3

  also closes, ensuring in the winding a holding current im.

  Then at time t1, the user for example, decides to extinguish the burner, and orders the opening of the switch CT3. The operation can be

  renewed, on each of the burners.

  The control device according to the invention opens up multiple possibilities of applications. In addition to the electronic control by a user of the ignition of a tap, it allows functions such as re-ignition, sequential simmer, timer, etc. For re-ignition for example, if we take the example of embodiment of the control means of Figure 4, a detection of absence of flame on a burner can cause the closure of

  CT2 and CT3, in order to discharge the capacitor in the winding to re-

  light the burner and keep it lit thanks to the holding current. In sequential simmering, the closing and opening of switches CT2 and CT3 can be controlled sequentially to ensure ignition

  sequential of the burner and allow simmering.

Claims (9)

  1- Device for controlling the opening of at least one tap (RBT) for controlling the gas flow rate of a burner, said tap comprising in particular a gas inlet pipe (1), a pipe (2) for gas outlet to the burner, said outlet conduit having an outlet passage (21) of predetermined fixed diameter, and a receiving housing (5) of an electromagnetic safety element for closing said outlet passage, the device being characterized in that it comprises - for each tap, a solenoid valve (4) comprising in particular an electromagnet (41) with a coil (43) with the given number of turns, a sealing pad (42) of sufficient size to allow the closure of said outlet passage, driven axially by the electromagnet, and a return spring (46) of said pad enabling said outlet passage to be kept in the closed position, the size of said solenoid valve being such that it can housing in the reception housing (5) of said tap, - electronic means (6) for controlling said solenoid valve (s) making it possible to supply a given peak current (ip) in the winding of each solenoid valve, and characterized in that said number of turns and said peak current are such that the product of the two is sufficient for the electromotive force applied by the electromagnet to cause displacement   of said pad (42) and the opening of the outlet passage (21).   2- Device according to claim 1, characterized in that the electronic control means (6) comprise control means (61) of the amount of energy delivered in the winding of each   solenoid valve when said peak current is supplied.   3- Device according to claim 2, characterized in that said control means (61) comprises a capacitor (C) and a charging circuit of said capacitor for accumulating said energy necessary for the movement of a sealing pad of a solenoid valve and in that the electronic control means further comprise - for each tap, means for transferring (62) the energy accumulated in the capacitor to the winding (43) of the tap solenoid valve for the movement of the sealing pad of said solenoid valve, - for each tap, means for supplying (63) a holding current (imr) in the winding of the solenoid valve of said tap to hold the sealing pad of said solenoid valve so as to maintain the opening of the outlet passage of said tap.   4- Device according to claim 3, characterized in that said transfer means (62) and said supply means (63) of the holding current can be controlled by a user for respectively controlling the opening and closing of the exit passage of the corresponding tap.   5- Device according to one of claims 3 or 4, characterized in   that the electronic control means further comprise electronic measurement (64) of at least one signal emitted by at least one flame detection system (F) of a burner, the measured signal being sent to the means supply (63) of the holding current of the valve of said burner, allowing in the event of untimely extinction of the flame (F), the stopping of the supply of said holding current in the solenoid valve of said valve   and closing the valve outlet passage.   6- Device according to one of the preceding claims,   characterized in that the electromagnet of said solenoid valve is U-shaped, comprising in particular a double coil and an armature (44), the patch   of the solenoid valve being connected to said armature by a pin (45).   7- Device according to claim 6, characterized in that the return force of the spring of said solenoid valve being of the order of Newton, the displacement (d) of the armature being about 1.5 mm, the product of number of turns of the winding by the peak current is of the order of thousand Ampere-turns.   8- Device according to claim 7, characterized in that the number of turns of the winding is of the order of a thousand, and the section of the wire forming the winding has a diameter substantially less than a tenth of millimeter.   9- Device according to one of claims 1 to 5, characterized in   that the electromagnet of said solenoid valve is cylindrical, and in particular comprises a coil and a core which slides in said coil, the   solenoid valve sealing pad being fixed to said core.   - Device according to one of the preceding claims,   characterized in that the valve or valves being equipped with a motorized flow control system, which can be electronically controlled by a user, the control of the opening of said valve (s) by the user allows in particular ignition of the corresponding burner. 11Baking table with at least one gas burner, and, for each burner, a gas flow control valve, said valve comprising in particular a gas inlet pipe, a gas outlet pipe to the burner, said pipe outlet having an outlet passage of 1o predetermined fixed diameter, and a housing for receiving an electromagnetic safety element for closing said outlet passage, characterized in that it comprises a device for controlling the   the opening of said valve or valves according to one of claims   previous. 12- Gas oven with at least one gas burner, and, for each burner, a gas flow control valve, said valve comprising in particular a gas inlet pipe, a gas outlet pipe towards the burner, said outlet duct having an outlet passage of predetermined fixed diameter, and a housing for receiving an electromagnetic safety element for closing said outlet passage, characterized in that it comprises a device for controlling the opening of the or said taps   according to one of claims 1 to 10.