Diaphragm type switching gas valve for a water heater

Abstract

 Switching valve (101) for the control of the access of a flow of gas to a burner (102) in a domestic combustion appliance, in particular in a water heater (100), that comprises a main valve (5) of the type operated by a diaphragm (8), and an electromagnetic auxiliary valve (1) mounted on the main valve (5), said main valve (5) being controlled by the energisation of said auxiliary valve (1). The switching valve comprises a flame thermocouple (4) next to the burner (102) in order to keep the auxiliary valve (1) energised, and also comprises operating means for the initial energisation of said auxiliary valve (1).

Description

TECHNICAL FIELD

[0001] The present invention relates to a Diaphragm type switching gas valve for a domestic combustion appliance, in particular for a water heater.

PRIOR ART

[0002] Diaphragm type switching gas valves adapted for a domestic combustion appliance are known. This type of switching valve comprises a main valve of the type operated by a diaphragm that defines on each side an inlet chamber and a control chamber with a differential pressure between them and that displaces a member stopping the passage of a flow of gas, and also comprises an auxiliary valve that governs said main valve. In order to open the passage of gas, said auxiliary valve generates a difference of pressure between both sides of the diaphragm, thereby displacing said diaphragm and the closing member.

[0003] EP 1376288 A2 describes a switching gas valve of this type wherein the auxiliary valve is mounted on the main valve, said auxiliary valve being of the tilting arm type that incorporates an electromagnet. When the electromagnet of the auxiliary valve is energised, said tilting arm pivots and closes a first duct that connects the chambers on both sides of the diaphragm and opens a drainage duct, creating a difference of pressure between both chambers of the diaphragm and displacing the closing member to enable it to be opened.

[0004] This type of switching gas valve is mainly used in gas water heaters and in gas heating appliances.

[0005] US 6,352,428 B1 describes a valve arrangement for the regulation of gas in a gas fireplace that comprises a switching valve with a main valve of the diaphragm type and an auxiliary valve of the tilting arm type with an electromagnet. In this case there is a permanent passage hole with a reduced calibre between the chambers that separate the diaphragm. When the electromagnet of the auxiliary valve is energised, the tilting arm pivots and opens a drainage duct, thereby generating a difference of pressure between the chambers separated by the diaphragm and opening the main valve. The auxiliary valve is energised by a control circuit powered by a battery.

[0006] EP 1027559 B1 discloses a gas water heater that also uses a switching valve with a main valve and an auxiliary valve. Said auxiliary valve is energised by a control circuit. The switching valve also has an additional valve to light a pilot flame in the burner. When the water passage is opened, a micro-switch is closed and a signal is sent to the control circuit, which lights the pilot flame in the burner and then energises the auxiliary valve, enabling the passage of gas to the burner. The water heater also comprises a flame detecting ionisation electrode whose signal is received by the control circuit so that, in the event of the burner accidentally being switched off, said control circuit de-energises the auxiliary valve, thereby closing the main valve.

DESCRIPTION OF THE INVENTION

[0007] The object of the invention is to provide a switching valve for the control of the access of a flow of gas to a burner in a domestic combustion appliance, in particular in a water heater, that is an alternative solution to solutions existing in the prior art.

[0008] The inventive switching valve comprises a main valve of the type operated by a diaphragm that defines on each side an inlet chamber and a control chamber with a differential pressure between them and that displaces a main closing member for stopping the passage of a flow of gas, and an auxiliary valve mounted on the main valve, said auxiliary valve being of the tilting arm type that incorporates an electromagnet.

[0009] The electromagnet is provided with a U-shaped core, and the tilting arm incorporates a ferromagnetic frame, which closes the magnetic circuit of the electromagnet when it is energised, thereby opening a valve seating in order to drain the control chamber of the main valve.

[0010] The electromagnet of the auxiliary valve, instead of being energised at all times by a control circuit, is energised by a flame thermocouple disposed next to the burner when said thermocouple is able to generate sufficient energy to keep the valve seating open in order to drain the control chamber of the main valve. To achieve this, the core of the electromagnet comprises a coil of thick wire that is powered by said thermocouple.

[0011] Given that, from the moment at which the burner is lit, the thermocouple needs a period of time to keep the auxiliary valve energised by itself, the inventive switching valve also comprises operating means for the initial energisation of said auxiliary valve.

[0012] The inventive switching valve contributes to the saving of energy in the combustion appliance, as during the period of time in which the auxiliary valve is energised by the thermocouple, there is no battery consumption on the part of said auxiliary valve. This means that, if the switching valve is used in a water heater, during practically the entire period of time said water heater is used the switching valve does not consume energy.

[0013] Furthermore, by using the inventive switching valve, in the event of the burner accidentally being switched off the auxiliary valve is no longer energised, thereby closing the main valve, without the control circuit of the appliance having to intervene. This means that said control circuit can be more simple, as it does not have to perform a safety function, and that ionisation electrodes for detecting the presence of a flame can also be dispensed with. In addition, in this way a safer and more reliable appliance is achieved.

[0014] These and other advantages and characteristics of the invention will be made evident in the light of the drawings and the detailed description thereof.

DESCRIPTION OF THE DRAWINGS

[0015] 

Fig. 1 is a schematic view of a gas water heater that incorporates a switching valve according to the invention, the heater being switched off.

Fig. 2 is a schematic view of the heater of Fig. 1, said heater being in the lighting-up phase.

Fig. 3 is a schematic view of the heater of Fig. 1, said heater being in operation.

Fig. 4 is a section view of a first embodiment of the inventive switching valve.

Fig. 5 is a section view of a second embodiment of the inventive switching valve.

Fig. 6 is a longitudinal section view of the auxiliary valve of Fig. 4, in a non-energised rest condition, with an electrical circuit powered by an electrical battery and a flame thermocouple.

Fig. 7 is a ground view of the auxiliary valve of Fig. 5.

Fig. 8 is a view in cross section of the auxiliary valve of Fig. 7, according to the VIII-VIII line.

DETAILED DISCLOSURE OF THE INVENTION

[0016] Figures 1 to 3 schematically show a gas water heater 100 with a switching valve 101 according to the invention that comprises a main valve 5 and an auxiliary valve 1. The main valve 5 comprises a diaphragm 8 and a main closing member 9. The heater 100 comprises a gas burner 102 that heats the water through a heat exchanger 103. The passage of gas to the burner 102 is controlled by the switching valve 101, and the flow of gas is regulated by a regulation valve 104 that is in connection with a water valve 105, with the flow of gas thereby being proportional to the flow of water. This type of regulation valve is known in the prior art and is not, therefore, described in detail. The heater 100 also comprises an electronic control circuit 106.

[0017] When the heater 100 is switched on by opening a water tap 107 (as shown in figure 2), the flow of water opens the regulation valve 104 and closes a micro-switch 108, the control circuit 106 thereby receiving the signal that the water tap 107 has been opened. Said control circuit 106 energises the auxiliary valve 1, thus opening the switching valve 101, with the gas passing to the burner 102, and simultaneously generates sparks by a spark plug 109, thereby lighting up the burner 102.

[0018] The control circuit 106 energises the auxiliary valve 1 for a predetermined period of time, and then stops doing so, said auxiliary valve 1 being supplied by a flame thermocouple 4 disposed next to the burner 102. From this moment, therefore, the auxiliary valve 1 stops consuming battery. In the event of the burner 102 accidentally being switched off, the thermocouple 4 stops energising the auxiliary valve 1 and the switching valve 101 is closed, as a result of which, so that the heater 100 is safe when the burner 102 switches off accidentally, it is not necessary that the control circuit 106 receives a flame presence signal from, for example, an ionisation electrode, nor is it the control circuit 106 that has to act on the auxiliary valve 1 to close the switching valve 101.

[0019] Figure 4 shows a first embodiment of the inventive switching valve 101, which comprises a main valve 5 and an auxiliary valve 1 mounted on said main valve 5. The main valve 5 includes a gas inlet duct 6 and an outlet duct 7, and is operated through a diaphragm 8 that displaces a main closing member 9. The diaphragm 8 defines on each of its sides a gas inlet chamber 8a and a control chamber 8b connected together by a hole 8c in said diaphragm 8 so that, when a flow 6' is supplied to the inlet chamber 8a it passes through the hole 8c to the control chamber 8b, equalising the pressure in both chambers 8a, 8b and the main closing member 9 keeps the passage of gas towards the outlet duct 7 closed, as a result of the pressure of a spring 9b on the diaphragm 8.

[0020] With reference to figures 4 and 6, the auxiliary valve 1 comprises a casing 10 with a gas outlet duct 15, an electromagnet 20 with a U-shaped core and a coil 23 of thick wire, a tilting arm 30 that incorporates a ferromagnetic frame 34 and an auxiliary closing member 35, a nozzle 18 housed in a duct 18b connected to the gas outlet duct 15 and whose end operates as a valve seating 18a, a return means 36, for example a spring, and a support plate 40, screwed to the casing 10, that supports the tilting arm 30 and the spring 36.

[0021] In a first moment the auxiliary valve 1 is energised by the control circuit 106 through operating means until the thermocouple 4 can keep, by itself, the ferromagnetic frame 34 attracted against both open faces of the core 21. The tilting arm 30 pivots thereby separating the auxiliary closing member 35 from the nozzle 18 and opening the passage of gas in order to drain the control chamber 8b of the main valve 5, so that the pressure exerted by the incoming gas 6' on the diaphragm 8 overcomes the force of the spring 9b and lifts the main closing member 9, allowing a flow of gas greater than that which passes through the diaphragm 8 through the hole 8c to exit, and the supply of the flow 7' of outlet gas of the main valve 5 is established.

[0022] When the energisation of the electromagnet 20 stops, the spring 36 forces the tilting arm 30 to return to its rest position thereby opening the passage of gas through the nozzle 18 so that the pressures on both sides of the diaphragm 8 of the main valve 5 are equalled out and the main closing member 9 keeps the passage of gas towards the outlet duct 7 closed as a result of the pressure of a spring 9b on the diaphragm 8.

[0023] In this first embodiment of the invention shown in figures 4 and 6, the operating means of the electromagnet 20 include on a branch 21a of the core 21, an auxiliary coil 22 of thin wire, wound on an insulating reel, that is supplied initially by a battery 2 until the thermocouple 4 that supplies the coil 23 of thick wire reeled directly on the other branch 21b of the core 21, keeps the auxiliary valve 1 energised. The two branches of the core 21a, 21b have a semi-circular section and their opposing faces are flat.

[0024] In an example of construction, the operating coil 22 is constructed with 360 turns of thin wire with a diameter of around 0.1 mm, with a resistance of 20 ohms and supplied by a nominal voltage of 0.9 to 1.5 VDC. The maintenance coil has 9 turns of thick wire with a diameter of around 0.7 mm and a resistance of 10 mohms.

[0025] In a second embodiment of the invention, shown in figures 5, 7 and 8, the operating means comprise a supply circuit 50 that provides the necessary voltage to the thermocouple 4 in order to supply the coil 23 until the thermocouple 4 itself is capable of generating the necessary voltage to keep the auxiliary valve 1 energised, as a result of which a second coil is not necessary. When the switching valve 101 has to be opened, the control circuit 106 makes said supply circuit 50 generate at its outlet a certain sufficient voltage in order to energise the auxiliary valve 1. The rest of the characteristics of the auxiliary valve 1 of this second embodiment are the same as for the first embodiment.

[0026] In an example of construction of this second embodiment, the coil 40 is constructed with 16 turns of thick wire of around 0.7 mm and a resistance of 20 mohms and is supplied initially by a voltage of 18 mV.

[0027] In both examples of construction each of the branches 21a, 21b of the core 21 has a section of around 23 mm², the distance separating both opposing faces being 3 mm.

Claims

1. Switching valve for the control of the access of a flow of gas (7') to a burner (102) in a domestic combustion appliance, in particular a water heater (100), that comprises

a main valve (5) of the type operated by a diaphragm (8) that defines on each side an inlet chamber (8a) and a control chamber (8b) with a differential pressure between them and that displaces a main closing member (9) for stopping the flow of gas (7'), and

an auxiliary valve (1) mounted on the main valve (5), said auxiliary valve (1) being of the tilting arm (30) type that incorporates an electromagnet (20) provided with a U-shaped core (21) wherein said tilting arm (30) incorporates a ferromagnetic frame (35) which closes the magnetic circuit of the electromagnet (20) when said electromagnet (20) is energised, thereby opening a seating valve (18a) in order to drain the control chamber (8b) of the main valve (5),
characterised in that the core (21) of the electromagnet (20) comprises a coil (23) of thick wire that is supplied by a flame thermocouple (4) disposed next to the burner (102) in order to keep the auxiliary valve (1) energised, the switching valve comprising operating means for the initial energisation of the auxiliary valve (1).

2. Switching valve according to the preceding claim, wherein said operating means comprise an auxiliary coil (22) incorporated into the coil (21), said coil (22) being supplied by a battery (2).

3. Switching valve according to claim 1, wherein the operating means comprise a supply circuit (50) that provides the necessary voltage to the coil (23) for the initial energisation of the auxiliary valve (1).

4. Gas water heater characterised in that it comprises a switching valve according to any of the preceding claims.

Drawing