WO2002035152A1

WO2002035152A1 - A device for the management and the control of a burner in general

Info

Publication number: WO2002035152A1
Application number: PCT/IT2000/000425
Authority: WO
Inventors: Giuseppe Veronese; Salvatore Pappalardo; Roberto Mozzato
Original assignee: Sit La Precisa S.P.A.
Priority date: 2000-10-23
Filing date: 2000-10-23
Publication date: 2002-05-02
Also published as: CA2424612A1; WO2002035152A9

Abstract

A device (1) for the control of a burner (2) in general comprises an electrical control unit (7) for the lighting and automatic control of flame in the burner and a valve unit including: normally-closed valve means (5, 6) which are disposed in main line (3) for the supply of fuel to the burner (2) and can be opened by the control unit (7), means (14), controlled by the control unit (7), for automatically lighting the flame in the burner, and flame-detection means (17) associated with the burner and connected to the control unit (7). The device (1) also comprises actuator means (18) operatively associated with the control unit (7) and connected to the valve means (5, 6) for the manual operation thereof when the control unit (7) is deactivated owing to lack of electrical energy. When the control unit (7) is activated upon the return of the electrical energy, the actuator means (18) are relieved of the control of the valve means (5, 6).

Description

A device for the management and the control of a burner in general

Technical field

The present invention relates to a device for the management and the control of a burner in general, according to the preamble to main Claim 1.

Technological background

In order to manage the operation of burners such as, for example, those used in domestic heating apparatus, it is known to use devices including electrical control units for the lighting and the automatic control of the flame. An example of these devices is known from the applicant ' s

Italian patent No. 1281973.

These control units are arranged to supervise burner lighting and extinguishing operations entirely automatically with reference to external electrical signals, for example, depending on time and/or temperature .

In apparatus of this type, there is a need to' manage the .operation of the burner automatically so as to ensure, on the one hand, automatic operation and, on the other hand, an ability to operate the apparatus manually in the event of a temporary lack of electrical energy.

In this connection, it is known from the above- mentioned Italian patent to provide, in the device, a second valve means disposed in a secondary fuel-supply line, separate from the main, normally-closed valve means which are disposed in the main supply line to the burner and can be opened by the control unit. The second valve means can be opened manually and kept open when the control unit is deactivated but can be closed by the control unit when the latter is activated, thus enabling the burner to be controlled and regulated even in the absence of energy from the electrical mains .

This arrangement leads to some structural complexity since it necessarily requires the provision of a secondary gas supply line connected to the main line and a second valve means separate from the valve means provided in the main gas supply line. Description of the invention

A primary object of the present invention is to provide a device for the management and the control of a burner, designed structurally and functionally to overcome the limitations described with reference to known solutions.

This object and others which will become clearer from the following description are achieved by the invention by means of a device for the management and the control of a burner having the characteristics defined in the appended claims . Description of the drawings

The characteristics and the advantages of the invention will become clearer from the detailed description of a preferred embodiment thereof, described by way of non- limiting example with reference to the appended drawings, in which:

- Figure 1 is a partially-sectioned schematic view of a device according to the present invention,

- Figures 2 to 4 are views corresponding to that of Figure 1 in respective different operative conditions of the device of the invention,

- Figure 5 is a partially-sectioned view of a detail of the device of the preceding drawings, on an enlarged scale.

Preferred embodiment of the invention With reference to Figures 1 to 4, a device according to the present invention for the management and the control of a burner 2, for example, of an apparatus, not shown, for heating domestic environments, is generally indicated 1. The burner 2 is connected to a line 3 for the supply of fuel such as, for example, methane gas.

The gas-supply line 3 is formed in a body 4 of the device, between an inlet opening 4a and an outlet opening 4b. Arranged in succession in the path of the gas in the line 3 are a first solenoid valve and a second solenoid valve which are indicated 5 and 6, respectively, and are of the type which is normally closed and is opened by a control unit 7 for lighting and controlling flame in the burner 2, to which unit the solenoid valves 5, 6 are connected by means of respective electrical wires 8, 9.

Each solenoid valve 5, 6 comprises a respective closure member 10, 11, urged into closure on a corresponding valve seat 10a, 11a by the resilient action of a respective spring 10b, lib. Each closure member 10, 11 is moved so as to open the respective valve seat 10a, 11a in opposition to the spring 10b, lib, as a result of the electromagnetic forces induced in the corresponding solenoid valves 5, 6.

The control unit 7 is connected to a electrical supply mains and comprises a control member 12, shown schematically in the drawings, such as, for example, a thermostat or a time programmer, on which the desired control parameters

(time and/or temperature) are set.

The control unit 7 is connected, by means of electrical wires 13, to means for automatic lighting of the burner flame 2, for example, comprising a pair of electrodes 14 between which an electrical discharge takes place to start combustion.

A pilot burner 15 associated with the burner 2 is in fluid communication with the gas path of the line 3 through a duct 16. In particular, the duct 16 opens into the gas- supply line 3 in a position between the valve seats 10a,

11a.

A filter 16a is provided in the duct 16 in the region of the connection with the gas-supply line 3.

Flame-detection means, preferably of the thermocouple type 17, are associated with the pilot burner 15.

The device according to the invention also comprises actuator means, generally indicated 18, operatively connected to the solenoid valves 5, 6 for controlling the respective closure members 10, 11, as described in detail below.

The actuator means comprise, for each closure member 10, 11, a respective control rod 19, 20 which is structurally independent of the corresponding solenoid valve 5,6 and acts on the respective closure member 10, 11 for the manual control thereof, so as to open/close the corresponding valve seat .

Each actuator rod 19, 20 is controlled by cam means 21 which act on the corresponding rod by means of a respective first-order lever 22, 23 having its fulcrum on the stationary structure of a casing 24 housing the cam means

21.

The cam means comprise a body 25 which is supported for rotating in the casing 24 about a respective axis X and which has a pair of annular grooves 26, 27 extending circumferentially and having respective interrupted profile lines 26a, 27a defining ramp surfaces, all indicated 28. Each of the levers 22, 23 has one end 22a, 23a engaged in the corresponding groove 26, 27 and is articulated to the respective operating rod 19, 20 at the opposite end 22b, 23b so that a rotation of the body 25 about the axis X brings about a corresponding pivoting of each lever about its fulcrum when the lever is engaged for sliding along the ramp surfaces of the grooves 26, 27. The ramp surfaces 28 of the grooves 26, 27 are spaced apart angularly along the respective profiles 26a, 27a in a manner such as to enable the closure members 10, 11 to be controlled in accordance with the modes of operation indicated below.

An operating rod 29 provided for controlling the cam means 21 is mounted in the axially hollow body 25, is fixed for rotation about the axis X with the body 25, and can slide to a limited extent relative thereto, along the same axis . The operating rod is preferably housed in an axial through-hole of polygonal cross-section in the body 25.

A knob 30, operable from outside the casing 24, is associated with the operating rod 29 for the control of the cam 21. A spring 31 fitted axially on the rod 29 acts between the knob 30 and the casing 24.

At the end remote from the knob 30, the casing 24 houses a magnetic unit comprising an electromagnet 32 with a fixed portion 32a constituting a core for the winding of the electromagnet and a movable portion or armature 32b which can be united with the fixed core as a result of the excitation of the electromagnet, in opposition to the action of a spring 33. The movable armature 32b is also attached, by means of a pin-like element 34, to the body 25 of the cam means 21, the function of which will become clear from the following description. The magnetic unit is electrically connected to the thermocouple 17 by means of electrical wires 35 so that the electromagnet 32 can be excited by the current generated by the heating of the thermocouple. The latter is in turn electrically connected to the control unit 7 so as to be able to receive an interruption signal which can cancel out the signal sent to the magnetic unit and consequently de- energize the electromagnet 32.

It should be noted that the casing 24 of the device of the invention is structurally independent of the valve body 4 in which the gas supply line is defined and is such as constitute a unit which can be handled and removed individually and which can be associated with the valve body 4. Moreover, the actuator rods 19, 20 of the solenoid valves 5, 6 are mounted in the body 4 with the interposition of sealing means such as, for example, sealing rings 36, so as to prevent any leakage of gas from the valve body 4 and to separate the entire casing 24 of the device from the portion through which the gas passes. Finally, security means are provided for preventing rotation of the cam means 21 and include a flexible plate element 37 an end of which can engage a toothed portion 38 formed on the outer surface of the body 25 and extending along a portion of the axial extent of the body (Figure 5) . The means for preventing rotation bring about unidirectional locking of the rotation of the cam means 21 about the axis X upon the occurrence of particular operative conditions described below.

In operation, when the control unit is supplied electrically by the normal electrical mains, the burner 2 is subject to control thereby, in conventional manner, with automatic management and control of the flame. In this situation, if a lack of flame in the burner 2 is detected, a control signal is automatically sent to the solenoid valves 5, 6 to shut off the respective valve seats 10a, 11a so as to interrupt the supply of gas to the burner.

If there is an interruption in the supply of electrical current in the electrical supply mains, the flame in the burner 2 is also stopped as a result of the safety closure of the solenoid valves 5, 6 effected by means of signals sent by the control unit 7. In this situation, the burner 2 can be supplied manually in the following manner.

First of all, the knob 30 is rotated about the axis X from the position of Figure 1 (OFF) , in which both of the control rods 19, 20 are removed from the respective closure members 10, 11, to the position of Figure 2 (PILOT) , in which the rod 19 is moved by the cam means to a position adjacent the corresponding closure member 10 and the rod 20 is kept at the same, initial distance from the closure member 11. The operating rod 29 is moved axially by a pressure on the knob 30 until it abuts the pin 34 with its free axial end. Further axial sliding of the rod 29 brings about axial movement of the pin 34, and of the body 25 of the cam means together therewith. The operative position reached is that shown in Figure 3, in which the lever 22 is pivoted so as to urge the closure member 10 to open the respective valve seat 10a whilst the lever 23 is pivoted so as to bring the rod 20 up to the closure member 11, which is kept in the closed position.

As a result of the opening of the valve seat 10a, a fuel flow is established through the duct 16 and permits lighting of the pilot burner 15 but not of the main burner 2 since the supply to the latter is shut off by the closure member 11. Once the pilot burner 15 is lit, the presence of flame is detected by the thermocouple 17 which, as it is heated, produces sufficient current to excite the electromagnet 32 so as to keep the movable armature 32b united with the fixed core by means of electromagnetic attraction (Figure 3) , in opposition to the action of the springs 31 and 33. From this position, a further rotation of the knob 30 to reach the operative condition of Figure 4 brings about pivoting of the lever 23 consequently urging the closure member 11 to open the respective valve seat 11a so as to allow gas to be supplied to the burner 2 through the outlet opening 4b and the flame to be lit by the pilot burner 15. The burner 2 can therefore be managed and controlled manually during the interruption of energy from the electrical mains. During this operation, if a lack of flame in the burner is detected by the thermocouple 17, the supply signal to the electromagnet 32 is interrupted, resulting in its de-energization. The removal of the armature 32b under the resilient action of the springs 31 and 33 brings about axial sliding of the cam means 21 and a corresponding pivoting of the levers 22, 23 which can move the closure members 10, 11 so as to close the respective valve seats 10a, 11a and to shut off the flow of fuel through the line 3 completely.

During manual operation, if the mains electrical energy supply returns, the control unit 7 is reactivated and a interference signal is sent through the wires 35 to the winding of the electromagnet 32. As a result of this, the attractive force between the fixed core 32a and the movable armature 32b of the electromagnet is lost, even in the presence of the current generated by the thermocouple 17, so that the closure members 10, 11 are re-closed onto the respective valve seats 10a, 11a, interrupting the flow of fuel through the line 3. The lighting and extinguishing of the burner 2 are then returned to the control of the electrical control unit 7, as previously.

The interference signal sent by the control unit 7 may be constituted by alternating-current pulses or, preferably, direct-current pulses in the opposite direction to the current generated by the flame detector.

When it is desired to stop and extinguish the burner 2 during operation with manual control (in the absence of an electrical supply) , the knob 30 is rotated back to the OFF position of Figure 1. In this position, further rotation of the knob 30 in the direction indicated by the arrow A of Figure 5 is prevented by the engagement of the plate element 37 in the toothed portion 38. In order for this rotation to take place it is necessary to wait for the electromagnet 32 to be de-energized so that the body 21 is moved axially with sufficient travel to disengage the plate 37 from the toothed portion 38 as a result of relative axial sliding thereof. The knob 30 is thus prevented from being rotated to the position of Figure 3 (PILOT) before the electromagnet 32 has been de-energized and the armature 32b has moved away from the fixed core 32a consequently shutting off the gas passage. This prevents the risk a full flame being lit in the burner 2 when the user rotates the knob from the OFF position to the PILOT position immediately after the burner 2 has been extinguished. In fact, in this situation, the thermocouple 17, which has not cooled sufficiently, may not have de-energized the electromagnet, allowing gas to be supplied to the main burner as a result of the rotation of the knob to the PILOT position.

The invention thus achieves the objects proposed, affording many advantages over known solutions.

A first advantage is that the device of the invention enables the burner to be operated manually, even when there is no electrical energy and the electrical control unit is therefore deactivated, by means of an actuator system acting directly on the closure members of the solenoid valves disposed in the main fuel supply line, with a consequent structural simplification which does not require, for example, the provision of additional valve means in any auxiliary gas lines for manual control of the burner. A second advantage is that the actuator unit is housed in a housing structure or casing which is structurally independent of the valve unit in which the gas duct is formed. In theory, this structure can easily be combined with a conventional valve unit in order to render the unit manually controllable in accordance with the invention in the event of deactivation of the electrical control unit for its automatic control, or in the absence of an electrical supply thereto.

Yet another advantage is that, by virtue of the provision of a gas-tight closure of the seats for the sliding of the actuator rods of the valve means, the entire casing housing the manual control device is advantageously separated from the region of the valve unit which is affected by the gas-flow.

Claims

1. A device for the control of a burner (2) in general, comprising an electrical control unit (7) for the lighting and automatic control of flame in the burner and a valve unit including:

- normally-closed valve means (5, 6) which are disposed in a main line (3) for the supply of fuel to the burner (2) and can be opened by the control unit (7) ,

- means (14) , controlled by the control unit (7) , for automatically lighting the flame in the burner, and

- flame-detection means (17) , associated with the burner and connected to the control unit (7) , characterized in that it comprises actuator means (18) operatively connected to the valve means (5, 6) for the manual operation of the valve means when the control unit (7) is deactivated owing to lack of electrical energy, the actuator means (18) in turn being operatively associated with the control unit (7) in order to be relieved of the control of the valve means when the control unit is activated upon the return of electrical energy.

2. A device according to Claim 1 in which the valve means comprise at least one solenoid valve (5, 6) with a closure member (10, 11) urged resiliently into closure on a respective valve seat (10a, 11a) provided in the gas line (3) , the actuator means (18) comprising at least one control rod (19, 20) for the closure member, the control rod being structurally independent of the solenoid valve (5, 6) and acting on the closure member (10, 11) for the manual control thereof, cam means (21) being associated with the rod (19, 20) for moving it away from and towards the closure member (10, 11) in order to control the closure member so as to open/close the corresponding valve seat .

3. A device according to Claim 2 in which the cam means (21) are operatively connected to the control rod (19, 20) of the closure member (10, 11) by means of a respective lever linkage.

4. A device according to Claim 3 in which the lever linkage comprises a lever (22, 23) having opposite ends connected to the rod (19, 20) and to the cam means (21) , respectively, so that a pivoting of the lever about its fulcrum brings about a corresponding translational movement of the rod (19, 20) away from or towards the closure member (10, 11) .

5. A device according to Claim 4 in which a pair of solenoid valves (5, 6) is provided in the gas line (3), each valve being associated with a respective control rod (19, 20) , each rod being connected to the cam means (21) by means of a respective lever linkage including a respective lever (22, 23) having its opposite ends connected to the rod (19, 20) and to the cam means (21) , respectively.

6. A device according to Claim 4 or Claim 5 in which the cam means (21) comprise a body (25) rotatable about a respective axis (X) , the body (25) having annular grooves

(26, 27) extending circumferentially and having interrupted profile lines (26a, 27a) defining, in the grooves, respective ramp surfaces (28) extending for at least a portion of the profile, each lever (22, 23) being engaged for sliding, at the end remote from the respective rod (19, 20), in the corresponding groove (26, 27), so that, a rotation of the body (25) about the axis (X) brings about a corresponding pivoting of each lever (22, 23) when the lever is engaged on the ramp surfaces (28) .

7. A device according to Claim 6 in which the body (25) is supported rotatably in a casing (24) and is hollow centrally in order to house an operating rod (29) of the cam means (21) .

8. A device according to Claim 7 in which the rod (29) is fixed for rotation with the body (25) and is slidable to a limited extent relative thereto, along the axis (X) .

9. A device according to Claim 7 or Claim 8 in which a knob (30) is provided for moving the operating rod (29) in order to bring about a rotational-translational movement thereof .

10. A device according to Claim 6 in which the body (25) is connected to a movable armature (32b) of an electromagnet (32) in a manner such that, as a result of the excitation of the electromagnet, the armature (32b) can be united with the fixed portion (32a) of the electromagnet (32) , in opposition to resilient means (33) .

11. A device according to Claim 10 in which the electromagnet (32) is electrically connected to the flame- detection means (17) so that, when the control unit (7) is deactivated, the electromagnet (32) is energized by the current generated by the flame-detection means (17) in the presence of flame in a pilot burner (15) , the flame- detection means in turn being electrically connected to the control unit (7) in a manner such that, when the latter is activated, a interference signal is sent to the flame- detection means (17) to de-energize the electromagnet (32) and to relieve the actuator means (18) of the control of the respective solenoid valves (5, 6) , allowing the device to be controlled automatically by means of the control unit (7) .

12. A device according to Claim 7, in which the fuel- supply line (3) is defined in a valve body (4) structurally independent of the casing (24) which houses the actuator means (18) and associated releasably therewith.

13. A device according to Claim 12 , in which the at least one control rod (19, 20) is mounted in the valve body

(4) with the interposition of sealing means (36) so as to prevent leakage of fuel from the valve body (4) and to keep the casing (24) separated from the valve body (4) through which the gas flows.

14. A device according to Claim 6 in which means for preventing rotation of the cam means (21) are provided and comprise a plate element (37) which can engage a toothed portion (38) formed on the outer surface of the body (25) of the cam means and extending along at least part of the axial extent of the body (25) .