GB2049917A

GB2049917A - A gas fitting, particularly for heating ovens and heating boilers

Info

Publication number: GB2049917A
Application number: GB8014598A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-05-23
Filing date: 1980-05-02
Publication date: 1980-12-31
Also published as: FR2457441A3; GB2049917B; FR2457441B3; NL8002987A; BE883443A; DE2920816A1; IT8021818V0

Abstract

A gas fitting combines a pressure regulator and a solenoid valve which is arranged in series therewith and which acts as the adjusting member of an "on-off" regulator and which, when it opens, successively opens a throttled gas passage and a gas passage which is unthrottled relative to the gas passage through the regulator. The unthrottled gas passage is the regulating port (34) of the pressure regulator (30, 32, 34, 36) itself, the regulating member (32) of which pressure regulator is pressed, by a closure spring (39) opposing the force of a regulating spring (36), against a valve seat which surrounds the regulating port (34) or which is formed in the regulating port itself, the action of the closure spring (39) upon the regulating member (32) being cancelled as soon as the armature of the solenoid valve (27) has covered a predetermined partial stroke. As a result of this functional coupling of the pressure regulator (30, 32, 34, 36) to the solenoid valve (27), there is no need to provide a closure member on the solenoid valve (27) and the solenoid can be of smaller dimensions than in the case of the known embodiments. <IMAGE>

Description

SPECIFICATION A gas fitting, particularly for heating ovens and heating boilers The present invention relates to a gas fitting for use in heating ovens and heating boilers.

In particular the present invention relates to a gas fitting having a pressure regulator and, in series therewith, a solenoid-operated valve which acts as an adjusting member for an "on--off" regulator and which, when it is opened, successively opens a throttled gas passage and a gas passage which is unthrottled in comparison with the passage through the pressure In gas fittings of this kind, it is known to construct the pressure regulator and the solenoid valve and, if required, an ignition safety valve, as independent and spatially separated assemblies.

For the purpose of releasing the gas supply in a stepwise manner, the solenoid valve has two valve ports and two closure members which are successively lifted from their seats. These fittings involve relatively high manufacturing costs, especially since the solenoid also has to be of correspondingly large dimensions.

Furthermore, in gas fittings having a pressure regulator and a solenoid valve, it is known (German Auslegeschrift 1 5 50 293, Figure 3) to vary the pressure of the regulating spring by an additional diaphragm subjected to the outlet pressure of the fitting for the purpose of releasing the gas supply in a stepwise or gradual manner.

These fittings are relatively expensive, especially since the solenoid valve disposed downstream of the pressure regulator monitors and controls the entire gas passage and therefore has to be of correspondingly large dimensions.

In a gas fitting having a servo-controlled pressure regulator and an ignition safety valve with sluice valve (German Utility Model 74 10 650), it is known additionally to associate the function of the sluice valve with the main gas valve of the pressure regulator. However, these fittings do not have a solenoid valve acting as an adjusting member of an "on-off" regulator and also do not reiease the gas supply in a stepwise manner.

An aim of the present invention is to provide a gas fitting of the kind referred to hereabove which is relatively compact and cheaper to produce the prior art fittings.

According to the present invention there is provided a gas fitting for heating ovens and heating boilers, comprising a pressure regulator and a solenoid valve which acts as an adjusting member of an "on-off" regulator and which, when it is energised, successively opens a throttled gas passage and a regulating port of the pressure regulator which is unthrottled relative to the gas passage through the pressure regulator, a regulating member of the pressure regulator being pressed against a regulator valve seat defining said regulating port, by a closing spring by way of a support member which abuts against the regulating member, an armature of the solenoid being coupled to the said support member by a drag connection which, during the course of a lifting movement by said solenoid, in excess of a predetermined initial stroke, lifts the support member from the regulating member by a distance which ensures unobstructed operation of the regulator.

An arrangement in accordance with the present invention, has the advantage that the solenoid valve can be smaller than that in the known constructions, and that the solenoid valve is not provided with an additional closure member, since the regulating member of the pressure regulator assumes the function of an addition closure member. By virtue of the fact that the pressure regulator is operatively coupled to the solenoid valve, tha passage of gas through the fitting can be simplified, whereby the unavoidable pressure loss in the fitting is also reduced.

A simple construction is provided if the throttled gas passage has a valve port which is arranged coaxially of the pressure regulator and in series with a preferably adjustable throttle, the spring-loaded closure member of which valve port is mounted on a push rod which connects the armature of the solenoid to the support member on the pressure regulator.

The solenoid valve can be kept particularly small if the portion of the gas passage leading through the pressure regulator extends parallel to a portion of the throttle gas passage which includes a throttle and a valve port controlled by the solenoid valve. In this case, only the throttled quantity of gas flows through the valve port controlled by the solenoid valve, so that the valve port and the force of the closing spring of the closure member controlling the valve port can be of correspondingly favourable dimensions.

In a further proposal in accordance with the invention, a valve port controlled by the solenoid valve is disposed downstream of the junction between a throttle portion of the gas passage and a portion of the gas passage which leads through the pressure regulator. As a result of this, the valve port controlled by the solenoid valve is disposed downstream of the pressure regulator, so that the regulating member of the pressure regulator does not have to be in the form of a tight closure element.

The present invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 diagrammatically illustrates one embodiment of the present invention; Figure 2 diagrammatically illustrates a further embodiment of the present invention; and Figure 3 shows a detail common to both embodiments of Figs. 1 and 2, drawn to a somewhat larger scale.

The gas fitting shown in Figure 1 includes an ignition safety valve 10 and a valve assembly 12 which combines the function of a pressure regulator and a magnetic adjusting member of an "on--off" regulator. The ignition safety valve 10 is of conventional construction and is therefore not further described. The gas flows through an inlet 14 and via the ignition safety valve 10 into a chamber 1 5 which communicates with a chamber 1 7 by way of a passage 16 and, by way of a passage 18, with a chamber 19 which forms a pressure-regulating inlet chamber of the valve assembly 12.The passage 1 6 is adjustably constricted by means of a throttle screvv 20, so that only a limited quantity of gas can pass through the passage 1 6. A valve port 22 leads from the chamber 17 into a chamber 23 which communicates with an outlet 24. The valve port 22 is controlled by a closure member 25 which is tiltably mounted on the push rod 26 of the armature of a solenoid 27 and which is pressed against a seat on the valve port 22 by a spring 28.

The valve port 22 is matched to-the throttle gas passage, so that the spring 28 can be of correspondingly weak dimensions. The closure member 25 can be rigidly or tiltably connected to the push rod 26, this being indicated in the drawing by the collar 29 which is located on the push rod 26 below the closure member 25.

The bottom of the chamber 1 9 is defined by a diaphragm 30 which is rigidly connected to a regulating element 32 by way of a pin 31. The regulating member 32 controls a regulating port 34 which leads from the chamber 1 9 into the chamber 23. A valve seat is provided at the regulating port 34. The regulating member 32 is in the form of a closure element which, when a corresponding force is applied, abuts sealingly against the valve seat and completely closes the regulating port 34. A regulating spring 36 acts upon the diaphragm 30 from below. The push rod 26 is extended into the chamber 23 when it is connected by way of a drag connection i.e. a connection which operates only when the push rod is retracted, to a plate-like support member 38 which is pressed against the regulating member 32 by means of a spring 39.The spring 39 abuts against a wall 40 which separates the chamber 17 and 23 from one another. The drag connection between the push rod 26 and the support member 38 is formed by a sleeve 42 which is secured to the support member and which surrounds the free end of the push rod 26 with play, the push rod 26 being provided with a collar which is located at a short distance from the bottom of the sleeve 42 when the solenoid 27 is non-energized. This distance is dimensioned such that the support member 38 is lifted from the regulating member 32 only when the push rod 26 has covered a further amount of travel after the valve 22, 25 has opened. The full stroke of the solenoid armature is sufficiently large to enable the regulating member 32 to perform its regulating movements unobstructed by the raised support member 38.

The solenoid 27 is provided with a damping device 44 which ensures that the individual switching operations of the valves 22,25 and at the regulating member 32 are performed in succession. As is shown in Figure 3, the damping device can have a diaphragm 45 which abuts against the extended top end 46 of the push rod 26 and defines a chamber 47 which is filled with fluid and which communicates by way of a throttle port 48 with a further chamber 49 whose volume is resiliently variable. This arrangement has the advantage that an equalizing chamber is not required, since the total of the volumes of the two chambers 47 and 49 remains constant over the stroke of the push rod. It will be appreciated that, alternatively, the solenoid 27 can be damped by mechanical or other known means.

The solenoid 27 forms part of a boiler temperature regulator which operates on the "on-off" principle. The temperature regulator does not require heat when the parts are in their illustrated positions. The solenoid 27 is nonenergized, so that the closure member 25 is applied to its seat at the valve port 22 and the spring 39 maintains the pressure regulator locked in the closed position. The inlet pressure of the gas prevailing in the chamber 1 9 when the ignition safety valve 1 O is open additionally presses the regulating member 32 against its valve seat at the regulating port 34 by way of the diaphragm 30.

When the solenoid 37 is energized when heat is required, the closure member 25 is first lifted from its value seat, whereupon (again assuming that the ignition safety 10 is open) a throttled quantity of gas flows through the passage 1 6 and the chambers 1 7 and 23 to the outlet 24. this gas quantity is dimensioned such that the burner is ignited without explosion. After covering a predetermined stroke, the drag connection acts upon the support member 38, whereupon the regulating member 32 is relieved of the action of the spring 39 and the pressure regulator is released.The regulating spring 36 now lifts the regulating member 32 from its valve seat, whereupon a larger quantity of gas flows through the regulating port 34 and, together with the throttled quantity of gas flowing through the valve port 22, provides the total quantity of gas required for the rated performance of the boiler. The pressure regulator shuts off the gas supply in the first instance upon de-energization of the solenoid 27, whereupon the valve 22, 25 also closes.

The spring 39 for locking the pressure regulator can be of relatively weak dimension, since the inlet pressure of the gas acting upon the diaphragm 30 biases the pressure regulator in the closing direction. Owing to this fact and the fact that, as a result of matching to the throttling of the gas passage through the valve port 22, the spring 28 can also be considerably weaker than a closing spring of a valve which controls the entire gas passage, the solenoid 27 in the embodiment of Figure 1 can be of substantially smaller construction than in conventional gas fittings.

The construction of the embodiment of Figure 2 is basically the same as that of Figure 1. Here also, an ignition safety valve 10 is provided which is combined with a valve assembly 52 to form a structural unit which combines the function of a pressure regulator and of a magnetic adjusting member of an "on-off' regulator. The embodiment of Figure 2 differs from the construction of Figure 1 in that the ignition gas passage 1 6 opens into a central chamber 53 and not into the upper chamber, and that the outlet 24 communicates with an upper chamber 54 and not with the centre chamber. The two chambers 53 and 54 are interconnected by a valve port 56 which is controlled by a closure member 55 and whose cross section is larger than the cross section of the valve port 22 of the embodiment of Figure 1.The gas passage 1 8, 1 9. 34 leading through the pressure regulator, and parts of the pressure regulator, are the same as those in the embodiment of Figure 1. For reasons which will be set forth hereinafter, the solenoid 57 which controls the valve 55, 56, and which is also provided with a damping device 44, is somewhat stronger than the solenoid 27.

In the gas fitting of Figure 2, the throttled portion of the gas passage leading through the throttle 20 and the passage 1 6 joins, upstream of the valve 55, 56 controlled by the solenoid 57, the portion of the gas passage which leads through the passage 1 8 and the pressure regulator and which is unthrottled in comparison with throttled portion of the gas passage. Therefore, the valve 55, 56 has to be dimensioned such that the entire quantity of gas can flow through in an unthrottled manner. Therefore, the closure member 55 has to be acted upon by a closing spring 58 which is stronger than the closing spring 28 in the embodiment previously described. Nevertheless, the solenoid 57 can be smaller than a solenoid for a known gas fitting whose magnetic adjusting member acts upon two closure member as mentioned initially. The reason for this is that one of these known closure members is mounted in a friction tight manner on the push rod actuated by the solenoid, and the solenoid also as to overcome this frictional force in addition to the force of the closing spring. The advantage of the fitting of Figure 2 over that of the first embodiment described hereabove resides in the fact that the valve 55, 56 controls the entire passage of gas and thus the regulating member 32 of the regulator need not be a tightly closing closure member, and the regulating port need not be surrounded by valve seat.

Claims

1. A gas fitting for heating ovens and heating boilers, comprising a pressure regulator and a solenoid valve which acts as an adjusting member of an "on---off' regulator and which, whilst is energised, successively opens a throttled gas passage and a regulating port of the pressure regulator which is unthrottled relative to the gas passage through the pressure regulator, a regulating member of the pressure regulator being pressed against a regulator valve seat defining said regulating port, by a closing spring by way of a support member which abuts against the regulating member, an armature of the solenoid being coupled to the said support member by a drag connection which, during the course of a lifting movement by said solenoid, in excess of a predetermined initial stroke, lifts the support member from the regulating member by a distance which ensures unobstructed operation of the regulator.

2. A gas fitting as claimed in claim 1, in which the pressure regulator has a regulating diaphragm which is during normal use subjected to the inlet gas pressure.

3. A gas fitting as claimed in claim 1 or 2, in which the throttled gas passage has a valve port which is disposed coaxially of the pressure regulator and in series with a throttle, said port being controlled by a spring-loaded closure member which is mounted on a push rod which connects the armature of the solenoid valve to the support member on the pressure regulator

4. A gas fitting as claimed in claim 3, in which the throttle is adjustable.

5. A gas fitting as claimed in any one of claims 1 to 4, in which the portion of the gas passage leading through the pressure regulator extends parallel to a portion of the throttled gas passage which incorporates a throttle and a valve port controlled by the solenoid.

6. A gas fitting as claimed in any one of the claims 1 to 4, in which a valve port controlled by the solenoid is disposed downstream of the junction between a throttled portion of the gas passage and a portion of the gas passage which leads through the pressure regulator.

7. A gas fitting for heating ovens and heating boilers, constructed and arranged substantially as hereinbefore described with reference to and as illustrated in Figs. 1 and 3, or Figs. 2 and 3 of the accompanying drawings.