GB2170929A

GB2170929A - Gas pressure regulator

Info

Publication number: GB2170929A
Application number: GB08602422A
Authority: GB
Inventors: Heijningen Jacques Van; Jacob Giger
Original assignee: Landis and Gyr AG; LGZ Landis and Gyr Zug AG
Current assignee: Siemens Building Technologies AG; Landis and Gyr AG
Priority date: 1985-02-08
Filing date: 1986-01-31
Publication date: 1986-08-13
Also published as: CH666971A5; GB8602422D0; DE3542705A1; GB2170929B

Abstract

A gas pressure regulator includes a first servo regulator (11) for maintaining a minimum amount of gas, a second servo regulator (14) for limiting the amount of gas to a maximum, and a means for controlling the amount of gas in accordance with the heat output required from a gas heating appliance. The controlling means comprises an electromagnetic actuator (16) including a yoke (22), a core (23) mounted in holders (24) and a coil (25) which is connected to a control line (17) and the force effect of which is transmitted by means of a pushrod (18) to a first auxiliary diaphragm (9) of the first servo regulator (11). There is an approximately linear relationship between the energisation voltage of the coil (25) and the amount of gas conveyed. <IMAGE>

Description

SPECIFICATION Gas pressure regulator This invention relates to a gas pressure regulator, in particular to a pneumatic gas pressure regulator for a gas heating appliance.

Gas pressure regulators are used for various gas heating appliances, for example for space heating installations and appliances for producing hot water. Simple gas pressure regulators only afford the possibility of regulating a given, fixedly adjustable gas pressure. In such arrangements there is no provision for varying the amount of gas in accordance with varying heat requirements so that it is only possible to satisfy varying heat requirements by way of a change in the relationship of the burning time to the switched-off time.

US Patent Specification No 3 843 849 discloses a gas pressure regulator in which a change in the amount of gas can be achieved by virtue of the fact that, with a higher level of heat requirement, the amount of gas is increased from a fixed basic amount to a fixed maximum amount.

German Patent Specification No 2 906 044 discloses a gas pressure regulator in which the amount of gas can be constantly regulated so that the burner can be supplied with an amount of gas that is proportional to the actual amount of heat required. This is achieved in that a temperature sensor acts on a regulator, the regulator in turn operates a diaphragm pump and the diaphragm pump generates a servo pressure which acts on various auxiliary diaphragms. Because of further devices which are also required to maintain a minimum gas pressure at a low level of heat requirement, and also for restricting the appliance to a maximum amount of gas when there is a high level of heat requirement, this arrangement is generally of a highly complex design. The manufacture of such a gas pressure regulator is therefore expensive.

In accordance with the present invention there is provided a pneumatic gas pressure regulator for a gas heating appliance, the regulator comprising a first servo regulator for maintaining a minimum amount of gas, a second servo regulator for limiting the amount of gas to a maximum, and a means for controlling the amount of gas in accordance with the heat output required from the gas heating appliance, wherein the controlling means comprises an electromagnetic actuator having a coil, a yoke and a core which produces a force dependent on a control voltage supplied to the coil, which force acts in the same direction as the force of a low-load spring, and wherein the core is coupled to a first auxiliary diaphragm of the first servo regulator for maintaining the minimum amount of gas.

A preferred embodiment of the invention provides a regulator which is capable of regulating the amount of gas in dependence on the signal of a temperature sensor and the connection of which is of such a simple design that, on the one hand it is very reliable in operation, while on the other hand it is advantageous from the point of view of production.

The invention will now be described, by way of illustrative and non-limiting example, with reference to the accompanying drawing, in which: Figure 1 is a diagrammatic view of the structure of a gas pressure and regulator in accordance with an embodiment of the invention; and Figure 2 shows a magnetic actuator which can be used in the regulator of Fig. 1.

Referring to Fig. 1, there is shown a gas pressure regulator for a gas heating appliance.

Disposed between an inlet chamber 1 and an outlet chamber 2 is a valve formed by a valve head 3 and a main valve seat 4. The valve head 3 is fixedly connected to a diaphragm 5, the position of which is determined by the pressure in the outlet chamber 2 and the force acting on the valve head 3 on the one hand, and the pressure in a servo chamber 6 on the other hand. The servo chamber 6 communicates by way of a servo line 7 with a throttle 8 and by way of a further branch of the same servo line 7 with a first servo regulator 11 including a first auxiliary diaphragm 9 and a first valve seat 10, and a second servo regulator 14 including a second auxiliary diaphragm 12 and a second valve seat 13. Disposed in the first servo regulator 11 is a low-load spring 1 5 which exerts a force on the first auxiliary diaphragm 9.A magnetic actuator 16 which is operated by way of the pair of control lines 1 7 by a temperature sensor (not shown), by way of a regulator which is also not shown, also applies force to the first auxiliary diaphragm 9 by way of a pushrod 18.

Disposed in the second servo regulator 14 is a full-load spring 19 which applies force to the second auxiliary diaphragm 12 and the force of which can be varied by means of an adjusting device 20. The two servo regulators 11 and 14 are connected by a communicating passage 21 to the outlet chamber 2.

Fig. 2 is a diagrammatic view of the essence of the structure of the electromagnetic actuator 16.

Disposed in a yoke 22 is a core 23 which is suspended in the yoke 22 by means of two holders 24 and is therewith movable in the axial direction. Arranged within the yoke 22 and around the core 23 is a coil 25, the winding of which is connected to the pair of control lines 17 (not shown in Fig. 2). The core 23 engages with its pushrod-end into an opening in the yoke 22, whereby that arrangement has the effect and properties of a plunger-type armature system. The pushrod 18 bears against the core 23, the function of the pushrod being to transmit the force of the core 23, generated by energisation of the coil 25, to the diaphragm 9 (Fig. 1).

The mode of operation of the arrangement will now be described with reference to Figs.

1 and 2.

As long as the coil 25 of the electromagnetic actuator 16 is not energised, the pressure in the outlet chamber 2 and thus the pressure flow through the valve 3, 4 is determined in known fashion by the action of the low-load spring 15.

When the coil 25 is energised, then a force is applied to the core 23 in a direction towards the pushrod 18, the magnitude of that force being determined by the level of the energisation voltage. That force is transmitted by the pushrod 18 to the first auxiliary diaphragm 9. The direction of operation of that force is the same as that of the low-load spring. That force urges the first auxiliary diaphragm 9 against the first valve seat 10 and causes the pressure in the servo line 7 and the servo chamber 6 to rise. That causes the diaphragm 5 to be moved in such a way that the valve head 3 moves further away from the main valve seat 4 so that the opening crosssection of the valve 3, 4 is increased and consequently more gas flows from the inlet chamber 1 into the outlet chamber 2 and the pressure in the outlet chamber 2 rises.The higher the level of energisation of the coil 25, the greater is the increase in the opening cross-section of the valve 3, 4, the amount of gas flowing therethrough and the pressure in the outlet chamber 2.

A particular advantage of the core 23 being arranged within the yoke 22 which is magnetisable by the coil 25 is that the force exerted on the pushrod 18 and thus on the first auxiliary diaphragm 9 by virtue of energisation of the coil 25 increases approximately quadratically with the energisation voltage. That also provides a quadratic variation in the pressure in the outlet chamber 2. Because the amount of gas conveyed is proportional to the square root of the gas pressure, that therefore provides an approximately linear dependency of the amount of gas on the energisation voltage of the coil 25.Controlling the amount of gas in response to the heat output required by the gas heating appliance is made quite particularly simple, by means of the above-described arrangement, for the reason that a difference between a reference temperature and an actual temperature can be converted in known manner into a control voltage which is linearly proportional to that difference, and the use of that voltage for energising the coil 25 results in a linear change in the amount of gas.

On the other hand, an advantage of the core 23 being arranged within the yoke 22 is that the force applied to the pushrod 18 by the core 23, in what is referred to as the operating range, is almost independent, in known fashion, of the depth of engagement of the core 23 into the pushrod-end opening of the yoke 22. Therefore a movement of the first auxiliary diaphragm 9 which is transmitted to the core 23 by the pushrod 18 does not result in any substantial change in force. That means that the system is virtually free of reaction and is thus stable from a control procedure point of view.

An important consideration in regard to satisfactory operation is that the core 23 is mounted in a play-free manner and with a low level of force hysteresis, within the coil 25, by means of holders 24.

The second auxiliary diaphragm 12 is pressed against the force of the full-load spring 19 by the pressure in the servo line 7 and in the communicating passage 21 which communicates with the outlet chamber 2. The force of the full-load spring 19 is so adjusted by means of the adjusting device 20 that, below a pressure in the outlet chamber 2 that corresponds to the full load of the burner to be operated, the second auxiliary diaphragm 12 lies against the second valve seat 13.As soon as the pressure in the servo line 7 and thus also in the outlet chamber 2 and in the communicating passage 21, as a result of strong energisation of the coil 25, reaches a level such that that pressure presses the second auxiliary diaphragm 12 against the fullload spring 19 so strongly that the second auxiliary diaphragm 12 lifts away from the second valve seat 13, the pressure in the servo line 7, in the communicating passage 21 and in the outlet chamber 2 will remain at a given level. Even if, because of a high level of heat requirement, the electromagnetic actuator 16 influences the first servo regulator 11 towards a higher pressure in the outlet chamber 2, the pressure cannot exceed a given level because of the action of the second servo regulator 14.In that way, the maximum amount of gas can be adapted by means of the adjusting device 20 to the burner being used, without any necessity to intervene in regard to the electromagnetic actuator 16 or the operating system thereof.

In regard to design configuration, there are various possible ways of arranging the actuator 16 and the low-load spring 15. Thus there is no need for example for both elements to act directly on the first auxiliary diaphragm 9.

As the only important consideration is that the forces of the low-load spring 15 and the actuator 16 are added to each other in regard to their action on the first auxiliary diaphragm 9, the low-load spring 15 may also be arranged within the actuator 16. It is also possible to provide an adjusting device for varying the force of the low-load spring 15, and the adjusting device may be of various designs.

An a.c. voltage may advantageously be modulated on the control voltage which is proportional to the amount of heat required and which is supplied to the coil 25 by the regulator (not shown), by way of the pair of control lines 1 7. In that way the force hysteresis which in itself is already low, by virtue of the arrangement of the components in the first servo regulator 11, may be further reduced by eliminating static friction.

Claims

1. A pneumatic gas pressure regulator for a gas heating appliance, the regulator comprising a first servo regulator for maintaining a minimum amount of gas, a second servo regulator for limiting the amount of gas to a maximum and a means for controlling the amount of gas in accordance with the heat output required from the gas heating appliance, wherein the controlling means comprises an electromagnetic actuator having a coil, a yoke and a core which produces a force dependent on a control voltage supplied to the coil, which force acts in the same direction as the force of a low-load spring, and wherein the core is coupled to a first auxiliary diaphragm of the first servo regulator for maintaning the minimum amount of gas.

2. A regulator according to claim 1, wherein the coil, the yoke and the core are formed as a plunger-type armature system in which the force exerted on the core is approximately quadratically proportional to the control voltage at the coil, and over an operating region is almost independent of the depth of engagement of the core into the pushrod-end opening of the yoke.

3. A regulator according to claim 1 or claim 2, wherein the core is mounted within the coil by means of holders in a play-free manner and with a low level of force hysteresis.

4. A regulator according to claim 1 or claim 2, wherein an a.c. voltage is moduiated on the control voltage being proportional to the amount of heat required from the gas heating appliance.

5. A pneumatic gas pressure regulator for a gas heating appliance, the regulator being substantially as hereinbefore described with reference to the accompanying drawing.