WO2006003680A1

WO2006003680A1 - Device for regulating the delivery pressure of combustible gases

Info

Publication number: WO2006003680A1
Application number: PCT/IT2004/000369
Authority: WO
Inventors: Michele Benvenuto
Original assignee: Sit La Precisa S.P.A.
Priority date: 2004-07-02
Filing date: 2004-07-02
Publication date: 2006-01-12
Also published as: CN100487622C; CN1981252A

Abstract

A device for regulating the delivery pressure of gases, which is arranged for use with gases of various natures, comprises a valve unit having at least one valve seat (5) and a respective closure element (4) which is controlled by a diaphragm (6), first resilient actuator means which can be regulated and which act on the diaphragm (6) first means for regulating the resilient load exerted on the diaphragm (6) by the first resilient means, second resilient means which can be regulated and which can be activated selectively to exert an additional resilient load on the diaphragm (6), second means for regulating the load exerted by the second resilient means, the second regulating means including check means for the second resilient means, which check means can be associated selectively with the regulating device to convert it from a first operative configuration in which the second resilient means are inactive and second operative configuration in which they are selectively activated to exert a preselected resilient load on the diaphragm .

Description

Device for regulating the delivery pressure of combustible gases Technical field

The present invention relates to a device for regulating the deliv¬ ery pressure of combustible gases, in accordance with the preamble of main claim No. 1.

Technological background

It is well known that such devices are used to regulate the pres¬ sure at which combustible gases are delivered to burners or similar equipment, in order to keep substantially constant the value of the de- livery pressure when the supply pressure varies.

The invention is applicable in particular to the specific technical field of pressure regulators that are arranged for use with combustible gases of various natures, such as, for example, natural gas and liquid gas, which have combustibility characteristics which differ from one an- other and which are such as to require corresponding separate opera¬ tions for calibrating the regulator.

As is known, natural gas is normally supplied at a pressure lower than that of liquid gas and it is therefore preferable to provide in the distribution network, or in the equipment arranged for the selective use of either of the two above-mentioned gases, pressure regulators in which a device capable of converting the regulator between two differ¬ ent calibration configurations is integrated.

An example of a regulating device having the above-mentioned features is known from US 3747629. That document describes a pres- sure regulator which is provided with a first springing system which acts on the diaphragm of the regulator to determine a first pressure value, in the case of use with natural gas, and a second, additional, springing system which can be selectively activated to exert on the dia¬ phragm a resilient load correlated with a second preselected pressure value, which is desired in the case of use with liquid gas. The passage from the first to the second calibration configuration is achieved by an auxiliary spacer means acting on the second springing system in the second configuration. The pre-setting of the two pressure values can in turn be regulated by screw means arranged to pre-load resiliently the respective springing systems. Thus, in order to use the device, the only requirement is the activation of the conversion spacer means in order to pass from one to the other of the configurations provided for, with¬ out requiring any other regulating intervention.

Also known in this field is the requirement to be able to keep the delivery pressure substantially constant when the flow rate varies, be¬ cause the pressure tends to decrease as a function of the increase in the power required at the equipment. In applications in which the flow supplied can vary substantially (owing to the variation in the power re¬ quired), a different and specific pre-setting is therefore desirable for each functioning condition and also for each of the gases provided for in the application. Description of the invention

A principal object of the present invention is to provide a pres¬ sure-regulating device which is structurally and functionally designed to satisfy the indicated requirements, at the same time overcoming the limits pointed out with reference to the mentioned prior art.

That and other objects which will emerge clearly hereinafter are achieved by a device for regulating the delivery pressure of combustible gases which is produced in accordance with the appended claims. Brief description of the drawings

Other features and advantages of the invention will become clear from the following detailed description of a preferred embodiment thereof which is illustrated by way of non-limiting example with refer¬ ence to the appended drawings in which: - Figure 1 is a view in axial section of a regulating device according to the invention in a first operative configuration,

- Figure 2 is a view in axial section of the regulating device of Figure 1 in a second distinct operative configuration,

- Figures 3 and 4 are top views of the device according to the inven- tion.

Preferred embodiment of the invention

With reference to the mentioned drawings, a device for regulat¬ ing the delivery pressure of combustible gases which is produced in ac¬ cordance with the present invention is generally indicated 1. The device 1 comprises a valve unit located on a duct 3 (shown sche¬ matically) and including a closure element 4 capable of shutting off a valve seat 5 by way of which a stream of gas is delivered to a con¬ sumer, such as a burner or similar equipment not illustrated in the drawings. The closure element 4 is displaceable during the movement of opening/closing the seat 5 in a direction identified in the drawings by the axis X.

The device 1 also comprises a diaphragm 6 which controls the closure element 4 and which is connected rigidly thereto by a connect¬ ing element 7. On the element 7 is a cylindrical blind seat 8 which is coaxial with the axis X and in which a rod 9 of a spring-carrying disc 10 is supported ro- tatably about said axis. A first and a second spring, which are coaxial with each other and with the axis X and which are indicated 11 and 12, respectively, act directly on the disc 10. In more detail, the correspond- ing axial ends of the springs 11, 12 are fitted on respective protuber¬ ances 11a, 12a which extend from the spring-carrying disc 10 and which are suitable for holding and guiding the springs on the disc.

At its opposite axial end, the spring 11 abuts a corresponding end 13a of a tubular formation 13 which is centrally hollow and which extends axially along the axis X. The tubular formation 13 is guided axially and rotatably inside a sleeve 14 which is connected rigidly to a stationary structure of the valve unit and which extends coaxially with the axis X.

15 indicates sealing rings interposed between the surfaces of the sleeve 14 and of the tubular casing 13 coupled slidingly to one another. A male thread/female thread coupling is also provided between those surfaces, in particular between an externally threaded portion 16 of the tubular formation 13 and a female thread 17 formed by internal thread¬ ing of the sleeve 14. 18 indicates an axially hollow ring capable of being fitted on the tubular formation 13. The ring has a head 18a from which extends a cylindrical shell 18b which is threaded externally at the location of its free axial end 18c so that it can be screwed into the female thread 17 of the sleeve 14 (with the shell 18b interposed between the sleeve 14 and the tubular formation 13). The ring 18 is used, among other things, to cancel out the clearance of the male thread/female thread coupling 16, 17. The ring is also fixed for rotation and axial translation with the tubular formation 13.

It should be noted that, by rotating the tubular formation 13 about the axis X, the formation is subjected to an axial translation movement owing to the male thread/female thread coupling 16, 17, and consequently the resilient pre-loading of the spring 11 can be var¬ ied between a minimum value and a maximum value which are prede¬ termined during the stage of calibrating the device. Advantageously, the resilient load is selected in such a manner that, in the case of use with combustible natural gas, the above-mentioned pre-setting guaran¬ tees the desired values of the gas delivery pressure downstream of the closure element 4.

In order to set the tubular formation 13 in rotation, the device 1 is provided with a substantially bell-shaped handle-form operating means 19 which extends from a centrally hollow head 19a and which is fitted on the tubular formation 13 and is also fixedly joined thereto by a screw means, such as a locking grub screw 20. The handle 19 is also locked on the ring 18, for example, by means of a coupling having a grooved axial profile. At the end opposite that fitted on the protuberance 12a, the sec¬ ond spring 12 abuts a guide element 21 which is in turn connected to the free end of a rod-shaped stem 22 which extends coaxially with the axis X and which is guided axially inside the axial cavity of the tubular formation 13. In this connection, a first shoulder 23 is provided in the tubular formation 13 and is capable of holding and guiding a corre¬ sponding portion 22a of the stem.

A shoulder surface 24, which is advantageously produced with a resilient ring, is also provided on the stem portion 22a. A spring 25 whose function will emerge clearly in the course of the description is active between the facing surfaces defined by the shoulders 23 and 24. The stem portion 22a is also held and guided axially by an ele¬ ment in the form of a centrally hollow bush 26 having an external cylin¬ drical profile threaded in such a manner that it can be screwed into a female thread 27 formed by the internal threading of part of the axial cavity defined at the end 13b of the tubular formation 13, which is axi¬ ally opposite the end 13a.

The first axial portion 26a which is extended by a second portion 26b of smaller diameter is defined in the axial through-hole of the bush 26. The first portion 26a constitutes a cylindrical guide means for a cor¬ responding cylindrical portion 22b of the stem 22 having a diameter larger than that of the portion 22a. The second portion 26b, on the other hand, constitutes an axial guide for the portion 22a, while the shoulder surface defined between the portions 26a and 26b acts as an abutment check element for the portion 22b, with the function of limit- ing the axial travel of the stem 22. It should be noted that the position of that travel stop abutment can be regulated axially by means of the male thread/female thread coupling between the bush 26 and the tubu¬ lar formation 13. A terminal stem portion 22c on which an end portion 28a of a spring 28 having an opposite free end indicated 28b is fitted, is pro¬ vided at the free end of the stem 22, which end is opposite that con¬ nected to the element 21.

As shown in the configuration of the device of Figure 1, the end 28b of the spring 28 is kept spaced from a check surface 29 which faces it and which is located in a screw element 30. That spaced posi¬ tion is achieved by the interposition of a bush 31 between the screw 30 and the tubular formation 13. To be more precise, the bush 31 has an axial hole and is provided with a head 31a from which extends a cylin- drical shell portion 31b which is in turn axially extended by an exter¬ nally threaded end portion 31c. The end portion 31c can be screwed into the female thread 27 of the tubular formation 13 while the cylindri¬ cal portion 31b is guided in the through-hole through the handle 19. The head 31a is advantageously provided with a polygonal external profile in order to permit the engagement of a control key.

At the location of the head 31a, the axial through-hole in the bush 31 has an internally threaded portion 32 into which a correspond¬ ing externally threaded shank portion 30a of the screw 30 can be screwed. The surface 29 is defined in the screw at the base of a blind cav- ity 29a formed axially in the shank 30a at the end opposite a head por¬ tion 30b of the screw. The head 30b is provided with a notch 29c for the engagement of a screwing tool.

In the configuration of Figure 2, it is provided that the bush 31 is removed beforehand from the device 1 and the screw 30 is screwed di¬ rectly into the tubular formation 13, by mutual screwing engagement between the threaded portion 30a and the female thread 27. In that configuration, the end 28b of the spring 28 is actively checked by the base surface 29 of the screw 30, with consequent compression of the spring 28 (and of the other springing systems axially associated therewith along the stem 22) and generation of a corresponding resil¬ ient load on the diaphragm 6. It should be noted that the resilient load is added, in the configuration of Figure 2, to the resilient load generated by the spring 11. As shown in Figures 3 and 4, the handle 19 is also provided with a pair of check surfaces 33a, 33b which can interfere with a corresponding abutment surface 34 in the stationary structure of the device 1. Those surfaces 33a, 33b, by interfering with the abutment 34, act as elements limiting the angular regulating travel (with rotation about the axis X) of the handle 19.

In operation, the configuration of Figure 1 is that typically pro¬ vided when the regulating device is used with combustible natural gas. In that configuration the diaphragm 6 is acted upon by the resilient load generated exclusively by the compression of the spring 11, which is achieved by regulating the axial position of the tubular formation 13. Before the calibration stage, the ring 18 is locked on the tubular forma¬ tion 13 so as to remain fixedly joined thereto for rotation (about the axis X) and for translation (along the axis X).

At the stage of calibrating the device 1, the axial position of the end 13a of the tubular formation 13 (and of the ring 18) corresponding to the minimum resilient load, which is correlated with the minimum delivery pressure desired, is determined. Once that position has been defined, the handle 19 is inserted and locked in such a manner that a condition of abutment of the check surface 33a of the handle on the abutment 34 corresponds to the above-mentioned position.

The axial position corresponding to the maximum resilient load, which is correlated with the maximum delivery pressure obtainable, is determined in a similar manner. Once that position has been defined, it is combined with the operative regulating condition in which the check surface 33b of the handle interferes with the abutment 34. A rotation of the handle of approximately 210° is advantageously provided in order to pass from the minimum to the maximum delivery pressure in the configuration of Figure 1. In addition, in the configuration of Figure 1, the spring 25 is used to cancel out the pre-loading of the spring 12 and also to oppose the weight of the stem 22 and of the other masses as¬ sociated therewith.

On the other hand, the configuration of Figure 2 is that typically provided when the regulating device is used with combustible liquid gas, having different combustibility characteristics from those of natural gas. In that configuration, after the bush 31 has been removed, the screw 30 is screwed directly into the tubular formation 13 in order to generate on the spring 28 a resilient pre-load capable of moving the stem 22 as far as the condition in which the stem portion 22b abuts the shoulder defined between the portions 26a and 26b of the bush 26. At the calibration stage, regulation of the axial position of the bush 26 (which determines a travel limit of the stem 22 in the direction of the axis X) and suitable dimensioning of the spring 28, and also of the springs 12 and 25, pre-impose the delivery pressure values desired at the location of the maximum and minimum handle positions 19 (shown in Figures 3 and 4).

From that it advantageously follows that, in operation, the con¬ version of the device from one to the other of the above-mentioned configurations, owing to the change in the gas delivered, requires only the insertion or removal of the spacer bush 31, without the necessity for any other regulating intervention, because the delivery pressure values obtainable have been imposed beforehand at the calibration stage by means of the regulation measures discussed above. When the device is used, all that is required, in the first configuration (use with natural gas), is that the bush 31 should be screwed in until the head 31a abuts the corresponding surface of the handle head, while, in the second configuration (use with liquid gas), all that is required is that, after the bush 31 has been removed, the screw 30 should be screwed in until the head 30b of the screw abuts the tubular formation 13 axi- ally, at the location of its end 13b. The invention thus achieves the proposed objects, obtaining the indicated advantages over the known solutions.

Attention should be drawn in particular to the improved ease with which the regulating device can be used with combustible gases of various natures in equipment in which regulation of the delivery pres¬ sure between at least two minimum and maximum pressure values is required, as a function of the variation in flow required at the burner.

It should also be pointed out that the entire predetermined angu¬ lar rotation of the handle is used in the modulation between the mini- mum and maximum delivery pressures, for each of the configurations provided for as a function of the type of gas used.

Claims

1. A device for regulating the delivery pressure of gases, which is arranged for use with gases of various natures, comprising: - a valve unit having at least one valve seat (5) and a respective clo¬ sure element (4) which is controlled by a diaphragm (6), is associated with the seat and is displaceable along a predetermined axis (X) during the movement of opening/closing the seat,

- first resilient actuator means which can be regulated and which act on the diaphragm (6) in order to subject it to a preselected resilient load,

- first means for regulating the resilient load exerted on the dia¬ phragm (6) by the first resilient means,

- second resilient means which can be regulated and which can be ac- tivated selectively to exert an additional resilient load on the diaphragm

(6), in addition to the resilient load exerted by the first resilient means,

- second means for regulating the load exerted by the second resilient means, the second regulating means including check means for the second resilient means, which check means can be associated selec- tively with the regulating device to convert it from a first operative con¬ figuration in which the second resilient means are inactive and are not exerting any resilient load on the diaphragm, and a second operative configuration in which they are selectively activated to exert a prese¬ lected resilient load on the diaphragm, characterised in that - the first and second resilient actuator means comprise respective springing systems (11, 12) which act directly on the diaphragm (6) and which are coaxial with said axis, and in that the device comprises a handle-form operating means (19) common to and associated with the first and second regulating means in order to impose selectively, in each of the operative configurations, the desired delivery pressure value, between a minimum value and a maximum value of pre-calibration, the pressure value being proportion¬ ally correlated with a predetermined resilient load exerted on the dia¬ phragm (6).

2. A device according to claim 1, wherein the first regulating means comprise a respective first check means (13) for the corresponding springing system (11) of the first resilient means, which means (13) is axially displaceable in an adjustable manner along the axis (X) by means of a male thread/female thread coupling between the check means and a stationary structure of the valve unit, it being possible to fix the handle-form operating means (19) for rotation with the first check means (13) about said axis so that the rotational movement of the handle means is converted into a corresponding axial translation movement of the first check means, with consequent regulation of the resilient load exerted on the diaphragm (6) by the springing system (11) of the first resilient actuator means, the check means (30) for the second resilient means, when activated in the second configuration, be¬ ing fixed for translation along the axis (X) with the first check means (13) and also fixed for rotation with the handle-form means (19) in or- der to regulate the resilient load of the second resilient means by rota- tion of the handle means.

3. A device according to claim 2, wherein the check means (30) for the second resilient means, when activated, are axially displaceable in an adjustable manner along said axis by means of a corresponding male thread/female thread coupling with the first check means (13).

4. A device according to one or more of the preceding claims, wherein the check means for the second resilient means comprise a surface (29) capable of checking the respective springing system (28) of the second resilient means, the check surface being defined in a screw element (30) capable of being screwed into a tubular formation (13) of the first regulating means, in the second operative configura¬ tion.

5. A device according to claim 4, comprising a spacer means (31) which is interposed axially in a removable manner between the screw element (30) and the tubular formation (13) in order, in the first opera¬ tive configuration, to maintain the check surface (29) at a distance from the corresponding springing system (28) in order not to exert any resilient load on that springing system.

6. A device according to claim 5, wherein the spacer means (31) is capable of being removed in the second operative configuration, either the screw element (30) or the spacer means (31), as desired, being capable of screw engagement over the same portion of the tubular formation (13).

7. A device according to claim 5 or 6, wherein the screw element (30) is supported on the spacer means (31) in the first operative con- figuration.

8. A device according to one or more of claims 4 to 7, wherein the springing system (28) of the second resilient means, which is capable of being resiliently preloaded by means of the screw element (30), is supported axially on an axial end of a stem (22) guided axially inside the tubular formation (13) coaxially with the axis (X), the opposite axial end of the stem (22) acting on the diaphragm (6) by means of the in¬ terposition of a further springing system (12).

9. A device according to claim 8, wherein the further springing sys- tern (12) together with the springing system (11) of the first resilient means have respective corresponding ends capable of bearing contact on a spring-carrying disc (10) supported rotatably on the diaphragm (6) about the axis (X).

10. A device according to one or more of the preceding claims, wherein adjustable stop means are provided for the axial travel, along said axis, of the first and second regulating means, in order to define the minimum and maximum values of the resilient preload acting on the diaphragm in each of the configurations, so as to predetermine in a correlated manner the minimum and maximum values of the delivery pressures that can be imposed in the device.