EP0989366A1 - Ventileinheit zur automatischen Regelung der Brenngasdurchflussmenge - Google Patents

Ventileinheit zur automatischen Regelung der Brenngasdurchflussmenge Download PDF

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Publication number
EP0989366A1
EP0989366A1 EP99202043A EP99202043A EP0989366A1 EP 0989366 A1 EP0989366 A1 EP 0989366A1 EP 99202043 A EP99202043 A EP 99202043A EP 99202043 A EP99202043 A EP 99202043A EP 0989366 A1 EP0989366 A1 EP 0989366A1
Authority
EP
European Patent Office
Prior art keywords
valve
diaphragm
flow
pressure
rate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99202043A
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English (en)
French (fr)
Inventor
Gianpierro Turrin
Giuseppe Veronese
Roberto Mozzato
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sit La Precisa SpA
Original Assignee
Sit La Precisa SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sit La Precisa SpA filed Critical Sit La Precisa SpA
Publication of EP0989366A1 publication Critical patent/EP0989366A1/de
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
    • F23N1/087—Regulating fuel supply conjointly with another medium, e.g. boiler water using mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/04—Measuring pressure
    • F23N2225/06—Measuring pressure for determining flow
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/16—Fuel valves variable flow or proportional valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/20—Membrane valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2235/00—Valves, nozzles or pumps
    • F23N2235/12—Fuel valves
    • F23N2235/24—Valve details

Definitions

  • the present invention relates to a valve unit for automatically regulating the flow-rate of a fuel gas to a device for heating a fluid in dependence on variations in the flow-rate of the fluid flowing through the heating device, in accordance with the preamble to main Claim 1.
  • a first known system for automatically regulating the flow-rate of gas provides for the use of an actuator with a diaphragm supplied with a pressure differential which is brought about in the pipe through which the water flows and is correlated with the flow-rate thereof.
  • the diaphragm actuator supplied with this water-pressure differential generates a displacement signal which is transferred directly to the closure member of a valve located in the gas-supply duct so as to regulate the flow-rate of fuel gas in a manner correlated with the flow-rate of water required by the user.
  • a second known system for automatically regulating the flow-rate of gas provides for the diaphragm actuator, which is supplied with the water-pressure differential, acting on the means for regulating the gas flow-rate by means of the control mediated by a pressure regulator device.
  • An example of such a system is known from the abstract of the Japanese patent application published with No. 58024756.
  • the pressure regulator device disclosed therein comprises a servo-valve located in a gas-supply duct and having a closure member with a diaphragm control, the diaphragm being subject to the gas-delivery pressure on one side and to a reference pressure established in a pilot chamber of the servo-valve on the other side, and a modulation valve, the diaphragm of which is subject, on one side, to the gas delivery pressure and, on the other side, to the resilient load exerted directly, by means of the diaphragm actuator, by the pressure differential which is brought about in the fluid and is correlated with the flow-rate thereof.
  • the problem upon which the present invention is based is that of providing a valve unit for automatically regulating the flow-rate of a fuel gas which is designed structurally and functionally so as to prevent all of the problems complained of with reference to the prior art mentioned.
  • a valve unit is for automatically regulating the flow-rate of a fuel gas delivered to a water-heating device such as, for example, a domestic water-heater or boiler, not shown in the drawings, in dependence on variations in the flow-rate of water flowing through the heating device.
  • the gas is supplied to the valve unit by a supply duct 2 and is output by the valve unit through a delivery duct 3 to a burner of the heating device, not shown in the drawing.
  • the ducts 2, 3 are separated by a servo-valve 4 comprising a first closure member 5 which is urged resiliently into closure on a first seat 6 by the resilient load of a spring 7 and which can be opened by a first diaphragm 8 which is sensitive to the pressure differential existing between the pressure Pu in the delivery duct 3 on one side, and the pressure Pt in a pilot chamber 9 on the other side.
  • the pressure Pt in the pilot chamber 9 is controlled by the control mediated by a diaphragm pressure-modulation valve, indicated 10, constituting, with the servo-valve 4, a servo-assisted, diaphragm pressure-regulator.
  • the pressure-modulation valve 10 comprises a control rod 12 screwed into a cup-shaped element 13 which is kept in abutment with a stationary structure of the valve unit by the resilient load of a first spring 14.
  • a second spring 15 acts between the cup-shaped element 13 and a plate 16 carrying a closure member 17 which can shut off a seat 18.
  • the plate 16 is fixed to a diaphragm 19 of the modulation valve which is subject to the load exerted by the control rod 12 on one side and to the pressure existing in a chamber 20 on the other side.
  • the chamber 20 is in communication with the delivery duct 3 through a transfer duct 21, and with a second chamber 22 through the valve seat 18.
  • the second chamber 22 is always in communication with the pilot chamber 9 through a second transfer duct 23, whereas it communicates selectively with a duct 24 for tapping off the gas supplied to the input of the valve unit and with a duct 25 communicating with the chamber 20 through an on-off valve 26.
  • the valve 26 comprises a closure member 27 which is urged into closure on a third seat 28 and is movable, by the action of a control rod 29 of the closure member, so as to close onto a fourth seat 30 in a manner such that, when the third seat 28 is closed, the fourth seat 30 remains open and vice versa.
  • constriction 24a such as to bring about a loss of pressure in order to derive the piloting pressure Pt from a fraction of the gas flow tapped off, at the input of the valve unit, from the flow supplied through the duct 2.
  • the control rod 12 of the modulation valve acts on the diaphragm 19 by means of a first-order lever 31 pivotable, in an intermediate position of the lever, on a fulcrum 32 associated with a bracket 32a fixed to the stationary structure of the valve unit 1.
  • the lever 31 acts directly on a shoulder 12a of the control rod 12 which is adjustable by screwing. This adjustment enables the distance between the shoulder 12a and the portion of the lever 31 which acts on the shoulder to be varied so as consequently to adjust the pressure-modulation activation threshold of the valve 10.
  • the lever 31 On the opposite side of the fulcrum 32 to the control rod 12, the lever 31 is movable by means of a rod 33 having opposite ends fixed to respective diaphragms 34, 35 of a diaphragm actuator indicated 35a.
  • the diaphragms 34, 35 are subject to the pressures detected in adjacent portions of a water-supply pipe 36a, downstream and upstream of a constriction 36 of the pipe 36a, respectively.
  • the actuator 35a is thus supplied with the pressure differential brought about in the pipe 36a and generates a load which is transferred directly to the rod 33 by the diaphragms 34, 35, and which is correlated with the pressure-differential value.
  • the actuator 35a comprises a single diaphragm 35b which is subject, on its opposite sides, to the pressures detected upstream and downstream of the constriction 36, respectively.
  • the single diaphragm 35b is fixed to one end of a rod 33a to the opposite end of which the lever 31 is connected.
  • the end portion of the lever 31 facing towards the rod 33a is surrounded by a sealing element 33b.
  • the sealing element is fitted on the lever 31 and its opposite ends are connected in a hydraulically leaktight manner to the lever and to the stationary portion of the valve unit, respectively.
  • the hydraulic seals provided are thus advantageously static and such as to permit the pivoting movement of the lever about its fulcrum without generating substantial friction opposing the movement of the lever.
  • the lever 31 is moved relative to the fulcrum 32 by the load exerted as a result of the pressure differential supplied to the diaphragm actuator 35a. Since the flow-rate of water in the pipe 36a is correlated proportionally with the pressure differential acting on the diaphragms 34, 35, as explained further below, for each value of the water flow-rate, the position of the control rod 12 of the modulation valve is controlled directly by means of the lever 31, in a correlated manner, by the water-pressure differential brought about in the pipe 36a.
  • a minimum adjustment screw associated with the control rod 12 of the modulation valve is indicated 37.
  • the travel of the rod 12 is adjusted by means of the screw 37 so as to ensure a minimum resilient load on the spring 15 and consequently a minimum pressure value of the valve.
  • the lever 31 is extended, on the same side of the fulcrum 32 as the rod 33, by an appendage 38 which is acted on resiliently by a respective spring 39 the resilient load of which serves to keep the lever in abutment with a shoulder of the rod 33.
  • first and second adjacent portions 40, 41 On the same side of the fulcrum 32 as the control rod 12, the lever 31 is further extended by first and second adjacent portions 40, 41.
  • the first portion 40 bears against a shoulder of an adjustment screw 42 for regulating the maximum pressure value permissible for the modulation valve.
  • the second portion 41 is constituted by a resilient plate fixed to one end of the lever and in abutment at its opposite end with a catch projection of a control rod 43 of the closure member 27.
  • the rod 43 in turn acts on a control element of a snap-action switch indicated 44, the operating threshold of which is adjustable by the screwing of a bush 45.
  • the switch 44 is acted on by the resilient load of the plate 41 and, for a predetermined value of this load, the rod 43 is moved, as a result of the snap action of the switch 44, with a predetermined travel such as to snap the closure member 27 into closure on the seat 30.
  • the pivoting of the lever 31 is such as to reduce the resilient load exerted by the spring 15 on the diaphragm 19 and, conversely, to increase the resilient load exerted by the plate 41 on the rod 43.
  • the resilient load of the plate operates the snap-action mechanism of the switch 44, the control element of which moves the rod 43 with a travel the length of which is such as to switch the on-off valve 26 and to bring the closure member 27 into closure on the seat 28.
  • the diaphragm 8 is thus subject to the same pressure on both sides and the closure member 5 is operated by the spring 7 so as to close the seat 6, shutting off the flow of gas through the valve unit.
  • the snap-action switch 44 also performs the function of a control element for devices (not shown) which are normally provided in apparatus equipped with the valve unit of the invention for lighting the burner and monitoring the flame.
  • the switch 44 may additionally be arranged to bring about the closure of a solenoid valve 45a disposed upstream of the valve unit, by means of the signal produced by the snap action, so as to shut off the main gas flow supplied through the duct 2.
  • valve unit 1 is shown in an operative condition in which the closure member 27 is closed onto the seat 30 so that the gas pressure tapped off through the duct 24 acts in the pilot chamber 9 through the transfer duct 23 and the chamber 22, as well as in the chamber 20 of the pressure-regulator 10.
  • the closure member 5 is acted on so as to open the seat 6 partially, so as to ensure delivery of the gas to the output of the valve unit 1.
  • the partial opening of the closure member 5 as a result of a reduction in the pressure loss brings about an increase in the delivery pressure Pu.
  • This pressure Pu also acts, through the duct 21, on the side of the membrane 19 facing the chamber 20 so as consequently to balance the resilient load exerted by the spring 15.
  • a pressure and a gas flow-rate correlated proportionally with the pressure-differential and the flow-rate of water detected in the pipe 36a is thus achieved for each value of the resilient load on the diaphragm 19.
  • the pressure differential detected in the water pipe reduces proportionally and a corresponding load is transmitted to the control rod 12 and, from the control rod 12 to the diaphragm 19, by means of the spring 15.
  • the reduction in the resilient load of the spring 15 causes partial opening of the seat 18 and a consequent reduction of the pilot pressure Pt existing in the chambers 22 and 9.
  • the closure member of the servo-valve 4 therefore partially closes the seat 6 so as to bring about a reduction in the delivery pressure Pu owing to the increase in the pressure loss.
  • This delivery pressure acts in the chamber 20 through the duct 21, balancing the resilient load acting on the diaphragm 19, thus achieving a value of the gas pressure delivered as well as a flow-rate value which are correlated proportionally with the water-pressure and flow-rate differential detected in the pipe 36a.
  • the delivery pressure Pu of the gas thus varies in direct proportion to the water-pressure differential detected in the supply pipe 36a.
  • the ratio between the water-pressure differential and the gas delivery pressure consequently remains substantially constant with variations in the required flow-rate of water. Since the flow-rates vary proportionally with the pressure differential (substantially with the square root of the pressure differential), the ratio between the gas flow-rate and the water flow-rate is kept constant in operation. This constant ratio between the gas and water flow-rates consequently ensures a substantially constant temperature differential between the water input to and output from the heater device. Since the water-input temperature can be considered approximately constant or at most variable in a limited manner and over long time intervals (for example, seasonal temperature variations), the water-output temperature remains substantially constant and such as to ensure adequate comfort for the user in all operating conditions.
  • a throttle element 48 is provided in the constriction 36 of the supply pipe, the various positions of this throttle element enabling different pressure losses and consequently different values of the pressure differential generated in the region of the constriction 36 to be brought about for a given flow-rate of water passing through the pipe 36a. It is thus possible to vary the ratio between the pressure differential and the gas-delivery pressure so as to vary the gas-delivery flow-rate selectively and consequently to vary the temperature of the water output by the heating device for a given flow-rate of water required by the user.
  • the throttle element thus constitutes an element for regulating the ratio between the water pressure differential and the gas delivery pressure.
  • the throttle element 48 may be disposed in the gas-supply pipe, downstream of the valve unit 1, in order to perform the function of an element for regulating the ratio between the pressure differentials and hence between the water and gas flow-rates, as described above.
  • FIG 2 shows a variant of the valve unit of the invention, generally indicated 50, in which parts corresponding to those of the preceding embodiment are marked with the same reference numerals.
  • the valve unit 50 is suitable, in particular, for applications in which a user such as an instantaneous water heater for domestic use is associated with a gas central-heating boiler.
  • Figure 4 is a functional diagram of a combined installation of the aforesaid type. The installation provides for a first water circuit with heating elements R such as room radiators, connected to a boiler C with an associated burner B supplied by a fuel-gas delivery line G. A second circuit is also provided for supplying washing water to a corresponding heating device such as a heat-exchanger S. The water is supplied to the user by means of a line W for supplying water to the heat exchanger S through which the fluid of the first circuit, diverted by means of a three-way valve V, is made to flow.
  • R heating elements
  • a second circuit is also provided for supplying washing water to a corresponding heating device such
  • the valve unit 50 differs from the unit of the previous embodiment in that a second servo-valve 51 is provided, in addition to the modulation valve 10.
  • the servo-valve 51 has a diaphragm 52 fixed to a plate 53 carrying a closure element associated with a corresponding valve seat 54.
  • the diaphragm 52 is subject, on one side, to a load exerted by a spring 55 and adjustable by screwing of a spring-holder 56 and, on the other side, to the pressure existing in a chamber 60.
  • the chamber 60 is in communication with the chamber 22 through the valve seat 54 and with the pilot chamber 9 through the transfer duct 23.
  • the chamber 60 also communicates selectively with the duct 21 through the valve seat 30, which is opened by the on-off valve 26.
  • the valve 26 constitutes a switching valve which can switch operation alternatively from the servo-valve 51 to the modulation valve 10, as elements for modulating the gas-delivery pressure.
  • valve unit is shown in an operative condition in which the delivery pressure Pu, and consequently the gas flow-rate, is regulated by the servo-valve 51 and the modulation valve 10 is excluded from operation.
  • the chamber 60 is in communication with the duct 21 through the valve seat 30 and the pilot pressure Pt is obtained from the balance between the pressure Pu acting on the diaphragm 52 and the resilient load acting thereon by means of the spring 55.
  • Adjustment of the travel of the spring holder 56 regulates the maximum permissible value of the delivery pressure (and flow-rate), which is selected in dependence on the power of the heating device of the installation.
  • the pressure Pu is regulated in the manner described above with reference to the valve unit 1 and, for each value of the water flow-rate required, the gas-delivery pressure varies in direct proportion to the water-pressure differential detected in the supply pipe.
  • the switching brought about by the valve 26 opens, by means of the switch 44, the three-way valve V by means of which the water flow of the first circuit is diverted towards the heat-exchanger S for heating the washing water.
  • the invention thus solves the problem set, achieving the advantages set out above in comparison with known solutions.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid-Driven Valves (AREA)
  • Lift Valve (AREA)
  • Feeding And Controlling Fuel (AREA)
  • Flow Control (AREA)
EP99202043A 1998-07-01 1999-06-24 Ventileinheit zur automatischen Regelung der Brenngasdurchflussmenge Withdrawn EP0989366A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITPD980164 1998-07-01
IT98PD000164A ITPD980164A1 (it) 1998-07-01 1998-07-01 Gruppo valvolare per la regolazione automatica della portata di un gas combustibile.

Publications (1)

Publication Number Publication Date
EP0989366A1 true EP0989366A1 (de) 2000-03-29

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EP99202043A Withdrawn EP0989366A1 (de) 1998-07-01 1999-06-24 Ventileinheit zur automatischen Regelung der Brenngasdurchflussmenge

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EP (1) EP0989366A1 (de)
IT (1) ITPD980164A1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6938634B2 (en) 2003-05-30 2005-09-06 Robertshaw Controls Company Fuel control mechanism and associated method of use
US6941962B2 (en) 2003-05-30 2005-09-13 Robertshaw Controls Company Convertible control device capable of regulating fluid pressure for multiple fluid types and associated method of use

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5525743A (en) * 1978-08-11 1980-02-23 Matsushita Electric Ind Co Ltd Fuel feed control system
JPS5525742A (en) * 1978-08-11 1980-02-23 Matsushita Electric Ind Co Ltd Fuel feed control system
EP0035147A1 (de) * 1980-02-22 1981-09-09 Joh. Vaillant GmbH u. Co. Gasdruckregler
JPS5824756A (ja) * 1982-07-22 1983-02-14 Youei Seisakusho:Kk ガス湯わかし器のガス量自動調節装置
EP0697563A1 (de) * 1994-08-17 1996-02-21 INTEGRA S.r.l. Ventilanordnung für einen Gazheizkessel

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5525743A (en) * 1978-08-11 1980-02-23 Matsushita Electric Ind Co Ltd Fuel feed control system
JPS5525742A (en) * 1978-08-11 1980-02-23 Matsushita Electric Ind Co Ltd Fuel feed control system
EP0035147A1 (de) * 1980-02-22 1981-09-09 Joh. Vaillant GmbH u. Co. Gasdruckregler
JPS5824756A (ja) * 1982-07-22 1983-02-14 Youei Seisakusho:Kk ガス湯わかし器のガス量自動調節装置
EP0697563A1 (de) * 1994-08-17 1996-02-21 INTEGRA S.r.l. Ventilanordnung für einen Gazheizkessel

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 004, no. 060 (M - 010) 6 May 1980 (1980-05-06) *
PATENT ABSTRACTS OF JAPAN vol. 007, no. 104 (M - 212) 6 May 1983 (1983-05-06) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6938634B2 (en) 2003-05-30 2005-09-06 Robertshaw Controls Company Fuel control mechanism and associated method of use
US6941962B2 (en) 2003-05-30 2005-09-13 Robertshaw Controls Company Convertible control device capable of regulating fluid pressure for multiple fluid types and associated method of use

Also Published As

Publication number Publication date
ITPD980164A1 (it) 2000-01-01

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