EP0697563A1 - Gas boiler valve assembly - Google Patents

Gas boiler valve assembly Download PDF

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Publication number
EP0697563A1
EP0697563A1 EP95112769A EP95112769A EP0697563A1 EP 0697563 A1 EP0697563 A1 EP 0697563A1 EP 95112769 A EP95112769 A EP 95112769A EP 95112769 A EP95112769 A EP 95112769A EP 0697563 A1 EP0697563 A1 EP 0697563A1
Authority
EP
European Patent Office
Prior art keywords
gas
burner
disk
valve assembly
valve seat
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Withdrawn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
EP95112769A
Other languages
German (de)
English (en)
French (fr)
Inventor
Giorgio Scanferla
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.)
INTEGRA Srl
Original Assignee
INTEGRA Srl
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 INTEGRA Srl filed Critical INTEGRA Srl
Publication of EP0697563A1 publication Critical patent/EP0697563A1/en
Withdrawn legal-status Critical Current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
    • F23N1/02—Regulating fuel supply conjointly with air supply
    • F23N1/027—Regulating fuel supply conjointly with air supply using mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N1/00—Regulating fuel supply
    • F23N1/007—Regulating fuel supply using mechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel
    • F23N5/188—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using mechanical means
    • 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
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel

Definitions

  • the present invention relates to a gas boiler valve assembly of the type comprising:
  • valve assembly of the present invention finds a preferred, although not exclusive, use in gas boilers of the so-called combined type equipped with a so-called "aired" burner.
  • boiler of the so-called combined type is meant to indicate a boiler capable of delivering either hot water for space heating or primary water and hot water for sanitary use.
  • aired boiler is meant a burner in which the combustion air is partly premixed with the combustible gas downstream of the nozzles feeding the gas to the burner (primary air) and partly fed downstream of the latter for completing combustion (secondary air).
  • valve assemblies of the so-called air-gas type which regulate the gas flow in response to the air flow fed to the burner and, hence, in response to the thermal power required.
  • valve assemblies of this type the gas flow fed to the burner is controlled between a minimum and a maximum value by intercepting a gas supply path, defined in the valve body and fed by the external gas distribution mains.
  • control is performed, starting from the maximum flow rate value, by means of a disk driven, as a function of the air flow fed to the burner, by a membrane controlled by a complex mechanical amplification system provided with levers.
  • the above mentioned membrane means are also operated, if necessary, by a gas flow limiting device, which drives the disk intercepting the gas supply path so as to limit the gas flow leaving the valve assembly below a predetermined maximum value.
  • the air-gas valve assemblies of the known type exhibit the acknowledged shortcoming of being unable to continuously control the thermal power of the burner over the whole variation range thereof.
  • the response limits of the membrane means designed to intercept the combustible gas path do not allow to reduce the gas flow leaving the valve assembly below a minimum threshold value, below which an extremely irregular gas delivery with a resulting instability of the entire boiler control system is observed.
  • the impossibility of continuously controlling the gas flow implies an on-off operation of the valve assembly and burner and causes further undesirable shortcomings such as a delivery of hot sanitary water at oscillating temperatures (hunting), a high boiler noise and a significant emission of unburnt gas upon every on-off cycle of the burner.
  • the technical problem underlying the present invention is thus to make available a gas boiler valve assembly which allows to continuously control the thermal power of the burner over the entire variation range thereof, while overcoming at the same time the shortcomings cited with reference to the above-mentioned prior art.
  • valve assembly of the above mentioned type which is characterized in that it further comprises, in said limiting device, means for adjustably positioning said second disk in said second valve seat, said means being driven in response to the thermal power required to the burner to adjustably position said first disk in said first valve seat by means of said membrane means.
  • the disk designed to intercept the combustible gas path and regulate the gas flow leaving the valve assembly is controlled in a first modulation range by a pneumatic control device, sensitive to any variation in the air flow fed to the burner and, in a second modulation range, by a solenoid-operated limiting-regulating device, operated by an electrical signal proportional to the thermal power required to the burner.
  • the solenoid-operated limiting-regulating device can modulate the gas flow (thermal power) either simultaneously with the pneumatic control device, or outside the sensitivity limits of the latter.
  • reference number 1 indicates a valve assembly designed to control the flow rate of a combustible gas fed to a conventional aired burner (not shown), of a boiler of the so-called combined type also of conventional type and not shown.
  • the valve assembly 1 essentially comprises a valve body 2 in which a gas path 3, extending between a gas inlet opening 4 and a gas outlet opening 5, is defined.
  • the openings 4, 5 are internally threaded to be coupled by means of screwing to the free ends of ducts 6, 7 by means of which the gas is fed into the valve body 2 and, respectively, conveyed to the burner.
  • a core member indicated by reference 8 is integrally formed within the valve body 2 and divides the gas path 3 in two upstream 3a and downstream 3b consecutive sections.
  • the core member 8 is also appropriately shaped so as to define in the upstream section 3a of the gas path 3 two contiguous chambers 9, 10 in mutual fluid communication through an opening 11 which essentially constitutes a valve seat on which a disk 12 is positionable in a gas-tight manner against the action of a spring 13.
  • Said disk is mounted in a conventional manner at one end of a stem 14 operated in a conventional manner not shown by a solenoid 15 driven by a flame sensor also not shown because entirely conventional.
  • upstream and downstream sections 3a, 3b of the fluid path 3 are also in mutual fluid communication through an opening 16, essentially coplanar to the previous one, also constituting a valve seat in which a disk 17 may be adjustably positioned, in a gastight manner, against the action of respective spring means 18.
  • valve seat 16 and the disk 17 will be indicated below by the terms: main valve seat and, respectively, main disk.
  • the main disk 17 is mounted, in a conventional manner, on one end of a stem 19 slidably guided in a corresponding seat 20 formed in the core member 8, whose other end is operated by a membrane 21.
  • the membrane 21 is operated in turn by a control device 22, which is driven by the air flow rate fed to the burner, and/or by a control and limiting device 23 which is operated in response to an electrical signal proportional to the thermal power required to the burner and which will be described in more detail hereinbelow.
  • the chamber 10 formed in the upstream section 3a of the gas path 3 is selectively connected to an airspace 24 defined between the membrane 21 and the valve body 2, by means of a first duct 25, a chamber 26 and a second duct 27 which constitute together a gas path placed in parallel to the gas path 3.
  • the outlet opening of the duct 25 is selectively intercepted by a disk 29 mounted, in a conventional manner, on one end of an arm 28 supported in a rotating manner in the chamber 26 and whose other end is operated by the core member 31 of a solenoid 32.
  • the disk 29 moves between opposite positions in which it closes and, respectively, opens the duct 25 against the action of counteracting spring means 30.
  • the chamber 10 is also in selective fluid communication with the downstream section 3b of the gas path 3, through a passageway 35 by-passing the main valve seat 16, comprising: the duct 25, the chamber 26 and a pair of calibrated ducts 33, 34 formed in the valve body 2 between the chamber 26 and the above-mentioned downstream section 3b.
  • the above mentioned by-pass passageway 35 forms an integral part of the gas flow control and limiting device 23, by which it is adjustably intercepted by means of a disk 36, cooperating with a respective valve seat 37 formed at an end of the duct 33 opposite the chamber 26.
  • the disk 36 is connected in a conventional manner to a membrane 38 and is operated against the action of counteracting spring means 39 by the moving core member 40 of a solenoid 41, driven in a known manner by an electrical signal proportional to the thermal power required to the burner.
  • the moving core member 40 is in particular mounted in a hole 58 axially formed within a central body of the solenoid 41 in which it is slidably guided against the action of a counteracting spring 56.
  • the opposite ends of the spring 56 abut against the moving core member 40 and, respectively, the fixed core member 55 of the solenoid 41, which may be adjustably and variably positioned within the hole 58.
  • a nut 57 operable from the outside of the valve assembly 1 blocks the fixed core member 55 in the selected position.
  • the compression degree of the spring 56 and, accordingly, the force exerted by the spring 56 on the core member 40 may be adjusted.
  • the stroke of the core member 40 and thus the maximum opening of the by-pass passageway 35 may also be adjusted by means of a rod 42, operable from the outside of the valve assembly of the present invention, which essentially constitutes an adjustable stop for the core member.
  • the regulating device 22 operating the membrane 21 comprises a unit 46, sensitive to the air flow fed to the burner, which drives a disk 45 allowing a selective fluid communication between the airspace 24 and the downstream section 3b of the gas path 3.
  • the disk 45 intercepts a further gas passageway by-passing the main valve seat 16, including a pair of ducts 43, 44 formed in the valve body 2 downstream of the airspace 24.
  • the disk 45 is conventionally supported by a stem 47, slidably guided in a corresponding seat formed in the valve body 2, which is fixed in turn to one end of an arm 48 operated in a conventional manner by a membrane 49 against the action of first and second spring means 50, 51.
  • the membrane 49 is supported within a chamber 52 which is divided thereby in two portions 52a, 52b connected upstream and, respectively, downstream of a device, not shown, designed to detect any variation in the air flow fed to the burner.
  • the force exerted by the spring means 50 and 51 on the disk 45 and, respectively, on the membrane 49 may be adjusted by providing appropriate pretensioning means entirely conventional and not shown.
  • valve assembly 1 In operation, the valve assembly 1 described above allows to regulate the gas flow (thermal power) of a boiler from a minimum to a maximum value including the entire range of intermediate values.
  • a special control unit provided in the boiler body activates a blower feeding air to the burner and starts the opening step of the valve assembly 1.
  • the gas is free to flow sequentially into the chamber 10 of the upstream section 3a of the gas path 3, into the duct 25, into the chamber 26, and into the duct 27 up to the airspace 24 located below the membrane 21 operating the main disk 17.
  • the pressure created in the airspace 24 causes a gradual upward movement of the main disk 17 from the corresponding valve seat 16, allowing gas to flow into the downstream section 3b of the gas path and then to be discharged from the valve assembly 1.
  • valve assembly 1 switches to the gas flow control mode, so that the gas flow is adjusted, depending upon the thermal power required to the burner, either by the regulating device 22 as a function of a pressure drop ( ⁇ P) appropriately amplified by the unit 46 and/or by the control and limiting device 23 as a function of an electrical signal sent to the solenoid 41.
  • ⁇ P pressure drop
  • a first control or modulation range - proximate to a preset maximum boiler thermal power - the gas flow fed to the boiler and thus the power delivered thereby is controlled by the device 22, which drives the main disk 17 in response to any variation of the air flow detected and appropriately amplified by the unit 46.
  • the stem 47 is lowered with a gradual displacement of the disk 45 away from the outlet of the duct 43.
  • the gas flow through the main valve seat 16 and the gas path 3 is modulated by the disk 45 (modulating disk) in response to the air flow variations detected by the unit 46.
  • each increase in the air flow will induce a corresponding increase in the pressure drop ( ⁇ P) detected by the unit 46: this implies an increased pressure on the membrane 49 against the action of the spring 51, with an ensuing downward movement of the membrane and a corresponding counterclockwise rotation of the arm 48 (viewing the figure).
  • this value may not exceed a threshold value, set during design and determined by the control and limiting device 23.
  • the calibration of the spring 39 may be readily effected by adjusting the compression degree of the spring 56, acting on the moving core member 40, which possesses a force greater than that of the spring 39.
  • This adjustment is performed by locking in a predetermined position the fixed core member 55 in the hole 48 by means of the nut 57.
  • the springs 50 and 51 may also be set in advance either the minimum pressure drop ( ⁇ P) capable of displacing the membrane 49, or the maximum extent of the opening stroke of the disk 45 to which corresponds the maximum opening of the duct 43 (lower regulation limit of the device 22).
  • ⁇ P minimum pressure drop
  • the gas flow regulation carried out by the device 22 takes place in a modulation range spanning from the maximum flow to approximately 1/3 of this value (maximum modulation ratio 3.5-3:1), i.e. up to the sensitivity limits of the membrane 49.
  • valve assembly 1 carries out the desired gas flow regulation by means of the control and limiting device 23, directly driven by the boiler control unit.
  • the solenoid 41 of the control device 23 effects a progressive upward movement of the core member 40 and, along therewith, a progressive upward upward movement of the disk 36, proportional to the decrease in required power.
  • the gas flow through the main valve seat 16 and the gas path 3 is modulated by the disk 36 (modulating disk) in response to an electrical signal sent to the solenoid 41 and proportional to the required thermal power.
  • the gas flow regulation carried out by the control and limiting device 23 takes place in a modulation range spanning from approximately 1/3 of the maximum flow up to a minimum compatible with a steady burner operation.
  • this value is less than the minimum thermal power required to the gas boilers presently available on the market.
  • valve assembly of the present invention is capable of adjusting with continuity the gas flow (thermal power) and thus ensure modulation ratios higher than the maximum values required today (6-7:1).
  • the minimum flow (thermal power) achievable may be controlled, depending upon the boiler characteristics, by merely positioning the stop rod 42 in the solenoid 41.
  • a first significant advantage is related to the possibility, on the one hand, to broaden the gas flow (thermal power) modulation range up to the maximum extent thereof and, on the other hand, to ensure a high efficiency of the burner substantially over the entire modulation range.
  • valve assembly of the present invention allows to achieve the above mentioned relevant advantages at a cost quite comparable with that of the air-gas control units presently available on the market.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Feeding And Controlling Fuel (AREA)
EP95112769A 1994-08-17 1995-08-14 Gas boiler valve assembly Withdrawn EP0697563A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITMI941747A IT1274622B (it) 1994-08-17 1994-08-17 Gruppo valvolare per caldaie a gas
ITMI941747 1994-08-17

Publications (1)

Publication Number Publication Date
EP0697563A1 true EP0697563A1 (en) 1996-02-21

Family

ID=11369480

Family Applications (1)

Application Number Title Priority Date Filing Date
EP95112769A Withdrawn EP0697563A1 (en) 1994-08-17 1995-08-14 Gas boiler valve assembly

Country Status (2)

Country Link
EP (1) EP0697563A1 (it)
IT (1) IT1274622B (it)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0800039A1 (en) * 1996-04-02 1997-10-08 SIT LA PRECISA S.r.l. A valve unit for controlling the delivery pressure of a gas
EP0989366A1 (en) * 1998-07-01 2000-03-29 Sit la Precisa S.p.a. A valve unit for automatically regulating the flow-rate of a fuel gas
WO2001065182A2 (en) * 2000-02-28 2001-09-07 Honeywell International Inc. Pressure proving gas valve
EP0957314A3 (de) * 1998-05-15 2002-03-13 Honeywell B.V. Regeleinrichtung für Gasbrenner
EP1959326A1 (en) * 2005-12-05 2008-08-20 Time Engineering Co., Ltd. Governor device
JP2015048968A (ja) * 2013-08-30 2015-03-16 株式会社パロマ 加熱調理器

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0036613A1 (de) * 1980-03-20 1981-09-30 Honeywell B.V. Durch einen Temperaturfühler steuerbare Regeleinrichtung für einen gasbefeuerten Wasser- oder Lufterhitzer
EP0103303A2 (de) * 1982-09-15 1984-03-21 Joh. Vaillant GmbH u. Co. Brennstoffbeheizte Wärmequelle
EP0390964A2 (de) * 1989-04-07 1990-10-10 Honeywell B.V. Regeleinrichtung für Gasbrenner
DE9101263U1 (de) * 1990-02-02 1991-04-25 Joh. Vaillant Gmbh U. Co, 5630 Remscheid Gasdruckregler
EP0532453A1 (de) * 1991-09-09 1993-03-17 Joh. Vaillant GmbH u. Co. Servodruckregler

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0036613A1 (de) * 1980-03-20 1981-09-30 Honeywell B.V. Durch einen Temperaturfühler steuerbare Regeleinrichtung für einen gasbefeuerten Wasser- oder Lufterhitzer
EP0103303A2 (de) * 1982-09-15 1984-03-21 Joh. Vaillant GmbH u. Co. Brennstoffbeheizte Wärmequelle
EP0390964A2 (de) * 1989-04-07 1990-10-10 Honeywell B.V. Regeleinrichtung für Gasbrenner
DE9101263U1 (de) * 1990-02-02 1991-04-25 Joh. Vaillant Gmbh U. Co, 5630 Remscheid Gasdruckregler
EP0532453A1 (de) * 1991-09-09 1993-03-17 Joh. Vaillant GmbH u. Co. Servodruckregler

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0800039A1 (en) * 1996-04-02 1997-10-08 SIT LA PRECISA S.r.l. A valve unit for controlling the delivery pressure of a gas
US6003544A (en) * 1996-04-02 1999-12-21 Sit La Precisa S.R.L. Valve unit for controlling the delivery pressure of a gas
EP0957314A3 (de) * 1998-05-15 2002-03-13 Honeywell B.V. Regeleinrichtung für Gasbrenner
EP0989366A1 (en) * 1998-07-01 2000-03-29 Sit la Precisa S.p.a. A valve unit for automatically regulating the flow-rate of a fuel gas
WO2001065182A2 (en) * 2000-02-28 2001-09-07 Honeywell International Inc. Pressure proving gas valve
WO2001065182A3 (en) * 2000-02-28 2002-01-24 Honeywell Int Inc Pressure proving gas valve
US6571817B1 (en) 2000-02-28 2003-06-03 Honeywell International Inc. Pressure proving gas valve
EP1959326A1 (en) * 2005-12-05 2008-08-20 Time Engineering Co., Ltd. Governor device
EP1959326A4 (en) * 2005-12-05 2012-01-11 Siemens Building Tech Ag REGULATOR DEVICE
JP2015048968A (ja) * 2013-08-30 2015-03-16 株式会社パロマ 加熱調理器

Also Published As

Publication number Publication date
ITMI941747A0 (it) 1994-08-17
IT1274622B (it) 1997-07-18
ITMI941747A1 (it) 1996-02-17

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