GB2251963A - Gas flow control system - Google Patents
Gas flow control system Download PDFInfo
- Publication number
- GB2251963A GB2251963A GB9124268A GB9124268A GB2251963A GB 2251963 A GB2251963 A GB 2251963A GB 9124268 A GB9124268 A GB 9124268A GB 9124268 A GB9124268 A GB 9124268A GB 2251963 A GB2251963 A GB 2251963A
- Authority
- GB
- United Kingdom
- Prior art keywords
- flow rate
- gas
- proportional valve
- shape memory
- memory alloy
- 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- Withdrawn
Links
Classifications
-
- 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
- F23N5/184—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel using electronic means
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1919—Control of temperature characterised by the use of electric means characterised by the type of controller
- G05D23/1921—Control of temperature characterised by the use of electric means characterised by the type of controller using a thermal motor
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/20—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature
- G05D23/24—Control of temperature characterised by the use of electric means with sensing elements having variation of electric or magnetic properties with change of temperature the sensing element having a resistance varying with temperature, e.g. a thermistor
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2231/00—Fail safe
- F23N2231/16—Fail safe using melting materials or shape memory alloys
-
- 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
- F23N2235/14—Fuel valves electromagnetically operated
Abstract
A gas flow control system for controlling the flow rate of gas based on a set desired temperature Tsp by means of a proportional valve 3 comprising a shape memory alloy member for controlling the opening of said proportional valve by supplying said shape memory alloy member with an electric current. A gas flow sensor 6 is disposed at a location downstream of said proportional valve for sensing the flow rate of gas outputted from the proportional valve. A controller 14 compares the sensed flow rate with a flow rate corresponding to the set desired temperature to control (5) the electric current supplied to said proportional valve in accordance with the comparison result so as to regulate the flow rate of gas. The flow rate of gas thus regulated is not influenced by changes in characteristics of the shape memory alloy member caused by ambient environment, aging change, and so on. The gas flow control system may be used in a water heater. A proportional valve is detailed (Fig. 3). <IMAGE>
Description
GAS FLOW CONTROL SYSTEM
This invention generally relates to a gas flow control system, and more particularly, to an improved proportional valve employed in a gas flow control system which is adapted to regulate the flow rate of gas corresponding to a desired set temperature.
Heretofore, as a gas proportioning valve for controlling the flow rate of gas, there has been known a proportioning valve using a shape memory alloy.
According to this proportioning valve, an electric current is applied to a string shape memory alloy to generate heat, causing the temperature of the shape memory alloy itself to rise up to a transformation point thereof to transform the alloy, thereby opening and closing the valve.
In such a conventional proportioning valve using a shape memory alloy, however, the characteristics of the shape memory alloy may vary depending on the ambient temperature around the alloy and the frequency of opening and closing of the valve. Therefore, the conventional proportioning valve in question involves a problem that even if the same electric current is applied to the valve, the flow rate of gas is not always the same.
Moreover, since the shape memory alloy is slow in response, the flow rate of gas does not promptly follow a change in an electric current applied to the valve to transform the shape memory alloy member. Due to these drawbacks, it has heretofore been considered difficult to employ a gas proportioning valve using a shape memory alloy in a hot water supply apparatus.
The present invention has been accomplished for solving the above-mentioned problems, and it is an object of the invention to provide a gas flow control system which, upon change in characteristics of a shape memory alloy in a gas proportioning valve using the said alloy, can correct it and afford a target gas flow rate immediately.
In order to achieve the above-mentioned object, in the gas flow control system for controlling the flow rate of gas based on a set desired temperature by means of a proportional valve comprising a shape memory alloy member for controlling the opening of said proportional valve by supplying said shape memory alloy member with an electric current, said gas flow control system comprises a gas flow sensor means, disposed at a location downstream of said proportional valve, for sensing the flow rate of gas outputted from said proportional valve and generating a signal representing said sensed flow rate and a control means coupled to receive said signal representing said sensed flow rate for comparing said sensed flow rate with a flow rate corresponding to said set desired temperature to control the electric current supplied to said proportional valve in accordance with the comparison result so as to regulate the flow rate of gas.
Other objects and advantages of the present invention will become more apparent from the following detailed description of an embodiment of the invention taken in connection with the accompanying drawings in which:
Fig. 1 is a diagram showing the configuration of a gas flow control system according to an embodiment of the present invention;
Fig. 2 is a block diagram showing control elements used in the said system; and
Fig. 3 is a partially cut-away perspective view showing a proportioning valve used in the said system.
An embodiment of the present invention will be described hereinunder with reference to the drawings.
Fig. 1 illustrates an embodiment in which the present invention is applied to a hot water supplying apparatus. In Fig. 1, the reference numeral 1 denotes a burner; the numeral 2 denotes a gas pipe for the supply of gas to the burner 1; numeral 3 denotes a proportioning valve using a shape memory alloy member for controlling the flow rate of gas in the gas pipe 2; and numeral 4 denotes a water distributing pipe for distributing water heated by the burner 1, the pipe 4 having a water inlet 4a and a hot water outlet 4b.
Numeral 5 denotes a drive circuit which supplies an electric current to the proportioning valve 3; numeral 6 denotes a gas flow sensor for detecting an actual flow rate of gas supplied through the proportioning valve 3 to the burner 1; numeral 7 denotes a temperature setting device for setting the temperature of hot water; numeral 8 denotes a flow sensor for detecting the flow rate of water flowing through the water distributing pipe 4; numeral 9 denotes a hot water thermistor for detecting the temperature of hot water; and numeral 10 denotes a water temperature sensor for detecting the temperature of water.
Numeral 11 denotes a bias current circuit for supplying a bias current continuously to the proportioning valve 3 through the drive circuit 5; numeral 12 denotes a maximum current limiting circuit for limiting the electric current fed from the drive circuit 5 to the proportioning valve 3 to a predetermined maximum value; and numeral 13 denotes a proportioning valve voltage detecting circuit for detecting the voltage across a shape memory alloy member used in the proportioning valve 3.
Numeral 14 denotes a microcomputer functioning as a control section which calculates the electric current fed to the proportioning valve, the above bias current, etc. on the basis of detected values from the above sensors, set temperatures, etc.
Fig. 2 conceptually illustrates control elements in the control system of Fig. 1, in which the same portions as those in Fig. 1 are indicated by the same reference numerals.
In Fig. 2, the portion enclosed with the dotted line represents the microcomputer 14 which is provided with comparators 15, 16 and P.I.D calculating units 17, 18. In the illustrated embodiment, the bias current circuit 11 is disposed within the microcomputer.
Fig. 3 schematically shows an example of the proportioning valve 3. In the same figure, the numeral 31 denotes a cylindrical case having a gas inlet 31a and a gas outlet 31b. Numeral 32 denotes a string-like shape memory alloy member in a V-shape; numeral 33 denotes a valve body made of rubber or the like, the opening of which is adjusted by transformation of the shape memory alloy 32; numeral 34 denotes a spring for urging the valve body 33; and numerals 35 and 36 represent current supplying terminals connected to both ends of the shape memory alloy member 32. The drive circuit 5 and the proportioning valve voltage detecting circuit 13 are connected to the terminals 35 and 36.
The operation of the gas flow control system having the above construction will now be described.
In Figs. 1 and 2, when a combustion sequence in the hot water supplying apparatus is started, the microcomputer 14 performs a feed forward control and P.I.D calculation in the P.I.D calculating unit 17 on the basis of the temperature, Tsp, set by the temperature setting device 7, the temperature of incoming water detected by the water temperature thermistor 10, the flow rate of incoming water detected by the flow sensor 8 and the temperature, Tpv, of hot water detected by the hot water thermistor 9, and determines a gas flow set value (required input), Gsp.
Further, by performing P.I.D calculation in the
P.I.D calculating unit 18 on the basis of the gas flow set value Gsp and an actual gas flow rate Gpv which is fed back from the gas flow sensor, a current value is determined such that the Gpv and Gsp coincide with each other. In accordance with this current value the drive circuit 5 supplies an electric current to the proportioning valve 3, whereby the flow rate of gas is controlled. In this event, the above current value is limited to a predetermined maximum value by the maximum current limiting circuit 12, thereby preventing the shape memory alloy member 32 from being overheated.
Besides, a suitable bias current is fed continuously to the proportioning valve 3 by the bias current circuit 11 to thereby.prevent a temperature drop of the shape memory alloy member 32 and prevent the shortening of the service life of the same caused by such temperature drop.
Further, since the transformation of the shape memory alloy member 32 causes its resistance value to vary, it is possible to check changes in its characteristics by detecting such varying resistance values by the proportioning valve voltage detecting circuit 13.
It will be appreciated from the above description that according to the present invention the electric current supplied to the proportioning valve is controlled based on the difference between a flow rate of gas outputted from the proportioning valve and a set flow rate to regulate the target or set flow rate without being influenced by changes in characteristics of the shape memory alloy member.
It will of course be understood that the present invention has been described above purely by way of example, and that modifications in detail can be made within the scope of this invention.
Claims (2)
1. A gas flow control system for controlling the flow rate of gas based on a set desired temperature by means of a proportional valve comprising a shape memory alloy member for controlling the opening of said proportional valve by supplying said shape memory alloy member with an electric current, said gas flow control system comprising:
a gas flow sensor means, disposed at a location downstream of said proportional valve, for sensing the flow rate of gas outputted from said proportional valve and generating a signal representing said sensed flow rate; and
a control means coupled to receive said signal representing said sensed flow rate for comparing said sensed flow rate with a flow rate corresponding to said set desired temperature to control the electric current supplied to said proportional valve in accordance with the comparison result so as to regulate the flow rate of gas.
2. A gas flow control system substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2331485A JP2718821B2 (en) | 1990-11-29 | 1990-11-29 | Gas flow control device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9124268D0 GB9124268D0 (en) | 1992-01-08 |
| GB2251963A true GB2251963A (en) | 1992-07-22 |
Family
ID=18244174
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9124268A Withdrawn GB2251963A (en) | 1990-11-29 | 1991-11-15 | Gas flow control system |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JP2718821B2 (en) |
| GB (1) | GB2251963A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU696863B2 (en) * | 1994-07-15 | 1998-09-17 | Daewoo Electronics Co., Ltd. | Valve utilizing shape memory alloys and an anti-lock brake system with the valve |
| US6076542A (en) * | 1995-12-01 | 2000-06-20 | Perception Incorporated | Fluid metering method |
| US6202679B1 (en) | 1995-12-01 | 2001-03-20 | Perception Incorporated | Fluid metering apparatus |
| WO2002090807A1 (en) | 2001-05-08 | 2002-11-14 | Scuola Superiore Di Studi Universitari E Di Perfezionamento S. Anna | Proportional valve with shape memory alloy (sma) actuator |
| CN108594897A (en) * | 2018-03-14 | 2018-09-28 | 西安电子科技大学 | Based on temperature controlled shape memory cable net structure type face precision active regulating system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4199981A (en) * | 1977-02-16 | 1980-04-29 | Wen Young | Flow control device for fluids flowing in a closed conduit |
| US4645489A (en) * | 1982-11-30 | 1987-02-24 | Beta Phase, Inc. | Fluid delivery apparatus with shape-memory flow control element |
| US4838483A (en) * | 1988-04-11 | 1989-06-13 | American Standard Inc. | Vav valve control with transducer tolerance compensation |
| EP0371597A2 (en) * | 1988-11-28 | 1990-06-06 | Mks Instruments, Inc. | Flow controller |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS63214599A (en) * | 1987-03-02 | 1988-09-07 | Toshiba Corp | Control device for liquefied natural gas gasifying facility |
| JPH01208614A (en) * | 1988-02-13 | 1989-08-22 | Ishikawajima Harima Heavy Ind Co Ltd | Fuel pressure controller for boiler |
| JP2586582B2 (en) * | 1988-06-20 | 1997-03-05 | 日本電気株式会社 | Driving method of liquid crystal display device |
| JPH0830574B2 (en) * | 1988-06-29 | 1996-03-27 | 株式会社東芝 | Combustion control device |
| JP2563532B2 (en) * | 1988-10-28 | 1996-12-11 | 松下電器産業株式会社 | Gas combustion amount control device |
-
1990
- 1990-11-29 JP JP2331485A patent/JP2718821B2/en not_active Expired - Lifetime
-
1991
- 1991-11-15 GB GB9124268A patent/GB2251963A/en not_active Withdrawn
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4199981A (en) * | 1977-02-16 | 1980-04-29 | Wen Young | Flow control device for fluids flowing in a closed conduit |
| US4645489A (en) * | 1982-11-30 | 1987-02-24 | Beta Phase, Inc. | Fluid delivery apparatus with shape-memory flow control element |
| US4838483A (en) * | 1988-04-11 | 1989-06-13 | American Standard Inc. | Vav valve control with transducer tolerance compensation |
| EP0371597A2 (en) * | 1988-11-28 | 1990-06-06 | Mks Instruments, Inc. | Flow controller |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU696863B2 (en) * | 1994-07-15 | 1998-09-17 | Daewoo Electronics Co., Ltd. | Valve utilizing shape memory alloys and an anti-lock brake system with the valve |
| US6076542A (en) * | 1995-12-01 | 2000-06-20 | Perception Incorporated | Fluid metering method |
| US6202679B1 (en) | 1995-12-01 | 2001-03-20 | Perception Incorporated | Fluid metering apparatus |
| US6460565B1 (en) * | 1995-12-01 | 2002-10-08 | Perception Incorporated | Fluid metering apparatus and method |
| WO2002090807A1 (en) | 2001-05-08 | 2002-11-14 | Scuola Superiore Di Studi Universitari E Di Perfezionamento S. Anna | Proportional valve with shape memory alloy (sma) actuator |
| CN108594897A (en) * | 2018-03-14 | 2018-09-28 | 西安电子科技大学 | Based on temperature controlled shape memory cable net structure type face precision active regulating system |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2718821B2 (en) | 1998-02-25 |
| GB9124268D0 (en) | 1992-01-08 |
| JPH04198611A (en) | 1992-07-20 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |