GB2191022A

GB2191022A - A fluid heating apparatus

Info

Publication number: GB2191022A
Application number: GB08704505A
Authority: GB
Inventors: Ikuro Adachi
Original assignee: Rinnai Corp
Current assignee: Rinnai Corp
Priority date: 1986-05-27
Filing date: 1987-02-26
Publication date: 1987-12-02
Anticipated expiration: 2007-02-26
Also published as: DE3716641C2; JPS62280516A; GB8704505D0; KR870011422A; JPH0378529B2; FR2599473B1; KR910002737B1; FR2599473A1; GB2191022B; DE3716641A1

Description

GB 2 191022A 1

SPECIFICATION heater;

Fig. 3 is an electrical wiring diagram of an A fluid heating apparatus r.p.m. detecting circuit; Fig. 4 is a graph showing the relationship The present invention relates to a fluid heating 70 between the r.p.m. of the blower and the out apparatus in which fuel gas is fed through a put from the r.p.m. detecting circuit; variable flow-regulating valve, and air is sup Fig. 5 is a graph showing the relationship plied by means of a blower, and particularly between the output of the r. p.m. detecting concerns a fluid heater improved so as to circuit and the electrical current supplied to a control both the blower and the variable flow- 75 variable flowregulating valve; regulating valve simultaneously in response to Fig. 6 is a graph showing the normal output adjustment of the desired temperature setting. of a thermo-couple against the output of the In a fluid heating apparatus suitable for a r.p.m. detecting circuit; water heater e.g. for space heating, flammable Fig. 7 is a block diagram of a control circuit gas such as vaporized kerosene is fed through 80 according to a second embodiment of the in - a flow-regulating valve and air is supplied by vention; means of a blower for combustion. Fig. 8 is a view similar to Fig. 6; The variable flow-regulating valve determines Fig. 9 is a block diagram of a control circuit the amount of fuel fed in response to adjustaccording to a third embodiment of the inven ment of the desired temperature setting. On 85 tion; the other hand, a temperature sensor is pro- Fig. 10 is a block diagram of a control cir vided to detect the air/fuel ratio by measuring cuit according to a fourth embodiment of the the temperature of the flame, so as to control invention; and the blower. Fig. 11 is a graph showing the normal out- As aforementioned, the variable flow-regu- 90 put of the thermo-couple against the output of lating valve and the blower are individually a heat adjustment circuit.

controlled, so that the blower is controlled by Fig. 2 shows a water heating device 1 ac- the output of the temperature sensor in re- cording to the present invention, which in sponse to the adjustment of desired setting, cludes a burner portion 3 having a heat ex- changing the amount of air supplied. This re- 95 changer 2, a flammable gas supply conduit 4, sults in very slow response of the blower to and an electronic control circuit 5. The burner the heat adjustment operation. portion 3 has a chamber 32 in which a cera Accordingly, it is an object of the present mic burner 31 is placed. Under the chamber invention to provide a burner apparatus which 32, is an air supply portion 34 provided into is capable of ensuring a quick change in rate 100 which a blower 33 is incorporated. Above the of fuel supply in response to that of air sup- chamber 32, there is provided an exhaust ply, so as to maintain a predetermined fuel-air opening 35 through which exhaust gas from ratio, at any heat adjustment level. the burner 31 may pass. The heat exchanger According to the present invention there is 2 has a water conduit 22 having a series of provided a fluid heating apparatus comprising: 105 fins 21, allowing transfer of heat to the water a burner plate; a varia ble flow-regulating flowing in the conduit 22 so as to supply hot valve, through which fuel gas flows into said water.

burner plate; a blower which supplies air to The gas supply conduit 4 has a nozzle 41 said burner plate; a temperature sensor which which ejects flammable gas from a gas supply detects the temperature of said burner plate; a 110 pipe 42. At the upper reach of the gas supply first control circuit which is responsive to the pipe 42, a valve 43 is provided to be ener temperature of output fluid and to a selected gized and deenergized for opening and clo target temperature therefor, said circuit con- sure. At the lower reach of the valve 43, a trolling one of said valve and said blower; a governor valve 44 is arranged the adjust flow second control circuit which controls the other 115 of the gas. A variable flow-regulating valve 45 of the valve and blower and is responsive to is disposed at the lower reach of the governor the output of the first control circuit or to the valve 44 to change its opening degree accord condition of said one of the valve and blower; ing to electrical current supplied.

and a compensation control circuit which pro- A pair of spaced electrodes 51 is disposed vides an additional control to the said other of 120 on the burner plate 31 to create a spark ther the valve and blower in accordance with the ebetween at the time of igniting the gas. A output of the temperature sensor. thermo-couple 52 is provided as a tempera In order that the invention may be more ture-sensor above the burner plate 31 to de readily understood the following description is tect air-fuel ratio by means of the electronic given by way of example only, with reference 125 control circuit 5. A water temperature sensor to the accompanying drawings in which: 53 is attached to the water supply pipe 22 of Fig. 1 is a block diagram of a controller the heat exchanger 2 so that the water tem according to a first embodiment of the inven- perature may be controlled by the electronic tion; control circuit 5. The circuit 5 controls the Fig. 2 is a schematic view of a water 130 temperature of the water coming from the 2 GB2191022A 2 supply pipe 22 of the heat exchanger 2 when sired water temperature so that the blower operated by means of a knob 54, so that a control circuit 61 instantaneously changes its blower 33, valve 43 and variable flow-regulat- output voltage in response to the output from ing valve 45 work as designed. the water temperature sensor 53, so as to Now, attention is called to Fig. 1 which 70 determine the r.p.m. of the blower 33. The shows how the opening degree of the flow- change in the r.p.m. of the blower 33 varies regulating valve 45 is controlled and how the the output voltage (V) of the valve opening amount of air supplied to the blower 33 is circuit 63a so as to determine the amount of controlled. According to Fig. 1, a blower con- energisation of the variable flow-regulating trol circuit 61 which acts as a temperature 75 valve 45 in accordance with Fig. 5.

adjustment circuit, is provided to adjust the This is to say, the operation of the knob 54 temperature of hot water flowing through the substantially changes both the r.p.m. of the supply pipe 22. This is accomplished by com- blower 33 and the opening degree of the paring output signal from the water tempera- flow-regulating valve 45 simultaneously, so ture sensor 53 with reference voltage from 80 that the hot water of the desired temperature the operation of the knob 54 to control the is quickly available. With the simultaneous amount of energisation of the blower 33. An change of both opening degree of the valve r.p.m. detecting circuit 62 is provided to de- 45 and r.p.m. of the blower 33, the amount tect the amount of air supplied by the blower of air from the blower 33 and that of fuel gas 33 by detecting the r.p.m. of the blower 33. 85 is maintained in appropriate proportion to ob A variable flow-regulating valve control circuit tain normal airfuel ratio.

63 is provided to control the amount of fuel In cases in which the airfuel ratio deviates gas by adjusting the opening degree of the from the normal value due to the change of flow-regulating valve 45 in response to the component of the fuel gas, or increased flow ouputs from the r.p.m. detecting circuit 62 90 resistance at the air inlet or outlet, the r.p.m.

and the thermo-couple 52. detecting circuit 62 has output voltage (V) In so doing, the flow-regulating valve circuit equal to value (A1) when the thermo-couple 63 includes a valve opening circuit 63a which 52 has output voltage (mV) equal to value determines the opening degree according to (A3) to show fuel rich condition. With this the output from the r.p.m. detecting circuit 95 case, the flow-regulating valve 45 acts to de 62. The valve circuit 63 further includes a crease the opening degree, by making up for compensation circuit 63b which makes up for the amount of energisation toward the valve the output from the valve opening circuit 63a, 45 so as to return the output voltage (mV) of so that the thermocouple 52 outputs as deter- the thermo-couple 52 back to the normal mined according to the output from the r.p.m. 100 value (A3).

detecting circuit 62. On the other hand, when the r.p.m. measur The r.p.m. detecting circuit 62 is comprised ing circuit 62 indicates the output voltage (V) as shown in Fig. 3 by way of illustration. In at value (A1), with the thermo-couple 52 indi the r.p.m. detecting circuit 62, a brushless cating the output voltage at (A4), this shows electric motor is incorporated into the blower 105 fuel-lean condition.

33 in which a permanent magnet 33b is se- This fuel-lean condition acts to increase the cured to a rotary shaft 33a of the motor. In opening degree of the flow- regulating valve 45 addition to the magnet 33b, the r.p.m. detect- by increasing the amount of energisation of ing circuit 62 has a hall device 33c, a signal the valve 45 so as to return the normal value generator 62a which includes coils (C01)- 110 (A3). Thus the air-fuel ratio remains normal (C04), an analogue switch means 62b, a de- during operation.

coder 62c, and a voltage tranducer 62d. The The sensor 53 monitors the temperature of tranducer 62d changes its voltage (V) in pro- the hot water, and the blower control circuit portion with the revolution (N) of the blower 61 controls the flow- regulating valve 63 so 33 within the range of a certain voltage as 115 the temperature measured by the sensor 53 seen in Fig. 4. The valve opening circuit 63a corresponds with the temperature set by the determines the amount of energisation (A) of knob 54, and thus the flow- regulating valve the variable flow-regulating valve 45 according 45 is controlled at its opening degree as to the output voltage (V) from the r.p.m. de- quickly as the sensor 53 detects the tempera tecting circuit 62 as seen in Fig. 5. The com- 120 ture of the hot water. This acts to compen pensation circuit 63b makes up for the sate the temperature of the hot water which amount of the energisation of the valves 45, is served from the water heater 1 as deter so that the thermo-couple 52 outputs the vol- mined by the knob 54.

tage (mV) as previously determined according It is noted that a cancel circuit (not shown) to the output (V) from the r.p.m. detecting 125 is incorporated into the blower control circuit circuit 62 as seen in Fig. 6. 61 to cancel the output from the thermo-cou With the structure thus far described, the ple 52 for a certain period of time such as, electronic control circuit 5 works as follows: for example, 10 seconds so as to obtain a Operation of the knob 54 changes the refer- stable output, and thus avoiding mulfunction ence voltage which corresponds to the de- 130 of the air-fuel control at the time of igniting 3 GB2191022A 3 the fuel gas. 333-to the opening degree of the valve 345 Instead of the hall device 33c as a means upon operation of the knob 345, thus further to detect the revolution of the blower 33, a preventing deviation from the normal air-fuel rotary encoder, a synchro resolver, a fre- ratio.

quency generator or the like may be em- 70 Still further, attention is called to Fig. 10 in ployed. which fourth embodiment of the invention is A pressure sensor may be used to detect shown. An electronic circuit 405 has a heat the wind pressure of the blower 33 at the determining circuit 481 which determines the lower reach thereof instead of detecting the amount of heat generation required at the bur- r.p.m. of the blower 33 when measuring the 75 ner plate 31 by comparing input signal of a amount of air supplied by the blower 33. In temperature sensor 453 with the reference this instance, the amount of energisation of value obtained from the desired temperature the blower 33 may be detected. setting. The circuit 405 further has a valve In the latter case, a delay circuit may be control circuit 482 which controls the amount employed at the input or output terminal of 80 of energisation of a flow- regulating valve 445 the flow-regulating valve control circuit 63 to based on the output from the heat determin change the opening degree of the valve 45 ing circuit 481. A blower 433 is controlled by while the blower 33 is changing its speed a blower control circuit 483 which adjusts the.

from low r.p.m. to high r.p.m., and vice versa. energisation of the blower 433 according to Now, attention is called to Fig. 7 in which a 85 outputs from the heat determining circuit 481 second embodiment of the invention is and the thermo-couple 452.

shown. The blower control circuit 483 further in An electronic control circuit 5 of the second cludes a r.p.m. determining circuit 483a which embodiment includes flow-regulating valve determines the amount of energisation of the control circuit 271 which controls the amount 90 blower 433 according to the output from the of energisation of a flow-regulating valve 245 heat determining circuit 481. The circuit 483 based on outputs from a water temperature has a speed compensation circuit 483b which sensor 253 and operation of a knob 254. The makes up for the output from the r.p.m. de circuit 5 further includes a blower control cirtermining circuit 483a, so that a thermo-cou cuit 272 which controls the amount of energi- 95 pie 452 generates output voltage (mV) as de sation of a blower 233 in accordance with the termined in accordance with output (p) from output of a thermo-couple 252 and the the heat determining circuit 471 as shown in amount of energisation of the flow-regulating Fig. 11.

valve 245. It is noted that for compensating air-fuel ra The blower control circuit 272 has a r.p.m. 100 tio, the flow-regulating valve control circuit determining circuit 272a which determines the 482 may be activated instead of the blower amount of energisation of the blower 233 ac- control circuit 483.

cording-to the output from the flow-regulating In addition, a delay circuit may be employed valve control circuit 271. The circuit 272 fur- to be connected to output or input terminal of ther has a speed compensation circuit 272b 105 the valve control circuit 482, so that the valve which makes up for output voltage of the 445 changes its opening degree while the r.p.m. determining circuit 272a, so that the blower 433 is changing its speed from lower thermo-couple 252 generates an output vol- r.p.m. to higher r.p.m., and vice versa.

tage (mV) as determined according to the out- This invention may be incorporated into air put (a) from the flow-regulating valve control 110 warming apparatus instead of water heating circuit 271 in Fig. 8. apparatus of the above embodiments. It is It is noted that the valve 245 is controlled also appreciated that other kinds of fuel such at its opening degree by detecting the amount as, for example, petroleum may be employed of energisation of the valve 245. Instead of instead of kerosene.

detecting the energisation, rotational displace-

Claims

ment of the valve 245 may be detected. CLAIMS

Further, attention is called to Fig. 9 in which 1. A fluid heating apparatus comprising: a third embodiment of the invention is shown. burner plate; a variable flow- regulating valve, Unlike the second embodiment of the inven- through which fuel gas flows into said burner tion in which operation of the knob 254 al- 120 plate; a blower which supplies air to said bur lows to change the amount of energisation ner plate; a temperature sensor which detects toward both blower 33 and flow-regulating the temperature of said burner plate; a first valve 245 simultaneously, a delay circuit 373 control circuit which is responsive to the tem is connected to the input terminal of a flow- perature of output fluid and to a selected tar regulating valve 345 to delay an input signal 125 get temperature therefor, said circuit control in the third embodiment. With this structure, ling one of said valve and said blower; a sec the valve 345 changes its opening degree, ond control circuit which controls the other of while the blower 333 is changing its rotation the valve and blower and is responsive to the speed. This makes it possible to precisely output of the first control circuit or to the match the change of the speed of the blower 130 condition of said one of the valve and blower; 4 GB2191022A 4 and a compensation control circuit which pro- vides an additional control to the said other of the valve and blower in accordance with the output of the temperature sensor.
2. A fluid heating apparatus according to claim 1, in which said temperature sensor is a thermo-couple provided to detect the temperature of the flame on said burner plate to confirm the fuel-air ratio.
3. A fluid heating apparatus according to claim 1 or 2, in which said first control circuit is a blower control circuit which adjusts the amount of energisation of said blower.
4. A fluid heating apparatus according to claim 3, in which said blower is controlled by detecting the speed thereof.
5. A fluid heating apparatus according to claim 1 or claim 2, in which said first control circuit is a valve control circuit which controls 3 the amount of energisation of said valve.
6. A fluid heating apparatus according to claim 5, in which the amount of fuel is detected by the amount of energisation of said valve by way of said valve control circuit.
7. A fluid heating apparatus according to claim 5 or claim 6 including a delay circuit between the first control circuit and the valve.
8. A fluid heating apparatus according to any one of claims 1 to 4 wherein the first control circuit is a heat determining circuit which controls the valve via a valve control circuit and outputs to the second control circuit which controls the blower.
9. A fluid heating apparatus substantially as hereinbefore described with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd. Dd 8991685. 1987. Published at The Patent Office. 25 Southampton Buildings, London, WC2A l AY, from which copies may be obtained.

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