JP2000018572A - Combustion apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a combustion apparatus including a fluid flow rate detection device and a fluid detection device capable of detecting a correct value without the need of a mechanical operation portion which might cause a bad operation even when the devices are used for a long period of time. SOLUTION: The present apparatus includes a combustion section for combusting fuel gas to heat a fluid passing through a fluid passage, a control section connected with the combustion section for combustion control, and a fluid flow rate detection device 110 for detecting a flow rate of the fluid flowing through said fluid passage and send a detected value to the control apparatus. Herein, the fluid flow rate detection device 110 is constructed with non-movable sections 111, 112.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus provided in a fluid passage for guiding a fluid such as a pipe disposed in a device such as a water heater, and having a detecting device for accurately detecting the flow rate and the fluid of the fluid. It concerns the device.

[0002]

2. Description of the Related Art As a device having a fluid passage therein, there is, for example, a combustion device having a pipeline inside a water heater or the like. Such a combustion device is provided with a hot water supply system for heating hot water and supplying hot water, or a reheating system for circulating and heating hot water in a bath tub, and a heat receiving tube communicating with this hot line is heated by a burner. Through a heat exchanger to be heated.

[0003] Such a pipe of a hot water supply system or a circulation system is provided with a fluid flow rate detecting device for detecting the flow rate of hot water passing through the pipeline and a fluid detecting device for confirming the presence or absence of hot water. Based on these detection signals, the combustion control of the combustion section such as the burner is performed.

As such a fluid flow detecting device, specifically, for example, a flow sensor as a flow sensor as shown in FIG. 10 is used. This flow sensor 1
When water is supplied into the cylindrical body 2, the turbine 3 disposed in the body 2 is rotated. The turbine 3 is provided with a ring-shaped magnet 4 in which N poles and S poles are alternately magnetized along a rotating circumferential direction. The phase change of the magnetic field by the magnet 4 corresponding to the rotation of the turbine 3 is provided. To Hall IC5
To detect and extract it as a signal. Therefore, based on the signal of the Hall IC 5,
The presence or absence of hot water and the flow rate of hot water in the pipeline can be detected.

On the other hand, as a fluid flow rate detecting device, specifically, for example, a flowing water switch as shown in FIG. 11 is used. The flowing water switch 6 includes a body 7, and a space S1 is formed in the body 7, and an inlet pipe 7a and an outlet pipe 7b communicate with the space S1. Further, a swing plate 8 is provided in the space S1, and when water feeds into the space S1, the swing plate 8 swings by receiving the water pressure. The swing plate 8 is provided with a magnet 8a. On the other hand, a reed switch 9 is arranged on the body 7 side. As a result, in FIG. 9, when the water supply enters the space S from the inlet side pipeline 7a and swings the swing plate 8 in the direction of the arrow, the magnet 8 of the swing plate 8
The magnetic field a acts on the reed switch 9 to turn on its contact. As a result, it is detected that flowing water exists in the pipeline.

[0006]

However, in the flow sensor 1 and the flowing water switch 6 as described above, like the turbine 3 and the swing plate 8, the flowing water is in direct contact with the flowing water so as to respond to the flowing water. It has a part that operates mechanically. Having such a movable part, if the resistance of the movable part due to aging increases, for example, if garbage in running water or, for example, hair flowing through a reheating line becomes entangled, malfunction will occur and correct There was a problem that detection became impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and does not require a mechanically operating portion which causes a malfunction, and can detect a correct flow rate even when used for a long time. An object is to provide a combustion device including a detection device and a fluid detection device.

[0008]

According to the present invention, there is provided a combustion section for burning a fuel gas to heat a fluid passed through a fluid passage, and a combustion section connected to the combustion section for controlling combustion. A combustion device comprising: a control device for performing the operation; and a fluid flow detection device that detects a flow rate of the fluid flowing through the fluid passage and sends the detected value to the control device, wherein the fluid flow detection device is non-movable. This is achieved by a combustion device characterized by being constituted by a part.

According to the present invention, the non-movable portion is disposed in the fluid passage, and measures the flow rate and temperature of the fluid by contacting the fluid flowing through the fluid passage. Then, correct flow rate detection can be performed by correcting the flow rate measurement value with the temperature measurement value. Further, the non-movable portion may be disposed in the fluid passage, and the flow rate of the fluid flowing through the fluid passage may be measured by a Venturi differential pressure method or an orifice differential pressure method.

[0010] In the present invention, a combustion unit for burning a fuel gas to heat a fluid passed through a fluid passage, a control device connected to the combustion unit and controlling combustion are provided. Detecting the fluid flowing through the fluid passage,
This is achieved by a combustion device comprising: a fluid detection device that sends the detection value to the control device, wherein the fluid detection device is configured by a non-movable part.

In the present invention, the non-movable portion is arranged in the fluid passage, and detects the fluid by contacting the fluid flowing through the fluid passage. Further, the non-movable portion may be arranged in the fluid passage, and the fluid flowing through the fluid passage may be detected by a Venturi differential pressure system or an orifice differential pressure system. Since no movable portion is provided in this way, no malfunction occurs, and a correct value can be detected even when the device is used for a long time.

[0012]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. The embodiments described below are preferred examples of the present invention, and therefore, various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. The embodiment is not limited to these embodiments unless otherwise stated.

FIG. 1 shows an example of the configuration of a combustion apparatus provided with a fluid flow detecting device according to an embodiment of the present invention. FIG.
In this combustion apparatus 10, one or a plurality of burners and one heat exchanger are accommodated in one can (the inner body of the heat exchanger), and the heat exchanger is provided with a water supply system and a reheating system. It is an example of a one-can-two-water-channel combustion device passing through a water channel. First, the configuration of the combustion device 10 will be described.

The combustion device 10 has one heat exchanger 13 in a can 11. A combustion section 12 is provided below the heat exchanger 13, and the combustion section 12 is provided with one burner 15. The burner 15 is connected to a supply pipe 15a for a fuel gas drawn from the outside.
A main solenoid on-off valve 22 and a proportional solenoid valve 21 are connected to the gas supply pipe 15a. Thereby, the main solenoid on-off valve 2
2, the fuel gas is drawn in from the outside, and the supply amount of the fuel gas is adjusted by the electromagnetic proportional valve 21.

An electric fan 17 for sending combustion air is disposed below the burner 15. An igniter (not shown) serving as ignition means, a frame rod 16 for checking combustion, and the like are provided near the flame opening of the burner 15. The end of the frame rod 16 is arranged in a combustion flame,
During combustion, the flame current is detected.

Above the burner 15, one heat exchanger 1
3 and an exhaust passage 48 above the heat exchanger 13.
Is provided. As a result, the heat exchanger 13 is heated by the combustion of the burner 15, and the exhaust gas is led to the outside via the exhaust passage 48. Heat exchanger 13
Are provided with a large number of fins 14, and a heat receiving pipe 30 a for a hot water supply system and a heat receiving pipe 50 a for a reheating system (bath system) 50 are arranged so as to penetrate the fins 14. Thereby, each of the heat receiving tubes 30a and 50a is heated by one heat exchanger 13 at the same time. Further, a temperature fuse 47 is disposed near the heat exchanger 13,
When the temperature of the heat exchanger 13 rises to an abnormally high temperature, the fuse 47 is blown. As a result, the power supply to the wiring connected to the thermal fuse 47 is cut off and detected by the control device 18 described later.

A circulation pipe 51 for additional heating provided between the heat receiving pipe 50a of the additional heating system 50 and the circulation fitting 58 of the bathtub 57 is connected. At one end (entrance side) of the heat receiving tube 50a, a return pipe 52 of a pipe 51 is provided.
The other end (outside) of Oa is connected to an outgoing pipe 53 of a reheating pipe line 51 so as to constitute a circulation pipe as a whole.

A return pipe 52 for drawing water from the bathtub 57 has a bath fluid flow detecting device 1 for detecting the amount of water.
00 and a bath thermistor 5 for detecting the temperature of the bath water
5 and a circulation pump 54 for drawing water from the bathtub 57 are provided. A pressure sensor (not shown) is provided at a predetermined location of the additional heating pipe 51 or the branch pipe 42 so that the water level of the bathtub 57 can be detected. The structure of the fluid flow detecting device 110 will be described later in detail.

On the other hand, in the hot water supply system 30, a water supply pipe 31 for drawing in water from the outside is connected to one end (entrance side) of the heat receiving pipe 30a, and heated water is supplied to the other end (outside). A hot water supply pipe 32 for tapping the hot water is connected. Water supply pipe 31
A flow sensor 35 for detecting the presence and amount of water flow guided from the outside, a water amount control valve 36 composed of, for example, a gear motor described later, and a water input thermistor 37 for detecting the temperature of the introduced water. It is connected. In the vicinity of the heat exchanger 13 in the middle of the heat receiving pipe 30a of the hot water supply system,
A thermistor 44 as temperature detecting means is attached.

A thermistor 39 is connected to a hot water supply pipe 32 connected to a place outside the heat exchanger 13 from the heat receiving pipe 30a.
Is connected. By branching a portion of the water supply pipe 31 downstream of the flow sensor 35 and upstream of the water amount control valve 36, and connecting a point of the hot water supply pipe 32 downstream of the thermistor 39,
A bypass means 34 is provided. The bypass means 34 is provided with a bypass valve 38 for varying the bypass flow rate. The bypass valve 38 is controlled by, for example, a gear motor as described later. A fixed bypass 33 is provided which branches the water supply pipe 31 downstream of the water input thermistor 37 and connects the hot water supply pipe 32 with a portion upstream of the second thermistor 39, and whose flow rate does not change.

A thermistor 41 is provided downstream of the connection point of the hot water supply pipe 32 with the bypass means 34. Further, the hot water supply pipe 32 branches downstream from the thermistor 39 and is connected to one end of a branch pipe (pouring pipe) 42. The other end of the branch pipe 42 is connected to the pump 54 of the additional heating line 51 described above. It is connected downstream. A pouring solenoid valve 43 is set in the branch pipe 42.

The combustion device 10 is provided with a control device 18 shown in FIGS. The control device 18 is configured as, for example, a control board of the combustion device 10. The control device 18 is connected to a recoat control device (hereinafter referred to as a “remote control”) 19, and the hot water supply system 3 is controlled via the remote control so as to reach a temperature set by a user.
That is, so-called automatic operation is performed in which the bathtub 57 is filled with water so as to control the temperature to 0 or the set water level, and the reheating system 50 is controlled so that the water can be reheated to the set temperature. .

The combustion unit 12 is connected to the control device 18 shown in FIG. The combustion unit 12 includes an ignition means for the burner 15 described above, a proportional valve 21 for supplying fuel gas to the burner 15, an on-off valve 22, and the like, and further includes a means for controlling combustion such as a pressure sensor (not shown). In.

The control unit 18 includes an electric fan 17 for sending air for combustion to the combustion unit 12, a bypass valve 38 for adjusting a flow rate of a bypass unit, a water amount control valve 36 for adjusting an amount of water supplied to a water supply pipe, and a branch pipe 42. A pouring solenoid valve 42 that opens and closes the pump, and a flow rate detection device 110 described below are also connected.

The combustion device 10 is operated, for example, as follows. First, the hot water supply operation will be briefly described. When the user turns on the remote control 19 and opens the hot water tap (not shown) of the hot water supply pipe 32, water is supplied from outside to the water supply pipe 31, and the flow sensor 35 detects this, and the control device 18
Send a signal to The control device 18 issues an instruction to the combustion unit 12, instructs the main solenoid on-off valve 22 and the proportional solenoid valve 21, respectively, introduces fuel into the burner 15, and starts combustion using ignition means such as an igniter (not shown). . The flame rod 16 detects a flame current in the combustion flame, and confirms ignition and monitors the state of continued combustion.

The fins 14 of the heat exchanger 13 are heated by the combustion of the burner 15, and the heat is exchanged with the water flowing from the water supply pipe 31 to the heat receiving pipe 30 a, and is discharged through the hot water supply pipe 32. Further, the incoming water thermistor 37 detects the temperature of incoming water introduced from outside, and the thermistor 44 detects the temperature of the heat exchanger 1.
In 3, the temperature of the stagnant water in the heat receiving tube 30 a is detected.
The thermistor 39 detects the temperature of the hot water in the hot water supply pipe on the outlet side of the heat exchanger 13, and the thermistor 41 monitors the actual hot water temperature after mixing by the bypass unit 34.

Therefore, the controller 18 detects the total amount of water taken in by the water amount control valve 36 while observing the detection result of the flow sensor 35. The control device 18 monitors the incoming water temperature by the incoming water thermistor 37, obtains the number of combustion and fuel supply amount required for heating to the temperature set by the remote controller 19 by a predetermined calculation, and controls the combustion. . Then, the control device 18 uses the thermistor 39 to
The temperature of hot water coming out of the heat exchanger 13 is detected, the bypass valve 38 is adjusted to determine a bypass flow rate, the heated hot water and the flow rate of water passing through the bypass means 34 are determined, and the thermistor 41 determines the flow rate. The opening degree of the water amount control valve 36 and the bypass valve 38 is controlled so that the detected hot water temperature matches the set temperature, and mixing is performed so as to obtain an appropriate flow rate ratio.

In the case of additional heating, the remote controller 19 is used.
When the user gives an instruction for additional heating via, the control device 18 drives the additional heating pump 54 to draw water from the bathtub 57 into the additional heating conduit 51. The control device 18 confirms the signal of the water flow detection of the fluid flow detection device 110, performs the above-described ignition operation, draws the bathtub water into the additional heating pipe line 51, and circulates the pump. Is heated by the heat exchanger 13. At this time, the control device 18
The combustion unit 12 stops the combustion of the burner 15 when the temperature detected by the thermistor 37 reaches, for example, 75 ° C., and resumes the combustion when the temperature falls below 70 ° C. The reason for performing such intermittent combustion is to perform reheating in a short time while preventing the hot water staying in the heat receiving tube 50a in the heat exchanger 13 from boiling. When the temperature detected by the bath thermistor 55 reaches the set temperature instructed via the remote controller 19, the reheating is completed.

The automatic operation in a state where the bathtub 57 is not filled with water is performed by opening the pouring solenoid valve 43 of the branch pipe 42 and burning the burner 15 from the hot water supply pipe 32 to the reheating line 51.
After warm water is introduced into the bath, the hot water is introduced into the bathtub 57 from the circulation fitting 58 and filled with hot water, and then the above-mentioned reheating operation is performed to boil the hot water. In addition, the hot water supply operation and the reheating operation can be performed simultaneously.

FIGS. 3 and 4 show a case where the fluid flow detecting device 110 is constituted as a single unit. The fluid flow detecting device 110 is disposed along a conduit of, for example, a return pipe 52 as a fluid passage, and the exposed portion 1 exposed on an inner surface of the conduit 52.
It has a flow sensor 111 and a temperature correction sensor 112 each having 11a and 112a.

As the flow sensor 111, a thermal flow sensor is used. Exposure part 111a of this thermal type flow sensor
Are heat conducting portions formed of, for example, copper or the like. On the outside of the heat conducting portion, there are provided a heating resistor which is a heating portion (not shown) provided so as to be in thermal contact with the heat conducting portion, and a temperature thermistor provided adjacent to the heating resistor. I have. This temperature thermistor is made of, for example, a temperature-sensitive semiconductor whose resistance value largely changes in response to a temperature change. The heating resistor and the temperature thermistor are arranged on one chip.

Then, by applying a predetermined voltage to the heat generating portion via an external circuit, the heat generating portion is caused to generate heat, and the heat is transmitted to the heat conducting portion. Thus, when a fluid such as water passes through the pipeline 52, the exposed portion 111a is touched and cooled, and the temperature thermistor detects that the heat of the heat generating portion or the heat conducting portion has dropped. The temperature detected by the temperature thermistor corresponds to the flow rate of the fluid, whereby the current flow rate of the fluid flowing in the pipe 52 is detected. However, since the detection value of the temperature thermistor also changes depending on the temperature of the fluid flowing through the pipeline 52, the temperature correction sensor 112 is provided.

The temperature compensating sensor 112 uses, for example, a temperature thermistor whose resistance value changes in response to a temperature change. The temperature correction sensor 112 changes its resistance value in accordance with the temperature of the fluid touching the exposed portion 112a. Has become. Thus, by using the output signal of the temperature correction sensor 112, the temperature output and the temperature error of the flow rate sensor 56 based on the water temperature are corrected as follows.

For example, FIG. 5 shows an example of a bridge circuit including a flow sensor 111 and a temperature correction sensor 112. The flow sensor 111 and the comparison resistor R1 are connected in series between the power supply side and the ground side, and further, the temperature correction sensor 112 and the comparison resistor R2 are connected in series between the same power supply side and the ground side. . A contact between the flow sensor 111 and the comparison resistor R1 and a contact between the temperature correction sensor 112 and the comparison resistor R2 are respectively connected to an inverting input terminal and a non-inverting input terminal of the differential amplifier 113, respectively. I have. As a result, the differential amplifier 113
By taking the differential output value of the voltage on the 1 side and the temperature correction sensor 112 side from the output terminal thereof (for example, V1−V2), the water X passing through the fluid passage 52 can be accurately determined according to the temperature of the water X. The flow rate can be detected.

That is, when the flow rate of the fluid in the fluid passage 52 is constant, for example, when the temperature of the water changes, the voltages at both ends of the flow rate sensor 111 and the temperature correction sensor 113 both rise and fall by the same amount. . That is, when the temperature of the water rises, the flow rate sensor 111 and the temperature correction sensor 11
The voltage at both ends of 2 decreases by the same amount, and when the water temperature decreases, the voltage at both ends increases by the same amount. Therefore, even if the temperature of the water changes, the value of the differential output value (V1-V2) is constant,
When the flow rate changes, the change in the flow rate can be detected by changing the differential output value (V1-V2).

FIG. 6 is a block diagram showing a circuit for processing a detection value obtained by the fluid flow detecting device 110 and the bath thermistor 55. The fluid flow detecting device 110 and the bath thermistor 55 are connected to the CPU 116 via A / D converters 114 and 115, respectively, and the detected values are A / D converted by the A / D converters 114 and 115, respectively. Later, the CPU 11
6 and is processed by software.

FIG. 7 is a block diagram showing a processing circuit obtained by simplifying the processing circuit shown in FIG. In this processing circuit, the temperature correction sensor 112 of the fluid flow rate detection device 110
Are omitted, and a bath thermistor 55 is used instead. According to such a configuration, performance equivalent to that of the processing circuit of FIG. 6 can be exhibited, and the circuit can be simplified by the temperature correction sensor 112 and the correction circuit, so that a significant cost reduction can be achieved. Can be.

As the fluid flow rate detecting device constituted by the non-movable part, an orifice shown in FIG. 8, for example, is used in addition to the fluid flow rate detecting device 110 constituted by the flow rate sensor 111 and the temperature correction sensor 112 and the like. The fluid flow detecting device 120 described above or the fluid flow detecting device 130 using a venturi shown in FIG. 9 may be used. The fluid flow detecting device 120 using an orifice shown in FIG. 8 is of a type in which a throttle (orifice) 121 is placed in a pipeline 52 to generate a differential pressure before and after it. Since this differential pressure is proportional to the square of the flow rate passing through the orifice 121, the differential pressure is measured to detect the flow rate. Specifically, a flow rate is detected by providing a differential pressure gauge where a pressure difference (P ₃ −P ₂ ) at the orifice can be obtained. To detect this pressure difference, chamber A,
A semiconductor pressure sensor or the like in which the chamber B is filled with a gel substance or silicon oil or the like is used.

A fluid flow detecting device 130 using a venturi shown in FIG. 9 is a venturi tube 131 which is gently expanded after a pipe is rapidly narrowed in the middle of a pipe 52.
In this method, a differential pressure is generated before and after that, and the differential pressure is measured to detect the flow rate. Specifically, similarly to the orifice, the pressure difference of the venturi (P ₃ -P
₂ ) Install a differential pressure gauge where the flow can be measured to detect the flow rate.
For detecting the pressure difference, a semiconductor pressure sensor or the like in which the chamber A and the chamber B are filled with a gel-like substance or silicone oil is used. The Venturi tube 131 has a more complicated structure than the restrictor (orifice) 121, but has excellent characteristics that mud and sediment hardly accumulate, small pressure loss, and durability.

In the combustion device 10 as described above, the fluid flow rate detection device 110 has no mechanically operated portion.
Unlike the related art, there is no concern that dust or the like may be caught and malfunction, and the presence of the fluid in the pipeline 52 can always be detected accurately, and an accurate detection result can be obtained for the flow rate. Here, the fluid flow rate detection devices 110 and 12 of the above-described embodiment are used.
Since 0 and 130 can also be applied to a device for detecting a fluid, they can be used instead of, for example, the flow sensor 35 of the combustion device 10 shown in FIG.

The flow rate sensor and the temperature correction sensor of the fluid flow rate detecting device according to the present invention are not limited to one set, but a plurality of sets may be provided, attached, and controlled by a single control device. The tube forming the fluid passage is not limited to a cylindrical tube, but may have another cross-sectional shape.

As a device to which the fluid flow rate detection device of the present invention is applied, a so-called one-can-two-channel combustion device is taken as an example. However, the present invention is not limited to this, and other types of devices or fields having completely different areas are used. Any device can be applied as long as it has a passage through which fluid flows.
The fluid is not limited to water, but may be another type of fluid.

[0043]

As described above, according to the present invention, it is possible to detect an accurate fluid flow rate and fluid even when used for a long period of time without requiring a mechanically operating part which causes malfunction. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a combustion device as an example of a device including a fluid flow detection device according to the present invention.

FIG. 2 is a diagram showing a periphery of a control device of the combustion device of FIG. 1;

FIG. 3 is a perspective view showing a preferred embodiment of a fluid flow detecting device of the present invention.

FIG. 4 is a partially cutaway sectional view showing the inside of the fluid flow detection device of FIG. 3;

5 is a diagram showing a bridge circuit having a flow rate sensor and a temperature correction sensor of the fluid flow rate detection device of FIG. 3;

6 is a block diagram showing a circuit for processing a detection value obtained by the fluid flow detection device and the bath thermistor of FIG. 3;

FIG. 7 is a block diagram showing another processing circuit of a detection value obtained by the fluid flow detection device and the bath thermistor of FIG. 3;

FIG. 8 is a sectional view showing another preferred embodiment of the fluid flow detecting device of the present invention.

FIG. 9 is a sectional view showing still another preferred embodiment of the fluid flow detecting device of the present invention.

FIG. 10 is a diagram showing an example of a conventional fluid flow detection device.

FIG. 11 is a diagram illustrating an example of a conventional fluid detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Combustion apparatus 12 Combustion part 15 Burner 18 Control device 19 Remote control 30 Hot water supply system 42 Branch pipe 50 Additional heating system 52 Additional heating pipe 55 Bath thermistor 57 Bathtub 110 Fluid flow rate detecting device 120 Fluid flow rate detecting device 130 Fluid flow rate detecting device 111 Flow rate sensor 112 Temperature correction sensor 113 Differential amplifier 114 A / D 115 A / D 116 CPU 121 Orifice 131 Venturi tube

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masanori Enomoto 3-4 Fukamidai, Yamato-shi, Kanagawa F-Term in Gaster Co., Ltd. (Reference) 2F030 CA10 CC04 CD15 CE02 CE04 CF05 CF08 CF20 3K005 MA06 MB01 MB06

Claims (8)

[Claims] 1. A combustion unit for burning a fuel gas to heat a fluid passed through a fluid passage, a control device connected to the combustion unit for performing combustion control, and a flow rate of the fluid flowing through the fluid passage. A combustion device comprising: a fluid flow detection device that detects and sends a detection value to the control device, wherein the fluid flow detection device includes a non-movable part. 2. The non-movable part is disposed in the fluid passage, and measures the flow rate and temperature of the fluid by contacting the fluid flowing through the fluid passage, and corrects the measured flow rate with the measured temperature. The combustion device according to claim 1. 3. The combustion apparatus according to claim 1, wherein the non-movable portion is disposed in the fluid passage, and measures a flow rate of the fluid flowing through the fluid passage by a Venturi differential pressure method. 4. The combustion apparatus according to claim 1, wherein the non-movable portion is disposed in the fluid passage, and measures a flow rate of the fluid flowing through the fluid passage by an orifice differential pressure method. 5. A combustion section for burning a fuel gas to heat a fluid passed through a fluid passage, a control device connected to the combustion section for controlling combustion, and detecting the fluid flowing through the fluid passage. And a fluid detection device for sending the detected value to the control device, wherein the fluid detection device is constituted by a non-movable part. 6. The combustion apparatus according to claim 5, wherein the non-movable portion is disposed in the fluid passage, and detects the fluid by contacting the fluid flowing through the fluid passage. 7. The combustion apparatus according to claim 5, wherein the non-movable portion is disposed in the fluid passage, and detects the fluid flowing through the fluid passage by a Venturi differential pressure method. 8. The combustion device according to claim 5, wherein the non-movable portion is disposed in the fluid passage, and detects the fluid flowing through the fluid passage by an orifice differential pressure method.