JP2001165735A - Thermal flow meter having fluid temperature compensating function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flowmeter capable of certainly compensating the temperature of a fluid even if the temperature of the inflow fluid changes suddenly to accurately detect the flow rate of the fluid. SOLUTION: In a metal casing member 2 in which the fluid flow channel extending from a fluid inflow opening 14 to a fluid outflow opening 16 is formed, a fluid stagnation region 6 having a flow cross-sectional area five times that of a flow channel part 8 is formed on the upstream side of the flow channel part 8, in which the fin plate 44 of a flow rate detection unit and the fin plate 44' of a fluid temperature detection unit are arranged so as to perform the giving and receiving of heat with a fluid, in relation to the flowing of the fluid. The flow velocity of the fluid in the fluid stagnation region 6 becomes 1/5 or less that in the flow channel part 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid flow sensing technology, and more particularly to a thermal flow meter having a fluid temperature compensating function.

[0002]

2. Description of the Related Art
Various types of flow meters [flow rate sensors] (or flow rate sensors [flow rate sensors]) for measuring the flow rate (or flow rate) of various fluids, especially liquids, are used, but it is easy to reduce the cost. For this reason, a so-called thermal (particularly indirectly heated) flow meter is used.

[0003] In this indirectly heated flow meter, a sensor chip formed by laminating a thin-film heating element and a thin-film temperature sensing element on a substrate by using a thin-film technology via an insulating layer is interposed between the sensor chip and a fluid in a pipe. What is arrange | positioned so that heat transfer is possible is used.
By energizing the heating element, the temperature sensing element is heated to change the electrical characteristics of the temperature sensing element, for example, the value of electrical resistance. This change in the electric resistance value (based on the temperature rise of the temperature sensing element) changes according to the flow rate (flow velocity) of the fluid flowing in the pipe. This is because a part of the calorific value of the heating element is transmitted into the fluid, and the amount of heat diffused into the fluid changes according to the flow rate (flow velocity) of the fluid. This is because the amount of heat supplied changes and the electrical resistance value of the thermosensitive body changes. The change in the electric resistance value of the temperature sensing element also differs depending on the temperature of the fluid. Therefore, a temperature sensing element for temperature compensation is incorporated in an electric circuit for measuring the change in the electric resistance value of the temperature sensing element. It has also been practiced to minimize the change in the flow measurement value due to the temperature of the fluid.

[0004] Such an indirectly heated flow meter using a thin film element is described in, for example, JP-A-11-118566. In this flow meter, an electric circuit (detection circuit) including a bridge circuit is used to obtain an electric output corresponding to the flow rate of the fluid.

[0005] In the flow rate detection by the thermal type flow meter as described above, the following problem occurs with a change in the temperature of the fluid whose flow rate is detected.

For example, when kerosene is circulated from a kerosene tank placed outdoors to a kerosene-burning device installed indoors by piping, and a flowmeter is installed in the indoor part of the piping, the outdoor air temperature becomes lower than the indoor temperature. When the temperature is significantly different from the temperature (for example, it may differ by about 20 ° C. in winter), kerosene remaining in the pipe indoors first passes through the flow meter when the use of kerosene-burning equipment is started. After the circulation, the kerosene existing in the outdoor portion of the pipe at the start of use reaches the flow meter, and the flow rate is detected.

However, a unit for detecting a fluid temperature, which incorporates a temperature compensation element for temperature compensation incorporated in a fluid flow detecting circuit, is often arranged at a position different from a unit for detecting a fluid flow. Also, even if they are arranged close to each other, the heat exchange for the fluid flow measurement in the fluid flow sensing unit and the heat exchange for the fluid temperature measurement in the fluid temperature sensing unit are actually performed. It is separated from the part, in which case, as described above, when a fluid of a different temperature suddenly flows into the flow meter,
A state in which the fluid temperature at the time of heat exchange with the fluid temperature detection unit temporarily differs from the fluid temperature at the time of heat exchange with the fluid flow detection unit appears, and accurate temperature compensation is no longer performed. Decrease.

Accordingly, an object of the present invention is to provide a flow meter capable of accurately performing fluid temperature compensation and performing accurate flow rate detection even if the temperature of the flowing fluid changes abruptly. Things.

[0009]

According to the present invention, a casing member having a fluid flow passage extending from a fluid inflow opening to a fluid outflow opening is provided. A flow rate detection unit that is attached and that changes an electrical characteristic value in response to the flow of the fluid in the fluid flow passage by transfer of heat with the fluid in the fluid flow passage; and A fluid temperature detecting unit that changes an electrical characteristic value in accordance with the temperature of the fluid by transferring heat with the fluid in the fluid flow passage, and detects a flow rate of the fluid by the fluid temperature. A thermal flow meter configured to perform based on an electrical characteristic value of a detection unit, wherein a position at which heat is exchanged between the flow detection unit and the fluid and a temperature of the fluid. Upstream with respect to the flow of the fluid from the position at which heat transfer between the sensing unit and the fluid is performed, the fluid flow passage has a position at which heat transfer between the flow rate detection unit and the fluid is performed or the fluid temperature. A fluid temperature compensation function, wherein a fluid retention area having a flow cross-sectional area of 5 times or more, preferably 10 times or more, of a flow cross-sectional area at a position where heat is exchanged between the detection unit and the fluid is formed. A thermal flow meter having the following formula:

According to the present invention, a casing member having a fluid flow passage extending from a fluid inflow opening to a fluid outflow opening is provided.
A flow rate detecting unit attached to the casing member, the electrical characteristic value of which changes in response to the flow of the fluid in the fluid flow passage by transfer of heat with the fluid in the fluid flow passage; and A fluid temperature detection unit attached to the casing member and having an electrical characteristic value that changes in accordance with the temperature of the fluid by transfer of heat with the fluid in the fluid flow passage; and A thermal flowmeter for detecting a flow rate compensated for a fluid temperature by a detection circuit including a fluid temperature detection unit, wherein a position at which heat is exchanged between the flow rate detection unit and the fluid and the fluid temperature detection unit In the fluid flow passage, upstream of the position where heat is exchanged between the fluid and the fluid, the fluid flow speed in the fluid flow passage is greater than the flow rate detection unit and the flow rate. Fluid retention region where the flow rate of fluid at the position where heat is transferred between the fluid and the position where heat is transferred between the fluid temperature detection unit and the fluid is 1/5 or less, preferably 1/10 or less. Is formed, and a thermal flow meter having a fluid temperature compensation function is provided.

In one embodiment of the present invention as described above,
The volume of the fluid retention area is per unit length in the fluid flow direction at a position where heat is exchanged between the flow rate detection unit and the fluid or at a position where heat is exchanged between the fluid temperature detection unit and the fluid. Is at least 50 times the volume of

In one aspect of the present invention, the fluid flow passage is connected to the first portion of the flow passage connected to the fluid inflow opening and the fluid outflow opening to exchange heat between the flow detection unit and the fluid. A fluid temperature detection unit and a flow passage second portion through which heat is exchanged with the fluid,
The fluid retention region is located between the first portion of the flow passage and the second portion of the flow passage, and the flow cross section of the first portion of the flow passage is smaller than the flow cross section of the fluid retention region.

In one embodiment of the present invention, the second portion of the flow passage is provided at a position where heat is exchanged between the flow rate detection unit and the fluid and heat exchange between the fluid temperature detection unit and the fluid is performed. A portion extending in parallel with the fluid retention region at a position where the fluid is retained.

In one embodiment of the present invention, a filter is interposed in a communicating portion between the fluid retaining region and the second portion of the flow passage. In one aspect of the present invention, the casing member is made of metal. In one embodiment of the present invention,
The flow rate detection unit is configured such that a heating element, a flow rate detection temperature sensing element, and a flow rate detection heat transfer member that can be extended into the fluid flow passage are arranged so as to be able to transfer heat to each other. The detection unit is configured such that a fluid temperature detection temperature sensing element and a fluid temperature detection heat transfer member that can be extended into the fluid flow passage are arranged so as to be able to transfer heat to each other.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a flow meter according to the present invention, and FIG. 2 is a partial sectional view thereof. 3 shows a front view, FIG. 4 shows a right side view, FIG. 5 shows a bottom view with some members removed, FIG. 6 shows a left side view, and FIG. 7 shows a plan view. FIG. 1 shows a cross section taken along the line AA ′ of FIG.
FIG. 2 shows a partial cross section taken along the line BB 'of FIG.

In these figures, a casing member 2 made of a material having good heat conductivity such as aluminum is formed with three portions 4, 6, 8 constituting a fluid flow passage. The flow passage portion 4 is continuous with the fluid inflow opening 14,
The flow passage portion 8 is connected to the fluid outflow opening 16, and the fluid flowing into the flow passage portion 4 from the fluid inflow opening 14 flows through the flow passage portion 6 to the flow passage portion 8, and flows out of the fluid outflow opening 16.
(Flow direction is indicated by an arrow). The flow passage portion 6 constitutes a fluid retaining area. Note that a lid member 3 is detachably attached to a lower portion of the casing member 2, and the lid member 3 forms a part of the casing member 2.

The flow passage portion 4 extends horizontally, the flow passage portion 6 extends vertically, and the flow passage portion 8 has a vertical portion 8a extending vertically and a horizontal portion extending horizontally. 8b. The fluid inflow opening 14 is connected to a fluid supply side pipe, and the fluid outflow opening 16 is connected to a fluid demand side pipe.

A male screw 10 is detachably attached to the casing member 2 by screwing so as to close an opening connected to an upper part of the flow passage portion 6. A filter 12 in which a non-woven fabric made of glass fiber, plastic fiber, or the like is held by an appropriate holder may be interposed between the communication portion between the flow passage portion 6 and the flow passage portion 8.

The flow rate detecting unit 24 and the fluid temperature detecting unit 26 are attached to the casing member 2 so as to face the vertical portion 8a of the flow passage portion 8. FIG. 8 is a sectional view of the flow rate detection unit 24. In the flow rate detection unit 24, the flow rate detection section 42 is joined to the surface of the fin plate 44 as a heat transfer member by a bonding material 46 having good heat conductivity, and the electrode pad of the flow rate detection section 42 and the electrode terminal 4
8 are connected by a bonding wire 50,
The flow rate detector 42, the bonding wire 50, a part of the fin plate 44, and a part of the electrode terminal 48 are accommodated in a synthetic resin housing 52. Flow detector 4
2 has a thickness of, for example, 0.1 mm made of silicon or alumina.
The thin-film thermosensitive element and the thin-film heating element are formed on a rectangular substrate of about 4 mm and about 2 mm square, insulated from each other.

The fluid temperature detecting unit 26 is equivalent to a device using a fluid temperature detecting unit instead of the flow detecting unit 42 in the flow detecting unit 24. In the fluid temperature detecting unit 26, members corresponding to those of the flow rate detecting unit 24 are denoted by the same reference numerals with “′” added thereto. The fluid temperature detecting section has the same configuration as that in which the thin film heating element is removed from the flow rate detecting section 42.

The ends of the fin plates 44, 44 'protruding from the housings 52, 52' of the flow rate detecting unit 24 and the fluid temperature detecting unit 26 extend into the vertical portion 8a of the flow passage portion 8 of the casing member 2. I have. The fin plates 44, 44 ′ extend through the center in the cross section in the flow passage section 8 having a substantially circular cross section. Since the fin plates 44, 44 'are arranged along the flow direction of the fluid in the flow passage portion 8, the fin plates 44, 44' do not greatly affect the flow of the fluid, and the flow rate detecting section 4 is not affected.
2 and the fluid can be satisfactorily transmitted between the fluid temperature detecting section 42 'and the fluid.

FIG. 5 is a bottom view with the cover member 3 removed, showing the flow passage portion 6 and the vertical portion 8a of the flow passage portion 8. As shown in FIGS. 5 and 1, in the present embodiment, the cross-sectional area of the flow passage portion (fluid retention region) 6 is formed sufficiently larger than the cross-sectional area of the flow passage portion 8. The cross-sectional area of the flow passage portion 6 is at least 5 times, preferably at least 10 times the cross-sectional area of the flow passage portion 8. The volume of the flow passage portion 6 is larger than the volume per unit length of the vertical portion 8a of the flow passage portion 8 where the flow rate detection unit 24 and the fluid temperature detection unit 26 are located, preferably 50 times or more, and more preferably 100 times. That is all.

As described above, the flow passage portion 6 is located upstream of the vertical portion 8a of the flow passage portion 8 where heat exchange for flow rate detection is performed in the fluid flow direction. And a region for temporarily storing fluid flowing therethrough. The speed of fluid flow in the flow passage portion 6 is lower than the speed of fluid flow in the vertical portion 8a of the flow passage portion 8, preferably 1/5 or less, more preferably 1/10 or less.

The vertical portion 8a of the flow passage portion 8 extends parallel to and close to the flow passage portion 6, and is particularly arranged so as to be easily affected by the fluid in the flow passage portion 6. .

The cross-sectional area of the flow passage portion 4 is smaller than the cross-sectional area of the flow passage portion 6 and is substantially the same as the cross-sectional area of the flow passage portion 8. Therefore, the flow rate of the fluid in the flow passage portion 4 is substantially equal to the flow speed of the fluid in the flow passage portion 8.

FIG. 9 is a schematic diagram showing a flow rate detection system of the thermal type flow meter of this embodiment. A DC voltage is supplied from the constant voltage circuit 102 to a bridge circuit (detection circuit) 104. The bridge circuit 104 includes a thin film temperature sensing element 104-1 for flow rate detection of the flow rate detection unit 24, a thin film temperature sensing element 104-2 for temperature compensation of the fluid temperature detection unit 26, and a variable resistor 104-.
3, 104-4. The potentials Va and Vb at points a and b of the bridge circuit 104 are input to the differential amplifier 106, and the output of the differential amplifier 106 is
Is input to

On the other hand, a DC voltage from the power supply is supplied to the thin-film heating element 112 via a transistor 110 for controlling a current supplied to the thin-film heating element 112 of the flow rate detection unit 4. That is, in the flow rate detection unit 42, based on the heat generated by the thin film heating element 112, the heat is absorbed by the fluid to be detected via the fin plate 44,
Temperature sensing by the thin-film sensing element 104-1 is performed. Then, as a result of the temperature sensing, the bridge circuit 10 shown in FIG.
4, a difference between the potentials Va and Vb at the points a and b is obtained.

The value of (Va-Vb) changes when the temperature of the flow sensing temperature sensing element 104-1 changes according to the flow rate of the fluid. Variable resistor 1 of bridge circuit 104 in advance
By appropriately setting the resistance values of 04-3 and 104-4,
In the case of a desired fluid flow rate as a reference, (Va−V
The value of b) can be set to zero. At this reference flow rate,
Output of integrating circuit 108 is constant (value corresponding to reference flow rate)
And the resistance value of the transistor 110 is also constant. In this case, the partial pressure applied to the thin-film heating element 112 also becomes constant, and the voltage at the point P at this time indicates the reference flow rate.

When the fluid flow rate increases or decreases, the output of the integrating circuit 46 has a polarity (depending on the positive or negative of the resistance-temperature characteristic of the flow rate detecting temperature sensing element 104-1) and magnitude according to the value of (Va-Vb). And the output of the integrating circuit 108 changes accordingly.

When the flow rate of the fluid increases, the temperature of the temperature sensing element 104-1 decreases.
In order to increase the calorific value of the transistor 12 (that is, increase the power), a control input to the base of the transistor 110 is made to decrease the resistance value of the transistor 110 from the integrating circuit 108.

On the other hand, when the flow rate of the fluid decreases, the temperature of the temperature sensing element 104-1 increases, so that the amount of heat generated by the thin-film heating element 112 is reduced (ie, the power is reduced). From the circuit 108, a control input to the base of the transistor 110 is provided so as to increase the resistance value of the transistor 110.

As described above, the heat generation of the thin film heating element 112 is feedback-controlled so that the temperature detected by the flow rate detecting temperature sensing element 104-1 always becomes the target value regardless of the change in the fluid flow rate. You. Since the voltage applied to the thin-film heating element 112 (the voltage at point P) at that time corresponds to the fluid flow rate, it is taken out as a flow rate output.

The flow rate output is appropriately A / D converted by an A / D converter, and then subjected to arithmetic processing such as integration by the CPU 120 as shown in FIG.
A display related to the flow rate is displayed on the display unit 122. still,
In response to a command from the CPU 120, the instantaneous flow rate and the integrated flow rate can be stored in a memory as appropriate, and can be transmitted to the outside via a telephone line or other communication line including a network.

In the present embodiment, since the flow passage portion 6 constitutes a fluid storage region, the fluid circulation speed in the flow passage portion 6 is low, and the temperature of the fluid flowing from the flow passage portion 4 into the flow passage portion 6 is low. Changes rapidly, the fluid is mixed with the fluid before the temperature change already existing in the flow passage portion 6, and there is a time allowance for the fluid temperature to be averaged. The temperature change of the supplied fluid becomes gentle. In addition, since the casing member 2 is made of a metal having good heat conductivity, even if the temperature of the fluid flowing into the fluid flow passage of the casing member 2 changes rapidly, the heat conduction of the casing member 2 causes the fluid in the flow passage to flow. Temperature averaging is promoted and the effects of sudden changes in the incoming fluid temperature are mitigated.

As described above, in the present embodiment, the temperature of the fluid in the vertical portion 8a of the flow passage portion 8 where the flow rate detecting unit 24 and the fluid temperature detecting unit 26 are located becomes gentle. Even if the temperature of the fluid flowing in suddenly changes, the fluid temperature detected by the fluid temperature detection unit 26 becomes almost the same as the temperature of the fluid detected by the flow rate detection unit 24, and the fluid temperature compensation is accurately performed. Thus, the accuracy of the flow rate detection can be improved.
Then, since the fluid temperature change in the vertical portion 8a of the flow passage portion 8 where the flow rate detection unit 24 and the fluid temperature detection unit 26 are located becomes gentle, the operation of the control system can be stabilized, From this point, the flow rate detection accuracy can be improved.

[0037]

As described above, according to the present invention,
By forming a fluid stagnation area in the fluid flow passage upstream of the flow rate detection unit and the fluid temperature detection unit, even if the temperature of the inflowing fluid changes suddenly, the fluid temperature compensation is performed accurately to improve the accuracy of the flow rate detection. It can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a flow meter according to the present invention.

FIG. 2 is a partial cross-sectional view of one embodiment of the flow meter of the present invention.

FIG. 3 is a front view of one embodiment of the flow meter of the present invention.

FIG. 4 is a right side view of one embodiment of the flow meter of the present invention.

FIG. 5 is a bottom view of the flow meter according to the embodiment of the present invention, in which a cover member is removed.

FIG. 6 is a left side view of one embodiment of the flow meter of the present invention.

FIG. 7 is a plan view of one embodiment of the flow meter of the present invention.

FIG. 8 is a cross-sectional view of the flow detection unit.

FIG. 9 is a schematic diagram showing a flow rate detection system of an embodiment of the flow meter according to the present invention.

[Explanation of symbols]

 Reference Signs List 2 casing member 3 lid member 4, 8 fluid flow passage portion 6 fluid flow passage portion (fluid retention region) 8a vertical portion 8b horizontal portion 10 male screw 12 filter 14 fluid inflow opening 16 fluid outflow opening 24 flow rate detection unit 26 fluid temperature detection unit 42 Flow rate detecting section 44, 44 'Fin plate 46 Bonding material 48, 48' Electrode terminal 50 Bonding wire 52, 52 'Housing 102 Constant voltage circuit 104 Bridge circuit 104-1 Flow rate detecting thin film temperature sensing element 104-2 For temperature compensation Thin-film thermosensor 104-3, 104-4 Variable resistor 106 Differential amplifier circuit 108 Integrator circuit 110 Transistor 112 Thin-film heating element

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Shinya Furuki 1333-2, Hara-shi, Ageo-shi, Saitama Mitsui Mining & Smelting Co., Ltd. F-term (reference) 2F030 CA10 CD15 CE13 2F031 AC01 AD01 2F035 EA04 EA08

Claims (10)

[Claims] 1. A casing member having a fluid flow passage extending from a fluid inflow opening to a fluid outflow opening. The casing member is attached to the casing member and receives and exchanges heat with the fluid in the fluid flow passage. A flow rate detection unit whose electrical characteristic value changes in response to the flow in the fluid flow passage; and a temperature of the fluid, which is attached to the casing member and exchanges heat with the fluid in the fluid flow passage. A thermal flow meter that has a fluid temperature detection unit whose electrical characteristic value changes in response to the flow rate, and that detects the flow rate of the fluid based on the electrical characteristic value of the fluid temperature detection unit. Wherein the flow of the fluid is higher than the position where heat is exchanged between the flow rate detection unit and the fluid and the position where heat is exchanged between the fluid temperature detection unit and the fluid. Upstream, the fluid flow passage has a flow cross-sectional area of 5 at a position where heat is exchanged between the flow detection unit and the fluid or at a position where heat is exchanged between the fluid temperature detection unit and the fluid. A thermal flow meter having a fluid temperature compensating function, characterized in that a fluid stagnation region having a flow cross section of twice or more is formed. 2. A flow cross section of the fluid stagnation area at a position where heat is exchanged between the flow rate detection unit and the fluid or at a position where heat is exchanged between the fluid temperature detection unit and the fluid. The thermal flow meter according to claim 1, wherein the thermal flow meter has a cross-sectional area that is 10 times or more. 3. A casing member having a fluid flow passage extending from a fluid inflow opening to a fluid outflow opening. The casing member is attached to the casing member and receives and exchanges heat with the fluid in the fluid flow passage. A flow rate detection unit whose electrical characteristic value changes in response to the flow in the fluid flow passage; and a temperature of the fluid, which is attached to the casing member and exchanges heat with the fluid in the fluid flow passage. A thermal flow meter that has a fluid temperature detection unit whose electrical characteristic value changes in response to the flow rate, and that detects a flow rate compensated for fluid temperature by a detection circuit including the flow rate detection unit and the fluid temperature detection unit. A position where heat is exchanged between the flow rate detection unit and the fluid and a position where heat exchange between the fluid temperature detection unit and the fluid is performed. In the upstream of the flow of the fluid, the flow rate of the fluid in the fluid flow passage is set at a position where heat exchange between the flow rate detection unit and the fluid is performed or heat exchange between the fluid temperature detection unit and the fluid is performed. A thermal flow meter having a fluid temperature compensating function, wherein a fluid stagnation region is formed so as to be 1/5 or less of a fluid flow speed at a position where the fluid flows. 4. The fluid stagnation area is located at a position where the flow rate of the fluid flows at a position where heat is exchanged between the flow rate detection unit and the fluid or at a position where heat exchange between the fluid temperature detection unit and the fluid is performed. 1/1 of fluid circulation speed
Characterized by being formed to be 0 or less,
The thermal flow meter according to claim 3. 5. The volume of the fluid stagnation area is a fluid flow direction at a position where heat is exchanged between the flow rate detection unit and the fluid or at a position where heat is exchanged between the fluid temperature detection unit and the fluid. Of volume per unit length of 5
The thermal flowmeter according to claim 1, wherein the thermal flowmeter is at least 0 times. 6. The fluid flow passage, wherein a first portion of the flow passage that communicates with the fluid inflow opening and the fluid outflow opening communicate with the flow rate detection unit and heat of the fluid, and the fluid temperature detection unit and the fluid temperature detection unit communicate with each other. A fluid passage second portion for transferring heat to and from the fluid, wherein the fluid retention region is located between the fluid passage first portion and the fluid passage second portion; The flow cross section of the portion is smaller than the flow cross section of the fluid retention area.
6. The thermal flow meter according to any one of claims 1 to 5, 7. The fluid passage second portion is configured to hold the fluid at a position where heat is exchanged between the flow rate detection unit and the fluid and a position where heat exchange is performed between the fluid temperature detection unit and the fluid. 7. The thermal flow meter according to claim 6, comprising a part extending parallel to the region. 8. The thermal flow meter according to claim 6, wherein a filter is interposed in a communicating portion between the fluid retaining region and the second portion of the flow passage. 9. The thermal flow meter according to claim 1, wherein said casing member is made of metal. 10. The flow rate detection unit includes a heating element, a flow rate detection temperature sensing element, and a flow rate detection heat transfer member that can be extended into the fluid flow passage so as to be able to transfer heat to each other. The fluid temperature detection unit may be configured such that a fluid temperature detection temperature sensing element and a fluid temperature detection heat transfer member that can be extended into the fluid flow passage are arranged so as to be able to transfer heat to each other. The thermal flow meter according to any one of claims 1 to 9, characterized in that: