JP2003090750A - Flow rate/flow velocity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate/flow velocity measuring apparatus that has a simple structure for facilitating manufacture and accurately measures flow rate/flow velocity. SOLUTION: The flow rate/flow velocity measuring apparatus has a detection element 2 that is arranged on a channel wall 3a on the outer periphery side of a channel 1 that is curved in a U shape while a flat flow passes, recesses 4a and 4b that are formed on a channel wall 3a at the upstream and downstream sides of the detection element 2 adjacently to the detection element 2, a curved section 5a that is formed on the channel wall 3a at the upstream side of the recess 4a, and a curved section 5b that is formed on a channel wall 3a at the downstream of the recess 4b. The flow is brought to the channel wall 3a where the detection element 2 is located, at the same time the turbulence constituent of the flow is taken into the recess 4a, the development of the turbulence constituent on a detection surface 2a is prevented, and the straightened flow is guided onto the detection surface 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a measuring device for measuring various quantities related to a flow, in particular, a flow rate and a flow velocity, and in particular, a heat-generating or endothermic detecting element and / or a detection integrally formed on a semiconductor chip. The present invention relates to a split flow meter using an element. This shunt type flow meter is, for example, a mass flow sensor for combustion control of a vehicle or an industrial engine, a mass flow sensor for an industrial air conditioning system or a compressed air supply system for a compressor, and an air-fuel ratio control for a domestic gas stove. It is suitably used as a flow rate sensor, a flow rate sensor for various industrial gases, and the like.

[0002]

2. Description of the Related Art JP-A-6-50783 and JP-A-2
Japanese Patent Laid-Open No. 000-275076 proposes a flow rate and flow velocity measuring device that suppresses eddy currents and separation of flows by making the detection surface of the detection element and the wall surface of the flow channel supporting the detection element flush. ing.

[0003]

However, the above-mentioned JP-A-6-50783 and JP-A-2000-27.
In order to achieve the above-mentioned flush surface described in Japanese Patent No. 5076, high manufacturing technology and detection element mounting technology are required, and precise inspection is also required.

A problem to be solved by the present invention is to provide a flow rate and flow velocity measuring device (hereinafter, also simply referred to as a measuring device) which has a simple structure which is easy to manufacture and which enables highly accurate flow rate and flow velocity measurement. .) Is to be provided.

[0005]

According to a first aspect of the present invention, a recess is formed in a flow passage wall on the upstream side and / or the downstream side of a detection element for detecting a flow-related quantity. Provided is a flow rate and flow velocity measuring device having a flow path structure in which a flow path is formed.

The concave portion effectively removes the turbulent flow component generated on the detection surface of the detection element, and enables stable flow rate and flow velocity measurement. Further, since the concave portion can be formed by a relatively simple method, the flow rate and flow velocity measuring device according to the present invention can be manufactured by a simplified process. According to the flow rate and flow velocity measuring apparatus of the present invention, highly accurate measurement is possible even when the mounting accuracy (assembly accuracy) of the detection element or the accuracy of product inspection is set to be relatively low. For example, even if the detection surface of the detection element and the wall surface of the flow path in the vicinity of the detection element are not located on the same surface (in order to position both surfaces on the same surface, the mounting accuracy of the detection element should be high. In the flow rate and flow velocity measuring device according to the present invention, since the turbulent flow such as a vortex flow on the detection surface is suppressed by having the concave portion, highly accurate measurement is possible.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below.

In a preferred embodiment of the invention,
As shown in FIG. 3, a diversion pipe is connected to the main flow pipe (not shown), a part of the flow in the main flow pipe (the flow Flow to be detected) is divided into the diversion pipe, and the divided flow is The flow rate or flow velocity is determined by the flow passage wall of the diversion pipe, for example,
It is detected by the detection element attached to the wall surface on the outer peripheral side of the bottom portion of the flow path curved in a substantially U shape. In particular, in the case of measuring both forward flow and reverse flow flowing in opposite directions in the flow path, concave portions are formed adjacent to the detection element on both the upstream side and the downstream side of the detection element (see FIG. 4). ).

It is desirable that the bottom surface of the recess be at a position lower (recessed) than the detection surface (upper surface) of the detection element, and more preferably 100 μm or more. The reason is that the turbulent flow component generated by the wall surface of the flow path can be effectively suppressed. Further, it is desirable that the detection surface of the detection element is located at a position lower than the wall surface of the flow path (the wall surface of the flow path on the side opposite to the detection element with respect to the recess).
It is more preferable if it is μm lower. The reason is that it is possible to suppress the influence of the turbulent flow component generated by the end portion of the detection element.

Although the recess can be formed by the following simple method, the method is not limited to the method described here. First, when forming the detection element mount part by resin molding, another detection part having a slightly larger area than the mold shape (convex shape) of the detection element mount part in the mold is formed as the detection element mount part. It is formed at a position one step lower than the upper surface of the convex portion. By molding using this mold shape, it is possible to simplify the dimension control of the convex portion for forming the detection element mount portion, and it is possible to easily form the concave portion.

In a preferred embodiment of the invention,
A flow direction control unit that biases the flow toward the detection surface (upper surface) of the detection element is formed on the upstream side or both sides of the detection element. By providing such a flow direction control unit, the flow in the flow path is generated as a flow that smoothly goes to the detection surface of the detection element, and as a result, the measurement accuracy is improved.

In a preferred embodiment of the invention,
A flow restrictor is formed on a wall of the flow path facing the detection surface of the detection element so that the flow is diverted toward the detection surface of the detection element. As a result, the flow in the flow path is brought closer to the flow path wall surface side where the detection element is located, and the flow on the detection surface of the detection element is rectified, and as a result, the measurement accuracy is improved.

In a preferred embodiment of the invention,
The following thermal detection elements are used. That is, this detection element is basically a thermal detection element in which four thin film resistors are provided on the surface of the substrate. More specifically, the diaphragm portion and the rim portion are provided on the semiconductor substrate.
The diaphragm portion is provided with (1) an upstream temperature sensor, (2) a downstream temperature sensor, and (3) a heater arranged between the upstream temperature sensor and the downstream temperature sensor. On the other hand, the rim portion is provided with (4) atmosphere temperature sensor. The diaphragm part is made extremely thin to achieve thermal insulation.

Next, the principle of detecting various quantities related to the flow such as the flow velocity and the flow rate using this detecting element will be described. (1) The electric power supplied to the heater is controlled so that the heater always has a constant temperature difference with respect to the ambient temperature. (2) Therefore, when there is no flow, the temperatures detected by the upstream temperature sensor and the downstream temperature sensor are almost equal. (3) However, when there is a flow, the temperature detected by the upstream temperature sensor decreases because heat escapes from its surface. The temperature detected by the downstream temperature sensor is smaller than that of the upstream temperature sensor because the heat input from the heater increases. The temperature of the downstream temperature sensor may increase. (4) The flow rate, the flow velocity, etc. are detected based on the detected temperature difference between the upstream temperature sensor and the downstream temperature sensor, and the flow direction is detected from the sign (the magnitude relationship) of this temperature difference. The temperature difference can be detected based on the change in electric resistance due to temperature.

In a preferred embodiment of the invention,
Another thermal sensing element is used as follows. That is, this other detection element is basically a thermal detection element in which three thin film resistors are provided on the surface of the substrate. More specifically, the diaphragm portion and the rim portion are provided on the semiconductor substrate. The diaphragm part has (1) an upstream heater and
(2) A downstream heater is provided. On the other hand, on the rim
(3) An ambient temperature sensor is provided. The diaphragm part is made extremely thin to achieve thermal insulation.

Next, the principle of detecting various quantities related to the flow such as the flow velocity and the flow rate using the other detecting element will be described. (1) The electric power supplied to the heater is controlled so that both the upstream heater and the downstream heater have a constant temperature difference with respect to the ambient temperature. (2) Therefore, when there is no flow, the temperatures of the upstream heater and the downstream heater are almost equal. (3) When there is a flow, the temperatures of the upstream heater and the downstream heater decrease because heat escapes from their surfaces. The temperature change of the downstream heater is smaller than that of the upstream heater because the heat input from the upstream heater increases. The temperature of the downstream heater may increase. (4) Based on the temperature change between the upstream heater and the downstream heater, the flow rate, flow velocity, etc. are detected from the respective differences in current or voltage required to maintain a constant temperature, and the sign of the difference in current or voltage ( The flow direction is detected based on the magnitude relationship. The temperature change can be detected based on the amount of change in electric resistance due to temperature.

The flow rate and flow velocity measuring device according to the present invention is preferably applied to the measurement of the flow rate of intake air and exhaust flow of an internal combustion engine mounted on a vehicle. For example, the measuring device according to the present invention is installed in the intake system of the engine of various vehicles, and can be applied to the measurement of the intake air amount of the engine mounted in a two-wheel or four-wheel vehicle. More specifically, the measuring device according to the present invention is installed in any part of the pipe line from the inside of the air cleaner to the throttle valve in the intake system of an engine mounted on a four-wheel vehicle. Further, the measuring device according to the present invention, in the intake system of an engine mounted on a two-wheel vehicle, introduces a flow rate or a flow velocity of intake gas into an intake pipe for a two-wheel vehicle connected to a cylinder, an air funnel in an air cleaner box, or the like. It is attached to measure etc.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to further clarify the preferred embodiment of the present invention described above, one embodiment of the present invention will be described with reference to the drawings.

[Comparative Examples 1 and 2] First, Comparative Example 1 having no recess, which is one of the features of the measuring apparatus of the present invention.
A flow rate and flow velocity measuring device according to Comparative Example 2 will be described.

FIGS. 1 and 2 are views for explaining the generation states of turbulent flow components near the detection element in the flow rate and flow velocity measuring devices according to Comparative Example 1 and Comparative Example 2, respectively.

Referring to FIG. 1, in the measuring apparatus of Comparative Example 1, the detection surface 2a of the detection element 2 is located at a position (protruding position) higher than the wall surface of the flow path wall 3a on which the detection element 2 is supported. Yes (there is a positive step). By this step,
The generation of turbulent components such as vortices is promoted on the detection surface 2a, so that highly accurate measurement is difficult.

Referring to FIG. 2, in the measuring device of Comparative Example 2, the detection surface 2a of the detection element 2 is located at a position lower than the wall surface of the flow path wall 3a on which the detection element 2 is supported (recessed position). Yes (there is a negative step). By this step,
The generation of turbulent components such as vortices is promoted on the detection surface 2a, so that highly accurate measurement is difficult.

Next, without using the high-precision detection element mounting technology and inspection technology for making the detection surface of the detection element flush with the wall surface of the flow channel, which is required to obtain the conventional measuring device, A flow rate and flow velocity measuring device according to an embodiment of the present invention that can achieve highly accurate measurement will be described.

[Embodiment 1] FIG. 4 is an explanatory view of a flow rate and flow velocity measuring apparatus according to Embodiment 1 of the present invention, showing a cross section of a main part of a flow path along a flow direction. FIG. 5 is an enlarged view of a main part of FIG.

With reference to FIGS. 4 and 5, the flow rate and flow velocity measuring apparatus includes a laminar flow (Flo) to be detected.
w) a flow path wall 3a on the outer peripheral side of the bottom of the flow path 1 curved in a U shape through which a detection element 2 arranged to be exposed to the flow in the flow path 1 and for detecting an amount related to the flow. The recess 4 formed in the flow passage wall 3a on the upstream side and the downstream side of the detection element 2 (the flow passage wall 3a on the detection element 2 side) adjacent to the detection element 2.
a and 4b. The flow channel wall facing the flow channel wall 3a is referred to as a flow channel wall 3b. The flow path 1 on the upstream side of the recess 4a
In addition, the flow path wall 3a has a structure in which the flow is diverted toward the detection surface (upper surface) 2a of the detection element 2 (flow direction control unit).
As a result, a curved portion 5a is formed, and similarly, a curved portion 5b is formed in the flow channel 1 or the flow channel wall 3a on the downstream side of the recess 4b. That is, the concave portion 4a is formed between the detection element 2 and the curved portion 5a, and the concave portion 4b is formed between the detection element 2 and the curved portion 5b. The detection surface 2a of the detection element is fixed to the flow path wall 3a in a recess of about 100 μm, and the bottom surfaces of the recesses 4a and 4b are the detection surface 2a.
It is formed at a position recessed by about 200 μm in the downward direction of FIG.

Next, the state of the flow in the vicinity of the detecting element 2 will be described.

In particular, referring to FIG. 5, the curved portion 5a causes the flow (flow) to be diverted toward the detection surface 2a (the flow is the flow path wall 3a where the detection element 2 is located).
Sent to). Next, the turbulent flow component is taken into the recess 4a (a vortex is formed in the recess 4a). Thus, due to the buffering effect of the recess 4a, the concave portion of FIG.
As shown in (1), the turbulent flow component generated on the detection surface 2a is removed, and the rectified flow is guided to the detection surface 2a. When the flow (flow) flows in the direction opposite to the direction shown in FIG. 5, the turbulent flow component is effectively removed by the recess 4b.

By thus providing the flow direction control portions 5a and 5b and the concave portions 4a and 4b, the detection surface 2a,
Even if the flow path surfaces near the detection surface 2a are not on the same surface, the generation of turbulent flow on the detection surface 2a is effectively suppressed, and a regular flow can be obtained on the detection surface 2a.
The flow rate or flow velocity can be detected with high accuracy.

[Embodiment 2] FIG. 6 is an explanatory view of a flow rate and flow velocity measuring apparatus according to Embodiment 2 of the present invention, showing a cross-section of a main part of a flow path along a flow direction. The second embodiment is an example in which the curved portion (flow direction control portion) in the measuring apparatus of the first embodiment is not provided, and the flow restricting portion is provided on the flow path wall facing the detection element 2.

Referring to FIG. 6, this flow rate and flow velocity measuring device has a flow passage wall 3a on the outer peripheral side of the bottom of the flow passage 1 curved in a U shape through which a laminar flow (Flow) to be detected passes.
And a detection element 2 arranged to be exposed to the flow in the flow path 1 and detecting an amount related to the flow, and flow path walls 3a (upstream and downstream of the detection element 2 adjacent to the detection element 2 ( It has recesses 4a and 4b formed in the flow path wall 3a on the detection element 2 side. On the flow path wall 3b facing the detection surface (upper surface) 2a of the detection element 2, there is formed a flow restricting portion (projection portion) 6 that projects toward the detection surface 2a and diverts the flow toward the detection surface 2a. There is. The apex of the flow restricting portion 6 is positioned so as to secure a predetermined gap on the detection surface 2a, and the flow path is narrowest on the detection surface 2a in the vicinity of the detection element. The detection surface 2a of the detection element is fixed to the flow path wall 3a in a recessed state by about 100 μm, and the bottom surfaces of the recesses 4a and 4b are arranged in the downward direction of FIG. 6 with respect to the detection surface 2a. It is formed at a depth of 200 μm.

Next, the state of the flow in the vicinity of the detecting element 2 will be described. FIG. 7 is an enlarged view of a main part of FIG.

Referring to FIG. 7, the flow restrictor 6 causes the flow (flow) to be biased toward the detection surface 2a (the flow is brought to the side of the flow path wall 3a where the detection element 2 is located) and is detected. It is narrowed down on the surface. Next, the turbulent flow component is taken into the recess 4a (a vortex is formed in the recess 4a). Thus, due to the buffering effect of the concave portion 4a, the turbulent flow component generated on the detection surface 2a as shown in FIG. 1 or 2 is removed, and the rectified flow is guided to the detection surface 2a. Note that the flow is
When flowing in the direction opposite to the direction shown in FIG.
b effectively removes the turbulent components of the flow.

In this way, the flow restrictor 6 and the recesses 4a, 4
By providing b, even if the detection surface 2a and the flow path surface in the vicinity of the detection surface 2a are not on the same surface, the occurrence of turbulent flow on the detection surface 2a is effectively suppressed, and the detection surface 2a is adjusted. The obtained flow can be obtained, and as a result, the flow rate or the flow velocity can be detected with high accuracy.

[Embodiment 3] FIG. 8 is an explanatory view of a flow rate and flow velocity measuring apparatus according to Embodiment 2 of the present invention, showing a cross section of a main part of a flow path along a flow direction.

With reference to FIG. 8, this flow rate and flow velocity measuring device has a flow path wall 3a of a substantially straight flow path 1 through which a laminar flow (Flow) to be detected passes, and the flow path 1 A detection element 2 arranged to be exposed to the flow and detecting an amount related to the flow, and a flow channel wall 3a on the upstream side and the downstream side of the detection element 2 adjacent to the detection element 2 (the flow channel wall on the detection element 2 side). )
It has the concave portions 4a and 4b formed in. The detection surface 2a of the detection element is about 100 μm away from the flow path wall 3a.
The recesses 4a and 4b are fixed in a depressed state, and the bottom surfaces of the recesses 4a and 4b are formed at a position recessed from the detection surface 2a by about 200 μm in the downward direction of FIG.

Next, the state of the flow in the vicinity of the detecting element 2 will be described. FIG. 9 is an enlarged view of a main part of FIG.

Referring to FIG. 9, the turbulent flow component is taken into the recess 4a (a vortex is formed in the recess 4a). Thus, due to the buffering effect of the concave portion 4a, the turbulent flow component generated on the detection surface 2a as shown in FIG. 1 or 2 is removed, and the rectified flow is guided to the detection surface 2a. In addition, when the flow (flow) flows in the direction opposite to the direction shown in FIG.
Effectively removes the turbulent components of the flow.

As described above, even when the flow path through which the flow to be measured passes is not provided with the flow direction controller or the flow restrictor, the concave portions 4a and 4b are adjacent to the detection element.
By providing the turbulent flow on the detection surface 2a, it is possible to effectively suppress the generation of turbulent flow, and to obtain a regular flow on the detection surface 2a. As a result, the flow rate or the flow velocity can be detected with high accuracy. it can.

In the above description of the first to third embodiments, the detection surface 2a and the wall surface of the flow path in the vicinity of the detection element 2 are not on the same surface, but when they are formed on the same surface. The same effect is also applied to.

[0040]

As described above, the present invention has the following effects.

The first effect of the present invention is that the detection surface of the detection element and the flow path wall surface are formed on the same surface by providing the concave portion in the flow path wall on the upstream side and / or the downstream side of the detection element. Therefore, the flow rate and flow velocity measuring device can be provided by a simple manufacturing process without using an advanced and complicated manufacturing technique or an element mounting technique.

The second effect of the present invention is to detect the detection element by using a flow rate and flow velocity measuring device having a simple structure in which a recess is provided in the flow path wall on the upstream side and / or the downstream side of the detection element. The turbulent flow component on the surface is reduced, and highly accurate flow rate and flow velocity measurement is possible.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a flow rate and flow velocity measuring device according to a comparative example 1.

FIG. 2 is an explanatory diagram of a flow rate and flow velocity measuring device according to a comparative example 2.

FIG. 3 is an explanatory diagram showing an example of the overall structure of a flow rate and flow velocity measuring device according to the present invention, showing a flow path cross section along the flow direction.

FIG. 4 is an explanatory diagram of a flow rate and flow velocity measuring device according to the first embodiment of the present invention, showing a cross section of a main part of a flow path along a flow direction.

FIG. 5 is an enlarged view of a main part of FIG.

FIG. 6 is an explanatory diagram of a flow rate and flow velocity measuring device according to a second embodiment of the present invention, showing a cross section of a main part of a flow path along a flow direction.

FIG. 7 is an enlarged view of a main part of FIG.

FIG. 8 is an explanatory diagram of a flow rate and flow velocity measuring device according to a third embodiment of the present invention, showing a cross section of a main part of a flow path along a flow direction.

9 is an enlarged view of a main part of FIG.

[Explanation of symbols]

1 flow path 2 detection element 2a detection surface (upper surface) 3a flow path wall (flow path wall on which detection element is supported) 3b flow path wall (flow path wall facing detection surface (upper surface) of detection element) 4a, 4b Recesses 5a, 5b Curved part (flow direction control part) 6 Flow constriction part (projection part)

Continued front page    (72) Inventor Takio Kojima             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. (72) Inventor Takafumi Oshima             14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi Japan special             Within Toyo Co., Ltd. F-term (reference) 2F030 CA10 CF09                 2F035 AA02 EA03 GA01

Claims (7)

[Claims] 1. A detection element which is arranged so as to be exposed to the flow in a passage through which a flow to be detected passes and which detects an amount related to the flow, and an upstream side of the detection element which is adjacent to the detection element. And / or a recess formed in the flow path wall on the downstream side, the flow rate and flow velocity measuring device. 2. A flow restricting portion for deflecting the flow toward the detection surface of the detection element is formed on a flow path wall facing the detection surface of the detection element. The flow rate and flow velocity measuring device described. 3. The flow rate and flow velocity measuring device according to claim 2, wherein the flow restrictor is formed so that the flow path on the detection surface is narrowest in the vicinity of the detection element. 4. The flow rate and flow velocity measurement according to any one of claims 1 to 3, wherein the detection element is installed on a wall surface on the outer peripheral side of the bottom portion of the flow path curved in a substantially U shape. apparatus. 5. A flow direction control unit for biasing the flow toward the detection surface of the detection element is formed in a flow channel or a flow channel wall on the upstream side and / or the downstream side of the recess. The flow rate and flow velocity measuring device according to any one of claims 1 to 4. 6. The flow rate and flow velocity measuring device according to claim 5, wherein the concave portion is arranged between the detection element and the flow direction control portion formed on the flow path wall. 7. The method according to claim 1, wherein the method is applied to flow rate measurement of intake air and exhaust air of an internal combustion engine mounted on a vehicle.
The flow rate and flow velocity measuring device according to any one of 1.