JPH04291118A - flow sensor - Google Patents

Abstract

PURPOSE:To improve the mounting property, durability, environmental resistance, safety, maintainability, etc., of a flow sensor. CONSTITUTION:After a metallic film of Ni, etc., is formed on the upper surface of a thin lower organic film 2 by a sputtering method, etc., and the patterns of an upstream-side heat sensitive sensor 3, downstream-side heat sensitive sensor 4, heater 5, and electrode 6 are formed by using a photomask, photoresist, and etching liquid, the surface of the film 2 is coated with a thin upper organic film 7. In addition, a lower reinforcing organic film 9 is formed on the lower surface of the film 2, with an air space 8 being left, and an upper reinforcing organic film 10 is formed on the upper surface of the film 2. Therefore, this flow sensor 1 can be formed in an elastically deformable state so as to improve the mounting property and, at the same time, the durability, environmental resistance, safety, and maintainability of the sensor 1 can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate sensor, and particularly to a flow rate sensor suitable for improving durability, environmental resistance, ease of mounting, ease of maintenance, safety, etc.

0002

[Prior Art] Conventionally, for example, Japanese Patent Application Laid-Open No. 63-252224
As in the technique described in the publication, a thin film heater and a pair of thin film heat sensing sensors are provided on a semiconductor substrate, and a layer made of a material having a large heat capacity is formed on the thin film heater and the pair of heat sensing sensors. and the semiconductor substrate, the thin film heater and
A flow velocity sensor has been developed that has a structure in which a space is formed between the pair of heat-sensing sensors, and the pair of thin-film heat-sensing sensors is formed near the thin-film heater and approximately parallel to the thin-film heater through an insulating part. has been done.

0003

However, the above-mentioned prior art has the following problems. When measuring the speed of fluid flow using the flow rate sensor, the flow rate sensor may become contaminated due to the influence of dirt or dust present in the fluid, resulting in poor measurement accuracy, or heat detection due to the flow of fluid. Sensors and thin film heaters may deteriorate, etc.
There were problems with reliability, durability, and environmental resistance. Also,
The flow velocity sensor has a structural property that it is difficult to elastically deform (bend) because it is a heat sensing sensor formed on a semiconductor substrate, but the flow path to which the flow velocity sensor is attached is connected to a pipe (e.g. Because there are many curved surfaces on the inner surface (casing, etc.), depending on the curvature of the inner surface of the pipe in the flow path, it is difficult to attach the flow velocity sensor directly to the inner surface of the pipe, for example, it may be necessary to attach the flow velocity sensor via a fixing member. However, there was a problem in that it took time and effort to install.

[0004] The present invention is intended to solve the above-mentioned problems, and aims to provide a flow sensor that achieves improvements in durability, environmental resistance, ease of mounting, safety, maintainability, etc.

[0005]

[Means for Solving the Problems] The present invention comprises a thin film heating means, a pair of thin film heat sensing means, and an electrode connected to the heating means and the heat sensing means. In a flow rate sensor that measures the flow rate based on the output difference between the pair of heat sensing means depending on the presence or absence of a flow, the heating means, the heat sensing means, and the electrode pattern are made of a thin film of a first organic material that can be elastically deformed. is formed on the surface of the film, and the first
The surface of the organic material film on the pattern formation side is covered with a second organic material film which is an elastically deformable thin film.

[0006]

[Operation] According to the present invention, since the flow rate sensor can be elastically deformed, it is possible to improve the ease of mounting regardless of the curvature of the curved surface of the piping, and it is also possible to improve the durability against external stress. , the heat sensing means, and the heating means are completely covered with an organic film, so it is possible to accurately measure the flow rate without being affected by dirt in the fluid or deteriorating.It is reliable, environmentally resistant, safe, Maintainability can be improved.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained based on the drawings. 1 and 2 are a plan view and a cross-sectional view of the flow rate sensor 1 of this embodiment, which is made of an elastically deformable thin film (for example, several μm or less in thickness) made of polyimide, polyester, etc. with low thermal conductivity. An upstream heat sensing sensor 3 and a downstream heat sensing sensor 4 are formed on one side in the longitudinal direction of the upper surface of the lower organic substance film 2. A thin film heater 5 is formed between the two. In this case, the upstream heat sensing sensor 3 and the downstream heat sensing sensor 4 are arranged symmetrically with respect to the heater 5. The flow rate sensor 1 is arranged in a flow path pipe such that the upstream heat sensing sensor 3 is located on the upstream side of the fluid in the flow path pipe, and the downstream heat sensing sensor 4 is located on the downstream side of the fluid in the flow path pipe. It is designed to be attached to the inside. Further, on the other side in the longitudinal direction of the upper surface of the lower organic substance film 2, a plurality of ( In this embodiment, for example, six electrodes 6 are formed, and a part of the electrodes 6 is exposed in order to connect the electrodes 6 to an external circuit. That is,
After forming a metal film such as Ni on the upper surface of the lower organic film 2 by a method such as sputtering, the upstream heat sensing sensor 3, downstream heat sensing sensor 4, A pattern of heaters 5 and electrodes 6 is formed.

Furthermore, the surface of the lower organic film 2 on which the patterns of the upstream heat sensor 3, downstream heat sensor 4, heater 5, and electrode 6 are formed is made of a material having low thermal conductivity, such as polyimide or polyester. It is covered with an upper organic film 7 which is an elastically deformable thin film (for example, a thickness of several μm or less). That is, an upstream heat sensing sensor 3, a downstream heat sensing sensor 4 formed on the upper surface of the lower organic film 2,
By covering the heater 5 and electrode 6 with the upper organic film 7, oxidation and corrosion of the upstream heat sensing sensor 3, the downstream heat sensing sensor 4, and the heater 5 are prevented. The thermal responsiveness of the flow rate sensor 1 is improved by forming the upper organic film 2 and the upper organic film 7 to be as thin as several μm or less. Further, a lower reinforcing organic film 9 that is elastically deformable with an air space 8 is formed on the lower surface of the lower organic film 2, and an elastically deformable upper reinforcing organic film 9 is formed on the upper surface of the upper organic film 7. The lower reinforcing organic film 9 and the upper reinforcing organic film 10 are made of, for example, polyimide or polyester. By using the lower reinforcing organic material film 9 and the upper reinforcing organic material film 10 as reinforcing materials for the lower organic material film 2 and the upper organic material film 7 formed into thin films, the mechanical strength of the flow rate sensor 1 is improved. It has become. In this case, by providing the air space 8 in a part of the lower surface of the lower organic film 2, thermal insulation of the upstream heat sensor 3, the downstream heat sensor 4, and the heater 5 is improved. There is. The flow rate sensor 1 includes a flow rate detection section 11 in which an upstream heat detection sensor 3, a downstream heat detection sensor 4, and a heater 5 are formed.
It is roughly divided into an electrode section 12 in which an electrode 6 is formed. Since the flow rate sensor 1 of this embodiment has the above-described structure, it can be elastically deformed (bent). Note that the arrows in FIG. 2 indicate the direction of fluid flow.

Next, the operation of the flow rate sensor of this embodiment having the above configuration will be explained. As shown in FIG. 3, after bonding the flow rate detection part 11 of the flow rate sensor 1 to the inner surface of the flow path pipe P to be measured, the flow rate sensor 1 is used to adjust the inner and outer surfaces of the pipe by utilizing its elastic deformation properties. It is bent along the curvature, the electrode part 12 is drawn out of the flow path pipe P, and the electrode part 12 is connected to an external circuit (not shown). In this case, since the flow rate sensor 1 is elastically deformable, it can be accurately attached to the curved surface of the pipe regardless of the curvature of the flow path pipe P. With the above connection, the heater 5 of the flow rate detection unit 11 is heated to a predetermined temperature from the external circuit via the electrode 6 of the electrode unit 12, and the upstream heat detection sensor 3 and downstream heat detection sensor 4 of the flow rate detection unit 11 are heated. The output of is supplied to an external circuit. After this, when measuring the flow rate inside the flow path pipe P, if there is no fluid flow,
an upstream heat sensing sensor 3 arranged symmetrically with respect to the heater 5;
As a result of the downstream heat sensing sensor 4 being heated to the same temperature by uniform heat conduction from the heater 5, there is no output difference between the two sensors 3 and 4, so the flow rate is measured as 0 by the external circuit. On the other hand, when there is a flow of fluid, the upstream heat sensor 3 is cooled as the fluid flows toward the heater 5, and the downstream heat sensor 4 is heated by the flow of fluid heated by the heater 5. As a result, a difference occurs between the outputs of both sensors 3 and 4, so that an external circuit measures the flow rate according to the fluid flow.

By the way, since the flow rate sensor 1 of this embodiment can be elastically deformed, it is possible to improve the ease of attachment to the flow path pipe, regardless of the curvature of the curved surface of the flow path pipe, as described above. Can be done. In addition, the upstream heat sensor 3, the downstream heat sensor 4, and the heater 5 of the flow rate sensor 1
The flow rate sensor 11 is completely covered with a lower organic film 2 and an upper organic film 7, which are chemically stable such as polyimide or polyester. It is possible to accurately measure the flow rate without being influenced or altered, and it is possible to improve reliability, durability, environmental resistance, safety, maintainability, etc.

[0011]

As described above, the present invention includes a thin film heating means, a pair of thin film heat sensing means, and an electrode connected to the heating means and the heat sensing means. In the flow rate sensor, the flow rate is measured based on the output difference between the pair of heat sensing means depending on the presence or absence of fluid flow, in which the heating means, the heat sensing means, and the electrode pattern are made of elastically deformable thin film. The organic material film is formed on the surface of the first organic material film, and the surface of the first organic material film on the pattern formation side is covered with the second organic material film, which is an elastically deformable thin film, so that the following effects can be achieved. Can be done. (1) Since the flow sensor has a structure that can be elastically deformed (bending), the flow sensor can be easily fixed regardless of the curvature of the curved surface of the flow path pipe, etc., which improves the ease of mounting. It is possible to improve durability against external stress. (2) Also, since the heat sensing means and heating means of the flow sensor are completely covered with an organic film, the flow sensor accurately measures the flow rate without being affected by dirt or dust in the fluid or changing its quality. As a result, the reliability of the flow sensor can be improved, as well as environmental resistance, safety, and maintainability.

[Brief explanation of the drawing]

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

FIG. 2 is a plan view of the flow rate sensor of this embodiment.

FIG. 3 is a perspective view of an example of how the flow rate sensor of this embodiment is attached to a flow path pipe.

[Explanation of symbols]

1 Flow rate sensor 2 Lower organic film (first organic film) 3 Upstream heat sensing sensor (heat sensing means) 4 Downstream heat sensing sensor (
Heat sensing means) 5 Heater (heating means) 6 Electrode 7 Upper organic film (second organic film) 8 Air space 9 Lower reinforcing organic film 10 Upper reinforcing organic film 11 Flow rate detection section 12 Electrode section

Claims (1)

[Claims] 1. A thin film heating means, a pair of thin film heat sensing means, and an electrode connected to the heating means and the heat sensing means, the pair of thin film heat sensing means being connected to each other according to the presence or absence of fluid flow. In the flow rate sensor that measures the flow rate based on the output difference of the heat sensing means, a pattern of the heating means, the heat sensing means, and the electrodes is formed on the surface of the first organic substance film which is an elastically deformable thin film; A flow rate sensor characterized in that a surface of the first organic material film on the pattern formation side is covered with a second organic material film that is an elastically deformable thin film.