JP2000137037A - Thermister air-speed detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a wind speed without depositing substantially a mist such as a paint particle, even when used, for example, inside an exhaust gas duct in an applying process, inside an exhaust gas duct in a cut metal component annealing furnace and the like. SOLUTION: Shielding plates 2, 3 are arranged in a periphery of a thermister element 1. A particle is prevented from coming into contact with the thermister element 1 by the shielding plate 2 in the windward side, and the particle is prevented from coming into contact with the thermister element 1, by an air current disturbed by the shielding plate 2 in the windward side, using the shielding plate 3 in the leeward side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor wind speed detector which uses a thermistor element as a heating element and detects the flow velocity of gas by utilizing the heat radiation, and in particular, devises the positional relationship between the thermistor element and a shielding plate. Thereby, for example, even when used in an exhaust duct of a painting process or an exhaust duct of a cutting metal part annealing furnace, there is almost no adhesion of mist such as paint particles, and the wind speed can be accurately detected. About things.

[0002]

2. Description of the Related Art Conventionally, methods for detecting a gas flow velocity (wind velocity) include a method for detecting the number of rotations of a windmill, a method for measuring the number of generated Karman vortices, and a method for utilizing the heat radiation of a heating element. Are known. Here, in the method of detecting the number of rotations of the windmill, a movable portion for counting the number of rotations is exposed to the measurement space. The Kalman velocimeter detects the number of vortices by various methods, and this detection unit is exposed to a measurement environment. Also, in the case of a thermal anemometer that heats a thermistor or a platinum resistor to a constant temperature and detects the heat radiation as a change in electric resistance, the detection unit is exposed to the measurement environment.

[0003]

These various current meters (wind speed detectors) can detect the wind speed without any problem when used in an environment having ordinary cleanliness. When used in the exhaust duct of a steel pipe or the exhaust duct of a cutting metal part annealing furnace, mist such as paint particles immediately adheres to any of the detectors, resulting in significant measurement errors. I will.
Therefore, in the past, measures such as installing a pipe cut into a substantially semi-cylindrical shape or a cover formed in a substantially U-shape in front of the thermistor of the detector were taken, but at both ends of the pipe and the cover, The generated vortex flows back to the thermistor, entrains mist such as paint particles, and attaches it to the thermistor, and the detector must be replaced quite frequently, which is very uneconomical.

The present invention has been made on the basis of the above points, and the object thereof is, for example, when a paint is used in an exhaust duct of a coating process or an exhaust duct of a cutting metal part annealing furnace. It is an object of the present invention to provide an inexpensive thermistor wind speed detector capable of accurately detecting a wind speed with little adhesion of mist such as particles.

[0005]

To achieve the above object, a thermistor wind speed detector according to the present invention is a thermistor wind speed detector in which a shield plate is arranged around a thermistor element. Prevents particles from coming into contact with the thermistor element, and prevents particles from coming into contact with the thermistor element due to air currents disturbed by the shielding plate on the leeward side with the shielding plate on the leeward side. is there.

A thermistor wind speed detector according to another aspect of the present invention is a thermistor wind speed detector in which a shielding plate is disposed around the thermistor element. Is disposed, a thermistor element is disposed in an upright state inside a first straight line connecting the edges thereof, and the first thermistor element is disposed rearward of the thermistor element in a convex shape outward as viewed from the thermistor element. A second shielding plate having a width smaller than that of the shielding plate is arranged, and a second straight line connecting the end sides is arranged inside the first straight line, and is arranged so as not to contact the inner wall of the first shielding plate. It is characterized by having been done.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the thermistor wind speed detector according to the present invention will be described with reference to FIGS. The thermistor wind speed detector according to this embodiment includes a thermistor element 1, a shield plate 2 disposed around the thermistor element 1 (first shield plate disposed on the windward side), and a shield plate 3 (on the leeward side). (A second shielding plate disposed).

The thermistor element 1 shown here has electrode layers formed on both surfaces of a manganese / nickel-based oxide sintered body, is cut into chips, and the electrode layers on both surfaces and lead wires are connected to each surface. A glass tube is covered so as to cover the chip portion, and is melted and hermetically sealed.

A first shielding plate 2 protruding outward when viewed from the thermistor element 1 is disposed in front of the thermistor element 1 so as to be perpendicular to the wind direction so as to prevent particles from adhering to the thermistor element 1. Act on. At this time, the position of the thermistor element 1 with respect to the shielding plate 2 needs to be disposed inside a straight line connecting the edges of the shielding plate 2.

On the other hand, a second shielding plate 3 narrower than the first shielding plate 2 projecting outward when viewed from the thermistor element 1 is arranged behind the thermistor element 1 so as to be perpendicular to the wind direction. Is done. The shielding plate 3 has an effect of preventing particles from adhering from behind the thermistor element 1 due to the air flow disturbed at both ends of the shielding plate 2. Shield plate 3 and shield plate 2
Is required to be arranged such that the straight line connecting the edges of the shielding plate 3 is inside the straight line connecting the edges of the shielding plate 2.

With such a structure, the wind entering between the shielding plate 2 and the shielding plate 3 is in a considerably low speed region, has little energy to carry particles, and has a path. Due to the lengthening, adhesion of particles to the thermistor element 1 is almost eliminated.

The shapes of the above-mentioned shielding plates 2 and 3 may be not only substantially semi-cylindrical as shown in FIGS. 1 and 2, but also U-shape and ellipse.
In addition, as the material, metal materials such as aluminum and brass,
A resin material resistant to a solvent contained in a paint such as Teflon may be used.

When the thermistor wind speed detector having the above configuration is used for actual use, a pin terminal or the like is passed through the base 4 and the lead wire of the thermistor element 1 is connected to the base 4 while maintaining the upright state. Each of the plates 3 is fixed to the base 4 by using a mechanical means or an adhesive.

The above-mentioned thermistor element 1 is of a radial lead type in which a pair of thermistor lead wires are led out in the same direction. A similar effect can be considered with a lead type. A similar effect can be obtained by using a resin-sealed thermistor instead of a glass-sealed thermistor.

The insulation between the lead wires of the thermistor element 1 is as follows.
It is also conceivable to cover the lead wire on one or both sides with a polyimide tube, or to coat the lead wire with urethane, formal, epoxy resin or the like.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. First, reference numeral 5 denotes a pin terminal made of SUS304 that penetrates the base 4 made of nylon resin.
A pair of lead wires 1a of the thermistor element 1 is connected to the tip of the pin terminal 5 by spot welding while maintaining the upright state. The surfaces of the thermistor lead wires 1a are coated with epoxy resin, respectively, thereby ensuring insulation between the lead wires.

The thermistor element 1 is a glass-sealed type, the dimensions of the element part are 1.0 × 1.5 mm, and the outer diameter of the thermistor lead wire 1a is 0.1 mm. The characteristics are
R (0 ° C.) = 15 KΩ, B constant (0-100 ° C.) = 33
A 90K one was used.

Reference numerals 2 and 3 denote shielding plates obtained by bending an aluminum plate having a thickness of 0.5 mm into a substantially semi-cylindrical shape. Fixed. The outer diameter of the shielding plate 2 is 16
mm, and the outer diameter of the shielding plate 3 is 8 mm.

The positional relationship between the shielding plate 2, the shielding plate 3, and the thermistor element 1 is as shown in FIG. That is, the position of the thermistor element 1 is arranged so as to be inside a straight line connecting the edges of the shielding plate 2. Further, the position of the shielding plate 3 is arranged such that a straight line connecting the edges of the shielding plate 3 is inside the straight line connecting the edges of the shielding plate 2.

Here, in order to evaluate the characteristics of the wind speed detector obtained as described above, as Comparative Example 1, a shield was manufactured in the same manner as in the present embodiment except that neither the shield plate 2 nor the shield plate 3 was provided. As a comparative example 2, a wind speed detector manufactured in the same manner as the present embodiment except that the shielding plate 3 is not provided is also
Each was prepared and installed in a test wind tunnel as shown in FIG. 4 and connected to a constant temperature bridge circuit using an OP amplifier to measure initial characteristics with respect to wind speed. As shown in Table 1 and FIG. Results. according to this,
It can be seen that the wind speed detector according to the present embodiment uses a very low wind speed region.

[0021]

[Table 1]

Further, in the present embodiment, a spraying test of the paint was carried out with the airbrush shown in FIG. 4 for the above three kinds of wind speed detectors, and the degree of adhesion was measured by a value called a decrease in output voltage. However, the results shown in Table 2 were obtained.
Here, the paint is a 1: 1 diluted plastic color for model (manufactured by Gunze Sangyo, trade name: Mr. Color, White). After spraying 5 cc / time 3 times every hour, It was measured. The measured wind speed was 7.0 m / s.

[0023]

[Table 2]

Looking at the item "Convert output voltage after test to wind speed value" in Table 2, the wind speed value obtained by spraying three times is as follows. It will be about halved. In the case of only the front shield plate 2 in Comparative Example 2, the initial value is -20%. The value according to the present embodiment is extremely small at -0.4%.

As described above, it has been proved that the thermistor wind speed detector according to the present embodiment in which the positional relationship between the thermistor element and the shielding plate is devised works extremely effectively against the adhesion of paint.

[0026]

As described above in detail, according to the present invention, the shielding plate on the windward side prevents particles from contacting the thermistor element, and the shielding plate on the leeward side prevents the particles from coming into contact with the thermistor element. By preventing the particles from coming into contact with the thermistor element due to the turbulent airflow, the particles became extremely difficult to reach the thermistor element. Therefore, despite having a simple configuration, for example, even when used in the exhaust duct of the painting process or the exhaust duct of the annealing furnace for cutting metal parts, there is almost no adhesion of mist such as paint particles, and the wind speed is accurately controlled. It is possible to detect.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a perspective view of a thermistor wind speed detector.

FIG. 2 is a view showing an embodiment of the present invention, and is a top view of a thermistor wind speed detector.

FIG. 3 is a view showing the embodiment of the present invention, and is a side view of the thermistor wind speed detector in a state before a shielding plate is attached.

FIG. 4 is a diagram showing a configuration of a test apparatus used in an example of the present invention.

FIG. 5 is a graph showing wind speed-output characteristics of the thermistor wind speed detectors according to the present embodiment, comparative examples 1 and 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Thermistor element 1a ... Thermistor lead wire 2 ... First shield plate 3 ... Second shield plate 4 ... Base 5 ... Pin terminal

Claims (2)

[Claims] 1. A thermistor wind speed detector having a shielding plate disposed around a thermistor element, wherein a shielding plate on an upwind side prevents particles from contacting the thermistor element, and a shielding plate on a leeward side prevents the particles from contacting the thermistor element. A thermistor wind speed detector characterized in that particles are prevented from coming into contact with a thermistor element due to an air flow disturbed by a shielding plate on the windward side. 2. A thermistor wind speed detector in which a shielding plate is disposed around a thermistor element, wherein a first shielding plate convex toward the outside as viewed from the thermistor element is disposed, and a first shielding plate connecting end sides thereof is provided. A thermistor element is arranged in an upright state inside one straight line, and a second shielding plate narrower than the first shielding plate is provided behind the thermistor element so as to protrude outward when viewed from the thermistor element and is narrower than the first shielding plate. The thermistor wind speed detector is arranged such that a second straight line connecting the end sides is inside the first straight line and does not contact the inner wall of the first shielding plate.