JPH0439576Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention discloses the fluid velocity in an apparatus for measuring the flow velocity of various liquids and gases, or the moving velocity of particles and powder, as disclosed in Japanese Patent Application No. 59-207780. Concerning improvement of measurement probes.

[Conventional technology]

The above technology utilizes the property that the resistance value of germanium decreases according to a fixed function when a certain temperature range is exceeded.A small piece of germanium single crystal is used as a sensor, and a current is passed through it to raise the temperature to a constant temperature. By bringing the heated sensor into contact with a fluid, the temperature of the sensor changes in response to changes in the speed of the fluid, and the resistance value changes. The current, which changes as the resistance of the sensor changes, measures fluid velocity by measuring voltage or power.

As shown in Fig. 2, the probe used in this device has a lower surface of the sensor a made of a small piece of germanium single crystal, and a support made of an insulating material and a material with poor thermal conductivity, which has an end surface that is approximately the same as that of the sensor a. It is fixed to the upper surface of support b using an adhesive or the like, and lead wires d and e are fixed to both sides of support b by vapor deposition or the like,
The lower end of this support b was erected on the upper surface of an electrically insulating base c having a thickness sufficient to withstand the force of the fluid.

[Problems with conventional technology]

The above probe solved the problems of hot wire anemometers, but as a result of various experiments and research to further improve accuracy, we discovered the following points that should be improved. That is, the probe has high thermal conductivity because the joint surface between support b and column c is large, and the heated heat of sensor a is conducted to column c via support b, causing the temperature of sensor a to decrease. As the flow rate increases, the resistance value, power consumption, and heat generation value increase, resulting in measurement errors.In addition, when measuring the fluid velocity from below, struts c and supports b get in the way, resulting in measurement errors. was occurring.

In view of these problems, the present invention provides a probe for measuring fluid velocity that minimizes the contact area between the sensor and the support, does not conduct the heat of the sensor to members such as the support, and has no significant measurement errors in all directions. shall be.

[Means for solving problems]

In order to achieve the above object, the fluid velocity measurement probe of the present invention includes two pillars made of a good electrical conductor that are set apart from each other on the top surface of a base, and a good electrical conductor that is fixed at a suitable position on the pillars. A sensor consisting of a metal wire consisting of a small piece of single crystal germanium fixed between the metal wires, and a voltage applied to the sensor to measure the resistance value of the sensor which changes with temperature change due to contact with a fluid. It is characterized by converting it into changes in current, voltage, or electric power and measuring the velocity of the fluid.

[Effect]

As mentioned above, since the sensor is fixed between the two pillars with a metal wire that is a good electrical conductor, the contact area between the pillar and the sensor is simply the metal wire interposed between them, and the heat from the sensor is transferred to the pillar. It almost completely prevents the fluid from escaping, has a low heat capacity, improves the thermal response speed, and eliminates the need for any parts to obstruct the passage of the fluid, preventing turbulence caused by parts other than the sensor, and increasing the fluid velocity. Errors in the measurements can be extremely small and the outer surface of the sensor can be positioned in all directions, making it possible to measure the velocity of the fluid from all angles.

〔Example〕

The fluid measurement probe of the present invention will be explained based on the drawings described in Examples.

In the figure, reference numeral 1 denotes a rectangular parallelepiped sensor made of a single crystal of germanium. Metal wires 2A and 2B made of a good electrical conductor are drawn out by vapor deposition from the upper and lower end surfaces of this sensor 1. It is fixed to the two pillars described later by vapor deposition or the like.

The metal wire used here may be made of a good conductor such as gold or silver, but it is most desirable to use strong platinum or tungsten when the fluid velocity is high or the fluid is highly viscous. Further, the sensor 1 may have various shapes such as spherical and cylindrical.

3A and 3B are pillars, and two cylinders made of metal such as stainless steel with high conductivity and low possibility of corrosion are erected on the base 5, and the ends 4 of each other are attached at appropriate places on the pillars.
A and 4B are bent so that they are aligned on a vertical line to form bent parts 3a and 3b, and the metal wire 2A is stretched in a straight line on the end 4A of the bent part 3a and soldered or conductive. The metal wire 2B is fixed to the end portion 4B of the other bent portion 3b in the same manner as the metal wire 2A was fixed to the end portion 4B of the other bent portion 3b. However, the struts 3A and 3B may be of any type as long as they are not deformed or damaged by fluid, and their length, thickness, etc. are not particularly limited. Here is an example of a fluid velocity measurement probe that the inventor experimented with: Sensor 1 has a rectangular parallelepiped shape of 0.3 mm x 0.3 mm x 1.0 mm, and strut 3A has a diameter of 0.5 mm and a length of 8.5 mm. 3B with a diameter of 0.5 mm and a length of 6.5 mm was used, the fluid was air, and the speed was 0 to 40 m/sec. No abnormality was observed.

The base 5 is used to fix the measurement main body described above, and is attached to an experimental device for measuring fluid velocity, or is installed in a device when measuring outdoors, and its shape depends on the measuring device. Not limited as it is determined.

Therefore, fluid velocity can be measured using the fluid velocity measuring probe according to the present invention by applying a voltage between the pillars 3A and 3B, and by constructing a closed circuit consisting of the pillar 3A → metal wire 2A → sensor 1 → metal wire 2B → pillar 3B. When a current flows through the circuit, the sensor 1 generates resistance heat 1 and is raised to the measurement reference temperature.This measurement reference temperature is lowered by contact with the fluid, and the resistance of the germanium single crystal increases, causing a potential change at both ends of the sensor 1. This is achieved by measuring the Here, sensor 1 and column 3A,
Since the only inclusions between 3B are the metal wires 2A and 2B, almost no heat from the sensor 1 set at the measurement reference temperature escapes to the outside, preventing measurement errors and reducing heat capacity and thermal response. My sexuality has improved tremendously. In addition, regarding the direction of the fluid, since only the metal wires 2A and 2B are placed near the sensor 1, it is possible to react sensitively to fluid sprayed from all directions. An omnidirectional fluid velocity measurement probe can be provided.

[Effect of idea]

Since the fluid velocity measurement probe according to the present invention has only a metal wire as the member that directly supports the sensor, it prevents the heat of the sensor from escaping to the support column, reduces fluid velocity measurement errors, and has a small heat capacity. It was possible to provide an omnidirectional fluid velocity measuring probe with good thermal response and by arranging the outer surfaces of the sensor to face each other in all directions.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of a probe for measuring fluid velocity according to the present invention, and FIG. 2 is a front view of a conventional example. 1...Sensor, 2A, 2B...Metal wire, 3A,
3B... Support, 5... Base.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. Two pillars made of a good electrical conductor that are erected on the top surface of a base at a distance from each other, a metal wire made of a good electrical conductor that is fixed in place on the pillar, and the metal wire. A sensor consisting of a small piece of single-crystal germanium fixed in between; and a voltage is applied to the sensor to change the resistance value of the sensor, which changes with temperature changes due to contact with a fluid, to changes in current, voltage, or electric energy. Converted,
A fluid velocity measurement probe that measures the velocity of a fluid. 2. The probe for fluid velocity measurement according to claim 1, wherein the sensor is formed into a rod shape, and both longitudinal ends of the sensor are fixed to metal wires.