JPH0632619Y2 - Ultrasonic sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an ultrasonic sensor for measuring gas concentration, which is used in ultrasonic devices for measurement and control.

[Prior art]

The inventors of the present invention have previously invented a gas concentration measuring device using ultrasonic waves, and have disclosed that in Japanese Patent Laid-Open Nos. 55-4528 and 61.
-269061. This device is a device that measures the concentration of a mixed gas or a single-component gas by utilizing the dependence of the ultrasonic wave propagation velocity on the measured gas concentration, and the ultrasonic sensor part thereof will be described in some detail with reference to the drawings.

FIG. 2 is a cross-sectional view of an ultrasonic transmitter and a receiver that constitute an ultrasonic sensor. The ultrasonic element (41) is attached to a metal or plastic holder (42) with an adhesive or the like. The two cables (43) coming out of the ultrasonic element (41) are connected to two terminals (45) respectively, and the terminals (45) are connected to the cable (50) and pulled out of the block (49). Has been. The substrate (47) is adhesively fixed to the inner wall of the holder (42) and holds the terminal (45). Also, substrate (48)
Serves as a retainer between the block (49) and the holder (42). Between the board (47) and the board (48), between the holder (42) and the block (49), and between the block (49) and the cable (50),
Encapsulate with an encapsulant (51) such as silicone resin or epoxy resin,
This prevents moisture from entering the ultrasonic element (41).

FIG. 3 is an overall view showing the external appearance of an ultrasonic sensor having the ultrasonic transmitter and receiver of the structure shown in FIG. 2 fixed to both ends. The ultrasonic transmitter and the receiver are face-to-face and appropriately fixed to the holding table (52) with screws or the like. A cable (53) is output from each of the ultrasonic transmitter and the receiver and is connected to the arithmetic processing unit. The space where the ultrasonic transmitter and the receiver face each other serves as the ultrasonic path portion. The ultrasonic path portion is covered with a mesh (54) in order to eliminate the influence of the gas concentration bias in the ultrasonic path portion, the influence of air flow, etc., and to make the concentration uniform. The mesh (54) is made of metal, plastic or the like. Also, attach a temperature sensor (55) consisting of a thermocouple, thermistor, etc. to the ultrasonic transmitter or receiver,
The temperature measuring unit is installed at or near the ultrasonic path unit, and the temperature cable (56) is connected to the arithmetic processing unit.

In use (measurement), this sensor is placed in the atmosphere of the gas to be measured. For example, in the case of a CO ₂ incubator, it will be installed for a long time under high temperature and high humidity conditions, so the sensor will malfunction. However, since the sensor is an open system, it has a drawback that it cannot be used for measuring the concentration of harmful gas or when the amount of gas to be measured is small.

[Purpose of device]

The present invention solves these problems of the conventional ultrasonic sensor, and can be used when the amount of gas to be measured is small or for measuring the concentration of harmful gas. The object is to provide an ultrasonic sensor that is excellent and has few failures.

[Constitution of device]

That is, the present invention provides a fluid (gas to be measured) passage that penetrates through a block made of metal, a heat exchange passage that is built in the block for equalizing the temperature of the block and the temperature of the fluid, and the passage of the fluid. A through hole that is provided across and has an inner wall surrounded by a mesh and that includes an ultrasonic path portion. An ultrasonic transducer is fixed in a holder attached to a substrate, and both ends of the through hole are mutually An ultrasonic sensor for measuring gas concentration, comprising: an ultrasonic wave transmitting unit and an ultrasonic wave receiving unit, which are installed face to face, and a temperature sensor for measuring the temperature of a fluid in a block.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of an ultrasonic sensor according to an embodiment of the present invention, (a) is a front view, (b) is a side view, and (c) is a top view. The ultrasonic transducer for wave transmission (1) and the transducer for wave reception (2) are attached to the inside of the holder (4) with an adhesive, and are connected to the terminal (5) by the cable (3). , Further connected to the arithmetic processing unit. holder
(4) is made of a material such as metal or plastic, and is fixed to the substrate (6) by an appropriate method such as adhesion or soldering.In the holder (4), silicone resin, epoxy resin, etc. are placed. Enclosed to prevent moisture from entering. The board (6) with the holder (4) attached is blocked as shown in Fig. 1 (a).
It is fixed to (7) by a suitable method such as a screw. In addition, an O-ring groove (9) is attached to the block to prevent water from entering the ultrasonic path section (8) through the gap between the block (7) and the substrate (6).
A ring (10) is preferably provided to provide a seal between the block (7) and the substrate (6). The block (7) is made of a metal having excellent corrosion resistance such as aluminum and stainless steel, and usually has a substantially cubic shape with one side of 50 to 80 mm, but is not limited to this.

Inner wall of the through hole (8) with ultrasonic transducers (1) and (2) attached to both ends and containing the ultrasonic path part, especially the gas passage to be measured
A part intersecting with (11) is surrounded by a mesh (13). The gas to be measured passing through the gas passage (11) hits the mesh (13) and diffuses into the through hole (8), so that the concentration in the through hole (8) can be made uniform. The mesh (13) is made of a material having excellent corrosion resistance such as stainless steel, aluminum and plastic.

By providing nipples and the like at the inlet and outlet of the gas passage (11) and connecting them to tubes, pipes, etc., even if the amount of gas to be measured is very small. It is possible to measure if there is an amount enough to pass through the gas passage (11) and the through hole (8), and even if the gas to be measured is a harmful gas, the block (7) and the substrate
Since the O-ring (10) is closed between (6), the measured gas does not leak to the outside from the block (7), and the measurement can be performed safely.

Further, in order to eliminate the influence of temperature on the ultrasonic wave propagation velocity, the temperature of the gas to be measured is measured and temperature compensation is performed. The temperature may be measured at one location, but in order to eliminate the influence of the non-uniformity of the temperature of the gas to be measured due to the position in the block, it is desirable to use a plurality of temperature sensitive parts to average the measured values.
Install the temperature sensor temperature sensor in the gas passage (1
1), the through hole (8), or both of them are preferably near the ultrasonic path portion. The ultrasonic path part is the space between the two ultrasonic transducers (1) and (2) facing each other.
Since it is located in the central portion of (8), when the temperature sensing portion of the temperature sensor is provided in the through hole (8), it is provided at a position close to the inner wall of the through hole (8). A thermistor, a resistance temperature detector, a thermocouple, etc. can be used as the temperature sensor.

Further, in order to eliminate the temperature difference due to the positions of the gas passage (11) and the through hole (8) in the block (7), it is desirable to make the temperature of the block (7) and the temperature of the gas to be measured uniform. For that purpose, it is effective to provide a heat exchange passage in the metal block (7) and pass the heat exchange passage before the gas to be measured enters the passage (11). The heat exchange passage (15) in FIG. 1 shows an example in which it is continuously provided along the ridgeline of the block (7), but the route of the heat exchange passage is averaged in the block (7). It is not particularly limited as long as it is distributed over time. By this method, the difference between the temperature of the gas to be measured and the temperature of the block (7) can be reduced, and the temperature distribution in the block (7) can be eliminated.

[Effect of device]

According to the present invention, since the ultrasonic sensor is a closed system, it is only necessary to introduce the gas to be measured into the ultrasonic path during measurement, so it can be used even when the amount of gas to be measured is small. Since it is not necessary to expose the whole to a gas atmosphere of high temperature and high humidity, it is possible to prevent breakdowns and deterioration of measurement accuracy, and even if the measured gas is a harmful gas, the gas may leak to the outside. Since the gas concentration can be measured safely, it is possible to provide an ultrasonic sensor for gas concentration measurement that is extremely useful in industry.

[Brief description of drawings]

FIG. 1 is a sectional view of a central portion of an ultrasonic sensor according to an embodiment of the present invention, (a) is a front view, (b) is a side view, and (c) is a top view. FIG. 2 is a cross-sectional view of an ultrasonic transmitter and a receiver constituting a conventional ultrasonic sensor, and FIG. 3 is an overall view showing the appearance of the conventional ultrasonic sensor.

Claims (3)

[Scope of utility model registration request] 1. A passage for a fluid (gas to be measured) which penetrates through a metal block, a heat exchange passage for equalizing the temperature of the block and the temperature of the fluid, which is built in the block, and a passage for the fluid. The ultrasonic transducer is fixed in a through hole that is provided across and has an inner wall surrounded by a mesh that encloses the ultrasonic path portion and a holder attached to the substrate.
A gas concentration characterized by comprising an ultrasonic wave transmitting portion and an ultrasonic wave receiving portion, which are installed at opposite ends of the through hole so as to face each other, and a temperature sensor for measuring the temperature of the fluid in the block. Ultrasonic sensor for measurement. 2. A utility model registration claim, wherein the temperature sensor has one or a plurality of temperature-sensing parts provided in the fluid passage and / or the through hole.
An ultrasonic sensor for measuring gas concentration according to item (1). 3. A utility model registration claim (1) or ((3), characterized in that the block has a built-in heat exchange passage for equalizing the temperature of the block and the temperature of the fluid. An ultrasonic sensor for measuring gas concentration according to the item 2).