JPH0317231Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to the structure of an insertion type temperature sensor that detects temperature using the oscillation frequency of a crystal oscillator and transmits the detected temperature as a data signal to a transmission line.

Traditional temperature sensors simply had the function of detecting temperature and sending it out as an electrical signal, but in recent years temperature sensors have been used to simplify system configurations and reduce the amount of wiring between air conditioning control devices. Sensors with data signal transmission/reception functions are being developed, and a "temperature sensor" (Patent Application No. 161192 filed in 1982) filed separately by the applicant is being developed.
has now been disclosed.

However, when such a temperature sensor is put into practical use as an insertion type, if the frequency of the clock pulse that regulates the operation of the conversion circuit that converts the oscillation frequency of the crystal oscillator to temperature changes depending on the ambient temperature, errors may occur in the measurement results. Therefore, there is a demand for a structure that has a simple structure and can prevent the occurrence of errors in measurement results.

The purpose of the present invention is to completely satisfy such conventional demands, and in addition to housing a crystal oscillator for temperature detection at the tip of the probe, a pulse generator for generating clock pulses is installed adjacent to the crystal oscillator for temperature detection at the tip of the probe. The present invention provides an extremely effective structure of an insertion type temperature sensor that is housed in the tip and cancels measurement errors caused by the frequency of a crystal oscillator that changes depending on the detected temperature.

Hereinafter, details of the present invention will be explained with reference to a cutaway side view of a main part showing an embodiment.

In the figure, a probe 1 is composed of a metal sleeve 2 disposed at the tip, and a pipe 4 made of phenol resin or the like connected to the metal sleeve 2 via a bushing 3. A crystal oscillator 5 for detecting temperature is housed in the oscillator 5, and a pulse generator 6, which is an integrated circuit for generating clock pulses, is housed adjacent to the crystal oscillator 5.

In this case, aluminum is used for the metal sleeve 2, and an alumite film is formed as an insulating film on the front surface to ensure heat conduction and insulation. A ring-shaped groove 2a is formed inside, into which a disk-shaped shield plate 7 made of an elastic metal such as phosphor bronze is press-fitted to prevent noise from being introduced into the interior from the opening.

Further, the lead wires of the crystal oscillator 5 are connected to the terminals 6a and 6b of the pulse generator 6, but the terminals 6a and 6b are directly connected to the terminals 6c and 6d internally, and The coaxial cable is connected to the inner conductor 8a and outer conductor 8b of the coaxial cable 8, and the power supply circuit and the common circuit are connected by the electric wire 9a connected to the terminal 6e, and the coaxial cable is connected to the terminals 6f and 6g. Clock pulses from the pulse generator 6 are transmitted through conductors 9b and 9c of 8'.

In addition, the terminal 6h is internally connected directly to the terminal 6f, the shield plate 7 is connected to the terminal 6h by the electric wire 9d, and the metal sleeve 2 and the shield plate 7 are in contact within the groove 2a. Since they are electrically connected, they are connected to a common circuit, providing a good shielding effect for the internal circuits.

However, the inside of the metal sleeve 2 and the outside of the shield plate 7 are filled with a filler 10 such as epoxy resin that has heat conductivity and insulation properties, and prevents movement of internal parts and wiring. This prevents disconnection accidents, improves heat transfer to each component, and improves responsiveness to detected temperatures.

Meanwhile, the base of the pipe 4 is screwed into the probe 1.
The casing 11 supporting the casing 11 is composed of a base 12 made of a heat insulating material such as resin and a cover 13, and screws 13a and 1 are screwed into bosses 12a and 12b formed to protrude inward from the base 12.
3b, a printed circuit board 15 equipped with an oscillation circuit combined with the crystal oscillator 5, a conversion circuit that converts the output of the oscillation circuit into temperature, a transmission circuit that transmits the output of the conversion circuit as a data signal to a transmission line, etc. The mounted printed circuit board 14 is fixed.

In addition, the coaxial cable 8 and the conductors 9b and 9c which penetrate the bushing 3 and are inserted into the vibrator 4
The coaxial cable 8' and the electric wire 9a pass through the bushing 16, the shield plate 17, and the printed circuit boards 14 and 15 provided at the boundary between the base 12 and the pipe 4, and also pass through the printed circuit boards 14 and 15.
Connection fittings 14a, 14b, 14 installed in 15
c, 15a and 15b by soldering, and the coaxial cable 8 connects the crystal oscillator 5 and the printed circuit board 15, and the coaxial cable 8' consisting of the electric wire 9a and the electric wires 9b and 9c generates pulses. The device 6 and the printed circuit board 14 are connected to each other.

However, when probe 1 is inserted into the test area,
A temperature difference occurs between the inside of the probe 1 and the inside of the casing 11, and moisture in the air moves into the casing 11 due to the breathing action through the pipe 4, causing dew condensation on the printed circuit boards 14 and 15. Since there is a risk of deteriorating the electrical characteristics, a filler 18 similar to the filler 10 is heaped up in an airtight manner at the boundary between the pipe 4 and the casing 1 to seal this area.

In addition, when inserting probe 1 into the fluid,
A stainless steel watertight pipe or the like may be attached to the probe 1, a connector or the like may be used in place of the bushing 3, and the crystal oscillator 5 and pulse generator 6
The present invention can be modified in various ways, such as the same effect even if the positions are reversed.

In addition, regarding measurement error cancellation when the crystal oscillator 5 and pulse generator 6 are installed adjacently,
Since the specific content is disclosed in the "Method for Correcting Measured Temperature" (Patent Application No. 60324 of 1982) filed separately by the present applicant, the details will be omitted.

As is clear from the above explanation, according to the present invention, measurement errors due to changes in the frequency of clock pulses in response to changes in ambient temperature are eliminated with a simple configuration, and therefore, a great effect can be obtained in insertion type temperature sensors for various uses. It will be done.

[Brief explanation of the drawing]

The figure is a cutaway side view of essential parts showing an embodiment of the present invention. 1...Probe, 2...Metal sleeve, 3...
Bushing, 4...pipe, 5...crystal oscillator,
6... Pulse generator, 14, 15... Printed circuit board.

Claims (1)

[Scope of utility model registration request] A crystal oscillator for detecting temperature, an oscillation circuit combined with the crystal oscillator, a conversion circuit that converts the output of the oscillation circuit into temperature, and a conversion circuit that transmits the output of the conversion circuit as a data signal to a transmission line. a transmission circuit;
In an insertion type temperature sensor having a pulse generator that generates clock pulses for regulating the operation of the conversion circuit and the transmission circuit, the crystal oscillator is housed in the tip of the probe, and the probe is disposed adjacent to the crystal oscillator. and the pulse generator housed in the tip of the insertion type temperature sensor.