JPH03221823A - Contactless temperature measuring equipment for centrifugal machine - Google Patents

Abstract

PURPOSE:To accurately execute the measurement of temperature by using a thermocou ple type infrared ray temperature sensor and providing heat insulating part around the temperature sensor. CONSTITUTION:In the thermocouple infrared ray temperature sensor 5, a heat receiving part 2 is heated by infrared rays 25 radiated from a rotator 15 with temperature TR opposed to the sensor 5 and a temperature difference TS between the heat receiving part 2 and a reference junction 4 is generated. The temperature difference TS is thermo electrically converted by a thermocouple 3 and the converted electric signal is outputted from the sensor 5, amplified by preamplifiers 11, 12 and outputted as voltages Va, Vb. When the inside room of the rotor 15 is made heat unbalanced state by thermal disturbance and an atmospheric temperature is changed, changes in the heat receiving part 2 and the reference junction 4 are eased by the heat insulating member 7. Since the time constant T of heat transmission of the member 7 to the a response time t1 to the incidence of infrared rays upon the sensor 5, a response time t2 to an atmo spheric temperature change in the sensor 5 and the time constant t3 of the sensor 5 is selected so that T>t1 to t3, the output Vo of an adder 13 indicates the temperature TR of the rotor 15 independently of thermal disturbance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a non-contact temperature measuring device for a centrifuge.

[Background of the invention]

A thermocouple type infrared temperature sensor generally has the configuration shown in FIG. ) 4, further transmitted to the case 26, and finally radiated to the atmosphere, achieving thermal equilibrium and creating a temperature gradient inside the temperature sensor. One or more thermocouples 3 thermoelectrically convert the slight temperature difference that occurs between the heat receiving body and the reference junction in the temperature gradient to become a voltage output signal of the temperature sensor 3, where: The temperature difference between the heat receiving body and the reference junction is less than 0.1°C when the temperature of the object to be measured is several tens of degrees, and the temperature sensor output is extremely small, about several tens of μV 1°C, and has a high output impedance. It is.

On the other hand, in a centrifugal machine, the rotor rotates at high speed in an evaporator 23 which is intermittently cooled to about -30'C in a rotor chamber 24 which has low atmospheric pressure. Therefore, the thermoelectric type infrared temperature sensor installed in the rotor chamber is exposed to thermal disturbances due to atmospheric disturbances, etc., and the thermal disturbances are transmitted through the sensor case and further transmitted to the reference junction. When the temperature gradient collapses, the sensor signal fluctuates greatly until it reaches thermal equilibrium with the new temperature gradient, and furthermore, the thermal disturbance is irregular and the temperature sensor output signal is unstable. There are some points.

The applicant has disclosed in Japanese Patent Publication No. Sho 58-32339 how to deal with thermal disturbances in the temperature measuring device of a centrifuge. Although it is intended to prevent heat radiation, it has little effect on heat transfer in the atmosphere at atmospheric pressure or low pressure, as described above. It was also necessary to suppress the conduction of thermal disturbances due to heat transfer to the temperature sensor.However, as mentioned above, since the temperature sensor has a high impedance, there is a problem that noise is easily induced.

[Purpose of the invention]

The purpose of the invention is to eliminate the drawbacks of the prior art and to enable accurate temperature measurement.

[Summary of the invention]

The present invention insulates a thermocouple type infrared temperature sensor from the atmosphere, suppresses disturbance of the thermocouple reference junction temperature in the temperature sensor due to the atmosphere, and limits heat input to infrared rays from an object to be measured. The arrangement of the heat insulating member and the conductive member is devised so as to shield the temperature sensor from induced noise.

[Embodiments of the invention]

FIGS. 1 and 2 show an embodiment of the present invention in a centrifuge.

The rotor 15 is cooled in the rotor chamber 24 by an evaporator 23 around which a cooling corrugated pipe 22 is wound, and is rotated by the motor 17. 11116 and rotates at high speed. Further, a dress cover 20 is attached to the bracket 18 via a spacer A19, and a sensor board 10 is attached above the dress cover via a spacer B21. A signal line from the sensor head is connected to an arithmetic circuit 14 outside the rotor chamber. The sensor head is composed of a thermocouple type infrared temperature sensor 1, a heat insulating member 7 covering the sensor, and a conductive member 8, and the conductive member is grounded by a grounding wire 9.

Further, the thermocouple type infrared temperature sensor faces the rotor at a predetermined position, and includes a thermocouple 3 having a heat receiving part 2 and a reference junction (cold junction) 4 outside the heat receiving part, and is provided near the reference junction. The output of the reference junction temperature sensor 5 is input to the preamplifier B12 in the arithmetic circuit 14, and similarly, the output of the thermal lightning pair is input to the preamplifier All. ing. The two preamplifiers A
, B are added together by an adder 13.

Next, the operation will be explained with reference to FIG.

In the thermocouple type infrared temperature sensor, the heat receiving part 2 generates heat due to the infrared rays 25 from the rotor having the temperature TB facing the temperature sensor, and a temperature difference Ts with respect to the reference junction 4 is generated. The temperature difference T's is thermoelectrically converted by the thermocouple 3, becomes the temperature sensor output, and is amplified by the preamplifier A to become the voltage Va. Here, when the rotor chamber is in a thermal equilibrium state, the temperature difference Ts and the voltage V'a are proportional to the temperature difference Td between the rotor temperature TR and the reference junction temperature. On the other hand, the output of the reference junction temperature sensor 5 is amplified by a preamplifier B and becomes a voltage vb. By adding and compensating the voltage vb indicating the reference junction temperature to the voltage Va indicating the temperature difference Td in an adder, the adder output voltage Vo indicates the rotor temperature Tp.

Now, due to thermal disturbance, the rotor chamber is in a state of thermal nonequilibrium as shown in Figure 3, and when the ambient temperature fluctuates as shown in Figure 3 (C), the heat insulating member causes , changes in the heat receiving part and the reference junction are alleviated. Here, with respect to the response time t□ of the thermocouple type infrared temperature sensor due to the incidence of infrared rays, the response time t2 of the temperature sensor to ambient temperature change, and the time constant t3 of the reference junction temperature sensor, the time of heat transfer of the heat insulating member is calculated. Since the constants T are selected in advance as T)tl, t2, and t3, the change in the temperature difference Ts follows the change in the temperature difference Td, and the output voltage Va of the preamplifier A changes according to the temperature difference T.
d, and the output vb of the reference junction temperature sensor can also follow the temperature change of the reference junction, so the adder output Vo indicates the rotor temperature Tpe regardless of thermal disturbances.

Moreover, the dotted line in FIG. 3 shows the state when there is no heat insulating member, and due to differences in ME th, t2, and t3, an error occurs in the voltage Vo at the time of thermal imbalance.

On the other hand, by installing a heat insulating member, the heat insulating member is affected by the electric field generated by a motor, etc. (As for the induction of noise caused by a high impedance thermocouple type infrared temperature sensor, conductive members and grounding Due to the shielding effect of the wire,
It can be prevented.

〔Effect of the invention〕

According to the present invention, thermal disturbance to the temperature sensor can be suppressed, and induced noise can also be suppressed, so that the temperature sensor output signal becomes stable and accurate temperature measurement can be achieved.

[Brief explanation of drawings]

1st construction drawing; Akamasui is a circuit diagram showing one embodiment of the present invention;
The figure is a longitudinal sectional view of a centrifuge equipped with the present invention, 2 is a heat receiving part, 3
Thermocouple 4 is a reference junction, 5 is a reference junction temperature sensor, 6 is a sensor head, 7 is a heat insulating member, 8 is a conductive member, 9 is a grounding wire, 10 is a sensor board, 11 is a preamplifier A, 12 is a preamplifier B , 13 is an adder, 14 is an arithmetic circuit, 15 is a rotor, 16 is a rotating shaft, 17 is a motor, and 18 is a bracket 1.
-19 is a spacer A, 20 is a dress cover, 21 is a spacer B, 22 is a cooling tube, 23 is an evaporator, 24 is a rotor chamber, 25 is an infrared ray, and 26 is a case.

Claims (1)

[Claims] 1. A non-contact temperature measuring device for a centrifuge, characterized in that a thermocouple-type infrared temperature sensor is used and a heat insulating member is provided around the temperature sensor. 2. The non-contact temperature measuring device according to claim 1, characterized in that a conductive member is provided around the temperature sensor, and the conductive member is grounded.