JPH0536499Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a constant temperature chamber that houses objects that need to be kept at a constant temperature, including gas analyzers.

(Prior Art) A magnetic wind type oxygen meter is an example of a measuring device that needs to maintain a constant temperature. Magnetic wind oxygen meters are specified in JISB7983.

As shown in FIG. 4, the measurement chamber 1 of the magnetic wind type oxygen meter is housed in a constant temperature bath 2, and the temperature inside the constant temperature bath 2 is controlled by a heater 3 and a temperature sensor 4. The temperature inside the thermostat 2 is detected by the temperature sensor 4, and the temperature in the thermostat 3 is detected by the temperature control unit 5.
The energization is controlled on and off, and the temperature inside the thermostatic oven 2 is kept constant. Reference numeral 6 denotes an amplifying section that amplifies the detection signal of the measurement chamber 1 and outputs the amplified signal.

Figure 5A shows a constant temperature chamber 2 containing the measurement chamber 1.
Figure B is a sectional view of the thermostatic chamber viewed from the front.

The side chamber 1 is provided with magnets 1a and 1b. Since the measurement chamber 1 is not directly related to the present invention, detailed explanation thereof will be omitted here.

A measurement chamber 1 as an object for keeping the temperature constant is provided in the center of a constant temperature bath 2, and a plate-shaped heater 3 is provided around the measurement chamber 1. The temperature sensor 4 is provided near the measurement chamber 1 where temperature accuracy is most required.
The outside of the constant temperature chamber 2 is entirely surrounded by a heat insulating material, and the constant temperature chamber 2 is an air bath type constant temperature chamber.

This constant temperature bath is a constant temperature bath for a magnetic wind type oxygen meter, but constant temperature baths with a similar structure are also used in other measuring meters.

(Problem that the invention attempts to solve) When electricity is started using such a constant temperature bath,
A temperature overshoot occurs as shown at A in FIG. This is because the heater 3 and sensor 4 are located far apart, so the heat from the heater 3 is difficult to transfer.
This is because by the time the temperature of the sensor 4 reaches the temperature set for temperature adjustment, the temperature of the heater 3 will reach about 1.5 to 2 times the set temperature. For example, if the temperature control temperature is 60℃, the temperature near heater 3 is 90℃.
The temperature can reach ~120℃.

If the overshoot is too large, it will take time for the temperature to reach the set temperature, which will not only lengthen the warm-up time of the analyzer, but also cause damage to the parts used in the thermostatic chamber due to the heat. There is. However, using heat-resistant parts increases costs.

One possible way to reduce the overshoot is to reduce the capacity of the heater 3, but in that case it takes even longer to warm up. Furthermore, in order to quickly transfer the heat from the heater 3 to the sensor 4, it is conceivable to install an air agitation fan in the thermostatic chamber 2, but this increases the size of the thermostatic chamber 2 and increases the cost. Furthermore, maintenance becomes troublesome because the fan must be replaced periodically.

The present invention has a simple structure that does not increase costs, and aims to reduce temperature overshoot, shorten warm-up time, and prevent damage to parts due to heat.

(Means for solving the problem) To explain with reference to FIG. 1A showing an embodiment, in the constant temperature oven of the present invention, the temperature sensor 4 for controlling the energization of the heating element 3 is used for temperature adjustment. It was supported by a support member 10 made of a shape memory alloy having a transformation temperature slightly lower than the set temperature, and the temperature sensor 4 was movable between the vicinity of the heating element 3 and the vicinity of the object 1.

(Example) FIG. 1A is a sectional view of an example seen from the top side.
Figure B is a sectional view seen from the front side.

2 is a constant temperature bath, 2a is a lid of the constant temperature bath, and these are surrounded by a heat insulating material (not shown). A measurement chamber 1 is installed in the center of the constant temperature bath 2, and a plate-shaped heater 3 is provided around the measurement chamber 1. These arrangements are the same as the conventional one shown in FIG.

A temperature sensor 4 for temperature control is attached to the tip of a support member 10 made of a shape memory alloy, and the base end of the support member 10 is fixed near the measurement chamber 1. A coil spring 11 is provided at the tip of the support member 10, and the coil spring 11 is attached to the plate heater 3. Support member 1
0 is stretched by a coil spring 11, and its tip is biased in a direction toward the plate heater 3.

The support member 10 has a transformation temperature slightly lower than the temperature control temperature set to keep the temperature inside the constant temperature bath 2 constant. To explain specifically, the temperature control temperature in the thermostatic chamber 2 is set to 60°C, for example, and the support member 1 is
The transformation temperature of the zero shape memory alloy is 59°C. When the temperature of the support member 10 is less than 59°C,
As shown in FIG. 2, it is stretched by the spring 11, but when the temperature exceeds 59° C., it deforms and contracts as shown in FIGS. 2A and B.

Next, the operation of this embodiment will be explained.

The explanation will be given assuming that the controlled temperature is 60°C and the transformation temperature of the shape memory alloy of the support member 10 is 59°C. At room temperature, the support member 10 is stretched by the spring 11, and the temperature sensor 4 is located near the heater 3, as shown in FIGS. 1A and 1B. In this state, heater 3
When energization is started, the temperature near the heater 3 is detected by the temperature sensor 4, and the temperature is controlled so that the temperature near the heater 3 is 60°C. At this time, the area near the measurement chamber 1 and the support member 10 is far away from the heater 3, and the temperature has not reached 59°C, so the area near the heater 3 is in the state shown in FIG. 1A and B.
Temperature control continues at 60℃.

Then, the heat of heater 3 gradually increases to measurement chamber 1.
is transmitted to the vicinity of the support member 10, and the support member 10
When the temperature near 59°C, the support member 10 changes to
It is contracted as shown in B, and the temperature sensor 4 is moved into the vicinity of the measurement chamber 1. The temperature sensor 4 has moved to a position of 59°C, which is the temperature control temperature of 60°C.
Since the temperature is lower than that, the temperature control circuit works and heater 3
The temperature is controlled so that the temperature near the measurement chamber 1 is 60°C.

What is indicated by symbol B in FIG. 3 is the temperature detected by the temperature sensor 4 according to this embodiment.

(Effect of the invention) In the constant temperature oven of the invention, the temperature sensor for controlling the energization of the heating element is supported by a support member made of a shape memory alloy that has a transformation temperature lower than the set temperature for temperature adjustment, and this temperature sensor generates heat. It is possible to move between the vicinity of the body and the vicinity of the object. Since the temperature sensor is located very close to the heater when power is started, heat is immediately transferred to the temperature sensor, minimizing overshoot to 10℃ or less, preventing component damage due to abnormal overshoot. It is possible to shorten the warm-up time.

When measuring with an analyzer, the temperature sensor is moved to the vicinity of the object where temperature accuracy is most needed, so accurate temperature control is performed and the measurements made by the analyzer are accurate.

In addition, when the thermostatic oven is in a temperature controlled state and the lid of the thermostatic oven is opened for adjustment or inspection, in conventional thermostatic ovens, the sensor is exposed to the outside air and the temperature drops, which may cause the heater to generate abnormal heat. However, in the thermostat of the present invention, when the lid is opened, the shape memory alloy support member is cooled down, the temperature sensor moves to the vicinity of the heater, and the temperature is adjusted at that position, so the heater does not generate abnormal heat. Another advantage is that adjustments and inspections can be made without turning off the power to the heater.

[Brief explanation of the drawing]

Figure 1A is a cross-sectional view of one embodiment viewed from the top side at a temperature below the transformation temperature of the shape memory alloy; Figure 1B
2A is a cross-sectional view of the same example as seen from the front side, FIG. Figure 3 is a waveform diagram showing the operation of the present invention and a conventional constant temperature chamber, Figure 4 is a block diagram showing a magnetic wind type oxygen meter, and Figure 5 A is a conventional constant temperature chamber. A cross-sectional view of the tank as seen from the top side, and FIG. 1B is a cross-sectional view as seen from the front side. 1...Measurement chamber, 2...Thermostat, 2a...
Lid, 3...Plate heater, 4...Temperature sensor,
10... Shape memory alloy support member, 11... Coil spring.

Claims (1)

[Scope of utility model registration request] In a constant temperature chamber containing an object to be maintained at a constant temperature, including a heating element and having an exterior wrapped with a heat insulating material, a temperature sensor for controlling energization of the heating element is provided with a shape having a transformation temperature lower than the constant temperature. A constant temperature bath, characterized in that the temperature sensor is supported by a support member made of a memory alloy and is movable between the vicinity of the heating element and the vicinity of the object.