JPH0816568B2 - Thermal shock tester - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

This invention cools a low temperature tank with a refrigerator and controls the temperature to a set temperature by a temperature control heater. In the cooling device, the amount of frost adhered to the refrigerator for measuring the amount of frost adhered to the refrigerator. The present invention relates to a measuring device. The present invention also relates to a thermal shock tester for performing a low temperature exposure test and a high temperature exposure test on an object to be tested.

[Prior art]

In the conventional cooling device, the low temperature tank is always cooled by the refrigerator, the temperature of the low temperature tank is detected by the temperature sensor, and the PID calculation is performed based on the detected value and the set temperature to calculate the control amount. Then, the temperature control heater provided in the low temperature tank is heated according to the control amount to control the low temperature tank to the set temperature. In such a cooling device, if frost adheres to the refrigerator, the refrigerating capacity decreases, so defrosting is performed when the amount of frost reaches a certain level. Conventionally, an operator of the cooling device determines the time to perform this defrosting by visually observing the state of frost adhesion. In that case, it is good if the frost is visible, but if the frost is hidden and not visible, the operator decides based on experience by comprehensively considering the operating time of the refrigerator and the ambient temperature. .

[Problems to be Solved by the Invention]

Whether or not to perform the conventional defrosting depends on the operator's judgment exclusively, which imposes a burden on the operator and requires skill, and when the cooling device is operated in the absence of the operator, It became impossible to perform proper defrosting, which hindered driving. Also, if defrosting is performed at regular intervals,
Refrigerators generally have large differences in solids and aging, so a fixed amount of frost does not adhere to them at regular intervals.
If the frost deposition rate is fast, the defrosting work is delayed, and during that time, the refrigerating capacity is reduced and energy is wasted.If the frost deposition rate is slow, the defrosting work is too fast, resulting in unnecessary labor. As time is consumed, the operating efficiency of the refrigerator becomes poor. Therefore, it is possible to automatically display the frost adhesion state, but there is a problem that there is no suitable method for quantifying the frost adhesion state. The present invention has been made in view of the above circumstances, and an object thereof is to obtain a thermal shock tester that can output an appropriate defrosting request signal.

[Means for Solving the Problems]

In the present invention, when the preset temperature is controlled after precooling to a predetermined precooling temperature, the reference value of the margin time from the time when the precooling temperature is reached until the control of the preset temperature is started, and the control amount The reference values of the above are set, and these reference values are compared with the actually sampled margin time and control amount, and a defrost request signal is output according to the comparison result, or the above two reference values are set. I am trying to update.

[Work]

In the case of the present invention, the reference value of the allowance time and the reference value of the control amount are updated to perform self-learning, and finally the two reference values settle to ideal values, and appropriate values are set based on this. The defrosting request signal is output at various timings.

【Example】

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a low temperature tank, 2 is a refrigerator for constantly cooling the low temperature tank 1, 3 is a temperature control heater provided in the low temperature tank 1, 4 is a temperature sensor for detecting the temperature in the low temperature tank 1, 5
Is an A / D converter that converts the temperature detected by the temperature sensor 4 into digital temperature data, 6 is a PID control calculation unit that calculates a control amount based on the temperature data and the set temperature, and 7 is the calculated control D / A converter for converting the amount into an analog control amount, 8 is a heater drive circuit for energizing the temperature control heater 3 according to the analog control amount, and 9 is required for operating the set temperature and other cooling devices. A keyboard controller 10 for inputting various data, and a keyboard controller 10 for sending the input data from the keyboard 9 to the PID control calculation unit 6. Reference numeral 11 indicates the amount of frost adhered in the low temperature tank by performing a calculation process described later based on the temperature data obtained from the A / D converter 5 and the data such as temperature and control amount obtained from the PID control calculation unit 6. Frost adhesion amount calculation unit for calculating
A memory in which predetermined data to be described later for calculating the frost adhesion amount obtained in 11 is stored, 13 is a display controller to which the current frost adhesion amount data obtained in the frost adhesion amount calculation unit 11 is supplied, 14 Is a display device which is controlled by the display controller 13 to display the current frost adhesion amount, and 15 is a timer used in the PID control calculation unit 6. Next, the operation will be described. The temperature detected by the temperature sensor 4 is converted into temperature data by the A / D converter 5, and this temperature data is transferred to the PID control calculation unit 6
Sent to The PID control calculation unit 6 determines the PID based on this temperature data and the set temperature input from the keyboard 9.
The control amount MV is calculated by performing the calculation. The control amount MV is converted into an analog amount by the D / A converter 7 and then supplied to the heater drive circuit 8. The heater drive circuit 8 energizes and heats the temperature control heater 3 at a time corresponding to the control amount. As described above, the normal PID control is performed and the low temperature tank 1 is maintained at the set temperature. Next, a method of creating data for calculating the frost adhesion amount with respect to the temperature stored in the memory 12 will be described. (1) First, the refrigerator 2 is sufficiently defrosted so that the frost adhesion amount is zero. (2) Next, a certain temperature T ₁ is set by the keyboard 9, the PID control described above is performed in a sufficiently stable state, and the control amount MV obtained during the control is sampled at 1 second intervals. (3) Since the sampled value varies, the sum V _S01 of the controlled variables is obtained by integrating the sampled values for 1 minute in order to obtain the time average, and this is stored as the standard controlled variable MV _S01 for the zero frost deposition amount. Remember and put in 12. (4) above (1) performed for the temperature T ₁ to Tn working to (3), stores each (sum of the controlled variable) Standard control amount MV _S01 ~MV _S0n. The set temperatures T _{1 to} Tn are changed in steps of 5 ° C. By the steps up to this point, the relationship between the setting in the frost deposition amount zero temperature T ₁ to Tn and the standard control amount MV _S01 to MV _S0n are obtained. (5) Next, 1 g (gram) of frost is forcibly attached to the refrigerator 2. This is done by defrosting, then thoroughly drying and then spraying with air containing 1 g of water. (6) When 1 g of frost adheres to the above (1)
~ Perform the same work as (4). As a result, the sum MV _{S11 of the} control amounts for the set temperatures T _{1 to} Tn in the frost adhesion amount of 1 g
~ MV _S1n is stored. (7) Next, the amount of frost adhering is changed from 2 g to 1 g, and the same work as (6) above is repeated for each amount of frost adhering. According to the above, the frost deposition amount 0～Mg, each control amount of the sum _{MV S01 ~MV S0n, MV S11 ~MV} S1n ··· MV Sm1 ~MV
_Smn is obtained for each of the set temperatures T _{1 to} Tn and is registered in the memory 12. From this, at a certain j-th set temperature Tj, it is possible to know the sum MV _Sij of the control amounts when the frost adhesion amount is ig. Therefore, for all the set temperatures T _{1 to} Tn, the least squares method is used to calculate constants αj, βj, γj such that i = αj + βjMVsij + γjMVsij ² (1), and the memory 12
Register with. Based on each data created as described above and registered in the memory 12, the current frost adhesion amount can be known as follows. (1) During operation of the refrigerator 2, the control amount MV obtained from the PID control calculation unit 6 is sampled at every 1 second in the frost adhesion amount calculation unit 11, and the sample value is integrated for 1 minute to sum the control amounts MSVij Calculate and put. (2) A temperature equal to or closest to the current temperature indicated by the temperature data obtained from the temperature sensor 4 is obtained from T _{1 to} Tn, and the corresponding MV _Sij is used to calculate the frost adhesion amount i using the above equation (1). calculate. (3) The calculated value of i is displayed on the display device 14. If you perform the work of (2) and (3) above every minute,
The amount of frost adhered can be constantly monitored. In the embodiment of the present invention described above, the control amount given to the temperature control heater 3 is used as a parameter for quantifying the adhesion of frost. That is, at the same set temperature, when the control amount is lower than when the frost adhesion amount is zero immediately after defrosting, it is assumed that it is due to the decrease in the refrigerating capacity of the refrigerator 2 due to the frost adhesion. ing. Next, a second embodiment of the present invention when the cooling device is used in a thermal shock tester will be described. The thermal shock tester is composed of a test tank containing the DUT, a low temperature tank that sends cold air cooled by a refrigerator to the test tank, and a high temperature tank that sends hot air heated by a heater to the test tank. . Then, a low temperature exposure test and a high temperature exposure test of the test object are performed by alternately sending cold air and hot air into the test tank for a predetermined time. FIG. 2 shows the temperature change characteristic p in the test tank and the temperature change characteristic q of the low temperature tank during the test. In Fig. 2, the temperature of the test tank is T ₁ when exposed to high temperature.
And T ₂ during low temperature exposure. When performing high temperature exposure, the low temperature tank will have a prescribed pre-cooling temperature T ₃ (<
Pre-cooling is performed at T ₂ ), and this pre-cooling promptly sets the target temperature T ₂ when the high-temperature exposure changes to the low-temperature exposure.
Trying to reach. Further, when the low temperature exposure is completed and the precooling is started, the temperature of the low temperature tank gradually decreases from T ₂ and reaches T ₃ at point A. Then, when the high temperature exposure is finished and the low temperature exposure is started from the point B, the temperature of the low temperature tank rises promptly, overshoots the target temperature T ₂ once, and then settles at T ₂ . Here, it is referred to as a margin time period t _a from the point A to point B, the margin time t _a, the larger the amount of adhering frost cryostat shortened. That is, when the amount of frost adhered is large, the cooling capacity of the refrigerator decreases, and therefore the time from the start of precooling to the point A becomes long. In the second embodiment, the frosting state of the low temperature tank in such a thermal shock tester is judged and a defrosting request signal is output at an appropriate timing. As the thermal shock tester, a test tank and a high temperature tank may be added to the low temperature tank 1 shown in FIG. 1, and other circuit blocks may have the same structure. However, the illustration and description of the control of the high temperature tank and the like are omitted. Next, the operation of the frost adhesion amount calculation unit 11 in such a thermal shock tester will be described with reference to the flowchart of FIG. First, at step ST1, the reference value t of the margin time t _a the aforementioned
and _b, and the lower limit value t _c of the shortest margin time t _a, PID control calculation unit 6
The reference value MV _b of the control amount MV calculated in step 1 is set to a size that is empirically considered to be appropriate. Next, step ST2
The refrigerator 2 is operated to cool the low temperature tank 1. And
By step ST3, the current margin time t _a during cooling
And the current controlled variable MV _a are detected. These values MV _a are time-averaged sampled values. Then step
In ST4, it is determined whether or not the detection in step ST3 is the first detection immediately after defrosting the low temperature tank 1. If not first detection, the process proceeds to step ST5, where the comparing the detected value t _a and the reference value t _b. If t _a <t _b, the defrosting request signal is output in step ST ₆ and then the process returns to step ST 2. The defrost request signal, the display device 14,
Displayed visually or audibly. If not t _a <t _b , the process proceeds to step ST7, where the detected value MV _a and the reference value MV _b.
Compare with If MV _a <MV _b , _a defrost request signal is output in step ST6, and if MV _a <MV _b , the process proceeds to step ST8. Here, the detected value t _a and the lower limit value t _c are compared, t _a>
If t _c , the process returns to step ST2, and if not t _a > t _c , the process proceeds to step ST9. Here tighter criteria margin time and the control amount, i.e., after changing the t _b and MV _b together so as to increase by a predetermined amount, the flow returns to step ST2. Immediately after the defrosting request signal is output in step ST6 and the defrosting operation of the low temperature tank 1 is performed accordingly, the determination in step ST4 is YES.
Continue to ST10. Here, it is checked whether the factor of the defrost request signal issued immediately before is due to t _a > t _b or MV _a <MV _b , and whether the factor is removed by performing defrosting. Find out. Step if factor is removed
If ST5 and the subsequent steps are executed and the cause is not removed, the process proceeds to step ST11. Here, it is assumed that the standard used up to that point is too tight, and the standard value depends on the above factors.
Loosen t _b or MV _b (both depending on the case). That is, the size is changed by a predetermined amount. According to the above, when the reference values t _b and MV _b are reduced in step ST11, accordingly, step ST5 and step ST7
Also in the determination of, even if the detected values t _a and M _Va are small, the process proceeds in the direction of NO. Therefore, t _a, MV _a gradually reduced, I operation coupled with this and step ST9, while going repeatedly executes a routine, self-learning is made in the reference value t _b, MV _b is the ideal Approaching the target value.

【The invention's effect】

According to the present invention, the reference value of the allowance time and the control amount and the actual detection value are respectively compared, and the defrosting request signal is output or the reference value is updated according to the comparison result. The reference value approaches the ideal value for the cooling device during operation of the cooling device, and the defrost request signal can be obtained at the most appropriate timing, and the cooling device capacity can be determined from the frequency of the defrost request signal. There is an effect that you can know.

[Brief description of drawings]

FIG. 1 is a block diagram showing a frost adhesion amount measuring device for a cooling device according to a first embodiment of the present invention, FIG. 2 is a temperature characteristic diagram of a thermal shock tester, and FIG. 3 is a second embodiment of the present invention. 3 is a flowchart showing the operation of the thermal shock tester according to the example. 1 is a low temperature tank, 2 is a refrigerator, 3 is a heater, 4 is a temperature sensor, 6 is a PID control calculation unit, 11 is a frost adhesion amount calculation unit, and 12 is a memory.

Claims (1)

[Claims] 1. A precooling period for precooling a temperature in a low temperature tank cooled by a refrigerator to a predetermined precooling temperature lower than a set temperature, and a temperature detected by detecting the temperature in the low temperature tank with a temperature sensor. The control amount is calculated based on the set temperature, and the temperature control heater is heated according to the control amount, so that the control period for controlling the temperature in the low temperature tank to the set temperature is alternately repeated. In the impact tester, the reference value of the margin time and the reference value of the control amount from the time when the temperature in the low temperature tank reaches the predetermined precooling temperature during the precooling period to the start time of the control period is set. Setting means, detecting means for detecting the margin time and the control amount during operation of the refrigerator, two detection values detected, a reference value of the margin time and a reference value of the control amount. Compare each and that Defrost requesting means for outputting a defrost request signal according to the comparison result, the two detection values detected immediately after the defrost request signal is output, the reference value of the margin time, and the reference of the control amount. A thermal shock tester, comprising: a changing unit that compares the two reference values with each other and changes the two reference values according to the comparison result.