JPH0339879A - Measuring device for frost deposition in cooling device - Google Patents

Abstract

PURPOSE:To obtain a proper defrosting request signal by storing in memory data for computing the amount of deposition of frost with respect to temperature, and evaluating the amount of deposition of frost in a low temperature tank on the basis of temperature detected in operation and the data stored in the memory. CONSTITUTION:There is evaluated the total sum of the amounts of control by integrating sampled values for one minute to obtain the time average which sum is stored in a memory 12 as the standard amount of control with respect to zero of the amount of deposition of frost. The amount of control yielded from a PID control computation part 6 is sampled every one second in a frost deposition amount computation part 11 based upon each data stored in the memory 12 upon operation of a refrigerator 2, the sample values being integrated for one minute to compute the sum of the amount of control. There is then estimated a temperature equal or closest to present temperature indicated by temperature data from a temperature sensor 4, and the amount of frost deposition is estimated from the amount of control corresponding to said estimated temperature. The computed value is displayed on a display unit 14.

Description

[Detailed description of the invention] [Industrial application field]

This invention relates to a cooling device in which a cryostat is cooled by a refrigerator and the temperature is controlled to a set temperature by a temperature control heater. This relates to a measuring device.

[Conventional technology]

In conventional cooling systems, the cryostat is constantly cooled by a refrigerator, and the temperature of the cryostat is detected by a temperature sensor.
By performing PID calculation based on the detected value and the set temperature, a control amount is calculated, and a temperature control heater installed in the cryostat is heated according to this control amount.
The cryostat is controlled to a set temperature. In such a cooling device, when frost adheres to the refrigerator, the refrigerating capacity decreases, so defrosting is performed when the amount of frost adhesion reaches a certain level. Conventionally, the timing for defrosting has been determined by the operator of the cooling device visually determining the state of frost buildup. In that case, it is fine if the frost is visible, but if the frost is hidden and cannot be seen, the operator should make a judgment based on experience, taking into consideration the operating time of the chiller, the surrounding temperature, etc. .

[Problem to be solved by the invention]

Deciding whether or not to perform conventional defrosting relies solely on the operator's judgment, which places a burden on the operator.
Further, it requires skill, and if the cooling device is operated in the absence of an operator, it becomes impossible to perform appropriate defrosting, causing problems in operation. In addition, if defrosting is performed at regular intervals of use, since refrigerators generally vary greatly between individuals and change over time, a certain amount of frost will not accumulate at regular intervals; If the speed is fast, the defrosting process will be delayed, which will reduce the refrigeration capacity and waste energy; if the frost buildup rate is slow, the defrosting process will be performed too quickly, resulting in wasted effort and time. At the same time, the operating efficiency of the refrigerator deteriorates. Therefore, it is possible to automatically display the frost adhesion state, but there are problems such as there being no suitable method for quantifying the frost adhesion state. This invention was developed in view of the above-mentioned circumstances, and includes a cooling device frost amount measuring device that is capable of quantifying the frost adhesion state of a refrigerator and displaying the current amount of frost adhesion. The object of the present invention is to obtain a frost adhesion amount measuring device for a cooling device that can obtain a defrosting request signal.

[Means to solve the problem]

In the invention of claim 1, data for calculating the amount of frost adhesion with respect to temperature is registered in the memory, and based on the temperature detected during operation and the data in the memory, the amount of frost in the cryostat is calculated. The amount of adhesion is calculated. In the invention of claim 2, when controlling the set temperature after precooling to a predetermined precooling temperature, the reference value of the margin time from the time when the precooling temperature is reached until starting the control of the set temperature , the reference value of the control amount, and combine these reference values with the actually sampled margin time and control value.
The defrosting request signal is output or the two reference values are updated depending on the comparison results.

[For use]

In the case of claim 1, the temperature sensor detects the temperature according to the temperature of the detection tank.
Temperature control is performed by PID III control, etc., and the state of frost adhesion inside the low temperature chamber can be known numerically during operation. In the case of claim 2, self-learning is performed by updating the reference value of the margin time and the reference value of the control amount, and finally the two reference values settle down to ideal values, and based on this, the self-learning is performed. A defrost request signal is output with appropriate tie straw.

【Example】

A first embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a cryostat, 2 is a refrigerator that constantly cools the cryostat 1, 3 is a temperature control heater provided in the cryostat 1, 4 is a temperature sensor that detects the temperature inside the cryostat 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 above temperature data and the set temperature; 7 is an A/D converter that converts the temperature detected by the temperature sensor 4 into digital temperature data; D to convert control iB'M into analog control amount
/A converter, 8 is a heater drive circuit that energizes the temperature control heater 3 according to the analog control amount, 9 is a keyboard for inputting the above set temperature and other data necessary for operating the cooling device, 10 is a keyboard Input data from 9 to P
This is a keyboard controller that sends data to the ID control calculation unit 6. 11 is the temperature data and PID obtained from the A/D converter 5
A frost adhesion amount calculation unit calculates the frost adhesion amount in the low temperature chamber by performing calculation processing described later based on data such as temperature and control amount obtained from the control calculation unit 6; 12 is a frost adhesion amount calculation unit; A memory in which predetermined data to be described later for calculating the amount of frost adhesion obtained by the frost adhesion amount calculating section 11 is stored, and 13 a display controller to which the current amount of frost adhesion data obtained by the frost adhesion amount calculating section 11 is supplied. , 14 is a display device that is controlled by the display controller 13 and displays the current amount of frost adhesion, and 15 is a PID control calculation unit 6.
This is a timer used in Next, the operation will be explained. The temperature detected by the temperature sensor 4 is converted into temperature data by the A/D converter 5, and this temperature data is sent to the PID control calculation section 6. The PID control calculation unit 6 calculates the control amount MV by performing a PID calculation based on this temperature data and the set temperature input from the keyboard 9. This 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 the temperature control heater 3 at a time corresponding to the control amount to perform heating. As described above, normal PID control is performed and the low temperature chamber 1 is maintained at the set temperature. Next, a method of creating data stored in the memory 12 for calculating the frost adhesion amount with respect to temperature will be described. (1) First, the refrigerator 2 is sufficiently defrosted to bring the amount of frost to zero. (2> Next, set a certain temperature T using the keyboard 9, and in a sufficiently stable state, set the above-mentioned PID fl
J? 11, and the control amount MV obtained during the control is 1
Sample every second. (3) Since the above-mentioned sampled values vary, the sampled values are integrated for one minute to obtain a time average, thereby obtaining the sum V of the control variables. , and store it in the memo IJ12 as the standard control amount MV, □ for zero frost adhesion amount. (4) Perform the operations in (1) to (3) above once for the temperature T, =Tn, and calculate each standard controlled variable (sum of controlled variables) MV. 1
~MV,. , memorize. In addition, the set temperature T, ~Tn is 5
The temperature shall be changed by ℃. Through the steps up to this point, the set temperature T, ~Tn and the standard control amount MV at zero frost adhesion amount are obtained. 1 to MV3on is required. (5) Next, Ig (Durham) frost is forcibly applied to the refrigerator 2. This is done by defrosting and drying thoroughly, and then spraying with air containing 1 g of moisture. (6) In the state where 1 g of frost is attached,
) to (4), and thereby the sum MV of the control amount for the set temperature T, -Tn at the frost adhesion amount of Ig! II to MV, . . . are stored. (7) Next, change the frost adhesion amount by Ig to 2 g and repeat the same operation as in (6) above for each frost adhesion amount. According to the above, for the amount of frost adhesion from 0 to mg, the sum of the control amounts MVso+ ~MV36R, MVsz ~MV
s+-...MVs-+ ~ MVs- is the set temperature T. .about.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 MV11J of the control variables when frost adhesion is 1ig. Therefore, for all set temperatures TINTn, using the least squares method, imαj+βj M Vsij + r j M Vs
Constants αj, βj, γj such that ij” (1) are calculated and registered in the memory 12. Based on each data created as described above and registered in the memory 12, the current frost adhesion is calculated. The amount can be known as follows: (1) When the refrigerator 2 is operating, the control amount MV obtained from the PID control calculation unit 6 is sampled every second in the frost adhesion amount calculation unit 11, and the sample is The sum of the controlled variables MSVij is calculated by integrating the values for one minute. (2) Find the temperature that is equal to or closest to the current temperature indicated by the temperature data obtained from the temperature sensor 4 from T and xTn and correspond to it. The frost adhesion amount i is calculated from the MVsij using the above formula (1). (3) The calculated value of i is displayed on the display device 14. By repeating this for several minutes, the amount of frost adhesion can be constantly monitored.
The control amount given to is used as a parameter to quantify frost adhesion. In other words, at the same set temperature, if the control amount is lower than when the amount of frost adhesion is zero immediately after defrosting, this is considered to be due to a decrease in the refrigerating capacity of the refrigerator 2 due to frost adhesion. I am using it. Next, a second embodiment of the present invention will be described in which the cooling device is used in a thermal shock M tester. A thermal shock tester consists of a test tank that houses the test object, 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, by alternately sending cold air and hot air into the test tank for a predetermined period of time, a low temperature exposure test and a high temperature exposure test of the test object are performed. FIG. 2 shows the temperature change characteristics p in the test chamber and the temperature change characteristics q of the low temperature chamber during the test. In FIG. 2, the temperature of the test chamber is maintained at 1.1 during high temperature exposure, and is maintained at T2 during low temperature exposure. When performing high-temperature exposure, the low-temperature bath is kept at a pre-cooled temperature T.
Pre-cooling is performed at i (<Tz), and by this pre-cooling, the target temperature Ta is quickly reached when transitioning from high-temperature exposure to low-temperature exposure. Further, when the low-temperature exposure is completed and pre-cooling begins, the temperature of the low-temperature chamber gradually decreases from Tz and reaches T at point A. When the high-temperature exposure is finished and the low-temperature exposure is started from point B, the temperature of the low-temperature bath quickly rises, overshoots the target temperature T, and then settles down to T. Here, from the above point A to B
If the time t up to the point is called a margin time, the margin time t8 becomes shorter as the amount of frost builds up on the low temperature chamber increases. That is, if the amount of frost adhesion is large, the cooling capacity of the refrigerator decreases, and therefore the time from the start of precooling to reaching point A becomes longer. In this second embodiment, the frosting state of the cryostat in such a thermal shock tester is determined and a defrosting request (delta) is issued at an appropriate timing. The thermal shock tester may have a configuration similar to the low-temperature Ifi+ shown in FIG. 1, with an r test chamber and a high-temperature chamber added, and other circuit blocks may also have the same configuration. However, 1261, high temperature tank control cylinder bJ
Therefore, illustration and explanation will be omitted. Next, in the operation of the zero frost adhesion section 110) in such a thermal shock tester, the flowchart of Fig. 3 -1.
I will explain it together. First of all 1. 1 in step S75, the reference value tl of the margin time t6 passed in advance, and the shortest lower limit value t of the margin time tl. The reference value Mvb of the control amount MV calculated by the PiDi control calculation unit 6 is set to a value that seems appropriate based on experience.Next, in step S2, the refrigerator 2 is operated. The cryostat 1 is cooled. Then, in step S75,
The current margin time during cooling (and the current control amount M
Detect V. These values t a and M V a are time-averaged sampling values. Next, in step S75, it is determined whether the detection in slap S73 is the first detection immediately after defrosting the low temperature chamber 1. If it is not the first detection, the process advances to step S75, where the detected value t and the reference value 1. Compare with. And 1. <1. In the case of , the defrosting request signal is output in step S Th and then the process returns to step S (lower 2). The defrosting request signal is visually or aurally displayed from the display device 14. If t<tl, the process proceeds to step S75, where the detected value MV
, and the reference (l!M V b . MV. If <MVb, a defrost request signal is output in step S75, and if MVm<M'Vb, the process proceeds to step S75. Here, the detection The value tl and the lower limit (illf t c are compared, and if 1. > 1., the process returns to step ST2; if ts > tC, the process proceeds to step ST9. Here, the standards for the margin time and control amount are tightened. , that is, t,
After changing both MV and MV to become larger by a predetermined amount, the process returns to step ST2. Immediately after the defrosting request signal is output in step ST6 and the defrosting work of the low temperature chamber 1 is performed in response to this, the determination in step ST4 is YES, and in that case, the process proceeds to step 5TIO. Here, the factor of the defrost request signal issued immediately before is due to 1, >1b or MV, <
In addition to checking whether this is due to MVb, check to see if the cause has been removed by defrosting. If the cause has been removed, steps ST5 and subsequent steps are executed; if the cause has not been removed, the process proceeds to step 5TII. Here, it is assumed that the standards used up to that point were too strict, and the standard value t or MV (as the case may be, both) are loosened depending on the above-mentioned factors. That is, it is changed to be smaller by a predetermined amount. According to the above, in step 5TII, the reference value tb+M
When Vb is decreased, step ST5
The determination in step ST7 is also based on the detected value t. Even if MV is small, it will move in the direction of No. Therefore, t□MV gradually decreases, and this, combined with the operation in step ST9, forces self-learning while repeatedly executing the routine, and the reference value t,,MV, becomes ideal. value.

【Effect of the invention】

According to the invention of claim 1, data consisting of a control amount for temperature, a predetermined calculation formula, etc. is registered in advance in the memory, and the frost adhesion amount is calculated based on the current temperature and the data in the memory. Therefore, the state of frost adhesion inside the cryogenic chamber can be expressed numerically, which eliminates the need for operator experience and intuition when defrosting, reducing the burden on the operator. Effects such as being able to provide functions to the refrigerator can be obtained. Further, according to the invention of claim 2, the reference values of the margin time and the control amount are compared with the actual detected values, and the defrosting request signal is issued or the reference value is updated according to the Φ comparison result. Since the reference value approaches the ideal value for the cooling device while the cooling device is in operation, the defrost request signal can be obtained with the most appropriate timing, and the defrost request signal can be obtained with the most appropriate timing. This has the effect of allowing the ability of the cooling device to be known from the frequency of the signal.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a frost adhesion 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 diagram showing a second embodiment of the present invention. It is a flowchart which shows the operation of the frost adhesion amount measuring device of the cooling device by 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 section, 11 is a frost adhesion amount calculation section, 12
is memory. Patent applicant: Yamatake Honeywell Co., Ltd.
Part 1 Tabai Espec Co., Ltd. Figure 3 Procedure Amendment (Voluntary)

Claims (2)

[Claims] (1) A temperature sensor detects the temperature inside the cryostat cooled by the refrigerator, calculates a control amount based on the detected temperature and the set temperature, and heats the temperature control heater according to this control amount. In this cooling device, the temperature in the cryostat is controlled to the set temperature, which includes a memory in which data consisting of a control amount for the set temperature, a predetermined arithmetic expression, etc. is registered in advance, and the temperature sensor. A frost adhesion amount measuring device for a cooling device, comprising: a frost adhesion amount calculating section that calculates an amount of frost adhesion in the low temperature chamber based on the temperature detected by the temperature and the data in the memory. (2) A pre-cooling period in which the temperature in the cryostat cooled by the refrigerator is precooled to a predetermined precooling temperature lower than the set temperature, and a temperature sensor detects the temperature in the cryostat, and the detected temperature and the above setting are performed. In the cooling device, a control period in which the temperature in the cryostat is controlled to the set temperature by calculating a control amount based on the temperature and heating a temperature control heater according to the control amount is alternately repeated. , a setting means for setting a reference value of a margin time from the time when the temperature in the low temperature chamber reaches the predetermined precooling temperature during the precooling period to the start of the control period and a reference value of the control amount; a detection means for detecting the margin time and the control amount during operation of the refrigerator, and comparing the two detected values with a reference value of the margin time and a reference value of the control amount, respectively; a defrosting requesting means that outputs a defrosting request signal according to the comparison result; and a defrosting requesting means that outputs a defrosting request signal of the two detection values detected immediately after the defrosting request signal is output, a reference value of the margin time, and the control amount. 1. A frost adhesion amount measuring device for a cooling device, comprising a changing means for comparing the two reference values with reference values and changing the two reference values according to the comparison results.