JP2816054B2 - Temperature control device for thermostatic chamber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PID control means for controlling a PID of a heating means, and a desired temperature gradient based on a target value set by a target setting means and a minimum resolution with respect to temperature and time of the control device. And a determining means for determining the temperature.

[0002]

2. Description of the Related Art Prior to the present invention, (i) JP-A-61-35
Japanese Patent Publication No. 856 discloses a thermostatic apparatus having a PID control means for controlling a temperature in a thermostatic chamber such as a cell culture apparatus to a desired temperature by controlling a heating means and a cooling means, and a temperature control method therefor. I have.

Further, prior to the present invention, (ii) Japanese Patent Laid-Open No. 2-6
Japanese Patent No. 4806 discloses that the temperature of an article in a constant temperature chamber is set to a desired set value in response to changes in the ambient temperature and the effects of heat generated in the constant temperature apparatus without using a temperature sensor for detecting the ambient temperature. A temperature control device for maintaining the temperature is disclosed.

Further, a conventional example of the present invention will be briefly described based on a block circuit diagram of a temperature control device (FIG. 8). 101
Is a temperature control device, which controls a heater 103 as a heating means based on a temperature detected by a temperature sensor 102 such as a thermocouple in order to control the temperature in the constant temperature chamber to a set temperature.
PID control means 104 for outputting a signal for control
A target setting means 105 for setting a target temperature of the constant temperature chamber and a target time for reaching the target temperature; and a signal to the PID control means 104 based on the value (that is, temperature gradient) set by the target setting means. Signal output means 1 for outputting
06. The signal output means 106 obtains a target temperature gradient from the target temperature and the target time, and calculates a desired constant temperature to change the target value by a constant temperature at predetermined time intervals based on the gradient. When,
An output unit 108 for increasing or decreasing the constant temperature calculated by the calculation unit 107 to the previous target value and outputting the same as the next target value.

[0005]

The control device shown in (i), (ii) and FIG. 8 has a predetermined time for changing the target value in the calculating section 107 in FIG. Since there is only a certain time, operation control with a temperature gradient smaller than (minimum resolution with respect to temperature) / (predetermined time, for example, minimum resolution with respect to time) could not be performed.
Further, even if the temperature gradient is equal to or more than (minimum resolution with respect to temperature) ÷ (predetermined time), the smaller the gradient is, the larger the deviation between the theoretical temperature value and the actual temperature (that is, the temperature error) tends to be. Even if an attempt is made to perform high-precision temperature control by PID control, the desired temperature gradient cannot be practiced due to restrictions on the set width of the temperature gradient (particularly the lower limit width), and in practice, very high-precision temperature control cannot be performed. there were.

Accordingly, in the present invention, operation control can be performed with a temperature gradient of less than the minimum resolution with respect to temperature and time of a temperature control device including a PID control means including a microcomputer and a driver IC for controlling the temperature of a constant temperature chamber, and high accuracy is achieved. It is an object of the present invention to provide a temperature control device for a constant-temperature chamber, which can perform an accurate temperature control.

[0007]

According to the present invention, there is provided a thermostatic chamber.
Temperature detecting means for detecting the temperature, heating means for heating the inside of the constant temperature chamber, target setting means for setting a target temperature in the constant temperature chamber and a target value for reaching the temperature, and analog-to-digital conversion And a PID for controlling the heating means so that the temperature in the thermostatic chamber detected by the temperature detecting means becomes a target temperature within a target time.
A temperature control device for thermostatic chamber and control means, before
Theoretically determined by the target value set by the target setting means
To be within a predetermined error range for the temperature gradient of
Multiply the minimum resolution of the temperature controller with respect to time by an integer
Time interval and the temperature of the analog-to-digital converter.
Determine the increase / decrease value that is an integral multiple of the minimum resolution
A temperature control device for a constant-temperature storage provided with a temperature gradient determining means for determining a distribution .

[0008] In the present invention, the temperature gradient determining means may include:
Time interval deciding means to determine the time interval to be minimum
There is provided a temperature control device for thermostatic chamber, characterized in that it includes.

[0009]

According to the present invention , the time interval for sequentially changing the set value can be appropriately determined based on the target temperature and the target time by the temperature gradient determining means. Operation with a temperature gradient of less than (resolution) ÷ (minimum resolution with respect to time) becomes possible, and the lower limit of the set width of the temperature gradient becomes wider.

According to the present invention , the temperature gradient determining means takes into account the minimum resolution for the temperature and time of the temperature control device with respect to the target value (ie, target temperature and target time) set by the target setting means. Can determine the temperature gradient in the control, the control limit (particularly, the lower limit of the set width) of the temperature control device can be expanded more than before, and the temperature can be controlled over a wide range, and the time interval at that time can be reduced.
Equipped with time interval determination means to determine the minimum
Within the specified error range of the theoretical temperature gradient and minimum
At the time intervals described above, fine temperature control can be performed, and the temperature control accuracy can be further improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 7 is a vertical cross-sectional view of the thermostatic chamber when the thermostatic chamber is viewed from the front.
Reference numeral 1 denotes a thermostatic chamber for business use, such as a hot air forced convection type high temperature thermostat. The thermostatic chamber 1 includes a heat insulating box 2 having a front opening constituting a main body thereof, and a door (not shown) for closing the opening. The heat-insulating box 2 includes a storage portion 3 having a top surface, a bottom surface, left and right side surfaces, and a back surface formed by heat-insulating walls, respectively, and a fan motor 1 formed on the right side wall of the storage room 3 and described later.
8 and an electrical component room 4 for storing electrical components such as a circuit board (not shown) including the temperature control device 31.

Reference numeral 10 denotes a vertical partition plate for partitioning the storage section 3 left and right. In the present embodiment, the left side of the vertical partition plate 11 is set at 30 ° C.
A constant temperature chamber 11 that can be heated to a high temperature up to about 300 ° C.
Heating means 13 such as an electric heater for alternating current, blower 1
7 is a blower chamber 12 in which a circulating fan (for example, a turbo fan) 19 and a temperature sensor 32 for controlling the temperature of a K thermocouple and the like connected to a temperature control device 31 to be described later are arranged. The constant temperature chamber 11 is further partitioned vertically by a net shelf (not shown), and the heating means 13 is formed in an annular shape and fixed to a substantially central portion of the blower chamber 12.

A suction port 14 for returning the air in the constant temperature chamber 11 to the suction side of the internal circulation fan 19 is formed at a substantially central portion of the vertical partition plate 10. Air outlets 15 and 16 for blowing out the air heated by the heating means 13 (that is, warm air) are formed in the constant temperature chamber 11.

An air blower 17 has two coaxial shafts and has an AC fan motor 18 located in the electrical component room 4, and a blower chamber 12 attached to one shaft of the fan motor 18.
And a fan motor 1 located inside the fan
8 and a cooling fan 20 for cooling each component of the electrical component room 4. It is desirable that the in-compartment circulation fan 19 has a smaller diameter than the annular heating means 13 and is disposed in a portion surrounded by the heating means 13.

Reference numeral 21 is attached to a portion of the right side wall of the heat insulating box 2 through which one shaft of the fan motor 18 penetrates for detecting the temperature of the surrounding atmosphere of the heating means 13 and the temperature in the vicinity of the internal circulation fan 19. And temperature detecting means (not shown in the block diagram) for preventing overheating, such as a posistor, and is connected to a temperature control device 31 described later.

FIG. 1 is a block circuit diagram of a temperature control device 31 for a constant temperature chamber. Reference numeral 32 denotes a temperature sensor for controlling the temperature of the K thermocouple for detecting the temperature of the constant temperature chamber 11, which is analog / digital (hereinafter referred to as "digital sensor"). A / D) via the conversion unit 33
Connected to ID control means 34. PID control means 34
The PID control of the heating means 13 and the fan motor 18 based on the output of the temperature gradient determining means 35 described later maintains the inside of the constant temperature chamber 11 at a desired set temperature. The temperature gradient determining unit 35 includes an arithmetic unit 36 as a time interval determining unit,
An output unit 37 is provided for increasing and decreasing the value calculated by the calculating unit 36 to a previous set value and outputting the set value.

A first memory 38 stores a minimum resolution (Δt) of time in the temperature control device, and a second memory 39 stores a minimum resolution (ΔT) of the A / D converter with respect to the temperature.
Is a target setting means for setting a user-specific target value consisting of a target temperature T of the constant temperature chamber 11 and a time t to reach the target temperature (that is, a target time) t. The target setting means 40 can set not only one target value but also a plurality of target values, and can change each target value in a stepwise manner or repeat this stepwise change. The so-called programmed operation for controlling the temperature of the constant temperature chamber can be set.

The arithmetic unit 36 as a time interval determining means includes:
Based on the minimum resolutions Δt and ΔT stored in the first and second memories 38 and 39 and the target temperature T and the target time t set by the target setting means 40, the set values Sn are sequentially set for each time interval. The time interval M for change and the value (increase / decrease value) Da to be increased / decreased to the previous set value are determined. The procedure for determining the time interval M and the increase / decrease value Da will be described later.

FIGS. 2 to 4 are flow charts for explaining the flow of the calculating operation in the calculating section 36 as the time interval determining means. The calculating operation will be briefly described below with reference to this flowchart.

In FIG. 2, when the power is turned on, a target value (T1, t1) for mode 1 is set in step S1, and
In step S2, a target value (T2, t2) for mode 2 is set, and in step S3, a target value (T1, t1) for mode 3 is set. However, the number of modes is not limited to three, but may be one, two or more, or any number.

Next, in step S4, it is determined whether or not the operation start switch has been pressed. The operation waits until the switch is pressed. If the start switch is pressed, the time for changing the set value is changed in step S5. The number of changes N of the timer (hereinafter referred to as a change timer) is set to 1, the temperature T0 of the constant temperature chamber 11 is sampled in step S6, and the first and second memories 38 and 3 are set in step S7.
9, the minimum resolution ΔT and Δt are read out, and a value Sa obtained by multiplying the minimum gradient by an integer (ie, Sa = mΔT / Δt) and a theoretical gradient St determined from the target value [ie, St = (T1−T0)
/ T1]. In the next step S8, the time interval M is set to 1 for calculation, and the process proceeds to step S9.
In step S9, the absolute value P of (1-MSa / MSt) (that is, P = | 1-MSa / MSt |) is calculated. Then, in step S10, it is determined whether or not P <0.02. If P ≧ 0.02, the value obtained by adding 1 to M in step S11 is set to M, and the process returns to step S9, where P <0.02 In step S12, M at this time is set as the time interval M of mode 1 and the value Da is increased or decreased to the previous set value Sn.
(Da = MSaΔt = MmΔT) is calculated, the count time of the change timer is set to NM, and the routine goes to step S13.

In step S13, the target time t for mode 1
It is determined whether or not 1 has elapsed, and if it has elapsed, the process proceeds to step S18, and if not, the process proceeds to step S14.
It is determined whether or not the counting time NM of the change timer has elapsed. If the NM has not elapsed, the process proceeds to step S17. If the NM has elapsed, the value obtained by adding 1 to N is set to N in step S15. In step S16, a value obtained by adding the increase / decrease value Da to the previous set value Sn is set as a new set value Sn + 1. In step S17, PID control is performed by the PID control means, and the process returns to step S13. Note that the initial value of the set value Sn in the mode 1 is T0.

Next, in FIG. 3, in step S18, it is determined whether or not there is a mode 2 of the program operation. If there is no mode 2, the process returns to step S1. N is set to 1, the temperature T0 of the thermostatic chamber 11 is sampled in step S20, the minimum resolutions ΔT and Δt are read out in step S21, and a value Sa obtained by multiplying the minimum gradient by an integer (ie, Sa = m)
ΔT / Δt) and the theoretical gradient St [that is, St = (T1−
T0) / t1] is calculated. In the next step S22, the time interval M is set to 1 for calculation, and the process proceeds to step S23, where P = | 1-MSa / MSt | is calculated. Then, in step S24, it is determined whether or not P <0.02, and if P ≧ 0.02, step S24 is executed.
In step 25, the value obtained by adding 1 to M is set to M, and the process returns to step S23. If P <0.02, M in step S25
Is set as the time interval M of the mode 2, and a value Da (Da = MSaΔt = MmΔT) that increases or decreases to the previous set value Sn is calculated, the time counted by the change timer is set to NM, and the process proceeds to step S27.

In step S27, the target time t for mode 2
It is determined whether or not 2 has elapsed, and if it has elapsed, the process proceeds to step S32, and if not, the process proceeds to step S28.
It is determined whether or not the counting time NM of the change timer has elapsed. If the NM has not elapsed, the process proceeds to step S31. If the NM has elapsed, the value obtained by adding 1 to N is set to N in step S29. In step S30, a value obtained by adding the increase / decrease value Da to the previous set value Sn is set as a new set value Sn + 1. In step S31, PID control is performed by the PID control means, and the process returns to step S27. The initial value of the set value Sn in the mode 2 is T0 = T1.

Finally, in FIG. 4, at step S32, it is determined whether or not there is a mode 3 of the program operation. If there is no mode 3, the process returns to step S1. N is set to 1, the temperature T0 of the constant temperature chamber 11 is sampled in step S34, and the minimum resolutions ΔT and Δt are sampled in step S35.
And a value Sa obtained by multiplying the minimum gradient by an integer (ie, Sa =
mΔT / Δt) and the theoretical slope St [ie, St = (T1
-T0) / t1]. In the next step S36, the time interval M is set to 1 for calculation, and in step S37
To calculate P = | 1-MSa / MSt |. Then, in a step S38, it is determined whether or not P <0.02.
If ≧ 0.02, the value obtained by adding 1 to M is set to M in step S39, and the process returns to step S37. If P <0.02, the value M is set to the time interval M of mode 3 in step S40.
And a value Da that increases or decreases to the previous set value Sn.
(Da = MSaΔt = MmΔT) is calculated, the count time of the change timer is set to NM, and the routine goes to step S41.

In step S41, the target time t for mode 3
It is determined whether or not 3 has elapsed, and if it has elapsed, the process returns to step S1, and if not, it is determined in step S42 whether or not the time NM of the change timer has elapsed. If not, the process proceeds to step S45. If NM has elapsed, the value obtained by adding 1 to N is set to N in step S43, and the value obtained by adding the increase / decrease value Da to the previous set value Sn is set to the new set value in the next step S44. As Sn + 1, PID control is performed by the PID control means in step S45, and the process returns to step S41. Note that the initial value of the set value Sn of the mode 3 is T0 = T2.

Here, a specific example of the target value will be described. As a first example, the range from 23.4.degree. C. to 100.degree.
If you want to raise the temperature with a constant temperature gradient over 0 hours,
In other words, the slope control is only for mode 1 and T1 is 10
Take the case where 0 ° C., t1 is 40 hours, and T0 is 23.4 ° C. ΔT = 1 [× 0.05 ° C.] , Δt = 1
[Minutes]. In this case, steps S1 to S1
8 are involved, of which steps S2 and S3 become unnecessary.

In step S7, Sa = mΔT / Δ
t = m = integer, St = (T1-T0) / t1 = (100
−23.4) /2400=0.0319 [° C./min]=
0.6383 [× 0.05 ° C./min] . In addition, Da =
Since MmΔT = Mm = MSa = integer, the actual increase / decrease value Da can be set only to an integer. Dt = MStΔ
Since t = MSt = 0.6383M, M and Da that satisfy step S10 are selected from values obtained by rounding down or rounding off the decimal part of the theoretical increase / decrease value MSt from the actual increase / decrease value Da. You know what to do.

In step S9, since Dt = 0.6383 when M = 1, Da = 0 or 1, and the value of P = | 1-Da / Dt |
5667, which are both larger than 0.02, so that the determination in step S10 is NO, and the next step S11
And add it to M as a new M (here, M =
2) Steps S9 to S11 are repeated until the error falls within 2% in step S10.
In the first example, the conclusion of step S12 is M = 11 [minutes] ,
Da = 7 [× 0.05 ° C.] = 0.35 [° C.] , and the progress of the calculation is shown in Table 1.

[0030]

[Table 1]

Until 40 hours have elapsed in step S13, the set value is set to 0.35 every 11 minutes.
The PID control is performed by the PID control means while increasing by [° C.].
It is determined whether or not there is, and since there is no mode 2, the process returns to step S1.

Next, as a second example, a case where temperature control with a constant temperature gradient toward three target values is set, that is, three gradient operations (slope control operation) continuous from modes 1 to 3, Target temperature T1 in mode 1 is 100
° C, the target time t1 is 2 hours, the sampled internal temperature T0 is 20 ° C, and the target temperature T2 in the mode 2 is 12 ° C.
A case where the target temperature t3 in the last mode 3 is 60 ° C. and the target time t3 is 2 hours is described below. Note that ΔT = 1 as in the first example.
[× 0.05 ° C.] , Δt = 1 [minute].

In the second example, first, in mode 1, in step S9, when M = 1, Dt = 13.0.
3333, Da = 13 or 14, and the value of P = | 1-Da / Dt | for each of them is 0.0250 or 0.
0500, and both are larger than 0.02, so it is determined NO in step S10, and M is determined in the next step S11.
And add it to M as a new M (here, M =
2) Steps S9 to S11 are repeated until the error falls within 2% in step S10.

In mode 1, the conclusion of step S12 is that M =
2 [min] , Da = 27 [× 0.05 ° C.] = 1.35
[° C.], and increases the set value every 1. minute by 1.35 ° C. every two minutes until two hours elapse in step S13.
PID control is performed by the ID control means, and after 2 hours, it is determined in step S18 whether or not there is mode 2;
Since there is the mode 2, the process proceeds to step S19.

In the next mode 2, in step S23, when M = 1, Dt = 3.3333, so that Da = 3 or
4, the value of P = | 1-Da / Dt | for each of these is 0.1000 or 0.2000.
Since it is larger than 2, it is determined as NO in step S24, 1 is added to M in the next step S25, and it is newly set as M (here, M = 2). In step S24, the error falls within 2%. Until the step S23 to the step S25 are repeated.

In mode 2, the conclusion of step S26 is M =
3 [min] , Da = 10 [× 0.05 ° C.] = 0.5 [° C.]
Until 3 hours elapse in step S17.
PID control is performed by the PID control means while increasing the set value by 0.5 ° C. every 2 minutes, and after 2 hours, it is determined whether or not there is a mode 3 in step S32. I do.

In the last mode 3, in step S37, when M = 1, Dt = -10, so that Da = -10
And the value of P = | 1-Da / Dt |
000, which is less than 0.02.
ES, and the conclusion in step S40 is M = 1.
[Min] , Da = −10 [× 0.05 ° C.] = − 0.5
[° C.], and the set value is reduced by 0.5 ° C. every 1 minute until PI has passed for 2 hours in step S44.
D control is performed, and the process returns to step S1 after 2 hours.

As described above, the time interval M for sequentially changing the set value can be appropriately determined by the time interval determining means 36 based on the target temperature T and the target time t set by the target determining means 40. Therefore, operation with a temperature gradient less than (minimum resolution with respect to temperature) ÷ (minimum resolution with respect to time), which cannot be realized with the conventional temperature control device, can be realized, and the lower limit of the set width of the temperature gradient is wider. And the control accuracy of the temperature control device is improved.

The temperature gradient determining means 35 controls the target temperature T and the target time t set by the target setting means 40, taking into account the minimum resolutions ΔT and Δt for the temperature and time of the temperature control device. Can be determined, the control limit of the temperature control device 31 (particularly, the lower limit of the set width of the temperature gradient) can be expanded as compared with the conventional temperature control device, and the temperature control can be performed over a wider range than in the past. The temperature control accuracy can be further improved.

[0040]

According to the present invention , the time interval for sequentially changing the set value can be appropriately determined based on the target temperature and the target time by the temperature gradient determining means . Operation at a temperature gradient of less than (minimum resolution with respect to temperature) ÷ (minimum resolution with respect to time) becomes possible, and the lower limit of the setting range of the temperature gradient becomes wider.

According to the present invention , the temperature gradient determining means takes into account the minimum resolution for the temperature and time of the temperature control device with respect to the target value (ie, target temperature and target time) set by the target setting means. Can determine the temperature gradient in the control, the control limit (particularly, the lower limit of the set width) of the temperature control device can be expanded more than before, and the temperature can be controlled over a wide range, and the time interval at that time can be reduced.
Equipped with time interval determination means to determine the minimum
Within the specified error range of the theoretical temperature gradient and minimum
At the time intervals described above, fine temperature control can be performed, and the temperature control accuracy can be further improved.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a temperature control device of the present invention.

FIG. 2 is a first flowchart showing a flow of a calculation operation of a temperature gradient determining means.

FIG. 3 is a second flowchart showing the flow of the calculation operation of the temperature gradient determining means.

FIG. 4 is a third flowchart showing the flow of the calculation operation of the temperature gradient determining means.

FIG. 5 is a time-temperature characteristic diagram in which a target value corresponds to one embodiment.

FIG. 6 is a time-temperature characteristic diagram corresponding to an example having three target values.

FIG. 7 is a vertical cross-sectional view of the thermostatic oven when the thermostatic oven is viewed from the front side.

FIG. 8 is a block circuit diagram showing a conventional example of a temperature control device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 constant temperature chamber 11 constant temperature chamber 13 heating means (heater) 31 temperature control device 32 temperature detection means (temperature sensor for temperature control) 33 analog / digital converter (A / D converter) 34 PID control means 35 temperature gradient determination means 36 time interval determination means (calculation unit) 37 output unit 40 target setting means

Claims (2)

(57) [Claims] 1. A temperature detecting means for detecting a temperature in a constant temperature chamber.
When a heating means for heating the inside constant temperature chamber, a target setting means for setting a target value as the target time to reach the target temperature and the temperature in the constant temperature chamber, an analog-to-digital converter
And a PID control means for PID controlling the heating means so that the temperature in the constant temperature chamber detected by the temperature detection means becomes a target temperature within a target time . Set by the goal setting means
Given the theoretical temperature gradient determined by the
The time of the temperature control device should be within the range of the error.
A time interval obtained by multiplying the minimum resolution with respect to the integer by the
Multiply the minimum resolution for the temperature of the digital-to-
Determine the temperature increase / decrease value and determine the temperature gradient
Temperature control of the thermostatic chamber, characterized in that a means. 2. The temperature gradient determining means according to claim 1 , wherein
A temperature control device for a constant-temperature storage , comprising a time interval determining means for determining so as to minimize the temperature.