TWI459172B - Electronic expansion valve control device - Google Patents

Description

Electronic expansion valve control device

The present invention relates to a control device for an electronic expansion valve of a refrigerating device, and more particularly to a control device for an electronic expansion valve that controls a valve opening degree of an electronic expansion valve to adjust the superheat degree of the refrigerating device.

For example, Japanese Patent Publication No. 2009-156502 (Patent Document 1) and Japanese Patent Publication No. Hei 8-33244 (Patent Document 2) are disclosed.

The technique of Patent Document 1 is a technique for changing the constant of the target value filter to determine that the degree of superheat is higher or lower than the set value of the superheat degree, and the superheat degree quickly converges to the set value, and the degree of superheat when the freezer is set is set. The adjustment is easy. Further, the technique of Patent Document 2 is a technique for monitoring the change in the degree of superheat and correcting the setting of the degree of superheat so that the operation can be always performed at the optimum setting value.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] JP-A-2009-156502 (Patent Document 2) Japanese Patent Publication No. 8-33244

In Patent Document 1, the adjusted superheat degree setting value can obtain the most suitable superheat setting at the time of adjustment, but it cannot be said that the set value is the most suitable value under any conditions. Therefore, infrequently In the case where the superheat setting value is adjusted, it is necessary to increase the superheat setting value in order to prevent the liquid back-mixing operation from continuing even if the season conditions or load conditions are changed. There is a problem on the top. In other words, in order to always operate at the most suitable degree of superheat, it is necessary for the user to change the superheat setting value each time the condition changes, thereby leaving a problem on the cumbersome side.

Further, in the technique of Patent Document 2, since the change in the degree of superheat of the fluctuation is input as a control signal to the controller during the period in which the superheat degree setting value is judged to be low and the correction is high, the electronic expansion valve is also volatility. The ground action is carried out, leaving a problem in the reliability of the electronic expansion valve.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a mechanical life that does not shorten the mechanical expansion of an electronic expansion valve even under a variety of refrigeration devices, loads, evaporator pressures, condenser pressures, etc., while operating at the most suitable degree of superheat. And the control device of the electronic expansion valve with high reliability.

The control device for an electronic expansion valve according to claim 1 is characterized in that it controls the superheat of the freezing device by giving an operation amount signal to the electronic expansion valve of the freezing device, and includes: a PID control mechanism according to the input a superheat setting value and a measured superheat degree of the freezing device, and outputting an operation amount signal to the electronic expansion valve; and a set value correcting unit that inputs a superheat degree setting value and a feedback value of the operation amount signal output by the PID control unit And correcting the superheat degree setting value outputted to the PID control mechanism, and outputting the corrected corrected superheat degree setting value to the PID control mechanism.

A control device for an electronic expansion valve according to claim 2 is the control device according to the first aspect, wherein the set value correcting means constantly monitors a change in a valve opening degree of the electronic expansion valve from a feedback value of the operation amount signal. In the first cycle (for example, one minute), the valve opening degree change amount and the valve opening degree change amount in the past second cycle degree (for example, about 10 minutes) are calculated, and the valve opening degree change amount in the past second cycle degree is calculated. When the first specific pulse (for example, 25 pulses) or less and the degree of change in the valve opening degree of the second cycle is less than or equal to the first specific pulse width (for example, 5 pulses), it is judged that the current superheat setting value is higher. In the case where the degree of change in the degree of opening of the second cycle is equal to or greater than the second specific pulse (for example, 87 pulses), it is judged that the current superheat setting value is lower. And correcting the superheat degree setting value to be higher; the first specific pulse and the first specific pulse amplitude are respectively obtained based on an experiment, and the structure of the electronic expansion valve or the length of the second cycle is long The degree is different, but the value of the upper limit obtained during the operation of the second period is determined in a state where the degree of superheat control is determined to be stable; and the second specific pulse is a value calculated from the life of the electronic expansion valve, and is as follows When the valve opening degree change amount in the second cycle period is within the second specific pulse, the operation of the refrigerating device is continued while the operation state is maintained, and it is assumed that the predetermined life (for example, 10 years) of the electronic expansion valve is passed. The value is also calculated in such a manner that the number of endurance actions of the electronic expansion valve is not exceeded, and the value is compared with the value obtained by the experiment which can reliably determine that the degree of superheat is low and unstable (close to liquid backmixing). The value of the smaller party.

The control device of the electronic expansion valve of the third aspect is the technical solution 2 The electronic expansion valve control device is characterized in that the set value correcting means memorizes the valve opening degree during the past third period every third period longer than the first period (for example, 10 minutes as in the second period) The amount of change is the value of the third period of the valve opening degree change during the third period, and the previous degree is maintained as the value of the third period of the valve opening degree change during the third period. In the first cycle, the amount of change in the valve opening degree during the third cycle in the past is the third specific pulse (for example, 21 pulses) or more, and is increased to "the valve opening during the third cycle". The value of the change in the value of the third period of the third period is more than three times, or the amount of change in the degree of opening of the valve in the third period of the past is the third specific pulse (for example, 21 pulses) or more, and is increased to "the first In the case where the value of the valve opening change during the 3 cycle period is more than 4 times the value of the previous period of the third cycle period, it is also judged that the current superheat degree setting value is lower, and the above superheat degree setting value is corrected to be more The highest; the value of the third specific pulse is based on the experiment The value reached, and even in a system with a slow change in superheat degree, it is judged that the superheat degree is low and unstable (close to liquid backmixing) is the minimum value, by setting the condition above the third specific pulse, For example, "the value of each third cycle period of the valve opening degree change amount during the third cycle period" is one pulse, and the valve opening degree change amount during the third cycle period of the first cycle is three pulses, or "The degree before the value of the valve opening degree change period during the third period is the first pulse", and the valve opening degree change amount is 4 pulses during the third period of the first cycle. In the case of a very small amount of valve opening change, it is possible to prevent the erroneous determination that the control should be stable as low and unstable (close to liquid backmixing). Also, the above 3 times and 4 times times the rate It is also a value based on experiments, and it is judged that the degree of superheat is low and unstable (close to liquid backmixing) even in a system where the degree of superheat changes slowly.

The control device for an electronic expansion valve according to claim 4 is the control device according to claim 2 or 3, characterized in that the self-refrigerating device starts to operate, and after the control device ends the startup process, the past calculation is performed from each of the first cycles. When the valve opening degree change range of the second cycle level is within the second specific pulse width (for example, 25 pulses), or the elapsed time after the freezing device starts operating and the control device ends the startup process becomes 30 minutes or longer, the time is established. , start the correction of the above superheat setting value.

According to the electronic expansion valve control device of the first aspect, the superheat degree of the freezing device is controlled by giving an operation amount signal to the electronic expansion valve of the refrigerating device, and includes: setting the superheat degree according to the input and the refrigerating device a PID control unit that outputs an operation amount signal to the electronic expansion valve; and an input superheat degree setting value and a feedback value of the operation amount signal output by the PID control unit, and corrects the superheat output to the PID control unit The set value is output, and the corrected corrected superheat setting value is output to the set value correcting mechanism of the PID control mechanism, so that the superheat degree setting value is judged to be higher or lower by the feedback value of the operation amount signal, thereby correcting It is the most suitable value and can be operated at the most suitable superheat setting according to the system state of the freezer.

The control device of the electronic expansion valve of the second aspect of the present invention determines that the current superheat degree setting value is higher by the valve opening degree change amount and the change range of the electronic expansion valve If it is lower, the correction is made. Since the amount of change in the valve opening degree of the electronic expansion valve whose superheat setting value is low is determined so as not to exceed the mechanical life of the electronic expansion valve, the operation of the electronic expansion valve is longer than the design life. Correcting the superheat setting value higher before, the change in the degree of superheat and the change in the valve opening degree of the electronic expansion valve can be stabilized, so that the reliability is remarkably improved in addition to the effect of the first embodiment.

According to the control device for the electronic expansion valve of the third aspect, in addition to the effect of the second aspect, even if the system is large in scale, the superheat setting value is low, the superheat degree is unstable, and the superheat degree is changed. If the amount of change in the valve opening degree of the electronic expansion valve of the second cycle does not reach the second specific pulse (for example, 87 pulses), it is still possible to judge that the change in the degree of superheat is unstable, thereby correcting the above. The superheat setting value described above can be operated at the most suitable superheat setting value.

According to the control device for the electronic expansion valve of the fourth aspect, since the setting of the superheat degree setting value is not performed in the initial stage of the unstable operation of the refrigerant, and the circulation from the refrigerant is stabilized, it depends on the constitution of the first to third embodiments. Since the state in which the correction of the superheat degree setting value becomes effective is started, the effects of the first to third aspects can be effectively obtained.

Next, an embodiment of a control device for an electronic expansion valve according to the present invention will be described with reference to the drawings. 1 is a functional block diagram of a main part of a first embodiment of a control device for an electronic expansion valve according to the present invention, and FIG. 2 is a functional block diagram of a main part of a second embodiment of a control device for an electronic expansion valve according to the present invention. Figure 3 is a third embodiment of the control device for an electronic expansion valve of the present invention The main part of the functional block diagram, which is surrounded by a broken line in FIGS. 1 to 3, is a unique configuration of the present invention. Fig. 4 is a view showing a first system example (Fig. 4(A)) and a second system example (Fig. 4(B)) of the refrigeration system using the control device of each embodiment.

In Fig. 4, a 10-series compressor, a 20-series condenser, a 30-series electronic expansion valve, and a 40-series evaporator are connected in a loop by a pipe to form a refrigeration cycle, which is used to compress, condense, and decompress the refrigerant. A well-known cycle of (expansion) and evaporative gasification. 50 is a valve drive unit such as a pulse motor that adjusts the valve opening degree of the electronic expansion valve 30 based on an input signal. The 100-series controller and the control device for the electronic expansion valve of each embodiment are mounted in the controller 100. The controller 100 seeks an operation amount signal of a PID operation with a deviation signal calculated based on the superheat degree of the comparison refrigeration cycle and the superheat degree setting value set therein, and outputs the operation amount signal to the valve driving unit 50 to control the electronic The valve opening of the expansion valve 30. That is, the operation amount signal corresponds to the number of driving pulses of the pulse motor or the like applied to the valve driving unit 50. The difference between the first system example and the second system example is as follows.

In the first system example of FIG. 4(A), a temperature sensor 60 that detects the temperature of the outlet-side pipe of the evaporator 40 and a pressure sensor 70 that detects the evaporation pressure on the outlet side of the evaporator 40 are provided, and the controller The air temperature is calculated from the input signal from the pressure sensor 70, and the difference between the input signal of the temperature sensor 60 from the outlet side pipe and the calculated evaporation temperature is obtained to calculate the degree of superheat according to the temperature/pressure type. In the second system example of FIG. 4(B), a temperature sensor 60 that detects the temperature of the outlet-side pipe of the evaporator 40 and a temperature sensor 80 that detects the temperature of the inlet-side pipe of the evaporator 40 are provided, and the controller 100 profit The degree of superheat according to the temperature/temperature type is calculated by taking the difference between the temperature of the outlet-side pipe of the evaporator 40 and the temperature of the inlet-side pipe of the evaporator 40 from the respective input signals from the temperature sensors 60, 80. Further, the above calculated superheat degree is referred to as "measurement superheat degree". In addition, the meaning of "the difference between "X" and "Y"" as used herein means "X" - "Y".

In the first embodiment of Fig. 1, the 1st set value correction means, the 2nd type PID control means, the 3rd type control object, and the 4th type measuring part. The controller 100 includes a computer including a CPU or a memory, and the functions of the set value correction unit 1, the PID control unit 2, and the measurement unit 4 are obtained by executing a specific control program by the computer of the controller 100. The PID control unit 2 includes a PID calculation unit 21, a target value change unit 22 including a target value filter, and a target value change control unit 23 of the control target value change unit 22. The set value correction means 1 receives, for example, a superheat degree set value SV set by the user, and the set value correcting means 1 outputs the corrected superheat degree set value SV' corrected by the superheat degree set value SV to the target value changing unit 22 and The target value change control unit 23. Further, the control target 3 is a refrigeration cycle including the first system example or the second system example of the electronic expansion valve 30, and the measuring unit 4 calculates the evaporation temperature or the superheat degree of the refrigeration cycle, and calculates the superheat degree as the measured superheat degree PV. It is output to the PID calculation unit 21.

The target value change unit 22 changes the input corrected superheat degree setting value SV' according to the transfer function of the target value filter, and outputs the set value of the superheated degree after the change to the PID calculation unit 21 as the target value. The change in the target value is done in a controlled manner. The corrected superheat degree set value SV' is also input to the target value change control unit 23, and the target value change control unit 23 detects the direction of the change of the corrected superheat degree set value SV', that is, the corrected superheat degree set value SV'. The state is changed or decreased, and the change in the target value output from the target value changing unit 22 is controlled in accordance with the direction of the change.

The PID calculation unit 21 performs a PID calculation based on the deviation E between the superheat degree setting value (target value) output from the target value changing unit 22 and the measured superheat degree PV, and supplies the operation amount signal MV to the control target 3. In the embodiment, the target value filter is provided, and the PID control of the two degrees of freedom is performed, and the target value change control unit 23 is used to change the target value at the time of the fall and the target value when the corrected superheat degree set value SV' is raised. The control target value changing unit 22 is more moderate than the change, and the measurement target value changing unit 22 can make the measurement overheated regardless of whether the corrected superheat degree setting value SV' is raised or decreased as long as it is an appropriate value for the control target. Degree PV quickly converges.

In the general refrigeration apparatuses of Patent Documents 1 and 2 and the control device using the electronic expansion valve of the present invention, the change in the degree of superheat of the superheat setting value is stabilized. Conversely, in the case where the superheat setting value is low, the change in the degree of superheat becomes unstable for the following reasons. When the superheat setting value is an appropriate value or more, the refrigerant in the piping ends to evaporate in the evaporator, and the temperature sensor detecting the outlet pipe temperature is completely turned into a gas, thereby becoming an overheating overheating. The state of the steam passes. Since the amount of heat absorbed by the evaporation portion of the refrigerant is much higher than that of the refrigerant which is completely evaporated by the end of the evaporation of the refrigerant, the piping of the evaporation portion of the refrigerant becomes low temperature. Therefore, in the low-pressure side piping of the refrigeration system, there is a portion where the temperature changes drastically before and after, that is, a portion where the evaporation change ends and is converted into a change in overheating. In the case where the superheat setting value is an appropriate value or more, the end of the evaporation change and the detection The installation position of the temperature sensor of the outlet piping temperature is sufficiently located on the upstream side. Therefore, under the superheat control, even if the movement is slightly moved back and forth, the temperature of the outlet pipe input to the controller remains stable, and the measured superheat is stable. . However, if the superheat setting value is lower than the appropriate value, if the end of the evaporation change is close to the installation position of the temperature sensor detecting the outlet pipe temperature, and the position slightly moves back and forth under the superheat control, In addition, the temperature of the outlet pipe input to the controller is drastically changed, and the change in the degree of superheat is measured. If the degree of superheat is controlled, the change in the degree of superheat will fluctuate. The correction process of the superheat degree setting value of the present invention is to correct the superheat degree set value to be low in the case where the superheat degree change is stable, and conversely, in the case where the superheat degree change is unstable, the superheat degree set value is corrected to The higher, as a result, the refrigerant ends the evaporation at a position slightly upstream of the mounting position of the temperature sensor that detects the outlet piping temperature. Since the temperature sensor that detects the temperature of the outlet pipe is installed at the outlet of the evaporator, evaporation is almost completed using the entire evaporator, so that efficient heat exchange can be performed.

Here, the control device for the electronic expansion valve according to the present invention controls the valve opening degree to be larger if the superheat degree is higher than the superheat degree setting value, and vice versa if the superheat degree is lower than the superheat degree setting value. The method is such that the valve opening degree is reduced so that the measured superheat of the refrigeration cycle is equal to the superheat setting value. Therefore, the change in the degree of superheat of the refrigeration cycle also appears as a change in the valve opening degree of the electronic expansion valve 30 (change in the operation amount signal MV). On the other hand, the set value correction unit 1 feeds back the output of the operation amount signal MV output from the PID control unit 2 (the PID calculation unit 21), and the set value correction unit 1 monitors the operation. The quantity signal MV corrects the superheat setting value SV and outputs the corrected superheat setting value SV'. Further, in the case of the above Patent Document 2, the measured superheat degree PV is fed back to the set value correcting means.

That is, when the set superheat of the refrigerating cycle is not equal to the superheat setting value and the fluctuation is higher or lower than the superheat setting value, the change of the valve opening degree also fluctuates, and the superheat degree is determined in the case of the freezing cycle. The change in valve opening is also stable. Therefore, as in Patent Document 2, even if the change in the measured superheat degree is not directly input, the output of the operation amount signal MV of the superheat degree is controlled by the feedback output, and as a result, it is judged that the change in the degree of superheat is stable or unstable. Thus, by judging based on the output of the operation amount signal MV, the mechanical life of the operating end of the electronic expansion valve can be considered at the same time. It is corrected in such a way that it does not operate when the operating terminal is excessively actuated.

In the second embodiment of Fig. 2, the same components as those in Fig. 1 are denoted by the same reference numerals as in the first embodiment, and the detailed description thereof will be omitted. In the second embodiment, the correction operation start determination means 5 that feeds back the evaporation temperature from the measurement unit 4 is provided. The correction operation start determination means 5 determines whether or not the "superheat degree setting addition processing at the time of startup" is completed and whether or not the prohibition of the correction operation is canceled, and outputs the correction processing for causing the set value correction means 1 to start the superheat degree setting value. Instructions.

In the third embodiment of Fig. 3, the same components as those in Fig. 1 are denoted by the same reference numerals as in the first embodiment, and the detailed description thereof will be omitted. In the third embodiment, the PID calculation unit 21 itself is a "PID control unit", and the set value correction unit 1 directly outputs the corrected superheat degree set value SV' of the corrected superheat degree set value SV to the PID calculation unit 21. Way composition.

Next, a more specific control of the embodiment will be described. First, "the superheat degree setting addition processing at the time of startup" is performed at the start of the freezing apparatus. This is for the following reasons. During the period from the start of the operation of the refrigerating apparatus, until the refrigerant passes through the refrigerant piping system, the refrigerant 40 is insufficient in the evaporator 40, and the degree of superheat becomes high. If the higher degree of superheat is detected and the degree of superheat control is directly performed, the valve opening degree of the electronic expansion valve 30 is excessively opened. Further, when the refrigerant is too low or the degree of superheat is too small, the liquid tends to be back-mixed, and the like, and the stable control state becomes slow. Therefore, the "superheat setting addition processing" described below is performed.

The correction superheat degree SV' output from the set value correction mechanism 1 is not a preset superheat setting (SH) from the end of the start of the freezing apparatus to the condition of any of the following conditions (1) or (2). The value is used to control the degree of superheat of the startup (SHS) as the target value for superheat control.

(1) "10 minutes after the end of the start-up process"

(2) "The evaporating temperature (SL) at the end of the self-starting process varies by 3 [K]/5 minutes"

The difference between the superheat degree setting (SHS) and the superheat degree setting (SH) at the time of startup is treated as an "additional part", and when the condition (1) or (2) is established, the additional part is set as the additional part. 0. That is, in appearance, the target value is changed from SHS to SH.

Next, the start point of the correction operation by the superheat degree setting of the set value correction mechanism 1 is controlled. The correction operation of the superheat degree setting is prohibited until the end of the start-up process to any of the conditions (3) or (4) below. And, if either of the conditions (3) or (4) is established, it is judged to be in a steady state (load and valve) In the state of the ability balance, the correction operation of the superheat setting is released, and the correction operation is started.

(3) "30 minutes after the end of the start-up process"

(4) "The valve opening in the past 10 minutes has changed within 25 pulses"

The startup process is to start the operation from the freezer, and the controller inputs an instruction to start the control (this input signal is called "start input", and is input to the controller with a relay contact, etc.) to the PID at which the controller starts superheat. Controlling the processing, for example, to set the valve opening degree of the electronic expansion valve to the valve opening position at which the PID control is started (this is referred to as the starting opening degree), or a certain time before starting the PID control (this is called Start time) Maintain the start of the opening process.

The correction operation of the superheat degree setting by the set value correction mechanism 1 is performed as follows. When the target value of the superheat degree is low, the liquid refrigerant comes to the vicinity of the mounting position of the temperature sensor 60 of the outlet pipe of the evaporator 40, and the input (detection temperature) of the temperature sensor 60 becomes not Stable, so that the value of the measured superheat becomes unstable. Therefore, the presence or absence of the unstable state is detected, and the setting of the superheat degree is corrected to the optimum value, and the corrected superheat degree setting value is generated.

The correction operation of the superheat setting value is also performed by adding or subtracting the additional portion of the setting in the same manner as the "superheat degree setting addition processing at the time of startup". The detection of the unstable state is judged based on the change in the valve opening degree of the electronic expansion valve 30, that is, the change in the operation amount signal MV.

FIG. 9 is a diagram conceptually showing the data processing of the set value correction mechanism 1. The set value correcting mechanism 1 corrects the superheat setting value, and the self-starting process ends. At the time, the data of the valve opening degree change amount, the maximum opening degree position, and the minimum opening position of the operation amount signal MV are counted every one minute, and the data is maintained for the past 10 minutes. The following values (a) and (b) are calculated based on the information of each other every 1 minute.

The change in valve opening in the past 10 minutes...(a)

The degree of change in valve opening in the past 10 minutes...(b)

Further, every 10 minutes, after the above-mentioned treatment per minute, the values of the following (c) and (d) are also updated.

The value of the valve opening change in the past 10 minutes (a) every 10 minutes... (c)

The value of the change in valve opening in the past 10 minutes (a) is above the value of every 10 minutes... (d)

When the "superheat degree setting addition processing at startup" is completed and the correction operation is prohibited, the conditions of (5) to (9) are evaluated every 1 minute to increase or decrease the additional portion of the setting to perform the superheat setting value. Corrected.

(In the case where a steady state is detected) The correction for lowering the superheat setting value is performed according to the conditions of (5) and (6) below.

(5) The amount of change in valve opening in the past 10 minutes (a) is 25 pulses or less

(6) The degree of change in valve opening in the past 10 minutes (b) is less than 5 pulses

When both of the above conditions (5) and (6) are satisfied, the additional portion of the setting is reduced by 1 [K], and the superheat setting value is corrected lower. Moreover, 15 minutes after the lower correction, even if both of the above conditions (5) and (6) are satisfied, the correction of the reduced superheat setting value will not be performed. Further, when the superheat degree setting value is corrected from the unstable state, the state is stabilized, and the superheat degree setting value is not corrected 30 minutes after the superheat degree setting value is increased.

(In the case where an unstable state is detected) The correction of the superheat setting value is performed in accordance with the conditions of (7), (8), and (9).

(7) The amount of change in valve opening in the past 10 minutes (a) is 87 pulses or more

(8) The amount of change in the valve opening degree in the past 10 minutes (a) is 21 pulses or more and is more than 3 times the value (c) of every 10 minutes of the change in the valve opening degree in the past 10 minutes.

(9) The amount of change in the valve opening degree in the past 10 minutes (a) is 21 pulses or more and is more than 4 times the value of the threshold value (d) above the value of the change in the valve opening degree in the past 10 minutes. When any one of (7), (8), and (9) is established, the additional portion of the setting is increased by 1.0 [K] to correct the superheat setting value.

In addition, when the correction is performed, the data of the valve opening degree change amount, the maximum position, and the minimum position of the past 10 minutes counted every one minute is temporarily reset to zero. Moreover, the values of (c) and (d) are updated with the data before the correction even after 10 minutes have elapsed, and the counter is restarted for 10 minutes.

5 to 8 are flowcharts showing the control operation of the set value correcting means 1 of the controller 100, which is executed by the microcomputer built in the controller 100, and the function of the set value correcting means 1 is obtained. The processing of FIGS. 5 to 7 is performed by, for example, the insertion processing of the timing of about 1 second with respect to the main processing of the controller 100, and the processing of FIGS. 5 and 6 corresponds to the second embodiment.

Fig. 5 is a flow chart showing the superheat degree setting addition processing at the time of startup. First, in step S1, it is determined whether or not the elapsed time after the start of the operation and the completion of the start processing is 10 minutes or longer. If the determination is YES, the corrected superheat degree set value is changed from SHS to SH in the step S2, and the superheat degree set value is ended. Add it and return to the original routine. If the determination in step S1 is NO, step S3 In the middle, it is determined whether the magnitude of change in the evaporation temperature (SL) in the past 5 minutes is 3 [K] or less. If the determination is YES, the addition of the superheat degree setting value is completed in step S2 and the original routine is restored. NO returns directly to the original routine. According to the above processing, the superheat degree setting addition processing corresponding to the start of the above conditions (1) and (2) is performed. The state of the system for setting the superheat degree at the time of startup is, for example, as shown in FIG.

Fig. 6 is a flow chart showing the process of canceling the determination of the prohibition of the operation. First, in step S4, it is determined whether or not the elapsed time after the start of the operation and the completion of the start processing is 30 minutes or longer. If the determination is YES, the prohibition of the correcting operation is canceled in step S5 and the original routine is restored. If the determination in step S4 is NO, it is determined in step S6 whether or not the valve opening degree change width in the past 10 minutes is 25 pulses or less. If the determination is YES, the prohibition of the correction operation is canceled in step S5 and the original routine is restored. If it is judged to be NO, it will directly return to the original routine. According to the above processing, the process of canceling the prohibition of the correction operation corresponding to the above conditions (3) and (4) is performed. The state of the system corresponding to the release determination processing for correcting the action prohibition is, for example, as shown in FIG.

Fig. 7 is a flow chart showing the correction processing of the superheat setting value. This processing is executed when the prohibition of the correction operation is released, and the 1-minute timer and the 10-minute timer are started, and the processing of the 1 minute timer and the 10-minute timer is repeated and restarted. First, in step S11, it is determined whether or not one minute has elapsed. If it is determined to be NO, the original routine is directly restored. If the determination is YES, in step S12, the valve opening according to the operation amount signal MV is counted for one minute. The amount of change in degree, the maximum opening position of 1 minute, and the minimum opening position of 1 minute, and the process proceeds to step S13. In step In step S13, based on the statistical data described above, the valve opening degree change amount (a) in the past 10 minutes and the valve opening degree change range (b) in the past 10 minutes are calculated, and the process proceeds to step S14.

In step S14, it is determined whether or not 10 minutes have elapsed. If the determination is NO, the process of the correction determination subroutine of Fig. 8 is performed in step S16, and the original routine is restored. If the determination in step 14 is YES, in step 15, the value of the valve opening degree change (a) in the past 10 minutes (c) and the valve opening degree change amount (a) in the past 10 minutes are updated. The value is returned (d) above every 10 minutes. Then, in step S16, the process of the correction determination subroutine of FIG. 8 is performed and the original routine is restored.

In the correction determination subroutine of Fig. 8, the determination of the above conditions (5), (6), and (7) to (9) is performed. The condition (7) is determined in step S21, the condition (8) is determined in steps S22 and S23, and the condition (9) is determined in steps S22 and S24. In the case where the condition (7) is satisfied in the step S21, the condition (8) is satisfied in the steps S22 and S23, and the condition (9) is satisfied in the steps S22 and S24, the process proceeds to step S25 to set the superheat degree. The 1[K] is increased and output as the corrected superheat setting value, and the masking time processing is performed in step S26 and restored to the original routine. The masking time processing of step S26 is for performing the process of correcting the setting of the reduction for 30 minutes after the setting value is increased, and the masking time is set to 30 minutes.

If none of the above conditions (7) to (9) is satisfied, it is determined in step S27 whether or not the masking time has elapsed. If the determination is NO, the original routine is directly restored. If the determination is YES, the step is The condition (5) is determined in S28, The condition (6) is determined in step S29. When both of the conditions (5) and (6) are satisfied in steps S28 and S29, the superheat degree setting value is lowered by 1 [K] in step S30 and output as the corrected superheat degree setting value, and masking is performed in step S31. The hood time is processed and restored to the original routine. The mask time processing of step S31 is to perform the process of correcting the reduction target value even if both of the above conditions (5) and (6) are satisfied, and the mask time is set. It is 15 minutes. The state of the system corresponding to the above-described correction processing of the superheat degree setting value is as shown in FIG.

Further, in a state where the degree of superheat is higher than the set value, there is a case where the control output for moving the electronic expansion valve in the valve opening direction is performed, but the upper limit opening degree (OLP) is restricted. When the degree of superheat correction is performed in the state, the valve opening degree is changed to the upper limit opening degree and is stabilized, so that the correction of the set value is continued to be lowered. Therefore, the case where the upper limit opening degree (OLP) is limited is reset. Variables are not corrected.

Further, it has a function of preventing the liquid from returning to the original state and preventing the overload of the compressor motor when the compressor is started, and the maximum operating pressure (MOP). In the state in which the degree of superheat is higher than the set value, the control output for moving the electronic expansion valve in the valve opening direction is performed, but the valve opening degree is restricted by the MOP function. The situation also resets the variables related to the correction without correcting the processing.

When the user changes the superheat degree setting SH, the behavior of the electronic expansion valve that does not recognize the change of the set value is not stabilized, and the change variable is temporarily reset and the correction process is restarted when the setting is changed. . Further, when SH is changed, the case where the additional portion is set is reset to zero.

Although the control device for inputting the operation amount signal output for judging is also widely existed in other fields, it is often used for the purpose of simply protecting the operation terminal. The control device of the present invention is different from the above, and the feedback input operation amount signal output is used as a control input signal processing, and is actively used by the superheat degree set value corrector. That is, since the input operation amount signal output functions only in the form of limiting the operation amount signal output for the purpose of protecting the operation terminal, there is a possibility that the desired control output cannot be output and the controllability is deteriorated. On the other hand, the control device of the present invention uses the feedback input operation amount signal output, and simultaneously determines whether the operation amount signal output is operated within a range in which the reliability of the electronic expansion valve can be ensured, and the superheat degree setting value is higher or higher. The low judgment does not deteriorate the controllability and the operation amount output can be suppressed to the extent that the reliability of the electronic expansion valve can be ensured, and the degree of superheat degree can be corrected to the most suitable value by effectively utilizing the evaporator. On the other hand, unlike other people, you can get huge results.

1‧‧‧Set value correction mechanism

2‧‧‧PID control agency

3‧‧‧Control objects

4‧‧‧Determination Department

5‧‧‧Revised action start determination mechanism

10‧‧‧Compressor

20‧‧‧Condenser

21‧‧‧PID Computing Department

22‧‧‧ Target Value Change Department

23‧‧‧ Target Value Change Control Department

30‧‧‧Electronic expansion valve

40‧‧‧Evaporator

50‧‧‧ Valve Drive Department

60‧‧‧ Temperature sensor for the outlet side of the evaporator

70‧‧‧pressure sensor

80‧‧‧ Temperature sensor for the inlet side of the evaporator

100‧‧‧ Controller

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a functional block diagram showing a principal part of a first embodiment of a control device for an electronic expansion valve according to the present invention.

Fig. 2 is a functional block diagram showing a principal part of a second embodiment of the control device for an electronic expansion valve according to the present invention.

Fig. 3 is a functional block diagram showing a principal part of a third embodiment of the control device for an electronic expansion valve according to the present invention.

4(A) and 4(B) are diagrams showing a first system example and a second system example of a refrigeration system using a control device according to each embodiment of the present invention.

Fig. 5 is a flow chart of the superheat degree setting addition processing at the start of the embodiment Figure.

Fig. 6 is a flow chart showing the process of canceling the determination of the correction operation prohibition in the embodiment.

Fig. 7 is a flow chart showing the correction processing of the superheat degree setting value in the embodiment.

Fig. 8 is a flow chart showing the subroutine of the correction determination of the embodiment.

Fig. 9 is a diagram conceptually showing the data processing of the embodiment.

Fig. 10 is a view showing an example of a state of a system corresponding to the superheat degree setting addition processing at the time of startup of the embodiment.

Fig. 11 is a view showing an example of a state of a system corresponding to the release determination prohibition determination processing of the embodiment.

Fig. 12 is a view showing an example of the state of the system corresponding to the correction processing of the superheat degree setting value in the embodiment.

1‧‧‧Set value correction mechanism

2‧‧‧PID control agency

3‧‧‧Control objects

4‧‧‧Determination Department

5‧‧‧Revised action start determination mechanism

21‧‧‧PID Computing Department

22‧‧‧ Target Value Change Department

23‧‧‧ Target Value Change Control Department

Claims (4)

A control device for an electronic expansion valve, characterized in that it controls the superheat of the freezing device by giving an operation amount signal to the electronic expansion valve of the freezing device, and includes: a PID control mechanism that is set according to the superheat degree of the input And an output operation amount signal for the electronic expansion valve; and a set value correction mechanism that inputs a superheat degree set value and a feedback value of the operation amount signal output by the PID control unit, and corrects an output The superheat degree setting value to the PID control mechanism is outputted, and the corrected corrected superheat degree setting value is output to the PID control mechanism. The control device for an electronic expansion valve according to claim 1, wherein the set value correcting means constantly monitors a change in a valve opening degree of the electronic expansion valve from a feedback value of the operation amount signal, and calculates a past value every first cycle. The amount of change in the degree of opening of the valve and the degree of change in the degree of opening of the valve in the second cycle are the number of changes in the degree of opening of the valve in the second cycle of the past, which are below the first specific pulse, and the degree of change in the degree of opening of the second cycle in the past is In the case where the first specific pulse width is lower than the first specific pulse width, it is judged that the current superheat degree setting value is higher, and the superheat degree setting value is corrected to be lower; in the past second cycle degree, the valve opening degree change amount is the second specific pulse. In the above case, it is judged that the current superheat setting value is lower, and the superheat degree setting value is corrected to be higher. The control device for an electronic expansion valve according to claim 2, wherein the set value correction mechanism is stored in every third cycle longer than the first cycle, and the memory is past The amount of change in the valve opening degree during the third cycle is maintained to the previous level, and the amount of change in the valve opening degree during the third cycle period in the past period is the third specific pulse or more and is increased to the first cycle. 3 times or more of the value of the "per-third cycle period of the valve opening change amount during the third cycle", or the valve opening degree change amount during the past 3rd cycle is the third specific pulse (for example, 21 pulses) In the case where the above is added to the time before the value of the period of the third period of the valve opening degree change during the third period is more than four times, it is judged that the current superheat setting value is lower, and the above is The superheat setting is corrected to be higher. The control device for the electronic expansion valve of claim 2 or 3, wherein the valve opening degree change range from the second cycle period calculated in the first cycle is started after the refrigeration device starts operating and the control device ends the startup process The correction of the superheat degree setting value is started from the point where the second specific pulse width is within the range of the second specific pulse width or when the elapsed time after the start of the control device and the start of the control device is established.