JPH02217753A - Control of refrigerant flow rate controller - Google Patents

Abstract

PURPOSE:To establish satisfactory transient cooling and smoothly transfer the operation to a stationary condition by flowing a refrigerant by two-step control wherein an electric valve is first fully opened upon building up of a transient interval of re-starting of cooling and then the electric valve is automatically adjusted to a proper degree of an opening. CONSTITUTION:A stationary condition (continuous cooling operation) are assumed as a state 1, a fully closed or refrigerator interruption state a state 2, and a transient condition from the interruption to the stationary condition a state 1. In the state 1, a control signal for adjusting the degree of valve open ing is issued from a valve driving part 16 to an electric valve 3 for effecting overheating control, and in the state 2 a valve opening signal BP is issued from a valve fully closing signal generator part 20 to the valve driving part 16 for effecting temperature control for a space to be cooled. For control in the state 3, the valve is fully opened by a constant control signal until an initial change is confirmed, and at the initial stage of re-starting of the cooling rapid cooling effect is assured. Further, upon completely transferring the operation to the stationary state 1, a result of the control in the previous stationary state is referred to for building up the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method of controlling a refrigerant flow rate control device applied to refrigeration devices such as air conditioners, freezers/refrigerators, and freezer/refrigerated showcases.

(b) Conventional technical patent publication No. 5g-47628 (IPC, F25B41
106), in the publication "Refrigerating", Vol. 56, No. 641 (March 1983 issue), pp. 60 to 64, there is a description of the refrigerant flow rate using a thermal lightning expansion valve, which is a type of electric valve. A control device is shown. According to such a refrigerant flow rate control device, the refrigerant flow rate control device operates according to the difference between the electric signals from the first temperature sensor provided at the inlet or intermediate portion of the evaporator and the second temperature sensor provided at the outlet portion of the evaporator. Refrigerant flow rate control is performed by outputting an electric signal to control the valve opening of the motor-operated valve to keep the difference between the electric signals constant and keeping the degree of superheating of the evaporator substantially constant.

In addition, the above conventional technology has been further improved, and i! ! In addition to valve-operated filtration heat control, a refrigerant flow control device has also been proposed that controls the temperature of a space to be cooled using an electric valve.

The cooling control device is shown in FIGS. 11 to 13, and its operating characteristics are shown in FIG. 14. Now, to explain according to each episode above, P indicates a refrigeration system, and this refrigeration system P is a compressor 1.
．． Condenser 2. A refrigerant circuit w16 is formed from the electric valve 3 and the evaporator 5 disposed in the space to be cooled 4, and a well-known cycle is formed in which the refrigerant is compressed, condensed and liquefied, decompressed (expanded), and evaporated. The heat-exchanged cool air 7 is circulated by the blower 8 as shown by the arrow. A7a indicates the discharged cold air, and 7b indicates the sucked cold air. Reference numeral 9 denotes a controller such as a microprocessor for controlling the opening/closing operation of the electric valve, and the controller 9 includes an evaporator outlet temperature sensor 10 provided at the outlet of the evaporator as a sensor for controlling the degree of superheating of the refrigerant; The detected value from the evaporation temperature sensor 1.1 installed at the inlet or the middle of the container is input as an electrical signal through signal lines L1 and L2, and the discharge cold air temperature is also used as a temperature control sensor to measure the temperature of the cold air in the space to be cooled. A sensor 12 and a suction temperature sensor 13 are provided, and detected values from these are also input as electrical signals through signal lines L31L4. L is a signal line through which a control signal to the electric valve 3 is output, and the controller 9 performs arithmetic processing as will be described later and outputs the signal line. Here, the internal configuration of the controller 9 will be explained using the block diagram of FIG. 12. It includes a first comparison section 14 that compares the set degree of superheat, which is a target value, and a feedback signal, an internal algorithm section 15, which serves as an adjustment section, A valve drive unit 16 serving as an operating unit, an evaporator temperature measuring unit 17 that detects the temperature of the evaporator 5, a cooled space temperature measuring unit 18 that detects the temperature of the cooled space 4, and a set humidity and a cooled space. It consists of a second comparison section 19 that compares the temperature with the temperature, and a valve fully open signal generation section 20. In addition, in the present invention, as the motor-operated valve, a pulse hydraulic expansion valve shown in FIG. Valve portion 26 and bellows 27 pressed by the shaft. It is composed of a valve body 30 consisting of a refrigerant inlet pipe 28 and a refrigerant outlet pipe 29, and a pulse motor 25 is operated to maintain an appropriate degree of superheat by a valve opening adjustment signal (pulse signal) from the valve driving section. to drive. Further, the rotational force of the pulse motor 25 is converted into vertical movement of the drive shaft 24 to adjust the valve opening degree.

The control operation of the electric valve in the above configuration will be explained.

Now, if the set degree of superheat (SH5) is set to 5°C, the measured degree of superheat SH is determined by the evaporator temperature measuring section 17 as follows: evaporator outlet temperature (8) detected by the evaporator outlet temperature sensor 10 - evaporator temperature sensor 11 The measured superheat degree (SH) and the set superheat degree (SH3) are calculated from the detected evaporation temperature (ET).
The first comparator 14 compares the deviation signal (DV) and inputs the deviation signal (DV) to the internal algorithm section 15, which corrects the deviation and sends the adjustment signal (H5) to the valve drive section 16.
Enter S). The valve drive unit 16 receives an adjustment signal (H3S)
Based on this, a valve opening adjustment signal (BKG) corresponding to the deviation from the set superheat degree (SO5) of 5°C is continuously given to the electric valve 3. In other words, the internal algorithm The pulse signal rejected and converged in section 15 is applied to the electric valve 3, and the refrigerant flow rate (Is) is adjusted to 5°C of the set superheat degree (S) Is) by the mechanical action of increasing/decreasing the valve opening → opening area → refrigerant flow rate (GA). Maintain an appropriate valve opening to maintain GA). As a result, the measured temperature (T resistance) of the cooled space 4 reaches the set temperature (Ts). The operation of the electric valve 3 by this superheat degree control is performed during the time period τ to τ□ in FIG. The valve opening degree !glffi5 is performed in the form of irregular steps.

Then, the temperature of the cooled space 4 is determined by the cooled space temperature measurement unit 1.
8 as the measured temperature (TM), and this measured temperature (TLI) is the average value of the temperature of the discharged cold air 7a (DA) and the temperature of the sucked cold air (RA), that is, TM = DA + RA / 2
It is calculated by This obtained measured temperature (TM).

The second comparing section 19 compares the set temperature (Ts) with the set temperature (Ts) and
)≦(Ts), the valve fully closed signal (BP) is input from the valve fully closed signal generator 20 to the valve drive unit 16 to close the electric valve 3, and performs temperature control called thermocycle. switching,
To prevent the cooled space 4 from becoming too cold. Moreover, this temperature 1
1 control is performed by the electric valve 3 regardless of superheat degree control.

In addition, a timer (T) is provided to enable cooling operation based on the duty cycle. - When the motor-operated valve 3 is opened at a certain opening degree for a certain period of time, the cooling operation is performed by circulating the refrigerant. After that, the electric valve 3 is closed, the cooling operation is stopped for a certain period of time, and then the cooling operation is resumed, which is a repeated operation.

Using the control method described above, the controller 9 controls the opening and closing of the electric valve 3 to perform cooling operation by controlling the refrigerant flow rate.

(c) The problem to be solved by the invention is that in the conventional device with the above configuration, from a steady state in which continuous cooling operation is performed by controlling the degree of superheating, the valves by defrost, thermocycle, and duty cycle Smoother and faster control of the motor-operated valve in a transient state where the refrigerator shuts down or the refrigerator stops, and then transitions from this stop to a steady state is not sufficiently implemented, so during recooling operation. The cooling speed of the refrigerator was slow, the pull-down time was prolonged, and the temperature of the space used increased over a long period of time, and the liquid return phenomenon had an adverse effect on the refrigerator. In addition, there are no thorough measures against failures of the various temperature sensors that control the degree of superheating and temperature, so in such emergencies, it is impossible to operate the refrigerant flow control device normally, and as a result, the space to be cooled becomes This has the drawback of not being able to properly cool the air, leading to abnormal temperatures.

The present invention solves the above-mentioned problems, and controls a refrigerant flow rate control device that quickly performs cooling even during re-cooling operation, has a sufficient backup function in case of sensor failure, and continues appropriate cooling operation. The purpose is to provide a method.

(d) Means for solving problems The present invention provides a superheat degree control sensor that measures the inlet temperature and outlet temperature of an evaporator, and a temperature control sensor that measures the discharge cold air temperature and suction cold air temperature of the space to be cooled. A controller is installed to control the opening and closing of the motor-operated valve based on the measured values from each sensor, and during the transition period of re-cooling operation such as after defrosting, the motor-operated valve is fully opened at first. Then, control is performed to adjust the valve opening to an appropriate degree calculated from the control valve data stored in the controller, and when the superheat control sensor fails, the electric valve is adjusted to the valve opening position immediately before the failure and fully open. control,
Furthermore, the present invention is a control method for a refrigerant flow rate control device in which temperature control is performed based on the measured value of a normal sensor when either one of the temperature control sensors fails, whereas duty cycle operation is performed when both of the temperature control sensors fail.

(E) Function In the transient state where cooling operation resumes from an unsteady state where cooling operation is stopped and shifts to a steady state, the motor-operated valve is once fully opened, rapid cooling is performed, and then the valve is opened according to the final state of the previous motor-operated valve. The system uses two-step control to start up and transition to a steady state.

This allows good cooling during transient times and smooth transition to a steady state. When the superheat control sensor fails, the electric valve is opened and closed at the open/close position immediately before the sensor malfunctions (if the previous one is fully open, the open/close position just before it becomes fully open), and the two open/close positions of fully open. It controls the temperature of the cooled space, and if one of the temperature control sensors fails,
The temperature of the space to be cooled is calculated from the other normal sensor and temperature control is performed. Furthermore, when both sensors fail, a duty cycle is activated to prevent the space to be cooled from becoming too cold.

In this way, even in the event of a sensor failure, the system operates according to a control method corresponding to the failure, and cooling control can be performed without any worries.

(f) Example An embodiment of the present invention will be described below based on the drawings.

The configuration of the refrigerant flow rate control device used in the present invention is as described above.
1 to 14, and the control states executed by the device can be distinguished as follows.

Steady state - continuous cooling operation → Displayed as state 1.

When fully opened, the refrigerator is stopped and displayed as 1m2.

A detailed comparison of these control states is shown in the chart of FIG. 1(a), and a graph of this state in relation to the transition of operation is shown in FIG. 2(b).

In other words, the cooling operation in state 1 from FIG.
t), when cooling begins, when recooling after defrosting is completed, and when the cooling period is in the duty cycle operation. Similarly, in state 2, when the cooled space temperature T reaches the set temperature Ts, cooling is stopped, defrosting is in progress, and the cooling is stopped during the duty cycle.

Transient state 3, which transitions from state MA2 to state 1, occurs at the time of opening the valve or starting operation, that is, at the start of cooling operation by the servo cycle, at the start of recooling operation after the end of defrost, and at the time of the duty cycle. This applies to the initial stage of cooling.

By the way, in the refrigerant flow rate control device adopted in the present invention, in state 1, a control signal for adjusting the valve opening degree is output from the valve drive unit 16 to the electric valve 3 to control the degree of superheating, and in state 2, A valve open signal (BP) is output from the valve fully closed signal generating section 20 to the valve driving section 16 to control the temperature of the 5 cooled spaces. FIG. 2 shows the state transition including the control signals given to these electric valves 3.

Next, the relationship between each state 1, 2.3 and the control signal Ca will be explained with reference to FIG. If the duration of state 2 is T11, then T
1 such that s << T K, e.g. Ts=6 seconds, TI=
120 seconds = 2 minutes or more (20-50 minutes when defrosting)
Under these conditions, control in state 1 is as follows. That is, if the control signal at time 1a is 100, it can be expressed as follows: "C,:='C,-z+ (Efi-Efi-1)
- Equation (1) Here, En8 deviation correction amount "C, -1 2nd control signal one time ago (Efi before Ts waiting time
-1 deviation correction (before Ts waiting time) Superheat degree control for adjusting the opening degree of the motor-operated valve 3 is carried out in the same way as in the past, using the control signal 1C7 according to the above equation (1).

Next, the control signal 2Cfl when performing control in state 2 is as follows: 3 is in the valve closed state. In this manner, when superheat degree control is not performed, a constant value is applied regardless of superheat degree data without performing control according to equation (1). Further, the final output control signal 'Cf1 (L) in the steady state is held separately from the output control 1C11 at that time for the TH time (TH>>Ts) during which the second state continues. This holding is performed by an internal algorithm or rhythm section 15.

Regarding the control in state 3, which is a feature of the present invention, stepwise control is performed by outputting the control signal in two steps as in the first order.

"Cl1=B (constant value)" until a change is recognized.
...(3) Continuation to equation state 1 'Cl1=kX''C
, (L)...Equation (4) (0≦≦1) In this way, (3
), keep it fully open with a constant control signal until you can confirm the initial change.

In this way, a rapid cooling effect is obtained at the initial stage of restarting cooling. Then, when completely transitioning to steady state 1 using equation (4), the previous steady state control result 1c
Start up with reference to e (r-).

In the case of this equation (4), the proportional constant can be adjusted appropriately according to the state by equipping the controller 9 with a learning function that can be changed according to the magnitude of the previous output value 1Cfi (L) to be referenced. The proportionality constant k can be determined.

In this way, two-step control from fully open to opening degree corresponding to the previous valve state is performed during the transition period, and once the transient state is no longer present, the control returns completely to steady state 1. Therefore, the timing of this state transition can be determined by determining whether or not the state is in a transient state.

To determine whether it is a transient state, monitoring of various elements and appropriate methods can be considered.

For example, the following method is used to return the state from s3 to 1 lil.

Time - After a certain period of time has elapsed after applying the output of formula (4), temperature - superheat data, temperature representative of the space to be cooled, etc. - Pressure, flow rate, etc. One or more of these quantities reach a certain standard. When it is recognized that this has occurred, the control returns to state 1 cyclically.

In this way, smooth and quick opening control of the motor-operated valve can be achieved in the transient state at the initial stage of restarting cooling, so the temperature rise at startup can be reduced, and liquid return is also prevented, reducing the danger to the refrigerator side. can also be resolved.

Next, the second aspect of the present invention will be explained. In the second invention, even when various sensors 10, 11, 12, 13 are out of order, alternative control is performed so that the temperature control of the space to be cooled can be carried out smoothly. The fault conditions and the controls that respond to them are as follows.

A: When the superheat control sensor fails, i.e. evaporation temperature sensor 1
1 failure or evaporator outlet temperature sensor 10 failure.

If one or both temperature sensors 1.0, 11 fail, the electric valve 3 immediately before sensor 10.11 fails.
Temperature control on the cooled space side is performed at the opening/closing position (if the immediately before is fully open, the opening/closing position immediately before full opening and the fully open position).

The specific situation is shown in Figure 3 when the evaporator outlet temperature sensor fails, Figure 4 when the evaporator temperature sensor fails, and Figure 5 when the southern temperature sensor fails. For example, in Figure 3 the evaporator outlet temperature sensor 1
0 fails at point a, motor operated valve 3 after sensor failure
The control operates in accordance with the thermocycle at two fixed positions, the open state of the electric valve indicated by ☆ and the fully open position. Similarly, if both the evaporation temperature sensors 11 fail at point (b) in FIG. 4 and at point (c) in FIG.
After that, the motor-operated valve 3 is controlled to be in the open position marked with ★ and fully open. In this case, the control data for electric valve 3 marked with ★ is as follows. This value is converged by excluding the disturbance (DT) that occurred during the time period from .tau. to .tau., serves as a reference value, and is stored in the internal algorithm section 15. Therefore, the disturbance (DT) is already
Since the valve opening degree data (reference value) that eliminates the sensor failure and realizes stable cooling is used, even if the sensor fails, the cooling effect does not change significantly and stable cooling can be continued.

FIG. 6 is a flowchart relating to a control method when the superheat degree control sensor 10.11 fails.

In the figure, the evaporation temperature sensor 11 is expressed as an (ET) sensor, and the evaporation outlet temperature sensor 10 is expressed as an (ST) sensor. In judgment 61, it is determined that either the ET or ST sensor has failed, and if it is normal (N), the process moves to process 62, where the controller 9 performs calculations, adjusts the valve opening degree by PID control, and controls the degree of superheating. On the other hand, if the determination 61 is a failure (N), a process 63 is performed in which the valve opening is set to the reference valve opening. In addition,
Here, it is assumed that the sensor can measure the upper limit temperature of +64°C and the lower limit temperature of -64°C to determine whether there is an abnormality in the ET or ST sensor.

The temperature detected by the ET and ST sensors is the upper limit +40°C.

A method of judgment is used in which when a temperature within the lower limit of -40°C is indicated, it is considered normal, and when a high temperature or low temperature exceeding this temperature range is indicated, it is considered abnormal.

B; Control when the temperature control sensor fails, that is, the discharge cold air temperature sensor 12 or the suction cold air temperature sensor 13 fails.

j) If either one of them fails, calculate the temperature of the space to be cooled from the normal temperature sensor.

Perform temperature control.

ii) If both temperature sensors fail, a duty cycle is activated to prevent the space to be cooled from becoming too cold. (Even if the duty cycle switch is OFF, the duty cycle is forcibly activated.

The specific situation is shown in Figure 7 when the intake cold air temperature sensor fails.
FIG. 8 shows the measured values of each temperature sensor and the electric valve actuation signal when the discharge cold air temperature sensor fails.

For example, if the suction cold air temperature sensor 13 fails at point (d) in FIG. It is calculated by regarding it as the temperature Tk of the space, and temperature control is performed. In the opposite case, as shown in FIG. 8, the temperature Tk is calculated by subtracting the temperature Δt from the measured value of the normal intake cold air temperature sensor 13.

When both fail, as shown in FIG. 9, the temperature of the space to be cooled is controlled by duty cycle operation after the failure.

In this way, when the temperature measurement sensor 12 or 13 in the space to be cooled fails, it is possible to calculate a value that approximates the temperature value under normal control from the measurement value of a normal sensor.

In addition, in the event of a failure in both, a thorough measure has been taken to perform the duty cycle, so that temperature control that provides sufficient cooling effect can be continued without interruption.

FIG. 10 is a flowchart relating to the control method when the temperature control sensor 12.13 fails. In the figure, the discharge cold air temperature sensor 12 is a (DA) sensor, and its measured temperature is (
OA), and the intake cold air temperature sensor 13 is expressed as (OA).
RA) sensor, and its measured temperature is expressed as (flA).

In judgment 101, it is determined whether or not there is an RA failure, and if it is normal (N), it is determined whether or not there is an OA failure.
+RA/2 is calculated. If the DA sensor is malfunctioning (Y) in the first judgment 102, a normal RA sensor is used and the process 10
4, the cooled space temperature Tk=RA-DΔ is calculated. Furthermore, if the RA sensor is faulty (Y) in the first judgment 101, it is judged in judgment 105 whether or not the DA sensor is faulty, and if the D^sensor is normal (N), processing 106 is performed and Tk=DA
The measured temperature is calculated by +Δt.

If the DA sensor is also faulty (Y) in judgment 105, after all,
Since both the RA and DA sensors are out of order, processing 107 for performing duty cycle operation is executed. Furthermore, this R
Similar to the ET and ST sensors described above, the abnormality judgment criteria for the A and DA sensors is based on whether or not the temperature is within the upper limit temperature of +40°C and the lower limit temperature of -40°C.

The above operations can be summarized as follows.

1) When the RA sensor fails, the measured temperature is assumed to be Tk.

2) When the DA sensor fails, →rRA-Δ is regarded as the measured temperature Tk.

3) When both RA and DA fail, the system shifts to duty cycle (cooling + valve closing).

4) If either ET, ST, or both fail, → maintain the electric valve at the standard valve opening.

In this way, each temperature sensor 10. il, 12.
13. When a failure occurs, temperature control of the space to be cooled is carried out based on the control method corresponding to each case.

(G) Effects of the Invention As described above, the refrigerant flow rate control device of the present invention employs two-stage control in which the electric valve is initially fully opened and then automatically adjusted to an appropriate opening degree at the start of the transition period of restarting cooling. Since the refrigerant is controlled to flow, the temperature rise in the space to be cooled during cooling stops tends to decrease quickly, and the one-step refrigerant flow eliminates the liquid return phenomenon and relieves the load on the refrigerator. In this way, the transition from an abnormal state (valve closed, refrigerator stopped) to a normal state (continuous cooling operation) is controlled smoothly.

Quick pay increases and improved control.

In addition, even if each temperature sensor for superheat degree control or temperature control fails, it has a sufficient backup function that will take over and operate the appropriate control accordingly, so until the failure is repaired, the It is possible to properly cool the space, and exhibits excellent effects such as not having a negative impact on stored products, etc.

[Brief explanation of the drawing]

Figure 1 (a) is a state classification diagram of cooling operation control, Figure 1 (b)
) is an operating characteristic diagram that associates the transition of operating state with the temperature at that time; Figure 2 is an operating characteristic diagram that correlates the control signal given to the electric valve with the transition of operating status and temperature;
The figure shows the relationship between each sensor measurement value and the electric valve operation signal when the evaporator outlet temperature sensor fails, and Figure 4 shows the relationship between each sensor measurement value and the electric valve operation signal when the evaporator temperature sensor fails.
Figure 5 is a diagram of the relationship between the measured values of each sensor and the operating signal of the electric valve when both the evaporator temperature sensor and evaporator outlet temperature sensor fail, and Figure 6 shows the failure detection of the evaporator temperature sensor and evaporator outlet temperature sensor. Fig. 7 is a diagram showing the relationship between each temperature sensor measurement value and the motor-operated valve operation signal when the intake cold air temperature sensor fails, and Fig. 8 shows the relationship between each sensor measurement value and the motor-operated valve operation signal when the discharge cold air temperature sensor fails. Figure 9 is a diagram showing the relationship between the measured values of each sensor and the operating signal of the electric valve when both the discharge cold air temperature sensor and the suction cold air temperature sensor fail. Figure 10 is the relationship between the discharge cold air temperature sensor and the intake cold air temperature sensor. 11 is a refrigerant circuit diagram, FIG. 12 is a block diagram of the controller, FIG. 13 is a longitudinal sectional view of the motor-operated valve, and FIG. 14 is a diagram of operating characteristics of the motor-operated valve. 3... Electric valve, 4... Space to be cooled, 5... Evaporator, 9... Controller, 10... Evaporator outlet temperature sensor, 11... Evaporation temperature sensor, ]2. ...Discharge cold air temperature sensor, 13...Suction cold air temperature sensor, I5...Internal algorithm section. Figure 1゜Figure Figure 1

Claims (1)

[Claims] An evaporator disposed in the space to be cooled, an electric valve for supplying reduced pressure liquid refrigerant to the evaporator, a superheat degree control sensor that measures an inlet temperature and an outlet temperature of the evaporator, respectively, and the space to be cooled. a temperature control sensor that measures the discharge cold air temperature and the suction cold air temperature, respectively; and a temperature control sensor that controls the valve opening of the electric valve based on the measured values obtained from the superheat degree control sensor, and the temperature control sensor and a control unit that closes the electric valve based on the measured value obtained from the control unit, and during the transition period of recooling operation, the electric valve is first fully opened, and then the control unit closes the electric valve based on the measured value obtained from the controller. Control is performed to adjust the valve opening to the calculated appropriate valve opening, and when the superheat control sensor fails, the electric valve is controlled at the valve opening position immediately before the failure and fully closed, and either one of the temperature control sensors fails. A control method for a refrigerant flow rate control device that sometimes performs temperature control based on the measured value of a normal sensor, and further performs duty cycle operation when both are malfunctioning.