JP2003106684A - Method for controlling refrigerating cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigerating cycle capable of providing high efficiency and high stability. SOLUTION: Valve opening compensation regions are provided above and below a temperature dead zone to compensate a valve opening and cause hunting of the valve opening in order to generate a pulse and an intermediate flow rate of pulse in a pseudo manner.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a refrigeration cycle using an electric expansion valve.

[0002]

2. Description of the Related Art JP-A-63-116 with reference to the drawings
An example of a conventional refrigeration cycle control device using an electric expansion valve disclosed in Japanese Patent No. 058 will be described.

FIG. 7 is a refrigeration cycle diagram showing the compressor 1,
The heat exchanger 2, the electric expansion valve 3, and the heat exchanger 4 are connected in an annular shape. The opening degree of the electric expansion valve is controlled by the control device 6a which receives the temperature detected by the discharge temperature sensor 5 as an input signal. In the figure, the solid line arrow indicates the flow direction of the refrigerant.

FIG. 8 is a block diagram of the control device 6a. The output of the temperature detection means 7 and the output of the target temperature setting means 8 are compared by the temperature comparison means 9, and the valve opening degree calculation means 10 determines the valve opening degree according to the output.

The valve opening comparison means 11 detects whether the obtained valve opening is the maximum valve opening or the minimum valve opening up to now, and when it is detected that it is the maximum valve opening. The valve opening degree at that time is stored in the maximum valve opening degree storage means 12, and when the minimum valve opening degree is detected, the valve opening degree at that time is stored in the minimum valve opening degree storage means 13. .

The maximum value and the minimum value are input to the average valve opening calculation means 14 and the average valve opening is output from the valve opening output means 15. At this time, the temperature dead zone generating means 16 changes the valve opening. It produces a temperature dead zone that stops.

FIG. 9 is a flowchart of the control device 6a. FIG. 10 shows changes in the discharge temperature and the valve opening with respect to the target temperature of the discharge temperature. 9 and 10 will be described below.

The discharge temperature Td is detected and compared with the target temperature Ts. As a result, if the discharge temperature is low, the valve opening
P decrease. The valve opening is maintained as it is for ΔT time, and the discharge temperature Td is again compared with the target temperature Ts. At this time, if the discharge temperature Td is higher than the target temperature Ts, the valve resolution is increased by ΔP, and the valve opening degree before the increase is stored as the minimum valve opening degree (Pmin).

Similarly, the discharge temperature Td and the target temperature Ts are repeatedly compared every ΔT time, and the discharge temperature Td becomes equal to the target temperature T.
When changing from a state higher than s to a state lower than s, that is, when the change in valve opening changes from ΔP increase to ΔP decrease,
The valve opening degree before P reduction is stored as the maximum valve opening degree (Pmax).

Maximum valve opening (Pmax), minimum valve opening (Pmax)
When min) is confirmed, the average value ((Pmax + Pm
in) / 2) to change the excuse.

Further, when the output of the average valve opening calculating means 14 is generated, the detected discharge temperature Td is Ts + by providing temperature lines of Ts + ΔTh and Ts−ΔTh on the plus side and the minus side of the target temperature Ts, respectively. ΔTh or less and
When Ts-ΔTh or more, the opening of the electrically driven expansion valve is not changed and the discharge temperature Td is brought close to the target temperature Ts to be stabilized.

[0012]

However, when the flow rate of the refrigerant is low, the refrigeration cycle is not stable because the discharge temperature has large overshoot and undershoot as shown in FIG.

Further, in the electric expansion valve in which the refrigerant flow rate change per minimum unit (1 pulse) of the valve opening degree is large, the discharge temperature Td changes greatly with a change of 1 pulse as shown in FIG.
There is a problem that the discharge temperature Td cannot be stabilized in the temperature dead zone region and a highly efficient refrigeration cycle cannot be provided.

Therefore, an object of the present invention is to provide a refrigerating cycle which brings the discharge temperature Td close to a target value and has high efficiency and high stability.

[0015]

A method for controlling a refrigeration cycle according to claim 1 of the present invention for achieving the above object comprises a refrigeration cycle including a compressor, a heat exchanger, an expansion valve, and the like. The temperature at a predetermined point in the previous period refrigeration cycle is detected by the temperature detecting means, the detected temperature is compared with the target temperature determined by the target temperature setting means by the temperature comparing means, and the detected temperature is equal to or higher than the target temperature by the valve opening output means. In the case of, the expansion valve is opened by a certain amount, and when the detected temperature is lower than the target temperature, a certain amount is closed, and when the operation of the expansion valve is changed from the opening operation to the closing operation, immediately before the closing operation is changed. Maximum valve opening calculation means for making the valve opening of the valve the maximum valve opening, and the minimum valve opening for making the valve opening immediately before changing to the opening operation the minimum valve opening when changing from the closing operation to the opening operation. Computation means, whether the maximum valve opening and the minimum valve opening An average valve opening calculating means for calculating an average valve opening, while maintaining the valve opening of the expansion valve and outputs a valve opening degree calculating means the output of said average valve opening calculating means,
When the output of the average valve opening calculation means is generated, a temperature dead zone in which the target temperature and the temperature detection means are not compared is generated so as to extend across the plus side and the minus side around the target temperature. In a control device including a dead zone generating means, a valve resolution correction area generating means for generating an area for correcting the valve opening of the expansion valve on the plus side and the minus side of the temperature dead zone, and the output of the detected temperature and the target temperature. A valve opening correction amount calculation means for obtaining the correction amount from is provided.

With this configuration, the valve opening correction area is provided on the plus side and the minus side of the temperature dead zone to correct the valve opening, thereby providing a highly efficient and highly stable refrigeration cycle even at a low refrigerant flow rate. can do.

In a refrigeration cycle control method according to a second aspect of the present invention, a refrigeration cycle is constituted by a compressor, a heat exchanger, an expansion valve, etc., and the temperature of a predetermined portion of the previous refrigeration cycle is detected by a temperature detecting means. The detected temperature and the target temperature determined by the target temperature setting means are compared with each other by the temperature comparison means, and when the detected temperature is equal to or higher than the target temperature, the expansion valve is opened by a certain amount, and when the detected temperature is less than the target temperature, a certain amount is opened. A control device having a valve opening output means for performing a closing operation is provided with a hunting table calculation means for hunting the valve opening.

With this configuration, it is possible to provide a highly efficient and highly stable refrigeration cycle even in the electric expansion valve in which the refrigerant flow rate change per minimum unit of valve opening (1 pulse) is large.

A refrigeration cycle control method according to a third aspect of the present invention is the refrigeration cycle control method according to the second aspect, wherein the calculation result pulse number of the valve opening is divided into a positive integer a and a decimal point number b. , The valve opening (a + b) is determined, and the valve opening (a) maintenance time ΔT (a) and the valve opening (a + 1) maintenance time ΔT (a + 1) are calculated as ΔT (a): ΔT. (A + 1) =
(1-b): The hunting table is calculated so as to be b, and the valve opening is hunted.

With this configuration, the refrigerant flow rate can be controlled more finely, and a highly efficient refrigeration cycle with high stability can be provided.

[0021]

The present invention according to claim 1 is characterized in that, in addition to the control method of the prior art, a valve opening correction region is provided on the plus side and the minus side of the temperature dead zone to correct the valve opening. And This makes it possible to provide a refrigeration cycle with high efficiency and high stability even when the flow rate of the refrigerant is low.

The present invention according to claims 2 and 3 is characterized in that the valve opening degree is hunted so that an intermediate flow rate between pulses is artificially generated. As a result, it is possible to provide a highly efficient and highly stable refrigeration cycle even in the electric expansion valve in which the refrigerant flow rate change per minimum unit (1 pulse) of the valve opening degree is large. Embodiment Mode 1 An embodiment mode of the present invention will be described with reference to the drawings. The same parts as those in the drawings of the conventional example are designated by the same reference numerals and the description thereof will be omitted.

FIG. 1 is a refrigeration cycle diagram, in which the opening degree of the electric expansion valve is controlled by a control device 6b which uses the temperature detected by the discharge temperature sensor 5 as an input signal.

FIG. 2 is a block diagram of the control device 6b. Overflow of discharge temperature at low refrigerant flow rate,
Correction is necessary because the undershoot is large. Therefore, the valve opening correction area generating means 17 generates a temperature area for correcting the valve opening on the plus side and the minus side of the temperature dead zone, and when the output of the temperature detecting means 7 is in the correction area, the valve opening is performed. The degree correction amount calculation means 18 determines the correction amount of the valve opening from the output of the temperature detection means 7 and the output of the target temperature setting means 8. From the output of the correction amount calculation means 18 and the output result of the average valve opening calculation means 14, the valve opening hunting table calculation means determines the valve opening as (a + b), and the valve opening (a) and the valve opening The respective maintenance times of (a + 1) are determined and repeatedly output from the valve opening output means 15.

Here, a is a positive integer and b is 0 ≦ b <1. Further, when the output of the repeated temperature detecting means 7 is in the correction area, the correction is further added.

3 to 5 are flowcharts of the control device 6b. FIG. 6 shows changes in the discharge temperature and the valve opening with respect to the target temperature of the discharge temperature. 9 and 10 will be described below.

The discharge temperature Td is detected and compared with the target temperature Ts. As a result, if the discharge temperature is low, the valve opening
P decrease. The valve opening is maintained as it is for ΔT time, and the discharge temperature Td is again compared with the target temperature Ts. At this time, if the discharge temperature Td is higher than the target temperature Ts, the valve resolution is increased by ΔP, and the valve opening degree before the increase is stored as the minimum valve opening degree (Pmin).

Similarly, the discharge temperature Td and the target temperature Ts are repeatedly compared for each ΔT time, and the discharge temperature Td becomes equal to the target temperature T.
When changing from a state higher than s to a state lower than s, that is, when the change in valve opening changes from ΔP increase to ΔP decrease,
The valve opening degree before P reduction is stored as the maximum valve opening degree (Pmax).

Maximum valve opening (Pmax), minimum valve opening (Pmax)
When min) is confirmed, the average value ((Pmax + Pm
in) / 2) to change the excuse.

Further, when the output of the average valve opening calculating means 14 is generated, Ts + ΔTh, Ts−ΔTh, and Ts + ΔTT are respectively on the plus side and the minus side of the target temperature Ts.
, Ts-ΔTT temperature lines are provided and the detected discharge temperature Td is Ts + ΔTh or less and Ts-ΔTh or more, the opening degree of the electric expansion valve is not changed. T
When s + ΔTT or less and higher than Ts + ΔTh, the correction amount calculating means 18 determines the correction amount ΔP (Td−Ts), and when Ts−ΔTh or less and Ts−ΔTT or more, the correction amount ΔP. Determine (Ts-Td).

From the output of the correction amount calculating means 18 and the output result of the average valve opening calculating means 14, the valve opening hunting table calculating means determines the valve opening as (a + b), and the valve opening (a) The maintenance time ΔT (a) and the maintenance time ΔT (a + 1) of the valve opening (a + 1) are expressed as ΔT (a): ΔT (a + 1) =
(1-b): The valve opening output means 15 is determined to be b.
The valve opening (a) and the valve opening (a + 1) are repeatedly output.

Here, a is a positive integer, and 0 ≦ b <1. Further, when the repeated discharge temperature Td is equal to or lower than Ts + ΔTT and higher than Ts + ΔTh, the correction amount calculation means 1
The correction amount ΔP (Td-Ts) is determined by 8, and Ts-Δ
When it is less than Th and more than Ts-ΔTT, the correction amount ΔP (Ts-Td) is determined and further correction is made.

[0033]

Since the present invention is constructed as described above, it has the following effects.

According to the control method of the first aspect of the present invention, the valve opening correction region is provided on the plus side and the minus side of the temperature dead zone so as to correct the valve opening degree, so that even when the refrigerant flow rate is low, the high value is obtained. A refrigeration cycle with high efficiency and high stability can be provided.

According to the control method of the second aspect of the present invention, the minimum unit of the valve opening (1 pulse) is generated by hunting the valve opening to artificially generate an intermediate flow rate between the pulses. It is possible to provide a highly efficient and highly stable refrigeration cycle even in an electric expansion valve in which the refrigerant flow rate per change is large.

According to the control method of the third aspect of the present invention, in the method of controlling the refrigeration cycle of the second aspect, the calculation result pulse number of the valve opening is separated into a positive integer a and a decimal point number b. Then, the valve opening is determined to be (a + b), and the maintenance time ΔT (a) of the valve opening (a) and the maintenance time ΔT (a + 1) of the valve opening (a + 1) are ΔT (a): Δ T (a + 1) =
By calculating the hunting table so that (1-b): b, the refrigerant flow rate can be controlled more finely, and a highly efficient refrigeration cycle with high stability can be provided.

[Brief description of drawings]

FIG. 1 is a refrigeration cycle configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram of a control device of the present invention.

FIG. 3 is a flowchart showing the control contents of the present invention.

FIG. 4 is a flowchart of the same.

[FIG. 5] Same flowchart

FIG. 6 is a time chart showing the discharge temperature and valve opening of the present invention.

FIG. 7 is a conventional refrigeration cycle configuration diagram.

FIG. 8 is a block diagram of a conventional control device.

FIG. 9 is a flowchart showing the control contents of a conventional example.

FIG. 10 is a time chart showing a discharge temperature and a valve opening of a conventional example.

FIG. 11 is a time chart showing a discharge temperature and a valve opening of a conventional example.

FIG. 12 is a time chart showing a discharge temperature and a valve opening of a conventional example.

[Explanation of symbols]

1 compressor 2, 4 heat exchanger 3 expansion valve 5 Discharge temperature sensor 6 control device 7 Temperature detection means 8 Temperature comparison means 9 Target temperature setting means 10 Valve opening calculation means 11 Valve opening comparison means 12 Maximum valve opening storage means 13 Minimum valve opening storage means 14 Average valve opening calculation means 15 Valve opening output means 16 Temperature dead zone generating means 17 Valve Opening Correction Area Generating Means 18 Valve opening correction amount calculation means 19 Valve opening hunting table calculation means

Continued front page    (72) Inventor Hiraya             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd.

Claims (3)

[Claims] 1. A refrigeration cycle comprising a compressor, a heat exchanger, an expansion valve, etc., the temperature of a predetermined portion of the previous refrigeration cycle is detected by a temperature detecting means, and the detected temperature and a target determined by a target temperature setting means. The temperatures are compared by the temperature comparison means, and the expansion valve is opened by a certain amount when the detected temperature is equal to or higher than the target temperature by the valve opening output means, and when the detected temperature is less than the target temperature, a certain amount is closed. When the operation of the expansion valve changes from the opening operation to the closing operation, the maximum valve opening calculation means for setting the valve opening immediately before the closing operation to the maximum opening, and when the closing operation changes to the opening operation A minimum valve opening calculating means for setting the valve opening immediately before the opening operation to the minimum valve opening, and an average valve opening calculating means for obtaining an average valve opening from the maximum valve opening and the minimum valve opening And the output of the average valve opening calculation means to the valve opening calculation means Then, while maintaining the valve opening of the expansion valve, when the output of the average valve opening calculating means occurs, the temperature dead zone in which the target temperature and the temperature detecting means are not compared, the target temperature In a control device equipped with a temperature dead zone generating means that is generated so as to straddle the plus side and the minus side in the center, a valve resolution that generates a region for correcting the valve opening degree of the expansion valve on the plus side and the minus side of the temperature dead zone A control device for a refrigeration cycle, comprising: a correction area generating means; and a valve opening correction amount calculation means for obtaining a correction amount from outputs of the detected temperature and the target temperature. 2. A refrigeration cycle is constituted by a compressor, a heat exchanger, an expansion valve, etc., the temperature of a predetermined portion of the previous refrigeration cycle is detected by a temperature detecting means, and the detected temperature and the target determined by the target temperature setting means. The temperature comparison means compares the temperatures, and when the detected temperature is equal to or higher than the target temperature, the expansion valve is opened by a certain amount, and when the detected temperature is less than the target temperature, a certain amount is closed and valve opening output means is provided. The control device of the refrigerating cycle, which is provided with hunting table calculation means for hunting the valve opening degree. 3. The method for controlling a refrigeration cycle according to claim 2, wherein the number of calculation result pulses of the valve opening is separated into a positive integer a and a decimal point number b, and the valve opening is determined as (a + b). , Valve opening (a) maintenance time ΔT (a) and valve opening (a +
The maintenance time ΔT (a + 1) of 1) is ΔT (a): ΔT (a
+1) = (1-b): A control device for a refrigeration cycle that calculates the hunting table so that b and hunts the valve opening.