JPH0257770A - Control device for motor-driven expansion valve - Google Patents

Abstract

PURPOSE:To provide a control device for a motor-driven expansion valve to stabilize a refrigerant circuit quickly by opening the valve till a preset degree of opening simultaneously with start of a compressor, and determining the degree of valve opening in accordance with pressure difference in front of and behind the valve after passage of a certain period of time. CONSTITUTION:A motor- driven expansion valve 13 is opened (ST2) till a preset degree of valve opening V1 by control devices 1, 8, 9 for the valve at the same time as starting (ST1) of a compressor. After passage (ST3) of a certain period of time T1, the pressure difference of the expansion valve 13 is sensed (ST4), and according to this pressure difference the degree of opening V2 of the expansion valve 13 is decided (ST5).

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for an electric expansion valve in a cooling/heating device.

[Conventional technology]

FIG. 5 is a well-known refrigerant circuit diagram of a conventional cooling/heating device, such as a cooling device. In the figure, 21 is a compressor;
2 is a heat source side heat exchanger, 23 is a temperature type expansion valve which is a pressure reducing device, 24 is a user side heat exchanger, 25 is a temperature sensing cylinder as a temperature sensor, and 26 is temperature data detected by this temperature sensing cylinder 25. This is a signal line that is supplied to the temperature type expansion valve 23 as a control signal.

Next, the operation will be explained. After the cooling device is started, the temperature-type expansion valve 23 is operated with its opening degree controlled by the temperature data detected by the temperature-sensitive tube 25 at that time.

[Problem to be solved by the invention]

Since the control device for the electric expansion valve in the conventional heating/cooling device is configured as described above, when the power is turned on to the heating/cooling device and the compression a21 is started, the thermostatic expansion valve 23 is operated as a temperature-sensitive The opening degree of the valve is controlled when the degree of superheating of the cylinder 25 is 0, and therefore the opening degree of the valve at that time is O1, that is, the valve starts as closed. Thereafter, the temperature-type expansion valve 23 opens in accordance with changes in the pressure and temperature of each part that change with the operation of the compressor 21.

As a result, there is a problem that the low pressure decreases when the heating/cooling device is started, and it takes a long time for the temperature and pressure in the refrigerant circuit to stabilize.

This invention was made to solve the above-mentioned problems, and it is possible to prevent a drop in low pressure at the time of starting the device, and also to reduce the temperature in the refrigerant circuit.

It is an object of the present invention to provide a control device for an electric expansion valve that can quickly stabilize pressure after starting the device.

[Means to solve the problem]

The electric expansion valve control device according to the present invention opens the electric expansion valve to a preset opening degree at the same time as the start of the compressor, and then, after a certain period of time, opens the electric expansion valve before and after the electric expansion valve. The configuration is such that pressure is detected and control is added to determine the opening degree of the electric expansion valve in accordance with the detected pressure.

[For production]

The electric expansion valve control device of the present invention detects the pressure difference before and after the electric expansion valve and determines the degree of opening based on that pressure, thereby preventing a drop in low pressure during startup.
In addition, the refrigerant circuit quickly reaches a stable opening.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the drawings, parts that are the same as those in FIG. 13 is an electric expansion valve as a pressure reducing device, l is a control circuit as a control device for controlling the opening degree of this electric expansion valve 13, and 8 is provided in an inlet pipe on the input side of the electric expansion valve 13. A pressure detection device 9 is a pressure detection device as another control device provided in the outlet piping on the output side of the electric expansion valve 13.

FIG. 2 is a circuit diagram mainly showing the specific configuration of the control circuit 1, in which 2 is a central processing unit that is a CPU, 3 is a program storage device that is a ROM that stores programs to be executed by this central processing unit 2; 4 is a data storage device consisting of a RAM; 5 is an analog input conversion circuit that receives analog detection signals from the pressure detection devices 8 and 9 and converts them into digital signals; 6 is a digital input conversion circuit that receives the start signal 11; circuit, 7 is a drive circuit for the electric expansion valve 13;
14 is an internal bus.

Next, the operation will be explained with reference to the flowchart in FIG. 3 and the graph in FIG. 4. When the power is turned on to the cooling device having the refrigerant circuit shown in FIG. The following control operations are performed in sequence.

That is, immediately after starting the compressor 21, the process of step ST2 is first executed, and the electric expansion valve 13 is set to a preset opening degree V and starts to operate. Thereafter, it is determined by the process in step ST3 whether or not a predetermined set time T has elapsed, and when it is confirmed that the predetermined set time T1 has elapsed, the process in step ST4 is then performed. The refrigerant pressures Pi and Psi are read by the pressure detection device 8.9 disposed on the output side of the electric expansion valve 13, that is, before and after the electric expansion valve 13, and the analog manual conversion is performed. Through circuit 5, central processing bag W2
is supplied to Therefore, the central processing unit 2 next executes the process of step ST5. That is, a new opening degree v2 of the electric expansion valve 13 is determined by referring to an internal table from the read and detected pressures Pi and Psi, and this is supplied to the electric expansion valve 13 via the drive circuit 7. do.

Note that in the above embodiment, control of the electric expansion valve 13 at the time of starting the compressor 21 was shown, but in a cooling system having a plurality of user-side heat exchangers 24 The present invention may be used for time control.

Further, the pressure at the outlet of the electric expansion valve 13 may be detected by providing a temperature detection device, and the detected temperature may be converted into pressure.

Further, although the above embodiments have been described with respect to a cooling device, the present invention may also be applied to a heat pump device as a heating device.

〔Effect of the invention〕

As described above, according to the present invention, the control device for the electric expansion valve of the cooling/heating device starts the electric expansion valve at a preset opening degree when the cooling/heating device is started, and After a predetermined period of time has passed after this startup, the pressure on the input and output sides of the electric expansion valve is detected, a new opening degree is determined according to this detected pressure, and the electric expansion valve is operated according to the opening degree. This configuration has the effect of quickly stabilizing the refrigerant circuit and preventing the low pressure from decreasing when the compressor is started.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram in a cooling device according to an embodiment of the present invention, Fig. 2 is a detailed circuit diagram of the control circuit 1, Fig. 3 is a flowchart showing the operation of the control circuit 1, and Fig. 4 is an electric expansion FIG. 5 is an explanatory diagram illustrating the opening state of the valve 13, and is a refrigerant circuit diagram in a conventional cooling device. 1 is a control circuit (control device), 2 is a central processing unit, 3 is a program storage device, 4 is a data storage device, 7 is an electric expansion valve drive circuit, 8 and 9 are pressure detection devices (control device), 1
3 is an electric expansion valve, 21 is a compressor, 22 is a heat source side heat exchanger, and 24 is a usage side heat exchanger. In addition, in the figures, the same symbols indicate the same or equivalent parts.

Claims (1)

[Claims] In a control device for an electric expansion valve of a cooling/heating device,
When the cooling/heating device is started, the electric expansion valve is started at a preset opening degree, and after a predetermined period of time has elapsed after the start, the electric expansion valve is opened to a new opening degree according to the pressure on the input and output side of the electric expansion valve. A control device for an electric expansion valve, characterized in that the electric expansion valve is operated according to the opening degree.