JPS5995347A - Controller for electric type expansion valve in refrigeration cycle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for an electric expansion valve in a refrigeration cycle that detects the amount of superheat of refrigerant sucked into a compressor and controls the entire opening of the electric expansion valve based on the detected amount.

Conventionally, a thermostatic automatic expansion valve has been used as a pressure reducing device in the refrigeration cycle, but since a thermosensitive cylinder is brought into contact with the piping in the section that controls the amount of superheat, and changes in temperature are converted into changes in pressure, the response is is delayed. For this reason, it has the disadvantage that it is unable to follow rapid load fluctuations, and tends to cause liquid puddles or hunting.

Further, since the amount of superheat is not directly detected, it is impossible to arbitrarily control the superheat i to the optimum level that matches the operating state of the air conditioner.

Furthermore, the conventional electric expansion valve that detects the amount of superheat as a control signal detects the temperature Te at the inlet or intermediate part of the evaporator and the compressor inlet fTs, and easily detects the amount of superheat. SH = Ts −
Although Te is used, there is a pressure drop at the evaporator inlet, middle part, and compressor inlet, and the amount of this drop changes depending on the operating conditions, making it impossible to accurately detect the amount of superheat.

In addition, there is a system that includes a pressure sensor and a temperature sensor at the inlet of the compressor to detect the amount of superheat. However, since the pressure sensor is expensive, it has the disadvantage of increasing the cost of the equipment.

This invention was made in order to eliminate the above-mentioned drawbacks of the conventional technology, and includes an external calculation function that detects the absolute value of the amount of superheat of the refrigerant sucked into the compressor, and calculates the superheat amount from that superheat amount to a preset amount of superheat. By using a controller that has a judgment function, the electric expansion valve is driven, and in order to protect the compressor, the operation of closing the electric expansion valve is faster and larger than the operation of opening the electric expansion valve. The electric expansion valve in the refrigeration cycle not only can maintain the optimal amount of superheat and protect the compressor, but also improve reliability and coefficient of performance. The purpose is to provide a control device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a control device for an electric expansion valve in a refrigeration cycle according to the present invention will be described with reference to the drawings. 1st
The figure is a schematic refrigeration circuit diagram of one embodiment. Reference numeral 1 in FIG. 1 indicates a compressor, and the high-temperature, high-pressure refrigerant gas compressed here reaches a four-way valve 2.

During cooling operation, from the four-way valve 2 to the outdoor heat exchanger 3,
It is condensed and liquefied, the pressure is reduced by the electric expansion valve 4, and it is evaporated and gasified by the indoor heat exchanger 5, and then enters the accumulator 6. Refrigerant gas is sucked into the compressor 1 again from the accumulator 6, and the circulation is repeated thereafter.

Reference numeral 11 denotes a bypass path that bypasses both ends of the electric expansion valve 40, and has capillary tubes 7 and 8 in the middle, and a tube 1 that branches off from the middle of each capillary tube 7 and 8.
0, the pressure is reduced in the capillary tube 9, and the suction pipe 1
5.

Immediately before the branch pipe 10 joins the suction pipe 15, a temperature sensor 13 and a temperature sensor 12 are installed downstream of the joining point 9, and the signals from the two temperature sensors 12 and 13 are sent to the controller 1.
4, and this controller 14 calculates the amount of superheat,
A judgment is made and a signal is sent to the electric expansion valve 4.

Next, the operation of the electric expansion valve control device in the refrigeration cycle of the present invention configured as described above will be explained. The high-pressure liquid refrigerant flows into the bypass circuit 11 from both ends of the electric expansion valve 4 during both cooling and heating operation, is depressurized through the branch pipe 1o, and near the junction with the suction pipe 15 is a low-pressure suction. A saturation temperature corresponding to the suction pressure is obtained.

Finally, the temperature sensor 13 indicates the saturated fLl temperature corresponding to the suction pressure, and the saturation temperature corresponding to the suction pressure can always be obtained without being affected by pressure drop due to the length of the indoor heat exchanger 5 and the indoor 1110 unit connection piping. It turns out.

Further, the temperature sensor 12 detects the temperature increase and increase in temperature, and the difference between the two temperature sensors 12 and 13 is directly calculated in the controller 14 as the superheat amount.

Next, the calculations in the controller 14 and the +IJ cutter embodiment will be explained with reference to the flowchart shown in FIG. In this Figure 2, Ti of the refrigerant gas of the pressure M machine 1 is the suction temperature, Ts is the saturation temperature, SH is the superheat amount, and 5
)41, SH2 is the set value, E is the opening of the electric expansion valve at the time of detection, E8 is the opening degree of the electric expansion valve at the time of the next command, △
E indicates the opening degree, and K indicates a constant.

In FIG. 2, the saturation temperature Ts measured by the temperature sensor 13 and the suction temperature Ti measured by the temperature sensor 12 shown in FIG. 1 are read at every fixed time Δ, which is step A.

Next, in step B, the difference between the suction temperature Ti and the saturation temperature Ts is calculated as the superheat amount SH.

Next, the process moves to step C, and if the calculated superheat amount 81 (is larger than the set value SHI but smaller than SH2), the process returns from step C to step A and the opening degree E of the electric expansion valve 4 is
2, leave it as it is and measure △ again after a period of time.

Further, in step C'', when the calculated superheat amount is larger than the set value SH2, the process moves from step C to step F, and the opening degree E8 of the electric expansion valve 4 outputs a signal ΔE in the opening direction.

Generally, when the calculated superheat amount SH is less than the set value SHI (step D), the opening degree E2 of the electric expansion valve 4 is changed to a signal 1 in the closing direction in step E.
Play E.

What is unique here is that the signal for the width that opens the electric expansion valve 4 is △E, while the signal for the width that closes the electric expansion valve 4 is -R・△E (R>1). In other words, the width that can be closed is large.

This is because the closing speed or closing amount is increased in order to avoid liquid compression as much as possible in order to protect the compressor 1.

As described above, according to the control device for an electric expansion valve in a refrigeration cycle of the present invention, the absolute amount of superheat is detected on the refrigerant suction side of the compressor, and the amount of superheat is adjusted to a preset amount. External calculations and judgments are performed by a controller, and this controller drives the Shimi pneumatic expansion valve.
J control has the advantage of protecting the compressor while maintaining the optimum amount of superheat, and it is possible to improve the reliability of the refrigeration cycle operation and the base area coefficient.

[Brief explanation of drawings]

FIG. 1 is a refrigeration circuit diagram of an embodiment of the electric expansion valve control device in the refrigeration cycle of the present invention, and FIG. It is a flowchart outlining the functions of 11fi. 1...Pressure machine, 2...Four-way valve, 3...Outdoor heat exchange inspection, 4...Electric expansion valve, 5...Indoor Feng II
Seven heat exchange tests, 6...Accumulator, 7-9...Capillary tube, 10...Branch w, tl.../6
Inokusu tube, 12.13...Temperature sensor, 14...
Controller, 15...Inhalation'iGf.゛ Agent Jo Kuzuno −

Claims (1)

[Claims] In a refrigeration cycle in which a compressor, a four-way valve, an outdoor refrigerant converter, an electric expansion valve, an indoor heat exchanger, and an accumulator are all connected in a ring, a detection system that detects the total amount of superheat of the refrigerant sucked into the compressor. and the detection means detected by this detection means.
refrigeration comprising a controller that controls the degree of opening of the electric expansion valve based on the amount of superheat generated, and controls the amount or speed at which the electric expansion valve is closed to be greater than the amount or speed at which it opens. Cycle electric expansion valve control device.