JPS6345031B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the control of an electric expansion valve in a refrigeration cycle, and in particular, when controlling the amount of superheat of refrigerant sucked into a compressor, the amount of superheat is not kept constant; When the outside temperature is low during operation, performance is prioritized over EER and super heat is increased.

A conventional device of this type is shown in FIG. For example, during heating, high-temperature, high-pressure refrigerant discharged from the compressor 1 passes through the four-way valve 2, is condensed and liquefied in the indoor heat exchanger 3, passes through the check valve 18, is depressurized and expanded in the expansion valve 4, and is It reaches the accumulator 6 from the valve 19 via the outdoor heat exchanger 5 and the four-way valve 2. From here, the low-pressure refrigerant gas is sucked into the compressor 1 through the suction pipe 7, and the same cycle is repeated again.

At this time, the expansion valve 4 performs so-called superheat control in which the temperature of the refrigerant gas sucked into the compressor 1 is detected as the amount of superheat within the temperature sensing cylinder 20. Note that 16 and 17 are also check valves.

Conventionally, a thermostatic automatic expansion valve as shown in FIG. 2 has been used as a device for controlling super heat. In FIG. 2, the valve body 4 is provided with a refrigerant inlet 21 and a refrigerant outlet 22, and a valve port 2 is provided inside.
A spindle 24 having a valve part for controlling the opening degree of 3 and a spring 25 acting on the spindle 24 are housed. One end of the spindle 24 is connected to a diaphragm 27 installed in a temperature sensing cylinder chamber 26 directly connected to the temperature sensing cylinder 20 .

The vertical movement of the diaphragm 27 causes the spindle 2 to
4 moves, and the opening degree of the valve port 23 is controlled. Therefore, in such a structure, since the amount of superheat is adjusted by the spring 25, the absolute value of superheat itself cannot be detected, and it is not possible to control it to an arbitrary value that is optimal for the operating condition. .

This invention was made to eliminate the above-mentioned conventional drawbacks, and the temperature near the confluence of the suction pipe and the branch pipe from the bypass path of the electric expansion valve is subtracted from the temperature of the suction pipe to generate super heat. perform calculations,
And when the saturation temperature T _s near the confluence point is lower than the set temperature T ₀ , the target super heat SH is set as T ₃ < SH < T ₄ .
When the saturation temperature T _s is higher than the set temperature T ₀ , the target superheat SH is set to T ₁ < SH < T ₂ (T ₁ < T ₂ < T ₃ < T ₄ )
It is an object of the present invention to provide an electric expansion valve control device that can perform detailed operation control in consideration of comfort and energy saving.

Embodiments of the electric expansion valve control device of the present invention will be described below with reference to the drawings. FIG. 3 is a refrigeration circuit diagram showing the configuration of one embodiment, and is a schematic diagram when selecting the amount of superheat by the electric expansion valve during heating operation of the refrigeration cycle.

In this Fig. 3, 1 is a compressor, and the high-temperature, high-pressure refrigerant gas compressed here passes through a four-way valve 2 and is condensed and liquefied in an indoor heat exchanger 3. The pressure is reduced by the adjustable electric expansion valve 4, evaporated by the outdoor heat exchanger 5, the flow path is switched by the four-way valve 2, and reaches the accumulator 6, where it is sucked into the compressor 1 through the suction pipe 7 and repeats the same cycle. It's becoming repetitive.

It also has a bypass path 11 that connects both ends of the electric expansion valve 4, and capillary tubes 8 and 9 are provided in the middle of this bypass path 11. A branch pipe 12 is connected to the compressor 1 from the middle of this bypass path 11.
It merges into the suction pipe 7 of. There is a capillary tube 10 in the middle of this branch pipe 12, a temperature sensor 13 is provided near the confluence point, and a temperature sensor 14 is also provided in the suction pipe 7.

The configuration is such that signals from the two temperature sensors 13 and 14 are sent to a controller 15, thereby outputting a signal instructing the opening degree of the electric expansion valve 4.

Next, the operation of the electric expansion valve control device of the present invention configured as described above will be explained. During heating operation, the high-pressure refrigerant liquid passes through the bypass path 11, expands adiabatically in the capillary tube 8, and then flows through the branch pipe 1.
2, the pressure is reduced to the pressure in the suction pipe 7 of the low-pressure compressor in the capillary tube 10, and the temperature sensor 13 indicates a saturation temperature corresponding to the suction pressure.

Further, this temperature corresponds to low pressure and has a certain correlation with the outside temperature, and if the outside temperature is low, the temperature sensor 13 will naturally indicate a low temperature.

On the other hand, since the temperature sensor 14 is attached to the suction pipe 7, it indicates the suction temperature. The detection outputs of these two temperature sensors 13 and 14 are sent to the controller 15.
The amount of superheat is calculated by the controller 15 based on these two detection outputs, and the opening degree of the electric expansion valve 4 is controlled.

Next, the state in which super heat control of the electric expansion valve 4 is executed based on the signals from the two temperature sensors 13 and 14 will be explained with reference to the flowchart shown in FIG.

In the figure, Ti is the suction temperature, Ts is the saturation temperature,
This is a signal that is detected at certain fixed time intervals and sent to the controller 15. When these two signals are sent to the controller 15 in step A, the controller 15 can calculate the superheat amount SH=Ti-Ts in step B.

Next, in step C, when the saturation temperature Ts is below a certain set value _T0 , this corresponds to a low outside temperature, and the heating capacity is supposed to be insufficient. That time
In order to perform performance-oriented operation even if EER is ignored, the superheat amount SH is set from a certain setting value T ₃ .
I want to keep it between _T4 (Step D).

Furthermore, when the saturation temperature Ts is higher than a certain set value T ₀ , it is desirable to perform an operation that prioritizes EER over heating capacity.

In the above points, what is particularly important is the superheat amount SH, heating capacity Q, and outside temperature (T ₀₁ >
As can be seen from the correlation with T ₀₂ ), when the outside temperature T ₀₂ is low, the capacity increases when the superheat amount SH is larger than when the outside temperature T ₀₁ is high.
As a result, the _set temperature in the flowchart _shown in FIG _.
The goal is to satisfy the relationship T ₄ .

Furthermore, when the superheat amount SH is less than the set width, a signal is issued in step E to open the opening E ^* of the electric expansion valve 4 in the direction of +ΔE, which is wider than the current opening E.
When the superheat amount SH is equal to or greater than the set width, a signal is output in step F in the direction of -k.ΔE in which the opening degree E ^* of the electric expansion valve 4 is closer than the current opening degree E.

As described above, according to the electric expansion valve control device of the present invention, the electric expansion valve is provided with a bypass path,
From this bypass path, a branch pipe having a capillary tube joins the suction pipe of the compressor, and when the saturation temperature T _s near the joining point is lower than the set temperature T ₀ ,
When the target super heat SH is T ₃ < SH < T ₄ and the saturation temperature T _s is higher than the set temperature T ₀ , the controller opens the electric expansion valve so that the target super heat SH becomes T ₃ < SH < T ₄ . Since we decided to perform degree control,
Under standard temperature conditions, the expansion valve opening is given priority to EER, and when heating capacity is insufficient at low temperatures, the opening is given priority to capacity, making it possible to perform fine-grained operation control that takes comfort and energy conservation into consideration. be.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional refrigeration cycle, Figure 2 is a sectional view showing the configuration of a conventional thermostatic expansion valve, and Figure 3 is a schematic diagram of a conventional refrigeration cycle.
The figure is a refrigerant circuit diagram of one embodiment of the electric expansion valve control device of the present invention, FIG. 4 is a flowchart showing the calculation and judgment of the controller in the electric expansion valve control device of FIG. 3, and FIG. FIG. 2 is a schematic diagram showing the correlation between outside temperature, superheat amount, and heating capacity. 1... Compressor, 2... Four-way valve, 3... Indoor heat exchanger, 4... Electric expansion valve, 5... Outdoor heat exchanger, 6... Accumulator, 7... Suction pipe, 8
~10... Capillary tube, 11... Bypass path, 12... Branch pipe, 13, 14... Temperature sensor. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A refrigeration cycle in which a compressor, a four-way valve, an indoor heat exchanger, an electric expansion valve, an outdoor heat exchanger, and an accumulator are connected in a ring, including a bypass passage connecting both ends of the electric expansion valve. The first and second pipes are connected in series in the middle of this bypass passage.
A capillary tube is provided, and the connection point of the first and second capillary tubes is connected to the suction pipe of the compressor via a branch pipe having a third capillary tube, and the temperature near the confluence point is A first temperature sensor is provided to detect the temperature of the suction pipe, a second temperature sensor is provided to detect the temperature of the suction pipe, and the value detected by the first temperature sensor is subtracted from the value detected by the second temperature sensor. Calculate the amount of superheat and detect the saturation temperature of the first temperature sensor.
Target super heat when T _s is lower than set temperature T ₀
SH is set as T ₃ < SH < T ₄ (T ₃ and T ₄ are set values), and when the detected saturation temperature T _s is higher than the set temperature T ₀ , the target superheat SH is set as T ₁ < SH < T ₂ ( _T1 ,
An electric expansion valve control device characterized in that a controller controls the opening of the electric expansion valve so that T ₂ is a set value and T ₁ <T ₂ <T ₃ <T ₄ .