JPH07104052B2 - Refrigeration equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a refrigerating apparatus including an electric expansion valve and a compressor whose rotational speed can be changed according to a refrigerating load.

(B) Conventional Technology As a conventional refrigerating apparatus of this type, there is one shown in Japanese Patent Application No. 61-20748.

This content is that when the power supply frequency becomes high (low) within a certain time after the start of operation of the compressor, the opening degree of the electric expansion valve is made large (small), and after a certain time, the refrigerant discharged from the compressor The temperature is set to the temperature of the normal operating state of the compressor.

(C) Problems to be Solved by the Invention In such a refrigeration system, when the refrigeration load is too large or too small after a certain period of time, the temperature of the refrigerant discharged from the compressor is set to the normal operating state. Had to be changed from the value specified in 1) to the value specified during overload operation or the value specified during low load operation.

That is, since the temperature of the refrigerant discharged from the compressor is corrected depending on the size of the refrigeration load after the elapse of a certain period of time, the time from the start of operation of the compressor to the refrigerant discharge temperature according to the load may be long. there were.

An object of the present invention is to stabilize the operation of the compressor in a short time by shortening the time from the start of operation of the compressor to the discharge temperature of the refrigerant according to the load.

(D) Means for Solving the Problems In order to achieve this object, the present invention is provided between a compressor whose capacity is changed by fluctuations of a power supply frequency to be supplied, and an outdoor heat exchanger and an indoor heat exchanger. In a refrigeration system provided with an electric expansion valve provided, the control device for controlling the opening degree of the electric expansion valve is configured so that the temperature of the refrigerant in the refrigeration system becomes a target temperature. First control means for controlling the opening degree of the valve from a fully closed state to a predetermined opening degree;
The target opening of the electric expansion valve is changed to the maximum target opening that is different from the predetermined opening and is closed based on the outside air temperature, and the maximum target opening is connected to these maximum target openings. A storage unit that stores a plurality of data indicating changes and a second control unit that controls the opening of the electric expansion valve to reach the target opening are provided. During the initial time until the temperature of the refrigerant becomes substantially constant, the second control means controls the opening degree of the electric expansion valve, and after the elapse of the predetermined time, the first control means controls the opening degree. The opening degree of the electric expansion valve is controlled.

(E) The opening of the electric expansion valve is adjusted in advance according to the outside temperature at the start of operation, and the temperature of the refrigerant discharged from the compressor after the initial time has elapsed is set to the discharge temperature set according to the load of the compressor. I try to get closer to.

(F) Embodiment 1 In FIG. 1, 1 is a separation type air conditioner, which is composed of an indoor unit 2, an outdoor unit 3, and an inter-unit pipe 4 connecting both units. The indoor unit 2 incorporates an indoor heat exchanger 5 that functions as an evaporator during cooling operation and as a condenser at the start of heating operation.

On the other hand, the outdoor unit 3 includes a compressor 6, a four-way valve 7, an outdoor heat exchanger 8 that functions as a condenser during cooling operation and an evaporator during heating operation, a strainer 9, and an electric expansion valve 10. The dayhide 11, the muffler 12, and the accumulators 13 and 14 are connected by a refrigerant pipe. A bypass pipe 15 bypasses the four-way valve 7, the indoor heat exchanger 5 and the electric expansion valve 10. The bypass pipe 15 is provided with an opening / closing valve 16. The on-off valve 16 is opened during the defrosting operation so that the high-temperature refrigerant discharged from the compressor 6 flows directly to the outdoor heat exchanger 8 as indicated by the one-dot chain line arrow. Reference numeral 17 is a control device for the electric expansion valve 10 and the compressor 6.

Reference numeral 18 denotes a temperature-sensitive element mounted on the discharge pipe 19 of the compressor 6, which detects the temperature of the refrigerant discharged from the compressor 6.
When the cooling operation is performed, the rotation speed of the compressor 6 is changed by the input from the frequency output power supply device that can change the power supply frequency to 30 Hz to 85 Hz, and the refrigerating capacity can be changed to 1320 cal / h to 2750 cal / h. Also, the power supply frequency during heating operation is 30Hz
It is possible to change the refrigerating capacity from 1350cal / h to 4100cal / h by the input from the frequency output power supply that can change to 125Hz.

One output side wiring 20 of the control device 17 is connected to the motor of the electric expansion valve 10. The other output side wiring 21 is connected to the compressor 6. Further, the first input side wiring 22 is the indoor temperature detecting element 23, the second input side wiring 24 is the temperature sensing element 18 of the refrigerant pipe 19 of the compressor 6, and the third input side wiring 25 is the outdoor heat exchange. Each of the temperature sensitive elements 27 of the refrigerant pipes 26 connected to the container 8 is connected to each other.

Then, during the cooling operation, the four-way valve 7 is set to the solid line state, and the refrigerant is flown as indicated by the solid line arrow in FIG. On the other hand, during the heating operation, the four-way valve 7 is set in a broken line state and the refrigerant flows as indicated by a broken line arrow. Further, during the defrosting operation, the on-off valve 16 is opened while the four-way valve 7 is held in the broken line state, and a part of the high temperature refrigerant discharged from the compression device 6 is made to flow as indicated by the one-dot chain line arrow.

The electric expansion valve 10 has a valve opening which can be changed by driving a built-in pulse motor. Ie the second
As shown in the figure, the opening degree of the valve is proportional to the number of pulses. For example, if the valve is fully open at 500 pulses, the valve is half-opened with 250 pulses and closed with 0 pulses. Therefore, the opening of the valve will be indicated by the number of pulses.

The power supply frequency input to the compressor 6 at the start of the cooling and heating operations is set as shown in the table below according to the difference ΔT ₁ between the room temperature and the set temperature.

The third frequency corresponding to the frequency (x) set in this way
As shown in the figure, the opening y of the electric expansion valve 10 (indicated by the number of pulses as described above, the larger the number, the larger the opening) is generally expressed by the following equation.

y = Ax + B A: Constant determined by the displacement volume of the compressor B: Constant determined by the operating condition and the outside air temperature Here, A = 1, B is 101 at the start of cooling operation, and the outside air temperature is 4
It is 76 at the start of heating operation above ℃ and 43 at the start of heating operation at outside temperature of 4 ℃ or less. Y ₁ is the valve opening degree at the start of cooling operation and y ₂ is the start of heating operation at outside air temperature of 4 ℃ or above. When the valve open degree at the time of starting the heating operation when the outside air temperature is 4 ° C. or less, y ₃ is represented by the following equations.

_{y 1 = x + 101 (x} <100), y 1 = 201 (x ≧ 100), y 2 = x + 76 (x <100), y 2 = 176 (x ≧ 100), y 3 = x + 43 (x <100 ), Y ₃ = 143 (x ≧ 100), FIG. 4 shows the relationship between the operating frequency after a lapse of a certain time from the start of operation and the target temperature (described later) of the refrigerant discharged from the compressor.

FIG. 5 is a flow chart showing the procedure of operation control of the compressor and control of the motor-operated valve.

In FIG. 5, when the operation of the air conditioner 1 is started, an 8-minute timer for measuring the initial time is started (step 50). Then, the room temperature T _a is measured and the set temperature T _s is detected, and the difference ΔT _l between T _a and T _s is obtained. Then, based on the power supply frequency corresponding to ΔT _l (see table above), the compressor 6
Are driven (step 51 to step 55).

When the operation of the compressor 6 is started in this way, the outside air temperature is measured especially during the heating operation, and the opening characteristic of the electric expansion valve 10 as shown in FIG. Electric expansion valve based on the data stored in the section)
The opening and closing of 10 is performed (step 56 to step 59).

In this way, the compressor 6 and the motor-operated valve 10 are controlled based on ΔT _{l and the} outside air temperature for 8 minutes from the start of operation (step 60). Then, it is considered that the temperature of the refrigerant discharged from the compressor 6 has become stable 8 minutes after the start of operation. △ after 8 minutes
At the same time as calculating T _l , the temperature sensor 27
The temperature T _d of the refrigerant flowing into (during heating operation) is detected. Next, as shown in FIG. 4, when the refrigerant temperature T _d is relatively high (low), it is determined that the air conditioner is in the over (low) load operation state, and in accordance with each operation frequency, The target temperature T _{b of the} refrigerant discharged from the compressor 6 is calculated (step 61
~ Step 66). Next, the temperature sensitive element 19 obtains the difference ΔT ₂ between the temperature T _{c of} the refrigerant discharged from the pressure end device 6 and the target temperature T _b (steps 67 to 68). If ΔT ₂ is 0 or more, the opening degree of the electric expansion valve is increased. On the other hand, if ΔT ₂ is 0 or more, the opening degree of the electric expansion valve 10 is reduced (step 69 to step
71). In this way, even if the outside air temperature becomes high (low) and the refrigerant temperature T _{c accordingly} becomes high (low), the electric expansion valve 10 is always kept at the temperature T _b corresponding to the frequency.
The opening degree of is adjusted.

In this way, when the outside air temperature is low at the start of heating operation (when the compressor is in low load operation after the initial time has elapsed)
The electric expansion valve is controlled by squeezing. Then, the refrigerant discharged from the compressor is brought close to the target temperature of the refrigerant during the overload operation after the initial time has elapsed. On the other hand, when the outside air temperature is high (when the compressor is overloaded after the initial time elapses), the electric expansion valve is controlled to be fully opened. Then, the temperature rise of the refrigerant discharged from the compressor is suppressed to approach the target temperature of the refrigerant during the overload operation after the initial time has elapsed.

(G) Effect of the Invention As described above, according to the refrigerating apparatus of the present invention, the electric expansion valve is optimally throttled by the outside air temperature within the initial time until the temperature of the refrigerant discharged from the compressor stabilizes. Since the control can be performed in the open state, the temperature of the refrigerant can reach the target value in a short time. Therefore, the operation of the compressor can be stabilized in a short time.

[Brief description of drawings]

The drawings show a refrigerating apparatus of the present invention. FIG. 1 is a refrigerant circuit diagram of the apparatus, and FIG. 2 is an explanation showing a relationship between a valve opening degree and a pulse number of an electric expansion valve incorporated in the apparatus. 3 and 4 are explanatory diagrams showing the relationship between the operating frequency and the number of pulses (valve opening) at the start of operation of the compressor, and FIG. 4 is the operating frequency and target of the refrigerant after the initial time of the compressor. FIG. 5 is an explanatory view showing the relationship with the temperature, and FIG. 5 is a flowchart showing the processing procedure of the apparatus. 5 ... Indoor heat exchanger, 6 ... Compressor, 8 ... Outdoor heat exchanger, 10 ... Electric expansion valve, 17 ... Control device.

Claims (1)

[Claims] 1. A refrigeration system provided with a compressor, the capacity of which is changed by fluctuations of a power supply frequency to be supplied, and an electric expansion valve arranged between an outdoor heat exchanger and an indoor heat exchanger, The control device for controlling the opening degree of the electric expansion valve,
Based on the outside air temperature, first control means for controlling the opening degree of the electrically driven expansion valve from a fully closed state to a predetermined opening degree so that the temperature of the refrigerant in the refrigeration system becomes a target temperature. Differently, the opening that is closed from the predetermined opening is set as the maximum target opening, and a plurality of openings that are connected to these maximum target openings and that indicate changes in the target opening of the electric expansion valve with respect to changes in the power supply frequency are displayed. A storage unit for storing data, and a second control for controlling the opening degree of the electric expansion valve to be the target opening degree.
And a control means for controlling the opening degree of the electrically driven expansion valve by the second control means within an initial time from the start of operation of the compressor until the temperature of the refrigerant becomes substantially constant, The refrigerating apparatus, wherein the opening degree of the electric expansion valve is controlled by the first control means after the lapse of the predetermined time.