KR20030043038A - Refrigerating cycle and control method - Google Patents

Abstract

PURPOSE: A refrigerating cycle and the control method are provided to have a bypass path to prevent high-side pressure for protection of a compressor and a system of a refrigerating cycle from excessively rising. CONSTITUTION: A refrigerating cycle comprises a compressor(52) compressing a refrigerant into a gas refrigerant of high temperature and high pressure; a condenser(54) heat-exchanging the gas refrigerant discharged from the compressor with outdoor air and condensing the heat-exchanged refrigerant into a liquid refrigerant of medium temperature and high pressure; a first pressure-reducing unit(56) decompressing the liquid refrigerant passing through the condenser into a liquid refrigerant of low temperature and low pressure; an evaporator(58) heat-exchanging the liquid refrigerant passing through the first pressure-reducing unit with indoor air and evaporating the heat-exchanged refrigerant into a gas refrigerant of low temperature and low pressure; a second pressure-reducing unit(62) connecting the outlet side of the compressor and the inlet side of the evaporator; a valve(64) opening and shutting capillary tubes, to make the refrigerant of the high side flow into the low side; and a pressure switch(66) opening and shutting the valve according to the pressure sensed from a refrigerant line of the outlet of the compressor. Thus, excessive pressure rise of the refrigerant is prevented.

Description

Refrigeration cycle and control method {Refrigerating cycle and control method}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle, and more particularly to a refrigeration cycle constituting a bypass path and a control method thereof in order to prevent excessively high pressure side pressures for protecting the compressor and system of the refrigeration cycle.

In general, the refrigeration cycle is applied to an air conditioner, a refrigerator, or the like to perform cooling or cooling by moving the heat of the low temperature portion to the high temperature portion while the working fluid passes through the compressor, the condenser, the expansion valve, and the evaporator.

1 is a configuration diagram showing a conventional refrigeration cycle, Figure 2 is a cross-sectional view showing a reciprocating compressor including a pressure control valve according to the prior art, Figure 3 according to the outside conditions in the conventional refrigeration cycle The pressure and the temperature of the discharge refrigerant pipe of the compressor are graphs.

Conventional refrigeration cycle is a compressor (2) for compressing the refrigerant as shown in Figure 1, a condenser (4) for condensing the gas refrigerant compressed to high temperature and high pressure in the compressor (2) through heat exchange with outdoor air, and Expansion valve (6) for depressurizing the liquid refrigerant compressed to medium temperature and high pressure in the condenser (4), and an evaporator (8) for heat-exchanging the refrigerant decompressed to low temperature and low pressure while passing through the expansion valve (6) with indoor air. When cooling, indoor air is cooled while circulating the refrigerant compressor (2), condenser (4), expansion valve (6), evaporator (8), and when heating, the refrigerant circulates in reverse order to warm the room air.

When the air conditioner composed of the refrigeration cycle as described above is cooled, the discharge pressure and the temperature of the compressor 2 increase as the temperature of the outdoor side increases as shown in FIG. 2.

For example, the discharge temperature and the pressure of the compressor 2 under standard conditions (35/24 ° C.) are 80 ° C. and 20 kgf / cm ² , respectively, and the discharge temperature of the compressor 2 under the overload condition (54/24 ° C.). The pressures are 108 ° C. and 30 kgf / cm ² , respectively, so that the discharge temperature and pressure of the compressor 2 are higher when the outdoor temperature is particularly high.

That is, when an overload condition is applied to the refrigerating cycle, the refrigerant is not sufficiently heat exchanged by the outdoor air while passing through the condenser 4, and thus the compressor passes through the condenser 4, the expansion valve 6, and the evaporator 8. (2) is introduced into the temperature and pressure relatively higher than the standard condition, the refrigerant introduced as described above is out of the temperature and pressure range to ensure the reliability of the compressor (2) while being compressed in the compressor (2) the compressor This affects the reliability of (2).

Therefore, conventionally, a reciprocating compressor having high pressure resistance is used to secure the reliability of the compressor 2, or an internal pressure relief valve is provided between the high pressure portion and the low pressure portion inside the compressor 2.

Here, looking at the operation of the pressure regulating valve 10 installed in the reciprocating compressor, the refrigerant is sucked into the compression chamber (C) formed inside the cylinder block (4) through the suction pipe (3) as shown in FIG. When the shaft is eccentrically rotated, the connecting rod 6 converting the eccentric rotational force into a linear reciprocating motion is linear, so that the piston 8 connected to the connecting rod 6 moves the refrigerant in the compression chamber C to a high temperature and high pressure. The refrigerant compressed at high temperature and high pressure is discharged to the outside of the compressor 2 through the discharge tube 9.

At this time, if the temperature and pressure of the refrigerant flowing into the compressor (2) is out of the reliability of the compressor (2), the overload prevention mechanism is activated and before the circulation of the refrigeration cycle is temporarily stopped, the pressure control valve (10) ) Is activated to discharge the gas refrigerant from the high pressure side to the low pressure side, thereby reducing the overload caused by the compressor 2 temporarily.

However, the conventional refrigeration cycle using the pressure control valve installed in the compressor can temporarily prevent the overload on the compressor even if the refrigeration cycle is operated when the outdoor air is relatively high, the pressure control valve is a high temperature and high pressure from the high pressure portion to the low pressure portion Since the gas coolant is discharged, the pressure and temperature of the low pressure portion are increased, thereby raising the pressure and temperature of the refrigerant circulating in the refrigerating cycle as a whole.

The present invention has been made to solve the above-mentioned problems of the prior art, when the temperature of the outdoor air during the cooling operation of the refrigeration cycle is increased excessively by circulating the refrigerant of the refrigeration cycle through the bypass path, The purpose of the present invention is to provide a refrigeration cycle and a method of controlling the same, which can increase the cooling efficiency as well as increase the reliability of the compressor.

1 is a block diagram showing a conventional refrigeration cycle,

Figure 2 is a cross-sectional view showing a reciprocating compressor including a pressure control valve according to the prior art,

3 is a graph showing the pressure and the temperature of the discharge refrigerant pipe of the compressor according to the outside conditions in the conventional refrigeration cycle,

4 is a configuration diagram showing a refrigeration cycle according to the first embodiment of the present invention,

5 is a configuration diagram showing a refrigeration cycle according to a second embodiment of the present invention,

6 is a configuration diagram showing a refrigeration cycle according to a third embodiment of the present invention,

7 is a graph showing the suction pressure and temperature and the discharge pressure and temperature of the compressor when the bypass cycle of the refrigeration cycle according to the present invention,

8 is a flowchart illustrating a control method of a refrigeration cycle according to the present invention.

<Explanation of symbols on main parts of the drawings>

52 compressor 54 condenser

56: first reducing means 58: evaporator

62,72,82: second pressure reducing means 64,74,84: valve

66,76,86: Pressure switch

The refrigeration cycle according to the present invention for solving the above problems is a compressor for compressing the refrigerant into a gas refrigerant of high temperature and high pressure, a condenser for condensing the gas refrigerant discharged from the compressor with the medium temperature and high pressure liquid refrigerant by heat exchange with the outdoor air An expansion valve for reducing the liquid refrigerant passing through the condenser with a low temperature low pressure liquid refrigerant, an evaporator for exchanging the liquid refrigerant passing through the expansion valve with indoor air to evaporate it into a low temperature low pressure gas refrigerant, and an excessive pressure on the high pressure side. Consists of a bypass device that flows the refrigerant on the high pressure side to the low pressure side when the pressure rises,

The control method of the refrigeration cycle as described above is a pressure sensing step of detecting the pressure of the refrigerant pipe at the outlet side of the compressor during operation of the refrigeration cycle, and a signal that generates a control signal according to the pressure detected in the pressure sensing step is more than the set value And a bypass step of opening a bypass path connecting the high pressure side and the low pressure side by the signal generated in the signal generation step.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a configuration diagram showing a refrigeration cycle according to the first embodiment of the present invention, Figure 5 is a configuration diagram showing a refrigeration cycle according to a second embodiment of the present invention, Figure 6 is a third of the present invention A refrigeration cycle according to the embodiment is a configuration diagram.

In the refrigerating cycle according to the present invention, as shown in FIGS. 4 to 6, the refrigerant is compressed at high temperature and high pressure in the compressor 52, and the gas refrigerant having the high temperature and high pressure discharged from the compressor 52 is connected to the condenser 54. While passing through and condensed by heat exchange with the outdoor air forcedly blown by the indoor side blower (not shown), the medium-temperature high-pressure liquid refrigerant passing through the condenser 54 is decompressed while passing through the first pressure reducing means (56) The low temperature and low pressure liquid refrigerant that has passed through the first pressure reducing means 56 is exchanged with the indoor air forcedly blown by an indoor blower (not shown) while passing through the evaporator 58, and the compressor 52 again. And a bypass device is installed between the portion where the refrigerant circulating in the refrigeration cycle maintains a relatively high pressure (hereinafter referred to as the high pressure side) and the portion that maintains a relatively low pressure (hereinafter referred to as the low pressure side), so And flowing a refrigerant to give a pressure increase when the high-pressure side toward the low-pressure part.

In the first embodiment, as shown in FIG. 4, the second pressure reducing means 62 connects the outlet side of the compressor 52 to the inlet side of the evaporator 58 and the second pressure reducing means ( A valve 64 installed at the outlet 62 to open and close the second pressure reducing means 62 so that the refrigerant at the high pressure side flows to the low pressure side, and an outlet refrigerant pipe of the compressor 52 at the outlet of the compressor 52. It consists of a pressure switch 66 for opening and closing the valve 64 in accordance with the pressure sensed.

Here, the valve 64 receives the signal from the pressure switch 66 when the pressure sensed by the pressure switch 66 is greater than or equal to the set value (P ₀ ) by controlling the opening and closing of the second pressure reducing means (62). It is a solenoid valve for controlling the flow rate of the refrigerant flowing through the capillary tube (62).

Therefore, since the refrigerant flows into the inlet side of the evaporator 58 maintaining the low pressure from the outlet side of the compressor 52 which maintains the highest pressure state in the refrigerating cycle, the pressure on the high pressure side can be lowered most. .

In the first embodiment, when the outlet side pressure of the compressor 52 is greater than or equal to the set value P ₀ , a part of the refrigerant passes through the compressor 52, the capillary tube 62, and the evaporator 58, and then returns to the compressor 52 side. It will flow along the incoming bypass path.

In the second embodiment, as shown in FIG. 5, the first pressure reducing means 56 for reducing the medium and high pressure liquid refrigerant flowing from the condenser 54 according to the set flow resistance ratio, respectively, is provided by the expansion valve 56. The bypass device is divided into upper and lower parts 56a and 56b, and the bypass device includes second reducing means 72 connecting the outlet side of the compressor 52 and the inlet side of the lower portion 56b of the first reducing means, and A valve 74 provided at the second pressure reducing means 72 to open and close the second pressure reducing means 72 so that the refrigerant on the high pressure side flows to the low pressure side, and the compressor 52 at the outlet of the compressor 52; It consists of a pressure switch 76 for opening and closing the valve 74 in accordance with the pressure sensed in the outlet refrigerant pipe of the.

Here, the valve 74 also receives a signal from the pressure switch 76 when the pressure sensed by the pressure switch 76 is greater than the set value (P ₀ ) by adjusting the opening and closing of the second pressure reducing means (72) It is a solenoid valve for adjusting the flow rate of the refrigerant flowing through the second pressure reducing means (72).

In particular, when the flow resistance of the upper portion 56a of the first pressure reducing means is smaller than the flow resistance of the lower portion 56b of the first pressure reducing means, the refrigerant from the outlet of the compressor 52 flows into the inlet of the lower portion 56b of the second pressure reducing means. Therefore, the pressure on the high pressure side may not be significantly reduced, but since the pressure introduced into the evaporator 58 is low, the temperature of the indoor air that is heat-exchanged with the evaporator 58 may be greatly reduced.

On the other hand, when the flow resistance of the upper portion 56a of the first pressure reducing means is greater than the flow resistance of the lower portion 56b of the first pressure reducing means, the refrigerant from the outlet of the compressor 52 flows into the inlet of the lower portion 56b of the second pressure reducing means. Therefore, the pressure on the high pressure side is greatly lowered, but since the pressure flowing into the evaporator 58 is high, the temperature of the indoor air that is heat-exchanged with the evaporator 58 cannot be significantly lowered.

In the second embodiment, when the pressure at the outlet of the compressor 52 is equal to or higher than the set value P ₀ , the refrigerant is compressed into the compressor 52, the second pressure reducing means 72, the first pressure reducing means 56b, and the evaporator 58. ) And then flows along the bypass path, which flows back into the compressor (52).

In the third embodiment, as shown in FIG. 6, the bypass device includes second decompression means 82 connecting the outlet side of the condenser 54 and the inlet side of the compressor 52, and the second decompression means. A valve 84 provided at 82 to open and close the second pressure reducing means 82 to flow the refrigerant on the high pressure side to the low pressure side; and an outlet refrigerant of the compressor 52 at the outlet of the compressor 52. It consists of a pressure switch 86 for opening and closing the valve 84 in accordance with the pressure sensed in the pipe.

Here, the valve 84 also receives a signal from the pressure switch 86 when the pressure sensed by the pressure switch 86 is greater than the set value (P ₀ ) by adjusting the opening and closing of the second pressure reducing means (82) It is a solenoid valve for adjusting the flow rate of the refrigerant flowing through the second pressure reducing means (82).

Therefore, the third embodiment does not significantly lower the pressure on the high pressure side, but because the refrigerant flows into the compressor 52 without passing through the evaporator 58, the compressor 52 is overheated by evaporation of some bypassed refrigerant. By preventing the reliability of the compressor 52 can be secured.

In the third embodiment, when the pressure at the outlet of the compressor 52 is greater than or equal to the set value P ₀ , the refrigerant passes through the compressor 52, the condenser 54, and the second pressure reducing means 82, and the compressor 52 again. It will flow along the bypass path flowing into the side.

Here, the first pressure reducing means 56 and the second pressure reducing means 64, 74, and 84 may be configured in various forms such as an expansion valve or a capillary tube.

Looking at the operation of the present invention configured as described above are as follows.

When the temperature of the outdoor air is operated under an overload condition (over a set operating condition of the refrigerating cycle), since the refrigerant is not sufficiently heat exchanged in the condenser 54, the refrigerant cycles toward the compressor 52 at a relatively high temperature and high pressure while circulating the refrigeration cycle. The refrigerant introduced into the compressor 52 is compressed and discharged.

Here, when the pressure of more than the set value (P ₀ ) is sensed by the pressure switches (66, 76, 86) installed on the outlet side of the compressor 52, the pressure switches (66, 76, 86) are the second pressure reducing means (62). Signals flow through the second pressure reducing means (62, 72, 82) according to the opening and closing degree of the valves (64, 74, 84) by giving a signal to the valves (64, 74, 84) installed in the (72, 82) Done.

Thus, the refrigerant is circulated along the bypass path according to each embodiment from the high pressure side to the low pressure side.

7 is a graph showing the suction pressure and temperature and the discharge pressure and temperature of the compressor when the bypass of the refrigeration cycle according to the present invention.

When the bypass of the refrigeration cycle is applied as shown in Figure 7, the suction pressure and temperature of the compressor 52 is increased, the discharge pressure and temperature of the compressor 52 is the pressure and temperature to ensure the reliability of the compressor Will fall below.

Therefore, when the pressure P of the outlet of the compressor 52 sensed by the pressure switches 66, 76, 86 drops below the set value P ₀ , a signal from the pressure switches 66, 76, 86 is detected. The valves 64, 74, and 84 received are closed to bypass the bypass path, and the normal refrigeration cycle is operated so that the refrigerant is compressed by the compressor 52, the condenser 54, the first pressure reducing means 56, and the evaporator 58. Will cycle).

8 is a flowchart illustrating a control method of a refrigeration cycle according to the present invention.

The control method of the refrigeration cycle of the present invention configured as described above, first, when the power is applied to the compressor 52 in the first step valves (64, 74) for controlling the opening and closing of the second expansion valve (62, 72, 82) 84 remains off (see S1 and S2).

The second step detects the discharge side pressure P of the compressor 52 by the pressure switches 66, 76 and 86 (see S3).

In the third step, when the pressure P detected in the second step is smaller than the preset pressure P ₀ , the pressure switch 66, 76, 86 detects the discharge side pressure of the compressor 52, and the second step If the detected pressure P is greater than the preset pressure P ₀ , the control signals are generated at the pressure switches 66, 76 and 86 (see S4 and S5).

In the fourth stage, the valves 64, 74, and 84 are turned on by the control signal generated in the third stage, and the refrigerant flows along the bypass path through the second expansion valves 62, 72, and 82. The high pressure side moves the refrigerant to the low pressure side (see S6).

The fifth step again compares the pressure P sensed by the pressure switches 66, 76, and 86 with the preset pressure P ₀ , and if the detected pressure P is greater than the set pressure P ₀ , the valve 64. 74, 84) On state (refer to S7, S8)

However, when the pressure P sensed in the fifth step is smaller than the set pressure P ₀ , the valves 64, 74, 84 are turned off to block the second expansion valves 62, 72, 82. The zoom causes the refrigerant to circulate along the path of a normal refrigeration cycle (see S9).

In the refrigeration cycle and the control method of the present invention configured as described above is to increase the pressure of the refrigerant excessively by circulating the refrigerant of the refrigeration cycle through the bypass path when the outdoor air temperature is high during the cooling operation of the refrigeration cycle. By preventing the increase of the reliability of the compressor, there is an advantage that can increase the cooling efficiency.

Claims (6)

A compressor for compressing the refrigerant into a gas refrigerant of high temperature and high pressure, a condenser for condensing the gas refrigerant discharged from the compressor with outdoor air to condense it into a medium temperature high pressure liquid refrigerant, and a liquid refrigerant having passed through the condenser at low temperature and low pressure liquid refrigerant. A first decompression means for depressurizing the air, an evaporator for heat-exchanging the liquid refrigerant passing through the first decompression means with indoor air, and evaporating the gas refrigerant with a low temperature low pressure gas, and connecting the outlet side of the compressor and the inlet side of the evaporator. A second pressure reducing means, a valve installed at the second pressure reducing means to open and close the capillary tube to flow the refrigerant on the high pressure side to the low pressure side, and installed at the compressor outlet side according to the pressure sensed at the outlet refrigerant pipe of the compressor. Refrigeration cycle comprising a pressure switch for opening and closing the valve. A compressor for compressing the refrigerant into a gas refrigerant having a high temperature and high pressure, a condenser for condensing the gas refrigerant discharged from the compressor with outdoor air and condensing it into a liquid refrigerant having a medium temperature and high pressure, and a liquid refrigerant passing through the condenser at a predetermined flow resistance ratio. The first pressure reducing means divided into upper and lower parts to sequentially depressurize the liquid refrigerant at low temperature and low pressure, and an evaporator for heat-exchanging the liquid refrigerant passing through the first pressure reducing means with indoor air to evaporate the gas refrigerant at low temperature and low pressure. A second pressure reducing means for connecting an outlet side of the compressor and an inlet side of the lower portion of the first pressure reducing means, a valve installed in the second pressure reducing means to open and close the second pressure reducing means to flow the refrigerant on the high pressure side to the low pressure side; A pressure switch installed at the compressor outlet and configured to open and close the valve according to the pressure sensed at the outlet refrigerant pipe of the compressor. Refrigeration cycle characterized by. A compressor for compressing the refrigerant into a gas refrigerant of high temperature and high pressure, a condenser for condensing the gas refrigerant discharged from the compressor with outdoor air to condense it into a medium temperature high pressure liquid refrigerant, and a liquid refrigerant having passed through the condenser at low temperature and low pressure liquid refrigerant. A first decompression means for depressurizing the air, an evaporator for exchanging liquid refrigerant passing through the first decompression means with indoor air, and evaporating it into a low-temperature low-pressure gas refrigerant, and connecting an outlet side of the condenser and an inlet side of the compressor. A pressure reducing means, a valve installed at the second pressure reducing means to open and close the capillary tube so that the refrigerant on the high pressure side flows to the low pressure side, and installed at the compressor outlet side according to the pressure sensed at the outlet refrigerant pipe of the compressor. Refrigeration cycle comprising a pressure switch for opening and closing the valve. The method according to claim 1 or 3, The valve is a refrigeration cycle, characterized in that the solenoid valve for opening and closing the second pressure reducing means to adjust the flow rate of the refrigerant flowing through the capillary tube in accordance with the pressure signal of the pressure switch. A pressure sensing step of detecting a pressure of a refrigerant pipe at an outlet side of the compressor during operation of a refrigeration cycle; A signal generation step of generating a control signal according to the detected pressure when the pressure detected in the pressure detection step is equal to or greater than a set value; And a bypass step of opening a bypass path connecting the high pressure side and the low pressure side by the signal generated in the signal generating step. The method of claim 5, The control method of the refrigeration cycle further comprises a bypass blocking step of blocking the bypass path when the pressure detected in the pressure sensing step is less than the set value.