JP6597955B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner.

  DESCRIPTION OF RELATED ART Conventionally, the air conditioning apparatus provided with the compressor and the motor operated valve provided in the bypass pipe which connects the discharge side and suction side of a compressor is known (for example, refer patent document 1). In patent document 1, it can suppress that the pressure on the discharge side of a compressor becomes high too much by letting the refrigerant | coolant on the discharge side of a compressor flow to a suction side through a bypass pipe.

JP 2011-47344 A

However, in the conventional air conditioner described above, when the indoor air conditioning load suddenly decreases due to a decrease in the number of indoor units operated, the refrigerant pressure suddenly exceeds the capacity of the motor-operated valve. There is a problem that the refrigerant pressure may rise and the refrigerant pressure may become too high.
The present invention has been made in view of the above-described circumstances, and in an air conditioner, even when the indoor air conditioning load suddenly decreases, the refrigerant pressure can be prevented from becoming too high. The purpose is to.

In order to achieve the above object, the present invention provides an air conditioner including a compressor and a motor-operated valve provided in a bypass pipe that connects a discharge side and a suction side of the compressor. A pressure sensor for detecting the pressure of the refrigerant discharged from the compressor, and a detection value of the pressure sensor; and an open / close valve connected to the bypass pipe in parallel with the electric valve. A control unit that controls the motor-operated valve and the on-off valve based on the control unit, and the control unit, when the increase rate of the refrigerant pressure is equal to or higher than a predetermined value and the refrigerant pressure is equal to or higher than a high-pressure side threshold, The on-off valve is opened .
The present invention further includes a pressure sensor that detects a pressure of the refrigerant discharged from the compressor, and a control unit that controls the electric valve and the on-off valve based on a detection value of the pressure sensor. The part is characterized in that the opening / closing valve is opened when the rising speed of the refrigerant pressure is equal to or higher than a predetermined value and the refrigerant pressure is equal to or higher than a high-pressure side threshold value.

In the present invention, the control unit determines whether or not the pressure of the refrigerant is equal to or higher than an intermediate threshold value smaller than the high-pressure side threshold after the opening / closing valve is opened, and the refrigerant pressure is equal to or higher than the intermediate threshold value. In this case, the opening degree of the motor-operated valve is increased.
Further, the control unit determines that the refrigerant pressure is smaller than the intermediate threshold value, and closes the on-off valve when the refrigerant pressure is equal to or less than an allowable threshold value smaller than the intermediate threshold value.
Further, the control unit closes the on-off valve when the refrigerant pressure becomes smaller than the intermediate threshold value after increasing the opening degree of the electric valve.

  According to the air conditioner of the present invention, according to the present invention, the air conditioner includes a compressor, and a motor-operated valve provided in a bypass pipe that connects a discharge side and a suction side of the compressor. It is a valve whose opening degree is adjustable, and includes an on-off valve connected to the bypass pipe in parallel with the electric valve. Thereby, by opening the on-off valve connected to the bypass pipe in parallel with the electric valve, the refrigerant on the discharge side can be effectively flowed to the suction side, and the pressure of the refrigerant can be quickly reduced. For this reason, even when the air conditioning load on the indoor side suddenly decreases, it is possible to prevent the refrigerant pressure from becoming too high.

It is a lineblock diagram of the air harmony device concerning an embodiment of the invention. It is a block diagram which shows the functional structure of an air conditioning apparatus. It is a flowchart of refrigerant pressure control.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an air-conditioning apparatus according to an embodiment of the present invention.
The air conditioner 10 includes an outdoor unit 11 and a plurality of indoor units 12 (... indicates a plurality. The same applies hereinafter). The outdoor unit 11 and the indoor units 12... Are connected by an inter-unit pipe 13 including a liquid pipe 13a and a gas pipe 13b, thereby constituting a refrigeration cycle circuit for performing an air conditioning operation. The outdoor unit 11 houses a gas engine 15 (engine) and a compressor 16 that compresses the refrigerant by the driving force of the gas engine 15. The gas engine 15 generates a driving force by burning an air-fuel mixture of a fuel such as a gas supplied via a fuel adjustment valve (not shown) and air supplied via a throttle valve (not shown).

The compressor 16 is driven by the gas engine 15 via a drive belt 17 that is stretched between the driven shaft of the compressor 16 and the output shaft of the gas engine 15.
An oil separator 18, a four-way valve 19, and outdoor heat exchangers 20, 20 are connected in order to the discharge pipe 16 a of the compressor 16, and the outdoor heat exchangers 20, 20 are connected to each indoor via the liquid pipe 13 a. It is connected to one end of the indoor heat exchangers 21 of the units 12. An expansion valve 22... Is provided on one end side of each indoor heat exchanger 21. The heat exchange between the outdoor heat exchangers 20 and 20 is promoted by the ventilation of the blower 20a.
A four-way valve 19 is connected to the other end of each indoor heat exchanger 21... Via a gas pipe 13 b, and a suction pipe 16 b of the compressor 16 is connected to the four-way valve 19. An accumulator 23 is provided in the vicinity of the compressor 16 in the suction pipe 16b. Each indoor heat exchanger 21... Has a blower (not shown).

The liquid pipe 13 a is provided with a motor-operated valve 24, a check valve 25, and a liquid pipe 81 connected to the inflow side of the accumulator 23.
In the discharge pipe 16a, a pressure switch 28 and a high-pressure side pressure sensor 29 (pressure sensor) for detecting the pressure of the refrigerant in the discharge pipe 16a are provided between the compressor 16 and the oil separator 18. The pressure switch 28 has a function of detecting the high pressure abnormality of the refrigerant and stopping the compressor 16.
In the suction pipe 16b, a low-pressure sensor 30 that detects the pressure of the refrigerant in the suction pipe 16b is provided between the compressor 16 and the accumulator 23. In addition, a refrigerant pipe 82 that connects the suction pipe 16b to the liquid pipe 13a side is connected to the suction pipe 16b, and an electric valve 80 is provided in the refrigerant pipe 82. The refrigerant pipe 82 includes the plate heat exchanger 31 at a portion between the motor operated valve 80 and the suction pipe 16b.

The outdoor unit 11 includes a bypass pipe 35 that connects the discharge pipe 16a and the suction pipe 16b. Specifically, one end of the bypass pipe 35 is connected to a portion of the discharge pipe 16a between the oil separator 18 and the four-way valve 19, and the other end of the bypass pipe 35 is connected to the accumulator 23 and the four-way valve 19 in the suction pipe 16b. Connected to the part between. A part of the refrigerant in the discharge pipe 16a flows through the bypass pipe 35 to the suction pipe 16b due to a pressure difference.
The bypass pipe 35 is provided with a bypass valve 36 (electric valve) that changes the area of the flow path of the bypass pipe 35. The bypass valve 36 is an electric valve controlled by the control unit 37 (outdoor control unit) of the outdoor unit 11, and the area of the flow path is arbitrarily set stepwise or steplessly between the open state and the closed state. Can be adjusted.

A sub-bypass pipe 38 is connected to the bypass pipe 35 so as to bypass the bypass valve 36. One end of the sub bypass pipe 38 is connected to the upstream portion of the bypass valve 36 on the bypass pipe 35, and the other end of the sub bypass pipe 38 is connected to the downstream portion of the bypass valve 36 on the bypass pipe 35.
The sub bypass pipe 38 is provided with an unloader valve 39 (electromagnetic valve) that opens and closes the flow path of the sub bypass pipe 38. The unloader valve 39 is an electromagnetic valve that takes either an open state or a closed state, and its opening and closing is controlled by the control unit 37. The unloader valve 39 is closed when the pressure state of the refrigerant is normal.

When the four-way valve 19 is switched to the heating operation, the refrigerant discharged from the compressor 16 to the discharge pipe 16a is transferred to the oil separator 18, the four-way valve 19, and the gas pipe 13b as shown by broken arrows in FIG. , The indoor heat exchanger 21..., The liquid pipe 13a, the outdoor heat exchangers 20 and 20, the four-way valve 19, the plate heat exchanger 31, the accumulator 23, and the compressor 16 circulate in this order, The room is heated by the heat of condensation of the refrigerant in the exchangers 21.
When the four-way valve 19 is switched to the cooling operation, the refrigerant discharged from the compressor 16 to the discharge pipe 16a is transferred to the oil separator 18, the four-way valve 19, and the outdoor heat exchange as shown by solid line arrows in FIG. The refrigerant circulates in the order of the chambers 20 and 20, the liquid pipe 13 a, the indoor heat exchanger 21..., The gas pipe 13 b, the four-way valve 19, the plate heat exchanger 31, the accumulator 23, and the compressor 16. The room is cooled by the heat of evaporation of the refrigerant in the exchangers 21.
Since the indoor heat exchangers 21 are connected in parallel, the refrigerant can be individually supplied to the indoor heat exchangers 21 and the indoor heat exchangers 21 are operated independently. It is possible.

The gas engine 15 includes a cooling water circuit 40.
The cooling water circuit 40 includes a hot water three-way valve 41, a radiator 43, a cooling water pump 44, and an exhaust gas heat exchanger 45 of the gas engine 15 that are sequentially connected from the gas engine 15 via a cooling water pipe. The cooling water pump 44 circulates cooling water in this circuit. The piping of the cooling water circuit is indicated by a thick line in FIG. 1, and the flow of the cooling water is indicated by a solid arrow.
The radiator 43 is arranged in parallel inside the outdoor heat exchanger 20. In the radiator 43, heat exchange between the outside air and the cooling water is performed.
In the plate heat exchanger 31, the refrigerant returning to the compressor 16 is heated by the cooling water flowing in the cooling water circuit 40 by the operation of the motor operated valve 80. Thereby, the low-pressure pressure of the refrigerant increases, and the heating efficiency is improved.
An exhaust muffler 46 and an exhaust top 47 for exhausting the exhaust gas are sequentially connected to the exhaust gas heat exchanger 45.

The cooling water circuit 40 can form a first path through which cooling water flows in the order of the gas engine 15, the hot water three-way valve 41, the radiator 43, the cooling water pump 44, the exhaust gas heat exchanger 45, and the gas engine 15.
The cooling water circuit 40 cools cooling water in the order of the gas engine 15, the hot water three-way valve 41, the plate heat exchanger 31, the cooling water pump 44, the exhaust gas heat exchanger 45, and the gas engine 15. A second path through which water flows can be formed.
Further, a reservoir tank 82 for replenishing cooling water is connected to the cooling water circuit 40.

FIG. 2 is a block diagram showing a functional configuration of the air conditioning apparatus 10.
The control unit 37 of the outdoor unit 11 is connected to the gas engine 15, the compressor 16, the four-way valve 19, the bypass valve 36, and the unloader valve 39 including each part of the cooling water circuit 40. Further, the high pressure side pressure sensor 29, the low pressure side pressure sensor 30, the pressure switch 28, an outside air temperature sensor 48 that detects the temperature of the outside air, an operation instruction to the outdoor unit 11, and the like are input to the control unit 37. A control panel 49 and the like are connected.
The indoor side control part 50 which controls the indoor units 12 ... is connected to the control part 37, and the control part 37 and the indoor side control part 50 communicate with each other. The indoor control unit 50 is connected to the expansion valves 22..., A room temperature sensor 51 that detects the room temperature, and a remote controller 52 to which an operation instruction to the indoor units 12.
The control unit 37 and the indoor side control unit 50 include a CPU, ROM as a storage unit, RAM, EEPROM, and the like.

The control unit 37 controls the bypass valve 36 and the unloader valve 39 on the basis of the detection value of the high pressure side pressure sensor 29, and performs refrigerant pressure control.
FIG. 3 is a flowchart of refrigerant pressure control. The process of FIG. 3 is repeatedly executed at predetermined time intervals.
First, during the operation of the air conditioner 10, the control unit 37 determines whether or not the rising speed of the refrigerant pressure in the discharge pipe 16a is equal to or higher than a predetermined speed S (predetermined value) based on the detection value of the high-pressure side pressure sensor 29. Is determined (step S1). Here, the predetermined speed S is a speed at which the pressure of the refrigerant is considered to be abruptly higher than usual, and is a speed at which the increase in pressure per second becomes 0.1 MPa, for example.
Such a sudden increase in the refrigerant pressure occurs when the air conditioning load of the indoor units 12... Suddenly decreases (decreases). For example, all the indoor units 12. A sudden increase in pressure may occur when the other indoor units 12 are stopped while leaving one indoor unit 12 inside. In this case, the number of indoor heat exchangers 21... Is reduced with respect to the output of the compressor 16, the refrigerant has nowhere to go, and the pressure of the gas refrigerant in the discharge pipe 16a increases rapidly. In particular, in the present embodiment, the air conditioner 10 is a gas heat pump type, the compressor 16 is driven by the gas engine 15 having a large output, and the output width of the compressor 16 is large. When the air conditioning load suddenly decreases (decreases), a sudden increase in the refrigerant pressure is likely to occur.

When the rising speed of the refrigerant pressure is equal to or higher than the predetermined speed S (step S1: Yes), the control unit 37 determines whether or not the detection value of the high pressure side pressure sensor 29 is equal to or higher than the high pressure side threshold value P1 ( Step S2). The high-pressure side threshold value P1 is set to a value smaller than the limit value in consideration of the pressure resistance of the air conditioner 10 and the like. When the pressure is not equal to or higher than the high-pressure side threshold value P1 (step S2: No), the control unit 37 returns to the process of step 1.
When the pressure is equal to or higher than the high-pressure side threshold value P1 (step S2: Yes), the control unit 37 opens the unloader valve 39 (step S3). Thereby, a part of the refrigerant flowing from the discharge pipe 16a to the bypass pipe 35 flows through the sub bypass pipe 38 and the unloader valve 39 to the suction pipe 16b. The unloader valve 39 is an open / close valve that is configured by an electromagnetic valve and is opened / closed at once. The unloader valve 39 has a higher opening / closing speed than the bypass valve 36. For this reason, the refrigerant | coolant of the discharge pipe 16a can be rapidly flowed into the suction pipe 16b, and the pressure of the refrigerant | coolant of the discharge pipe 16a can be rapidly reduced. In step S3, the control unit 37 may open the unloader valve 39 and control the output of the gas engine 15 to be reduced so as to reduce the output of the compressor 16.

Next, the control unit 37 determines, based on the high pressure side pressure sensor 29, whether or not the pressure of the refrigerant after opening the unloader valve 39 is equal to or higher than the intermediate threshold value P2 (step S4). Here, the intermediate threshold value P2 is a pressure smaller than the high-pressure side threshold value P1.
When the pressure is not equal to or higher than the intermediate threshold value P2 (step S4: No), the control unit 37 determines whether or not the refrigerant pressure is equal to or lower than the allowable threshold value P3 that is smaller than the intermediate threshold value P2, based on the high pressure side pressure sensor 29. If it is not less than the allowable threshold value P3 (step S5: NO), the process returns to step S3, and the unloader valve 39 is kept open. Here, the allowable threshold value P3 is a pressure at which the pressure of the refrigerant can be regarded as a pressure during normal operation.

When the refrigerant pressure is equal to or lower than the allowable threshold value P3 (step S5: Yes), the control unit 37 closes the unloader valve 39 (step S6). Thus, the refrigerant in the discharge pipe 16a does not pass through the sub bypass pipe 38.
Next, the control unit 37 determines whether or not the opening degree of the bypass valve 36 is being controlled (step S7). If the opening degree of the bypass valve 36 is not being controlled (step S7: Nо), the refrigerant The pressure control process is terminated. Here, the opening degree of the bypass valve 36 is controlled by the control unit 37 so that the pressure becomes equal to or less than the allowable threshold value P <b> 3 based on the pressure increase and decrease speeds obtained from the high pressure side pressure sensor 29.
When the opening degree of the bypass valve 36 is being controlled (step S7: Yes), the control unit 37 determines whether or not the refrigerant pressure is equal to or lower than the allowable threshold value P3 (step S8), and the pressure is equal to the allowable threshold value P3. When it is below (step S8: Yes), the control of the opening degree of the bypass valve 36 is turned off (step S9), and the process is terminated.

When the pressure is equal to or higher than the intermediate threshold P2 after the unloader valve 39 is opened (step S4: Yes), the control unit 37 increases the opening degree of the bypass valve 36 (step S10). That is, when the pressure does not sufficiently decrease even when the unloader valve 39 is opened, the controller 37 further increases the opening of the bypass valve 36 and increases the amount of refrigerant flowing from the bypass pipe 35 to the suction pipe 16b. For this reason, the pressure of the refrigerant in the discharge pipe 16a can be quickly reduced.
After increasing the opening degree of the bypass valve 36, the control unit 37 determines whether or not the pressure is smaller than the intermediate threshold value P2 based on the high pressure side pressure sensor 29 (step S11), and the pressure is determined to be the intermediate threshold value P2. If not smaller (step S11: NO), the process returns to step S10, and the control to increase the opening degree of the bypass valve 36 is continued. Here, in step S11, instead of the intermediate threshold value P2, an intermediate threshold value P2a (not shown) smaller than the intermediate threshold value P2 and larger than the allowable threshold value P3 may be used.

When the pressure is smaller than the intermediate threshold value P2 (step S11: Yes), the control unit 37 determines whether or not the unloader valve 39 is opened (step S12).
When the unloader valve 39 is opened (step S12: Yes), the control unit 37 proceeds to step 6, closes the unloader valve 39, and proceeds to step S7. If the opening degree of the bypass valve 36 is being controlled in step S7 (step S7: NO), the process proceeds to step S8. When the pressure is not less than or equal to the allowable threshold value P3 (step S8: No), the control unit 37 returns to step S10 and continues the control to increase the opening degree of the bypass valve 36. When the pressure is equal to or less than the allowable threshold P3 (step S8: Yes), the control of the opening degree of the bypass valve 36 is turned off (step S9), and the process is terminated.

If the unloader valve 39 is closed (step S12: NO), the control unit 37 proceeds to step S8. In this case, the processing after step S8 is the same as that described above.
When the rising speed of the refrigerant pressure is not equal to or higher than the predetermined speed S (step S1: No), the control unit 37 determines whether or not the refrigerant pressure is equal to or higher than the intermediate threshold value P2 (step S13). When the refrigerant pressure is not equal to or higher than the intermediate threshold value P2 (step S13: No), the control unit 37 returns to the process of step S1.
When the refrigerant pressure is equal to or higher than the intermediate threshold value P2 (step S13: Yes), the control unit 37 proceeds to the process of step S10. The processing after step S10 is the same as that described above. That is, when the rising speed of the refrigerant pressure is smaller than the predetermined speed S in step S1 and the refrigerant pressure is equal to or higher than the intermediate threshold P2, the unloader valve 39 remains closed in the subsequent processing, and the refrigerant pressure Is controlled to be equal to or less than the allowable threshold value P3 by controlling the opening degree of the bypass valve 36.

  As described above, according to the embodiment to which the present invention is applied, the air conditioner 10 includes the compressor 16 and the bypass valve 36 provided in the bypass pipe 35 that connects the discharge side and the suction side of the compressor 16. The bypass valve 36 is a valve whose opening degree is adjustable, and includes an unloader valve 39 connected to the bypass pipe 35 in parallel with the bypass valve 36. Thereby, by opening the unloader valve 39 connected to the bypass pipe 35 in parallel with the bypass valve 36, the refrigerant on the discharge side can be effectively flowed to the suction side, and the pressure of the refrigerant can be quickly reduced. Can do. For this reason, even if it is a case where the air-conditioning load of indoor unit 12 ... falls rapidly (it becomes small), it can prevent that the pressure of a refrigerant | coolant becomes too high. Further, for example, when a mechanism having the function of the unloader valve 39 is provided integrally with the compressor 16, it takes time for maintenance and replacement of the mechanism, but the unloader valve 39 is connected to the bypass pipe 35. Since the bypass pipe 38 is provided, maintenance and replacement of the unloader valve 39 are easy.

The high pressure side pressure sensor 29 that detects the pressure of the refrigerant discharged from the compressor 16, and the control unit 37 that controls the bypass valve 36 and the unloader valve 39 based on the detection value of the high pressure side pressure sensor 29, The control unit 37 opens the unloader valve 39 when the rising speed of the refrigerant pressure is equal to or higher than the predetermined speed S and the refrigerant pressure is equal to or higher than the high-pressure side threshold value P1. Thereby, the unloader valve 39 is opened when the rising speed of the refrigerant pressure is equal to or higher than the predetermined speed S and the refrigerant pressure is equal to or higher than the high pressure side threshold value P1, so that it is effective that the refrigerant pressure becomes too high. Can be prevented. In addition, since the unloader valve 39 is not opened when the rising speed of the refrigerant pressure is slow, it is possible to prevent the unloader valve 39 from being opened frequently and to stabilize the refrigerant pressure.
Further, after the unloader valve 39 is opened, the control unit 37 determines whether or not the refrigerant pressure is equal to or higher than the intermediate threshold value P2 that is smaller than the high-pressure side threshold value P1, and when the refrigerant pressure is equal to or higher than the intermediate threshold value P2. The opening degree of the bypass valve 36 is increased. Thereby, even when the unloader valve 39 is opened, when the refrigerant pressure is equal to or higher than the intermediate threshold value P2, the opening degree of the bypass valve 36 is increased, so that the refrigerant on the discharge side is effectively flowed to the suction side. And the pressure of the refrigerant can be quickly reduced.

Further, the control unit 37 determines that the refrigerant pressure is smaller than the intermediate threshold value P2, and closes the unloader valve 39 when the refrigerant pressure is equal to or smaller than the allowable threshold value P3 smaller than the intermediate threshold value P2. As a result, when the refrigerant pressure becomes equal to or less than the allowable threshold value P3, the unloader valve 39 is closed, so that the refrigerant pressure can be prevented from becoming too high and the refrigerant pressure can be stabilized at an early stage.
Further, after increasing the opening degree of the bypass valve 36, the control unit 37 closes the unloader valve 39 when the refrigerant pressure becomes smaller than the intermediate threshold value P2. For this reason, it can prevent that the pressure of a refrigerant | coolant becomes high too much, and can stabilize the pressure of a refrigerant | coolant at an early stage.

DESCRIPTION OF SYMBOLS 10 Air conditioning apparatus 16 Compressor 29 High pressure side pressure sensor (pressure sensor)
35 Bypass pipe 36 Bypass valve (motorized valve)
37 Control unit 39 Unloader valve (open / close valve)
P1 High pressure side threshold P2 Intermediate threshold P3 Allowable threshold S Predetermined speed (predetermined value)

Claims (4)

In an air conditioner comprising a compressor and an electric valve provided in a bypass pipe connecting a discharge side and a suction side of the compressor,
The motor-operated valve is a valve whose opening degree is adjustable,
An open / close valve connected to the bypass pipe in parallel with the motor-operated valve ;
A pressure sensor for detecting the pressure of the refrigerant discharged from the compressor, and a control unit for controlling the electric valve and the on-off valve based on a detection value of the pressure sensor;
The air conditioner characterized in that the control unit opens the on-off valve when the rising speed of the refrigerant pressure is equal to or higher than a predetermined value and the refrigerant pressure is equal to or higher than a high-pressure side threshold value . The control unit determines whether or not the pressure of the refrigerant is equal to or higher than an intermediate threshold value smaller than the high-pressure side threshold after the opening / closing valve is opened, and when the pressure of the refrigerant is equal to or higher than the intermediate threshold value, air conditioner according to claim 1, characterized in that to increase the opening degree of the valve. Wherein the control unit determines that the pressure of the refrigerant is smaller than the intermediate threshold value, if the pressure of the refrigerant is smaller allowable threshold value or less than the intermediate threshold value, according to claim 2, wherein the closing the on-off valve Air conditioner. 3. The air conditioner according to claim 2 , wherein the control unit closes the on-off valve when the refrigerant pressure becomes smaller than the intermediate threshold after increasing the opening of the electric valve.

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