JP2007127327A - High pressure rise preventing means of engine drive type heat pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve reliability of a high pressure rise preventing means of an existing connecting piping and to improve versatility to enable use in both cooling operation and heating operation, in regard to an engine drive type heat pump in transferring to HFC refrigerant. <P>SOLUTION: This engine drive type heat pump 1 having a compressor 10 by driving of an engine, a receiver 14 for storing a liquid refrigerant, and a four-way valve 20 capable of connecting a discharge path with an outdoor heat exchanger or an indoor heat exchanger, further comprises a bypass path 66 provided with a bypass solenoid valve 32 on the way, connected with the discharge path 60 at its one end, and connected with a suction path 61 at the other end, a first pressure switch 97 disposed on a path connecting the four-way valve 20 and the indoor heat exchanger 13, a second pressure switch 96 disposed on a path connecting the receiver and the indoor heat exchanger, and a high pressure rise preventing means opening the bypass solenoid valve 32 when the first pressure switch 97 or the second pressure switch 96 becomes more than a prescribed value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for avoiding a high-pressure rise in an engine-driven heat pump.

Conventionally, for the purpose of protecting the global environment, the refrigerant used in the refrigeration apparatus and the air conditioner has been transferred from the HCFC refrigerant to the HFC refrigerant. This is because an HFC refrigerant that does not contain chlorine at all with respect to an HCFC refrigerant containing chlorine does not destroy the ozone layer and has an ozone depletion potential of zero.
The problem of this HFC refrigerant transfer is the difference in the respective refrigerant saturation pressures. In general, the saturation pressure of HFC refrigerant is higher than that of HCFC refrigerant. For example, when the saturation temperature exceeds 50 ° C., the saturation pressure of HFC-R410A refrigerant is about 1.4 times higher than the saturation pressure of HCFC-R22 refrigerant.

Recently, in buildings or condominiums, communication pipes that connect outdoor units and indoor units of air-conditioning apparatuses are often embedded in wall surfaces. Here, when the existing air conditioner is removed and a new air conditioner is installed, the existing connection pipe is usually used as it is.
Therefore, when replacing the HCFC refrigerant air conditioner with the HFC refrigerant air conditioner, the pipe endurance pressure of the existing communication pipe becomes a problem. For example, the piping design pressure of the air conditioner using the HCFC-R22 refrigerant is 2.75 MPa, but is significantly higher when using the HFC-R410A refrigerant.

In response to such a problem of HFC refrigerant transfer, Patent Document 1 discloses a refrigeration apparatus that reduces the pressure in the communication pipe to a predetermined value or less. During the cooling operation, the refrigeration apparatus increases the opening degree of the expansion valve, increases the amount of refrigerant circulation, and reduces the high pressure of the communication pipe. On the other hand, during the heating operation, the operating frequency of the compressor is reduced to avoid an increase in the high pressure of the connecting pipe.
JP-A-2005-49057

However, the high pressure rise avoidance means disclosed in Patent Document 1 cannot avoid high pressure rise during heating unless the compressor is capable of capacity control. In addition, the piping of a refrigeration unit usually does not rupture if the design pressure is exceeded even a little, but considering fatigue, aging deterioration, or strength variation of the brazed part, the time for exceeding the design pressure in long-term use Accumulated and may cause pipe rupture / damage. Here, in the expansion valve control, the opening degree is controlled with fine pulses, and the followability to the refrigerant behavior is slow, so there may be a timing when the design pressure is exceeded. Thus, the high pressure increase avoidance means based only on the expansion valve control has low reliability with respect to the design pressure of the communication pipe.
Therefore, the problem to be solved is to improve the reliability of the high pressure rise avoidance means of the existing communication pipe in the engine-driven heat pump when the HFC refrigerant is transferred, and to improve the versatility so that it can be used in the cooling operation and the heating operation. That is.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, the compressor driven by the engine, the discharge path connected to the discharge side of the compressor, the suction path connected to the suction side of the compressor, and the high-pressure liquid refrigerant are stored. In an engine-driven heat pump having a receiver and a four-way valve capable of communicating the discharge path with an outdoor heat exchanger or an indoor heat exchanger, an open / close valve is provided in the middle thereof, one end is connected to the discharge path, and the other end is connected A bypass path connected to the suction path, a first pressure switch provided on a path connecting the four-way valve and the indoor heat exchanger, and a first pressure switch provided on a path connecting the receiver and the indoor heat exchanger. A two-pressure switch and high-pressure rise avoiding means for opening the on-off valve by the first pressure switch or the second pressure switch are provided.

  As effects of the present invention, the following effects can be obtained.

  In claim 1, versatility is improved so that high pressure rise avoidance for the existing communication pipe at the time of transition to the HFC refrigerant can be used even during cooling operation or heating operation. Furthermore, since the predetermined refrigerant amount is immediately bypassed by the opening / closing means, the reliability with respect to the existing communication pipe design pressure can be improved.

Next, embodiments of the invention will be described.
FIG. 1 is a refrigerant circuit diagram showing an overall configuration of an engine-driven heat pump according to an embodiment of the present invention. FIG. 2 is a diagram showing refrigerant behavior of high-pressure rise mitigation control and high-pressure rise avoidance control in the same cooling operation. 3 is a diagram showing refrigerant behavior of high pressure increase mitigation control and high pressure increase avoidance control in the heating operation.

  As shown in FIG. 1, an engine-driven heat pump 1 includes a compressor 10 that obtains power from an engine (not shown) as a drive source and compresses refrigerant, and is connected to the discharge side of the compressor 10 during cooling. A four-way valve 20 that switches the flow of refrigerant during heating, an outdoor heat exchanger 12 that is supplied with refrigerant discharged from the compressor 10 via the four-way valve 20 during cooling, and heat exchange between the outdoor heat exchanger 12 and outdoor air An outdoor fan 5 that is heated, an indoor heat exchanger 13 that is supplied with refrigerant discharged from the compressor 10 through a four-way valve 20 during heating, an indoor fan 6 that exchanges heat between the indoor heat exchanger 13 and indoor air, It has the outdoor heat exchanger expansion valve 21 arrange | positioned between the heat exchanger 12 and the indoor heat exchanger 13, and uses the refrigerant cycle comprised by these.

  The compressor 10 sucks and compresses the gas refrigerant from the suction side and discharges the high-temperature and high-pressure gas refrigerant. The four-way valve 20 is connected to the discharge side of the compressor 10 through a discharge path 60, and the refrigerating machine oil contained in the gas refrigerant is separated into the discharge path 60 to the suction side of the compressor 10. An oil separator 11 for returning is provided. That is, the gas refrigerant discharged from the compressor 10 flows into the four-way valve 20 through the oil separator 11 and is guided in a predetermined direction by the four-way valve 20. Further, since the gas refrigerant sucked into the compressor 10 is also guided by the four-way valve 20, the refrigerant suction side of the compressor 10 and the four-way valve 20 are connected by a suction path 61. The second pressure sensor 90 and the high-pressure cutoff switch (HPS) 95 are provided on the compressor 10 side of the discharge path 60 in order to detect the high-pressure gas refrigerant pressure discharged by the compressor 10.

  The four-way valve 20 is connected to one end side of the outdoor heat exchanger 12, and a receiver 14 is connected to the other end side of the outdoor heat exchanger 12. On the other hand, one end of the indoor heat exchanger 13 is connected to the receiver 14 via a liquid side communication pipe 50, and the other end is connected to the four-way valve 20 via a gas side communication pipe 51. Yes. The liquid side communication pipe 50 and the gas side communication pipe 5 are often installed inside the building, and recently, they may be used as they are when the air conditioner is updated. Further, a liquid closing valve 40 and a gas closing valve 41 are provided on the side of the outdoor unit 2 of these communication pipes 50 and 51, respectively. Furthermore, a first pressure sensor 91 and a first pressure switch 96 are provided on the outdoor unit 2 side of the liquid side communication pipe 50. On the other hand, a second pressure switch 97 is provided on the gas communication pipe 51 on the outdoor unit 2 side.

  The waste heat recovery unit 15 is provided in a path 63 that branches from between the outdoor heat exchanger expansion valve 21 and the receiver 14 and is connected to the suction path 61. The waste heat recovery device expansion valve 22, the supercooling heat exchanger 17, and the waste heat recovery device 15 are connected in series to the passage 63 toward the suction passage 61. The refrigerant passing through the path 63 subcools the liquid refrigerant in the receiver 14 by latent heat of vaporization in the supercooling heat exchanger 17 and recovers engine waste heat from the engine cooling water in the waste heat recovery unit 15. Evaporate.

  The first bypass path 65 and the second bypass path 66 are bypass paths that short-circuit the discharge path 60 and the suction path 61. The first bypass path 65 is provided with a bypass expansion valve 24 as a pressure reducing mechanism, and the second bypass path 66 is provided with a bypass electromagnetic valve 32 and a capillary 25 as a pressure reducing mechanism. These bypass paths 65 and 66 prevent an abnormal pressure increase on the high-pressure side of the engine-driven heat pump 1 by short-circuiting the discharge gas of the compressor 10 and returning it to the suction path.

  A path 67 is a path from the upper surface of the receiver 14 toward the discharge path 60. The path 67 can release the gas refrigerant to the discharge path when the high pressure of the receiver 14 rises abnormally. Further, the path 67 prevents the high-temperature and high-pressure discharged gas refrigerant from flowing back to the receiver 14 via the check valves 75 and 76.

The pressure switches 95, 96, and 97 described above detect pressure changes and open and close the contacts of the electric circuit, and are devices that open and close the electric circuit such as the compressor 10 and the electromagnetic valve for protection and security. For example, the high-pressure shut-off switch (HPS) 95 immediately shuts down the compressor 10 electrically when the discharge pressure of the compressor 10 exceeds a predetermined value, and stops the piping or equipment due to abnormally high pressure. It is a safety device to prevent. On the other hand, the pressure sensors 90 and 91 are devices that convert a pressure change into an electrical signal using a diaphragm, and many of them are devices for controlling the refrigerant in normal operation.
The controller 100 detects the refrigerant state by the temperature sensor and the pressure sensor, and opens / closes or controls the opening / closing of the electromagnetic valve, the electronic expansion valve, and the four-way valve. On the other hand, the closing valve is normally opened and closed by an operator's hand.

Recently, in buildings or condominiums, connecting pipes 50 and 51 that connect the outdoor unit 2 and the indoor unit 3 of the air conditioner such as the engine-driven heat pump 1 are often embedded in the wall surface. Here, when the existing air conditioner is removed and a new engine-driven heat pump 1 is installed, the existing communication pipes 50 and 51 are usually used as they are.
Therefore, when updating from an air conditioner using HCFC refrigerant to an engine-driven heat pump 1 using HFC refrigerant, the piping design pressure of the existing communication pipes 50 and 51 becomes a problem. For example, when the HFC-R410A refrigerant is used, the pipe design pressure is larger than the pipe design pressure of the air conditioner using the HCFC-R22 refrigerant. Therefore, the design of the existing connection pipes 50 and 51 when using the HCFC-R22 refrigerant is used. Do not exceed pressure.
In the present embodiment, in the engine-driven heat pump 1 using HFC refrigerant, the high-pressure control means and high-pressure avoidance means of the communication pipes 50 and 51 will be described on the assumption that the existing communication pipes 50 and 51 are HCFC refrigerant use. To do.

As shown by the thick line in FIG. 2, the refrigerant behavior during the cooling operation of the engine-driven heat pump 1 will be described here.
During the cooling operation, the high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 10 is sent to the outdoor heat exchanger 12 via the discharge path 60 and the four-way valve 20, and this outdoor heat exchanger. 12 is condensed by dissipating heat to the outside air blown by the outdoor fan 5, and this condensed heat is dissipated into the outdoor air. Here, the gas refrigerant changes from gas to liquid. The liquefied refrigerant flows into the receiver 14, and further reaches the indoor heat exchanger expansion valve 23 from the receiver 14 via the liquid side connection pipe 50, and suddenly reaches the indoor heat exchanger expansion valve 23. Then, the pressure is reduced and the gas is easily evaporated and is led to the indoor heat exchanger 13. This indoor heat exchanger 13 becomes an evaporator, and the refrigerant takes evaporation heat from the indoor air and changes from liquid to gas, and cools the indoor air. The vaporized refrigerant passes through the gas side connecting pipe 51, passes through the suction path 61 through the four-way valve 20, is sucked and compressed by the compressor 10, and then discharged again.

As shown by the broken line in FIG. 2, the refrigerant behavior during the high-pressure rise mitigation control during the cooling operation of the engine-driven heat pump 1 will be described.
During normal cooling operation, the cause of the increase in high pressure includes an increase in outside air temperature and an increase in indoor cooling load.
In such a case, the amount of refrigerant passing through the first bypass path 65 is controlled so as not to exceed the design pressure of the liquid side communication pipe 50 that passes through the communication pipes 50 and 51 first. Specifically, when the pressure detected by the first pressure sensor 91 provided on the upstream side of the liquid side connecting pipe 50 exceeds a predetermined value, the controller 100 is provided in the middle of the first bypass path 65. By controlling the opening degree of the bypass expansion valve 24, the amount of refrigerant passing through is controlled and normal operation is continued. By preventing a part of the total circulating refrigerant amount of the engine-driven heat pump 1 from working as a bypass refrigerant amount (not flowing through the outdoor heat exchanger 12), the increase in high pressure is mitigated.

As shown by the alternate long and short dash line in FIG. 2, the refrigerant behavior during the high-pressure rise avoidance control during the cooling operation of the engine-driven heat pump 1 will be further described.
Even in the above-described high pressure rise mitigation control, as a cause when the high pressure is not sufficiently lowered, there is an obstacle in the ventilation path of the outdoor unit 2 (for example, a vinyl sheet or the like), the indoor heat exchanger expansion valve 23 is clogged, or A non-condensable gas may be mixed in the refrigerant circuit. Further, for example, in the case of an engine-driven heat pump in which a plurality of indoor units 3... 3 are connected, a large number of indoor units 3. In the situation where only the operation is performed, the refrigerant concentrates on one indoor unit 3 that is operated, and the high pressure may suddenly rise.
In such a case, the amount of bypass refrigerant is increased using the second bypass path 66 so as not to exceed the design pressure of the liquid side communication pipe 50. Specifically, when the pressure of the refrigerant passing through the liquid side connection pipe 50 exceeds a predetermined value preset in the first pressure switch 96, the controller 100 is in the middle of the second bypass path 66. The bypass solenoid valve 32 provided is opened, and the amount of refrigerant passes through the second bypass path 66. In other words, a high pressure rise is avoided by further increasing the amount of bypass passage refrigerant. Here, since the bypass solenoid valve 32 is controlled to be opened and closed by ON-OFF, when one end is turned ON, an increase in high pressure can be immediately avoided.

As shown by the thick line in FIG. 3, the refrigerant behavior during the heating operation of the engine-driven heat pump 1 will be further described.
During the heating operation, the high-temperature and high-pressure gas refrigerant compressed and discharged by the compressor 10 passes through the discharge path 60, passes through the four-way valve 20, passes through the gas communication pipe 51, and the indoor heat exchanger 13. In the indoor heat exchanger 13, heat is condensed to the indoor air blown by the indoor fan 6, and the condensed heat is dissipated in the indoor air to warm the indoor air. Here, the refrigerant changes from gas to liquid. The liquefied refrigerant flows into the receiver 14 via the liquid communication pipe 50, reaches the outdoor heat exchanger expansion valve 21 from the receiver 14, and is rapidly depressurized by the outdoor heat exchanger expansion valve 21. The state is easily evaporated and is led to the outdoor heat exchanger 12. This outdoor heat exchanger 4 becomes an evaporator, and the refrigerant takes heat of evaporation from the outdoor air, and a part of the refrigerant changes from liquid to gas. Then, the refrigerant evaporated through the outdoor heat exchanger 4 passes through the suction path 61 via the four-way valve 20, is sucked and compressed by the compressor 10, and is then discharged again.

In the case of heating operation, the means of the high pressure rise mitigating means and the high pressure rise avoiding means are the same as in the cooling operation. However, contrary to the case of the cooling operation, since the refrigerant passes through the gas side connection pipe 51 first of the connection pipes 50 and 51, the second pressure sensor 90 is connected to the compressor 10 side of the discharge path 60. The pressure switch 97 is provided on the upstream side of the gas side communication pipe 51 during the heating operation. The reason why the second pressure sensor 90 is not provided on the gas side connecting pipe 51 is that the pressure of the gas side connecting pipe 51 is higher than the discharge side of the compressor 10 in consideration of the pipe pressure loss of the outdoor heat exchanger 12. Because there is no.
On the other hand, the reason why only the second pressure switch 97 is provided for the gas side communication pipe 51 is that a high-pressure cutoff switch (HPS) 95 is provided on the discharge side of the compressor 10. When the high pressure cutoff switch (HPS) 95 is activated, the compressor 10 is stopped. Therefore, the set values of the first pressure switch 96 and the second pressure switch 97 are less than the set values of the high pressure cutoff switch (HPS) 95. Must-have.

In this embodiment, in addition to the high-pressure rise mitigating means for controlling the passage refrigerant amount by opening degree control of the bypass expansion valve 24, the high-pressure rise avoiding means for increasing the bypass refrigerant amount by the bypass solenoid valve 32 for opening / closing control by ON-OFF. Therefore, the reliability for the design pressure of the existing connecting pipe has been improved. Further, in this embodiment, it is possible to avoid a high pressure rise during cooling operation and heating operation, and the versatility is improved.
This embodiment not only avoids a high pressure increase with respect to the design pressure of the existing communication pipes 50 and 51 when the HFC refrigerant is transferred, but also in a refrigerant circuit including equipment whose operation is not guaranteed unless the pressure is lower than a predetermined pressure. Can be applied.

The refrigerant circuit figure which showed the whole structure of the engine drive type heat pump which concerns on the Example of this invention. The figure which similarly shows the refrigerant | coolant behavior of the high voltage | pressure rise mitigation control and high voltage | pressure rise avoidance control in a cooling operation. The figure which similarly shows the refrigerant | coolant behavior of the high voltage | pressure rise mitigation control and high voltage | pressure rise avoidance control in heating operation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine drive type heat pump 10 Compressor 13 Indoor heat exchanger 14 Receiver 20 Four-way valve 32 Bypass solenoid valve 60 Discharge path 61 Intake path 66 Bypass path 96 Second pressure switch 97 First pressure switch

Claims (1)

An engine driven compressor;
A discharge path connected to the discharge side of the compressor;
A suction path connected to the suction side of the compressor;
A receiver for storing high-pressure liquid refrigerant;
In an engine-driven heat pump having an outdoor heat exchanger or a four-way valve capable of communicating with the indoor heat exchanger, an opening / closing valve is provided in the middle of the discharge path, one end is connected to the discharge path, and the other end is the suction path A bypass path connected to
A first pressure switch provided on a path connecting the four-way valve and the indoor heat exchanger;
A second pressure switch provided on a path connecting the receiver and the indoor heat exchanger;
An engine-driven heat pump comprising a high-pressure rise avoiding means for opening the on-off valve by the first pressure switch or the second pressure switch.

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