JPH11159911A - Refrigerating cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve return of oil to a compressor at a transfer timing from cooling operation to heating operation, in a refrigerating cycle device independently provided with an evaporator for cooling serving as a heat-exchanger on the indoor side and a condenser for heating, and performing dehumidification and heating. SOLUTION: During the starting of a heating mode, an exhaust mode for flooded oil of a vaporizer is decided based on an outside air temperature at a step 104. When it is decided that this oil discharge mode is needed, an oil discharge mode is set at a step S105. At this mode, after a discharge gas refrigerant of a compressor is condensed by a condenser, the gas refrigerant is caused to pass through a pressure reducing means, an outdoor heat exchanger, and the vaporizer and is sucked in the compressor. This constitution discharges lubrication oil from the vaporizer for cooling.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle device constituting a heat pump system capable of dehumidifying and heating, and is suitable as an air conditioner for an electric vehicle.

[0002]

2. Description of the Related Art The present applicant has previously disclosed in Japanese Patent Application Laid-Open
JP-A-39550, JP-A-9-86149, and JP-A-9-66736 propose a heat pump system capable of dehumidifying and heating for use in an air conditioner for a vehicle such as an electric vehicle.

In these prior arts, two heat exchangers, a cooling evaporator and a heating condenser, are arranged as indoor heat exchangers, so that they are once cooled by the cooling evaporator. The function of dehumidifying heating is realized by reheating the air with a condenser for heating. In addition, as described above, by independently providing a cooling only evaporator and a heating only condenser, when switching from the cooling mode to the heating mode, it is possible to prevent fogging of the window glass due to rapid evaporation of condensed water. ing.

[0004]

By the way, in the above-mentioned prior art, in the middle season such as spring and autumn, since the cooling heat load is small, when the electric compressor is operated in the cooling mode, the cooling capacity of the electric compressor is suppressed. Driven at low rpm for.
As a result, a phenomenon occurs in which the liquid refrigerant containing the lubricating oil in the cycle falls into the evaporator.

[0005] In such a refrigerant stagnation state, when the mode shifts from the cooling mode to the heating mode, the cooling evaporator is disconnected from the refrigerant flow path, and the refrigerant does not flow through the cooling evaporator. When the operation is switched to the heating operation, the liquid refrigerant including the lubricating oil in the cooling evaporator is not discharged, and almost remains in the evaporator. As a result, the amount of oil recirculating in the compressor becomes insufficient, resulting in poor lubrication of the compressor and adversely affecting the durability of the compressor.

[0006] The present invention has been made in view of the above points,
In the refrigeration cycle device comprising a heat pump system capable of dehumidifying and heating, each independently including an evaporator for cooling and a condenser for heating as an indoor heat exchanger,
It is an object of the present invention to improve the return of oil to the compressor during the transition from the cooling operation to the heating operation. In addition, the present invention provides a mode for discharging the sleeping oil in the cooling evaporator,
It is another object of the present invention to be able to execute while suppressing deterioration of the heating feeling.

[0007]

In order to achieve the above object, according to the first to fifth aspects of the present invention, conditioned air is provided upstream of a conditioned air passage (2) through which conditioned air is passed indoors. An evaporator (11) for cooling the evaporator (11) is disposed, and a condenser (12) for heating the conditioned air is disposed downstream of the evaporator (11) in the air-conditioned air passage (2).
The cooling mode of 1), the heating mode by the heat radiation action of the condenser (12), and the dehumidification mode by which the air cooled by the cooling action of the evaporator (11) is reheated by the heat radiation action of the condenser (12). In the settable refrigeration cycle device, when the heating mode is started, the necessity of the oil discharge mode for discharging the bed oil of the evaporator (11) is determined, and it is determined that the oil discharge mode is necessary. After condensing the gas refrigerant discharged from the compressor (22) in the condenser (12), the pressure reducing means (26, 27, 3)
3, 35), outdoor heat exchanger (24) and evaporator (1
It is characterized in that an oil discharge mode for allowing the compressor (22) to pass through 1) is set, and after the oil discharge mode is executed for a predetermined time, a heating mode is set.

The determination means for determining the necessity of the oil discharge mode can be constituted specifically by the step (S104) in FIGS. 8 and 11. Specifically, it can be constituted by the step (S105) in FIG. 8 or the step (S105 ′) in FIG. 11, and the means for setting the heating mode is, specifically, the step (S107) in FIG. Can be configured.

According to the first to fifth aspects of the present invention, when the oil discharge mode is necessary at the time of starting the heating mode, the oil discharge mode is set, and even if the heating mode is set, the evaporator (11) is set. The liquid refrigerant containing the lubricating oil, which has been laid in the evaporator (11) during cooling, can be discharged by flowing the refrigerant through a path passing through. As a result, it is possible to improve the return of oil to the compressor during the transition from the cooling operation to the heating operation, and it is possible to eliminate insufficient lubrication of the compressor.

In addition, in the oil discharge mode at the time of starting heating, refrigerant flows through both the outdoor heat exchanger (24) and the evaporator (11), thereby reducing the amount of heat absorbed (cooling capacity) in the evaporator (11). Since the temperature can be suppressed, it is possible to avoid a phenomenon in which the temperature of the indoor blown air at the time of starting the heating is excessively lowered and the heating feeling is deteriorated. Therefore, the sleeping oil in the cooling evaporator (11) can be discharged while avoiding deterioration of the heating feeling at the time of starting the heating.
According to the second aspect of the present invention, in the dehumidification mode, specifically, after the gas refrigerant discharged from the compressor (22) is condensed in the condenser (12), the condensed refrigerant is decompressed by the pressure reducing means (26, 2).
7) The pressure is reduced to a low pressure by the evaporator (11) or the evaporator (11) and the outdoor heat exchanger (2).
4), the mixture is evaporated and then sucked into the compressor (22). In the oil discharge mode, the compressor (2)
After condensing the discharged gas refrigerant in 2) in the condenser (12), the condensed refrigerant is reduced to a low pressure by the decompression means (26, 27), and the low-pressure refrigerant is evaporated to the evaporator (11) and the outdoor heat exchanger ( After passing through the parallel circuit of 24) and evaporating, the refrigerant is sucked into the compressor (22). By switching the refrigerant flow, the dehumidification mode and the oil discharge mode can be executed.

According to the third aspect of the invention, in the cooling mode, the condenser (12) is cut off from the flow of the conditioned air in the conditioned air passage (2), and the discharge gas of the compressor (22) is discharged. After passing through the condenser (12), the refrigerant is condensed in the outdoor heat exchanger (24), and the condensed refrigerant is decompressed (35)
The pressure is reduced to a low pressure by the evaporator (1).
After being evaporated in 1), the refrigerant is sucked into the compressor (22). In the heating mode, the gas refrigerant discharged from the compressor (22) is condensed by the condenser (12), and the condensed refrigerant is decompressed (33). To evaporate the low-pressure refrigerant in the outdoor heat exchanger (24) and then suck it into the compressor (22). In the dehumidification mode, the discharge gas refrigerant of the compressor (22) is condensed by the condenser ( 12), the condensed refrigerant is decompressed by the first decompression means (33) of the decompression means, and then passed through the outdoor heat exchanger (24), and thereafter, the second decompression means (35) of the decompression means After the pressure is reduced again by evaporating, the evaporator (11) evaporates and sucks the compressed air into the compressor (22). In the oil discharging mode, the dehumidifying mode is set. Such switching of the refrigerant flow can also execute a dehumidification mode as a cooling mode, a heating mode, a dehumidification mode, and an oil discharge mode.

Further, when the rotation speed of the compressor (22) is increased to a predetermined rotation speed or more in the oil discharge mode, the amount of refrigerant circulating in the cycle is increased. Thereby, discharge of the sleeping oil in the evaporator (11) can be promoted. Claim 5
When the outside air temperature is equal to or higher than the predetermined temperature as described in the invention described above, the necessity of the oil discharge mode is determined to be necessary. It can be carried out.

The reference numerals in parentheses of the above means indicate the correspondence with the concrete means described in the embodiments described later.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 shows the overall structure of a first embodiment in which the present invention is applied to an air conditioner for an electric vehicle, and is substantially the same as that of Japanese Patent Application Laid-Open No. 9-39550. The air-conditioning unit 1 is installed in the cabin of an electric vehicle, and the air-conditioning duct 2 forms an air-conditioned air passage for guiding conditioned air into the cabin. This air conditioning duct 2
The suction ports 3, 4, and 5 for sucking inside and outside air are provided at one end side. The inside air suction port 4 and the outside air suction port 5 are switched and opened and closed by an inside / outside air switching door 6.

A blower 7 for blowing air into the air-conditioning duct 2 is provided adjacent to the suction ports 3 to 5, and the blower 7 includes a motor 7a and centrifugal fans 7b, 7b driven by the motor 7a. It is composed of On the other hand, the other end of the air-conditioning duct 2 has a plurality of air outlets communicating with the passenger compartment, that is, foot air outlets 8 for blowing the air-conditioned air toward the feet of the passengers in the passenger compartment. A face outlet 9 for blowing out air and a defroster outlet 10 for blowing out conditioned air are formed on the inner surface of the vehicle windshield.

A cooling evaporator 11 is provided in the air-conditioning duct 2 downstream of the blower 7 in the air. The cooling evaporator 11 is an indoor heat exchanger that constitutes a part of the refrigeration cycle 21. In a cooling operation and a dehumidifying operation mode, which will be described later, the air in the air conditioning duct 2 is absorbed by a heat absorbing effect of the refrigerant flowing inside. Function as a cooler to dehumidify and cool.

A heating condenser 12 is provided in the air conditioning duct 2 downstream of the cooling evaporator 11 in the air. The heating condenser 12 includes a refrigeration cycle 21.
And functions as a heater that heats the air in the air-conditioning duct 2 by radiating the refrigerant flowing inside during a heating operation and a dehumidifying operation mode to be described later.

The air flow path in the air conditioning duct 2 is divided by a partition wall 13 into a first air flow path 14 on the foot outlet 8 side.
And a second air passage 15 on the side of the face outlet 9 and the defroster outlet 10.
The two divisions 4 and 15 reduce the heating load by sucking high-temperature inside air from the inside air inlet 3 into the air flow path 14 on the side of the foot outlet 8 and blowing warm air to the feet in winter, The low-humidity outside air is sucked into the air passage 15 on the side of the defroster outlet 10 from the outside air suction port 5 so as to reliably prevent fogging of the front window.

The door 16 opens and closes the second air passage 15, the door 17 opens and closes a partition between the first and second air passages 14 and 15, and the doors 19 to 20 open and close the respective air passages. It is a door that opens and closes the air passages of the outlets 8, 9, and 10. Incidentally, the refrigeration cycle 21 is configured as a heat pump refrigeration cycle for cooling and heating the vehicle interior by the cooling evaporator 11 and the heating condenser 12. In addition, the following equipment is provided.

That is, the refrigerant compressor 22, the electromagnetic four-way valve 23 for switching the flow of the refrigerant, the outdoor heat exchanger 24, the gas-liquid separator 25 for separating the refrigerant gas and liquid and storing the liquid refrigerant, The cycle high-pressure side refrigerant introduced into the liquid separator 25 is subjected to an intermediate pressure (for example, 4 to 15 kg / cm ^2).
Electrical expansion valve (first pressure reducing means) 26 for reducing the pressure to about
Temperature-operated expansion valve (second pressure reducing means) 27, solenoid valve 28
a, 28 b and check valves 29 a to 29 e are further provided in the refrigeration cycle 21.

The outdoor heat exchanger 24 is installed outside the vehicle compartment of the electric vehicle, and exchanges heat with the outside air blown by the electric outdoor fan 24a. Further, the refrigerant compressor 22 is an electric compressor, and an AC motor (not shown) is built in a sealed case integrally, and driven by this motor to perform suction, compression and discharge of the refrigerant. An AC voltage is applied to the AC motor of the refrigerant compressor 22 by an inverter 30, and the frequency of the AC voltage is adjusted by the inverter 30 to continuously change the motor rotation speed. Therefore, inverter 3
Reference numeral 0 denotes a means for adjusting the number of revolutions of the compressor 22, and a DC voltage from a vehicle-mounted battery 31 is applied to the inverter 30.

The refrigerant compressor 22 injects a discharge port 22a for discharging the compressed refrigerant, a suction port 22b for sucking the refrigerant on the low pressure side of the cycle, and an intermediate-pressure gas refrigerant separated by the gas-liquid separator 25. A gas injection port 22c is provided. The gas injection port 22c communicates with a gas refrigerant outlet 25a at the upper part of the gas-liquid separator 25 via a gas injection passage 22d having a check valve 29e.

A temperature-sensitive cylinder 27a of a temperature-operated expansion valve 27 is provided in a refrigerant suction passage 22e connected to the suction port 22b, and the degree of opening of the expansion valve 27 is determined by the temperature of the refrigerant in the suction passage 22e. The degree of superheat is adjusted to a predetermined value. The inverter 30 is provided with an air conditioning control device 40.
Is controlled. The air-conditioning control device 40 is an electronic control device composed of a microcomputer and its peripheral circuits.
a, 28b are also controlled. In this example, the four-way valve 23 and the solenoid valves 28a and 28b constitute a "path switching means for switching the circulation path of the refrigerant".

The control device 40 includes an outside air temperature sensor for detecting the outside air temperature, an evaporator temperature sensor for detecting the air temperature immediately after the cooling evaporator 11 is blown out, and a refrigerant pressure (cycle high pressure) discharged from the compressor 21. A sensor signal is input from an air conditioning sensor group 41 including a discharge pressure sensor and the like for detecting the pressure. Also, each lever of the air-conditioning control panel 50 (see FIG. 2) provided near the driver's seat in the vehicle cabin,
A signal from the switch group 50a is also input to the control device 40.

Although FIG. 1 does not show the electrical connection with the air conditioning controller 40, the doors 6, 16, 17, 1
The operations of 8, 19, 20, the blower 7, and the outdoor fan 24a are also controlled by the control device 40. The air conditioning control panel 50 shown in FIG. 2 is provided with the following operation members that are manually operated by an occupant. Reference numeral 51 denotes a temperature control lever for setting a target value of the temperature of the air blown into the vehicle compartment. In this example, the temperature control lever 51 is configured to set a target value for adjusting the rotation speed of the electric compressor 22. Further, the operation of the four-way valve 23 and the solenoid valves 28a and 28b is controlled in accordance with the target value set by the operation position of the temperature control lever, thereby switching the operation mode of the refrigeration cycle. That is, as shown in FIG. 3, by moving the operating position of the lever 51 from the left to the right, the cooling mode, the dehumidifying mode, and the heating mode can be sequentially set.

As shown in FIGS. 4, 5 and 6, by moving the operating position of the temperature control lever 51, the target evaporator air temperature is set during cooling, and the target high pressure is set during dehumidification and heating. It has become so. The operation position signal of the temperature control lever 51 is input to the control device 40, and the control device 40 operates the compressor so that the actual evaporator blown air temperature or high pressure detected by the sensor group 41 matches the target value. The number of rotations of the air blower 22 is controlled to control the temperature of the blown air.

Reference numeral 52 denotes an air volume switching lever of the blower 7; 53, an air conditioner switch for interrupting the operation of the compressor 22; 54, an air conditioning blow mode switching lever for switching the opening and closing of the outlet switching doors 18 to 20; 6 is an inside / outside air switching lever that opens and closes 6. Next, the operation of the above configuration will be described. FIG. 8 shows a control routine executed by the microcomputer of the control device 40. When the air conditioner switch 53 is turned on, the control routine of FIG. 8 starts, and initialization is performed in step S101. The flag F is set to 0, and the timer is started. Then, in step S102, the operation mode is determined based on the operation position of the temperature control lever 51.

If the temperature control lever 51 is operated between the PC1 position and the PC2 position in FIGS. 3 and 4, the cooling mode is selected, and the process proceeds to step S201, where the valve of the refrigeration cycle 21 (the four-way valve 23) is selected. And solenoid valve 2
8a, 28b) are set to the state of the cooling mode of FIG.
Thereby, in the refrigeration cycle of FIG.

That is, the high-temperature and high-pressure superheated gas refrigerant discharged from the compressor 22 flows into the outdoor heat exchanger 24 through the four-way valve 23 and the check valve 29b.
The gas refrigerant condenses by exchanging heat with the outside air blown by 4a. Next, the refrigerant flowing out of the outdoor heat exchanger 24 passes through the check valve 29d because the electromagnetic valve 28a is closed,
The pressure is reduced by the electric expansion valve 26 to be in a gas-liquid two-phase state at an intermediate pressure.

The intermediate-pressure gas-liquid two-phase refrigerant is supplied to the gas-liquid separator 2.
5, where the refrigerant is separated into a saturated gas refrigerant and a saturated liquid refrigerant. The gas refrigerant passes from the gas refrigerant outlet 25a at the upper part of the gas-liquid separator 25 through the gas injection passage 22d and the check valve 29e to the gas injection port 22c.
The intermediate pressure gas refrigerant is injected from the port 22c into a part of the compressor 22 in the middle of the compression process.

On the other hand, the liquid refrigerant in the gas-liquid separator 25 flows out from the liquid refrigerant outlet 25b opened near the bottom of the gas-liquid separator 25, and is decompressed by the temperature-operated expansion valve 27.
After passing through 8b, it flows into the evaporator 11. In the evaporator 11, the refrigerant absorbs heat from the air blown by the blower 7 and evaporates. The cool air absorbed by the evaporator 11 and cooled is blown out from the face outlet 9 into the vehicle compartment to cool the vehicle compartment.

The gas refrigerant evaporated in the evaporator 11 is sucked into the suction port 22b of the compressor 22 from the refrigerant suction passage 22e. At this time, the temperature of the compressor suction refrigerant is sensed by the temperature-sensitive cylinder 27a provided in the refrigerant suction passage 22e and transmitted to the expansion valve 27, so that the expansion valve 27 has a predetermined degree of superheat of the compressor suction refrigerant. Thus, the flow rate of the refrigerant flowing into the evaporator 11 is adjusted.

Next, when the temperature control lever 51 is operated between the PD1 position and the PD2 position in FIGS. 3 and 5, the dehumidification mode is selected in step S102, and the process proceeds to step S202, where the valve ( Four-way valve 23
And the solenoid valves 28a and 28b) are set to the state of the dehumidification mode in FIG. Thereby, in the refrigeration cycle of FIG.

That is, the gas refrigerant discharged from the compressor 22 flows into the indoor condenser 12 through the four-way valve 23, and exchanges heat (radiates) with the air blown by the blower 7 here. The gas refrigerant condenses. And the condenser 12
The refrigerant flowing out of the pump passes through the check valve 29c and is decompressed by the electric expansion valve 26 to be in a gas-liquid two-phase state at an intermediate pressure. The intermediate-pressure gas-liquid two-phase refrigerant flows into the gas-liquid separator 25,
The gas refrigerant separated here passes from the gas refrigerant outlet 25a at the upper part of the gas-liquid separator 25 through the gas injection passage 22d and the check valve 29e to the gas injection port 22c.
Inhaled.

On the other hand, the liquid refrigerant in the gas-liquid separator 25 flows out from the liquid refrigerant outlet 25b and is reduced to a low pressure by the temperature-operated expansion valve 27. When the solenoid valve 28a is closed, the low-pressure refrigerant flows into the evaporator 11 only through the solenoid valve 28b, where it absorbs heat from the air blown by the blower 7 and evaporates. When the solenoid valve 28a is opened,
The low-pressure refrigerant decompressed by the temperature-operated expansion valve 27 flows into the outdoor heat exchanger 24 through the check valve 29a as indicated by a dashed arrow D, where it absorbs heat from outside air and evaporates.

At the same time, the low-pressure refrigerant decompressed by the temperature-operated expansion valve 27 passes through the solenoid valve 28b and passes through the evaporator 11
, And heat is absorbed from the air blown by the blower 7 to evaporate. And only the evaporator 11 or the evaporator 11
Then, the refrigerant evaporated in the parallel circuit of the outdoor heat exchanger 24 is sucked into the compressor 22. Here, the opening and closing of the solenoid valve 28a is performed according to the temperature of the blown air from the evaporator 11, and the temperature of the blown air from the evaporator 11 is set to the target blown air temperature (for example,
When the temperature is lower than the outside air temperature (−5 ° C.), the solenoid valve 28a is closed to allow the refrigerant to flow only into the evaporator 11, and conversely, when the temperature of the air blown out of the evaporator 11 is higher than the target air temperature. Opens the electromagnetic valve 28a, allows the refrigerant to flow into the outdoor heat exchanger 24 in parallel, and adjusts (suppresses) the amount of heat absorbed by the evaporator 11.

As described above, by adjusting the amount of heat absorbed by the evaporator 11, the temperature of the air blown out of the evaporator 11 can be maintained at the target air temperature. As described above, in the dehumidification mode, the refrigerant flows through both the evaporator 11 and the condenser 12 installed in the indoor air conditioning unit 1, and the air blown by the blower 7 is first cooled and dehumidified by the evaporator 11, and thereafter, It is reheated in the condenser 12. Here, since the heat radiation amount of the refrigerant in the condenser 12 is obtained by adding the power consumption of the compressor 22 to the heat absorption amount in the evaporator 11, the air temperature at the outlet side of the condenser 12 is 5, higher than the intake air temperature. Therefore, it is possible to perform heating while performing dehumidification.

Next, when the temperature control lever 51 is operated between the PH1 position and the PH2 position in FIGS. 3 and 6, the heating mode is selected in step S102, and the flow advances to step S103 to determine whether the flag F = 0. I do. Flag F
Has been initialized to F = 0 in step S101, so the determination in step S103 is YES, the process proceeds to step S104, and the outside air temperature Tam rises from a predetermined temperature (15 ° C. in this example) corresponding to the middle season. Determine if it is high.

This judgment is for judging whether or not this is the first operation of shifting from the cooling mode to the heating mode. That is, during the first heating operation in the transition from the cooling mode to the heating mode, it is necessary to discharge the liquid refrigerant containing the lubricating oil lying inside the cooling evaporator 11 from the cooling evaporator 11. If the heating operation is the second or subsequent heating operation after shifting from the heating mode to the heating mode, the sleeping oil in the cooling evaporator 11 has already been discharged at the time of starting the previous heating operation. It is not necessary to set.

If it is determined in step S104 that the outside air temperature is equal to or higher than 15 ° C., it is determined that the operation is the first operation of shifting from the cooling mode to the heating mode, and the process proceeds to step S105, where the refrigeration cycle is performed. 21 valves (four-way valve 2
3 and the solenoid valves 28a, 28b) are set to the oil discharge mode (deformed dehumidification mode) shown in FIG. By the switching of the valve operating position, in the refrigeration cycle of FIG. 1, the refrigerant flows through the path of the dehumidification mode shown by the arrow D, and at the same time, the refrigerant is moved from the temperature-operated expansion valve 27 to the check valve 29a by opening the solenoid valve 28a. , And also flows to the outdoor heat exchanger 24 side. That is, in the oil discharge mode, the refrigerant depressurized by the temperature-operated expansion valve 27 flows through the cooling evaporator 11 and the outdoor heat exchanger 24 in parallel.

As a result, during the cooling operation, the cooling evaporator 1
The liquid refrigerant containing the lubricating oil laid inside 1 is pushed out by the refrigerant flow passing through the cooling evaporator 11, and is returned to the compressor 22. In addition, at this time, since the refrigerant flows through the cooling evaporator 11 and the outdoor heat exchanger 24 in parallel, the flow rate of the refrigerant to the cooling evaporator 11 decreases, and the cooling capacity is suppressed accordingly. It is possible to avoid a phenomenon in which the temperature of the indoor blown air at the time of startup is too low and the heating feeling is deteriorated.

That is, the sleeping oil in the cooling evaporator 11 can be discharged while avoiding deterioration of the heating feeling when the heating is started. In the next step S106, it is determined whether or not a predetermined time, for example, 5 minutes, has elapsed in the timer time started in step S101. If the timer time is within 5 minutes, the oil discharge mode in step S105 is continued. The discharge of the sleeping oil in the cooling evaporator 11 is terminated.

When the execution time of the oil discharge mode has elapsed for 5 minutes, the valves (four-way valve 23 and solenoid valves 28a, 28b) of the refrigeration cycle 21 are set to the heating mode shown in FIG. 7 in the next step S107. As a result, in the refrigeration cycle of FIG. That is, the gas refrigerant discharged from the compressor 22 flows through the four-way valve 23 into the condenser 12 on the indoor side, where it exchanges heat (radiates) with the air blown by the blower 7 to generate gas refrigerant. Condense. The warm air heated by the heat release of the gas refrigerant is mainly blown out from the foot outlet 8 into the vehicle interior to heat the interior of the vehicle.

The refrigerant flowing out of the condenser 12 is
Through the check valve 29c, the pressure is reduced by the electric expansion valve 26,
It becomes a gas-liquid two-phase state of intermediate pressure. The intermediate-pressure gas-liquid two-phase refrigerant flows into the gas-liquid separator 25, and the separated gas refrigerant flows from the gas refrigerant outlet 25a at the upper part of the gas-liquid separator 25 into the gas injection passage 22d and the check valve 29e. Through
It is sucked into the gas injection port 22c.

On the other hand, the liquid refrigerant in the gas-liquid separator 25 flows out of the liquid refrigerant outlet 25b, is decompressed by the temperature-operated expansion valve 27, passes through the check valve 29a, and then passes through the outdoor heat exchanger 24.
Flows into. In the outdoor heat exchanger 24, the refrigerant absorbs heat from the blown air (outside air) of the outdoor fan 24a and evaporates. The gas refrigerant evaporated in the outdoor heat exchanger 24 passes through the solenoid valve 28a and flows from the refrigerant suction passage 22e to the suction port 2 of the compressor 22.
2b.

Since the flag F is set to 1 in the next step S108, the determination in step S103 is NO, and the heating mode in step S107 is continued. If the outside air temperature Tam is lower than 15 ° C., it is considered that the heating operation is the second or later heating operation after the transition from the cooling mode to the heating mode, and the process proceeds directly from step S104 to step S104.
Proceeding to 107, the heating mode is set.

(Second Embodiment) FIG. 9 shows the entire configuration of the second embodiment, and the same reference numerals as those in FIG. 1 denote the same or equivalent parts. Hereinafter, differences between the second embodiment and the first embodiment will be mainly described. First, the air conditioning unit 1
A heating condenser 12 is disposed at a central portion in the air conditioning duct 2, and a bypass passage 12 a is provided beside the heating condenser 12.
A switching door 12 is provided between the heating condenser 12 and the air flowing into the bypass passages 12a and 12b.
It can be switched by c and 12d.

That is, in the heating mode and the dehumidification mode, the switching doors 12c and 12d are operated to the positions indicated by solid lines to allow air to flow into the heating condenser 12, while in the cooling mode, the switching doors 12c and 12d are operated. By operating at the position indicated by the broken line in the drawing, the air is prevented from flowing into the heating condenser 12, and the air is passed through the bypass passages 12a and 12b. next,
The refrigeration cycle 21 has a cycle configuration that does not have a gas injection function (a configuration of an accumulator cycle). Therefore, the accumulator 32 is installed on the suction side of the electric compressor 22, and the accumulator 3
At 2, the gas-liquid of the refrigerant sucked into the compressor 22 is separated, and the gas refrigerant is sucked into the compressor 22 from the gas extraction pipe 32a. Further, as is well known, the liquid refrigerant stored in the accumulator 32 is sucked through a minute oil return hole (not shown) at the bottom of the gas extraction pipe 32a, and the compressor 22
Reflux to

In the refrigeration cycle 21, a heating-side electric expansion valve (heating-side pressure reducing means, first pressure reducing means) is provided between the outlet side of the heating condenser 12 and the inlet side of the outdoor heat exchanger 24. 33 and a solenoid valve 34 are provided in parallel. Further, between the outlet side of the outdoor heat exchanger 24 and the inlet side of the cooling evaporator 11, a cooling-side electric expansion valve (cooling-side depressurizing means, second depressurizing means) 35 is provided, and the outdoor heat exchanger 24 is provided. A bypass passage 36 is provided to directly connect the outlet side of the air conditioner (the inlet side of the cooling-side electric expansion valve 35) and the inlet side of the accumulator 32, and an electromagnetic valve 37 is provided in the bypass passage 36.

The second embodiment is configured as described above, and its control is performed according to the control flowchart of FIG. 11 is different from FIG. 8 in that step S105 ′ is different from step S10 of the second embodiment in FIG.
Instead of the 5 oil discharge mode (deformation dehumidification mode),
The only difference is that the dehumidification mode itself is adopted as the oil discharge mode.

When the cooling mode is selected in step S102, in step S201, the switching doors 12c and 12d are connected to the bypass passage 12 as shown in FIG.
The electromagnetic valves 34 are operated to the open position and the electromagnetic valve 37 is operated to the closed position at the same time as the air is shut off by operating the open positions a and 12b to the condenser 12 for heating. Thereby, in the refrigeration cycle 21, the compressor 22 → the heating condenser 12 → the solenoid valve 34 → the outdoor heat exchanger 24 → the cooling side electric expansion valve 35 → the cooling evaporator 11 → the accumulator 3
Refrigerant flows through the path from 2 to the compressor 22.

At this time, since heat exchange with the air is hindered by the heating condenser 12, the condenser 12 merely serves as a refrigerant passage, and the gas discharged from the compressor 22 is The gas passes through the solenoid valve 34 in a gaseous state, and is condensed in the outdoor heat exchanger 24. Then, the condensed refrigerant is decompressed by the cooling-side electric expansion valve 35 so that the low-pressure gas-liquid 2
This low-pressure refrigerant is absorbed by the cooling evaporator 11 from the blast air in the air-conditioning duct 2 and evaporated, and then is sucked into the compressor 22 through the accumulator 32.
The blast air in the air conditioning duct 2 is cooled by the cooling evaporator 11 to become cool air, and is blown into the vehicle interior through the bypass passages 12a and 12b.

On the other hand, when the dehumidification mode is selected in step S102, in step S202, as shown in FIG. 10B, the switching doors 12c and 12d are
The solenoid valves 34 and 37 are operated at the same time as the air flows into the heating condenser 12 by being operated to the closed positions of the heating valves 12a and 12b.
Are both operated to the closed position. Thereby, in the refrigeration cycle 21, the compressor 22 → the heating condenser 12 → the heating side electric expansion valve 33 → the outdoor heat exchanger 24 → the cooling side electric expansion valve 35 → the cooling evaporator 11 → the accumulator 32.
→ The refrigerant flows through the path of the compressor 22. As a result, the blast air in the air conditioning duct 2 is cooled by the cooling evaporator 11 and then reheated by the heating condenser 12 to set the dehumidification mode.

The refrigerant in the cycle is decompressed in two stages by the heating-side electric expansion valve 33 and the cooling-side electric expansion valve 35, so that the opening degrees (throttle amounts) of the two expansion valves 33, 35 are reduced. Can be switched between the case where the action of the outdoor heat exchanger 24 exhibits the endothermic action as the evaporator and the case where the action of the outdoor heat exchanger 24 exerts the heat dissipation action as the condenser. Can be controlled.

Next, the outline of the opening control of the electric expansion valves 33 and 35 in the dehumidifying mode will be described. The opening pattern KPN of the electric expansion valves 33 and 35 is shown in a control map (micro (Stored in the ROM of the computer) according to the outside air temperature Tam and the air volume level of the blower 7. Here, the air volume level is LO
To HI.

Next, the initial opening EVH of the heating-side electric expansion valve 33 and the cooling-side electric expansion valve 3 according to the control map shown in FIG.
5 is determined. Here, the flow characteristics of the expansion valve with respect to the opening degrees EVH and EVC in FIG. 13 are, for example, as shown in FIG. Note that the number of pulses on the horizontal axis in FIG. 14 is the number of pulses applied to the step motor that constitutes the actuator of both electric expansion valves 33 and 35.
The opening degree of the expansion valve is increased by increasing the number of applied pulses.

After setting the initial opening as described above and starting the refrigeration cycle, based on the opening pattern KPN in FIG. 12, the opening of both electric expansion valves 33 and 35 is changed to the cycle high pressure (compressor discharge). Is controlled to reach the target high pressure. That is, when the actual cycle high pressure> the target high pressure, the value of the opening degree pattern KPN is increased. This opening degree pattern K
Due to the increase in PN, the opening EV of the heating-side electric expansion valve 33 is increased.
Since H increases and the opening EVC of the cooling-side electric expansion valve 35 decreases, the outdoor heat exchanger 24 is on the high pressure side, that is, on the heat radiation side, and the cycle high pressure is reduced to approach the target high pressure.

Conversely, when the actual cycle high pressure <the target high pressure, the value of the opening degree pattern KPN is reduced. Due to the decrease in the opening degree pattern KPN, the heating-side electric expansion valve 33 is provided.
Is decreased and the opening EVC of the cooling-side electric expansion valve 35 is increased, so that the outdoor heat exchanger 24 is on the low pressure side, that is, on the heat absorption side, and the cycle high pressure is increased to approach the target high pressure. The temperature of the air blown from the cooling evaporator 11 is controlled so as to reach the target evaporator air temperature (for example, the outside air temperature −5 ° C.) by controlling the compressor speed.

Next, if the heating mode is selected in step S102, the process proceeds to step S103 and step S104. If the outside temperature Tam is equal to or higher than 15 ° C., the process proceeds to step S102.
Proceeding to 105 ', the dehumidification mode is selected as the oil discharge mode. This dehumidification mode is exactly the same as the above-mentioned dehumidification mode. As described above, the compressor 22 → the heating condenser 12 → the heating-side electric expansion valve 33 → the outdoor heat exchanger 2
The refrigerant flows through the path of 4 → cooling side electric expansion valve 35 → cooling evaporator 11 → accumulator 32 → compressor 22.

As a result, during the cooling operation, the cooling evaporator 1
The liquid refrigerant containing the lubricating oil laid inside 1 is pushed out by the refrigerant flow passing through the cooling evaporator 11, and is returned to the compressor 22. In addition, at this time, the refrigerant flows in series through the cooling evaporator 11 and the outdoor heat exchanger 24, and the opening degree of the electric expansion valves 33 and 35 controls the outdoor heat exchanger 24 to the low pressure side so that the evaporator functions as an evaporator. The amount of heat absorbed (cooling capacity) in the cooling evaporator 11 by performing the heat absorbing action.
Therefore, it is possible to avoid a phenomenon in which the temperature of the indoor blown air at the time of starting heating is excessively lowered and the heating feeling is deteriorated.

Therefore, also in the second embodiment, the sleeping oil in the cooling evaporator 11 can be discharged while avoiding the deterioration of the heating feeling when the heating is started. Note that, also in the dehumidification mode as the oil discharge mode in step S105 ', both electric expansion valves 33,
The opening degree control of 35 is basically the same as that in the above-described dehumidification mode, and the opening degree of both electric expansion valves 33 and 35 near the outside air temperature Tam = 15 ° C. is shown in FIGS. As understood from the characteristics, the opening degree E of the heating-side electric expansion valve 33 is determined.
VH <opening EVC of the cooling-side electric expansion valve 35, the outdoor heat exchanger 24 is on the low-pressure side (heat-absorbing side), and the dehumidification mode for heating is set.

In FIG. 11, the above step S105 '
After executing the dehumidification mode as the oil discharge mode for a predetermined time, the valve is operated to the heating mode position in step S107. That is, as shown in FIG.
The switching doors 12c and 12d are connected to the bypass passages 12a and 12b.
The solenoid valve 34 is operated to the closed position and the electromagnetic valve 37 is operated to the open position at the same time as the air is caused to flow into the heating condenser 12 by operating to the closed position.

As a result, in the refrigeration cycle 21,
Compressor 22 → heating condenser 12 → heating side electric expansion valve 3
3 → outdoor heat exchanger 24 → solenoid valve 37 (bypass passage 3
6) Refrigerant flows through the path of → accumulator 32 → compressor 22. Thereby, the refrigerant decompressed to a low pressure by the heating-side electric expansion valve 33 evaporates and absorbs heat in the outdoor heat exchanger 24, and the refrigerant radiates condensation heat in the heating condenser 12 to perform a heating function. Fulfill.

(Other Embodiments) The first and second embodiments described above
In the embodiment, in steps S105 and S105 'for setting the oil discharge mode, the rotation speed of the electric compressor 22 is forcibly increased and held at a predetermined rotation speed (for example, 2000 rpm) or more to circulate the refrigerant in the cycle. The amount may be increased, thereby expediting the drainage of the sleeping oil in the evaporator 11.

In the first and second embodiments described above, at the time of starting the heating mode, in order to determine the necessity of the oil discharging mode for discharging the sleeping oil of the evaporator 11, it is determined in step S104 that Although it is determined that the outside air temperature Tam ≧ 15 ° C., for example, the temperature of the air blown into the vehicle interior necessary to maintain the vehicle interior at the target temperature is calculated, and this required air temperature is higher than a predetermined temperature. At this time, it may be determined that the oil discharge mode is necessary.

The present invention is not limited to a refrigeration cycle apparatus for vehicle air conditioning, but can be widely applied to various uses.

[Brief description of the drawings]

FIG. 1 is a refrigeration cycle diagram showing a first embodiment of the present invention.

FIG. 2 is a front view of an air conditioner control panel used in the first embodiment.

FIG. 3 is a characteristic diagram of an entire operation range of a temperature control lever in the air conditioner control panel of FIG. 2;

FIG. 4 is a characteristic diagram of a cooling region of the temperature control lever.

FIG. 5 is a characteristic diagram of a dehumidification region of the temperature control lever.

FIG. 6 is a characteristic diagram of a heating region of the temperature control lever.

FIG. 7 is a table for explaining an operation of a valve used in the first embodiment.

FIG. 8 is a control flowchart according to the first embodiment.

FIG. 9 is a refrigeration cycle diagram showing a second embodiment of the present invention.

FIG. 10 is a refrigeration cycle diagram for explaining the operation of the second embodiment.

FIG. 11 is a control flowchart according to the second embodiment.

FIG. 12 is a control map of an expansion valve opening pattern according to the second embodiment.

FIG. 13 is a control map of an expansion valve opening degree in the second embodiment.

FIG. 14 is a control map of an expansion valve flow rate in the second embodiment.

[Explanation of symbols]

11 evaporator, 12 condenser, 22 compressor, 24 outdoor heat exchanger, 25 gas-liquid separator, 26 electric expansion valve (first pressure reducing means), 27 temperature-operated expansion valve ( Second pressure reducing means), 33: heating-side electric expansion valve (heating-side pressure reducing means), 35: cooling-side electric expansion valve (cooling-side pressure reducing means).

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code FI F25B 13/00 361 F25B 13/00 361 (72) Inventor Katsuya Tanaka 1-1-1, Showa-cho, Kariya-shi, Aichi Pref.

Claims (5)

[Claims] 1. An air-conditioned air passage (2) for passing air-conditioned air toward a room, a blower (7) for blowing the air-conditioned air through the air-conditioned air passage (2), and an air-conditioned air passage (2). An evaporator (11) arranged to cool the conditioned air; and a condenser (12) arranged in the conditioned air passage (2) downstream of the evaporator (11) to heat the conditioned air. An outdoor heat exchanger (24) installed outside the air-conditioned air passage (2) and performing heat exchange between outside air and a refrigerant; and an evaporator (11) or the outdoor heat exchanger (24). A compressor (2) that sucks, compresses, and discharges refrigerant from the outlet side
2) and decompression means (26, 27, 27) for decompressing and expanding the refrigerant condensed in the condenser (12) or the outdoor heat exchanger (24).
33, 35), the air cooled by the cooling action of the evaporator (11), the heating mode by the heat dissipation action of the condenser (12), and the air cooled by the cooling action of the evaporator (11). In a refrigeration cycle apparatus capable of setting a dehumidifying mode in which reheating is performed by a heat radiation action of a condenser (12), a necessity of an oil discharge mode for discharging bed oil of the evaporator (11) when the heating mode is activated. Determining means (S104), and when the determining means (S104) determines that the oil discharge mode is necessary, the compressor (22)
After condensing the discharged gas refrigerant in the condenser (12), the refrigerant is passed through the pressure reducing means (26, 27, 33, 35), the outdoor heat exchanger (24) and the evaporator (11), Oil discharge mode setting means (S105, S105) for setting an oil discharge mode to be sucked into the compressor (22).
105 '), and a heating mode setting means (S107) for setting the heating mode after executing the oil discharge mode for a predetermined time. 2. The compressor (2) in the dehumidification mode.
After condensing the discharged gas refrigerant of 2) in the condenser (12), the condensed refrigerant is depressurized to a low pressure by the decompression means (26, 27), and the low-pressure refrigerant is decompressed by the evaporator (1).
1) Alternatively, after being evaporated in both the evaporator (11) and the outdoor heat exchanger (24), the oil is sucked into the compressor (22). In the oil discharge mode, the compressor ( 2
After condensing the discharged gas refrigerant of 2) in the condenser (12), the condensed refrigerant is depressurized to a low pressure by the decompression means (26, 27), and the low-pressure refrigerant is decompressed by the evaporator (1).
The refrigeration cycle apparatus according to claim 1, wherein the refrigerant is vaporized by passing through a parallel circuit of (1) and the outdoor heat exchanger (24), and then sucked into the compressor (22). 3. The condenser (1) in the cooling mode.
2) is cut off from the flow of the conditioned air in the conditioned air passageway (2), and the outdoor heat exchanger (2) passes the refrigerant gas discharged from the compressor (22) after passing through the condenser (12).
4) and the condensed refrigerant is decompressed by the pressure reducing means (35).
, The low-pressure refrigerant is evaporated by the evaporator (11) and then sucked into the compressor (22). In the heating mode, the discharge gas refrigerant of the compressor (22) is The condensed refrigerant is condensed in a condenser (12), the condensed refrigerant is decompressed to a low pressure by the decompression means (33), and the low-pressure refrigerant is evaporated in the outdoor heat exchanger (24) and then sucked into the compressor (22). In the dehumidification mode, the gas refrigerant discharged from the compressor (22) is condensed by the condenser (12), and the condensed refrigerant is depressurized by the first decompression means (33) of the decompression means. After passing through the outdoor heat exchanger (24), the pressure is reduced again by the second pressure reducing means (35) of the pressure reducing means, and then evaporated by the evaporator (11) to the compressor (22). Inhaled Manner, further, wherein the oil discharge mode, the refrigeration cycle apparatus according to claim 1, characterized in that setting the dehumidifying mode. 4. The refrigeration cycle apparatus according to claim 1, wherein a rotation speed of the compressor is increased to a predetermined rotation speed or more in the oil discharge mode. 5. The method according to claim 1, wherein the determining unit determines that the oil discharge mode is necessary when the outside air temperature is equal to or higher than a predetermined temperature.
A refrigeration cycle apparatus according to any one of the above.