JP2018035972A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device including an evaporation pressure regulation valve, constituted to switch a refrigerant circuit, and capable of suppressing frost formation on a heat exchanger for cooling.SOLUTION: An evaporation pressure regulation valve 19 for raising a refrigerant evaporation pressure in an indoor evaporator 18 in accompany with increase of a flow rate of a refrigerant circulated in the indoor evaporator 18, is disposed at a downstream side of the indoor evaporator 18, and a pressure regulation characteristic of the evaporation pressure regulation valve 19 is determined according to the flow rate of the refrigerant circulated in a cooling mode. In a dehumidification heating mode in which the flow rate of the refrigerant is reduced in comparison with that in a cooling mode, the control to prevent temperature down is executed by changing an area ratio Ae2/Ae1 of a second throttle passage area Ae2 of a second expansion valve 15b disposed at an upstream side of the indoor evaporator 18 to a first throttle passage area Ae1 of a first expansion valve 15a disposed at an upstream side of an outdoor heat exchanger 16, so that the flow rate of the refrigerant is increased with respect to a reference flow rate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a refrigeration cycle apparatus including an evaporation pressure adjusting valve and configured to be able to switch a refrigerant circuit.

  Conventionally, Patent Document 1 discloses a refrigeration cycle apparatus applied to a vehicle air conditioner. The refrigeration cycle apparatus disclosed in Patent Document 1 includes a heating mode refrigerant circuit that heats blown air blown into a vehicle interior, a dehumidifying heating mode refrigerant circuit that reheats cooled and dehumidified blown air, and blown air. The cooling mode refrigerant circuit for cooling is configured to be switchable.

  More specifically, in the refrigeration cycle apparatus of Patent Document 1, in the dehumidifying heating mode, the indoor evaporator that is a cooling heat exchanger that evaporates the refrigerant and cools the blown air and the outdoor heat that exchanges heat between the refrigerant and the outside air. The exchanger switches to a refrigerant circuit connected in parallel to the refrigerant flow. In this refrigerant circuit, after the blown air is cooled by the indoor evaporator, the heat absorbed from the outside air by the outdoor heat exchanger is radiated to the blown air by the indoor condenser which is a heat exchanger for heating. The air is reheated.

  Furthermore, in the refrigeration cycle apparatus of Patent Document 1, an evaporation pressure adjusting valve is arranged on the downstream side of the refrigerant flow in the indoor evaporator. The evaporation pressure adjusting valve functions to adjust the refrigerant evaporation pressure in the indoor evaporator to be equal to or higher than a predetermined pressure regardless of the refrigerant evaporation pressure in the outdoor heat exchanger. Thereby, in the refrigerating cycle device of patent documents 1, it is going to control that frost formation will arise in an indoor evaporator at the time of dehumidification heating mode.

JP 2012-225637 A

  By the way, in the refrigeration cycle apparatus which can switch a refrigerant circuit like patent document 1, generally the suitable circulation refrigerant | coolant flow volume which circulates a cycle differs for every operation mode. Furthermore, in the refrigeration cycle apparatus of Patent Document 1, since the indoor evaporator and the outdoor heat exchanger are connected in parallel during the dehumidifying heating mode, the refrigerant flow rate flowing through the indoor evaporator during the cooling mode is This is less than the flow rate of refrigerant flowing through the evaporator.

  Further, the evaporation pressure adjustment valve of Patent Document 1 is configured by a mechanical mechanism, and the evaporation of the room increases with an increase in the flow rate of refrigerant flowing through the evaporation pressure adjustment valve (that is, the flow rate of refrigerant flowing through the indoor evaporator). It has a pressure regulation characteristic that raises the refrigerant evaporation pressure in the vessel. For this reason, in the refrigeration cycle apparatus of Patent Document 1, the refrigerant evaporation pressure in the indoor evaporator in the cooling mode is higher than the refrigerant evaporation pressure in the indoor evaporator in the dehumidifying heating mode.

  Therefore, if the pressure regulation characteristic of the evaporation pressure adjustment valve is set so that frosting of the indoor evaporator can be suppressed during the dehumidifying heating mode, the temperature of the blown air cannot be lowered to a desired temperature during the cooling mode. There is a risk that.

  On the other hand, a means for increasing the refrigerant discharge capacity of the compressor in the cooling mode can be considered. However, if the refrigerant discharge capacity of the compressor is increased, the refrigerant circulation flow rate is increased, so that the refrigerant evaporation pressure adjusted by the evaporation pressure adjusting valve further increases. As a result, control interference that unnecessarily increases the refrigerant discharge capacity of the compressor is caused.

  For this reason, in the refrigerating cycle device of patent documents 1, it is desirable to set the pressure regulation characteristic of an evaporation pressure regulation valve so that the temperature of blowing air can be lowered to desired temperature at the time of air conditioning mode.

  However, if the pressure regulation characteristic of the evaporation pressure adjusting valve is set so that the temperature of the blown air can be lowered to a desired temperature in the cooling mode, the refrigerant evaporation temperature in the indoor evaporator is 0 ° C. in the dehumidifying heating mode. As a result, frost formation may occur in the indoor evaporator.

  In view of the above points, an object of the present invention is to suppress the occurrence of frost formation in a cooling heat exchanger of a refrigeration cycle apparatus that includes an evaporation pressure adjustment valve and is configured to be able to switch a refrigerant circuit. .

In order to achieve the above object, the invention according to claim 1 is a refrigeration cycle apparatus applied to an air conditioner,
A compressor (11) that compresses and discharges the refrigerant, a heating heat exchanger (12) that heats the blown air blown into the air-conditioning target space using the refrigerant discharged from the compressor as a heat source, and a pressure reduction of the refrigerant A first pressure reducing device (15a) to be performed, an outdoor heat exchanger (16) for exchanging heat between the refrigerant flowing out of the first pressure reducing device and the outside air, a second pressure reducing device (15b) for reducing the pressure of the refrigerant, and a second pressure reducing device A cooling heat exchanger (18) for exchanging heat between the refrigerant flowing out of the apparatus and the blown air before passing through the heating heat exchanger, and an evaporation pressure adjusting valve for adjusting the refrigerant evaporation pressure (Pe) in the cooling heat exchanger (19), a refrigerant circuit switching device (21, 22) for switching the refrigerant circuit, and a decompression device control unit (40c) for controlling the operation of the first decompression device and the second decompression device,
The evaporating pressure adjusting valve increases the refrigerant evaporating pressure (Pe) with an increase in the flow rate of the refrigerant flowing through the inside,
In the cooling mode in which the cooled blast air is blown out to the air-conditioning target space, the refrigerant circuit switching device causes the refrigerant flowing out from the heating heat exchanger to flow through the first pressure reducing device → the outdoor heat exchanger → the second pressure reducing device → the cooling heat exchanger. Switch to refrigerant circuit that flows in order of → Evaporative pressure adjustment valve → Compressor, and flow of refrigerant that has flowed out of the heat exchanger for heating in the dehumidifying heating mode in which the blown air that has been cooled and dehumidified is reheated and blown out to the air conditioning target space One of the branched refrigerants flows in the order of the first pressure reducing device → the outdoor heat exchanger → the compressor, and the other branched refrigerant flows in the second pressure reducing device → the heat exchanger for cooling → the evaporation pressure adjusting valve → Switch to the refrigerant circuit that flows in the order of the compressor,
In the dehumidifying and heating mode, the decompression device control unit controls the first throttle passage area of the first decompression device (Ge) so that the refrigerant flow rate (Ge) flowing through the evaporation pressure regulating valve is larger than a predetermined reference flow rate (KGe). This is a refrigeration cycle device that changes the area ratio (Ae2 / Ae1) of the second throttle passage area (Ae2) of the second decompression device to Ae1).

  According to this, since the refrigerant circuit switching device (21, 22) is provided, the refrigerant circuit in the cooling mode and the refrigerant circuit in the dehumidifying heating mode can be switched.

  Further, the decompression device is configured so that the refrigerant flow rate (Ge) is larger than the reference flow rate (KGe) in the dehumidifying heating mode in which the refrigerant flow rate (Ge) flowing through the evaporation pressure regulating valve (19) is smaller than that in the cooling mode. The control unit (40c) changes the area ratio (Ae2 / Ae1). Therefore, the refrigerant evaporation pressure in the cooling heat exchanger (18) can be maintained at a certain pressure or higher in the dehumidifying heating mode.

  Thus, the reference flow rate (KGe) is set so that the refrigerant evaporation temperature (Te) becomes a temperature that does not cause frost formation in the cooling heat exchanger (18) (for example, a temperature higher than 0 ° C.). Thus, it is possible to suppress frost formation in the cooling heat exchanger (18).

  That is, according to the first aspect of the present invention, the cooling heat of the refrigeration cycle apparatus that includes the evaporation pressure regulating valve (19) and is configured to be able to switch between the cooling mode refrigerant circuit and the dehumidifying heating mode refrigerant circuit. It is possible to suppress frost formation on the exchanger (18).

The invention according to claim 7 is a refrigeration cycle apparatus applied to an air conditioner,
A compressor (11) that compresses and discharges the refrigerant, a heating heat exchanger (12) that heats the blown air blown into the air-conditioning target space using the refrigerant discharged from the compressor as a heat source, and a pressure reduction of the refrigerant A first pressure reducing device (15a) to be performed, an outdoor heat exchanger (16) for exchanging heat between the refrigerant flowing out of the first pressure reducing device and the outside air, a second pressure reducing device (15b) for reducing the pressure of the refrigerant, and a second pressure reducing device A cooling heat exchanger (18) for exchanging heat between the refrigerant flowing out of the apparatus and the blown air before passing through the heating heat exchanger, and an evaporation pressure adjusting valve for adjusting the refrigerant evaporation pressure (Pe) in the cooling heat exchanger (19), an opening / closing device (23) for opening and closing the refrigerant outlet side of the cooling heat exchanger, an opening / closing control unit (40d) for controlling the operation of the opening / closing device, and a refrigerant circuit switching device (21, 21) for switching the refrigerant circuit 22), and
The evaporating pressure regulating valve increases the refrigerant evaporating pressure (Pe) as the flow rate of the refrigerant flowing through the cooling heat exchanger increases.
In the cooling mode in which the cooled blast air is blown out to the air-conditioning target space, the refrigerant circuit switching device causes the refrigerant flowing out from the heating heat exchanger to flow through the first pressure reducing device → the outdoor heat exchanger → the second pressure reducing device → the cooling heat exchanger. Switch to the refrigerant circuit that flows in the order of switchgear → compressor, and in the dehumidifying heating mode in which the blown air that has been cooled and dehumidified is reheated and blown out to the air-conditioning target space, the flow of the refrigerant that has flowed out of the heat exchanger for heating is branched In addition, the one branched refrigerant flows in the order of the first pressure reducing device → the outdoor heat exchanger → the compressor, and the other branched refrigerant flows in the order of the second pressure reducing device → the heat exchanger for cooling → the opening / closing device → the compressor. Switch to the refrigerant circuit to flow,
The open / close control unit is in the dehumidifying heating mode, and when the refrigerant evaporation temperature (Te) in the cooling heat exchanger is higher than a predetermined reference evaporation temperature (KTe), When the refrigerant outlet side of the exchanger is opened and the refrigerant evaporating temperature (Te) is equal to or lower than the reference evaporating temperature (KTe) in the dehumidifying heating mode, the refrigerant of the cooling heat exchanger It is a refrigeration cycle device that controls the operation of the opening and closing device to close the outlet side.

  According to this, since the refrigerant circuit switching device (21, 22) is provided, the refrigerant circuit in the cooling mode and the refrigerant circuit in the dehumidifying heating mode can be switched.

  Further, the refrigerant flow rate (Ge) flowing through the evaporation pressure regulating valve (19) is in the dehumidifying heating mode where the refrigerant flow rate (Ge) is smaller than that in the cooling mode, and the refrigerant evaporation temperature (Te) is lower than the reference evaporation temperature (KTe). When it is, the open / close control unit (40d) controls the operation of the open / close device so as to close the refrigerant outlet side of the cooling heat exchanger (18). As a result, the refrigerant does not flow into the cooling heat exchanger (18), and the refrigerant does not evaporate in the cooling heat exchanger (18) and exerts an endothermic effect.

  Therefore, even when the refrigerant evaporation temperature (Te) is lower than the reference evaporation temperature (KTe) in the dehumidifying heating mode, it is possible to suppress the formation of frost on the cooling heat exchanger (18).

  That is, according to the seventh aspect of the present invention, the cooling heat of the refrigeration cycle apparatus including the evaporating pressure regulating valve (19) and configured to be able to switch between the cooling mode refrigerant circuit and the dehumidifying heating mode refrigerant circuit. It is possible to suppress frost formation on the exchanger (18).

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

1 is an overall configuration diagram of a vehicle air conditioner according to a first embodiment. It is an axial sectional view of the evaporation pressure regulating valve of the first embodiment. It is a block diagram which shows the electric control part of the vehicle air conditioner of 1st Embodiment. It is a flowchart which shows the control processing of the vehicle air conditioner of 1st Embodiment. It is a flowchart of the subroutine which determines an operation mode among the control processing of the vehicle air conditioner of 1st Embodiment. It is a flowchart of the subroutine performed at the time of dehumidification heating mode among the control processing of the vehicle air conditioner of 1st Embodiment. It is a chart which shows the operating state of various air-conditioning control equipment in each operation mode of a 1st embodiment. It is explanatory drawing for demonstrating the pressure regulation characteristic of the evaporation pressure regulating valve of 1st Embodiment. It is explanatory drawing for demonstrating the change of the 1st aperture_diaphragm | restriction passage area at the time of temperature fall prevention control of 2nd Embodiment, and a 2nd aperture_diaphragm | restriction passage area. It is a Mollier diagram which shows the change of the state of the refrigerant | coolant in the normal control at the time of the dehumidification heating mode of 2nd Embodiment. It is a Mollier diagram which shows the change of the state of the refrigerant | coolant at the time of the temperature fall prevention control at the time of the dehumidification heating mode of 2nd Embodiment. It is a whole block diagram of the vehicle air conditioner which concerns on 3rd Embodiment. It is a block diagram which shows the electric control part of the vehicle air conditioner of 3rd Embodiment.

(First embodiment)
1st Embodiment of this invention is described using FIGS. In the present embodiment, the refrigeration cycle apparatus 10 according to the present invention is applied to a vehicle air conditioner 1 that is mounted on an electric vehicle that obtains a driving force for traveling from a traveling electric motor. The refrigeration cycle apparatus 10 fulfills a function of cooling or heating the air blown into the vehicle interior, which is the air-conditioning target space, in the vehicle air conditioner 1. Accordingly, the heat exchange target fluid of this embodiment is blown air.

  Furthermore, the refrigeration cycle apparatus 10 is configured to be capable of switching between a heating mode refrigerant circuit, a dehumidifying heating mode refrigerant circuit, and a cooling mode refrigerant circuit. In the vehicle air conditioner 1, the heating mode is an operation mode in which the blown air is heated and blown out into the passenger compartment. The dehumidifying and heating mode is an operation mode in which the blown air that has been cooled and dehumidified is reheated and blown out into the passenger compartment. The cooling mode is an operation mode in which the blown air is cooled and blown out into the passenger compartment.

  In FIG. 1, the refrigerant flow in the refrigerant circuit in the heating mode is indicated by black arrows, the refrigerant flow in the refrigerant circuit in the dehumidifying and heating mode is indicated by hatched arrows, and the refrigerant flow in the refrigerant circuit in the cooling mode is further indicated. The flow is indicated by white arrows.

  Further, in this refrigeration cycle apparatus 10, an HFC-based refrigerant (specifically, R134a) is adopted as the refrigerant, and a vapor compression subcritical refrigeration cycle in which the high-pressure side refrigerant pressure Pd does not exceed the critical pressure of the refrigerant. It is composed. Of course, an HFO refrigerant (for example, R1234yf) or the like may be adopted as the refrigerant. Furthermore, refrigeration oil for lubricating the compressor 11 is mixed in the refrigerant, and a part of the refrigeration oil circulates in the cycle together with the refrigerant.

  Among the components of the refrigeration cycle apparatus 10, the compressor 11 sucks refrigerant in the refrigeration cycle apparatus 10, compresses it, and discharges it. The compressor 11 is arrange | positioned in the vehicle bonnet. The compressor 11 is configured as an electric compressor that drives a fixed capacity type compression mechanism with a fixed discharge capacity by an electric motor. As this compression mechanism, various compression mechanisms such as a scroll-type compression mechanism and a vane-type compression mechanism can be employed.

  The operation (rotation speed) of the electric motor is controlled by a control signal output from the air conditioning control device 40 described later, and either an AC motor or a DC motor may be adopted. And the refrigerant | coolant discharge capability of a compression mechanism is changed because the air-conditioning control apparatus 40 controls the rotation speed of an electric motor. Accordingly, in the present embodiment, the electric motor constitutes the discharge capacity changing unit of the compression mechanism.

  The refrigerant inlet side of the indoor condenser 12 is connected to the discharge port of the compressor 11. The indoor condenser 12 heats the blown air by exchanging heat between the high-temperature and high-pressure discharged refrigerant discharged from the compressor 11 and the blown air that has passed through the indoor evaporator 18 described later in the heating mode and the dehumidifying heating mode. It is a heat exchanger for heating. The indoor condenser 12 is arrange | positioned in the casing 31 of the indoor air conditioning unit 30 mentioned later.

  One refrigerant inlet of the first three-way joint 13a is connected to the refrigerant outlet of the indoor condenser 12. Such a three-way joint may be formed by joining a plurality of pipes, or may be formed by providing a plurality of refrigerant passages in a metal block or a resin block. Further, the refrigeration cycle apparatus 10 includes second to fourth three-way joints 13b to 13d as described later. The basic configuration of the second to fourth three-way joints 13b to 13d is the same as that of the first three-way joint 13a.

  These three-way joints function as branch portions or junction portions. For example, in the first three-way joint 13a in the dehumidifying and heating mode, one of the three inlets and outlets is used as an inlet and the remaining two are used as outlets. Therefore, the first three-way joint 13a in the dehumidifying and heating mode functions as a branching portion that branches the flow of the refrigerant flowing in from one inflow port and outflows from the two outflow ports.

  Further, for example, in the fourth three-way joint 13d in the dehumidifying and heating mode, two of the three inflow / outflow ports are used as the inflow port, and the remaining one is used as the outflow port. Accordingly, the fourth three-way joint 13d in the dehumidifying and heating mode functions as a joining portion that joins the refrigerant that has flowed in from the two inlets and flows out from the one outlet.

  A first refrigerant passage 14a that guides the refrigerant flowing out of the indoor condenser 12 to the refrigerant inlet side of the outdoor heat exchanger 16 is connected to another inflow / outlet of the first three-way joint 13a. Further, at yet another inflow / outlet of the first three-way joint 13a, the refrigerant that has flowed out of the indoor condenser 12 is introduced to the inlet side (specifically, the second expansion valve 15b disposed in the third refrigerant passage 14c described later). The second refrigerant passage 14b leading to one inflow / outlet of the third three-way joint 13c is connected.

  A first expansion valve 15a is disposed in the first refrigerant passage 14a. The first expansion valve 15a is a first decompression device that decompresses the refrigerant flowing out of the indoor condenser 12 during the heating mode and the dehumidifying heating mode. The first expansion valve 15a is a variable throttle mechanism having a valve body configured to be able to change the throttle opening degree and an electric actuator composed of a stepping motor that changes the throttle opening degree of the valve body.

  Furthermore, the first expansion valve 15a is configured as a variable throttle mechanism with a fully-open function that functions as a simple refrigerant passage with almost no refrigerant decompression effect by fully opening the throttle opening. The operation of the first expansion valve 15a is controlled by a control signal (control pulse) output from the air conditioning controller 40.

  The refrigerant inlet side of the outdoor heat exchanger 16 is connected to the outlet side of the first expansion valve 15a. The outdoor heat exchanger 16 exchanges heat between the refrigerant that has flowed out of the first expansion valve 15a and the outside air (outside air) blown from a blower fan (not shown). The outdoor heat exchanger 16 is disposed on the vehicle front side in the vehicle bonnet. The blower fan is an electric blower whose number of rotations (blowing capacity) is controlled by a control voltage output from the air conditioning control device 40.

  One inlet / outlet of the second three-way joint 13b is connected to the refrigerant outlet side of the outdoor heat exchanger 16. A third refrigerant passage 14c that guides the refrigerant flowing out of the outdoor heat exchanger 16 to the refrigerant inlet side of the indoor evaporator 18 is connected to another inflow / outlet of the second three-way joint 13b. In addition, at another inflow / outflow port of the second three-way joint 13b, the refrigerant flowing out of the outdoor heat exchanger 16 is supplied to the inlet side of an accumulator 20 (specifically, one inflow / outlet port of the fourth three-way joint 13d). ) Is connected to the fourth refrigerant passage 14d.

  In the third refrigerant passage 14c, a check valve 17, a third three-way joint 13c, and a second expansion valve 15b are arranged in this order with respect to the refrigerant flow. The check valve 17 only allows the refrigerant to flow from the second three-way joint 13b side to the indoor evaporator 18 side. The second refrigerant passage 14b described above is connected to the third three-way joint 13c.

  The second expansion valve 15 b is a second decompression device that decompresses the refrigerant that flows out of the outdoor heat exchanger 16 and flows into the indoor evaporator 18. The basic configuration of the second expansion valve 15b is the same as that of the first expansion valve 15a. Furthermore, the second expansion valve 15b of the present embodiment is configured by a variable throttle mechanism with a fully-closed function that closes the refrigerant passage when the throttle opening is fully closed.

  Therefore, in the refrigeration cycle apparatus 10 of the present embodiment, the refrigerant circuit can be switched by closing the third refrigerant passage 14c with the second expansion valve 15b fully closed. In other words, the second expansion valve 15b functions as a refrigerant decompression device and also has a function as a refrigerant circuit switching device that switches a refrigerant circuit of the refrigerant circulating in the cycle.

  The indoor evaporator 18 is a cooling heat exchanger that exchanges heat between the refrigerant flowing out of the second expansion valve 15b and the blown air before passing through the indoor condenser 12 in the cooling mode and the dehumidifying heating mode. In the indoor evaporator 18, the blown air is cooled by evaporating the refrigerant decompressed by the second expansion valve 15 b and exerting an endothermic action. The indoor evaporator 18 is arranged in the casing 31 of the indoor air conditioning unit 30 on the upstream side of the air flow of the indoor condenser 12.

  The refrigerant outlet of the indoor evaporator 18 is connected to the inlet 91 a side of the evaporation pressure adjusting valve 19. The evaporation pressure adjusting valve 19 functions to adjust the refrigerant evaporation pressure Pe in the indoor evaporator 18 to be equal to or higher than the frost suppression pressure APe in order to suppress frost formation (frost) of the indoor evaporator 18. In other words, the evaporation pressure adjusting valve 19 functions to adjust the refrigerant evaporation temperature Te in the indoor evaporator 18 to be equal to or higher than the frosting suppression temperature ATe.

  In the present embodiment, R134a is adopted as the refrigerant, and the frost suppression temperature ATe is set to a value slightly higher than 0 ° C. Therefore, the frosting suppression pressure APe is set to a value slightly higher than 0.293 MPa which is the saturation pressure of R134a at 0 ° C.

  The detailed configuration of the evaporation pressure adjusting valve 19 will be described with reference to FIG. The evaporation pressure adjusting valve 19 is composed of a mechanical mechanism having a body 91, a cylindrical valve body 92, a bellows 93, a spring 94, and the like.

  The body 91 is formed in a cylindrical shape by combining a plurality of metal or resin members. The body 91 forms an outer shell of the evaporation pressure adjusting valve 19. Inside the body 91, a coolant passage is formed in which the tubular valve body 92, the bellows 93, the spring 94, and the like are accommodated.

  An inflow port 91 a connected to the refrigerant outlet side of the indoor evaporator 18 is formed on one end side in the axial direction of the body 91 formed in a cylindrical shape. On the other end side in the axial direction of the body 91, an outlet 91b connected to the inlet side of the accumulator 20 described later is formed. Further, a cylinder portion 91 c is formed on the downstream side of the refrigerant flow of the inlet 91 a of the body 91.

  The cylinder part 91c is a part that forms a cylindrical space inside. A cylindrical portion 92a of the cylindrical valve body portion 92 is fitted in the columnar space formed in the cylinder portion 91c so as to be slidable in the axial direction. That is, the outer diameter dimension of the cylindrical part 92a of the cylindrical valve body part 92 and the inner diameter dimension of the cylinder part 91c have a dimensional relationship of gap clearance.

  The cylindrical valve body 92 is formed of a bottomed cylindrical (that is, cup-shaped) metal member. On the bottom surface arranged on the other axial end side (that is, the outflow port 91b side) of the tubular valve body portion 92, a flange portion 92b extending vertically in the axial direction is provided. The flange portion 92b is a part that abuts on the end of the cylinder portion 91c on the downstream side of the refrigerant flow and regulates the displacement of the cylindrical valve body portion 92.

  Furthermore, a plurality of communication holes 92c are formed on the side surface of the cylindrical portion 92a of the cylindrical valve body portion 92 to communicate the inner peripheral side and the outer peripheral side. These communication holes 92c are blocked by the inner peripheral wall surface of the cylinder when the cylindrical valve body 92 is displaced toward one end in the axial direction and the flange 92b is in contact with the downstream end of the cylinder 91c. Yes. Therefore, in the state where the flange portion 92b is in contact with the downstream end portion of the cylinder portion 91c, the communication between the inflow port 91a and the outflow port 91b is blocked.

  Further, when the tubular valve body portion 92 is displaced from the state where the flange portion 92b is in contact with the downstream end portion of the cylinder portion 91c to the other end side in the axial direction, it is formed in the cylindrical portion 92a of the tubular valve body portion 92. The communicated hole 92c is exposed from the cylinder portion 91c. Thereby, the inflow port 91a and the outflow port 91b are connected. And the area of the site | part exposed from the cylinder part 91c of the communicating hole 92c increases as the displacement amount L to the axial direction other end side of the cylindrical valve body part 92 increases.

  That is, the cylinder part 91c and the cylindrical valve body part 92 of the present embodiment constitute a so-called slide valve. Then, the area of the refrigerant passage in the evaporation pressure regulating valve 19 is changed by displacing the cylindrical valve body portion 92 in the axial direction. Furthermore, in this embodiment, when viewed from a direction perpendicular to the axial direction of the body 91, each communication hole 92c is formed in a substantially rectangular shape. Therefore, the refrigerant passage area in the evaporation pressure adjusting valve 19 increases in proportion to the increase in the displacement L.

  The bellows 93 is a metal hollow cylindrical member formed to be extendable and contractible in the displacement direction of the cylindrical valve body portion 92. The bellows 93 applies a load to the cylindrical valve body 92 on the side that reduces the refrigerant passage area in the evaporation pressure adjusting valve 19 (that is, the inlet 91a side). The bellows 93 is disposed on the downstream side of the refrigerant flow of the cylindrical valve body portion 92. And the axial direction one end side of the bellows 93 is connected with the collar part 92b side of the cylindrical valve body part 92. As shown in FIG. On the other hand, the other axial end side of the bellows 93 is fixed to the body 91 via an interposed member.

  The spring 94 is disposed in the internal space of the bellows 93. The spring 94 is a coil spring that expands and contracts in the displacement direction of the tubular valve body 92. Similar to the bellows 93, the spring 94 applies a load to the cylindrical valve body 92 on the side where the refrigerant passage area in the evaporation pressure adjusting valve 19 is reduced. The load that the bellows 93 and the spring 94 act on the tubular valve body 92 can be adjusted by the adjusting screw 94a.

  Therefore, the cylindrical valve body 92 of the present embodiment is configured such that the load due to the refrigerant pressure on the inlet 91a side (that is, the refrigerant evaporation pressure in the indoor evaporator 18), the refrigerant pressure on the outlet 91b side (that is, the compressor 11). Load due to suction side refrigerant pressure, refrigerant pressure in accumulator 20), and further load due to bellows 93 and spring 94.

  Then, when the cylindrical valve body 92 is displaced to a position where these loads are balanced, the refrigerant passage area in the evaporation pressure adjusting valve 19 (that is, the opening area of the communication hole 92c) is adjusted.

More specifically, the balance of the load received by the tubular valve body portion 92 can be expressed by the following formula F1.
P1 * A1 + P2 * A2 = K * L + P2 * A1 + F0 (F1)
Here, P1 is the refrigerant pressure on the inlet 91a side, P2 is the refrigerant pressure on the outlet 91b side, A1 is the pressure receiving area of the tubular valve body 92, A2 is the pressure receiving area of the bellows 93, K is the bellows 93 and The total spring constant of the spring 94, L is the amount of displacement of the tubular valve body 92, and F0 is the initial load of the bellows 93 and spring 94 adjusted by the adjusting screw 94a.

Furthermore, in the evaporating pressure regulating valve 19 of the present embodiment, A1≈A2 is set, so that Formula F1 can be modified as Formula F2 below.
P1 = K / A1 × L + F0 / A1 (F2)
According to this mathematical formula F2, it can be seen that the refrigerant pressure P1 on the inlet 91a side increases as the displacement amount L increases. As described above, as the displacement L increases, the refrigerant passage area in the evaporation pressure adjusting valve 19 increases and the flow rate of the refrigerant flowing through the evaporation pressure adjusting valve 19 also increases.

  Therefore, the evaporating pressure adjusting valve 19 increases the refrigerant pressure P1 (that is, the indoor pressure) on the inlet 91a side as the refrigerant flow rate that flows through the evaporating pressure adjusting valve 19 (that is, the refrigerant flow rate that flows through the indoor evaporator 18) increases. It has a pressure regulation characteristic that increases the refrigerant evaporation pressure Pe) in the evaporator 18. Further, in the present embodiment, the pressure regulation characteristic of the evaporation pressure adjusting valve 19 is set so that the refrigerant evaporation pressure Pe in the indoor evaporator 18 becomes equal to or higher than the frosting suppression pressure APe in the cooling mode.

  As shown in FIG. 1, a fourth three-way joint 13 d is connected to the outlet side of the evaporation pressure adjusting valve 19. The fourth refrigerant passage 14d described above is connected to the fourth three-way joint 13d. The inlet side of the accumulator 20 is connected to still another inlet / outlet of the fourth three-way joint 13d.

  The accumulator 20 is a gas-liquid separator that separates the gas-liquid of the refrigerant that has flowed into the accumulator and stores excess refrigerant in the cycle. The suction port side of the compressor 11 is connected to the gas-phase refrigerant outlet of the accumulator 20. Therefore, the accumulator 20 functions to prevent liquid phase refrigerant from being sucked into the compressor 11 and prevent liquid compression in the compressor 11.

  A first on-off valve 21 is disposed in the fourth refrigerant passage 14d that connects the second three-way joint 13b and the fourth three-way joint 13d. The first on-off valve 21 is an electromagnetic valve as a refrigerant circuit switching device that switches a refrigerant circuit by opening and closing the fourth refrigerant passage 14d. The operation of the first on-off valve 21 is controlled by a control signal output from the air conditioning control device 40.

  Similarly, the 2nd on-off valve 22 is arrange | positioned in the 2nd refrigerant path 14b which connects the 1st three-way coupling 13a and the 3rd three-way coupling 13c. The second on-off valve 22 is an electromagnetic valve as a refrigerant circuit switching device that switches the refrigerant circuit by opening and closing the second refrigerant passage 14b. The basic configuration of the second on-off valve 22 is the same as that of the first on-off valve 21.

  Next, the indoor air conditioning unit 30 shown in FIG. 1 will be described. The indoor air conditioning unit 30 is for blowing out the blown air whose temperature has been adjusted by the refrigeration cycle apparatus 10 into the vehicle interior. The indoor air conditioning unit 30 is disposed inside the instrument panel (instrument panel) at the forefront of the vehicle interior. The indoor air conditioning unit 30 is configured by housing a blower 32, the indoor evaporator 18, the indoor condenser 12 and the like in a casing 31 that forms an outer shell thereof.

  The casing 31 forms an air passage for blown air blown into the vehicle interior. The casing 31 is formed of a resin (for example, polypropylene) having a certain degree of elasticity and excellent in strength. Inside / outside air switching device 33 as an inside / outside air switching unit for switching and introducing inside air (vehicle compartment air) and outside air (vehicle compartment outside air) into casing 31 is arranged on the most upstream side of the blown air flow in casing 31. Yes.

  The inside / outside air switching device 33 continuously adjusts the opening area of the inside air introduction port through which the inside air is introduced into the casing 31 and the outside air introduction port through which the outside air is introduced by the inside / outside air switching door, so that the air volume of the inside air and the air volume of the outside air are adjusted. The air volume ratio is continuously changed. The inside / outside air switching door is driven by an electric actuator for the inside / outside air switching door. The operation of the electric actuator is controlled by a control signal output from the air conditioning controller 40.

  A blower 32 that blows the air sucked through the inside / outside air switching device 33 toward the vehicle interior is disposed on the downstream side of the blowing air flow of the inside / outside air switching device 33. The blower 32 is an electric blower that drives a centrifugal multiblade fan (sirocco fan) with an electric motor, and the number of rotations (air flow rate) is controlled by a control voltage output from the air conditioning control device 40.

  On the downstream side of the blower air flow of the blower 32, the indoor evaporator 18 and the indoor condenser 12 are arranged in this order with respect to the blown air flow. In other words, the indoor evaporator 18 is disposed on the upstream side of the blown air flow with respect to the indoor condenser 12. Further, in the casing 31, a cold air bypass passage 35 is formed in which the blown air that has passed through the indoor evaporator 18 bypasses the indoor condenser 12 and flows downstream.

  On the downstream side of the blower air flow of the indoor evaporator 18 and on the upstream side of the blower air flow of the indoor condenser 12, the air volume ratio of the blown air that has passed through the indoor evaporator 18 is allowed to pass through the indoor condenser 12. An air mix door 34 to be adjusted is disposed.

  In addition, the blast air heated by the indoor condenser 12 and the blast air not heated by the indoor condenser 12 through the cold air bypass passage 35 are mixed on the downstream side of the blast air flow of the indoor condenser 12. A mixing space is provided. Further, a plurality of opening holes for blowing the blown air (air conditioned air) mixed in the mixing space into the vehicle interior, which is the air conditioned space, are arranged in the most downstream portion of the blown air flow of the casing 31.

  Specifically, a face opening hole, a foot opening hole, and a defroster opening hole (all not shown) are provided as these opening holes. The face opening hole is an opening hole for blowing conditioned air toward the upper body of the passenger in the vehicle interior. The foot opening hole is an opening hole for blowing conditioned air toward the feet of the passenger. The defroster opening hole is an opening hole for blowing out conditioned air toward the inner side surface of the vehicle front window glass.

  Further, the air flow downstream of the face opening hole, the foot opening hole and the defroster opening hole is respectively connected to the face air outlet, the foot air outlet and the defroster air outlet ( Neither is shown).

  Therefore, the air mix door 34 adjusts the air volume ratio between the air volume that passes through the indoor condenser 12 and the air volume that passes through the cold air bypass passage 35, thereby adjusting the temperature of the conditioned air mixed in the mixing space. The temperature of the conditioned air blown from each outlet into the passenger compartment is adjusted.

  That is, the air mix door 34 functions as a temperature adjustment unit that adjusts the temperature of the conditioned air blown into the vehicle interior. The air mix door 34 is driven by an electric actuator for driving the air mix door. The operation of the electric actuator is controlled by a control signal output from the air conditioning controller 40.

  Further, on the upstream side of the air flow of the face opening hole, foot opening hole, and defroster opening hole, a face door for adjusting the opening area of the face opening hole, a foot door for adjusting the opening area of the foot opening hole, and a defroster opening, respectively. A defroster door (both not shown) for adjusting the opening area of the hole is disposed.

  These face doors, foot doors, and defroster doors constitute an outlet mode switching door that switches the outlet mode. The face door, the foot door, and the defroster door are connected to an electric actuator for driving the air outlet mode door via a link mechanism or the like, and are rotated in conjunction with each other. The operation of this electric actuator is also controlled by a control signal output from the air conditioning controller 40.

  Specific examples of the outlet mode switched by the outlet mode switching door include a face mode, a bi-level mode, and a foot mode.

  The face mode is an air outlet mode in which the face air outlet is fully opened and air is blown from the face air outlet toward the upper body of the passenger in the passenger compartment. The bi-level mode is an air outlet mode in which both the face air outlet and the foot air outlet are opened and air is blown toward the upper body and the feet of the passengers in the passenger compartment. The foot mode is an air outlet mode in which the foot air outlet is fully opened and blown air is blown from the foot air outlet toward the feet of the passengers in the passenger compartment.

  Further, the occupant can manually operate the blow mode switching switch provided on the operation panel 60 to fully open the defroster blowout port, thereby setting the defroster mode in which air is blown from the defroster blowout port to the vehicle front window glass inner surface. .

  Next, the electric control unit of the present embodiment will be described with reference to FIG. The air conditioning control device 40 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. The compressor 11, the first expansion valve 15a, the second expansion valve 15b, the first on-off valve 21, connected to the output side, perform various calculations and processes based on the control program stored in the ROM. The operation of air conditioning control devices such as the second on-off valve 22 and the blower 32 is controlled.

  Further, on the input side of the air-conditioning control device 40, an inside air temperature sensor 51, an outside air temperature sensor 52, a solar radiation sensor 53, a discharge temperature sensor 54, a high pressure side pressure sensor 55, an evaporator temperature sensor 56, a low pressure side pressure sensor 57, an air blower. A detection signal of a sensor group for air conditioning control such as the air temperature sensor 58 is input.

  The inside air temperature sensor 51 is an inside air temperature detecting unit that detects a vehicle interior temperature (inside air temperature) Tr. The outside air temperature sensor 52 is an outside air temperature detecting unit that detects a vehicle compartment outside temperature (outside air temperature) Tam. The solar radiation sensor 53 is a solar radiation amount detection unit that detects the solar radiation amount As irradiated into the vehicle interior. The discharge temperature sensor 54 is a discharge temperature detection unit that detects the discharge refrigerant temperature Td of the refrigerant discharged from the compressor 11.

  The high pressure side pressure sensor 55 is a high pressure side pressure detector that detects the outlet side refrigerant pressure (high pressure side refrigerant pressure) Pd of the indoor condenser 12. The high pressure side refrigerant pressure Pd is a refrigerant pressure in a range from the discharge port side of the compressor 11 to the inlet side of the first expansion valve 15a in the heating mode. In the dehumidifying heating mode, the refrigerant pressure is in a range from the discharge port side of the compressor 11 to the inlet side of the first expansion valve 15a and the inlet side of the second expansion valve 15b. In the cooling mode, the refrigerant pressure is in a range from the discharge port side of the compressor 11 to the inlet side of the second expansion valve 15b.

  The evaporator temperature sensor 56 is an evaporator temperature detector that detects a refrigerant evaporation temperature (evaporator temperature) Te in the indoor evaporator 18. The evaporator temperature sensor 56 of this embodiment detects the heat exchange fin temperature of the indoor evaporator 18, but the temperature detector 56 detects the temperature of other parts of the indoor evaporator 18 as the evaporator temperature sensor 56. May be adopted. Further, a temperature detection unit that directly detects the temperature of the refrigerant itself flowing through the indoor evaporator 18 may be employed.

  The low pressure side pressure sensor 57 is a low pressure side pressure detector that detects the outlet side refrigerant pressure (low pressure side refrigerant pressure) Pe of the indoor evaporator 18. The low-pressure side refrigerant pressure Pe is a value corresponding to the refrigerant evaporation pressure in the indoor evaporator 18 in the cooling mode and the dehumidifying heating mode. The blown air temperature sensor 58 is a blown air temperature detection unit that detects the blown air temperature TAV blown from the mixing space into the vehicle interior.

  Furthermore, operation signals from various air conditioning operation switches provided on the operation panel 60 disposed near the instrument panel in the front part of the vehicle interior are input to the input side of the air conditioning control device 40. Specifically, various air conditioning operation switches provided on the operation panel 60 are provided with an auto switch, a cooling switch (A / C switch), an air volume setting switch, a temperature setting switch, a blowing mode switching switch, and the like.

  The auto switch is an input unit for setting or canceling the automatic control operation of the vehicle air conditioner 1. The cooling switch is an input unit for requesting cooling of the passenger compartment. The air volume setting switch is an input unit for manually setting the air volume of the blower 32. The temperature setting switch is an input unit for setting a vehicle interior set temperature Tset, which is a target temperature in the vehicle interior. The blowing mode changeover switch is an input unit for manually setting the blowing mode.

  The air-conditioning control device 40 is configured integrally with a control unit (in other words, a control device) that controls various air-conditioning control devices connected to the output side thereof. The structure (hardware and software) to control comprises the control part which controls the action | operation of each air-conditioning control apparatus.

  For example, in this embodiment, the structure which controls the action | operation of the compressor 11 among the air-conditioning control apparatuses 40 comprises the discharge capability control part 40a. A configuration for controlling the operation of the first on-off valve 21 and the second on-off valve 22 that are refrigerant circuit switching devices constitutes the refrigerant circuit control unit 40b. The configuration for controlling the operation of the first expansion valve 15a, which is the first pressure reducing device, and the second expansion valve 15b, which is the second pressure reducing device, constitutes the pressure reducing device control unit 40c.

  Of course, the discharge capacity control unit 40a, the refrigerant circuit control unit 40b, the decompression device control unit 40c, and the like may be configured as separate control units with respect to the air conditioning control device 40.

  Next, operation | movement of the vehicle air conditioner 1 of this embodiment is demonstrated using FIGS. In the vehicle air conditioner 1 of the present embodiment, the operation in the heating mode, the dehumidifying heating mode, and the cooling mode can be switched as described above. The switching between these operation modes is performed by executing an air conditioning control program stored in the air conditioning control device 40 in advance.

  FIG. 4 is a flowchart showing a control process as a main routine of the air conditioning control program. The control process of the main routine is executed when the auto switch of the operation panel 60 is turned on (ON). In addition, each control step of the flowchart shown to FIGS. 4-6 comprises the various function implementation | achievement part which the air-conditioning control apparatus 40 has.

  First, in step S1 of FIG. 4, initialization such as initialization of flags and timers configured by the storage circuit of the air conditioning control device 40 and initial positioning of the stepping motors constituting the various electric actuators described above is performed. It should be noted that in the initialization in step S1, some of the flags and the calculated values are read out from the values stored at the previous stop of the vehicle air conditioner or the end of the vehicle system.

  Next, in step S2, detection signals of the air conditioning control sensor groups 51 to 58, operation signals of the operation panel 60, and the like are read. In subsequent step S3, based on the detection signal and operation signal read in step S2, a target blowing temperature TAO that is a target temperature of the blown air blown into the vehicle interior is calculated.

Specifically, the target blowing temperature TAO is calculated by the following formula F3.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × As + C (F3)
Here, Tset is the vehicle interior set temperature set by the temperature setting switch, Tr is the vehicle interior temperature (internal air temperature) detected by the internal air temperature sensor 51, Tam is the external air temperature detected by the external air temperature sensor 52, and As is solar radiation. The amount of solar radiation detected by the sensor 53. Kset, Kr, Kam, Ks are control gains, and C is a correction constant.

  Next, in step S4, the operation mode is determined. More specifically, in step S4, a subroutine shown in FIG. 5 is executed. First, in step S41, it is determined whether or not the cooling switch of the operation panel 60 is turned on. When it is determined in step S41 that the cooling switch is turned on (turned on), the process proceeds to step S42.

  On the other hand, when it is determined in step S41 that the cooling switch is not turned on (turned off), the process proceeds to step S45, the operation mode is determined as the heating mode, and the process proceeds to step S5.

  In step S42, it is determined whether or not a value (TAO-Tam) obtained by subtracting the outside air temperature Tam from the target blowing temperature TAO is lower than a predetermined reference cooling temperature α (α = 0 in the present embodiment). .

  If (TAO−Tam) <α in step S42, the process proceeds to step S43, the operation mode is determined to be the cooling mode, and the process returns to step S5. On the other hand, if (TAO−Tam) <α is not satisfied in step S42, the process proceeds to step S44, the operation mode is determined to be the dehumidifying heating mode, and the process returns to step S5.

  In step S5 of FIG. 4, the operating states of various control target devices are determined according to the operation mode determined in step S4. More specifically, in step S5, as shown in the chart of FIG. 7, the opening and closing states of the first and second on-off valves 21 and 22, the opening of the air mix door 34, the first and second expansion valves 15a, The operating state of 15b and the like are determined.

  Further, in step S5, although not shown in the chart of FIG. 7, the refrigerant discharge capacity of the compressor 11 (that is, the rotation speed of the compressor 11), the blowing capacity of the blower 32 (that is, the rotation speed of the blower 32), The operating state of the inside / outside air switching device 33, the operating state of the air outlet mode switching door (that is, the air outlet mode), and the like are also determined.

  In step S6, control signals or control voltages are output from the air conditioning control device 40 to the various air conditioning control devices so that the operating states of the various air conditioning control devices determined in step S5 are obtained. In the subsequent step S7, the process waits for the control period τ, and returns to step S2 when it is determined that the control period τ has elapsed.

  In the vehicle air conditioner 1 of the present embodiment, the operation mode is determined as described above, and the operation in each operation mode is executed. The operation in each operation mode will be described below.

(A) Heating mode In the heating mode, as shown in the chart of FIG. 7, the air conditioning control device 40 opens the first on-off valve 21, closes the second on-off valve 22, and exerts a pressure reducing action on the first expansion valve 15a. The second expansion valve 15b is fully closed.

  Thereby, in the heating mode, as indicated by the black arrow in FIG. 1, the compressor 11 → the indoor condenser 12 → the first expansion valve 15 a → the outdoor heat exchanger 16 → (the first on-off valve 21 →) the accumulator 20 → A vapor compression refrigeration cycle in which refrigerant is circulated in the order of the compressor 11 is configured.

  Further, with the configuration of this refrigerant circuit, as described in step S5 above, the air conditioning control device 40 determines the operating states of the various air conditioning control devices in the heating mode (control signals output to the various air conditioning control devices). To do.

  For example, the control signal output to the electric motor of the compressor 11 is determined as follows. First, the target condensing pressure PCO in the indoor condenser 12 is determined based on the target blowing temperature TAO with reference to a control map stored in the air conditioning control device 40 in advance. In this control map, the target condensing pressure PCO is determined to increase as the target blowing temperature TAO increases.

  Then, based on the deviation between the target condensation pressure PCO and the high-pressure side refrigerant pressure Pd detected by the high-pressure side pressure sensor 55, compression is performed so that the high-pressure side refrigerant pressure Pd approaches the target condensation pressure PCO using a feedback control method. A control signal output to the electric motor of the machine 11 is determined.

  Regarding the control signal output to the electric actuator for driving the air mix door, the air mix door 34 fully closes the cold air bypass passage 35, and the total flow rate of the blown air after passing through the indoor evaporator 18 is the indoor condenser 12. To pass through the side air passage.

  The control signal output to the first expansion valve 15a is determined so that the degree of supercooling of the refrigerant flowing into the first expansion valve 15a approaches the target degree of supercooling. The target degree of supercooling is a value determined so that the coefficient of performance (COP) of the cycle becomes a maximum value.

  The control voltage output to the electric motor of the blower 32 is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target blowing temperature TAO. In this control map, the air flow rate is set to the maximum air flow rate in the extremely low temperature range (maximum cooling range) and the extremely high temperature range (maximum heating range) of the target blowing temperature TAO.

  Further, as the target blowing temperature TAO increases from the extremely low temperature range toward the intermediate temperature range, the air flow rate is decreased, and as the target blowing temperature TAO decreases from the extremely high temperature range toward the intermediate temperature range, Reduce air flow. Then, when the target blowing temperature TAO is in the intermediate temperature range, the blowing amount is set as the minimum blowing amount.

  The control signal output to the electric actuator for the inside / outside air switching door is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target outlet temperature TAO. In this control map, the outside air mode for introducing outside air is basically determined. And when the target blowing temperature TAO becomes an extremely high temperature region and it is desired to obtain high heating performance, the inside air mode for introducing the inside air is determined.

  The control signal output to the electric actuator for driving the outlet mode door is determined with reference to a control map stored in advance in the air conditioning control device 40 based on the target outlet temperature TAO. In this control map, as the target outlet temperature TAO decreases from the high temperature region to the low temperature region, the outlet mode is switched in the order of foot mode → bilevel mode → face mode.

  Therefore, in the refrigeration cycle apparatus 10 in the heating mode, the high-pressure refrigerant discharged from the compressor 11 flows into the indoor condenser 12. Since the air mix door 34 opens the air passage on the indoor condenser 12 side, the refrigerant flowing into the indoor condenser 12 exchanges heat with the blown air that has been blown from the blower 32 and passed through the indoor evaporator 18 to dissipate heat. To do. Thereby, blowing air is heated.

  Since the second on-off valve 22 is closed, the refrigerant flowing out of the indoor condenser 12 flows out from the first three-way joint 13a toward the first refrigerant passage 14a and is decompressed until it becomes a low-pressure refrigerant at the first expansion valve 15a. Is done. The low-pressure refrigerant decompressed by the first expansion valve 15a flows into the outdoor heat exchanger 16 and absorbs heat from the outside air blown from the blower fan.

  The refrigerant flowing out of the outdoor heat exchanger 16 flows out from the second three-way joint 13b to the fourth refrigerant passage 14d side because the first on-off valve 21 is opened and the second expansion valve 15b is fully closed. It flows into the accumulator 20 through the fourth three-way joint 13d and is separated into gas and liquid. The gas-phase refrigerant separated by the accumulator 20 is sucked from the suction side of the compressor 11 and compressed again by the compressor 11.

  As described above, in the heating mode, the vehicle interior can be heated by blowing the blown air heated by the indoor condenser 12 into the vehicle interior.

(B) Dehumidification heating mode In the dehumidification heating mode, as shown in the chart of FIG. 7, the air conditioning control device 40 opens the first on-off valve 21, opens the second on-off valve 22, and restricts the first expansion valve 15a. And the second expansion valve 15b is in the throttle state.

  Thus, in the dehumidifying heating mode, as indicated by the hatched arrows in FIG. 1, the compressor 11, the indoor condenser 12, the first expansion valve 15a, the outdoor heat exchanger 16, and the first opening / closing valve 21. While circulating the refrigerant in the order of accumulator 20 → compressor 11, compressor 11 → indoor condenser 12 → (second on-off valve 22 →) second expansion valve 15 b → indoor evaporator 18 → evaporating pressure adjusting valve 19 → accumulator 20 → A vapor compression type refrigeration cycle in which the refrigerant is circulated in the order of the compressor 11 is configured.

  That is, in the dehumidifying and heating mode, the flow of the refrigerant flowing out from the indoor condenser 12 is branched at the first three-way joint 13a, and one of the branched refrigerants is changed from the first expansion valve 15a to the outdoor heat exchanger 16 to the compressor 11. And the other branched refrigerant is switched to a refrigerant circuit that flows in the order of the second expansion valve 15b → the indoor evaporator 18 → the evaporation pressure regulating valve 19 → the compressor 11.

  Further, with the configuration of the refrigerant circuit, as described in step S5 above, the air conditioning control device 40 determines the operating state of various air conditioning control devices in the dehumidifying heating mode.

  For example, the control signal output to the electric motor of the compressor 11 is determined similarly to the heating mode. As for the control signal output to the electric actuator for driving the air mix door, the air mix door 34 fully closes the cold air bypass passage 35 and the total flow rate of the blown air after passing through the indoor evaporator 18 is the same as in the heating mode. It is determined so as to pass through the air passage on the indoor condenser 12 side.

  Further, the control signals output to the first expansion valve 15a and the second expansion valve 15b are determined so as to suppress frost formation in the indoor evaporator 18.

  More specifically, the control signal output to the first expansion valve 15a and the second expansion valve 15b is obtained by executing the subroutine shown in FIG. The refrigerant flow rate (Ge) (mass flow rate) flowing through the vessel 18 is determined to be larger than a predetermined reference flow rate KGe.

  Here, in the evaporation pressure adjusting valve 19 of the present embodiment, when the refrigerant flow rate Ge is the reference flow rate KGe, the refrigerant evaporation pressure in the indoor evaporator 18 is adjusted to be the reference evaporation pressure KPe. Further, the refrigerant evaporation temperature (hereinafter referred to as the reference evaporation temperature KTe) in the indoor evaporator 18 at the reference evaporation pressure KPe is a temperature that does not cause frost formation in the indoor evaporator 18 (in this embodiment, 1 ° C.). ) Is set.

  First, in step S61 of FIG. 6, it is determined whether or not the refrigerant evaporation temperature Te detected by the evaporator temperature sensor 56 is higher than a predetermined reference evaporation temperature KTe. If it is determined in step S61 that the refrigerant evaporation temperature Te is higher than the reference evaporation temperature KTe, the process proceeds to step S62, and normal control is executed.

  When the refrigerant evaporation temperature Te is higher than the reference evaporation temperature KTe, there is no possibility that frost formation will occur in the indoor evaporator 18. Therefore, in the normal control in step S62, as for the control signal output to the first expansion valve 15a, the supercooling degree of the refrigerant flowing into the first expansion valve 15a approaches the target supercooling degree, as in the heating mode. To be determined.

  The control signal output to the second expansion valve 15b is determined so that the flow rate of the refrigerant flowing through the indoor evaporator 18 becomes an appropriate flow rate. Specifically, the throttle opening degree of the second expansion valve 15b is adjusted so that the superheat degree of the refrigerant on the outlet side of the indoor evaporator 18 approaches a predetermined reference cooling superheat degree (5 ° C. in this embodiment). The

  On the other hand, when it is determined in step S61 that the refrigerant evaporation temperature Te is equal to or lower than the reference evaporation temperature KTe, the process proceeds to step S63, and temperature decrease prevention control is executed.

  When the refrigerant evaporation temperature Te is equal to or lower than the reference evaporation temperature KTe, frost formation may occur in the indoor evaporator 18. Therefore, in the temperature decrease prevention control in step S63, the second throttle passage of the second expansion valve 15b with respect to the first throttle passage area Ae1 of the first expansion valve 15a so that the refrigerant evaporation temperature Te becomes higher than the reference evaporation temperature KTe. The area ratio Ae2 / Ae1 of the area Ae2 is changed.

  More specifically, in step S63 of the present embodiment, the first throttle passage area Ae1 is decreased by a predetermined amount and the second throttle passage area Ae2 is increased by a predetermined amount. Thus, the area ratio Ae2 / Ae1 is increased so that the refrigerant flow rate Ge becomes larger than the reference flow rate KGe, so that the refrigerant evaporation temperature Te becomes higher than the reference evaporation temperature KTe.

  Moreover, about the control voltage output to the electric motor of the air blower 32, it determines similarly to heating mode. The control signal output to the electric actuator for the inside / outside air switching door is determined in the same manner as in the heating mode. About the control signal output to the electric actuator for blower outlet mode door drive, it determines similarly to heating mode.

  Therefore, in the refrigeration cycle apparatus 10 in the dehumidifying heating mode, the high-pressure refrigerant discharged from the compressor 11 flows into the indoor condenser 12. Since the air mix door 34 opens the air passage on the indoor condenser 12 side, the refrigerant flowing into the indoor condenser 12 is blown from the blower 32 and passed through the indoor evaporator 18 as in the heating mode. Heat exchange with heat. Thereby, blowing air is heated.

  The flow of the refrigerant flowing out of the indoor condenser 12 is branched at the first three-way joint 13a because the second on-off valve 22 is open. One refrigerant branched by the first three-way joint 13a flows out to the first refrigerant passage 14a side and is depressurized until it becomes a low-pressure refrigerant by the first expansion valve 15a. The low-pressure refrigerant decompressed by the first expansion valve 15a flows into the outdoor heat exchanger 16 and absorbs heat from the outside air blown from the blower fan.

  On the other hand, the other refrigerant branched by the first three-way joint 13a flows out to the second refrigerant passage 14b side. The refrigerant that has flowed out to the second refrigerant passage 14b side does not flow out to the outdoor heat exchanger 16 side due to the action of the check valve 17, and the second expansion is performed via the second on-off valve 22 and the third three-way joint 13c. It flows into the valve 15b.

  The refrigerant that has flowed into the second expansion valve 15b is depressurized until it becomes a low-pressure refrigerant. The low-pressure refrigerant decompressed by the second expansion valve 15 b flows into the indoor evaporator 18, absorbs heat from the blown air blown from the blower 32, and evaporates. Thereby, blowing air is cooled. The refrigerant that has flowed out of the indoor evaporator 18 is decompressed by the evaporation pressure adjusting valve 19, and has the same pressure as the refrigerant that has flowed out of the outdoor heat exchanger 16.

  The refrigerant that has flowed out of the evaporating pressure adjusting valve 19 flows into the fourth three-way joint 13d and joins with the refrigerant that has flowed out of the outdoor heat exchanger 16. The refrigerant merged at the fourth three-way joint 13d flows into the accumulator 20 and is gas-liquid separated. The gas-phase refrigerant separated by the accumulator 20 is sucked from the suction side of the compressor 11 and compressed again by the compressor 11.

  As described above, in the dehumidifying and heating mode, the dehumidifying and heating in the vehicle interior is performed by reheating the blown air that has been cooled and dehumidified by the indoor evaporator 18 and blown out into the vehicle interior by the indoor condenser 12. Can do.

  Furthermore, in the dehumidifying and heating mode of the present embodiment, the refrigerant evaporation temperature in the outdoor heat exchanger 16 can be made lower than the refrigerant evaporation temperature in the indoor evaporator 18. Therefore, the temperature difference between the refrigerant evaporation temperature and the outside air in the outdoor heat exchanger 16 can be increased, and the heat absorption amount in the outdoor heat exchanger 16 can be increased.

  Thereby, the heating capacity of the blown air in the indoor condenser 12 can be increased as compared with the refrigeration cycle apparatus in which the refrigerant evaporation temperature in the outdoor heat exchanger 16 is equal to the refrigerant evaporation temperature in the indoor evaporator 18.

(C) Cooling mode In the cooling mode, as shown in the chart of FIG. 7, the air conditioning control device 40 closes the first on-off valve 21, closes the second on-off valve 22, and fully opens the first expansion valve 15a. The second expansion valve 15b is brought into a throttled state.

  Thereby, in the cooling mode, as indicated by the white arrow in FIG. 1, the compressor 11 → the indoor condenser 12 → (first expansion valve 15 a →) outdoor heat exchanger 16 → (check valve 17 →) second A vapor compression refrigeration cycle in which the refrigerant is circulated in the order of the expansion valve 15b → the indoor evaporator 18 → the evaporation pressure adjusting valve 19 → the accumulator 20 → the compressor 11 is configured.

  Further, with the configuration of this refrigerant circuit, as described in step S5 above, the air conditioning control device 40 determines the operating states of various air conditioning control devices in the cooling mode.

  For example, the control signal output to the electric motor of the compressor 11 is determined as follows. First, the target evaporation temperature TEO in the indoor evaporator 18 is determined based on the target outlet temperature TAO with reference to a control map stored in the air conditioning control device 40 in advance. In this control map, it is determined that the target evaporation temperature TEO is decreased as the target blowing temperature TAO is decreased. Further, the target evaporation temperature TEO is provided with a lower limit value (2 ° C. in the present embodiment) in order to suppress frost formation of the indoor evaporator 18.

  Then, based on the deviation between the target evaporation temperature TEO and the refrigerant evaporation temperature Te detected by the evaporator temperature sensor 56, the compressor 11 is used so that the refrigerant evaporation temperature Te approaches the target evaporation temperature TEO using a feedback control method. A control signal to be output to the electric motor is determined.

  Regarding the control signal output to the electric actuator of the air mix door 34, the air mix door 34 fully opens the cold air bypass passage 35, and the entire flow rate of the blown air after passing through the indoor evaporator 18 passes through the cold air bypass passage 35. To be decided. In the cooling mode, the opening degree of the air mix door 34 may be controlled so that the blown air temperature TAV approaches the target blowing temperature TAO.

  The control signal output to the second expansion valve 15b is determined so that the degree of supercooling of the refrigerant flowing into the second expansion valve 15b approaches the target degree of supercooling. The target degree of supercooling is a value determined so that the coefficient of performance (COP) of the cycle becomes a maximum value.

  Moreover, about the control voltage output to the electric motor of the air blower 32, it determines similarly to heating mode and dehumidification heating mode. The control signal output to the electric actuator for the inside / outside air switching door is determined in the same manner as in the heating mode and the dehumidifying heating mode. About the control signal output to the electric actuator for blower outlet mode door drive, it determines similarly to heating mode and dehumidification heating mode.

  Therefore, in the refrigeration cycle apparatus 10 in the cooling mode, the high-pressure refrigerant discharged from the compressor 11 flows into the indoor condenser 12. At this time, since the air mix door 34 fully closes the air passage on the indoor condenser 12 side, the refrigerant flowing into the indoor condenser 12 flows out of the indoor condenser 12 with almost no heat exchange with the blown air. .

  Since the second on-off valve 22 is closed, the refrigerant flowing out from the indoor condenser 12 flows out from the first three-way joint 13a toward the first refrigerant passage 14a and flows into the first expansion valve 15a. At this time, since the first expansion valve 15a is fully opened, the refrigerant flowing out of the indoor condenser 12 flows into the outdoor heat exchanger 16 without being depressurized by the first expansion valve 15a.

  The refrigerant flowing into the outdoor heat exchanger 16 radiates heat to the outside air blown from the blower fan in the outdoor heat exchanger 16. Since the first on-off valve 21 is closed, the refrigerant that has flowed out of the outdoor heat exchanger 16 flows into the third refrigerant passage 14c via the second three-way joint 13b, and the low-pressure refrigerant is separated from the refrigerant at the second expansion valve 15b. The pressure is reduced until

  The low-pressure refrigerant decompressed by the second expansion valve 15b flows into the indoor evaporator 18 and absorbs heat from the blown air blown from the blower 32 to evaporate. Thereby, blowing air is cooled. The refrigerant flowing out of the indoor evaporator 18 flows into the accumulator 20 through the evaporation pressure adjusting valve 19 and is separated into gas and liquid. The gas-phase refrigerant separated by the accumulator 20 is sucked from the suction side of the compressor 11 and compressed again by the compressor 11.

  As described above, in the cooling mode, the vehicle interior can be cooled by blowing the blown air cooled by the indoor evaporator 18 into the vehicle interior.

  Therefore, according to the vehicle air conditioner 1 of the present embodiment, appropriate air conditioning in the passenger compartment can be realized by switching the operation of the heating mode, the dehumidifying heating mode, and the cooling mode.

  Here, in the refrigeration cycle apparatus capable of switching the refrigerant circuit as in the present embodiment, generally, the appropriate circulating refrigerant flow rate for circulating the cycle is different for each operation mode. Furthermore, in the refrigeration cycle apparatus 10 of the present embodiment, the indoor evaporator 18 and the outdoor heat exchanger 16 are connected in parallel to the refrigerant flow during the dehumidifying heating mode, and thus flow through the indoor evaporator 18 during the cooling mode. The refrigerant flow rate is higher than the refrigerant flow rate flowing through the indoor evaporator 18 in the dehumidifying heating mode.

  In addition to this, the evaporation pressure adjusting valve 19 of the present embodiment increases the flow rate of the refrigerant flowing through the evaporation pressure adjusting valve 19 (that is, the refrigerant flow rate Ge flowing through the indoor evaporator 18) and increases the indoor evaporator 18. It has a pressure regulation characteristic that increases the refrigerant evaporation pressure Pe.

  More specifically, the pressure regulation characteristic of the evaporation pressure regulating valve 19 of the present embodiment is set as shown by the thick solid line and the thick broken line in FIG.

  That is, as shown by the thick solid line in FIG. 8, within the range of the refrigerant flow rate Ge in the cooling mode, the refrigerant evaporating pressure Pe becomes the frosting suppression pressure APe (specifically, A value slightly higher than 0.293 MPa). Thereby, the evaporating pressure adjusting valve 19 adjusts the refrigerant evaporating temperature Te to be the lowest value (specifically, 2 ° C.) of the target evaporating temperature TEO even at the time of the minimum refrigerant flow rate in the cooling mode. Can do.

  On the other hand, in the pressure regulation characteristic of the evaporation pressure regulating valve 19 of the present embodiment, as shown by the thick broken line in FIG. 8 in the dehumidifying heating mode in which the refrigerant flow rate flowing through the indoor evaporator 18 is lower than in the cooling mode. The refrigerant evaporation pressure Pe of the indoor evaporator 18 is lower than the frosting suppression pressure APe, and frost formation may occur in the indoor evaporator 18.

  On the other hand, in the refrigeration cycle apparatus 10 of the present embodiment, in the dehumidifying heating mode, the refrigerant flow rate Ge is set to be larger than the reference flow rate KGe, that is, not to enter the region of the thick broken line in FIG. The area ratio Ae2 / Ae1 of the second throttle passage area Ae2 of the second expansion valve 15b to the first throttle passage area Ae1 of the first expansion valve 15a is changed.

  Accordingly, during the dehumidifying heating mode, the refrigerant evaporation temperature Te in the indoor evaporator 18 can be maintained at a temperature that does not cause the indoor evaporator 18 to form frost, and the indoor evaporator 18 can be prevented from forming frost. can do.

  Furthermore, in the present embodiment, the refrigerant evaporation temperature Te can be adjusted to the minimum value (specifically, 2 ° C.) of the target evaporation temperature TEO at the maximum refrigerant flow rate in the cooling mode. Therefore, in order to lower the refrigerant evaporation temperature Te until reaching the target evaporation temperature TEO, there is no control interference that unnecessarily increases the refrigerant discharge capacity of the compressor 11.

  As a result, it is possible to suppress the consumption power of the compressor 11 from being increased unnecessarily and the cooling capacity of the blown air in the indoor evaporator 18 from being insufficient.

  In the refrigeration cycle apparatus 10 of the present embodiment, the area ratio Ae2 / Ae1 is changed so that the refrigerant evaporation temperature Te in the indoor evaporator 18 is higher than the reference evaporation temperature KTe in the dehumidifying heating mode. Therefore, the area ratio Ae2 / Ae1 is set so that the refrigerant flow rate Ge is larger than the reference flow rate KGe with a simple configuration without requiring a flow rate detection unit for detecting the flow rate of the refrigerant actually flowing through the indoor evaporator 18. Can be changed.

  Of course, the same effect can be obtained by changing the area ratio Ae2 / Ae1 so that the low-pressure side refrigerant pressure Pe detected by the low-pressure side pressure sensor 57 is higher than the predetermined reference evaporation pressure KPe in the dehumidifying heating mode. Can be obtained.

  Further, in the refrigeration cycle apparatus 10 of the present embodiment, the refrigerant evaporation temperature Te is the reference when it is in the dehumidifying heating mode and the refrigerant evaporation temperature Te in the indoor evaporator 18 is equal to or lower than the reference evaporation temperature KTe. The area ratio Ae2 / Ae1 is changed so as to be higher than the evaporation temperature KTe.

  Therefore, even in the dehumidifying and heating mode, when the refrigerant evaporation temperature Te is higher than the reference evaporation temperature KTe, the operation of the first expansion valve 15a and the second expansion valve 15b is controlled to control the refrigeration cycle. The apparatus 10 can exhibit a high coefficient of performance (COP).

(Second Embodiment)
This embodiment demonstrates the example which changed the control aspect in the temperature fall prevention control of dehumidification heating mode with respect to 1st Embodiment.

  In the temperature drop prevention control of the present embodiment, as in the first embodiment, the pressure reducing device controller 40c decreases the first throttle passage area Ae1 by a predetermined amount and increases the second throttle passage area Ae2 by a predetermined amount. As a result, the area ratio Ae2 / Ae1 is increased. In addition, the total passage area Ae1 + Ae2 of the first throttle passage area Ae1 and the second throttle passage area Ae2 is increased.

  More specifically, as shown in FIG. 9, similarly to the first embodiment, the first throttle passage area Ae1 of the first expansion valve 15a is decreased by a predetermined amount (point A11 → point A12 in FIG. 9). Further, the first throttle passage area Ae1 is increased by a predetermined amount (point A12 → point A13 in FIG. 9). For this reason, in the temperature drop prevention control of the present embodiment, the operation of the first expansion valve 15a is controlled so as to maintain the first throttle passage area Ae1.

  Similarly to the first embodiment, the second throttle passage area Ae2 of the second expansion valve 15b is increased by a predetermined amount (point A21 → point A22 in FIG. 9), and the second throttle passage area Ae2 is further increased. Increase by a fixed amount (point A22 → point A23 in FIG. 9). That is, in the temperature decrease prevention control of the present embodiment, the total passage area Ae1 + Ae2 is increased by enlarging the second throttle passage area Ae2 than in the first embodiment.

  Furthermore, in the temperature decrease prevention control of the present embodiment, the first expansion valve 15a and the second expansion valve 15b are arranged so that the superheat degree SH of the refrigerant on the outlet side of the outdoor heat exchanger 16 approaches the predetermined reference outdoor superheat degree. The operation is controlled. The reference outdoor superheat degree is a value set to suppress an excessive increase in the superheat degree SH of the refrigerant on the outlet side of the outdoor heat exchanger 16.

  The operation of the refrigeration cycle apparatus 10 in the dehumidifying and heating mode of the present embodiment will be described with reference to the Mollier diagrams of FIGS. First, in the refrigeration cycle apparatus 10 during normal control in the dehumidifying operation mode, as shown in FIG. 10, the refrigerant discharged from the compressor 11 (point a10 in FIG. 10) flows into the indoor condenser 12 and blown air. The heat is dissipated (point a10 → point b10 in FIG. 10).

  One refrigerant that has flowed out of the indoor condenser 12 and branched by the first three-way joint 13a is decompressed by the first expansion valve 15a (b10 point → c10 point in FIG. 10). The refrigerant decompressed by the first expansion valve 15a absorbs heat from the outside air in the outdoor heat exchanger 16 (point c10 → point d10 in FIG. 10).

  The other refrigerant that has flowed out of the indoor condenser 12 and branched by the first three-way joint 13a is decompressed by the second expansion valve 15b (b10 point → e10 point in FIG. 10). The refrigerant decompressed by the second expansion valve 15b absorbs heat from the blown air in the indoor evaporator 18 (point e10 → point f10 in FIG. 10). The refrigerant that has flowed out of the indoor evaporator 18 is decompressed by the evaporation pressure regulating valve 19 and becomes the same pressure as the refrigerant that has flowed out of the outdoor heat exchanger 16 (f10 point → g10 point in FIG. 10).

  The refrigerant flow that has flowed out of the outdoor heat exchanger 16 and the refrigerant flow that has been depressurized by the evaporating pressure adjusting valve 19 are merged by the fourth three-way joint 13d and are separated into gas and liquid by the accumulator 20 to be supplied to the compressor 11. Inhaled (d10 point → h10 point, g10 point → h10 point in FIG. 10).

  Next, temperature drop prevention control will be described. In the refrigeration cycle apparatus 10 during the temperature reduction prevention control, the total passage area Ae1 + Ae2 is increased, so that a refrigerant having a lower density can flow through the first expansion valve 15a and the second expansion valve 15b than during the normal control. For this reason, as shown in FIG. 11, the cycle balances in a state where the enthalpy of the refrigerant flowing out from the indoor condenser 12 is higher than that during normal control (b11 point in FIG. 11).

  Furthermore, at the time of temperature drop prevention control, the area ratio Ae2 / Ae1 increases and the flow rate of refrigerant flowing through the outdoor heat exchanger 16 tends to decrease, so that the refrigerant evaporation temperature in the outdoor heat exchanger 16 rises and the outlet side refrigerant The degree of superheat SH (point d11 in FIG. 11) tends to increase. Therefore, in the temperature decrease prevention control, the first expansion valve 15a and the second expansion valve 15b are set so that the superheat degree SH of the refrigerant on the outlet side of the outdoor heat exchanger 16 (point d11 in FIG. 11) approaches the reference outdoor superheat degree. The operation is controlled.

  Here, in the Mollier diagram of FIG. 11, the state of the refrigerant at the same place in the cycle configuration is indicated by the same reference numerals (alphabet) as in FIG. 10 with respect to the Mollier diagram of FIG. Only the subscripts (numbers) are changed.

  Other configurations and operations of the refrigeration cycle apparatus 10 are the same as those in the first embodiment. Therefore, also in the refrigeration cycle apparatus 10 of the present embodiment, in the dehumidifying heating mode, the area ratio Ae2 / Ae1 and the total passage area Ae1 + Ae2 can be changed so that the refrigerant flow rate Ge is larger than the reference flow rate KGe. Similarly to the embodiment, it is possible to suppress frost formation in the indoor evaporator 18.

  Furthermore, in the refrigeration cycle apparatus 10 of the present embodiment, the operation of the first expansion valve 15a is controlled so as to maintain the first throttle passage area Ae1 during the temperature drop prevention control. As a result, a significant decrease in the flow rate of the refrigerant flowing through the outdoor heat exchanger 16 can be suppressed, and a decrease in the heat absorption amount in the outdoor heat exchanger 16 can be suppressed.

  Further, in the refrigeration cycle apparatus 10 of the present embodiment, the operation of the first expansion valve 15a and the second expansion valve 15b is controlled so that the superheat degree SH of the refrigerant on the outlet side of the outdoor heat exchanger 16 approaches the reference outdoor superheat degree. doing. According to this, the degree of superheat SH of the refrigerant on the outlet side of the outdoor heat exchanger 16 increases excessively, and the refrigerant evaporation pressure of the outdoor heat exchanger 16 (that is, the refrigerant pressure in the accumulator 20) is unnecessarily lowered. Can be suppressed.

  Therefore, it can suppress that the density of the suction | inhalation refrigerant | coolant suck | inhaled from the accumulator 20 to the compressor 11 falls, and the heating capability at the time of reheating blowing air in the indoor condenser 12 will fall. This can be suppressed.

(Third embodiment)
In the present embodiment, an example in which a third on-off valve 23 is added to the first embodiment will be described as shown in the overall configuration diagram of FIG. The third opening / closing valve 23 is an electromagnetic valve as an opening / closing device that opens and closes the refrigerant outlet side of the indoor evaporator 18. The third on-off valve 23 is disposed in the refrigerant passage extending from the outlet 91b of the evaporation pressure adjusting valve 19 to the fourth three-way joint 13d.

  The basic configuration of the third on-off valve 23 is the same as that of the first on-off valve 21. Therefore, as shown in FIG. 13, the operation of the third on-off valve 23 is controlled by a control signal output from the air conditioning control device 40. For this reason, in this embodiment, the structure which controls the action | operation of the 3rd on-off valve 23 among the air-conditioning control apparatuses 40 comprises the on-off control part 40d.

  Next, the temperature drop prevention control of this embodiment will be described. In the temperature decrease prevention control of the present embodiment, when the refrigerant evaporation temperature Te is equal to or lower than the reference evaporation temperature KTe, the third on-off valve 23 is closed and the second expansion valve 15b is fully closed. Of course, during normal control (that is, when the refrigerant evaporation temperature Te is higher than the reference evaporation temperature KTe), the third on-off valve 23 is opened.

  Other configurations and operations of the refrigeration cycle apparatus 10 are the same as those in the first embodiment. In the refrigeration cycle apparatus 10 of the present embodiment, the third on-off valve 23 is closed and the second expansion valve 15b is fully closed during temperature reduction prevention control. Thereby, at the time of temperature fall prevention control, the refrigerant does not flow into the indoor evaporator 18, and the refrigerant is not evaporated in the indoor evaporator 18 and exhibits an endothermic effect. Therefore, it is possible to suppress frost formation in the indoor evaporator 18.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  (1) In the above-described embodiment, the example in which the refrigeration cycle apparatus 10 of the present invention is applied to the vehicle air conditioner 1 mounted on an electric vehicle has been described, but the application of the present invention is not limited to this. For example, the driving force for driving the vehicle may be applied to a vehicle air conditioner mounted on a normal vehicle that obtains the driving force from the internal combustion engine (engine), and the driving force for driving may be applied to both the driving electric motor and the internal combustion engine. You may apply to the vehicle air conditioner mounted in the hybrid vehicle obtained from.

  Moreover, in the vehicle air conditioner 1 applied to a vehicle having an internal combustion engine, a heater core that heats the blown air using the cooling water of the internal combustion engine as a heat source may be provided as an auxiliary heating device for the blown air. Furthermore, the refrigeration cycle apparatus 10 of the present invention is not limited to a vehicle, and may be applied to a stationary air conditioner or the like.

  Further, in the above-described embodiment, the indoor condenser 12 that is a heat exchanger for heating causes heat exchange between the discharged refrigerant discharged from the compressor 11 and the blown air, and the blown air directly using the discharged refrigerant as a heat source. Although the example which heats was demonstrated, the heating aspect of the ventilation air in the heat exchanger for a heating is not limited to this.

  For example, a heat medium circulation circuit for circulating the heat medium is provided, and the heat medium circulation circuit is heated by a water-refrigerant heat exchanger and a water-refrigerant heat exchanger that exchange heat between the discharged refrigerant and the heat medium. A heating heat exchanger that heats the blown air by exchanging heat between the heat medium and the blown air is disposed. Then, in the heat exchanger for heating, the blown air may be indirectly heated through the heat medium using the discharged refrigerant as a heat source.

  (2) In each of the embodiments described above, the refrigeration cycle apparatus 10 that can be switched to the refrigerant circuit in the heating mode, the dehumidifying heating mode, and the cooling mode has been described. However, at least the dehumidifying heating mode and the cooling mode of the above-described embodiment are used. If it is a switchable refrigeration cycle apparatus, the effect of suppressing frost formation of the indoor evaporator 18 described in each embodiment can be obtained.

  Further, in the refrigeration cycle apparatus 10 described in each of the above-described embodiments, the first and second on-off valves 21 and 22 are closed and the outdoor heat exchanger 16 and the indoor evaporator 18 are directly connected in the same manner as in the cooling mode. Auxiliary dehumidification heating mode (series dehumidification heating mode) that performs dehumidification heating in the passenger compartment by switching to the refrigerant circuit and changing the throttle opening of the first expansion valve 15a and the second expansion valve 15b according to the target blowing temperature TAO. The operation in the heating mode may be performed.

  Specifically, in the auxiliary dehumidifying heating mode, the throttle opening of the first expansion valve 15a is decreased and the throttle opening of the second expansion valve 15b is increased as the target blowing temperature TAO increases. Thereby, the outdoor heat exchanger 16 may be switched from a state of functioning as a radiator to a state of functioning as an evaporator, and the heating capacity of the blown air in the indoor condenser 12 may be changed.

  (3) In the above-described second embodiment, the example in which the area ratio Ae2 / Ae1 is increased and the total passage area Ae1 + Ae2 is increased during the temperature decrease prevention control has been described. The effect is obtained by increasing the flow rate of the refrigerant flowing through the evaporation pressure regulating valve 19. Therefore, even if the total passage area Ae1 + Ae2 is changed in the same manner as in the second embodiment without changing the area ratio Ae2 / Ae1, the effect of suppressing frost formation can be obtained.

  (4) In the third embodiment described above, an example in which the third on-off valve 23 as an on-off device is arranged in the refrigerant passage from the outlet 91b of the evaporation pressure adjusting valve 19 to the fourth three-way joint 13d has been described. Of course, you may arrange | position in the upstream of the inflow port 91a of the evaporation pressure regulating valve 19. FIG. That is, as long as the refrigerant outlet side of the indoor evaporator 18 can be opened and closed, the third on-off valve 23 may be arranged in any refrigerant passage from the refrigerant outlet of the indoor evaporator 18 to the fourth three-way joint 13d. .

  In the third embodiment described above, the third on-off valve 23 and the second expansion valve 15b are continuously closed during the temperature drop prevention control, but the third on-off valve 23 and the second expansion valve 15b are intermittently connected. You may make it close automatically. According to this, it is possible to suppress control hunting while supplying a small amount of refrigerant to the indoor evaporator 18 and exhibiting a certain amount of cooling capacity (dehumidification capacity) of the blown air.

  In the above-described third embodiment, the example in which the third on-off valve 23 is added as the on-off device has been described. However, the evaporation pressure adjusting valve 19 and the third on-off valve 23 may be integrated. In this case, a variable throttle mechanism with a fully-closed function similar to the second expansion valve 15b may be employed.

  (5) The means disclosed in each of the above embodiments may be appropriately combined within a practicable range. For example, in the second embodiment, as described in the first embodiment, in the dehumidifying heating mode, the area is set so that the low-pressure side refrigerant pressure Pe detected by the low-pressure side pressure sensor 57 is higher than the reference evaporation pressure KPe. The ratio Ae2 / Ae1 and the total passage area Ae1 + Ae2 may be varied.

  In the third embodiment, the third opening / closing is also performed in the dehumidifying heating mode and when the low-pressure side refrigerant pressure Pe detected by the low-pressure side pressure sensor 57 is higher than the reference evaporation pressure KPe. When the valve 23 is opened and the low pressure side refrigerant pressure Pe detected by the low pressure side pressure sensor 57 is equal to or lower than the reference evaporation pressure KPe in the dehumidifying and heating mode, the third on-off valve 23 is opened. You may make it close.

  (6) In each of the above-described embodiments, the example in which each operation mode is switched by executing the air conditioning control program has been described. However, the switching of each operation mode is not limited to this. For example, an operation mode setting switch for setting each operation mode may be provided on the operation panel, and the heating mode, the cooling mode, and the dehumidifying heating mode may be switched according to an operation signal of the operation mode setting switch.

11 Compressor 12 Indoor condenser (heat exchanger for heating)
15a First expansion valve (first decompression device)
15b Second expansion valve (second decompression device)
16 Outdoor heat exchanger 18 Indoor evaporator (cooling heat exchanger)
19 Evaporation pressure regulating valve 21, 22 First on-off valve, second on-off valve (refrigerant circuit switching device)
23 Third open / close valve (open / close device)
40c Pressure reducing device control unit 40d Opening / closing control unit

Claims (8)

A refrigeration cycle apparatus applied to an air conditioner,
A compressor (11) for compressing and discharging the refrigerant;
A heat exchanger for heating (12) that heats the air blown into the air-conditioning target space by using the refrigerant discharged from the compressor as a heat source;
A first decompression device (15a) for decompressing the refrigerant;
An outdoor heat exchanger (16) for exchanging heat between the refrigerant flowing out of the first decompression device and the outside air;
A second decompression device (15b) for decompressing the refrigerant;
A cooling heat exchanger (18) for exchanging heat between the refrigerant flowing out of the second decompression device and the blown air before passing through the heating heat exchanger;
An evaporation pressure adjusting valve (19) for adjusting the refrigerant evaporation pressure (Pe) in the cooling heat exchanger;
A refrigerant circuit switching device (21, 22) for switching the refrigerant circuit;
A pressure reducing device controller (40c) that controls the operation of the first pressure reducing device and the second pressure reducing device,
The evaporating pressure regulating valve increases the refrigerant evaporating pressure (Pe) with an increase in the flow rate of the refrigerant flowing inside.
The refrigerant circuit switching device is
In the cooling mode in which the cooled blown air is blown out to the air-conditioning target space, the refrigerant that has flowed out of the heating heat exchanger is converted into the first pressure reducing device → the outdoor heat exchanger → the second pressure reducing device → the heat exchange for cooling. Switch to a refrigerant circuit that flows in the order of the vessel → the evaporation pressure control valve → the compressor,
In the dehumidifying and heating mode in which the blown air that has been cooled and dehumidified is reheated and blown out to the air-conditioning target space, the flow of the refrigerant flowing out from the heating heat exchanger is branched, and one of the branched refrigerants is divided into the first refrigerant Refrigerant that flows in the order of the pressure reducing device → the outdoor heat exchanger → the compressor and the other branched refrigerant flows in the order of the second pressure reducing device → the heat exchanger for cooling → the evaporation pressure regulating valve → the compressor. Switch to circuit,
In the dehumidifying and heating mode, the decompression device control unit controls the first decompression device so that the refrigerant flow rate (Ge) flowing through the evaporation pressure regulating valve is greater than a predetermined reference flow rate (KGe). A refrigeration cycle apparatus that changes an area ratio (Ae2 / Ae1) of a second throttle passage area (Ae2) of the second decompression device to a throttle passage area (Ae1).   In the dehumidifying and heating mode, the decompression device controller controls the area ratio (Ae2 / Ae1) so that the refrigerant evaporation temperature (Te) in the cooling heat exchanger is higher than a predetermined reference evaporation temperature (KTe). The refrigeration cycle apparatus according to claim 1, wherein the refrigeration cycle apparatus is changed.   The decompression device control unit is in the dehumidifying heating mode, and when the refrigerant evaporation temperature (Te) in the cooling heat exchanger is equal to or lower than a predetermined reference evaporation temperature (KTe), The area ratio (Ae2 / Ae1) is changed so that the refrigerant evaporation temperature (Te) in the cooling heat exchanger is higher than a predetermined reference evaporation temperature (KTe). The refrigeration cycle apparatus described.   In the dehumidifying and heating mode, the decompression device control unit controls the first decompression device so that the refrigerant flow rate (Ge) flowing through the evaporation pressure regulating valve is greater than a predetermined reference flow rate (KGe). The refrigeration cycle according to any one of claims 1 to 3, wherein the total passage area (Ae1 + Ae2) of the throttle passage area (Ae1) and the second throttle passage area (Ae2) of the second decompression device is increased. apparatus.   The said decompression device control part controls the action | operation of a said 1st decompression device so that the 1st throttle passage area (Ae1) of a said 1st decompression device may be maintained at the time of the said dehumidification heating mode. Refrigeration cycle equipment.   In the dehumidifying and heating mode, the decompression device control unit is configured so that the degree of superheat (SH) of the refrigerant on the outlet side of the outdoor heat exchanger (16) approaches a predetermined reference outdoor superheat degree and The refrigeration cycle apparatus according to claim 4 or 5, wherein the operation of the second decompression device is controlled. A refrigeration cycle apparatus applied to an air conditioner,
A compressor (11) for compressing and discharging the refrigerant;
A heat exchanger for heating (12) that heats the air blown into the air-conditioning target space by using the refrigerant discharged from the compressor as a heat source;
A first decompression device (15a) for decompressing the refrigerant;
An outdoor heat exchanger (16) for exchanging heat between the refrigerant flowing out of the first decompression device and the outside air;
A second decompression device (15b) for decompressing the refrigerant;
A cooling heat exchanger (18) for exchanging heat between the refrigerant flowing out of the second decompression device and the blown air before passing through the heating heat exchanger;
An evaporation pressure adjusting valve (19) for adjusting the refrigerant evaporation pressure (Pe) in the cooling heat exchanger;
An opening and closing device (23) for opening and closing the refrigerant outlet side of the cooling heat exchanger;
An open / close control unit (40d) for controlling the operation of the open / close device;
A refrigerant circuit switching device (21, 22) for switching the refrigerant circuit,
The evaporating pressure adjusting valve increases the refrigerant evaporating pressure (Pe) as the flow rate of the refrigerant flowing through the cooling heat exchanger increases.
The refrigerant circuit switching device is
In the cooling mode in which the cooled blown air is blown out to the air-conditioning target space, the refrigerant that has flowed out of the heating heat exchanger is converted into the first pressure reducing device → the outdoor heat exchanger → the second pressure reducing device → the heat exchange for cooling. Switch to the refrigerant circuit that flows in the order of the vessel → the switchgear → the compressor,
In the dehumidifying and heating mode in which the blown air that has been cooled and dehumidified is reheated and blown out to the air-conditioning target space, the flow of the refrigerant flowing out from the heating heat exchanger is branched, and one of the branched refrigerants is divided into the first refrigerant The refrigerant circuit flows in the order of the pressure reducing device → the outdoor heat exchanger → the compressor and the other branched refrigerant flows in the order of the second pressure reducing device → the cooling heat exchanger → the switchgear → the compressor. switching,
The opening / closing control unit is in the dehumidifying heating mode, and when the refrigerant evaporation temperature (Te) in the cooling heat exchanger is higher than a predetermined reference evaporation temperature (KTe), When the refrigerant outlet side of the cooling heat exchanger is opened, and in the dehumidifying and heating mode, and the refrigerant evaporation temperature (Te) is equal to or lower than the reference evaporation temperature (KTe), A refrigeration cycle apparatus that controls the operation of the switchgear so as to close a refrigerant outlet side of the cooling heat exchanger. Furthermore, a pressure reducing device controller (40c) that controls at least the operation of the second pressure reducing device is provided,
The second pressure reducing device has a fully closed function of fully closing the throttle passage,
In the dehumidifying and heating mode, the decompression device control unit is configured to close the second decompression device so as to close the second decompression device when the refrigerant evaporation temperature (Te) is equal to or lower than the reference evaporation temperature (KTe). The refrigeration cycle apparatus according to claim 7, wherein the operation of the apparatus is controlled.

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