JP4195523B2 - Air conditioner refrigerant circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a refrigerant circuit of an air conditioner, and is particularly useful when applied to a refrigerant circuit of a vehicle air conditioner provided in a hybrid vehicle having an engine and a travel motor as travel drive means.
[0002]
[Prior art]
FIG. 7 is an explanatory view showing an example of the configuration of a main part of a conventional vehicle air conditioner provided in a hybrid vehicle, and FIG. 8 is a block diagram showing an example of a refrigerant circuit of the vehicle air conditioner. The apparatus shown in FIGS. 7 and 8 is disclosed in JP-A-5-162536.
[0003]
The hybrid vehicle 14 shown in FIG. 7 has an engine 13 mounted at the rear of the vehicle and a traveling motor 5 mounted at the front of the vehicle. The hybrid vehicle 14 is also equipped with a battery, an inverter, etc. (not shown) for driving the traveling motor 5.
[0004]
The vehicle air conditioner of the hybrid vehicle 14 has a duct 7 having intake holes 1, 6, 8, 9, 10, 12 and an exhaust hole 4. A switching damper 2, an outdoor heat exchanger 3, and a blower 14 are provided inside the duct 7. The exhaust hole 4 is provided on the lower surface of the vehicle, and the outdoor heat exchanger 3 and the blower 14 are provided immediately before the exhaust hole 4. The switching damper 2 is provided above the outdoor heat exchanger 3 and is turned to the a side or the b side in FIG. 7 by a motor or the like (not shown) so that the flow path communicating with the exhaust hole 4 is connected to the intake hole 1 side or Switch to other intake holes 6, 8, 9, 10, 12 side. In addition, 11 in FIG. 7 is a radiator.
[0005]
Therefore, in this vehicle air conditioner, when the cooling operation is performed, the switching damper 2 is rotated to the a side in FIG. 7 and the flow path is switched to the intake hole 1 side. As shown, the air sucked from the intake hole 1 by the blower 14 passes through the outdoor heat exchanger 3 and is discharged from the exhaust hole 4 to the outside of the vehicle. When heating operation is performed, the switching damper 2 is rotated to the b side in FIG. 7 to switch the flow path to the intake holes 6, 8, 9, 10, and 12, and the black arrow in FIG. 7. As shown, the air sucked from the intake holes 6, 8, 9, 10, and 12 by the blower 14 is discharged from the exhaust hole 4 through the outdoor heat exchanger 3 to the outside of the vehicle.
[0006]
As shown in FIG. 8, the refrigerant circuit of the vehicle air conditioner functions as a heat pump, and performs cooling operation and heating operation by switching the refrigerant flow path by the four-way valve 15. ing.
[0007]
That is, during the cooling operation, the refrigerant is the compressor 16, the four-way valve 15, the outdoor heat exchanger 3, the check valve 22, the capillary tube (capillary tube) 20, the indoor heat exchanger 21, the four-way valve 15, the accumulators 17 and 18, and the compressor 16. It flows in the order. At this time, the indoor heat exchanger 21 becomes a heat absorber (evaporator), the outdoor heat exchanger 3 becomes a heat radiator (condenser), and the interior of the vehicle compartment 24 (see FIG. 7) is cooled. On the other hand, during the heating operation, the refrigerant flows in the order of the compressor 16, the four-way valve 15, the indoor heat exchanger 21, the check valve 23, the capillary tube 19, the outdoor heat exchanger 3, the four-way valve 15, the accumulators 17 and 18, and the compressor 16. . At this time, the outdoor heat exchanger 3 becomes a heat absorber (evaporator), the indoor heat exchanger 21 becomes a radiator (condenser), and the interior of the vehicle compartment 24 is heated.
[0008]
[Problems to be solved by the invention]
However, in the refrigerant circuit of the conventional vehicle air conditioner, when the compressor 16 is temporarily stopped and then restarted, it cannot be restarted immediately, and a relatively long waiting time is required. That is, if the pressure difference between the discharge side and the suction side of the compressor 16 is large, the torque is too large.²Can't be restarted) However, since the refrigerant circuit is provided with a throttle mechanism (capillary tubes 19 and 20 in the illustrated example) for reducing the pressure of the refrigerant, the discharge side and the suction side of the compressor 16 do not readily equalize pressure. For example, it takes about 3 minutes to equalize the pressure.
[0009]
This is considered to be a problem particularly in the case of the hybrid vehicle 14. That is, in the hybrid vehicle 14, in order to take advantage of the characteristics of the traveling motor 5 that can obtain a high torque at the time of starting (at low speed) and the characteristics of the engine 13 that can obtain a high torque at the time of high speed, the hybrid vehicle 14 can start at the time of starting the vehicle (at low speed). ) Travels by the traveling motor 5 and travels by the engine 13 at a high speed. In this case, there is a possibility that the traveling motor 5 and the engine 13 are frequently switched. In the hybrid vehicle 14, the compressor 16 may be configured to be selectively driven by the engine 13 and a compressor motor (not shown). In this case, as described above, the travel motor 5 and the engine 13 are connected to each other. If the switching is frequently performed, the start / stop of the compressor 16 is frequently repeated accordingly. For this reason, if it takes time to restart the compressor 16 as described above, appropriate air conditioning cannot be performed, which is very inconvenient. From the viewpoint of comfort, the waiting time until restart is preferably as short as possible.
[0010]
For example, when the compressor 16 is stopped during the heating operation, the liquid refrigerant in the indoor heat exchanger (condenser) 21 on the high pressure side flows into the outdoor heat exchanger (evaporator) 3 side on the low pressure side, as described above. If the start / stop of the compressor 16 is frequently repeated, the liquid refrigerant in the outdoor heat exchanger (evaporator) 3 returns to the compressor 16 and the oil circulating with the refrigerant is diluted in the compressor 16. For this reason, the oil film of the bearing part of the compressor 16 becomes thin, and the compressor 16 may be seized and may break down.
[0011]
Furthermore, it is preferable that the compressor 16 is stabilized in a short time after the compressor 16 is restarted (the refrigerant distribution is restored to the state before the stop in a short time), and also from this, the high pressure part (condenser) and the low pressure part (evaporator) ) Is instantaneously interrupted to prevent the refrigerant from moving from the high pressure section (condenser) to the low pressure section (evaporator).
[0012]
However, in general, for example, when a temperature expansion valve is used to control the degree of superheat of the refrigerant at the evaporator outlet at a constant level, the time from when the compressor stops until the temperature expansion valve reaches full closure is used. The length is unavoidable due to its structure. That is, the temperature type expansion valve applies an evaporating pressure and a spring force in the valve closing direction, while applying a higher pressure in the valve opening direction by a pressure corresponding to the superheat degree, and the superheat degree is large. When the differential pressure Δp between the two pressures acting on the temperature type expansion valve increases, the opening degree increases and the refrigerant flow rate increases. When the superheat degree decreases and the differential pressure Δp decreases, the opening degree increases. The superheat degree is controlled to be constant by decreasing the refrigerant flow rate. For this reason, when the compressor is stopped, the temperature type expansion valve is closed to eliminate the degree of superheat. However, it takes time for the temperature expansion valve to reach full closure. Accordingly, during this time, the refrigerant moves from the high pressure portion (condenser) to the low pressure portion (evaporator), and it takes time for the refrigerant distribution to return to the original state after restart. That is, the time required to reach stability becomes longer.
[0013]
Further, when unvaporized refrigerant (liquid refrigerant) directly flows into the compressor 16 by the evaporator (the indoor heat exchanger 21 or the outdoor heat exchanger 3) at the time of starting or the like, the oil is diluted as in the above case, and the compressor 16 Therefore, an accumulator is provided on the suction side of the compressor 16 in order to accumulate liquid refrigerant and return only the vapor refrigerant to the compressor 16 (in the illustrated example, the two-stage accumulators 17 and 18 are provided). Provided).
[0014]
As such an accumulator, one having a structure as shown in FIG. 7 is generally known. In the accumulator 25 shown in the figure, the end portion 27a of one pipe 27 connected to the accumulator 25 is located at the upper portion (gas phase portion 25a) of the accumulator 25, while the end portion 26a of the other pipe 26 connected to the accumulator 25 is shown. Is formed in a U-shape, is located in the liquid phase part 25b of the accumulator 25, and has a tip protruding into the gas phase part 25a. In addition, since oil also accumulates in the liquid phase portion 25a of the accumulator 25 and the oil in the compressor disappears as it is, the oil accumulated in the accumulator 25 is sucked into the end portion 26a of the pipe 26 and supplied to the compressor. In addition, an oil pickup hole 26b is provided.
[0015]
However, in such a U-shaped tube type accumulator 25, when the liquid refrigerant accumulated in the accumulator 25 increases due to repeated start-up and stop of the compressor, the end portion 26a (U-shaped) of the pipe 26 increases. The liquid refrigerant enters the portion), and the liquid refrigerant is sucked into the compressor when the compressor is started. As a result, as in the case described above, there is a possibility that the oil in the compressor is diluted and the compressor breaks down.
[0016]
  Therefore, in view of the prior art, the present invention provides a refrigerant circuit of an air conditioner that can equalize the discharge side and the suction side of a compressor in a short time.ImposeThe title.
[0022]
[Means for Solving the Problems]
  The present invention solves the above problems.The refrigerant circuit of the air conditionerThe refrigerant compressed by the compressor is sent from the discharge side of the compressor to the outdoor heat exchanger or the indoor heat exchanger, and again returned from the indoor heat exchanger or the outdoor heat exchanger to the suction side of the compressor. In the refrigerant circuit of the air conditioner,
  Providing a check valve on the discharge side of the compressor, connecting the check valve and the compressor, and the suction side of the compressor with a capillary tube;
  An open / close valve is provided in series with the capillary tube, and an oil separator provided with a liquid level detecting means is provided between the compressor and the check valve, and one end of the capillary tube is connected to the oil separator. In addition, a control device for controlling the opening and closing of the on-off valve is provided, and based on the detection signal of the liquid level detecting means for detecting the liquid level of the oil separator when the oil separator is operated by the control device.When the liquid level is equal to or higher than a predetermined value, the on-off valve is opened, and when the liquid level is lower than the predetermined value, the on-off valve is closed to prevent the refrigerant from blowing through,It is characterized in that the on-off valve is controlled to be opened when stopped.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0026]
FIG. 1 is a plan view showing a layout relating to a thermal system of a hybrid vehicle provided with a refrigerant circuit of a vehicle air conditioner according to an embodiment of the present invention, FIG. 2 is a system diagram of the thermal system, and FIG. 3 is a diagram of the refrigerant circuit. It is a block diagram extracted and shown.
[0027]
<Configuration>
A hybrid vehicle 31 shown in FIG. 1 is a so-called parallel hybrid vehicle, and a drive unit 33 including a traveling motor is mounted on the front of the vehicle, and an engine 32 is mounted on the rear of the vehicle. A transmission 48, a generator 35, a battery 34, and the like are mounted on the rear portion of the vehicle, and an inverter 36 and the like are mounted on the front portion of the vehicle.
[0028]
Therefore, in the hybrid vehicle 31, the rear wheel 37 is rotationally driven by the engine 32 via the transmission 48, and the front wheel 38 is rotationally driven by the drive unit 33. In addition, the hybrid vehicle 31 takes advantage of the characteristics of the drive unit 33 (travel motor) that can obtain a high torque at the start (low speed) and the characteristics of the engine 32 that can obtain a high torque at a high speed. The vehicle travels by the drive unit 33 (at low speed), and travels by both the engine 32 and the drive unit 33 or only by the engine 32 at high speed.
[0029]
Note that the drive motor of the drive unit 33 is supplied with electric power from the battery 34 via the inverter 36 and the rotation speed and the like are controlled by the inverter 36 and the like. Further, when the engine 32 is operated, the generator 35 is rotationally driven by the engine 32 to generate power, and this generated power is charged to the battery 34 and also supplied to the traveling motor via the inverter 36. .
[0030]
Moreover, each component regarding thermal systems, such as a vehicle air conditioner, is arrange | positioned at the hybrid vehicle 21 as follows.
[0031]
That is, the indoor heat exchanger 39, the heater core 40, and the blower 41 (rotated and driven by a motor) of the vehicle air conditioner are disposed in the front portion of the vehicle compartment 42. The outdoor heat exchanger 43 and the blower 44 (rotated by the motor 44a) of the vehicle air conditioner are arranged along the rear side of the vehicle side surface. Therefore, the air blown to the outdoor heat exchanger 43 by the blower 44 is discharged outside the vehicle from the exhaust hole 45 provided at the rear side of the vehicle. The compressor 46 of the vehicle air conditioner is disposed in the vicinity of the engine 32 and is selectively driven to rotate by the engine 32 or the compressor motor 47.
[0032]
An engine radiator 49 is disposed at the rear of the vehicle, and a blower 50 (rotated and driven by a motor 50a) is disposed adjacent to the engine radiator 49. An electric equipment radiator 51 and a battery radiator 52 are disposed adjacent to each other at the front of the vehicle, and a blower 53 (rotated and driven by a motor 53a) is disposed adjacent to the battery radiator 52. An intake hole 76 is provided at the front end of the vehicle, and a shutter 54 that is opened and closed by a motor 55 is provided at the rear end of the vehicle.
[0033]
Next, the system configuration of the thermal system will be described with reference to FIG. In FIG. 2, a thick line indicates a refrigerant circulation circuit (refrigerant circuit), and a thin line indicates a cooling water (long life coolant (LLC) or the like) circulation circuit (cooling water circuit).
[0034]
The refrigerant circuit A of the vehicle air conditioner functions as a heat pump, and the cooling operation and the heating operation are performed by switching the refrigerant flow path by the four-way valve 61. A detailed description of the refrigerant circuit A will be described later.
[0035]
As the coolant circuit, an engine coolant circuit B, a battery coolant circuit C, and an electrical equipment coolant circuit D are provided.
[0036]
Among these, in the engine cooling water circuit B, the engine cooling water is circulated mainly between the engine 32 and the engine radiator 49 by the pump 64, and a part of the engine cooling water is used for the vehicle via the throttle valve 65. It also flows to the heater core 40 of the air conditioner and also flows to the battery warm-up heat exchanger 67 via the throttle valve 66. In the passage from the engine 32 to the engine radiator 49, another throttle valve 75 that bypasses the throttle valve 66 and the battery warm-up heat exchanger 67 is provided. By adjusting the flow rate between them, it is possible to adjust the heat release in the heat exchanger 67 for warming up the battery.
[0037]
In the battery cooling water circuit C, the flow of the battery cooling water is switched between when the battery 34 is cooled and when the battery 34 is warmed up. That is, when the battery 34 is cooled, the throttle valve 68 that bypasses the battery radiator 52 is closed and the throttle valve 69 is opened, and the pump 70 supplies battery cooling water between the battery 34 and the battery radiator 52. Circulate with. At this time, the throttle valve 66 is closed so that the engine coolant does not flow to the battery warm-up heat exchanger 67. On the other hand, when warming up the battery 34, the throttle valve 66 is opened so that the engine coolant flows to the battery warm-up heat exchanger 67, the throttle valve 68 is opened, and the throttle valve 69 is closed. The battery cooling water bypasses the battery radiator 52 and is circulated between the battery 34 and the battery warming heat exchanger 67 by the pump 70.
[0038]
In the electrical equipment coolant circuit D, the electrical equipment coolant is circulated between the various electrical equipment (drive unit or the like) 71 and the electrical equipment radiator 51 by the pump 72.
[0039]
Thus, in the vehicle air conditioner, cooling and heating by the indoor heat exchanger 39 (refrigerant circuit A) and heating by engine cooling water (heater core 40) are performed, and in the engine cooling water circuit B, engine cooling by engine cooling water is performed. In the battery cooling water circuit C, battery cooling by battery cooling water and battery warm-up by engine cooling water are performed, and in the electric equipment cooling water circuit D, electric equipment cooling by electric equipment cooling water is performed.
[0040]
Note that reference numeral 74 in FIG. 2 denotes a switching damper that is rotated by a motor or the like (not shown). The switching damper 74 switches the air suction direction by the blower 44 of the vehicle air conditioner. That is, during the cooling operation, the switching damper 74 is rotated to the side a in FIG. 2, and the outside air is directly sucked by the blower 44 and discharged from the exhaust hole 45 to the outside of the vehicle. On the other hand, during the heating operation, the switching damper 74 is rotated to the b side in FIG. 2 to effectively use the exhaust heat of the engine 32, the battery 34, etc. to assist the heating capability in winter, and the engine 32 (engine Air warmed by exhaust heat from the radiator 49) and the battery 34 is sucked by the blower 44 and discharged from the exhaust hole 45 to the outside of the vehicle. Further, reference numeral 73 in FIG. 2 denotes a switching damper that switches between introduction of outside air and circulation of inside air, and is rotated by a motor or the like (not shown).
[0041]
Here, based on FIG. 3, the structure of the refrigerant circuit A is demonstrated in detail.
[0042]
As shown in FIG. 3, the refrigerant circuit A is provided with a four-way valve 61, and the cooling operation or the heating operation is performed by switching the refrigerant flow path by the four-way valve 61. That is, during the cooling operation, the refrigerant flows in the order of the compressor 46, the four-way valve 61, the outdoor heat exchanger 43, the expansion valve (throttle valve) 62, the indoor heat exchanger 39, the four-way valve 61, the accumulator 63, and the compressor 46. At this time, the indoor heat exchanger 39 serves as a heat absorber (evaporator), the outdoor heat exchanger 43 serves as a radiator (condenser), and the interior of the passenger compartment 42 is cooled. On the other hand, during the heating operation, the refrigerant flows in the order of the compressor 46, the four-way valve 61, the indoor heat exchanger 39, the expansion valve 62, the outdoor heat exchanger 43, the four-way valve 61, the accumulator 63, and the compressor 46. At this time, the outdoor heat exchanger 43 serves as a heat absorber (evaporator), and the indoor heat exchanger 39 serves as a radiator (condenser), thereby heating the interior of the vehicle interior 42. FIG. 4 is a diagram showing a characteristic example of the refrigerant circuit A.
[0043]
A check valve 75 is provided on the discharge side of the compressor 46. An oil separator 76 is provided between the compressor 46 and the check valve 75, and the oil separator 76 and the suction side of the compressor 46 are connected by a capillary tube (capillary tube) 77. That is, one end of the capillary tube 77 is connected to the oil separator 77, and the other end is connected to the suction side (pipe 79) of the compressor 46.
[0044]
Thus, during operation, the mixed fluid of the refrigerant and oil discharged from the compressor 46 is separated into the refrigerant and oil by the oil separator 76, and the refrigerant passes through the four-way valve 61 and the indoor heat exchanger 39 or the outdoor heat. While being sent to the exchanger 43, the oil is returned to the suction side of the compressor 46 by the capillary tube 77, and when stopped, the refrigerant between the compressor 46 and the check valve 75 is sucked into the compressor 46 through the capillary tube 77 together with the oil. Returning to the side, the discharge side and the suction side of the compressor 46 are equalized.
[0045]
The oil separator generally opens and closes the oil return when the oil level in the oil separator decreases by opening and closing an oil return pipe provided in the oil separator based on a detection signal of a liquid level detection device such as a float switch. Gas (refrigerant) is prevented from blowing through the tube. Specifically, a float type on-off valve in which a float switch and an on-off valve are integrated is often used. However, when a float type on-off valve is used, the refrigerant is bypassed at the time of stopping to equalize the discharge side and the suction side of the compressor, and the refrigerant is prevented from blowing through at the same time. It cannot be satisfied.
[0046]
Therefore, in order to satisfy both the pressure equalization at the time of stopping and the prevention of refrigerant blow-off during operation, an on-off valve 100 represented by an electromagnetic valve is provided in series with the capillary tube 77 as shown in FIG. The on / off valve 100 may be controlled to be opened / closed by the control device 101.
[0047]
That is, during operation, the on-off valve 100 is opened and closed based on the detection signal of the liquid level detector 102 that detects the liquid level of the oil separator 76. Specifically, the opening / closing valve 100 is opened when the liquid level in the oil separator 76 is higher than a predetermined value, and the opening / closing valve 100 is closed when the liquid level in the oil separator 76 falls below a predetermined value. Prevents refrigerant from blowing through. When stopping, the on-off valve 100 is opened regardless of the liquid level in the oil separator 76.
[0048]
However, when the pressure equalization at the stop is mainly considered, the capillary tube 77 has a very large gas flow resistance and a very small liquid flow resistance. Is sacrificed, the on-off valve 100 is unnecessary.
[0049]
On the other hand, in order to satisfy both the pressure equalization at the time of stop and the prevention of refrigerant blow-off at the time of operation, the on-off valve 100 is provided as described above, and the controller 101 controls the liquid level detection device 102 at the time of operation. Based on the detection signal, the on-off valve 100 is opened and closed, and at the time of stop, the on-off valve 100 is controlled to open regardless of the liquid level in the oil separator 76. Liquid level detection devices include those that directly detect the liquid level with a float switch, ultrasonic waves, etc., and the fluid state (gas or oil) in the oil return pipe (capillary tube in this case) indirectly depending on the temperature. There is something to distinguish.
[0050]
As shown in FIG. 3, the expansion valve 62 is provided in the flow path between the indoor heat exchanger 39 and the indoor heat exchanger 43. The expansion valve 62 is an electric type (EEV), and the needle at the tip is moved by rotating a shaft by a stepping motor so that the flow path can be opened and closed instantaneously. When the cooling operation is performed, the flow path is throttled at an opening degree appropriately adjusted so that the degree of superheating is constant according to the evaporation pressure and the evaporator outlet temperature at each time, and when the compressor 46 is stopped during the heating operation or the cooling operation, for example, Based on a control signal (compressor stop command signal) from the control device 101 shown in FIG. 5, the valve is instantly closed and the flow path between the indoor heat exchanger 39 and the outdoor heat exchanger 43 is instantaneously shut off. Can do.
[0051]
That is, the expansion valve 62 functions as a throttle mechanism for reducing the pressure of the refrigerant, and a flow path between the indoor heat exchanger 39 and the outdoor heat exchanger 43 when the compressor 46 is stopped during heating operation or cooling operation. Is instantaneously shut off from the high-pressure side indoor heat exchanger 39 or the outdoor heat exchanger 43 functioning as a condenser to the low-pressure side outdoor heat exchanger 43 or the indoor heat exchanger 39 functioning as an evaporator. It also has the function of preventing liquid refrigerant from flowing in.
[0052]
Instead of the expansion valve 62, a capillary tube and an opening / closing valve may be provided. For example, as indicated by a one-dot chain line in FIG. 3, a capillary tube 82 as a throttle mechanism and an electromagnetic valve 81 as an on-off valve may be provided in series instead of the expansion valve 62. The solenoid valve 81 is opened during operation, and the solenoid valve 81 is closed based on the stop command signal when stopped. That is, the expansion valve (EEV) 62 can be freely controlled to open and close, but the temperature-type or fixed-throttle type (capillary tube) expansion valve cannot be opened or closed essentially or cannot be opened or closed instantaneously. Therefore, this is supplemented by a solenoid valve.
[0053]
Further, as shown in FIG. 3, the accumulator 63 provided on the suction side of the compressor 46 is not a U-tube type as in the prior art, but ends 79a and 80a of pipes 79 and 80 connected to the accumulator 63. Are located in the upper part of the accumulator 63 (upper part of the gas phase part 63a). The bottom portion of the accumulator 63 (the bottom portion of the liquid phase portion 63 b) and the suction side (pipe 79) of the compressor 46 are connected by a capillary tube 78.
[0054]
<Action and effect>
According to the refrigerant circuit A having the above configuration, the mixed fluid of the refrigerant and oil discharged from the compressor 46 during the heating operation or the cooling operation is separated into the refrigerant and the oil in the oil separator 76, and the refrigerant passes through the four-way valve 61. The oil is sent to the indoor heat exchanger 39 or the outdoor heat exchanger 43, while the oil is returned to the suction side of the compressor 46 by the capillary tube 77.
[0055]
And, for example, when the compressor 46 is temporarily stopped to switch the drive means of the compressor 46 from the compressor motor 47 to the engine 32 as the travel drive means of the hybrid vehicle 31 is switched from the drive unit 33 to the engine 32. The refrigerant between the compressor 46 and the check valve 75 flows together with oil to the suction side of the compressor 46 through the capillary tube 77, and the check valve 75 causes the high pressure side (the indoor heat exchanger 39 side or the side of the refrigerant circuit A). In order to prevent the refrigerant on the outdoor heat exchanger 43 side) from flowing to the discharge side of the compressor 46, the discharge side and the suction side of the compressor 46 are equalized in a short time.
[0056]
For this reason, the compressor 46 can be restarted immediately even if the whole refrigerant circuit A is not equalized. Accordingly, even if the drive unit 33 and the engine 32 are frequently switched and the compressor 16 is frequently started and stopped, there is no particular inconvenience and appropriate air conditioning can be performed.
[0057]
Further, by providing the oil separator 76, only the oil can be returned from the discharge side of the compressor 46 to the suction side by the capillary tube 77 during operation. That is, the oil separator 76 is not provided, and the discharge side and the suction side of the compressor 46 are shortened similarly to the above even if the compressor 46 and the check valve 75 are simply connected to the suction side of the compressor 46 by the capillary tube 77. Although the pressure can be equalized over time, in this case, a part of the refrigerant together with the oil returns to the suction side of the compressor 46 through the capillary tube 77 during operation. ) Will decrease. On the other hand, if the oil separator 76 is provided as described above and one end of the capillary tube 77 is connected to the oil separator 76, only oil can be returned to the suction side of the compressor 46, so that COP is improved.
[0058]
In addition, since the oil return circuit of the oil separator 76 used here is not premised on opening / closing control depending on the amount of oil, depending on the operating conditions, there is a case where the oil runs out and gas (refrigerant) blows out. However, in the most part of the operating range, the oil separator 76 is designed to be operated in a range where the oil does not become full. Further, since the refrigerant and the oil are separated by the oil separator 76, the heat transfer coefficient on the refrigerant side in the indoor heat exchanger 39 and the outdoor heat exchanger 43 is increased, and the pressure loss in the flow path is also reduced. The COP of the refrigerant circuit A can be improved. That is, the pressure equalization between the discharge side and the suction side of the compressor 46 can be performed in a short time, and the COP of the refrigerant circuit A can be improved.
[0059]
As shown in FIG. 6, the oil separator 76 may not be provided, and the opening / closing valve 100 may be connected in series to the capillary tube 77 and the opening / closing valve 100 may be controlled to open / close by the control device 101. In this case, the control device 101 performs control so that the on-off valve 100 is closed during operation and the on-off valve 100 is opened when stopped. This makes it possible to satisfy both the pressure equalization at the time of stopping and the prevention of refrigerant blow-off during operation.
[0060]
However, from the viewpoint of improving COP, it is preferable to provide the oil separator 46 as described above, and it is also preferable to provide the on-off valve 100. That is, by providing the oil separator 46, the oil and the refrigerant can be separated, and by providing the on-off valve 100, it is possible to satisfy both the pressure equalization at the time of stopping and the prevention of the blow-through of the refrigerant at the time of operation. Therefore, COP can be further improved.
[0061]
Further, according to the refrigerant circuit A having the above configuration, when the compressor 46 is stopped, the flow path between the indoor heat exchanger 39 and the outdoor heat exchanger 43 is instantaneously blocked by the expansion valve 62 or the electromagnetic valve 81. Thus, the liquid refrigerant can be prevented from flowing from the high-pressure side indoor heat exchanger 39 or the outdoor heat exchanger 43 into the low-pressure side outdoor heat exchanger 43 or the indoor heat exchanger 39. For this reason, even if the start / stop of the compressor 46 is repeated, the oil in the compressor 46 can be prevented from being diluted by the liquid refrigerant. Moreover, since there is not much difference in refrigerant distribution between when the compressor 46 is in operation and when it is stopped, the rise when the compressor 46 is started up is quick. That is, the compressor 46 is stabilized in a short time after restarting (the refrigerant distribution is restored to the state before the stop in a short time).
[0062]
Further, the end portions 79a and 80a of the pipes 79 and 80 connected to the accumulator 63 are positioned at the upper portion of the accumulator 63, and the bottom portion of the accumulator 63 and the suction side of the compressor 46 are connected by the capillary tube 78. The oil in the liquid phase portion 63b is supplied to the compressor 46 through the capillary tube 78, and even if the accumulator 46 accumulates a large amount of liquid refrigerant by frequently starting and stopping the compressor 46, The liquid refrigerant can be prevented from being sucked into the compressor 46, and the oil in the compressor 46 can be prevented from being diluted. This is particularly effective when there is no blocking means (expansion valve (EEV) 62 or electromagnetic valve 81) that instantaneously blocks the flow path between the indoor heat exchanger 39 and the outdoor heat exchanger 43. Further, although the required amount of refrigerant differs between the cooling operation and the heating operation, this excess refrigerant can be easily stored in the accumulator 63.
[0063]
The present invention is particularly useful when applied to a refrigerant circuit of a vehicle air conditioner for a hybrid vehicle. However, the present invention is not necessarily limited thereto, and may be applied to a refrigerant circuit of another air conditioner. it can.
[0064]
【The invention's effect】
  As specifically described above with the embodiment of the invention,The present inventionThe refrigerant circuit of the air conditioner sends out the refrigerant compressed by the compressor from the discharge side of the compressor to the outdoor heat exchanger or the indoor heat exchanger, and again from the indoor heat exchanger or the outdoor heat exchanger to the compressor. In the refrigerant circuit of the air conditioner configured to return to the suction side, a check valve is provided on the discharge side of the compressor, and a capillary tube is provided between the check valve and the compressor and the suction side of the compressor. Connected andAn open / close valve is provided in series with the capillary tube, and an oil separator provided with a liquid level detecting means is provided between the compressor and the check valve, and one end of the capillary tube is connected to the oil separator. In addition, a control device for controlling the opening / closing of the on-off valve is provided, and the control device controls the liquid level based on a detection signal from a liquid level detection means for detecting the liquid level of the oil separator during operation of the oil separator. The on-off valve is opened when the value is equal to or greater than the value, and the on-off valve is closed when the liquid level is lower than the predetermined value to prevent the refrigerant from being blown out. WasIt is characterized by that.
[0065]
  Therefore,BookAccording to the refrigerant circuit of the air conditioner of the invention, when the compressor is stopped, the refrigerant between the compressor and the check valve flows along with the oil to the intake side of the compressor through the capillary tube, and the high pressure of the refrigerant circuit by the check valve. In order to prevent the refrigerant on the side (indoor heat exchanger side or outdoor heat exchanger side) from flowing to the discharge side of the compressor, the pressure on the discharge side and the suction side of the compressor is equalized in a short time. For this reason, the compressor can be restarted immediately, and even if the start / stop of the compressor is frequently repeated, there is no particular inconvenience and appropriate air conditioning can be performed.
[0071]
  Also bookAccording to the refrigerant circuit of the air conditioner of the invention, oil and refrigerant can be separated by providing an oil separator, and pressure equalization at the time of stop and prevention of refrigerant blow-off during operation by providing an on-off valve Therefore, COP can be further improved.
[Brief description of the drawings]
FIG. 1 is a plan view showing a layout relating to a thermal system of a hybrid vehicle including a refrigerant circuit of a vehicle air conditioner according to an embodiment of the present invention.
FIG. 2 is a system diagram of the thermal system.
FIG. 3 is a configuration diagram showing the refrigerant circuit extracted.
FIG. 4 is a diagram showing a characteristic example of the refrigerant circuit.
FIG. 5 is a main part configuration diagram showing another configuration example of the refrigerant circuit;
FIG. 6 is a main part configuration diagram showing another configuration example of the refrigerant circuit.
FIG. 7 is an explanatory diagram showing an example of a configuration of a main part of a conventional vehicle air conditioner provided in a hybrid vehicle.
FIG. 8 is a configuration diagram showing an example of a refrigerant circuit of the vehicle air conditioner.
FIG. 9 is a structural diagram showing a general example of a conventional accumulator.
[Explanation of symbols]
31 Hybrid vehicle
32 drive units
33 engine
39 Indoor heat exchanger
43 Outdoor heat exchanger
46 Compressor
47 Compressor motor
61 Four-way valve
62 Expansion valve
63 Accumulator
75 Check valve
76 Oil separator
77, 78, 82 Capillary tube
79,80 piping
79a, 80a End of piping
81 Solenoid valve
100 Solenoid valve
101 Control device
102 Liquid level detection device
A refrigerant circuit

Claims (1)

The refrigerant compressed by the compressor is sent from the discharge side of the compressor to the outdoor heat exchanger or the indoor heat exchanger, and again returned from the indoor heat exchanger or the outdoor heat exchanger to the suction side of the compressor. In the refrigerant circuit of the air conditioner,
A check valve is provided on the discharge side of the compressor, and a capillary tube is connected between the check valve and the compressor and the suction side of the compressor.
An open / close valve is provided in series with the capillary tube, and an oil separator provided with a liquid level detecting means is provided between the compressor and the check valve, and one end of the capillary tube is connected to the oil separator. together, to provide a control device for the opening and closing control of the on-off valve, this control device, at the time of the oil separator operation based on a detection signal of the liquid level detecting means for detecting the liquid level of the oil separator, the liquid surface is given The on-off valve is opened when the value is equal to or greater than the value, and the on-off valve is closed when the liquid level is lower than the predetermined value to prevent the refrigerant from being blown out. The refrigerant circuit of the air conditioner characterized by having made it.

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