Vehicular air conditioner

Abstract

To provide a vehicular air conditioner that is configured to enable a compressor to be activated normally, without coagulation of lubricant in the compressor, even under an extremely low outdoor temperature environment.SOLUTION: A vehicular air conditioner according to the present invention comprises; a refrigerant circuit including a compressor, an indoor heat exchange part and an external heat exchange part; an air conditioning unit in which the indoor heat exchange part is arranged; and a control device that controls the refrigerant circuit and the air conditioning unit. The vehicular air conditioner further comprises a lubricant temperature estimating part that estimates a temperature of lubricant in the compressor when the compressor stops. When the lubricant temperature estimating part determines that the temperature of the lubricant is a specified value or lower, the vehicular air conditioner executes a lubricant heating mode of heating the lubricant in the compressor.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an air conditioner for a vehicle. [Background technology]

[0002] 2. Description of the Related Art Air conditioners that use a heat pump (refrigerant circuit) as a heat source are known as air conditioners for electric vehicles (EVs) that do not have a combustion-based heat source such as an engine or for vehicles that have a small amount of heat from a combustion-based heat source.

[0003] In general, air conditioners using heat pumps operate their external heat exchanger as a heat sink during heating operation, obtaining heat from the outside air. Therefore, when the outside temperature becomes extremely low (for example, below -40°C), it becomes difficult to absorb heat from the outside air, and the heating capacity drops significantly.

[0004] In such an extremely low outside air temperature environment, it is common to secure a heat source using an electric heater such as a PTC heater, etc. However, the use of such a heat source increases battery consumption, which may adversely affect the driving range of an electric vehicle, and the installation of a PTC heater increases the manufacturing cost of the air conditioner.

[0005] On the other hand, hot gas heating, which uses high-temperature, high-pressure refrigerant discharged from the compressor of the refrigerant circuit, is a heating method that does not absorb heat and is expected to be effective in extremely low-temperature environments. This hot gas heating system makes the interior heat exchanger of the vehicle air conditioner function as a radiator (interior condenser), into which the high-temperature, high-pressure refrigerant discharged from the compressor flows directly, and after reducing the pressure of the refrigerant that leaves the radiator, it returns it to the compressor via an accumulator without passing through an external heat exchanger (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2014-196017 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in an extremely low outside temperature environment (for example, below -40°C), even if the vehicle air conditioning system performs any of the heating operations described above, if the compressor is then stopped by parking the vehicle, etc., the lubricating oil in the compressor will cool and become more viscous, and the solidified lubricating oil will adhere to various parts inside the compressor. This may cause torque abnormalities, etc., the next time the compressor is started, resulting in a startup failure.

[0008] The present invention has been made in consideration of the above circumstances, and has an object to provide a vehicle air conditioning system that is capable of starting the compressor in a normal state without the lubricating oil in the compressor solidifying, even in an extremely low outside air temperature environment. [Means for solving the problem]

[0009] The vehicle air conditioning system of the present invention is equipped with a refrigerant circuit including a compressor, an indoor heat exchange unit, and an external heat exchange unit, an air conditioning unit having the indoor heat exchange unit disposed therein, and a control device that controls the refrigerant circuit and the air conditioning unit, and is characterized in that it has a lubricant oil temperature estimation unit that estimates the temperature of the lubricant oil in the compressor when the compressor is stopped, and when the lubricant oil temperature estimation unit determines that the temperature of the lubricant oil is below a specified value, it executes a lubricant oil heating mode to heat the lubricant oil in the compressor. Effect of the Invention

[0010] According to the present invention, it is possible to provide a vehicle air conditioner that can start the compressor in a normal state without the lubricating oil in the compressor solidifying, even in an extremely low outside air temperature environment. [Brief description of the drawings]

[0011] [Figure 1]1 is an explanatory diagram showing an example of a system configuration of a vehicle air conditioner according to an embodiment of the present invention; [Diagram 2] 1 is an explanatory diagram illustrating an example of a control device for a vehicle air conditioner according to an embodiment of the present invention; [Diagram 3] 4 is a flowchart for explaining an execution control process of a lubricant oil heating mode of the vehicle air conditioner according to the present embodiment. [Figure 4] 4 is a flowchart for illustrating a lubricant oil heating mode (first example) of the vehicle air conditioner according to the present embodiment. [Diagram 5] FIG. 11 is an explanatory diagram for explaining a circuit operation in a chiller refrigerant recovery operation in a lubricant oil heating mode (first example). [Figure 6] FIG. 4 is an explanatory diagram for explaining a circuit operation in an external heat exchanger refrigerant recovery operation in a lubricant oil heating mode (first example). [Figure 7] FIG. 4 is an explanatory diagram for explaining a circuit operation in a bypass operation mode in a lubricant oil heating mode (first example). [Figure 8] 5 is a flowchart for illustrating a lubricant oil heating mode (second example) of the vehicle air conditioner according to the present embodiment. [Figure 9] 5 is a flowchart for illustrating a lubricant oil heating mode (third example) of the vehicle air conditioner according to the present embodiment. [Figure 10] FIG. 13 is an explanatory diagram for explaining a circuit operation in an oil heating mode (third example). [Figure 11] 6 is a flowchart for illustrating a lubricant oil heating mode (fourth example) of the vehicle air conditioner according to the present embodiment. [Figure 12] 10 is a flowchart for illustrating a lubricant oil heating mode (fifth example) of the vehicle air conditioner according to the present embodiment. [Figure 13] FIG. 13 is an explanatory diagram for explaining a circuit operation in an oil heating mode (fifth example). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same reference numerals denote parts having the same functions, and duplicated descriptions in each drawing will be omitted as appropriate.

[0013] [System Configuration] As shown in Fig. 1, the vehicle air conditioner 1 includes a refrigerant circuit 10 and an air conditioning unit 20. The refrigerant circuit 10 includes a compressor 2, indoor heat exchangers 21, 22 (indoor heat exchange section) arranged inside the air conditioning unit 20, and an external heat exchanger 11 (external heat exchange section) provided outside the vehicle compartment, which are arranged along a refrigerant flow path. The indoor heat exchangers 21, 22 are provided for heat exchange between the refrigerant and air flowing through an air flow passage 26 of the air conditioning unit 20. The external heat exchanger 11 is provided for heat exchange between the outside air and the refrigerant outside the vehicle compartment.

[0014] The compressor 2 of the refrigerant circuit 10 compresses and circulates the refrigerant. The refrigerant compressed by the compressor 2 is reduced in pressure to a required level by passing through a first pressure reduction section V1, a second pressure reduction section V2, a third pressure reduction section V3, and a fourth pressure reduction section V4, which are, for example, expansion valves, in an appropriately selected refrigerant flow path. The refrigerant circuit 10 is provided with flow path switching valves 12 and 13 for switching the refrigerant flow path, and also with check valves 14 and 15 for regulating the flow direction of the refrigerant. An accumulator 16 is provided immediately upstream of the compressor 2 in the refrigerant circuit 10 to recover liquid refrigerant and separate the refrigerant into gas and liquid.

[0015] As described above, the air conditioning unit 20 includes the indoor heat exchangers 21 and 22, and the air introduced from the inside or outside of the room by the blower 23 selectively passes through the indoor heat exchangers 21 and 22 and is blown into the room. The air conditioning unit 20 includes an air damper 24 in an air flow passage 26. As shown in FIG. 1, when the air damper 24 is fully open, the air introduced by the blower 23 passes through both the indoor heat exchangers 21 and 22 and is blown into the room, and when the air damper 24 is fully closed (not shown), the air introduced by the blower 23 passes only through the indoor heat exchanger 22 and is blown into the room. Another air damper 25 provided in the air conditioning unit 20 switches the air introduced into the blower 23 between the inside and outside of the room, and selectively closes an air inlet 25A connected to the outside and an air inlet 25B connected to the inside of the room.

[0016] Although the above-mentioned external heat exchanger 11 and indoor heat exchangers 21, 22 are described as examples in which the refrigerant and air directly exchange heat, the refrigerant and air may indirectly exchange heat via a heat medium that has exchanged heat with the refrigerant. That is, the refrigerant may absorb heat from the air via the heat medium, or the refrigerant may dissipate heat to the air via the heat medium.

[0017] The vehicle air conditioner 1 also includes a heat medium circuit 30. The heat medium circuit 30 operates a circulation pump 31 to circulate the heat medium in a heat medium flow path (heat medium piping) C1, heats the heat medium in a heater (ECH: Electric Coolant Heater) 32, and recovers waste heat from a temperature control object such as a battery in a temperature control object heat exchanger 33. The refrigerant circuit 10 and the heat medium circuit 30 are also provided with a refrigerant-heat medium heat exchanger (chiller heat exchanger) 34 that exchanges heat between the refrigerant and the heat medium in a flow path 34A through which the refrigerant flows and a flow path 34B through which the heat medium flows.

[0018] As shown in PTS 42, 43 in FIG. 1, the refrigerant circuit 10 is provided with a refrigerant temperature sensor 42 (FIG. 2) that detects the refrigerant temperature on the side sucked into the compressor 2, and a refrigerant pressure sensor 43 (FIG. 2) that detects the refrigerant pressure on the side sucked into the compressor 2.

[0019] [Control device] The vehicle air conditioner 1 includes a control device (air conditioning controller) 100 shown in Fig. 2. The control device 100 controls the refrigerant circuit 10, the air conditioning unit 20, and the heat medium circuit 30 based on various input signals G (air conditioning instruction signals, charger connection signals, etc.) and detection signals from a sensor section 40.

[0020] The sensor unit 40, which inputs detection signals to the control device 100, includes, for example, an outside air temperature sensor 41 that detects the outside air temperature, a refrigerant temperature sensor 42 that detects the refrigerant temperature in the refrigerant circuit 10, and a refrigerant pressure sensor 43 that detects the refrigerant pressure in the refrigerant circuit 10. The sensor unit 40 also includes various other sensors (not shown) that detect information required when the control device 100 performs various controls.

[0021] 2, the control device 100 controls the compressor 2, the first pressure reduction section V1, the second pressure reduction section V2, the third pressure reduction section V3, the fourth pressure reduction section V4, and the flow path switching valves 12, 13, etc. in the refrigerant circuit 10, controls the blower 23, the air dampers 24, 25, etc. in the air conditioning unit 20, and controls the circulation pump 31, etc. in the heat medium circuit 30. The control device 100 also controls the vehicle air conditioner 1 according to the processing result of the control device 100.

[0022] [Outdoor air heat absorption heating operation] The vehicle air conditioner 1 can perform an outside air heat absorption heating operation in which heat is absorbed from outside air under the control of the control device (air conditioning controller) 100. In Fig. 1, in the outside air heat absorption heating operation, under the control of the control device 100, the flow path switching valve 12 is controlled to be closed and the flow path switching valve 13 is controlled to be open, the first pressure reduction section V1 is controlled to an appropriate opening degree, the second pressure reduction section V2, the third pressure reduction section V3, and the fourth pressure reduction section V4 are controlled to be fully closed, and the grill shutter (not shown) provided in the external heat exchanger 11 is controlled to be in an open state.

[0023] As a result, when the refrigerant circulating through the refrigerant circuit 10 is discharged from the compressor 2, it flows through the refrigerant pipes R1 and R2, passes through the indoor heat exchanger 21, enters the refrigerant pipe R3 into the refrigerant pipe R5, and passes through the first pressure reducing section V1 into the external heat exchanger 11. The refrigerant that has exchanged heat with the outside air (air) in the external heat exchanger 11 enters the refrigerant pipe R6 into the refrigerant pipe R7, passes through the flow path switching valve 13 and the check valve 14, and then enters the accumulator 16 from the refrigerant pipe R10. Then, the refrigerant that has been separated into gas and liquid in the accumulator 16 returns from the refrigerant pipe R1 to the compressor 2. Therefore, in this external heat absorption heating operation, the inflow of refrigerant into the chiller heat exchanger 34 is blocked.

[0024] In this outside air heat absorption heating operation, high-temperature, high-pressure refrigerant compressed by the compressor 2 is sent to the indoor heat exchanger 21 in the air conditioning unit 20, which functions as a radiator, and air taken into the air conditioning unit 20 from the air inlet 25B by the drive of the blower 23 is heated as it passes through the indoor heat exchanger 21 and is blown out into the vehicle cabin. At this time, the air inlet 25A of the air conditioning unit 20 is closed by the air damper 25, and the air damper 24 in the air flow passage 26 opens only the flow path of air heading toward the indoor heat exchanger 21.

[0025] [Hot gas heating operation] The vehicle air conditioner 1 can also perform hot gas heating operation under the control of the control device (air conditioning controller) 100. This hot gas heating operation heats the vehicle interior by dissipating heat from a part or all of the refrigerant compressed by the compressor 2 in the indoor heat exchanger 21 without causing the refrigerant to absorb heat in the external heat exchanger 11.

[0026] In Fig. 1, in hot gas heating operation, the flow path switching valve 12 is controlled to be open and the third pressure reduction section V3 is controlled to an appropriate opening degree under the control of the control device 100. Also, under the control of the control device 100, the flow path switching valve 13 is controlled to be closed and the first pressure reduction section V1 is controlled to be fully closed, so that no refrigerant flows to the external heat exchanger 11. Also, under the control of the control device 100, the fourth pressure reduction section V4 is controlled to be fully closed, so that no refrigerant flows to the indoor heat exchanger 22.

[0027] In this hot gas heating operation, under the control of the control device 100, the high-temperature, high-pressure refrigerant discharged from the compressor 2 flows through the refrigerant pipe R1, and part of it flows from the branch point P1 through the refrigerant pipe R2 and passes through the indoor heat exchanger 21, then from the refrigerant pipe R3 through the flow path switching valve 12 and flows through the refrigerant pipes R4 and R8, is depressurized in the third pressure reduction section V3 to become a low-pressure refrigerant, enters the flow path 34A of the chiller heat exchanger 34 from the refrigerant pipe R8, flows through the refrigerant pipes R9 and R10 and enters the accumulator 16, where gas-liquid separation occurs, and then returns from the refrigerant pipe R1 to the compressor 2.

[0028] In the vehicle air conditioner 1 performing the hot gas heating operation, the refrigerant circuit 10 has a hot gas bypass 10V (bypass path) that reduces the pressure of at least a portion of the refrigerant discharged from the compressor 2 without passing through (bypassing) the indoor heat exchanger 21 (indoor heat exchange section) and the external heat exchanger 11 (external heat exchange section) and flows it to the suction side of the compressor 2. In the hot gas bypass 10V, a portion of the high-temperature, high-pressure refrigerant is branched off at a branch point P1 immediately downstream of the compressor 2, reduced in pressure at a second pressure reduction section V2 (hot gas valve), and merged with the low-pressure refrigerant reduced in pressure at a third pressure reduction section V3 at a junction point P2 immediately upstream of the accumulator 16.

[0029] By providing such a hot gas bypass 10V, it becomes possible to mix the liquid refrigerant condensed by heat release in the indoor heat exchanger 21 with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant, which can then be returned to the compressor 2. In addition, by increasing the refrigerant flow rate flowing through the hot gas bypass 10V, it is possible to suppress the amount of heat release in the indoor heat exchanger 21, and by opening and closing the second pressure reduction section V2 (hot gas valve) under the control of the control device 100 to adjust the amount of refrigerant flowing through the hot gas bypass 10V, it is possible to maintain a balance between the amount of heat release in the refrigerant circuit 10 and the amount of heat input to the compressor 2.

[0030] During hot gas heating operation, the refrigerant flow in the flow path that passes through the indoor heat exchanger 21 is decompressed in the third decompression section V3, so that the refrigerant upstream of that becomes high-pressure refrigerant and the refrigerant downstream of that becomes low-pressure refrigerant. At this time, in order to maintain the heating capacity, heat exchange is not performed in the chiller heat exchanger 34 in the low-pressure side flow path. In the air conditioning unit 20, the air introduced by the blower 23 is heated by heat dissipation in the indoor heat exchanger 21 and is blown out into the vehicle cabin.

[0031] [Lubricant oil heating mode execution control process] Usually, in an extremely low outside air temperature (for example, -40°C or lower) environment, when the operation mode such as air conditioning is stopped due to stopping the vehicle or the like (i.e., the compressor 2 is stopped), the lubricant (oil) present in the compressor 2 increases in viscosity and solidifies, and the solidified lubricant adheres to various parts in the compressor 2, causing torque abnormalities and the like, which may result in a start failure. Therefore, in the vehicle air conditioner 1 of this embodiment, when the operation mode is stopped in such an extremely low outside air temperature environment (i.e., when the compressor 2 is stopped), a lubricant heating mode is executed based on the control of the control device (air conditioning controller) 100 to heat the lubricant in the compressor 2 to prevent it from solidifying. The execution control process of this lubricant heating mode (FIG. 3) will be described below.

[0032] When the control device (air conditioning controller) 100 starts the execution control process of the lubricant heating mode, in step S101, in order to determine whether it is necessary to execute the lubricant heating mode, the control device determines whether the environment in which the compressor 2 is currently stopped is below a preset extremely low outside temperature (below -40°C) based on the outside air temperature detected by the outside air temperature sensor 41.

[0033] When the control device 100 determines that the environment in which the compressor 2 is currently stopped is at this extremely low outside temperature (-40°C or lower) (YES in step S101), it proceeds to step S102 to further determine whether it is necessary to execute the lubricant oil heating mode, and when it determines that the environment in which the compressor 2 is currently stopped is not at this extremely low outside temperature (-40°C or lower) (NO in step S101), it determines that it is not necessary to execute the lubricant oil heating mode and ends the series of processes in Fig. 3. Note that although the extremely low outside temperature is set to -40°C or lower here, this temperature value is merely an example, and the extremely low outside temperature may be set to -35°C or lower, for example.

[0034] In step S102 following step S101, the control device (air conditioning controller) 100 estimates the temperature of the lubricant in the compressor 2 in order to estimate whether the state of the lubricant in the compressor 2 is about to change from a liquid to a solid state (a state about to solidify) or is already in a solid state (a solidified state), and determines whether the estimated temperature is equal to or lower than a preset specified value. The control device 100 that estimates the temperature of the lubricant in the compressor 2 constitutes a lubricant temperature estimation unit.

[0035] Here, the specified value may be, for example, a pour point that is 2.5°C higher than the freezing point of the lubricant in the compressor 2. In this case, when the temperature of the lubricant estimated by the control device 100 (lubricant temperature estimation unit) is higher than the freezing point but equal to or lower than the pour point, it may be estimated that the lubricant is already in a state where it is about to lose fluidity just before it becomes solid. Also, when the temperature of the lubricant estimated by the control device 100 (lubricant temperature estimation unit) is equal to or lower than the freezing point, it may be estimated that the lubricant is already in a solid state (solidified state). Note that the definition of the specified value is not limited to this, and may be a temperature that is a predetermined value (several degrees Celsius) higher than the freezing point.

[0036] When the control device 100 determines that the estimated temperature of the lubricating oil in the compressor 2 is equal to or lower than a specified value, thereby determining that the lubricating oil is in a state where it is about to solidify or has already solidified (YES in step S102), the process proceeds to step S103 to heat the lubricating oil. On the other hand, when the control device 100 determines that the estimated temperature of the lubricating oil in the compressor 2 is not equal to or lower than a specified value (i.e., higher than the specified value), thereby determining that the lubricating oil is not yet in a state where it is about to solidify (NO in step S102), there is no need to heat the lubricating oil, and therefore the series of processes shown in FIG. 3 is terminated.

[0037] In this step S102, the control device 100 may estimate the temperature of the lubricating oil in the compressor 2 from at least one of the state of the refrigerant in the refrigerant circuit 10 and the outside air temperature detected by the outside air temperature sensor 41. Examples of the state of the refrigerant in the refrigerant circuit 10 may include at least one or both of the temperature of the refrigerant (refrigerant temperature) sucked into the compressor 2 detected by the refrigerant temperature sensor 42 and the refrigerant pressure from which the temperature of the refrigerant sucked into the compressor 2 can be estimated detected by the refrigerant pressure sensor 43 ("PTS 42, 43" in FIG. 1). Note that this example is not limited to this, and at least one of the refrigerant temperature sensor 42 and the refrigerant pressure sensor 43 may be provided at another location in the refrigerant circuit 10, and the control device 100 may estimate the temperature of the lubricating oil in the compressor 2 from at least one or both of the refrigerant temperature and the refrigerant pressure detected by the sensor.

[0038] Furthermore, without being limited to this example, the control device 100 may, for example, in step S102, estimate that the temperature of the lubricating oil in the compressor 2 is below a specified value by confirming that the outside air temperature detected by the outside air temperature sensor 41 in the previous step S101 is below a specific value (e.g., -45°C) within the extremely low outside air temperature (below -40°C).

[0039] Alternatively, the control device 100 may estimate that the temperature of the lubricating oil in the compressor 2 is equal to or lower than a specified value by, for example, determining YES in step S101 (i.e., because the environment is an extremely low outside air temperature (−40° C. or lower)). In this case, after step S101, the control device 100 skips the process of step S102 and proceeds to step S103.

[0040] In step S103 following step S102, the control device 100 executes a lubricant heating mode for heating the lubricant in the compressor 2. After the process of step S103, the control device 100 ends the series of processes shown in Fig. 3. After ending the series of processes in Fig. 3, the control device 100 starts the series of processes in Fig. 3 at a predetermined time interval (for example, every few seconds or every few minutes). An example of the process of the lubricant heating mode in step S103 will be described below.

[0041] [Lubricant oil heating mode (first example)] The processing contents of the lubricant heating mode (step S103) of the first example will be described. In the lubricant heating mode of the first example, when the compressor 2 is operated to heat the lubricant in the compressor 2, a refrigerant recovery operation is performed in the refrigerant circuit 10, in which the refrigerant is passed through a heat exchange section through which the refrigerant was passed in the operation mode performed before the compressor 2 was stopped. The heat exchange section through which the refrigerant was passed in the operation mode performed before the compressor 2 was stopped is a location that is relatively easy to cool after the end of that operation mode, so that the refrigerant is likely to accumulate in the heat exchange section. Therefore, in this refrigerant recovery operation, the refrigerant estimated to have accumulated in the heat exchange section is recovered in the accumulator 16.

[0042] In addition, in the lubricant oil heating mode of the first example, the compressor 2 is operated in a bypass operation mode in which the refrigerant flows through the bypass path after the refrigerant is recovered. In the lubricant oil heating mode of the first example, heat exchange of the refrigerant is prohibited, and in the refrigerant recovery operation, the refrigerant discharged from the compressor 2 flows in the refrigerant circuit 10 without heat exchange and is recovered in the accumulator 16.

[0043] Specifically, in the lubricant oil heating mode of this first example, in step S201 shown in FIG. 4, the control device 100 determines whether the operating mode before the current lubricant oil heating mode was executed was also the lubricant oil heating mode (i.e., whether the refrigerant recovery operation has already been executed) and thereby determines whether the refrigerant that is estimated to have accumulated in the heat exchange section after the end of the operating mode that was executed before the compressor 2 was stopped has already been recovered in the accumulator 16 (the refrigerant has been recovered).

[0044] When the control device 100 determines that the refrigerant recovery operation has not yet been performed and thus determines that the refrigerant has not yet been recovered (NO in step S201), the control device 100 proceeds to step S202 in order to recover the refrigerant estimated to have accumulated in the heat exchange section in the accumulator 16 by heating the lubricating oil in the compressor 2 and causing the refrigerant to flow through the heat exchange section in the refrigerant circuit 10 through which the refrigerant passed in the operation mode performed before the compressor 2 was stopped, in the accumulator 16. On the other hand, when the control device 100 determines that the refrigerant recovery operation has already been performed and thus determines that the refrigerant has been recovered (YES in step S201), the control device 100 proceeds to step S206 in order to shorten as much as possible the refrigerant flow path through which the refrigerant flows when the compressor 2 is operating, in order to reduce the energy consumption required for heating the lubricating oil.

[0045] In step S202 following step S201, the control device 100 judges whether the operation mode performed before the compressor 2 was stopped was the outdoor air heat absorption heating operation. When the control device 100 judges that the operation mode performed before the compressor 2 was stopped was not the outdoor air heat absorption heating operation, and thus judges that the operation mode performed before the compressor 2 was stopped was the hot gas heating operation (NO in step S202), the control device 100 advances the process to step S203 in order to flow the refrigerant through the flow path 34A of the chiller heat exchanger 34, which is the heat exchanger through which the refrigerant passed in the hot gas heating operation. On the other hand, when the control device 100 judges that the operation mode performed before the compressor 2 was stopped was the outdoor air heat absorption heating operation (YES in step S202), the control device 100 advances the process to step S204 in order to flow the refrigerant through the external heat exchanger 11, which is the heat exchanger through which the refrigerant passed in the outdoor air heat absorption heating operation.

[0046] If the result of step S202 is NO, the control device 100 confirms that the circulating pump 31 of the heat medium circuit 30 is stopped in the subsequent step S203, thereby confirming that heat exchange between the refrigerant and the heat medium in the flow path 34B of the chiller heat exchanger 34 is prohibited. Then, the control device 100 operates the compressor 2 in the subsequent step S205 to perform chiller refrigerant recovery operation. Although not shown in FIG. 4, in this chiller refrigerant recovery operation, the control device 100 controls the flow path switching valve 12, the third pressure reduction section V3, the flow path switching valve 13, the first pressure reduction section V1, the fourth pressure reduction section V4, etc. to the same state as during the hot gas heating operation, which is the operation mode performed before the compressor 2 was stopped, and the second pressure reduction section V2 is controlled to be fully closed (the third pressure reduction section V3 may be controlled to be fully open). In addition, the control device 100 controls the heat medium circuit 30 and the air conditioning unit 20 to be in an inoperative state.

[0047] In this chiller refrigerant recovery operation, the lubricating oil in the compressor 2 is heated by heat (self-heating) due to friction and current flow in the compressor 2 by operating the compressor 2. At the same time, in this chiller refrigerant recovery operation, as shown by the thick black line in FIG. 5, the refrigerant is caused to flow through the flow path 34A of the chiller heat exchanger 34, which is a heat exchanger through which the refrigerant passed in the hot gas heating operation, which is the operation mode performed before the compressor 2 was stopped. It is estimated that the refrigerant accumulated in the flow path 34A of the chiller heat exchanger 34 after the hot gas heating operation, which is the operation mode performed before the compressor 2 was stopped, was ended. Therefore, in the chiller refrigerant recovery operation, the refrigerant is caused to flow through the flow path 34A of the chiller heat exchanger 34, and the refrigerant is recovered from the flow path 34A to the accumulator 16.

[0048] In addition, in the chiller refrigerant recovery operation, even if a small amount of lubricating oil mixed with the refrigerant is discharged from the compressor 2 in the hot gas heating operation, which is the operating mode that was performed before the compressor 2 was stopped, the chiller refrigerant recovery operation can recover the lubricating oil mixed with the refrigerant in the accumulator 16.

[0049] As shown in FIG. 5, the refrigerant discharged from the compressor 2 flows through refrigerant pipes R1 and R2 and passes through the indoor heat exchanger 21, then flows from refrigerant pipe R3 through flow path switching valve 12 to refrigerant pipes R4 and R8, passes through the third pressure reduction section V3, enters the flow path 34A of the chiller heat exchanger 34 from refrigerant pipe R8, and flows through refrigerant pipes R9 and R10 to be recovered in the accumulator 16.

[0050] If the answer is YES in step S202, the control device 100 closes the grill shutter (not shown) of the external heat exchanger 11 in step S204 to prohibit heat exchange between the refrigerant and the outside air. Then, the control device 100 operates the compressor 2 in step S205 to perform an external heat exchanger refrigerant recovery operation. Although not shown in FIG. 4, in this external heat exchanger refrigerant recovery operation, the control device 100 controls the flow path switching valve 12, the flow path switching valve 13, the first pressure reduction section V1, the third pressure reduction section V3, and the fourth pressure reduction section V4 to the same state as during the external heat absorption heating operation, which is the operation mode performed before the compressor 2 was stopped (the first pressure reduction section V1 may be controlled to be fully open). In addition, the control device 100 sets the heat medium circuit 30 and the air conditioning unit 20 to an inoperative state.

[0051] In this external heat exchanger refrigerant recovery operation, the compressor 2 is operated to heat the lubricating oil in the compressor 2 by heat generation (self-heating) due to friction and current flow in the compressor 2. At the same time, in this external heat exchanger refrigerant recovery operation, as shown by the thick black line in FIG. 6, the refrigerant is made to flow through the external heat exchanger 11, which is a heat exchanger through which the refrigerant passed in the outdoor air heat absorption heating operation, which is the operation mode performed before the compressor 2 was stopped. It is estimated that the refrigerant accumulated in the external heat exchanger 11 after the outdoor air heat absorption heating operation, which is the operation mode performed before the compressor 2 was stopped, was ended. Therefore, in the external heat exchanger refrigerant recovery operation, the refrigerant is made to flow through the external heat exchanger 11, and the refrigerant is recovered from the external heat exchanger 11 to the accumulator 16.

[0052] In addition, in the external heat exchanger refrigerant recovery operation, even if a small amount of lubricating oil mixed in the refrigerant is discharged from the compressor 2 in the external heat absorption heating operation, which is the operating mode performed before the compressor 2 is stopped, the lubricating oil mixed in the refrigerant can also be recovered in the accumulator 16 by this external heat exchanger refrigerant recovery operation.

[0053] As shown in FIG. 6, the refrigerant discharged from the compressor 2 flows through refrigerant pipes R1 and R2 and passes through the indoor heat exchanger 21, then flows through refrigerant pipe R3 and enters refrigerant pipe R5, passes through the first pressure reduction section V1 and then passes through the external heat exchanger 11 whose grill shutter is closed, and then enters refrigerant pipe R6 from refrigerant pipe R7, passes through the flow path switching valve 13 and the check valve 14, and is recovered from refrigerant pipe R10 to the accumulator 16.

[0054] In this way, in the refrigerant circuit 10, the control device 100 causes the refrigerant to flow (with heat exchange prohibited) through the heat exchange section through which the refrigerant passed in the operation mode performed before the compressor 2 was stopped, and after the refrigerant is recovered in the accumulator 16, operates the compressor 2 in a bypass operation mode in which all of the refrigerant discharged from the compressor 2 flows through the bypass path. That is, if the answer is YES in the above-mentioned step S201 (if the refrigerant has been recovered), in the subsequent step S206, the control device 100 operates the compressor 2 in the bypass operation mode in which the refrigerant flow path through which the refrigerant flows when the compressor 2 is operating is made as short as possible in order to reduce energy consumption for heating the lubricating oil.

[0055] In this bypass operation mode, the second pressure reducing section V2 is fully opened, the flow path switching valve 12 and the flow path switching valve 13 are closed, and the first pressure reducing section V1, the third pressure reducing section V3, and the fourth pressure reducing section V4 are fully closed under the control of the control device 100. As a result, in the bypass operation mode, the lubricating oil in the compressor 2 is heated by heat (self-heating) due to friction and current flow in the compressor 2 by operating the compressor 2, and at this time, as shown by the thick black line in Fig. 7, the refrigerant flows into the hot gas bypass 10V (bypass route) described above. That is, the refrigerant discharged from the compressor 2 passes through the second pressure reducing section V2 (hot gas valve) from the refrigerant pipes R1 and R11, passes through the accumulator 16 from the refrigerant pipe R10, and then returns to the compressor 2 from the refrigerant pipe R1.

[0056] In step S207 following step S205 or step S206, the control device 100 estimates the temperature of the lubricant in the compressor 2 in order to estimate whether the lubricant in the compressor 2 has become unsolidified, and determines whether the estimated temperature is higher than the specified value described in the previous step S102. Note that the estimation of the lubricant temperature in this step S207 may be performed in the same manner as in the above-mentioned step S102.

[0057] When the control device 100 determines that the estimated temperature of the lubricant in the compressor 2 is higher than a specified value, and thereby determines that the lubricant in the compressor 2 is not solidified (YES in step S207), the control device 100 proceeds to the process of step S208 to end the lubricant heating mode. On the other hand, when the control device 100 determines that the estimated temperature of the lubricant in the compressor 2 is not higher than a specified value (i.e., is equal to or lower than the specified value), and thereby determines that the lubricant in the compressor 2 is still in a state where it is likely to solidify or has solidified (NO in step S207), the control device 100 performs the process of step S207 again. That is, the process of step S207 is repeated until the control device 100 determines that the lubricant in the compressor 2 is not solidified.

[0058] In step S208 following step S207, the control device 100 performs a process of stopping the operation of the compressor 2. After the process of step S208, the control device 100 ends the series of processes shown in FIG.

[0059] According to the lubricant oil heating mode of the first example, even if the compressor 2 is stopped in an extremely low outside air temperature environment, when the next operation mode such as air conditioning is started, the lubricant oil in the compressor 2 does not solidify and the compressor 2 can be started in a normal state. In addition, according to the lubricant oil heating mode of the first example, the refrigerant accumulated in the heat exchange section by the operation mode performed before the compressor 2 was stopped is recovered in the accumulator 16 by flowing the refrigerant through the heat exchange section, so that it is possible to prevent a shortage of refrigerant to be flowed through the refrigerant circuit 10 in the next operation mode such as air conditioning. Furthermore, according to the lubricant oil heating mode of the first example, when the refrigerant has already been recovered in the accumulator 16, the compressor 2 is operated in the bypass operation mode, so that the energy consumption for heating the lubricant oil can be reduced.

[0060] [Lubricant oil heating mode (second example)] The processing contents of the lubricant heating mode (step S103) of the second example will be described. The lubricant heating mode of this second example is different from the lubricant heating mode of the first example in that the compressor 2 is only operated in the bypass operation mode. That is, in the lubricant heating mode of the second example, the refrigerant recovery process is not performed, and only the lubricant in the compressor 2 is heated in the bypass operation mode in which the refrigerant flows in the refrigerant flow path shown by the thick black line in Fig. 7 described above.

[0061] Specifically, as shown in FIG. 8, in step S301, the control device 100 performs the same process as in step S206 (FIG. 4) described above (i.e., operates the compressor 2 in a bypass operation mode in which the refrigerant flows through the refrigerant flow path indicated by the thick black line in FIG. 7), and in the following step S302, performs the same process as in step S207 described above (determines whether the lubricant temperature is less than the specified value). If NO in step S302, the control device 100 performs the process of step S302 again, and if YES in step S302, performs the same process as in step S208 described above (stops the compressor 2) in the following step S303, and then ends the series of processes shown in FIG. 8. According to the lubricant heating mode of the second example, the compressor 2 is operated in the bypass operation mode, so that the energy consumption for heating the lubricant in the compressor 2 can be reduced.

[0062] [Lubricant oil heating mode (third example)] The processing contents of the lubricant heating mode (step S103) of the third example will be described. The lubricant heating mode of the third example is different from the lubricant heating modes of the first and second examples in that the lubricant in the compressor 2 is heated by passing electricity through a winding (not shown) of a motor provided in the compressor 2 without flowing refrigerant through the refrigerant circuit 10.

[0063] In the lubricant heating mode of the third example, as shown in FIG. 9, the control device 100 controls the compressor 2 in step S401 to lock the motor (not shown) provided therein during operation of the compressor 2 so that the motor is not rotated. At this time, as shown by the dashed line in FIG. 10, the refrigerant circuit 10 is in a state in which refrigerant does not flow. Of course, the heat medium circuit 30 and the air conditioning unit 20 are not in operation at this time. In this state, in the subsequent step S402, the control device 100 heats the lubricant in the compressor 2 by energizing the windings of the motor in the compressor 2 in this locked state. Thus, in the lubricant heating mode of the third example, the compressor 2 is operated in a locked state, so that the compressor 2 itself is used as a heater and only the lubricant in the compressor 2 is heated without flowing the refrigerant in the refrigerant circuit 10.

[0064] In the next step S403, the control device 100 performs the same process as in the above-mentioned step S207 (determining whether the lubricant temperature is less than a specified value). If NO in step S403, the control device 100 performs the process of step S403 again, and if YES in step S403, in the next step S404, the control device 100 stops the power supply to the windings of the locked motor provided in the compressor 2, and then performs the same process as in the above-mentioned step S208 (stopping the compressor 2) in step S405, and then ends the series of processes shown in FIG. 9.

[0065] According to the lubricant oil heating mode of the third example, the lubricant oil in the compressor 2 can be easily heated and prevented from solidifying with a simple configuration and simple process of using the compressor 2 itself as a heater. Moreover, according to the lubricant oil heating mode of the third example, the refrigerant is not caused to flow through the refrigerant circuit 10, so that the energy consumption for heating the lubricant oil in the compressor 2 can be reduced.

[0066] [Lubricant oil heating mode (Example 4)] The processing contents of the lubricant heating mode (step S103) of the fourth example will be described. The lubricant heating mode of the fourth example is different from the lubricant heating modes of the first and second examples in that refrigerant is not caused to flow through the refrigerant circuit 10, and different from the lubricant heating mode of the third example in that a compressor heater (not shown) is provided on the outer surface of the compressor 2, and the lubricant in the compressor 2 is heated by energizing the compressor heater. As the compressor heater, for example, a ribbon heater (not shown) that is wound around the outer surface of the compressor 2 can be used, but is not limited thereto, and other heaters may be used.

[0067] In the lubricant oil heating mode of the fourth example, the compressor 2 is stopped under the control of the control device 100, and no refrigerant flows through the refrigerant circuit 10. Furthermore, no heat medium flows through the heat medium circuit 30, and the air conditioning unit 20 is not in operation. In addition, in the lubricant oil heating mode of the fourth example, in step S501 shown in Fig. 11, the control device 100 applies electricity to a compressor heater provided on the outer surface of the compressor 2 to heat the lubricant oil in the compressor 2.

[0068] Then, in the next step S502, the control device 100 performs the same process as in the above-mentioned step S207 (determining whether the lubricant temperature is less than the specified value). If the result in step S502 is NO, the control device 100 performs the process in step S502 again, and if the result in step S502 is YES, in the next step S503, the control device 100 stops the supply of electricity to the compressor heater and ends the series of processes shown in FIG.

[0069] According to the lubricant oil heating mode of the fourth example, the lubricant oil in the compressor 2 can be easily heated and prevented from solidifying by a simple configuration and simple process, such as passing electricity through a heater (compressor heater) provided on the outer surface of the compressor 2. Moreover, according to the lubricant oil heating mode of the fourth example, since the refrigerant is not caused to flow through the refrigerant circuit 10, the energy consumption for heating the lubricant oil in the compressor 2 can be reduced.

[0070] [Lubricant oil heating mode (example 5)] The processing contents of the lubricant heating mode (step S103) of the fifth example will be described. The lubricant heating mode of the fifth example is different from the lubricant heating modes of the first and second examples in that the refrigerant is not flowed through the refrigerant circuit 10, and is different from the lubricant heating modes of the third and fourth examples in that the compressor 2 receives heat from the heat medium heated by the heater (ECH: Electric Coolant Heater) 32 of the heat medium circuit 30 to heat the lubricant in the compressor 2, as will be described later with reference to FIG. 12. That is, the lubricant heating mode of the fifth example uses the heat medium heated by the heater (ECH) 32 as a heat source instead of the compressor heater in the lubricant mode of the fourth example.

[0071] In the vehicle air conditioner 1 that executes the lubricant oil heating mode of the fifth example, the heat medium circuit 30 includes a heat medium flow path (heat medium piping) C2 in contact with the compressor 2 in addition to the heat medium flow path (heat medium piping) C1, and also includes three-way valves 35 and 36, as shown in Fig. 13. Also, a heat medium pump 37 that heats the heat medium circulating through the heat medium flow path C2. Note that the heat medium flow paths (heat medium piping) C1 and C2 are shared between the three-way valve 35 and the heater 32, and between the three-way valve 36 and the heater (ECH) 32.

[0072] In the lubricant heating mode of the fifth example, the compressor 2 is stopped under the control of the control device 100, and the refrigerant does not flow through the refrigerant circuit 10. Also, under the control of the control device 100, the valves of the three-way valves 35 and 36 connected to the heater (ECH) 32 and the heat medium pump 37 are opened, and the valves of the three-way valve 35 connected to the circulation pump 31 and the valves of the three-way valve 36 connected to the flow path 34B of the chiller heat exchanger 34 are closed. Also, under the control of the control device 100, the circulation pump 31 and the temperature-controlled heat exchanger 33 are not operated, and the heater 32 and the heat medium pump 37 are operated. As a result, the heat medium circulates through the heat medium flow path C2 instead of the heat medium flow path C1. The lubricant oil in the compressor 2 that comes into contact with the heat medium flow path C2 is heated.

[0073] Specifically, in the lubricant oil heating mode of the fifth example, as shown in Fig. 12, the control device 100 operates the heater (ECH) 32 in step S601, and then operates the heat medium pump 37 in step S602 to circulate the heat medium heated by the heater 32 in the heat medium flow path C2. As a result, the compressor 2 receives heat from the heat medium flow path C2 through which the heated heat medium flows, and the lubricant oil in the compressor 2 is heated.

[0074] Then, in the next step S603, the control device 100 performs the same process as in the above-mentioned step S207 (determining whether the lubricant temperature is less than the specified value). If the result of step S603 is NO, the control device 100 performs the process of step S603 again. On the other hand, if the result of step S603 is YES, the control device 100 stops the operation of the heat medium pump 37 in the next step S604, and then stops the operation of the heater (ECH) 32 in step S605. This stops the heating of the lubricant in the compressor 2 by the heat of the heated heat medium.

[0075] According to the lubricant oil heating mode of the fifth example, the lubricant oil in the compressor 2 can be easily heated by a simple process, and the lubricant oil can be prevented from solidifying. Moreover, according to the lubricant oil heating mode of the fifth example, the refrigerant is not caused to flow through the refrigerant circuit 10, so that the energy consumption for heating the lubricant oil in the compressor 2 can be reduced.

[0076] The present embodiment and its modified examples have been described in detail above with reference to the drawings. However, the specific configuration is not limited to the above-described examples, and the present invention also includes design changes and the like that do not deviate from the gist of the present invention.

[0077] For example, in the lubricant heating modes of the first to fifth examples described above, the entire outer surface of the compressor 2 may further be covered with a heat insulating material (not shown). The heat insulating material may be, for example, a non-flammable heat insulating sheet (not shown), but may have other configurations. By covering the entire outer surface of the compressor 2 with a heat insulating material (not shown), it is possible to suppress heat radiation from the surface of the compressor 2 and make the compressor 2 less likely to cool, and also to further reduce the energy consumption for heating the compressor 2. [Explanation of symbols]

[0078] 1: vehicle air conditioner, 2: compressor, 10: refrigerant circuit, 10V: hot gas bypass, 11: external heat exchanger, 12, 13: flow path switching valve, 14, 15: check valve, 16: accumulator, 20: air conditioning unit, 21, 22: indoor heat exchanger, 23: blower, 24, 25: air damper, 25A, 25B: air inlet, 26: air flow passage, 30: heat medium circuit, 31: circulation pump, 32: heater, 33: temperature control target heat exchanger, 34: refrigerant heat medium heat exchanger, 34A, 34B: flow path, 35, 36: three-way valve, 37: heat medium pump, 40: sensor unit, 41: outside air temperature sensor, 42: refrigerant temperature sensor, 43: refrigerant pressure sensor, 100: control device

Claims

1. a refrigerant circuit including a compressor, an indoor heat exchanger, and an external heat exchanger; an air conditioning unit having the indoor heat exchanger disposed therein; a control device for controlling the refrigerant circuit and the air conditioning unit, A lubricant temperature estimating unit is provided for estimating a temperature of the lubricant in the compressor when the compressor is stopped. death, a lubricant temperature estimating unit that, when determining that the temperature of the lubricant is equal to or lower than a specified value, executes a lubricant heating mode in which the lubricant in the compressor is heated.

2. 2. The vehicle air conditioning system according to claim 1, wherein the lubricant temperature estimation unit estimates the temperature of the lubricant from at least one of a state of the refrigerant in the refrigerant circuit and an outside air temperature.

3. 2. The vehicle air conditioner according to claim 1, wherein the lubricant oil heating mode causes the refrigerant to flow through a heat exchange section in the refrigerant circuit through which the refrigerant passed in the operation mode performed before the compressor was stopped.

4. 4. The air conditioner for a vehicle according to claim 3, wherein in the lubricant oil heating mode, heat exchange of the refrigerant is prohibited.

5. a bypass path through which the refrigerant discharged from the compressor flows to a suction side of the compressor, bypassing the indoor heat exchanger; 4. The vehicle air conditioning system according to claim 3, wherein in the lubricant oil heating mode, after the refrigerant in the refrigerant circuit has been caused to flow through a heat exchange section through which the refrigerant had passed in the operation mode performed before the compressor was stopped, all of the refrigerant discharged from the compressor is caused to flow through the bypass path.

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