Vehicular air conditioning device

Abstract

[Problem] To provide a vehicular air conditioner capable of starting a compressor in a normal state without solidifying lubricating oil inside the compressor even in an extremely low outside air temperature environment. [Solution] A vehicular air conditioner according to the present invention comprises: a refrigerant circuit including a compressor, an indoor heat exchange unit, and an outdoor heat exchange unit; an air conditioning unit in which the indoor heat exchange unit is disposed; and a control device that controls the refrigerant circuit and the air conditioning unit. The vehicular air conditioner has a lubricating oil temperature estimation part for estimating the temperature of lubricating oil inside the compressor when the compressor stops. When the lubricating oil temperature estimating part determines that the temperature of the lubricating oil is equal to or lower than a specified value, a lubricating oil heating mode for heating the lubricating oil inside the compressor is executed.

Description

Vehicle air conditioning system

[0001] The present invention relates to an air conditioning system for a vehicle.

[0002] BACKGROUND 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 low heat output from a combustion-based heat source.

[0003] Generally, air conditioners that use 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 drops to extremely low temperatures (for example, -40°C or below), it becomes difficult to absorb heat from the outside air, resulting in a significant drop in heating capacity.

[0004] In such extremely low ambient temperature environments, it is common to secure a heat source using an electric heater such as a PTC heater, etc. However, using such a heat source increases battery consumption, which can have a negative impact on the driving range of electric vehicles, and the installation of a PTC heater increases the manufacturing cost of the air conditioning system.

[0005] On the other hand, hot gas heating, which uses a high-temperature, high-pressure refrigerant discharged from a compressor in a refrigerant circuit, is a heating method that does not involve heat absorption and is expected to be effective in extremely low-temperature environments. In this hot gas heating method, the interior heat exchanger of a vehicle air conditioner functions as a radiator (interior condenser), and the high-temperature, high-pressure refrigerant discharged from the compressor flows directly into this condenser. After decompressing the refrigerant, the refrigerant is returned to the compressor via an accumulator without passing through an external heat exchanger (see, for example, Patent Document 1).

[0006] Japanese Patent Application Laid-Open No. 2014-196017

[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 subsequently stopped due to parking or the like, the lubricating oil in the compressor will cool and become more viscous, causing the solidified lubricating oil to adhere to various parts inside the compressor, which may cause torque abnormalities or the like when the compressor is next started, resulting in a startup failure.

[0008] The present invention has been made in consideration of the above circumstances, and has as its object to provide a vehicle air conditioning system that can start the compressor in a normal state without the lubricating oil in the compressor solidifying, even in an extremely low outside temperature environment.

[0009] The vehicle air conditioning system of the present invention is equipped with 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, 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 that heats the lubricant oil in the compressor.

[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.

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

[0012] Hereinafter, a mode for carrying out the present invention (the present embodiment) 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] 1, the vehicle air conditioning system 1 includes a refrigerant circuit 10 and an air conditioning unit 20. The refrigerant circuit 10 includes a compressor 2, indoor heat exchangers 21 and 22 (indoor heat exchange portion) disposed inside the air conditioning unit 20, and an external heat exchanger 11 (external heat exchange portion) disposed outside the vehicle cabin, all of which are arranged along a refrigerant flow path. The indoor heat exchangers 21 and 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 refrigerant and outside air outside the vehicle cabin.

[0014] The compressor 2 of the refrigerant circuit 10 compresses and circulates a refrigerant. The refrigerant compressed by the compressor 2 is reduced to a required pressure by passing through an appropriately selected refrigerant flow path, for example, 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 expansion valves. The refrigerant circuit 10 is provided with flow path switching valves 12 and 13 for switching the refrigerant flow path, and 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. Air introduced from the inside or outside of the room by the blower 23 selectively passes through the indoor heat exchangers 21 and 22 before being blown into the room. The air conditioning unit 20 also 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 before being blown into the room. 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 before being 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-described external heat exchanger 11 and indoor heat exchangers 21, 22 have been described as examples in which the refrigerant directly exchanges heat with the air, the refrigerant may indirectly exchange heat with the air 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 release 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-controlled object such as a battery in a temperature-controlled 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 by the PTSs 42 and 43 in FIG. 1, the refrigerant circuit 10 is provided with a refrigerant temperature sensor 42 (FIG. 2) that detects the temperature of the refrigerant on the side sucked into the compressor 2, and a refrigerant pressure sensor 43 (FIG. 2) that detects the pressure of the refrigerant on the side sucked into the compressor 2.

[0019] 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 the sensor unit 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 necessary for the control device 100 to perform 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, 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. In addition, the control device 100 controls the vehicle air conditioner 1 in accordance with the processing results of the control device 100.

[0022] [Outside Air Heating Operation] The vehicle air conditioner 1 can perform 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, the control device 100 controls the flow path switching valve 12 to be closed and the flow path switching valve 13 to be open, the first pressure reduction section V1 to be 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 to be fully closed, and the grill shutter (not shown) provided in the external heat exchanger 11 to be open.

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

[0024] In this outside-air heat-absorbing heating operation, high-temperature, high-pressure refrigerant compressed by compressor 2 is sent to indoor heat exchanger 21 in air conditioning unit 20, which functions as a radiator, and air taken into air conditioning unit 20 from air inlet 25B by driving blower 23 is heated as it passes through indoor heat exchanger 21 and is then blown into the vehicle cabin. At this time, air inlet 25A of air conditioning unit 20 is closed by air damper 25, and air damper 24 in air flow passage 26 only opens the flow path of air heading toward 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 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] 1, in hot gas heating operation, the flow switching valve 12 is controlled to be open and the third pressure reducing unit 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 switching valve 13 is controlled to be closed and the first pressure reducing unit V1 is controlled to be fully closed, so that refrigerant does not flow to the external heat exchanger 11. Also, under the control of the control device 100, the fourth pressure reducing unit V4 is controlled to be fully closed, so that refrigerant does not flow 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 decompressed in the third pressure reduction section V3 to become 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, undergoes gas-liquid separation in this accumulator 16, and then returns to the compressor 2 from the refrigerant pipe R1.

[0028] In the vehicle air conditioner 1 that performs 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 unit) and the external heat exchanger 11 (external heat exchange unit) 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, depressurized at a second depressurization section V2 (hot gas valve), and merged with the low-pressure refrigerant depressurized at a third depressurization section V3 at a junction point P2 immediately upstream of the accumulator 16.

[0029] By providing such hot gas bypass 10V, the liquid refrigerant condensed by heat release in the indoor heat exchanger 21 is mixed with the gas refrigerant that has passed through the hot gas bypass 10V to produce a gas-rich refrigerant that can be returned to the compressor 2. In addition, by increasing the flow rate of refrigerant flowing through the hot gas bypass 10V, the amount of heat release in the indoor heat exchanger 21 can be suppressed, 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 flow rate of refrigerant flowing through the hot gas bypass 10V, the balance between the amount of heat release from the refrigerant circuit 10 and the amount of heat input to the compressor 2 can be maintained.

[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 becomes high-pressure refrigerant upstream and low-pressure refrigerant downstream. At this time, to maintain heating capacity, heat exchange does not occur in the chiller heat exchanger 34 in the low-pressure flow path. In the air conditioning unit 20, air introduced by the blower 23 is heated by heat released by the indoor heat exchanger 21 and blown into the vehicle cabin.

[0031] [Lubricant Oil Heating Mode Execution Control Process] Typically, when an operating mode such as air conditioning is stopped (i.e., compressor 2 is stopped) due to a vehicle being parked in an extremely low outside temperature environment (e.g., −40° C. or below), the viscosity of the lubricant oil in compressor 2 increases and solidifies. This solidified lubricant oil may adhere to various components in compressor 2, causing torque abnormalities and potentially resulting in startup failure. Therefore, in the vehicle air conditioner 1 of this embodiment, when an operating mode is stopped in such an extremely low outside temperature environment (i.e., when compressor 2 is stopped), a lubricant oil heating mode is executed under the control of the control device (air conditioning controller) 100, in which the lubricant oil in compressor 2 is heated to prevent solidification. The execution control process for this lubricant oil heating mode ( FIG. 3 ) is described below.

[0032] When the control device (air conditioning controller) 100 starts the execution control process for the lubricant oil heating mode, in step S101, in order to determine whether it is necessary to execute the lubricant oil heating mode, the control device (air conditioning controller) 100 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] If the control device 100 determines that the environment in which the compressor 2 is currently stopped is this extremely low outside temperature (-40°C or below) (YES in step S101), it proceeds to step S102 to further determine whether it is necessary to execute the lubricant oil heating mode.If the control device 100 determines that the environment in which the compressor 2 is currently stopped is not this extremely low outside temperature (-40°C or below) (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 Figure 3. Note that although the extremely low outside temperature is set to -40°C or below here, this temperature value is just an example, and the extremely low outside temperature may be -35°C or below, for example.

[0034] In step S102 following step S101, the control device (air conditioning controller) 100 estimates the temperature of the lubricating oil in the compressor 2 to estimate whether the state of the lubricating oil in the compressor 2 is changing from a liquid to a solid state (a state that is 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 lubricating oil in the compressor 2 constitutes a lubricating oil temperature estimation unit.

[0035] Here, the specified value may be, for example, the pour point, which is 2.5°C higher than the freezing point of the lubricant in the compressor 2. In this case, when the lubricant temperature estimated by the control device 100 (lubricant temperature estimation unit) is higher than the freezing point but lower than the pour point, it may be assumed that the lubricant is already in a state where it is losing its fluidity, just before it becomes solid. Also, when the lubricant temperature estimated by the control device 100 (lubricant temperature estimation unit) is lower than the freezing point, it may be assumed 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 it 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, and thereby determines that the lubricating oil is in a state where it is about to solidify or has already solidified (YES in step S102), the control device 100 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), and thereby determines 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 the series of processes shown in FIG. 3 are terminated.

[0037] In 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 of the temperature of the refrigerant (refrigerant temperature) drawn into the compressor 2, detected by the refrigerant temperature sensor 42, and the refrigerant pressure, from which the temperature of the refrigerant drawn into the compressor 2 can be estimated, detected by the refrigerant pressure sensor 43 ("PTS 42, 43" in FIG. 1 ). This example is not limiting, and at least one of the refrigerant temperature sensor 42 and the refrigerant pressure sensor 43 may be provided elsewhere 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 of the refrigerant temperature sensor 42 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, confirm 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 range (below -40°C), thereby estimating that the temperature of the lubricating oil in the compressor 2 is below a specified value.

[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 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 processing of step S102 and proceeds to step S103.

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

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

[0042] 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. In the refrigerant recovery operation, the refrigerant discharged from the compressor 2 flows through 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 had 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 (whether the refrigerant has already been recovered).

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

[0045] In step S202, which follows step S201, the control device 100 determines whether the operating mode performed before the compressor 2 was stopped was the outdoor-air heat absorption heating operation. If the control device 100 determines that the operating mode performed before the compressor 2 was stopped was not the outdoor-air heat absorption heating operation and therefore determines that the operating mode performed before the compressor 2 was stopped was the hot gas heating operation (NO in step S202), the control device 100 proceeds to step S203 to cause the refrigerant to flow through the flow path 34A of the chiller heat exchanger 34, which is the heat exchanger through which the refrigerant passed during the hot gas heating operation. On the other hand, if the control device 100 determines that the operating mode performed before the compressor 2 was stopped was the outdoor-air heat absorption heating operation (YES in step S202), the control device 100 proceeds to step S204 to cause the refrigerant to flow through the external heat exchanger 11, which is the heat exchanger through which the refrigerant passed during the outdoor-air heat absorption heating operation.

[0046] If the result of step S202 is NO, the control device 100 subsequently confirms in step S203 that the circulation pump 31 of the heat medium circuit 30 is stopped, 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, in step S205, the control device 100 operates the compressor 2 to perform chiller refrigerant recovery operation. Although not shown in FIG. 4 , during this chiller refrigerant recovery operation, the control device 100 controls the flow path switching valve 12, the third pressure reduction unit V3, the flow path switching valve 13, the first pressure reduction unit V1, the fourth pressure reduction unit V4, and other components to the same states as those during the hot gas heating operation, which was performed before the compressor 2 was stopped, and the second pressure reduction unit V2 is controlled to be fully closed (note that the third pressure reduction unit V3 may be controlled to be fully open). The control device 100 also 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 compressor 2 is operated, and heat (self-heating) due to friction and current flow within the compressor 2 heats the lubricating oil within the compressor 2. At the same time, in this chiller refrigerant recovery operation, as shown by the thick black line in FIG. 5 , refrigerant flows through the flow path 34A of the chiller heat exchanger 34, which is the heat exchanger through which the refrigerant passed during the hot gas heating operation, which was the operation mode performed before the compressor 2 was stopped. It is estimated that refrigerant accumulated in the flow path 34A of the chiller heat exchanger 34 after the hot gas heating operation, which was the operation mode performed before the compressor 2 was stopped, ended. Therefore, in the chiller refrigerant recovery operation, the refrigerant flows through the flow path 34A of the chiller heat exchanger 34, and the refrigerant is recovered from the flow path 34A into the accumulator 16.

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

[0049] As shown in FIG. 5 , the refrigerant discharged from the compressor 2 flows through the refrigerant pipes R1 and R2 and passes through the indoor heat exchanger 21, then flows from the refrigerant pipe R3 through the flow path switching valve 12 to the 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 the refrigerant pipe R8, flows through the refrigerant pipes R9 and R10, and is collected in the accumulator 16.

[0050] If the answer to step S202 is YES, the control device 100 then closes a grille shutter (not shown) of the external heat exchanger 11 in step S204 to inhibit heat exchange between the refrigerant and the outside air. Then, in step S205, the control device 100 operates the compressor 2 to perform an external heat exchanger refrigerant recovery operation. Although not shown in FIG. 4 , during 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 unit V1, the third pressure reduction unit V3, and the fourth pressure reduction unit V4 to the same states as during the external heat absorption heating operation, which was performed before the compressor 2 was stopped (note that the first pressure reduction unit V1 may be controlled to be fully open). The control device 100 also disables the heat medium circuit 30 and the air conditioning unit 20.

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

[0052] Furthermore, in the external heat exchanger refrigerant recovery operation, even if a small amount of lubricating oil is discharged from the compressor 2 mixed with the refrigerant during the external endothermic heating operation, which is the operating mode performed before the compressor 2 is stopped, the external heat exchanger refrigerant recovery operation can recover the lubricating oil mixed with the refrigerant into the accumulator 16.

[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 and refrigerant pipe R7, passes through flow path switching valve 13 and check valve 14, and is collected from refrigerant pipe R10 to accumulator 16.

[0054] In this way, the control device 100 causes the refrigerant in the refrigerant circuit 10 to flow (with heat exchange prohibited) through the heat exchange section that was passed through 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 the bypass operation mode, the control device 100 fully opens the second pressure reduction unit V2, closes the flow path switching valves 12 and 13, and fully closes the first pressure reduction unit V1, the third pressure reduction unit V3, and the fourth pressure reduction unit V4. As a result, in the bypass operation mode, the compressor 2 is operated, and heat (self-heating) due to friction and current flow within the compressor 2 heats the lubricating oil in the compressor 2. At this time, as shown by the thick black line in Fig. 7, the refrigerant flows through the hot gas bypass 10V (bypass path) described above. That is, the refrigerant discharged from the compressor 2 passes through the second pressure reduction unit 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 lubricating oil in the compressor 2 in order to estimate whether the lubricating oil 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 lubricating oil 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 lubricating oil in the compressor 2 is higher than a specified value and therefore determines that the lubricating oil in the compressor 2 has not solidified (YES in step S207), the control device 100 proceeds to step S208 to end the lubricating oil heating mode. On the other hand, when the control device 100 determines that the estimated temperature of the lubricating oil in the compressor 2 is not higher than a specified value (i.e., is equal to or lower than the specified value) and therefore determines that the lubricating oil 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 processing of step S207 again. That is, the processing of step S207 is repeated until the control device 100 determines that the lubricating oil in the compressor 2 has not solidified.

[0058] In step S208 following step S207, the control device 100 performs processing to stop the operation of the compressor 2. After processing in step S208, the control device 100 ends the series of processing 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 outdoor air temperature environment, the lubricant oil in the compressor 2 does not solidify and the compressor 2 can be started normally when the next operating mode, such as air conditioning, is started. Furthermore, according to the lubricant oil heating mode of the first example, the refrigerant accumulated in the heat exchange section during the operating mode performed before the compressor 2 was stopped is returned to the accumulator 16 by flowing the refrigerant through the heat exchange section, thereby preventing a shortage of refrigerant to flow through the refrigerant circuit 10 during the next operating mode, such as air conditioning. Furthermore, according to the lubricant oil heating mode of the first example, if refrigerant has already been recovered in the accumulator 16, the compressor 2 can be operated in the bypass operating mode, thereby reducing the energy consumption required to heat the lubricant.

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

[0061] Specifically, as shown in FIG. 8 , in step S301, the control device 100 performs the same process as step S206 ( FIG. 4 ) described above (i.e., operates the compressor 2 in the bypass operation mode in which the refrigerant flows through the refrigerant flow path indicated by the thick black line in FIG. 7 ), and then in step S302, performs the same process as step S207 described above (determines whether the lubricant temperature is less than the specified value). If the result in step S302 is NO, the control device 100 performs the process in step S302 again. If the result in step S302 is YES, the control device 100 performs the same process as step S208 described above (stops the compressor 2) in 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, thereby reducing the energy consumption required to heat the lubricant in the compressor 2.

[0062] [Lubricant Oil Heating Mode (Third Example)] The processing details of the lubricant oil heating mode (step S103) of the third example will be described. The lubricant oil heating mode of the third example differs from the lubricant oil heating modes of the first and second examples in that the lubricant oil in the compressor 2 is heated by energizing a winding (not shown) of a motor provided in the compressor 2 without flowing refrigerant through the refrigerant circuit 10.

[0063] In the lubricant oil heating mode of the third example, as shown in FIG. 9 , in step S401, the control device 100 controls the compressor 2 to lock the motor (not shown) installed inside the compressor 2 so that the motor is not rotated when the compressor 2 is operating. At this time, as shown by the dashed line in FIG. 10 , no refrigerant flows through the refrigerant circuit 10. Of course, the heat medium circuit 30 and the air conditioning unit 20 are not operating at this time. In this state, in the subsequent step S402, the control device 100 energizes the motor windings in the locked compressor 2 to heat the lubricant oil in the compressor 2. In this way, in the lubricant oil heating mode of the third example, by operating the compressor 2 in the locked state, the compressor 2 itself is used as a heater, and only the lubricant oil in the compressor 2 is heated without flowing refrigerant through the refrigerant circuit 10.

[0064] In the next step S403, the control device 100 performs the same process as in the above-described step S207 (determining whether the lubricating oil temperature is less than the specified value). If the result in step S403 is NO, the control device 100 performs the process in step S403 again. If the result in step S403 is YES, the control device 100 stops the power supply to the windings of the locked motor provided in the compressor 2 in the next step S404, and then performs the same process as in the above-described 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, such as using the compressor 2 itself as a heater. Furthermore, according to the lubricant oil heating mode of the third example, refrigerant is not circulated through the refrigerant circuit 10, so energy consumption for heating the lubricant oil in the compressor 2 can be reduced.

[0066] [Lubricant Oil Heating Mode (Fourth Example)] The processing details of the lubricant oil heating mode (step S103) of the fourth example will be described. The lubricant oil heating mode of this fourth example differs from the lubricant oil heating modes of the first and second examples in that refrigerant is not circulated through the refrigerant circuit 10, and differs from the lubricant oil 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 oil in the compressor 2 is heated by energizing the compressor heater. As the compressor heater, for example, a ribbon heater (not shown) that is wrapped around the outer surface of the compressor 2 can be used, but the present invention is not limited to this, and other heaters may also be used.

[0067] In the lubricant oil heating mode of this 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 operating. Furthermore, in the lubricant oil heating mode of this 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, thereby heating the lubricant oil in the compressor 2.

[0068] In the next step S502, the control device 100 performs the same process as in the above-described step S207 (determining whether the lubricant temperature is less than the specified value). If the determination in step S502 is NO, the control device 100 performs the process in step S502 again. If the determination in step S502 is YES, the control device 100 stops the supply of power to the compressor heater in the next step S503, and ends the series of processes shown in FIG. 11.

[0069] According to the lubricant oil heating mode of the fourth example, it is possible to easily heat the lubricant oil in the compressor 2 and prevent the lubricant oil from solidifying with a simple configuration and simple process, such as by passing electricity through a heater (compressor heater) provided on the outer surface of the compressor 2. Furthermore, according to the lubricant oil heating mode of the fourth example, refrigerant is not circulated through the refrigerant circuit 10, so it is possible to reduce the energy consumption for heating the lubricant oil in the compressor 2.

[0070] [Lubricant Oil Heating Mode (Fifth Example)] The processing details of the lubricant oil heating mode (step S103) of the fifth example will be described. Unlike the lubricant oil heating modes of the first and second examples, the lubricant oil heating mode of the fifth example does not flow refrigerant through the refrigerant circuit 10. Also, unlike the lubricant oil heating modes of the third and fourth examples, as will be described later with reference to FIG. 12 , the compressor 2 receives heat from a heat medium heated by a heater (ECH: Electric Coolant Heater) 32 of the heat medium circuit 30 to heat the lubricant oil in the compressor 2. That is, the lubricant oil 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 of the lubricant oil mode of the fourth example.

[0071] 13 , in the vehicle air conditioner 1 that executes the lubricant oil heating mode of this fifth example, the heat medium circuit 30 includes, in addition to the heat medium flow path (heat medium piping) C1, a heat medium flow path (heat medium piping) C2 that contacts the compressor 2, and also includes three-way valves 35 and 36. The heat medium circuit 30 also includes 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 piping 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 oil heating mode of this fifth example, the compressor 2 is stopped under the control of the control device 100, and no refrigerant flows through the refrigerant circuit 10. The control device 100 also opens the valves of the three-way valves 35 and 36 connected to the heater (ECH) 32 and the heat transfer medium pump 37, and closes the valves of the three-way valve 35 connected to the circulation pump 31 and the valve of the three-way valve 36 connected to the flow path 34B of the chiller heat exchanger 34. The control device 100 also deactivates the circulation pump 31 and the temperature-controlled heat exchanger 33, while operating the heater 32 and the heat transfer medium pump 37. As a result, the heat transfer medium circulates through the heat transfer medium flow path C2 instead of the heat transfer medium flow path C1. The lubricant oil in the compressor 2 that comes into contact with the heat transfer medium flow path C2 is heated.

[0073] 12 , in the lubricant oil heating mode of the fifth example, the control device 100 operates the heater (ECH) 32 in step S601, and then operates the heat medium pump 37 in step S602, thereby circulating 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 following step S603, the control device 100 performs the same process as in the above-described step S207 (determining whether the lubricant temperature is less than the specified value). If the determination in step S603 is NO, the control device 100 performs the process in step S603 again. On the other hand, if the determination in step S603 is YES, the control device 100 stops the operation of the heat medium pump 37 in the following 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 and prevented from solidifying through a simple process. Furthermore, according to the lubricant oil heating mode of the fifth example, the refrigerant is not circulated 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 above in detail with reference to the drawings, but 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 oil 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), heat radiation from the surface of the compressor 2 can be suppressed, making it difficult for the compressor 2 to cool, and also making it possible to further reduce the energy consumption for heating the compressor 2.

[0078] 1: Vehicle air conditioning device, 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-controlled 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 vehicle air conditioning system comprising 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 for controlling the refrigerant circuit and the air conditioning unit, the vehicle air conditioning system further comprising a lubricant temperature estimation unit for estimating a temperature of a lubricant in the compressor when the compressor is stopped, and a lubricant heating mode for heating the lubricant in the compressor when the lubricant temperature estimation unit determines that the temperature of the lubricant is below a specified value.

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 the state of the refrigerant in the refrigerant circuit and the outside air temperature.

3. The vehicle air conditioning system according to claim 1, characterized in that in the lubricant oil heating mode, the refrigerant is caused 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. The vehicle air conditioner according to claim 3, wherein in the lubricant oil heating mode, heat exchange of the refrigerant is prohibited.

5. A vehicle air conditioning system as described in claim 3, characterized in that it has a bypass path through which the refrigerant discharged from the compressor flows to the suction side of the compressor, bypassing the indoor heat exchange section, and in the lubricant oil heating mode, after the refrigerant in the refrigerant circuit flows through the heat exchange section through which the refrigerant passed in the operating mode performed before the compressor was stopped, all of the refrigerant discharged from the compressor flows through the bypass path.

Images