Patent Application
20250164163
The present disclosure relates to a refrigeration cycle device including an electric expansion valve.
A conventional refrigeration cycle device determines shortage of refrigerant, when a pressure difference caused by fluctuations in pressure of the refrigerant compressed by a compressor is less than an abnormality determination value after lapse of a predetermined time from a start of the compressor.
However, due to a gradual increase of a degree of superheat of the refrigerant flowing out of an evaporator as an amount of refrigerant gradually decreases, it may be difficult for a lubricating oil to return to the compressor, thereby causing problems in lubrication of the compressor.
According to an aspect of the present disclosure, a refrigeration cycle device includes: a compressor configured to suck, compress and discharge a refrigerant; a radiator configured to dissipate heat from the refrigerant that is discharged from the compressor; an expansion valve configured to decompress and expand the refrigerant flowing from the radiator; an evaporator configured to evaporate the refrigerant which has been decompressed and expanded by the expansion valve; and a controller configured to control an opening degree of the expansion valve. The controller includes at least one of a circuit and a processor having a memory, and is configured: to determine an increase/decrease amount (a variation amount) of the opening degree of the expansion valve to a first amount when a superheat degree of the refrigerant flowing out from the evaporator is equal to or lower than a predetermined superheat degree; and to determine the increase/decrease amount of the opening degree of the expansion valve to a second amount that is set to more suppress an increase of the superheat degree of the refrigerant flowing out from the evaporator, than that of the first amount, when the superheat degree of the refrigerant flowing out from the evaporator is higher than the predetermined superheat degree.
For example, the controller may determine the first amount to cause a subcooling degree of the refrigerant flowing out from the radiator closer to a target subcooling degree, and may determine the second amount to cause the superheat degree of the refrigerant flowing out from the evaporator closer to a target superheat degree.
The foregoing and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description with reference to the accompanying drawings. In the drawings:
In a conventional refrigeration cycle device, when a pressure difference caused by fluctuations in the pressure of the refrigerant compressed by a compressor after lapse of a predetermined time from a start of the compressor is less than an abnormality determination value, it is determined that there is a shortage of refrigerant.
However, in the conventional refrigeration cycle device, during a transition time from when an amount of refrigerant begins to decrease until it is determined that there is a shortage of refrigerant, a degree of superheat of the refrigerant flowing out of an evaporator is gradually increased as an amount of refrigerant decreases, and an amount of refrigerant that is dissolved in a lubricating oil decreases, thereby making it difficult for the lubricating oil to return to the compressor. In such manner, problems might be caused in lubrication of the compressor.
In view of the above, it is an object of the present disclosure to suppress a situation in which it is difficult for a lubricating oil to return to a compressor.
According to an aspect of the present disclosure, a refrigeration cycle device includes a compressor, a radiator, an expansion valve, an evaporator and a controller controlling an opening degree of the expansion valve. The controller determines an increase/decrease amount (variation amount) of the opening degree of the expansion valve, to a first amount, when a superheat degree of the refrigerant flowing out from the evaporator is equal to or lower than a predetermined superheat degree. In addition, the controller determines the increase/decrease amount of the opening degree of the expansion valve, to a second amount that is set to more suppress an increase of the superheat degree of the refrigerant flowing out from the evaporator, than that of the first amount, when the superheat degree of the refrigerant flowing out from the evaporator is higher than the predetermined superheat degree.
According to the above, even when the amount of refrigerant decreases and the degree of superheat of the refrigerant increases, a further increase in the degree of superheat of the refrigerant can be restricted. In such manner, it is possible to prevent a situation in which the lubricating oil is difficult to return to the compressor due to a decrease in the amount of refrigerant dissolved in the lubricating oil.
The following describes embodiments for carrying out the present disclosure with reference to the drawings. In the respective embodiments, parts corresponding to matters already described in the preceding embodiments are given reference numbers identical to reference numbers of the matters already described. The same description is therefore omitted depending on circumstances. In case where only a part of the configuration is described in each embodiment, other embodiments previously described can be applied to other parts of such configuration. It is also possible to partially combine the embodiments even when it is not explicitly described, as long as there is no problem in such combination as well as the combination of the parts specifically and explicitly described that the combination is possible.
In the present embodiment, a refrigeration cycle device 10 according to the present disclosure is applied to a vehicle air conditioner 1. Therefore, a cooling target object of the refrigeration cycle device 10 in the present embodiment is air blown into a vehicle compartment.
The vehicle air conditioner 1 includes the refrigeration cycle device 10, an in-compartment air-conditioning unit 30, a high-temperature-side thermal medium circuit 40, and the like, as shown in the overall configuration diagram of
In order to perform air-conditioning in the vehicle compartment, the refrigeration cycle device 10 cools air supplied to the vehicle compartment and heats a high-temperature-side thermal medium circulating in the high-temperature-side thermal medium circuit 40.
The refrigeration cycle device 10 is configured to be capable of switching between refrigerant circuits for various operation modes, in order to perform air-conditioning in the vehicle compartment. For example, a refrigerant circuit for a cooling mode, a refrigerant circuit for a dehumidifying and heating mode, a refrigerant circuit for a heating mode, and the like may be provided to be switchable.
Further, the refrigeration cycle device 10 uses an HFO-based refrigerant (specifically, R1234yf) as a refrigerant, and provides a vapor compression type subcritical refrigeration cycle in which the pressure of a discharged refrigerant discharged from a compressor 11 does not exceed a critical pressure of the refrigerant. Further, a refrigerator oil for lubricating the compressor 11 is mixed in the refrigerant. A part of the refrigerator oil circulates in the cycle together with the refrigerant.
The compressor 11 sucks the refrigerant, compresses, and discharges the refrigerant in the refrigeration cycle device 10. The compressor 11 is arranged on a front side of the vehicle compartment, and is arranged within a drive device compartment that also accommodates an electric motor and the like. The compressor 11 is an electric compressor that uses an electric motor to rotationally drive a fixed capacity type compression mechanism having a fixed discharge capacity. The rotation speed (that is, refrigerant discharge capacity) of the compressor 11 is controlled by a control signal output from a controller 60, which is described later.
An inlet side of a refrigerant passage of a water-refrigerant heat exchanger 12 is connected to a discharge port of the compressor 11. The water-refrigerant heat exchanger 12 has a refrigerant passage for circulating a high-pressure refrigerant discharged from the compressor 11 and a water passage for circulating a high-temperature-side thermal medium circulating in the high-temperature-side thermal medium circuit 40. The water-refrigerant heat exchanger 12 is a heating heat exchanger which performs heat exchange between the high pressure refrigerant flowing in the refrigerant passage and the high-temperature-side thermal medium flowing in the water passage to heat the high-temperature-side thermal medium.
An outlet port of the refrigerant passage of the water-refrigerant heat exchanger 12 is connected to an inlet side of a heating expansion valve 14a. The heating expansion valve 14a is a heating decompressor, which decompresses a high-pressure refrigerant flowing out from the refrigerant passage of the water-refrigerant heat exchanger 12, and simultaneously adjusts a flow amount (i.e., mass flow rate) of the refrigerant flowing out to a downstream side, in an operation mode for heating at least the vehicle compartment. The heating expansion valve 14a is an electric variable throttle mechanism that includes (a) a valve body, an opening degree of throttle provided therein is configured to be changeable, and (b) an electric actuator, which changes a degree of opening of the valve body.
The refrigeration cycle device 10 includes a cooling expansion valve 14b. The basic configuration of the cooling expansion valve 14b is similar to that of the heating expansion valve 14a.
The heating expansion valve 14a and the cooling expansion valve 14b have (a) a full-open function of fully opening a valve opening degree to function as a refrigerant passage almost without exerting flow rate control effects and refrigerant decompression effects, and (b) a full-close function of fully closing the valve opening degree to obstruct the refrigerant passage.
The heating expansion valve 14a and the cooling expansion valve 14b are capable of switching the refrigerant circuit in the respective operation mode, through the full-open function and the full-close function.
Therefore, the heating expansion valve 14a and the cooling expansion valve 14b of the present embodiment also have a function as a refrigerant circuit switcher. The operations of the heating expansion valve 14a and the cooling expansion valve 14b are controlled by control signals (i.e., control pulse) output from the controller 60.
A refrigerant inlet side of an outside heat exchanger 16 is connected to an outlet port of the heating expansion valve 14a. The outside heat exchanger 16 is a heat exchanger which performs heat exchange between (i) the refrigerant discharged from the heating expansion valve 14a and (ii) an outside air blown by a cooling fan (not shown). The outside heat exchanger 16 is arranged on a front side within an inside of a drive device compartment. Therefore, traveling wind can be applied to the outside heat exchanger 16 when the vehicle is traveling.
The refrigerant outlet port of the outside heat exchanger 16 is connected to an inlet side of a third three-way joint 13c which includes three inflow/outflow ports in fluid communication with each other. As such a three-way joint, a three-way joint formed by joining a plurality of pipes, or a three-way joint formed by providing a plurality of refrigerant passages in a metal block or a resin block is adoptable.
One inlet port of a fourth three-way joint 13d is connected to one outlet port of the third three-way joint 13c via a heating passage 22b. A basic configuration of the fourth three-way joint 13d is the same as that of the first three-way joint 13c. A heating open-close valve 15b is arranged in the heating passage 22b. The heating open-close valve 15b is an electromagnetic valve that opens and closes the heating passage 22b.
The heating open-close valve 15b can switch refrigerant circuits corresponding to various operation modes by opening and closing the refrigerant passage. Therefore, the heating open-close valve 15b is a refrigerant circuit switcher for switching the refrigerant circuit of the cycle. The operation of the heating open-close valve 15b is controlled by a control voltage output from the controller 60.
An inlet side of the cooling expansion valve 14b is connected to other outlet port of the third three-way joint 13c. The cooling expansion valve 14b is a cooling decompressor, which decompresses the refrigerant flowing out from the outside heat exchanger 16, and simultaneously adjusts a flow amount of the refrigerant flowing out to a downstream side, in an operation mode for cooling at least the vehicle compartment.
A refrigerant inlet side of an in-compartment evaporator 18 is connected to an outlet port of the cooling expansion valve 14b. The in-compartment evaporator 18 is arranged in an air conditioning case 31 of the in-compartment air-conditioning unit 30. The in-compartment evaporator 18 is a cooling heat exchanger to cool air by (a) evaporating low-pressure refrigerant by exchanging heat between the low-pressure refrigerant decompressed by the cooling expansion valve 14b and the air blown by a blower 32, and (b) causing the low-pressure refrigerant to exert heat absorbing effects. A refrigerant outlet port of the in-compartment evaporator 18 is connected to other inflow port of the fourth three-way joint 13d. An inlet side of an accumulator 21 is connected to an outlet port of the fourth three-way joint 13d. The accumulator 21 is a gas-liquid separator that separates gas and liquid of the refrigerant flowing into the accumulator 21, and stores therein surplus liquid-phase refrigerant of the cycle. A gas-phase refrigerant outlet port of the accumulator 21 is connected to a suction port side of the compressor 11.
The refrigeration cycle device 10 configures an accumulator cycle having the accumulator 21.
Next, the high-temperature-side thermal medium circuit 40 is described. The high-temperature-side thermal medium circuit 40 is a thermal medium circulation circuit for circulating a high-temperature-side thermal medium. As the high-temperature side thermal medium, a solution, an antifreeze and the like, containing ethylene glycol, dimethylpolysiloxane, nanofluid, or the like, may be adoptable. In the high-temperature-side thermal medium circuit 40, a water passage of the water-refrigerant heat exchanger 12, a high-temperature-side thermal medium pump 41, a heater core 42, and the like are arranged.
The high-temperature-side thermal medium pump 41 is a water pump which pumps the high-temperature-side thermal medium to an inlet side of the water passage of the water-refrigerant heat exchanger 12. The high-temperature-side thermal medium pump 41 is an electric pump in which a rotation speed (that is, a pumping capacity) is controlled by a control voltage output from the controller 60.
Further, a thermal medium inlet side of the heater core 42 is connected to an outlet port of the water passage of the water-refrigerant heat exchanger 12. The heater core 42 is a heat exchanger which performs, for heating air, heat exchange between (a) the high-temperature-side thermal medium heated by the water-refrigerant heat exchanger 12 and (b) air passing through the in-compartment evaporator 18. The heater core 42 is arranged in the air conditioning case 31 of the in-compartment air-conditioning unit 30. A suction port side of the high-temperature-side thermal medium pump 41 is connected to a thermal medium outlet port of the heater core 42.
Therefore, in the high-temperature-side thermal medium circuit 40, the high-temperature-side thermal medium pump 41 adjusts an amount of heat dissipated from the high-temperature-side thermal medium in the heater core 42 to air, i.e., an amount of heat that heats air in the heater core 42, by adjusting a flow rate of the high-temperature-side thermal medium flowing into the heater core 42.
That is, in the present embodiment, a heater unit is constituted by each of the components of the water-refrigerant heat exchanger 12 and the high-temperature-side thermal medium circuit 40, for heating the air using the refrigerant discharged from the compressor 11 as a heat source.
Next, the in-compartment air-conditioning unit 30 is described. The in-compartment air-conditioning unit 30 is provided for blowing, into the vehicle compartment, air whose temperature has been adjusted by the refrigeration cycle device 10. The in-compartment air-conditioning unit 30 is arranged inside an instrument panel at a frontmost part of the vehicle compartment.
As shown in
The air conditioning case 31 forms an air passage of air to be blown into the vehicle compartment. The air conditioning case 31 is formed of a resin (e.g., Polypropylene) having a certain degree of elasticity and also excellent in strength.
An inside-outside air switcher 33 is arranged on an air flow most upstream side of the air conditioning case 31. The inside-outside air switcher 33 switches and introduces inside air (i.e., air within the vehicle compartment) and outside air (i.e., air outside the vehicle compartment) into the air conditioning case 31.
The inside-outside air switcher 33 continuously adjusts (i) an opening area size of an inside air introduction port through which the inside air is introduced into the air conditioning case 31 and (ii) an opening area size of an outside air introduction port through which the outside air is introduced into the air conditioning case 31 by using an inside-outside air switch door, to change an introduction ratio between an introduction air volume of the inside air to an introduction air volume of the outside air. The inside-outside air switch door is driven by an electric actuator for the inside-outside air switch door. Operation of the electric actuator is controlled by a control signal output from the controller 60.
The blower 32 is arranged on an air flow downstream side of the inside-outside air switcher 33. The blower 32 blows air sucked through the inside-outside air switcher 33 toward the vehicle compartment. The blower 32 is an electric blower in which a centrifugal multi-blade fan is driven by an electric motor. A rotation speed, i.e., an air blowing capacity, of the blower 32 is controlled by a control voltage output from the controller 60.
The in-compartment evaporator 18 and the heater core 42 are arranged on an air flow downstream side of the blower 32 in this written order with respect to the air flow. That is, the in-compartment evaporator 18 is arranged on an air flow upstream side of the heater core 42.
A cold-air bypass passage 35 in which air after passing through the in-compartment evaporator 18 flows while bypassing the heater core 42 is provided in the air conditioning case 31. An air-mix door 34 is arranged on (a) an air flow downstream side of the in-compartment evaporator 18 and (b) an air flow upstream side of the heater core 42.
The air-mix door 34 is an air-volume-ratio adjuster, which variably adjusts an air volume ratio between (a) an air volume passing through the heater core 42 and (b) an air volume passing through the cold-air bypass passage 35, among air having passed through the in-compartment evaporator 18. The air-mix door 34 is driven by an electric actuator for the air-mix door. Operation of the electric actuator is controlled by a control signal output from the controller 60.
A mixing space is arranged on an air flow downstream side of the heater core 42 and the cold-air bypass passage 35 in the air conditioning case 31. The mixing space is a space for mixing (a) air heated by the heater core 42 and (b) air not heated by passing through the cold-air bypass passage 35.
Further, an opening hole for blowing air, i.e., a conditioned air, mixed in the mixing space into the vehicle compartment which is a space to be air-conditioned is arranged in an air flow downstream portion of the air conditioning case 31.
As the opening hole, a face opening hole, a foot opening hole, and a defroster opening hole (any of them is not shown) are provided. The face opening hole is an opening hole for blowing a conditioned air toward an upper body of an occupant in the vehicle compartment. The foot opening hole is an opening hole for blowing the conditioned air toward a foot of the occupant. The defroster opening hole is an opening hole for blowing the conditioned air toward an inner surface of window glass at a vehicle front part.
The face opening hole, the foot opening hole, and the defroster opening hole are respectively connected to a face outlet port, a foot outlet port, and a defroster outlet port (none of which is shown) provided in the vehicle compartment through ducts defining air passages.
Therefore, temperature of the conditioned air mixed in the mixing space is adjusted by adjusting, by using the air-mix door 34, an air volume ratio between (a) an air volume passing through the heater core 42 and (b) an air volume passing through the cold-air bypass passage 35, Then, temperature of the air (i.e., conditioned air) to be blown from each outlet port into the vehicle compartment is adjusted.
On an upstream side of the air flow regarding the face opening hole, the foot opening hole, and the defroster opening hole, a face door, a foot door, and a defroster door (none of which is shown) are arranged, respectively. The face door adjusts an opening area size of the face opening hole. The foot door adjusts an opening area size of the foot opening hole. The defroster door adjusts an opening area size of the defroster opening hole.
The face door, the foot door, and the defroster door constitute an outlet mode switching device which switches outlet modes. These doors are coupled to an electric actuator for driving an outlet mode door via a link mechanism or the like, and are operated to rotate in conjunction therewith. The operation of the electric actuator for driving the outlet mode door is controlled by a control signal output from the controller 60.
Specific examples of the outlet mode to be switched by the outlet mode switching device include a face mode, a bi-level mode, a foot mode and the like.
The face mode is an outlet mode in which the face outlet port is fully opened to blow air from the face outlet port toward the upper body of an occupant in the vehicle compartment. The bi-level mode is an outlet mode in which both the face outlet port and the foot outlet port are opened to blow air toward the upper body and the foot of the occupant in the vehicle compartment. The foot mode is an outlet mode in which the foot outlet port is fully opened and the defroster outlet port is opened by a small opening degree to blow air mainly from the foot outlet port.
Further, the occupant can manually operate the outlet mode switch provided on an operation panel 70 to switch to the defroster mode. The defroster mode is an outlet mode in which the defroster outlet port is fully opened to blow air from the defroster outlet port to an inner surface of a front window glass.
Next, the outline of a controller of the present embodiment is described. The controller 60 includes a known microcomputer including a CPU, a ROM, and a RAM, and a peripheral circuit of the microcomputer. The controller 60 performs various calculations and processes based on an air-conditioning control program stored in the ROM, and controls the operations of the various control target devices 11, 14a, 14b, 15b, 32, 41, and so on connected to an output side of the controller 60.
To an input side of the controller 60, as shown in a block diagram of
The inside air temperature sensor 61 is an inside air temperature detector that detects vehicle compartment temperature (i.e., room temperature) Tr. The outside air temperature sensor 62 is an outside air temperature detector that detects outside vehicle compartment temperature (i.e., ambient temperature) Tam. The solar radiation sensor 63 is a solar radiation amount detector that detects a solar radiation amount Ts radiated into the vehicle compartment.
The first refrigerant temperature sensor 64a is a discharged refrigerant temperature detector that detects temperature T1 of the refrigerant discharged from the compressor 11. The second refrigerant temperature sensor 64b is a second refrigerant temperature detector that detects temperature T2 of the refrigerant discharged from the refrigerant passage of the water-refrigerant heat exchanger 12. The third refrigerant temperature sensor 64c is a third refrigerant temperature detector that detects temperature T3 of the refrigerant that has flowed out of the outside heat exchanger 16.
The fourth refrigerant temperature sensor 64d is a fourth refrigerant temperature detector that detects temperature T4 of the refrigerant that has flowed out of the in-compartment evaporator 18. The fifth refrigerant temperature sensor 64e is a fifth refrigerant temperature detector that detects temperature T5 of the refrigerant that has flowed out from the accumulator 21.
The evaporator temperature sensor 64f is an evaporator temperature detector that detects refrigerant evaporation temperature (i.e., evaporator temperature) Tefin in the in-compartment evaporator 18. The evaporator temperature sensor 64f of the present embodiment specifically detects a heat exchange fin temperature of the in-compartment evaporator 18.
The first refrigerant pressure sensor 65a is a first refrigerant pressure detector which detects a pressure P1 of the refrigerant that has flowed out from the refrigerant passage of the water-refrigerant heat exchanger 12. The second refrigerant pressure sensor 65b is a second refrigerant pressure detector that detects a pressure P2 of the refrigerant that has flowed out from the accumulator 21.
The fifth refrigerant temperature sensor 64e and the second refrigerant pressure sensor 65b are refrigerant state detectors that detect the temperature T5 and the pressure P2 of the refrigerant downstream of the accumulator 21 and on the suction side of the compressor 11, in order to calculate the degree of superheat of the refrigerant downstream of the accumulator 21 and on the suction side of the compressor 11.
The high-temperature-side thermal medium temperature sensor 66a is a high-temperature-side thermal medium temperature detector that detects high-temperature-side thermal medium temperature TWH, which is temperature of the high-temperature-side thermal medium flowing out from the water passage of the water-refrigerant heat exchanger 12.
The conditioned-air temperature sensor 69 is a conditioned air temperature detector detecting an air temperature TAV of the air blown from the mixing space into the vehicle compartment.
Further, as shown in
Specific examples of the various operation switches provided on the operation panel 70 include an automatic switch which sets or cancels automatic control operation of the vehicle air conditioner, an air-conditioner switch which requests for cooling of air by the in-compartment evaporator 18, an air volume setting switch which manually sets an air volume of the blower 32, a temperature setting switch which sets a target temperature Tset in the vehicle compartment, an outlet mode selector switch which manually sets an outlet mode, and the like.
Note that, the controller 60 according to the present embodiment is a device which includes, in one body, a control unit or units for controlling various control target devices, which are connected to an output side of the controller 60, but a configuration for controlling the operation of each of the control target devices (hardware and software) serves as a control unit for controlling the operation of each of the control target devices.
For example, in the controller 60, a configuration that controls a refrigerant discharge capacity of the compressor 11 (specifically, the rotation speed of the compressor 11) constitutes a compressor control unit 60a. A configuration for controlling the operation of the heating expansion valve 14a and the cooling expansion valve 14b constitutes an expansion valve control unit 60b. A configuration for controlling the operation of the heating open-close valve 15b constitutes a refrigerant circuit switching control unit 60c. A configuration for controlling a pumping capacity of the high-temperature-side thermal medium by the high-temperature-side thermal medium pump 41 constitutes a high-temperature-side thermal medium pump control unit 60d.
Next, the operation of the present embodiment in the above-described configuration is described. In the refrigeration cycle device 10, operations in multiple operation modes are performable by switching the refrigerant circuit. For example, the multiple operation modes including operation in a cooling mode and in a heating mode are performable.
The cooling mode is an operation mode in which the vehicle compartment is cooled by cooling air and blowing such air into the vehicle compartment. The heating mode is an operation mode in which the vehicle compartment is heated by heating air and blowing such air into the vehicle compartment.
These operation modes are switched by executing an air-conditioning control program. The air-conditioning control program is executed when an automatic switch of the operation panel 70 is turned on (switched ON) by an operation of an occupant and automatic control of the vehicle compartment is set.
The air-conditioning control program firstly reads the detection signal from the group of sensors and the operation signal of the operation panel 70 described above. Subsequently, a target outlet temperature TAO, which is a target temperature of the blown air blown into the vehicle compartment, is determined based on the detection signal and the operation signal read in the above. Specifically, the target outlet temperature TAO is calculated by the following formula F1.
TAO=Kset×Tset−Kr×Tr−Kam×Tam−Ks×Ts+C (F1)
Tset is vehicle compartment set temperature set by the temperature setting switch. Tr is vehicle compartment temperature detected by the inside air temperature sensor 61. Tam is outside vehicle compartment temperature detected by the outside air temperature sensor 62. Ts is an amount of solar radiation detected by the solar radiation sensor 63. Kset, Kr, Kam, and Ks are control gains respectively, and C is a constant for correction.
Next, it is determined whether or not the air conditioning switch is ON (i.e., switched ON). The fact that the air conditioning switch is ON means that the occupant has requested cooling or dehumidification of the vehicle compartment. In other words, turning ON of the air conditioning switch means that cooling of the blown air by the in-compartment evaporator 18 is requested.
When it is determined that the air conditioning switch is ON, the cooling mode is selected as the operation mode. When it is determined that the air conditioning switch is not ON, the heating mode is selected as the operation mode.
In the air-conditioning control program of the present embodiment, the operation mode of the refrigeration cycle device 10 is switched as described above. Further, the air-conditioning control program controls not only the operation of each component of the refrigeration cycle device 10, but also the operation of the high-temperature-side thermal medium pump 41 of the high-temperature-side thermal medium circuit 40.
Specifically, the controller 60 controls the operation of the high-temperature-side thermal medium pump 41, for exerting a reference pumping capacity for each of the predetermined operation modes, regardless of the operation mode of the refrigeration cycle device 10 described above.
Therefore, in the high-temperature-side thermal medium circuit 40, when the high-temperature-side thermal medium is heated in the water passage of the water-refrigerant heat exchanger 12, the heated high-temperature-side thermal medium is pumped to the heater core 42. The high-temperature-side thermal medium flowing into the heater core 42 exchanges heat with air. The air is heated according to the above-described manner. The high-temperature-side thermal medium flowing out from the heater core 42 is sucked into the high-temperature-side thermal medium pump 41, and is pumped to the water-refrigerant heat exchanger 12.
Detailed operation of the vehicle air conditioner 1 in each operation mode is described in the following. Control maps referred to in each operation mode described in the following are stored in advance in the controller 60 for each operation mode. The control maps corresponding to each operation mode may be equivalent to each other, or may be different from each other.
In the cooling mode, the controller 60 executes a control flow of the cooling mode shown in
In step S610, an increase/decrease amount ΔIVO of the rotation speed of the compressor 11 is determined. The increase/decrease amount ΔIVO is determined so that the evaporator temperature Tefin approaches the target evaporator temperature TEO by the feedback control method, based on a deviation between the target evaporator temperature TEO and the evaporator temperature Tefin detected by the evaporator temperature sensor 64f.
Subsequently, in step S630, a subroutine shown in
Firstly, in step S1000, a target subcooling degree SCOa of the refrigerant flowing out from the outside heat exchanger 16 is determined. The target subcooling degree SCOa is determined by referring to a control map, for example, based on the ambient temperature Tam. In the control map of the present embodiment, the target subcooling degree SCOa is determined so that a coefficient of performance (COP) of the cycle approaches a maximum value.
In step S1010, a first provisional increase/decrease amount ΔEVC1 of the opening degree of throttle of the cooling expansion valve 14b is determined. The first provisional increase/decrease amount ΔEVC1 is determined so that the subcooling degree SCa of the refrigerant on the outlet side of the outside heat exchanger 16 approaches the target subcooling degree SCOa by the feedback control method, based on a deviation between the target subcooling degree SCOa and a subcooling degree SCa of the refrigerant on the outlet side of the outside heat exchanger 16. The first provisional increase/decrease amount ΔEVC1 is an increase/decrease amount of an opening degree of throttle of the cooling expansion valve 14b during normal control.
The subcooling degree SCa of the refrigerant on the outlet side of the outside heat exchanger 16 is calculated based on the temperature T3 detected by the third refrigerant temperature sensor 64c and the pressure P1 detected by the first refrigerant pressure sensor 65a.
In step S1020, it is determined whether a degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 exceeds a predetermined degree of superheat αC. The degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 is calculated based on the temperature T5 detected by the fifth refrigerant temperature sensor 64e and the pressure P2 detected by the second refrigerant pressure sensor 65b.
The predetermined degree of superheat αC is a fixed value stored in advance in the controller 60. Even when the amount of refrigerant sealed in the refrigeration cycle device 10 decreases, by controlling the degree of superheat SHe to a value smaller than the predetermined degree of superheat αC, it is possible to suppress a situation in which it is difficult for the lubricating oil to return to the compressor 11.
When it is determined in step S1020 that the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 does not exceed the predetermined degree of superheat αC, the process proceeds to step S1030, in which a value of the increase/decrease amount ΔEVC of an opening degree of throttle of the cooling expansion valve 14b is set to the same value as the first provisional increase/decrease amount ΔEVC1, and the subroutine shown in
The opening degree increase/decrease amount ΔEVC of throttle of the cooling expansion valve 14b determined in step S1030 is an increase or decrease amount in the opening degree of throttle of the cooling expansion valve 14b during normal control (in other words, the first opening degree increase/decrease amount).
When it is determined in step S1020 that the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 exceeds the predetermined degree of superheat αC, the process proceeds to step S1040, where a target degree of superheat SHOe of the refrigerant flowing out from the in-compartment evaporator 18 is determined. The target degree of superheat SHOe is determined to be, for example, the same value as the predetermined degree of superheat αC used in step S1020.
In step S1050, a second provisional increase/decrease amount ΔEVC2 of an opening degree of throttle of the cooling expansion valve 14b is determined. The second provisional increase/decrease amount ΔEVC2 is determined so that the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18 approaches the target degree of superheat SHOe by the feedback control method, based on a deviation between the target degree of superheat SHOe and the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18.
The second provisional increase/decrease amount ΔEVC2 is an increase/decrease amount of an opening degree of throttle of the cooling expansion valve 14b that is capable of suppressing an increase in the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18.
In step S1060, the value of the opening degree increase/decrease amount ΔEVC of throttle of the cooling expansion valve 14b is determined to be a greater value among the first provisional increase/decrease amount ΔEVC1 and the second provisional increase/decrease amount ΔEVC2.
The opening degree increase/decrease amount ΔEVC of throttle of the cooling expansion valve 14b determined in step S1060 is an increase/decrease amount of the throttle opening of the cooling expansion valve 14b that is capable of suppressing an increase in the superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18 more than the increase during normal control (in other words, a second opening degree increase/decrease amount).
In step S1070, it is determined whether the opening degree EXPC of throttle of the cooling expansion valve 14b has reached an upper limit opening degree βC. When it is determined in step S1070 that the opening degree EXPC of throttle of the cooling expansion valve 14b has not reached the upper limit opening degree βC, the subroutine shown in
When it is determined in step S1070 that the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC, the process proceeds to step S1080, in which it is determined whether an elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds a predetermined time γC.
When it is determined in step S1080 that the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC does not exceed the predetermined time γC, the subroutine shown in
When it is determined in step S1080 that the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds the predetermined time γC, the process proceeds to step S1090, where it is determined that there is a shortage of refrigerant (specifically, gas-phase refrigerant), the compressor 11 is stopped, and the occupant is notified of the shortage of refrigerant visually or audibly, and the subroutine shown in
Subsequently, in step S640, an opening degree SW of the air-mix door 34 is calculated by using the following formula F2.
SW=[TAO+(Tefin+C2)]/[TWH+(Tefin+C2)] (F2)
TWH is a high-temperature-side thermal medium temperature detected by the high-temperature-side thermal medium temperature sensor 66a. C2 is a constant for control.
In step S650, in order to switch the refrigeration cycle device 10 to the refrigerant circuit in the cooling mode, the heating expansion valve 14a is fully opened, the cooling expansion valve 14b is put in a throttled state for exerting refrigerant decompression effects, and the heating open-close valve 15b is closed. Further, control signals or control voltages are output to each control target device so that the control state determined in steps S610, S630, and S640 is obtained.
Therefore, in the refrigeration cycle device 10 in the cooling mode, a steam compression type refrigeration cycle is configured, where the refrigerant circulates in an order of the compressor 11, the water-refrigerant heat exchanger 12, the heating expansion valve 14a, the outside heat exchanger 16, the cooling expansion valve 14b, the in-compartment evaporator 18, the accumulator 21, and the compressor 11.
That is, in the refrigeration cycle device 10 in the cooling mode, the steam compression type refrigeration cycle is configured in which the water-refrigerant heat exchanger 12 and the outside heat exchanger 16 function as a radiator which dissipates heat from the refrigerant discharged from the compressor 11, the first cooling expansion valve 14b functions as a decompressor which reduces the refrigerant pressure, and the in-compartment evaporator 18 functions as an evaporator.
According to the above, the in-compartment evaporator 18 can cool air, and the water-refrigerant heat exchanger 12 can heat the high-temperature-side thermal medium.
Therefore, the vehicle air conditioner 1 in the cooling mode can perform a cooling of the vehicle compartment (a) by reheating, by using the heater core 42, a part of the air cooled by the in-compartment evaporator 18 by adjusting the opening degree of the air-mix door 34, and (b) by blowing into the vehicle compartment the temperature-adjusted air, which is temperature-adjusted to approach the target outlet temperature TAO.
In the heating mode, the controller 60 executes a control flow of the heating mode shown in
In step S910, the increase/decrease amount ΔIVO of the rotation speed of the compressor 11 is determined. In the heating parallel cooling mode, the increase/decrease amount ΔIVO is determined so that the high-temperature-side thermal medium temperature TWH approaches the target high-temperature-side thermal medium temperature TWHO by the feedback control method, based on a deviation between the target high-temperature-side thermal medium temperature TWHO and the high-temperature-side thermal medium temperature TWH.
In step S930, a subroutine shown in
In step S2000, a target subcooling degree SCOc of the refrigerant flowing out from the refrigerant passage of the water-refrigerant heat exchanger 12 is determined. The target subcooling degree SCOc is determined by referring to a control map based on suction temperature of the air flowing into the water-refrigerant heat exchanger 12 or the ambient temperature Tam. In the control map of the present embodiment, the target subcooling degree SCOc is determined so that the coefficient of performance (COP) of the cycle approaches a maximum value.
In step S2010, a first provisional increase/decrease amount ΔEVH1 of an opening degree of throttle of the heating expansion valve 14a is determined. The first provisional increase/decrease amount ΔEVB is determined so that the subcooling degree SCc of the refrigerant on the outlet side of the water-refrigerant heat exchanger 12 approaches the target subcooling degree SCOc, by the feedback control method, based on a deviation between the target subcooling degree SCOc and the subcooling degree SCc of the refrigerant on the outlet side of the water-refrigerant heat exchanger 12.
The first provisional increase/decrease amount ΔEVH1 is an increase/decrease amount of an opening degree of throttle of the heating expansion valve 14a during normal control (in other words, the first opening degree increase/decrease amount).
The subcooling degree SCc of the refrigerant on the outlet side of the water-refrigerant heat exchanger 12 is calculated based on the temperature T2 detected by the second refrigerant temperature sensor 64b and the pressure P1 detected by the first refrigerant pressure sensor 65a.
In step S2020, it is determined whether the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 exceeds a predetermined degree of superheat αH. The degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 is calculated based on (i) the temperature T5 detected by the fifth refrigerant temperature sensor 64e and (ii) the pressure P2 detected by the second refrigerant pressure sensor 65b.
When it is determined in step S2020 that the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 does not exceed the predetermined degree of superheat αH, the process proceeds to step S2030, in which the value of the increase/decrease amount ΔEVH of the opening degree of throttling of the heating expansion valve 14a is set to the same value as the first provisional increase/decrease amount ΔEVH1, and the subroutine shown in
The increase/decrease amount ΔEVH of the opening degree of throttle of the heating expansion valve 14a determined in step S2030 is an increase/decrease amount of an opening degree of throttle of the heating expansion valve 14a during normal control (in other words, the first opening degree increase/decrease amount).
When it is determined in step S2020 that the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 exceeds the predetermined degree of superheat αH, the process proceeds to step S2040, where a target degree of superheat SHOa of the refrigerant flowing out from the outside heat exchanger 16 is determined. The target degree of superheat SHOa is determined to be, for example, the same value as the predetermined degree of superheat αH used in step S2020.
In step S2050, the second provisional increase/decrease amount ΔEVH2 of the opening degree of throttle of the heating expansion valve 14a is determined. The second provisional increase/decrease amount ΔEVH2 is determined so that the degree of superheat SHa of the refrigerant on the outlet side of the outside heat exchanger 16 approaches the target degree of superheat SHOa, by the feedback control method, based on a deviation between the target degree of superheat SHOa and the degree of superheat SHa of the refrigerant on the outlet side of the outside heat exchanger 16.
The second provisional increase/decrease amount ΔEVH2 is an increase/decrease amount of an opening degree of throttle of the heating expansion valve 14a that is capable of suppressing an increase in the degree of superheat SHa of the refrigerant on the outlet side of the exterior heat exchanger 16 (in other words, a second opening degree increase/decrease amount), In step S2060, the value of the increase/decrease amount ΔEVH of the opening degree of throttle of the heating expansion valve 14a is determined to be a greater value among the first provisional increase/decrease amount ΔEVH1 and the second provisional increase/decrease amount ΔEVH2.
The increase/decrease amount ΔEVH of the opening degree of throttle of the heating expansion valve 14a determined in step S2060 is an increase/decrease amount of the opening degree of throttle of the heating expansion valve 14a that is capable of suppressing an increase in the degree of superheat SHa of the refrigerant on the outlet side of the outside heat exchanger 16 more than during normal control (in other words, the second opening degree increase/decrease amount).
In step S2070, it is determined whether an opening degree EXPH of throttle of the heating expansion valve 14a has reached an upper limit opening degree pH. When it is determined in step S2070 that the opening degree EXPH of throttle of the heating expansion valve 14a has not reached the upper limit opening degree pH, the subroutine shown in
When it is determined in step S2070 that the opening degree EXPH of throttle of the heating expansion valve 14a has reached the upper limit opening degree βH, the process proceeds to step S2080, in which it is determined whether an elapsed time nH since the opening degree EXPH of throttle of the heating expansion valve 14a has reached the upper limit opening degree βH exceeds a predetermined time γH.
When it is determined in step S2080 that the elapsed time nH since the opening degree EXPH of throttle of the heating expansion valve 14a has reached the upper limit opening degree pH does not exceed the predetermined time γH, the subroutine shown in
When it is determined in step S2080 that the elapsed time nH since the opening degree EXPH of throttle of the heating expansion valve 14a has reached the upper limit opening degree pH exceeds the predetermined time γH, the process proceeds to step S2090, where it is determined that there is a shortage of refrigerant, the compressor 11 is stopped, and the occupant is notified of the shortage of refrigerant visually or audibly, and the subroutine shown in
In step S940, the opening degree SW of the air-mix door 34 is calculated similar to the cooling mode. Here, in the heating mode, since the target outlet temperature TAO is higher than that in the cooling mode, the opening degree SW of the air-mix door 34 approaches 100%. Therefore, in the heating mode, the opening degree of the air-mix door 34 is determined such that substantially the entire flow rate of the air having passed through the in-compartment evaporator 18 passes through the heater core 42.
In step S950, in order to switch the refrigeration cycle device 10 to a refrigerant circuit in the heating mode, the heating expansion valve 14a is put in a throttled back state, the cooling expansion valve 14b is put in a fully-closed state, and the heating open-close valve 15b is opened. Further, control signals or control voltages are output to each control target device so that the control state determined in steps S910, S930, and S940 is obtained.
Therefore, in the refrigeration cycle device 10 in the heating mode, a steam compression type refrigeration cycle is configured, wherein the refrigerant circulates in an order of the compressor 11, the water-refrigerant heat exchanger 12, the heating expansion valve 14a, the outside heat exchanger 16, the heating passage 22b, the accumulator 21, and the compressor 11.
That is, in the refrigeration cycle device 10 in the heating mode, the refrigeration cycle is configured in such a manner that the water-refrigerant heat exchanger 12 functions as a radiator that dissipates heat from the refrigerant discharged from the compressor 11, the heating expansion valve 14a functions as a decompressor, and the outside heat exchanger 16 functions as an evaporator.
According to the above, it is possible to heat the high-temperature-side thermal medium in the water-refrigerant heat exchanger 12. Therefore, in the vehicle air conditioner 1 in the heating mode, heating of the vehicle compartment is performable by blowing air heated by the heater core 42 into the vehicle compartment.
As described above, in the refrigeration cycle device 10 of the present embodiment, various operation modes are switchable. In such manner, the vehicle air conditioner 1 can realize comfortable air-conditioning in the vehicle compartment.
When the amount of refrigerant sealed in the refrigeration cycle device 10 is equal to or greater than the required amount of refrigerant, normal control is performed. That is, the opening of throttle of the cooling expansion valve 14b is controlled so that a degree of subcooling SCa of the refrigerant on the outlet side of the outside heat exchanger 16 approaches a target degree of subcooling SCOa. Specifically, as described in step S1030, the increase/decrease amount ΔEVC of the opening degree of throttle of the cooling expansion valve 14b is determined to be first provisional increase/decrease amount ΔEVC1 (i.e., first opening degree increase/decrease amount ΔEVC1).
As the amount of refrigerant sealed in the refrigeration cycle device 10 decreases, the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 increases. When the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 exceeds a predetermined degree of superheat αC, the opening degree EXPC of throttle of the cooling expansion valve 14b is made greater than the value for normal control so that the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 does not exceed the target degree of superheat SHOe. Specifically, as described in step S1060, the increase/decrease amount ΔEVC of the opening degree of throttle of the cooling expansion valve 14b is determined to be the second provisional increase/decrease amount ΔEVC2 (i.e., second opening degree increase/decrease amount ΔEVC2).
In such manner, the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 is suppressed from increasing significantly, thereby (i) suppressing a decrease in the amount of refrigerant dissolved in the lubricating oil and (ii) suppressing a situation in which it is difficult for the lubricating oil to return to the compressor 11.
When the amount of refrigerant sealed in the refrigeration cycle device 10 further decreases and the opening degree EXPC of throttle of the cooling expansion valve 14b reaches the upper limit opening degree βC, the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 increases significantly, thereby making it difficult for the lubricating oil to return to the compressor 11.
Therefore, as explained in steps S1080 to S1090, when the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds a predetermined time γC, it is determined that a shortage of refrigerant has occurred, and the compressor 11 is stopped. In such manner, it is possible to protect the compressor 11 from a situation in which it is difficult for the lubricating oil to return to the compressor 11.
A shortage of refrigerant is not immediately determined as occurring when the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC, but is determined as occurring when the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds a predetermined time γC, thereby making it possible to prevent a determination that a shortage of refrigerant has occurred when the degree of superheat SHe increases transiently due to load fluctuation or the like. Therefore, erroneous determination of a shortage of refrigerant is suppressible.
In the cooling mode of the present embodiment, as described in step S630, when the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 is equal to or lower than the predetermined degree of superheat αC, the controller 60 determines the opening degree increase/decrease amount ΔEVC of the cooling expansion valve 14b to be the first opening degree increase/decrease amount ΔEVC1. When the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 exceeds the predetermined degree of superheat αC, the controller 60 determines the opening degree increase/decrease amount ΔEVC of the cooling expansion valve 14b to be the second opening increase/decrease amount ΔEVC2 that is more capable of suppressing the increase in the degree of superheat SHe than the first opening degree increase/decrease amount ΔEVC1.
According to the above, when the amount of refrigerant decreases and the degree of superheat SHe of the refrigerant increases, a further increase in the degree of superheat SHe of the refrigerant is suppressible. Therefore, it is possible to suppress a situation in which it is difficult for the lubricating oil to return to the compressor 11 due to a decrease in the amount of refrigerant dissolved in the lubricating oil.
In the cooling mode of the present embodiment, the first opening degree increase/decrease amount ΔEVC1 of the cooling expansion valve 14b is a value determined so as to bring the degree of subcooling SCa of the refrigerant from which heat is dissipated in the outside heat exchanger 16 closer to the target degree of subcooling SCOa, and the second opening degree increase/decrease amount ΔEVC2 of the cooling expansion valve 14b is a value determined so as to bring the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 closer to the target degree of superheat SHOe.
According to the above, in the cooling mode of the accumulator cycle equipped with the accumulator 21, when the amount of refrigerant is not decreasing, the accumulator cycle is appropriately controllable by appropriately controlling the degree of subcooling SCa of the refrigerant, and when the amount of refrigerant decreases, it is possible to suppress a situation in which it is difficult for the lubricating oil to return to the compressor 11.
In the cooling mode of the present embodiment, the controller 60 determines a shortage of refrigerant when the opening degree EXPC of the cooling expansion valve 14b reaches the upper limit opening degree βC.
According to the above, a shortage of refrigerant is determined when the increase in the opening degree EXPC of the cooling expansion valve 14b accompanying a decrease in the amount of refrigerant reaches its limit, thereby a shortage of refrigerant is more accurately determinable than when a shortage of refrigerant is determined based on the pressure of refrigerant.
In the cooling mode of the present embodiment, the controller 60 determines a shortage of refrigerant when (a) the opening degree EXPC of the cooling expansion valve 14b reaches the upper limit opening degree βC and (b) the elapsed time nC since the opening degree EXPC of the cooling expansion valve 14b reaches the upper limit opening degree βC exceeds the predetermined time γC.
In such manner, it is possible to prevent a determination that there is a shortage of refrigerant when the degree of superheat SHe increases transiently due to load fluctuation or the like. Therefore, erroneous determination of a shortage of refrigerant is suppressible.
In the cooling mode of the present embodiment, the controller 60 stops the compressor 11 when it is determined that a shortage of refrigerant is caused. In such manner, it is possible to protect the compressor 11 when a shortage of refrigerant is caused.
In the cooling mode of the present embodiment, the fifth refrigerant temperature sensor 64e and the second refrigerant pressure sensor 65b detect the temperature T5 and pressure P2 of the refrigerant downstream of the accumulator 21 and on the suction side of the compressor 11, and the controller 60 calculates the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 by using the refrigerant temperature and pressure detected by the fifth refrigerant temperature sensor 64e and the second refrigerant pressure sensor 65b.
According to the above, since the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 is highly accurately detectable, a shortage of refrigerant is highly accurately determinable.
In the heating mode of the present embodiment, as described in step S930, when the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 is equal to or lower than the predetermined degree of superheat αH, the controller 60 determines the opening degree increase/decrease amount ΔEVH of the heating expansion valve 14a to be the first opening degree increase/decrease amount ΔEVH1. When the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 exceeds the predetermined degree of superheat αH, the controller 60 determines the opening degree increase/decrease amount ΔEVH of the heating expansion valve 14a to be the second opening increase/decrease amount ΔEVH2 that is more capable of suppressing the increase in the degree of superheat SHa than the first opening degree increase/decrease amount ΔEVH1.
According to the above, when the amount of refrigerant decreases and the degree of superheat SHa of the refrigerant increases, a further increase in the degree of superheat SHa of the refrigerant is suppressible. Therefore, it is possible to suppress a situation in which it is difficult for the lubricating oil to return to the compressor 11 due to a decrease in the amount of refrigerant dissolved in the lubricating oil.
In the heating mode of the present embodiment, the first opening degree increase/decrease amount ΔEVH1 of the heating expansion valve 14a is a value determined so as to bring the degree of subcooling SCc of the refrigerant from which heat is dissipated in the water-refrigerant heat exchanger 12 closer to the target degree of subcooling SCOc, and the second opening degree increase/decrease amount ΔEVH2 of the heating expansion valve 14a is a value determined so as to bring the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 closer to the target degree of superheat SHOa.
According to the above, in the heating mode of the accumulator cycle equipped with the accumulator 21, when the amount of refrigerant is not decreasing, the accumulator cycle is appropriately controllable by appropriately controlling the degree of subcooling SCc of the refrigerant, and when the amount of refrigerant has decreased, it is possible to suppress a situation in which it is difficult for the lubricating oil to return to the compressor 11.
In the heating mode of the present embodiment, the controller 60 determines a shortage of refrigerant when the opening degree EXPH of the heating expansion valve 14a reaches the upper limit opening degree βH.
According to the above, a shortage of refrigerant is determined when the increase in the opening degree EXPH of the heating expansion valve 14a due to a decrease in the amount of refrigerant reaches its limit, thereby a shortage of refrigerant is more accurately determinable than when a shortage of refrigerant is determined based on the pressure of refrigerant.
In the heating mode of the present embodiment, the controller 60 determines a shortage of refrigerant when the opening degree EXPH of the heating expansion valve 14a has reached the upper limit opening degree βH, and the elapsed time nH since the opening degree EXPH of the heating expansion valve 14a has reached the upper limit opening degree βH exceeds the predetermined time γH.
In such manner, it is possible to prevent a determination that there is a shortage of refrigerant when the degree of superheat SHa increases transiently due to load fluctuation or the like. Therefore, erroneous determination of a shortage of refrigerant is suppressible.
In the heating mode of the present embodiment, when it is determined that a shortage of refrigerant is caused, the controller 60 stops the compressor 11. In such manner, it is possible to protect the compressor 11 when a shortage of refrigerant is caused.
In the heating mode of the present embodiment, the fifth refrigerant temperature sensor 64e and the second refrigerant pressure sensor 65b detect the temperature T5 and pressure P2 of the refrigerant downstream of the accumulator 21 and on the suction side of the compressor 11, and the controller 60 calculates the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 by using the refrigerant temperature and pressure detected by the fifth refrigerant temperature sensor 64e and the second refrigerant pressure sensor 65b.
According to the above, the degree of superheat SHa of the refrigerant flowing out from the outside heat exchanger 16 is highly accurately detectable, thereby a shortage of refrigerant is highly accurately determinable.
In the first embodiment, the refrigeration cycle device 10 configures an accumulator cycle having the accumulator 21. In the present embodiment, as shown in
The receiver 25 is a high-pressure-side gas-liquid separator that separates gas and liquid from a refrigerant flowing thereinto, and stores the separated liquid-phase refrigerant as an excess refrigerant in the cycle. An inlet side of the receiver 25 is connected to a refrigerant outlet side of an outside heat exchanger 16. A refrigerant inlet side of a cooling expansion valve 14b is connected to a liquid-phase refrigerant outlet port of the receiver 25.
The refrigeration cycle device 10 of the present embodiment is provided with an electric heater 26 in place of a water-refrigerant heat exchanger 12 in the above-described first embodiment. The electric heater 26 is a heater unit that generates heat when electric power is supplied thereto and heats the high-temperature-side thermal medium.
The vehicle air conditioner 1 of the present embodiment can operate in the cooling mode. The basic operation of the vehicle air conditioner 1 in the cooling mode of the present embodiment is similar to that of the first embodiment.
In the present embodiment, in step S630 in the cooling mode, a subroutine shown in
First, in step S3000, a first target degree of superheat SHOe1 of the refrigerant flowing out from an in-compartment evaporator 18 is determined. The first target degree of superheat SHOe1 is determined, for example, based on the temperature of a sucked air flowing into the in-compartment evaporator 18 with reference to a control map. In the control map of the present embodiment, the first target degree of superheat SHOe1 is determined so that the coefficient of performance (COP) of the cycle approaches a maximum value.
In step S3010, a first provisional increase/decrease amount ΔEVC1 of an opening degree of throttle of the cooling expansion valve 14b is determined. The first provisional increase/decrease amount ΔEVC1 is determined so that the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18 approaches the target degree of superheat SHOe1 by the feedback control method, based on a deviation between the target degree of superheat SHOe1 and the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18. The first provisional increase/decrease amount ΔEVC1 is an increase/decrease amount of an opening degree of throttle of the cooling expansion valve 14b during normal control (in other words, the first opening degree increase/decrease amount).
In step S3020, it is determined whether the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 exceeds a predetermined degree of superheat αC. When it is determined in step S3020 that the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 does not exceed the predetermined degree of superheat αC, the process proceeds to step S3030, in which the value of the increase/decrease amount ΔEVC of the opening degree of throttle of the cooling expansion valve 14b is determined to be the same as the first provisional increase/decrease amount ΔEVC1, and the subroutine shown in
The increase/decrease amount ΔEVC of the opening degree of throttle of the cooling expansion valve 14b determined in step S3030 is an increase or decrease amount in the opening degree of throttle of the cooling expansion valve 14b during normal control (in other words, the first opening degree increase/decrease amount).
When it is determined in step S3020 that the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 exceeds the predetermined degree of superheat αC, the process proceeds to step S3040, where a second target degree of superheat SHOe2 of the refrigerant flowing out from the in-compartment evaporator 18 is determined. The second target degree of superheat SHOe2 is determined to be, for example, the same value as the predetermined degree of superheat αC used in step S3020.
In step S3050, a second provisional increase/decrease amount ΔEVC2 of the opening degree of throttle of the cooling expansion valve 14b is determined. The second provisional increase/decrease amount ΔEVC2 is determined so that the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18 approaches the second target degree of superheat SHOe2 by the feedback control method, based on a deviation between the second target degree of superheat SHOe2 and the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18.
The second provisional increase/decrease amount ΔEVC2 is an increase/decrease amount of an opening degree of throttle of the cooling expansion valve 14b that is capable of suppressing an increase in the degree of superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18 (in other words, the second opening degree increase/decrease amount).
In step S3060, the value of the increase/decrease amount ΔEVC in the opening degree of throttle of the cooling expansion valve 14b is determined to be a greater value among the first provisional increase/decrease amount ΔEVC1 and the second provisional increase/decrease amount ΔEVC2.
The increase/decrease amount ΔEVC in the opening degree of throttle of the cooling expansion valve 14b determined in step S3060 is an increase/decrease amount in the opening degree of throttle of the cooling expansion valve 14b that is more capable of suppressing the increase in the superheat SHe of the refrigerant on the outlet side of the in-compartment evaporator 18 than during normal control (in other words, the second opening degree increase/decrease amount).
In step S3070, it is determined whether an opening degree EXPC of throttle of the cooling expansion valve 14b has reached an upper limit opening degree βC. When it is determined in step S3070 that the opening degree EXPC of throttle of the cooling expansion valve 14b has not reached the upper limit opening degree βC, the subroutine shown in
When it is determined in step S3070 that the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC, the process proceeds to step S3080, in which it is determined whether an elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds a predetermined time γC.
When it is determined in step S3080 that the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC does not exceed the predetermined time γC, the subroutine shown in
When it is determined in step S3080 that the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds the predetermined time γC, the process proceeds to step S3090, where it is determined that there is a shortage of refrigerant, the compressor 11 is stopped, and the occupant is notified of a shortage of refrigerant visually or audibly, and the subroutine shown in
As the amount of refrigerant sealed in the refrigeration cycle device 10 decreases, the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 increases beyond the first target degree of superheat SHOe1. When the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 exceeds the predetermined degree of superheat αC, the opening degree EXPC of throttle of the cooling expansion valve 14b is made greater than the value for normal control so that the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 does not exceed the second target degree of superheat SHOe2. Specifically, as described in step S3060, the increase/decrease amount ΔEVC of the opening degree of throttle of the cooling expansion valve 14b is determined to be the second opening degree increase/decrease amount ΔEVC2.
In such manner, the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 is suppressed from increasing significantly, thereby (i) suppressing a decrease in the amount of refrigerant dissolved in the lubricating oil and (ii) suppressing a situation in which it is difficult for the lubricating oil to return to the compressor 11.
When the amount of refrigerant sealed in the refrigeration cycle device 10 further decreases and the opening degree EXPC of throttle of the cooling expansion valve 14b reaches the upper limit opening degree βC, the degree of superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 increases significantly, thereby making it difficult for the lubricating oil to return to the compressor 11. Therefore, when the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds the predetermined time γC, it is determined that a shortage of refrigerant is caused, and the compressor 11 is stopped. In such manner, it is possible to protect the compressor 11 from a situation in which it is difficult for the lubricating oil to return to the compressor 11.
A shortage of refrigerant is not immediately determined as occurring when the opening degree EXPC of throttle of the cooling expansion valve 14b reaches the upper limit opening degree βC, but is determined as occurring when the elapsed time nC since the opening degree EXPC of throttle of the cooling expansion valve 14b has reached the upper limit opening degree βC exceeds a predetermined time γC, thereby making it possible to prevent a determination that a shortage of refrigerant has occurred when the degree of superheat SHe increases transiently due to load fluctuation or the like. Therefore, erroneous determination of a shortage of refrigerant is suppressible.
In the cooling mode of the present embodiment, the first opening degree increase/decrease amount ΔEVC1 of the cooling expansion valve 14b is a value determined so as to bring the superheat SHe of the refrigerant flowing out from the in-compartment evaporator 18 closer to the first target degree of superheat SHOe1, and the second opening increase/decrease amount ΔEVC2 of the cooling expansion valve 14b is a value greater than the first opening degree increase/decrease amount ΔEVC1.
According to the above, in the cooling mode of the receiver cycle equipped with the receiver 25, when the amount of refrigerant is not decreasing, the receiver cycle is appropriately controllable by appropriately controlling the degree of superheat SHe of the refrigerant, and when the amount of refrigerant decreases, it is possible to prevent a situation in which it is difficult for the lubricating oil to return to the compressor 11.
The present disclosure is not limited to the embodiments described above, and various modifications can be made as follows within a range not departing from the spirit of the present disclosure.
In the above-described embodiment, the predetermined degrees of superheat αC, αH are fixed values stored in advance in the controller 60, but they do not necessarily have to be fixed values. For example, the predetermined degrees of superheat αC, αH may be varied depending on the operating environment, and the like.
In the above-described embodiment, the target degrees of superheat SHOe, SHOa, SHOe2 are determined to be the same values as the predetermined degrees of superheat αC, αH, but they do not necessarily have to be determined to be the same values. For example, the target degrees of superheat SHOe, SHOa, SHOe2 may be varied with respect to the predetermined degrees of superheat αC, αH depending on the operating environment, and the like.
Although the refrigeration cycle device 10 capable of switching to a plurality of operation modes has been described in the above-described embodiment, the switching of operation modes of the refrigeration cycle device 10 is not limited to the above.
For example, the mode may be switchable to a dehumidifying and heating mode in which a low-pressure refrigerant is evaporated by both of the outside heat exchanger 16 and the in-compartment evaporator 18 to cause the low-pressure refrigerant to absorb heat.
The configuration of the heater unit is not limited to those disclosed in the embodiments described above. For example, a radiator may be added to the high-temperature-side thermal medium circuit 40 described in the first embodiment to dissipate excess heat to the outside air. Further, in a vehicle including an internal combustion engine such as a hybrid vehicle, an engine cooling water may be circulated in the high-temperature-side thermal medium circuit 40.
In the refrigeration cycle device 10, a battery cooling heat exchanger that cools a battery may be arranged in parallel with the in-compartment evaporator 18.
Further, in the refrigeration cycle device 10, a chiller for cooling a low-temperature-side thermal medium may be provided, and the low-temperature-side thermal medium cooled by the chiller may be used to cool the cooling target object, such as a battery, an inverter, a motor generator and the like.
In each of the above-described embodiments, the refrigeration cycle device 10 according to the present disclosure is applied to the vehicle air conditioner 1, but the application of the refrigeration cycle device 10 is not limited to the above. For example, it may be applied to a device, such as an air-conditioner with a server cooling function for appropriately adjusting a temperature of a computer server while air-conditioning a room.
Although the present disclosure has been described according to the embodiments, it is understood that the present disclosure is not limited to the above-described embodiments or structures. The present disclosure includes various modification examples and equivalents thereof. In addition, various combinations and configurations, including one element added thereto, less than that or more than that, are also within the spirit and scope of the present disclosure.
The features of the refrigeration cycle device disclosed in the present specification may be suitably changed.
For example, a refrigeration cycle device may include: a compressor configured to suck, compress and discharge a refrigerant; a radiator configured to dissipate heat from the refrigerant that is discharged from the compressor; an expansion valve configured to decompress and expand the refrigerant flowing from the radiator; an evaporator configured to evaporate the refrigerant which has been decompressed and expanded by the expansion valve; an accumulator configured to separate the refrigerant evaporated in the evaporator into gas and liquid; and a controller configured to control an opening degree of the expansion valve. The controller includes at least one of a circuit and a processor having the memory, and is configured to: determine an increase/decrease amount of the opening degree of the expansion valve, to a first amount, when a superheat degree of the refrigerant flowing out from the evaporator is equal to or lower than a predetermined superheat degree; determine the increase/decrease amount of the opening degree of the expansion valve, to a second amount that is set to more suppress an increase of the superheat degree of the refrigerant flowing out from the evaporator, than that of the first amount, when the superheat degree of the refrigerant flowing out from the evaporator is higher than the predetermined superheat degree; determine the first amount to cause a subcooling degree of the refrigerant flowing out from the radiator closer to a target subcooling degree; and determine the second amount to cause the superheat degree of the refrigerant flowing out from the evaporator closer to a target superheat degree.
With this, the subcooling degree of the refrigerant flowing out from the radiator can be made closer to the target subcooling degree in accordance with the first amount, and the superheat degree of the refrigerant flowing out from the evaporator can be made closer to a target superheat degree in accordance with the second amount.
For example, the second amount is a value greater than that of the first amount. The controller may determine a shortage of the refrigerant when an opening degree of the expansion valve reaches an upper limit opening degree.
The controller may determine a shortage of the refrigerant, when an opening degree of the expansion valve reaches an upper limit opening degree and when an elapsed time since the opening degree of the expansion valve has reached the upper limit opening degree exceeds a predetermined time. The controller may stop the compressor when the controller determines that a shortage of the refrigerant is caused.
A refrigerant state detector may be provided to detect a temperature and a pressure of the refrigerant at a position downstream of the accumulator and on a suction side of the compressor. In this case, the controller calculates the superheat of the refrigerant flowing out from the evaporator, by using the temperature and the pressure of the refrigerant detected by the refrigerant state detector.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-127817 | Aug 2022 | JP | national |
The present application is a continuation application of International Patent Application No. PCT/JP2023/025841 filed on Jul. 13, 2023, which designated the U.S. and claims the benefit of priority from Japanese Patent Application No. 2022-127817 filed on Aug. 10, 2022. The entire disclosures of all of the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/025841 | Jul 2023 | WO |
| Child | 19034345 | US |
