JP4557031B2 - Air conditioner for vehicles - Google Patents

Description

  The present invention relates to a refrigeration cycle apparatus using an electric compressor.

  Conventionally, in an electric compressor integrated with a compression mechanism and an electric motor that drives the compression mechanism, when the temperature of the inverter, the electric motor, etc. rises due to the high load state of the electric compressor, the temperature rise of the electric motor, etc. is avoided The temperature protection control to be performed is disclosed in Patent Documents 1 and 2, for example.

In Patent Document 1, the temperature of the electric motor is estimated by estimating the temperature of the electric motor from the motor rotation speed of the electric compressor, the input current of the inverter, and the like, and stopping the compressor when the estimated temperature exceeds a predetermined value. The rise is avoided. Further, in Patent Document 2, in an electric compressor configured to cool an inverter having an electric motor drive circuit with a compressor suction refrigerant, the load on the compression mechanism is large and the torque to be generated by the electric motor is large. Nevertheless, in order to suppress the temperature rise of the inverter that occurs when the rotation speed of the electric compressor is low, the rotation speed of the electric motor is increased, the operation of the electric compressor is stopped, and the like.
JP 2006-291878 A JP 2005-248730 A

  However, in Patent Document 1, as a temperature protection control for avoiding a temperature rise of the electric motor, in order to stop the electric compressor, the refrigeration cycle apparatus including the electric compressor is applied to the vehicle air conditioner. There was a problem that the feeling of air conditioning in the passenger compartment deteriorated remarkably.

  Further, in Patent Document 2, the purpose is to protect the temperature of the inverter element, but in a situation where the temperature of the inverter rises, the current value input to the electric motor at the same time is high, so the amount of heat generated by the electric motor increases. The electric motor is also in a high temperature state. In this case, similarly to Patent Document 1, the electric compressor is stopped and the temperature protection control of the electric motor is performed, so the same problem as in Patent Document 1 occurs.

  An object of this invention is to perform the temperature protection control which avoids the temperature rise of the electric motor of an electric compressor, without stopping an electric compressor in view of the said point.

In order to achieve the above object, in the inventions according to claims 1 to 7 , the compression mechanism (11b) for sucking and compressing the refrigerant, the compression mechanism (11b) are driven and cooled by the refrigerant on the suction side of the compression mechanism (11b). An electric compressor (11) comprising a possible electric motor (11a), a variable throttle mechanism (12, 16) for depressurizing refrigerant discharged from the electric compressor (11), and an electric motor (11a) Motor temperature detection means for detecting the motor temperature, protection determination means for determining whether or not the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value, and detected by the motor temperature detection means by the protection determination means And a motor protection control unit that controls at least the opening degree of the variable throttle mechanism (12, 16) when the motor temperature is determined to be equal to or higher than the reference value . It is characterized by.

  As described above, when the motor temperature of the electric motor (11a) is equal to or higher than a predetermined value, the discharge of the electric compressor (11) is controlled by controlling so that at least the opening of the variable throttle mechanism (16) does not decrease. An increase in the refrigerant pressure can be avoided. Accordingly, at least an increase in the load of the electric compressor (11) can be avoided and an increase in the motor current output to the electric motor (11a) can be avoided, so that the electric compressor (11) can be operated without stopping. The temperature protection control for avoiding the temperature rise of the motor (11a) can be performed.

  Here, the motor temperature detection means is not limited to the detection means that directly detects the motor temperature, but also includes a detection means that indirectly detects the motor temperature based on a parameter related to the motor temperature or the like.

Further, in the invention according to claim 1, for driving the moving motor (11a) collector comprising a drive circuit (19), drive circuit (19), the motor current value output to the electric motor (11a) The motor temperature detecting means detects the motor rotational speed of the electric motor (11a), and the motor temperature detecting means detects the motor rotational speed, the motor current value, and the motor detected by the drive circuit based on the control characteristics in which the motor temperature is associated in advance. The second feature is that the motor temperature is calculated and detected from the rotation speed and the motor current value.

  As described above, the motor temperature of the electric motor (11a) can be calculated and detected based on the control characteristics in which the motor rotation speed and the motor current value are associated with the motor temperature. Thereby, since it is not necessary to provide a dedicated temperature detection means for the motor temperature of the electric motor (11a), the configuration of the electric compressor (11) can be simplified.

Further, in the invention according to claims 1 to 3, are control characteristic, the reference value corresponding to the motor speed and the motor current value is defined in advance, the protection determining means detected by calculating the motor temperature detection means It is a third feature that it is determined whether or not the measured motor temperature is equal to or higher than a reference value defined in the control characteristics.

  In this way, by defining the reference value according to the motor speed and the motor current value in the control characteristics, the motor temperature of the electric motor (11a) is calculated and detected based on the control characteristics, and the electric motor (11a) is detected. ) Whether the motor temperature is equal to or higher than a reference value.

In addition to the first to third features described above, in the invention according to claim 1, the control characteristics, as a reference value, at least a first reference value and second reference motor temperature is higher than the first reference value A value is defined, and the protection determination means determines whether the motor temperature calculated and detected by the motor temperature detection means is equal to or higher than a first reference value specified in the control characteristics, and the motor protection control means The opening of the variable throttle mechanism (12, 16) is controlled not to decrease when the motor temperature calculated and detected by the motor temperature detecting means is equal to or higher than the first reference value and lower than the second reference value; When it becomes more than a 2nd reference value, it controls so that the opening degree of a variable aperture mechanism (12, 16) may increase.

  Thus, by dividing the reference value of the motor current set according to the motor rotation speed of the electric motor (11a) into at least the first and second reference values, the variable aperture mechanism (16) is opened step by step. The degree can be adjusted. Thereby, for example, in an air conditioner, since the cooling / heating capacity can be adjusted in stages, it is possible to suppress deterioration of the indoor air conditioning feeling and the like.

  By the way, if the superheat degree of the refrigerant | coolant of the suction side of an electric compressor (11) becomes large, the cooling effect of the electric motor (11a) by the refrigerant | coolant of a suction side will fall. Further, when the superheat degree of the refrigerant on the suction side of the electric compressor (11) increases, the refrigerant temperature on the discharge side of the electric compressor (11) rises excessively, so that the motor temperature of the electric motor (11a) rises. .

Therefore, in the invention described in claim 2 , in addition to the first to third features described above, suction refrigerant superheat detection means for detecting the refrigerant superheat degree on the suction side of the electric compressor (11), and suction refrigerant superheat Control characteristic selection means for selecting a specific control characteristic from among a plurality of control characteristics for which different reference values are defined in advance based on the refrigerant superheat degree detected by the degree detection means, and the protection determination means includes a motor It is characterized in that it is determined whether or not the motor temperature calculated and detected by the temperature detecting means is equal to or higher than a reference value defined in a specific control characteristic.

  As described above, based on the refrigerant superheat degree on the suction side of the electric compressor (11), a specific control characteristic is selected from among a plurality of control characteristics having different reference values set in advance, and based on the specific control characteristic. Thus, it is possible to appropriately determine the temperature protection control of the electric motor (11a) by calculating and detecting the motor temperature of the electric motor (11a). Thereby, the reliability of the temperature protection control of the electric motor (11a) can be improved.

  Here, when the refrigeration cycle apparatus (10) is configured as a heat pump capable of switching between the cooling operation mode and the heating operation mode, the refrigerant overheating on the suction side of the electric compressor (11) is performed in the cooling operation mode and the heating operation mode. The degree is higher in the cooling operation mode. That is, the motor temperature of the electric motor (11a) is more likely to rise in the cooling operation mode than in the heating operation mode.

Therefore, in the invention described in claim 3 , in addition to the first to third features described above, at least a cooling operation mode in which indoor air is cooled with a refrigerant and a heating operation mode in which indoor air is heated with a refrigerant can be switched. It is configured as a heat pump, and comprises a control characteristic selection means for selecting a specific control characteristic from a plurality of control characteristics for which different reference values are defined in advance based on the operation mode. In the operation mode, a specific control characteristic having a reference value lower than the reference value specified in the control characteristic in the heating operation mode is selected, and the protection determination means is calculated by the motor temperature detection means. In this case, it is determined whether or not the detected motor temperature is equal to or higher than a reference value defined in a specific control characteristic.

  Thereby, determination of temperature protection control of an electric motor (11a) can be performed appropriately, and the reliability of temperature protection control of an electric motor (11a) can be improved.

Further, the invention described in claim 4, in addition to the first feature described above, the electric compressor (11) radiating heat exchanger for cooling the refrigerant in the discharge side of the (6, 13), the heat exchanger for heat radiation A first electric blower (13a) for blowing outdoor air to the fan (13), and first electric blower control means for controlling the rotational speed of the first electric blower (13a), and a variable throttle mechanism (12, 16) decompresses the refrigerant on the outlet side of the heat-dissipating heat exchanger (6, 13), and the refrigerant pressure on the discharge side of the electric compressor (11) becomes the outlet side of the heat-dissipating heat exchanger (6, 13). is controlled so as to approach the target high pressure is determined based on the coolant temperature, the motor protection control unit, when the motor temperature detected by the motor temperature detection means is equal to or greater than the reference value, lowering the target high pressure motor detected by the allowed, the motor temperature detection means by the protection determination means If the degree is determined to be equal to or greater than the reference value, the first electric blower control unit may increase the rotational speed of the first electric blower (13a).

  Thus, the target high pressure can be reduced by increasing the number of revolutions of the first electric blower (13a) and lowering the refrigerant temperature on the outlet side of the heat dissipation heat exchanger (13). Thereby, the refrigerant | coolant pressure (discharge refrigerant | coolant pressure Pd) of the discharge side of an electric compressor (11) can be reduced, and the temperature rise of an electric motor (11a) can be avoided.

Further, in the invention according to claim 5 , in the invention according to claim 4 , the evaporator (5) for evaporating the refrigerant depressurized by the variable throttle mechanism (12, 16), and the evaporator (5) A second electric blower (4) for blowing the fluid to be heat exchanged and a second electric blower control means for controlling the rotation speed of the second electric blower (4) are detected by the motor temperature detection means by the protection judgment means. When it is determined that the motor temperature is equal to or higher than the reference value, the second electric blower control means reduces the rotational speed of the second electric blower (4).

  Thus, the degree of superheat of the refrigerant on the suction side of the electric compressor (11) can be reduced by lowering the rotation speed of the second electric blower (4) and lowering the cooling performance of the evaporator (5). it can. Thereby, the refrigerant | coolant pressure (suction | inhalation refrigerant | coolant pressure Ps) of the suction | inhalation side of an electric compressor (11) can be reduced, and the temperature rise of an electric motor (11a) can be avoided.

According to a sixth aspect of the present invention, in the fourth aspect of the present invention, the evaporator (5) for evaporating the refrigerant decompressed by the variable throttle mechanism (12, 16) and the evaporator (5) It is provided with inside / outside air switching control means capable of switching the air exchange target fluid to be blown from the inside air mode introduced from the room to the outside air mode introduced from the outside, and the motor temperature detected by the motor temperature detecting means by the protection judging means is a reference. When it is determined that the value is equal to or greater than the value, the inside / outside air switching control means switches to the inside air mode.

  In this way, the degree of superheat of the refrigerant on the suction side of the electric compressor (11) can be reduced by switching to the inside air mode by the inside / outside air switching control means and reducing the cooling performance of the evaporator (5). Thereby, the refrigerant | coolant pressure (suction | inhalation refrigerant | coolant pressure Ps) of the suction | inhalation side of an electric compressor (11) can be reduced, and the temperature rise of an electric motor (11a) can be avoided.

Further, in the invention described in claim 7 , in addition to the first feature described above, the motor temperature detection means is a motor temperature detection sensor for detecting the motor temperature of the electric motor (11a).

  Thereby, since the motor temperature of the electric motor (11a) can be detected with high accuracy, temperature protection control for avoiding the temperature rise of the electric motor (11a) can be performed with high accuracy. Here, the motor temperature includes not only the internal temperature of the electric motor (11a) but also an indirect temperature such as the surface temperature of the housing of the electric compressor (11).

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

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram of the overall configuration when the refrigeration cycle apparatus of the present embodiment is applied to a vehicle air conditioner. As shown in FIG. 1, the vehicle air conditioner of the present embodiment includes an indoor air conditioning unit 1 disposed inside an instrument panel that forms an instrument panel or the like at the foremost part of the vehicle interior.

  The indoor air-conditioning unit 1 forms a shell of the indoor air-conditioning unit 1 and has a resin case 2 that houses each component device of the indoor air-conditioning unit 1. In this case 2, an air passage for indoor blown air that is blown toward the vehicle interior is formed.

  An inside / outside air switching box 3 having an inside air introduction port 3a and an outside air introduction port 3b is disposed at the most upstream portion of the air passage of the case 2, and an inside / outside air switching door 3c is rotatably disposed therein. .

  The inside / outside air switching door 3c is driven by a servo motor (not shown), and an inside air mode for introducing inside air (indoor air) from the inside air introduction port 3a, an outside air mode for introducing outside air (outdoor air) from the outside air introduction port 3b, and Switch between the inside and outside air mode that introduces inside air and outside air at the same time.

  On the downstream side of the inside / outside air switching box 3, an electric type electric blower 4 that blows indoor blown air toward the vehicle interior is disposed. The electric blower (first electric blower) 4 is an electric blower that drives a well-known centrifugal multiblade fan (sirocco fan) with an electric motor 4a. The number of revolutions of the electric motor 4a is controlled by a control voltage output from an air-conditioning control device 20 described later.

  An evaporator 5 is disposed on the downstream side of the electric blower 4. This evaporator 5 is one of the components constituting the refrigeration cycle apparatus 10 described later. The evaporator 5 functions as a cooling heat exchanger that cools the blown air blown from the electric blower 4 by evaporating the low-pressure side refrigerant that has flowed into the inside and exhibiting an endothermic action.

  On the downstream side of the evaporator 5, a heater core 6 is disposed as a heating heat exchanger that heats the air that has passed through the evaporator 5 using hot water heated by an electric heater or the like as a heat source. The hot water heated by an electric heater or the like is supplied into the heater core 6 by an electric pump (not shown).

  On the side of the heater core 6, a bypass ventilation path 7 that bypasses the heater core 6 and through which the blown air flows is formed, and an air mix door 8 that constitutes a temperature adjusting means for the blown air is rotatably disposed. The air mix door 8 is driven by a servo motor (not shown) so that its rotational position (opening) can be continuously adjusted.

  By adjusting the opening degree of the air mix door 8, the ratio of the amount of air passing through the heater core 6 and the amount of air passing through the bypass ventilation path 7 is adjusted, and the temperature of the blown air downstream of the heater core 6 is adjusted. The In this embodiment, since the bypass ventilation path 7 is formed on both sides of the heater core 6, the air mix door 8 is also arranged on both sides of the heater core 6, and the two air mix doors 8 are operated in conjunction with each other. It is like that.

  A defroster outlet (not shown) for blowing conditioned air toward the front window glass of the vehicle and a face outlet for blowing conditioned air toward the upper body of the occupant are provided at the most downstream portion of the air passage of the case 2. (Not shown) and a foot outlet (not shown) for blowing out the conditioned air toward the feet of the occupant are provided. Opening / closing doors (not shown) are rotatably arranged in the upstream portions of these air outlets, and the opening / closing doors are opened / closed by a common servo motor via a link mechanism (not shown).

  Next, the refrigeration cycle apparatus 10 will be described. The refrigeration cycle apparatus 10 includes an electric compressor 11, an outdoor heat exchanger 13, an electric expansion valve 16, an accumulator 18 and the like in addition to the evaporator 5 described above.

  First, the electric compressor 11 is configured by integrating an electric motor 11a and a compression mechanism 11b driven by the electric motor. The electric motor 11 a is disposed on the suction side of the electric compressor 11 and is cooled by the low-temperature suction refrigerant of the electric compressor 11.

  Here, the electric motor 11a is a three-phase AC motor, and the compression mechanism 11b is a known scroll-type compression mechanism, for example. The electric motor 11a is controlled at a variable speed by an inverter device 19 described later.

  An outdoor heat exchanger 13 is provided on the discharge side of the electric compressor 11. The outdoor heat exchanger 13 of the present embodiment acts as a heat dissipation heat exchanger that cools the refrigerant by exchanging heat between the high-temperature and high-pressure discharged refrigerant discharged from the electric compressor 11 and the outside air (outdoor air). . Outside air is blown to the outdoor heat exchanger 13 by an electric cooling fan (second electric blower) 13a. Here, the cooling fan 13a is driven by the electric motor 13b, and the rotation speed of the electric motor 13b is controlled by a control voltage output from the air conditioning controller 20 described later.

  On the outlet side of the outdoor heat exchanger 13, an electric expansion valve 16 is provided as a variable throttle mechanism. The electric expansion valve 16 serves as a pressure control valve whose opening degree is electrically controlled so that the discharged refrigerant pressure Pd becomes the target high pressure during normal cycle operation. Further, the electric expansion valve 16 functions as a control valve for suppressing an increase in motor temperature when the motor temperature of the electric motor 11a of the electric compressor 11 is in a high temperature state.

  Specifically, the electric expansion valve 16 includes, for example, an electric actuator mechanism 16a formed of a stepping motor and a valve mechanism driven by the electric actuator mechanism 16a. The opening degree of the valve mechanism is the same as that of the electric actuator mechanism 16a. It can be finely adjusted by minute amounts depending on the operating angle. The opening degree of the electric expansion valve 16 is controlled by the air conditioning controller 20 described later.

  The above-described evaporator 5 is provided on the outlet side of the electric expansion valve 16. An accumulator 18 is provided on the outlet side of the evaporator 5. This accumulator 18 is gas-liquid separation means for separating the liquid refrigerant (saturated liquid phase refrigerant) and the gas refrigerant (saturated gas phase refrigerant) as the outlet refrigerant of the evaporator 5 and storing surplus refrigerant in the cycle. The gas refrigerant separated in step S is led out toward the suction side of the electric compressor 11.

  Next, an outline of the electric control unit in the first embodiment will be described with reference to FIG. Here, FIG. 2 is a block diagram of the electric control unit. The air conditioning control device 20 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. The air-conditioning control device 20 performs various calculations and processes based on the control program stored in the ROM, and controls the inverter device 19 of the electric compressor 11, the electric motor 13 b of the cooling fan 13 a, and the electric expansion valve 16. The operation of electric devices such as the electric actuator mechanism 16a and the electric motor 4a of the electric blower 4 is controlled.

  Here, the inverter device 19 of the electric compressor 11 will be briefly described. The electric motor 11a of the electric compressor 11 that is a three-phase AC motor is rotationally driven by the three-phase AC power that is converted and output by the power device 190 of the inverter device 19. Here, the motor rotation speed of the electric motor 11a is finely controlled (variable speed drive control) by the inverter control unit 191.

  The inverter control unit 191 includes a CPU 192, a communication circuit 193, and the like, and controls the motor rotation speed of the electric motor 11a of the electric compressor 11 to be an optimum value while communicating with the air conditioning control device 20.

  Here, the inverter control unit 191 detects the motor current output to the electric motor 11a and the motor rotation speed of the electric motor 11a, and outputs the detected value to the air conditioning controller 20. In addition, the power supply of the inverter apparatus 19 is the battery 21 mounted in the vehicle.

  On the input side of the control device 20 for air conditioning, a discharge pressure sensor 31 that detects a discharge refrigerant pressure Pd on the discharge side of the electric compressor 11 and an outdoor refrigerant temperature Tho that is an outlet side refrigerant temperature of the outdoor heat exchanger 13 are detected. The outdoor refrigerant temperature sensor 32 that performs the operation, the blown air temperature sensor 33 that detects the blown air temperature Te of the evaporator 5, and the like are connected.

  The air conditioning control device 20 also receives detection signals from a sensor group 34 including a known outside air temperature sensor, inside air temperature sensor, solar radiation sensor, and the like. These various sensors 31 to 34 constitute various detection means of the present embodiment. In addition, various air conditioning operation signals are input to the air conditioning control device 20 from the operation members of the air conditioning operation panel 40 disposed near the instrument panel (instrument panel) in the passenger compartment.

  Specifically, the set temperature signal in the vehicle interior by the temperature setting switch, the electric compressor operation command signal by the air conditioner switch, the air volume switching signal of the electric blower 4 by the air volume switching switch, and the blowing mode of the indoor air conditioning unit section by the blowing mode switching switch An air conditioning operation signal such as a switching signal and an inside / outside air introduction mode switching signal of the inside / outside air switching box by the inside / outside air switching switch is input from the air conditioning operation panel 40.

  Next, the operation of this embodiment in the above configuration will be described. First, the basic operation of the refrigeration cycle apparatus 10 will be described. When an operation command signal for the electric compressor 11 is generated by the operation member (air conditioner switch) of the air conditioning operation panel 40, the electric motor 11a is energized through the inverter device 19, and the electric motor 11a rotates. The driving force of the electric motor 11a is transmitted to the compression mechanism 11b, and the electric compressor 11 is driven.

  The refrigerant is compressed by the electric compressor 11 to be in a high temperature and high pressure state. This high-temperature and high-pressure refrigerant then flows into the outdoor heat exchanger 13, where it exchanges heat with the outside air (outdoor air) blown by the cooling fan 13a and dissipates heat into the outside air.

  And the exit refrigerant | coolant of the outdoor heat exchanger 13 is pressure-reduced by the electric expansion valve 16, and becomes a low-temperature low-pressure gas-liquid two-phase state. This low-temperature and low-pressure gas-liquid two-phase refrigerant then flows into the evaporator 5 where it absorbs heat from the blown air of the electric blower 4 and evaporates. Thereby, the air blown from the electric blower 4 can be cooled by the evaporator 5, and the cool air can be blown into the passenger compartment.

  The low-pressure refrigerant that has passed through the evaporator 5 then flows into the accumulator 18, and the low-pressure refrigerant is separated into a saturated liquid-phase refrigerant and a saturated gas-phase refrigerant in the accumulator 18. Saturated gas-phase refrigerant is led out from the outlet of the accumulator 18 toward the suction side of the electric compressor 11, sucked into the electric compressor 11, and compressed again.

  Next, a basic control process executed by the air conditioning control device 20 of the present embodiment will be described. This control process starts when the air conditioner switch is turned on while the start switch (not shown) of the vehicle is turned on.

  First, flags, timers, etc. are initialized, and detection signals from various sensors 31 to 34 and operation signals from the air conditioning operation panel 40 are read. Then, control states of the various actuators 4a, 13b, 16a, 19 and the like are determined.

  Specifically, a target blowing temperature TAO to be blown into the vehicle interior is calculated based on the target temperature Tset of the blown air into the vehicle interior, the internal air temperature Tr, and the external air temperature Tam. Based on the target blowing temperature TAO and the like, the target rotational speed of the electric blower 4 (applied voltage to the electric motor 4a), the target rotational speed of the outdoor blower fan 13a (applied voltage to the outdoor blower fan 13a), the air mix door 8 The target opening (control signal output to the servo motor for the air mix door 8) is calculated.

  Further, based on the target blowing temperature TAO, a target evaporator blowing temperature TEO that is a target value of the degree of cooling of the evaporator 5 is determined, and the evaporator 5 blowing air temperature Te approaches the target evaporator blowing temperature TEO. The refrigerant discharge capacity of the electric compressor 11 (control signal output to the inverter device 19) is calculated.

  Further, based on the outlet side refrigerant temperature (outdoor refrigerant temperature) Tho of the outdoor heat exchanger 13, a target high pressure Po that maximizes the cycle efficiency (COP) is determined, and the discharge refrigerant pressure Pd of the electric compressor 11 is The valve opening degree of the electric expansion valve 16 (control signal output to the electric actuator mechanism 16a) is determined so that the target high pressure Po is reached.

  Then, an output signal is output from the air conditioning control device 20 to the various actuators 4a, 11b, 13a, 16a, etc. so that the determined control state is obtained.

  Here, the electric compressor 11 of the present embodiment is configured to cool the electric motor 11a with the refrigerant sucked by the electric compressor 11, but the motor current from the inverter device 19 is large and the rotational speed of the electric motor 11a is low. In some cases, the electric motor 11a cannot be sufficiently cooled by the refrigerant sucked by the electric compressor 11 and becomes in a high temperature state.

  In such a case, the electric compressor 11 has been stopped until now. However, in this embodiment, the temperature of the electric motor 11a of the electric compressor 11 is increased by controlling the opening of the electric expansion valve 16. Temperature protection control to avoid is performed.

  The temperature protection control of the electric motor 11a according to the present embodiment will be described with reference to FIGS. Here, FIG. 3 is a flowchart of the opening setting process of the electric expansion valve 16 executed by the air conditioning controller 20, and FIG. 4 is the motor rotation speed of the electric motor 11a of the electric compressor 11 in the present embodiment. FIG. 5 is a control characteristic diagram in which motor current values and motor temperatures are associated with each other.

  The opening setting process of the electric expansion valve 16 shown in FIG. 3 is started by starting the refrigeration cycle (starting the electric compressor 11). First, in step S100, detection signals from various sensors, various air conditioning operation signals from the air conditioning operation panel 40, and the like are read.

  Specifically, the discharge refrigerant pressure Pd detected by the discharge pressure sensor 31, the outlet side refrigerant temperature (outdoor refrigerant temperature) Tho of the outdoor heat exchanger 13 detected by the outdoor refrigerant temperature sensor 32, and the inverter device 19 The motor current value output to the electric motor 11a of the electric compressor 11 and the motor rotation number are read.

  Next, in step S200, the discharge refrigerant pressure Pd detected by the discharge pressure sensor 31 is based on the outlet side refrigerant temperature (outdoor refrigerant temperature) Tho of the outdoor heat exchanger 13 detected by the outdoor refrigerant temperature sensor 32. The control amount of the opening degree of the electric expansion valve 16 is calculated so that the target high-pressure pressure Po determined in this way is obtained. Here, the electric expansion valve 16 of this embodiment is controlled to the opening increase side when the control amount of the opening is larger than zero, and is controlled to the opening decreasing side when it is smaller than zero.

  In the present embodiment, the control characteristics shown in FIG. 4 are stored in advance in the ROM or the like of the air conditioning control device 20. This control characteristic is obtained by associating the motor rotation speed and motor current detected by the inverter device 19 with the motor temperature. The motor temperature is inversely proportional to the refrigerant flow rate, that is, the motor rotation speed, and the heat generation amount, that is, the motor current value. The relationship is proportional to the square of. For example, the motor temperature is low when the motor rotation number is high and the motor current value is small, and the motor temperature is high when the motor rotation number is low and the motor current value is large.

  In the present embodiment, the motor temperature of the electric motor 11a is calculated and detected based on the control characteristics. The motor temperature of the electric motor 11a may be calculated by an arithmetic expression or the like based on the motor speed and the motor current value.

  Further, the control characteristic defines a reference value for the motor temperature used for determining whether or not to avoid a temperature increase of the electric motor 11a. Here, in the control characteristics of the present embodiment, first to third reference values are defined as reference values, and limit values are defined.

  The relationship between each reference value and limit value is as follows: first reference value <second reference value <third reference value <limit value. The first to third reference values and the limit value are defined so as to increase in proportion to the increase in the motor current value when the motor rotation number is constant, depending on the motor rotation number and the motor current value. The first reference line indicating the first reference value to be set, the second reference line indicating the second reference value, the third reference line indicating the third reference value, and the limit line indicating the limit value are parallel lines. ing.

  The temperature of the electric motor 11a of the electric compressor 11 is divided into a plurality of regions by the first to third reference lines and the limit line. Specifically, the region where the motor temperature is lower than the first reference value is a region A based on the control characteristics in which the motor speed and the motor current and the motor temperature are associated with each other, and the region where the motor temperature is lower than the second reference value. Area B, the area above the second reference value and below the third reference value is area C, the area above the third reference value and below the limit value is area D, and the area above the limit value (shaded area) is the limit area It is said.

  The areas A to D and the restriction area are indexes indicating the motor temperature state of the electric motor 11a of the electric compressor 11, the area A indicates a normal state, and the restriction area is abnormal in the electric motor 11a. This indicates an abnormal state in which there is a possibility that a high insulation temperature (for example, 120 ° C.) may occur and insulation defects of the internal windings may occur. Regions B to D are set between the region A and the restricted region, and indicate a state where temperature protection control of the electric motor 11a is required.

  Returning to FIG. 3, in step S300, based on the control characteristics, the current motor temperature of the electric motor 11a is calculated and detected from the motor rotational speed and motor current value detected in step S100, and any region in the control characteristics described above is detected. To belong to. In step S400, it is determined whether or not the region of the motor temperature calculated in step S300 is region A.

  If it is determined in step S400 that the motor temperature region is region A, the control amount calculated in step S200 is set as the control amount of the opening degree of the electric expansion valve 16 (step S500). That is, the discharge refrigerant pressure Pd of the electric compressor 11 can be maintained at the target high pressure Po for optimal control.

  If the region A is not determined in step S400, it is determined in step S410 whether the control amount of the opening degree of the electric expansion valve 16 calculated in step S200 is greater than zero. If the control amount is smaller than zero, the opening degree of the electric expansion valve 16 is controlled to the decreasing side. Therefore, the control amount is set to zero in step S420 and the opening degree of the electric expansion valve 16 does not change. Change to control amount. If the control amount is greater than or equal to zero, the process proceeds to step S430 without changing the control amount.

  Next, in step S430, it is determined whether the motor temperature region is region B or not. If it is determined in step S430 that the region is B, the process proceeds to step S500, and a control amount of zero or more is set as a control amount of the opening degree of the electric expansion valve 16.

  Thus, in the region B, at least the opening degree of the electromagnetic expansion valve 16 is controlled so as not to decrease. That is, by suppressing at least the increase in the discharge refrigerant pressure Pd of the electric compressor 11, an increase in the load of the electric compressor 11 can be avoided and an increase in the motor temperature of the electric motor 11a can be avoided.

  If it is not determined in step S430 that the region is B, it is determined in step S440 whether the motor temperature region is region C or not. If the region C is determined in step S440, the first predetermined value α is set to the control amount of the opening degree of the electric expansion valve 16 calculated in step S200 or the control amount set to zero in step 420 in step S450. to add.

  And it progresses to step S500 and sets the control amount added by 1st predetermined value (alpha) by step S450 as a control amount of the opening degree of the electric expansion valve 16. FIG. Thus, in the region C, the opening degree of the electromagnetic expansion valve 16 is controlled to increase. That is, by reducing the discharge refrigerant pressure Pd of the electric compressor 11, it is possible to reduce the load on the electric compressor 11 and avoid an increase in the motor temperature of the electric motor 11a.

  Furthermore, when it is not determined as the region C in step S440, it is determined whether or not the motor temperature region is the region D in step S460. If the region D is determined in step S460, the second predetermined value β is set to the control amount of the opening degree of the electric expansion valve 16 calculated in step S200 or the control amount set to zero in step 420 in step S470. to add.

  Then, the process proceeds to step S500, and the control amount added by the second predetermined value β in step S450 is set as the control amount of the opening degree of the electric expansion valve 16. Here, the second predetermined value β added in step S460 is set to a value larger than the first predetermined value α added in step S450 (first predetermined value α <second predetermined value β), and the region D In the control, the opening degree of the electromagnetic expansion valve 16 is controlled to be larger than that in the region C.

  In this way, by reducing the discharge refrigerant pressure Pd of the electric compressor 11 in a stepwise manner, the load on the electric compressor 11 can be reduced, and an increase in the motor temperature of the electric motor 11a can be avoided. The deterioration of the air conditioning feeling in the passenger compartment due to the sudden change in the discharged refrigerant pressure Pd of 11 can be suppressed.

  If the region D is not determined in step S460, it is determined in step S480 that the motor temperature of the electric motor 11a is abnormal, and that fact is stored in the ROM or the like of the air conditioning control device 20.

  Incidentally, in this restricted area, the malfunction of the refrigeration cycle apparatus 10 and the like are expected, so that the operation of the electric compressor 11 is stopped. Here, the determination processing in steps S400, S430, S440, and S460 corresponds to protection determination means, and steps S420, S450, and S470 correspond to motor protection control means.

  As explained above, when the electric motor 11a of the electric compressor 11 is equal to or higher than the first reference value, at least the opening degree of the electromagnetic expansion valve 16 is controlled so as not to decrease. An increase in the discharge refrigerant pressure can be avoided. As a result, at least an increase in the load of the electric compressor 11 can be avoided and an increase in the motor current output to the electric motor 11a can be avoided, so that the temperature of the electric motor 11a can be increased without stopping the electric compressor 11. Temperature protection control to avoid can be performed.

  In addition, when the motor temperature of the electric motor 11a is calculated and detected based on the control characteristic that associates the motor temperature according to the motor rotation speed and the motor current value, and the detected motor temperature is equal to or higher than the reference value, The temperature protection control for avoiding the temperature rise of the electric motor 11a can be performed.

  Further, when detecting the motor temperature of the electric motor 11a based on the control characteristics, the temperature protection control for avoiding the temperature rise of the electric motor 11a can be performed without providing a dedicated detection device. The configuration of the compressor 11 can be simplified.

  Moreover, since the opening degree of the electric expansion valve 16 can be adjusted in stages by defining a plurality of reference values defined in the control characteristics as the first to third reference values, the discharge of the electric compressor 11 It is possible to suppress deterioration of the air conditioning feeling in the passenger compartment due to the sudden change in the refrigerant pressure Pd. In the present embodiment, the first to third reference values are set as reference values. However, the present invention is not limited to this, and the number of reference values may be increased or decreased.

(Second Embodiment)
Next, a third embodiment of the present invention will be described with reference to FIGS. Parts that are the same as or equivalent to those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted. Here, FIG. 5 is a conceptual diagram of the overall configuration when the refrigeration cycle apparatus of the present embodiment is applied to a vehicle air conditioner. The refrigeration cycle apparatus 10 of the present embodiment is configured as a heat pump refrigeration cycle that can be switched between a cooling operation (cooling operation) mode and a heating operation (heating operation) mode.

  As shown in FIG. 5, in the present embodiment, the heater core 6 arranged in the case 2 of the indoor air conditioning unit 1 is a high-temperature and high-pressure discharged from the electric compressor 11 as one of the components of the refrigeration cycle apparatus 10. It functions as a use side heat exchanger that heats the air that has passed through the evaporator 5 using the refrigerant as a heat source. The heater core 6 also acts as a heat dissipation heat exchanger that radiates the heat of the refrigerant to the air that has passed through the evaporator 5 to cool the refrigerant.

  The configuration of the refrigeration cycle apparatus 10 of the present embodiment includes an evaporator 5, a heater core 6, an electric compressor 11, a first electric expansion valve 12, an outdoor heat exchanger 13, an internal heat exchanger 15, and a second electric type. An expansion valve (corresponding to the electric expansion valve in the first embodiment) 16, an accumulator 18, and the like are configured. For convenience of explanation, the heater core 6 will be described below by replacing it with a use side heat exchanger.

  The discharge side of the electric compressor 11 is connected to the inlet side of the use side heat exchanger 6 described above. A first electric expansion valve 12 constituting a variable throttle mechanism is connected to the outlet side of the use side heat exchanger 6.

  The opening degree of the first electric expansion valve 12 is electrically controlled by a control signal output from the air-conditioning control device 20 so that the discharge refrigerant pressure Pd of the cycle becomes the target high pressure Po in the heating operation mode described later. It also functions as a high-pressure control valve. The first electric expansion valve 12 includes an electric actuator mechanism 12a and a valve mechanism.

  An outdoor heat exchanger 13 is connected to the outlet side of the first electric expansion valve 12. In the present embodiment, a first bypass passage 14 a that directly connects the outlet side of the use side heat exchanger 6 and the inlet side of the outdoor heat exchanger 13 to bypass the first electric expansion valve 12 is provided. ing. Further, a first on-off valve 14 for opening and closing the first bypass passage 14a is disposed in the first bypass passage 14a. The first on-off valve 14 is an electromagnetic valve that is controlled to open and close by a control voltage output from the air conditioning control device 20.

  In the cooling operation mode described later, the outdoor heat exchanger 13 acts as a heat dissipation heat exchanger that radiates the heat of the refrigerant to the outside air and cools the refrigerant, as in the first embodiment, and in the heating operation mode, It acts as an endothermic heat exchanger that absorbs heat from outside air and evaporates the refrigerant.

  A first refrigerant passage 15 a of the internal heat exchanger 15 is connected to the outlet side of the outdoor heat exchanger 13. The internal heat exchanger 15 is connected to the refrigerant on the outlet side of the outdoor heat exchanger 13 that passes through the first refrigerant passage 15a and the suction side of the electric compressor 11 that passes through the second refrigerant passage 15b in the cooling operation mode described later. A function of cooling the refrigerant on the outlet side of the outdoor heat exchanger 13 is exhibited by exchanging heat with the refrigerant.

  A second electric expansion valve 16 constituting a variable throttle mechanism is disposed on the outlet side of the first refrigerant passage 15a of the internal heat exchanger 15. The second electric expansion valve 16 has basically the same configuration as the first electric expansion valve 12, and includes an electric actuator mechanism 16a and a valve mechanism.

  The opening degree of the second electric expansion valve 16 is electrically controlled by a control signal output from the air conditioning controller 20 so that the discharged refrigerant pressure Pd becomes the target high pressure Po in the cooling operation mode described later. It also functions as a high-pressure control valve. The evaporator 5 is connected to the outlet side of the second electric expansion valve 16.

  Further, in the present embodiment, the internal heat exchanger 15, the evaporator 5 and the second electric type are directly connected between the inlet side of the first refrigerant passage 15a of the internal heat exchanger 15 and the outlet side of the evaporator 5. A second bypass passage 17 a that bypasses the expansion valve 16 is provided. The second bypass passage 17a is provided with a second on-off valve 17 that opens and closes the second bypass passage 17a.

  The second on-off valve 17 is an electromagnetic valve that has basically the same configuration as the first on-off valve 14 and is controlled to open and close by a control voltage output from the air-conditioning control device 20. An accumulator 18 is disposed on the downstream side of the evaporator 5 and the second bypass passage 17a. Further, the gas-phase refrigerant outlet of the accumulator 18 is connected to the inlet side of the second refrigerant passage 15b of the internal heat exchanger 15, and the inlet side of the electric compressor 11 is connected to the outlet side of the second refrigerant passage 15b. ing.

  Further, the air conditioning control device 20 of the present embodiment performs various calculations and processes based on the control program stored in the ROM, and various actuators 4a, 12a, 13a, 14, 16a, 17, 19 described above. Control the operation of etc.

  In addition to the configuration of the first embodiment, an intake pressure sensor 35 for detecting the intake refrigerant pressure Ps of the electric compressor 11 and an intake refrigerant temperature Ts of the electric compressor 11 are provided on the input side of the air conditioning control device 20. A suction refrigerant temperature sensor 36 for detecting, a discharge refrigerant temperature sensor 37 for detecting the discharge refrigerant temperature Td of the electric compressor 11, a use side refrigerant temperature sensor 38 for detecting the use side refrigerant temperature Tco of the use side heat exchanger 6, etc. are connected. Then, detection signals from these sensors 35 to 38 are input.

  Furthermore, the air conditioning operation panel 40 is provided with a cooling / heating switching switch for selectively switching between one of a heating operation mode for heating indoor blown air and a cooling operation mode for cooling indoor blown air.

  Next, the operation of this embodiment in the above configuration will be described. First, the basic operation of the refrigeration cycle apparatus 10 will be described in the case where the cooling / heating switching switch of the air conditioning operation panel 40 is in the cooling operation mode side.

  In the cooling operation mode, the first on-off valve 14 is opened, the first electric expansion valve 12 is fully closed, and the second on-off valve 17 is closed. Therefore, in the cooling operation mode, the high-temperature and high-pressure refrigerant compressed by the electric compressor 11 radiates heat to the indoor blown air by the use side heat exchanger (heater core) 6. The refrigerant that has flowed out of the use side heat exchanger 6 flows into the outdoor heat exchanger 13 through the first bypass passage 14a, and further dissipates heat to the outdoor air and is cooled.

  The refrigerant that has flowed out of the outdoor heat exchanger 13 flows into the first refrigerant passage 15a of the internal heat exchanger 15, exchanges heat with the intake refrigerant of the electric compressor 11 that passes through the second refrigerant passage 15a, and is further cooled. Being reduced enthalpy. Thereby, the enthalpy difference (refrigeration capacity) of the refrigerant | coolant between the refrigerant | coolant inlet_port | entrance and outlet in the evaporator 5 can be increased.

  The refrigerant that has flowed out of the first refrigerant passage 15 a of the internal heat exchanger 15 is decompressed by the second electric expansion valve 16. The refrigerant decompressed by the second electric expansion valve 16 flows into the evaporator 5 and absorbs heat from the indoor air and evaporates. Thereby, indoor ventilation air is cooled. Then, the refrigerant that has flowed out of the evaporator 5 flows into the accumulator 18 and is gas-liquid separated. Further, the gas-phase refrigerant that has flowed out of the accumulator 18 is sucked into the electric compressor 11 through the second refrigerant passage 15 b of the internal heat exchanger 15.

  On the other hand, in the heating operation mode, the first on-off valve 14 is closed, the second on-off valve 17 is opened, and the first electric expansion valve 16 is fully closed. Therefore, in the heating operation mode, the high-temperature and high-pressure refrigerant compressed by the electric compressor 11 radiates heat to the indoor blown air by the use side heat exchanger 6.

  The refrigerant that has flowed out of the use-side heat exchanger 6 is decompressed by the first electric expansion valve 12. The refrigerant depressurized by the first electric expansion valve 12 evaporates as the outdoor heat exchanger 13 absorbs heat from the outdoor air. The refrigerant flowing out of the outdoor heat exchanger 13 flows in the order of the second bypass passage 17 a → accumulator 18 → second refrigerant passage 15 b of the internal heat exchanger 15 and is sucked into the electric compressor 11.

  Next, temperature protection control of the electric motor 11a by the first and second electric expansion valves 12 and 16 according to the present embodiment will be described with reference to FIGS. FIG. 6 is a flowchart of the opening setting process of the electric expansion valves 12 and 16 executed by the air conditioning control device 20 in the present embodiment, and FIG. 7 shows the electric motor 11a of the electric compressor 11 in the present embodiment. It is a control characteristic figure which prescribed | regulated the reference value of the motor electric current value set according to motor rotation speed. FIG. 7 (a) shows a control characteristic diagram in the cooling operation mode, and FIG. 7 (b) shows a control characteristic diagram in the heating operation mode.

  First, in step S100, in step S100, detection signals from various sensors, various air conditioning operation signals from the air conditioning operation panel 40, and the like are read.

  Specifically, the discharge refrigerant pressure Pd detected by the discharge pressure sensor 31, the outdoor refrigerant temperature Tho detected by the outdoor refrigerant temperature sensor 32, the use side refrigerant temperature Tco detected by the use side refrigerant temperature sensor 38, The inverter device 19 reads the motor current value output to the electric motor 11a of the electric compressor 11, the motor rotation number, and the like. In addition, it detects whether the cooling / heating switch of the air conditioning operation panel 40 is set to the cooling operation mode side or the heating operation mode side.

  Next, in step S110, it is determined whether or not the cooling / heating changeover switch of the air conditioning operation panel 40 is in the cooling operation mode side (second parameter detection means). When it is determined that the cooling operation mode is set, in step S210, the discharge refrigerant pressure Pd of the electric compressor 11 becomes the target high pressure Po determined based on the outdoor refrigerant temperature Tho of the outdoor heat exchanger 13. Then, the control amount of the opening degree of the second electric expansion valve 16 is calculated.

  Here, in the present embodiment, in the cooling operation mode, the refrigerant that has flowed out of the outdoor heat exchanger 13 and the refrigerant sucked by the electric compressor 11 are exchanged by the internal heat exchanger 15, so that the refrigerant sucked by the electric compressor 11 is exchanged. Is heated by the refrigerant flowing out of the outdoor heat exchanger 13 and has a degree of superheat compared to that in the heating operation mode. Therefore, in the cooling operation mode, compared to the heating operation mode, the discharge refrigerant temperature of the electric compressor 11 is increased, and the motor temperature of the electric motor 11a is increased. That is, in the cooling operation mode and the heating operation mode, the temperature of the refrigerant sucked in the electric compressor 11 is different, and the motor temperature of the electric motor 11a is different even at the same motor current and motor rotation speed.

  Therefore, in the present embodiment, the control characteristics for the cooling operation mode (see FIG. 7A) and the control characteristics for the heating operation mode (see FIG. 7B) are preliminarily stored in the ROM of the air conditioning control device 20. I remember it. As shown in FIG. 7, the control characteristic for the cooling operation mode has a lower reference temperature than the control characteristic for the heating operation mode. A plurality of control characteristics having different reference values are stored in the ROM or the like of the air conditioning control device 20 for each operation mode.

  Next, in step S310, the control characteristic for the cooling operation mode is selected, and based on the control characteristic, the motor temperature is calculated and detected from the detected motor rotation speed and motor current value, and the detected motor temperature is Which region in the control characteristics during the cooling operation mode belongs is calculated, and the process proceeds to step S400.

  On the other hand, when it is determined in step S110 that the heating operation mode is selected, the target high pressure in which the discharge refrigerant pressure Pd of the electric compressor 11 is determined based on the use side refrigerant temperature Tco of the use side heat exchanger 6 in step S220. The control amount of the opening degree of the first electric expansion valve 16 is calculated so as to be the pressure Po.

  In step S320, a control characteristic for the heating operation mode is selected, and based on the control characteristic, the motor temperature is calculated and detected from the detected motor rotation speed and motor current value. Which region in the control characteristics for the operation mode belongs is calculated, and the process proceeds to step S400. Here, step S310 and step S320 correspond to control characteristic selection means.

  As described above, for each operation mode, a control characteristic adapted to the operation mode is selected from among a plurality of control characteristics having different reference values, and the motor temperature of the electric motor 11a is detected based on the selected control characteristic. By determining whether or not the selected control characteristic exceeds the reference value, it is possible to appropriately determine the temperature protection control of the electric motor 11a. Thereby, the reliability of the temperature protection control of the electric motor 11a can be improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described. The same or equivalent parts as those in the first and second embodiments are denoted by the same reference numerals, and the description thereof is omitted.

  In the second embodiment, a specific control characteristic is selected according to the operation mode, and based on the selected control characteristic, the temperature of the electric motor 11a is calculated and detected from the detected value of the inverter device 19. In the present embodiment, a plurality of control characteristics having different reference values are stored in the air conditioning control device 20 in advance, and specific control characteristics are selected from the plurality of control characteristics in accordance with the degree of refrigerant superheat on the suction side of the electric compressor 11. The temperature of the electric motor 11a is calculated from the detection value of the inverter device 19 and detected.

  Specifically, the suction pressure sensor 35 detects the suction refrigerant pressure Ps of the electric compressor 11, the suction refrigerant temperature sensor 36 detects the suction refrigerant temperature Ts of the electric compressor 11, and then the detected suction refrigerant pressure Ps. Then, the saturated vapor temperature of the refrigerant is obtained, and the refrigerant superheat degree SH on the intake side of the electric compressor 11 is calculated from the intake refrigerant temperature Ts and the saturated vapor temperature. Note that the suction refrigerant pressure Ps may be estimated from the blown air temperature Te of the evaporator 5 detected by the blown air temperature sensor 33.

  If the refrigerant superheat degree SH on the suction side of the electric compressor 11 is large, the motor temperature of the electric motor 11a increases. Therefore, a control characteristic having a low reference value is selected from among a plurality of control characteristics. On the other hand, if the refrigerant superheat degree SH on the suction side of the electric compressor 11 is small, the motor temperature of the electric motor 11a is unlikely to rise, so a control characteristic with a high reference value is selected from among a plurality of control characteristics.

  As described above, based on the refrigerant superheat degree SH on the suction side of the electric compressor 11, a specific control characteristic is selected from a plurality of control characteristics having different preset reference values, and based on the specific control characteristic. By calculating and detecting the motor temperature of the electric motor 11a, it is possible to appropriately determine the temperature protection control of the electric motor 11a. Thereby, the reliability of the temperature protection control of the electric motor 11a can be improved.

  Here, the content of the control processing of the present embodiment is not limited to the heat pump type refrigeration cycle apparatus shown in the second embodiment, but can be applied to the refrigeration cycle apparatus shown in the first embodiment.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows.

  (1) In the above-described embodiment, the temperature of the electric motor 11a is calculated and detected using the control characteristics in which the motor speed of the electric motor 11a of the electric compressor 11 and the motor current are associated with the motor temperature. It is not limited to. For example, the motor temperature of the electric motor 11a may be detected by a temperature sensor that detects the internal temperature of the electric motor 11a, a temperature sensor that detects the temperature of the housing of the electric motor 11a, or the like.

  (2) In the above-described embodiment, in the temperature protection control of the electric motor 11 a of the electric compressor 11, the control amount of the opening degree of the electric expansion valves 12, 16 is directly changed. is not. For example, by reducing the target high pressure determined based on the outlet side refrigerant temperature (outdoor refrigerant temperature) Tho of the outdoor heat exchanger 13 and the use side heat exchanger 6 that acted as heat dissipation heat exchangers, The discharge refrigerant pressure Pd of the compressor 11 may be reduced.

  (3) In the above-described embodiment, when the temperature protection of the electric motor 11a of the electric compressor 11 is required, by preventing the opening of the electric expansion valve 16 from decreasing, Although the temperature protection control of the electric motor 11a is performed, in addition to the opening degree control of the electric expansion valve 16, the rotation speed of the electric motor 13b of the cooling fan (first electric blower) 13a may be increased.

  Thus, the target high pressure can be reduced by increasing the number of revolutions of the cooling fan 13a and lowering the refrigerant temperature on the outlet side of the heat-dissipating heat exchangers 6 and 13. Thereby, the refrigerant | coolant pressure (discharge refrigerant pressure Pd) by the side of discharge of the electric compressor 11 can be reduced, and the temperature rise of the electric motor 11a can be avoided.

  (4) When the temperature protection of the electric motor 11a of the electric compressor 11 is required, the rotation speed of the electric motor 4a of the electric blower (second electric blower) 4 may be decreased.

  Thus, the superheat degree of the refrigerant | coolant by the side of the suction | inhalation of the electric compressor 11 can be reduced by reducing the rotation speed of the electric blower 4 and reducing the cooling performance of the evaporator 5. Thereby, the refrigerant | coolant pressure (suction | inhalation refrigerant | coolant pressure Ps) of the suction side of the electric compressor 11 can be reduced, and the temperature rise of the electric motor 11a can be avoided.

  (5) Furthermore, when temperature protection of the electric motor 11a of the electric compressor 11 is required, the inside / outside air switching door 3c may be switched to the inside air mode. In this way, by switching the inside / outside air switching door 3c to the inside air mode and reducing the cooling performance of the evaporator 5, the degree of superheat of the refrigerant on the suction side of the electric compressor 11 can be reduced. Thereby, the refrigerant | coolant pressure (suction | inhalation refrigerant | coolant pressure Ps) of the suction side of the electric compressor 11 can be reduced, and the temperature rise of the electric motor 11a can be avoided.

  (6) In the second embodiment described above, control characteristics having different reference values are selected for the two operation modes of the cooling operation mode and the heating operation mode, but the present invention is not limited to this. For example, even in the dehumidifying operation mode, the control characteristics for the heating operation mode may be applied, or the control characteristics for the dehumidifying operation mode may be selected.

  (7) In the second embodiment described above, since the superheat degree on the suction side of the electric compressor 11 is small when the electric compressor 11 is started, even in the cooling operation mode, for example, the superheat degree is If is smaller than a predetermined value, the same control characteristic as that in the heating operation mode may be selected, and if the degree of superheat becomes larger than the predetermined value, the control characteristic for the cooling operation mode may be selected.

  (8) Moreover, you may apply the above-mentioned refrigerating-cycle apparatus 10 to the ejector cycle known by the patent 3322263 etc. In this case, the variable throttle mechanism may be configured by an ejector provided with a variable needle.

  (10) In each of the above-described embodiments, the example in which the refrigeration cycle apparatus 10 of the present invention is applied to a vehicle air conditioner has been described. However, the application of the present invention is not limited to this. For example, the present invention may be applied to stationary air conditioners for home use and business use. Moreover, you may apply not only to the air-conditioner which can be switched between heating and cooling but also to a heating-only machine.

(11) Although the above-described refrigeration cycle apparatus 10 did not specify the type of refrigerant, the refrigerant is a supercritical cycle of vapor compression type such as CFC-based, HC-based alternative CFC, carbon dioxide (CO ₂ ), and sub-cycle. It may be applicable to any of the critical cycles.

It is a schematic block diagram of the vehicle air conditioner of 1st Embodiment. It is a block diagram of the electric control part of the vehicle air conditioner of 1st Embodiment. It is a whole flowchart which shows the opening degree setting process of the electric expansion valve of 1st Embodiment. It is a control characteristic diagram in which the motor speed and the motor current value of the electric motor of the electric compressor of the first embodiment are associated with the motor temperature. It is a schematic block diagram of the vehicle air conditioner of 2nd Embodiment. It is a flowchart which shows the principal part of the opening degree setting process of the electric expansion valve of 2nd Embodiment. It is a control characteristic diagram in which the motor speed and the motor current value of the electric motor of the electric compressor of the second embodiment are associated with the motor temperature.

Explanation of symbols

5 Evaporator 11 Electric Compressor 11a Electric Motor 11b Compression Mechanism 13 Outdoor Heat Exchanger 16 Variable Throttle Mechanism 19 Drive Circuit (Inverter Device)

Claims (7)

An electric compressor (11a) including a compression mechanism (11b) for sucking and compressing refrigerant, and an electric motor (11a) that drives the compression mechanism (11b) and can be cooled by refrigerant on the suction side of the compression mechanism (11b). )When,
A variable throttle mechanism (12, 16) for depressurizing the refrigerant discharged from the electric compressor (11);
Motor temperature detecting means for detecting the motor temperature of the electric motor (11a);
Protection determination means for determining whether or not the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value;
When it is determined by the protection determination means that the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value, at least the opening of the variable throttle mechanism (12, 16) is controlled not to decrease. Motor protection control means ;
A drive circuit (19) for driving the electric motor (11a),
The drive circuit (19) detects a motor current value output to the electric motor (11a) and detects a motor rotation number of the electric motor (11a),
The motor temperature detecting means is configured to calculate the motor temperature from the motor rotational speed and the motor current value detected by the drive circuit based on a control characteristic in which the motor rotational speed and the motor current value are associated with the motor temperature in advance. To detect and
In the control characteristic, the reference value corresponding to the motor rotation speed and the motor current value is defined in advance, and further, as the reference value, the motor temperature is at least compared with the first reference value and the first reference value. A high second reference value is defined,
The protection determination means determines whether the motor temperature calculated and detected by the motor temperature detection means is equal to or higher than the first reference value defined in the control characteristics;
The motor protection control means is configured such that the variable throttle mechanism (12, 16) when the motor temperature calculated and detected by the motor temperature detection means is equal to or higher than the first reference value and lower than the second reference value. The refrigeration cycle is controlled so that the opening degree of the variable throttle mechanism (12, 16) increases when the opening degree of the variable throttle mechanism (12, 16) becomes larger than the second reference value. apparatus. An electric compressor (11a) including a compression mechanism (11b) for sucking and compressing refrigerant, and an electric motor (11a) that drives the compression mechanism (11b) and can be cooled by refrigerant on the suction side of the compression mechanism (11b). )When,
A variable throttle mechanism (12, 16) for depressurizing the refrigerant discharged from the electric compressor (11);
Motor temperature detecting means for detecting the motor temperature of the electric motor (11a);
Protection determination means for determining whether or not the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value;
When it is determined by the protection determination means that the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value, at least the opening of the variable throttle mechanism (12, 16) is controlled not to decrease. Motor protection control means ;
A drive circuit (19) for driving the electric motor (11a);
Suction refrigerant superheat detection means for detecting the refrigerant superheat degree on the suction side of the electric compressor (11);
Control characteristic selection means for selecting a specific control characteristic from among the plurality of control characteristics in which the different reference values are defined in advance based on the refrigerant superheat degree detected by the suction refrigerant superheat degree detection means,
The drive circuit (19) detects a motor current value output to the electric motor (11a) and detects a motor rotation number of the electric motor (11a),
The motor temperature detecting means is configured to calculate the motor temperature from the motor rotational speed and the motor current value detected by the drive circuit based on a control characteristic in which the motor rotational speed and the motor current value are associated with the motor temperature in advance. To detect and
In the control characteristic, the reference value corresponding to the motor rotation speed and the motor current value is defined in advance,
The protection determination means determines whether or not the motor temperature calculated and detected by the motor temperature detection means is equal to or higher than a reference value defined in the specific control characteristic. apparatus. It is configured as a heat pump that can be switched at least between a cooling operation mode that cools the heat exchange target fluid with a refrigerant and a heating operation mode that heats the heat exchange target fluid with a refrigerant,
An electric compressor (11a) including a compression mechanism (11b) for sucking and compressing refrigerant, and an electric motor (11a) that drives the compression mechanism (11b) and can be cooled by refrigerant on the suction side of the compression mechanism (11b). )When,
A variable throttle mechanism (12, 16) for depressurizing the refrigerant discharged from the electric compressor (11);
Motor temperature detecting means for detecting the motor temperature of the electric motor (11a);
Protection determination means for determining whether or not the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value;
When it is determined by the protection determination means that the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value, at least the opening of the variable throttle mechanism (12, 16) is controlled not to decrease. Motor protection control means ;
A drive circuit (19) for driving the electric motor (11a);
Control characteristic selection means for selecting a specific control characteristic from a plurality of the control characteristics in which the different reference values are defined in advance based on the operation mode,
The drive circuit (19) detects a motor current value output to the electric motor (11a) and detects a motor rotation number of the electric motor (11a),
The motor temperature detecting means is configured to calculate the motor temperature from the motor rotational speed and the motor current value detected by the drive circuit based on a control characteristic in which the motor rotational speed and the motor current value are associated with the motor temperature in advance. To detect and
In the control characteristic, the reference value corresponding to the motor rotation speed and the motor current value is defined in advance,
The control characteristic selection means, when the operation mode is the cooling operation mode, the specific control characteristic in which the reference value lower than the reference value specified in the control characteristic in the heating operation mode is defined. Select
The protection determination means determines whether or not the motor temperature calculated and detected by the motor temperature detection means is equal to or higher than a reference value defined in the specific control characteristic. apparatus. An electric compressor (11a) including a compression mechanism (11b) for sucking and compressing refrigerant, and an electric motor (11a) that drives the compression mechanism (11b) and can be cooled by refrigerant on the suction side of the compression mechanism (11b). )When,
A variable throttle mechanism (12, 16) for depressurizing the refrigerant discharged from the electric compressor (11);
Motor temperature detecting means for detecting the motor temperature of the electric motor (11a);
Protection determination means for determining whether or not the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value;
When it is determined by the protection determination means that the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value, at least the opening of the variable throttle mechanism (12, 16) is controlled not to decrease. Motor protection control means ;
A heat dissipating heat exchanger (6, 13) for cooling the refrigerant on the discharge side of the electric compressor (11);
A first electric blower (13a) for blowing outdoor air to the heat dissipation heat exchanger (13);
First electric blower control means for controlling the rotation speed of the first electric blower (13a),
The variable throttle mechanism (12, 16) depressurizes the refrigerant on the outlet side of the heat dissipation heat exchanger (6, 13), and the refrigerant pressure on the discharge side of the electric compressor (11) is used for the heat dissipation. Controlled so as to approach the target high pressure determined based on the refrigerant temperature on the outlet side of the heat exchanger (6, 13),
The motor protection control means reduces the target high pressure when the motor temperature detected by the motor temperature detection means is equal to or higher than the reference value,
When it is determined by the protection determination means that the motor temperature detected by the motor temperature detection means is equal to or higher than the reference value, the first electric blower control means rotates the number of rotations of the first electric blower (13a). A refrigeration cycle apparatus characterized by raising An evaporator (5) for evaporating the refrigerant decompressed by the variable throttle mechanism (12, 16);
A second electric blower (4) for blowing heat exchange target fluid to the evaporator (5);
A second electric blower control means for controlling the rotational speed of the second electric blower (4),
When it is determined by the protection determination means that the motor temperature detected by the motor temperature detection means is equal to or higher than the reference value, the second electric blower control means is the number of rotations of the second electric blower (4). The refrigeration cycle apparatus according to claim 4 , wherein the refrigeration cycle apparatus is lowered. An evaporator (5) for evaporating the refrigerant decompressed by the variable throttle mechanism (12, 16);
An inside / outside air switching control means capable of switching the heat exchange target fluid blown to the evaporator (5) between an inside air mode for introducing from the room and an outside air mode for introducing from the outside;
The inside / outside air switching control means switches to the inside air mode when the protection judging means judges that the motor temperature detected by the motor temperature detecting means is equal to or higher than the reference value. 4. The refrigeration cycle apparatus according to 4 . An electric compressor (11a) including a compression mechanism (11b) for sucking and compressing refrigerant, and an electric motor (11a) that drives the compression mechanism (11b) and can be cooled by refrigerant on the suction side of the compression mechanism (11b). )When,
A variable throttle mechanism (12, 16) for depressurizing the refrigerant discharged from the electric compressor (11);
Motor temperature detecting means for detecting the motor temperature of the electric motor (11a);
Protection determination means for determining whether or not the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value;
When it is determined by the protection determination means that the motor temperature detected by the motor temperature detection means is equal to or higher than a reference value, at least the opening of the variable throttle mechanism (12, 16) is controlled not to decrease. Motor protection control means ,
The refrigeration cycle apparatus, wherein the motor temperature detection means is a motor temperature detection sensor for detecting a motor temperature of the electric motor (11a) .

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