JP2009243784A - Refrigerant shortage detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a versatile refrigerant shortage detection device appropriately detecting shortage of a refrigerant. <P>SOLUTION: As a radiator 12, a subcool type condenser comprising a heat exchange part 12a for condensation, a liquid receiving part 12b and a heat exchange part 12c for supercooling is adopted. The refrigerant shortage detection device is provided with: a condensation refrigerant temperature sensor 25 for detecting the temperature of a refrigerant which has undergone heat radiation by the heat exchange part 12a for condensation; and a supercooling refrigerant temperature sensor 26 for detecting the temperature of a refrigerant which has undergone heat radiation by the heat exchange part 12c for supercooling. The versatile refrigerant shortage detection device is further provided with a refrigerant shortage determination means for determining shortage of the amount of a refrigerant filled in a refrigeration cycle device 10 when a temperature difference Tco-Tsc obtained by subtracting a detection value Tsc by the supercooling refrigerant temperature sensor 26 from a detection value Tco by the condensation refrigerant temperature sensor 25 becomes below a determination value KT, so as to appropriately detect shortage of the amount of the refrigerant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a refrigerant shortage detection device that detects that the amount of refrigerant charged in a refrigeration cycle device is insufficient.

  2. Description of the Related Art Conventionally, a refrigerant shortage detection device that detects that the amount of refrigerant charged in a vapor compression refrigeration cycle device is insufficient is known.

  For example, in the refrigerant shortage detection device of Patent Document 1, the point determined based on the pressure and the outside air temperature of the compressor suction refrigerant on the control map stored in advance by the control device is based on the compressor rotation speed. When it is lower than the determined threshold value, it is determined that the amount of refrigerant charged in the refrigeration cycle apparatus is insufficient.

Further, in the refrigerant shortage detection device applied to the low temperature showcase and the refrigeration cycle device for a refrigerator of Patent Document 2, the volume flow rate of the refrigerant flowing out from the liquid receiver is detected, and the detection flow value is determined in advance. When the value is higher than the value, it is determined that the amount of refrigerant charged in the refrigeration cycle apparatus is insufficient.
JP-A-6-194014 JP-A-7-151432

  However, the refrigerant shortage detection device of Patent Document 1 detects refrigerant shortage on the assumption that the pressure of the refrigerant sucked by the compressor decreases at a predetermined rate as the compressor rotational speed increases (Patent Document 1). (See paragraph 0005).

  Therefore, for example, in a refrigeration cycle apparatus that employs a variable capacity compressor configured such that the discharge capacity can be continuously changed as a compressor, a refrigerant shortage cannot be detected appropriately. The reason is that, in a variable capacity compressor, even if the number of revolutions of the compressor increases, changing the discharge capacity changes the pressure drop rate of the refrigerant sucked by the compressor.

  Further, in the refrigerant shortage detection device of Patent Document 2, the determination value is determined on the assumption that the flow rate of refrigerant flowing out of the liquid receiver during normal operation is substantially constant (see Paragraph 0009 of Patent Document 2). Therefore, for example, in the refrigeration cycle apparatus that changes the flow rate of the circulating refrigerant circulating in the cycle due to the air conditioning heat load or the like, the refrigerant shortage cannot be detected appropriately.

  In view of the above points, an object of the present invention is to provide a highly versatile refrigerant shortage detecting device that can appropriately detect that the amount of refrigerant charged in the refrigeration cycle apparatus is insufficient.

  In order to achieve the above object, according to the first aspect of the present invention, a refrigerant shortage detection device applied to a refrigeration cycle device (10) including a radiator (12) that dissipates heat from a refrigerant discharged from the compressor (11). The heat radiator (12) separates the gas-liquid of the refrigerant flowing out of the heat exchanger for condensation (12a) and the heat exchanger for condensation (12a) for condensing the refrigerant discharged from the compressor (11). Part (12b) and a supercooling heat exchange part (12c) for supercooling the saturated liquid phase refrigerant flowing out from the liquid receiving part (12b), and further, in the heat exchange part for condensation (12a) The first temperature detection means (25, 27) for detecting the physical quantity correlated with the temperature of the refrigerant that has radiated heat and the physical quantity correlated with the temperature of the refrigerant radiated by the supercooling heat exchange section (12c) are detected. Second temperature detection means (26) and first temperature detection The second detection temperature (Tsc) determined based on the detection value of the second temperature detection means (26) is subtracted from the first detection temperature (Tco) determined based on the detection value of the stage (25, 27). When the subtraction value (Tco−Tsc) is equal to or less than a predetermined determination value (KT), the refrigerant shortage determination means (determining that the amount of refrigerant charged in the refrigeration cycle device (10) is insufficient) S7).

  By the way, in the refrigeration cycle apparatus (10) employing the heat radiator (12) configured to include the heat exchanger for condensation (12a), the liquid receiver (12b), and the heat exchanger for supercooling (12c), If the amount of refrigerant charged is in an appropriate range, surplus liquid phase refrigerant can be stored in the liquid receiving part (12b), so that only the saturated liquid phase refrigerant can flow into the supercooling heat exchange part (12c). it can.

  Therefore, the temperature of the refrigerant radiated by the heat exchanger for condensation (12a) becomes a saturation temperature corresponding to the condensation pressure of the refrigerant. On the other hand, since the saturated liquid phase refrigerant is stably cooled in the supercooling heat exchange section (12c), the temperature of the refrigerant dissipated in the supercooling heat exchange section (12c) is almost stable. It becomes temperature which has.

  As a result, the temperature difference between the temperature of the refrigerant that has radiated heat in the heat exchanger for condensation (12a) and the temperature that has radiated heat in the heat exchanger for subcooling (12c) becomes a substantially constant value.

  On the other hand, if the amount of refrigerant charged in the refrigeration cycle device (10) is insufficient, the saturated liquid phase refrigerant in the liquid receiving section (12b) is insufficient, and not only the saturated liquid phase refrigerant but also the saturated gas phase. The phase refrigerant also flows into the supercooling heat exchange section (12c). For this reason, the refrigerant condenses also in the supercooling heat exchange section (12c).

  As a result, the saturated liquid phase refrigerant is hardly cooled in the supercooling heat exchange section (12c), and the degree of supercooling of the liquid phase refrigerant radiated in the supercooling heat exchange section (12c) is reduced.

  In other words, when the amount of refrigerant charged is insufficient, the temperature of the refrigerant radiated by the heat exchanger for condensation (12a) and the heat for supercooling are compared with the case where the amount of refrigerant charged is appropriate. The temperature difference with the temperature at which heat is radiated in the exchange part (12c) is reduced. In addition, the degree of supercooling in this claim shows the absolute value of the temperature fall amount from the saturation temperature corresponding to the condensing pressure of a refrigerant | coolant.

  Therefore, as in the first aspect of the present invention, the temperature difference (Tco−Tsc) obtained by subtracting the second detection temperature (Tsc) from the first detection temperature (Tco) is equal to or less than the determination value (KT). Sometimes, the refrigerant shortage determination means (S7) that determines that the refrigerant amount charged in the refrigeration cycle apparatus (10) is insufficient can be appropriately detected.

  Further, even in the refrigeration cycle apparatus in which the refrigerant discharge capacity of the compressor (11) varies, the increase / decrease in the rotational speed of the compressor (11) does not correlate with the pressure change of the refrigerant sucked into the compressor (11). Even in the refrigeration cycle apparatus, since the temperature difference is reduced due to the shortage of the refrigerant amount described above, a highly versatile refrigerant shortage detection apparatus applicable to these refrigeration cycle apparatuses can be provided.

  As in the second aspect of the present invention, in the refrigerant shortage detecting device according to the first aspect, the first temperature detecting means detects the temperature of the refrigerant that has dissipated heat in the heat exchanger for condensation (12a). It may be a temperature sensor (25), and the second temperature detection means may be a supercooled refrigerant temperature sensor (26) that detects the temperature of the refrigerant radiated by the supercooling heat exchange section (12c).

  As in the third aspect of the present invention, in the refrigerant shortage detection device according to the first aspect, the first temperature detection means detects the pressure of the refrigerant radiated by the supercooling heat exchange section (12c). It is a cooling refrigerant pressure sensor (27), and the second temperature detection means may be a supercooling refrigerant temperature sensor (26) that detects the temperature of the refrigerant that has radiated heat in the supercooling heat exchange section (12c).

  Since the pressure of the refrigerant radiated by the heat exchanger for supercooling (12c) is equal to the pressure of the refrigerant radiated by the heat exchanger for condensation (12a), heat is radiated by the heat exchanger for condensation (12a). This value corresponds to the condensing pressure of the refrigerant. Therefore, the saturation temperature of the saturated liquid phase refrigerant determined by the physical properties of the refrigerant can be estimated from the condensation pressure.

  That is, the pressure of the refrigerant dissipated in the supercooling heat exchanging section (12c) is a physical quantity that correlates with the temperature of the refrigerant dissipated in the condensation heat exchanging section (12a), and the supercooling refrigerant pressure sensor (27 ) Can be determined from the detected pressure (Psc). Therefore, the shortage of the refrigerant amount charged in the refrigeration cycle apparatus (10) can be detected appropriately.

  Further, as in the invention according to claim 4, in the refrigerant shortage detection device according to claim 3, the supercooling refrigerant pressure sensor (27) depressurizes the refrigerant flowing out of the radiator (12) from the radiator (12). The refrigerant shortage detection device according to any one of claims 2 to 4 may be provided in the refrigerant flow path leading to the decompression means (13) to be expanded, or as in the invention according to claim 5. The supercooled refrigerant temperature sensor (26) may be provided in the refrigerant flow path from the radiator (12) to the decompression means (13) for decompressing and expanding the refrigerant flowing out of the radiator (12).

  Thereby, the mountability at the time of arrange | positioning a 1st temperature detection means (27) and a 2nd temperature detection means (26) in a refrigerating-cycle apparatus (10) can be improved, and the versatility of a refrigerant | coolant shortage detection apparatus is improved further. Can be made.

  As in the sixth aspect of the invention, in the refrigerant shortage detection device according to any one of the first to fifth aspects, specifically, the determination value (KT) may be 3 ° C. In addition, 3 degreeC in this claim does not only mean that it is 3 degreeC completely, but the meaning which includes the value which shifted | deviated slightly from 3 degreeC by a measurement error etc. is included.

  According to a seventh aspect of the present invention, in the refrigerant shortage detecting device according to any one of the first to sixth aspects, the compressor is driven by a driving force transmitted from a driving source, and the driving source It is a variable capacity type compressor (11) always connected to.

  In this type of variable displacement compressor (11), the discharge capacity can be made substantially 0%, so that the operation of the refrigeration cycle apparatus (10) can be stopped without interrupting the power transmission from the drive source. it can. That is, even if the operation of the refrigeration cycle apparatus (10) is stopped, the variable displacement compressor (11) may be driven.

  In such a case, if the refrigerant flow rate is insufficient, there is a risk of poor lubrication of the variable capacity compressor (11). It is extremely effective to be able to properly detect the shortage of the amount of refrigerant charged.

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

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of a vehicle air conditioner 1 including a refrigeration cycle apparatus 10 to which the refrigerant shortage detection device of the present invention is applied.

  The refrigeration cycle apparatus 10 employs a normal chlorofluorocarbon refrigerant (specifically, HFC-134a) as a refrigerant, and constitutes a subcritical cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant. . Further, the refrigerant is mixed with refrigerating machine oil for lubricating the compressor 11, and the refrigerating machine oil circulates in the cycle together with the refrigerant.

  The compressor 11 sucks, compresses and discharges the refrigerant in the refrigeration cycle apparatus 10, and a driving force is transmitted from a vehicle travel engine (not shown) via a clutchless pulley and belt. Driven by rotation.

  The compressor 11 is a well-known swash plate type variable displacement compressor configured such that a discharge capacity can be continuously changed by a control current Ic output from an air conditioning controller 20 described later. The discharge capacity is the geometric volume of the working space where the refrigerant is sucked and compressed, that is, the cylinder volume between the top dead center and the bottom dead center of the piston stroke.

  Specifically, the compressor 11 includes a swash plate chamber (not shown) that introduces suction refrigerant and discharge refrigerant, an electromagnetic capacity control valve 11a that adjusts the ratio of suction refrigerant and discharge refrigerant introduced into the swash plate chamber, It has a swash plate (not shown) that displaces the tilt angle in accordance with the pressure in the swash plate chamber. The piston stroke (discharge capacity) is changed according to the inclination angle of the swash plate.

  The electromagnetic capacity control valve 11a includes a pressure responsive mechanism that generates a force due to a differential pressure between the suction refrigerant pressure and the discharge refrigerant pressure of the compressor 11, and an electromagnetic mechanism that generates an electromagnetic force opposite to the force due to the differential pressure. It is built in and adjusts the valve opening (ratio of suction refrigerant and discharge refrigerant) by the balance between the force due to the differential pressure and the electromagnetic force to change the pressure in the swash plate chamber.

  Further, the electromagnetic force of the electromagnetic mechanism is determined by the control current Ic output from the air conditioning controller 20, and when the control current Ic is increased, the pressure in the swash plate chamber decreases and the inclination angle of the swash plate increases. Thereby, a piston stroke increases and the discharge flow rate of the compressor 11 increases. Conversely, when the control current Ic is decreased, the pressure in the swash plate chamber increases and the tilt angle of the swash plate decreases. Thereby, a piston stroke reduces and the discharge flow rate of the compressor 11 reduces.

  Further, in the compressor 11, the discharge capacity can be continuously changed in a range of approximately 0% to 100% by adjusting the control current Ic. Thus, since the discharge capacity can be reduced to about 0% in the compressor 11 of the present embodiment, as described above, the clutch 11 can be configured to be always connected to the vehicle travel engine. .

  A radiator 12 is connected to the refrigerant discharge side of the compressor 11. The radiator 12 is a heat-dissipating heat exchanger that exchanges heat between the high-temperature and high-pressure refrigerant discharged from the compressor 11 and the outside air (air outside the passenger compartment) blown by the cooling fan 12d to radiate the high-pressure refrigerant.

  In the present embodiment, as the radiator 12, a heat exchanger for condensation 12a that condenses the refrigerant, and a liquid receiver that separates gas and liquid of the refrigerant cooled by the heat exchanger 12a for condensation and stores excess liquid phase refrigerant. A so-called subcooled condenser is employed which includes a modulator section 12b and a supercooling heat exchange section 12c for supercooling the saturated liquid phase refrigerant flowing out of the modulator section 12b.

  The cooling fan 12 d is an electric blower in which the rotation speed (the amount of blown air) is controlled by a control voltage output from the air conditioning control device 20.

  A known temperature type expansion valve 13 is connected to the outlet side of the radiator 12 (specifically, the outlet side of the heat exchanger 12c for supercooling). The temperature type expansion valve 13 is a pressure reducing unit that decompresses and expands the high-pressure refrigerant radiated by the radiator 12 and also a flow rate adjusting unit that adjusts the flow rate of the refrigerant flowing out to the downstream side (low pressure side) of the temperature type expansion valve 13. is there.

  Specifically, the temperature type expansion valve 13 has a temperature sensing part for detecting the degree of superheat of the evaporator 14 outlet side refrigerant, which will be described later, and corresponds to the temperature of the evaporator 14 outlet side refrigerant inside the temperature sensing part. The refrigerant passage area (refrigerant flow rate) of the variable throttle mechanism 15b is adjusted by the balance between the internal pressure of the temperature sensing portion and the refrigerant pressure on the outlet side of the evaporator 13. Thereby, the superheat degree of the evaporator 13 outlet side refrigerant | coolant can be adjusted so that it may approach a predetermined value.

  An evaporator 14 is connected to the outlet side of the temperature type expansion valve 13. The evaporator 14 performs heat exchange between the low-pressure refrigerant decompressed by the temperature type expansion valve 13 and the blown air blown into the vehicle compartment from the blower fan 14a, and evaporates the low-pressure refrigerant to exert an endothermic effect. It is a heat exchanger. The refrigerant outlet side of the evaporator 14 is connected to the refrigerant suction side of the compressor 11.

  The blower fan 14 a is an electric blower in which the rotation speed (the amount of blown air) is controlled by a control voltage output from the air conditioning controller 20.

  In addition, the evaporator 14 is arrange | positioned in the case 15 which forms the air passage of vehicle interior blowing air in the indoor air conditioning unit of a vehicle air conditioner. Further, on the downstream side of the air flow of the evaporator 14 in the case 15, a cold air passage such as a cold air passage for heating and a cold air bypass passage for flowing the cold air after passing through the evaporator 14 is formed.

  The cold air passage for heating is a cold air passage that guides the cold air to the heater core 16 that is a heat exchanger for heating that reheats the cold air that has passed through the evaporator 14. The heater core 16 reflows the cold air by causing the high-temperature engine cooling water circulating in the cooling water circuit of the vehicle running engine to flow into the interior and exchanging heat between the engine cooling water and the cold air after passing through the evaporator 14. It is.

  The cold air bypass passage is a cold air passage through which the cold air after passing through the evaporator 14 flows so as to bypass the heater core 16. Further, an air mix door 17 is disposed between the evaporator 14 and the heater core 16 as door means for changing the air volume ratio between the amount of cold air flowing to the heating cold air passage side and the amount of cold air flowing to the cold air bypass passage side. ing.

  The air mix door 17 is connected to a driving servo motor via a link mechanism (not shown) and is rotated. The operation of the servo motor for driving the air mix door 17 is controlled by a control signal output from the air conditioning controller 20.

  On the downstream side of the cold air bypass passage and the air flow of the heater core 16, a mixing space for mixing the cold air that has passed through the cold air bypass passage and the hot air heated by the heater core 16 is formed. Then, the temperature of the indoor air is adjusted by mixing the cool air and the warm air in this mixing space.

  The indoor blast air whose temperature is adjusted in the mixed space passes through the defroster opening, face opening, and foot opening (not shown), respectively, on the inner surface of the vehicle window glass, the upper body (face) side of the occupant, and the occupant It blows out toward the lower body (foot) side.

  Next, an outline of the electric control unit of the present embodiment will be described. The air conditioning control device 20 includes a known microcomputer including a CPU, a ROM, a RAM, and the like and peripheral circuits thereof. Then, various calculations and processes are performed based on the control program stored in the ROM, and the operations of the above-described various electric actuators 11a, 12d, 14a, 17 and the like are controlled.

  An air conditioning sensor group 21 to 26 and an operation panel 30 disposed in the passenger compartment are connected to the input side of the air conditioning control device 20. The air conditioning sensor group 21 to 26 is provided with a detection signal and an operation panel 30. The operation signals of the various operation switches 31 to 33 are input.

  Specifically, the air conditioning sensor group includes an outside air temperature sensor 21 that detects the outside air temperature Tam, an inside air temperature sensor 22 that detects the inside air temperature Tr, a solar radiation sensor 23 that detects the amount of solar radiation Ts incident on the vehicle interior, and an evaporator. 14, an evaporator temperature sensor 24 that detects the fin temperature Te, a condensing refrigerant temperature sensor 25 that is a first temperature detecting means that detects the temperature Tco of the refrigerant radiated by the condensing heat exchanging section 12 a, and a supercooling heat exchanging section. A supercooled refrigerant temperature sensor 26, which is a second temperature detecting means for detecting the temperature Tsc of the refrigerant that has radiated heat at 12c, is provided.

  In the present embodiment, as the condensed refrigerant temperature sensor 25, specifically, a thermistor that detects the refrigerant temperature flowing from the modulator section 12 b to the supercooling heat exchange section 12 c is employed. Of course, other types of detection means (for example, a thermocouple) may be employed. Furthermore, the refrigerant temperature stored in the modulator unit 12b may be detected, or the surface temperature of the refrigerant flow path from the condensation heat exchange unit 12b outlet side to the supercooling heat exchange unit 12c may be detected.

  Further, as the supercooling refrigerant temperature sensor 26, specifically, a thermistor that detects the surface temperature of the refrigerant pipe from the outlet side of the supercooling heat exchange section 12c to the inlet side of the temperature type expansion valve 13 is employed. Of course, other types of detection means may be employed, and the temperature of the refrigerant flowing through the refrigerant pipe (refrigerant flow path) from the outlet side of the supercooling heat exchange section 12c to the inlet side of the temperature type expansion valve 13 may be adjusted. It may be detected directly.

  Specifically, the operation switch of the operation panel 30 includes an air conditioner switch 31 that outputs an operation command signal for the vehicle air conditioner, an auto switch 32 that outputs an automatic control request signal for requesting automatic control of the air conditioning state, and a space to be cooled. A temperature setting switch 33 or the like serving as target temperature setting means for setting a target temperature Tset in the vehicle interior is provided.

  Further, the display panel of the operation panel 30 is provided with a warning lamp 34 that is a warning means for warning the occupant when it is determined that the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient. Yes.

  Further, on the output side of the air-conditioning control device 20, an electric capacity control valve 11 a of the compressor 11, an electric motor of the cooling fan 12 d and the blower fan 14 a, an electric actuator such as a servo motor of the air mix door 17, and the operation panel 30. Are connected, and the operation of these devices is controlled by the output signal of the air conditioning controller 20.

  Next, the operation of the present embodiment in the above configuration will be described with reference to FIG. FIG. 2 is a flowchart showing a control process executed by the air conditioning control device 20. This control process starts when the auto switch 32 is turned on (ON) in a state where a vehicle start switch (ignition switch) (not shown) is turned on.

  First, as shown in FIG. 2, in step S <b> 1, flags, timers, and the like are initialized, and in the next step S <b> 2, the detection signals detected by the air conditioning sensor groups 21 to 26 and the operation of the operation panel 30. Read the signal.

Next, in step S3, a target blowing temperature TAO of the vehicle cabin blowing air is calculated. The target blowing temperature TAO is calculated by the following formula F1 based on the air conditioning thermal load fluctuation and the set temperature Tset set by the temperature setting switch 33.
TAO = Kset × Tset−Kr × Tr−Kam × Tam−Ks × Ts + C (F1)
Kset, Kr, Kam, and Ks are control gains, and C is a correction constant.

  Next, in step S4, control states of various air conditioning control devices excluding the compressor 11 are determined. That is, among the various electric actuators connected to the output side of the air conditioning control device 20, outputs to the electric motor of the cooling fan 12d and the blower fan 14a, the servo motor of the air mix door 17, etc., excluding the electromagnetic capacity control valve 11a. The control signal to be determined is determined.

  For example, with respect to the control signal (control voltage) output to the electric motor of the blower fan 14a, the control signal stored in the air-conditioning control device 20 in advance is referred to based on the target blowout temperature TAO, and appropriate according to the TAO. It decides so that it may become the amount of blast.

  More specifically, the control voltage is set to the maximum value in the extremely low temperature range (maximum cooling range) and the extremely high temperature range (maximum heating range) of TAO, and the air flow rate is set to the maximum air volume. As the TAO rises from the extremely low temperature range toward the intermediate temperature range, or as the TAO decreases from the extremely high temperature range toward the intermediate temperature range, the control voltage is decreased to reduce the air flow rate. Further, when the TAO enters a predetermined intermediate temperature range, the control voltage is set to the minimum value, and the air volume is set to the minimum air volume.

  Next, the target refrigerant | coolant evaporation temperature TEO in the evaporator 14 is determined in step S5. Specifically, based on the target blowing temperature TAO, the target refrigerant evaporation temperature TEO is determined with reference to a control map stored in the air conditioning control device 20 in advance. In the present embodiment, it is determined that TEO increases as TAO increases.

  Next, in step S6, the refrigerant discharge capacity of the compressor 11 is determined. Specifically, a deviation En (Te−TEO) between the fin temperature Te of the evaporator 14 detected by the evaporator temperature sensor 24 and the target refrigerant evaporation temperature TEO is calculated, and Te is calculated based on the deviation En. The control current Ic to be output to the electromagnetic capacity control valve 11a is determined by a feedback control method based on proportional-integral control (PI control) so as to approach TEO.

  Next, in step S7, it is determined whether or not the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient. Specifically, in step S7, a temperature difference Tco-Tsc obtained by subtracting the second detected temperature Tsc detected by the supercooled refrigerant temperature sensor 26 from the first detected temperature Tco detected by the condensed refrigerant temperature sensor 25 is calculated in advance. It is determined whether or not it is equal to or less than a predetermined determination value KT.

  In the present embodiment, the determination value KT is specifically 3 ° C. If Tco−Tsc ≦ KT in step S7, it is determined that the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient, and the process proceeds to step S8. In step S8, the warning lamp 34 is turned on and the process proceeds to step S9.

  If Tco−Tsc ≦ KT is not satisfied in step S7, it is determined that the amount of refrigerant charged in the refrigeration cycle apparatus 10 is not insufficient, and the process proceeds to step S9. Therefore, the control step S7 of the present embodiment constitutes a refrigerant shortage determination means. In this embodiment, the control step S7, the condensed refrigerant temperature sensor 25, and the supercooled refrigerant temperature sensor 26 constitute a refrigerant shortage detection device. The

  In step S9, a control signal is output from the air conditioning controller 20 to the electric actuator so that the control state determined in step S4 is obtained. In the next step S10, the process waits for the control period τ, and when it is determined that the control period τ has elapsed, the process returns to step S2.

  In this embodiment, since it operates as described above, the refrigerant discharged from the compressor 11 circulates in the order of the radiator 12 → the temperature type expansion valve 13 → the evaporator 14 → the compressor 11, and the evaporator 14 The air blown into the passenger compartment can be cooled. A part of the air blown into the passenger compartment cooled by the evaporator 14 is reheated by the heater core 16 so that the temperature-conditioned air is blown into the passenger compartment and air conditioning in the passenger compartment is realized. .

  Furthermore, in this embodiment, since it is determined in step S7 whether or not the temperature difference Tco−Tsc is equal to or smaller than a predetermined determination value KT, the amount of refrigerant charged in the refrigeration cycle apparatus 10 is determined. It is possible to appropriately detect that the refrigerant is insufficient or that the refrigerant leaks during operation of the refrigeration cycle apparatus 10 and the refrigerant amount in the cycle is insufficient.

  Furthermore, if it is determined in step S7 that the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient, the warning lamp 34 is lit in step S8, so that the user can exceed the amount of refrigerant charged. We can make shortage recognized. Thereby, it is possible to prevent an adverse effect on the durable life of the compressor 11 by measures such as charging the refrigerant.

  This will be described in more detail with reference to FIG. FIG. 3 is a graph showing the relationship between the refrigerant amount (g) charged in the refrigeration cycle apparatus 10 and the degree of supercooling (° C.) of the refrigerant radiated by the heat exchanger 12c for supercooling.

  As in the present embodiment, in the subcool type condenser having the heat exchanger 12a for condensation, the modulator 12b, and the heat exchanger 12c for supercooling as the radiator 12, the amount of refrigerant charged in the refrigeration cycle apparatus 10 is reduced. If it is in an appropriate range, the surplus liquid phase refrigerant can be stored in the modulator section 12b, so that only the saturated liquid phase refrigerant can flow into the supercooling heat exchange section 12c.

  Therefore, the temperature of the refrigerant dissipated in the heat exchanger for condensation 12a becomes a saturation temperature corresponding to the condensation pressure of the refrigerant. On the other hand, since the saturated liquid-phase refrigerant is stably cooled in the supercooling heat exchange section 12c, as shown in FIG. 3, the temperature of the refrigerant radiated in the supercooling heat exchange section 12c is almost stable. The temperature has a degree of supercooling. As a result, the temperature difference between the temperature of the refrigerant that has dissipated heat at the condensing heat exchange unit 12a and the temperature of heat that has dissipated heat at the subcooling heat exchange unit 12c becomes a substantially constant value.

  On the other hand, if the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient, the saturated liquid phase refrigerant in the modulator unit 12b is insufficient, and not only the saturated liquid phase refrigerant but also the saturated gas phase refrigerant is supercooled. Will flow into the heat exchanger 12c. For this reason, a refrigerant | coolant condenses also in the heat exchange part 12c for supercooling.

  Therefore, the saturated liquid phase refrigerant is less likely to be cooled by the supercooling heat exchange unit 12c, and the degree of supercooling of the liquid phase refrigerant radiated by the supercooling heat exchange unit 12c is reduced, as shown in FIG. . As a result, the temperature difference between the temperature of the refrigerant radiated by the condensation heat exchange unit 12a and the temperature radiated by the subcooling heat exchange unit 12c is also reduced.

  Further, when the amount of refrigerant charged in the refrigeration cycle apparatus 10 is excessive, the condensed refrigerant is further cooled also in the heat exchanger for condensing 12a. Therefore, as shown in FIG. The degree of supercooling of the liquid-phase refrigerant that has radiated heat at 12c increases.

  From the above, when the amount of refrigerant filled is insufficient, the temperature of the refrigerant radiated by the heat exchanger for condensation 12a and the supercooling amount are compared with the case where the amount of refrigerant filled is appropriate. The temperature difference from the heat dissipated in the heat exchange part 12c is reduced. That is, when the amount of refrigerant charged is insufficient, the temperature difference Tco-Tsc obtained by subtracting the second detection temperature Tsc from the first detection temperature Tco is compared with the case where the amount of refrigerant charged is appropriate. to shrink.

  Further, according to the study by the present inventors, it has been found that there is no problem such as cold air is not blown from the vehicle air conditioner 1 until the temperature difference Tco−Tsc becomes 3 ° C. or less. ing. Therefore, according to the control step S7 constituting the refrigerant shortage determining means of the present embodiment, it is possible to appropriately detect the shortage of the refrigerant amount filled in the refrigeration cycle apparatus 10.

  Moreover, even in the refrigeration cycle apparatus in which the refrigerant discharge capacity of the compressor 11 varies depending on the air-conditioning heat load or the like as in the present embodiment, or the increase and decrease in the number of rotations and the compressor suction refrigerant as in the variable capacity compressor. Even in a refrigeration cycle apparatus that has no correlation in pressure change, the temperature difference Tco-Tsc is reduced due to a shortage of the refrigerant amount, so that it can be applied to these refrigeration cycle apparatuses, and the refrigerant shortage detection apparatus The versatility can be improved.

  In addition, when the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient, the refrigeration oil circulating in the cycle together with the refrigerant becomes difficult to return to the compressor 11, resulting in poor lubrication of the compressor 11. In particular, as in the present embodiment, in the case of a clutchless configuration in which the compressor 11 is always connected to the vehicle travel engine, the discharge capacity is substantially 0% even when the operation of the vehicle air conditioner 1 is stopped. Since the compressor is driven in the state, it greatly affects the durable life of the compressor 11.

  Further, when a swash plate type variable displacement compressor is employed as the compressor 11 as in the present embodiment, if the amount of refrigerant charged in the refrigeration cycle device 10 is insufficient, the inertia force of the piston increases and the piston is The problem of so-called top contact that collides with the housing in the operating direction is likely to occur, and the failure rate of the compressor 11 increases.

  Therefore, as in the present embodiment, in the refrigeration cycle apparatus 10 that employs a swash plate type variable displacement compressor that is always connected to the vehicle running engine as the compressor 11, the refrigerant charged by the refrigerant shortage detection device. It is extremely effective to be able to properly detect the lack of quantity and to alert the user of this.

  Further, since the excess or deficiency of the filled refrigerant can be managed by the temperature difference Tco-Tsc, the sight glass for visually recognizing the refrigerant circulating in the cycle or the refrigerant stored in the modulator unit 12b is abolished. The manufacturing cost of the refrigeration cycle apparatus 10 can be reduced.

(Second Embodiment)
In the present embodiment, as shown in the overall configuration diagram of FIG. 4, the condensed refrigerant temperature sensor 25 is abolished, and the pressure Psc of the refrigerant radiated by the supercooling heat exchanging portion 12 c is detected as the first temperature detecting means. A supercooling refrigerant pressure sensor 27 is employed. Further, the radiator 12 of the present embodiment is integrally configured so that the heat exchanger for condensation 12a, the modulator portion 12b, and the heat exchanger for subcooling 12c are directly connected to the respective inlets and outlets.

  The supercooling refrigerant temperature sensor 26 and the supercooling refrigerant pressure sensor 27 are specifically mounted on the refrigerant pipe extending from the outlet side of the supercooling heat exchange section 12c to the inlet side of the temperature type expansion valve 13. It is attached to the part. Other configurations are the same as those of the first embodiment. In FIG. 4, the same or equivalent parts as those in the first embodiment are denoted by the same reference numerals.

  Here, the pressure Psc of the refrigerant radiated by the subcooling heat exchange unit 12c is equal to the pressure of the refrigerant radiated by the condensation heat exchange unit 12a, and therefore the refrigerant radiated by the condensation heat exchange unit 12a. It becomes a value corresponding to the condensation pressure. Therefore, the saturation temperature of the saturated liquid phase refrigerant determined by the physical properties of the refrigerant can be estimated from the condensation pressure.

  For example, the relationship between the condensing pressure (MPa) and the saturation temperature (° C.) of the refrigerant of this embodiment is as shown in the graph of FIG. 5, and by storing this relationship in the air conditioning control device 20 in advance, The temperature Tco of the refrigerant radiated by the heat exchanger for condensation 12a can be estimated from the pressure Psc of the refrigerant radiated by the heat exchanger for subcooling 12c.

  That is, the pressure of the refrigerant radiated by the supercooling heat exchange unit 12c is a physical quantity having a correlation with the temperature of the refrigerant radiated by the condensation heat exchange unit 12a. Therefore, even if the vehicle air conditioner of this embodiment is operated, the same effect as that of the first embodiment can be obtained.

  Furthermore, both the supercooling refrigerant pressure sensor 27, which is the first temperature detection means constituting the refrigerant shortage detection device, and the supercooling refrigerant temperature sensor 26, which is the second temperature detection means, are connected to the temperature type from the outlet side of the radiator 12. Since it is attached to the refrigerant pipe reaching the inlet side 13 of the expansion valve, these can be easily attached. As a result, the mountability of both sensors can be improved, and the versatility of the refrigerant shortage detection device can be further improved.

(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, an example in which a swash plate type variable displacement compressor is employed as the compressor 11 has been described, but the compressor is not limited to this. For example, a fixed-capacity compressor that adjusts the refrigerant discharge capacity by changing the operating rate of the compressor operation by switching the electromagnetic clutch, or an electric compressor that adjusts the refrigerant discharge capacity by adjusting the rotation speed of the electric motor is adopted. Even if it is a refrigeration cycle apparatus, the refrigerant shortage determination apparatus of the present invention can be applied.

  (2) In the above-described embodiment, when it is determined in step S7 that the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient, the warning lamp 34 is turned on in step S8. Furthermore, you may make it reduce the refrigerant | coolant discharge capability of the compressor 11 in step S8. For example, if the discharge capacity is approximately 0%, that is, the operation of the compressor 11 is stopped, the compressor 11 can be reliably protected.

  (3) In the above-described embodiment, the example in which the temperature type expansion valve 13 is employed as the pressure reducing means has been described, but the pressure reducing means is not limited to this. For example, you may employ | adopt the electric expansion valve comprised by the electric actuator mechanism which consists of a stepping motor, and the valve mechanism driven by this electric actuator mechanism.

  (4) In the above-described embodiment, as shown in the flowchart of FIG. 2, it is determined whether or not the amount of refrigerant charged in the refrigeration cycle apparatus 10 is insufficient for each control period during the operation of the cycle. This determination may be performed only immediately after the start of the cycle.

  (5) In the above-described embodiment, the warning lamp 34 is employed as the warning means. However, for example, an acoustic device that issues a warning by sound, a vibration device that generates a warning by vibration, or the like may be employed.

  (6) In the above-described embodiment, an example in which a normal chlorofluorocarbon refrigerant is employed as the refrigerant has been described. However, the type of refrigerant is not limited to this. For example, a hydrocarbon-based refrigerant or the like may be employed as long as the cycle configuration condenses the refrigerant on the high pressure side of the cycle.

  (7) In the above-described embodiment, an example in which the refrigeration cycle apparatus 10 to which the refrigerant shortage determination apparatus of the present invention is applied is applied to a vehicle air conditioner, but the application of the present invention is not limited to this. For example, the present invention may be applied to a stationary refrigeration cycle apparatus such as a commercial refrigeration apparatus, a household refrigerator, a vending machine cooling apparatus, and a showcase with a refrigeration function.

  (8) In the above-described embodiment, the radiator 12 is an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, and the evaporator 14 is an indoor heat exchanger that is applied for cooling the vehicle interior. The present invention is applied to a heat pump cycle in which the evaporator 14 is configured as an outdoor heat exchanger that absorbs heat from a heat source such as outside air, and the radiator 12 is configured as an indoor heat exchanger that heats a heated fluid such as air or water. May be.

It is a whole block diagram of the vehicle air conditioner of 1st Embodiment. It is a flowchart which shows control of the refrigerating-cycle apparatus of 1st Embodiment. It is a graph which shows the relationship between the refrigerant | coolant amount with which the refrigerating-cycle apparatus of 1st Embodiment was filled, and the supercooling degree of the refrigerant | coolant which flowed out from the heat radiator. It is a whole block diagram of the vehicle air conditioner of 2nd Embodiment. It is a graph which shows the relationship between the condensation pressure of the refrigerant | coolant of 2nd Embodiment, and saturation temperature.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Refrigeration cycle apparatus 11 Compressor 12 Radiator 12a Condensation heat exchange part 12b Modulator part 12c Supercooling heat exchange part 13 Thermal expansion valve 25 Condensed refrigerant temperature sensor 26 Supercooled refrigerant temperature sensor 27 Supercooled refrigerant pressure sensor

Claims (7)

A refrigerant shortage detection device applied to a refrigeration cycle device (10) including a radiator (12) that dissipates heat from a refrigerant discharged from a compressor (11),
The radiator (12) includes a heat exchanger for condensation (12a) that condenses the refrigerant discharged from the compressor (11), and a liquid receiver that separates gas-liquid refrigerant flowing out of the heat exchanger for condensation (12a). (12b), and a supercooling heat exchange section (12c) for supercooling the saturated liquid phase refrigerant that has flowed out of the liquid receiving section (12b),
Furthermore, a first temperature detection means (25, 27) for detecting a physical quantity having a correlation with the temperature of the refrigerant radiated by the heat exchanger for condensation (12a),
A second temperature detecting means (26) for detecting a physical quantity having a correlation with the temperature of the refrigerant radiated by the supercooling heat exchange section (12c);
The second detected temperature determined based on the detected value of the second temperature detecting means (26) from the first detected temperature (Tco) determined based on the detected value of the first temperature detecting means (25, 27). When the subtraction value (Tco−Tsc) obtained by subtracting (Tsc) is equal to or less than a predetermined determination value (KT), the refrigerant amount charged in the refrigeration cycle apparatus (10) is insufficient. A refrigerant shortage detection device comprising: a refrigerant shortage determination means (S7) for determination. The first temperature detecting means is a condensing refrigerant temperature sensor (25) for detecting the temperature of the refrigerant radiated by the heat exchanger for condensation (12a),
2. The refrigerant according to claim 1, wherein the second temperature detection means is a supercooling refrigerant temperature sensor (26) that detects the temperature of the refrigerant that has radiated heat in the supercooling heat exchange section (12 c). Insufficient detection device. The first temperature detection means is a supercooling refrigerant pressure sensor (27) for detecting the pressure of the refrigerant radiated by the supercooling heat exchange section (12c),
2. The refrigerant according to claim 1, wherein the second temperature detection means is a supercooling refrigerant temperature sensor (26) that detects the temperature of the refrigerant that has radiated heat in the supercooling heat exchange section (12 c). Insufficient detection device.   The supercooled refrigerant pressure sensor (27) is provided in a refrigerant flow path from the radiator (12) to a decompression means (13) for decompressing and expanding the refrigerant flowing out of the radiator (12). The refrigerant shortage detection device according to claim 3.   The supercooling refrigerant temperature sensor (26) is provided in a refrigerant flow path from the radiator (12) to a decompression means (13) for decompressing and expanding the refrigerant flowing out of the radiator (12). The refrigerant shortage detection device according to any one of claims 2 to 4.   The refrigerant shortage detection device according to any one of claims 1 to 5, wherein the determination value (KT) is 3 ° C.   7. The compressor according to claim 1, wherein the compressor is a variable capacity compressor (11) that is driven by a driving force transmitted from a driving source and is always connected to the driving source. The refrigerant shortage detection device according to any one of the above.

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