Vehicle air conditioning

Abstract

A vehicle air conditioning system (1), comprising: a compressor (2) for compressing a refrigerant, an airflow channel (3) through which air to be supplied to the vehicle interior flows, a radiator (4) arranged in this airflow duct (3) to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger (7) arranged outside the vehicle interior to allow the refrigerant to absorb heat, a detection means (44) for detecting an intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and a tax resource (32), so that the control medium (32) causes the refrigerant released by the compressor (2) to radiate heat into the radiator (4), and decompresses the refrigerant from which the heat was radiated in order to allow the refrigerant in the external heat exchanger (7) to absorb heat, thereby heating the vehicle interior; wherein the control means (32) has a vacuum protection function for setting a speed of the compressor (2) so that a detected value does not fall below a limit setpoint, based on the detected value of the detection means (44) and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor (2), the control means (32) has a predetermined lower limit and a predetermined upper limit which is higher than the predetermined lower limit, and sets the speed of the compressor (2) by setting the limit setpoint as the upper limit when starting up the compressor (2), and the taxable amount (32) gradually reduces the limiting target value towards the lower limit as the recorded value falls towards the upper limit.

Description

Technical field

[0001] The present invention relates to an air conditioning system of a heat pump system that conditions air in a vehicle interior, and in particular relates to an air conditioning system for a vehicle that is suitable for a hybrid car or an electric vehicle. State of the art

[0002] Due to a resurgence of environmental concerns in recent years, hybrid and electric vehicles have become more widespread. Furthermore, an air conditioning system applicable to such a vehicle has been developed, comprising a compressor for compressing and releasing a refrigerant, a radiator (condenser) located on the interior side of the vehicle to allow the refrigerant to radiate heat, a heat absorber (evaporator) located on the interior side of the vehicle to allow the refrigerant to absorb heat, and an external heat exchanger located outside the vehicle interior to allow the refrigerant to radiate or absorb heat. It is provided that respective operating modes of a heating function are available to allow the refrigerant released by the compressor to radiate heat in the radiator and to allow the refrigerant from which the heat was radiated in this radiator to...to allow the refrigerant released by the compressor to absorb heat in the external heat exchanger, to perform a dehumidification and heating operation in order to allow the refrigerant released by the compressor to radiate heat in the radiator and to allow the refrigerant from which the heat was radiated in the radiator to absorb heat in the heat absorber, and a cooling operation in order to allow the refrigerant released by the compressor to radiate heat in the external heat exchanger and to allow the refrigerant in the heat absorber to absorb heat, are changed and carried out (see, for example, patent specification 1).

[0003] DE 199 35 731 A1 (Patent 2) describes a method for operating a subcritical or transcritical vehicle refrigeration system, in which a supercritical pressure relative to the critical pressure of a refrigerant circulating in the circuit is generated on the high-pressure side of a vapor compression circuit comprising a compressor, a gas cooler, an expansion valve and an evaporator connected in series and forming an integral closed circuit, in order to provide cooling capacity, and simultaneously a subcritical pressure is achieved on the low-pressure side of the circuit, wherein heat energy is supplied to the refrigerant cooled on the low-pressure side via the evaporator, wherein the refrigerant mass flow is regulated by the compressor and the desired high pressure is set by means of an expansion valve.

[0004] DE 102 18 504 A1 (Patent 3) relates to a vehicle air conditioning system with a control unit that includes a detection device for determining the initial start of a compressor for compressing refrigerant in a refrigeration circuit after the compressor has been installed in a vehicle. The control unit regulates the operation of the compressor such that the compressor is operated for a predetermined period at a speed equal to or less than a predetermined speed when the detection device determines the initial start of the compressor.

[0005] Patent specification DE 10 2012 215 622 A1 (4) relates to a refrigerant circuit device comprising a compressor, a user-side heat exchanger that heats a heat exchange fluid by carrying out heat exchange between the heat exchange fluid and the high-pressure refrigerant flowing from the compressor, an intermediate pressure passage through which gaseous intermediate pressure refrigerant, obtained by the decompression of the high-pressure refrigerant flowing from the user-side heat exchanger, is introduced into the intermediate pressure channel of the compressor, an external heat exchanger that evaporates low-pressure refrigerant, obtained by the decompression of high-pressure refrigerant flowing from the user-side heat exchanger, and causes the evaporated refrigerant to flow towards an intake channel of the compressor, and an auxiliary heater that heats the heat exchange fluid before or at the same time.to which the heat exchanger on the user side heats the heat exchange fluid.

[0006] DE 11 2008 001 492 T5 (patent 5) relates to a starting control device for an electric scroll compressor, which includes a motor and a scroll compression unit driven by the motor and used to compress a refrigerant, wherein the starting control device has a detector for detecting a temperature and pressure of a refrigerant present in the compression unit before the compression unit is started and for outputting a detection result, and a control unit for controlling the driving of the motor when the compressor is started.

[0007] JP H08-282 253 A (Patent 6) relates to the detection of an outside air temperature at the time of the start of a heating operation, and in the case where it is lower than a specified temperature, a start rotation frequency and a continuity time are determined based on the outside air temperature. A compressor is started under these start conditions.

[0008] JP 2014-172 478 A (Patent 7) relates to a cooling circuit device configured to further suppress overshoot and oscillation.

[0009] US Patent 4,724,680 A (Patent 8) relates to an air conditioning system comprising a variable frequency power source device for providing an alternating current of variable frequency, a variable capacity compressor driven by the alternating current, and a start detector for detecting a start state of the compressor a predetermined time after the compressor is energized. Citation list of patent specifications Patent specification 1: Japanese patent no. 3985384 Patent specification 2: German patent application disclosure no. 199 35 731 Patent specification 3: German patent application disclosure no. 102 18 504 Patent specification 4: German patent application disclosure no. 10 2012 215 622 Patent specification 5: German patent application disclosure no. 11 2008 001 492 Patent specification 6: Japanese patent application disclosure with the number H08-282253 Patent specification 7: Japanese patent application disclosure no. 2014-172478 Patent specification 8: US patent no. 4,724,680 Summary of the invention Problems to be solved by the invention

[0010] In a vehicle air conditioning system like the one described above, if the low pressure of a refrigerant circuit drops excessively, a problem arises: the compressor or any low-pressure-side component of the refrigerant circuit can be damaged. This is particularly true when the compressor is started in heating mode, which is typically used during a season with decreasing outside air temperatures. The compressor speed increases rapidly, causing the low pressure to drop quickly. To address this problem, this type of vehicle air conditioning system has traditionally implemented a low-pressure protection feature. This feature regulates the compressor speed to prevent the intake refrigerant temperature from falling below a predetermined limit, based on the compressor's intake refrigerant temperature (which is converted into an intake refrigerant pressure for evaluation).

[0011] Fig. Figure 10 is a diagram illustrating such a conventional underpressure protection control. In this diagram, the lower limit intake temperature (TLL) is the intake refrigerant temperature corresponding to a compressor intake pressure (the intake refrigerant pressure) of, for example, 0.01 MPaG, and is set to a value that takes into account the service life of the compressor or the low-pressure-side component. Furthermore, the protection stop value (TLS) is an intake refrigerant temperature at which the compressor will stop, and this protection stop value (TLS) is set to a value (TLS = TLL + 2 degrees) that is, for example, a margin of 2 degrees higher than the lower limit intake temperature (TLL), taking into account the accuracy of an intake temperature sensor that measures the compressor's intake refrigerant temperature.

[0012] Furthermore, a limit setpoint TGTs is a target value for the intake refrigerant temperature that limits the compressor speed. This value (fixed at TGTs = TLS + 3 degrees) is set to a value that is, for example, 3 degrees above the protective stop value TLS, taking into account override and response delay of the intake temperature sensor. A control unit of the vehicle's air conditioning system then adjusts the compressor speed to prevent the intake refrigerant temperature from falling below the limit setpoint TGTs, based on the intake refrigerant temperature detected by the intake temperature sensor. Specifically, if the intake refrigerant temperature is expected to fall below the limit setpoint TGTs, the control unit reduces the compressor speed and adjusts it until the intake refrigerant temperature reaches the limit setpoint TGTs.This protects the compressor and the low-pressure side components, while at the same time preventing the compressor from coming to a standstill as much as possible.

[0013] However, if the intake refrigerant pressure (the low pressure) drops rapidly during compressor start-up or similar situations, the intake temperature sensor cannot detect this drop. If this reaction delay increases, the compressor speed cannot be adjusted in time. Furthermore, if the compressor speed is adjusted solely based on the predetermined limit setpoint TGTs, as in conventional technology, the actual intake refrigerant temperature (the intake refrigerant pressure) drops significantly below the limit setpoint TGTs and falls beyond the protection stop value TLS to the lower limit intake temperature TLL (overshoot). Consequently, in conventional technology, the compressor operates at such a low pressure that damage to the compressor and the low-pressure-side components occurs.

[0014] The present invention was developed to solve such conventional technical problems, and one of its aims is to create an air conditioning system for a vehicle in which the negative pressure protection is implemented precisely to improve reliability. Means to solve the problems

[0015] A vehicle air conditioning system according to claim 1 comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing means for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control means such that this control means causes the refrigerant discharged by the compressor to radiate heat in the radiator and decompresses the refrigerant from which the heat was radiated in order to allow the refrigerant to absorb heat in the external heat exchanger, thereby heating the vehicle interior, and the vehicle air conditioning system is characterized in thatthat the control device has a vacuum protection function for adjusting the compressor speed so that a detected value does not fall below a limit setpoint, based on the detected value of the detection device and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor, and that the control device has a predetermined lower limit and a predetermined upper limit, which is higher than the predetermined lower limit, and adjusts the compressor speed by setting the limit setpoint as the upper limit when the compressor is started, and that the control device gradually reduces the limit setpoint towards the lower limit as the detected value falls to the upper limit.

[0016] The vehicle air conditioning system of the invention of claim 2 is characterized in that the control means in the above invention reduces the limit setpoint to the lower limit limit with a predetermined time constant of a first-order delay when the detected value drops to the upper limit limit.

[0017] The vehicle air conditioning system of the invention of claim 3 includes an auxiliary heating medium arranged on an upstream side of the radiator to the flow of air in the airflow channel in the above-mentioned invention, and is characterized in that the control means causes the auxiliary heating medium to generate heat when the compressor is started up.

[0018] The vehicle air conditioning system of the invention of claim 4 is characterized in that the control means in the above-mentioned inventions has speed limiting data which show a ratio between an outside air temperature and an upper limit speed of the compressor at which the intake refrigerant temperature or the intake refrigerant pressure does not fall below the lower limit at the outside air temperature, and the control means changes the upper limit speed of the compressor on the basis of the outside air temperature as a function of these speed limiting data.

[0019] The vehicle air conditioning system of the invention of claim 5 is characterized in that the control means in the inventions of claims 1 to 3 reduces an upper limit speed of the compressor for a predetermined time after the compressor has been started up or when high pressure is low.

[0020] A vehicle air conditioning system according to claim 6 comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an auxiliary heating element arranged on an upstream side of the radiator with respect to the airflow in the airflow duct, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing element for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control element such that this control element causes the refrigerant discharged by the compressor to radiate heat into the radiator and decompresses the refrigerant from which the heat has been radiated.to allow the refrigerant in the external heat exchanger to absorb heat, thereby heating the vehicle interior, and the vehicle air conditioning system is characterized in that the control medium has a vacuum protection function for adjusting the speed of the compressor so that a detected value does not fall below a limit setpoint, based on the detected value of the detection medium and the limit setpoint set to the intake refrigerant temperature or the intake refrigerant pressure of the compressor, and the control medium allows the auxiliary heating medium to generate heat when the compressor is started.

[0021] A vehicle air conditioning system according to claim 7 comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing means for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control means such that this control means causes the refrigerant discharged by the compressor to radiate heat in the radiator and decompresses the refrigerant from which the heat was radiated to allow the refrigerant to absorb heat in the external heat exchanger, thereby heating the vehicle, and the vehicle air conditioning system is characterized in thatthat the control device has a vacuum protection function for adjusting the compressor speed so that a detected value does not fall below a limit setpoint, based on the detected value of the detection device and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor, and that the control device has speed limit data that show a ratio between an outside air temperature and an upper limit speed of the compressor at which the intake refrigerant temperature or intake refrigerant pressure at the outside air temperature does not fall below the limit setpoint, and changes the upper limit speed of the compressor based on the outside air temperature depending on these speed limit data.

[0022] A vehicle air conditioning system according to claim 8 comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing means for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control means such that this control means causes the refrigerant discharged by the compressor to radiate heat in the radiator and decompresses the refrigerant from which the heat was radiated to allow the refrigerant to absorb heat in the external heat exchanger, thereby heating the vehicle, and the vehicle air conditioning system is characterized in thatthat the control device has a vacuum protection function for adjusting the compressor speed so that a detected value does not fall below a limit setpoint, based on the detected value of the detection device and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor, and the control device reduces an upper limit speed of the compressor for a predetermined time after the compressor has been started or when a high pressure is low. Advantageous effect of the invention

[0023] According to the invention of claim 1, a vehicle air conditioning system comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing means for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control means such that this control means causes the refrigerant discharged by the compressor to radiate heat in the radiator and decompresses the refrigerant from which the heat was radiated in order to allow the refrigerant to absorb heat in the external heat exchanger, thereby heating the vehicle interior.and the control device in the vehicle air conditioning system has a vacuum protection function for adjusting the compressor speed so that a detected value does not fall below a limit setpoint, based on the detected value of the detection device and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor, and the control device has a predetermined lower limit and a predetermined upper limit that is higher than the predetermined lower limit, and adjusts the compressor speed by setting the limit setpoint as the upper limit when the compressor is started, and the control device gradually reduces the limit setpoint towards the lower limit.when the measured value drops to the upper limit. By setting the lower limit to the aforementioned conventional limit setpoint, the control unit adjusts the compressor speed accordingly by setting the limit setpoint to the upper limit, which is higher than the lower limit when the compressor is started.

[0024] Consequently, underpressure protection begins earlier than in conventional technology, effectively preventing overshoot of the actual intake refrigerant temperature or pressure due to a delayed response from the sensing agent. This improves the reliability of the compressor and low-pressure components. Furthermore, as the sensing agent falls towards the upper limit, the control agent gradually reduces the setpoint towards the lower limit. This enables precise underpressure protection without unnecessarily restricting the compressor speed.

[0025] In this case, as in the invention of claim 2, the control device reduces the limit setpoint to the lower limit limit with a predetermined time constant of a first-order delay when the detected value falls to the upper limit limit. Consequently, it is possible to precisely reduce the limit setpoint as a function of the decrease in the actual intake refrigerant temperature or the intake refrigerant pressure.

[0026] Furthermore, as in the invention of claim 3, if an auxiliary heating medium is arranged on an upstream side of the radiator with respect to the airflow into the airflow duct, the control means causes the auxiliary heating medium to generate heat during compressor start-up, thereby increasing both the high and low pressure. Additionally, the compressor speed does not increase, thus preventing a rapid drop in the intake refrigerant temperature or pressure during compressor start-up and further improving reliability.

[0027] Furthermore, as in claim 4 of the invention, the control device comprises speed limiting data that define a relationship between an ambient air temperature and an upper limit speed of the compressor at which the intake refrigerant temperature or intake refrigerant pressure does not fall below the lower limit at the ambient air temperature, and the control device modifies the upper limit speed of the compressor based on the ambient air temperature as a function of the speed limiting data. Consequently, it is possible to change the upper limit speed of the compressor as a function of the ambient air temperature and to reliably prevent the intake refrigerant temperature or intake refrigerant pressure from falling below the lower limit.

[0028] On the other hand, as in the invention of claim 5, the control means reduces an upper limit speed of the compressor for a predetermined time after the compressor is started up or when the high pressure is low. Consequently, it is possible to suppress the disadvantage of the compressor speed increasing too sharply and the intake refrigerant temperature or pressure rapidly dropping below the lower limit during start-up or when the high pressure is low.

[0029] According to the invention of claim 6, a vehicle air conditioning system comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an auxiliary heating element arranged on an upstream side of the radiator with respect to the airflow in the airflow duct, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing element for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control element such that this control element causes the refrigerant discharged by the compressor to radiate heat into the radiator and decompresses the refrigerant from which the heat has been radiated.To allow the refrigerant in the external heat exchanger to absorb heat, thus heating the vehicle interior, the vehicle air conditioning system incorporates a vacuum protection function to adjust the compressor speed so that a measured value does not fall below a setpoint. This setpoint is based on the measured value of the sensor and the setpoint for the compressor's intake refrigerant temperature or pressure. The control system also allows the auxiliary heating element to generate heat when the compressor starts. As a result of the auxiliary heating element heating, both the high and low pressures increase. Furthermore, the compressor speed does not increase, thus preventing a rapid drop in the intake refrigerant temperature or pressure when the compressor starts.and an improvement in reliability can be achieved.

[0030] According to the invention of claim 7, a vehicle air conditioning system comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing means for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control means such that this control means causes the refrigerant discharged by the compressor to radiate heat in the radiator and decompresses the refrigerant from which the heat was radiated to allow the refrigerant to absorb heat in the external heat exchanger, thereby heating the vehicle interior.In the vehicle air conditioning system, the control unit has a vacuum protection function for adjusting the compressor speed so that a detected value does not fall below a setpoint. This setpoint is based on the detected value and the intake refrigerant temperature or pressure of the compressor. The control unit also has speed limit data that defines the relationship between an ambient air temperature and an upper compressor speed at which the intake refrigerant temperature or pressure does not fall below the setpoint. The upper compressor speed is adjusted based on the ambient air temperature according to this speed limit data. Consequently, it is possible to change the upper compressor speed depending on the ambient air temperature.and the intake refrigerant temperature or intake refrigerant pressure is prevented from falling below the limit setpoint, thus improving reliability.

[0031] According to the invention of claim 8, a vehicle air conditioning system comprises a compressor for compressing a refrigerant, an airflow duct through which air to be supplied to a vehicle interior flows, a radiator arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger arranged outside the vehicle interior to allow the refrigerant to absorb heat, a sensing means for sensing an intake refrigerant temperature or intake refrigerant pressure of the compressor, and a control means such that this control means causes the refrigerant discharged by the compressor to radiate heat in the radiator and decompresses the refrigerant from which the heat was radiated to allow the refrigerant to absorb heat in the external heat exchanger, thereby heating the vehicle interior.In the vehicle air conditioning system, the control unit incorporates a vacuum protection function to adjust the compressor speed, preventing a measured value from falling below a setpoint. This setpoint is based on the measured value and the intake refrigerant temperature or pressure of the compressor. Furthermore, the control unit reduces the compressor speed to a predetermined maximum for a specified period after compressor start-up or when high pressure is low. Consequently, the disadvantage of excessive compressor speed increases and rapid drops in intake refrigerant temperature or pressure below the setpoint during start-up or low high pressure is eliminated, resulting in improved reliability. Brief description of the characters Fig. Figure 1 is a constitutional view of a vehicle air conditioning system of an embodiment to which the present invention is applied; Fig. 2 is a block diagram of an electrical circuit of a control unit for the vehicle's air conditioning system. Fig. 1; Fig. 3 is a control block diagram of a compressor speed control by the control unit of Fig. 2 in a heating operation; Fig. 4 is a diagram illustrating a vacuum protection control system operated by the control unit of Fig. 2 is to be executed (execution form 1); Fig. 5 is a time-based graph to illustrate the negative pressure protection control of Fig. 4; Fig. Figure 6 is a constitutional view of a vehicle air conditioning system of another embodiment to which the present invention is applied (embodiment 2); Fig. Figure 7 is a timing diagram to illustrate a low-pressure protection control system operated by a control unit in the vehicle's air conditioning system. Fig. 6 is executed; Fig. Figure 8 is a diagram illustrating another example of the vacuum protection control provided by the control unit of Fig. 2 is to be executed (execution form 4); Fig. Figure 9 is a constitutional view of a vehicle air conditioning system with yet another embodiment to which the present invention is applied (embodiment 5); and Fig. Figure 10 is a diagram illustrating a conventional negative pressure protection control system. Method for carrying out the invention

[0032] Embodiments of the present invention are described in detail below with reference to the figures. Design 1

[0033] Fig. Figure 1 shows a structural view of a vehicle air conditioning system 1 of an embodiment of the present invention. The vehicle of the embodiment to which the present invention is applied is an electric vehicle (EV) in which no engine (an internal combustion engine) is installed, and which is driven by an electric motor, for the embodiment, which is powered by energy stored in a battery (which is not shown in the figure), and the vehicle air conditioning system 1 of the present invention is also powered by battery energy. In particular, in the electric vehicle, which is not capable of generating heat from engine waste heat, the vehicle air conditioning system 1 of the embodiment performs heating by means of a heat pump process, employing a refrigerant circuit, and furthermore, the air conditioning system selectively performs respective operating modes of dehumidifying and heating, dehumidifying and cooling, cooling, and other functions.

[0034] It should be noted that the vehicle is not limited to electric vehicles, and the present invention is also effective for a so-called hybrid car, in which the internal combustion engine is used together with the electric motor. Furthermore, the present invention is of course also applicable to a conventional car powered by an internal combustion engine.

[0035] The vehicle air conditioning system 1 of the embodiment performs air conditioning (heating, cooling, dehumidifying and ventilating) of a vehicle interior of the electric vehicle, and a refrigerant line 13 successively connects an electric compressor 2 for compressing a refrigerant, a radiator 4 arranged in an airflow duct 3 of an HVAC unit 10, through and in which the vehicle interior air flows and circulates to allow the high-temperature, high-pressure refrigerant, which has been discharged by the compressor 2 and flows in through a refrigerant line 13G, to radiate heat in the vehicle interior, an external expansion valve 6, which consists of an electric valve that decompresses and expands the refrigerant during heating, an external heat exchanger 7, which performs the heat exchange between the refrigerant and the outside air to act as a radiator during cooling and as an evaporator during heating, and an internal expansion valve 8.which consists of an electric valve for decompressing and expanding the refrigerant, a heat absorber 9 arranged in the airflow duct 3 so that the refrigerant can absorb heat during cooling and dehumidification from the inside and outside of the vehicle, an evaporation control valve 11 to control evaporation capacity in the heat absorber 9, a storage unit 12 and other connected components, forming a refrigerant circuit R.

[0036] It should be noted that an external fan 15 is provided in the external heat exchanger 7. The external fan 15 forces the outside air through the external heat exchanger 7 to carry out the heat exchange between the outside air and the refrigerant, whereby the outside air also flows through the external heat exchanger 7 when the vehicle is stationary (i.e., a speed VSP of 0 km / h).

[0037] Furthermore, the external heat exchanger 7 has a receiver-drier section 14 and a subcooling section 16 sequentially on a refrigerant flow downstream side. A refrigerant line 13A extending from the external heat exchanger 7 to the outside is connected to the receiver-drier section 14 by means of a solenoid valve 17, which acts as an open / close valve for cooling and is to be opened during cooling. An outlet port of the subcooling section 16 is connected to the internal expansion valve 8 by means of a check valve 18. It should be noted that the receiver-drier section 14 and the subcooling section 16 structurally form part of the external heat exchanger 7, and one side of the internal expansion valve 8 and the check valve 18 are forward-directed.

[0038] Furthermore, a refrigerant line 13B is arranged between the check valve 18 and the internal expansion valve 8, in a heat exchange relationship with a refrigerant line 13C extending from the evaporation control valve 11, located on the outlet side of the heat absorber 9, and both lines form an internal heat exchanger 19. As a result, the refrigerant flowing into the internal expansion valve 8 via refrigerant line 13B is cooled (subcooled) by the refrigerant flowing out of the heat absorber 9 via the evaporation control valve 11. It should be noted that the evaporation control valve 11 can be located on the downstream side of the internal heat exchanger 19.

[0039] Additionally, refrigerant line 13A, extending from the external heat exchanger 7 to the outside, branches off. This branching refrigerant line 13D communicates with and connects to refrigerant line 13C on a downstream side of the internal heat exchanger 19 via a solenoid valve 21, acting as a normally open / closed heating valve that is to be opened during heating. Furthermore, refrigerant line 13E branches off on an outlet side of the radiator 4 upstream of the external expansion valve 6. This branching refrigerant line 13F communicates with and connects to refrigerant line 13B on a downstream side of the check valve 18 via a solenoid valve 22, acting as a normally open / closed dehumidification valve that is to be opened during dehumidification. That is, solenoid valve 22 is connected in parallel to the external heat exchanger 7.

[0040] Furthermore, the external expansion valve 6 is connected in parallel to a branch line 13J, and a solenoid valve 20 is interposed in the branch line 13J as a diverting valve. This valve is designed to be open during cooling operation, allowing the refrigerant to bypass the external expansion valve 6. Note that the line between the external expansion valve 6 and the solenoid valve 20, as well as the external heat exchanger 7, is designated 13I.

[0041] Additionally, in the airflow channel 3 on an upstream side of the heat absorber 9, there are corresponding intake connections such as an outside air intake connection and an inside air intake connection (represented by an intake connection 25 in Fig. 1) is designed, and an intake changeover flap 26 is arranged in the intake port 25 to change the air supplied to the airflow duct 3 into interior air, which is the air of the vehicle interior (an interior air recirculation mode), and into outside air, which is the air outside the vehicle interior (an outside air supply mode). Furthermore, an internal fan (a blower fan) 27 is arranged on a downstream airflow side of the intake changeover flap 26 to make the supplied interior air or outside air available to the airflow duct 3.

[0042] Furthermore, an air mixing flap 28 is arranged in the airflow channel 3 on the upstream side of the radiator 4 to adjust the degree at which the indoor or outdoor air flows through the radiator 4. Further along in the airflow channel 3 on the downstream side of the radiator 4, each outlet opening (represented by an outlet opening 29 in Fig. 1) of the foot, the vent or the defroster, and in the outlet opening 29 an outlet changeover flap 31 is arranged to carry out a changeover control of the blowing of air from each of the above-mentioned outlet openings.

[0043] Next up is 32 in Fig. 2 a control unit (ECU) such as a control device consisting of a microcomputer, and an input of the control unit 32 is connected to the corresponding outputs of an outside air temperature sensor 33 for detecting an outside air temperature Tam of the vehicle, an outside air humidity sensor 34 for detecting an outside air humidity of the vehicle, an HVAC intake temperature sensor 36 for detecting a temperature of the air to be drawn in from the intake port 25 to the airflow duct 3, an interior air temperature sensor 37 for detecting a temperature of the air in the vehicle interior (the interior air), an interior air humidity sensor 38 for detecting a humidity of the air in the vehicle interior, an interior air CO2 concentration sensor 39 for detecting a carbon dioxide concentration in the vehicle interior, an outlet temperature sensor 41 for detecting a temperature of the air to be blown out from the outlet opening 29 to the vehicle interior,an outlet pressure sensor 42 for detecting a pressure (an outlet pressure Pd) of the refrigerant discharged by compressor 2, an outlet temperature sensor 43 for detecting a temperature of the refrigerant discharged by compressor 2, an intake temperature sensor 44 (a detection means) for detecting a temperature (an intake refrigerant temperature Ts: a detected value) of the refrigerant to be drawn into compressor 2, a radiator temperature sensor 46 for detecting a temperature of radiator 4 (a radiator temperature TCI), a radiator pressure sensor 47 for detecting a refrigerant pressure of radiator 4 (a radiator pressure PCI), a heat absorber temperature sensor 48 for detecting a temperature of heat absorber 9 (a heat absorber temperature Te), a heat absorber pressure sensor 49 for detecting a refrigerant pressure of heat absorber 9, a Sunlight sensor 51 from, e.g.,connected to a photosensor system for detecting the amount of solar radiation in the vehicle, a speed sensor 52 for detecting the vehicle's speed, an air conditioning control unit 53 for setting a change to a predetermined temperature or operating modes, an external heat exchanger temperature sensor 54 for detecting the temperature (TXO) of the external heat exchanger 7, and an external heat exchanger pressure sensor 56 for detecting the refrigerant pressure of the external heat exchanger 7.

[0044] On the other hand, an output of the control unit 32 is connected to the compressor 2, the external fan 15, the internal fan (the blower fan) 27, the intake changeover flap 26, the air mixing flap 28, the outlet changeover flap 31, the external expansion valve 6, the internal expansion valve 8, the respective solenoid valves 22, 17, 21 and 20, and the evaporation capacity control valve 11. The control unit 32 then controls this component based on the outputs of the respective sensors and the setting input from the air conditioning control section 53.

[0045] Next, a process of the vehicle air conditioning system 1 of the embodiment with the above configuration is described. The control unit 32 switches between and executes the respective operating modes, broadly categorized as heating, dehumidifying and heating, internal recirculation, dehumidifying and cooling, and cooling. First, the refrigerant flow rate in each operating mode is described. (1) Heating operation

[0046] When heating mode is selected by the control unit 32 or by manual operation on the air conditioning operating section 53, the control unit 32 opens solenoid valve 21 and closes solenoid valves 17, 22, and 20. The control unit then actuates compressor 2 and the respective fans 15 and 27, and the air mixing flap 28 is in a position where it directs the air blown out by the internal fan 27 through radiator 4. Consequently, high-temperature, high-pressure refrigerant gas discharged by compressor 2 flows into radiator 4. The air in airflow duct 3 flows through radiator 4 and is thus heated by the high-temperature refrigerant in radiator 4. Conversely, heat is drawn from the air in the refrigerant in radiator 4, causing it to cool and condense.

[0047] The refrigerant, liquefied in radiator 4, flows out of radiator 4 and then through refrigerant line 13E to the external expansion valve 6. The refrigerant flowing into the external expansion valve 6 is decompressed there and then flows into the external heat exchanger 7. The refrigerant flowing into the external heat exchanger 7 evaporates, and the heat is drawn upwards by the outside air, which is guided through the duct or the external fan 15. In other words, the refrigerant circuit R acts as a heat pump, and the external heat exchanger 7 acts as the evaporator of the refrigerant.The low-temperature refrigerant exiting the external heat exchanger 7 then flows through refrigerant line 13A, solenoid valve 21, and refrigerant line 13D, and from refrigerant line 13C into the reservoir 12 to perform gas-liquid separation. The gaseous refrigerant is then drawn into the compressor 2, and this circulation is repeated. The air heated in the radiator 4 is blown out through the outlet 29, thus heating the vehicle interior.

[0048] The control unit 32 controls a speed Nc of the compressor 2 based on a high pressure of the refrigerant circuit R, which is detected by the radiator pressure sensor 47, controls a valve position of the external expansion valve 6 based on the temperature (the radiator temperature TCI) of the radiator 4, which is detected by the radiator temperature sensor 46, and the refrigerant pressure (the radiator pressure PCI) of the radiator 4, which is detected by the radiator pressure sensor 47, and controls a degree of subcooling of the refrigerant in an outlet opening of the radiator 4.

[0049] Fig. Figure 3 is a control block diagram of the control unit 32, which determines a setpoint speed (a compressor setpoint speed) TGNC of the compressor 2 for this heating operation. A feedforward control amount calculation section 58 of the control unit 32 calculates an F / F control amount TGNCff of the compressor setpoint speed based on the outside air temperature Tam, obtainable from the outside air temperature sensor 33, a fan voltage BLV of the internal fan 27, an air mixing flap position SW of the air mixing flap 28, obtainable from SW = (TAO - Te) / (TH - Te), a setpoint subcooling degree TGSC, which is a setpoint of a subcooling degree SC in the outlet of the radiator 4, a radiator setpoint temperature TCO, which is a setpoint of the temperature of the radiator 4, and a radiator setpoint pressure PCO, which is a setpoint of the pressure of the radiator 4.

[0050] It should be noted that TAO is a setpoint outlet temperature, which is a setpoint for the temperature of the air blown out of outlet 29; TH is the temperature of radiator 4 (a radiator temperature), obtainable from radiator temperature sensor 46; TE is the temperature of heat absorber 9 (the heat absorber temperature), obtainable from heat absorber temperature sensor 48; and the air mixing flap position SW changes in a range of 0 ≤ SW ≤ 1. When the position is set to 0, the air mixing flap is in a closed air mixing state, in which the flap does not allow air to pass through radiator 4; and when the position is set to 1, the air mixing flap is in a fully open air mixing state, in which all the air in the airflow duct 3 passes through radiator 4.

[0051] The radiator setpoint pressure PCO is calculated based on the setpoint subcooling level TGSC and the radiator setpoint temperature TCO. Furthermore, a feedback control calculation section 60 calculates an F / B control amount TGNCfb of the compressor setpoint speed based on the radiator setpoint pressure PCO and the radiator pressure PCI, which is the refrigerant pressure of the radiator 4. Then, an adder 61 adds the F / F control amount TGNCff, calculated by the F / F control calculation section 58, and the F / B control amount TGNCfb, calculated by the F / B control calculation section 60. This added value (TGNCff + TGNCfb) is limited by a low-pressure protection control section 62 (a low-pressure control function of the control device 32) and is then determined as the compressor setpoint speed TGNC. In this heating mode, the control unit 32 controls the speed Nc of the compressor 2 based on the compressor setpoint speed TGNC.It should be noted that the description for the limit control of the compressor setpoint speed TGNC for a low temperature protection to be carried out by the vacuum protection control section 62 will follow in detail later. (2) Dehumidification and heating operation

[0052] Next, in dehumidifying and heating mode, the control unit 32 opens the solenoid valve 22 in the heating mode described above. Consequently, a portion of the condensed refrigerant flowing through the radiator 4 and the refrigerant line 13E is distributed and flows through the solenoid valve 22 to the internal heat exchanger 19 via the refrigerant lines 13F and 13B, and thus to the internal expansion valve 8. The refrigerant is decompressed in the internal expansion valve 8 and then flows into the heat absorber 9 to evaporate. At this point, water in the air blown out by the internal fan 27 coagulates and adheres to the heat absorber 9 through heat absorption, thereby cooling and dehumidifying the air.

[0053] The refrigerant evaporated in the heat absorber 9 flows through the evaporation control valve 11 and the internal heat exchanger 19 to connect the refrigerant from refrigerant line 13D to refrigerant line 13C, and then flows through the reservoir 12 to be drawn into the compressor 2, with this circulation being repeated. The air dehumidified in the heat absorber 9 is reheated as it flows through the radiator 4, thus dehumidifying and heating the vehicle interior. The control unit 32 regulates the speed Nc of the compressor 2 based on the high pressure R of the refrigerant circuit, which is detected by the radiator pressure sensor 47, and the control unit regulates the valve position of the external expansion valve 6 based on the temperature of the heat absorber 9, which is detected by the heat absorber temperature sensor 48. (3) Internal circulation operation

[0054] Next, in internal recirculation mode, the control unit 32 switches off the external expansion valve 6 in the above dehumidifying and heating mode (a shutdown position) and also closes the solenoid valves 20 and 21. With the external expansion valve 6 and the solenoid valves 20 and 21 closed, the refrigerant flow into and out of the external heat exchanger 7 is restricted. Consequently, all the condensed refrigerant flowing through the radiator 4 and the refrigerant line 13I flows through the solenoid valve 22 to the refrigerant line 13F. The refrigerant flowing through the refrigerant line 13F then flows from the refrigerant line 13B through the internal heat exchanger 19 to the internal expansion valve 8. The refrigerant is decompressed in the internal expansion valve 8 and then flows into the heat absorber 9 to evaporate.The water in the air blown out by the internal fan 27 coagulates at this point and adheres to the heat absorber 9 through the heat absorption process, thus cooling and dehumidifying the air.

[0055] The refrigerant evaporated in the heat absorber 9 flows through the evaporation control valve 11, the internal heat exchanger 19, the refrigerant line 13C, and the reservoir 12 to be drawn into the compressor 2, with this circulation being repeated. The air dehumidified in the heat absorber 9 is reheated as it flows through the radiator 4, thus dehumidifying and heating the vehicle interior. However, in this internal circulation process, the refrigerant circulates between the radiator 4 (heat radiation) and the heat absorber 9 (heat absorption), which are located in the airflow duct 3 on one side of the interior. Therefore, heat is not drawn up from the outside air, but the refrigerant's heat capacity is utilized to offset the energy consumed by the compressor 2.The entire amount of refrigerant flows through the heat absorber 9, which performs a dehumidification process, and thus the dehumidification capacity is higher compared to the dehumidification and heating operation above, but the heating capacity decreases.

[0056] The control unit 32 controls the speed Nc of the compressor 2 based on the temperature of the heat absorber 9 or the aforementioned high pressure of the refrigerant circuit R. At this point, the control unit 32 selects a lower compressor setpoint speed from among the compressor setpoint speeds, obtainable from calculations of the temperature of the heat absorber 9 and the high pressure, in order to control the compressor 2. (4) Dehumidification and cooling operation

[0057] Next, in dehumidifying and cooling mode, the control unit 32 opens solenoid valve 17 and closes solenoid valves 21, 22, and 23. The control unit then actuates compressor 2 and the respective fans 15 and 27, and the air mixing flap 28 is in the position where it directs the air blown out by the internal fan 27 through radiator 4. Consequently, the high-temperature, high-pressure refrigerant gas discharged by compressor 2 flows into radiator 4. Air flows through radiator 4 via airflow duct 3, and thus the air in airflow duct 3 is heated by the high-temperature refrigerant in radiator 4, while heat is extracted from the air by the refrigerant in radiator 4, cooling the refrigerant to condense and liquefy.

[0058] The refrigerant flowing from the radiator passes through refrigerant line 13E to the external expansion valve 6, and then through the valve, which is controlled to be slightly open, to flow into the external heat exchanger 7. The refrigerant flowing into the external heat exchanger 7 is cooled by passing through it or by the outside air drawn in by the external fan 15, causing it to condense. The refrigerant flowing out of the external heat exchanger 7 passes through refrigerant line 13A and then through solenoid valve 17 into the receiver-drier section 16. Here, the refrigerant is subcooled.

[0059] The refrigerant flowing from the subcooling section 16 of the external heat exchanger 7 flows from the check valve 18 into the refrigerant line 13B and through the internal heat exchanger 19 to the internal expansion valve 8. The refrigerant is decompressed in the internal expansion valve 8 and then flows into the heat absorber 9 to evaporate. At this point, the water in the air blown out by the internal fan 27 coagulates and adheres to the heat absorber 9 through the heat absorption process, thus cooling and dehumidifying the air.

[0060] The refrigerant evaporated in the heat absorber 9 flows through the evaporation control valve 11, the internal heat exchanger 19, and the refrigerant line 13C to the reservoir 12, where it is drawn into the compressor 2, and this circulation is repeated. The air cooled and dehumidified in the heat absorber 9 is reheated as it flows through the radiator 4 (its radiative efficiency is lower than during the initial heating), thus dehumidifying and cooling the vehicle interior. The control unit 32 regulates the speed Nc of the compressor 2 based on the temperature of the heat absorber 9, which is detected by the heat absorber temperature sensor 48. It also controls the valve position of the external expansion valve 6 based on the aforementioned high pressure R of the refrigerant circuit and regulates the refrigerant pressure of the radiator 4 (the radiator pressure PCI). (5) Cooling operation

[0061] Next, in cooling mode, the control unit 32 opens the solenoid valve 20 in the dehumidifying and cooling mode described above (in this case, the external expansion valve 6 can be in any position, including fully open (the valve position is an upper limit of the control)), and the air mixing flap 28 controls a state in which it has a volume of supply air, including the state in which the air does not pass through the radiator 4. Consequently, the high-temperature, high-pressure gas refrigerant discharged by the compressor 2 flows into the radiator 4. If the air in the airflow duct 3 does not pass through the radiator 4, the refrigerant only flows through the radiator, and if the air does pass through the radiator, the control unit allows the refrigerant to radiate heat into the air.The refrigerant flowing out of the radiator 4 flows through the refrigerant line 13E to the solenoid valve 20 and the external expansion valve 6.

[0062] At this point, the solenoid valve 20 opens, and the refrigerant bypasses the external expansion valve 6 to flow through the auxiliary line 13J and into the external heat exchanger 7. There, the refrigerant is cooled by flowing through it or by the outside air passing through the external fan 15, causing it to condense and liquefy. The refrigerant exiting the external heat exchanger 7 flows from the refrigerant line 13A through the solenoid valve 17 to successively enter the receiver-drier section 14 and the subcooling section 16. Here, the refrigerant is subcooled.

[0063] The refrigerant flowing from the subcooling section 16 of the external heat exchanger 7 passes through the check valve 18 to the refrigerant line 13B and flows through the internal heat exchanger 19 to the internal expansion valve 8. The refrigerant is decompressed in the internal expansion valve 8 and then flows into the heat absorber 9 to evaporate. At this point, the water in the air blown out by the internal fan 27 coagulates and adheres to the heat absorber 9 through heat absorption, thus cooling the air.

[0064] The refrigerant evaporated in the heat absorber 9 flows through the evaporation control valve 11, the internal heat exchanger 19, and the refrigerant line 13C to the storage tank 2, and from there is drawn into the compressor 2, with this circulation being repeated. The air cooled and dehumidified in the heat absorber 9 does not flow through the radiator 4, or only to a minimal extent, and is blown out of the outlet opening 29 into the vehicle interior, thus cooling the vehicle interior. In this cooling operation, the control unit 32 controls the speed Nc of the compressor 2 based on the temperature of the heat absorber 9, which is detected by the heat absorber temperature sensor 48.

[0065] Upon commissioning, the control unit 32 selects the operating mode based on the outside air temperature Tam, which is detected by the outside air temperature sensor 33, and the setpoint outlet temperature TAO. Furthermore, after commissioning, the control unit selects and modifies the above-mentioned operating modes depending on changes in the environment and predetermined conditions of the outside air temperature Tam, the setpoint outlet temperature TAO, and similar parameters. (6) Vacuum protection control via control unit

[0066] Next, an example of controlling a negative pressure protection system using the control unit 32 in the aforementioned heating operation will be given with reference to Fig. 3 to Fig. 5 described. As described above, the vacuum protection control section 62 of the control unit 32 limits the added value (TGNCff + TGNCfb) of the F / F tax amount TGNCff, calculated by the F / F tax amount calculation section 58, and the amount TGNCfb, calculated by the F / B tax amount calculation section 60.

[0067] In this case, the vacuum protection control section 62 selects a smaller value (MIN) of values ​​consisting of a value obtained by multiplication by a predetermined increase, a difference (Ts - TGTs) obtained by subtracting a limit setpoint TGTs for vacuum protection from the intake refrigerant temperature Ts, which is a sensed value detected by the intake temperature sensor 44 (the sensing means), and adding a previous compressor setpoint speed TGNCpst to the multiplied value, and the above added value (TGNCff + TGNCfb), to determine the selected value as the compressor setpoint speed TGNC.

[0068] In particular, if the intake refrigerant temperature Ts is lower than the limit setpoint TGTs, the value of the difference (Ts - TGTs), multiplied by the predetermined increase, is necessarily negative. Therefore, the value obtained by adding the previous compressor setpoint speed TGNCpst to the value of this difference (Ts - TGTs), multiplied by the predetermined increase, is less than the previous compressor setpoint speed TGNCpst. Then, if the value obtained by adding the previous compressor setpoint speed TGNCpst to the value of the difference (Ts - TGTs), multiplied by the predetermined increase, is less than the added value (TGNCff + TGNCfb), the value is selected. If the value is greater than the added value, the added value (TGNCff + TGNCfb) is selected. Therefore, in any case, the compressor setpoint speed TGNC decreases if the intake refrigerant temperature Ts is lower than the limit setpoint TGTs.

[0069] Consequently, the vacuum protection control section 62 of the control unit 32 adjusts the speed of compressor 2 so that the intake refrigerant temperature Ts of the measured value, which is detected by the intake temperature sensor 44, does not fall below the limit setpoint TGTs (the vacuum protection function). However, the control unit 32 also changes the limit setpoint TGTs when compressor 2 is started in heating mode.

[0070] Fig. Figure 4 shows a conceptual diagram of such variable control of the limit setpoint TGTs by the control device 32. In this case, the control device 32 has a predetermined lower limit TGTsL (the aforementioned conventional fixed value of the limit setpoint TGTs). Fig. 10: TLS + 3 degrees) and an upper limit TGTsH (TGTsL + 3 degrees), which is higher than this lower limit TGTsL by a predetermined value (e.g., 3 degrees). When compressor 2 is started up, the control unit first sets the limit setpoint TGTs to the upper limit TGTsH. Therefore, when compressor 2 is started up, the vacuum protection control section 62 limits the compressor setpoint speed TGNC so that the intake refrigerant temperature Ts, detected by the intake temperature sensor 45, does not fall below this upper limit TGTsH.

[0071] If the intake refrigerant temperature Ts, detected by the intake temperature sensor 44, drops to the upper limit TGTsH (Ts = TGTsH), the control unit 32 reduces the limit setpoint TGTs towards the lower limit TGTsL. In this case, if a range from the upper limit TGTsH (0% of a dashed line, labeled TGTs (changeable)) in a lower range of the Fig. 4) up to the lower limit TGTsL as 100% (a dashed line, labelled TGTs (not changeable) in the lower range of the Fig. 4) is defined, for example, the control device 32 reduces the limit setpoint TGTs by up to 63.6% in 30 to 60 seconds with a time constant of a first-order delay, as defined by the dashed line, labelled TGTs (changeable) in the lower range of the Fig. 4, is shown.

[0072] It should be noted that an upper area of ​​the Fig. 4 and an upper area of ​​the Fig. 5 changes in the intake refrigerant temperature Ts, detected by the intake temperature sensor 44, show, and the lower range of the Fig. 4 and a middle range of Fig. Five changes to the aforementioned limit setpoint TGTs are shown. Furthermore, a solid line (changeable) indicates a lower range of the Fig. 5 a change in the speed Nc of the compressor 2 by such a variable control of the limit setpoint TGTs.

[0073] If the limit setpoint TGTs is fixed at TLS + 3 degrees, as in conventional control ( Fig. 10), the speed Nc of compressor 2 increases rapidly from start-up due to the reaction delay of the intake temperature sensor 44, as from a non-changing area (a dashed line) in Fig. 5 is shown, and therefore the intake refrigerant temperature Ts drops significantly below the lower limit TGTsL in each figure, as shown by the non-changing regions in Fig. 4 and Fig. Figure 5 is shown. Subsequently, a so-called overshoot occurs, in which the temperature of the refrigerant actually drawn into compressor 2 drops significantly below the intake refrigerant temperature Ts.

[0074] On the other hand, as in the embodiment, the control device limits the speed Nc of compressor 2 so that the limit setpoint TGTs is the upper limit TGTsH from the beginning when compressor 2 is started up, and thereafter gradually reduces the limit setpoint TGTs towards the lower limit TGTsL. Consequently, as shown by the solid line (changeable) in Fig. As shown in Figure 5, the rotational speed Nc of compressor 2 is limited from the time when the intake refrigerant temperature Ts drops to the upper limit TGTsH, and the rotational speed does not increase rapidly. Subsequently, the intake refrigerant temperature Ts also drops gently, as shown in a variable range in each figure, and the temperature of the refrigerant actually drawn into compressor 2 also drops gently, thus eliminating or effectively preventing overshoot. Thereafter, the intake refrigerant temperature Ts, detected by the intake temperature sensor 44, and the temperature of the refrigerant actually drawn into compressor 2 ultimately converge at the lower limit TGTsL. Fig. 4 and Fig. 5).

[0075] In this embodiment, the control device 32 has a vacuum protection function for adjusting the speed Nc of the compressor 2 so that the intake refrigerant temperature Ts (the detected value) does not fall below the limit setpoint TGTs, based on the intake refrigerant temperature Ts, which is the detected value of the intake temperature sensor 44, and the limit setpoint TGTs, which is set to the temperature of the refrigerant to be drawn into the compressor 2 (the intake refrigerant temperature), and the control device has the predetermined lower limit TGTsL and the predetermined upper limit TGTsH, which is higher than the predetermined lower limit, and adjusts the speed Nc of the compressor 2 so that the limit setpoint TGTs is the upper limit TGTsH when the compressor 2 is started up.and the control unit gradually reduces the limit setpoint TGTs towards the lower limit TGTsL as the intake refrigerant temperature Ts (the detected value) drops to the upper limit TGTsH. Consequently, by setting the lower limit TGTsL to the aforementioned conventional value (TLS + 3 degrees) of the limit setpoint, the control unit 32 adjusts the speed Nc of compressor 2 by setting the limit setpoint TGTs to the upper limit TGTsH, which is higher than the lower limit at the start-up of compressor 2.

[0076] Consequently, the vacuum protection starts earlier than in conventional technology, effectively preventing overshoot of the actual intake refrigerant temperature due to the response delay of the intake temperature sensor 44. This improves the reliability of compressor 2 and the low-pressure side components. Furthermore, the control unit 32 reduces the limit setpoint TGTs towards the lower limit TGTsL as the intake refrigerant temperature Ts (the detected value) drops to the upper limit TGTsH. Therefore, accurate vacuum protection is achieved without unnecessarily limiting the speed of compressor 2.

[0077] In this case, the control unit 32 reduces the limit setpoint TGTs to the lower limit TGTsL with the predetermined time constant of the first-order delay when the intake refrigerant temperature Ts (the detected value) drops to the upper limit TGTsH. Therefore, it is possible to precisely reduce the limit setpoint TGTs as a function of the decrease in the temperature of the refrigerant actually drawn into the compressor 2 (the temperature of the drawn-in refrigerant). Design 2

[0078] Next, a constitutional view of a vehicle air conditioning system 1 of an embodiment of the present invention and a negative pressure protection control of a control unit 32 is shown, in this case with reference to Fig. 6 and Fig. 7 described. It should be noted that components in Fig. 6, which are designated with the same reference symbols as in Fig. 1, perform the same or similar functions. In this case, an auxiliary heating source 40 is arranged as an auxiliary heating medium on an upstream side (an upstream airflow side) of a radiator 4 for the flow of air in an airflow duct 3. This auxiliary heating source 40 in this embodiment consists of a PTC heating device (an electric heating device).

[0079] When the heating capacity of the radiator 4 becomes insufficient during heating operation, the control device 32, in the conventional manner, causes the auxiliary heating source 40 to generate (operate) heat and heats the air in the airflow channel 3 that flows into the radiator 4 to compensate for the heating capacity of the radiator 4 in order to contribute to heating a vehicle interior, but in this invention the control device also actuates the auxiliary heating source 40 when a compressor 2 is started up.

[0080] Fig. Figure 7 shows a time diagram of an intake refrigerant temperature Ts, detected by an intake temperature sensor 44, and a speed Nc of the compressor 2, and an operating state of the auxiliary heating source 40 in this case. According to the embodiment, when the compressor 2 is started in heating mode, the control device 32 first heats the auxiliary heating source 40 before the compressor 2 is started, and an internal fan 27 begins to operate. Afterwards, the control device 32 starts the compressor 2, but in this case, the air flowing into the radiator 4 is heated by the auxiliary heating source 40 to increase the air temperature, thus increasing the high pressure R of a refrigerant circulation circuit and also the low pressure.

[0081] Furthermore, the rotational speed Nc of compressor 2 does not increase due to an increase in radiator pressure PCI (represented in a low range of the Fig. 7) rises rapidly, and therefore the intake refrigerant temperature Ts does not drop rapidly when compressor 2 is started up. A solid line in the upper range of the Fig. Figure 7 shows the intake refrigerant temperature Ts when the auxiliary heat source 40 is heated (with the auxiliary heat source in operation), and a dashed line within it shows a change in the intake refrigerant temperature Ts when the auxiliary heat source is not heated (without the auxiliary heat source in operation). When the auxiliary heat source 40 is not heated, as shown by the dashed line, the intake refrigerant temperature Ts and the temperature (the temperature of the refrigerant drawn in) of the refrigerant actually drawn into compressor 2 drop significantly and overshoot. However, when the auxiliary heat source 40 is heated, the intake refrigerant temperature Ts drops gently after compressor 2 starts up, and the temperature (the temperature of the refrigerant drawn in) of the refrigerant actually drawn into compressor 2 does not overshoot.

[0082] It should be noted that if compensation of the heating by means of the auxiliary heating source 40 is not necessary, the control device 32 stops the heating from the auxiliary heating source 40 in a state in which the intake refrigerant temperature Ts is stable. Furthermore, in embodiment 2, as described above, the control device starts the heating from the auxiliary heating source 40 and then starts the compressor 2, but it can start operation from the auxiliary heating source simultaneously with the start-up of the compressor 2.

[0083] Furthermore, the negative pressure protection control of embodiment 1, as described above, can be combined with the operation of the auxiliary heating source of embodiment 2. In particular, when the compressor 2 is started up in heating mode, if the control device starts the compressor 2 while it is heating the auxiliary heating source 40, in addition to performing a change control of a limit setpoint TGTs, it is possible to further and more effectively prevent so-called overshoot of the actual intake refrigerant temperature, and the reliability of the compressor 2 and the low-pressure side components can be improved. embodiment 3

[0084] In addition to the low-pressure protection control by the change control of the limit setpoint TGTs of the embodiment 1 described above and the low-pressure protection control of the operation of the auxiliary heating source 40 of embodiment 2, or separately from such control, a control device 32 can alternatively reduce an upper limit speed of the control of a compressor 2, for example an upper limit speed TGNCh of a compressor setpoint speed TGNC for a predetermined time after the commissioning of the compressor 2 or when a high pressure (a radiator pressure PCI) is lower than a predetermined value.

[0085] If the upper limit speed TGNCh of the compressor setpoint speed TGNC decreases, the speed Nc of compressor 2 does not increase significantly during compressor 2 start-up or when the high pressure is lower, due to feedback back-control from the F / B control amount calculation section 60 described above. Therefore, it is possible to prevent the disadvantage of the refrigerant temperature (the temperature of the refrigerant drawn into the compressor) rapidly dropping below the limit setpoint TGTs described above, and an improvement in reliability can be achieved. Design 4

[0086] Next is Fig. Figure 8 shows a diagram illustrating yet another example of a vacuum protection control system implemented by a control unit 32. It should be noted that a constitution of the Fig. 1 as a constitution of a vehicle air conditioning system 1 of an object is effective and a constitution of the Fig. 6 is also effective. Fig. Figure 8 shows speed limit data processed by the control unit 32. The data shows a relationship between an outside air temperature Tam, detected by an outside air temperature sensor 33, and an upper speed limit of the control unit of a compressor 2, that is, an upper speed limit TGNCh and a compressor setpoint speed TGNC.

[0087] These speed limit data show the relationship between the ambient air temperature Tam and the upper speed limit TGNCh at which the intake refrigerant temperature Ts, when compressor 2 operates at ambient air temperature Tam, does not fall below a limit setpoint TGTs, corresponding to the lower limit limit TGTsL described above. This relationship is obtained beforehand through experiments. (-20, TGNC1) in the figure means that if the ambient air temperature Tam is, for example, -20°C, the control unit sets the upper speed limit TGNCh to TGNC1, and therefore the intake refrigerant temperature Ts does not fall below the limit setpoint TGTs.

[0088] Similarly, (-15, TGNC2) means that if the outside air temperature Tam is, for example, -15°C, the control unit sets the maximum speed TGNCh to TGNC2, and therefore the intake refrigerant temperature Ts does not fall below the limit setpoint TGTs; (-10, TGNC3) means that if the outside air temperature Tam is, for example, -10°C, the control unit sets the maximum speed TGNCh to TGNC3, and therefore the intake refrigerant temperature Ts does not fall below the limit setpoint TGTs; and (-5, TGNC4) means that if the outside air temperature Tam is, for example, -5°C, the control unit sets the maximum speed TGNCh to TGNC4, and therefore the intake refrigerant temperature Ts does not fall below the limit setpoint TGTs. It should be noted that there is a tendency for TGNC1 < TGNC2 < TGNC3 < TGNC4.

[0089] When the control unit 32 subsequently starts the compressor 2 in heating mode, the control unit derives the maximum speed TGNCh, corresponding to the outside air temperature Tam at that time, from the outside air temperature Tam, as measured by the outside air temperature sensor 33, in order to change the control unit's maximum speed to the maximum speed TGNCh. Consequently, when the control unit calculates the target compressor speed TGNC, it reduces the TGNC speed to the changed maximum speed TGNCh.

[0090] In this embodiment, the control unit changes the upper speed limit TGNCh of compressor 2 based on the outside air temperature Tam, and therefore the control unit can change the upper speed limit TGNCh of compressor 2 depending on the outside air temperature Tam, so that the intake refrigerant temperature Ts does not fall below the limit setpoint TGTs. As a result, an improvement in reliability can be achieved.

[0091] It should be noted that the underpressure control described above for embodiment 1 can also be combined with the upper speed limit control TGNCh in this case. That is, when compressor 2 is started up in heating mode, the control unit performs the control of the limit setpoint TGTs, and additionally, the control unit also changes the upper speed limit TGNCh of compressor 2 depending on the outside air temperature Tam. Consequently, it is possible to further effectively prevent so-called overshoot of an actual intake refrigerant temperature, and the reliability of compressor 2 and the low-pressure-side components can be improved.However, in this case, for the speed limit data, a ratio between the outside air temperature Tam and the upper speed limit TGNCh, at which the intake refrigerant temperature Ts does not fall below the aforementioned lower limit TGTsL when compressor 2 operates at the outside air temperature Tam, is obtained through experiments. Design 5

[0092] Next, show Fig. Figure 9 shows another constitutional view of a vehicle air conditioning system 1 of the present invention. In this embodiment, a collecting dryer section 14 and a subcooling section 16 are not provided in an external heat exchanger 7, and a refrigerant line 13A extending from the external heat exchanger 7 is connected to a refrigerant line 13B via a solenoid valve 17 and a check valve 18. Furthermore, a refrigerant line 13B branching off from the refrigerant line 13A is also connected to a refrigerant line 13C on a downstream side of an internal heat exchanger 19 via a solenoid valve 21.

[0093] The other constitution is similar to the example of the Fig. 1. The present invention is also effective in the vehicle air conditioning system 1 of a refrigerant circulation circuit R, where an external heat exchanger 7, which does not have the collector dryer section 17 and the subcooling section 16 in this way, is used.

[0094] It should be noted that, in the embodiments described above, the intake temperature Ts, detected by the intake temperature sensor 44, which measures the temperature of the refrigerant being drawn into the compressor 2, is converted into pressure to perform the vacuum protection control. However, if an intake pressure sensor, which measures the pressure of the refrigerant being drawn into the compressor 2, is provided, the vacuum protection control can be achieved directly with an intake refrigerant pressure. In this case, the intake refrigerant temperature Ts described above is replaced by an intake refrigerant pressure Ps, detected by the intake pressure sensor, and the respective values ​​of the limit setpoint TGTs, the upper limit TGTsH, and the lower limit TGTsL are replaced by the respective pressure values ​​of a limit setpoint TGPs, an upper limit TGPsH, and a lower limit TGPsL.

[0095] Furthermore, the constitution of the refrigerant circulation circuit R or any numerical value, as described above in each embodiment, does not limit the present invention and is modifiable without departing from the idea of ​​the present invention. DESCRIPTION OF THE REFERENCE MARKS 1 Vehicle air conditioning 2 compressor 3 airflow channel 4 radiators 6 External expansion valve 7 external heat exchangers 8 Interior expansion valve 9 heat absorbers 11 17, 20, Evaporation capacity control valve 21, 22 Solenoid valve (opening / closing valve) 26 Intake changeover flap 27 internal fans (one blower fan) 28 Air mixing flap 32 Control device (a control instrument) 44 Intake air temperature sensor R Refrigerant circulation circuit

Claims

[1] A vehicle air conditioning system (1) comprising: a compressor (2) for compressing a refrigerant, an airflow channel (3) through which air to be supplied to the vehicle interior flows, a radiator (4) arranged in this airflow duct (3) to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger (7) arranged outside the vehicle interior to allow the refrigerant to absorb heat, a detection means (44) for detecting an intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and a tax resource (32), so that the control medium (32) causes the refrigerant released by the compressor (2) to radiate heat into the radiator (4), and decompresses the refrigerant from which the heat was radiated in order to allow the refrigerant in the external heat exchanger (7) to absorb heat, thereby heating the vehicle interior; wherein the control means (32) has a vacuum protection function for setting a speed of the compressor (2) so that a detected value does not fall below a limit setpoint, based on the detected value of the detection means (44) and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor (2), the control means (32) has a predetermined lower limit and a predetermined upper limit which is higher than the predetermined lower limit, and sets the speed of the compressor (2) by setting the limit setpoint as the upper limit when starting up the compressor (2), and the taxable amount (32) gradually reduces the limiting target value towards the lower limit as the recorded value falls towards the upper limit. [2] The vehicle air conditioning system (1) according to claim 1, wherein the control means (32) reduces the limit setpoint to the lower limit limit with a predetermined time constant of a first-order delay when the detected value falls to the upper limit limit. [3] The vehicle air conditioning system (1) according to claim 1 or 2, comprising: an auxiliary heating medium (40), arranged on an upstream side of the radiator (4) to the flow of air in the airflow channel (3), wherein the control medium (32) causes the auxiliary heating medium (40) to generate heat when the compressor (2) is started up. [4] The vehicle air conditioning system (1) according to any one of claims 1 to 3, wherein the control means (32) displays speed limit data which shows a ratio between an outside air temperature and an upper limit speed of the compressor (2) at which the intake refrigerant temperature or intake refrigerant pressure does not fall below the lower limit at the outside air temperature and the control means (32) changes the upper limit speed of the compressor (2) based on the outside air temperature depending on the speed limit data. [5] The vehicle air conditioning system (1) according to any one of claims 1 to 3, wherein the control means (32) reduces an upper limit speed of the compressor (2) for a predetermined time after the compressor has been started or when a high pressure is lower. [6] The vehicle air conditioning system (1), comprising: a compressor (2) for compressing a refrigerant, an airflow channel (3) through which air to be supplied to the vehicle interior flows, a radiator (4) arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an auxiliary heating medium (40), arranged on an upstream side of the radiator (4) to the flow of air in the airflow channel (3), an external heat exchanger (7) arranged outside the vehicle interior to allow the refrigerant to absorb heat, a detection means (44) for detecting an intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and a tax resource (32), so that the control medium (32) causes the refrigerant released by the compressor (2) to radiate heat into the radiator (4), and decompresses the refrigerant from which the heat was radiated in order to allow the refrigerant in the external heat exchanger (7) to absorb heat, thereby heating the vehicle interior; wherein the control means (32) has a vacuum protection function for adjusting the speed of the compressor (2) so that a detected value does not fall below a limit setpoint, based on the detected value from the detection means (44) and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and the control medium (32) allows the auxiliary heating medium to generate heat when the compressor (2) is put into operation. [7] A vehicle air conditioning system (1), comprising; a compressor (2) for compressing a refrigerant, an airflow duct (3) through which air to be supplied to the vehicle interior flows, a radiator (4) arranged in this airflow duct to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger (7) arranged outside the vehicle interior to allow the refrigerant to absorb heat, a detection means (44) for detecting an intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and a tax resource (32), so that the control medium (32) causes the refrigerant released by the compressor (2) to radiate heat into the radiator (4), and decompresses the refrigerant from which the heat was radiated in order to allow the refrigerant in the external heat exchanger (7) to absorb heat, thereby heating the vehicle interior; wherein the control means (32) has a vacuum protection function for adjusting the speed of the compressor (2) so that a detected value does not fall below a limit setpoint, based on the detected value from the detection means (44) and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and the control means (32) has speed limiting data which show a ratio between an outside air temperature and an upper limit speed of the compressor (2) at which the intake refrigerant temperature or intake refrigerant pressure does not fall below the limit setpoint at the outside air temperature, and changes the upper limit speed of the compressor (2) on the basis of the outside air temperature depending on the speed limiting data. [8] A vehicle air conditioning system (1) comprising: a compressor (2) for compressing a refrigerant, an airflow channel (3) through which air flows to be supplied to the vehicle interior, a radiator (4) arranged in this airflow duct (3) to allow the refrigerant to radiate heat, thereby heating the air supplied to the vehicle interior, an external heat exchanger (7) arranged outside the vehicle interior to allow the refrigerant to absorb heat, a detection means (44) for detecting an intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and a tax resource (32), so that the control medium (32) allows the refrigerant released by the compressor (2) to radiate heat into the radiator (4), and decompresses the refrigerant from which the heat was radiated in order to allow the refrigerant in the external heat exchanger (7) to absorb heat, thereby heating the vehicle interior; wherein the control means (32) has a vacuum protection function for adjusting the speed of the compressor (2) so that a detected value does not fall below a limit setpoint, based on the detected value from the detection means (44) and the limit setpoint set to the intake refrigerant temperature or intake refrigerant pressure of the compressor (2), and the control means (32) reduces an upper limit speed of the compressor (2) for a predetermined time after the compressor (2) is started or, if a high pressure is lower.

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