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  Refrigeration cycle device for vehicleUSPTO Application #: 20060236708Title: Refrigeration cycle device for vehicle Abstract: A refrigeration cycle device for a vehicle includes a condition detecting unit for detecting a condition that an inner pressure of the refrigerant cycle exceeds a control set pressure, and a pressure reducing unit for reducing a pressure of the refrigerant at a low pressure side of a refrigerant cycle when the condition is detected. For example, when the condition detecting unit detects the condition, the pressure reducing unit starts up a compressor of the refrigerant cycle so as to reduce the pressure at the low pressure side in the refrigerant cycle. (end of abstract) Agent: Harness, Dickey & Pierce, P.L.C - Bloomfield Hills, MI, US Inventors: Syuichi Mizuno, Shin Nishida, Satoshi Itoh, Nobuharu Kakehashi USPTO Applicaton #: 20060236708 - Class: 062228300 (USPTO) Related Patent Categories: Refrigeration, Automatic Control, Refrigeration Producer, Compressor Or Its Drive Controlled, By Refrigerant Pressure The Patent Description & Claims data below is from USPTO Patent Application 20060236708. Brief Patent Description - Full Patent Description - Patent Application Claims
CROSS REFERENCE TO RELATED APPLICATION [0001] This application is based on Japanese Patent Applications No. 2005-127000 filed on Apr. 25, 2005, and No. 2006-55384 filed on Mar. 1, 2006, the contents of which are incorporated herein by reference in its entirety. FIELD OF THE INVENTION [0002] The present invention relates to a vehicle refrigeration cycle device using refrigerant containing carbon dioxide (CO.sub.2) as a main component, for example. BACKGROUND OF THE INVENTION [0003] As one of this type of refrigeration cycle devices is known a refrigeration cycle device equipped with a compressor in which the discharge capacity thereof is variable in accordance with a control amount input from the external and the pressure of refrigerant can be increased up to a supercritical area, a heat radiator for cooling the refrigerant compressed by the compressor, an expansion device for reducing the pressure of the refrigerant cooled by the heat radiator, and an evaporator for evaporating the refrigerant reduced in pressure by the expansion device. According to this refrigeration cycle device, when it is determined that a thermal load at the start time of the device is larger than a predetermined load, the control amount to be input from the external is adjusted so that the discharge amount of the compressor is continuously varied from the minimum state to the maximum state during a predetermined time, whereby abnormal increase of high pressure can be suppressed even at the start time of the refrigerant cycle under a high load, and thus pipes, etc. can be prevented from being damaged (for example, JP-A-2002-71228). [0004] In the above-described refrigeration cycle device, the abnormal increase of the high pressure is suppressed by controlling the output condition of the compressor when the compressor is started, and there is no description on the timing of driving the compressor under the stopped state. Particularly in the refrigeration cycle device for a vehicle, as compared with the increase of the refrigerant pressure due to increase of the ambient temperature such as the outside air temperature or the like, the increase of the refrigerant pressure is more greatly affected by heat occurring from an engine, etc. during travel of the vehicle, so that the increase of the refrigerant pressure when the compressor is under the stopped state causes a more critical problem. SUMMARY OF THE INVENTION [0005] The present invention has been implemented in view of the foregoing problem, and has an object to provide a refrigeration cycle device for a vehicle that can suppress increase of refrigerant pressure. [0006] Furthermore, the present invention has another object to provide a refrigeration cycle device for a vehicle that can suppress excessive increase of refrigerant pressure by forcedly operating a refrigerant cycle even under the state that a driver does not make any request for actuating the refrigerant cycle. [0007] Still furthermore, the present invention has further object to provide a refrigeration cycle device for a vehicle that can suppress increase of refrigerant pressure due to afterheat from an engine, an electric motor or the like after the vehicle is stopped. [0008] Still furthermore, the present invention has further object to provide a refrigeration cycle device for a vehicle that can suppress pressure increase of a refrigerant cycle after stop of an engine serving as a driving force source of the refrigerant cycle or the like by forcedly operating the refrigerant cycle before the engine or the like is stopped. [0009] Still furthermore, the present invention has further object to provide a refrigeration cycle device for a vehicle that can suppress pressure increase of a refrigerant cycle even after stop of an engine, an electric motor or the like serving as a driving force source of the refrigerant cycle by enabling the refrigerant cycle to be forcedly driven. [0010] According to an aspect of the present invention, a vehicle refrigeration cycle device includes a refrigerant cycle through which refrigerant circulates, a condition detecting unit for detecting a condition that an inner pressure of the refrigerant cycle exceeds a control set pressure, and a pressure reducing means for reducing a pressure of the refrigerant at a low pressure side of the refrigerant cycle when the condition is detected. Accordingly, an increase of the refrigerant pressure due to heat from the engine or the like when the vehicle travels can be suppressed and thus the equipment of the vehicle can be prevented from being damaged. [0011] For example, the control set pressure is set lower than a set value that is set for a lowest withstanding pressure in the refrigerant cycle. In this case, the functions of respective functional parts of the refrigerant cycle can be warranted by setting the control set pressure to be lower than the lowest withstanding pressure set value in the refrigerant cycle. [0012] The refrigerant cycle can include a relief device with a set pressure for protecting an equipment at the low pressure side in the refrigerant cycle. In this case, the control set pressure is set to be lower than the set pressure of the relief device. The control set pressure can be set to be lower than the set pressure of the relief device for protecting the equipment at the low pressure side of the refrigerant cycle by 0.5 MPa or more. When carbon dioxide is used as a main component of the refrigerant, the control set pressure is set in a range between 7 MPa and 12 MPa. Furthermore, the control set pressure can be set in prospect of an increase of the pressure in the refrigerant cycle. In addition, the control set pressure can be set in prospect of an increase of the pressure in the refrigerant cycle due to residual heat of an engine of the vehicle after an ignition switch of the vehicle is set to OFF. [0013] When the refrigerant cycle includes a relief device with a set pressure for protecting an equipment at the low pressure side in the refrigerant cycle, the control set pressure is set to be lower than the set pressure of the relief device by 1.0 MPa or more. [0014] Generally, the refrigerant cycle includes a compressor for compressing refrigerant, a gas cooler for cooling the refrigerant discharged from the compressor, and a cooling fan for blowing air to the gas cooler. In this case, the pressure reducing means starts up at least one of the cooling fan and the compressor by a control unit when the condition detecting unit detects the condition, and reduces the refrigerant pressure at the low pressure side in the refrigerant cycle. Therefore, the refrigerant pressure due to environment condition can be effectively reduced. [0015] As the compressor, a displacement variable compressor can be used. In this case, the pressure reducing means starts up the displacement variable compressor while a discharge capacity of the displacement variable compressor is controlled by the control unit when the condition detecting unit detects the condition. [0016] The pressure reducing means can start up the compressor when the condition detecting unit detects the condition while an engine of the vehicle is operated under a state where an ignition switch of the vehicle is set to ON. [0017] Alternatively, the compressor can be constructed with an electrical compressor driven electrically. In this case, the condition detecting unit detects the condition under a state where an ignition switch of the vehicle is set to OFF. [0018] The refrigerant cycle can be provided with a compressor for compressing refrigerant, a gas cooler for cooling the refrigerant discharged from the compressor, an evaporator for evaporating refrigerant after being decompressed, a first fan for blowing air to the gas cooler, and a second fan for blowing air to the evaporator. In this case, when the condition detecting unit detects the condition, at least one of the first fan and the compressor is driven and the second fan is stopped by the control unit. [0019] The condition detecting unit can include a pressure detecting unit for detecting whether the refrigerant pressure in the refrigerant cycle reaches a predetermined value. For example, the pressure detecting unit is a discharge pressure sensor for detecting the refrigerant pressure at a discharge side of the compressor in the refrigerant cycle. [0020] Alternatively, the condition detecting unit can include a first temperature detecting unit for detecting whether a refrigerant temperature in the refrigerant cycle reaches a predetermined value. In this case, the first temperature detecting unit includes a discharge temperature sensor for detecting a refrigerant temperature at a discharge side of the compressor of the refrigerant cycle. Furthermore, the first temperature detecting unit can include at least one of a post-evaporation temperature sensor for detecting a temperature of air passed through the evaporator of the refrigerant cycle, a fin temperature sensor for detecting a temperature of a fin of the evaporator, and an air blow-out temperature sensor for detecting a temperature of air to be blown into a passenger compartment of the vehicle. Continue reading... Full patent description for Refrigeration cycle device for vehicle Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Refrigeration cycle device for vehicle patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. 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