It is an object of the invention to provide a refrigeration cycle which uses HFC-152a as refrigerant, and can be operated stably without hunting of the superheat degree (SH). A charge amount of refrigerant is increased, and refrigerant at an inlet of an expansion device is placed in a state where the subcool degree (SC) is ensured to be at least 5 degrees such that the subcool degree (SC) does not become equal to zero by variation in pressure. This suppresses fluctuation in the superheat degree (SH) of refrigerant at an outlet of an evaporator to thereby stabilize the system. In this state, to enhance the efficiency of a compressor, the superheat degree (SH) can be increased by decreasing the set value of the expansion device.

A refrigeration cycle containing a variable displacement compressor 1 combines an expansion valve 4 controlling the flow rate to an evaporator 5 such that normally refrigerant at the evaporator outlet always maintains a predetermined level of superheat. A minimum flow rate-securing device 7 is provided to assure a predetermined minimum flow rate when the flow rate is otherwise most restricted.

Expansionsorgan mit einer Festdrossel (2,8,31), einem in einer die Festdrossel (2,8,31) umgehenden Bypassleitung (6,28,36) angeordneten Überdruckventil (3,27,35) und einem mechanischen oder thermischen Regelventil (9,17,37), wobei alle Ventilkomponenten in ein gemeinsames Ventilgehäuse (1,25,30) integriert sind.

Verwendung des Expansionsorgans für CO₂-Klimaanlagen von Kraftfahrzeugen.

A body of a prior art thermal expansion valve is utilized as a valve body 30, and a rod member 316 of a heat sensing shaft 36f is a shaft with small diameter which is driven back and forth across a path 34 according to the displacement of a diaphragm 36a of a power element portion 36, so clearance 37, 38 is formed along the rod member 316 to connect the path 34 and the path 321. In order to seal the clearance, an x-ring 50 contacting the outer peripheral of the rod member 316 is positioned inside a large hole 38, so that the x-ring 50 exists between the two paths. Further, a push nut 41 working as a self-locking nut is mounted on the rod member 316 inside the large hole 38 contacting the x-ring 50 so as to prevent the x-ring from moving in the longitudinal direction (toward the power element portion 36) by the force from a coil spring 32d and the refrigerant pressure inside the path 321.

A body of a prior art thermal expansion valve is utilized as a valve body 30, and a rod member 316 of a heat sensing shaft 36f is a shaft with small diameter which is driven back and forth across a path 34 according to the displacement of a diaphragm 36a of a power element portion 36, so clearance 37, 38 is formed along the rod member 316 to connect the path 34 and the path 321. In order to seal the clearance, an x-ring 50 contacting the outer peripheral of the rod member 316 is positioned inside a large hole 38, so that the x-ring 50 exists between the two paths. Further, a push nut 41 working as a self-locking nut is mounted on the rod member 316 inside the large hole 38 contacting the x-ring 50 so as to prevent the x-ring from moving in the longitudinal direction (toward the power element portion 36) by the force from a coil spring 32d and the refrigerant pressure inside the path 321.

A refrigerating system having a cool storage evaporator 14 and a refrigerating evaporator 15 arranged in series. The cool storage evaporator 14 includes a rounded cross sectioned tube 25 which is in contact with a cool storage material stored in containers. The cool storage material has a melting temperature which substantially corresponds to a predetermined value of evaporating temperature of a refrigerant when the temperature inside a refrigerating compartment is reduced to a predetermined value for switching from a refrigerating operation to a cool storage operation. During the refrigerating operation, the cool storage material is prevented from being frozen, thereby preventing a load to the cool storage material. During a cool storage operation obtained by stopping the operation of an inner fan 31, a throttling of a temperature operated expansion valve 13 maintains desired temperature difference between the temperature of the cool storage material and an evaporating temperature of the refrigerant at the cool storage evaporator 14.

A thermal expansion valve drives a valve body (18) in a housing (10) through a driving member (22) by a gas pressure of a heat sensitive working fluid sealed in a power element (20), neighboring with the housing, by a diaphragm (19). The driving member holds a heat ballast at its blind hole opened to the working fluid. A diaphragm has a center opening surrounded by a tubular projection (30), the diaphragm side end portion of the driving member is inserted in the opening, and a diaphragm catch (32) is fitted on the outer periphery of the projection. The catch, the extended end of the projection and the end of the driving member are airtightly welded each other.

A refrigeration circuit is disclosed, which includes a sub­cooling control valve (12) and a decompression device (13). The sub­cooling control valve (12) controls the flow amount of refrigerant depending upon a detected subcooling value. The decompression device (13) controls changes of the flow amount of refrigerant. Therefore, the refrigeration circuit can control the flow amount of refrigerant and prevent the occurence of hunting phenomenon.

A pulsed controlled solenoid flow control valve suitable for use in a closed vapor cycle air conditioning system is disclosed. A pulsewidth modulated control signal is generated for cyclically opening and closing the flow through the expansion valve. The duty cycle of the pulsed control signal determines the average flow rate through the valve. An exponential response control curve is used in conjunction with an integrator offset to obtain a single set point control operating point for all flow rates through the valve, where a given change in the second superheat of the evaporator produces the same percentage change in flow rate regardless of the flow rate.

A pulsed controlled solenoid flow control valve suitable for use in a closed vapor cycle air conditioning system is disclosed. A pulsewidth modulated control signal is generated for cyclically opening and closing the flow through the expansion valve. The duty cycle of the pulsed control signal determines the average flow rate through the valve. An exponential response control curve is used in conjunction with an integrator offset to obtain a single set point control operating point for all flow rates through the valve, where a given change in the second superheat of the evaporator produces the same percentage change in flow rate regardless of the flow rate.