Nippondenso Co., Ltd.

Akio Matsuoka

Masashi Takagi

Kazutoshi Nishizawa

Yuuji Honda

Fuzio Nomura

Akiro Yoshimi

Masasi Takagi

A condenser is connected to an outlet of a compressor. An expansion valve is connected to the condenser. An evaporator is connected between the expansion valve and an inlet of the compressor. A sensor detects a condition of refrigerant at an outlet side of the evaporator. A variation in rate of refrigerant flow into the evaporator is detected. A control device determines a variation in the detected condition of refrigerant which occurs in response to the variation in the rate of refrigerant flow. The control device judges a quantity of refrigerant to be insufficient when the determined variation in the refrigerant condition is equal to or smaller than a reference value.

Refrigeration system

A rotary compressor comprises an input shaft, a compressor component and a clutch component movable between an engaged position where the compressor component is connected to the input shaft to allow a torque to be transmitted from the input shaft to the compressor component and a disengaged position where the compressor component is disconnected from the input shaft to prevent the torque from being transmitted from the input shaft to the compressor component. A hydraulic pump is drivingly connected to the input shaft to discharge a pressurized working fluid upon the rotation of the input shaft. The clutch component includes a clutch member disposed within a clutch cylinder and cooperating therewith to define a pressure chamber. A valve unit is movable between a position where the pressurized working fluid from the pump is allowed to be applied to the pressure chamber to cause the clutch member to be engaged with a rotor member of the compressor component thereby moving the clutch component to the engaged position and a position where the pressurized working fluid from the pump is prevented from being applied to the pressure chamber to prevent the clutch member from engaging with the rotor member to move the clutch component to the disengaged position.

Rotary compressor with clutch and bypass control actuated by hydraulic

The degree of opening of the expansion valve in refrigeration system is controlled by means of PID control such that a refrigerant superheat at the outlet of the evaporator approaches a target valve. Since an elapsed time after the start of the refrigeration system varies in response to a change of a heat load of air to be cooled by the evaporator, if the control constant of the PID control is designed so that the expansion valve can be controlled adequately for high evaporator heat load, or for low evaporator heat load, adequate control cannot be achieved in the opposite case not taken into consideration in design. According to the present invention, the control constant of the PID control is varied when an elapsed time after the start of the refrigeration system reaches a reference time which is determined on the basis of a heat load of air to be cooled by the evaporator.

Rotary compressor with clutch actuated by hydraulic fluid and compressed

A variable capacity vane type compressor has an unloading mechanism operative to relieve a part of compressed fluid from a working chamber when in its compression stroke and an additional mechanism for controlling the suction of fluid into the compressor. The additional mechanism has a spool valve movable to a position to restrict the opening area of the compressor suction port. The spool valve is disposed in a passage communicated with the suction port and with a working chamber when in its compression stroke. The spool valve is formed therein with another passage which, when the spool valve is in the position to restrict the suction port, communicates the compression chamber with the suction port to relieve a part of the compressed fluid.

Variable capacity vane type compressor

A refrigeration system comprises a refrigeration cycle including a compressor of a variable capacity type for compressing a refrigerant and an evaporator for evaporating the compressed refrigerant. A driving source is connected to the compressor through a clutch movable between an engaged position and a disengaged position. A first detector detects pressure of the refrigerant evaporated by the evaporator to generate a signal. A second detector detects temperature relating to a cooling condition of the evaporator to generate a signal. A capacity control unit controls a discharge capacity of the compressor so as to cause the pressure detected by the first detector to approach an aimed pressure. A clutch control unit is operative in response to the signals from the respective first and second detectors to judge a condition of frosting on the evaporator for controlling the clutch for movement between the engaged and disengaged positions and to judge an insufficiency in quantity of the refrigerant in the refrigeration cycle for controlling the clutch for movement to the disengaged position.

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Obu, Japan

Akio Matsuoka