Abstract: A roots compressor has a housing, a rotary shaft, a rotor and a layer. The housing defines a pump chamber, a suction port and a discharge port. The suction port and the discharge port adjoin to the pump chamber. The rotary shaft is rotatably supported by the housing. The rotor is connected to the rotary shaft and contained in the pump chamber. Fluid introduced into the pump chamber through the suction port is discharged to the outside of the pump chamber through the discharge port by rotation of the rotor which is driven through the rotary shaft. The layer is formed on an inner peripheral surface of the housing, which defines the pump chamber. The layer is thinner from a side adjacent to the suction port toward a side adjacent to the discharge port in circumferential direction of the housing.

Abstract: A starting system for a pump includes a driving motor, an electric source, a selector switch, a starter sensor, a temperature sensor and a control unit. The selector switch is located between the driving motor and the electric source for reversing polarity of the electric power supplied from the electric source to the driving motor. The starter sensor senses whether or not the driving motor has been started. The temperature sensor senses a temperature. The control unit operates the selector switch so as to repeatedly give the driving motor indications of reverse rotation and normal rotation in a case where the starter sensor does not sense that the driving motor has been started even if the control unit operates the selector switch so as to give the driving motor the indication of normal rotation in a state where the temperature sensed by the temperature sensor is below a preset temperature.

Abstract: A starting system for a pump includes a driving motor, an electric source, a selector switch, a starter sensor, a temperature sensor and a control unit. The selector switch is located between the driving motor and the electric source for reversing polarity of the electric power supplied from the electric source to the driving motor. The starter sensor senses whether or not the driving motor has been started. The temperature sensor senses a temperature. The control unit operates the selector switch so as to repeatedly give the driving motor indications of reverse rotation and normal rotation in a case where the starter sensor does not sense that the driving motor has been started even if the control unit operates the selector switch so as to give the driving motor the indication of normal rotation in a state where the temperature sensed by the temperature sensor is below a preset temperature.

Abstract: A fuel cell system includes a fuel cell stack, a hydrogen flowing passage, an air flowing passage and a control valve. At least one of the gas flowing passages includes a bypass, a selecting means, a gas flowing means and a control unit. The bypass allows a gas to flow therethrough so as to detour the fuel cell stack and the control valve. The selecting means selects one of a passage which passes through the fuel cell stack and the bypass. The gas flowing means flows the gas to the bypass. In the control unit, the through passage is selected by the selecting means when the system is operated, The bypass is selected by the selecting means when the operation of the system is stopped. The gas is flowed to the bypass by operating the gas flowing means when the control valve is frozen thereby heating the control valve.

Abstract: A roots compressor module has a roots compressor accommodating drive and driven rotors in a rotor chamber of a compressor housing, an electric motor arranged coaxially with the drive rotor and having a motor housing fixedly connected to the compressor housing, a first device supported on one of the compressor and motor housings, a discharge passage formed in the compressor housing and extending from a discharge side of the rotor chamber in a direction perpendicular to an axis of the drive rotor, and a communication passage connecting the discharge passage with the first device. The first device is located by a side of the electric motor, while the communication passage extends from the discharge passage toward the first device along the axial direction of the drive rotor.

Abstract: A compressor, which is cooled by cooling medium, includes a compression chamber, a first cooling chamber and a second cooling chamber. In the compression chamber, gas is compressed and then discharged therefrom. The first cooling chamber, in which the cooling medium flows, is provided so as to adjoin the compression chamber for cooling the gas in the compression chamber. The second cooling chamber adjoins the first cooling chamber. The second cooling chamber has a gas passage in which the discharged gas flows and a medium passage in which the cooling medium flows. The medium passage is arranged so as to restrain transmission of heat of the discharged gas in the gas passage to the cooling medium in the first cooling chamber.