The screw compressor includes a first-stage compressor main body and a second-stage compressor main body for compressing fluid with screw rotors, a motor for driving the first-stage compressor main body and the second-stage compressor main body, and a gear box. The gear box is connected to the first-stage compressor main body, the second-stage compressor main body, and the motor; transmits a driving force of the motor to the screw rotors, and includes a first attachment hole for attaching the first-stage compressor main body and a second attachment hole for attaching the second-stage compressor main body; and is provided with an annular rib surrounding both of the first attachment hole and the second attachment hole. In the screw compressor, the vibration of the natural vibration mode which is most burdensome and should be reduced can be efficiently reduced.

An electrically operated device (10) includes an electric motor (36) with an electrical cord set (30). The cord set (30) includes an electrical connecting plug (80) for coupling with an AC electrical outlet. The device (10) further includes a detector (46). A control (42) is electrically coupled to the motor (36) and electrically coupled to the detector (46) for controlling the level of electric current drawn by the electric motor (36) from the AC electrical outlet. The detector (46) detects whether the electrical connecting plug (80) is connected to a 15 Amp electric receptacle or to a 20 Amp electric receptacle and, in response, the control (42) establishes the electric profile of the electric motor (36) to correspond to the 15 Amp electric receptacle or to the 20 Amp electric receptacle.

Power systems and methods of controlling an engine driven air compressor include an air compressor driven by an engine via a clutch. A first pressure sensor configured to sense a pressure level at an outlet of the air compressor. An inlet valve configured to close in response to the first pressure sensor sensing a pressure level above a first pressure level. In addition, a second pressure sensor to sense a pressure level below a second pressure level at a housing of the air compressor, wherein the clutch is configured to disengage in response to the second pressure level, wherein the first pressure level is higher than the second pressure level.

A technique is provided that can further reduce power at the time of unload operation control in a gas compressor that generates a compressed gas at a set pressure by constant-speed control. The gas compressor includes a compressor main unit, a drive source, an intake throttle valve, a gas release valve, rotation speed converting means, a pressure detecting device that detects a discharge pressure, and a controller that, the relationship between an upper-limit pressure H and a lower-limit pressure L being H>L, carries out opening the intake throttle valve and closing the gas release valve and operating the drive source at a full-load rotation speed until the discharge pressure reaches the upper-limit pressure H. The controller carries out at least one of closing the intake throttle valve and opening the gas release valve to reduce the discharge pressure to within a predetermined range when the discharge pressure reaches the upper-limit pressure H. The controller carries out switching to load operation when the discharge pressure drops to the lower-limit pressure L. In the gas compressor, the controller outputs a command of a lower rotation speed than the full-load rotation speed to the rotation speed converting means when the discharge pressure rises and reaches the upper-limit pressure H. The controller outputs a command of the full-load rotation speed to the rotation speed converting means when the discharge pressure drops and reaches the lower-limit pressure L.

A screw compressor for a utility vehicle has at least one housing with at least one housing cover and with at least one rotor housing, at least one baffle plate and at least one seal. In the assembled state, an oil sump is present in the housing, wherein, with regard to the assembled state, the seal is arranged between housing cover and rotor housing and projects out of the oil sump. The seal at least partially separates the interior of the housing cover from the interior of the rotor housing. With regard to the assembled state, in the case of a substantially horizontal orientation of the screw-type compressor and in the case of a substantially horizontal orientation of the oil sump, the baffle plate is oriented substantially parallel to the upper level of the oil sump.

A gas ejection apparatus includes: a cylinder having a rotating member that rotates within the cylinder; a motor coupled to the rotating member of the cylinder and that causes gas to be compressed inside the cylinder and to be ejected from the cylinder by causing rotation of the rotating member; a control circuit board that controls the motor; and a case in which the cylinder, the motor and the control circuit board are disposed. The case extends in a planar direction and has side surfaces that are orthogonal to the planar direction. The motor and the cylinder are arranged adjacent to each other in the planar direction of the case. The control circuit board is disposed adjacent to and substantially parallel to one of the side surfaces of the case.

An epitrochoidal vacuum pump includes a housing having a chamber, a rotor rotatably received within the internal space of the chamber, and a drive shaft configured to rotate the rotor eccentrically about an axis within the chamber in an epitrochoidal manner. An externally toothed guide sprocket meshes with and guides movement of a guide gear of the rotor as it is driven by the drive shaft. A chamber inlet draws air under negative pressure into the housing, and an outlet is provided to expulse air under positive pressure from the housing. Further, a fluid inlet is provided to input lubricant along the drive shaft and into the internal space of the chamber. The fluid inlet is communicated by channel(s) in an interior of the housing. The lubricant is drawn into the housing via a pressure differential.

An air pump system includes a housing defining a first vent in fluid communication with an interior cavity of an inflatable member, a first one-way valve configured to open or close the first vent, a main pump having a main pump inlet and a main pump outlet, a valve control assembly for selectively opening or closing the one-way valve, an air pressure control assembly for sensing an air pressure of the interior cavity and generating a first air pressure signal when the air pressure reaches a first threshold air pressure, and generating a second air pressure signal when the air pressure reaches a second threshold air pressure, and a control device in electrical communication with the main pump, valve control assembly and the air pressure control assembly.

A water lubrication air compression system disposes an lubricant heat dissipation system at a bearing chamber close to the high pressure end of the compressor for cooling and circulating lubricant due to the rise of temperature during operation of the compressor, hence enhancing the ability and stability of the compressor. On the other hand, a negative pressure system is connected to the air chambers between the oil lubrication and the water lubrication of the compressor in order to provide a negative pressure. If any leak of water vapor at the compressor chamber or oil vapor at the bearing chamber, the negative pressure system is able to produce a negative pressured condition toward the sealing structure so that the oil lubrication can be effectively isolated from the water lubrication and inter-contamination between the lubricant and water can be avoided.

A rotation device according to an embodiment includes a first gear, a second gear, and an energizing part. The first gear includes a toothless part and is connected with a rotation driving source. The toothless part is obtained by cutting a part of continuous teeth of the first gear. The second gear is arranged to be able to be engaged with the first gear and is rotated, when engaged with the first gear, in a predetermined direction by a rotation of the rotation driving source in one direction. The energizing part energizes the second gear in a direction reverse to the predetermined direction when the second gear is in a free state in which an engagement of the second gear with the first gear is released by the toothless part.