A dry type primary vacuum pump is provided, including at least two pumping stages mounted in series between a suction and a discharge of the pump; two rotors extending in the pumping stages and being configured to rotate synchronously in a reverse direction to drive a gas to be pumped between the suction and the discharge; an injection device configured to distribute a purge gas in at least one pumping stage, the injection device including at least one injector and at least one injection valve with an on or off control configured to be interposed between a purge gas supply source and the injector; and a control device configured to control opening and closing of the injection valve to inject a purge gas by successive pulses into the at least one pumping stage. A method for controlling the injection of a purge gas the vacuum pump is also provided.

A gas ejection apparatus ejects gas using a compressor that compresses the gas by a rotating body inside a cylinder, and includes a detector and a microcomputer. The detector detects a position of the rotating body inside the cylinder based on positions of gears which are coupled to the rotating body. When the microcomputer receives an ejection instruction, the microcomputer controls intake and exhaust of the compressor according to detection results of the detector, and causes the compressor to wait in an intake completion state upon completion of ejection of the gas that was performed in response to the ejection instruction.

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.

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.

A dry type primary vacuum pump is provided, including at least two pumping stages mounted in series between a suction and a discharge of the pump; two rotors extending in the pumping stages and being configured to rotate synchronously in a reverse direction to drive a gas to be pumped between the suction and the discharge; an injection device configured to distribute a purge gas in at least one pumping stage, the injection device including at least one injector and at least one injection valve with an on or off control configured to be interposed between a purge gas supply source and the injector; and a control device configured to control opening and closing of the injection valve to inject a purge gas by successive pulses into the at least one pumping stage. A method for controlling the injection of a purge gas the vacuum pump is also provided.

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 he 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.

A gas ejection apparatus ejects gas using a compressor that compresses the gas by a rotating body inside a cylinder, and includes a detector and a microcomputer. The detector detects a position of the rotating body inside the cylinder based on positions of gears which are coupled to the rotating body. When the microcomputer receives an ejection instruction, the microcomputer controls intake and exhaust of the compressor according to detection results of the detector, and causes the compressor to wait in an intake completion state upon completion of ejection of the gas that was performed in response to the ejection instruction.

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.