Abstract: An internal gear pump includes: an internal gear rotatably fitted in a body; an external gear inscribed in and meshed with the internal gear; a filler piece that partitions a liquid feeding space formed between the internal gear and the external gear into a high pressure region and a low pressure region; and a sealing member that covers both end surfaces of both the gears in a rotation axis direction and seals the liquid feeding space, in which a communication groove for communicating an enclosed space surrounded by the filler piece and a tooth groove of at least one of the gears with the high pressure region is formed, and the communication groove is formed such that a cross-sectional area communicating with the enclosed space continuously increases and an increase rate thereof acceleratively increases as a rotation phase of both the gears advances.

Abstract: An internal gear pump includes: an internal gear rotatably fitted in a body; an external gear inscribed in and meshed with the internal gear; a filler piece that partitions a liquid feeding space formed between the internal gear and the external gear into a high pressure region and a low pressure region; and a sealing member that covers both end surfaces of both the gears in a rotation axis direction and seals the liquid feeding space, in which a communication groove for communicating an enclosed space surrounded by the filler piece and a tooth groove of at least one of the gears with the high pressure region is formed, and the communication groove is formed such that a cross-sectional area communicating with the enclosed space continuously increases and an increase rate thereof acceleratively increases as a rotation phase of both the gears advances.

Abstract: A gear pump or a gear motor in which a tooth groove is easily filled with a liquid. A gear pump includes a casing, a gear storage chamber, a suction passage, a discharge passage, a gear that is housed in the gear storage chamber and including a drive gear and a driven gear that rotate while meshing with each other, and a suction-side communication path that connects a first space and a tooth groove of the gear, the first space being a closed space formed by the drive gear and the driven gear meshing with each other, the tooth groove being opened to the suction passage.

Abstract: A dual phase difference pump 100 that can reduce the pulsation of a discharge pressure as much as possible. The dual phase difference pump 100 includes, in series, two gear pump units 1, 2 each including a pair of gears 4, 5 configured to mesh with each other. Shafts 42 of the gear pump units 1, 2 are coupled to each other by using a coupler 6. The pair of gears 4, 5 mesh with each other without backlash. The coupler 6 is configured to couple the shafts 42 to each other at any one of a plurality of predetermined phase angles, and is configured to make a phase difference between the gear pump units 1, 2 equal irrespective of which predetermined phase angle is selected among the plurality of predetermined phase angles as a phase angle at which the shafts 42 are coupled to each other.

Abstract: A gear pump or a gear motor in which a tooth groove is easily filled with a liquid. A gear pump includes a casing, a gear storage chamber, a suction passage, a discharge passage, a gear that is housed in the gear storage chamber and including a drive gear and a driven gear that rotate while meshing with each other, and a suction-side communication path that connects a first space and a tooth groove of the gear, the first space being a closed space formed by the drive gear and the driven gear meshing with each other, the tooth groove being opened to the suction passage.