Abstract: In order to realize cost reduction in a gear pump apparatus by reducing form accuracy of a gear while securing pump performance, a running-in coating is provided on a tooth sliding contact portion when forming a confinement area in at least one of gears of the gear pump apparatus. By this feature, the running-in coating is gradually worn away and deformed according to rotary drive of the pump, and thus it is possible to obtain an optimal gear form in meshing combinations of the gears. Further, it is possible to reduce leakage inside the pump to secure the pump performance even if the form accuracy of the gear is reduced for the sake of the cost reduction.

Abstract: An oil pump including a first housing having a rotation shaft insertion hole, a cam ring, a pump element, a rotation shaft rotatably extending through the rotation shaft insertion hole, a second housing disposed on the cam ring, wherein the cam ring is placed in a position relative to the rotation shaft insertion hole of the first housing by using a jig, and the cam ring includes a clamped portion that is clamped by a cam ring holding device, while the first housing and the second housing are fixed to each other after placing the cam ring in the position relative to the rotation shaft insertion hole by using the jig. Alternatively, the oil pump including a fixing means for fixing the cam ring to the pump body instead of the clamped portion.

Abstract: An oil pump is provided which includes a cam ring made of a material having a first line expansion coefficient, a pump element rotatably disposed in the cam ring and smaller in an axial length than the cam ring, a first housing member disposed on one of axially opposite sides of the cam ring and made of a material having a second line expansion coefficient larger than the first line expansion coefficient, and a second housing member disposed on the other of the axially opposite sides of the cam ring and made of a material having a third line expansion coefficient than the first line expansion coefficient.

Abstract: In order to realize cost reduction in a gear pump apparatus by reducing form accuracy of a gear while securing pump performance, a running-in coating is provided on a tooth sliding contact portion when forming a confinement area in at least one of gears of the gear pump apparatus. By this feature, the running-in coating is gradually worn away and deformed according to rotary drive of the pump, and thus it is possible to obtain an optimal gear form in meshing combinations of the gears. Further, it is possible to reduce leakage inside the pump to secure the pump performance even if the form accuracy of the gear is reduced for the sake of the cost reduction.

Abstract: In a pump device applicable to a power steering apparatus, a pump element is housed within a pump housing and is configured to drain a working oil, an electric motor is configured to drive the pump element, a reservoir tank is installed on the housing and is configured to reserve the working oil supplied to the oil element, a passage is formed within the pump housing and is connected to the pump element, and a control valve is installed in the pump housing, is configured to communicate with the passage, and is configured to control a flow of the working oil caused to flow through the passage.

Abstract: A trochoid pump for supplying hydraulic fluid to a power cylinder in a power steering system. The trochoid pump includes a housing formed therein with an annular operating chamber. Outer rotor having internal teeth and inner rotor having external teeth are rotatably accommodated in the operating chamber in such a manner that the internal and external teeth are engageable with each other. A driving shaft is provided for rotationally driving the inner rotor. A low pressure passage is opened to a clearance between an outer peripheral surface of the outer rotor and an inner peripheral surface of the operating chamber within a discharge region at side of an engaging section at which the volume of the pump chamber is the minimum so as to release a high pressure applied to the outer peripheral surface of the outer rotor, to a low pressure side.

Abstract: An oil pump is provided which includes a cam ring made of a material having a first line expansion coefficient, a pump element rotatably disposed in the cam ring and smaller in an axial length than the cam ring, a first housing member disposed on one of axially opposite sides of the cam ring and made of a material having a second line expansion coefficient larger than the first line expansion coefficient, and a second housing member disposed on the other of the axially opposite sides of the cam ring and made of a material having a third line expansion coefficient than the first line expansion coefficient.