| 摘要 |
PROBLEM TO BE SOLVED: To restrain lowering of a mechanical efficiency by adjusting pressure applied to an internal gear in the radial direction so that an internal gear is prevented from being pressed onto the inner circumferential surface of a housing recessed part toward the outside in the radial direction of a discharge port. SOLUTION: A groove 16 opened along the outer circumferential surface 2A of an internal gear is formed so as to be dented at one end surface of a lid member on the outer side in the radial direction of a discharge port 9(13) so that the groove 16 is communicated with the discharge port 9 through a communication groove 17. By this constitution, against action force acting on the inner circumferential surface 2B of an internal gear 2 outward in the radial direction based on the pressure of high pressure oil in the discharging area P2 of a pump chamber P, acting force based on the pressure of high pressure oil of the discharge port 9(13) to be introduced in the groove 16, acts on the outer circumferential surface 2A of the internal gear 3 inward in the radial direction, acting force based on the pressure of high pressure oil can be acted onto the internal gear 2 oppostely in the radial direction, and the internal gear 2 is prevented from being pressed onto the inner circumferential surface 4A of a housing recessed part 4 outward in the radial direction.
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