Patent ID: 9080641
Filing Date: 2015-07-14
Classification: F16H

Abstract:
1. A tensioner comprising: a housing having a plunger-accommodating hole having a cylindrical wall and a central axis; a hollow plunger located partly within said plunger-accommodating hole and protruding from said hole, said plunger having a closed front end wall located outside said plunger-accommodating hole for engagement with a movable guide for guiding a traveling transmission medium, said plunger being slidable in said hole along said central axis in an advancing direction to a fully advanced position and in a setback direction opposite to said advancing direction; and means for biasing the plunger in the advancing direction; wherein the plunger has a rear end wall located within the plunger-accommodating hole, said rear end wall comprising an inner circumferential surface and an outer circumferential surface, and a cylindrical side wall located between the front and rear end walls and a central axis about which the cylindrical side wall is symmetrical; wherein the cylindrical side wall has an outer circumferential surface including a sliding contact surface that comes into sliding contact with the cylindrical wall of the plunger-accommodating hole, and an inner circumferential surface; wherein substantially the entirety of the side wall and front end wall has a uniform thickness resulting from formation of the plunger by deep drawing; wherein said rear end wall meets the cylindrical side wall, and the outer circumferential and inner circumferential surfaces of the rear end wall meet the respective outer and inner circumferential surfaces of the side wall at a boundary, and the outer and inner circumferential surfaces of the rear end wall extend both rearward and inward from said boundary toward the central axis of the plunger; wherein a radial gap between the side wall of the plunger and the wall of the plunger-accommodating hole permits the plunger to become inclined so that the central axis of the plunger is inclined in relation to the central axis of the plunger-accommodating hole; wherein the inclination of the plunger can reach a maximum angle when the plunger is in its fully advanced position; and wherein said maximum angle is substantially equal to an angle, formed in a plane in which the central axis of the plunger accommodating hole lies, between an intersection of said plane with said sliding contact surface and a line in said plane tangent to said outer circumferential surface of the rear end wall at the location of said boundary.