Patent ID: 8371973
Filing Date: 2013-02-12
Classification: F16H

Abstract:
1. A chain tensioner comprising: a cylindrical cylinder having an open end and a bottom; a cylindrical plunger axially slidably inserted in said cylinder, and having a bottom and an open end located in said cylinder; and a screw rod mounted in said cylinder and having an external thread on an outer periphery thereof, wherein said plunger has a protrusion on an inner periphery thereof which is in threaded engagement with said external thread of said screw rod, wherein said external thread has a pressure flank configured to receive pressure when a force is applied that pushes said plunger into said cylinder, and a clearance flank, said pressure flank having a larger flank angle than said clearance flank, whereby said external thread is serration-shaped, and a return spring mounted between said plunger and said screw rod and biasing said plunger in a direction to protrude from said cylinder, thereby pressing a chain with said plunger, and wherein said protrusion extends circumferentially less than an entire circumference of said inner periphery of said plunger.