Patent ID: 8052557
Filing Date: 2011-11-08
Classification: F01L,F16H

Abstract:
1. A hydraulic auto-tensioner comprising a housing, a tensioning plunger guided in a plunger bore of said housing, a free piston guided in said plunger bore, a plunger rod formed on said tensioning plunger and extending through the free piston, a hydraulic reservoir delimited by the tensioning plunger, the housing and the free piston, and a sealing unit which is arranged on the free piston and by means of which the hydraulic reservoir is sealed with respect to the housing and the plunger rod, characterized in that the sealing unit is implemented as a double seal ring with an outer sealing surface which is in sliding contact with the plunger bore of the housing, and an inner sealing surface which is in sliding contact with the plunger rod of the tensioning plunger, wherein the double seal ring is provided with a spring means, said spring means pretensioning the outer sealing surface with respect to the plunger bore and the inner sealing surface with respect to the plunger rod.