A hydraulic tensioner having a piston sliding around an outside surface of a pin or rod, so that the high pressure chamber for chain control is created by the area between the piston internal diameter and the rod outside diameter. A spring around the outside of the rod presses against the bottom of the piston, biasing the piston outward during low oil pressure conditions. Preferably, the piston is steel and the rod is aluminum, the reverse of prior art designs, which means that as temperature increases, the piston to bore clearance reduces. This can offset the oil viscosity reduction and maintain the same performance over operating temperatures.

A tensioning device, more particularly a hydraulically actuated chain tensioner, for a chain drive of an internal combustion engine, having a tensioner housing, a tensioning piston which is displaceably guided in a piston bore of the tensioner housing and has a piston skirt, a transport securing means for fastening the tensioning piston in the tensioner housing, a adjustment apparatus for incrementally adjusting and limiting the working range of the tensioning piston, and a final position securing means for the captive arrangement of the tensioning piston in the piston bore. The transport securing means, the adjustment apparatus and the final position securing means together have a single securing ring for fastening the tensioning piston in the tensioner housing, the incremental adjustment and limiting of the working range of the tensioning piston and the captive arrangement of the tensioning piston. A chain drive, more particularly a control chain drive, of an internal combustion engine, having such a tensioning device is also provided.

A variable force tensioner (VFT) system that includes a primary piston split into two chambers disposed within a primary bore. The two chambers including a first low pressure chamber having a primary reservoir therein that feeds fluid through a check valve into a second high pressure chamber to control a biasing force on the primary piston. A piston bore clearance path can extend along a groove in the primary bore to feed oil back to the primary reservoir from the high pressure chamber.

A tensioner for tensioning a chain span which uses two pistons. The movement of the two pistons may be coupled together. The first piston provides damping to the chain span and a second piston provides variable, dominant and automatically adjusting spring force to the chain span. The tensioner automatically adjusts the mean tension force to keep the chain tension as low as possible without sacrificing chain control, significantly improving drive efficiency at new chain conditions and conditions with dynamic loads.

A chain tensioner includes a sleeve fixedly disposed in a cylinder, with a first end of the sleeve inserted in a plunger and a second end of the sleeve protruding out of the plunger. A cylindrical space is defined between an outer periphery of the sleeve and an inner periphery of the cylinder. An oil supply passage opens to the cylindrical space. A communication passage is defined in the sleeve and provides communication between the cylindrical space and a reservoir chamber.

To provide a tensioner that can keep the oil pressure in an oil pressure chamber stable and consistently generate suitable reaction force and damping force to impact loads to reduce looseness in the chain and noise. A piston is set such as to partition an inner space of a plunger into an adjustment space on the front side and the oil pressure chamber on the rear side, a piston restricting member restricting the movement of the piston toward the adjustment space. An oil relief mechanism is configured to cause the piston to move forward when oil pressure in the oil pressure chamber rises so as to discharge oil inside the oil pressure chamber to the outside. The piston restricting member has an orifice function that can control the amount of discharged oil.

The present invention provides a chain tensioner that automatically adjusts flow path resistance inside an oil leak path with a simple configuration to make it possible to reduce a change in damping characteristics resulting from a change in oil temperature and reduce an increase in manufacturing cost. In the chain tensioner, a pressure oil chamber is provided with an oil leak path communicating with an outside of the chain tensioner, the oil leak path contains a movable piece which is movable with a temperature-dependent deformation member that deforms according to oil temperature, and the movable piece is formed into a shape that changes flow path resistance of the oil leak path according to a position to which the movable piece is moved.

To provide a chain tensioner that can suppress oil leakage from a gap between a plunger bore and a plunger to achieve stable damping characteristics and that can avoid an increase in production cost, with a simple structure. The chain tensioner includes a packing member that is provided on an inner circumferential side of the plunger bore and that suppresses oil leakage from a cylindrical outer surface of the plunger. The plunger is provided with an oil leak passage that extends from an oil pressure chamber inside the plunger to the outside.

To provide a tensioner that has a simple structure and is easy to assemble, and is configured to smoothly relieve pressure during oil release with reduced flow resistance so that the oil pressure in an oil pressure chamber is kept stable in a favorable manner. A relief valve unit includes a cap member that fits with a seat member to retain a stopper member inside the seat member. An external relief hole, which causes a relief-side space in a plunger hole to communicate with the outside of a plunger, opens radially in an outer circumferential surface of the plunger.

An integrated valve for a hydraulic tensioner includes a pressure relief valve with an integrated band, which is preferably made of metal, placed around the outside of a pressure relief valve body. A hydraulic tensioner includes a housing with a bore and a hollow piston slidably received within the bore. A piston spring biases the piston in a direction toward a power transmission device. The tensioner also includes an integrated check valve in a body of the housing. The integrated check valve includes a pressure relief valve mechanism and a band check valve mechanism surrounding a circumference of the pressure relief valve mechanism. The pressure relief valve mechanism permits transfer of pressurized fluid from a piston chamber formed by the hollow piston to the source of pressurized fluid and the check valve mechanism permits transfer of pressurized fluid from the source of pressurized fluid to the piston chamber.