Abstract: This invention pertains to the field of hydraulic tensioners. A hydraulic tensioner of this invention includes a tensioner body having a bore in fluid communication with a source of pressurized fluid through an inlet, a hollow piston slidably received within the bore and having an outer diameter, a hydraulic pressure chamber defined by the hollow piston and the bore of the tensioner body, a piston spring received within the hydraulic pressure chamber for biasing the piston away from the inlet, and a metallic band surrounding the outer diameter of the piston. The metallic band forms a seal between an outer surface of the piston and the tensioner body when pressure builds in the hydraulic pressure chamber, wherein metallic bands or seals are placed over a hydraulic tensioner piston in order to seal the high pressure chamber and prevent or reduce leakage through the clearance between the piston and the tensioner body.

Abstract: A hydraulic tensioner includes a valve seat, first valve member, retainer, and second valve member. The seat includes a first aperture disposed about an axis and a second aperture radially outward thereof. The first member includes a first plate having a third aperture aligned with the first aperture. The first plate extends radially outward of the second aperture. The first plate is axially movable between a closed position wherein it inhibits flow through the second aperture, and an open position wherein it permits flow through the second aperture. The retainer includes a second plate fixed relative to the seat. The second member includes a third plate between the second plate and valve seat. The third plate is axially movable between a closed position wherein it inhibits flow through the first aperture while permitting flow through the second aperture, and an open position wherein it permits flow through the first aperture.

Abstract: A hydraulic tensioner can include a valve retainer and valve member within a housing including a cavity, passageway, and boss. The passageway provides fluid communication with the cavity through an end face of the cavity. The boss is disposed about the passageway and extends axially outward from the end face. The valve retainer can include a first plate. The first plate can be fixedly coupled to the housing. The valve member can include a second plate that can be axially between the first plate and the boss. The second plate can extend in a radial direction beyond an outermost edge of the boss. The second plate can move axially between a closed position wherein the second plate is in sealing contact with the boss and an open position wherein the second plate is axially spaced apart from the boss. The valve spring biases the second plate toward the closed position.

Abstract: A hydraulic tensioner for an internal combustion engine for tensioning a span of a chain or a belt has a piston with an internal reservoir connected to a high pressure chamber through a check valve assembly. The check valve assembly has a disk seat received within the hollow bore of the body of the piston having at least one passage connecting the internal reservoir to the hydraulic pressure chamber; a check valve retainer coupled to the disk seat; a check valve disk received between the disk seat and the check valve retainer moveable between a first position and a second position, and a check valve spring received between the check valve disk and the check valve retainer.