Abstract: A tensioner uses a low rate torsion spring in a first stage and a high rate torsion spring in a second stage to maintain tension in a chain or belt. The first stage is connected to the second stage by a torque coupling. The high rate torsion spring is maintained in an energized state between a ground and a dead stop to store energy and to provide tension under high loads. In some embodiments, the torque coupling is a damper. In other embodiments, the torque coupling is a clutch. A method stores energy in a high rate torsion spring of a tensioner.

Abstract: A tensioner uses a low rate torsion spring in a first stage and a high rate torsion spring in a second stage to maintain tension in a chain or belt. The first stage is connected to the second stage by a torque coupling. The high rate torsion spring is maintained in an energized state between a ground and a dead stop to store energy and to provide tension under high loads. In some embodiments, the torque coupling is a damper. In other embodiments, the torque coupling is a clutch. A method stores energy in a high rate torsion spring of a tensioner.

Abstract: A tensioner comprising a piston slidably received within a piston bore of the housing having a plurality of grooves formed on an outer circumference, the piston forming a first pressure chamber with the piston bore. The tensioner uses a mechanism to remove a sliding pawl or expandable clip from engaging the grooves on the piston, such that the piston can move towards the housing and reduce chain load when fluid pressure is reduced in the first pressure chamber during engine shutdown, but not so much as to leave the chain uncontrolled during engine restart. The mechanism may for example be a fluid biased spool piston which engages the expandable clip or a pawl piston that engages a sliding pawl.

Abstract: A tensioner comprising a piston slidably received within a piston bore of the housing having a plurality of grooves formed on an outer circumference, the piston forming a first pressure chamber with the piston bore. The tensioner uses a mechanism to remove a sliding pawl or expandable clip from engaging the grooves on the piston, such that the piston can move towards the housing and reduce chain load when fluid pressure is reduced in the first pressure chamber during engine shutdown, but not so much as to leave the chain uncontrolled during engine restart. The mechanism may for example be a fluid biased spool piston which engages the expandable clip or a pawl piston that engages a sliding pawl.

Abstract: A tensioner comprising a piston slidably received within a piston bore of the housing having a plurality of grooves formed on an outer circumference, the piston forming a first pressure chamber with the piston bore. The tensioner uses a mechanism to remove a sliding pawl or expandable clip from engaging the grooves on the piston, such that the piston can move towards the housing and reduce chain load when fluid pressure is reduced in the first pressure chamber during engine shutdown, but not so much as to leave the chain uncontrolled during engine restart. The mechanism may for example be a fluid biased spool piston which engages the expandable clip or a pawl piston that engages a sliding pawl.

Abstract: An apparatus (10) for imparting tension to strands of an endless power transferring member loop (12) encircling a drive sprocket (14) and at least one driven sprocket (16 a, 16b). Two tensioning arms (38a, 18b) are spaced apart and have guided movement relative to at least one fixed pin (26) with a tension driver (5) operably engaged with one of the tensioning arms (18a, 18b) for driving both tensioning arms (18a, 18b) in motion acting through a rotatable, motion transfer body (34) located generally centrally with respect to the endless loop power transferring member (12) for connection to corresponding motion transfer locations (30a, 30b) associated with the pair of tensioning arms (18a, 18b), either directly or indirectly. A link assembly (60) can connect first ends (40a, 40b) to the motion transfer body (34) and second locations (42a, 42b) to corresponding opposite ends of the two spaced apart tensioning arms (38a, 18b).

Abstract: A tensioner comprising a piston slidably received within a piston bore of the housing having a plurality of grooves formed on an outer circumference, the piston forming a first pressure chamber with the piston bore. The tensioner uses a mechanism to remove a sliding pawl or expandable clip from engaging the grooves on the piston, such that the piston can move towards the housing and reduce chain load when fluid pressure is reduced in the first pressure chamber during engine shutdown, but not so much as to leave the chain uncontrolled during engine restart. The mechanism may for example be a fluid biased spool piston which engages the expandable clip or a pawl piston that engages a sliding pawl.

Abstract: An apparatus (10) for imparting tension to strands of an endless power transferring member loop (12) encircling a drive sprocket (14) and at least one driven sprocket (16a, 16b). Two tensioning arms (38a, 18b) are spaced apart and have guided movement relative to at least one fixed pin (26) with a tension driver (5) operably engaged with one of the tensioning arms (18a, 18b) for driving both tensioning arms (18a, 18b) in motion acting through a rotatable, motion transfer body (34) located generally centrally with respect to the endless loop power transferring member (12) for connection to corresponding motion transfer locations (30a, 30b) associated with the pair of tensioning arms (18a, 18b), either directly or indirectly. A link assembly (60) can connect first ends (40a, 40b) to the motion transfer body (34) and second locations (42a, 42b) to corresponding opposite ends of the two spaced apart tensioning arms (38a, 18b).

Abstract: The present invention is directed to decrease the impact sound of the ratchet mechanism generated at the time of piston retraction. The tensioner includes a piston 3 slidable in the piston bore 2a of the housing 2 and an expandable circlip member 5 engageable with the engagement groove 3a of the piston 3. The piston bore 2a has a guide groove 20 formed therein that has front and rear stop surfaces 20a, 20b adapted to contact the circlip member 5. The engagement groove 3a is formed by a round seat portion S0 that the circlip member 5 is adapted to seat, a piston-retraction restricting portion S0S1 that is formed on the front side of the round scat portion S0 and a piston-advance permitting portion S0S2 that is formed on the front side of the round seat portion S0.

Abstract: The present invention is directed to decrease the impact sound of the ratchet mechanism generated at the time of piston retraction. The tensioner includes a piston 3 slidable in the piston bore 2a of the housing 2 and an expandable circlip member 5 engageable with the engagement groove 3a of the piston 3. The piston bore 2a has a guide groove 20 formed therein that has front and rear stop surfaces 20a, 20b adapted to contact the circlip member 5. The engagement groove 3a is formed by a round seat portion S0 that the circlip member 5 is adapted to seat, a piston-retraction restricting portion S0S1 that is formed on front side of the round scat portion S0 and a piston-advance permitting portion S0S2 that is formed on the front side of the round seat portion S0.

Abstract: A hydraulic tensioner comprising a piston slidably inserted in a piston bore of a housing having rack teeth on an outer circumference thereof, a piston spring biasing the piston in a protruding direction, a pawl member having teeth engageable with the rack teeth of the piston to permit protruding movement of the piston but to block reverse movement of the piston provided in a pawl hole of the housing, and a pawl spring in a pawl spring hole of a generally elliptical cross-section that biases the pawl member in an engaging direction of the teeth of the pawl member with the rack teeth of the piston. A long axis of the generally elliptical cross-sectional shape of the pawl spring is oriented toward an axial direction of the piston. Wire portions of the pawl spring substantially follow the long axis that contacts an upper surface of the pawl member.

Abstract: A tensioner that includes a piston supported slidably in a piston bore formed in a housing, a piston spring biasing the piston in the protruding direction, and a circlip member having an expandable ring-shaped body that is engageable with the rack teeth of the piston. In the piston bore, the ring-shaped body of the circlip member is adapted to engage with an upper and lower stop surface. The rack teeth of the piston are formed in such a shape that when the ring-shaped body of the circlip member engages with the upper stop surface of the piston bore, the piston is permitted to move in the protruding direction and, when the ring-shaped body of the circlip member engages with the lower stop surface of the piston bore, the piston restricts movement in the retracting direction.

Abstract: A tensioner that includes a piston supported slidably in a piston bore formed in a housing, a piston spring biasing the piston in the protruding direction, and a circlip member having an expandable ring-shaped body that is engageable with the rack teeth of the piston. In the piston bore, the ring-shaped body of the circlip member is adapted to engage with an upper and lower stop surface. The rack teeth of the piston are formed in such a shape that when the ring-shaped body of the circlip member engages with the upper stop surface of the piston bore, the piston is permitted to move in the protruding direction and, when the ring-shaped body of the circlip member engages with the lower stop surface of the piston bore, the piston restricts movement in the retracting direction.

Abstract: A tensioning device to impart tension to a chain or belt comprising a tensioner arm, a supporting member, a pivot, and a biasing element. The tensioner arm has a proximal end with a curved engaged surface formed on a lower surface thereof, a distal end opposite the proximal end, and an arcuately curved chain sliding surface extending between the proximal end and the distal end. The supporting member has an engaging surface for slidably contacting the engaged surface of the proximal end of the tensioner arm, such that the force exerted by a chain passing over the chain sliding surface is transmitted from the engaged surface to the engaging surface. The pivot couples the tensioner arm to the supporting member. The biasing element is between the supporting member and imparts a resilient force on the distal end of the tensioner arm.

Abstract: A hydraulic tensioner comprising a piston slidably inserted in a piston bore of a housing having rack teeth on an outer circumference thereof, a piston spring biasing the piston in a protruding direction, a pawl member having teeth engageable with the rack teeth of the piston to permit protruding movement of the piston but to block reverse movement of the piston provided in a pawl hole of the housing, and a pawl spring in a pawl spring hole of a generally elliptical cross-section that biases the pawl member in an engaging direction of the teeth of the pawl member with the rack teeth of the piston. A long axis of the generally elliptical cross-sectional shape of the pawl spring is oriented toward an axial direction of the piston. Wire portions of the pawl spring substantially follow the long axis that contacts an upper surface of the pawl member.