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 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.

Abstract: A hydraulic tensioner for applying tension to a chain comprising a housing, a hollow piston, a spring, and a pawl. The housing has a cylindrical bore and pawl hole. The hollow piston has rack teeth along its length and is slidably received by the bore. The piston and the bore define a fluid chamber within the bore. A spring biases the piston in a protruding direction from the bore. A pawl, received by the pawl hole of the housing has a front surface, a rear surface, and a tooth section biased to engage the rack teeth of the piston by a pawl spring in a pawl spring accommodating section of the pawl hole. A clearance is present between the pawl hole and the front surface and the rear surface of the pawl, to allow longitudinal travel of the pawl.

Abstract: A hydraulic tensioner that applies tension to a chain is comprised of a hollow plunger slidably received in a bore of the housing having an inner space defining a fluid chamber with the bore and a rack member provided slidably in an axial direction in a groove on the outer circumference of the plunger. The hydraulic tensioner further comprises a spring biasing the plunger in a protruding direction, a ratchet member provided slidably in a ratchet hole extending in an inclined direction intersecting an axis of the plunger having cylindrical head portion with an outer circumferential edge portion adapted to engage rack teeth of the rack member, permitting travel of the plunger in a protruding direction but preventing retraction of the plunger in a backward direction, and a coil spring that biases the ratchet member in an engaging direction of the rack teeth.

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 hydraulic tensioner includes a housing with a piston bore. A hollow piston with rack teeth on an outer circumference is inserted slidably in the piston bore, forming a fluid chamber. A piston spring urges the piston to extend. A retraction blocking member such as a pawl is provided in a retraction blocking member opening. The pawl has teeth engageable with the piston rack teeth, and a pawl spring that urges the teeth of the pawl member to engage the rack teeth. The width of the pawl member is greater than the width of the tip portion of the rack teeth of the piston. In one embodiment, a pawl retainer is mounted at a retainer hole and houses the pawl. In this embodiment, the width of the axial portion of the pawl retainer is greater than the width of the tip portion of the rack teeth of the piston.

Abstract: A hydraulic tensioner that decreases the number of components, secures an adequate backlash, and prevents backward movement of a plunger. The hydraulic tensioner includes a hollow plunger having rack teeth formed on a portion of an outer circumferential surface, slidably received in a bore of the housing, where the plunger has an inner space to form a fluid chamber with the bore. A slider housing portion, having an inclined surface, located in the housing, receives a wedge-shaped slider having a ratchet portion adapted to engage with the rack teeth of the plunger and a second side surface. The wedge-shaped slider being slidable along the inclined surface of the slider housing portion in a direction crossing an axial centerline of the plunger. The hydraulic tensioner further includes a first spring biasing the plunger in a protruding direction, and a second spring biasing the slider such that the slider moves along the inclined slide surface of the slider housing portion.

Abstract: A hydraulic tensioner comprising a hollow plunger having rack teeth formed on a portion of an outer circumferential surface, slidably received in a bore of the housing, where the plunger has an inner space to form a fluid chamber with the bore. A slider housing portion, having an inclined surface, located in the housing, receives a wedge-shaped slider having a ratchet portion adapted to engage with the rack teeth of the plunger and a second side surface. The wedge-shaped slider being slidable along the inclined surface of the slider housing portion in a direction crossing an axial centerline of the plunger. The hydraulic tensioner further includes a first spring biasing the plunger in a protruding direction, and a second spring biasing the slider such that the slider moves along the inclined slide surface of the slider housing portion. A “wedge-effect” prevents the plunger from moving backwards.

Abstract: The present invention provides a hydraulic tensioner with a ratchet mechanism simple in structure. The hydraulic tensioner (1) includes a hollow plunger (3) that is slidably received in a bore (2a) of the housing (2) that has an inner space (3a) defining a fluid chamber (20) with the bore (2a) and a rack member (7) provided slidably in axial direction in a groove (3b) on an outer circumference of the plunger (3).

Abstract: A hydraulic tensioner that decreases the number of components, secures an adequate backlash, and prevents backward movement of a plunger. The hydraulic tensioner includes a hollow plunger having rack teeth formed on a portion of an outer circumferential surface, slidably received in a bore of the housing, where the plunger has an inner space to form a fluid chamber with the bore. A slider housing portion, having an inclined surface, located in the housing, receives a wedge-shaped slider having a ratchet portion adapted to engage with the rack teeth of the plunger and a second side surface. The wedge-shaped slider being slidable along the inclined surface of the slider housing portion in a direction crossing an axial centerline of the plunger. The hydraulic tensioner further includes a first spring biasing the plunger in a protruding direction, and a second spring biasing the slider such that the slider moves along the inclined slide surface of the slider housing portion.