Abstract: There is provided a chain guide that reduces a space occupied by the chain guide in an engine room while maintaining required strength, rigidity, and durability with a simple configuration, reduces the number of manufacturing steps and the waste of a material, does not require a structure that permits an error, prevents increases in vibration and noise during use, and reduces the burden of a maintenance operation. The chain guide has a guide shoe and a base member that reinforces the guide shoe, and an attachment portion includes an attachment member that is provided separately from the guide shoe and the base member and can be fixed to at least one of the guide shoe and the base member or both of the guide shoe and the base member.

Abstract: There is provided a chain guide that reduces a space occupied by the chain guide in an engine room while maintaining required strength, rigidity, and durability with a simple configuration, reduces the number of manufacturing steps and the waste of a material, does not require a structure that permits an error, prevents increases in vibration and noise during use, and reduces the burden of a maintenance operation. The chain guide has a guide shoe and a base member that reinforces the guide shoe, and an attachment portion includes an attachment member that is provided separately from the guide shoe and the base member and can be fixed to at least one of the guide shoe and the base member or both of the guide shoe and the base member.

Abstract: In a ratchet-type tensioner, a rocking ratchet pawl is released from a rack of teeth on a tensioner plunger following engine start-up by a hydraulically operated pin slidable in a pin hole and caused to protrude therefrom by oil under pressure received directly from an external oil supply, or alternatively from the tensioner's high pressure oil chamber through a passage in the tensioner housing. Optionally, an orifice can be provided within the pin hole to control flow of oil when the supply is excessive and to avoid leakage when the supply is insufficient.

Abstract: In a ratchet tensioner, a linearly moving ratchet for engagement with rack teeth on a plunger is operated a piston that is spring-biased in a direction to engage the ratchet teeth with the rack, and movable by oil pressure in a direction to disengage the ratchet teeth from the rack. The piston is located within a hole in the housing and, with that hole, forms a second high pressure oil chamber that can receive oil through an oil supply path independent of the oil supply path that carries oil to a first high pressure oil chamber formed by the plunger and the tensioner housing.

Abstract: An oil tight type chain tensioner applies tension to a chain used in an engine. The tensioner includes a housing, in which oil is sealed, and a reciprocating rod extending from the interior of the housing to the exterior for pressing the chain. An oil seal is located between the outer circumferential surface of the rod and the inner circumferential surface of the housing. A reservoir for retaining the oil is communicated with the interior of the housing. This structure permits the oil to flow between the interior of the housing and the reservoir in correspondence with the reciprocation of the rod. The reservoir has a hole for permitting air communication from the interior of the reservoir to the exterior but restricting an oil flow from the exterior of the reservoir to the interior.

Abstract: A tensioner has a tensioner body and a plunger slidably mounted in a hollow cylindrical part of the tensioner body. A plug is screwed into a female or internal screw formed from one end of the hollow cylindrical part. A coil spring is loaded in a spring accommodating hole of the plunger and in a spring accommodating hole of the plug. The coil spring is a left hand spring. On the other hand, the direction of the plug being screwed into the tensioner body is right, which is opposite to the winding direction of the coil spring. Since the direction of the plug being screwed and the winding direction of the coil spring are different, when the plug is being screwed into the tensioner body with the coil spring held between the plug and the plunger, the coil spring slides on the bottom of the spring accommodating hole of the plunger or on the bottom of the spring accommodating hole of the plug without being caught at either end.

Abstract: A plunger equipped with a relief valve mechanism is slidably mounted in a tensioner housing. The relief valve mechanism has a valve spring disposed between a valve and a spring retainer plug in a compressed condition. The spring retainer plug has a stopper surface formed on the side which opposes the valve. The maximum displacement of the valve and the maximum amount of compression of the valve spring are defined by the stopper surface so that the maximum shear stress acting in a wire of the valve spring is less than a fatigue limit of the valve spring wire.

Abstract: A closed hydraulic tensioner has a high-pressure chamber, a low-pressure chamber and a reservoir that are previously filled with an oil sealed in the hydraulic tensioner. The hydraulic tensioner further has a pressure chamber disposed next to said reservoir with a movable member disposed therebetween so as to displace the movable member toward the reservoir to thereby pressurize the oil inside the reservoir. The pressure chamber is supplied with an oil from the exterior of the tensioner.

Abstract: A tensioner has a substantially U-shaped stopper pin hooked at opposite end parts on a tensioner body and part of a plunger, respectively, to keep the plunger in a retracted position against the force of a spring before the tensioner is mounted to an engine body at an appropriate position relative to a power transmitting chain.

Abstract: A plunger equipped with a relief valve mechanism is slidably mounted in a tensioner housing. The relief valve mechanism has a valve spring disposed between a valve and a spring retainer plug in a compressed condition. The spring retainer plug has a stopper surface formed on the side which opposes the valve. The maximum displacement of the valve and the maximum amount of compression of the valve spring are defined by the stopper surface so that the maximum shear stress acting in a wire of the valve spring is less than a fatigue limit of the valve spring wire.

Abstract: A tensioner has a substantially U-shaped stopper pin hooked at opposite end parts on a tensioner body and part of a plunger, respectively, to keep the plunger in a retracted position against the force of a spring before the tensioner is mounted to an engine body at an appropriate position relative to a power transmitting chain.

Abstract: A closed hydraulic tensioner has a high-pressure chamber, a low-pressure chamber and a reservoir that are previously filled with an oil sealed in the hydraulic tensioner. The hydraulic tensioner further has a pressure chamber disposed next to said reservoir with a movable member disposed therebetween so as to displace the movable member toward the reservoir to thereby pressurize the oil inside the reservoir. The pressure chamber is supplied with an oil from the exterior of the tensioner.

Abstract: A closed hydraulic tensioner has a high-pressure chamber, a low-pressure chamber and a reservoir and contains an oil sealed in advance in the high-pressure chamber, the low-pressure chamber and the reservoir. The hydraulic tensioner further has an oil storage chamber disposed above the reservoir for holding therein an oil scattered within a chain case. The oil storage chamber communicates through an orifice with the reservoir. The hydraulic tensioner further has a bypass passage interconnecting the reservoir and the low-pressure chamber.

Abstract: A tensioner device for adjusting a tension in a chain wound around two sprockets includes a tensioner lever held in sliding contact with a slack run of the chain, an oil-filled tensioner provided on a stationary member, and a ratchet tensioner provided on the tensioner lever. The oil-filled tensioner includes a piston movable back and forth relatively to a housing attached to the stationary member, and a spring urging the piston in the forward direction. The ratchet tensioner includes a plunger movable in the forward direction relative to a housing formed integrally with the tensioner lever, and a spring urging the plunger in the forward direction. The piston and the plunger are held in face-to-face abutment with each other. The spring of the oil-filled tensioner has a larger spring coefficient than the spring of the ratchet tensioner.

Abstract: A hydraulic tensioner which has a small number of components and hence can be reduced in size. The hydraulic tensioner includes a plunger 3 slidably fitted in a cylinder disposed in a tensioner body, a reservoir chamber formed in the tensioner body in a lower portion of the cylinder, a check valve permitting flow of an oil in a single direction from the reservoir chamber into the cylinder which is formed as a high pressure chamber, a low pressure chamber formed in the tensioner body exteriorly of the cylinder, an oil passage connecting a bottom of the low pressure chamber to a position between the check valve and the reservoir chamber, and a spring urging the plunger upwardly, wherein the low pressure chamber contains an air layer formed above a surface of the oil held in the lower pressure chamber. The oil passages and check valve enable the oil to flow into the high pressure chamber in a short time and hence efficiently dampen vibrations of the plunger.

Abstract: A hydraulic tensioner 10 includes a piston rod 12 slidably fitted in a cylinder 14 with a small gap or clearance therebetween, and a housing 16 containing the cylinder 14. A ball seat 20 is press-fitted in an end of the cylinder 14 opposite to the piston rod 12 so as to define within the cylinder 14 a high pressure oil chamber 21. The housing 16 has a partition wall 26 at a substantially central portion thereof. The cylinder 14 is loosely fitted in the housing 16 with its longitudinal portion extending forwardly from the partition wall 26. The partition wall 26 has an oil passage 32 having an inside diameter smaller than the outside diameter of the ball seat 20, so that the cylinder 14 and the ball seat 20 are in abutment with the partition wall 26 of the housing 16. A force tending to retract the piston rod 12 generates a pressure which acts on the partition wall 26 either directly via a spring 24 and the cylinder 14 or via the high pressure oil chamber 21 and the ball seat 20.

Abstract: A hydraulic tensioner 10 includes a hollow housing 14 having formed therewith an intermediate partition wall 12, a circular hollow cylinder 16 disposed concentrically in the housing 14, and a piston rod 18 slidably received in the cylinder 16 with a small gap or clearance therebetween. The cylinder 16 and the piston rod 18 jointly define therebetween a high pressure oil chamber 20. The pressure in the high pressure oil chamber 20 counteracts the force tending to retract the piston rod 18. The piston rod 18 projects from an open end of the housing 14, and a seal 24 surrounds the piston rod 18 to seal or close the end of the housing 14. The piston rod 18 has secured thereto a rod guide 28 disposed within the low pressure oil chamber 26. A spring 36 is disposed in a compressed condition between the housing 14 and the rod guide 28 to urge the piston rod 18 in the advancing direction. The rod guide 28 has radially elongated oil holes or passages 38 formed in its surface which engages the spring 36.

Abstract: A tensioner includes a plunger slidably inserted in a housing and biased by spring means. The spring means include sequentially operable first and second portions in which the first portion has a relatively larger pitch and large spring modulus and the second portion has a relatively small pitch and small spring modulus. When the spring means is depressed a certain degree, the coils of the second spring portion 16 will move into close contact with each other to vary the spring modulus. Thus, the amount of backward movement and jutting out speed of the plunger will be decreased, thereby a required tensile force will be given to a belt, or the like, without delay.

Abstract: A tensioner for a chain or toothed belt which includes an oil reservoir. Oil contained in the oil reservoir is hermetically sealed by a diaphragm fixed to the oil reservoir by a plug. A pressurizing means is mounted between the diaphragm and the plug. The pressurizing means includes a compression spring and a bowl-shaped spring seat. A diaphragm is urged by the pressurizing means. A detent portion, extending upwardly from the diaphragm, is integrally formed on the surface of the diaphragm facing the atmosphere. The spring seat includes a recess at the central portion of the spring seat so that the detent portion of the diaphragm is engaged with the recess preventing free movement between the diaphragm and the pressurizing means.

Abstract: In a fluid tensioner of the piston and cylinder type an annular element is provided either on the piston or on the wall of the cylinder. In the case of an annular element on the wall of the piston, the annular element has a coefficient of linear expansion greater than that of the wall of the cylinder. In the case of an annular element on the wall of the cylinder, the annular element has a coefficient of linear expansion less than that of the piston material. In both cases, the annular element provides compensation for changes in hydraulic fluid viscosity to maintain a constant leak-down rate, allows for flexibility in the choice of piston, rod and cylinder materials.