摘要:
A hydraulic autotensioner has a cylinder having a closed bottom end, a sleeve mounted in the cylinder and a plunger slidably mounted in the sleeve. The interior of the cylinder is divided into a reservoir chamber and a pressure chamber by the plunger which is formed with a passage through which the reservoir chamber and the pressure chamber communicate with each other. A check valve is provided in the passage to close the passage if the pressure of hydraulic oil in the pressure chamber increases above the pressure of hydraulic oil in the reservoir chamber. A return spring is mounted in the cylinder to bias a rod which is axially movable together with the plunger in such a direction as to protrude from an upper opening of the cylinder. The return spring is mounted in a space formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the cylinder.
摘要:
A hydraulic autotensioner has a cylinder having a closed bottom end, a sleeve mounted in the cylinder and a plunger slidably mounted in the sleeve. The interior of the cylinder is divided into a reservoir chamber and a pressure chamber by the plunger which is formed with a passage through which the reservoir chamber and the pressure chamber communicate with each other. A check valve is provided in the passage to close the passage if the pressure of hydraulic oil in the pressure chamber increases above the pressure of hydraulic oil in the reservoir chamber. A return spring is mounted in the cylinder to bias a rod which is axially movable together with the plunger in such a direction as to protrude from an upper opening of the cylinder. The return spring is mounted in a space formed between the outer peripheral surface of the sleeve and the inner peripheral surface of the cylinder.
摘要:
An autotensioner for controlling the tension of a belt. It is filled with a hydraulic oil containing poly-.alpha.-olefin as a basic ingredient. Since such an oil has excellent viscosity-temperature properties as well as good lubricating properties, a body and a piston slidably mounted in the body are abraded less at their sliding surface than with a prior art autotensioner and thus the size of an oil leakage gap formed therebetween is less subject to change. This will prevent cavitation in a pressure chamber formed in the body.
摘要:
An autotensioner includes a cylinder having its bottom closed and filled with a hydraulic oil and air, an oil seal mounted in the cylinder to seal the hydraulic oil and air, a rod slidably extending through the oil seal, and a piston slidably mounted in the cylinder with its top end abutting the bottom of the rod. The interior of the cylinder is separated into an upper reservoir chamber and a lower pressure chamber by the piston. Both chambers communicate with each other through a channel formed in the piston. The rod is biased by a spring mounted in the reservoir chamber in such a direction as to protrude from the cylinder. A check valve is provided in the pressure chamber near the bottom of the piston to open the channel in the piston only when the pressure in the pressure chamber is lower than the pressure in the reservoir chamber. The cylinder may have an outer casing and an inner sleeve so that the piston can slide on the inner surface of the sleeve.
摘要:
An autotensioner for adjusting the tension of a timing belt used with an automotive engine. It includes a cylinder case filled with a hydraulic oil, a piston partitioning the interior of the cylinder case into a pressure chamber and a reservoir chamber and a push rod having its bottom end coupled to the piston and the top end adapted to protrude from the cylinder case. A spring is provided to bias the piston and the push rod upwardly. The pressure chamber communicates with the reservoir chamber through a channel formed through the piston. A plate-shaped check valve is provided in the pressure chamber to open and close the bottom of the channel. The plate-shaped valve can respond quickly to the fluctuation of pressure in the pressure chamber because of its reduced mass. Thus, when the piston and the push rod rise biased by the spring, the valve can move quickly to such a position as to open the channel, thus allowing the hydraulic oil in the reservoir chamber to flow quickly and smoothly back into the pressure chamber. This will prevent cavitation in the pressure chamber. The responsiveness of the valve will be improved further by providing another spring for biassing the valve in such a direction as to open the channel.
摘要:
A belt autotensioner for giving a desired tension to a belt. It includes a tension pulley pressed against the belt, an eccentric shaft extending through the tension pulley to rotatably support it and formed with a hole arranged eccentrically from the axis of the tension pulley, an actuator having a cylinder and a push rod silidably mounted in the cylinder and having its one end protruding from the cylinder and butting a projection fixed to the eccentric shaft, a bolt extending through the hole in the eccentric shaft and the cylinder of the actuator to pivotally support the eccentric shaft and a spring for biasing the eccentric shaft to pivot it in such a direction as to increase the tension of the belt. The spring may be a torsion coil spring mounted around the eccentric shaft with its one end fixed to the outer periphery of the eccentric shaft and the other end fixed to the cylinder of the actuator.
摘要:
A chain tensioner includes a housing formed with a cylinder chamber in which a plunger is slidably mounted. A return spring, also mounted in the cylinder chamber, biases the plunger outwardly of the cylinder chamber. The housing is formed with an oil supply passage communicating with a pressure chamber defined in the cylinder chamber by the plunger. A check valve is provided at the outlet of the oil supply passage. An oil filter is mounted in the inlet of the oil supply passage. The oil filter removes foreign objects contained in hydraulic oil supplied into the oil supply passage, thereby preventing malfunction of the chain tensioner due to foreign objects getting stuck in moving parts of the chain tensioner.
摘要:
A chain tensioner includes a cylinder having a closed end, a plunger axially slidably inserted in the cylinder and having an internal thread on the inner periphery thereof, a return spring biasing the plunger in the protruding direction from the cylinder, and a screw rod having an external thread that is in threaded engagement with the internal thread of the plunger. The portion of the screw rod protruding from the plunger abuts a rod seat provided in the cylinder. The external thread of the screw rod is formed by rolling. The screw rod has an intermediate portion protruding from the plunger and having an outer diameter smaller than the diameter of the root of the external thread. A contact surface contact surface of the screw rod to be brought into contact with the rod seat is formed on the axial end face of the intermediate portion by forging. The internal thread may be formed by pressing, and a pressed recess may be formed on the outer circumference of the plunger, corresponding to the internal thread.
摘要:
A chain tensioner includes a housing defining a cylinder chamber, and a plunger having a small-diameter end and a spring both mounted in the cylinder chamber. A register ring is fitted in a ring-receiving groove formed in the inner periphery of the cylinder chamber near its open end. A plurality of annular grooves are formed in the outer periphery of the plunger so as to be axially spaced from each other at equal intervals. The register ring is adapted to be press-fitted in one of the annular grooves. With the register ring trapped between an engaging surface of a first annular groove which is one of the annular grooves located nearest to the front end of the plunger and a locking surface of the ring-receiving groove, an outer cylindrical surface of the plunger extending forwardly from the first annular groove has its front portion supported by an inner cylindrical surface of the cylinder chamber extending forwardly from the ring-receiving groove.
摘要:
A hydraulic tensioner includes a cylinder having a hollow space filled with hydraulic oil. A plunger is slidably mounted in the cylinder. A pushrod is mounted in the hollow space so as to be axially movable together with the plunger with one end thereof protruding from the cylinder. A spring is mounted in the cylinder to bias the plunger and pushrod outwardly of the cylinder. The plunger is formed with a passage through which a pressure chamber and reservoir chamber communicate with each other. The passage is formed with a valve seat. A check ball is arranged so as to be moved into and out of contact with the valve seat. The check ball is adapted to contact the valve seat when pressure in the pressure chamber exceeds pressure in the reservoir chamber, thereby closing the passage. The valve seat is formed of a steel for carburizing and has a surface carbon concentration of 0.55–0.75% to reduce deposition of carbides and to have a surface hardness at least equal to that of the check ball.