Patent application number | Description | Published |
20080261736 | Chain tensioner - A stepped set groove having shallow and deep portions is formed in the inner periphery of a cylinder chamber formed in a housing of a chain tensioner near its open end. A radially and elastically deformable set ring having circumferentially separated ends is received in the set groove in a radially compressed state. The set ring has at the respective ends thereof a pair of grip portions which are received in a cutout formed in housing at its front end. By engaging the set ring in an engaging groove formed in the outer periphery of the plunger near its front end and the shallow portion, it is possible to keep the plunger pushed into the cylinder chamber. In this state, the chain tensioner is mounted in position. One of the grip portions is brought into abutment with one of the circumferentially opposed end walls of the cutout to prevent the plunger from rotating about its axis in such a direction that the axial gap between an internal thread of the plunger and an external thread of a screw rod inserted in the plunger disappears. Thus, it is possible to keep the axial gap larger than the axial distance by which the plunger has to be moved to move the set ring from the shallow portion into the deep portion. This makes it possible to disengage the set ring from the engaging groove by pushing the plunger into the cylinder chamber. | 10-23-2008 |
20080268993 | Chain tensioner - A chain tensioner includes a housing defining a cylinder chamber having a closed end. A cylindrical plunger having a closed front end is slidably received in the cylinder chamber. A nut member and a return spring are mounted in the cylinder chamber. The return spring biases the plunger outwardly of the housing to press its closed end against a pivotally supported chain guide. The nut member has a serration-shaped internal thread formed on the inner periphery thereof which is in threaded engagement with a serration-shaped external thread formed on the outer periphery of the screw rod. The screw rod is biased toward the closed end of the plunger by a rod spring. A damper is mounted between the front end of the screw rod and the closed front end of the plunger for damping, in cooperation with the return spring, a pushing force applied to the plunger, and for allowing the screw rod and the plunger to move relative to each other in a direction in which the distance between respective remote ends thereof decreases by an amount not less than an axial play present between the internal and external threads. | 10-30-2008 |
20080280712 | Chain tensioner - A chain tensioner includes a housing defining a cylinder chamber. A plunger is mounted in the cylinder chamber so as to be slidable along an inner surface of the cylinder chamber. A return spring is mounted in the cylinder chamber to bias the plunger outwardly. The housing is formed with an oil supply passage communicating with a pressure chamber defined in the housing behind the plunger. A check valve is disposed at an oil exit of the oil supply passage and configured to close the oil supply passage when the pressure in the pressure chamber is higher than the pressure in the oil supply passage. The housing is formed with a threaded hole extending from an upper portion of an outer periphery of the housing to the pressure chamber. A screw has its external thread in threaded engagement with the internal thread of the threaded hole, whereby a gap, as an air bleed passage, is defined between the internal and external threads. The internal thread of the threaded hole has an internal diameter larger than an internal diameter of an internal thread under JIS. | 11-13-2008 |
20090011880 | Auto-tensioner - An auto-tensioner includes a plunger slidably inserted in a cylinder and having a closed front end protruding from the cylinder and an open rear end which is located in the cylinder. The plunger is formed with an internal thread on its inner periphery. A screw rod having an external thread formed on its outer periphery thereof and inserted in the plunger with its external thread in threaded engagement with the internal thread of the plunger. The screw rod has a rear end protruding from the open rear end of the plunger. A seat member is mounted in the cylinder and in abutment with the rear end of the screw rod. A return spring having one end thereof supported by the screw rod biases the plunger outwardly of the cylinder to press the closed front end of the plunger against a chain or a belt. An elastic member which is compressible in the axial direction of the cylinder supports the seat member. | 01-08-2009 |
20100087285 | CHAIN TENSIONER - A chain tensioner includes a cylinder inserted in a tensioner mounting hole of an engine cover and having a flange fixed to the outer surface of the engine cover. A plunger is axially slidably mounted in the cylinder. The cylinder is formed with an oil supply passage through which hydraulic oil is introduced into a pressure chamber defined by the cylinder and the plunger. The oil supply passage includes a first hole portion extending inwardly from a mating surface of the flange facing the engine cover, and a second hole portion extending from the outer periphery of the flange to the pressure chamber and intersecting the first hole portion. An externally threaded portion of an externally threaded member is in threaded engagement with an internal thread formed on the second hole portion, thereby closing its outer open end. The externally threaded member is fixed in position with an adhesive applied to its externally threaded portion. | 04-08-2010 |
20100099529 | CHAIN TENSIONER - 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. | 04-22-2010 |
20100130320 | CHAIN TENSIONER - A chain tensioner includes a cylindrical cylinder having a closed end, a plunger slidably mounted in the cylinder, and a return spring biasing the plunger. The cylinder is formed with an oil supply passage through which hydraulic oil is introduced into a pressure chamber defined by the plunger and the cylinder. The oil supply passage has an orifice at its end portion facing the pressure chamber. A leak gap is defined between sliding surfaces of the plunger and the cylinder. A damper force is produced by viscous resistance of hydraulic oil flowing from the pressure chamber through the leak gap, and by viscous resistance of hydraulic oil flowing from the pressure chamber into the oil supply passage through the orifice. | 05-27-2010 |