Ratchet-type tensioner

Abstract

The present invention provides a ratchet-type tensioner which prevents a back clearance of a plunger piston from a timing chain when an engine after the engine after long-time placement, stably generates the oil pressure in a high-pressure oil chamber of a piston part that allows the retreating movement of piston, and smoothly realizes quick retreating movement of the plunger. A piston high pressure oil chamber (P) is provided between a piton accommodating hole (113) and a hydraulic pin (170). The piston high pressure oil chamber (P) causes the hydraulic pin (170) to displace in a direction of releasing a ratchet (150) and biting with the rachet teeth (122) relatively to the side surface of the plunger. The hydraulic pin (170) pushes with a mode that a swingable projection from a hydraulic pin accommodating hole to the ratchet is allowed. A second oil supply passage (114) which introduces the pressure oil into the piston high pressure oil chamber (P) is not branched from a first oil supply passage (111) for introducing the outside pressure chamber and is formed independently from a tensioner housing (110).

Description

technical field [0001] The present invention relates to a ratchet tensioner for applying tension to a timing chain that drives a camshaft of an engine. Background technique [0002] Conventionally, there is known a tensioner in which a spring and external oil act on a plunger that is slidably fitted into a case and forms an oil chamber with the case by using a timing chain such as a camshaft that drives an engine. The protruding force caused by the pressure, thus imparting tension to the timing chain. [0003] As such a conventional tensioner, such as Figure 9 As shown, it is composed of a housing 501 having a cylinder hole-shaped oil chamber 510 with an open front end, a retreat restricting portion 503 restricting the retreat of the plunger 502, and a jump-out restricting portion 504 restricting the plunger 502 from jumping out of the opening 513, and the The jump-out restricting portion 504 includes the following components: a piston chamber 540 formed on the outer perip...

AI Technical Summary

Problems solved by technology

[0005] In the conventional tensioner 500 as described above, as Figure 9 As shown, since the plunger internal oil chamber 510 for applying oil pressure to the plunger 502 and the oil chamber 543 for applying oil pressure to the piston 542 are connected to each other, if the engine is left standing for a long time after the engine stops, air will enter the oil chamber 510. When the engine is started, it is affected by the pulsation of the external oil pressure generated from the oil pump, so that sufficient oil pressure cannot be ensured in the oil chamber 510, and the backward movement of the piston 542 based on the oil pressure in the oil chamber 510 becomes unstable, so that not only cannot The engagement between the locking teeth 531a of the swing body 531 and the rack 525 is completely and quickly released, and there is also the possibility of destroying the engagement between the locking teeth 531a and the rack 525

[0006] Therefore, in the conventional tensioner 500, the engagement between the locking teeth 531a and the rack 525 cannot be completely and quickly released as described above when the engine is started, and the smooth movement of the plunger 502 cannot be achieved after the engine is started. The problem of sliding forward and backward movement, and because of the incomplete engagement between the locking tooth 531a and the rack 525, the locking tooth 531a and the rack 525 are destroyed, resulting in the inability to ensure the timing corresponding to the wear progress of the timing chain. The force of the plunger 502, or completely prevent the plunger 502 from the timing chain from the backlash (backbash) of the retraction phenomenon and cannot eliminate the noise caused by the fitting of the timing chain. The coil spring 522 that applies force in the direction in which the plunger 502 protrudes must be a strong spring that can withstand the backlash of the plunger 502, and there is a problem that the tensioner itself is enlarged.

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