To provide an external hydraulic auto tensioner for preventing damage to a return spring due to the biting of foreign matter into a coil portion of the return spring or the collision of jumping stones.
An oil seal 13 is incorporated in the upper opening of a cylinder 11 in which a sleeve 12 is mounted. The elastic force of the return spring 17 provided outside the cylinder 11 is loaded on a rod 14 which slidably passes through the oil seal 13, for energizing it outward. An elastic spiral protector ring 30 is incorporated in between the coil portion 17a of the return spring 17, and spiral pieces 31a-31d are provided at an inner diameter portion and an outer diameter portion on the upper side face and the lower side face of the protector ring 30 for elasticall contact with both upper parts and both lower parts of the coil portion 17a. The protector ring 30 prevents damage to the return spring 17 due to the biting of foreign matter in the coil portion 17a or the collision of foreign matter.
COPYRIGHT: (C)2007,JPO&INPIT
YAMADA MASAYOSHI
Torii Kazuhisa
Takayoshi Tagawa
Higashio Masahiro