Patent ID: 8926460
Filing Date: 2015-01-06
Classification: F16H

Abstract:
1. A ratchet-type tensioner, comprising: a housing body in which an oil passage for supplying external pressure oil is formed; a plunger-accommodating hole formed in the housing body; a plunger projecting out of the plunger-accommodating hole toward a traveling chain, and slidable in said plunger-accommodating hole in an advance/setback direction; a high-pressure oil chamber formed between the plunger-accommodating hole of said housing body and a hollow portion of the plunger; a plunger biasing spring accommodated in the high-pressure oil chamber to bias the plunger in a plunger projection direction; a ratchet-receiving hole formed within said housing, said ratchet-receiving hole having a front end adjacent said plunger-accommodating hole and a rear end remote from said plunger-accommodating hole; a columnar ratchet element fittingly inserted into the ratchet-receiving hole and sliding in a direction transverse to said advance/setback direction of the plunger; ratchet teeth provided at a plunger-side front-end area of the ratchet element; a ratchet biasing spring for biasing the ratchet teeth toward rack teeth provided on a side surface of the plunger; and a spring stopping washer fitted into said ratchet-receiving hole at a location adjacent said rear end of said ratchet-receiving hole to seat the ratchet biasing spring; characterized in that said ratchet biasing spring is inserted and attached within a spring-accommodating hole provided within said ratchet element, said spring being extendible in a sliding direction of the ratchet element as the ratchet element moves in a direction in which the ratchet element projects out of the spring-accommodating hole; said ratchet-receiving hole is defined by a wall having a diameter, and has a circumferential groove formed in said wall at a location adjacent said rear end thereof; said spring stopping washer comprises a resilient C-ring having opposed free ends, said C-ring being capable of being reduced to a diameter smaller than the diameter of said wall of the ratchet-receiving hole by drawing said free ends toward each, and being resiliently expansible to a larger diameter greater than the diameter of said wall, said C-ring being anchored at said location adjacent said rear end of said ratchet-receiving hole by fitting into said circumferential groove, and said spring stopping washer also comprises a spring stopping piece, located centrally within said ratchet-receiving hole and offset from said C-ring toward said front end of the ratchet-receiving hole, to seat the ratchet biasing spring, and a narrow neck-shaped connecting portion, unitary with said spring stopping piece and said C-ring, connecting said spring stopping piece to the C-ring, said narrow-neck-shaped connecting portion extending obliquely with reference to said sliding direction of the ratchet element, both inward toward a central location within said ratchet-receiving hole and forward toward said front end of the ratchet-receiving hole, from an intermediate location on the C-ring between said free ends of the C-ring to the spring stopping piece; and said spring stopping piece overlaps both of said free ends of the C-ring by extending in directions transverse to said sliding direction of the ratchet element, and is engageable with both free ends of the C-ring by movement of said spring stopping piece in said sliding direction of the ratchet element upon deflection of said narrow neck-shaped connecting portion, the extent of the overlap of the stopping piece with the free ends of the C-ring, when the C-ring is fitted into said circumferential groove, being sufficient that the spring stopping piece can be supported both by said narrow neck-shaped connecting portion and by engagement of overlapping parts of the spring stopping piece with parts of the free ends of the C-ring.