| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a hydraulic tensioner of low cost having a timing chain provided with response characteristics that are instantaneously regulatable to sudden change in tension which is capable of preventing impact sound at a valve element likely to occur in a relief valve mechanism, or sagging or breaking of a spring energizing a valve element in a simple valve structure when oil fed from a hydraulic pressure generating source such as an oil pump is excessively fed, when abrupt tension is generated in the timing chain, or when excessive high pressure occurs in a high pressure oil chamber. SOLUTION: The relief valve mechanism 17 of this hydraulic tensioner provided with a relief valve mechanism is composed of a valve element engagement/insertion part 17a of an enlarged diameter communicated with an oil feed port 17b, a valve element 17c freely slidable in the valve element fit-inserted part 17a to advance or retract by hydraulic pressure from the oil feed port 17b, and a spring 17d to energize the valve element 17c to be elongated toward the oil feed port. An oil relief hole 17h bored in a circumferential wall of the valve element fit-inserted part 17a is provided at such a position as to be closed when the valve element 17c excessively retracts by sudden increase in hydraulic pressure from the oil feed port 17b.</p> |
