JPS6235957Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a sealed autotensioner.

An autotensioner, which has a structure similar to a hydraulic lifter used in a valve mechanism of an internal combustion engine, is used to apply tension to a belt, chain, etc. This type of hydraulic lifter (auto tensioner) is, for example, an open type used with an oil pan as disclosed in U.S. Pat. No. 3,875,908, and a sealed type as disclosed in U.S. Pat. No. 2,815,740. There is something. The open type requires an oil pan, which limits its usage. On the other hand, the sealed type
It uses the lifting and lowering of a plunger inside the body.
Since the plunger diameter is large and its stroke is small, the places where it can be used are limited, similar to the open type.

In order to eliminate the above-mentioned problems with the sealed autotensioner, this idea was developed by arranging a plunger inside the body to create a large-diameter oil chamber, and a piston in the center hole of the plunger to create a small-diameter oil chamber. The oil chamber is communicated with a small diameter passage, the piston provides a large stroke, and the body is divided into two parts.
A technical means is used in which a dust seal is provided in the hole through which the piston passes through the top wall of the upper body, and the top wall is used as a seating surface for a spring that biases the plunger. According to this invention, the body is divided into two parts and a dust seal is placed on the top wall of the body, so that no dust enters the body and does not interfere with the piston stroke. Further, since the piston is guided by the plunger and the top wall of the body, there is an advantage that the stroke of the piston is smooth.

According to this invention, a plunger is slidably inserted into a body and forms a large-diameter oil chamber at the bottom of the body, and a plunger is slidably inserted into a central hole of the plunger and has a small-diameter oil chamber at the bottom of the central hole. A sealed autotensioner that includes a piston that forms an oil chamber and a spring that biases the plunger toward the large-diameter oil chamber, and that communicates the large-diameter oil chamber and the small-diameter oil chamber through a small passage. The body is divided into two parts, a hole is provided in the top wall of the upper body through which the piston passes, a dust seal is disposed around the hole, and the top wall is used as a seating surface for the spring. A sealed autotensioner is provided.

An embodiment of this invention will be described with reference to the accompanying drawings.

The sealed oil tensioner 1 has a body 2 divided into upper and lower halves. The plunger 4 is slidably inserted into the lower body 3. A large diameter oil chamber 5 is created between the bottom wall of the plunger 4 and the bottom wall of the lower body, a piston 7 is slidably disposed in the center hole 6 of the plunger 4, and a small diameter oil chamber 5 is formed between the bottom wall of the plunger 4 and the bottom wall of the lower body. Create room 8.

A dust seal 11 is arranged around the hole in the top wall 10 of the upper body 9, and the dust seal 11 is in sliding contact with the upper part of the piston 7 and the top wall 1
0 is a spring 1 seated on the stepped portion of the plunger 4
2, and screw it onto the lower body 3.

The oil sealed in the large diameter oil chamber 5 and the small diameter oil chamber 8 are conducted through a small diameter passage 13 bored in the bottom wall of the plunger 4. Further, the free length of the piston 7 is defined by bringing the stepped portion 14 of the piston 7 into contact with the top wall 10. The end of the plunger 7 becomes a working surface 15 that is pressed against a belt, chain, etc., either directly or through another member.

When an external force acts on the working surface 15 of the piston 7,
The piston 7 sinks into the plunger 4, and the small diameter oil chamber 8
This pressure increase is transmitted to the large diameter oil chamber 5 via the small diameter passage 13, acts on the bottom wall of the plunger 4, and is kept in balance with the biasing force of the spring 12. During the operation of the autotensioner, the dust seal 11 prevents dust from entering the body 2, so that the piston 7 and the plunger 4 can always maintain smooth movement.

[Brief explanation of the drawing]

The figure is a sectional view of an autotensioner according to an example of this invention. In the diagram: 3...lower body, 4...plunger, 5
...Large diameter oil chamber, 7...Piston, 8...Small diameter oil chamber, 9...Upper body, 10...Top wall, 11...Dust seal, 13...Small diameter passage.

Claims (1)

[Scope of utility model registration request] a plunger that is slidably inserted into a body and forms a large-diameter oil chamber at the bottom of the body; and a piston that is slidably inserted into a central hole of the plunger and forms a small-diameter oil chamber at the bottom of the central hole. a spring that biases the plunger toward the large-diameter oil chamber, and a sealed autotensioner that communicates the large-diameter oil chamber and the small-diameter oil chamber via a small-diameter passage; A sealed autotensioner characterized in that the upper body is divided into parts, a hole is provided in the top wall of the upper body for the piston to pass through, a dust seal is disposed around the circumferential surface of the hole, and the top wall is used as a seating surface for the spring. .