JPH0749105Y2 - Hydraulic auto tensioner - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a hydraulic automatic tensioner for maintaining the tension of a transmission member such as an endless toothed belt or chain at a set tension.

[Conventional technology]

As a hydraulic auto tensioner, as shown in Fig. 6,
In the cylinder 30, a plunger 31, a rod 32 that moves in the axial direction together with the plunger 31, and a pressure adjusting spring 33 that applies an outward biasing force to the rod 32 are incorporated, and the upper portion of the rod 32 is attached to the cylinder 30. Of the hydraulic oil in a pressure chamber 35 formed below the plunger 31 and a reservoir chamber 36 provided above the plunger 31. And the passage 37 formed in the plunger 31 into the both chambers 35,
The applicant of the present application has already proposed that the check valve 38 is provided in the passage 37 through the 36.

In the above hydraulic auto tensioner, the belt is pressed by the rod 32, the tension of the belt increases, and the rod 32
Also, when the plunger 31 is pushed in, the hydraulic oil in the pressure chamber 35 is leaked from the sliding surface of the plunger 31 and the cylinder 30 to buffer the impact force applied to the rod 32.

When the tension of the belt becomes small, the pressure adjusting spring 33
The rod 32 and the plunger 31 are moved outward by the elasticity of the check valve 38 at the same time, and the reservoir chamber is opened.
The hydraulic oil 36 is made to flow into the pressure chamber 35 from the passage 37.

As described above, the hydraulic auto tensioner
Since the configuration is such that the belt 31 and the rod 32 are moved together in the axial direction to absorb the belt tension change, the plunger 31 and the rod 32 are
It is necessary to integrate 32 and 32 in the axial direction.

As a method of integrating the plunger 31 and the rod 32 with each other, as shown in FIG. 6, a recess 39 is formed in the upper end surface of the plunger 31, and the lower end of the rod 32 is press-fit into the recess 39. There is a method of forming the plunger 31 and the rod 32 by forging and shaving.

[Problems to be solved by the device]

By the way, in the integration by press-fitting, there is a large variation in the removal force due to the press-fitting margin, and when the press-fitting margin is increased, the outer diameter of the plunger 31 is deformed and the leak formed between the sliding surface of the plunger 31 and the cylinder 30. The clearance changes. Therefore, it becomes necessary to accurately machine the inner diameter of the recess 39 of the plunger 31 and the outer diameter of the rod 32 to a predetermined dimension, which is extremely troublesome to machine.

On the other hand, in the method of forging or carving out the plunger and rod, the outer diameter of the plunger 31 is considerably larger than the outer diameter of the rod 32, which makes it difficult to perform cold forging. Is large and is disadvantageous in terms of cost.

Further, although the outer diameter of the plunger 31 needs to be ground with high precision, there are many inconveniences such as inexpensive through-feed centerless grinding cannot be adopted because the length of the rod 32 is long.

It is a technical object of the present invention to solve the above-mentioned inconvenience, to facilitate the processing of the plunger and the rod, and to reduce the cost.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, in the present invention, a recess is formed in the upper end surface of the plunger in which the lower part of the rod is loosely fitted, and the inner peripheral surface of this recess and the outer peripheral surface of the rod respectively have engagement grooves. At least one of the upper end surface of the plunger-side engagement groove and the lower end surface of the rod-side engagement groove is formed as a taper surface that inclines outward, and the taper is formed between the pair of engagement grooves by the restoring elasticity in the radial direction. It employs a construction that incorporates a retaining ring that is partially cut off to press the lower end of the rod against the bottom surface of the recess by pressing against the surface, its tapered surface, and the end surface at the diagonal position.

[Action]

When the rod is pushed in in the axial direction, the lower end of the rod pushes the bottom surface of the recess, so that the plunger moves together with the rod, and when the rod moves upward, the plunger is pulled up via the retaining ring.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

As shown in FIG. 1, a bottomed sleeve 2 is inserted into a lower portion of a cylinder 1 whose lower end is closed, and a plunger 3 is slidably inserted into the sleeve 2. The outer diameter surface of the plunger 3 and the sleeve 2 A leak gap (not shown) is provided between the inner diameter surfaces of the.

A recess 4 is formed in the upper end surface of the plunger 3, and the upper end surface of the engagement groove 5 provided in the inner peripheral surface of the recess 4 is a tapered surface 6 that inclines outward, as shown in FIG. ing.

A lower end portion of a rod 7 is loosely fitted in the recess 4, and an engaging groove 8 is provided at the lower end portion of the rod 7 so as to face the engaging groove 5, and between the engaging grooves 5 and 8. The snap ring 9 is fitted.

Here, as the snap ring 9, as shown in FIG. 3 (a), a partially cut circular shape, and as shown in FIG. 3 (b), a partially cut oval shape, Figure 3 (C)
It is possible to use a substantially triangular shape with a part separated as shown in FIG.

Any of the retaining rings 9 has a reduced diameter, and the pair of engagement grooves 5,
It is inserted between 8. Therefore, the retaining ring 9 has an elastic force in the outer diameter direction, and the elastic force presses the tapered surface 6 of the plunger side engagement groove 5. The rod 7 is pressed against the bottom surface of the recess 4 by this pressing.

A cylindrical separator 10 and a wear ring 11 are inserted outside the rod 7. Separator 10 has a flange that extends toward the upper and lower ends and that is provided at the lower end.
12 is supported on the upper end of the sleeve 2. On the other hand, the wear ring 11 has a hole 13 and its upper surface engages with a step 14 formed in the middle of the rod 7. A pressure adjusting spring 15 is incorporated between the wear ring 11 and the flange 12 of the separator 10, and the elasticity of the pressure adjusting spring 15 allows the rod 7 to project outward.

The upper portion of the rod 7 slidably penetrates through the oil seal 16 attached to the upper opening of the cylinder 1, and the cylinder 1
Protruding to the outside.

In the cylinder 1 sealed by the oil seal 16, the pressure chamber 17 below the plunger 3 and the reservoir chamber above the plunger 3.
18 are provided, and both chambers 17 and 18 communicate with each other through a passage 19 formed in the plunger 3 and the rod 7. The lower end of the passage 19 communicates with a recess 20 formed in the lower surface of the plunger 3,
A check valve 22 for opening and closing the lower end opening of the passage 19 is incorporated in a cage 21 press-fitted into the recess 20.

The check valve 22 opens the passage 19 when the pressure in the pressure chamber 17 becomes lower than the pressure in the reservoir chamber 18.

The working oil is put into the pressure chamber 17 and the reservoir chamber 18, the working oil occupies 70% of the space sealed by the oil seal 16, and the remaining 30% of the space absorbs the volume change of the working oil.

In the autotensioner having the above structure, when the tension of the belt acting on the upper end of the rod 7 decreases, the rod 7 and the plunger 3 are pushed out by the elastic force of the pressure adjusting spring 15, and at the same time, the check valve 22 opens the passage 19 and the reservoir chamber. Allow 18 hydraulic fluid to flow into the pressure chamber 17.

The rod 7 and the plunger 3 stop when the tension of the belt and the elasticity of the pressure adjusting spring 15 are balanced.

On the contrary, when the tension of the belt increases, the rod 7 and the plunger 3 are pushed in, and the check valve 22 passes the passage.
Close 19 At this time, the hydraulic oil in the pressure chamber 17 flows into the reservoir chamber 18 through the leak clearance on the outer diameter surface of the plunger 3, and exerts a buffering action.

When connecting the plunger 3 and the rod 7, a retaining ring 9 is fitted in the engaging groove 8 of the rod 7, the retaining ring 9 is reduced in diameter, and the lower end of the rod 7 is inserted into the recess 4 of the plunger 3.

When the rod 7 comes into contact with the bottom surface of the recess 4, the engagement groove 8 on the rod 7 side faces the engagement groove 5 on the plunger 3 side, and the retaining ring 9 expands in the outer diameter direction, and the engagement groove 8 on the plunger side. Engage 5.

At this time, the retaining ring 9 pushes the tapered surface 6, so that the rod 7
The lower end of is strongly pressed against the bottom surface of the recess 4. Therefore, there is no backlash in the axial direction of the rod 7, and vibration and noise are prevented from occurring.

4 and 5 show another embodiment of the hydraulic type automatic tensioner.

In the embodiment shown in FIG. 4, the lower end surface of the rod side engaging groove 8 is a tapered surface 23, and the tapered surface 23 is pressed by a retaining ring 9 having an elastic force in the inner diameter direction.

Further, in the embodiment shown in FIG. 5, the plunger side engagement groove 5
And the lower end surface of the rod-side engagement groove 8 are tapered surfaces 6 and 23 inclined outward, respectively.
Is pressed by a retaining ring 9 having elasticity in the outer diameter direction, and the lower end surface of the rod 7 is pressed against the bottom surface of the recess 4.

In the embodiment shown in FIG. 5, a third retaining ring 9 is used.
When the retaining rings shown in FIGS. (B) and (C) are used, the A portion of each retaining ring 9 abuts the taper surface 23 of the rod side engagement groove 8 and the B portion thereof is the taper surface of the plunger side engagement groove 5. 6, and presses the contact portion in opposite directions.

[Effect of device]

As described above, in the auto tensioner according to the present invention, since the plunger and the rod are connected by the retaining ring, it is possible to process each part separately. For this reason,
It is easy to process and can reduce the cost.

In addition, by incorporating a partially separated snap ring between the engagement groove of the plunger and the rod, the restoring elasticity of the snap ring in the radial direction causes the taper surface and the taper surface to oppose the end surface at the diagonal position. Since the lower surface of the rod is pressed against the bottom surface of the recess by being pushed in the direction, the plunger and the rod can be securely coupled in the axial direction without backlash, and the retaining ring presses the tapered surface, so that the plunger is pressed. And the rod can be coaxially connected.

Further, since the recess of the plunger has a size such that the lower portion of the rod is loosely fitted, it is not necessary to strictly control the dimensional accuracy of the inner diameter of the recess and the outer diameter surface of the rod, and both parts can be easily processed. .

Also, by fitting a retaining ring in the engagement groove of the plunger or the engagement groove of the rod to elastically deform in the radial direction, and by inserting the lower end of the rod into the recess of the plunger in that deformed state,
When the engagement grooves face each other, the retaining ring restores its shape and penetrates into the engagement groove at the opposing position, so that the plunger and the rod can be connected very easily.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the automatic tensioner according to the present invention, FIG. 2 is an enlarged sectional view showing a connecting portion between a plunger and a rod in the same, FIG. 3 (a),
(B) and (C) are front views of the retaining ring, FIGS. 4 and 5 are sectional views showing another embodiment of the same automatic tensioner, and FIG. 6 is a vertical sectional front view showing a conventional automatic tensioner. . 1 ... Cylinder, 3 ... Plunger, 4 ... Recess, 5 ...
… Engagement groove, 6 …… Tapered surface, 7 …… Rod, 8 …… Engagement groove, 9 …… Retaining ring, 15 …… Pressure adjusting spring, 16 …… Oil seal, 17 …… Pressure chamber, 18… … Reservoir chamber, 19 …… passage, 22 …… check valve, 23 …… tapered surface.

Claims (1)

[Scope of utility model registration request] 1. A plunger is inserted into a cylinder with a required leak clearance, and an upper portion of a rod which moves axially together with the plunger is penetrated through an oil seal attached to an upper opening portion of the cylinder so as to protrude outside the cylinder. , Hydraulic oil is put into a pressure chamber formed below the plunger and a reservoir chamber provided above the plunger, and both chambers are communicated with each other through a passage formed in the plunger, and the pressure of the pressure chamber is stored in the passage. In the hydraulic autotensioner equipped with a check valve that opens the passage when the pressure becomes lower than the pressure in the cylinder, and a pressure adjusting spring that applies an outward biasing force to the rod is installed in the cylinder, A recess is formed in the end surface where the lower part of the rod is loosely fitted, and engagement grooves are formed on the inner peripheral surface of this recess and the outer peripheral surface of the rod, respectively. At least one of the upper end surface of the engagement groove and the lower end surface of the rod engagement groove is formed as a taper surface that inclines outward, and the taper surface and the surface thereof are elastically restored between the pair of engagement grooves in the radial direction. A hydraulic autotensioner characterized by incorporating a retaining ring, a part of which is cut off, pressing the lower end of the rod against the bottom surface of the recess by pressing it against the end face at a diagonal position.