JP2891667B2 - Automatic tensioner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endless transmission, such as an engine timing chain or a belt, which is pressed in a tensioning direction to automatically absorb looseness.
The present invention relates to an automatic tensioner that applies a predetermined tension to an endless transmission.

[0002]

2. Description of the Related Art There are various types of conventional automatic tensioners of this kind (see Japanese Patent Publication No. 56-53139).
However, an example is shown in FIG. This automatic tensioner applies a tension to a cam chain of an engine. A bearing member 51 is provided at a front end (right side in the drawing) of a body 50, and a non-circular hole 51a of the bearing member 51 is provided with a chain guide 5
Pressing member 5 for pressing a cam chain (not shown) through
2 is supported so that it can move forward and is prevented from rotating, and a shaft 54 to which an elastic force is applied in a fixed rotational direction by a torsion spring 53 is attached to the female thread 52a of the pressing member 52 by its male thread 54a. It is screwed. The rearward position of the rear end of the pressing member 52 is regulated by a washer 58 fitted into the step portion 57 of the shaft 54.
Further, a spacer 59 for regulating the forward position of the shaft 54 is disposed between the washer 58 and the bearing member 51.

In setting the automatic tensioner, the torsion spring 53 is wound up and the body 5
In a state where the plate-shaped stopper member 55 is fitted into the radial stopper groove formed in the shaft 54 and the shaft 54, the rotation of the shaft 54 is stopped, and the body 50 is moved to the cylinder block 5.
6, the pressing member 52 is oriented in a direction of pressing the cam chain. Then, when the stopper member 55 is pulled out and the rotation inhibition of the shaft 54 is released, the shaft 54 is rotated by the spring force of the torsion spring 53.
At this time, since the pressing member 52 screwed to the shaft 54 is prevented from rotating by the bearing member 51 , the pressing member 52 advances in the direction (rightward) for pressing the cam chain with the rotation of the shaft 54.

[0004]

However, in the above configuration, the bearing member 51 for guiding the pressing member 52 to move forward is
It is formed in a disk shape so that it can be processed at low cost by press molding, and its axial length is very short, about 1.5 to 2.5 mm. On the other hand, it is necessary to increase the clearance due to the manufacturing method of the bearing member 51. There is. Therefore, the pressing member 52 vibrates due to the force or vibration transmitted from the timing chain during the operation of the engine, and accordingly, between the bearing member 51 and the pressing member 52 or between the bearing member 51 and the body 5.
A collision sound is generated between zero.

The present invention has been made in view of the above circumstances, and has as its object to provide an automatic tensioner capable of suppressing the generation of a collision sound caused by a force or vibration transmitted from the endless transmission.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an automatic tensioner which applies tension by pressing a belt-shaped endless transmission in a tensioning direction to advance and press the endless transmission. A pressing member, a shaft screwed to the pressing member and having an elastic force applied in a fixed rotational direction, a body for housing the pressing member and the shaft in a mounting hole, and preventing rotation of the pressing member. A bearing member for advancing the pressing member in the axial direction by rotation of the shaft based on the elastic force,
The bearing member includes a shaft supporting portion that supports an outer surface of the pressing member, and a holding portion that has an axial length larger than the shaft supporting portion, is fitted in a mounting hole of the body, and is held by the body.
Abuts on the shaft to regulate the advance of this shaft
And a spacer portion .

According to this automatic tensioner, the outer surface of the pressing member is supported by the shaft supporting portion of the bearing member, and the holding portion having an axial length larger than the shaft supporting portion is fitted and held in the mounting hole of the body. Runode hardly falls down bearing member, and between the bearing member and the pressing member, with the collision sound between the bearing member and the body can be greatly suppressed from occurring, the bearing
Since the member also serves as a spacer member, the number of parts can be omitted.
You .

[0008]

[0009]

[0010]

[0011]

In one embodiment of the present invention, the shaft of the automatic tensioner has a male thread portion screwed into a female thread portion of the pressing member, and a rear portion of the spacer portion is provided at a rear portion of the male thread portion. The collar part which contacts with is formed integrally. According to this configuration, as the shaft, which is prevented from advancing by the contact between the spacer portion and the collar portion, is rotated by the elastic force, the pressing member, which is prevented from rotating by the bearing member, advances and the Pressed by the endless transmission.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a schematic side view showing a use state of the automatic tensioner according to one embodiment of the present invention. A timing chain 4, which is a belt-shaped endless transmission, is stretched over the crankshaft 1, the camshafts 2, 3 of the engine.
Forwarded in the direction. The automatic tensioner T is fixed to a mounting portion 6 such as a cylinder head, a cylinder, or a crankcase in a state where the automatic tensioner T faces a chain guide 5 provided along a portion between the crankshaft 1 and the camshaft 2 of the chain 4. The pressing portion 8 a at the tip of the pressing member 8 is pressed against the pressure receiving portion 5 a of the chain guide 5. As a result, a pressing force in the tension direction acts on the chain 4, and a constant tension is applied to the chain 4.

FIG. 1 is a longitudinal sectional view of the automatic tensioner T. The body 7 which forms the main body of the automatic tensioner T is made of aluminum and has a front portion of the mounting hole 11 (right side in the figure).
Is provided with a steel pressing member 8 that moves forward and presses the pressure receiving portion 5a of the chain guide 5. The pressing member 8 is a front pressing portion 8 that directly contacts the pressure receiving portion 5a.
a and a rear main body 8b connected to the rear end of the pressing portion 8a via a pin 9. The main body 8b is supported by a bearing member 10 provided at the front of the body 7 so as to be able to advance and retreat.
As shown by a chain line in FIG. 3, the main body 8b is formed by forming an internal thread 8ba on the inner surface of a cylindrical body having a substantially elliptical cross section. At the rear end of the main body 8b, the bearing member 10
A thick portion 8c that fits into the inner periphery of a holding portion 10b described below and that can move in the axial direction is integrally formed.

While the body 7 is made of aluminum and the pressing member 8 is made of steel, the bearing member 10 is made of a different material, for example, a sintered material such as ceramics or resin. Fig. 2 (A)
As shown in a rear view, a partially cutaway side view, and a front view, respectively, in (C), a front portion is a shaft support portion 10a that supports an outer surface of the main body 8b, and a rear portion is a circular cross section formed in the body 7. And a holding body 10b fitted to the front of the mounting hole 11 and supported by the body 7. The shaft support 10a has an inner periphery 10ai having a cross-sectional shape of the main body 8a.
b is substantially the same oval as the outer circumference of b.
The pressing member 8 is inserted in a state in which the pressing member 8 can move forward and backward in the axial direction and is prevented from rotating. The axial length of the holding portion 10b is set to a sufficiently large length as compared with the shaft supporting portion 10a. Further, three fitting protrusions 10c are integrally formed on the outer peripheral surface of the shaft support portion 10a at equal intervals of a rotation angle of 120 °, and an outer surface of the fitting protrusion 10c has a circumferential direction. A groove 13 is formed, and the groove 13 is formed with C shown in FIG.
The character ring 12 is fitted.

On the other hand, as shown in FIG. 3, at the front end of the body 7, there are formed three fitting recesses 7a into which fitting protrusions 10c of the shaft support 10a are fitted. A circumferential groove 14 for fitting the C-shaped ring 12 is formed on the outer peripheral surface of the front end of the body 7. The holding portion 10b is fitted into the mounting hole 11 of the body 7, and the fitting protrusions 10c of the shaft supporting portion 10a are fitted into the fitting recesses 7a of the body 7, so that the bearing member 10 By fitting the C-shaped ring 12 from the groove 13 of the fitting projection 10c to the groove 14 of the body 7 in a state where the circumferential position is regulated, the bearing member 10 is prevented from coming off in the axial direction. Thus, the bearing member 10 is mounted on the front end of the body 7.
Note that the bearing member 10 may be press-fitted into the body 7, that is, tightly fitted without using the C-shaped ring 12.

A shaft 15 having an external threaded portion 15a whose front portion is screwed to the main body 8b is mounted in the mounting hole 11 of the body 7 in FIG.
The thrust washer 1 is attached to the step 11a formed at the rear of the
6 are locked. An elastic force is applied to the shaft 15 by a torsion spring 17 in a certain rotational direction. The torsion spring 17 is wound around the rear part of the shaft 15, one end of the torsion spring 17 is locked in a locking stopper groove 15 b formed at the rear end of the shaft 15, and the other end of the torsion spring 17 is connected to the middle part of the body 7. Is fixed to the locking groove 22 provided on the inner wall of the first member.

At the rear end of the body 7, the shaft 15
A stopper groove 7b that can be aligned with the stopper groove 15b is formed, and the torsion spring 17 can be held in a wound state twisted in a predetermined rotation direction by a stopper member 18 that is engaged over the stopper grooves 15b and 7b. In addition, the male screw portion 15 of the shaft 15
A collar portion 15c is integrally formed at a rear portion from the portion a.
The collar portion 15c abuts on the rear portion of the holding portion 10b of the bearing member 10 with the shaft 15 slightly advanced,
Regulate further progress. That is, the bearing member 1
The zero holding portion 10b also serves as a spacer (corresponding to the spacer 59 in FIG. 5) for restricting the shaft 15 from moving forward beyond a certain level. The flange 15c of the shaft 15 also serves as a conventional washer 58 (FIG. 5). With these combined structures, the number of parts of the automatic tensioner T can be reduced. At the rear end of the mounting hole 11 of the body 7, there is formed an internal thread portion 11b into which a stopper (not shown) for preventing oil leakage from the rear end side of the mounting hole 11 is screwed.

The body 7 has a pair of mounting pieces 7c protruding from its outer surface. The mounting piece 7c is applied to the mounting portion 6 such as the side wall of the cylinder block, and for example,
The bolt 2 is inserted through the bolt insertion hole 19 provided in the mounting piece 7c.
The automatic tensioner T is fixed to the mounting portion 6 by screwing the “0” into the screw hole of the mounting portion 6. Reference numeral 21 denotes an O-ring interposed between the mounting piece 7c and the mounting portion 6.

The automatic tensioner T is mounted so as to press the chain guide 5 by the following mounting procedure. First, the pressing member 8 is screwed into the male thread portion 15a until the rear end of the pressing member 8 comes into contact with the flange portion 15c of the shaft 15, and the torsion spring 17 is wound up in a predetermined rotation direction to form the stopper groove 7b at the rear end of the body 7. The stopper member 18 is engaged over the stopper groove 15b of the shaft 15 from above to hold the torsion spring 17 in a wound state, and the automatic tensioner T
Is fixed to the mounting portion 6.

Next, the stopper member 18 is removed from the stopper grooves 15b and 7b, and the wound state of the torsion spring 17 is released. At this time, the torsion spring 1
7, the shaft 15 rotates in a direction opposite to the predetermined rotation direction. The main body 8b of the pressing member 8 screwed into the external thread 15a of the shaft 15
Since the rotation of the shaft member 15 is prevented by the shaft supporting portion 10 a of the bearing member 10, the pressing member 8 advances with the rotation of the shaft 15 and is pressed against the pressure receiving portion 5 a of the chain guide 5. Thereafter, when the chain guide 5 is displaced to the pressing side, the spring back action causes
The pressing member 8 advances by the amount of the displacement, and the tension of the chain 4 is maintained constant.

In this automatic tensioner T, the bearing member 10
Since the holding portion 10b whose axial length is set sufficiently longer than the shaft supporting portion 10a is fitted in the mounting hole 11 of the body 7, the bearing member 10 does not become inclined.
It is stably mounted on the front part of the body 7. For this reason, even if the pressing member 8 vibrates due to an external force or vibration transmitted from the timing chain 4 to the automatic tensioner T via the chain guide 5 during operation of the engine, between the bearing member 10 and the pressing member 8, or Generation of collision noise between the bearing member 10 and the body 7 can be effectively suppressed. Furthermore, since the bearing member 10 is made of a different material from the aluminum body 7 and the pressing member 8, the occurrence of the collision noise can be further suppressed. The material of the bearing member 10 is particularly preferably resin for suppressing collision noise.

The bearing member 10 is reliably prevented from tilting,
In order to further enhance the effect of suppressing the generation of the collision sound, the axial length a (FIG. 2B) of the shaft support 10a is set to the minimum inner diameter b of the shaft support 10a (FIG. 2C). It is preferable to set it to 1/3 or more. On the other hand, in order to reduce the frictional resistance between the bearing member 10 and the pressing member 8 and to smoothly move the pressing member 8 forward and backward, the axial length of the shaft supporting portion 10a must be equal to that of the shaft supporting portion 10a. It is preferable that the diameter be equal to or smaller than the minimum inner diameter b.

As described above, according to the automatic tensioner of the present invention, the shaft supporting portion for supporting the outer surface of the pressing member is provided on the bearing member for supporting the pressing member for moving forward and pressing the endless transmission. A holding portion having an axial length larger than that of the shaft supporting portion and fitted in the mounting hole of the body and held by the body, and abutting on the shaft to regulate the advance of the shaft.
And a spacer section for controlling . Therefore , while the outer surface of the pressing member is supported by the shaft supporting portion of the bearing member, the holding portion of the bearing member is fitted and stably held in the mounting hole of the body. It is possible to greatly suppress the generation of collision noise between the bearing members and between the bearing member and the body, and the bearing member also serves as the spacer member.
Therefore, the number of parts can be omitted .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an automatic tensioner according to an embodiment of the present invention.

FIG. 2A is a rear view of a bearing member constituting the automatic tensioner, FIG. 2B is a half-cut side view of the bearing member,
(C) is a front view of the same, (D) is a plan view of a C-shaped ring constituting the automatic tensioner.

FIG. 3 is a front view showing the same bearing member mounted on the body of the automatic tensioner.

FIG. 4 is a side view showing a use state of the automatic tensioner.

FIG. 5 is a longitudinal sectional view showing an example of a conventional automatic tensioner.

[Explanation of symbols]

7: Body, 8: Pressing member, 8b: Main body, 8ba: Main body, 10: Bearing member, 10a: Shaft support, 10b: Holding part (spacer) , 11: Mounting hole, 15: Shaft,
15a: male thread, 15c: collar, 17: torsion spring, T: automatic tensioner .

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F16H 7/00-7/24 F16C 17/00-17/26

Claims (2)

(57) [Claims] 1. An automatic tensioner for applying tension by pressing a belt-shaped endless transmission in a tensioning direction, comprising: a pressing member which advances and presses the endless transmission; A shaft to which an elastic force is applied in a rotational direction, a body for accommodating the pressing member and the shaft in a mounting hole, and a rotation of the shaft based on the elastic force to prevent the pressing member from rotating. A bearing member for supporting the outer surface of the pressing member, the bearing member having an axial length larger than the shaft support portion, and being fitted into a mounting hole of the body. Holder that is held together by the body
Abuts on the shaft to regulate the advance of this shaft
An automatic tensioner having a spacer portion to perform. 2. The shaft according to claim 1, wherein the shaft is
It has a male thread part screwed into the female thread part of the pressing member,
Collar abutting the rear of the spacer on the rear of the male thread
Automatic tensioner with integrated part .