JPH03260444A - Tensioner - Google Patents

Abstract

PURPOSE:To prepare a high precision bottom-equipped bearing body without any special machine processing and prevent wear of a casing by forming the bearing body with its cylindrical part and bottom part separately, and locating it between a rotor and the casing. CONSTITUTION:The shank 32 of a rotor 30 is borne by a casing 20 at its recess 23 for rotary supporting. A bottom-equipped bearing body 82 is provided between these shank 32 and recess 23. This is formed from a combination of a cylindrical part 82a and a bottom part 82a, which are formed separately, and a projection 82d is provided on the peripheral wall of the cylindrical part 82b. A channel- shaped groove A is formed at the bottom side-face of the cylindrical part 82b, and the bottom 82a will be fitted in the channel-shaped groove A owing to a projection B formed at the periphery. Thereby the corner C of the bottom 82a will be at right angle accurately, and a high precision bottom-equipped cylinder is achieved without resorting to any special machine processing. Further the casing 20 is well prevented from wearing, and the rotor rotating can be supported stably.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a tensioner that applies a constant tension to a chain or timing belt that drives the camshaft of the engine of a two-wheel vehicle or a four-wheel vehicle. .

[Prior Art] Tensioners such as chain tensioners and belt tensioners are used to press the chain or belt in a certain direction to maintain a certain tension when the chain or belt becomes loose due to stretching or abrasion during use. is used to maintain the

A conventional example of this tensioner is shown in FIG.

The tensioner includes a casing 1 in which an axial cavity 1a is formed, a shaft-shaped rotating body 2 rotatably inserted into the base side (right end side in FIG. 8) of the casing l, and a rotating body. a pressing body 3 that is screwed onto the tip of the casing 1; one end 4a of the rotating body 2 is inserted into the engagement groove 2a of the rotating body 2; The main parts are constituted by a torsion coil spring 4 inserted into the rotor 1b and applying rotational force to the rotating body 2, and a seal bolt 6 screwed into the base end of the casing 1 via a circle ring 5. A cap 8 is fixed to the tip of the pressing body 3 by a spring pin 7, and the cap 8 comes into contact with a chain, belt, etc., and is pressed so that the chain or belt maintains a constant tension. Further, the pressing body 3 has a substantially oval outer periphery, and is inserted into a bearing 9 in which a bearing hole of the same shape is formed to restrict rotation.
As a result, the rotational force of the rotating body 2 is converted into the propulsive force of the pressing body 3, so that the pressing body 3 advances to the outside of the casing.

In such a tensioner, the rotation of the rotating body 2 for propelling the pressing body 3 is an important movement element, and the support recess 1 rotatably supports the base end of the rotating body 2.
c is formed inside the casing 1. The supporting recess 1c is formed so that its inner diameter is the same as the outer diameter of the rotating body 2, and is machined with high precision so that the rotating body 2 can be stably operated with little vibration. .

"Problems to be Solved by the Invention" However, since the support recess 1c is provided in a location that is difficult to machine, it requires a great deal of effort and skill to precisely machine the support recess 1c inside the casing 1. Moreover, even with precision machining, it is difficult to smoothly rotate and stably support the rotating body, making it impossible to provide good rotational support for the rotating body. The recess IC is easily worn out, and this wear weakens the supporting force of the rotating body, causing problems such as rattling and vibration during rotation.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tensioner that does not require highly precise machining of the support recess and can stably support the rotation of a rotating body.

[Means for Solving the Problems] The present invention provides a system in which a rotating body biased to rotate by a spring and a pressing body whose rotation is restrained by a bearing are inserted into a casing in a screwed state, and the rotational force of the rotating body is In the device for converting force into a propulsive force in the axial direction of a pressing body, the device includes a cylindrical part that is fitted onto a base end of the rotating body, and a bottom part that is formed separately from the cylindrical part and covers an end surface of the base end. A bottomed bearing body is provided between the rotating body and the casing and rotatably supports the rotating body.

[Function] In the above configuration, the bottomed bearing body interposed between the rotating body and the casing stably supports the rotation of the rotating body without co-rotating with the rotating body, and also supports the rotation of the rotating body and the casing. Designed to prevent direct contact. In addition, by forming the cylindrical portion and the bottom portion that constitute the bottomed bearing body separately and joining them together, a high-precision bottomed bearing body can be obtained without requiring any special machining. Embodiment] FIGS. 1, 2, and 3 show the overall configuration of an embodiment of the present invention. The tensioner includes a casing 20 in which an axial cavity 21 is formed, and a rotating body 30 and a pressing body 40 that are inserted in a screwed state;
A spring (torsion spring) 50 that applies rotational force to the rotating body 30, a bearing 6° that is attached to the tip of the casing 20 (the left end in FIG. 1) and restricts the rotation of the pressing body 40, and the casing 20. It is provided with a bellows 70 that can be expanded and contracted to cover the space between the pressing body 40 and the pressing body 40 .

The casing 20 is to be attached to equipment such as an engine (not shown), and a mounting hole 22 for this purpose is formed in the outer part. Further, a seal bolt 80 is screwed into the base end (the right end in FIG. 1) via a packing 81 to maintain airtightness on the base end side.

The rotating body 30 is rotatably supported within the casing 2o. The rotating body 3o is formed by connecting a male threaded portion 31 on the distal end side and a shaft portion 32 on the proximal end side, and a pressing body 40 is screwed into the male threaded portion 31 to transmit rotational force. . Further, the shaft portion 32 is supported within the support recess 23 of the casing 20 for rotational support. In this case, a bottomed bearing body 82 is provided between the shaft portion 32 and the support recess 23 of the casing.

The structure of this bottomed bearing body 82 is shown in FIG. The bottomed bearing body 82 is formed by combining a separately formed cylindrical portion 82b and a bottom portion 82a. The cylindrical portion 82b is a cylindrical body,
The outer diameter of the cylindrical portion 82b is formed to a size that allows it to be fitted into the support recess 23 of the casing 2°, and the inner diameter of the cylindrical portion 82b is formed to a size that allows the base end portion of the shaft portion 32 of the rotating body 3o to be rotatably fitted. It is something that will be done.

On the outer circumferential wall of the cylindrical portion 82b, there are protrusions 82 at intervals of 90'.
d is provided. The protrusion 82d is tapered from the upper edge of the opening of the cylindrical portion 82b toward the bottom portion 82a. Further, U-shaped grooves A (opening downward in the drawing) are formed at intervals of 90' on the lower end side end surface of the cylindrical portion 82b. On the other hand, the bottom portion 82a is formed into a disk having an outer diameter approximately equal to the inner diameter of the cylindrical portion 82b, and a protrusion B that fits into the U-shaped groove A is formed on the outer periphery of this disk. In this way, the cylindrical parts 82b and 82a are formed separately, and by fitting the protrusion B of the bottom part 82a into the U-shaped groove A of the cylindrical part 82b and joining the bottom part 82a to the cylindrical part 82b, a bottomed bearing is formed. 82 is formed. The bottomed bearing body 82 formed in this manner has a corner C of the bottom portion 82a at an accurate right angle, and becomes a highly accurate bottomed cylindrical body without requiring any special machining. This bottomed bearing body 82 is connected to the casing 20
By being press-fitted into the support recess 23, the protrusion 82d bites into the side wall of the recess 23 and is prevented from rotating. As described above, since the projection 82d is formed to prevent the rotation of the bottomed bearing body 82, at least one projection 82d may be formed.

The bottomed bearing bodies 821 and 822 shown in FIGS. 7 and 8 are modified examples of the bottomed bearing body, and have the same external shape as the bottomed bearing body 82. Instead, the slit 821d and the through hole 822d are connected to the cylindrical portion 82.
It is formed in b. This bottomed bearing body 821. and 82
2 is assembled into a mold, and during insert molding of the casing 2o, a part of the casing is fitted into the slit 821d and the through hole 822d to be integrated with the casing 20, thereby preventing rotation. The bottomed bearing bodies 823 and 824 shown in FIGS. 9 and 10 are yet another modification of the bottomed bearing body, and differ from the aforementioned bottomed bearing body 82 only in the structure of the cylindrical portion.

That is, the bottomed bearing bodies 823 and 824 are formed by coupling separately formed cylindrical parts 823b and 824b and the bottom part 82a, and this coupling structure is the same as that of the bottomed bearing body 82.

In this case, as shown in FIG.
3d are arranged in series. The cylindrical body of the cylindrical portion 823b corresponds to the cylindrical portion 82b of the bottomed bearing body 82, and the flange portion 823b is formed so that its outer diameter approximately matches the inner diameter of the cavity 21, and after being installed in the casing 20. covers the bottom surface of the cavity 21.

Engagement recesses 823e are provided on the outer periphery of the flange portion 823d at intervals of 90'. This engagement recess 823e
By fitting a portion of the casing 20 inside, the bottomed bearing body 823 is prevented from rotating. Engagement recess 82
A portion of the casing 20 is inserted into the bottomed bearing body 82.
During the insert molding of the casing 20 in which 3 is incorporated into the mold, not only is it performed simultaneously with the casing molding, but also a protrusion (not shown) is formed in advance on the inner wall of the cavity 21.
The engaging recess 823e may fit into the engaging recess 823e.

Further, as shown in FIG. 10, the cylindrical portion 824b of the bottomed bearing body 824 has a flange portion 824e connected to the outer periphery of the opening of the small span portion 824d, and a large diameter portion formed rising along the outer periphery of the flange portion 824e. It is formed from the intermediate portion 824C.

The small diameter cylindrical portion 824d corresponds to the aforementioned bottomed bearing body 82b. The large-diameter cylindrical portion 824C is formed so that its outer diameter substantially matches the inner diameter of the casing inner cavity 21, and its inner diameter is formed to a size that allows the base end of the spring 50 to be loosely inserted therein. Further, a through hole 824f is formed in the large diameter cylindrical portion 824C.

A part of the casing 20 is fitted into this through hole 824f to prevent the support member 86 from rotating, and the fitting is performed when the casing 20 is insert-molded.

Such bottomed bearing bodies 821, 822° 823, and 8
Similarly to the bottomed bearing body 82, the bottomed bearing body 82 is also formed by combining a separately formed cylindrical part and a bottom part, so that the inner corner C of the bottomed bearing body (the boundary between the cylindrical part and the bottom part) is a precise right angle, resulting in a highly accurate bottomed bearing body that is suitable for stable rotation of the rotating body 30 without any special machining.

Note that an escape hole 82c is provided in the center of the bottom portion 82a, which is used for assembling the tensioner, tightening the spring 50, and the like. Such a bottomed bearing body 82 is fitted into the support recess 23 of the casing 20, and the shaft portion 32 of the rotating body 30 is inserted into the space 82b. That is, the bottomed bearing body 82 is connected to the support recess 23 of the casing 20 and the rotating body 3.
The rotating body 30 is interposed between the shaft end of the casing 2 and the shaft end of the casing 2.
Since the casing 20 is prevented from coming into direct contact with the rotating body and is not worn out by the rotation of the rotating body, stable rotational support can be achieved. Since it can be molded from material, it can be made lighter. Further, the cylindrical portion 82b of the bottomed bearing body 82 is connected to the shaft portion 3 of the rotating body 30.
Since it extends so as to cover the outer surface of 2, and the supporting force is increased, even more stable rotational support can be achieved. Further, the bottomed bearing body 823 also covers the bottom surface of the cavity 21 with the flange portion 823d to prevent this bottom surface from being worn out due to contact with the base end surface of the spring 50. In addition to preventing wear on the bottom surface, the large diameter cylindrical portion 82
4c covers the side surface of the cavity 21 to prevent contact due to buckling of the spring 50, thereby preventing wear on the side surface.

Incidentally, an axial split slit 33 is formed in the shaft portion 32 of the rotary body 30, and as will be described later, the rotary body 30 is engaged with a spring 50 and is biased to rotate.

The suppressor 40 includes a pipe portion 42 having a female threaded portion 41 formed on its inner surface, and a bush shaft 43 fitted to the tip of the pipe portion 42 .

The vibrator 42 is screwed into the male threaded portion 31 of the rotating body 30 to transmit the rotational force of the rotating body 30, and is also inserted into the bearing 60 in a rotationally restrained state to convert the rotational force of the rotating body 30 into propulsive force. It is something. On the other hand, the tip of the bushing shaft 43 extends outward from the casing 20, and the tip surface comes into contact with a chain, belt, etc. directly or via a roller that presses them. This maintains tension in chains, belts, etc.

The spring 50 is connected to such a pressing body 4o and the rotating body 30.
has been extrapolated to This spring 5o is inserted into the pressing body 40 and the rotating body 30 when they are in a screwed state, and the extrapolated portion extends from the inside to the outside of the rotating body 30.
, a pressing body 40, and a spring 5o.

Here, one end 51 of the spring 50 is bent into an oval shape to engage with the casing 20, and the other end 52 is inserted into the split slit 33 of the rotating body 30 to engage with the rotating body 30. The goal is to ensure consistency. Therefore, when the rotary body 30 is rotated by inserting a driver or the like into the split slit 33 from the outside of the casing 2o with the seal bolt 80 removed, rotational energy can be stored in the spring 50.

The bearing 60 restricts the rotation of the pressing body 40, and is prevented from being pulled out by the circlip 61 so that the casing 20
Figures 4 and 5 show the structure of this bearing 60 and its mounting structure. The bearing 60 has a bearing hole 62 formed in its central portion, and engagement pieces 63 formed at 90 degree intervals in its outer portion. Bearing hole 62
The pressing body 40 is formed into a substantially oval shape in which both sides of a circle are cut parallel to each other, and the outer shape is the same.
The vibration part 42 is inserted into the bearing hole 62 to restrain the rotation of the pressing body 40. On the other hand, the engagement piece 63 resists the rotational force of the rotating body 30 and performs rotational restraint. For this reason, the casing 2 corresponds to the engagement piece 63.
0, retaining grooves 24 are formed at 90 degree intervals, and the rotation is restrained by fitting the engaging pieces 63 into the engaging grooves 24. In this case, the depth of the engagement groove 24 of the casing 20 is larger than the thickness of the retaining piece 63, and the bearing 60 is attached to the casing 20.
It is installed slightly recessed from the tip.

A clip groove 25 protruding beyond the bearing 60 and into which the circlip 61 is fitted is provided on the inner surface of the casing 20.
is formed.

Furthermore, a spacer 9 is provided between the bearing 60 and the casing 20.
0 is inserted. The spacer 90 is inserted between the bearing 60 and the casing 20 at the opposing portion, and in particular, the portion of the bearing 60 corresponding to each engagement piece 63 is bent into a U-shape so as to wrap around each engagement piece 63. As a result, the engaging piece 63
and the engagement groove 24 of the casing 20. In the spacer 90 having such a structure, the wide surface of the spacer 90 prevents the pressing force of the retaining piece 63 due to the rotational force of the rotating body 30 transmitted through the pressing body 40 from directly acting on the casing 20. Therefore, the engagement piece 63 and the casing 2
This makes it possible to prevent the end faces of the engagement grooves 24 from being worn out.

In this way, by using the spacer 90 for the bearing 60 and using the support member 82 of the rotating body 30, the casing 2
0 can be constructed using a material with poor wear resistance such as aluminum or synthetic resin, and even in this case, the tensioner can prevent wear of the casing 20 at the mounting portion of the bearing 60 and the shaft portion of the rotating body 30. It operates without any problems and is lightweight. In addition, one end 51 of the spring 50 is extracted from a part of the engagement groove 24 in the casing 20 to be engaged with the casing 20 described above.

Next, the bellows 70 is passed between the bush shaft 43 of the pressing body 40 and the casing 20, and covers the space between them. A protruding line 71 is formed on the inner surface of the end of the bellows 7o on the pressing body 40 side.
is fitted into a corresponding groove 44 formed on the outer surface of the bush shaft 43. The end portion on the pressing body 40 side is sealed by winding the garter spring 72 from the outside. On the other hand, the end on the casing side is connected to a cap 73 attached to the casing 20. Note that this connection can be made by any suitable means such as adhesion or welding. The cap 73 is made of a substantially cylindrical hard material whose base side has an inner diameter approximately equal to the outer diameter of the casing 20 and whose tip is slightly bent inward. It is attached to the casing 20 by caulking 74 a predetermined position on the outer peripheral surface of the casing 20 . The bellows 7° is connected to the bent portion at the tip of the cap 73 6 Furthermore, the casing 2
A circumferential groove 26 is formed on the outer surface, and a seal ring 75 is wound around the circumferential groove 26. Seal ring 7
5 is made of an elastic body, and when the cap 73 is attached to the casing 20 while being wound around the circumferential groove 26, the cap 7
3 and the outer surface of the casing 20 to seal the space between them. Therefore, intrusion of dust from the outside and leakage of the lubricating oil sealed inside the casing 20 are prevented. With the structure using such a seal ring 75, airtightness between the cap 73 and the casing 20 can be ensured.

In FIGS. 2 and 3, 100 is a stopper that locks the pushing body 40 in front of the tensioner assembly. This stopper 100 is removed after the tensioner is installed at the location where it is used.

Note that 40a, 60a, and 90a in FIG. 1 are circulation paths for lubricating oil established in the pressing body 40, bearing 60, and spacer 90, respectively, and the inside is filled with these circulation paths 40a, 60a, and 90a. Lubricant oil casing 2o
It is designed to circulate evenly inside.

[Effects of the Invention] As explained above, the present invention has a structure in which the inner corner of the bottom (the boundary between the cylinder and the bottom) is formed separately from the bottomed bearing body that supports the rotation of the rotating body. We were able to obtain a high-precision bottomed bearing body that has an accurate right angle and is suitable for stable rotation of a rotating body without any special machining. Furthermore, the casing is not worn out by the rotation of the rotor, and can stably support the rotation of the rotor.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention, FIGS. 2 and 3 are a plan view and a side view thereof, and FIGS. 4 and 5 are perspective views and sectional views showing a bearing mounting structure, 6 to 8 show the bottomed bearing body, each figure (a) is a central sectional view,
Each figure (b) shows a bottom view, FIGS. 9 and 10 show another bottomed bearing body, each figure (a) shows a top view, each figure (b) shows a central sectional view, and each figure (c ) is a bottom view, and FIG. 11 is a sectional view of the conventional example. 20...Casing, 30...Rotating body, 40...
Pressing body, 50... Spring, 60... Bearing, 70...
Bellows, 82.821, 822, 823, 824--bottomed bearing body, 82a--bottom portion, 82b, 823b, 824b--cylindrical portion.

Claims (1)

[Claims] (1) A rotating body that is rotationally biased by a spring and a pressing body whose rotation is restrained by a bearing are inserted into a casing in a screwed state, and the rotational force of the rotating body is converted into an axial propulsive force of the pressing body. In the converting device, a bottomed bearing body is formed by combining a cylindrical part that is fitted onto the base end of the rotating body and a bottom part that is formed separately from the cylindrical part and covers an end surface of the base end. A tensioner that is provided between a body and a casing and rotatably supports a rotating body.