JPH03260443A - Tensioner - Google Patents

Abstract

PURPOSE:To accomplish a casing in light weight and enhance its anti- abrasiveness and anti-corrosiveness by forming the casing from Al or Al alloy, and subjecting to a surface hardening process with Ni-P alloy plating. CONSTITUTION:A tensioner is composed of a casing 20, rotor 30, pressing member 40, spring 50, bearing 60, and bellows 70. The casing 20 as the mantle for these major components is made of Al or Al alloy for accomplishing lightweight construction, and the surface undergoes the hardening process with Ni-P alloy plating. This allows the casing 20 to the embodied in light weight, and its anti- abrasiveness and anti-corrosiveness are enhanced owing to the surface hardening process.

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. 6) of the casing 1, and a rotating body. 2
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 28 of the rotating body 2; The main parts are constituted by a torsion coil spring 4 that is inserted into the rotary body 2 and applies rotational force to the rotating body 2, and a seal bolt 6 that is screwed into the base end of the casing 2 via an O-ring 5. A cap 8 is properly attached 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 its rotation. This is converted into a propulsive force, and the pressing body 3 moves out 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 I rotatably supports the base end of the rotating body 2.
C is formed inside the casing 1. In order to reduce the weight of the tensioner, the casing is made of aluminum or an alloy thereof.

[Problems to be Solved by the Invention] If the casing 1 is formed of aluminum or its alloy for the purpose of weight reduction, the wear resistance and corrosion resistance will be poor, the life of the tensioner will be shortened, and the reliability will be reduced. You couldn't get some tensioner.

That is, the support recess 1C that supports the rotating body 2 is formed by the rotation of the rotating body 2 or by a return force (force pushed back into the casing 2) acting on the rotating body 2 via the pressing body 3. IC wear occurs when excessive load is applied to the IC.

Further, the contact portion between the bearing 9 and the casing 2 is worn out due to the rotational force of the spring 4 being transmitted to the bearing 9 that restrains the rotation of the pressing body 3, and a pressing force acting on the contact portion.

Further, in the cavity 1a of the casing 1, the base end surface of the spring 4 contacts the inner wall of the cavity 1a, or when the spring 4 is tightened and buckled, the spring 4 contacts the inner wall of the cavity 1a. and wear out.

Such wear weakens the supporting force of the rotating body 2 and the bearing 9, causing the rotating body 2 and the pressing body 3 to wobble or vibrate, making it impossible to obtain proper operation, and further reducing the strength of the casing itself.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a tensioner that has improved wear resistance and corrosion resistance and can be made lighter.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a system in which a rotating body 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, In the device for converting the rotational force of the rotating body into the axial propulsive force of the pressing body, the casing is formed of surface-hardened aluminum or aluminum alloy.

The surface hardening treatment may be nickel phosphorus alloy plating.

[Function] In the above configuration, since the casing is formed of aluminum or aluminum alloy, weight reduction can be achieved.

Further, by hardening the surface of the casing formed of aluminum or aluminum alloy, wear resistance and corrosion resistance are improved.

By performing the surface hardening treatment using nickel phosphorus alloy plating, good wear resistance can be obtained.

[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, a rotating body 30 and a pressing body 40 that are screwed into the cavity 21 of the casing 20.
A spring (torsion spring) 50 that applies rotational force to the rotating body 30, a bearing 60 that is attached to the tip of the casing 2o (the left end in FIG. 1) and restricts the rotation of the pressing body 40, and the casing 20 and the pressing It is provided with a bellows 70 which can be expanded and contracted to cover the space between the body 40 and the 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 20. The rotating body 30 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. 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 pressing body 40 includes a vibrator 42 having a female thread 41 formed on its inner surface, and a bushing shaft 43 fitted to the tip of the vibrator 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 6o 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 40 and the rotating body 30.
has been extrapolated to This spring 50 is fitted onto 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 50.

In such a structure, when a tribar or the like is inserted into the split slit 33 from the outside of the casing 20 with the seal bolt 80 removed and the rotating body 30 is rotated, the spring 5
It is possible to store rotational energy at zero. Note that the end 52 of the spring 50 on the rotating body side is connected to the rotating body 30.
After the spring 50 is inserted into the split slit 33, it is bent in the radial direction of the rotating body 3o, but such bending can prevent the above-mentioned radial displacement of the spring 50 during operation, and the spring 50 is bent in the radial direction. 50 stable operation is ensured.

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
Attached to the tip of the FIGS. 4 and 5 show the bearing 60 and its mounting structure. The bearing 60 has a bearing hole 62 formed in its center portion, and retaining 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 restricts rotation against the rotational force of the rotating body 30. For this reason, the casing 2 corresponds to the engagement piece 63.
Engagement grooves 24 are formed at 90 degree intervals on the distal end surface of the 0, and the rotation is restrained by fitting the engagement pieces 63 into the engagement grooves 24. In this case, the depth of the engagement groove 24 of the casing 20 is larger than the thickness of the engagement 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.

Some of the engagement grooves 24 in the casing 20 are provided with stiffness 50.
One end 51 of is pulled out to engage with the casing 20 described above.

The main components of the tensioner are formed in this way, and the casing 20, which is the outer shell of this main component, is made of aluminum or aluminum alloy to reduce weight, and its surface is hardened. .

For this surface hardening treatment, for example, Kanigen (trade name) plating can be employed. This Kanigen plating is a nickel-phosphorus alloy plating applied to the casing surface.

Plating consists of a pretreatment process, a plating reaction process, and a heat treatment process. The pretreatment step is to wash the molded casing to activate its surface, and removes fats and oils adhering to the surface by trichlene washing, alkaline degreasing, pickling, and the like. The plating reaction step is a step in which the casing cleaned in the above step is immersed in a plating solution at about 95° C. to perform a plating reaction. At this time, in the plating reaction, the hypophosphite anions and nickel cations in the plating solution continue to generate a nickel-phosphorous alloy due to the self-decomposition of nickel. As a result, the entire surface of the casing 1 is coated with the nickel hot alloy, and the plating is completed. Further, the heat treatment step is a step of increasing the hardness of the plating layer produced in the plating reaction step, and the hardness of the plating layer can be increased by increasing the heat treatment temperature. Generally, heat treatment at 400°C or higher provides wear resistance equal to or higher than that of hardened chromium. The surface-hardened casing l is made of aluminum or aluminum alloy to reduce its weight, and the surface-hardened casing improves wear resistance and corrosion resistance.

The support recess 23 that rotatably supports the rotary body 30 is a part that is easily worn due to the rotation of the rotary body 30 and the return force acting on the rotary body 30 via the pressing body 40. The treatment provides sufficient wear resistance. The engagement groove 24 into which the engagement piece 63 of the bearing 60 is fitted is formed by the pressing body 4
The pressing force of the engagement piece 63 due to the rotational force of the rotating body 30 transmitted through the groove 24 acts directly on the side wall of the engagement groove 24, and the side wall is easily worn. Abrasion resistance is improved by the surface hardening treatment described above. Also,
The inner wall of the cavity 1a is a place where it is easy to wear due to contact due to buckling during tightening of the spring 50 or contact with the proximal end surface of the rib 50, but the surface hardening treatment also reduces the wear resistance of this place. will improve.

Furthermore, although the mounting hole 22 of the casing 20 is a location where the tightening force of the bolt acts and is likely to wear out, the wear resistance of this location is also improved by the surface hardening treatment.

The casing 1, which has been surface hardened in this manner, can have sufficient wear resistance even in the above-mentioned locations where wear is likely to occur, without the use of separate members such as spacers.

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 convex line 71 is formed on the inner surface of the end of the bellows 70 on the pressing body 40 side, and this convex line 71 is fitted into a corresponding concave line 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 2o and whose tip is slightly bent inward.After the base side is inserted into the casing 20, the cap 73 It is attached to the casing 20 by caulking 74 a predetermined position on the outer peripheral surface of the casing 20 . The bellows 70 is connected to a bent portion at the tip of the cap 73. Furthermore, casing 20
A circumferential groove 26 is formed on the outer surface, and a seal ring 75 is wound around this circumferential groove 26. The seal ring 75 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, it comes into close contact with the inner surface of the cap flap and the outer surface of the casing 20, sealing 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. Therefore, when attaching the cap 73, it is not necessary to press-fit the cap to maintain airtightness of the part, and there is no need for a high degree of dimensional accuracy for press-fitting.

Therefore, processing can be performed easily and productivity is improved.

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.

In addition, 40a and 60a in FIG. 1 are the pressing bodies 40, respectively.
．． and a lubricating oil circulation path established in the bearing 60, and these circulation paths 40a and 60a allow the lubricating oil filled inside to be evenly circulated inside the casing 20.

Further, the present invention is not limited to the case where the entire surface of the casing 20 is hardened as described above, but also the case where the casing 20 is hardened.
It is also possible to apply a hardening treatment to at least the parts of 0 that are prone to wear.

[Effects of the Invention] As explained above, since the present invention is made of a surface-hardened aluminum alloy, it is possible to reduce the weight and provide sufficient wear resistance and corrosion resistance for actual operation.

This eliminates the need for separate members such as spacers even in areas of the casing that are prone to wear, which further improves weight reduction and facilitates assembly due to the small number of parts.

[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, FIG. 6 is a sectional view of a conventional device. 20...Casing, 30...Rotating body, 40...
Pressing body, 50... Spring, 60... Bearing, 70...
Bellows. DingOO 7 Figure 2

Claims (2)

[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. 1. A tensioner for converting a tensioner, characterized in that the casing is formed of surface-hardened aluminum or aluminum alloy. (2) The tensioner according to claim 1, wherein the surface hardening treatment is nickel-phosphorus alloy plating.