JP2001153195A - Lever and arm of tensioner or the like - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an arm easily manufactured without reducing flexural strength as compared with a conventional I-shaped cross-sectional arm in an aluminum die-cast arm for constituting a tensioner lever. SOLUTION: When molding an arm 1 by a die-cast by using a split mold, the cross section is formed in a Z shape to eliminate the necessity of forming an outer peripheral surface 12 and an inner peripheral surface 9 as a taper surface so that a shoe 2 can be installed without secondarily working the outer peripheral surface 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tensioner lever for constantly applying a proper tension to a chain wound around a sprocket of a drive shaft and a driven shaft, and a chain guide and a chain damper disposed on the opposite side of the tensioner lever. It is related to the structure of.

[0002]

2. Description of the Related Art FIG. 7 shows a general chain drive device. A chain (a) has sprockets (d) and (e) attached to a drive shaft (b) and a driven shaft (c). The chain (a) is pressed by the tensioner lever (f), and an appropriate tension is constantly applied. Accordingly, the vibration of the chain (a) traveling along with the rotation of the two sprockets (d) and (e) is suppressed, and the vibration is transmitted to the driven shaft (c) without delay. Further, by suppressing the vibration, the impact force acting on the chain (a) is eliminated, and the life of the chain can be improved.

The tensioner lever (f) is pressed by the tensioner (g) and acts on the chain (a). There are various forms of the tensioner lever (f). A rubber or resin shoe is bonded to the arm, and the shoe is formed integrally with the arm. When the shoe is adhered to the arm, the shoe may be peeled off, and when the shoe is integrally formed with the arm, a molding die is required and the manufacturing cost is increased.

[0004] Therefore, the separately manufactured arm and shoe are
There is known a tensioner lever assembled and fixed without using an adhesive. The “chain guide rail provided with a synthetic resin shoe” according to Japanese Utility Model Publication No. 7-36201 has a structure in which the shoe is detachably attached to a shoe support member. That is, the end hook piece formed on the shoe is engaged with the chain running start end of the shoe support member, and the L-shaped side engaging piece formed on the shoe is engaged with and attached to the shoe support member. I have.

[0005] As described above, the shoe is detachably attached to the shoe support member (arm), and various other shoe attachment structures are known. For example, "the lifting prevention structure of the tensioner lever shoe" according to Utility Model Registration No. 2519476 is one in which the shoe is attached in a detachable structure.

The arm of a conventional tensioner lever is often die-cast using an aluminum alloy, but in order to achieve both strength and weight reduction, it is suitable to make the arm cross section I-shaped. (4-11
No. 9654). FIG. 8 shows a state in which a shoe (b) is attached to the outer periphery of an arm (a) having an I-shaped cross section.

The arm (a) having the I-shaped cross section is die-cast molded using a pair of split dies.
FIG. 9 shows a state in which the arm (a) is formed by the split dies (c) and (c). Die-cast arm with I-shaped cross section
(B) is extracted by opening the split molds (C) and (C),
A draft is provided so that the arm (a) can be easily separated from the split dies (c) and (c). That is, after molding, split mold (c),
Even when the arm (a) remains in one split mold (c) when opening (c), the arm (a) can be removed because of the draft angle. Conversely, if there is no draft, it is not easy to remove the arm (a) from the split mold (c).

FIG. 10 shows an arm having an I-shaped cross section removed from the split dies (C) and (C).
Due to the draft angle, the upper end surface has tapered surfaces (d), (d) ... inclined from neutral to both sides. Since the shoe (b) cannot be attached to the tapered surfaces (d) and (d), the tapered portion (the hatched portion in FIG. 10) at the upper end of the arm is removed by cutting. The upper end of this arm must be smoothly curved and machined in the longitudinal direction so that the shoe (b) can be attached, and cutting of the tapered portion requires many man-hours.

[0009]

As described above, the arm constituting the lever such as the tensioner has the above-mentioned problem. Problems to be solved by the present invention are these problems, and provide an arm that does not require secondary processing after die casting. Further, the present invention provides a lever such as a tensioner which has sufficient strength and rigidity, and on the other hand, allows easy attachment and detachment of a shoe and does not shift or come off.

[0010]

The arm constituting the lever of the tensioner or the like according to the present invention is made of aluminum die-cast, has a smoothly curved bow shape, and has a Z-shaped cross section. . That is, the outer peripheral piece and the inner peripheral piece are both curved, and the ribs connecting the outer peripheral piece and the inner peripheral piece are inclined and have a Z-shaped cross section. Even if it is configured as a Z-shaped cross section as described above, if the thickness of each part is the same, the second moment of area is not different from the conventional I-shaped cross section, and the bending strength of the arm does not decrease.

The arm having a Z-shaped cross section is die-cast, and the mold used is a pair of split dies, but the split die is not provided with a draft. That is, the arm formed without the draft by making the cross section Z-shaped can be easily removed from the split mold. Therefore, the tapered surface does not remain on the outer peripheral surface of the arm, and there is no need to cut and remove the secondary processing.

By the way, a shoe molded using a material such as rubber or resin is attached along the outer peripheral surface of the arm. The shoe mounting structure allows the arm to be easily attached to and detached from the arm, and has a positional shift. I try not to. However, the specific structure of the attachment is not limited. Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.

[0013]

FIG. 1 is an embodiment showing a tensioner lever according to the present invention. The tensioner lever includes a curved arm 1 and a shoe 2. The shoe 2 is attached to the outer periphery of the arm 1, and has a detachable structure so that the shoe 2 can be replaced if it is damaged due to wear or the like. I have. Here, the mounting structure of the shoe 2 is not limited, but in the tensioner lever shown in the figure, the keys 3 and 4 provided at both ends of the shoe 2 are engaged with the locking pieces 5 on the chain running start end side of the arm 1. And the locking pieces 6 on the opposite side. Then, on the side of the shoe 2, an L-shaped engagement piece 7,
7 are engaged with the side of the arm 1.

FIG. 2 is an enlarged cross-sectional view taken along the line AA of FIG. 1 and shows a specific example showing a cross section of the tensioner lever. As is clear from the figure, the cross section of the arm 1 has a Z-shape, and has an outer peripheral piece 8 and an inner peripheral piece 9 which are parallel to each other.
And the inner peripheral piece 9 are connected by an inclined rib 10.

In the outer peripheral piece 8 and the inner peripheral piece 9, the base side to which the rib 10 is connected is thicker than the distal end, so that the outer peripheral piece 8 and the inner peripheral piece are 9 has a higher bending strength by itself. The arm 1 is formed by die-casting using aluminum as a material, and a pair of split dies 11a and 11b are used as a forming die as shown in FIG.

In the split dies 11a and 11b, the cabin formed in a closed state has a Z-shaped cross section, but is not symmetrical with respect to the central axis, and the outer peripheral surface 12 has one split die 11b.
And the inner peripheral surface 13 has the other split mold 11a
Molded by the cabin. Therefore, no burr is generated on the outer peripheral surface 12 and the inner peripheral surface 13 in the gap between the split molds 11a and 11b, and it is not necessary to provide a tapered surface as a draft.

An arm having a Z-shaped cross section is formed by aluminum die-casting using split molds 11a and 11b.
When the arms 1a and 11b are opened, the other split mold 11a in contact with the inner peripheral surface 13 even if the arm remains on one split mold 11b side.
Are separated from each other, the arm having the Z-shaped cross section is easily detached from the split mold 11b. Further, the rib 10 connecting the outer peripheral piece 8 and the inner peripheral piece 9 is not continuous over the entire length, and a through hole can be provided in some places. Cast molding is possible.

By the way, the most required strength of the arm 1 is the bending strength, and the tension from the chain running on the shoe 2 is applied to the tensioner lever swinging about the shaft fitted in the shaft hole 14 in FIG. Acts and balances with the tensioner that presses the arm 1. Therefore, a large bending stress acts on the arm 1, and a strength that can withstand this stress is required.

FIG. 4 shows a comparison between the cross-sectional secondary moment of the conventional I-shaped section and the Z-shaped section according to the present invention. , And the rib thickness t, the two moments of area are equal, and the bending strengths are also equal. The bending strength does not decrease due to the Z-shaped arm cross section.

FIG. 5 shows a tensioner lever to which the shoe 2 is attached by another attachment structure. So, shoe
2 is in contact with the outer peripheral surface 12 of the arm. In this case, the projection 15 at the chain running start end is fitted into the groove, and the L-shaped engaging piece 1
6, 16 ... engage with the notch groove formed on the side of the arm,
The ridges fit into holes formed in the outer peripheral surface of the arm.

FIG. 6 is an enlarged sectional view taken along the line BB of FIG. (c) shows the case where the shoe 2 is attached to the arm 1, (a) shows the case where the shoe 2 is removed, and (b) shows the case where the shoe 2 is attached to the arm 1. A ridge 18 protrudes from the rear surface 17 of the shoe 2, and the cross section of the ridge 18 forms a right-angled triangle, and the side on which the L-shaped engagement piece 16 is formed rises vertically from the back 17. Surface 19. The protruding strip 18 fits into a hole 20 formed on the outer peripheral surface 12 of the arm 1, while the locking surface 19 is
The ridge 18 can be locked by abutting on the inner surface of the "0".

When removing the shoe 2 from the arm 1, if a pointed tool is inserted into the opposite side of the L-shaped engaging piece 16 to remove the ridge 18 from the hole 20, the shoe 2
The whole moves to one side of the L-shaped engagement and comes off. Conversely arm 1
When the shoe 2 is mounted on the arm 1, the L-shaped engaging pieces 16, 16... Are fitted into cutout grooves (not shown) formed on the side surface of the arm 1 as shown in FIG. If pressed in the direction, the ridge 18 can fit into the hole 20. In this case, the protrusion 15 at the chain running start end also fits into the groove.

As described above, the arm constituting the lever of the tensioner or the like according to the present invention is made of aluminum die-cast having a Z-shaped cross section, and the shoe is detachably attached to the outer periphery of the arm. Therefore, the following effects can be obtained.

[0024]

The arm constituting the lever such as the tensioner of the present invention is made of aluminum die-cast, and has a Z-shaped cross section. However, compared to a conventional arm having an I-shaped cross section, the secondary moment of area does not decrease, and the bending strength is sufficiently ensured.

By making the arm cross-section Z-shaped, die-casting can be performed using a split mold having no draft angle. Therefore, there is no need to perform secondary processing on the outer peripheral surface of the arm to which the shoe is attached. The man-hour for manufacturing the arm is reduced. The shoe of the lever is attached to the outer periphery of the arm, but is detachable and can be easily replaced if it is damaged due to wear or the like. Also, by engaging the L-shaped engaging piece provided on the shoe with the notch groove of the arm and fitting the ridge into the hole and locking it, the shoe does not come off the arm, and There is no surface. Of course, the shoe cannot move to the side.

[Brief description of the drawings]

FIG. 1 is an embodiment showing a tensioner lever of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along line AA of FIG.

FIG. 3 is a split mold for die-casting an arm having a Z section according to the present invention.

FIG. 4 is a moment of inertia of area of a Z-shaped section arm of the present invention and a conventional I-shaped section arm.

FIG. 5 shows another embodiment of the tensioner lever of the present invention.

6 is an enlarged cross-sectional view taken along the line BB of FIG.

FIG. 7 is a chain transmission including a tensioner device.

FIG. 8 is an I-shaped cross section showing a conventional tensioner lever.

FIG. 9 is a split mold for die-casting an arm having an I-shaped cross section.

FIG. 10 is a tapered surface formed on the outer periphery of an arm having an I-shaped cross section.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arm 2 Shoe 3 Key 4 Key 5 Locking piece 6 Locking piece 7 L-shaped engaging piece 8 Outer peripheral piece 9 Inner peripheral piece 10 Rib 11 Split mold 12 Outer peripheral surface 13 Inner peripheral surface 14 Shaft hole 15 Projection 16 L Figure-shaped engaging piece 17 Back face 18 Protrusion strip 19 Locking face 20 hole

Claims (3)

[Claims] 1. A lever such as a tensioner having a shoe mounted on the outer periphery of an arm, wherein the arm is made of aluminum die-cast, has a Z-shaped cross section, and the shoe is detachably mounted on the outer periphery of the arm. A lever such as a tensioner. 2. A lever such as a tensioner having a shoe attached to the outer periphery of the arm, wherein the arm is made of aluminum die-cast, has a Z-shaped cross section, and has a cutout groove formed on one side of the arm. In addition, a hole or a depression is provided on the outer peripheral surface and a groove is provided at a chain running start end portion. A notch groove is engaged with the projecting strip projecting from the back surface into the hole or the recess on the outer peripheral surface of the arm, and a protrusion provided at the chain running start end is fitted into the groove. Lever such as tensioner. 3. An arm constituting a lever such as a tensioner to which a shoe on which a chain travels is removably attached is formed by die-casting aluminum and has a Z-shaped cross section. Etc. arm.