Tension lever

Abstract

To provide a tensioner lever which is simple in a structure, can constantly exert a proper reaction to a variety of tension variations accompanied by a chain behavior, and can reduce vibration and noise at the traveling of a chain.SOLUTION: A tensioner lever 100 according to the present invention comprises: a lever main body 110 having a shoe face S for slidably guiding a chain CH; a first pressing spring 120 which is configured so that a tip part of a first pressing arm part extending from one end of a first winding part abuts on the lever main body 110 as a first load point, and a tip part of a first support arm part extending from the other end of the first winding part abuts on, and is supported on a first support part W1 which is provided on an attachment face as a first support point R1; and a second pressing spring 130 which is supported on the lever main body 110 in a position different from the first pressing spring 120.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tension lever for slidingly guiding a running chain, and more particularly to a tension lever for a chain that slidingly guides a chain by pressing the shoe surface of a lever body against the chain side by a pressing mechanism.

Background Art

[0002] Conventionally, in a chain transmission device used for driving auxiliary machines of an automobile engine or the like, as a tension lever for removing slack in a chain and preventing vibration of the running chain, it is swingably attached to an attachment surface such as an engine block, and has a lever body having a shoe surface for slidingly guiding the chain, and a pressing mechanism using a torsion coil spring interposed between the lever body and the attachment surface and pressing the shoe surface toward the chain side is known (see, for example, Patent Documents 1 to 3).

[0003] In these tension levers, the winding portion of the torsion coil spring is loosely fitted on the outer peripheral surface of a boss portion formed to project from the base portion of the lever body toward the attachment surface side, the pressing arm portion extending from one end of the winding portion contacts the lever body, and the tip portion of the support arm portion extending from the other end of the winding portion is inserted into a spring holding hole formed in the attachment surface, and thus it is attached to the attachment surface. In such a tension lever, when the torsion coil spring is twisted by receiving a load from the chain, a reaction force corresponding to the amount of twist (the amount of angular change of the pressing arm portion) is obtained.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the conventional tensioner lever, since the tip of the support arm is fixed and the load from the chain is received at the tip of the pressing arm, there is a limit to the maximum allowable load of the torsion coil spring. Also, when receiving an excessive load, the torsion coil spring will undergo large elastic deformation, and there is a problem that the followability is poor with respect to rapid fluctuations in chain behavior. For this reason, when the chain rattles greatly or the resonance of the chain at high frequency occurs during engine startup, it is impossible to exert an appropriate reaction force, and it has been difficult to suppress fluctuations in chain behavior.

[0006] The present invention solves such problems, and its object is to provide a tensioner lever with a simple structure that can always exert an appropriate reaction force against various tension fluctuations associated with fluctuations in chain behavior, and can reduce vibrations and noise during the running of the chain.

Means for Solving the Problems

[0007] The present invention is a tensioner lever having a shoe surface for slidably guiding a chain, a lever body rotatably supported by a pivot shaft erected on a mounting surface, and a pressing mechanism interposed between the lever body and the mounting surface for pressing the shoe surface toward the chain side. The pressing mechanism includes a first pressing spring and a second pressing spring. The first pressing spring has a first winding portion loosely fitted in a cylindrical boss portion provided on the lever body, a first pressing arm portion extending from one end of the first winding portion and having a tip portion abutting against the lever body as a first load point, and a first support arm portion extending from the other end of the first winding portion and having a tip portion abutting against and supported by a first support portion provided on the mounting surface as a first support point. The second pressing spring is supported by the lever body at a position different from that of the first pressing spring, thereby solving the above problems. , the second pressing spring has a second winding portion loosely fitted in a second mounting portion provided on the lever body, a second pressing arm portion extending from one end of the second winding portion and having a tip portion contacting the lever body as a second load point, and a second support arm portion extending from the other end of the second winding portion and having a tip portion contacting and supported by a second support portion provided on the mounting surface as a second support point. to solve the above problems.

Effects of the Invention

[0008] According to the tension lever according to claim 1, by having two pressing springs with different characteristics of generating pressing force, it is possible to always exert an appropriate reaction force against various tension fluctuations accompanying the change in chain behavior. At the same time, since the second pressing spring is supported by the lever body at a position different from the first pressing spring, the structure becomes simple, and assembly and maintenance work can be easily performed. Also, by making the structure of the second pressing spring the same as that of the first pressing spring, the structure becomes simpler, and assembly and maintenance work can be easily performed.

[0009] According to the configuration described in claim 2, at least one of the first pressing spring and the second pressing spring is configured to generate an effective pressing force when the lever body is displaced by a predetermined amount or more after receiving a load of a certain magnitude or more from the chain. As a result, during normal times, only one of the pressing springs receives the load to improve followability, and when receiving an excessive load, both pressing springs receive the load, making it possible to increase the maximum load. 。 Claim 3 According to the configuration described in, it is possible to arrange the first pressing spring and the second pressing spring compactly. Claim 4 According to the configuration described in, it becomes easier to further improve the followability with respect to the change in chain behavior.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0011] Hereinafter, a tensioner lever according to an embodiment of the present invention will be described with reference to the drawings.

[0012] As shown in FIG. 1, the tensioner lever 100 is swingably attached to a pivot shaft Pa protruding from an attachment surface (not shown) such as an engine block (not shown), and slides and guides a chain CH spanned between a drive-side sprocket SP1 attached to a crankshaft and a driven-side sprocket SP2 attached to an accessory shaft, and appropriately holds the chain tension.

[0013] The tensioner lever 100 includes a lever body 110 formed of a synthetic resin or the like, and a first pressing spring 120 formed of a metal or the like interposed between the lever body 110 and the attachment surface.

[0014] As shown in FIG. 2, the lever body 110 includes a lever peripheral wall portion 111 formed so as to have a substantially hook shape in a side view.

[0015] As also shown in FIG. 3, the lever peripheral wall portion 111 has an arcuate peripheral wall portion 111a having a shape along a concentric circle circumference centered on the pivot shaft Pa, a substantially flat plate-shaped one-end peripheral wall portion 111b extending toward the chain CH continuously at one end of the arcuate peripheral wall portion 111a, a chain-side peripheral wall portion 111c having a shape along an arc that is convex toward the chain CH with one end smoothly continuous with the other end of the one-end peripheral wall portion 111b, a substantially flat plate-shaped anti-chain-side peripheral wall portion 111d extending facing the chain-side peripheral wall portion 111c with one end smoothly continuous with the other end of the arcuate peripheral wall portion 111a, and an other-end peripheral wall portion 111e having an arcuate shape that is smoothly continuous with the other ends of the chain-side peripheral wall portion 111c and the anti-chain-side peripheral wall portion 111d, and the outer surface of the chain-side peripheral wall portion 111c facing the chain CH is configured as a shoe surface S that slidably guides the chain CH.

[0016] The space surrounded by the lever peripheral wall portion 111 is partitioned into two space portions in the longitudinal direction by a reinforcing rib portion 112a provided between the chain-side peripheral wall portion 111c and the non-chain-side peripheral wall portion 111d. A first pressing spring accommodating portion H1 is formed by the space portion located at one end side, and a second pressing spring accommodating portion H2 is formed by the space portion located at the other end side.

[0017] In the portion of the lever peripheral wall portion 111 that defines the first pressing spring accommodating portion H1, a lever side wall portion 115 that covers the first pressing spring accommodating portion H1 is continuously provided on the end face on the side opposite to the mounting surface. A shaft hole 116 into which a pivot shaft Pa is inserted is formed in the lever side wall portion 115. Further, a cylindrical boss portion 117 that protrudes from the peripheral edge of the shaft hole 116 toward the mounting surface side is integrally formed on the lever side wall portion 115. By inserting the pivot shaft Pa into the boss portion 117, the lever main body 110 is supported by the mounting surface so as to be swingable (rotatable). The end face of the boss portion 117 on the mounting surface side is formed to protrude slightly toward the mounting surface side from the lever peripheral wall portion 111. Thereby, it is avoided that portions other than the end face of the boss portion 117 on the mounting surface side contact the mounting surface, and smooth swinging (rotation) of the lever main body 110 around the pivot shaft Pa is ensured.

[0018] A regulating protrusion portion 118 that regulates the movement of the first pressing spring 120 toward the mounting surface side is formed at the end portion of the outer peripheral surface of the boss on the mounting surface side. Thereby, in the state before the tension lever 100 is attached to the mounting surface, the first pressing spring 120 is prevented from coming off the lever main body 110, and in the state where the tension lever 100 is attached to the mounting surface, the first pressing spring 120 is prevented from interfering with the mounting surface.

[0019] The first pressing spring 120 has a first winding portion 121, a first pressing arm portion 122 extending from one end of the first winding portion 121, and a first support arm portion 123 extending from the other end of the first winding portion 121. The tip portion 122a of the first pressing arm portion 122 is bent toward the mounting surface side, and the tip portion 123a of the first support arm portion 123 is bent toward the side opposite to the mounting surface.

[0020] The first pressing spring 120 is provided on the lever main body 110 with the first winding portion 121 loosely fitted on the boss outer peripheral surface of the boss portion 117. The tip portion 122a of the first pressing arm portion 122 contacts the inner surface of the chain side peripheral wall portion 111c as the first load point P1, and at the same time, the tip portion 123a of the first support arm portion 123 led out to the outside of the lever main body 110 through the notch portion 114 formed in the arcuate peripheral wall portion 111a contacts the first support portion W1 provided on the mounting surface as the first support point R1 (see FIG. 1). The tip side portion of the first pressing arm portion 122 is locked to the spring locking rib portion 119 protruding from the inner surface of the chain side peripheral wall portion 111c, thereby ensuring an appropriate contact state of the tip portion 122a of the first pressing arm portion 122 with the inner surface of the chain side peripheral wall portion 111c. Therefore, as shown in FIG. 1, in the state where the tension lever 100 is attached to the mounting surface, the elastic force of the first pressing spring 120 rotationally biases the lever main body 110 toward the chain CH side around the pivot axis Pa, and presses the chain CH through the shoe surface S.

[0021] The tension lever 100 according to the present embodiment includes a second pressing spring 130 that is supported by the lever main body 110 at a position different from that of the first pressing spring 120 when receiving a load of a certain magnitude or more from the chain CH, and generates a pressing force that rotationally biases the lever main body 110 toward the chain CH side around the pivot axis Pa and presses the chain CH through the shoe surface S.

[0022] The second pressing spring 130 is disposed in the second pressing spring accommodating portion H2, and has a second winding portion 131, a second pressing arm portion 132 extending from one end of the second winding portion 131, and a second support arm portion 133 extending from the other end of the second winding portion 131. The tip portion 132a of the second pressing arm portion 132 is bent toward the mounting surface side, and the tip portion 133a of the second support arm portion 133 is also bent toward the mounting surface side.

[0023] The second pressing spring 130 is provided on the lever main body 110 with the second winding portion 131 loosely fitted on the outer peripheral surface of the second mounting portion 117a. The tip 132a of the second pressing arm portion 132 abuts against the inner surface of the chain side peripheral wall portion 111c as the second load point P2, and the tip 133a of the second support arm portion 133 led out to the outside of the lever main body 110 through the second notch portion 114a formed in the anti-chain side peripheral wall portion 111d abuts against the second support portion W2 provided on the mounting surface as the second support point R2 (see FIG. 1).

[0024] Both the first pressing spring 120 and the second pressing spring 130 are torsion coil springs, and are arranged so as to be compressed in opposite directions (so that the directions in which the pressing arm portion and the support arm portion extend from the winding portion are opposite to each other). In addition, the first pressing spring 120 is formed such that even when the chain CH is stopped, the lever main body 110 is rotationally biased toward the chain CH side about the pivot axis Pa by the elastic force and presses the chain CH through the shoe surface S. On the other hand, the second pressing spring 130 is not compressed when the chain CH is stopped, and is arranged to generate an effective pressing force when the lever main body 110 swings and displaces more than a predetermined amount under a load of a certain magnitude or more received from the chain CH.

[0025] In the present embodiment, the spring constant of the second pressing spring 130 is set to be larger than that of the first pressing spring 120. Normally, the first pressing spring 120 with a small spring constant flexibly absorbs the tension fluctuation, and when a load of a certain magnitude or more is received from the chain CH, the pressing force of the second pressing spring 130 with a large spring constant is applied, making it possible to take a larger maximum load. Note that when only the first pressing spring 120 operates and the pressing force of the second pressing spring 130 does not act, there may be a non-contact state at the second load point P2 or the second support point R2. However, by appropriately optimizing the outer diameter and shape of the second mounting portion 117a, the inner surface of the chain side peripheral wall portion 111c, or the shape of the second support portion W2, it is possible to operate without impact or damage when the pressing force of the second pressing spring 130 is applied.

[0026] As described above, one embodiment of the present invention has been described in detail. However, the present invention is not limited to the above embodiment, and various design changes can be made without departing from the present invention described in the claims.

[0027] For example, in the above-described embodiment, the spring constant of the second pressing spring 130 is set to be larger than that of the first pressing spring 120, but they may be the same, or conversely, the first pressing spring 120 may be made larger. Further, the first pressing spring 120 may be configured to generate an effective pressing force when the lever body 110 swings and displaces by a predetermined amount or more when receiving a load of a certain magnitude or more from the chain CH. Further, the first pressing spring 120 and the second pressing spring 130 may be integrally formed such that the tip 123a of the first support arm portion 123 and the tip 133a of the second support arm portion 133 are continuous, and the first support portion W1 and the second support portion W2 may be integrated.

Explanation of Reference Numerals

[0028] 100 ··· Tension lever 110 ··· Lever body 111 ··· Lever peripheral wall portion 111a ··· Arc-shaped peripheral wall portion 111b ··· One-end side peripheral wall portion 111c ··· Chain-side peripheral wall portion 111d ··· Anti-chain-side peripheral wall portion 111e ··· Other-end side peripheral wall portion 112a ··· Reinforcing rib portion 113 ··· Partition wall portion 114 ··· Notch portion 114a ··· Second notch portion 115 ··· Lever side wall portion 116 ··· Shaft hole 117 ··· Boss portion 117b ··· Second mounting portion 118 ··· Regulation protrusion portion 119 ··· Spring locking rib portion 120 ··· First pressing spring 121 ··· First winding part 122 ··· First pressing arm 122a ··· Tip 123 ··· First supporting arm 123a ··· Tip 130 ··· Second compression spring 131 ··· Second winding part 132 ··· Second pressing arm 132a ··· Tip 133 ··· Second supporting arm 133a ··· Tip CH ··· Chain H1 ··· First compression spring housing part H2 ··· Second compression spring housing part Pa ··· Pivot shaft P1 ··· First load point P2 ··· Second load point R1 ··· First support point R2 ··· Second support point S ··· Shoe surface SP1 ··· Driving side sprocket SP2 ··· Driven side sprocket W1 ··· First support part W2 ··· Second support part

Claims

1. A tension lever having a shoe surface for slidably guiding a chain, a lever body rotatably supported by a pivot shaft erected on a mounting surface, and a pressing mechanism interposed between the lever body and the mounting surface for pressing the shoe surface toward the chain side, wherein the pressing mechanism includes a first pressing spring and a second pressing spring, the first pressing spring has a first winding portion loosely fitted in a cylindrical boss portion provided on the lever body, a first pressing arm portion extending from one end of the first winding portion and having a tip portion contacting the lever body as a first load point, and a first support arm portion extending from the other end of the first winding portion and having a tip portion contacting and supported by a first support portion provided on the mounting surface as a first support point, the second pressing spring is supported by the lever body at a position different from that of the first pressing spring, and the second pressing spring has a second winding portion loosely fitted in a second mounting portion provided on the lever body, a second pressing arm portion extending from one end of the second winding portion and having a tip portion contacting the lever body as a second load point, and a second support arm portion extending from the other end of the second winding portion and having a tip portion contacting and supported by a second support portion provided on the mounting surface as a second support point. The tension lever is characterized by this.

2. The tension lever according to claim 1, wherein at least one of the first pressing spring and the second pressing spring is configured to generate an effective pressing force when the lever body is displaced by a predetermined amount or more upon receiving a load of a certain magnitude or more from the chain.

3. The tension lever according to claim 1 or claim 2, wherein the first load point as seen from the first winding portion of the first pressing spring and the second load point as seen from the second winding portion of the second pressing spring are arranged in a reverse positional relationship with respect to each other in the extending direction of the shoe surface.

4. The tension lever according to any one of claims 1 to 3, wherein the second pressing spring is arranged to generate an effective pressing force when the lever body is displaced by a predetermined amount or more upon receiving a load of a certain magnitude or more from the chain, and is configured to have a spring constant greater than that of the first pressing spring.

Images