JP2024142586A - Tensioner lever structure - Google Patents

Abstract

To provide a tensioner lever structure for enabling the rigidity to be secured even when there is no space on the back side of a slide surface while enabling weight saving.SOLUTION: A tensioner lever structure (TS) is provided. The tensioner lever structure (TS) includes a tensioner lever (10) which slides having a slide surface (10a) where a chain (CH) slides. The tensioner lever (10) has a wall part (11) erected from the slide surface (10a) in a height direction of the chain (CH). The wall part (11) has a high wall portion (11b) higher than a height (h) of the chain (CH), and a low wall portion (11a) lower than the height (h) of the chain (CH).SELECTED DRAWING: Figure 3

Description

The present invention relates to a tensioner lever structure.

Conventionally, tensioner levers are known that press against a cam chain to provide the appropriate tension to the cam chain (see, for example, Patent Document 1). In such tensioner levers, ensuring rigidity can be important in order to suppress chain flutter and reduce noise. In the technology disclosed in Patent Document 1, the rigidity of the tensioner lever is ensured by extending a wall portion on the tensioner lever.

JP 2020-186776 A

In the above-mentioned conventional technology, a wall portion is provided on the opposite side of the sliding surface along which the cam chain slides (i.e., the back side of the sliding surface). However, there may be cases where it is difficult to provide a wall portion on the back side of the sliding surface due to factors such as the engine configuration.

Furthermore, in recent years, there has been an emphasis on ensuring that more people have access to affordable, reliable, sustainable and advanced energy. From the perspective of contributing to energy efficiency, it is necessary not only to ensure the rigidity of the tensioner lever, but also to reduce its weight.

The present invention aims to provide a tensioner lever structure that can ensure rigidity even when there is no space behind the sliding surface, and that can also be made lighter. This will ultimately contribute to energy efficiency.

As a means for solving the above problem, the first aspect of the present invention is a tensioner lever structure (TS) including a tensioner lever (10) that swings and has a sliding surface (10a) on which a chain (CH) slides, the tensioner lever (10) having a wall portion (11) erected in the height direction of the chain (CH) from the sliding surface (10a), the wall portion (11) having a high wall portion (11b) higher than the height (h) of the chain (CH) and a low wall portion (11a) lower than the height (h) of the chain (CH).

According to this configuration, a wall portion is provided on the chain side of the tensioner lever (sliding surface) to improve the rigidity of the tensioner lever. This ensures the rigidity of the tensioner lever even when there is no space to provide a wall portion on the back side of the tensioner lever (sliding surface). In addition, by having a low wall portion and not making the entire wall portion a high wall portion, the weight of the tensioner lever can be reduced. Therefore, it is possible to provide a tensioner lever structure that ensures rigidity even when there is no space on the back side of the tensioner lever, and that can also be made lightweight. This in turn contributes to energy efficiency.

The second aspect of the present invention is characterized in that, in the first aspect, the tensioner lever (10) further has a pressure-receiving portion (12) that is pressed by a tensioner lifter (50), and the pressure-receiving portion (12) and the high wall portion (11b) are aligned in the pressing direction in which the tensioner lifter (50) presses the pressure-receiving portion (12).

This configuration improves the rigidity of the portion of the tensioner lever that is pressed by the tensioner lifter.

The third aspect of the present invention is characterized in that, in the second aspect, the tensioner lever (10) is further provided with a pivot shaft (20) that swingably supports the tensioner lever (10), and the boundary portion (11c) located at the boundary between the high wall portion (11b) and the low wall portion (11a) is located between the pivot shaft (20) and the pressure receiving portion (12).

With this configuration, the low wall portion is located on the pivot shaft side, and the high wall portion is located on the pressure-receiving portion side. This allows the tensioner lever to be more reliably lightweight and have high rigidity as a whole by providing high wall portions in areas where rigidity is required and low wall portions in areas where rigidity is not required.

The fourth aspect of the present invention is the third aspect, characterized in that the boundary portion (11c) has an inclined portion (11d) whose height gradually increases from the low wall portion (11a) toward the high wall portion (11b).

This configuration makes it possible to avoid sudden changes in stiffness at the boundary between the low wall and high wall sections.

The fifth aspect of the present invention is any one of the first to fourth aspects, characterized in that the height (H) of the high wall portion (11b) is 1.2 to 1.8 times the height (h) of the chain (CH).

This configuration makes it possible to more effectively achieve both rigidity and weight reduction.

The sixth aspect of the present invention is characterized in that, in any one of the first to fifth aspects, the tensioner lever (10) has a back wall portion (13) extending on the opposite side of the chain (CH) as viewed from the sliding surface (10a), the back wall portion (13) has a high-wall side back wall portion (13b) aligned with the high-wall portion (11b) in the height direction, and a low-wall side back wall portion (13a) aligned with the low-wall portion (11a) in the height direction, and a hollowed-out portion (14) is formed in the low-wall side back wall portion 13a.

With this configuration, the weight of the tensioner lever can be further reduced by the hollowed-out portion. Furthermore, by providing the hollowed-out portion for weight reduction on the lower wall side, it becomes easier to ensure the necessary rigidity of the tensioner lever. In other words, it is possible to more effectively achieve both ensuring rigidity and reducing weight.

According to the above aspect of the present invention, it is possible to provide a tensioner lever structure that can ensure rigidity even when there is no space behind the sliding surface, and that can also be made lighter. This in turn can contribute to energy efficiency.

FIG. 1 is a right side view of a motorcycle according to an embodiment of the present invention. FIG. 2 is an enlarged view showing an engine of the motorcycle. FIG. 2 is an enlarged view showing a tensioner lever structure according to an embodiment of the present invention. FIG. 4 is a diagram showing the tensioner lever of FIG. 3 . 5 is a view of the tensioner lever of FIG. 4 as viewed from the arrow V.

The following describes an embodiment of the present invention with reference to the drawings. In the following description, the directions of front, rear, left and right are the same as those in the vehicle described below unless otherwise specified. In addition, in the appropriate places in the drawings used in the following description, an arrow FR indicating the front of the vehicle and an arrow UP indicating the top of the vehicle are shown.

<Entire vehicle>
1 is a right side view of a motorcycle 100, which is an example of a saddle-ride type vehicle. The motorcycle 100 of this embodiment includes a front wheel 2 which is a steered wheel, a rear wheel 3 which is a driven wheel, a front fork 4 which supports the front wheel 2, a swing arm (not shown) which supports the rear wheel 3, a body frame 5 which supports the front fork 4 and the swing arm, and an engine (internal combustion engine, prime mover) 1 supported by the body frame 5.

A pair of front forks 4 are provided on the left and right. The front forks 4 are linked to a steering handle (bar handle) 6 extending in the left-right direction (vehicle width direction), for example, via a steering system (not shown). A seat 7 on which the rider of the motorcycle 100 sits is provided behind the steering handle 6.

Figure 2 is an enlarged view showing the outline of the engine 1 in this embodiment. A crankshaft 31 with a rotation axis (crank axis) C1 aligned in the left-right direction is disposed inside the crankcase 30 of the engine 1. A cylinder 40 is erected on the crankcase 30 facing diagonally upward and forward.

A piston (not shown) is provided in the cylinder 40. The reciprocating motion of the piston is converted into the rotational motion of the crankshaft 31, for example, via a connecting rod (not shown). A first camshaft 41 and a second camshaft 42 having a rotation axis parallel to the crank axis C1 are disposed in a cylinder head 40a attached to the top of the cylinder 40. The first camshaft 41 is located at the front of the top of the cylinder 40. The second camshaft 42 is located at the rear of the top of the cylinder 40. A cylinder head cover 40b may be attached to the top of the cylinder head 40a.

For example, on the side of the cylinder 40, a cam chain chamber 43 is provided to house the cam chain (chain) CH that links the crankshaft 31 and each of the camshafts 41 and 42. The cam chain CH is an endless part. The cam chain CH is wound around the cam drive sprocket 31a of the crankshaft 31, the cam driven sprocket 41a of the first camshaft 41, and the cam driven sprocket 42a of the second camshaft 42. Note that the arrow F1 in the figure indicates the direction of rotation of the cam drive sprocket 31a (crankshaft 31) when the engine is operating. Similarly, the arrows F2 and F3 indicate the direction of rotation of each of the cam driven sprockets 41a and 42a (each of the camshafts 41 and 42), respectively.

The portion of the cam chain CH located in front of the cylinder 40 is pulled in and tensioned by the cam drive sprocket 31a, i.e., the tension side. On the other hand, the portion of the cam chain CH located in the rear of the cylinder 40 is sent out by the cam drive sprocket 31a and slackens, i.e., the slack side. Note that the portion of the cam chain CH located on the upper side of the cylinder 40 (the portion spanning each of the cam driven sprockets 41a, 42a) may also be part of the tension side of the cam chain CH. The cam chain CH winds around the outer circumference of each of the sprockets 31a, 41a, 42a along a plane perpendicular to the left-right direction.

A chain guide 44 is provided at the front of the cam chain chamber 43. The chain guide 44 slides against the tension side of the cam chain CH from the outside (front) of the winding area of the cam chain CH, guiding the direction of travel of the cam chain CH. Note that a chain guide may also be provided at the top of the cam chain chamber 43, sliding against the tension side of the cam chain CH from the outside (top) of the winding area of the cam chain CH, guiding the direction of travel of the cam chain CH.

Meanwhile, a tensioner lever structure TS equipped with a tensioner lever 10 is provided at the rear of the cam chain chamber 43. The tensioner lever 10 slides against the slack side of the cam chain CH from the outside (rear side) of the winding area of the cam chain CH, and guides the direction of travel of the cam chain CH. The tensioner lever 10 also applies an appropriate tension to the slack side of the cam chain CH, removing slack from the cam chain CH. The tensioner lever structure TS is described in detail below.

<Tensioner lever structure>
Fig. 3 is an enlarged view showing the tensioner lever structure TS in this embodiment. As shown in Figs. 2 and 3, the tensioner lever structure TS in this embodiment includes a tensioner lever 10, a pivot shaft 20 connected to a member 21 and extending in the left-right direction, and a tensioner lifter 50. The tensioner lever 10 extends along the longitudinal direction (travel direction) of the cam chain CH. The pivot shaft 20 supports one end of the tensioner lever 10 (the lower end in the example of Fig. 2). As a result, the pivot shaft 20 supports the tensioner lever 10 so that it can swing. The tensioner lifter 50 has a plunger 51 that presses the tensioner lever 10 toward the cam chain CH.

The tensioner lever 10 is formed, for example, from a resin material. The tensioner lever 10 has a sliding surface (sliding contact surface) 10a on which the cam chain CH slides (comes into sliding contact). The sliding surface 10a is pressed against the cam chain CH by the pressing force exerted by the tensioner lifter 50 (plunger 51). The sliding surface 10a extends along the longitudinal direction of the cam chain CH. In the illustrated example, the sliding surface 10a is gently curved so as to be convex toward the inside of the winding area of the cam chain CH when viewed from the left-right direction (as viewed from the side of the engine). Here, the material of the tensioner lever 10 may be made of an elastic metal such as steel, or a hybrid material of metal and resin.

Hereinafter, the direction along the sliding surface 10a (i.e., the longitudinal direction and travel direction of the cam chain CH) is referred to as the sliding direction. The height direction of the cam chain CH sliding on the sliding surface 10a is simply referred to as the height direction. The height direction is also the direction perpendicular to the sliding surface 10a (i.e., the direction of the intersection of the sliding surface 10a). Hereinafter, the dimension in the height direction is simply referred to as the height. In addition, the sliding surface 10a side of the tensioner lever 10 is referred to as the "front side of the tensioner lever 10 (sliding surface 10a)" or the "chain side of the tensioner lever 10 (sliding surface 10a)", and the opposite side is referred to as the "rear side of the tensioner lever 10 (sliding surface 10a)".

Figures 4 and 5 are views showing the tensioner lever 10 of Figure 3. As shown in Figures 3 and 4, the tensioner lever 10 in this embodiment has a wall portion 11, a pressure receiving portion 12, and a back wall portion 13.

The wall portion 11 stands upright from the sliding surface 10a in the height direction of the cam chain CH. In other words, the wall portion 11 is provided on the chain side of the tensioner lever 10 (sliding surface 10a). The wall portion 11 extends in the sliding direction. The wall portion 11 is a portion for increasing the rigidity of the tensioner lever 10. As shown in FIG. 5, the tensioner lever 10 in this embodiment has two wall portions 11. The two wall portions 11 stand upright from both side edges of the sliding surface 10a. The cam chain CH slides against the sliding surface 10a between the two wall portions 11.

As shown in Figures 3 and 4, the wall portion 11 has a high wall portion 11b that is higher than the height h of the cam chain CH, a low wall portion 11a that is lower than the height h of the cam chain CH, and a boundary portion 11c. The height H of the high wall portion 11b is preferably, for example, 1.2 to 1.8 times the height h of the cam chain CH.

The boundary portion 11c is located at the boundary between the low wall portion 11a and the high wall portion 11b. The low wall portion 11a, the boundary portion 11c, and the high wall portion 11b are arranged in this order in the sliding direction. In the illustrated example, the boundary portion 11c has an inclined portion 11d whose height gradually increases from the low wall portion 11a to the high wall portion 11b. In other words, the height of the wall portion 11 changes smoothly from the low wall portion 11a to the high wall portion 11b. The tip surface of the inclined portion 11d in the height direction is inclined with respect to the intersection direction of the sliding surface 10a. In other words, the boundary portion 11c in the illustrated example is not perpendicular to the sliding surface 10a.

The pressure-receiving portion 12 is the portion that is pressed by the tensioner lifter 50 (plunger 51). In the pressing direction in which the tensioner lifter 50 (plunger 51) presses the pressure-receiving portion 12, the pressure-receiving portion 12 and the high wall portion 11b are aligned. In other words, the high wall portion 11b of the wall portion 11 is located on the axis C2 of the plunger 51.

The aforementioned boundary portion 11c is located between the pivot shaft 20 and the pressure receiving portion 12 (tensioner lifter 50) in the sliding direction. That is, in the sliding direction, the low wall portion 11a is located on the pivot shaft 20 side, and the high wall portion 11b is located on the pressure receiving portion 12 side. More specifically, in the illustrated example, the boundary portion 11c is located near the midpoint M in the sliding direction between the pivot shaft 20 and the pressure receiving portion 12. The term "midpoint M" refers to a point that is equidistant d from both the pivot shaft 20 and the pressure receiving portion 12.

The back wall portion 13 extends on the opposite side to the cam chain CH when viewed from the sliding surface 10a. In other words, the back wall portion 13 is provided on the back side of the tensioner lever 10 (sliding surface 10a). The back wall portion 13 extends in the sliding direction. As shown in Figures 3 and 4, the back wall portion 13 has a high-wall side back wall portion 13b aligned with the high wall portion 11b in the height direction, and a low-wall side back wall portion 13a aligned with the low wall portion 11a in the height direction. The maximum height of the high wall portion 11b (the maximum value of the height of the high wall portion 11b) is greater than the maximum height of the low wall portion 11a (the maximum value of the height of the low wall portion 11a).

The low-wall side back wall portion 13a has a plurality of lightening holes (lightening portions) 14 formed therein. In the illustrated example, the high-wall side back wall portion 13b also has a plurality of lightening holes 14 formed therein. The total area of the lightening holes 14 formed in the low-wall side back wall portion 13a may be greater than the total area of the lightening holes 14 formed in the high-wall side back wall portion 13b.

Next, we will explain the operation of the tensioner lever structure TS configured as described above.

In conventional technology, in order to ensure the rigidity of the tensioner lever, a wall portion is extended on the side opposite the cam chain as viewed from the sliding surface on which the cam chain slides (i.e., the back side of the sliding surface). However, for example, factors such as the engine configuration may make it difficult to provide a wall portion on the back side of the sliding surface. Furthermore, from the perspective of contributing to energy efficiency, it is necessary not only to ensure the rigidity of the tensioner lever, but also to realize a lightweight tensioner lever.

In response to these issues, in the tensioner lever structure TS of this embodiment, a wall portion 11 is provided on the chain side of the tensioner lever 10 (sliding surface 10a) to improve the rigidity of the tensioner lever 10. This ensures the rigidity of the tensioner lever 10 even if there is no space to provide the wall portion 11 on the back side of the tensioner lever 10 (sliding surface 10a). In addition, by having the wall portion 11 have the low wall portion 11a and not making the entire wall portion 11 a high wall portion 11b, the tensioner lever 10 can be made lighter.

As described above, the tensioner lever structure TS in the above embodiment is a tensioner lever structure that includes a tensioner lever 10 that has a sliding surface 10a along which a chain (cam chain CH) slides and that swings, and the tensioner lever 10 has a wall portion 11 that stands upright from the sliding surface 10a in the height direction of the cam chain CH, and the wall portion 11 has a high wall portion 11b that is higher than the height h of the cam chain CH, and a low wall portion 11a that is lower than the height h of the cam chain CH.

This configuration makes it possible to provide a tensioner lever structure TS that can ensure rigidity even when there is no space behind the tensioner lever 10, and that can also be made lighter. This in turn contributes to improved energy efficiency.

In the above tensioner lever structure TS, the tensioner lever 10 further has a pressure-receiving portion 12 that is pressed by a tensioner lifter 50, and is characterized in that the pressure-receiving portion 12 and the high wall portion 11b are aligned in the pressing direction in which the tensioner lifter 50 presses the pressure-receiving portion 12.

This configuration improves the rigidity of the portion of the tensioner lever 10 that is pressed by the tensioner lifter 50 (i.e., the area around the pressure-receiving portion 12).

The tensioner lever structure TS further includes a pivot shaft 20 that supports the tensioner lever 10 so that it can swing, and the boundary portion 11c located at the boundary between the high wall portion 11b and the low wall portion 11a is located between the pivot shaft 20 and the pressure receiving portion 12.

After careful consideration, the inventors of the present application have found that the area of the tensioner lever 10 that requires particular rigidity is the area around the pressure receiving portion 12, and that there is no need to increase the rigidity excessively around the pivot shaft 20. With the above configuration, the low wall portion 11a is located on the pivot shaft 20 side, and the high wall portion 11b is located on the pressure receiving portion 12 side. This allows the tensioner lever 10 to be more reliably secured in its overall rigidity and lighter in weight by providing the high wall portion 11b in the area where rigidity is required, while making the low wall portion 11a the area where rigidity is not required.

In the above tensioner lever structure TS, the boundary portion 11c is characterized by having an inclined portion 11d whose height gradually increases from the low wall portion 11a toward the high wall portion 11b.

This configuration makes it possible to avoid abrupt changes in rigidity at the boundary between the low wall portion 11a and the high wall portion 11b.

The tensioner lever structure TS is characterized in that the height H of the high wall portion 11b is 1.2 to 1.8 times the height h of the cam chain CH.

This configuration makes it possible to more effectively achieve both rigidity and weight reduction.

In the above tensioner lever structure TS, the tensioner lever 10 has a back wall portion 13 extending on the opposite side to the cam chain CH as viewed from the sliding surface 10a, and the back wall portion 13 has a high-wall side back wall portion 13b aligned with the high-wall portion 11b in the height direction, and a low-wall side back wall portion 13a aligned with the low-wall portion 11a in the height direction, and a lightening portion (lightening hole 14) is formed in the low-wall side back wall portion 13a.

With this configuration, the weight of the tensioner lever 10 can be further reduced by the weight reduction holes 14. Furthermore, by providing the weight reduction holes 14 on the bottom wall portion 11a side (i.e., the pivot shaft 20 side), it becomes easier to ensure the necessary rigidity of the tensioner lever 10. In other words, it is possible to more effectively achieve both ensuring rigidity and reducing weight.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, the tensioner lever structure of this embodiment may be applied to saddle-type vehicles other than motorcycles.

The saddle-type vehicle includes all vehicles on which the driver straddles the vehicle body, including not only motorcycles (including motorized bicycles and scooter-type vehicles), but also three-wheeled vehicles (including vehicles with one front wheel and two rear wheels, as well as vehicles with two front wheels and one rear wheel) or four-wheeled vehicles (such as four-wheeled buggies). It may also be applied to vehicles that include an electric motor as a prime mover. It may also be applied to vehicles other than saddle-type vehicles (passenger cars, buses, trucks, etc.).

The configuration in the above embodiment is one example of the present invention, and various modifications are possible without departing from the gist of the present invention, such as replacing the components of the embodiment with well-known components. In addition, the above-described embodiments and modifications may be combined as appropriate.

TS Tensioner lever structure CH Cam chain (chain)
REFERENCE SIGNS LIST 10 tensioner lever 10a sliding surface 11 wall portion 11a low wall portion 11b high wall portion 11c boundary portion 11d inclined portion 12 pressure receiving portion 13 back wall portion 13a low wall side back wall portion 13b high wall side back wall portion 14 lightening hole (lightening portion)
20 Pivot shaft 50 Tensioner lifter

Claims (6)

A tensioner lever structure including a tensioner lever that has a sliding surface on which a chain slides and that swings,
the tensioner lever has a wall portion erected in a height direction of the chain from the sliding surface,
1 is a tensioner lever structure according to the first embodiment of the present invention; and The tensioner lever further has a pressure receiving portion that is pressed by a tensioner lifter,
2. The tensioner lever structure according to claim 1, wherein the pressure receiving portion and the high wall portion are aligned in a pressing direction in which the tensioner lifter presses the pressure receiving portion. The tensioner lever further includes a pivot shaft that pivotably supports the tensioner lever.
3. The tensioner lever structure according to claim 2, wherein a boundary portion between the high wall portion and the low wall portion is located between the pivot shaft and the pressure receiving portion. The tensioner lever structure according to claim 3, characterized in that the boundary portion has an inclined portion whose height gradually increases from the low wall portion toward the high wall portion. The tensioner lever structure according to any one of claims 1 to 4, characterized in that the height of the high wall portion is 1.2 to 1.8 times the height of the chain. the tensioner lever has a back wall portion extending on a side opposite to the chain as viewed from the sliding surface,
The rear wall portion has a high-wall-side rear wall portion aligned with the high wall portion in the height direction and a low-wall-side rear wall portion aligned with the low wall portion in the height direction,
6. The tensioner lever structure according to claim 5, wherein a hollow portion is formed in the lower wall side rear wall portion.

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