JP7750719B2 - Pulley device - Google Patents

Description

The present invention relates to a pulley device.

Scooter-type motorcycles and the like employ belt-type continuously variable transmissions (see, for example, Patent Documents 1 to 3). These continuously variable transmissions include a drive pulley device fixed to the engine crankshaft, a driven pulley device, and a belt stretched between these pulleys. Each of the drive pulley device and the driven pulley device has a fixed sheave and a movable sheave that faces the fixed sheave and is axially movable.

In the above-described continuously variable transmission, the driven pulley device has a fixed sheave and a movable sheave, as described above. The fixed sheave is fixed to one end of a cylindrical fixed boss, and the movable sheave is fixed to one end of a similarly cylindrical movable boss. The movable boss is positioned radially outward of the fixed boss and is movable in the axial direction.

A cam mechanism is also provided between the fixed boss and the movable boss. The cam mechanism consists of a pin fixed to the fixed boss and a cam groove formed in the movable boss. The pin is inserted slidably into the cam groove of the movable boss. A slider is used to improve the sliding ability of the pin in the cam groove.

JP 2015-64014 A Japanese Patent Application Laid-Open No. 2019-163856 Japanese Patent Application Publication No. 8-178004

The slider is subjected to a load from the cam groove, which places a strain on the slider. Therefore, it is necessary to prevent damage to the slider. The objective of this invention is to prevent damage to the slider of the cam mechanism in a pulley device.

(1) A pulley device according to one aspect of the present invention is a pulley device that rotates in a first direction of rotation in response to torque input from a drive source. The pulley device comprises a fixed sheave, a fixed boss, a movable sheave, a movable boss, a pin, and a slider. The fixed boss extends axially from the fixed sheave. The movable sheave is arranged to be movable in the axial direction. The movable boss has a cam groove. The cam groove includes a torque input surface facing the first direction of rotation. The cam groove extends axially while inclined relative to the axial direction. The movable boss extends axially from the movable sheave. The movable boss is arranged radially outward from the fixed boss. The movable boss is cylindrical. The pin has a torque receiving surface facing the torque input surface. The pin is arranged in the cam groove. The pin is fixed to the fixed boss. The slider is arranged between the pin and the torque input surface. The torque receiving surface is either a flat surface extending along the torque input surface or a concave surface recessed away from the torque input surface.

In the above structure, the pin has a torque receiving surface. The torque receiving surface is either a flat surface that extends along the torque input surface, or a concave surface that recesses away from the torque input surface. A torque receiving surface configured in this manner receives the torque input from the torque input surface as a load in a fixed direction without dispersing it. As a result, the load on the slider is also a load in a fixed direction, making it less likely that the slider will be subjected to tensile or bending loads. This makes it possible to prevent damage to the slider.

(2) Preferably, the slider is made of resin.

(3) When viewed radially, the slider has a shape that includes an imaginary diagonal line extending in the direction in which the cam groove extends. This allows the thickness of the slider wall to be thin at the corners on the imaginary diagonal line, while the thickness of the wall abutting the torque-receiving surface can be thickened.

(4) The bottom surface of the slider is shaped to match the shape of the fixed boss. This shape prevents the slider from rotating relative to the fixed boss. As a result, the torque-receiving surface can be kept facing in a fixed direction.

(5) The fixed boss has a rotation stopper. The rotation stopper prevents the pin from rotating. This prevents the pin from rotating relative to the fixed boss.

(6) The rotation stopper is a recess. The recess has a pair of walls configured to sandwich the pin.

(7) The slider has a protrusion extending toward the fixed boss. The protrusion is positioned between the pair of wall surfaces and the pin. This prevents the pin from rotating relative to the fixed boss.

(8) The recess extends in the circumferential direction.

The present invention as described above can prevent damage to the slider of the cam mechanism in a pulley device.

1 is a cross-sectional view of a pulley device according to an embodiment of the present invention. FIG. FIG. 4 is a plan view showing the relationship between the pin, the slider, and the cam groove. FIG. FIG. FIG. FIG. FIG. 10 is a cross-sectional view taken horizontally in the axial direction, showing the relationship between a pin and a slider in a modified example. FIG. 10 is a cross-sectional view perpendicular to the axial direction showing the relationship between the pin and the slider in a modified example. FIG. 10 is a plan view showing the relationship between the pin, the slider, and the cam groove in a modified example. FIG. 10 is a plan view showing the shape of a pin in a modified example.

[Overall configuration]
1 and 2 , torque is transmitted to a pulley device 100 from a drive pulley device (not shown) via a belt 2. The pulley device 100 rotates in a first rotation direction in response to torque input from a drive source. The pulley device 100 has a fixed sheave 3, a movable sheave 4, a cylindrical fixed boss 5, a cylindrical movable boss 6, and a cam mechanism 7.

In the cross-sectional view of Figure 1, line O-O is the axis of rotation. In the following description, unless otherwise specified, "axial direction" refers to the direction in which the axis of rotation of the pulley device 100 extends. "Radial direction" refers to the radial direction of a circle centered on the axis of rotation O of the pulley device 100, unless otherwise specified. "Circumferential direction" refers to the circumferential direction of a circle centered on the axis of rotation O of the pulley device 100, unless otherwise specified. Arrow R1 in Figure 2 indicates the first side of the rotational direction, and arrow R2 indicates the opposite side, the second side of the rotational direction (the same applies to the following figures).

[Fixed sheave 3 and fixed boss 5]
The fixed sheave 3 is arranged so as not to move in the axial direction. The fixed sheave 3 is a disc-shaped member with a through hole 3a in the center. The surface of the fixed sheave 3 facing the movable sheave 4 is formed in a tapered shape that slopes away from the movable sheave 4 as it moves radially outward relative to the fixed sheave 3. The surface of the fixed sheave 3 facing the movable sheave 4 forms a V-groove together with the opposing surface of the movable sheave 4.

The fixed boss 5 extends axially from the fixed sheave 3. The fixed boss 5 is cylindrical. The fixed boss 5 has an axially extending cylindrical portion 5b and an engaging portion 5c formed at one end (the left end in Figure 1).

The cylindrical portion 5b has the same outer diameter and extends to the engagement portion 5c on the other end. The cylindrical portion 5b has multiple (five in this embodiment) pin holes 5d that penetrate radially in the axial center.

As shown in Figure 3, the fixed boss 5 has a rotation prevention portion 5e. The rotation prevention portion 5e is formed on the outer peripheral surface of the fixed boss 5. The rotation prevention portion 5e is a recess that is recessed radially inward relative to the outer peripheral surface of the cylindrical portion 5b. The rotation prevention portion 5e prevents the pin from rotating. As shown in Figure 4, the recess has a pair of wall surfaces 51e. The pair of wall surfaces 51e are configured to sandwich the pin 8.

The rotation stopper portion 5e extends circumferentially. Therefore, the pair of wall surfaces 51e also extend circumferentially.

An output shaft (not shown) that transmits torque to the wheel side passes through the cylindrical portion 5b.

[Movable sheave 4 and movable boss 6]
As shown in Figures 1 and 2, the movable sheave 4 is arranged to be movable in the axial direction. The movable sheave 4 is biased toward the fixed sheave 3 by a spring (not shown). The movable sheave 4 is a disk-shaped member with a through-hole 4a in the center. The surface of the movable sheave 4 facing the fixed sheave 3 is tapered, inclining away from the fixed sheave 3 as it approaches the outer periphery. The surface of the movable sheave 4 facing the fixed sheave 3 forms a V-groove together with the opposing surface of the fixed sheave 3.

The movable boss 6 extends axially from the movable sheave 4. The movable boss 6 is cylindrical and positioned radially outward of the fixed boss 5. In other words, the fixed boss 5 extends axially within the movable boss 6. The movable boss 6 has a cylindrical portion 6b extending axially and a cam groove 61.

The cylindrical portion 6b has the same outer diameter and extends to the other end, and has multiple (five in this embodiment) cam grooves 61. The cam grooves 61 are formed to penetrate the cylindrical portion 6b in the radial direction. The cam grooves 61 extend in the axial direction while inclining at a predetermined angle relative to the axial direction. The cam grooves 61 are also formed to be inclined relative to the circumferential direction. The cam grooves 61 are arranged at intervals from each other in the circumferential direction.

The cam groove 61 is inclined more axially at positions farther from the movable sheave 4 than at positions closer to the movable sheave 4.

The cam groove 61 is defined by a torque input surface 611 and a counter torque input surface 612. The torque input surface 611 and the counter torque input surface 612 extend in the longitudinal direction. The torque input surface 611 and the counter torque input surface 612 are arranged parallel to each other. The torque input surface 611 faces the first side in the rotational direction. The torque input surface 611 is arranged on the second side in the rotational direction of the cam groove 61. The torque input surface 611 applies a load to the pin 8 when torque is input from the drive source. The counter torque input surface 612 is arranged on the first side in the rotational direction of the cam groove 61. The counter torque input surface 612 applies a load to the pin 8 when torque is input from the drive wheel side.

[Cam mechanism 7]
1 to 3, the cam mechanism 7 has a plurality of pins 8, a cam groove 61 formed in the movable boss 6, and a slider 9. The cam mechanism 7 applies an axial thrust to the movable boss 6.

[Pin 8]
As shown in FIGS. 3 and 4, the pin 8 is disposed in the cam groove 61 of the movable boss 6.

As shown in Figures 5 and 6, the pin 8 has a head 83 and a leg 84. The head 83 and leg 84 are formed from a single member. The outer diameter of the head 83 is larger than the outer diameter of the leg 84.

As shown in Figures 3 to 6, the head 83 protrudes radially outward from the outer peripheral surface of the fixed boss 5. The head 83 is disposed on the rotation stopper 5e of the fixed boss 5. Specifically, the head 83 is sandwiched between a pair of wall surfaces 51e of the rotation stopper 5e and prevented from rotating. The shape of the head 83 in plan view is a parallelogram with rounded corners. The outer periphery of the end of the head 83 facing away from the leg 84 may be chamfered.

The head 83 has a torque receiving surface 81, a counter torque receiving surface 85, and a pair of rotation stop surfaces 82. The surfaces connecting the torque receiving surface 81 and each of the rotation stop surfaces 82 are rounded.

The torque receiving surface 81 faces the torque input surface 611. The torque receiving surface 81 faces the second side in the rotational direction. The torque receiving surface 81 is arranged on the second side in the rotational direction of the head 83. The torque receiving surface 81 is a flat surface that extends along the torque input surface 611. Note that the torque receiving surface 81 extending along the torque input surface 611 does not only mean that the torque receiving surface 81 extends completely parallel to the torque input surface 611, but also means that the angle between the extension direction of the torque receiving surface 81 and the extension direction of the torque input surface 611 is 10 degrees or less.

The counter torque receiving surface 85 faces the first side in the rotational direction. The counter torque receiving surface 85 is arranged on the first side in the rotational direction of the head 83. The counter torque receiving surface 85 is parallel to the torque receiving surface 81.

The pair of rotation stop surfaces 82 face in the axial direction. The pair of rotation stop surfaces 82 are arranged parallel to each other. The pair of rotation stop surfaces 82 abut against a pair of wall surfaces 51e that define the rotation stop portion 5e of the movable boss 6.

The leg portion 84 protrudes toward the fixed boss 5 from the end face of the head 83 on the fixed boss 5 side. The leg portion 84 is cylindrical. The leg portion 84 fits into the pin hole 5d of the fixed boss 5. The outer periphery of the end of the leg portion 84 away from the head 83 may be chamfered.

The pin 8 is made of a sintered material. This allows the pin 8 to be impregnated with grease. The sintered material may be a sintered material made from powder containing at least one of the elements Fe, Cr, Mo, Ni, Mn, etc., or may be ceramic.

[Slider 9]
The slider 9 is disposed between the pin 8 and the torque input surface 611 of the cam groove 61. As shown in FIGS. 5 and 6 , the slider 9 is provided so as to cover the outer peripheral surface of the head 83 of the pin 8. Specifically, the slider 9 covers the half of the head 83 away from the leg 84. The slider 9 has a recess facing radially inward, into which the head 83 fits. The shape of the wall surface defining the recess of the slider 9 follows the shape of the head 83. This makes it possible to suppress rotation of the slider 9 relative to the fixed boss 5. The outer peripheral surface of the slider 9 slides against the wall surface defining the cam groove 61.

As shown in FIG. 3 , the slider 9 has a shape that includes an imaginary diagonal line A that extends in the direction in which the cam groove 61 extends, when viewed radially. Therefore, at the corners on the imaginary diagonal line A, the thickness of the wall surface of the slider 9 can be made thin, while the thickness of the wall surface that abuts the torque receiving surface 81 can be made thick. Note that "imaginary diagonal line A extending along the direction in which the cam groove 61 extends" not only means that the imaginary diagonal line A extends completely parallel to the direction in which the cam groove 61 extends, but also means that the angle between the direction in which the imaginary diagonal line A extends and the direction in which the cam groove 61 extends is 10 degrees or less.

When the slider 9 is not inserted into the cam groove 61, the contact surface 93 that contacts the torque input surface 611 of the slider 9 bulges outward in the radial direction of the slider 9. Therefore, when the slider 9 is compressed and inserted into the cam groove 61, the contact surface 93 can maintain sufficient contact with the torque input surface 611 even if the inclination angle of the cam groove 61 relative to the axial direction changes.

As shown in FIG. 7 , the bottom surface 91 of the slider 9 faces the outer peripheral surface of the fixed boss 5. The bottom surface 91 of the slider 9 has a shape that follows the shape of the fixed boss 5. In detail, the bottom surface 91 of the slider 9 has a shape that follows the shape of the outer peripheral surface of the fixed boss 5.

The slider 9 is made of a material with a higher elastic modulus than the pin 8. The slider 9 is made of a material with a lower coefficient of friction than the pin 8. More specifically, the pin 8 is made of resin. The resin is, for example, PTFE (polytetrafluoroethylene).

[Operation and effect of cam mechanism]
As the engine speed increases, the movable sheave 4 rotates in the first rotational direction at a faster speed than the fixed sheave 3. This causes the movable boss 6 to rotate relative to the fixed boss 5. The cam mechanism 7 then converts the torque in the rotational direction into axial torque and applies an axial thrust to the movable boss 6. Receiving the thrust, the movable boss 6 moves axially toward the fixed sheave 3. The torque input surface 611 inputs torque to the pin 8 via the slider 9. In the pulley device 100 of this embodiment, the torque receiving surface 81 extends along the torque input surface 611. Therefore, the pin 8 can receive the torque input from the torque input surface 611 via the slider 9 at the torque receiving surface 81. The torque receiving surface 81 receives the input torque as a load in a fixed direction without dispersing it. As a result, the load applied to the slider 9 is also a load in a fixed direction, making it less likely for the slider 9 to be subjected to tensile or bending loads. This ensures the strength of the slider 9. When torque is input to the pin 8, the pin 8 is fixed to the fixed boss 5, so the movable boss 6 moves axially away from the fixed sheave 3 via the cam groove 61. As a result, the movable sheave 4 moves toward the fixed sheave 3 and firmly clamps the belt 2.

[Modification]
The present invention is not limited to the above-described embodiments, and various modifications and alterations are possible without departing from the scope of the present invention.

(a) In the above embodiment, the pin 8 abuts against the wall surfaces that define the rotation stop portion 5e, but this is not particularly limited. As shown in Figures 8 and 9, the slider 9 may have a pair of protrusions 92 that extend toward the fixed boss 5. The pair of protrusions 92 are positioned between the pin 8 and a pair of wall surfaces 51e of the rotation stop portion 5e.

Note that the protrusions 92 do not have to be a pair of protrusions. For example, the protrusions 92 may be cylindrical. If the protrusions 92 are cylindrical, the pin 8 is disposed inside the cylindrical portion.

(b) In the above embodiment, the torque receiving surface 81 was flat, but this is not limited to this. For example, as shown in Figures 10 and 11, the torque receiving surface 81 may be a concave surface that is recessed away from the torque input surface 611. A slider 9 is placed in the recessed portion of the pin 8. In this case, even if torque is input in multiple directions, the pin 8 can receive the torque as a load in a fixed direction without dispersing it.

(c) In the above embodiment, the pin 8 was made of a sintered material, but this is not a limitation. The pin 8 may be made of, for example, a light metal or an iron-based material.

(d) In the above embodiment, the rotation stop portion 5e is defined by a pair of wall surfaces, but this is not particularly limited. For example, the rotation stop portion 5e may be a wall surface that extends along the torque receiving surface 81 and supports the torque receiving surface 81.

(e) In the above embodiment, the counter torque receiving surface 85 of the pin 8 is parallel to the torque receiving surface 81, but this is not limited to this. The counter torque receiving surface 85 may also bulge toward the first side in the rotational direction.

2 Belt 3 Fixed sheave 4 Movable sheave 5 Fixed boss 5e Rotation stopper 6 Movable boss 6d Cam groove 61d Torque input surface 7 Cam mechanism 8 Pin 9 Slider 81 Torque receiving surface 100 Pulley device

Claims (6)

A pulley device that rotates in a first rotation direction by torque input from a drive source,
A fixed sheave;
a fixed boss extending axially from the fixed sheave;
a movable sheave arranged to be movable in the axial direction;
a cylindrical movable boss including a torque input surface facing the first side in the rotational direction and having a cam groove extending in the axial direction while being inclined with respect to the axial direction, the movable boss extending in the axial direction from the movable sheave and being disposed radially outward of the fixed boss;
a pin having a torque receiving surface facing the torque input surface, the pin being disposed in the cam groove and fixed to the fixed boss;
a slider disposed between the pin and the torque input surface;
Equipped with
The torque receiving surface is a flat surface extending along the torque input surface or a concave surface recessed away from the torque input surface.
The fixing boss has a rotation stop portion that stops the pin from rotating,
The rotation stopper is a recess having a pair of wall surfaces configured to sandwich the pin.
Pulley device.
The slider is made of resin.
The pulley assembly of claim 1 .
the slider has a shape including a virtual diagonal line extending in a direction in which the cam groove extends, when viewed in a radial direction;
The pulley device according to claim 1 or 2.
The bottom surface of the slider has a shape that follows the shape of the fixing boss.
The pulley device according to any one of claims 1 to 3.
the slider has a protrusion extending toward the fixed boss,
The protrusions are disposed between the pair of wall surfaces and the pin.
The pulley device according to any one of claims 1 to 4 .
The recess extends in a circumferential direction.
The pulley device according to any one of claims 1 to 5 .