JPS6220419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power transmission device for a motorcycle equipped with a buffer mechanism that absorbs torque fluctuations.

[Conventional technology]

2. Description of the Related Art Some conventional motorcycles equipped with a shaft drive mechanism include a shock absorbing mechanism interposed in a power transmission device that connects an engine and a drive wheel. This buffer mechanism has the effect of absorbing torque fluctuations caused by intermittent explosions of the engine and torque fluctuations caused by sudden acceleration/deceleration, and improves ride comfort. This type of shock absorbing mechanism is one in which a shaft connected to the engine side and a shaft connected to the driving wheel side are connected by rubber baked on each shaft, or As disclosed in Japanese Patent Application Laid-open No. 2712 and Japanese Patent Application Laid-open No. 49-85437, there is a nut screwed into a spiral groove and a nut connected via a spring that presses the nut.

[Problem that the invention seeks to solve]

However, in either structure, there were some conditions in which the ride comfort could not necessarily be improved. That is,
In the former case, it is structurally impossible to increase the relative torsion angle between each axis, and it is necessary to ensure that this torsion angle remains within the allowable range even during maximum torque fluctuations. It has been difficult to reduce the spring constant used as a buffer mechanism. For this reason, especially when a shaft drive mechanism is employed in a small motorcycle, the spring constant is too large, making it unsuitable for absorbing engine torque fluctuations.

On the other hand, in the latter, the structure absorbs shock by compressing and deforming the spring by moving the nut in only one direction, so the torque fluctuations transmitted from the drive wheels to the engine cannot be buffered. Ta.

[Means for Solving the Problems] The present invention was made in view of the above circumstances, and provides a power transmission device for a motorcycle that can improve riding comfort.

A power transmission device for a motorcycle according to the present invention includes a cylindrical housing to which a housing shaft is slidably coupled, and a push screw inserted into the housing, which are coupled by a torsion spline. A washer, which the housing and the push screw come into contact with, is slidably attached to a push screw shaft that is slidably connected to the push screw shaft in the axial direction, and the washer is attached to the push screw shaft. A retainer for interposing a compression spring between the two and a retainer for bringing the push screw into contact are fixed.

[Effect]

In the present invention, when the push screw rotates in a direction opposite to the torsion direction of the torsion spline, it moves rearward with respect to the housing and presses the washer to compress and deform the compression spring, while in a direction equal to the torsion direction. Even if it rotates to , it moves forward with respect to the housing and presses the retainer, similarly compressing and deforming the compression spring.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a side view of a small motorcycle implementing the power transmission device for a motorcycle according to the present invention;
The figure is a plan view showing a section of a part of the power transmission device.
FIG. 3 is an exploded perspective view of the main parts, and FIG. 4 is an explanatory diagram of its operation. In Figure 1, numeral 1 is the main frame, 2 is the front fork, 3 is the front wheel,
4 is a steering handle, and 5 is a seat. 6 is a power transmission device equipped with a single cylinder engine, and this power transmission device 6 includes an engine section 7, a rear wheel hub 8,
The vicinity of the engine part 7 is rotatably held on the main frame 1 by a support shaft 10, and the rear wheel hub 8 is provided with a damper-equipped shock absorber 12. It is strongly supported by A rear wheel 13 serving as a driving wheel is attached to the rear wheel hub 8. That is, the rear wheel 13
The power transmission device 6 rotates integrally around a support shaft 10, forming a so-called unit swing type rear wheel suspension system. In addition, in Figure 1, 1
4 is a vaporizer, and 15 is an air filter.

The power transmission device 6 is constructed as shown in FIG. A crankshaft 16 is pivotally supported in the engine section 7, and one piston 17 is connected thereto via a connecting rod 18. crankshaft 16
A flywheel magneto 19 is attached to one end, and a gear 20 is fixed to the other end.
21 is a clutch shaft that supports the centrifugal clutch 22; a gear 23 that meshes with the gear 20 is rotatably supported on this clutch shaft 21;
Centrifugal top 2 pressed by centrifugal force against the inner peripheral surface of
5 is rotatably supported. clutch shaft 21
The other end is connected via a bevel gear 27 to an output shaft 26 serving as a housing shaft, one end of which faces inside the connecting pipe 9 . Note that 28 is a hard crank, and the rotation of this hard crank 28 causes the gear 23 to be rotated by a known hard starting mechanism.

The rear wheel hub 8 is attached to a rear wheel shaft 31 rotatably supported by a case 30. This case 30 is firmly connected to the engine section 7 together with the connecting pipe 9, and a driving large gear 32 fixed to a rear wheel shaft 31 is housed within this case 30. This driving gear 3
A drive pinion 33 meshes with the drive pin 2, and the shaft end of the drive pinion 33 faces into the connecting pipe 9. A propulsion shaft 34 as a push screw shaft is housed in the connecting pipe 9, and an engagement hole 35 having a square cross section is formed at the rear end of the propulsion shaft 34. (3rd
(See figure) This engagement hole 35 is provided with the drive small gear 33.
The end of the is engaged. Further, the front end of this propulsion shaft 34 is connected to the output shaft 26 of the engine section 7 via a buffer mechanism 36 according to the present invention. In other words, the buffer mechanism 36 constitutes a part of a power transmission device that transmits the rotation of the engine section 7 to the rear wheel hub 8.

Next, this buffer mechanism 36 will be explained in detail. 37
is a generally cylindrical housing provided with a torsion spline (to be described later) inside, and a collar 38 having an engagement hole 39 with a square cross section is fixed to the front end of the housing, into which the rear end of the output shaft 26 is inserted. It's involved. That is, the housing 37 is connected to be movable in the axial direction. 40 is a push screw, which is screwed into the housing 37.
That is, the housing 37 is connected to the housing 37 by a torsion spline 41. The torsion spline 41 is formed to twist in the left-hand thread direction, as shown in FIG. The axial length of the push screw 40 is shorter than that of the housing 37, and the torsion spline 41 on the inner peripheral surface of the housing 37 has the same axial length as the push screw 40. Further, the torsion spline 41 on the inner peripheral surface of the housing 37 is formed such that its teeth protrude from the inner peripheral surface, and its end 37a (see FIG. 4) on the side of the collar 38 is stepped. The front end of the propulsion shaft 34 is inserted into the push screw 40, and both are connected by a straight spline 42 parallel to the axis. A retainer 43 is secured to the tip of the propulsion shaft 34 passing through the push screw 40 by a circlip 44. The push screw 40 and the stepped end 37a of the torsion spline 41 on the housing 37 side come into contact with this retainer 43. Further, the push screw 40 and the washer 4 which the rear end surface of the housing 37 abuts on the propulsion shaft 34.
5 is slidably attached. A retainer 46 is attached to the intermediate position of the propulsion shaft 34, and this retainer 46 is attached to a circlip 47 that is attached to the propulsion shaft 34.
Movement to the rear is restricted. A compression coil spring 48 is interposed between the retainer 46 and the washer 45 in a compressed state. This spring 48 is formed to have an outer diameter substantially equal to the outer diameter of the housing 37.

Next, the operation of this buffer mechanism 36 will be explained. The output shaft 26 rotates in the direction of arrow A in FIG. 3, and at this time the vehicle body moves forward. FIG. 4A shows when the engine is running, FIG. 4B shows when the engine is stopped, and FIG. 4C shows when the engine is braked. When the engine is currently stationary or idling and the driving force of the engine is not transmitted to the output shaft 26, the buffer mechanism 36 is in the state shown in FIG. 4B.

That is, the washer 45 is a compression coil spring 48.
The push screw 40 and the end faces of the housing 37 are pushed forward (upward in FIG. 4) by the washer 45, so that the torsion spline 41 of the push screw 40 and the housing 37 is pushed forward (upward in FIG. 4) by the washer 45. and the retainer 43 at the front end of the propulsion shaft 34, and is maintained in this state. Next, when the engine is started and its rotational speed increases and the centrifugal clutch 22 becomes engaged, torque is applied to the output shaft 26 in the direction of arrow A in FIG. Therefore, the housing 37 is rotated in the same direction, but since the propulsion shaft 34 that interlocks with the rear wheel 13 is stopped, the push screw 40 is moved rearward (downward in FIG. 4A) by the action of the torsion spline 41. Extruded. This pushing force further compresses the compression coil spring 48 via the washer 45 against the elastic force. Furthermore, torque fluctuations due to intermittent explosions of the engine during driving are absorbed by the compression of the compression coil spring 48 in exactly the same way. In other words, changes in the torque transmitted from the engine to the rear wheels 13 are alleviated by the compression of the coil spring 48, so the rear wheels 13 rotate smoothly.

Conversely, when the engine brake is applied, torque based on the inertia of the vehicle body is transferred from the rear wheels 13 to the propulsion shaft 3.
4 can be conveyed. In this case, putushiyuscuriyu 4
0 tries to move forward (upward in FIG. 4c) within the housing 37 due to the action of the torsion spline 41. However, there is a retainer 4 at the tip of the propulsion shaft 34.
3, the push screw 40 contacts this retainer 43 and cannot move forward any further. Therefore, the housing 37 moves backward (downward in the figure), and the end surface of the housing 37 presses the washer 45. Due to the force of this housing 37 pressing against the washer 45, the compression coil spring 48 is compressed against its elastic force. In other words, the rear wheel 13 during engine braking
Fluctuations in the torque transmitted from the engine toward the engine are also absorbed by the compression of the compression coil spring 48.

In this embodiment, the shock absorbing mechanism 36 is attached to the propulsion shaft 34, so that the entire power unit 6 can be made more compact.

In this embodiment, the output shaft 26 of the engine section 7 is used as the housing shaft that engages with the housing 37, and the propulsion shaft 34 is used as the push screw shaft that engages with the push screw 40. The invention is not limited to this,
It can be installed at any position in the power transmission system between the engine and the rear wheels 13. Also, the housing 37 is moved toward the rear wheel 13 side, and the push screw 4
It is also possible to arrange it so that 0 is on the engine side.

Furthermore, since the above embodiment is applied to a motorcycle equipped with a small single-cylinder engine, the radius of the coil spring 48 and the torsion spline 41 is By appropriately selecting the torque and pitch (twist angle), it is possible to sufficiently absorb engine torque fluctuations and significantly improve ride comfort. However, it goes without saying that the present invention is not limited to small cars.

〔Effect of the invention〕

As explained above, according to the present invention, the cylindrical housing to which the housing shaft is slidably coupled;
A push screw inserted into the housing is coupled by a torsion spline, and the push screw shaft is slidably coupled to the push screw in the axial direction, and the push screw is connected to the push screw shaft. A washer that is in contact with the user is slidably attached, and a retainer for interposing a compression spring between the push screw shaft and the washer and a retainer for bringing the push screw into contact are fixed to the push screw shaft. Therefore, the torque fluctuation between the housing shaft and the push screw shaft is changed into forward and backward movement of the push screw with respect to the housing, and the torque fluctuation is absorbed by the deformation of the compression spring caused by this movement. I can do it.

Therefore, the spring constant of the damping mechanism can be freely changed by changing the radius and pitch of the compression spring and the torsion spline, increasing the degree of freedom in selecting the spring constant. In addition, even though there is a large degree of freedom in selecting the spring constant, it is possible to absorb torque fluctuations transmitted not only from the engine side to the drive wheel side but also from the drive wheel side to the engine side, so when suddenly starting or accelerating At the same time, since the buffer mechanism operates even when the engine brake is applied, the shock transmitted to the driver is reduced, and the driver does not feel uncomfortable.

Moreover, the torsion angle between the housing shaft and the push screw shaft also depends on the pitch of the torsion spline.
By changing the length in the axial direction, etc., it becomes possible to freely select the shock absorbing mechanism, which has the advantage that the optimum shock absorbing mechanism can be obtained depending on the vehicle.

[Brief explanation of the drawing]

FIG. 1 is a side view of a small motorcycle incorporating the power transmission device for a motorcycle according to the present invention, FIG. 2 is a plan view showing a part of the power transmission device in cross section, and FIG.
The same figure is an exploded perspective view of the main parts, and FIG. 4 is an explanatory diagram of its operation. 26... Output shaft as housing shaft, 34...
...propulsion axis as pushscrew axis, 36...
... Buffer mechanism, 37 ... Housing, 40 ... Push screw, 41 ... Torsion spline, 45
... Washer, 46 ... Retainer, 48 ... Compression coil spring.

Claims (1)

[Claims] 1 a push screw 40 inserted into a cylindrical housing 37 and torsionally spline connected to the inner peripheral surface of the housing 37;
A housing shaft 26 and a push screw shaft 34 are slidably coupled in the axial direction to the push screw shaft 7 and the push screw 40, respectively; A washer 45 whose end face abuts against the push screw shaft 34 , a compression spring 48 interposed between the washer 45 and a retainer 46 fixed to the push screw shaft 34 , and the push screw shaft 34 A power transmission device for a motorcycle, characterized in that the retainer 43 is fixed to a distal end of the retainer 43 and a push screw 40 comes into contact with the retainer 43.