JPH0422107Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Industrial application field) The present invention relates to a transmission for a motorcycle.

(Prior Art) Fig. 1 shows a general motorcycle transmission.
In FIG. 1, an input shaft 4 is supported by a case 1 via a pair of bearings 2 and 3, and an end (not shown) protruding from the bearing 2 to the right in FIG. It is connected to the crankshaft at the front of the vehicle. Gears a, b, c, d, e, and f are provided on the input shaft 4 in order from the bearing 2 side toward the bearing 3. gear a
is integral with the input shaft 4, and gears b and e are integral with the input shaft 4.
It can be rotated freely against. Gears c and d are integral with each other and are spline-fitted to the input shaft 4 so as to be able to freely slide in the axial direction, and have protrusions 8 and 9 that can be fitted into holes 6 and 7 of gears b and e (not shown). It has an annular groove 10 into which the shifter fits. The gear f is fitted onto the input shaft 4 so as not to be slidable in the axial direction.

The output shaft 11 is located behind the input shaft 4 and is supported by the case 1 via a pair of bearings 12 and 13. An output sprocket 14 is attached to the left end of the output shaft 11 projecting outward from the bearing 13, and the sprocket 14 is connected to a sprocket on the rear wheel shaft via a chain (not shown).

On the output shaft 11 are gears g, h, i, j, k, l.
are attached in order from the bearing 12 side. Gear g meshes with gear a, and is rotatably fitted to output shaft 11 via bush 15. The gear h meshes with the gear b, and is slidably spline-fitted to the output shaft 11, and has a protrusion 17 that can fit into the hole 16 of the gear g and a protrusion 19 that can fit into the hole 18 of the gear i. and an annular groove 20 into which a shifter (not shown) fits. Gear i and gear j are rotatably fitted to the tips of spline teeth 21 of output shaft 11 while in contact with each other. Gear k is slidably spline fitted to output shaft 11, and a shifter (not shown) is fitted with a projection 23 that can fit into hole 22 of gear J and a projection 25 that can fit into hole 24 of gear L. An annular groove 26 is provided. The gear l is fitted onto the output shaft via a bush 27 and cannot be slid in the axial direction.

If each gear having a hole is referred to as a second gear, the second gear has a shape shown in more detail in FIGS. 2 and 3, for example. Second
The gear 28 has six holes 29 arranged at equal intervals in the circumferential direction, and the holes 29 are elongated holes that are long in the circumferential direction. 30 is an external tooth of the gear 28. on the other hand,
Assuming that each of the gears having conventional projections is referred to as a first gear, the first gear has a shape shown in more detail in FIGS. 4 and 5, for example. 1st
The gear 31 has a hole 29 in the second gear 28 (second
6 protrusions 3 on the circumference with the same radius as (Fig. 3)
2 are arranged at equal intervals. All the protrusions 32 have the same shape, and the protrusions 32 are connected to the holes 29 (second
3), the gears are connected, and torque is transmitted from the input shaft 4 shown in FIG. 1 to the output shaft 11 via the connected gear. Furthermore, protrusions 33 are similarly formed on the opposite side of the gear 31 from the protrusions 32, so that protrusions 33 are equally spaced in the circumferential direction, and can be fitted into a gear (not shown) having another hole. .

However, in FIG. 1, a slight play always occurs between the input shaft 4 and each gear. Particularly, backlash mainly occurs in the first gear which is freely movable in the axial direction. As a result, for example, when connecting gear b as a second gear and gear c as a first gear, an inclination occurs between both gears b and c, and the fitting between the protrusion 8 and the hole 6 is uneven. Put it away. Due to this bias, when power is transmitted from the input shaft 4 to the output shaft 11 via the gears c, b, h, thrust forces parallel to the shaft 4 and opposite to each other act on the gears b, c, so-called A phenomenon occurs in which the gear moves in the direction of disengagement. Therefore, gears b, c,
An unreasonable force is applied to the shifter, etc. that holds the shifter in a direction parallel to the shaft, which is a factor in reducing the durability of the transmission (for example, Publication of Utility Model Publication No. 47-22530).

Here, in a state where the output shaft 11 is driven by the torque input to the input shaft 4 (for example, an acceleration state),
When gears b and c are engaged, and when gears d and e are engaged, a walking phenomenon occurs in the direction of gear disengagement.On the other hand, in the opposite state (for example, engine braking state), gears g,
When h is fitted, when gears h and i are fitted, when gears j and k are fitted, and when gears k and l are fitted, a walking phenomenon occurs in the direction in which the gears come out, resulting in insufficient meshing.

In order to explain in more detail the conditions under which the gear walking phenomenon occurs in the pulling direction, first, the input shaft 4 in FIG.
Looking at the relationship between gears c and b above, gear c, which is axially movably fitted to input shaft 4 and has protrusion 8, is the first gear, and gear b, which has hole 6, is the second gear. , in a driving state in which the output shaft 11 is accelerated by the torque input to the input shaft 4, torque in the rotational direction is transmitted from the first gear c to the second gear b,
As a result, the first gear c receives a thrust force in the direction of withdrawal, and a gear walking phenomenon occurs in the direction of withdrawal.

On the other hand, due to engine braking, etc., the output shaft 11
In the driving state in which torque in the rotational direction is transmitted from the input shaft 4 to the input shaft 4, the torque in the rotational direction is transmitted from the second gear b having a hole to the first gear c having a protrusion. The first gear c receives a thrust force in the direction of biting into the second gear b.

Next, looking at the relationship between the gears h and g on the output shaft 11 in FIG. In the engine braking state where the torque input from the output shaft 11 imparts rotational torque to the input shaft 4, the first gear h (the first gear during engine braking) becomes the second gear.
0) to the second gear g,
Torque in the rotational direction is transmitted, and as a result, the first gear h receives a thrust force in the direction of disengagement, causing a walking phenomenon in the disengagement direction.

On the other hand, when accelerating, the input shaft 4 to the output shaft 11
In a driving state in which torque in the rotational direction is transmitted, torque in the rotational direction is transmitted from the second gear g having the hole to the first gear h having the protrusion,
As a result, the first gear h receives a thrust force in the direction of biting into the second gear g.

(Purpose of the invention) The purpose of the invention is to prevent the so-called walking phenomenon of the gear in the pulling direction, improve the durability of the transmission, and to have a simple structure without increasing the cost. To provide a transmission for a motorcycle that can be easily improved and manufactured from a transmission for a motorcycle.

(Technical Means for Achieving the Object) In order to achieve the above object, the present invention includes a first gear spline-fitted to the central shaft and movable in the axial direction; a second gear fixed in the direction; a plurality of protrusions projecting parallel to the central axis are provided on the first gear at equal intervals in the circumferential direction;
In a motorcycle transmission in which a dog clutch is formed by providing a hole in the second gear that can be fitted into the protrusion, one side is operated by engaging and disconnecting the dog clutch,
Divide the protrusion group into two ranges each with a plurality of protrusions for a certain diameter, and calculate the ratio of the circumferential length of the protrusions in one range to the circumferential length of the hole in the other range. The ratio of the circumferential length of the protrusion to the circumferential length of the hole is made smaller, and rotational torque is applied in the rotational direction from the first gear having the protrusion to the second gear having the hole. In this case, the position of each hole or protrusion in the circumferential direction is set so that the protrusion on the other side comes into contact with the hole, and the protrusion on one side does not come into contact with the hole.

(Example) FIG. 6 is a front view showing a gear of a motorcycle transmission to which the present invention is applied, and is a first gear having a protrusion corresponding to that shown in FIG. 4. FIG. 7 is a cross-sectional view taken from FIG. As is clear from Figure 7,
A protrusion 35 parallel to the center line is formed on the front side of the first gear 34, and a protrusion 36 parallel to the center line and protruding in the opposite direction to the protrusion 35 is formed on the back side. The protrusions 35 of the gear 34 are arranged at equal intervals in the circumferential direction as shown in FIG.
The shape of the protrusion 35a arranged in the upper half of the figure is the fourth
Although the projection 35b has the same shape as the projection 32 of the conventional gear 31 shown in the figure, the projection 35b arranged in the lower half of FIG.
The contact surfaces 37 on the same side are slightly cut out compared to the conventional shape (double-dashed line). Protrusion 36
(Fig. 7) also has a protrusion 36a located in the upper half.
has a conventional shape, with the protrusion 36b located in the lower half cut out.

For example, suppose that such a structure of the protrusion is adopted as the protrusion 8 of the gear c on the input shaft 4 in FIG. 1 as the first gear. Hole 6 of gear b as second gear
When the protrusion 8 of the gear c is fitted into the hole 6 of the gear b, both gears b and c are connected, and the torque of the input shaft 4 is transmitted to the output shaft 11 via the gears c, b, and h. 2 at a certain diameter of the contact surface on the side that comes into contact with
The abutting surfaces of the protrusions 8 (corresponding to the protrusions 35b) on one side are cut out to prevent these cut-out protrusions 8 from coming into contact with the holes 6. With this configuration, even if gears b and c are tilted, both gears b and c
In the meantime, thrust forces in opposite directions parallel to the shaft no longer act, and the so-called gear walking phenomenon in the direction of gear disengagement no longer occurs. The same applies between gears d and e.

On the other hand, between the gears g and h on the output shaft 11, the gear h,
Between gears i, between gears j and k, and between gears k and l, a phenomenon of gear walking in the pull-out direction occurs during engine braking, contrary to the gears between gears b and c and between gears d and e. The contact surface of the protrusion corresponding to the protrusion 35b in FIG. 6 that comes into contact during engine braking must be cut out.

The reason why the gear walking phenomenon in the withdrawal direction can be eliminated or suppressed will be explained with reference to another drawing.

FIG. 10 is a developed view of the dog tooth (protrusion 8) and the hole 6 into which it fits. In the figure, if the drive gear (first gear) c is tilted and the positional relationship with the driven gear (second gear) b becomes as shown, the meshing becomes shallower in order. Therefore, a gear walking phenomenon occurs, resulting in insufficient meshing.

That is, the inner part of the protrusion 8 is engaged during one rotation in the direction of the arrow, and then returns to the engaged position again. Therefore, the engagement position between any projection 8 and hole 6 moves in the axial direction during one rotation, and an axial thrust is applied to the gear. If the driving and driven are reversed, the meshing will be...
Therefore, the walking phenomenon will be in the opposite direction, where the meshing will become deeper.

FIG. 11 is a developed view of the dog teeth of the present invention.
In the present invention, since the meshing teeth (protrusions) are limited to a part of the circumference, the positional relationship between the driving and driven parts is always kept approximately the same, and no further walking phenomenon occurs. That is, since the meshing teeth are present only on a part of the circumference, there is no possibility that the meshing position will move significantly in the axial direction during one rotation even if the drive gear is tilted.

(Effects of the invention) As explained above, the present invention has a first gear 34 which is spline-fitted to the central shaft and which is movable in the axial direction.
and a second gear 28 rotatably fitted to the central shaft and fixed in the axial direction, and the first gear 34 has a plurality of protrusions 35 projecting parallel to the central axis at equal intervals in the circumferential direction. In a motorcycle transmission in which a dog clutch is formed by providing a hole 29 in the second gear 28 that can be fitted into the projection 35, and in which gears are changed by engaging and disconnecting the dog clutch, a plurality of groups of projections 35 are provided for a certain diameter. Divide each book into two areas,
The ratio of the circumferential length of the protrusion 35b in one range to the circumferential length of the hole 29 is the ratio of the circumferential length of the protrusion 35a to the circumferential length of the hole 29 in the other range. When applying a rotational torque in the rotational direction from the first gear 34 having the protrusion 35 to the second gear 28 having the hole 29, the protrusion 35a on the other side is
each hole 29 or protrusion 35 so that the projection 35b on one side does not contact the hole 29
Since the position in the circumferential direction is set, there are the following advantages.

(1) The phenomenon of walking in the direction of gear disengagement can be prevented,
The durability of the transmission is improved, the structure is extremely simple and the cost does not increase, and furthermore, the transmission can be manufactured by simply improving the conventional transmission.

(2) During rotation when the gear does not walk in the direction of disengagement, torque is transmitted by all the protrusions 35 around the entire circumference as before, so the strength of the gear fit is lowered more than necessary. It never gets put away.

Note that the transmission according to the present invention does not need to be applied to all gears having protrusions, and may be applied to each gear as necessary.

The cutout contact surface 37 does not need to contact the hole 29 (FIG. 2), and may be a flat surface instead of a curved surface. Furthermore, although FIG. 7 shows an example in which the protrusions 35 and 36 arranged in the lower half of the gear 34 are cut out, it is not necessary that the protrusions 35 and 36 on the same side are cut out. In the figure, the protrusion 36 on the upper half
may be cut out.

In another embodiment, as shown in FIG.
The length of a part of the hole 29 in the rotational direction may be extended so that the protrusion 32 of the gear 31 does not come into contact with it, or the length of the hole 29 in the rotational direction may be shortened as shown in FIG. You can.

[Brief explanation of the drawing]

Fig. 1 is a partial cross-sectional view of a general transmission, Fig. 2 is a front view showing an example of a gear with holes, Fig. 3 is a cross-sectional view of Fig. 2, and Fig. 4 shows a protrusion of a conventional example. 5 is a cross-sectional view of FIG. 4, FIG. 6 is a front view of an example of a gear having protrusions according to the present invention, and FIG. 7 is a cross-sectional view of FIG. 6. 8 and 9 are front views showing different embodiments, and FIGS. 10 and 11 are developed views of dog teeth of the conventional example and the present invention, respectively. 4...Input shaft (center axis), 6, 7, 16, 18,
22, 24, 29... hole, 8, 9, 17, 19,
23, 25, 32, 35, 36...protrusion, 11...
...Output axis (center axis), b, e, g, e, j, l,
28...Second gear, c, d, h, k, 31, 3
4...First gear.

Claims (1)

[Scope of utility model registration request] It has a first gear spline-fitted to the center shaft and movable in the axial direction, a second gear rotatably fitted to the center shaft and fixed in the axial direction, and the first gear is connected parallel to the center shaft. In a motorcycle transmission, a transmission for a motorcycle is provided with a plurality of protrusions projecting at equal intervals in the circumferential direction, a dog clutch is formed by providing a hole in the second gear that can be freely fitted into the protrusion, and the gear is changed by engaging and disengaging the dog clutch, Divide the protrusion group into two ranges each with a plurality of protrusions for a certain diameter, and calculate the ratio of the circumferential length of the protrusions in one range to the circumferential length of the hole in the other range. be smaller than the ratio of the circumferential length of the protrusion to the circumferential length of the hole;
When a rotational torque is applied in the rotational direction from a first gear having a protrusion to a second gear having a hole, the protrusion on the other side comes into contact with the hole, and the protrusion on one side contacts the hole. A transmission for a motorcycle, characterized in that the position of each hole or protrusion in the circumferential direction is set so that the protrusion does not come into contact with the hole.