JPS6212136Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission for a motorcycle that includes a transmission mechanism that is shifted in conjunction with the rotation of a shift drum.

Conventionally, when this type of device is equipped with a transmission mechanism that can be shifted to three speeds, for example, low, middle, and high, the shift drum is sequentially switched from a low speed shift position to a medium speed shift position and a high speed shift position by rotation of the shift drum. When further rotated from the high-speed shift position, it is returned to the low-speed shift position, but according to this, if the shift drum is mistakenly operated from the high-speed shift position while driving, the shift drum will inadvertently shift to the low-speed shift position without passing through the medium-speed shift position. It is desirable to prevent this erroneous operation, as there is a risk that the driver may feel uncomfortable if the driver is switched to erroneous operation.

The present invention aims to provide a device that satisfies such demands, and is composed of a speed change mechanism that is sequentially switched to a high-speed shift position in conjunction with the rotation of a shift drum, and a lock mechanism that is provided on a transmission shaft of the speed change mechanism and prevents the rotation of the shift drum from the high-speed shift position to the low-speed shift position,
The lock mechanism is characterized in that it is formed by a lock piece that is frictionally engaged with the transmission shaft via a resilient body and is urged toward the shift drum by the rotation of the transmission shaft, and a notch on the radially inner side of the outer periphery of the shift drum for engaging the lock piece.

Next, embodiments of the present invention will be explained with reference to attached drawings.

In FIG. 1, 1 is a transmission case, 2 is a transmission mechanism housed in the case 1, and the transmission mechanism 2 is
Although not shown, it includes an input shaft 4 having a driven gear 3 at the end connected to the crankshaft of the engine via a clutch, and an output shaft 6 having a chain sprocket 5 at the end connected to the drive wheel, First and second shift gears 7-1 and 7-2, which are spline-engaged with the input shaft 4 and the output shaft 6, are connected to the first and second shift gears 7-1 and 7-2 on the shift drum 8 which is arranged in parallel with both the shafts 4 and 6. According to the rotation of the shift drum 8 from the illustrated neutral position by sliding the shift forks 9-1 and 9-2, the second shift gear 7-2 is first slid to the left in the low-speed shift position. , the second shift gear 7-2 is connected to the rotatable low-speed driven gear 11 on the output shaft 6 that meshes with the low-speed drive gear 10 on the input shaft 4, so that the low-speed gear train is engaged, and then the medium-speed In the shift position, the second shift gear 7-
2 is returned to the neutral position, the first shift gear 7-1 is slid to the left, and the second shift gear 7-2
The first shift gear 7-1 is connected to a rotatable medium-speed drive gear 12 on the input shaft 4 that is always engaged with the input shaft 4 to form a medium-speed gear train. is returned to the neutral position, and the second shift gear 7-2 is slid to the right, and the rotatable high-speed driven gear 13 on the output shaft 6 meshing with the first shift gear 7-1 engages the second shift gear 7-2.
The shift gear 7-2 is connected to engage the high-speed gear train.

The shift drum 8 has an engagement pin 14 at its outer end.
As clearly shown in FIG. 2, the engagement pin 14 has a claw piece 15a at the tip of the shift arm 15 that swings in conjunction with a shift pedal (not shown).
as the shift arm 15 swings.
Rotation is given in increments of 90 degrees, and according to the counterclockwise rotation in the drawing from the neutral position, it is sequentially rotated to the above-mentioned low speed shift position, medium speed shift position, and high speed shift position. Now returns to neutral position.

In the drawing, reference numeral 16 indicates a cam plate provided at the outer end of the shift drum 8, and the cam plate 16 cooperates with a cam stopper 17 that is in elastic contact with the cam plate 16 to elastically engage the shift drum 8 at each shift position. It works to stop it.

Although the above is not particularly different from the conventional type described above, according to the present invention, a lock mechanism 18 that is activated by detecting the running condition is provided to prevent the rotation of the shift drum 8 from the high speed shift position to the low speed shift position. I tried to prevent it.

To explain this in more detail, the lock mechanism 18 includes, for example, a lock piece 19 whose tip end faces the circumferential surface of the shift drum 8 as shown in FIG. A notch 20 is formed so that the tip of the lock piece 19 is engaged by counterclockwise rotation from the shift position to the low-speed shift position. In a running state in which the output shaft 6 is rotated, the output shaft 6 is rotatably supported by a center boss 21 that is spline-engaged with the center boss 21 and is frictionally engaged with the center boss 21 via a friction spring 22. The spring 22 is attached to the lock piece 19.
In the drawing, the tip of the lock piece 19 is pressed against the circumferential surface of the shift drum 8, so that a pressing force is applied in the clockwise direction, and further, the tip of the lock piece 19 is in a state where no pressing force is applied. When the shift drum 8 is rotated, an inclined cam 2 contacts the end wall of the notch 20 and causes the lock piece 19 to swing in a counterclockwise direction.
3 was formed.

In addition, when there is a neutral position between the high speed shift position and the low speed shift position as shown in the figure, the notch 20 is
The lock piece 19 may be engaged between the high speed shift position and the neutral position, but in the illustrated embodiment, the lock piece 19 is engaged between the neutral position and the low speed shift position. It was formed so that

Next, to explain its operation, when the shift drum 8 is not rotated from the neutral position to the low speed shift position as shown in FIG. 8 is rotated, the lock piece 19
As shown in the figure, the end wall of the notch 20 comes into contact with the inclined cam 23 at the tip and is swung counterclockwise, so that the locking piece 19 and the notch 20 do not engage with each other. If you try to rotate the shift drum 8 from the high speed shift position to the neutral position and then to the low speed shift position in this state, the rotation of the output shaft 6 will cause the lock piece 1 to
Since a clockwise pressing force is applied to the lock piece 9, the tip of the lock piece 19 bites into the notch 20 as it rotates from the neutral position, and the end wall of the notch 20 comes into contact with the inclined cam 23. Instead, as shown in FIG. 5, the leading edge of the lock piece 19 abuts and engages with the end wall of the notch 20, preventing rotation to the low speed shift position. When the shift pedal is released in this state, the shift drum 8 is returned to the neutral position by the elastic force of the cam stopper 17 which abuts against the cam plate 16 at its outer end as shown by the dotted line in FIG.

Note that when the shift drum 8 is rotated clockwise from the high speed shift position and returned to the low speed shift position via the medium speed shift position, the locking operation by the lock mechanism 18 is not performed.

FIG. 6 shows another embodiment in which the lock piece 19 is connected to the boss of the gear 25 on the input shaft 4 which is engaged with the gear 24 on the output shaft 6 and rotates as the output shaft 6 rotates. The lock piece 19 and the gear 25 are frictionally engaged with each other through a friction spring 22 in the form of a disc spring, so that the lock piece 19 is supported by the rotation of the output shaft 6. Accordingly, a pressing force is applied in the direction of pressing the shift drum 8 through the gears 24, 25 and the friction spring 22, and in the running state in which the output shaft 6 rotates, it is the same as in the above embodiment. The notch 20 of the shift drum 8 is located between the high speed shift position and the neutral position or between the neutral position and the low speed shift position.
The lock piece 19 engages with the shift drum 8.
rotation from the high speed shift position to the low speed shift position is prevented.

The embodiment shown in FIG. 6 is equipped with a four-speed transmission mechanism 2, and the shift drum 8 moves from the illustrated neutral position to a low-speed shift position where a gear train corresponding to the low-speed gear train is engaged, and from a neutral position shown in the figure to a low-speed shift position where the gear train corresponding to the low-speed gear train is engaged. A second shift position where a second gear train corresponding to the gear train is engaged, a third shift position where a third gear train corresponding to the high speed gear train is engaged, and a first shift gear 7-1 on the input shaft 4 is connected to the gear 25. Then, the gear 25 and the gear 24 are sequentially rotated to a high-speed shift position where the high-speed gear train is engaged. Further, in the above embodiment, the notch 20 is connected to the shift drum 8.
Although a groove is formed on the circumferential surface of the shift drum 8, it is also possible to form a groove for fixing the core mold of the shift drum 8 as shown in FIG.

Furthermore, in the above embodiment, the running state is detected by the rotation of the output shaft 6, but the input shaft 4 is also rotated when the vehicle is running, and when the vehicle is stopped, its rotation is stopped together with the output shaft 6 by the brake. The locking mechanism 18 detects the running state by the rotation of the input shaft 4.
may be activated.

FIG. 8 shows such an embodiment, and the transmission mechanism 2 itself is the same as that shown in FIG.
A lock piece 19 is frictionally engaged with the upper high-speed driven gear 13 via a friction spring 22.

Note that when there is a neutral position between the high-speed shift position and the low-speed shift position, in this embodiment, the lock piece 19 has the notch 2 between the high-speed shift position and the neutral position.
0 must be engaged.

When engaged between the neutral position and the low speed shift position, when the shift drum 8 is rotated from the neutral position to the low speed shift position and a starting operation is performed,
Lock piece 19 caused by idling rotation of input shaft 4
The locking mechanism 18 is actuated by the pressing force on the
This is because the starting operation is obstructed.

In this way, according to the present invention, the shift drum 8
The transmission mechanism which is sequentially switched to a high speed shift position in conjunction with the rotation of the shift drum 8 has a lock provided on the transmission shafts 4 and 6 to prevent rotation of the shift drum 8 from the high speed shift position to the low speed shift position. Mechanism 18
, it is possible to prevent sudden downshifts from high gear to low gear while driving, and the lock mechanism 18 is frictionally engaged with the transmission shafts 4 and 6 via the elastic body 22 to prevent the transmission from occurring. This is because it is formed with a lock piece 19 that is urged toward the shift drum 8 by rotation of the shafts 4 and 6, and a notch 20 on the radially inner side of the outer periphery of the shift drum to engage the lock piece 19. When the transmission shafts 4 and 6 are rotating, the lock piece 19 is urged toward the shift drum, but except for the notch 20, the lock piece 19 only contacts the outer periphery of the shift drum 8 and does not hinder its high-speed operation. At the notch 20, the locking piece 19 engages with the notch 20 to prevent shifting from high speed to low speed, and also prevents the transmission shaft 4,
When gear 6 is not rotating, lock piece 19 is not biased, and lock piece 1 remains unchanged even when shifting from high speed to low speed.
Since the gear 9 does not engage with the notch 20, it is possible to shift from high speed to low speed, which has the effect of quickly shifting the speed change gear position to the low speed position.

[Brief explanation of the drawing]

Fig. 1 is a cutaway sectional view of an example of the device of the present invention in an expanded state, Fig. 2 is a side view taken along the - line in Fig. 1, and Fig. 3 is a cross-sectional view taken along the line -
The figures are a side view taken along the line -- in Fig. 1, Fig. 4 a side view cut away to explain the inoperative state of the lock mechanism, and Fig. 5.
The figure is a cutaway side view illustrating the operating state of the lock mechanism, and FIG. 6 is a cutaway sectional view of another embodiment in the unfolded state.
FIG. 7 is a cross-sectional side view of the main parts of a modified example of the locking mechanism, and FIG. 8 is a cross-sectional view of still another embodiment in an expanded state. 2... Speed change mechanism, 4, 6... Transmission shaft, 8... Shift drum, 18... Lock mechanism, 19... Lock piece, 20... Notch, 22... Bullet body.

Claims (1)

[Scope of utility model registration request] a transmission mechanism that is sequentially switched to a high-speed shift position in conjunction with rotation of a shift drum; and a lock mechanism that is provided on a transmission shaft of the transmission mechanism and prevents rotation of the shift drum from a high-speed shift position to a low-speed shift position. a lock piece that is frictionally engaged with the transmission shaft via an elastic body and urged toward the shift drum by rotation of the transmission shaft; and a lock piece that engages the lock piece. 1. A transmission for a motorcycle, characterized in that the shift drum has a notch on the radially inner side of the outer periphery of the shift drum.