JPH0794866B2 - Anti-jump mechanism for transmission - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a jump prevention mechanism for a transmission.

[Prior art]

2. Description of the Related Art In some transmissions for motorcycles, a fork is moved left and right by a speed change drum having a cam groove on its surface, and the speed change gear is operated by the left and right movement of the fork. As an operation mechanism for operating the transmission drum of this transmission from the outside, there is a ratchet type operation mechanism.

In the ratchet system, a plate-like body that rotates integrally with the drum shaft and a rotatable support plate are attached to the drum shaft end of the transmission drum, and the ratchet is urged toward the outer side in the radial direction on the support plate. The ratchet tip is disengageably engaged with a feed groove provided on the inner periphery of the plate-like body, and the support plate is rotated in conjunction with the swing operation of the speed change lever. The transmission drum is rotated through engagement between the transmission drum and the feed groove.

However, in this ratchet system, when the gear shift lever is vigorously full-stroked, the gear shift drum side may excessively rotate due to inertial force or the like, jump over a predetermined gear shift position, and rotate to the next gear shift position.

In order to prevent such jumping phenomenon,
Japanese Patent No. 147 proposes that a stopper is provided to lock the ratchet toward the feed groove side on the outer side in the radial direction when the transmission drum rotates to a predetermined position of full stroke. However, this conventional structure has a drawback that the number of parts is increased and the mounting work is troublesome because a separate stopper is screwed to the surface of the engine case. Therefore, it is extremely disadvantageous especially for a racer vehicle which needs to be maintained in a short time.

[Problems to be Solved by the Invention]

It is an object of the present invention to provide a jump prevention device for a transmission that can reduce the number of parts and improve maintainability while maintaining the compact structure of the ratchet system.

[Means for Solving the Problems]

The present invention that achieves the above object, a plate-shaped body that rotates integrally with the drum shaft and a support plate that is rotatable around the drum shaft are attached to the drum shaft end of the transmission drum so as to face each other.
The support plate supports a ratchet biased outward in the radial direction, and the ratchet tip is disengageably engaged with a feed groove provided on the inner periphery of the disc-shaped body, while the ratchet is centered on the transmission shaft. A swingable shift lever is extended from the shift shaft beyond the center of rotation of the shift drum, and a roller supported by a pin fixed on the support plate is engaged with a long groove provided at the extended end of the shift lever. In this transmission, the support plate is rotatably connected in conjunction with the gear shift operation of the gear shift lever, and the gear shift drum is rotated through the engagement between the ratchet and the feed groove. A stopper protruding to the side of the board is integrally formed in a portion between the speed change shaft and the connecting portion to the support plate, and the stopper prevents the rotation of the board in the full stroke state of the speed change operation of the speed change lever. regulate It is characterized in that it has a formed.

〔Example〕

 The present invention will be described below with reference to the embodiments shown in the drawings.

FIGS. 1 and 2 show a return type transmission among two types of transmissions of a return type and a rotary type. In this transmission, 1 is a transmission drum, and a cam groove 1a is provided on the surface thereof. A fork (not shown) for shifting the transmission gear is engaged with the cam groove 1a. The transmission drum 1 has a drum shaft 2 rotatably supported by an engine case 4 via a bearing 3. A star-shaped cam plate 5 and a plate-shaped body 6 are fixed to the end of the drum shaft 2 protruding to the outside of the engine case 4 so as to rotate integrally, and a support plate 7 is rotatably supported via a shaft 8. It is supported.

The star-shaped cam plate 5 has a plurality of (six in this embodiment) recesses 5a, ... 5a and a notch 5b at the neutral position, the number of which corresponds to the number of gear stages. The recess 5a and the notch 5b
A roller 20 urged by a spring 19 is engaged with the gear, and the engagement of the roller 20 causes the transmission drum 1 to stand still at a predetermined gear shift position or neutral position.

A plurality of (six in this embodiment) feed grooves are provided on the inner circumference of the disc-shaped body 6 at predetermined intervals in the circumferential direction, the number corresponding to the number of shift stages.
9, ... 9 are provided. A pair of ratchets 10a, 10b are pivotally supported on the support plate 7 so as to be swingable, and are biased radially outward by a single spring 11. The ratchets 10a, 10b thus urged are in a state in which about half of the thickness direction is inserted into the inside of the plate-shaped body 6, and the claw at the tip thereof is inserted into the feeding grooves 9, 9 on the side of the plate-shaped body 6. They are engaged with each other.

Reference numeral 22 is a cam plate fixed to the engine case and covers the front side of the feed grooves 9, ... 9 of the plate-shaped body 6 over approximately 240 °. Therefore, the ratchet 10 pivotally supported by the support plate 7
When the tip ends of a and 10b pass through the inner peripheral edge region of the cam plate 22, they are pushed inward in the radial direction by the inner peripheral edge of the cam plate 22 and separated from the feed groove 9.

Further, a roller 13 is attached to the support plate 7 via a pin 12, and the roller 13 is provided with a long groove 15 provided in a speed change lever 14.
It is slidably fitted to. The speed change lever 14 is rotatably supported by the speed change shaft 16 while being biased by the return spring 17, and is interlocked with a speed change pedal (not shown). Reference numeral 18 denotes a pin fixed to the engine case, which serves as a stopper that regulates the rotation angle of the shift lever 14. In this way, the gear shift lever 14 is swingably provided around the gear shift shaft 16, and its end portion is extended so as to exceed the rotation center of the gear shift drum 1, and the extended end portion is provided with the pin 12 and the roller 13 through Although the support plate 7 is connected, a pair of stoppers 21a, 21a, 21b is integrally formed.

Next, the operation of the above-described transmission will be described with reference to FIGS.

By operating a shift pedal (not shown), the shift lever 14 is swung about the shift shaft 16 as shown in FIG. 3 by a full stroke as shown by an arrow A. By this swing, along the roller 13 or the long groove 15, The support plate 7 is rotated by moving from the upper end to the lower end as shown by an arrow a. The rotation of the support plate 7 causes the ratchet 10a to move as shown by an arrow b, and the disc-shaped body 6 rotates as shown by an arrow c via the feed groove 9 that engages with the ratchet 10a. At this time, the other ratchet 10b
Is pushed inward in the radial direction by the cam plate 22, is separated from the feed groove 9, and rotates together with the support plate 7.

On the other hand, since the stopper 21a on the back side is moved as shown by the arrow d due to the swing of the speed change lever 14, the tip of the ratchet 10a which is in contact with the stopper 21a is pushed up in the radial direction and the feed groove. It will be in a state of being sandwiched between the rear surface of 9 and. For this reason, the plate-shaped body 6 stops, and even if it is attempted to rotate further due to inertial force, it cannot continue its rotation. By stopping the rotation of the board 6,
Since the transmission drum 1 also does not rotate, the jump phenomenon does not occur.

The above is the case where the transmission lever 14 is operated to the left side in the front view of FIGS. 2 and 3, but when operating the transmission lever 14 to the right side, the other ratchet 10b and the other stopper 21b operate in the same manner as described above. I do.

In the above jump prevention mechanism, the shift lever 14 is provided with the stoppers 21a and 21b, and the stoppers 21a and 21b are provided at an intermediate portion between the shift shaft 16 of the shift lever 14 and the connecting portion to the support plate 7. Since it is provided, the original length of the speed change lever 14 is not extended and expanded to both outer sides to install the stopper, and the compact structure peculiar to the ratchet system is not hindered and maintained as it is. be able to. Also, the stopper
Since 21a and 21b are formed integrally with the speed change lever 14, the number of parts can be reduced as compared with the conventional separate stopper. In addition, since it is not necessary to perform a mounting work such as a conventional separate stopper, maintainability can be improved. Therefore, it is particularly advantageous in the case of a racer vehicle that requires maintenance in a short time.

〔The invention's effect〕

As described above, according to the present invention, in the ratchet type transmission, the stopper is integrally formed with the shift lever, and the stopper is provided at an intermediate portion between the shift shaft of the shift lever and the connecting portion to the shift plate. Therefore, the compact structure peculiar to the ratchet system can be maintained without increasing the original length of the shift lever. Further, since the stopper is integrally formed, the number of parts can be reduced as compared with the case where a separate stopper is provided in the related art, and the mounting work is unnecessary, so that the maintainability can be improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an anti-jump mechanism of a motorcycle transmission according to an embodiment of the present invention, FIG. 2 is a front view of the same mechanism, and FIG. 3 is a front view illustrating the operation of the same mechanism. . 1 ... Variable speed drum, 2 ... Drum shaft, 6 ... Board, 7
...... Support plate, 9 ...... Feed groove, 10a, 10b ...... Ratchet, 1
1 …… spring, 12 …… pin, 13 …… roller, 14 …… shift lever, 15 …… long groove, 21a, 21b …… stopper.

Claims (1)

[Claims] 1. A plate-like body that rotates integrally with the drum shaft and a support plate that is rotatable around the drum shaft are attached to the drum shaft end of the transmission drum so as to face each other. The ratchet urged toward the ratchet is supported and the tip of the ratchet is disengageably engaged with the feed groove provided on the inner circumference of the board, while the gear shift lever is swingable about the gear shift shaft. The support plate is extended beyond the rotation center of the transmission drum from the transmission shaft, and the support plate is engaged with a long groove provided at the extended end of the transmission plate so that the support plate is supported by a pin fixed on the support plate. In the transmission, which is rotatably connected in association with the gear shift operation and further rotates the gear shift drum through the engagement between the ratchet and the feed groove, a gear shift lever for the gear shift shaft and the support plate is provided. The part between the connecting part The plate-like side stopper projecting integrally formed, the stopper interlace preventing mechanism of the speed change apparatus in the configuration for regulating the rotation of said plate-like member in shifting operation full stroke state of the shift lever.