JP2675577B2 - Neutral braking system for vehicle transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a neutral braking of a transmission for a vehicle, which is adapted to prevent the driven side member of a centrifugal clutch from being entrained in a neutral state and at the time of idle rotation. The present invention relates to an apparatus, and more particularly, to an improvement in a braking structure that prevents an increase in the operation force of the gear shifting operation when the braking force is obtained by utilizing the gear shifting operation to the neutral state.

[Conventional technology]

In the vehicle transmission, when the rotation of the crankshaft is transmitted to the gear transmission via the centrifugal clutch, even when the engine is in neutral, idle rotation is accompanied by rotation of the drive side of the centrifugal clutch. A so-called entrainment phenomenon occurs in which the driven side also rotates. This phenomenon is mainly due to the viscosity of the hydraulic fluid for clutch and the rotational resistance between the driven member and the crankshaft. When such a centrifugal clutch is provided, an abnormal noise may be simply generated due to the tooth surfaces of the transmission or the like being in contact with each other, or a reverse clutch engagement noise may be generated due to fluctuations in the rotation of the crankshaft. . Since this is a very offensive sound, there is a problem of impairing the marketability.

Therefore, conventionally, in order to prevent the generation of this abnormal noise, for example, as described in Japanese Utility Model Laid-Open No. 60-19846, the neutral side is designed to prevent the driven side member from rotating during idle rotation. Braking devices have been proposed. This is because the braking lever is provided so as to come into contact with the outer surface of the driven side drum of the centrifugal clutch, and is biased in a non-contact state, and when the change lever is shifted to the neutral position against the biasing force. The lever is configured to contact the driven drum. According to this device, the driven drum can be prevented from rotating, and the abnormal noise can be prevented from occurring.

[Problems to be solved by the invention]

However, in the braking device described in the above publication, it is necessary to newly provide a braking lever for urging the braking lever into a non-braking state, which increases the number of parts and complicates the structure. In the gear shift operation, it is necessary to operate the change pedal against the biasing force, and the operation becomes heavier by that amount, resulting in a problem of poor operability.

The present invention has been made to solve the above-mentioned conventional problems, and has a very simple structure and can prevent the driven side member from rotating with a light operating force, and as a result, prevents the generation of abnormal noise. It is an object of the present invention to provide a neutral braking device for a transmission for a vehicle, which can improve the marketability.

[Means for solving the problem]

The present invention transmits the rotation of a crankshaft to a gear type transmission through a centrifugal clutch mounted on the crankshaft, usually a multi-plate clutch that transmits a rotational force and manually blocks the rotation transmission only during a gear shifting operation. In a vehicle transmission configured as described above, a neutral braking device for preventing entrainment of a driven side member of a centrifugal clutch in a neutral state and at the time of idle rotation, in an axial direction according to a gear shift operation of the transmission. The shift fork that moves to a position is formed with a braking portion, the braked portion is fixed to the primary shaft of the transmission equipped with the multi-plate clutch so that it cannot rotate, and the braking is performed when the shift fork is completely moved to the neutral position. It is characterized in that the portion comes into contact with the braked portion.

Here, the "manually-disengaging multi-plate clutch" in the present invention means a multi-disc clutch that is in the disengaged state when a gear shift operation such as depressing a shift pedal is performed. The purpose is to exclude clutches that automatically turn on and off as the number increases and decreases.

[Action]

In the neutral braking device according to the present invention, when the change pedal is rotated to the neutral position, the shift fork axially moves to the neutral position similarly to a general transmission, but at this time, the shift fork is formed on the shift fork. The braking portion comes into contact with the portion to be braked that is fixedly formed on the primary shaft, whereby rotation of the driven member is prevented, and the entrainment phenomenon described above and the occurrence of abnormal noise can be prevented.

Further, in the present invention, the rotation prevention of the driven member can be realized by a very simple structure in which the braking portion and the braking portion are respectively formed on the shift fork and the primary shaft which are indispensable for the speed change mechanism. There is no problem that the structure like is complicated.

Further, in the present invention, the operation force to the neutral state is the same as that in the case where the braking device is not provided, and there is no problem that the operability is lowered as in the conventional example.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 and 2 are views for explaining a neutral braking device for a motorcycle according to an embodiment of the present invention.
In the figure, reference numeral 1 is an engine unit in which an engine body and a power transmission mechanism are integrated with each other. The engine unit rotates the crankshaft 2 in a centrifugal clutch 3, a multi-plate clutch 4, and a transmission 5.
It is configured to be transmitted to the rear wheel via.

A piston (not shown) is connected to the crank arm 2a of the crank shaft 2 via a connecting rod 6, and both sides of the crank arm 2a are pivotally supported by ball bearings 7. The centrifugal clutch 3 is mainly configured by spline-fitting a drive plate 8 as a drive side member to the crankshaft 2 and rotatably mounting a dish-shaped driven drum 9 as a driven side member on the crankshaft 2. There is. A shoe 8a is attached to the outer peripheral edge of the drive plate 8 so that it can be rotated outward by a centrifugal force and slidably contacts the inner peripheral surface of the driven drum 9. The driven drum 9 is engaged with a primary drive gear 11 rotatably supported on the crankshaft 2 via a collar 10. A one-way clutch 12 is interposed between the driven drum 9 and the crankshaft 2, and the clutch 12 is configured to transmit only torque from the driven drum 9 side to the crankshaft 2 direction. There is.

The multi-disc clutch 4 is rotatably supported by the primary shaft 13 of the transmission 5, and the outer clutch 15 is fixed to the primary driven gear 14 meshed with the primary drive gear 11, and the inner clutch 16 is fixed to the primary shaft 13. It is configured by spline fitting. The outer and inner clutches 15 and 16 are arranged so that clutch plates 15a and 16a are alternately positioned, and a pressing member 17 is arranged on the outer side of the clutch plates 15a and 16a so as to press the clutch plates 15a and 16a into contact with each other. It is located in. The pressing member 17 is fixed to the tip of an operating rod 18 which is arranged in the primary shaft 13 so as to be movable in the axial direction.
18 shifts to the right in the figure at the time of gear change to disconnect the multi-plate clutch 4.

The transmission 5 includes a gear train and a shift operation unit,
In the gear train, a primary shaft 13 and a secondary shaft 19 are rotatably arranged in parallel with the crankshaft 2, and transmission gears 13a and 19 are provided on the respective shafts.
a to 19c are rotatably mounted and the dog members 13b, 19
It is configured such that d is fitted in serration so as to be movable in the axial direction, and a drive gear 13c is integrally formed with the primary shaft 13.
Further, as shown in FIG. 2, the shift operation unit has a shift cam 20 and a shift shaft 21 arranged in parallel with the primary shaft 13, and the shift cam 20 is rotated by depressing a change pedal. The shift forks 22a and 22b mounted on the shift shaft 21 are configured to move in the axial direction. The shift forks 22a, 22b are slidably engaged in the engagement grooves 13d, 19e of the dog members 13b, 19d, whereby the dog members 13b, 19d are axially moved when the change pedal is rotated. To shift gears 13a, 19a ~
The gear shift operation is performed by engaging 19c.

Further, in this embodiment, a brake plate 23 as a braking member is attached to the shift fork 22a. This brake plate 23
Is made of leaf spring, the base of which is the shift fork 22a.
Is fitted and attached to the flange portion by press fitting, and the tip portion extends near the primary shaft 13. And this primary shaft 13
An abutting plate 24 as a braked portion is fixedly attached to the braking plate 23, and a friction plate 24a is attached to the braking plate 23 side of the corresponding contacting plate 24. It is adapted to come into contact with the plate 24a.

 Next, the operation and effect of this embodiment will be described.

In the apparatus of this embodiment, the crankshaft 2 is used during normal traveling.
Is transmitted to the rear wheels via the centrifugal clutch 3, the multi-plate clutch 4, and the transmission 5. Then, in the neutral state and at the time of idling rotation, the centrifugal clutch 3 is in the disengaged state, but the driven drum 9 is also rotated along with the rotation of the drive plate 8. In this case, the drive plate 8 rotates while slightly fluctuating according to the fluctuation of the engine rotation,
Since the rotation of the driven drum 9 gradually increases and the rotation of the driven drum 9 is substantially constant at this high rotation speed, there may be a moment when the rotation speed of the driven drum 9 becomes higher than that of the drive plate 8. When this happens, the one-way clutch 12 is activated, which causes the resistance to the driven drum 9 to rapidly increase.
As a result, for example, there is a problem that an impact sound is generated between the tooth surfaces of the primary drive gear 11 and the driven gear 14.

On the other hand, in this embodiment, when the change pedal is rotated to the neutral position, the shift fork 22a moves to the first position.
After moving to the state shown in the figure, the braking plate 23 fixed to the fork 22a comes into contact with the friction plate 24a of the contact plate 24, and the rotation of the primary shaft 13 is blocked. Therefore, in the centrifugal clutch 3, the driven drum 9 does not rotate, and therefore, the abnormal noise does not occur.

Further, in the present embodiment, the above-mentioned noise prevention can be realized by a simple structure in which the brake plate 23 is provided on the shift fork 22a which is essential to the speed change mechanism, and the contact plate 24 is provided only on the primary shaft 13. There is no need to newly provide a special braking device as in the conventional example, the structure is simple, and an increase in cost can be suppressed.

Further, in the present embodiment, when the change pedal is rotated to the neutral position, it is not necessary to rotate the pedal against the biasing force of the braking device as in the above-described conventional example. The operability can be improved without causing the problem of increasing

It should be noted that, although the case where the centrifugal clutch having the one-way clutch is provided has been described in the above embodiment, the present invention can of course be applied to the case where the one-way clutch is not provided.

〔The invention's effect〕

As described above, according to the neutral braking device for a vehicular transmission according to the present invention, a braking portion is formed on the shift fork, and a braking portion that comes into contact with the braking portion when the shift fork is moved to the neutral position is provided. Since it is formed on the primary shaft of the speed change mechanism, the braking portion and the braked portion contact with each other during neutral to prevent rotation of the driven side member of the centrifugal clutch, and as a result, generation of abnormal noise due to impact between tooth flanks, It can be prevented without increasing the operation force, and there is an effect that the marketability can be improved. Moreover, there is an effect that the above-mentioned noise prevention can be realized by a simple structure in which the braking portion and the braking portion are respectively formed on the primary shaft and the shift fork which is essential to the speed change mechanism.

[Brief description of the drawings]

FIG. 1 is a sectional development view of a neutral braking device according to an embodiment of the present invention, and FIG. 2 is a sectional development view of a gear shift operation portion thereof. In the figure, 2 is a crankshaft, 3 is a centrifugal clutch, 5 is a gear type transmission, 9 is a driven drum (driven side member), 8 is a drive plate (driving side member), 12 is a one-way clutch, 22
a is a shift fork, 23 is a braking plate (braking part), 24 is a contact plate (braking part), and 13 is a primary shaft (rotating shaft).

Claims (1)

(57) [Claims] Claim: What is claimed is: 1. A gear type transmission, comprising a centrifugal clutch mounted on the crankshaft, a multi-plate clutch for transmitting a rotational force, and manually interrupting the rotational transmission only during a gear shifting operation. In a transmission for a vehicle configured to transmit, a neutral braking device for preventing entrainment of a driven side member of a centrifugal clutch in a neutral state and at the time of idle rotation, and a shaft according to a shift operation of the transmission. When a braking portion is formed on the shift fork moving in the direction, the braked portion is non-rotatably fixed to the primary shaft of the transmission in which the multi-plate clutch is mounted, and the shift fork is completely moved to the neutral position. A neutral braking device for a vehicle transmission, characterized in that a braking portion is brought into contact with a braked portion.