JPS6226959B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a breather device for a gear case of a shaft drive type power transmission mechanism in a motorcycle.

Generally, in a shaft drive type power transmission mechanism for a motorcycle, a drive bevel gear that is integrally provided at the rear end of a propeller shaft that is linked to the engine is meshed with a driven bevel gear that is mounted on a rear fork and is linked to the rear wheel. The drive and driven bevel gears are housed in a sealed gear chamber in a gear box provided on one side of the rear fork, and the rotation is transmitted to the rear wheels by lubricating oil sealed in the chamber. The gearbox is designed to be lubricated, but in order to reduce air resistance during rotation of the drive and driven bevel gears, especially at high speeds, the gearbox includes:
It is necessary to provide a breather device for the gear room.

Therefore, the main object of the present invention is to provide a breather device for a gear case in a two-wheeled motor vehicle with a simple structure, which promotes the breathing action of the gear chamber, and is integrated with the propeller shaft connected to the engine. A driving bevel gear and a driven bevel gear rotatably mounted on the rear fork and interlocked with the rear wheel are meshed, and the driving and driven bevel gears are stored in a gear chamber of a gear case provided in the rear fork, and a wall surface of the gear case is A main breather passage that communicates the gear chamber with outside air, and an auxiliary breather passage that communicates the gear chamber with the main breather passage are formed, and the auxiliary breather passage is narrowed in the middle with a shim plate for positioning the driven bevel gear. I'm trying to form a path.

A first embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

In Figure 1, the body frame F of the motorcycle
The V-type engine E is installed horizontally (its crankshaft 1
is mounted in a direction perpendicular to the longitudinal direction of the vehicle body frame F. Propeller shaft 2 connected to the engine E
extends in the longitudinal direction of the vehicle body frame F, running longitudinally within the rear fork 3 which is pivotally supported by the vehicle body frame F so as to be swingable up and down.

As shown in FIG. 2, the rear end of the propeller shaft 2 is rotatably supported by a rear fork 3 via a ball bearing 4, and a drive bevel gear 11 is integrally provided at the rear end.

On the other hand, a rear wheel W is rotatably supported on an axle 5 horizontally mounted on the rear fork 3 via ball bearings 6 and 7. The rear wheel W is connected to a hollow power transmission shaft 10 rotatably supported by the rear fork 3 via ball bearings 8 and 9. The hollow transmission shaft 10 passes through the axle 5 and is arranged concentrically with the axle 5, and a driven bevel gear 12 is spline-coupled to the outer periphery of the hollow transmission shaft 10. The driven bevel gear 12
is meshed with the drive bevel gear 11 which is integrated with the propeller shaft 2. Therefore engine E
When the propeller shaft 2 is rotated by the operation of
The power is transmitted to the hollow power transmission shaft 10 via the shaft 10, and the rear wheels W connected to the shaft 10 can be driven.

The driving and driven bevel gears 11 and 12 are housed in a gear case 13 provided on one side of the rear fork 3 and integrally therewith. The gear chamber C in the gear case 13 is formed to be oil-tight, and the opening on the rear wheel W side and the opening on the propeller shaft 2 side of the gear chamber C are both sealed by oil seals 14 and 15. is filled with an appropriate amount of lubricating oil O.

A breather device B for causing the gear chamber C to breathe is provided on the wall surface of the gear case 13. Next, to explain the configuration of this device B, the gear case 13 has a main breather passage 16 on the wall surface that communicates the gear chamber C with the outside air, and an auxiliary breather passage 17 that communicates the main breather passage 16 with the gear chamber C. is formed. Main breather passage 1
6 is bored approximately vertically into the wall of the gear case 13,
Its lower end is opened between the driven bevel gear 12 and the ball bearing 8 in the gear chamber C. Further, its upper end is open to the outside air, and a breather cap 19 is screwed thereto. The breather cap 19 prevents rainwater, dust, etc. from entering the main breather passage 16. In addition, the auxiliary breather passage 17 is connected to the gear case 13.
It is bent from the upper wall to the inner wall, and its lower end communicates with the gear chamber C through the gap between the inner race 9i and outer race 9o of the ball bearing 9, and its upper end communicates with the main breather passage 16. They are connected almost perpendicularly in the middle. As shown in FIG. 4, an annular shim plate 20 for positioning the driven bevel gear 12 is interposed between the inner race 9i of the ball bearing 9 and the back surface of the driven bevel gear 12.
This shim plate 20 is formed to have a larger diameter than the outer diameter of the inner race 9i, and its outer periphery protrudes between the inner race 9i and the outer race 9o. Since the gap between the inner race 9i and the outer race 9o is a part of the auxiliary breather passage 17, the gap between the shim plate 20 and the outer race 9o is
The narrow passage 17a of the auxiliary breather passage 17 is
is formed. The gap ΔX between the narrow passage 17a is the inner race 9i and the outer race 9o.
It is preferable to set the gap to about 1/3 of the gap X between the two (for example, X=6 mm, ΔX=2 mm).

Further, in the auxiliary breather passage 17, on the downstream side of the narrowed passage 17a, there are first and second expansion chambers D ₁ ,
D ₂ is formed. That is, a first expansion chamber _D1 is formed between the ball bearing 9 and the oil seal 15, and a second expansion chamber _D2 is formed in the middle of the auxiliary breather passage 17 on the downstream side of the chamber _D1 . The air mixed with lubricating oil that has passed through the narrow passage 17a is transferred to the first expansion chamber D ₁ and then to the second expansion chamber.
The lubricating oil is expanded in stages in D ₂ and separated efficiently.

Next, to explain the operation of the first embodiment of the present invention, when the engine E is driven to run the motorcycle, the propeller shaft 2 is rotated, and this rotation is caused by the drive bevel gear 11, the driven bevel gear 12, and the hollow It is transmitted to the rear wheels W via the transmission shaft 10.

The gear chamber C includes driving and driven bevel gears 11,
12, the main breather passage 16 and the auxiliary breather passage 17 are
In this case, the air flowing through the auxiliary breather passage 17 passes through the narrow passage 17a formed in the middle of the passage and is constricted, and then enters the first and second expansion chambers D ₁ and D. At that _time , the lubricating oil mixed in the air flowing through the auxiliary breather passage 17 is efficiently separated, and only the air flows to the main breather passage 16, and the lubricating oil in the passage 16 is Blockage due to oil film is prevented, air flow within the passage 16 is improved, and the gear chamber C is efficiently ventilated.

FIG. 5 shows a second embodiment of the invention. In this embodiment, an annular shim plate 20' for positioning the driven bevel gear 12 is sandwiched between the outer race 9o of the ball bearing 9 and the gear case 13.
0' is made smaller than the inner diameter of the outer race 9o, and its inner circumference protrudes between the inner race 9i and the outer race 9o to form a narrow passage 17'a in the auxiliary breather passage 17. The configuration is the same as that of the first embodiment.

FIG. 6 shows a third embodiment of the invention. In this third embodiment, the gear 12 is connected between the back surface of the driven bevel gear 12 and the inner race 9i of the ball bearing 9.
An annular first shim plate 22 for positioning is sandwiched, and the outer race 9o of the ball bearing 9
An outer peripheral portion of an annular second shim plate 23 is held between the gear case 13 and the gear case 13 . This second shim plate 23 has an inclined surface 2 that slopes downward toward the oil seal 15.
3a, the inner periphery of which is equipped with an oil seal 1
5 and its inner peripheral edge is the oil seal 15.
The lip piece 15a is polymerized with the lip piece 15a. The outer diameter of the first shim plate 22 is equal to the inner race 9i of the ball bearing 9.
On the other hand, the inner peripheral edge of the second shim plate 23 cooperates with the lip piece 15a of the oil seal 15 to form a narrow passage 17a of the auxiliary breather passage 17. is formed. Furthermore, in this third embodiment, the inclined surface 23a of the second shim plate 23 prevents the lubricating oil in the gear chamber C from scattering outward in the radial direction due to the centrifugal force, so that the lubricating oil droplets are sprayed onto the auxiliary breather. It can be prevented from entering the passage 17.

As is clear from the above embodiments, according to the present invention, a main breather passage that communicates the gear chamber in the case with the outside air and a gear chamber are provided on the wall surface of the gear case housing the driving and driven bevel gears that mesh with each other. An auxiliary breather passage is formed in the middle of the main breather passage to communicate with the main breather passage, and a narrow passage is formed in the middle of the breather passage by a shim plate for positioning the driven bevel gear, and an expansion chamber is formed on the downstream side of the narrow passage. After being constricted in the narrow passage, it flows into the expansion chamber, and at that time, it efficiently separates the lubricating oil mixed in the air and allows only the air to flow into the main breather passage, promoting the flow of air within the passage. This allows the gear chamber to efficiently breathe, and reduces the rotational resistance of the driven and driven bevel gears due to the air sealed in the gear chamber.

[Brief explanation of the drawing]

Figures 1 to 4 show a first embodiment of the present invention, Figure 1 is a side view of a two-wheeled motor vehicle equipped with the device of the present invention, and Figure 2 is an enlarged cross-sectional view taken along the line shown in Figure 1. 3 is an enlarged vertical sectional view along the line of FIG. 1, FIG. 4 is a partially enlarged view of FIG. 3, FIG. 5 is a partial sectional view showing the second embodiment of the present invention, The figure is a partial sectional view showing a third embodiment of the present invention. C...Gear chamber, _D1 , _D2 ...First and second expansion chambers, E...Engine, W...Rear wheel, 2...Propeller shaft, 3...Rear fork, 11, 12...Drive, Driven bevel gear, 13...Gear case, 1
6, 17...Main, auxiliary breather passage, 17a...
narrowed path, 20... shim plate, 22, 23... first,
Second shim board.

Claims (1)

[Claims] 1. A driving bevel gear integral with a propeller shaft connected to an engine is meshed with a driven bevel gear rotatably mounted on a rear fork and linked to a rear wheel, and the driving and driven bevel gears are stored in a gear chamber of a gear case provided on the rear fork. A main breather passage that communicates the gear chamber with outside air and an auxiliary breather passage that communicates the gear chamber with the main breather passage are formed on the wall surface of the gear case, and the driven breather passage is formed in the middle of the auxiliary breather passage. A breather device for a gear case in a motorcycle, characterized in that a narrow passage is formed using a shim plate for positioning a bevel gear, and an expansion chamber is formed on the downstream side of the narrow passage.