JPS62209250A - Transmission for vehicle - Google Patents

Abstract

PURPOSE:To increase a coaxial accuracy of three bearings and improve the durability, by retaining two bearings for supporting a main shaft to a crank case, and supporting an end portion of the main shaft on a reverse gear side to a boss portion integrally formed with the crank case. CONSTITUTION:A reverse gear 74 is mounted at one end of a main shaft 18. A bearing 18A for supporting the main shaft 18 between the reverse gear 74 and a gear train of a main transmission 26 is retained to a crank case 12a. An end portion of the main shaft 18 on the reverse gear 74 side is supported to a boss portion 12c integrally formed with the crank case 12a. That is, the main shaft 18 is supported by the bearing 18A between the gear 74 and the gear train of the main transmission 26, and is supported at a right end thereof by a bearing 18B. The bearings 18A and 18B are retained to the crank cases 12a and 12b, respectively. The main shaft 18 is further supported at a left end thereof by the boss portion 12c projecting from the crank case 12a. As the boss portion 12c is integrally formed with the crank case 12a as mentioned above, a coaxial accuracy among the boss portion 12c and the bearings 18A and 18B may be increased. Accordingly, the noise due to shaft vibration may be reduced, and the durability may be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a vehicle transmission system that includes a reverse transmission system that bypasses a forward main transmission and transmits engine output to drive wheels.

(Background of the Invention) It has been proposed to provide a reverse transmission system that bypasses the forward main transmission and transmits the engine output to the drive wheels, thereby making it possible to quickly switch between forward and reverse. If the reverse transmission system is installed on the side of the crankcase independently of the main transmission system with such a device, it will be necessary to install a reverse gear at one end of the main shaft of the main transmission to take out the reverse output. . For this reason, the main shaft becomes long, so it is desirable to provide bearings that support the main 1 pongee not only at both ends but also in the middle. Therefore, it is conceivable to hold this intermediate bearing in the crankcase and to support the shaft end of the main shaft in an auxiliary transmission case that houses the reverse transmission system. However, if you try to support the shaft on the crankcase and the sub-transmission cover separate from the sub-transmission cover like this, the accuracy of each bearing part will deteriorate due to machining errors and assembly differences in the crankcase and sub-transmission cover. Problems arise in that RF noise is likely to be generated, which is disadvantageous in terms of durability.

(Objective of the Invention) The present invention was made in view of the above circumstances, and although the main rift is supported at three points, it is possible to improve the accuracy of the axial center of the three bearings. The object of the present invention is to provide a vehicle transmission device that is also suitable for improving durability.

(Structure of the Invention) According to the present invention, the object is to provide a main transmission system including a forward main transmission provided on a main shaft and a counter shaft parallel to the crankshaft, and a main transmission system that bypasses the main transmission and connects the engine to the main shaft. A vehicle transmission including a reverse transmission system that transmits output to drive wheels, wherein a reverse gear is provided on one end side of the main shaft, and the main shaft is supported between the reverse gear and a group of gears of the main transmission. This is achieved by a vehicle transmission characterized in that a bearing is held in the crankcase, and an end of the main shaft on the reverse gear side is supported by a boss integrally formed with the crankcase.

(Example) Fig. 1 is a developed sectional view of an embodiment of the present invention, Fig. 2 is a side view of the engine with the auxiliary transmission cover removed, Fig. 3 is an enlarged side view of the vicinity of the main shaft bearing, and Fig. 4 is a side view of the engine with the sub-transmission cover removed. The figure is a power system diagram of the entire engine, and FIG. 5 is a side view of a four-wheeled vehicle for traveling on rough terrain equipped with this engine.

The engine lO is a left and right crank case 12 (12a
, 12b) and a cylinder 14. The crankcase 12 has a main shaft 18 and a counter shaft 20 parallel to the crankshaft 16.
is pivoted. A starting centrifugal clutch 22 is disposed at the right end of the crankshaft 16, and a speed change clutch 24 is disposed at the right end of the main shaft 18. Further, a group of gears forming a forward main transmission 26 is mounted on the main shaft 18 and the counter shaft 20 balls,
This gear group is housed within the crankcase 12.

This main shift a26 is shifted by a main shift drum 28 (FIG. 2.5) disposed below within the crankcase 12. That is, by operating the shift pedal 30 with your foot, the shift clutch 24 is temporarily disengaged and the main shift drum 28 is turned off.
The cam groove formed on the outer periphery of this drum 28 moves the shift fork 32.34 (Fig. 2) in the engine width direction, changing the meshing of the gear group. This mechanism is different from the conventional one. It's no different from the one.

A sub-transmission 36 is disposed on the left side of the crankcase 12. The auxiliary transmission 36 includes a high/low speed switching mechanism 38 that changes the output of the main transmission 26, that is, the rotation of the subshaft 20 into two high and low speeds, and a reverse switching mechanism 40.

The sub-transmission 36 includes first and second output shafts 4 that are pivotally supported by the sub-transmission cover 42 and the left crankcase 12a.
4.46 and an idle shaft 48, the subshaft 20 passes through the crankcase 12a, and its left end is pivotally supported by the subtransmission cover 42. Shifting of the sub-transmission 36 is performed by a sub-transmission drum 50 disposed on the L side within the sub-transmission cover 42. In other words, this sub-speed change drum 5
0 is a shift fork 56 that is rotated via a link 54 by a manual lever 52 protruding from the left side of the engine 10, as shown in FIG. .58 (FIG. 2) moves the high/low speed switching shifter 60 on the subshaft 20 and the reverse switching shifter 62 on the idle shaft 48.

The high/low speed switching shifter 60 is a high speed gear 6 on the subshaft 20.
4 and the low speed gear 66. These gears 64 and 66 are each gear 6 fixed to the first output shaft 44.
It meshes with 8.70.

A first idle gear 72 is also freely rotatably held on the countershaft 20 adjacent to the crankcase 12a. A reverse gear 74 is press-fitted from the left end of the main shaft 18, and the main shaft 18 is supported by a bearing 18A between this gear 74 and the gear group of the main transmission 26, and the right end is supported by a bearing 18B. Bearings 18A and 18B are held in crankcases 12a and 12b. Further, the left end of the main shaft 18 is supported by a boss portion 12c protruding from the crankcase 12a. The outer diameter of the reverse gear 74 is slightly smaller than the bearing hole 12d into which the bearing 18A is inserted, and the main shaft 18 is inserted into the bearing 12d from the right side, and its left end is engaged with the boss portion 12C. and bearing 18
A is fixed to the crankcase 12a by an arc-shaped holding plate 18c (Fig. 1.3) bolted to the left end surface of the receiving hole 12d. The rotation of the main shaft 18 is transmitted from this gear 74 via the first idle gear 72 to the second idle gear 76 which can freely rotate on the idle shaft 48L. This idle axis 48 also has another southeast 78
are fixed by spline connection, and this gear 78 further meshes with a float 80 fixed to the first output shaft 44.

The reverse shifter 62 engages and disengages from the second idle gear 76 on the idle shaft 48. That is, when the operating lever 52 is in the reverse position, the high/low speed J switching shifter 60 is in the high ◆
While being disengaged from the low-speed gears 64, 66 and held in the neutral position, the reverse shifter 62 engages with the second idle gear 76.

Next, the operation of this embodiment will be explained. First, when the manual operating lever 52 is placed in the forward high speed position, the sub-shift drum 50 slides the reverse shift shifter 62 out of the second idle gear 76 and moves the high/low speed shift shifter 60 into the high speed float 64. engage. When the slave/) lever is used, the L including the main transmission 26
Co-rotation transmission is performed by the transmission system. That is, when the crankshaft 16 rotates 751 times, the centrifugal clutch 22 is connected, and the rotation is transmitted to the second output shaft 46 via the clutch 24, main shaft 18, subshaft 20, high-speed gear 64, and gear 68. It will be done. This rotation of the second output shaft 46 is transmitted to the final output shaft 86 via the bevel gear 82 and the cam type damper 84.

Further, when the operating lever 52 is placed in the forward low speed position, the auxiliary speed change drum 50 moves the high/low speed switching chic 60 to engage the low speed gear 66. At this time, the rotation of the subshaft 20 is the low speed gear 66, south 1i-j 70.

The first output shaft 44 is transmitted via the teeth 11'E 68 to the second output I[ill 46 and further to the final output shaft 86.

When the operating lever 52 is placed in the reverse position, the auxiliary transmission drum 50 moves the high/low speed switching shifter 60 to the neutral position and engages the reverse switching shifter 62 with the second idle gear 76 . Therefore, the rotation of the main shaft 18 is transmitted to the final output shaft 86 by a reverse transmission system that bypasses the main transmission 92B. That is, the rotation of the reverse gear 74 at the left end of the main shaft 18 is caused by the rotation of the first and second idle gears 72, 76 and the first output shaft 44.
h gear 80.68 to the second output shaft 46, and further to the final output shaft 86.

This engine 10 is mounted near the center of the vehicle body as shown in FIG.
It is transmitted to the rear wheel shaft 90 by: - It is transmitted to the rear wheels 92 as driving wheels fixed to the left and right ends of the rear wheel shaft 90. In this figure, 94 is a pair of left and right front wheels, 96 is a steering bar/handle, 98 is a straddle type driver's seat, 100 is a front fender, and 102 is a rear fender.

An oil jacket 200 is formed in the boss portion 12c, and lubricating oil sent from a lubricating oil pump (not shown) is guided to this oil jacket 200 through an oil passage 202 provided in the crankcase 12. Part of it is the main axis 1
8, the remaining part is an oil passage 204 formed in the sub-transmission cover 42.
to each axis 20.44.48.

(Effects of the Invention) As described above, although the main shaft is supported at three points, the boss part that supports the end of the main shaft is formed integrally with the crankcase, so that the boss part and other bearings are not connected to each other. It is possible to increase the accuracy of the shaft center. Therefore, noise due to shaft vibration can be reduced and durability can be improved.

[Brief explanation of drawings]

Fig. 1 is a developed sectional view of an embodiment of the present invention, Fig. 2 is a side view of the engine with the auxiliary transmission cover removed, Fig. 3 is an enlarged side view of the vicinity of the main shaft bearing, and Fig. 4 is the entire engine. Fig. 5 is a side view of a four-wheeled vehicle for traveling on rough terrain equipped with this engine. DESCRIPTION OF SYMBOLS 10...Engine, 12...Crankcase, 12c...Boss part, 16...Crankshaft, 18...Main shaft, 20...Sub-1 oil, 26...Main transmission for forward movement , 36... Sub-transmission, 40... Reverse switching mechanism, 44.46... Output shaft, 74... Reverse gear, 92... Rear wheel as drive wheel. 200...Oil jacket, 202...Oil path.

Claims (2)

[Claims] (1) A main transmission system including a forward main transmission installed on a main shaft and a subshaft parallel to the crankshaft, and a reverse transmission system that bypasses the main transmission and transmits the engine output from the main shaft to the drive wheels. A vehicle transmission comprising: a reverse gear on one end side of the main shaft; a bearing supporting the main shaft between the reverse gear and a group of gears of the main transmission is held in the crankcase; A vehicle transmission, characterized in that a reverse gear side end of the main shaft is supported by a boss integrally formed with the crankcase. (2) The vehicle transmission according to claim 1, wherein an oil passage for supplying lubricating oil to the main shaft is formed in the boss portion.