JPH0649472B2 - Motorcycle - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a motorcycle in which a shock absorber for suspending wheels is arranged immediately below a crankcase of an engine.

[Technical Background of the Invention and Problems Thereof] The present applicant previously filed Japanese Patent Application No. 57-107638,
An application is made for a motorcycle having a so-called horizontally opposed engine in which cylinders extending substantially horizontally in the front-rear direction of the vehicle body are arranged on both front and rear sides of a crankcase.

Unlike the conventional parallel multi-cylinder and V-type multi-cylinder engines, the horizontally opposed engine used in this type of motorcycle has a rear cylinder that projects rearward from the crankcase, just above the front end pivot of the rear arm. Therefore, if a recent suspension system in which one hydraulic shock absorber is vertically arranged near the front end pivotal support portion of the rear arm is adopted, the wheel base becomes long. In addition, since the position of the center of gravity of the vehicle body is likely to be deviated rearward by the amount of the rear cylinder protruding, there is also a demand to bring a heavy load such as a hydraulic shock absorber forward as much as possible.

Therefore, also in a motorcycle equipped with this horizontally opposed engine, it is considered that the hydraulic shock absorber is arranged substantially horizontally just below the crankcase as shown in, for example, Japanese Patent Laid-Open No. 58-97580.

By the way, generally, an engine for a motorcycle has a gear transmission integrally incorporated in a crankcase, and engine power taken out to a crankshaft is transmitted to an input shaft of the transmission through a wet clutch. Has become.

However, since the input shaft and the output shaft of a transmission are generally installed at substantially the same height as the crankshaft, the level of engine oil stored at the bottom of the crankcase is the agitation resistance of the engine oil. Considering this, it is unavoidable to set it below the outer diameter of the crank web of the crank shaft. Particularly in a 4-cycle engine, the amount of engine oil is large, so the crankcase becomes deeper by that amount, and the oil pan projects greatly downward.

As a countermeasure against this, it is conceivable to arrange the transmission below the crankshaft and raise the oil level by that amount, as seen in the horizontally opposed engine of the above-mentioned application, but on the input shaft of the transmission When the wet clutch is provided, this clutch is immersed in the oil this time, so that the oil level has to be set below the wet clutch, and the overhang of the crankcase below becomes large.

Therefore, if the hydraulic shock absorber is installed just below the crankcase as described above, the minimum ground clearance is extremely lowered, and it may be used only for some special purposes such as racing.

[Object of the Invention]

The present invention has been made based on such a situation, and it is possible to suppress the protrusion of the crankcase to the lower side, to easily secure the installation space of the shock absorber directly under the crankcase, and also to obtain the minimum ground clearance. It is an object of the present invention to provide a motorcycle that can be secured and that can sufficiently store lubricating oil in spite of suppressing the downward protrusion of the crankcase to a small extent and improve the reliability of lubrication.

[Outline of Invention]

In order to achieve the above object, the present invention arranges an engine between front and rear wheels suspended on a vehicle body, and installs a gear transmission located below a crankshaft in a crankcase of this engine. , A wet clutch is provided on the input shaft of this gear transmission, and this wet clutch is provided with an input gear that has a larger diameter than the clutch housing and is coaxial, and that this input gear is interlocked with the crankshaft. It is premised on motorcycles.

Then, just below the crankcase, when arranging the shock absorber for suspending the wheels in a substantially horizontal direction along the front-rear direction of the vehicle body, the outer periphery of the bottom side of the wet clutch including the input gear is
By surrounding it with a partition wall with an open top,
The wet clutch is partitioned from the lubricating oil stored in the bottom of the crankcase, and the peripheral wall of the partition wall is curved in an arc shape along the rotation trajectory of the wet clutch, and at least the peripheral wall of the partition wall is formed. The bottom portion is a first portion that is close to the peripheral surface of the clutch housing,
A second portion which is close to the peripheral surface of the input gear and which extends outward of the first gear in the radial direction of the input gear, and has an oil level of the lubricating oil stored in the bottom portion of the crankcase. It is characterized in that it is set above the bottom of the wet clutch.

Example of Invention

The present invention will be described below based on an embodiment shown in the drawings.

In FIG. 1, reference numeral 1 is a cradle-shaped frame that constitutes a vehicle body, and a front fork 1b is pivotally supported by a steering head pipe 1a located at the front end of the frame 1. A front wheel 1c is supported on the lower end of the front fork 1b.

A main pipe 2 and a down tube 3 are connected to the steering head pipe 1 a, and a water-cooled engine 4 is mounted in a space surrounded by the main pipe 2 and the down tube 3. Bracket 5, welded to the connecting portion between the main pipe 2 and the down tube 3.
A front end portion of the rear arm 6 is pivotally supported between the portions 5 via a pivot shaft 7 so as to be vertically swingable. Rear arm 6
The front end of the rear arm 6 is located behind the crankcase 8 of the engine 4, and the rear wheel 9 is supported at the rear end of the rear arm 6.

The engine 4 is a 4-cycle horizontally opposed two-cylinder engine in which a front cylinder 10 and a rear cylinder 11 extending substantially horizontally along the front-rear direction of the vehicle body are arranged on both front and rear surfaces of a crankcase 8 so as to face each other. , Rear cylinder 11
Extends on the front end pivot of the rear arm 6. The crankcase 8 of the engine 4 has a two-part structure in which the left and right case halves 8a and 8b are abutted with each other, and a crank chamber 12 is formed therein. A crank shaft 13 is axially supported along the left-right direction of the vehicle body in the upper center of the crank chamber 12, and the crank shaft 13 is connected to pistons 14 and 14 in the cylinders 10 and 11 by connecting rods 15 and 15, respectively. Are connected via. Cylinder head for each cylinder 10, 11
An intake port 18 and an exhaust port 19 (only one head side is shown) are formed in 16 and 17, and the intake port 18 and the exhaust port 19 are opened and closed by an intake valve 20 and an exhaust valve 21, respectively. A carburetor 23 is provided at the intake port 18, and an exhaust port 19 is provided.
Exhaust pipes 24 are connected to each. The carburetor 23 is connected to an air cleaner 26 installed between the engine 4 and the fuel tank 25.

A constantly meshing gear transmission 27 is integrally incorporated in the crank chamber 12 on the lower rear side of the crank shaft 13. The gear transmission 27 has an input shaft 28 and an output shaft 29 that are parallel to the crankshaft 13, and a plurality of transmission gears 30 ... And 31 ... Are attached to the outer peripheral surfaces of these shafts 28, 29, respectively. There is. A wet multi-plate clutch 32 is attached to one end of the input shaft 28.
Is located below the crankshaft 13 and
The outside is covered with the crankcase cover 8c. The wet multi-plate clutch 32 holds a large number of clutch plates (not shown) between a clutch housing 33 rotatably provided on the input shaft 28 and a clutch boss 34 that rotates integrally with the input shaft 28. The power is transmitted by the frictional force generated between these clutch plates. The clutch housing 33 includes an input gear 35 that rotates integrally with the clutch housing 33. The input gear 35 is coaxial with the clutch housing 33 and has a larger diameter than the clutch housing 33, and the input gear 35 meshes with the drive gear 36 on the crankshaft 13. Therefore, the rotation of the crankshaft 13 is temporarily reduced and transmitted to the clutch housing 33.
It is adapted to be transmitted to the input shaft 28 through the clutch plate and the clutch boss 34.

Further, below the input shaft 28 and the output shaft 29, a shift drum 37 which is rotated in association with a shift operation is arranged. When the shift drum 37 is rotated, a guide groove formed on its peripheral surface is formed. The shift forks 39, 39 slide in the axial direction of the input shaft 28 and the output shaft 29 in accordance with the shape of the 38, and the meshing of the transmission gears 30, ..., 31 ... Is switched appropriately. Therefore, the rotation of the input shaft 28 depends on the speed change gears 30, ..., 31.
By selecting the meshing of ..., It is decelerated in a plurality of stages and transmitted to the output shaft 29. Wet multi-plate clutch for output shaft 29
The end opposite to 32 penetrates the side surface of the crankcase 8 and is led out to the outside, and the drive sprocket 40 attached to this lead-out end and the driven sprocket (not shown) on the rear wheel 9 side are A chain 41 for driving the rear wheels is wound between the two.

By the way, the wet multi-plate clutch 32 and the gear transmission 27
The engine oil stored in the oil pan 42 at the bottom of the crankcase 8 is pressure-fed to each part of the crankcase 8 through an oil gallery from an oil pump (not shown). A cover 43 is provided as a partition wall that surrounds the outer periphery of the input gear 35 on the bottom side. As shown in FIG. 2 to FIG. 4, the cover 43 has a rectangular opening 43a at its upper end, and approximately the upper half of the wet multi-plate clutch 32 and the input gear 35 projects from this opening 43a. Has been done.

Further, the cover 43 has a peripheral wall 43b curved in an arc shape so as to follow the rotation loci of the wet multi-plate clutch 32 and the input gear 35. The peripheral wall 43b includes a first portion 43c located near the peripheral surface of the clutch housing 33,
The second portion 43d is located closer to the peripheral surface of the input gear 35, and the second portion 43d is projected more outward in the radial direction of the input gear 35 than the first portion 43c.

Therefore, the first portion 43c of the peripheral wall 43b is formed to have a smaller diameter than the second portion 43d, and the peripheral wall 43d itself has a stepped shape.

Also, the engine oil level L in the crankcase 8
As shown in FIG. 4, is set above the lowermost parts of the wet multi-plate clutch 32 and the input gear 35 and lower than the opening 43a of the cover 43. As a result, the cover 43 prevents the wet multi-plate clutch 32 from being immersed in engine oil. Therefore, by enclosing the wet multi-plate clutch 32 with the cover 43, it is possible to increase the oil level L, and therefore the bottom surface of the crankcase 8 is pulled up by that amount, and the load clearance H with the ground GL is increased. It is getting bigger.

On the other hand, directly below the crankcase 8 is the rear arm 6
A single hydraulic shock absorber 44 for suspending is disposed substantially horizontally along the longitudinal direction of the vehicle body. This hydraulic shock absorber 44
The front end of the cylinder 45 is supported by a bracket 46 extending from the down tube 3, and the rear end of the piston rod 47 is connected to the lower surface of the front end of the rear arm 6 via a link mechanism 48. It is located on the center line along the direction. The link mechanism 48 is the rear arm 6
Is a rotatably combined link member 49 that connects the lower surface of the piston rod 47 and a link arm 49 that connects the intermediate portion of the link member 49 and the rear end portion of the down tube 3 to the rear arm 6. When the link member 49 is swung upward due to an impact force, the lower end portion is pushed forward with the intermediate portion as a pivot point while moving upward, and therefore the hydraulic shock absorber.
The piston rod 47 of 44 is actuated in the compression direction to absorb and relax the impact force applied to the rear arm 6.

Reference numeral 51 in FIG. 1 is a radiator, which is installed on the front surface of the upper portion of the down tube 3.

According to this structure, the outer periphery of the wet multi-plate clutch 32 on the bottom side is surrounded by the cover 43, and the oil level L in the crankcase 8 is set higher than that of the bottom of the wet multi-plate clutch 32. The bottom surface of the crankcase 8 can be pulled up as much as the oil level L becomes higher, and the downward protrusion of the oil pan 42 can be suppressed. Therefore, the space immediately below the crankcase 8 is expanded, so that the hydraulic shock absorber 44 can be installed without difficulty and the minimum ground clearance h can be sufficiently secured.

Moreover, the cover 43 and the peripheral wall 43b have the input gear 35
Since it is curved in an arc shape along the rotation locus of the clutch housing 33, there is no useless space between the cover 43 and the clutch housing 33 and the input gear 35 that contributes to storing engine oil. Absent. Therefore, it is possible to suppress the protrusion of the bottom of the crankcase 8 and the oil pan 42 to the lower side without reducing the amount of engine oil, and this point also contributes effectively in securing the minimum ground clearance.

Further, on the peripheral wall 43 b of the cover 43, the second portion 43 d facing the input gear 35 is provided with the clutch housing 33.
Is formed to have a larger diameter than the first portion 43c facing each other,
Since the peripheral wall 43b itself has a stepped shape that follows the external shapes of the input gear 35 and the clutch housing 33 having different diameters, it is possible to suppress the outward protrusion of the first portion 43c in the radial direction as much as possible. .

Since the bottom of the cover 43 is deepest in the portion corresponding to the second portion 43d, even if the engine oil scattered inside the cover 43 enters the second portion 43d. Starts to accumulate. Therefore, the clutch housing 3 of the wet multi-plate clutch 32
3 is not soaked in engine oil, so that excessive oil supply to the wet multi-plate clutch 32 can be prevented and the agitation resistance can be reduced.

Further, even if the engine oil collects in the cover 43, the engine oil is scraped up by the rotation of the input gear 35 and returned into the crankcase 8 through the opening 43a of the cover 43.

Therefore, the engine oil does not remain in the cover 43, which also contributes to the reduction of stirring resistance.

Moreover, according to the said structure, a hydraulic shock absorber with comparatively heavy weight.
Since the 44 moves to the front of the front end pivotal support of the rear arm 6, not only the mass concentration but also the load distribution in the front-rear direction of the vehicle body can be easily equalized, and the hydraulic shock absorber 44 is located below the engine 4. Therefore, the position of the center of gravity can be further lowered, and the running stability and maneuverability can be improved.

In carrying out the present invention, the number of cylinders of the engine is not limited to two cylinders, but may be four cylinders, for example.

〔The invention's effect〕

According to the present invention described in detail above, the oil level in the crankcase can be set higher than that of the bottom of the wet clutch, so that the position of the bottom of the crankcase can be raised accordingly, and the crankcase can be projected downward. Can be kept low. Therefore, a sufficiently large space can be secured immediately below the crankcase, and the shock absorber can be arranged comfortably here, and the minimum ground clearance can be secured sufficiently.

Moreover, since the peripheral wall of the partition wall for partitioning the wet clutch and the input gear from the oil is curved in an arc shape along the rotation locus of the input gear and the clutch housing, the partition wall and the clutch housing There is no wasted space between the input gear and it that does not contribute to storing engine oil. At the same time, the peripheral wall of the partition wall has a stepped shape so as to follow the outer shapes of the input gear and the clutch housing having different diameters, so that the overhang of the first portion of the peripheral wall can be suppressed as much as possible. It is possible to prevent the crankcase from protruding downward without reducing the amount of oil stored in the crankcase.

Also, since the bottom of the partition wall is deepest at the portion corresponding to the second portion, even if engine oil scattered inside the partition wall enters, the engine oil collects from the second portion. start. For this reason, the wet clutch is less likely to be immersed in the engine oil, excessive oil supply to the wet clutch can be prevented, and stirring resistance is reduced.

Furthermore, the engine oil that collects inside the partition wall is scraped up by the rotation of the input gear and returned to the inside of the crankcase through the opening of the partition wall, so that the engine oil remains inside the partition wall. This is also advantageous in terms of reduction of agitation resistance and prevention of excessive oil supply to the clutch.

[Brief description of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a side view of a motorcycle, Fig. 2 is a side view in which an engine is partially sectioned, and
2 is a sectional view taken along the line III-III in FIG. 2, FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2, and FIG. 1 ... Body (frame), 1c ... Front wheel, 4 ... Engine, 9 ... Rear wheel, 13 ... Crankshaft, 27 ... Gear transmission, 28 ... Input shaft, 32 ... Wet clutch (wet type) Multi-plate clutch), 33 ... Clutch housing, 35 ... Input gear, 43 ... Partition wall (cover), 43a ... Opening part,
43b ... peripheral wall, 43c ... first part, 43d ... second part, 44 ... shock absorber, L ... oil level.

Claims (1)

[Claims] 1. An engine is arranged between front and rear wheels suspended from a vehicle body, and a gear transmission is installed below a crankshaft in a crankcase of the engine. A wet clutch is provided on the input shaft of, and this wet clutch has an input gear that has a larger diameter than the clutch housing and is coaxial, and in a motorcycle in which this input gear is interlocked with the crankshaft, Immediately below the crankcase, when arranging the shock absorber for suspending the wheels in a substantially horizontal direction along the front-rear direction of the vehicle body, the outer periphery of the bottom side of the wet clutch including the input gear is
By surrounding it with a partition wall with an open top,
This wet clutch is partitioned from the lubricating oil stored at the bottom of the crankcase, and the peripheral wall of this partition wall is curved in an arc shape so as to follow the rotation trajectory of the wet clutch, and at least the peripheral wall of this partition wall is The bottom portion is close to the peripheral surface of the clutch housing, and the second portion is close to the peripheral surface of the input gear and projects outward from the first gear in the radial direction of the input gear. A motorcycle having: and the oil level of the lubricating oil stored in the bottom of the crankcase is set above the bottom of the wet clutch.