JPH02215933A - Crankshaft supporting structure for engine - Google Patents

Abstract

PURPOSE:To improve assembleability of subject crankshaft and make it compact in the crankshaft axial direction by inserting a crankshaft from the side of a holding hole, and in the state that the inserted end is supported on a crankcase side wall, fitting a holding member in the side of the other side wall. CONSTITUTION:A crankshaft 27 is inserted from the side of a holding hole 33 and a right main shaft part is supported on a crankcase right side wall via a metal bearing 31. Since a ball bearing 41 is pressed in a left main shaft part, it supports both ends of the crankshaft 27. Simultaneously with installing a camshaft driving gear 35 in the crankshaft 27, a left side of the camshaft driving gear 35 is covered with the outer part of a holding member. Thus, assembleability in a supporting structure is improved and it can be made compact in the crankshaft direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a crankshaft support structure for an engine used to drive, for example, a motorcycle.

[Conventional technology]

Conventionally, the crankcase of an engine is generally divided into left and right or upper and lower parts, and the pair of divided case halves are tightened together using a tightening port.

By the way, for engines installed in motorcycles, scooters, etc., it is desired to simplify the assembly work by integrating the engine. There is an internal combustion engine disclosed. This is an integral part of the engine crankcase, with a holding hole large enough to allow the crankshaft to be inserted into one side wall of the crankcase, and a holding member that holds the crankshaft in this holding hole. It is configured to fit.

[Problem to be solved by the invention]

However, in such a structure, when trying to install a camshaft drive gear that drives the camshaft, a holding member that supports the crankshaft is installed, and a cam drive chamber is formed after the camshaft drive gear is installed. Since the cam drive chamber cover member must be attached, the number of members to be assembled increases, and the ease of assembly is not necessarily good. In addition, there are many members stacked in the direction of the crankshaft, and it is necessary to provide sufficient gaps between each member to account for manufacturing errors in each member, resulting in the problem that the length of the parts increases in the direction of the crankshaft. The invention was made in view of these circumstances,
The present invention provides an engine crankshaft support structure that improves assemblability and can be made compact in the crankshaft direction.

[Means to solve the problem]

In the engine crankshaft support structure according to the present invention, a shaft hole for supporting one end of the crankshaft is provided in one side wall of an integrally formed crankcase, and the other side wall is sized to allow the crank arm of the crankshaft to be inserted therethrough. A holding hole is provided, and a holding member having a housing portion for storing a camshaft drive gear mounted on the crankshaft is fitted into the holding hole through which the crankshaft is inserted, and the crankshaft of this holding member is fitted. A bearing that supports the crankshaft is fitted on the arm side.

[Effect]

In the present invention, when the crankshaft is inserted from the holding hole side and the insertion end is supported by the crankcase side wall, and the holding member is fitted to the other side wall, both ends of the crankshaft are supported, and the holding member This will cover the sides of the camshaft drive gear.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view taken along the line 1-1 in FIG.
The figure is a side view showing a scooter with an engine installed.
The figure is a sectional view taken along line mm in FIG. 2. In FIG. 2, the reference numeral 1 indicates a scooter, which has a low footrest 4 between a handle 2 and a seat 3.
A vehicle body cover 5 that covers the lower part of the seat 3 is provided at the rear. 6 is a body frame extending in the longitudinal direction of the scooter 1, which includes a front frame 6a made of one tube;
2 branched left and right from the rear end of this front frame 6a.
It is composed of a rear frame 6b made of a book tube.

7 is a unit swing type engine. This unit swing type engine 7 is disposed in the vehicle body cover 5 below the seat 3, and includes a forced air-cooled four-stroke engine 8 and a power transmission mechanism including a V-belt 10 that transmits the power of the engine 8 to the rear. , and a transmission case 11 that accommodates this power transmission mechanism and supports the rear wheel 9. 1
2 is a unit swing type engine 7 attached to the rear frame 6b
This is a bracket for swingingly supporting the

Reference numeral 13 denotes a shock absorber that absorbs the vertical movement of the rear part of the transmission case 11, and the rear end of the transmission case 11 and the rear frame 6b.
It is interposed between.

The engine 8 includes a rearwardly inclined cylinder body 14, a cylinder head 15, and a crankcase 16.
The engine case 17 is integrally formed with the inner part of the transmission case 11. One cylinder hole 14a is provided inside the cylinder body 14, and the piston 21 is fixed to the cylinder body 14 by an oval-shaped fixing plate 23 that holds and presses the piston 21 therein. A combustion chamber 24 is formed at the upper end of the cylinder hole 14a, and a cam drive chamber 25 for driving a camshaft, which will be described later, is integrally formed on the left side. The combustion chamber 24 is formed into a substantially hemispherical shape in order to uniformly cool the head side and reduce thermal distortion. The crank arm 16 is formed in a box shape with an opening opened downward, and supports a crankshaft 27 connected to the piston 21 via a connecting rod 26 by both side walls so as to be rotatable in the vehicle width direction. An oil pan 28 that closes the opening is attached to the lower end with a screw.

A spark plug 29 is screwed onto the right side of the cylinder head 15 so as to face the center of the combustion chamber 24. Further, a large number of cooling fins 30 are provided on the outer peripheral surface of the cylinder body 14.
...is protruding horizontally.

A ring sleeve 22 is provided on the rear side of the cylinder head 15 and extends from below to the side through the intake valve. Furthermore, an exhaust port is provided on the front side of the cylinder head 15 and is connected to the combustion chamber 24 via an exhaust valve and extends forward.

To explain the support of the crankshaft 27 in detail, a shaft hole 32 is provided in the right side wall of the crankcase 16 to support the right end portion of the crankshaft 27 via a metal bearing 31. On the other hand, the crankshaft 2 is attached to the left side wall of the crankcase 16.
A holding hole 33 is opened and has a size that allows the crank arm 27a of No. 7 to be inserted therethrough. That is, the crankshaft 27 is inserted and assembled from the left side of the crankcase 16. 34 is a holding member fitted into the holding hole 33. This holding member 34 is formed in a shape in which a disc that fits into the holding hole 33 and a disc provided outside the holding hole 33 are connected by a peripheral wall extending along the periphery, and the crankshaft 27 is inserted through the disc. In addition, a housing portion 34a is provided for housing a metal camshaft driving gear 35 mounted on the crankshaft 27 by the peripheral wall.

This storage portion 34a is positioned below the camshaft gear 37 provided at the left end of the camshaft 36, and forms the lower end portion of the cam drive chamber 25. Reference numeral 41 designates a pole bearing that is fitted into a recess provided on the inner circumferential edge of the holding member 34 on the crank arm side and supports the crankshaft 27 . Between the camshaft driving gear 35 and the camshaft gear 37, there is a synthetic resin 2
The two intermediate gears 42 and 42 are connected to each other via intermediate gears 42 and 42. Therefore, the metal gears do not mesh with each other, and the meshing noise is suppressed to a low level.

43 is a lubricating device inserted into the crankcase I6 from below, and supplies oil to the crankshaft 27 and the camshaft 36 via a pipe 44 cast into the engine case 17, as shown by the arrow in FIG. do. 39 is a plug that closes the oil passage of the lubricating device 43 so that oil flows to the pipe 44, and 40 is a plug that closes the oil passage provided in the crankshaft 27. 45 is the crankshaft 27
46 is a cooling fan fixed to the outer surface of the generator, and 47 is a V-belt type automatic speed change power transmission device mounted on the left end of the crankshaft. 48
A shroud covers the outside of the cooling fan 46 and the circumference of the cylinder body 14 to form a cooling air passage, and 49 is a cylinder head cover.

The intake boat is connected to a carburetor 51 disposed on the right rear side of the cylinder head 15 via an intake manifold 52, and the carburetor 51 is connected to an air cleaner 54 via a joint 53.

On the other hand, the exhaust port is connected to a muffler 56 via an exhaust pipe 55. Reference numeral 57 denotes a muffler mounting bracket that is attached to the engine 8 and supports the muffler 56.

In the engine crankshaft support structure configured in this manner, the crankshaft 27 is inserted from the holding hole 33 side, the right main shaft portion is supported on the right side wall of the crankcase via the metal bearing 31, and in this state the crankcase is When fitted into the holding hole 33 on the left side wall, the pole bearing 4 is attached to the left main shaft.
1 is press-fitted, both ends of the crankshaft 27 can be supported.

At this time, if the holding member 34 is fitted with the camshaft driving gear 35 stored in the storage portion 34a, the camshaft driving gear 35 is mounted on the crankshaft 27 and at the same time, the outside of the holding member 34 is fitted. The portion can cover the left side of the camshaft driving gear 35.

That is, the holding member 34 can constitute a lid that covers the cam drive chamber 25. Then, such a storage section 34
By providing the support member 34, the thickness of the holding member 34 in the crankshaft direction can be increased to increase the rigidity, so that the crankshaft 27 can be supported reliably.

〔Effect of the invention〕

As explained above, according to the present invention, one side wall of the integrally formed crankcase is provided with a shaft hole that supports one end of the crankshaft, and the other side wall is provided with a shaft hole large enough to allow the crank arm of the crankshaft to be inserted therethrough. The crankshaft is inserted into the holding hole, and a holding member having a storage portion for storing a camshaft drive gear mounted on the crankshaft is fitted into the holding hole, and the crack arm of this holding member is fitted. Since the bearing that supports the crankshaft is fitted to the side, insert the crankshaft from the holding hole side, and with the insertion end supported by the crankcase side wall, fit the holding member to the other side wall to tighten the crankshaft. Both ends of the shaft can be supported, and the sides of the camshaft driving gear can be covered with the holding member.

Therefore, since it is possible to support the crankshaft and cover the sides of the camshaft drive gear with one member, installation is easier compared to a structure in which separately formed lid members are stacked in the direction of the crankshaft. Not only can this be improved, but it can also be made more compact in the direction of the crankshaft. Furthermore, the holding member can be made thicker in the direction of the crankshaft by the storage portion, and its rigidity can be increased, so that the support of the crankshaft can be ensured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line I-1 in FIG. 2 showing a scooter on which the engine crankshaft support structure according to the present invention is implemented, FIG. 2 is a side view showing the scooter on which the engine is mounted, and FIG. is a sectional view taken along line II [-1 in FIG. 2. 16...Crank case, 27...Crankshaft, 31...Metal bearing, 32...Shaft hole, 33...
. . . Holding hole, 34 . . . Holding member, 34a, mountain storage portion, 35 . . . Camshaft driving gear, 41 . . . Ball bearing. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] A shaft hole for supporting one end of the crankshaft via a bearing is provided in one side wall of the integrally formed crankcase, and a holding hole having a size that allows the crank arm of the crankshaft to be inserted is provided in the other side wall. The crankshaft is inserted into this holding hole, and a holding member having a storage portion for storing a camshaft driving gear mounted on the crankshaft is fitted, and the crankshaft is supported on the crank arm side of this holding member. An engine crankshaft support structure consisting of fitted bearings.