JPH02112628A - Engine - Google Patents

Abstract

PURPOSE:To contrive the miniaturization or the like of an engine by respectively providing a crankshaft and a speed change subshaft to be arranged between upper and lower divided surfaces of a crankcase further a speed change main shaft to be arranged in one of the upper and lower cases while forming a rotatably supporting point of a rear part arm in the divided surface or the like. CONSTITUTION:An engine unit 9 provides a cylinder block 11, cylinder head 12 and a head cover 13 to be successively arranged in the upper surface front part of a chankcase 10. Here the crankcase 10 is divided into two upper and lower parts 23, 24, and this divided surface A provides a crankshaft 18 and a speed change subshaft 35 to be respectively arranged. While a speed change main shaft 32 is arranged between both the shafts 18, 35 further in the upper from the divided surface A. While a pivot part 24a of a rear part arm, supporting a rear wheel, is integrally formed with the lower part case 24. The pivot part 24a is supported to a bracket part of a car body frame with the front end part of the rear part arm. In this way, length of the crankcase and a wheel base are respectively shortened.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an engine suitable for a motorcycle, and in particular, the front and rear crankcase lengths are shortened to make the entire engine smaller, and the distance between the front and rear wheel axles is reduced. The present invention relates to an arrangement structure of a crankshaft, a five-speed variable speed main shaft (main shaft), a variable speed sub-shaft (drive shaft), etc., which can shorten the wheelbase (hereinafter referred to as a wheel base).

[Conventional technology]

For example, motorcycle engines generally employ a structure in which a crankshaft and a transmission having a transmission main shaft and a subshaft are integrated into a crankcase. In this case, in order to improve the workability of assembling the crankshaft and transmission, the crankcase is often divided into upper and lower parts, and the crankshaft, transmission main shaft, and subshaft are arranged side by side between the divided surfaces. (For example, see Japanese Patent Application Laid-Open No. 59-79020)
.

[Problem that the invention seeks to solve]

As described above, when the crankshaft and each transmission shaft are arranged side by side between the dividing surfaces, there is a problem that the front-rear length of the crankcase becomes long and the overall size of the engine increases. Further, the rear arm that pivotally supports the rear wheel is pivotally supported near the engine suspension position of the vehicle body frame, but as mentioned above, as the longitudinal length of the engine becomes longer, there is also the problem that the wheel base becomes longer.

The present invention has been made in view of the above-mentioned conventional situation, and an object of the present invention is to provide an engine that can be made smaller by shortening the longitudinal length of the engine, and can also shorten the wheel base.

[Means for solving problems]

The present invention divides the crankcase into two parts, an upper case and a lower case.
A crankshaft and a speed change sub-shaft are arranged in parallel between the divided surfaces of both cases, and a speed change main shaft is arranged in the upper case or lower case, and the shaft fulcrum (pivot part) of the rear arm is placed in the upper case or lower case.
The engine is characterized in that it is provided either in the lower case or between the divided surfaces.

[Effect]

In the engine according to the present invention, since the speed change main shaft is disposed in the upper case or the lower case, the speed change countershaft can be moved closer to the crankshaft, thereby shortening the longitudinal length of the crank case and thus the engine.

Therefore, the engine can be made smaller and the wheelbase can be shortened. In addition, since the rear arm pivot point is formed in the crankcase itself, the rear arm is pivoted at the pivot point, and the engine is also suspended, thereby creating a gap between the engine body support and the rear arm pivot point. There is no longer a gap in the front-rear direction, so the wheelbase can be shortened from this point as well.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

1 to 4 are diagrams for explaining one embodiment of the present invention.

In the figure, reference numeral 1 denotes a motorcycle equipped with the engine of this embodiment.A front fork 4, which pivotally supports a front wheel 3 at its lower end, is supported at the front end of a body frame 2 of this motorcycle so as to be steerable left and right. At the lower end, a rear arm 6, which pivotally supports the rear wheel 5 at the rear end, is pivotably supported up and down, and a large fuel tank 7 and a seat 8 are mounted on the upper part in order from the front. Also, on the lower front side of this body frame 2, there is an engine unit.
7 and 9 are suspended and supported.

The engine unit 9 is an air-cooled four-stroke parallel two-cylinder type engine unit, and a cylinder block 11. Cylinder head 12 and head cover 13
The structure is such that they are mounted on a vehicle and are tilted forward at approximately 45 degrees with respect to the horizontal plane.

Left and right cylinders 11a of the cylinder block 11.

A combustion chamber 14 is formed in the upper part of the combustion chamber 11b by the pistons 14a, 14b and the recesses 12a, 12b of the cylinder head 12, and an intake valve 15a is connected to the intake and exhaust ports communicating with the combustion chamber 14. Book.

Two exhaust valves 15b are arranged. Each intake valve 15a
, intake camshaft 16a for exhaust valve 15b, exhaust camshaft 16
A driven sprocket 16e is fixed to the right end portion of b when viewed from the rear of the vehicle (the same applies hereinafter).

Each piston 14a, 14b has a connecting rod 17a,
! 7b, crank arm parts 18a and 18b are formed by connecting a pair of webs of the crankshaft 18 with a crank bin.
connected to parts. A drive sprocket 18c is integrally formed on the right side protrusion of the crankshaft 18, and a force chain 20 is wound between the sprocket 180 and the driven sprockets 16e of the camshafts 16a and 16b.

This force chain 20 is attached to the cylinder rad 12. It is arranged to pass through chain case parts 11e, 12c, and 23a that are bulged on the right side walls of the cylinder block 11 and the upper case 23. Further, a tensioner 60 is disposed behind the force chain 20, and the tensioner 60
The lower end of the chain pressing member 60a is rotatably supported by a pin 61a. On the outside of this pin 61a, a pole 10a that connects the upper split type crankcase 10 is located so as to be substantially orthogonal to the axis of the pin 61a, which will be described later. No removal is allowed.

A pump drive gear 25 is attached to the right end of the crankshaft 18, and below this gear, lubricating oil is supplied from an oil tank (not shown) having an oil cooler function to the bearings 192 to 19C, etc. A feed pump 26 for supplying lubricating oil to a lubricating section and a scavenge pump 27 for feeding lubricating oil in an oil pan 28 into an oil tank are arranged in parallel at the front and rear of the vehicle. In addition, the above crank case 10
A water pump 53 for circulating cooling water is disposed in a recessed portion of the right side wall in front of the chain case portion 23a.
In addition, 29 is an oil strainer, 31 is an oil cleaner, and 30 is a cap, which makes the cleaner chamber 28a
is lower case 24. Oil pan 28 and cap 30-3
It has a layered structure.

The above-mentioned crankcase 10 has a top and bottom split structure with upper and lower cases 23 and 24 separated by 2 minutes, and this split surface A
is slanted so that the front side is lower when mounted on a vehicle. The crankshaft 18 is located closer to the front side between the divided surfaces, and is located between the left and right crank arm portions lsa and 18b.
The right outer portion is supported by a solid bearing 19c and two left and right bearings 19a and 19b formed between the divided surfaces, respectively.

A front balancer shaft 47 is located in front of the crankshaft 18 of the lower case 24 and below the dividing surface A, and a rear balancer shaft is located behind the crankshaft 18 of the upper case 23 and above the dividing surface A. 48 is the crankshaft 18
The line connecting the axes of both balancer shafts 47 and 48 is located in front of the axis of the crankshaft 18.

The front and rear balancer shafts 47, 48 have a structure in which a support shaft 50 is inserted into the balancer body 49, and a needle bearing 51 is disposed between them. The rear support shaft 50 is inserted through the insertion hole 23b formed in the side wall of the upper case 23, and its tip is supported in the support hole 23C formed in the right side wall of the upper case 23, and its rear end is a key. It is fixed to the left side wall by a plate 47b. Note that the same applies to the front support shaft. The balancer main body 49 is formed by integrally forming a weight portion 49b at both ends of a cylindrical body 49a and a positioning portion 49c at the center.
9b indicates each crank arm portion 18a, 1 of the crankshaft 18.
It is located between the webs of 8b.

The positioning portions 49c are arranged below and above the balancer shaft 4748, and are inserted into guide grooves of a positioning plate 52 fixed to the crankcase. axially positioned. Further, a driven gear 47a is fixed to the left end portion of the balancer main body 49.

48a meshes with a balancer gear 21 fixed to the crankshaft 18, thereby rotating in the opposite direction to the crankshaft 18.

Note that 58 is a breather cover forming a breather chamber, and this is formed at the rear of the upper surface of the upper case 23.
It also serves as a lid member for opening and closing an opening for assembling the rear balancer shaft 48 and the like.

A transmission main shaft (main shaft) 32 is disposed in a portion of the upper case 23 on the rear side of the crankshaft 18 and above the dividing surface A, and the transmission main shaft 32 is disposed between the dividing surfaces.
A speed change subshaft (drive shaft) 35 is disposed at a slightly more rearward portion. Both left and right ends of the speed change main shaft 32 are bearings 32b, 32C, and both ends of the speed change subshaft 35 are bearings 35b,
35C, each is pivotally supported. The right bearing 32c of the speed change main shaft 32 is a speed change gear 32a mounted on the main shaft 32.
It is attached to the right side wall of the upper case 23 via a larger diameter housing 32d. Further, an opening for removing the main shaft 32 is formed in the left bearing 32b, and a camp 32e is fitted into the opening. This cap 32e and the oil seal 35d on the outside of the left bearing 35b of the subshaft 35 are pressed by a presser plate 35e made of sheet metal fixed to the left side wall of the crankcase IO.

In addition, a wet multi-plate clutch 33 is located at the right end of the speed change main shaft 32.
A large reduction gear 33b fixed to the outer 33a of the clutch 33 meshes with a small reduction gear 22 fixed to the crankshaft 18. This clutch 3
The operating shaft 33d for moving the pressing member 33c of No. 3 is inclined forward from the vertical when viewed from the right side of the vehicle, and the clutch cable 336 passes through the rear side of the cylinder block 11 and extends downward through a concave portion. The cable is routed to the left side of the vehicle body to prevent any friction from occurring, and extends to the left grip of the steering wheel. Further, the speed change gears 32a and 35a of each stage mounted on the speed change main shaft 32° and the counter shaft 35 mesh with each other, thereby forming a constant mesh type transmission.

The left end of the speed change subshaft 35 projects outward from the left side wall of the crankcase IO, and a rear wheel drive sprocket 36 is attached to the projecting portion, and the sprocket 36 and the rear wheel 5
A power transmission chino 37 is wound between the driven sprockets 53. A chino cover 38 is disposed on the outside of the sprocket 36 so as to cover it, and the chino cover 38 is for shielding mud etc. splashed by the sprocket 36 and the sprocket 36. Also, a change pedal 3 disposed below the drive sprocket 36
9 and the shift shaft 40 disposed on the upper side are connected by a connecting rod 41b that has a universal joint 41a at both ends and extends in the vertical direction outside the drive sprocket 36, and the connecting port 7 door 41b is It is covered with a case cover 42.

Further, a pivot portion (axis fulcrum) 24a is integrally formed at the rear end portion of the lower case 24 of the crankcase 10. The left side of this pivot portion 24a.

The front end of the rear arm 6 is located on the right outside, and the support bracket 2a of the vehicle body frame 2 is located outside of this, and the pivot shaft 24h is arranged to pass through these. There is.

This allows the engine unit 9 to be suspended and the rear arm 6 to be suspended.
The central support is established.

The reference numeral 43 is a starter motor, and a drive gear 43b attached to an output shaft 43a of the starter motor meshes with a starting gear 46 attached to the crankshaft 18 via a one-way clutch via an idle gear 45.

Next, the effects of this embodiment will be explained.

In this embodiment, the crankcase 10 is divided into two parts, an upper part and a lower part, and a crankshaft 18. Since the speed change subshaft 35 is arranged and the speed change main shaft 32 is arranged in the portion between the two shafts 18 and 35 of the upper case 23 and above the dividing plane, the speed change subshaft 35 can be placed closer to the front side. The length of the crankcase can be shortened accordingly, making it possible to downsize the entire engine and shorten the wheelbase.

Further, since the pivot portion 24a that pivotally supports the rear arm 6 is integrally formed with the lower case 24, and the pivot portion 24a is supported together with the front end portion of the rear arm 6 by the support bracket portion 2a of the vehicle body frame 2, the engine suspension portion There is no gap between the rear arm and the rear arm pivot, and the wheel base can also be shortened from this point of view.

In addition, in the above embodiment, the transmission main shaft 32 is arranged on the upper case 23 side, but it may be arranged on the lower case 24 side.
In addition, although the pivot portion 24a is formed in the lower case 24,
This may be formed in the upper case 23 or between the split surfaces of both cases. Even if the transmission main shaft 32 is arranged in such a position and the pivot part 24a is formed, the same effect as in the above embodiment can be obtained. It will be done.

〔Effect of the invention〕

As described above, according to the engine according to the present invention, the crankshaft and the speed change subshaft are arranged between the upper and lower divided surfaces of the crankcase, the speed change main shaft is arranged in the upper case or the lower case, and either the upper or lower case or the divided Since the rear arm shaft fulcrum is integrally formed between the surfaces, it is possible to shorten the length of the crankcase and downsize the engine, as well as shorten the wheelbase.

[Brief explanation of the drawing]

1 to 4 are diagrams for explaining an engine according to an embodiment of the present invention, in which FIG. 1 is a partially sectional right side view thereof, FIG. 2 is a partially sectional left side view thereof, and FIG. FIG. 3 is a developed cross-sectional plan view thereof, and FIG. 4 is a side view of a motorcycle equipped with the engine. In the figure, 10 is a crankcase, 18 is a crankshaft, 23 and 24 are upper and lower cases, 24a is a pivot portion (the pivot point of the rear arm), 32 is a transmission main shaft, 35 is a transmission subshaft,
A is the dividing plane. Patent Applicant Yamaha Motor Co., Ltd. Agent Patent Attorney Tsutomu Shimo

Claims (1)

[Claims] (1) The crankcase is divided into two parts, an upper case and a lower case, and the crankshaft and the gear shift subshaft are arranged in parallel between the divided surfaces of both cases, and the gear shift main shaft is arranged in the upper case or the lower case, and the rear An engine characterized in that the fulcrum of the arm is formed in either the upper or lower case or between the divided surfaces.