JP2646484B2 - Square 4 engine of motorcycle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a square 4 engine of a motorcycle in which an exhaust passage is extended to both sides of an engine unit.

(Prior Art) Generally, a cam chain for driving a camshaft of an overhead cam type four-cycle engine is provided in a cam chain chamber formed at the center or both sides of a cylinder block and a cylinder head.

For this reason, the lateral widths of the cylinder block, the cylinder head, and the crankcase are increased by the amount of the cam chain chamber, resulting in an increase in weight. In addition, since the cam chain and the sprocket gear are inside, there has been a problem that the number of steps is increased due to the disassembly of the engine unit during maintenance or the like.

In the case where four cylinders are arranged in one engine unit like a square four engine, the cylinder block, cylinder head, and crankcase are large,
The above tendency became remarkable.

(Problems to be Solved by the Invention) As described above, in the case where the cam chain is housed in the chain chamber formed in the engine unit, there is a problem that the engine unit is increased in size, weight or maintenance work is increased. .

The present invention has been made in view of the above-described circumstances, and provides a square 4 engine of a motorcycle in which an engine unit can be reduced in size and weight and maintenance of a cam chain and sprocket gears is facilitated. The purpose is to:

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object, a square 4 engine of a motorcycle according to the present invention is configured such that exhaust passages from front and rear cylinders are arranged side by side on both sides in the engine width direction of a cylinder head. In a square 4 engine in which a camshaft extending in the engine width direction is arranged side by side in the engine front-rear direction on the cylinder head, one end of a crankshaft is projected to one outer surface of the engine unit to fix a cam drive sprocket gear, On the same outer surface, between the front and rear exhaust passages, one end of a cam drive shaft supported by the cylinder head in the engine width direction is protruded from the cylinder head to fix a cam driven sprocket gear. While the cam drive shaft is suspended in the cylinder head at the other end of the cam drive shaft. Eve gears are fixed, the cam drive gear is meshed with a driven gear fixed to the center of the camshaft in the engine width direction to drive the camshaft of each cylinder,
A chain chamber cover for sealing the cam chain line is detachably attached to the side of the engine unit between the front and rear exhaust passages.

(Operation) In the square 4 engine of the motorcycle, the chain chamber is disposed outside the engine unit, and the side of the cylinder block, the cylinder head, and the crankcase can be shortened, so that the size and weight can be reduced.

Since the cam chain chamber itself only accommodates the chain line suspended between the two sprocket gears, it is compact, can be easily opened by removing the displacement, and the man-hours such as maintenance are greatly reduced.

(Embodiment) FIG. 1 is a side view of a motorcycle equipped with a square 4 engine according to an embodiment of the present invention. 2, 3 and 4 are detailed views of a square 4 engine of a motorcycle.

FIG. 5 shows a DOHC type 4-cycle engine configured for each cylinder of a square 4 engine. A piston 2 sliding in a cylinder 1 is connected to a crankshaft 4 via a connecting rod 3.
It moves up and down by the rotation of. A combustion chamber 5 formed at the upper end of the cylinder 1 has two intake ports 6a and 6b and two exhaust ports 7a and 7b on both sides of the combustion chamber 5 which is vertically divided by a center line XX orthogonal to the crankshaft 4. Are arranged in tandem, and intake valves 8a and 8b and exhaust valves 9a and 9b are interposed in each of them.

Above the combustion chamber 5, two overhead camshafts 10a and 10b parallel to the crankshaft 4 are suspended. On one overhead camshaft 10a, an intake cam 11a and an exhaust cam 12a are formed. , And controls the exhaust valve 9a. Similarly, an intake cam 11b and an exhaust cam 12b for controlling the intake valve 8b and the exhaust valve 9b are formed on the other overhead cam shaft 10b.

The intake passage 13 connected to the intake ports 6a, 6b is introduced into the intake passages 13a, 13b in a straight line substantially parallel to the cylinder axis between the overhead camshafts 10a, 10b. On the other hand, the exhaust passages 14a and 14b connected to the exhaust ports 7a and 7b rise upward and are led out of the cylinder head almost parallel to the crankshaft 4 to join the exhaust passage 14.

The spark plug 15 is connected to the intake passages 13a, 13b and the exhaust passage 14.
It is inserted into the cylinder head toward the center of the combustion chamber 5 in the space surrounded by a and 14b. In this case, the spark plug 15 for avoiding interference with the intake passage 13 is inclined toward the exhaust passage 14. Since the overhead camshafts 10a and 10b do not exist on the extension of the axial center of the spark plug 15, a space for insertion can be easily secured by this inclination.

This four-cycle engine can skillfully avoid interference between the intake passage 13 and the spark plug 15, and interference between the space for inserting the spark plug 15 and the overhead camshafts 10a and 10b. The intake passage 13 can be formed in an ideal top field with a four-valve system, and the included angle of the valve can be reduced without obstruction. Overall fuel filling efficiency is increased, high combustion efficiency is obtained, and engine output is improved. Will do.

Next, in the engine unit 16, as shown in FIG. 3, the four-stroke engine shown in the basic form is arranged in a four-cylinder front-rear and left-right rectangular shape, and the crankshafts 4a and 4b are moved back and forth as shown in FIG. Books are arranged in parallel, and the cylinders 1a and 1b in the front row share the front crankshaft 4a, and the cylinders 1c and 1d in the rear row share the rear crankshaft 4b. As shown in FIG. 3, the intake valves 8a, 8 of the left and right cylinders 1a and 1b and 1c and 1d.
b, exhaust valves 9a, 9b, intake cams 11a, 11
b, exhaust cams 12a, 12b, intake passage 13, exhaust passage 14
Are arranged symmetrically.

The exhaust passage 14 opens on both sides of the cylinder head 17 in the engine width direction, and is connected to an exhaust pipe 18. As shown in FIG. 1, the exhaust pipe 18 extends to the side of the cylinder head 17 in the width direction of the engine, then descends forward and downward along the side surface of the engine unit 16, and then is guided U-turn.

The intake passage 13 has a cylinder head 17 and a head cover 19
And is opened on the upper surface of the head cover 19. Intake passage
A carburetor 20 connected to 13 is mounted on the upper surface of the head cover 19. A box type frame 21 is connected to the upper surface of the head cover 19 as shown in FIGS. The inside of the box type frame 21 functions as an air cleaner case together with the cap 22. Reference numeral 23 indicates an air cleaner element, and reference numeral 24 indicates an inlet.

A steering head 25 is detachably fixed to the front end of the box-type frame 21, and a fuel tank 26 is connected to the rear of the cap 22.

The steering head 25 supports the front wheels 27 so that they can be steered,
The rear wheel 28 is pivotally supported at the rear end of a swing arm 29 pivotally supported by the rear edge of the engine unit 16 and a rear cushion unit.
Buffered suspension by 30. Reference numeral 31 denotes a seat rail fixed to the engine unit 16, on which a seat 32 is mounted.

The two overhead camshafts of the four cylinders 1 are camshafts 33a, 33b, 33c, and 33d, which are continuously integrated left and right with the driven gears 32a, 32b, 32c, and 32d interposed therebetween. Be prepared.

The rear end of the crankshaft 4b protrudes from the side surface of the engine unit 16 as shown in FIG. 4, and the cam drive sprocket gear 34 is supported and fixed. A cam drive gear shaft 35 is rotatably mounted on the cylinder head 17, and a driven sprocket gear 36 is pivotally supported at an outer end protruding to the side thereof, and a cam chain 37 is provided between the cylinder head 17 and the cam drive sprocket gear 34. Is suspended, and rotation is transmitted from the crankshaft 4b.

A cam drive gear 38 is fixed to the inner end side of the cam drive gear shaft 35 at the center in the engine width direction, and simultaneously meshes with the driven gears 32b, 32c of the camshafts 33b, 33c at the intermediate portion. The driven gears 32b, 32c are linked with the driven gears 32a, 32d via idle gears 39a, 39b shown in FIG. 3, respectively. In this way, the respective camshafts 33a, 33b, 33c, 33d are simultaneously driven stably with the right and left balance.

In FIGS. 3 and 4, reference numeral 40 denotes a spark plug insertion hole formed in the cylinder head 17;
Denotes an idle sprocket gear for guiding the cam chain 37, reference numeral 42 denotes a tensioner, reference numeral 43 denotes a chain chamber housing, and reference numeral 44 denotes a chain chamber cover.

The cam drive sprocket gear 34, cam driven sprocket gear 36, cam chain 37, idle sprocket gear 41, and tensioner 42
It is sealed by the chain chamber housing 43 and the chain chamber cover 44 mounted on the side. The profile of the chain chamber cover 44 is vertical and fits between the exhaust pipes 18.

Thus, the cam chain 37, sprocket gears 34, 36,
41 and the tensioner 42 can be easily provided for maintenance by removing the exhaust pipe 18 and opening the chain chamber cover 44. The engine unit 16 has a small width and can be reduced in size and weight.

〔The invention's effect〕

As described above, the square 4 of the motorcycle according to the present invention.
The engine has a square 4 in which an exhaust passage is led out of each of the cylinders in the front and rear rows on both sides in the engine width direction of the cylinder head in a front-rear direction, and a camshaft extending in the engine width direction is provided on the cylinder head in the engine front-rear direction.
In the engine, a cam drive sprocket gear is fixed by projecting one end of the crankshaft to one outer surface of the engine unit, and a cam supported by the cylinder head in the engine width direction between the front and rear exhaust passages on the same outer surface. A cam driven sprocket gear is fixed by projecting one end of the drive shaft from the cylinder head, and a cam chain is suspended between the two sprocket gears, while a cam drive gear is fixed in the cylinder head at the other end of the cam drive shaft. ,
The cam drive gear is meshed with a driven gear fixed to the center of the camshaft in the engine width direction to drive the camshaft of each cylinder. Since the cam chain chamber was formed outside the engine unit because it was detachably attached between the engine units, the engine unit could be made smaller and lighter.
In addition, maintenance of the cam chain and sprocket gears can be performed without disassembling the engine unit, which facilitates the maintenance.

In addition, the chain chamber cover forming the cam chain chamber only covers the two sprockets on which the cam chain is suspended, and is provided between the front and rear exhaust passages, so that it can be made compact and easy to install. The driving force transmitted to the cam driven sprocket gear is transmitted to the driven gear of each cam shaft fixed at the center in the engine width direction via a common cam drive shaft and a cam drive gear, and the cam shaft is moved right and left at the center in the engine width direction. Since driving can be performed in a balanced manner, cam driving can be balanced in the left and right directions, and can be driven stably.

[Brief description of the drawings]

FIG. 1 is a side view of a motorcycle equipped with a square 4 engine according to an embodiment of the present invention, and FIGS. 2, 3, and 4 are detailed views of main parts of the square 4 engine of FIG. And the second
Figure is a side view, Figure 3 is a plan view, Figure 4 is a rear view,
FIG. 5 is a perspective view showing the structure of a single DOHC engine incorporated in the square 4 engine of FIG. 4a, 4b ... crankshaft, 14 ... exhaust passage, 16 ... engine unit, 17 ... cylinder head, 18 ... exhaust pipe, 33
a, 33b, 33c, 33d… cam shaft, 34… cam drive sprocket gear, 36… cam driven sprocket gear, 37… cam chain, 38… cam drive gear, 43
…… Chain room housing, 44 …… Chain room cover.

Claims (1)

(57) [Claims] 1. A square 4 in which exhaust passages are respectively extended from both front and rear cylinders on both sides in the engine width direction of a cylinder head and camshafts extending in the engine width direction are juxtaposed in the cylinder head in the engine front and rear direction.
In the engine, a cam drive sprocket gear is fixed by projecting one end of the crankshaft to one outer surface of the engine unit, and a cam supported by the cylinder head in the engine width direction between the front and rear exhaust passages on the same outer surface. A cam driven sprocket gear is fixed by projecting one end of the drive shaft from the cylinder head, and a cam chain is suspended between the two sprocket gears, while a cam drive gear is fixed in the cylinder head at the other end of the cam drive shaft. ,
The cam drive gear is meshed with a driven gear fixed to the center of the camshaft in the engine width direction to drive the camshaft of each cylinder. A square 4 engine for a motorcycle, wherein the square 4 engine is detachably attached to a side of the engine unit.