JPH01104905A - Single overhead camshaft engine - Google Patents

Abstract

PURPOSE:To miniaturize an engine as securing a setting hole to be large enough by deflecting a camshaft to either side of a suction or exhaust valve, while setting up the setting hole of a spark plug between two rocker arms at the deflection side and the opposite side. CONSTITUTION:In one cylinder, there are provided with one camshaft 13, an exhaust valve 14 and a suction valve 18 paralleled so as to be orthogonal with this camshaft 13, and three rocker arms 32, 33, 36 being supported by rocker arms 34, 35, 37 in parallel with the camshaft 13 and opening or closing these valves 14 and 15, respectively. Also there is provided with a spark plug 38 which is situated on a vertical flat surface of the camshaft 13 and its ignition part 39 is adjoined to the inside of a combustion chamber 15. In this constitution, the camshaft 13 is deflected to one side, for example, the side of the suction valve 18 to the cylinder center. In addition, a clearance, where a setting hole 40 of the spark plug 38 is passed through, is formed in a space between these rocker arms 34 and 35. Then, the setting hole 40 is formed in a cylinder head 22 and a head cover 23 respectively.

Description

Detailed Description of the Invention (Industrial Application Field) This invention provides a method for opening and closing these intake and exhaust valves using a single camshaft when each cylinder has a plurality of intake valves and exhaust valves. This invention relates to a single overhead camshaft type engine.

(Background of the Invention) The so-called overhead camshaft (hereinafter referred to as OHC) is a camshaft that is conventionally arranged in the head of the engine and adapted to high-speed rotation.
There is an engine. Furthermore, an engine is already known in which a plurality of intake valves and a plurality of exhaust valves are provided in each combustion chamber to improve intake and exhaust efficiency, thereby achieving high output.

In this way, it has multiple intake and exhaust valves.
Conventionally, when constructing an HC engine, separate camshafts were provided for the intake and exhaust valves, a double-over-rad cam (DOHC) configuration was used, and a spark plug was disposed between both camshafts. However, this DOHC configuration had the problem that the number of parts increased and the engine became larger. So 1
A configuration in which all the intake and exhaust valves are opened and closed using a single camshaft is conceivable, but in this case, the layout around the cylinder head in particular becomes a problem. In other words, it is desirable to arrange the spark plug so that the electrode, which is the ignition part, faces almost the center of the combustion chamber, but if the camshaft is located above the center of the combustion chamber, the valve mechanism such as the camshaft This is because the ignition plugs become close to each other, making it particularly difficult to secure a space (attachment/detachment hole) for attaching and detaching the ignition plug. Therefore, there was a problem in that the cylinder head became larger.

(Object of the invention) This invention was made in view of the above circumstances,
When opening and closing multiple intake valves and exhaust valves using a single camshaft, the ignition plug can be placed close to the center of the combustion chamber and the attachment/detachment hole can be easily secured, and it is also suitable for downsizing the engine. The purpose is to provide an overhead camshaft type engine.

(Structure of the Invention) According to the invention, this object is to
A camshaft, a plurality of intake valves and a plurality of exhaust valves arranged in parallel perpendicularly to the camshaft, and a rocker arm shaft parallel to the camshaft holds the intake and exhaust valves, which are opened and closed by the camshaft. In a single overhead camshaft engine comprising a plurality of rocker arms and an ignition plug located on a plane perpendicular to the camshaft and having an ignition portion thereof facing near the center of a combustion chamber, the camshaft is deflected to one side. , the distance between the two rocker arms on the opposite side to this deflection direction is made wider and longer than the rocker arm on the other side, the rocker arm axes of these rocker arms are divided between both rocker arms, and the ignition is carried out between the two divided rocker arm axes. This is achieved by a single overhead camshaft type engine which is characterized by the arrangement of plug attachment/removal holes.

(Example) The present invention will be described in detail below based on the drawings.

Fig. 1 is a partially sectional side view of a motorcycle equipped with an engine which is an embodiment of the present invention, Fig. 2 is a vertical sectional view of the main part thereof, and Figs. 3 and 4 are the same. 1. -III line and IV-IV line sectional view.

In Fig. 1, numeral 1 is a cradle type main frame;
2 is a front wheel fork, 3 is a front wheel, and 4 is a rear wheel. 5 is a steering head pipe that constitutes the main frame 1;
6 is the same (main pipe, the front end is welded to this head pipe 5 and extends rearward almost horizontally. 7 is the down tube that also constitutes the main frame 1, the side is bent into an approximately inverted trapezoid, the front end is is welded to the head vibrator 5, and its rear end is welded to the main vibro. 8 is a tank rail, and 9 is a reinforcing stay. The front wheel fork 2 is rotatably attached to the head vibrator 5 of the main frame 1. 10 is a rear arm that pivotally supports the rear wheel 4, and its front end is pivotally attached to the main frame 1 so as to be able to swing up and down, and between the rear end and the main vibro is a rear arm equipped with a damper. A spring 11 is attached.

Reference numeral 12 denotes a single overhead camshaft type single cylinder engine having one camshaft 13, which is located below and rearward of the head vibe 5. The upper and lower parts of this engine 12 are held by the main vibro and down tube 7, respectively. Reference numeral 14 designates exhaust valves, two of which are provided in the front band of the combustion chamber 15. The exhaust passage 16 opens in the vehicle traveling direction of the engine 12, and the exhaust gas exiting from the exhaust passage 16 is guided to the rear of the vehicle by an exhaust pipe 17. Reference numeral 18 denotes intake valves, two of which are provided in the rear band of the combustion chamber 15. The intake passage 19 opens toward the rear of the engine 12, and a carburetor 20 is installed here.
is connected. The exhaust valve 14 and the intake valve 18 are provided in a cylinder head 22 joined above a cylinder block 21, and a cylinder head cover 23 is mounted above the cylinder head 22. A valve train chamber is formed by these cylinder head 22 and cylinder head cover 23, and rocker arms 32, 33, 36
, rocker arm shaft 34.35.37, valve spring 27.28
The valve train functions such as the following are accommodated. In addition, 24 in the figure is a sprocket provided integrally with the camshaft 13, and a timing chain 26 is passed between this sprocket 24 and a sprocket 25 provided on the crankshaft. When the camshaft 13 rotates twice, the camshaft 13 rotates once.

Next, the vicinity of the cylinder head 22 will be explained based on FIGS. 2 to 4. The two exhaust valves 14 are arranged side by side on the cylinder head 22 so as to be tilted forward, and a valve spring 27 is attached to the upper protrusion of the shaft portion 14a.
4 in the direction of closing. The intake valve 18 is the combustion chamber 1
Two of them are arranged side by side on the rear obi of No. 5. The intake valve 18 is provided so as to be inclined rearward, and a valve spring 28 is attached to the upper protrusion of the shaft portion 18a, urging the intake valve 18 in the closing direction. The valve shafts of these intake and exhaust valves are cam shafts 13
They are arranged in parallel so that they are orthogonal to each other. In the space within the included angle of the V-shaped path in side view formed by the exhaust valve 14 and the intake valve 18,
One camshaft 13 is laterally supported between mating surfaces of the cylinder head 22 and head cover 23. As is clear from FIG. 2.3, this camshaft 13 is offset toward the intake valve 18 side with respect to the center of the cylinder. This camshaft 13
In the middle of the figure, there is an intake cam 2 that opens and closes the intake valve 18.
One cam 9 is formed, and two exhaust cams 30 and 31 are formed sandwiching this cam 29. The sprocket 24 is fixed to one end of the camshaft 13.

Reference numerals 32 and 33 denote a pair of left and right exhaust rocker arms that are made separately, and these are located above the camshaft 13 and between the camshaft 13 and the exhaust valve 14, and are connected to a pair of left and right rocker arm shafts 34 that are parallel to the camshaft 13. Each of the cams 30.
1, and the other end faces the shaft end of each exhaust valve 14. Note that the rocker arm shafts 34 and 35 are arranged coaxially, but between the two shafts there is an attachment/removal hole 4 for a spark plug 38, which will be described later.
A gap is formed through which 0 passes.

Reference numeral 36 denotes an intake rocker arm, which is pivotally supported by a single rocker arm shaft 37 located above the camshaft 13 so as to be freely swingable. The rocker arm shaft 37 is positioned so as to form a substantially inverted triangle in side view together with the rocker arms 34 and 35 on the exhaust side and the camshaft 13. The rocker arm 36 has one end facing the cam, and the other end is bifurcated and faces the shaft ends of the two intake valves 18, respectively.

38 is a spark plug, and an electrode 39 is the ignition part at its tip.
faces substantially the center of the combustion chamber 15 from a position surrounded by each exhaust valve 14 and intake valve 18, and is installed so as to be located between the two exhaust valves 14 and substantially parallel to the exhaust valves 14. That is, this ignition column 38 is located on a plane perpendicular to the camshaft 13, and is located on a plane perpendicular to the camshaft 13, and is connected to the two exhaust side rocker arms 34, 35.
It can be put on and taken off from between. An attachment/detachment hole 40 is formed in the cylinder head 22 and head cover 23 for attaching and detaching the ignition plug 38. That is, the cap member for holding the bearing of the camshaft 13 from above is also used by the head cover 23, and the head cover 23 is integrally formed with an attachment/detachment hole 40 that closely contacts the cylinder head 22 side and communicates with the cylinder head 22.

This attachment/detachment hole 40 opens obliquely toward the front and upper side of the engine 12. Therefore, the ignition plug 38 can be attached and removed from the diagonally upper front of the engine 12, that is, from the lower rear of the head vibrator 5.

41 is a cooling air passage formed in the cylinder head 22, the front opening 42 of which passes between the two exhaust valves 14, 14, and points toward the front of the engine 12; It passes between valves 18, 18 and is directed toward the rear of engine 12.

This cooling air passage 41 merges with the attachment/detachment hole 40 near the ignition plug 38 and is formed to pass below the camshaft 13. In this embodiment, as is clear from FIG. 3.4, the ignition column 38 passes below the camshaft 13.
A lateral cooling air passage 44 that merges with the cooling air passage 41 in the vicinity is formed in the cylinder head 23 .

The cooling air passage heat radiation path 44 has a side surface opposite to the sprocket 24 that opens laterally.

In the above embodiment, the attachment/detachment hole 40 of the ignition plug 38 is connected to the exhaust valve 14.
Although the camshaft 13 is tilted toward the intake valve 18 side, the ignition plug 38 is tilted toward the intake valve 18 side and the camshaft 13 is tilted toward the intake valve 18 side.
It is also possible to deviate it to the opposite side. In this case, two intake port arms 36 may be provided, and the spark plug 38 may be placed between them.

(Effects of the Invention) As described above, the present invention provides one cylinder with one camshaft, a plurality of intake valves and exhaust valves, a plurality of rocker arms, and an ignition part facing near the center of the combustion chamber. When the camshaft has one spark plug, the camshaft is deviated to either side of the intake/exhaust valve, and the distance between the two rocker arms on the opposite side is widened and the rocker arm on the other side is made longer. Then, the rocker arm shaft of these longer rocker arms is divided, and the divided rocker arm shaft is positioned between the intake/exhaust valves and the camshaft on the same side as these, and between the two divided rocker arm shafts. Since the ignition plug attachment/detachment hole is disposed in the space between the two long rocker arms and the camshaft, a sufficiently large spark plug attachment/detachment hole can be secured in the space surrounded by the two long rocker arms and the camshaft. Additionally, the camshaft can be placed at a sufficiently low position, making it possible to downsize the engine.

[Brief explanation of the drawing]

Fig. 1 is a partially sectional side view of a motorcycle equipped with an engine which is an embodiment of the present invention, Fig. 2 is a longitudinal sectional view of the main part thereof, and Figs. 3 and 4 are the same (III -III
FIG. 4 is a sectional view taken along the line and IV-IV. 12... Overhead camshaft engine, 13-... Camshaft, 14... Exhaust valve, 15... Combustion chamber, 18... Intake valve, 34. 35... Rocker arm shaft, 38... - Spark plug, 39... Electrode as ignition part, 4
0... Attachment/detachment hole. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] For one cylinder, one camshaft, a plurality of intake valves and a plurality of exhaust valves arranged in parallel orthogonally to the camshaft, and a rocker arm shaft parallel to the camshaft. a single overhead camshaft comprising: a plurality of rocker arms held in the camshaft for opening and closing these intake and exhaust valves by the camshaft; and an ignition plug located on a plane perpendicular to the camshaft, the ignition part of which faces near the center of the combustion chamber; type engine, the camshaft is deflected to one side, the distance between the two rocker arms on the opposite side to the direction of deflection is made wider and longer than the rocker arm on the other side, and the rocker arm axes of these rocker arms are aligned with both rocker arms. A single overhead camshaft type engine characterized by having an ignition plug attachment/removal hole arranged between the two divided rocker arm shafts.