JPH0321724B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Field of Application) This invention provides a method for connecting the intake and exhaust valves using a single camshaft when each cylinder has a plurality of intake valves and a plurality of exhaust valves. The present invention relates to a single overhead camshaft type engine that is driven to open and close.

(Background of the Invention) Conventionally, there has been a so-called overhead camshaft (hereinafter referred to as OHC) engine in which a camshaft is disposed in the engine head and adapted to high-speed rotation. Also 1
Engines that pursue high output by providing a plurality of intake valves and a plurality of exhaust valves for each combustion chamber to increase intake and exhaust efficiency are already known.

When constructing an OHC engine with multiple intake and exhaust valves, conventionally, separate camshafts were provided for each intake and exhaust valve, resulting in a double overhead cam (DOHC) configuration.
A spark plug was placed between both camshafts. But this
DOHC configurations had the problem of increasing the number of parts and making the engine larger. Therefore, a configuration in which all the intake and exhaust valves are opened and closed by a single camshaft has been considered, but in this case, the layout especially around the cylinder head becomes a problem. In other words, it is desirable to arrange the spark plug so that the electrode, which is the ignition part, faces approximately 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 may This is because the ignition plugs are close together, making it particularly difficult to secure a space (attachment/detachment hole) for attaching and detaching the ignition plug. As a result, there was a problem in that the cylinder head became larger.

(Purpose of the Invention) This invention was made in view of the above circumstances, and when a plurality of intake valves and exhaust valves are driven to open and close by a single camshaft, the ignition plug is positioned near the center of the combustion chamber. To provide a single overhead camshaft type engine which can easily secure an attachment/detachment hole while increasing the size of the engine, and is suitable for downsizing the engine.

(Structure of the Invention) According to the present invention, the object is to provide one cylinder with one camshaft and a plurality of camshafts arranged in parallel in the camshaft direction on a plane perpendicular to the camshaft. An intake valve, a plurality of exhaust valves, a plurality of rocker arms held by a rocker arm shaft parallel to a camshaft and opening and closing these intake and exhaust valves by the camshaft, and a rocker arm located on a plane perpendicular to the camshaft and having an ignition portion thereof. In a single overhead camshaft engine equipped with a spark plug facing near the center of a combustion chamber, the camshaft is deflected to one side, and the distance between two rocker arms on the opposite side to the direction of this deviation is widened, and the camshaft is widened on the other side. the rocker arm on the opposite side of the camshaft deflection direction.
This is achieved by a single overhead camshaft type engine characterized in that the rocker arm shaft of the two rocker arms is divided between both rocker arms, and a spark plug attachment/removal hole is arranged between the two divided rocker arm shafts.

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

FIG. 1 is a partially sectional side view of a motorcycle equipped with an engine that 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 sectional views taken along the - line and - line in FIG. 2.

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. Numeral 5 is a steering head pipe constituting the main frame 1, and 6 is a main pipe whose front end is welded to the head pipe 5 and extends rearward approximately horizontally. Reference numeral 7 designates a down tube which also constitutes the main frame 1, and whose side surfaces are bent into a substantially inverted trapezoid shape and whose front end is welded to the head pipe 5 and its rear end to the main pipe 6, respectively. Further, 8 is a tank rail, and 9 is a reinforcing stay. The front wheel fork 2 is rotatably supported by a head pipe 5 of the main frame 1. Reference numeral 10 denotes a rear arm that pivotally supports the rear wheel 4. Its front end is pivotally attached to the main frame 1 so as to be able to swing vertically, and a spring 11 with a damper is installed between the rear end and the main pipe 6. has been done.

Reference numeral 12 designates a single overhead camshaft type single cylinder engine having one camshaft 13, which is located below and rearward of the head pipe 5. The upper and lower parts of this engine 12 are held by the main pipe 6 and down tube 7, respectively. Reference numeral 14 designates exhaust valves, two of which are provided near the front of the combustion chamber 15. The exhaust passage 16 opens in the vehicle traveling direction of the engine 12,
Exhaust gas exiting from this exhaust passage 16 is guided to the rear of the vehicle by an exhaust pipe 17. 18 is an intake valve;
Two intake passages 19 are provided near the rear of the combustion chamber 15 and open toward the rear of the engine 12.
A vaporizer 20 is connected here. Exhaust valve 1
4 and the intake valve 18 are provided in a cylinder head 22 joined above the 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 the rocker arm 32,
33, 36, rocker arm shaft 34, 35, 37,
Valve operating functions such as valve springs 27 and 28 are accommodated. In addition, 24 in the figure is a sprocket provided integrally with the camshaft 13, and this sprocket 24
A timing chain 26 is spanned between and a sprocket 25 provided on the crankshaft.
The camshaft 13 rotates once when the crankshaft rotates twice.

Next, the cylinder head 22 is
Describe the area. 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, and this valve spring 27 moves in the direction of closing the exhaust valve 14. It is energizing. Two intake valves 18 are arranged in parallel near the rear of the combustion chamber 15. 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 on a plane perpendicular to the camshaft 13 and are arranged in parallel in the camshaft direction. 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 supported horizontally between the mating surfaces of the cylinder head 22 and the head cover 23. ing. As is clear from FIGS. 2 and 3, the camshaft 13 is offset toward the intake valve 18 with respect to the center of the cylinder. One intake cam 29 for opening and closing the intake valve 18 is formed approximately in the center of the camshaft 13, 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 parallel to the camshaft 13.
4 and 35, each of which is rotatably supported independently,
One end thereof slides into contact with the cams 30 and 31, respectively, and the other end faces the shaft end of each exhaust valve 14. Although the rocker arm shafts 34 and 35 are coaxially arranged, there is a spark plug 38 (described later) between the two shafts.
A gap is formed through which the attachment/detachment hole 40 passes. 36
is an intake rocker arm, which is rotatably supported by one rocker arm shaft 37 located above the camshaft 13. Rotsuka arm shaft 37
is located so as to form a substantially inverted triangle when viewed from the side together with the rocker arm shafts 34 and 35 on the exhaust side and the camshaft 13. One end of the rocker arm 36 is in sliding contact with the cam 29, and the other end is bifurcated and faces the shaft ends of the two intake valves 18, respectively.

Reference numeral 38 denotes an ignition plug, and an electrode 39 which is the ignition part at the tip faces approximately the center of the combustion chamber 15 from a position surrounded by each exhaust valve 14 and intake valve 18, and is located between the two exhaust valves 14. It is attached so as to be substantially parallel to this exhaust valve 14. That is, the ignition plug 38 is located on a plane perpendicular to the camshaft 13 and can be attached and detached from between the two rocker arm shafts 34 and 35 on the exhaust side. This spark plug 3 is attached to the cylinder head 22 and head cover 23.
An attachment/detachment hole 40 is formed for attaching and detaching the device 8. That is, the cap member that holds the bearing of the camshaft 13 from above is also used as the head cover 23, and the cylinder head 2 is attached to this head cover 23.
An attachment/detachment hole 40 is integrally formed on the second 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 upper front of the engine 12, that is, from the lower rear of the head pipe 5.

41 is a cooling air passage formed in the cylinder head 22, and its front opening 42 is connected to two exhaust valves 1.
The rear opening 43 passes between the two intake valves 18, 18 and is oriented toward the front of the engine 12.
It passes through the gap and points toward the rear of the engine 12.
This cooling air passage 41 merges with the attachment/detachment hole 40 near the spark plug 38, and also joins the camshaft 13.
It is formed to pass under the In this embodiment, as is clear from FIGS. 3 and 4, the camshaft 1
A horizontal cooling air passage 44 is formed in the cylinder head 23, passing below the cylinder head 3 and merging with the cooling air passage 41 near the spark plug 38. The cooling air passage heat radiation passage 44 has a side surface opposite to the sprocket 24 that opens laterally.

In the above embodiment, the attachment/detachment hole 40 of the spark plug 38 is inclined toward the exhaust valve 14 side, and the camshaft 13 is connected to the intake valve 14 side.
Although the spark plug 38 is tilted toward the intake valve 18 side, it is also possible to tilt the camshaft 13 toward the opposite side. In this case, two intake rocker 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 for one cylinder,
One camshaft, multiple intake valves and exhaust valves,
When the camshaft is deviated to either side of the intake/exhaust valve when the ignition plug has multiple locker arms and one spark plug with an ignition part facing near the center of the combustion chamber, two locker arms on the opposite side can be used. The distance between the two locking arms is widened and the locking arm shafts on the other side are made wider and the locking arm shafts of these longer locking arms are divided, and the divided locking arm shafts are connected between the intake/exhaust valves and camshafts on the same side. Since the ignition plug mounting/detaching hole is arranged between the two divided rocker arm shafts, a sufficiently large spark plug mounting/detaching hole must be secured in the space surrounded by the two long rocker arms and the camshaft. Can be done. 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 that 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 sectional views taken along the - line and - line in FIG. 2. 12...Overhead camshaft engine, 13...Camshaft, 14...Exhaust valve, 15...Combustion chamber, 18...
Intake valve, 34, 35... Rotsuka arm shaft, 38...
...Spark plug, 39...Electrode as ignition part, 40...
...Detachment hole.

Claims (1)

[Claims] 1. For one cylinder, one camshaft, and a plurality of intake valves and a plurality of exhaust valves arranged in parallel in the camshaft direction on a plane perpendicular to the camshaft. , a plurality of rocker arms held by rocker arm shafts parallel to the camshaft, which open and close these intake and exhaust valves by the camshafts, and a plurality of rocker arms located on a plane perpendicular to the camshafts, with their ignition parts facing near the center of the combustion chamber. In a single overhead camshaft engine equipped with a spark plug, the camshaft is deflected to one side, and the distance between the two rocker arms on the opposite side to the direction of the deflection is widened and the rocker arms on the other side are made longer, A single overhead camshaft type engine, characterized in that the rocker arm shaft of the rocker arm on the opposite side to the deflection direction of the camshaft is divided between both rocker arms, and a spark plug attachment/removal hole is arranged between the two divided rocker arm shafts.