JPH0321723B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) 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. This 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 near the center and above 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.

Further, when each intake/exhaust valve is opened and closed by a rocker arm, it is desirable to consider the relationship with the rocker arm and to enable a rational arrangement that is suitable for downsizing and has excellent workability.

(Object 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 via a rocker arm, the ignition plug is connected to the combustion chamber. To provide a single overhead camshaft type engine which can easily secure an attachment/detachment hole while facing near the center, and can be rationally arranged suitable for miniaturization of the engine.

(Structure of the Invention) According to the present invention, the object is to provide one camshaft for one cylinder, and a plurality of camshafts arranged in parallel in the camshaft direction on a plane perpendicular to the camshaft. intake valves and exhaust valves, a plurality of rocker arms that open and close these intake and exhaust valves using camshafts, and one rocker arm that is located on a plane perpendicular to the camshaft and whose ignition part faces near the center of the combustion chamber. In a single overhead camshaft engine equipped with an ignition plug, the attachment/detachment hole of the ignition plug is located between two rocker arms located on one side with respect to the camshaft, and the two rocker arms sandwiching the attachment/detachment hole are connected to the attachment/detachment hole. This is achieved by a single overhead camshaft engine characterized by a curved line along the .

If the camshaft is deviated to one side with respect to the cylinder centerline and the ignition plug is tilted to the other side, the ignition plug attachment/detachment hole can be more easily secured to a larger size.

(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 of them are provided near the rear of the combustion chamber 15. The intake passage 19 opens 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 the exhaust valve 14 and the intake valve 18 are arranged on a plane perpendicular to the camshaft 13 and parallel to each other 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. This camshaft 13
One intake cam 29 for driving the intake valve 18 to open and close is formed approximately in the center thereof, and two exhaust cams 30 and 31 are formed with this cam 29 in between.
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 connected to a pair of left and right rocker arm shafts 34 and 3 located above the camshaft 13.
5 so as to be able to swing independently, one end of which is in sliding contact with the cams 30 and 31, and the other end of which is opposed to the shaft end of each of the exhaust valves 14. Although the rocker arm shafts 34 and 35 are arranged coaxially, a gap is formed between the two shafts through which an attachment/detachment hole 40 for a spark plug 38 (to be described later) passes. As is clear from FIG. 3, these rocker arms 32 and 33 on the exhaust side are curved along the attachment/detachment hole 40, and their tips, that is, the tips on the shaft end sides of the exhaust valves 14 and 14 are close to each other. For this reason, even when the distance between both exhaust valves is small in a small displacement engine,
It becomes possible to secure a sufficient space for the attachment/detachment hole 40.

36 is an intake rocker arm, which is connected to the camshaft 13.
It is pivotally supported by one rocker arm shaft 37 located higher up. The rocker arm shaft 37 is positioned so as to form a substantially inverted triangle in side view 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 the 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 and 14 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.

(Effect of the invention) As described above, the present invention has a plurality of suction and
When each cylinder has an exhaust valve, a plurality of rocker arms, and one spark plug whose ignition part faces near the center of the combustion chamber, the spark plug is arranged between two rocker arms on the intake side or the exhaust side. Since these rocker arms are curved along the spark plug attachment/removal hole, the engine can be made smaller while ensuring a large spark plug attachment/removal hole. In addition, since the spacing between valves opened and closed by these locking arms can be narrowed, especially when applied to small displacement engines,
The ignition plug can be easily placed between the rocker arms without increasing the valve interval.

[Brief explanation of the drawing]

FIG. 1 is a partially cross-sectional view of a motorcycle equipped with an engine according to 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, 32, 33, 36...Rotsuka arm, 3
4, 35...Rotsuka arm shaft, 38...Ignition plug,
39... Electrode as an ignition part, 40... Attachment/removal hole.

Claims (1)

[Claims] 1. For one cylinder, one camshaft, and a plurality of intake valves and exhaust valves arranged in parallel in the camshaft direction on a plane perpendicular to the camshaft. , a plurality of rocker arms that open and close these intake and exhaust valves using camshafts, and one spark plug that is located on a plane perpendicular to the camshaft and whose ignition part faces near the center of the combustion chamber. In the camshaft type engine, the attachment/detachment hole of the ignition plug is located between two rocker arms located on one side of the camshaft, and the two rocker arms sandwiching the attachment/detachment hole are curved along the attachment/detachment hole. A single overhead camshaft engine featuring: