JPH01110864A - One overhead cam shaft type engine - Google Patents

Abstract

PURPOSE:To provide an ignition plug on an ideal position, together with an attaching/detaching hole therefore, so as to improve workability thereof and sealing ability of the attaching/detaching hole by locating the ignition plug between rocker arms, setting a bearing cut surface of a camshaft flush with an upper surface of a cylinder head, and integrally forming an ignition plug attaching/detaching hole on a cap member. CONSTITUTION:An ignition plug 38 is detachably mounted between discharge side rocker arms 34, 35, while an attaching/detaching hole 40 communicated with a cylinder head 22 is integrally formed on a cylinder head cover 23. The ignition plug 38 is arranged to face to a part in the vicinity of the center of a combustion chamber 15, so that the attaching/detaching hole 40 thereof can naturally be secured. The works on the cut surface of the bearing of a camshaft 13 and the upper surface of a cylinder head 22 can simultaneously be performed so that work steps can be reduced to improve workability. Furthermore, the fitting surface between attaching/detaching holes 30 respectively on the cylinder head 22 side and the cylinder head 23 as a cap member is arranged flush with the upper face of the cylinder head 22, thereby the sealing ability between the attaching/detaching holes 40 themselves can be improved.

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. In addition, the ignition plug attachment/removal hole also serves as a partition wall between the valve chamber that houses the valve mechanism,
It is also necessary to improve the sealing performance between them.

In addition, when each plate/exhaust valve is opened and closed by a rocker arm, it is desirable to consider the relationship with these rocker arms and to enable a rational arrangement that is suitable for miniaturization, has excellent workability, and can reduce the number of parts.

(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 installation/removal hole can be easily secured, and the sealing performance of the ignition plug installation/removal hole can be improved. It is an object of the present invention to provide a single overhead camshaft type engine which is suitable for miniaturization of the engine, has excellent workability, and enables rational arrangement suitable for reducing the number of parts.

(Structure of the Invention) According to the present invention, the object is to provide a single camshaft within a substantially ■-shaped angle in side view formed by a plurality of intake valves and a plurality of exhaust valves mounted on a cylinder head. The camshaft is located on a plane perpendicular to the camshaft, and its ignition part faces near the center of the combustion chamber.
In a single overhead camshaft type engine, which has two ignition plugs and a plurality of rocker arms that open and close intake and exhaust valves using camshafts, there are two rocker arms on the intake side or the exhaust side, and the ignition plug is positioned between them. , the bearing split surface of the camshaft is located on the same plane as the upper surface of the cylinder head, and a cap member that holds the camshaft bearing from above is integrally formed with an ignition plug attachment/removal hole that tightly contacts the cylinder head. This is achieved by a single overhead camshaft engine.

Here, the camshaft is offset to one side with respect to the Schilling center line,
If the ignition plug is tilted to the other side, the ignition plug attachment/detachment hole can be made wider (and secured) more easily.

(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 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 the same. -II
They are sectional views taken along the I line and the IV-IV line.

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;
Reference numeral 6 also designates a main pipe whose front end is welded to the head pipe 5 and extends rearward approximately horizontally. 7 is the same (down tube that constitutes the main frame 1, the side is bent into an approximately inverted trapezoid, and the front end is welded to the head vibe 5 and the rear end to the main vibe, respectively. 8 is a kunk rail, and 9 is a down tube. This is a reinforcing stay.The front wheel fork 2 is rotatably supported by the head vibe 5 of the main frame 1.The reference numeral 10 is a rear arm that pivotally supports the rear wheel 4, and its front end is connected vertically to the main frame 1. It is pivotally mounted so as to be swingable, and a spring 11 with a damper is installed between the rear end and the main vibro.

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 near the front 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 near the rear 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 placed side by side near the rear of 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. Here, the intake valve 18 and the exhaust valve 14 are
They are arranged in parallel in the longitudinal direction of the camshaft 13 so as to be perpendicular to the camshaft 13. A camshaft 13 is laterally supported between the mating surfaces of the cylinder head 22 and the head cover 23 in a space within the narrow angle of the side view road ■-shaped formed by the intake valve 14 and the exhaust valve 14. The center of the camshaft 13 is located below the line connecting the ends of each valve shaft. 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. One intake cam 29 for opening and closing the intake valve 18 is formed approximately at 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 designate a pair of left and right exhaust rocker arms that are made separately, and these are independently pivotably supported by a pair of left and right rocker arm shafts 34 and 35 located above the camshaft 13. One end of each of the cams 30.
31, and the other end faces the shaft end of each exhaust valve 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 an ignition plug 38 (to be described later) 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 the rocker arm 34.35 on the exhaust side.
and the camshaft 13 are positioned so as to form a substantially inverted triangle when viewed from the side. This rocker arm 36 has one end connected to the cam 29.
The other end is bifurcated and faces the shaft ends of the two intake valves 18 described above.

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 column 38. That is, the head cover 23 also serves as a cap member for holding the bearing of the camshaft 13 from above, 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 column 38 can be attached and detached from diagonally above the front of the engine 12, that is, from below the 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 the intake valves 18, 18 and is directed toward the rear of the 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 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 includes one camshaft and one camshaft within an included angle approximately on the ■ side in side view surrounded by a plurality of intake and exhaust valves.
Since the ignition plugs and the rocker arms of the intake and exhaust valves are arranged, they can be compactly accommodated in parallel within the included angle of the V-shape.

Also, the ignition plug is arranged so that its ignition part faces near the center of the combustion chamber and is located between two rocker arms on the intake side or the exhaust side, so that the ignition plug can be attached or removed from between these two rocker arms. Therefore, it is possible to arrange the ignition plug in an ideal position and also secure a hole for attaching and detaching the spark plug.

Furthermore, since the camshaft is located on the same plane as the top surface of the cylinder head, that is, the base surface of the cylinder and the rad cover,
Machining of the split surface of the camshaft bearing can be done simultaneously with machining of the upper surface of the cylinder head, reducing the number of machining steps and improving workability.

Furthermore, since the ignition plug attachment/detachment hole is integrally formed in the cap member that holds the camshaft bearing from above, the base surface of the attachment/detachment hole on the cylinder head side and the cap member side is also the same as the above-mentioned cylinder head top surface. The reliability of the seal between the attachment/detachment holes can be increased, and the number of parts can be reduced.

[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 vertical sectional view of the main part, and Figs. 3 and 4 are the same (TII -TII
FIG. 12... Overhead camshaft engine, 13... Camshaft, 14... Exhaust valve, 15... Combustion chamber, 18... Intake valve, 22... Cylinder head, 23... Cap Cylinder head cover as a member, 32.33.36... Rocker arm, 38... Ignition plug, 39... Electrode as an ignition part, 40... Attachment/removal hole. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] Within a substantially V-shaped angle in side view formed by a plurality of intake valves and a plurality of exhaust valves mounted on the cylinder head, there is one camshaft and a plane perpendicular to this camshaft. A combustion engine with one spark plug located at the top, with its ignition part facing near the center of the combustion chamber, and multiple rocker arms that open and close intake and exhaust valves using camshafts.
In an overhead camshaft type engine, there are two rocker arms on the intake side or the exhaust side, a spark plug is positioned between them, and the bearing split surface of the camshaft is
A single overhead camshaft, characterized in that an ignition plug attachment/removal hole that is in close contact with the cylinder head is integrally formed in a cap member that is located on the same plane as the upper surface of the cylinder head and that holds the bearing of the camshaft from above. type engine. (2) The camshaft is arranged offset to one side with respect to the cylinder centerline, and the spark plug is inclined toward the other side. camshaft engine.