JPH0255811A - Four-valve one-overhead cam shaft engine - Google Patents

Abstract

PURPOSE:To facilitate a layout by arranging a pair of exhaust valves in both sides of a spark plug, arranging a cam shaft in a plane containing an intake valve and opening and closing the exhaust valve through a rocker arm. CONSTITUTION:A pair of exhaust valves 34 are arranged in both sides of a spark plug provided in the vicinity of the center axis A of a cylinder. An intake valve 36 is provided to be arranged in one side of a plane B containing the exhaust valve 34. A cam 40 is provided on a plane D containing the intake valve 36, while the exhaust valve 34 is opened and closed by a pair of rocker arms 52. In this way, a layout can be facilitated by preventing the rocker arm from interfering with a mountremoval hole of the spark plug.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a four-valve single overhead camshaft engine that opens and closes two intake valves and two exhaust valves per cylinder using a single camshaft. .

(Background of the Invention) A four-valve engine is known in which each cylinder has two intake valves and two exhaust valves. In this case, conventionally, two camshafts were arranged parallel to each other on both sides of the cylinder center.
A so-called double overhead camshaft (DOHC) system is used in which each camshaft directly opens and closes two intake valves and two exhaust valves, but in this case there is a problem that the engine becomes larger. Various proposals have also been made to reduce the number of camshafts to one. For example, there is one in which a camshaft is slightly deviated from the center of the cylinder toward the side opposite to the spark plug so as not to interfere with the spark plug near the center of the cylinder, and the intake and exhaust valves are opened and closed by the camshaft via rocker arms. However, in this case, not only does the number of rocker arms increase, but there is a risk that the rocker arm that opens and closes the intake valve or exhaust valve, which is located on the same side of the camshaft as the ignition plug, may interfere with the ignition plug attachment/removal hole. Conventionally, this rocker arm had to be forcibly curved, which caused problems in terms of layout and poor assembly efficiency.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and it eliminates the risk of the rocker arm interfering with the ignition plug attachment/removal hole, allows for easy layout of each member, and reduces the size of the engine. The purpose of the present invention is to provide a 4-valve, 1-overhead camshaft engine that is suitable for increasing the number of parts and reducing the number of parts.

(Structure of the Invention) According to the present invention, this purpose is to provide four suction and
In a four-valve single overhead camshaft engine that opens and closes exhaust valves, there is one spark plug located near the center axis of the cylinder, and a pair of exhaust/intake valves located on both sides of the spark plug.
a pair of intake/exhaust valves disposed on one side of a plane containing the pair of exhaust/intake valves, and the camshaft is disposed near the plane containing the intake/exhaust valves, while the exhaust/exhaust valves are disposed near the plane containing the intake/exhaust valves. This is achieved by a 4-valve, 1-overhead camshaft engine characterized in that the intake valves are opened and closed by a pair of rocker arms held by a rocker shaft parallel to the camshaft.

(Example) Fig. 1 is an overall schematic diagram of a type 6-cylinder engine according to an embodiment of the present invention, Fig. 2 is a plan view showing the left bank valve chamber, and Figs. 3.4.5 are 6 III-II in Figure 2
I! 3, 1V-iV line oyobi v-v! J! The sectional view, FIG. 6, is a bottom view of the cylinder head to show the valve arrangement.

In Figure 1, the engine consists of a pair of banks 10 forming a roughly ■ shape.
．． 10, and each bank 10 has a cylinder ladder head 14 and a head cover 16 attached to a cylinder block 12 that is approximately pentagonal in front view. The cylinders 18.18 of both banks 10.10 form an angle of 90°, and the pistons 20.20 of the cylinders in each bank 10.10 that form a pair with each other form a crankshaft 24 with a phase difference of 30°.
a and 24b by connecting rods 26 and 26, respectively. Here, the crankshaft 22 rotates clockwise in FIG. Each bank 10.10 has both banks 10
．． The intake pipe 28 disposed on the valley side of the V-shape formed between the banks 10 and 10 is connected, and the exhaust pipe 30.30 is connected to each bank 10.1.
Connected to the outer surface of 0. 31 oil pan.

Next, the cylinder head 14 will be explained, but since it is bilaterally symmetrical, the cylinder head 14 of the left bank 10 will be used for explanation.

The cylinder head 14 has cylinder 1 for three cylinders.
8 are arranged in parallel to the crankshaft 22, and each cylinder has an ignition plug 32 arranged near the cylinder center axis A, and two exhaust valves 34 arranged in parallel on the crankshaft 22 with the ignition plug 32 in between. .34 and plane B containing these exhaust valves 34.34.
(Fig. 4) A pair of intake valves 36 and 36 are provided at the valley sides of the V-shape with the gap between them. For this reason, the combustion chamber 38 is the third.
As shown in FIG. 6, it has a bathtub shape that is long in the direction of the crankshaft 22, and a large squish area C is formed on the opposite side of the intake valve 36 with the plane B in between.

A plane B including the two exhaust valves 34, 34 is approximately parallel to and close to the cylinder central axis A.

Further, the plane D (FIG. 4) including the two intake valves 36, 36 is largely inclined toward the valley side of the V-shape with respect to the cylinder center axis A, and the V-shape is formed by both hand surfaces B and D.

40 is a single camshaft parallel to the crankshaft 22, the center of which is on a plane containing the intake valves 36.36, and directly presses the valve lifters 42.42 of the intake valves 36.36 to release the intake air. Valves 36 and 36 are opened and closed in the same phase. 44 is a rocker shaft located between both hand surfaces B and D and parallel to the camshaft 40. The cut plane between the head cover 16 and the cylinder head 14 is parallel to the cut plane between the cylinder head 14 and the cylinder block 12, and the cam shaft 40 and the rocker shaft 44 are parallel to the cut plane between the head cover 16 and the cylinder head 14. Located in Both ends of the camshaft 40 and the rocker shaft 44 are held between the split surfaces of the cylinder head 14 and the head cover 16, and are held between the cylinder head 14 and the cap 46 above the center of each cylinder. This cap 46
is fixed to the cylinder head 14 by a pair of bolts 48, 48 that sandwich the camshaft 40, and a bolt 50 that passes through the rocker shaft 44. A pair of rocker arms 52 and 52 are held on the rocker shaft 44 with a cap 46 in between, and one end of these rocker arms 52 is attached to the intake cam 4 of the cam shaft 40.
Exhaust side cams 40b, 40 located outside of 0a, 40a
b slidingly contacts from above, and the other end contacts the upper end of the exhaust valve 34.34. The ram shaft 40 rotates clockwise in FIG. 4.

Reference numeral 54 designates an attachment/detachment hole for the ignition plug 32. The lower end of the metal pipe is press-fitted into the cylinder head 14, and the upper end is inserted into the head cover 1.
6, and the plug cord is connected to the spark plug 32 by inserting the plug cap 56 into the opening formed in the head cover 16. An O-ring is attached to the outer periphery of the upper end of the attachment/detachment hole 54, and this O-ring is in close contact with the inner circumferential surface of the fitting hole on the head cover 16 side to ensure liquid tightness of the valve chamber. Reference numeral 58 designates an electromagnetic fuel injection valve, which is connected to each intake valve 36 .
Gasoline fuel is injected toward the vicinity of the branch to 36. A clip 6 made of metal or resin is attached to the rocker shaft 44 to restrict movement of the rocker arm 52 in the axial direction.
2 is installed. That is, this clip 62 is located between both ends of the rocker shaft 44 and each cylinder.

The cylinder head 14 with the valve mechanism preassembled in this way is fixed to the cylinder block 12 with a plurality of head bolts 64 and 66. These head bolts 64
．． 66 is a hexagon socket bolt, which is attached to the cylinder head 1.
4 and between each cylinder. The head bolt 64 is screwed onto the cylinder head 14 by passing through a flange portion 14a that projects outward from the exhaust valve 34 side of the cylinder head 14. The head bolt 66 is attached to the camshaft 40 and the rocker shaft 44.
Located below between. In this embodiment, this bolt 6
6 interferes with the rocker shaft 44 when it is attached or detached, so a notch 44a shown in FIG. 2.5 is formed in the rocker shaft 44. Therefore, once the clip 62 is removed, the bolt 66 can be installed or removed using an Allen key driver.

In this embodiment, since the spark plug 32 is located between the exhaust valves 34, 34, the exhaust valves 34, 34 are separated from each other, and the cooling performance of the cylinder head 14 is improved. Also exhaust valve 3
The heat around squish area C is evenly transmitted to squish area C, which moderately warms the air-fuel mixture sandwiched therein, increases its combustion speed, and suppresses the occurrence of knocking due to abnormal combustion.

FIG. 7 is a diagram showing the valve arrangement of another embodiment, in which the ignition plug 3
Intake valves 36A and 36A are arranged with 2 in between. According to this embodiment, since the intake valves 36A and 36A are separated from each other, a decrease in intake efficiency due to interference between intakes in the combustion chamber is less likely to occur, and the diameter of the intake valve 36A is reasonably larger than that of the exhaust valve 34A. Can be set, cylinder 1
8 circular spaces can be used effectively.

(Effects of the Invention) As described above, the present invention arranges a pair of exhaust valves (or intake valves) with the spark plug near the center of the cylinder in between, and also places a camshaft near the plane containing these valves. Since a pair of intake valves (or exhaust valves) are arranged on one side of the plane, the rocker arm for opening and closing the pair of valves that sandwich the ignition plug does not interfere with the ignition plug attachment/removal hole, and these valves can be operated easily. The system can be laid out easily. It is also more compact than a double overhead camshaft type, and has the advantage of reducing the number of parts compared to a single overhead camshaft type in which multiple valves are opened and closed by rocker arms.

[Brief explanation of the drawing]

Fig. 1 is an overall schematic diagram of a V type 6-cylinder engine which is an embodiment of the present invention, Fig. 2 is a plan view showing the left punctured valve chamber, and Figs. III-III
FIG. 6 is a bottom view of the cylinder head to show the valve arrangement. Moreover, FIG. 7 is a diagram showing the valve arrangement of another embodiment. 18... Cylinder, 32... Spark plug, 34.34A... Exhaust valve, 36.36A... Intake valve, 40... Camshaft, 44... Rocker shaft, 52... Rocker arm , A... Cylinder center axis, B... Plane containing the exhaust valve, D... Plane containing the intake valve. Patent applicant Yamaha Motor Co., Ltd.

Claims (1)

[Claims] In a four-valve single overhead camshaft engine in which one camshaft opens and closes four intake and exhaust valves, the engine includes one spark plug disposed near the center axis of the cylinder, and the ignition plug disposed near the center axis of the cylinder. A pair of exhaust/intake valves are provided on both sides of the valve, and a pair of intake/exhaust valves are provided on one side of a plane including the pair of exhaust/intake valves, and the camshaft is connected to the intake valve. A 4-valve, 1-overhead camshaft engine, characterized in that the exhaust/intake valve is opened and closed by a pair of rocker arms held by a rocker shaft parallel to the camshaft, while the exhaust valve is disposed near a plane containing the exhaust valve. .