JP2732076B2 - Multi-valve engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an engine having a plurality of intake valves and a plurality of exhaust valves.

BACKGROUND OF THE INVENTION A multi-valve engine having a plurality of intake valves and a plurality of exhaust valves for each cylinder is known. When a large number of intake / exhaust valves are provided in this manner, head portions of the large number of intake / exhaust valves appear on the surface on the cylinder head side facing the piston top surface. For this reason, it has been difficult to secure a squish area, that is, a sufficiently large area sandwiching the interval between the piston top surface and the cylinder head. As a result, there is a problem that improvement in combustion is limited.

(Effects of the Invention) The present invention has been made in view of such circumstances, and when a plurality of intake valves and exhaust valves are provided, it is possible to secure a sufficiently wide squish area and improve combustion. It is an object to provide a simple multi-valve engine.

According to the present invention, an object of the present invention is to provide an overhead camshaft engine having a plurality of intake valves and exhaust valves each opened and closed by a camshaft. A substantially V-shape is formed by a second plane that is greatly inclined with respect to the center axis, and two intake valves or exhaust valves are formed on the first plane such that their heads overlap the cylinder center axis when viewed from the cam shaft longitudinal direction. A plurality of exhaust valves or intake valves disposed on a second plane, and a spark plug disposed near the center of the cylinder between the two intake valves or exhaust valves on the first plane. A squish area having an interval between a piston top surface and a cylinder head is formed on the opposite side of the second plane with respect to the first plane.

(Embodiment) FIG. 1 is an overall schematic view of a V-type six-cylinder engine according to an embodiment of the present invention, FIG. 2 is a plan view showing a valve operating chamber of the left bank, and FIGS. III-III line, IV in FIG.
FIG. 6 is a bottom view of the cylinder head for illustrating a valve arrangement, taken along a line IV-V and a line VV.

In FIG. 1, the engine is a pair of banks 1 forming a substantially V-shape.
Each bank 10 has a cylinder head 14 and a head cover 16 attached to a cylinder block 12 having a substantially pentagonal shape in front view. Cylinders 18, 18 in both banks 10, 10
The pistons 20, 20 of the cylinders in each bank 10, 10, which are paired with each other, are connected to crank pins 24a, 24b having a phase difference of 30 ° of the crankshaft by connecting rods 26, 26, respectively. I have. Each bank 10, 10 has both banks 10,
An intake pipe 28 is connected to the V-shaped valley formed between the intake pipes 10, and the exhaust pipes 30, 30 are connected to the outer surfaces of the banks 10, 10, respectively. 31 is an oil pan.

Next, the cylinder head 14 will be described. However, since the cylinder head 14 is symmetric, the cylinder head 14 of the left bank 10 will be described.

The cylinder head 14 has cylinders 18 for three cylinders.
Are arranged side by side in parallel with the crankshaft 22, and each cylinder has an ignition plug 32 disposed near the cylinder center axis A and two exhaust pipes arranged in the longitudinal direction of the crankshaft 22 with the ignition plug 32 interposed therebetween. valve
34, and a pair of intake valves 3 arranged on the V-shaped valley side with the first plane B (FIG. 4) including these exhaust valves 34, 34 interposed therebetween.
6 and 36 are provided. For this reason, the combustion chamber 38 has a bathtub shape long in the direction of the crankshaft 22 as shown in FIGS. 3 and 6, and a large-area squish area C is formed on the opposite side of the intake valve 36 across the first plane B.

A first plane B including the two exhaust valves 34, 34 is substantially parallel to and close to the cylinder center axis A. That is, the exhaust valves 34, 34 are close to the first plane so that their heads overlap the cylinder center axis when viewed from the longitudinal direction of the cam shaft 40 described later. A second plane D including two intake valves 36, 36;
(FIG. 4) is greatly 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 planes B and D.

Numeral 40 denotes a single camshaft parallel to the crankshaft 22, the center of which is on a plane D including the intake valves 36, 36, and
Directly press the valve lifters 42, 42 of 6, 36 to make the intake valves 36, 3
6 opens and closes in phase. A rocker shaft 44 is located between the planes B and D and parallel to the cam shaft 40. The split surface between the head cover 16 and the cylinder head 14 is parallel to the split surface between the cylinder head 14 and the cylinder block 12, and the camshaft 40
And the rocker shaft 44 are located on a split surface between the head cover 16 and the cylinder head 14. The cam shaft 40 is held between the cylinder head 14 and the cap 46 above the center of each cylinder, while both ends of the rocker shaft 44 are held between the split surfaces of the cylinder head 14 and the head cover 16. This cap 46
Is a pair of bolts 48, 48 sandwiching the cam shaft 40, and a rocker shaft 44.
And is fixed to the cylinder head 14 by a bolt 50 penetrating through. A pair of rocker arms 52, 52 are held on the rocker shaft 44 with a cap 46 interposed therebetween. Sliding contact, the other end is exhaust valve 34, 34
Abuts the top of The camshaft 40 rotates clockwise in FIG.

Reference numeral 54 denotes a mounting 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 held by the head cover 16, and a plug cap 56 is inserted into an opening formed in the head cover 16. A plug cord is connected to spark plug 32. An O-ring is attached to the outer periphery of the upper end of the attachment / detachment hole 54, and the O-ring is in close contact with the inner peripheral surface of the fitting hole on the head cover 16 side to ensure liquid tightness of the valve chamber. Numeral 58 denotes an electromagnetic fuel injection valve, which injects gasoline fuel in a vicinity of a branch to each of the intake valves 36, 36 in an intake passage 60 connected to the intake valve 36. A clip 62 made of metal or resin is mounted on the rocker shaft 44 to restrict the movement of the rocker arm 52 in the axial direction. That is, the clip 62 is located between both ends of the rocker shaft 44 and each cylinder.

The cylinder head 14 with the valve mechanism pre-assembled in this way is fixed to the cylinder block 12 by a plurality of head boats 64, 66. These head bolts 64 and 66 are hexagonal bolts and are located at both ends of the cylinder head 14 and between the cylinders. Head bolt 64 is for cylinder head 14
And is screwed to the cylinder head 14 through a flange portion 14a protruding outside the exhaust valve 34 side. The head bolt 66 is located below between the cam shaft 40 and the rocker shaft 44. In this embodiment, the bolt 66 interferes with the rocker shaft 44 when the bolt 66 is attached and detached. Therefore, a notch 44a shown in FIGS. Therefore, if the clip 62 is removed, the bolt 66 can be attached and detached 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. Further, the heat in the vicinity of the exhaust valve 34 is evenly transmitted to the squish area C, and the air-fuel mixture sandwiched therebetween is appropriately warmed to increase the combustion speed, thereby suppressing knocking due to abnormal combustion.

FIG. 7 is a view showing a valve arrangement of another embodiment,
The intake valves 36A, 36A are arranged with the 32 interposed therebetween. 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 the 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. It can be set and the circular space of the cylinder 18 can be used effectively.

(Effect of the Invention) As described above, the present invention arranges two intake valves or exhaust valves on the first plane close to the cylinder center axis A such that their heads overlap the cylinder center axis when viewed from the cam shaft longitudinal direction. And a plurality of exhaust valves or intake valves are disposed on a second plane that is greatly inclined with respect to the cylinder center axis.
Since the ignition plug is disposed near the center of the cylinder between the two intake valves or the exhaust valves, it is possible to form a sufficiently wide squish area on the opposite side of the second plane with respect to the first plane. Therefore, combustion can be improved by providing a wide squish area despite having a large number of intake and exhaust valves.

[Brief description of the drawings]

FIG. 1 is an overall schematic view of a V-type six-cylinder engine according to an embodiment of the present invention, FIG. 2 is a plan view showing a valve operating chamber in a left bank thereof, and FIGS. III-III line, IV-
FIG. 6 is a bottom view of the cylinder head for illustrating the valve arrangement. FIG. 7 is a view showing a valve arrangement of another embodiment. 18 ... cylinder, 32 ... spark plug, 34, 34A ... exhaust valve, 36, 36A ... intake valve, 44 ... rocker shaft, 52 ... rocker arm, A ... cylinder center axis, B ... cylinder center A first plane substantially parallel to the axis, D... A second plane greatly inclined.

Claims (1)

(57) [Claims] An overhead camshaft engine having a plurality of intake and exhaust valves each opened and closed by a camshaft, a first plane close to a cylinder center axis and a second plane inclined greatly with respect to the center axis. And a substantially V-shape is formed, and two intake valves or exhaust valves are disposed on the first plane such that their heads overlap the cylinder center axis when viewed from the longitudinal direction of the camshaft. A plurality of exhaust valves or intake valves are disposed on the first plane, and an ignition plug is disposed near the center of the cylinder between the two intake valves or exhaust valves on the first plane, and the first plane is interposed therebetween. A valve train for an engine, wherein a squish area is formed on the opposite side of the second plane with a gap between a piston top surface and a cylinder head.