JP2732077B2 - One overhead camshaft engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an overhead camshaft engine which opens and closes a plurality of intake valves and exhaust valves per cylinder with one camshaft.

BACKGROUND OF THE INVENTION A four-valve engine having two intake valves and two exhaust valves for each cylinder is known. In this case, conventionally, two camshafts are arranged in parallel on both sides with respect to the center of the cylinder, and each camshaft directly opens and closes two intake valves and two exhaust valves. (DOHC). However, in this case, there is a problem that the engine becomes large.

There has also been proposed a single camshaft that directly opens and closes two intake (exhaust) air valves with the camshaft and opens and closes the other two exhaust (suction) air valves via a rocker arm. .
However, in this case as well, the conventional camshaft increases the size of the engine in the direction of the center axis of the cylinder, which also increases the size of the engine. In particular, when the ignition plug is disposed near the center of the combustion chamber, the camshaft must be located at a higher position, and the size of the engine is further increased. Therefore, it is conceivable to divide the rocker shaft that interferes with the ignition plug attaching / detaching hole. However, there is a problem that the configuration becomes complicated.

(Object of the Invention) The present invention has been made in view of such circumstances, and it is possible to reduce the size in the cylinder central axis direction when the engine is downsized while positioning the ignition plug near the center of the combustion chamber. It is another object of the present invention to provide an overhead camshaft engine that does not need to split a rocker shaft.

(Constitution of the Invention) According to the present invention, it is an object of the present invention to provide an overhead camshaft engine having a plurality of intake valves and exhaust valves, each of which is opened and closed by a single camshaft. Two exhaust valves or intake valves arranged on a first plane, a plurality of intake valves or exhaust valves arranged on a second plane that is greatly inclined with respect to the cylinder center axis, and a split surface between a cylinder head and a head cover. A camshaft held between them for directly driving an intake or exhaust valve on the second plane, a rocker arm for opening and closing the exhaust or intake valve on the first plane, and two exhausts on the first plane. One ignition plug facing the center of the cylinder between the valves or the intake valves, wherein a mounting hole for the ignition plug is disposed between the two exhaust valves or the intake valves on the first plane, and the rocker arm Holding rocker shaft Is held between the split surfaces so as to be parallel to the camshaft between the mounting hole of the spark plug and the camshaft.

Here, the split surface between the cylinder head that holds the rocker shaft and the cam shaft and the head cover can be parallel to the split surface between the cylinder and the cylinder head.

(Embodiment) FIG. 1 is an overall schematic view of a V-type six-cylinder engine according to one 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 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 by connecting rods 26, 26 to crank pins 24a, 24b having a phase difference of 30 ° of the crankshaft 22, respectively. ing. Each bank 10, 10 has both banks 1
Intake pipe 2 arranged on the V-shaped valley side formed between 0 and 10
8 are connected, 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, each cylinder is provided with a spark plug 32 disposed near the cylinder center axis A, and two exhaust valves provided side by side with the spark plug 32 in the longitudinal direction of the crankshaft 22. Three
4 and 34, and a pair of intake valves 3 disposed on the V-shaped valley side with the first plane B (FIG. 4) including these exhaust valves 34 and 34 interposed therebetween.
Prepare with 6, 36. For this reason, the combustion chamber 38 becomes a bathtub type long in the direction of the crankshaft 22 as shown in FIGS.
A large area squish area C is formed on the opposite side of the intake valve 36 across the plane B.

The first plane B including the two exhaust valves 34, 34 is substantially parallel to and close to the cylinder center axis A, and the two intake valves 3
The second plane D including FIG.
Is greatly inclined toward the valley side of the V-shape, and a V-shape is formed by the same planes B and D.

A valve gear for opening and closing the exhaust valve 34 and the intake valve 36 includes:
It is housed in a valve chamber formed between the cylinder head 14 and the head cover 16.

Reference numeral 40 denotes one cam shaft parallel to the crankshaft 22, the center of which is on the second plane D including the intake valves 36, 36, and directly presses the valve lifters 42, 42 of the intake valves 36, 36. Intake valve 3
6, 36 open and close in phase. Reference numeral 44 denotes a rocker shaft located on both planes B and D and parallel to the cam shaft 40. The head cover 16
The split surface between the cylinder head 14 and the cylinder head 14 is parallel to the split surface between the cylinder head 14 and the cylinder block 12.
40 and rocker shaft 44 are head cover 16 and cylinder head 14
It is located on the split plane with Both ends of the cam shaft 40 and the rocker shaft 44 are held between the split surfaces of the cylinder head 14 and the head cover 16, while the cylinder head 14 is located above the center of each cylinder.
And the cap 46. 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, which is disposed between the two exhaust valves 34 on the first plane B. The attachment / detachment hole 54 is formed by pressing the lower end of the metal pipe into the cylinder head 14 and holding the upper end by the head cover 16.
The plug cord is connected to the ignition plug 32 by inserting the plug cap 56 into the opening formed in the plug. 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 operating 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 clips 62 are located between both ends of the rocker shaft 44 and each cylinder.

The cylinder head 14 with the valve mechanism pre-assembled is fixed to the cylinder block 12 by a plurality of head bolts 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 cylinder head
The screw 14 is screwed to the cylinder head 14 through a flange portion 14a protruding outside the exhaust valve 34 side. 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 or detached, so the notch 44a shown in FIGS.
Is formed. Therefore, if clip 62 is removed, bolt 66
Can be attached and detached using an Allen key driver.

In this embodiment, since the ignition plug 32 is located between the exhaust valves 34, 34, the exhaust valves 34, 34 are separated from each other, so that 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.

FIG. 8 is a plan view of a cylinder head according to still another embodiment, and FIG. 9 is a sectional view taken along line IX-IX. In this embodiment, a cap 46A holding the camshaft 40A and the rocker shaft 44A is integrally formed with an ignition plug attaching / detaching hole 54A, and this attaching / detaching hole 54A is communicated with an ignition plug attaching / detaching hole 54B formed on the cylinder head 14A side.
It is fixed by three bolts 70a, 70b, 70c. An O-ring 72 is held between the cap 46A and the cylinder head 12A, and a rubber seal 74 is held between the cap 46A and the head cover 16A.

According to this embodiment, the number of parts is reduced,
The sealing properties of 54A and B are improved.

(Effect of the Invention) As described above, according to the present invention, a plurality of intake valves (or exhaust valves) and camshafts are arranged on the second plane (D) which is greatly inclined with respect to the cylinder center axis. Since two exhaust valves (or intake valves) are arranged on the first plane (B) close to the cylinder and opened and closed by the camshaft via a rocker arm, the dimension in the cylinder central axis direction can be reduced. The engine can be downsized. Further, since the spark plug attaching / detaching hole is disposed between the two exhaust valves or the intake valves on the first plane (B), the spark plug attaching / detaching hole does not interfere with the cam shaft, and the rocker shaft has the cam shaft. Because the diameter is smaller, it can be easily placed between the camshaft and the spark plug attachment / detachment hole parallel to the camshaft, and the camshaft can be closer to the combustion chamber without dividing the rocker shaft, making it possible to further reduce the size of the engine. It is.

If the split surface of the cylinder head holding the rocker shaft and the cam shaft and the head cover is made parallel to the split surface of the cylinder and the cylinder head, not only these machining operations become simple, but also the rocker shaft The engine can be further reduced in size by being brought closer to the combustion chamber.

[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, FIG. 8 is a plan view of a cylinder head of still another embodiment, and FIG. 9 is a sectional view taken along line IX-IX of the cylinder head. 14, 14A: Cylinder head, 16, 16A: Head cover, 32: Spark plug, 34, 34A: Exhaust valve, 36, 36A: Intake valve, 40, 40A: Cam shaft, 44, 44A Rocker shaft, 52: Rocker arm, A: Central axis of cylinder, B: Plane almost parallel to central axis of cylinder, D: Largely inclined plane.

Claims (2)

(57) [Claims] 1. An overhead camshaft type engine having a plurality of intake valves and exhaust valves, each of which is opened and closed by a single camshaft, wherein the engine is disposed on a first plane close to a cylinder center axis. A plurality of exhaust valves or intake valves, a plurality of intake valves or exhaust valves disposed on a second plane that is greatly inclined with respect to the cylinder center axis, and a plurality of intake valves or exhaust valves that are held between the split surfaces of the cylinder head and the head cover. A cam shaft for directly driving an intake valve or an exhaust valve, a rocker arm for opening and closing the exhaust valve or the intake valve on the first plane, and a cylinder center between the two exhaust valves or the intake valves on the first plane. One ignition plug facing the vicinity, a mounting hole for the ignition plug is disposed between two exhaust valves or intake valves on the first plane, and a rocker shaft holding the rocker arm is connected to the ignition plug. Stopper hole and cam An overhead camshaft type engine, wherein the engine is held between the split surfaces so as to be parallel to the camshaft with respect to the shaft. 2. The one-headed camshaft engine according to claim 1, wherein the split surface between the cylinder head and the head cover is parallel to the split surface between the cylinder and the cylinder head.