JP2767591B2 - One overhead camshaft engine - Google Patents

Description

The present invention relates to an overhead camshaft engine in which one camshaft opens and closes two intake valves and two exhaust valves per cylinder.

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.

In addition, there has been proposed an apparatus in which one cam shaft is used, and two intake (exhaust) air valves are directly opened and closed by the cam shaft, and the other two exhaust (intake) air valves are opened and closed via a rocker arm. .

However, in this case, since the valve that directly opens and closes the camshaft has a valve lifter, the cam that presses the rocker arm must be arranged away from the valve lifter so as not to interfere with the valve lifter. That is, when viewed from the sliding direction of the valve lifter, the cam for pressing the rocker arm must not overlap the diameter of the valve lifter. For this reason, the interval between the cams increases, the camshaft becomes longer, the degree of freedom in designing the camshaft bearing arrangement decreases,
There has been a problem that the shape of the rocker arm is complicated and rigidity is disadvantageous.

(Object of the Invention) The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a one-head camshaft type engine that has a shorter camshaft, increases the degree of freedom in designing the camshaft bearing arrangement, simplifies the shape of the rocker arm, and is also suitable for increasing its rigidity.

(Constitution of the Invention) According to the present invention, it is an object of the present invention to provide a camshaft parallel to a crankshaft and two intake / exhausts which are directly opened and closed with a valve lifter sandwiched between two cams formed on the camshaft. A valve, and two exhaust / intake valves opened and closed via a rocker arm by two cams formed on the outside of the two cams on the camshaft, and the camshaft directions of the two cams pressing the valve lifter are provided. In addition to the projection shape of the cam that presses the rocker arm, the cam shape that overlaps the diameter of the valve lifter is provided, and a camshaft bearing is disposed between the two cams that press the valve lifter. And
The rocker arm is formed in a linear shape substantially orthogonal to the cam shaft in plan view, and the interval between two exhaust / intake valves opened and closed by the rocker arm is opened and closed by the valve lifter.
This is achieved by a one-head camshaft engine characterized by having a greater spacing than the individual intake / exhaust valves.

(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. In this figure, the crankshaft 22 rotates counterclockwise. Each bank 10,10 has both banks 10,10
An intake pipe 28 arranged on the V-shaped valley side formed between them is 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.
When both camshafts 40 rotate counterclockwise in FIG. 1, the present invention is applied to the left bank. Therefore, the following description will be made using the cylinder head 14 of the left bank 10.
The cam shaft 40 in the left bank is counterclockwise, and the cam shaft 40 in the right bank
When the 40 rotates clockwise, it goes without saying that the present invention is applicable to the cam shafts of both banks.

The cylinder head 14 has cylinders 18 for three cylinders.
Are arranged in parallel with the crankshaft 22. Each cylinder has an ignition plug 32 disposed near the cylinder center axis A, and two exhaust valves 34, 34 disposed in parallel with the crankshaft 22 with the ignition plug 32 interposed therebetween. And V with respect to a plane B (FIG. 4) including these exhaust valves 34, 34.
A pair of intake valves 36, 36 disposed on the valley side of the mold.
For this reason, the combustion chamber 38 has a crankshaft as shown in FIGS.
Bathtub type long in 22 directions, intake valve across plane B
A squish area C having a large area is formed on the opposite side of 36. The 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 36,
A plane D (FIG. 4) including 36 is greatly inclined toward the V-shaped valley with respect to the cylinder center axis A, and a V-shaped is formed by both 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.

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. 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 being held between the cylinder head 14 and the cap 46 above the center of each cylinder. 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, and one ends of these rocker arms 52 are slidably contacted with the exhaust side cams 40b, 40b located outside the intake side cams 40a, 40a of the cam shaft 40. The other end contacts the upper ends of the exhaust valves 34, 34. The shape of the exhaust-side cam 40b is determined so as to fall within the projected shape of the intake-side cam 40a in the direction of the cam shaft 40. For example, when both cams 40a and 40b are installed in the same phase, the camshaft 40 is rotated counterclockwise in FIG. 4, and the plane E including the center of the camshaft 40 and the sliding contact of the rocker arm 52 is a plane D. Is set to about 120 °. The two cams 40a and 40b are close to each other as shown in FIG. 2, and are located so as to overlap the diameter of the valve lifter 42.

The rocker arms 52, 52 are clearly shown in FIG.
It is formed in a straight line substantially perpendicular to the cam shaft 40 in plan view. For this reason, the shape of the rocker arms 52, 52 can be made simple and advantageous in rigidity. Here rocker arm 5
Since 2 and 52 are straight lines almost perpendicular to the camshaft 40,
The interval between the two exhaust valves 34, 34 is wider than the interval between the two intake valves 36, 36, and a space is formed between the two rocker arms 52, 52 to dispose an ignition plug 32 and the like as described later herein. Becomes possible.

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 gap 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 fitting hole on the head cover 16 side and the inner peripheral surface 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 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.

As for the right bank, if the cam shaft 40 is rotated clockwise, the present invention can be applied as it is as described above. However, when the cam shaft 40 is rotated counterclockwise, the present invention is applied to the right bank. Instead, a conventional structure can be used.

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.

In addition, the present invention is applicable to and encompasses not only a V-type engine but also an in-line multi-cylinder engine.

(Effect of the Invention) As described above, the present invention is configured such that the cam that presses the rocker arm is included in the projected shape of the cam that presses the valve lifter in the cam axis direction, and the two cams overlap the diameter of the valve lifter. Furthermore, since the camshaft bearing is disposed between the two cams that press the valve lifter, the cam that presses the valve lifter and the cam that presses the rocker arm located on both sides of the bearing can be brought closer to each other. It is possible to shorten the camshaft and increase the degree of freedom of the camshaft bearing arrangement. In particular, restrictions on the arrangement of the cams for the rocker arm are reduced, and the rocker arm can be formed in a straight line perpendicular to the cam axis in plan view. For this reason, the shape of the rocker arm can be simplified so as to be advantageous in terms of rigidity, and the space between the two exhaust / intake valves opened and closed by the rocker arm is widened to increase the accommodation space such as the ignition plug between the two rocker arms. It becomes possible to secure.

[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. 14 ... cylinder head, 16 ... head cover, 32 ... spark plug, 34, 34A ... exhaust valve, 36, 36A ... intake valve, 40, 140 ... camshaft, 40a, 40b, 140a ... cam, 42: Valve lifter, 44: Rocker shaft, 46: Cap forming camshaft bearing, 52: Rocker arm.

Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01L 1/26

Claims (1)

(57) [Claims] 1. A camshaft parallel to a crankshaft, two intake / exhaust valves directly opened and closed with a valve lifter sandwiched between two cams formed on the camshaft, and two camshafts connected to the camshaft. And two exhaust / intake valves that are opened and closed via rocker arms by two cams formed outside the two cams.
The projection shape of the two cams pressing the valve lifter in the cam axis direction includes the projection shape of the cam pressing the rocker arm, and the two cams overlap the diameter of the valve lifter to press the valve lifter. A camshaft bearing is disposed between the two cams, the rocker arm is formed in a straight line substantially orthogonal to the camshaft in plan view, and the interval between two exhaust / intake valves opened and closed by these rocker arms is defined as described above. An overhead camshaft engine characterized in that the interval between two intake / exhaust valves opened and closed by a valve lifter is made wider.