JP2001073723A - Valve system of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide valve system excellent in valve following and durability without need of adjustment of valve clearance, which drives fuel jetting valves positioned at center of each cylinder, each two valves for intake and exhaust put on either side of each cylinder along its line by single camshaft. SOLUTION: This device has two rocker shafts 91, 92 perpendicularly against cylinder lines offsetting from directly above cylinder 4 to same direction as camshaft 8. First rocker arm 101 in contact with first valve 61 nearer to camshaft 8 is supported to first rocker shaft 91 further from cylinder 4. Further, second rocker arm 102 in contact with second valve 62 further from camshaft 8 is supported to second rocker shaft 92 nearer to cylinder 4. Then, hydraulic tappet 12 is fitted to the end of valve of each rocker arm 101, 102.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve train for an internal combustion engine mainly composed of a diesel engine.

[0002]

2. Description of the Related Art Conventionally, as a diesel engine, a cylinder head is provided with a fuel injection valve located at the center of each cylinder and two cylinders located at one side of each cylinder in the cylinder row direction and arranged in a direction orthogonal to the cylinder row direction. And two exhaust valves which are located on the opposite side of each cylinder in the cylinder row direction and are arranged in a direction orthogonal to the cylinder row direction.

[0003] When the valve train of such a diesel engine is configured as a single overhead cam (SOHC) type, conventionally, an intake crosshead straddling two intake valves of each cylinder and an exhaust crosshead straddling two exhaust valves. In addition to providing a crosshead, an intake rocker arm that abuts the intake crosshead and an exhaust rocker arm that abuts the exhaust crosshead are provided. Two intake valves and two exhausts for each cylinder are provided by a single camshaft that is arranged offset in the orthogonal direction, through each rocker arm for intake and exhaust, and each crosshead for intake and exhaust. And a valve (see Japanese Patent Laid-Open No. 8-2).
No. 70412).

[0004]

It is difficult to incorporate a hydraulic tappet in a valve gear using a crosshead as in the above-mentioned prior art, and it is necessary to adjust the valve clearance with an adjusting screw attached to the crosshead. become.

This clearance adjustment is performed by removing the head cover. However, if the fuel pipe remains connected to the fuel injection valve, the fuel pipe hinders the removal of the head cover. Therefore, the fuel pipe is removed, and then the head cover is removed. Is required, and as a result, a trouble may occur due to invasion of foreign matter into the fuel pipe.

[0006] In view of the above, it is an object of the present invention to provide a maintenance-free valve train that does not require adjustment of valve clearance.

[0007]

Means for Solving the Problems In order to solve the above problems,
The present invention provides a fuel injection valve positioned at the center of each cylinder in a cylinder head, and two intake valves positioned on one side of each cylinder in the cylinder row direction and arranged in a direction orthogonal to the cylinder row direction. A valve train for an internal combustion engine, comprising two exhaust valves located on the opposite side of the cylinder row direction and arranged in the direction perpendicular to the cylinder row direction, the valve train being arranged in a direction perpendicular to the cylinder row direction from immediately above the cylinders. In a configuration in which the intake valve and the exhaust valve are driven by a single camshaft arranged to be offset, the camshaft is offset from a portion immediately above the cylinder in the same direction as the camshaft offset direction by a cylinder head. Two rocker shafts located below the shafts are arranged side by side in the direction perpendicular to the cylinder row direction, and each of the two rocker shafts is placed on a first rocker shaft farther from the cylinder than the other. A pair of first and second intake valves for driving the first intake valve and the first exhaust valve closer to the camshaft among the two intake valves and the two exhaust valves in conjunction with the camshaft, respectively. A pair of intake and exhaust valves for driving a rocker arm and a second rocker shaft closer to the cylinder to a second rocker shaft closer to the cylinder and a second intake valve and a second exhaust valve farther from the camshaft in conjunction with the camshaft, respectively. Two rocker arms are supported, a hydraulic tappet is assembled at the valve contact end of each of the rocker arms, and the first rocker shaft is disposed above the second rocker shaft.

According to the present invention, each intake valve and each exhaust valve are driven via separate rocker arms. Then, the valve clearance is automatically adjusted to be zero by the hydraulic tappet attached to the valve contact end of each rocker arm, and the clearance adjustment by removing the head cover becomes unnecessary.

Here, it is conceivable to support the first rocker arm and the second rocker arm on a common rocker shaft. However, in this case, the second rocker arm for driving the intake / exhaust valve farther from the camshaft is large. Shape,
For this reason, the valve follow-up performance at high rotation is deteriorated,
The cam surface pressure becomes excessive and the durability decreases. On the other hand, in the present invention, the first rocker arm for driving the intake / exhaust valve on the side closer to the camshaft is connected to the first rocker arm on the side farther from the cylinder.
Since the second rocker arm that is supported by the rocker shaft and drives the intake / exhaust valve farther from the camshaft is supported by the second rocker shaft closer to the cylinder,
The second rocker arm and the second rocker arm can both be appropriately sized, and the above-described problem does not occur.

In addition, since the first rocker arm extends beyond the portion where the second rocker shaft is disposed, it is necessary to prevent the first rocker arm from interfering with the second rocker shaft. In this case, it is conceivable to secure the clearance between the first rocker arm and the second rocker shaft by reducing the width of the first rocker arm in the vertical direction. However, the rigidity of the first rocker arm cannot be secured. On the other hand, when the first rocker shaft is disposed above the second rocker shaft as in the present invention, the clearance between the first rocker shaft and the second rocker shaft can be increased without reducing the vertical width of the first rocker arm. As a result, the first rocker arm does not have insufficient rigidity.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, reference numeral 1 denotes a cylinder block of a diesel engine, 2 denotes a cylinder head, 3
Indicates a head cover.

As shown in FIG. 2, the cylinder head 2 has
The fuel injection valve 5 is located at the center of each cylinder 4 and
4 is positioned on one side in the cylinder row direction (X direction in FIG. 2).
Two intake bars arranged in a row direction and a direction orthogonal to the row direction (Y direction in FIG. 2)
Lube 6₁, 6_TwoAre located on the opposite side of each cylinder 4 in the cylinder row direction.
Two exhaust valves arranged in the direction perpendicular to the cylinder row
7 ₁, 7_TwoAre provided. In the figure, 6a and 7a are each intake air.
Valve 6₁, 6_TwoAnd each exhaust valve 7₁, 7_TwoAttached to the upper end of
It is a girder spring retainer.

The fuel injection valve 5 is inserted through a head cover 3 into a guide cylinder 5a erected on the cylinder head 2, and
Cylinder head 2 at the lower nozzle portion (not shown)
The fuel pipe 5c is connected to an upper part of the fuel injection valve 5 exposed on the head cover 3 by being screwed into a mounting hole 5b facing the center of each cylinder 4 formed in the above.

The cylinder head 2 is further provided with a single camshaft 8 offset from a position directly above the cylinder 4 in a direction orthogonal to the cylinder row direction, and from a position directly above the cylinder 4 in the same direction as the camshaft offset direction. Offset and aligned in a direction orthogonal to the cylinder row direction below the camshaft 8 2
The rocker shafts 9 ₁ and 9 ₂ are arranged.

[0015] Then, both the rocker shaft 9 _1, 9 to the first rocker shaft 9 ₁ remote from the cylinders 4 of _2, two intake valves 6 ₁ of each cylinder 4, 6 ₂ and two exhaust valves 7 _1, 7 first rocker arm 11 for the exhaust from the first rocker arm 10 ₁ for intake respectively abut against the first intake valve 6 ₁ side and the ₁ first exhaust valve 7 is close to the cam shaft 8 of _{2 1} second rocker arm for the intake of preparative is supported, respectively abut against the second rocker shaft 9 _second side to the second intake valve 6 ₂ remote from the cam shaft 8 and ₂ second exhaust valve 7 is close to cylinder 4 10 ₂ and the second is made to support the rocker arm 11 ₂ for exhaust.

Each rocker arm 10 ₁ , 10 ₂ , 11 ₁ ,
11 The _second abutting roller 10a in each cam 8a formed on the cam shaft 8, and 11a are mounted, the rocker arm 10 ₁ by the cams 8a, 10 _2, 11 _1,
11 ₂ the intake valves 6 ₁ through 6 ₂ and the exhaust valves 7 _1, 7 ₂ is driven.

Further, each rocker arm 10 ₁ , 10 ₂ , 1
The 1 _1, 11 ₂ of the valve abutment end, the hydraulic tappet 12 is mounted as shown in FIG. The hydraulic tappet 12
Slidably-ah 12a and inner 12a and an extrapolated outer 12b, the rocker arm 10 ₁ to 1
1 ₂ tappet mounting hole 10b which downwardly opening formed in the valve abutment end, to 11b, and the hydraulic tappet 12 by inserting the outer 12b in the bottom, outer 12b each intake valve 6 _1, 6 ₂ and each exhaust valve It is into contact with the upper end of the 7 _1, 7 _2. The hydraulic tappet 12 further each rocker shaft 9 _1, 9 oil hole 10c formed in the rocker arm 10 ₁ to 11 ₂ to the lubricating oil passage 9a formed in the _second shaft hole, 1
An oil chamber 12c in the inner 12a, which communicates via the
The oil chamber 12c is provided with an oil chamber 12e between the inner 12a and the outer 12b which communicates via a valve hole 12d at the lower end of the inner 12a.
A spring 12f that urges b downward and a check valve 12g that closes the valve hole 12d are housed. In addition, each rocker arm 10 ₁ to 11 _2, oil from the lubricating oil passage 9a of the tappet mounting hole 10b, the outer insertion portion of the upper end portion to supply oil hole 10d of 11b, 11d are formed. Thus, when the valve is closed, the outer 12b is pushed downward by the urging force of the spring 12f and the oil pressure from the oil holes 10d and 11d to be seated on the upper end of the valve, and the valve clearance becomes zero. At this time, the oil chamber 12e is connected to the oil chamber 12 through the valve hole 12d.
However, when the valve is opened, the check valve 12g is closed due to an increase in the internal pressure of the oil chamber 12e due to an upward reaction force acting on the outer 12b, and the oil is sealed in the oil chamber 12e and the outer chamber 12b is closed. The upward movement is prevented, and the driving force from the camshaft 8 is reliably transmitted to the intake / exhaust valves 6 ₁ , 6 ₂ , 7 ₁ , 7 ₂ . In this way each rocker arm 10 ₁ ~
11 ₂ By attaching the hydraulic tappets 12, valve clearance is automatically zeroing clearance adjustment to remove the head cover 3 is unnecessary.

[0018] It should be noted that, in each of the rocker arm 10 ₁ to 11 _2,
Nozzle holes 10e, 11e for discharging the oil in the oil holes 10c, 11c toward the rollers 10a, 11a are formed, and a sliding contact surface between the inner 12a and the outer 12b is formed on the inner 12a of the hydraulic tappet 12. Oil hole 12 for lubricating
h is formed.

The second rocker arms 10 ₂ , 11 ₂ for intake and exhaust are bent in the cylinder row direction in order to avoid interference with the first rocker arms 10 ₁ , 11 ₁ for intake and exhaust. It is formed on, so that the second rocker arm 10 _2, 11 ₂ acts torsional moment. Therefore, it is not possible to adopt an end pivot type as the second rocker arm 10 _2, 11 ₂ of the support system, it is necessary to support in a shaft system by the rocker shaft. In this case, the second omitted rocker shaft 9 _2, the first rocker arm to the first rocker shaft 9 ₁ 1
0 _1, 11 ₁ and the second rocker arm 10 _2, 11 ₂ and the it is conceivable to be supported, this is the second rocker arm 10 _2, 11 ₂ are large in size, poor valve followability at the time of high rotation At the same time, the cam surface pressure becomes excessive and the durability is reduced. Therefore, in this embodiment, the second rocker arm in a position close to the first cylinder 4 than the rocker shaft 9 ₁ 1
0 _2, 11 ₂ of the second place the rocker shaft 9 ₂ supporting, so that does not cause the above problem.

[0020] However, when the second placing rocker shaft 9 _2, the first rocker arm to said shaft 9 ₂ 1
A problem of interference of 0 ₁ and 11 ₁ occurs. In this case, by reducing the vertical width of the portion located on the first rocker arm 10 _1, 11 ₁ of the second rocker shaft 9 ₂ on the first rocker arm 10 _1, 11 ₁ and the second rocker shaft 9 ₂ It is conceivable to secure clearance, but this is the first
The rigidity of the rocker arms 10 ₁ and 11 ₁ is reduced. Therefore, in this embodiment, the first rocker shaft 9 ₁ second
And disposed above the rocker shaft 9 _2, without reducing the first rocker arm 10 _1, 11 ₁ of the vertical width, the first rocker arm 10 _1, 11 ₁ and the second rocker shaft 9 ₂
To ensure clearance.

In FIG. 1, 13 ₁ and 13 ₂ are first and second intake ports connected to the first and _second intake valves 6 ₁ and 6 ₂ , respectively.
14 is both the first and second exhaust valves 7 _1, 7 an exhaust port leading to _2.

[0022]

As is apparent from the above description, according to the present invention, it is not necessary to adjust the valve clearance by removing the head cover.
A valve train excellent in valve followability and durability can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a main part of a diesel engine showing an example of the present invention.

FIG. 2 is an enlarged plan view of a part of a cylinder head in a state where a camshaft is removed.

FIG. 3 is an enlarged vertical sectional view of a valve contact end of a rocker arm.

[Explanation of symbols]

2 Cylinder head 5 Fuel injection valve 6 ₁ First intake valve 6 ₂ Second intake valve 7 ₁ First exhaust valve 7 ₂ Second exhaust valve 8 Camshaft 9 ₁ First rocker shaft 9 ₂ Second rocker shaft 10 _{1 For} intake 1st rocker arm 10 ₂ Second rocker arm 11 for intake 11 _1st exhaust
Rocker arm 11 ₂ Second rocker arm for exhaust 12 Hydraulic tappet

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) F02F 1/24 F02F 1/24 FR J (72) Inventor Dai Dai Asari 1-4-4 Chuo, Wako-shi, Saitama No. 1 F-term in Honda R & D Co., Ltd. (reference) 3G016 AA07 AA19 BA03 BA06 BA27 BB12 BB22 BB29 BB38 CA47 CA57 GA00 3G024 AA04 AA18 DA06 DA09 DA17

Claims (1)

[Claims] 1. A fuel injection valve located at a center of each cylinder in a cylinder head, and two intake valves located at one side of each cylinder in a cylinder row direction and arranged in a direction orthogonal to the cylinder row direction, What is claimed is: 1. A valve train for an internal combustion engine, comprising: two exhaust valves located on the opposite side of a cylinder in the cylinder row direction and arranged in a direction perpendicular to the cylinder row direction, the valve train comprising: A single camshaft arranged offset to drive these intake and exhaust valves.The cylinder head is offset from the top of the cylinder in the same direction as the offset direction of the camshaft. Two rocker shafts located below the camshaft are arranged side by side in the direction perpendicular to the cylinder row direction, and the first rocker shaft of the two rocker shafts that is farther from the cylinder is Of the two intake valves and two exhaust valves of each cylinder, a first intake valve and a first exhaust valve closer to the camshaft are driven in association with the camshaft, respectively. A first rocker arm and a second rocker shaft closer to the cylinder, and a pair of intake and exhaust for driving a second intake valve and a second exhaust valve farther from the camshaft in conjunction with the camshaft, respectively. And a hydraulic tappet is incorporated at a valve contact end of each of the rocker arms, and the first rocker shaft is disposed above the second rocker shaft. Valve train.