JP2815063B2 - Valve train for V-type engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve train for a V-type engine, and more particularly to an improvement in the structure of a valve train capable of narrowing an engine width.

[Related Art] A V-type engine has a configuration in which a plurality of cylinders are formed in a cylinder block in a left and right V-shape, and a cylinder head and a head cover are stacked on the cylinder block. Compactness of the engine width (dimension in the direction perpendicular to the crankshaft) and the like is required. To lower the engine height, the V-shaped bank angle is set to, for example, 90.
Although it is effective to increase the size as much as possible, there is a problem that the width of the engine is increased. In particular, when a DOHC type valve train is provided, in which the intake valve and the exhaust valve are arranged inside and outside the V bank with the cylinder axis interposed therebetween and are directly driven by separate camshafts, the outer cam is used. The width of the engine is increased by the amount that the shaft protrudes outward.

Therefore, in order to reduce the engine width, for example, an OHC type valve train in which the outer camshaft is eliminated and the outer valve is opened and closed by the inner camshaft is advantageous. An engine equipped with such a valve train is disclosed, for example, in JP-A-63-18 / 1988.
As described in Japanese Patent Publication No. 107, in an engine in which cylinders are arranged in series, an intake valve is driven directly by a camshaft, and an exhaust valve is driven via a rocker arm driven by the camshaft. There is.

[Problems to be solved by the invention]

However, the valve gear described in the above publication is intended for an in-line engine. Even if this is used for a V-type engine as it is, the rocker arm protrudes outward, so that it is not so effective in narrowing the engine width. Absent.

On the other hand, as an attempt to narrow the engine width for a V-type engine, for example, as described in JP-A-60-13906, the valve opening force from a camshaft arranged inside the bank is reduced. Some of the components are transmitted to an outer valve via a cam follower, a push rod, and a rocker arm. However, there is a problem that the number of parts increases and the structure becomes complicated.

The present invention has been made in view of the above conventional problems,
It is an object of the present invention to provide a valve train for a V-type engine that can have a narrow engine width with a simple structure.

[Means for solving the problem]

The present invention relates to a valve train for a V-type engine in which a cylinder head and a head cover are stacked on each cylinder of a cylinder block formed such that the cylinders form a V-bank space. Two intake valves and two exhaust valves are arranged on the outside, and the mating surface between the cylinder head and the head cover is inclined so that the outside of the V bank is lower than a plane perpendicular to the cylinder axis, V above the cylinder axis of the mating surface
A rocker shaft is arranged inside the bank and a cam shaft is arranged further inside than the rocker shaft, and the left and right intake valves are driven by the left and right intake cams of the cam shaft via the left and right lifters. The left and right exhaust cams disposed outside the left and right intake cams, the left and right exhaust cams are supported by the rocker shaft.
The left and right exhaust valves are driven via the right rocker arm, the portion between the left and right intake cams of the cam shaft is supported by cam bearings, and the rocker shaft is moved left and right near the cylinder axis. A spark plug insertion hole is formed between the divided left and right rocker shafts, the left and right rocker arms are disposed between the left and right of the ignition plug insertion hole, and the cylinder head is positioned on the cylinder block side. When the head bolts inside the V-bank among the head bolts fixed to the cylinder are viewed in the cylinder axis direction, they are arranged between the rocker shaft and the cam shaft.

Here, in the present invention, the mating surface is inclined to reduce the width of the engine as will be described later. In view of this purpose, the inclination is steeper, and the closer to vertical, the more effective the rocker arm is. Is naturally limited by the required length of the arm, the angle between the arm and the valve, and so on, so that it is appropriately set from these viewpoints.

[Action]

In the valve gear of the V-type engine according to the present invention, the mating surface of the cylinder head and the head cover is inclined so that the outside of the bank is lower than a plane perpendicular to the cylinder axis, and the rocker shaft is arranged on the mating surface. The rocker arm becomes substantially upright, and the amount of outward bulging of the head cover is reduced, and the width of the engine is reduced accordingly.

In addition, since the rocker shaft is arranged inside the V bank from the cylinder axis and the cam shaft is further arranged inside the rocker shaft,
The exhaust valve can be set up standing almost parallel to the cylinder axis,
As a result, the amount of bulging of the head cover to the outside of the V bank can be reduced, and from this point, the engine width can be further reduced.

Also, as described above, the rocker shaft is divided into left and right,
Since the ignition plug insertion hole is formed between the divided left and right rocker shafts, the ignition plug can be arranged at the center of the combustion chamber, so that the combustibility of the engine can be improved.

Further, when the rocker shaft and cam shaft are arranged closer to the inside of the V bank than the cylinder axis, the cam shaft bearing is arranged between the left and right intake cams. The head bolt can be arranged so as to face outward in the cylinder axis direction from between the shaft and the shaft. As a result, work such as retightening the head bolt with the cam shaft and rocker shaft mounted may interfere with the cam shaft and the like. It can be easily done without.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

1 to 3 are views for explaining a valve train of a V-type engine according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a V-type six-cylinder engine having a bank angle of 90 degrees and four valves for each cylinder. The V-type six-cylinder engine has a structure in which a cylinder head 3 and a head cover 4 are stacked on the left and right upper surfaces of a cylinder block 2.

At the center of the bottom of the cylinder block 2, a crankshaft 5 is supported by a bearing case 6, and an oil pan 7 is mounted on a lower surface of the case 6. In the upper part of the cylinder block 2, left and right cylinders 8, 8 are formed such that their axes L form a bank angle of 90 degrees, and are slidably inserted into the cylinders 8, 8, respectively. The piston 8a is connected to a crankpin 5a of the crankshaft 5 by a connecting rod 8b. The combustion recess 9 of the cylinder head 3 is located on the upper surface of each cylinder 8. A pair of intake ports 10 and exhaust ports 11 are formed on the inside and outside of the bank with the axis L of the cylinder head 3 interposed therebetween, and the intake pipes 10b and exhaust pipes 11b are formed on the outside openings of the ports 10, 11, respectively.
Are connected respectively. In addition, the inner openings 10a and 11a of the ports 10 and 11 have valve plates 12a and 12a of an intake valve 12 and an exhaust valve 13, respectively.
13a is provided. The intake valve 12 extends upward from the axis L to the inside of the bank, that is, rises vertically, and the exhaust valve 13 is substantially parallel to the axis L. An urging spring 14 is provided between retainers 12b, 13b mounted on the upper ends of the valves 12, 13 and a spring seat 3a formed above each of the ports.
The lifter 15 inserted in the slide hole 3d of the cylinder head 3 is mounted on the intake valve 12 side.

The mating surface S between the cylinder head 3 and the head cover 4 is inclined so that the outside of the bank is lower than a plane A perpendicular to the axis L. In other words, it is closer to vertical by the joint surface S. Further, the intake valve 12 of the joint surface S
A cam shaft 16 is provided on the side. A pair of intake cams is provided on both outer portions of each cylinder 8 when viewed from the plane of the cam shaft 16.
16a, 16a are formed, and a portion between the two cams 16a, 16a is pivotally supported by the bearing 3b formed on the mating surface S and the cap 20. A pair of exhaust cams 1 is provided outside the intake cams 16a.
6b and 16b are formed. And when viewed from a plane, the intake cam 16a is located at the center of the lifter 15, and the exhaust cam 1
6b is located very close to this. When the two cams 16a and 16b are brought close to each other, the exhaust cam 16b is
There is a concern of interference. In this embodiment, the cam ridge of the intake cam 16a is formed higher than the exhaust cam 16b, and both the cams 16a, 16b
Are arranged at the same angular position when viewed in the axial direction, thereby solving the problem of the interference.

Further, a rocker shaft 17 is disposed substantially at the center of the mating surface S. When the rocker shaft 17 is viewed from a plane, each cylinder 8
And is supported by a support portion 3f formed at a portion between adjacent cylinders of the mating surface S, and the cap 18
Bolts, and each rocker shaft 17
A predetermined interval is provided at the center of the cylinder.
A plug hole 3c for inserting a spark plug 21 is formed in a portion between the rocker shafts 17 and 17 of the cylinder head 3 so that the spark plug 21 It faces the recess 9. 3d and 3e are head bolt bolt holes for fastening the cylinder head 3 to the cylinder block 2, the bolt hole 3d is located between the cam shaft 16 and the cap 18, and the bolt hole 3e is It is located outside.

Rocker arms 19 are swingably supported at both end portions of the rocker shaft 17 projecting from the cap 18. The rocker arm 19 is substantially parallel to the mating surface S when viewed from the rocker axial direction, and a sliding contact surface 19a formed at one end of the rocker arm 19 slides against the exhaust cam 16b, and an adjuster 19b mounted at the other end Is in contact with the upper end of the exhaust valve 13. When viewed from a plane, the rocker arm 19 is bent inward so that the other end portion is located in the same axial direction position as the intake cam 16a, thereby forming the plug hole 3c.
Is surrounded.

 Next, the operation and effect of this embodiment will be described.

In this embodiment, the lifter 15 is directly pressed by the intake cam 16a of the camshaft 16, the intake valve 12 is lowered, and the intake port 10
The inner opening 10a of the exhaust port 11 is opened, the rocker arm 19 is swung by the exhaust cam 16b, the exhaust valve 13 is lowered by the adjuster 19b, and the inner opening 11a of the exhaust port 11 is opened.

In an engine equipped with a valve operating device for performing such a valve opening operation, in the conventional engine, the mating surface between the cylinder head and the head cover is perpendicular to the cylinder axis (indicated by the symbol A in FIG. 1), and therefore, only that much. The rocker arm and, consequently, the head cover bulged outward as shown by the two-dot chain line in FIG. On the other hand, in this embodiment, the mating surface S is inclined by the plane A perpendicular to the cylinder axis L so that the outside becomes lower, so that the rocker arm 19 becomes nearly vertical, and the projecting amount of the outer end thereof , The amount of swelling of the head cover 4 decreases accordingly, and as a result, the engine width can be reduced by 2 × W. In the present embodiment, the narrowing of the engine width is realized only by inclining the mating surface S, which is compared with that disclosed in the above-mentioned publication in which the valve opening force is transmitted through a number of components such as a push rod. And the structure is very simple.

In this embodiment, the rocker shaft 17 is connected to the intake valve 12 and the exhaust valve 1.
3 and divided at the center of the cylinder, and a plug insertion hole 3c was formed in the divided portion.
Can be located in the center of the combustion chamber. Furthermore, in this embodiment, since the head cover 4 is made smaller, the head bolt hole 3e can be arranged outside the head cover 4, and the workability of fastening the head bolt in this portion is improved.

In the above embodiment, the mating surface S is shifted from the vertical plane A by 12 to
Although the inclination is three degrees, the effect of reducing the engine width can be obtained by increasing the amount of inclination. However, this inclination angle
Since there is a limit depending on the angle between the adjuster portion 13 and the adjuster portion 19b, the required length of the valve 13, and the like, an appropriate selection is made according to these relationships and the required engine width.

〔The invention's effect〕

As described above, according to the valve train for a V-type engine according to the present invention, the mating surface between the cylinder head and the head cover is inclined so that the outside is lower than a plane perpendicular to the cylinder axis, so that the rocker arm is mounted on the engine. , The amount of outward bulging of the head cover is suppressed accordingly, and as a result, the width of the engine can be reduced.

In addition, since the rocker shaft is arranged inside the V-shape from the cylinder axis and the cam shaft is further arranged inside the rocker shaft,
This has the effect of reducing the amount of bulging of the head cover to the outside of the V-bank to further narrow the engine width. In addition, the rocker shaft is divided into left and right, and ignition is performed between the divided left and right rocker shafts. Since the plug insertion hole is formed, there is an effect that the ignition plug is arranged at the center of the combustion chamber and the combustibility of the engine can be improved.

Furthermore, the cam shaft bearing is arranged between the left and right intake cams, and the head bolt inside the V bank is arranged so as to face outward in the cylinder axis direction from between the rocker shaft and the cam shaft. Workability such as retightening the camshaft and the rocker shaft while the camshaft and the rocker shaft are mounted.

[Brief description of the drawings]

1 to 3 are views for explaining a valve train of a V-type engine according to an embodiment of the present invention. FIG. 1 is a sectional side view taken along line II of FIG. 2, and FIG. FIG. 3 is a plan view of the valve gear, and FIG. 3 is a partially sectional front view of the engine. In the figure, 1 is a V-type engine, 2 is a cylinder block, 3 is a cylinder head, 4 is a head cover, 8 is a cylinder, 12 and 13 are intake valves and exhaust valves, 16 is a cam shaft, 17 is a rocker shaft, and 19 is a rocker arm. , A is a right-angled plane, L is a cylinder axis, and S is a mating surface.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F01L 1/02 F01L 1/12 F01L 1/18

Claims (1)

(57) [Claims] 1. A valve train for a V-type engine in which a cylinder head and a head cover are stacked on each cylinder of a cylinder block formed so that cylinders form a V-bank space. , Two intake valves and two exhaust valves are arranged on the outside, respectively, and the mating surface of the cylinder head and the head cover is inclined so that the outside of the V bank is lower than a plane perpendicular to the cylinder axis, From the cylinder axis of the mating surface, V
A rocker shaft is arranged inside the bank and a cam shaft is arranged further inside than the rocker shaft, and the left and right intake valves are driven by the left and right intake cams of the cam shaft via the left and right lifters. The left and right exhaust cams disposed outside the left and right intake cams, the left and right exhaust cams are supported by the rocker shaft.
The left and right exhaust valves are driven via the right rocker arm, the portion between the left and right intake cams of the cam shaft is supported by cam bearings, and the rocker shaft is moved left and right near the cylinder axis. A spark plug insertion hole is formed between the divided left and right rocker shafts, the left and right rocker arms are disposed between the left and right of the ignition plug insertion hole, and the cylinder head is positioned on the cylinder block side. A valve train for a V-type engine, wherein a head bolt inside a V-bank among head bolts fixed to the camshaft is disposed between the rocker shaft and the cam shaft when viewed in the cylinder axis direction.