JP2652852B2 - Valve train for 4-cycle engine - Google Patents

Description

Description: TECHNICAL FIELD [0001] The present invention relates to a valve train for a four-stroke engine provided with an automatic hydraulic valve clearance corrector.

(Prior art)

In a four-stroke cycle engine, an overhead type valve train is configured such that one end of a rocker arm swingably supported on a rocker shaft is brought into contact with a cam synchronized with engine rotation, and the other end is brought into contact with an upper end of an intake / exhaust valve. The opening and closing of the intake / exhaust valve is performed.

In such a valve operating device, instead of the rocker shaft, an intermediate upper portion of the rocker arm is supported by an automatic hydraulic valve clearance corrector called a lash adjuster. There has been proposed a device in which a gap between the rocker arm and the upper end of the intake / exhaust valve can be automatically corrected. This automatic hydraulic valve clearance compensator is disclosed in Japanese Utility Model Laid-Open No. 58-144006,
As described in Japanese Patent Application Laid-Open Publication No. H10-209, the holding outer cylinder is generally formed integrally with a cylinder head cover. For this reason, when assembling the automatic hydraulic valve clearance corrector as a valve operating mechanism, it has to be set together with the cylinder head cover.

However, since the cylinder head cover has a much larger covering area than the automatic hydraulic valve clearance corrector, as described above, installing the automatic hydraulic valve clearance corrector at the same time as assembling the cylinder head cover may obstruct the view. Therefore, there is a problem that it is difficult to set at an appropriate position and it requires skill. As a result, the productivity has been reduced and the cost has been increased.

[Object of the invention]

An object of the present invention is to provide an automatic hydraulic valve clearance corrector as a component of a valve operating mechanism in a cylinder head cover. An object of the present invention is to provide an engine valve gear.

[Configuration of the invention]

To achieve the above object, the present invention provides an automatic rocker arm in which one end of a rocker arm abuts on a cam synchronized with engine rotation, the other end abuts on a valve rod upper end of an intake / exhaust valve, and an intermediate upper part is provided on a cylinder head cover side. In a four-cycle engine supported by a pressure rod of a hydraulic valve clearance corrector, the cylinder head cover is located in a direction connecting a contact position of a cam with which one end of the rocker arm contacts and an upper end of a valve rod with which the other end contacts. An opening through which the rocker arm can be inserted facing the upper end of the valve rod is provided on a side surface of the cylinder head cover. A detachable lid is provided in the opening, and a through hole is provided in the upper surface of the cylinder head cover, and the through hole is formed in the opening. Part is provided so as to be inclined toward the opening side, and the outer cylinder of the automatic hydraulic valve gap corrector is inserted into the through hole from the outside toward the inside,
The outer cylinder is detachably fixed to the upper surface of the cylinder head cover with a bolt via a flange provided below the upper end surface thereof, and the bolt is disposed at a position separated from the rocker arm in plan view. Is what you do.

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

In the figure, 1 is a cylinder, 2 is a cylinder head, 3
Is a cylinder head cover. The cylinder head 2 is provided with an intake port 4 and an exhaust port 5, and an intake valve 6 and an exhaust valve 7 for opening and closing these ports.
The intake valve 6 and the exhaust valve 7 have springs 8, 9 engaged with the upper ends of the valve rods 6a, 7a, respectively, and are urged in a direction to always close. A cam shaft 10 is provided at an intermediate position between the intake valve 6 and the exhaust valve 7 so as to synchronize with the engine rotation. Cams 11 and 12 for driving the intake and exhaust valves are integrated with the cam shaft 10. Is provided.

13 and 14 are rocker arms, respectively. One rocker arm 13 has one end in contact with the cam 11, the other end in contact with the upper end of the valve rod 6a of the intake valve 6, and the other rocker arm 14 has one end in contact with the cam 12. The other end is in contact with the upper end of the valve rod 7a of the exhaust valve 7. An automatic hydraulic valve clearance corrector attached to the cylinder head cover 3 is provided at an upper intermediate portion between the rocker arms 13 and 14.
The distal ends of the pressing rods 17 and 15 are engaged with each other, and the rocker arms 13 and 14 can swing about these pressing ends as fulcrums.

Each automatic hydraulic valve clearance corrector 15 has a holding outer cylinder 16 formed independently of the cylinder head cover 3.
Reference numeral 16 designates a structure in which a pressing rod 17 is slidably inserted therein, and a plunger 18 is provided inside the pressing rod 17. The outer cylinder 16 has a flange 19 formed on the outer periphery on the upper side below the upper end surface thereof. When inserted from the outside toward the inside, the flange 19 is brought into close contact with the upper surface of the cylinder head cover 3 with the O-ring 22 interposed therebetween, and is fixed by the bolt 21. Further, the bolt 21 is disposed at a position separated from the rocker arm 17 in plan view.

When the automatic hydraulic valve clearance corrector 15 is configured to be detachable from the cylinder head cover 3 in this manner, the upper limit of the allowable rotation speed of the intake / exhaust valve may be restricted due to the reduced mounting rigidity. However, in the above embodiment, the flange 19
By fixing the O-ring 22 between the cylinder head cover 3 and the cylinder head cover 3, the mounting rigidity of the automatic hydraulic valve clearance compensator 15 is increased, and the upper limit of the allowable rotation speed of the intake and exhaust valves is increased.

Also, each automatic hydraulic valve clearance compensator installed in this way
As shown in FIG. 2, an oil supply path 25 is connected to 15, and pressurized oil is supplied from the oil supply path 25. This oil allows the plunger 18
The pushing rod 17 is pushed out through the shaft, and its tip is pushed to the middle upper part of the rocker arms 13 and 14, respectively, and acts as a swing fulcrum of the rocker arms 13 and 14, and the upper ends of the valve rods 6a and 7a of the intake and exhaust valves. Is corrected.

As shown in FIG. 3, the fulcrums B, B at which the distal ends of the pressing rods 17, 17 support the rocker arms 13, 14, respectively, have both ends of the rocker arms 13, 14 in contact with the cams 11, 12, respectively, in plan view. The contact points A, A and the points C, C contacting the upper end of the valve rod 6a of the intake valve and the upper end of the valve rod 7a of the exhaust valve coincide with a straight line. By arranging the action points A, B, and C of the three forces on a straight line in this manner, rolling does not occur on the rocker arms 13 and 14 and a stable valve operation can be performed.

Further, the cylinder head cover 3 has two side positions located in a direction connecting the contact position of the cam 11 with which one end of each of the rocker arms 13 and 14 contacts and the upper ends of the valve rods 6a and 7a with which the other ends contact, respectively. Openings 23 and 23 are provided so that the upper part of the valve rod 6a of the intake valve 6 and the upper part of the valve rod 7a of the exhaust valve 7 can be seen, respectively. In addition, these openings 23,23
A lid 24 for closing is detachably attached to the cover.

In the above-described valve gear, the outer cylinder 16 of the automatic hydraulic valve gap corrector 15 is formed independently of the cylinder head cover 3, and the outer cylinder 16 is inserted into the through hole 20 provided in the cylinder head cover 3 from outside to inside. It is configured to be fixed. Therefore, when assembling the automatic hydraulic valve clearance compensator 15 as a valve operating mechanism, it is not necessary to perform the assembly simultaneously with the assembly of the cylinder head cover 3 having a large area as in the related art. Since they can be performed independently, they can be assembled accurately and easily.

If the openings 23, 23 are further provided on the side of the cylinder head cover 3 as in the above embodiment, the rocker arms 13, 14 are inserted through the openings 23, 23, and the openings 2
The position of the rocker arm can be adjusted while viewing the inside from 3, 23, and the automatic hydraulic valve clearance compensator 15, 15 can be assembled, making the work more accurate and simpler. Workability can be improved.

Also, since the through hole 20 for mounting the automatic hydraulic valve clearance corrector 15 is provided so as to face the opening 23 side, the work of assembling the rocker arms 13 and 14 from the opening 23 and the outer cylinder 16 of the automatic hydraulic valve clearance corrector 15 The assembling work can be performed at the same position, and the assembling work can be performed efficiently.

Further, by providing the bolt 21 attached to the flange 19 at a position separated from the rocker arms 13 and 14 in a plan view, the cylinder head cover 3 located below the bolt 21 is configured to protrude inward. Even
There is no hindrance in assembling the rocker arms 13 and 14, and even if the bolt 21 is attached so as to be screwed to the cylinder head cover 3, the screwing length can be ensured. The outer cylinder 16 of the container 15 is fixed to the upper surface of the cylinder head cover 3 with a bolt 21 via a flange 19 formed below the upper end surface thereof, so that the bolt 21 protrudes upward from the outer cylinder 16 to save extra space. Does not occupy.

〔The invention's effect〕

As described above, the present invention relates to a valve gear using an automatic hydraulic valve clearance corrector, wherein the outer cylinder of the automatic hydraulic valve clearance corrector is configured to be independent of a cylinder head cover, and a through hole provided in the cylinder head cover. In this configuration, the automatic hydraulic valve clearance compensator alone can be independently assembled after the cylinder head cover is mounted, so that it can be easily and accurately assembled.

Also, since an opening for inserting the rocker arm facing the upper end of the valve rod is provided on the side surface of the cylinder head cover located in a direction connecting the contact position of the cam with which one end of the rocker arm is in contact with the upper end of the valve rod with which the other end is in contact. The operator can adjust the set position of the rocker arm and assemble the automatic hydraulic valve clearance corrector while visually observing the inside from the opening, thereby further simplifying the assembling work.

In addition, since a through hole for mounting the outer cylinder of the automatic hydraulic valve clearance corrector is provided on the upper surface of the cylinder head cover so as to face the opening side, the work of assembling the rocker arm from the opening and the work of mounting the outer cylinder of the automatic hydraulic valve clearance corrector Can be performed at the same work position, so that the assembling work can be performed more efficiently.

In addition, a bolt for fixing the outer cylinder is arranged at a position separated from the rocker arm in a plan view, so that the cylinder head cover located on the lower side of the bolt projects inward, and the screwing length of the bolt is reduced. Even if it is secured, it does not become a hindrance when assembling the rocker arm, and furthermore, a bolt is attached to the upper surface of the cylinder head cover via a flange provided below the upper end surface of the outer cylinder of the automatic hydraulic valve clearance compensator. By fixing the bolt, it is possible to prevent the bolt from projecting upward from the outer cylinder and occupying extra space.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cylinder head portion of a four-stroke engine having a valve train according to an embodiment of the present invention, taken along the line II of FIG. 2, and FIGS. It is a top view of a cycle engine. 2 ... Cylinder head, 3 ... Cylinder head cover,
6 ... intake valve, 7 ... exhaust valve, 6a, 7a ... valve rod, 10 ...
Cam shaft, 11,12… Cam, 13,14 …… Rocker arm, 15…
... Automatic hydraulic valve clearance corrector, 16 ... outer cylinder, 17 ... pressing rod, 19 ... flange, 20 ... through hole, 21 ... bolt, 23
...... Opening, 24 ... Lid.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-65713 (JP, A) JP-B-61-32088 (JP, Y2) JP-B-59-49582 (JP-A-60-162204) Microfilm (JP, U) photographing the contents of the specification and drawings attached to the application of the present application Photographing the contents of the specifications and drawings attached to the application of Jpn. Microfilm (JP, U)

Claims (1)

(57) [Claims] 1. An automatic hydraulic valve clearance correction wherein one end of a rocker arm abuts a cam synchronized with engine rotation, the other end abuts an upper end of a valve rod of an intake / exhaust valve, and an intermediate upper portion is provided on a cylinder head cover side. In a four-stroke engine designed to be supported by a pressure rod of a vessel, a side surface of the cylinder head cover located in a direction connecting a contact position of a cam with which one end of the rocker arm contacts and an upper end of a valve rod with which the other end contacts, An opening through which the rocker arm can be inserted is provided facing the upper end of the valve rod, and a detachable lid is provided in this opening.
A through-hole is provided on the upper surface of the cylinder head cover, and the through-hole is provided so as to be inclined so that an opening thereof is directed to the opening side. And the outer cylinder is detachably fixed to the upper surface of the cylinder head cover with a bolt via a flange provided below the upper end surface thereof with a bolt, and the bolt is located at a position separated from the rocker arm in plan view. A valve train for a four-stroke engine, wherein the valve train is arranged.