JP2758714B2 - Valve train in internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to one or both of a timing of opening and closing an intake valve or an exhaust valve (so-called valve timing) and a valve lift of an internal combustion engine. The present invention relates to a valve train that can be changed during operation.

[Conventional technology]

Japanese Utility Model Laid-Open Publication No. 61-58605 as a prior art discloses a valve operating device that can change a valve timing or a valve lift during operation of an internal combustion engine as described above.
The following are proposed.

That is, this prior art valve train has a
While providing a low-speed cam having a cam profile suitable for a low-speed rotation region and a high-speed cam having a cam profile suitable for a high-speed rotation region, an intake valve or an exhaust valve is provided on a rocker arm shaft arranged in parallel with the cam shaft. A main rocker arm abutting on the low-speed cam and a sub-rocker arm abutting on the high-speed cam are pivotally adjacent to each other, and both the main rocker arm and the sub-rocker arm are parallel to the rocker arm axis. A pin hole was drilled with its axis aligned, a plunger pin was slidably inserted into one of the two pin holes, and the plunger pin was retracted into one of the pin holes. When the two rocker arms are in a non-coupled state by retracting the plunger pin into one of the pin holes, the state is configured to be switchable between a state and a state of fitting over both of the pin holes. The air valve or the exhaust valve is opened and closed by a low-speed cam at a valve timing or a valve lift adapted to a low-speed rotation range, and when the two rocker arms are connected by fitting the plunger pin across both pin holes. The intake valve or the exhaust valve is configured to be opened / closed at a valve timing or a valve lift adapted to a high-speed rotation range by a high-speed cam.

[Problems to be solved by the invention]

However, the valve train in this prior art has the following disadvantages.

That is, when the two rocker arms are connected by fitting the plunger pins over both of the pin holes of the two rocker arms, it is necessary to open the intake valve or the exhaust valve against the spring of the plunger pin. A torsion force acts due to a bending moment and a shear load due to a large force (hereinafter, referred to as a valve opening force), and the plunger pin must slide in the axial direction against the torsion force. The inner surfaces of the two pin holes to be fitted are liable to cause abrasion such as settling and have low durability, and in addition to the low durability, the plunger slides in the axial direction so that the plunger slides quickly. Because it lacks, it does not follow the increase in the speed of the internal combustion engine.

In addition, in the prior art valve train, the plunger pin is configured to be fitted over both pin holes or to be retracted into one of the pin holes.
The distance from the axis of the rocker arm axis to the center of the pin hole in the main rocker arm, and the distance from the axis of the rocker arm axis to the center of the pin hole in the sub rocker arm, so that the axes of these pin holes are aligned in a straight line. It is necessary to form the pin holes accurately, and a high processing accuracy is required to process these two pin holes. Therefore, there is a problem that the production cost is significantly increased.

It is an object of the present invention to provide a variable valve timing and / or valve lift type valve train that solves these problems.

[Means for solving the problem]

In order to achieve this object, the present invention provides a low-speed cam and a high-speed cam on a cam shaft, while providing an intake valve or an exhaust valve and the low-speed cam on a rocker arm shaft arranged in parallel with the cam shaft. A valve actuating device having a main rocker arm that contacts both the cam and a pivotal arm, and further including a sub rocker arm that contacts the high-speed cam;
The main rocker arm is rotatably pivoted with a pin, and the sub rocker arm is provided with a contact fulcrum for the rocker arm shaft, while the rocker arm shaft is rotated by the rocker arm shaft. The eccentric portion is configured to be switchable between a position contacting the contact fulcrum portion and a position not contacting the contact fulcrum portion.

[Action]

In this configuration, when the eccentric portion of the rocker arm shaft is set at a position where the eccentric portion of the rocker arm shaft does not come into contact with the contact fulcrum portion of the sub-rocker arm by the rotation operation of the rocker arm shaft, the sub-rocker arm is centered on a pivot pin for the main rocker arm. In this case, the swing rocking operation is performed only by the high-speed cam, and does not swing around the rocker arm shaft as a fulcrum.
Since it is not transmitted to the intake valve or the exhaust valve, the intake valve or the exhaust valve is pivotally attached to the rocker arm shaft and is connected to the low-speed cam through the swinging rotation of the main rocker arm. , The valve is opened and closed at a valve timing or a valve lift suitable for the low-speed rotation range.

When the eccentric portion of the rocker arm shaft is brought into contact with the contact fulcrum of the sub rocker arm by rotating the rocker arm shaft, the sub rocker arm that contacts the high-speed cam is moved by the rocker arm. The swinging rotation is performed by the high-speed cam with the shaft as a fulcrum, and this swinging rotation is transmitted to the intake valve or the exhaust valve via the main rocker arm. The high-speed cam is opened and closed at a valve timing or a valve lift suitable for a high-speed rotation range.

〔The invention's effect〕

As described above, according to the present invention, the valve timing or the valve lift is changed by the rotation operation of the rocker arm shaft. At the time of the change operation, a twisting force due to a large valve opening force is generated as in the prior art. Without and can be operated quickly, it is possible to greatly improve the durability, it is possible to reliably follow the high speed of the internal combustion engine, and, as in the prior art,
Since high processing accuracy is not required, there is an effect that the manufacturing cost can be significantly reduced.

〔Example〕

Hereinafter, a description will be given of a drawing in which an embodiment of the present invention is applied to an intake valve. In the drawings, reference numeral 1 denotes a cylinder block, and reference numeral 2 denotes a cylinder head fastened to the upper surface of the cylinder block 1. Each is shown.

Reference numeral 3 denotes an intake valve provided at an opening of the intake port 4 formed in the cylinder head 2 into the combustion chamber 5. The two intake valves 3 are provided with a valve spring 6 for holding each of them normally closed.

A cam shaft 7 and a rocker arm shaft 8 are disposed on the upper surface of the cylinder head 2 in parallel with each other, and the cam shaft 7 and the rocker arm shaft 8 are provided on a bearing portion 9 provided on the upper surface of the cylinder head 2. And a pair of left and right low-speed cams 10 for both intake valves 3 and one high-speed cam for both intake valves 3 on the camshaft 8.
11 and are integrally formed.

A base boss portion 12a of a pair of left and right main rocker arms 12 is rotatably fitted to the rocker arm shaft 8, and the two low speed cams 10 are mounted on the upper surfaces of the two main rocker arms 12.
The other end of the two intake valves 3a
Are provided with tappet screws 12c abutting on the upper end of the stem 3a.

Further, between the two main rocker arms 12, a sub rocker arm 13 having a slipper portion 13a on the upper surface which contacts the high-speed cam 11 is wired, and the sub rocker arm 13 is connected to the main rocker arms 12. And pivotally attached via a pin 14.

A contact fulcrum 15 for the rocker arm shaft 8 is integrally protruded toward the rocker arm 8 on the sub rocker arm 13 while the rocker arm shaft 8
Of the parts corresponding to the contact fulcrum part 15, an eccentric part 16 with respect to the axis 8a of the rocker arm shaft 8 is provided integrally, and this eccentric part 16 is rotated by rotating the rocker arm shaft 8. A position where the eccentric portion 16 does not contact the contact fulcrum portion 15 as shown in FIG.
4 is configured to selectively switch to a position where it contacts the contact fulcrum 15 as shown in FIG.

The auxiliary rocker arm 13 is urged upward by a spring 17 provided between the auxiliary rocker arm 13 and the cylinder head 2.

In this configuration, the eccentric portion of the local arm shaft 8
16 is moved to the third position by the rotation operation of the rocker arm shaft 8.
As shown in the figure, the contact fulcrum of the sub rocker arm 13
When the rocker arm shaft 13 is set at a position where the rocker arm shaft 8 is not brought into contact with the main rocker arm 12, the rocker arm shaft 8 is pivoted only by the high-speed cam 11 around the pivot pin 14 for both main rocker arms 12. It does not swing and pivot as a fulcrum,
Accordingly, since the swinging rotation of the sub rocker arm 13 is not transmitted to the intake valves 3, the intake valves 3 are pivotally connected to the rocker arm shaft 8 and contact the low speed cam 10. Through the swinging rotation of the rocker arm 12, the low-speed cam
At 10, the valve is opened and closed at a valve timing or valve lift suitable for the low speed rotation range.

Then, the eccentric portion 16 of the rocker arm shaft 8 is
As shown in FIG. 4, when the rocker arm shaft is rotated to a position where it contacts the contact fulcrum 15 of the sub rocker arm 13, the sub rocker arm 13 that contacts the high-speed cam 11 is The high-speed cam 11 swings about the rocker arm shaft 8 as a fulcrum, and this swinging rotation is transmitted to both the intake valves 3 via the two auxiliary rocker arms 12. Is opened and closed by the high-speed cam 11 at a valve timing or a valve lift suitable for a high-speed rotation range.

Therefore, by rotating the rocker arm shaft 8 as described above according to the rotation speed of the internal combustion engine,
It is possible to automatically control the valve timing or the valve lift of the two intake valves 3 so as to be adapted over both the low-speed rotation range and the high-speed rotation range during the operation of the internal combustion engine.

In addition, although the said Example showed the case where it applied to the intake valve 3 provided in two in one combustion chamber 5, this invention is not limited to this and only one is provided in one combustion chamber 5. It is needless to say that the present invention can be applied to an intake valve which is provided in a single combustion chamber and also to an exhaust valve provided in one or two combustion chambers. You can do it.

[Brief description of the drawings]

1 shows an embodiment of the present invention. FIG. 1 is a view showing the gist of the present invention. FIG. 2 is a sectional view taken along line II of FIG. 2, FIG. 2 is a plan view, and FIG. III is a sectional view, FIG. 4 is a view showing an operation state of FIG. 3, and FIG. 5 is a sectional view taken along line VV of FIG. 1 ... Cylinder block, 2 ... Cylinder head, 3 ...
... intake valve, 4 ... intake port, 5 ... combustion chamber, 6 ... valve spring, 7 ... cam shaft, 8 ... rocker arm shaft, 9 ...
… Bearing part, 10… Cam for low speed, 11… Cam for high speed, 12
… Main rocker arm, 13… Sub-rocker arm, 14… Connecting pin, 15… Contact fulcrum, 16… Eccentric part.

Claims (1)

(57) [Claims] 1. A low-speed cam and a high-speed cam are provided on a cam shaft, and both a suction valve or an exhaust valve and the low-speed cam are provided on a rocker arm shaft arranged in parallel with the cam shaft. A valve operating device comprising a main rocker arm that pivotally contacts the contacting main rocker arm and a sub rocker arm that contacts the high-speed cam, wherein the sub rocker arm is pivotally connected to the main rocker arm rotatably with a pin, Further, the auxiliary rocker arm is provided with a contact fulcrum for the rocker arm shaft, and the rocker arm axle is provided with a position contacting the contact fulcrum by rotating the rocker arm shaft, and A valve train in an internal combustion engine provided with an eccentric part configured to be switchable to a position not in contact with the part.