JPH02223613A - Valve system in internal combustion engine - Google Patents

Abstract

PURPOSE:To improve the rigidity of a locker arm and the durability of a spacer body by providing the spacer body which is constructed so that it may be changed over to an engaged condition or an disengaged condition between a main contact portion and a sub contact portion. CONSTITUTION:When a spacer body 26 is engaged between a main contact portion 22 and a sub contact portion 23, the clearance between both contact portions 22, 23 is decreased by the spacer body 26, and the oscillating movement of a sub locker arm 20 brought into touch with a cam 16 for high-speed is transmitted to a main locker arm 19 through the spacer body 26. Since the main locker arm 19 rotates oscillating through the cam 16 for high-speed, an intake valve 4 is opened and closed by the valve timing or valve lift conforming to a high-speed rotational range. In this case, the spacer body 26 is placed between both the contact portions 22, 23, so valve opening force does not work upon the spacer body 26 as bending moment and shearing load at the same time, but as simple compressive force.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a method for changing either or both of the timing of opening and closing an intake valve or an exhaust valve (so-called valve timing) and the valve lift in an internal combustion engine. The present invention relates to a valve train.

[Conventional technology]

As prior art, Japanese Utility Model Application Publication No. 61-58605 and Japanese Patent Application Laid-Open No. 63-57806 disclose a valve train as described below as a valve train mechanism capable of changing valve timing or valve lift as described above. We are proposing a device.

That is, the valve train of this prior art has a low-speed cam on the camshaft with a cam profile suitable for the low-speed rotation range;
A high-speed cam with a cam profile suitable for a high-speed rotation range is provided, and a main rocker arm that contacts the intake valve or exhaust valve and the low-speed cam is provided on a rocker arm axis parallel to the cam shaft, and a main rocker arm that contacts the low-speed cam, and the high-speed cam The main rocker arm and the sub rocker arm are fitted adjacently to each other, and both the main rocker arm and the sub rocker arm are provided with a bottle hole parallel to the rocker arm axis so that their axes coincide with each other. A plunger pin is slidably inserted into one of the holes, and the plunger pin is switched between a state in which it is retracted into one of the bottle holes and a state in which it is fitted across both bottle holes. When the plunger bin is retracted into one of the bin holes and both rocker arms are disconnected, the intake valve or the exhaust valve is controlled by the low-speed cam to adjust the valve timing or valve lift to suit the low-speed rotation range. When the plunger bin is fitted across both bin holes to connect both rocker arms, the intake valve or exhaust valve is controlled by the high-speed cam to adjust the valve timing to suit the high-speed rotation range (this high-speed The valve timing suitable for the rotation range is such that the intake valve opening timing is earlier than the intake valve opening timing in the valve timing suitable for the low speed rotation range, and the valve timing that the intake valve opening timing is suitable for the low speed rotation range. The opening and closing timing was set at approximately the same time as or later than the timing at which the intake valve opens) or the opening/closing operation was performed by valve lift.

[Problem to be solved by the invention]

However, this prior art valve train has the following problems.

In other words, when both rocker arms are connected by fitting a plunger pin across both pin holes in both rocker arms, the force required to open the intake valve or exhaust valve against its spring (hereinafter referred to as , referred to as valve opening force) is
Since the force is transmitted from the auxiliary rocker arm to the main rocker arm via the plunger bin fitted across both bottle holes, the plunger bin receives both the bending moment and shear load due to the valve opening force at the same time. from,
The rigidity of the connecting portion is low, and in addition to this, a twisting force due to the bending moment and shear load on the plunger bin acts on the inner surface of the pin hole in both rocker arms. Since wear such as sagging occurs on the inner surface and the durability is low, combined with the low rigidity of the connecting portion, the internal combustion engine cannot keep up with the higher speeds of internal combustion engines.

Although this problem can be solved by increasing the diameter of the plunger bin, increasing the diameter of the plunger bin will only lead to an increase in the size of both rocker arms and, in turn, an increase in the size of the internal combustion engine. Alternatively, increasing the size of both rocker arms increases their inertial mass, which impedes high-speed adaptation.

Moreover, in the prior art valve train, in order to configure the plunger pin to fit across both the pin holes, the pin hole in the main rocker arm and the pin hole in the auxiliary rocker arm must be connected to both of them. The axes of the bottle holes must be configured so that they line up exactly on a straight line, and the machining of both bottle holes requires a high degree of precision, resulting in a significant increase in manufacturing costs. . Another problem is that when the base surface of the cam wears out, the plunger pin and the pin hole no longer align in a straight line, making it difficult to fit them together.

SUMMARY OF THE INVENTION An object of the present invention is to provide a valve operating system in which one or both of valve timing and valve lift can be varied, which eliminates these problems.

[Means to solve the problem]

To achieve this object, the present invention provides a low-speed cam and a high-speed cam on a camshaft, while also providing both an intake valve or an exhaust valve and the low-speed cam on a rocker arm shaft parallel to the camshaft. In the valve operating system, the main rocker arm is fitted with a main rocker arm that contacts the high-speed cam, and a sub-rocker arm that contacts the high-speed cam, the main rocker arm is provided with a main contact portion, and the sub-rocker arm is When the secondary rocker arm rotates in the opening direction of the intake valve or the exhaust valve, a secondary contact portion is provided that approaches the main contact portion of the main rocker arm, and the secondary rocker arm rotates in the opening direction of the intake valve or the exhaust valve. The rocker arm is provided with a spacer body configured to be switchable between a position inserted between the main contact part and the sub contact part and a position removed from between the main contact part and the sub contact part. I configured it.

[For production]

In this configuration, when the spacer body is positioned away from between the main contact part and the sub contact part, a gap is created between the main contact part and the sub contact part, and as a result, The rocking motion of the auxiliary rocker arm that contacts the high-speed cam is not transmitted to the main rocker arm, so the intake valve or exhaust valve is adapted to the low-speed rotation range by the low-speed cam that the main rocker arm contacts. It is opened and closed by timing or pulse lift.

On the other hand, when the spacer body is inserted between the main contact part and the sub-contact part, the gap between the main contact part and the sub-contact part is filled by the spacer body, and the high speed The rocking motion of the auxiliary rocker arm that comes into contact with the high speed cam is transmitted to the main rocker arm through the spacer body, and the main rocker arm is rocked and rotated by the high speed cam, so the intake valve or exhaust valve is It is opened and closed by appropriate valve timing or valve lift.

In this case, since the spacer body is sandwiched between both abutting portions, the valve opening force is applied to the spacer body.
Unlike the prior art, it does not act as a bending moment and a shear load at the same time, but acts only as a simple compressive force.

〔Effect of the invention〕

Therefore, according to the present invention, it is possible to improve the rigidity of the connecting portion of the sub rocker arm to the main rocker arm without increasing the size of the rocker arm, and, unlike the prior art, wear such as sagging due to bending moment and shear load can be improved. Since there is no damage and durability can be improved, it is possible to reliably keep up with the increase in speed of internal combustion engines.

Moreover, the present invention allows the valve timing or valve lift to be changed by inserting a spacer body into the gap between the main contact part and the sub-contact part, and by inserting the spacer body into the gap between the main contact part and the sub-contact part. This is performed by drawing out the spacer body, and unlike the prior art, high processing precision is not required, which has the effect of significantly reducing manufacturing costs.

〔Example〕

Hereinafter, an embodiment of the present invention will be explained with reference to the drawings when applied to an intake valve. In the drawings, reference numeral 1 indicates a cylinder block, and reference numeral 2 indicates a cylinder head fastened to the upper surface of the cylinder block 1. , 3 designate cylinder rad covers for the upper surface of the cylinder head 2, respectively.

Reference numeral 4 designates an intake valve provided at the opening of the intake boat 5 into the combustion chamber 6 in the cylinder head 2, and reference numeral 7 designates an intake valve provided at the opening into the combustion chamber 6 of the exhaust boat 8 in the cylinder head 2. The intake valve 4 and the exhaust valve 7 are each provided with valve springs 9 and 10 for keeping each of them normally closed. Furthermore, the reference numeral 11 indicates a spark plug.

A camshaft 12, a hollow rocker arm shaft 13 for an intake valve, and a hollow rocker arm shaft 14 for an exhaust valve are supported on the upper surface of the cylinder head 2 so as to be parallel to each other. On the top, there is a low speed cam 15 for the intake valve 3 and a high speed cam 1 for the intake valve 3.
G and the cam 17 for the exhaust valve 7 are integrally formed. The exhaust valve rocker arm shaft 14 also has a slipper at one end that abuts the exhaust valve cam 17.
Exhaust valve rocker arm 18 is rotatably fitted into exhaust valve rocker arm 18, which has tappet screw 18b on the other end of which is in contact with the upper end of stem 7a of exhaust valve 7.

A main rocker arm 19 and a sub-rocker arm 20 are rotatably fitted onto the intake valve rocker arm shaft 13, and the main rocker arm 19 has a slipper at one end that abuts the low-speed cam 15. -19a, and a tappet screw 19b is provided at the other end of the intake valve 4, the tappet screw 19b coming into contact with the upper end of the stem 4a of the intake valve 4.

The auxiliary rocker arm 20 is provided with a slipper 202 at one end thereof that comes into contact with the high-speed cam 16, while the auxiliary rocker arm 20 is supported by a spring 21 provided between the other end 20b and the cylinder head 2. Slippers-20
8 is urged so that it is always in contact with the high speed cam 16. In addition, as this urging spring means, the other end 20b
Not limited to the spring 21 provided between the and cylinder hend 2,
Other types of spring means may be used, such as a torsion spring fitted onto the rocker arm shaft 13.

A main contact portion 22 that protrudes upward from the sub rocker arm 20 is integrally formed on the side surface of the main rocker arm 19, while the sub rocker arm 20 is formed counterclockwise on the upper surface of the sub rocker arm 20. A sub-contact part 23 that protrudes upward so as to approach the main abutment part 22 when rotated in the direction is integrally formed.
An adjuster screw 24 is provided at the tip.

The main rocker arm 19 also includes the main contact portion 22.
A bottle shaft-shaped spacer body 26 that fits into the guide groove 25 formed in the recess is inserted into the spacer body 26 so as to be slidable in the axial direction. A spring 27 is provided to urge the spacer to retreat to a position away from a position between the inner surface of the guide groove 25 in the main contact part 22 and the tip of the adjuster screw 24 in the sub contact part 23. The inside 13a of the rocker arm shaft 13 is located within the hydraulic chamber 28 formed on the back surface of the body 26.
By supplying hydraulic pressure through the oil boat 29, the spacer body 26 is brought into contact with the inner surface of the guide groove 25 in the main contact portion 22 and the sub contact portion 2, as shown in FIG.
It is configured to be inserted between the tip of the adjuster screw 24 at No. 3. That is, the spacer body 26 is
The position inserted between the inner surface of the guide groove 25 in the main contact portion 22 and the tip of the adjuster screw 24 in the sub contact portion 23 and the position inserted between the inner surface of the guide groove 25 and the tip of the adjuster screw 24 are removed. It is configured so that it can be switched between the two positions.

In this configuration, when the supply of hydraulic pressure to the hydraulic chamber 28 is stopped in the low-speed rotation range of the internal combustion engine, the spacer body 26 is moved by its spring 27 to the inner surface of the guide groove 25 and the adjuster screw, as shown in FIG. 24, and a gap is created between the main abutting part 22 and the auxiliary abutting part 23, which causes the oscillating movement of the auxiliary rocker arm 20 that comes into contact with the high-speed cam 16. is the main rocker arm 1
9, the intake valve 4 is opened and closed by the low-speed cam 15, which the main rocker arm 19 contacts, with valve timing or valve lift suitable for the low-speed rotation range.

Then, when the internal combustion engine reaches a high speed range, the hydraulic chamber 2
8, the spacer body 26 resists the spring 27 and moves into the guide groove 25, as shown in FIG.
By moving forward to a position where it is inserted between the inner surface of the adjuster screw 24 and the tip of the adjuster screw 24, and closing the gap between the main contact part 22 and the sub contact part 23, the sub contact part that contacts the high speed cam 16 is inserted. The rocking motion of the rocker arm 20 is transmitted to the main rocker arm 19 via the spacer body 26, and the main rocker arm 19 is rocked and rotated by the high-speed cam 16, so the intake valve 4 is a valve suitable for the high-speed rotation range. It is opened and closed by timing or valve lift.

In this case, since the spacer body 26 is sandwiched between the main contact portion 22 and the sub contact portion 23 (strictly speaking, the tip of the adjuster screw 24), the spacer body 26 is , the opening force of the intake valve 4 does not act as a bending moment and a shear load at the same time, but acts only as a simple compressive force.

In addition, although the above-mentioned embodiment shows the case where it is applied to the intake valve 4, the present invention is not limited to this, and can be applied to the exhaust valve 7 as well. If the adjuster screw 24 is provided for the sub-contact portion 23 as in the embodiment, there is an advantage that the gap at each contact point can be adjusted.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which FIG. 1 is a vertical front view, FIG. 2 is a sectional view taken along ■-■ in FIG. 1, and FIG. 3 is a cross-sectional view taken along m--
FIG. 4 is a cross-sectional view taken along the line 1--2 in FIG. 1, and FIG. 5 is a view showing the operating state of FIG. 1... Cylinder block, 2... Cylinder head, 4... Intake valve, 7-... Exhaust valve, 12...
...Cam shaft, 13...Rocker arm shaft, 15...
・Low speed cam, 16...High speed cam, 19...
Main rocker arm, 20... Secondary rocker arm, 22.
... Main contact part, 23 ... Side contact part, 24 ...
Adjuster screw, 25... Guide groove, 26...
・Spacer body, 27...spring, 28...hydraulic chamber.

Claims (1)

[Claims] (1) A low-speed cam and a high-speed cam are provided on the camshaft, and a main rocker arm that contacts both the intake valve or exhaust valve and the low-speed cam is placed on the rocker arm shaft parallel to the camshaft. and a sub-rocker arm that contacts the high-speed cam, the main rocker arm is provided with a main contact portion, and the sub-rocker arm is provided with a sub-rocker arm that contacts the intake valve. Alternatively, when the exhaust valve rotates in the opening direction, a sub-contact part is provided that approaches the main abutment part of the main rocker arm, and one of the two rocker arms has a sub-contact part that approaches the main contact part of the main rocker arm. A spacer body configured to be switchable between a position inserted between the contact part and the sub-contact part and a position removed from between the main contact part and the sub-contact part is provided. Valve train in internal combustion engine.