JPS6132092Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an intake/exhaust valve drive device for an internal combustion engine that variably controls the opening/closing timing and valve lift amount of intake/exhaust valves according to operating conditions.

Various intake and exhaust valve drive devices have been proposed in the past, which variably control the opening/closing timing of the intake and exhaust valves and the amount of valve lift according to the engine operating conditions so that valve overlap, fresh air filling efficiency, etc. are always optimally achieved. One example is the U.S. Patent No. 1 shown in Figure 1.
No. 3413965 is known.

This valve drive device has a rocker arm 3 whose one end abuts the valve drive cam 1 and whose other end is fitted and supported by the stem end of the intake/exhaust valve 2. The back surface 4 of the rocker arm 3 is curved, and the back surface 4 is connected to the lever 5. By swinging the left and right sides of the rocker arm 3 while contacting the fulcrum,
The lift of the cam 1 is transmitted to the intake and exhaust valves 2, and in particular, the lever 5 is pivotably supported at one end thereof, and its inclination is regulated by a control cam 6. ing. The control cam 6 is rotationally driven in an appropriate phase according to engine operating conditions by a drive mechanism such as a hydraulic actuator, thereby variably controlling the opening/closing timing and lift amount of the intake/exhaust valve 2. That is, for example, if the lever 5 is pushed down by a large amount by the control cam 6, the free end of the lever 5 and the rocker arm 3 will be close to each other in the base circle state of the valve drive cam 1, and therefore the intake and exhaust valves 2 will be pushed down by a large amount. As the valve opening timing becomes earlier, the valve lift amount increases, and if the amount of depression by the control cam 6 is small, the free end of the lever 5 and the rocker arm 3 will move even if the valve driving cam 1 is in the same base circle state.
Therefore, the opening timing of the intake and exhaust valves is delayed and the amount of valve lift becomes small.

However, in this conventional intake/exhaust valve drive device, since the rocker arm 3 receives thrust force from the drive cam 1 in its longitudinal direction, a strong bending moment acts on the valve stem 2a of the intake/exhaust valve 2. Therefore, there are problems such as the valve stem 2a becoming fatigued and breaking, or the oil seal at the upper end of the valve guide wearing out prematurely due to the valve stem 2a being bent.

Furthermore, in this conventional configuration, the lever 5
Since the relative movement between the lever 5 and the locker arm 3 is complicated, it is difficult to provide a spring for returning the locker arm 3 between the lever 5 and the locker arm 3.
For example, when the rocker arm 3 is pushed down only slightly by the control cam 6, the followability of the rocker arm 3 with respect to the valve drive cam 1 deteriorates, and jumps or bounces of the rocker arm occur. These become a cause of noise vibration and abnormal wear. In addition, the rocker arm 3 is not regulated to be displaced in the axial direction of the camshaft, and there is a risk that it may come off the lever 5 during operation.

This invention aims to eliminate the above-mentioned conventional drawbacks, and one embodiment thereof will be described in detail below with reference to the drawings.

2 and 3 are a sectional view and a plan view showing an embodiment of this invention, in which 11 is a valve drive cam that rotates in synchronization with engine rotation, and 12 is a valve drive cam that absorbs the movement of this valve drive cam 11. The rocker arm that transmits to the exhaust valve 13 is shown, and the rocker arm 12
has a back surface 14 formed into a predetermined gently convex curved surface, and one end 12a is connected to the valve drive cam 11, and the other end 12b is connected to the valve stem 15.
are arranged so as to abut on the stem ends 15a of the respective stem ends 15a. Here, the other end 12b has an appropriate radius.
The stem end 15a comes into contact with the stem end 15a in a sliding or rolling contact at the contact surface 12a, and guide portions 16 are integrally formed on both sides of the contact surface 12a to prevent the two from separating. There is.

Reference numeral 17 denotes a lever having a linear support surface 18 for supporting the lock arm 12. This lever 17 is rotatably supported by a shaft 19 fixed on a line extending from the valve stem 15, and is disposed adjacent to the back surface 14 of the lock arm 12 so that the back surface 14, which forms a convex curved surface, comes into fulcrum contact with the support surface 18. A control cam 20 abuts against the back surface of this lever 17, and positions the lever 17 in accordance with the amount of cam lift.

On the other hand, a cylindrical pivot accommodating part 21 whose lower end is open in the support surface 18 is bored in the approximate center of the lever 17, and a cylindrical pivot member 22 is inserted therein so as to be movable forward and backward. ing. This pivot member 22 has a tip end 22a.
has a hemispherical shape and is constantly biased in the protruding direction by an internal coil spring 23,
The hemispherical tip portion 22a is swingably fitted into a pivot fitting portion 24 that is recessed in a hemispherical shape approximately at the center of the back surface 14 of the rocker arm 12.

In addition, the pivot member 22 and the pivot storage section 2
1 and the oil gear lary 2 in the shaft 19.
5 through oil holes 26 and 27, and lubricating oil is supplied between the pivot member 22 and the pivot fitting portion 24 from within the pivot storage portion 21 through the oil hole 28. It's summery. Also,
Reference numeral 29 denotes an air hole communicating with the pivot storage portion 21.

In the above configuration, the pivot member 22 is always fitted into the pivot fitting portion 24 of the rocker arm 12, and the locker arm 12 is held in this fitted state.
oscillates. That is, the biasing force of the coil spring 23 of the pivot member 22 is set to be sufficiently smaller than the reaction force of the valve spring 30, so that when the valve drive cam 11 starts to lift, the pivot member 22 gradually moves upward. The rocker arm 12 swings while moving the contact fulcrum between the back surface 14 of the rocker arm 12 and the support surface 18 of the lever 17 to the left in the figure. Here, a thrust force acts on the rocker arm 12 in its longitudinal direction, but since the pivot member 22 is fitted into the pivot fitting part 24 as described above, movement in the longitudinal direction is restricted, and therefore the intake and exhaust The lift of the valve drive cam 11 is transmitted to the valve 13 as a force along the axial direction of the valve stem 15 . Therefore,
The valve stem 15 is not bent or deformed.

Also, when the lift of the valve drive cam 11 falls from the peak lift, a thrust force acts in the opposite direction, but this thrust force is also supported by the pivot member 22 in this case.

Further, according to the above configuration, the rocker arm 12 reliably follows the valve drive cam 11 due to the biasing force of the coil spring 23 installed in the pivot member 22, and there is no fear that the rocker arm 12 will fall off the lever 17. .

It should be noted that when the inclination angle of the lever 17 changes due to the rotation of the control cam 20, the opening/closing timing and lift amount of the intake/exhaust valve 13 change, just as in the conventional example described above.

As explained above in detail, according to this invention, a strong bending moment does not act on the valve stem of the intake and exhaust valve, and the bending deformation of the valve stem can be prevented without particularly strengthening the valve stem. This has the effect of regulating the irregular movement of the rocker arm and improving the ability to follow the valve drive cam.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional intake/exhaust valve drive device, FIG. 2 is a sectional view of the intake/exhaust valve drive device according to this invention, and FIG. 3 is a plan view thereof. 11... Valve drive cam, 12... Locker arm, 13... Intake and exhaust valve, 15... Valve stem,
16...Guide part, 17...Lever, 20...Control cam, 22...Pivot member, 23...Coil spring, 24...Pivot fitting part.

Claims (1)

[Scope of utility model registration request] A valve drive cam that rotates in synchronization with engine rotation, and a rocker arm that has one end interlocked with the valve drive cam and the other end with the valve stem, and has a pivot fitting portion recessed approximately in the center of its back surface. , a lever disposed substantially along the back surface of the rocker arm, making fulcrum contact with the back surface, and rotatably supported at one end on the valve stem side;
A pivot member is disposed in a substantially central portion of the lever so as to be movable back and forth, and the tip of the pivot member is swingably fitted in the pivot fitting portion, and a spring biases the pivot member toward the pivot fitting portion. An intake/exhaust valve drive device for an internal combustion engine, comprising: a member; and a control means for controlling the inclination of the lever.