JPH09217607A - Combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the velocity and acceleration of a valve by specifying an angle formed by a line from an inclined shaft to a contact at which a rocking arm is brought into contact with a lever, to a line from the contact to a rotating shaft in the engine where its valves are opened/closed by the rocking arm inclined around an inclined shaft by way of the lever. SOLUTION: When a cam shaft 10 is rotated, a ball bearing 17 is rolled over the outer surfaces of cams 11 and 12 which are switched over so a to be used in response to engine revolution speeds, and is moved upward. The movement of the ball bearing 17 causes a rocking arm 14 to be rocked to the direction of P2, and a valve 5 is opened by letting the flat lower side 25 of the rocking arm 14 be brought into contact with the ball bearing 19 of a lever 21 at a contact 26. In this place, an angle is set up in a range of 80 deg. to 170 deg., which is formed by a line from the inclined shaft 15 of the rocking arm 14 to the contact 26 and a line from the contact 26 to the rotating shaft 22 of the lever 21. By this constitution, smooth velocity and acceleration are enhanced when a valve is opened/closed, and concurrently abrasion resistance at the contact 26 is thereby enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camshaft, a swinging arm tilted about an inclination axis by the camshaft, a lever swinging around the rotation axis by the swinging arm, and a closed position to an open position. A valve driven by a lever is provided so that the relative position of the contact point where the rocking arm contacts the lever is changed according to the tilt amount of the rocking arm. is there.

[0002]

BACKGROUND OF THE INVENTION In conventional combustion engines, a camshaft provided with a cam is rotated so that the cam engages one end of a swing arm which can be tilted about a tilt axis. At its end remote from the camshaft, the rocker arm engages a valve that moves against the force of a spring. The inlet to the combustion chamber of the combustion engine is opened and closed by this valve.

In the combustion engine of JP-A-58-217710 described in the preamble of claim 1, the lever is located between the swing arm and the valve. This lever is used to limit the height of the engine. When the swing arm tilts, the contact position between the swing arm and the lever changes. Since the angle between the tilt axis of the swing arm to the contact and the line from the contact to the pivot axis of the lever is a relatively sharp angle, the effect of contact fluctuations on valve movement is negligible.

The locus of movement of the valve, ie the movement of the valve during opening and closing, is mainly determined by the shape of the cam. The limit of this movement is determined by the fixed transmission ratio of the swing arm. The transmission ratio is the ratio between the distance between the contact between the rocking arm and the cam and the tilt axis of the rocking arm and the distance between the contact between the lever and the rocking arm and the tilt axis.

[0005]

Due to the increasing demand for increasing the speed and acceleration of valve opening and closing, the shape of the cam becomes more complex. Creating such a complex cam shape is expensive. In addition, relatively small cam followers are the only means to follow the movements forced by the cams.

It is an object of the present invention to provide a combustion engine in which the valve speed and acceleration can be relatively high, yet the shape of the cam on the camshaft can be maintained relatively easily. .

[0007]

In the combustion engine of the present invention that achieves this object, the angle between the line from the tilt axis to the contact and the line from the contact to the pivot axis is at the valve closed position. Within 80 ° to 170 °.

The lever is rotated by the inclination of the swing arm,
This causes the contact between the swing arm and the lever to shift. As a result of this, and due to the angle of 80 ° to 170 ° between the rocking arm and the lever, the transmission ratio between the rocking arm and the lever is substantially equal during tilting of the rocking arm and rotation of the lever. Changes to. Due to this substantial change in the transmission ratio, the locus of movement of the valve is not only determined by the shape of the cam, but in part by the changing transmission ratio of the rocker arm. As a result, the degree of freedom in designing the shape of the cam is increased. By properly selecting the cam, the swing arm, and the lever, it becomes possible to use a motion locus that cannot be realized by the cam alone. If the angle is outside the above-mentioned angle range, the movement locus of the valve has no or negligible effect.

In one embodiment of the combustion engine of the present invention, a rotary roller is provided on at least one of the rocking arm and the lever so that the rocking arm and the lever roll relative to each other.

Rolling the rocker arm and lever relative to each other avoids frictional forces that cause unwanted wear.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

A combustion engine 1 shown in FIG. 1 is provided with a combustion chamber 2 located inside a cylinder. Two entrance channels 3
And one outlet channel 4 are connected to the combustion chamber 2. Inlet channel 3 and outlet channel 4 in combustion chamber 2
The passage can be closed by a valve 5 (two intake valves and one exhaust valve). Each valve 5 comprises a valve rod 6, which is provided on one side remote from the valve 5 with a disc 7. The valve rod 6 is attached to the housing 8 of the combustion engine 1. A compression spring 9 is arranged between the housing 8 and the disc 7, which pushes the valve 5 into the closed position shown in FIG. Further, the combustion engine 1 is provided with a camshaft 10. The camshaft 10 is located between the valves 5 arranged in a V-shape in the inlet channel 3 and the outlet channel 4. The camshaft 10 extends perpendicularly to the plane of the drawing in FIG. 1 and is provided with a plurality of cams 11, 12 so that each valve 5 is associated with two different cams 11, 12. The camshaft 10 can be moved in a direction perpendicular to the plane of the drawing by means well known per se (not shown), whereby either the cam 11 or the cam 12 can be moved depending on the position of the camshaft 10. Bind to 5.
The camshaft 10 can rotate around the shaft 13 in the direction indicated by the arrow P1. A swing arm 14 located above the camshaft 10 is provided in the combustion engine 1. The swing arm 14 can be tilted about the tilt axis 15 in the direction indicated by arrow P2 and in the opposite direction. The ball bearing 17 provided at the one end 16 of the swing arm 14 constitutes a cam follower, which corresponds to the position of the cam shaft 10 and the cam 11
It hits the cam 12. One end 18 of the swing arm 14 located on the other side of the tilt shaft 15 abuts one end 20 of a lever 21, and a ball bearing 19 is provided at the end 20 of this lever. Another state of the swing arm 14 and the lever 21 is shown in FIG. Lever 21 pivots about pivot pin 22 in the direction indicated by arrow P3 and in the opposite direction. As is clearly shown in FIG. 2, the lever 21 is provided with three fingers, two fingers 23 respectively abutting the disc 7 of the valve 5 closing the inlet channel. An intermediate finger 24 forms the end 20 of the lever about which the ball bearing 19 is mounted for rotation.
As the camshaft 10 rotates in the direction indicated by the arrow P1, the swing arm 14 tilts, and as a result, the lever 21
Rotates in the direction indicated by arrow P3. The valve 5 moves in the direction indicated by the arrow P4 by the rotation of the lever 21. As a result, the passage of the inlet channel 3 to the combustion chamber 2 is opened. Only one valve 5 is shown for clarity.

In order to open and close the outlet channel 4, the combustion engine 1 is provided with further swing arms and levers, which operate in the same way as the swing arm 14 and lever 21 shown in FIG. Is operated by the camshaft 10. Only one finger 23 is provided on the lever that opens the discharge valve 5. This is because the combustion chamber 2 has only one outlet channel 4. If the combustion chamber 2 were provided with two outlet channels, it would use the same lever 21 used to operate the intake valve 5.

The operation of the combustion engine of the present invention will be described in detail. Arrow P
When the camshaft 10 is rotated in the direction indicated by 1, the ball bearings 17 roll on the outer surfaces of the cams 11 and 12,
It is moved upwards as seen in FIG. The cam 11 or the cam 12 is engaged depending on whether the rotation speed of the combustion engine is high or low.
The swing arm 14 is moved to P by the movement of the ball bearing 17.
Tilt in the direction indicated by 2. The position of the oscillating arm 14 indicated by shading is reached when the cam 11 is used.
4 is the maximum limit position. Swing arm 14 shown in FIG.
In the position of, the flat lower side 25 of the swing arm 14 has the lever 2
The ball bearing 19 of No. 1 is contacted with the contact 26. The line from the tilt axis 15 of the swing arm 14 to the contact 26 and the contact 26
The angle β formed by the line from the to the axis of rotation 22 of the lever 21 lies between 80 ° and 170 °, and more specifically 125 °. This angle β is not shown in FIG. 1 but is shown in FIG. 4 because the figure becomes complicated. This angle β is the valve 5
Is measured in the closed position. The contact 26 is above the arc 27. This arc has a tilt axis 15 as its center. Due to the inclination of the swing arm 14, the swing arm 14
When using the cam 11, it moves to the position shown in shade in FIG. As can be seen in FIG. 1, the lower side 25 of the swing arm 14 pushes down on the ball bearing 19 and moves the lever 21 in the direction of arrow P
Rotate in the direction indicated by 3. As a result, the valve 5 is moved to the arrow P.
Move in the direction indicated by 4. During this tilting and rotation, the contact point 26 between the lower side 25 of the swing arm and the ball bearing 19 is the arrow P.
5 is moved in the direction shown. This new contact 26 'lies on an arc 29 with the tilt axis 15 as the center, so that the radius of the arc 29 is smaller than the radius of the arc 27. As a result, the instantaneous transmission ratio of the swing arm 14 is changed. As a result of the continuously changing transmission ratio of the oscillating arm, the movement of the valve 5 is not only changed by the shape of the cam 11 or 12, but also by the continuously changing transmission ratio of the oscillating arm 14. In the swing arm 14 shown in FIG. 1, its lower side 25 is at a height of a distance d above the tilt axis 15. Another variation of the transmission ratio is obtained by bending the contour of the lower side 25 of the rocker arm and / or by increasing or decreasing the distance d to the tilt axis 15.

FIG. 3 is a schematic diagram of changes in the transmission ratio of the swing arm. In FIG. 3, the lower side 25 of the swing arm 14 passes through the tilt shaft 15 of the swing arm 14. The diameter of the ball bearing 19 of the lever 21 can be ignored. Tilt axis 1 for simplicity
5, only the lower side 25 of the swing arm 14, the pivot pin 22 of the swing arm 14 and the lever 21 are shown. Lever 2
When 1 rotates, the ball bearing 19 follows an arc 30. In the initial state of the rocker arm and lever, the ball bearing 19 contacts the lower side 25 at the contact point 31 '. When the swing arm 14 is tilted stepwise by the angle α, the lever 21 is rotated in the direction indicated by the arrow P3, and the ball bearing 19 is moved over the arc 30. Ball bearing 1
The contact point 31 between 9 and the lower side 25 is in the direction indicated by the arrow P5,
Moving towards the tilt axis 15. Lower side 25 of swing arm 14
Point 33 (which was located at contact 31 ') is arc 3
Moved along 4. The distance between the point 33 and the contact 32 increases as the swing arm 14 tilts in the direction indicated by the arrow P2. The transmission ratio of the oscillating arm 14 is determined by the ratio of the radius R1 from the tilt axis 15 to the contact point of the cams 11, 12 with the ball bearing 17 and the distance between the tilt axis 15 and the contact point 31. Contact 31 goes from 31 'to 31''
.. As a result of moving to 31 "'", the transmission ratio becomes smaller as the angle changes. This can be seen in FIG. The angle at which the lever 21 pivots (leaving the tilt of the rocking arm 14 at the angle .alpha.
This is because as 1 is moved, it becomes smaller. When the swing arm 14 is tilted at a constant speed, the point 33
Moves along the arc 34 at a constant speed. However, the ball bearing 19 is moved in the direction indicated by the arrow P3 while decelerating. In this way, the valve 5 can be opened at a reduced speed by using the cam in which the swing arm is tilted at a constant speed. This makes cam 1
The shapes of 1 and 12 are relatively simple. In the combustion engine of FIG. 1, the distance between the contact 31 and the rotating shaft 22 also changes. The ball bearing 19 has certain dimensions so that different contacts appear on different parts of the ball bearing 19 and strike the underside 25 of the rocker arm 14.

FIG. 4 shows the valve 5 closed and FIG. 5 shows the valve 5 open. Arrows P10 and P1
0 ′ indicates the speed at which the valve 5 is moved when the swing arm 14 is tilted at the angular speed W. In the valve position shown in FIG. 4, the contact point 26 between the rocking arm 14 and the ball bearing 19 is a distance r1 from the tilt axis 15. The ball bearing 19 experiences a velocity wr1 in the direction indicated by arrow P7. Arrow P7 indicates the direction and magnitude of the velocity experienced by the ball bearing 19. From this instantaneous speed P7, the speed P at which the ball bearing 19 rotates about the rotation axis 22
In order to obtain 8, the arrow P7 is projected on a line orthogonal to the line 39 connecting the rotary shaft 40 of the ball bearing 19 and the rotary shaft 22. The contact point 41 between the lever 21 and the disc 7 is moved at an instantaneous speed P9. The magnitude of this instantaneous speed P9 is determined by the instantaneous speed P8, and its direction is perpendicular to the line connecting the rotating shaft 22 and the contact 41. The valve 5 is moved at an instantaneous speed P10 in the direction indicated by arrow P4, which is a projection of the speed P9 in the direction indicated by arrow P4.

In the open state shown in FIG. 5, the contact 26 is away from the tilt axis 15 by a distance r1 ', which is a distance r1.
Shorter. The speed P7 'at which the contact 26 moves is small,
And it is equal to wr1 '. In the same manner as shown in FIG. 4, the speed P7 ′ is passed through the speed P8 ′ of the ball bearing 19 with respect to the rotary shaft 22, the speed P9 ′ of the contact 41 with respect to the rotary shaft 22, and the valve in the direction indicated by arrow P4. 5
Can be converted into the speed P10 '. The magnitude of the speed of the valve 5 indicated by the length of the arrow P10 ′ is considerably smaller than the magnitude of the speed indicated by the arrow P10. This is a result of the reduced length r1 and the increased angle α between the connecting line 39 and the arrow P7.

Among others, in particular the shape of the lower side 25 of the rocker arm 14 and its position relative to the tilt axis 15, the size of the ball bearing 19, the tilt axis 15, the pivot axis 22 and the rotary axis 40. By selecting the relative position, the shape of the cam that causes the valve to follow the desired trajectory can be determined. In this way, a relatively large amount of design freedom is obtained and the desired deceleration, acceleration or speed can be achieved while using a relatively simple cam shape. Instead of moving the camshaft axially, it is also possible to change the cam in other ways known per se.

[Brief description of drawings]

FIG. 1 is a sectional view of a combustion engine of the present invention.

2 is a perspective view of a portion of the combustion engine of FIG.

FIG. 3 shows movements of a swing arm and a lever of the combustion engine of the present invention.

4 shows a valve closed state of the combustion engine shown in FIG.

5 shows the valve of the combustion engine shown in FIG. 1 in an open state.

[Explanation of symbols]

1: combustion engine, 2: combustion chamber, 3: inlet channel, 4:
Outlet channel, 5: valve, 6: valve rod, 7: disc,
8: housing, 9: compression spring, 10: camshaft,
11: cam, 12: cam, 13: axis, 14: swing arm, 15: tilt axis, 17: ball bearing, 19: ball bearing, 21: lever, 22: turning pin, 2
3: finger body, 24: finger body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 596018780 Dr. Hub van Doornew eg 1, 6121 RD Born, The Netherlands (72) Inventor Derek Bernard Woodcroft The Netherlands, 5708 H. Hermond, Holtzedick 133

Claims (6)

[Claims] 1. A cam shaft, a swing arm tilted about the tilt axis by the cam shaft, a lever that turns about a rotation axis by the swing arm, and can be moved from a closed position to an open position by the lever. And a valve so that the relative position of the contact point where the rocking arm contacts the lever changes in accordance with the tilt amount of the rocking arm. Combustion engine, wherein the angle between the line to the contact and the line from the contact to the pivot is within 80 ° to 170 ° in the closed position of the valve. 2. The combustion engine according to claim 1, wherein a rotating roller is provided on at least one of the swing arm and the lever so that the swing arm and the lever roll on each other. 3. The combustion engine according to claim 2, wherein the rotating roller is a rolling bearing located above the lever. 4. The lever comprises three fingers, the middle finger hits the swing arm and the two outer fingers hit two valves which move against the force of the spring. The combustion engine according to claim 1 or 2. 5. A combustion engine according to claim 1, wherein the camshaft comprises at least two cams arranged side by side, which cams are alternately connected to the rocker arm. 6. The combustion engine according to claim 1, wherein the swing arm and the lever form an obtuse angle with each other.