DE4026264A1 - IC engine with variable camshaft - produces varying, inlet valve, movement pattern, controlling load without throttle valve - Google Patents

Abstract

The engine camshaft (1) is axially displaceable, and the cam is cylindrical in its base circle, while the shape of the cam curve is different on the face sides, so that the surface of the cam path is conical and assymetrical. In the axial position of the camshaft (1) where the tractive lever (4) slides on the face side of the cam, the cam lift curve and the opening angle are the greatest. If the camshaft moves in the other axial position where the tractive lever (4) slides on the other face side of the cam, the cam lift curve and opening angle are the smallest, and phase-displaced in relation to the position on the first face side. By virtue of the camshaft movements, the inlet valve (3) opening point is variable while the valve closure point is the same in each load range. USE/ADVANTAGE - To control the load of an IC piston engine without the use of a throttle valve.

Description

The invention relates to a camshaft arrangement according to the Preamble of claim 1.

With conventional, standard engines, certainly in the strong Dimensions of the unchangeable control cross-sectional areas of the valve the torque curve, the nominal speed, the Idling quality, fuel consumption and exhaust emissions the machine.

For quantity controlled engines, with the system in which the Valve lift curves in stroke and opening times are variable in order to regulate the load control without throttle to the cargo To reduce change work, the inlet valve opens conventionally and closes early depending on the amount of charge required and fast.

In this invention, the inlet closing point does not change or is caused by axial phase shift of the camshaft changed, however, the inlet opening point can be changed as required of the degree of filling are steplessly brought forward.

An axially displaceable camshaft ( 1 ) creates a variable cam elevation curve in that the cam track ( 12 ) is cylindrical in its base circle (X), but the cam curves on the end faces I and II, FIG. 8, are different. Thus, the cam track ( 12 ) between the end faces (I and II) in the area of the cam base circle (X) to a cylindrical roller and between the cam curves on the end faces (I and II) creates a surface of the cam track ( 12 ), which is conical and is asymmetrical.

If the camshaft ( 1 ) is in a position where the thrust dome ( 9 ) of the rocker arm ( 4 ) slides on the side of the cam curve (I), the largest and longest valve lift results. However, if the camshaft ( 1 ) changes the axial position towards the cam curve (II), the valve lift becomes shorter and lower and the intake begins later. However, if the run-on cap ( 9 ) of the rocker arm ( 4 ) slides on the side of the cam curve (II), the inlet begins at the latest and the smallest and shortest valve lift is carried out.

If you look at the cam ( 2 ) from the end face, Fig. 8, z. B. between ° KW 600 and ° KW 260 the cylindrical part of the cam track ( 12 ), which is also the cam base circle (X) and appears in Fig. 9 as the dashed line (X).

But if you look at the cam ( 2 ) in Fig. 8 z. B. between ° KW 340 and ° KW 600, the cam track ( 12 ) between the cam curve on the end face (I) and the cam curve on the end face (II) is shown in FIG. 9 as a diagonal line, with FIG . 9, the axial positions of the rocker arm can be seen (4) (vertical lines) to the camshaft (1), as well as the angle of inclination of the cam track and the height of the cam curve in the radial positions (° KW) and the intake beginning, which at the intersection the diagonal line with the dashed line of the cam base circle (X).

In order to make the cam elevation curve ( Fig. 10) visible, the intersections of the axial position of the rocker arm ( 4 ) to the cam ( 2 ) can be seen in the horizontal lines and the associated curves from 1-8 by using the horizontal lines as The cam base circle (X) is considered and the distance of the horizontal to the diagonal lines of FIG. 9 is assigned to the respective vertical line of ° KW 340-620 and transmitted.

From the cam elevation curves of FIG. 10, the larger valve lift curve of FIG. 11 results from the lever transmission of the rocker arm ( 4 ).

From the valve lift curves of Fig. 11 it can be seen that in the axial cam position 1 the valve lift curve is longest and largest, whereas in the axial cam position 8 the valve lift curve is shortest and smallest. The point at which the inlet valve ( 3 ) opens can be seen if, for. B. in the axial cam position 6 the line of the valve lift curve in the vertical line ° KW 500 intersects the horizontal line or the cam base circle (X).

The rocker arm ( 4 ) performs two functions, whereby it increases the elevation of the cam track ( 12 ) via the bucket tappet ( 8 ) to the inlet valve ( 3 ) through a lever transmission, on the other hand it can be supported by its ball socket bearing ( 5 and 6 ) his ramp ( 9 ) the inclinations of the cam track ( 12 ) adjust non-positively, his movements over the parts ball socket ( 5 ), ball ( 6 ), slide ( 7 ), cup tappet ( 8 ) with guide groove for slide ( 7 ) the inlet valve ( 3 ) transmits. On the opposite side is the rocker arm ( 4 ) over the ball socket ( 5 ), the ball ( 6 ) on the cup tappet ( 10 ), which is pressed by the compression spring ( 11 ) against the rocker arm ( 4 ), and has the task hold the rocker arm ( 4 ) in the area where the cam track runs within the cam base circle (X) forcefully on the cam track ( 12 ), Fig. 1. The cam track ( 12 ), Fig. 2, 3 and 4, on or outside the cam base circle (X), the rocker arm ( 4 ) presses the bucket tappet ( 10 ) with its end face onto the bottom surface of the guide cylinder ( 13 ), the further movement of the rocker arm ( 4 ) then passing onto the inlet valve ( 3 ).

The fact that in this system z. B. for an in-line engine the adjustment range of the camshaft ( 1 ) is limited to the space of cylinder diameter plus one cylinder wall, the cam elevation is much smaller than the valve lift by lever transmission of the rocker arm ( 4 ), so that the inclination of the conically asymmetrical cam ( 2 ) can be kept low.

The change in the cam curve or cam track ( 12 ) from inside to outside of the cam base circle (X) resulting jerky transition, which causes a shock to the mechanical transmission parts between the camshaft ( 1 ) and the inlet valve ( 3 ) is caused by a in Bucket tappet ( 10 ) integrated hydraulic shock absorber removed. This is e.g. B. performed as follows: The cylinder ( 22 ) in the tappet housing ( 13 ) has a control edge, the lower edge of the shock absorber piston ( 24 ) above this control edge, the cylinder ( 22 ) is filled with oil via the oil line ( 17 ). When the shock absorber piston ( 24 ), which is conical on its lower part, falls, the throttle cross section ( 25 ) between it and the control edge of the cylinder ( 22 ) becomes smaller and smaller, a pressure builds up in the cylinder ( 22 ), so that the check valve ( 18 ) closes; The oil in the cylinder ( 22 ) is now pressed through the increasingly narrow throttle cross-section ( 25 ), so that the inlet valve ( 3 ) rises and the tappet ( 10 ) gently touches the bottom surface of the guide cylinder ( 13 ). Thus, with the correct design of the shock absorber, the inlet valve ( 3 ) opens smoothly. After closing the inlet valve ( 3 ) the tappet ( 10 ) with the shock absorber piston ( 24 ) by the compression spring ( 11 ) is pushed up again, so that the process begins again.

To change the timing of the engine, the camshaft ( 1 ) with its camshaft bearings ( 20 ) in the elongated bushes of the camshaft bearing blocks ( 21 ) is set in motion axially by a camshaft adjuster; thus the inlet opening point can be moved back and forth continuously, the inlet closing point not changing. For example, there is a small stroke and a short opening angle of the inlet valve ( 3 ) around and after bottom dead center, by the vacuum that has formed during the intake stroke in the combustion chamber, occurs when the inlet valve ( 3 ) is open in the area of Valve plates a high flow, so that a strong turbulence forms in the combustion chamber, which results in a good mixture preparation when idling, on the other hand, the remaining vacuum is used to reduce the gas exchange. With increasing partial load, the stroke increases, the opening angle is longer and brought forward, whereby due to the later opening inlet valve ( 3 ) there is still enough vacuum in the combustion chamber, depending on the load point, to allow the required mixture at the inlet valve ( 3 ) from the opening point to the closing point in To offset turbulence. It can be concluded from this that a good mixture formation also takes place in the part-load ranges.

As the load increases, the consumption differences will decrease the load control through the variable valve control the throttle control is getting smaller, as we know the throttle losses decrease.

At full load, a good degree of delivery and torque increase can be achieved due to the possibility of the late closing point of the inlet valve ( 3 ) and the basic contour of the cam shape.

However, it is necessary that the inlet closing point be in phase must be moved, so in the camshaft adjuster (axial) a phase shift (radial) z. B. by oblique toothing can be integrated, so that the inlet valve opening  start earlier in idle and part load. This can cause the expansion in the intake stroke to end earlier, whereby the low temperature level in the range of bottom dead center is raised and the gas exchange work is reduced. With increasing load, the opening angle becomes larger and shifts to an earlier opening point in the Intake stroke in the direction of the O.T., the closing point moves but back to a smaller extent until the has set the ideal opening angle or valve lift curve.

In this construction, due to the good mixture formation and Reduction of the charge change in idle and in the part load ranges up to full load good values in consumption, performance and expected emission.

Claims (16)

1. Device for a cam-controlled reciprocating piston machine with a camshaft ( 1 ) through which the movement of the inlet valve ( 3 ) is variable. 2. Valve control according to claim 1, characterized in that the camshaft ( 1 ) is axially displaceable. 3. Valve control according to claims 1 and 2, characterized in that the cam ( 2 ), Fig. 8, is cylindrical in its base circle, on the other hand, the shape of the cam curve on the end faces (I) and (II) is different, so that the surface of the cam track ( 12 ) is conical and asymmetrical. 4. Valve control according to claims 1, 2 and 3, characterized in that z. B. the cam curve on the end face (I), Fig. 8, by its shape z. B. ° KW 340 to 600 is the largest and longest elevation, compared to the cam curve on the end face (II), Fig. 8, which z. B. runs between the radial positions ° KW 260 to 520 within the cam base circle (X), then swings between the position ° KW 520 to 600 over the cam base circle, being the smallest, shortest and phase-shifted cam elevation. 5. Valve control according to claims 1, 2, 3 and 4, characterized in that in the axial position of the camshaft ( 1 ), where the rocker arm ( 4 ) on the end face (I) of the cam ( 2 ) slides, the cam elevation curve and the opening angle is the largest. In case the camshaft (1) in the axial position where the cam follower (4) slides on the end face (II) of the cam (2), the cam lift curve in the hub opening is angularly smallest and phase shifted from the position on the front side (I ). 6. Valve control according to claims 1, 2, 3, 4 and 5, characterized characterized in that by the rocker arm ratio Cam lift curve increased to the valve lift curve becomes. 7. Valve control according to claims 1, 2, 3, 4, 5 and 6, characterized in that the rocker arm ( 4 ) with its ball sockets ( 5 ) on the balls ( 6 ) on the tappets ( 8 ) and ( 10 ) mounted is, the rocker arm ( 4 ) with its thrust cap ( 9 ) can adjust the inclinations of the cam track ( 12 ) non-positively. 8. Valve control according to claims 1, 2, 3, 4, 5, 6 and 7, characterized in that in a guide groove of the cup tappet ( 8 ), Fig. 1, 2 and 5, z. B. a slider ( 7 ), in which the ball ( 6 ) is mounted, slides, the result of the up and down movements of the rocker arm ( 4 ) resulting Verla tion of the pressure point, as well as the lateral displacement forces, which takes up by the movements and inclination of the cam track ( 12 ) arise. 9. Valve control according to claims 1, 2, 3, 4 and 5, characterized characterized in that instead of claims 6, 7 and 8 an adjustment element on a conventional or fork shape, e.g. B. for two inlet valves, designed rocker arm is mounted, which adapts to the cam track. 10. Valve control according to claims 1, 2, 3, 4 and 5, characterized characterized in that instead of claims 6, 7, 8 and 9 Hydraulic cam lift increased to the valve lift becomes. 11. Valve control according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10, characterized in that the camshaft ( 1 ), Fig. 1, 2, 5 and 6, with their camshaft bearings ( 20 ) in the bushings of the camshaft bearing blocks ( 21 ) can carry out the radial and axial movements. 12. Valve control according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 and 11, characterized in that by the pressure spring ( 11 ), Fig. 1, 2, 3 and 4, the bucket tappet ( 10 ) presses the rocker arm ( 4 ) with its starting cap ( 9 ) against the cam track ( 12 ) in the area where the cam track ( 12 ) runs within the cam base circle (X) so that the rocker arm is always non-positive, the tappet ( 10 ) lies in the area of the opened inlet valve ( 3 ) with its end face on the bottom surface of the guide cylinder ( 13 ). 13. Valve control according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12, characterized in that by changing the cam track ( 12 ) from inside to outside of the cam base circle ( X), depending on the axial position of the camshaft ( 1 ), the more or less strong impact on the camshaft ( 1 ) on the inlet valve ( 3 ) with the associated transmission parts z. B. is absorbed by the hydraulic shock absorber integrated in the tappet ( 10 ), FIGS. 1, 2 and 7. 14. Valve control according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 and 13, characterized in that the inlet opening point is variable, on the other hand, the inlet closing point of the inlet valve remains ( 3 ) the same in every load range. 15. Valve control according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 14, characterized in that z. B. is at idle, the inlet opening point in the area of bottom dead center, with the increase in the load range, however, by the axial displacement of the camshaft ( 1 ) moves continuously to an earlier point in time, so that the full opening angle is used in the full load range. 16. Valve control according to claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 and 15, characterized in that the inlet closing point is infinitely variable in the idle and part-load range compared to claim 14 can be moved to an earlier point in time, z. B. in the camshaft adjuster, which fixes the camshaft ( 1 ) depending on the load range in the required axial position, a phase shift is integrated by helical toothing of the camshaft drive, the variable opening angle migrating in the phase shift.