DE102004049538A1 - Fully variable lift valve controller for internal combustion engine has intermediate element in form of pivotable rocker arm acted upon by cam or camshaft at first engagement surface with control block at free end - Google Patents

Abstract

The internal combustion engine has a camshaft (1) and at least one rocker finger (3) acting on a lifting valve (5) and an intermediate element (2) between the rocker finger and the camshaft. The intermediate element is in the form of a rocker arm that can be pivoted about an axle (C2) and that is acted upon by the cam or camshaft at a first engagement surface (2h) and that has a control block (2g) at its free end.

Description

The Inventions describe fully variable lift valve controls for internal combustion engines.

With a fully variable lift valve control can be in particular a spark ignition Operate engine throttle free, which manages the with conventional throttling over wide load conditions to minimize occurring charge exchange losses. This is possible improve the performance and torque characteristics as well as fuel consumption and reduce pollutant emissions.

Furthermore is characterized by such a fitted internal combustion engine in the lower Speed range through improved response and a increased Smooth running out.

Fully variable Hubventilsteuerungen are usually designed as a so-called latching cam gear, which the experts by the relevant patent literature (eg DE 101 36 612 . DE 38 33 540 WO 02/053881) are known per se in their basic mode of operation.

Around an effective throttle-free operation in idle and part load range to enable is in such Hubventilsteuerungen next to the valve and the opening duration (NW-grade) considerably reduced to a desired Control strategy of the "early intake concludes "to be able to realize It is advantageous, the camshaft with a known per se phase adjustment to provide around the valve closing time Within a Verstellwinkels largely free to choose can.

The Load is at a fully variable lift valve control through the opening cross-section determines the respectively adjusted elevation curve of the intake valve.

Around a greatest possible Potential of a throttle-free load control is to open it desirable in the partial load range, the intake valve as possible early close. To the cylinder at very short opening times provide the required amount of charge in the partial load to be able to However, it is necessary here, the opening cross-section through a steeply rising and falling survey curve with a high realize relative valve acceleration.

at known fully variable Hubventilsteuerungen with a kinematic Design for a maximum allowable Valve acceleration at high speeds increases the relative valve acceleration the partial load usually off.

Basically to further reduce charge cycle losses through shortest possible opening times however desirable, at low engine speeds and partial strokes one to achieve relative valve acceleration, which is much higher as at full load.

task Therefore, it is the inventions in particular, fully variable Hubventilsteuerungen to create, with which the highest possible relative valve acceleration kinematically generated at the partial load.

in this connection should the Hubventilsteuerungen be made as stiff and compact as possible, have a low tolerance sensitivity and cost-effective too be finished. According to the invention, the task by the claims 1 or 2 solved. advantageous Embodiments are shown in the subclaims.

The inventions are intended in embodiments with the aid of the drawing 1 and 2 be explained.

It becomes the control mechanism of a single inlet valve 5 ( 1 ) and two parallel operated inlet valves 5 ( 2 ) of a single cylinder, wherein the Hubventilsteuerung is preferably provided for multi-cylinder engines.

1 , shows a four-membered lift valve control from the end face of the cylinder head during the base circle phase, wherein the adjusting shaft 6 is adjusted in its angular position to a maximum stroke.

2 , shows a five-membered lift valve control from the end face of the cylinder head as a full section through the cylinder plane during the base circle phase, wherein the adjusting shaft 6 is adjusted in its angular position to a maximum stroke.

Here is the valve actuator 3 as so-called fork rocker arm 3 executed, which two lift valves 5 operated in parallel.

functionally identical Components or component sections are the same in both figures Provided with reference numerals.

The return springs 7 the gate lever 2 ( 1 ) and 22 ( 2 ) are shown only schematically for a better overview of the drawings.

First, the Hubventilsteuerung according to 1 be explained in more detail.

In a cylinder head, the camshaft rotating about a fixed axis C1 is 1 vorgese hen.

Furthermore, the drag lever 3 with its forked one end on the rotatable adjusting shaft 6 mounted pivotally about the stationary center C3 and acts with its free end on, in the rocker arm 3 integrated hydraulic valve clearance compensation element 3a on the lift valve 5 one.

The oil supply of the valve clearance compensation element 3a takes place here by the adjusting shaft 6 therethrough.

To a mounting of the finger lever 3 on the, as eccentric shaft 6 designed adjusting shaft 6 to allow the rocker arm 3 optionally be provided with an open bearing shell or with a divided and sealed with a bearing cap bearing bore. Likewise, a closed bearing bore in the drag lever 3 conceivable, wherein the control eccentric only during assembly, for example, by a dowel pin, a clamp or by shrinking with the adjusting 6 is added.

Between the drag lever 3 and the camshaft 1 is a one-piece, partly forked gate lever 2 provided, which advantageously via an intermediate Abgrifvorolle 2h from the cam of the camshaft 1 is charged.

At its lower end is the gate lever 2 in this case provided with an axle, on which axially centrally a roller bearing roller 2c is stored around the center C2.

The gate lever 2 this is due to a preloaded return spring 7 (Lost-motion element) is acted upon at its upper end by a force F, whereby the attachment of the Abgriff 2h on the camshaft 1 and the installation of the lower roller 2c on the control eccentric of the adjusting shaft 6 is always guaranteed.

The return spring 7 can be formed for example by a bow-shaped Torsionschenkelfeder or by a translationally guided compression spring or a tension spring. The control eccentric of the adjusting shaft 6 can also be designed differently from the illustrated cylindrical shape, whereby the adjustment characteristic can be selectively influenced.

The axle with the center C2 projects axially on both sides via the crank lever 2 out and carries at its protruding ends on both sides each a plain bearing roller 2i to which the rocker arm 3 over the lower pressure surfaces 3b two circular arcuate slots on the crank lever 2 supported.

Here, the slots may be widened in the lower area by laterally outwardly projecting noses to a wider pressure surface 3b for the plain bearing rollers 2i to be able to represent.

Alternative to the plain bearing rollers 2i in this case also two juxtaposed, pivotally mounted about the axis C2, arcuate sliding blocks can be provided, which are guided in the oblong holes, whereby advantageously the surface pressure can be further reduced.

The printing surface 3b describes during the valve lock (ie with the lift valve closed 5 ) a radius contour R2 around the stationary center C4 of a, over several cylinders extending thru axle 4 on which a roller bearing roller 4a is rotatably mounted around the center C4.

Alternative to a thru axle 4 can be a fixed bearing axis with a center C4 for the cam followers 4a also oriented, for example, on the camshaft bearing cap in a semicircular receiving tray and screwed over a transverse bore from above with the lids or clamped over Spannpratzen. For example, a plurality of receiving shells arranged one behind the other can be manufactured particularly precisely over a milling or broaching process over the cylinder head longitudinal axis.

On the cylindrical surface of the cam follower 4a the gate lever is supported 2 with its upper end over a control gate 2g which of a valve latch section 2d , which describes a radius contour R1 about the pivot center C2, via a start-up ramp 2e in an outwardly extending lifting section 2f passes.

Furthermore, the adjusting shaft 6 be rotated about the bearing axis C3 via an adjusting device (actuator), not shown, wherein, for example, an electric servomotor via an intermediate worm gear with the adjusting 6 is in drive connection.

In the following it is assumed that the Hubventilsteuerung in a position according to 1 located. (Full load)

Will now the camshaft 1 set in a rotation, so the cam acts on the Abgriff 2h on the crank lever 2 a, which in this case deflects about the pivot axis C2, wherein the sliding lever 2 over the ramp 2e with subsequent lifting section 2f through the cam follower 4a a downward movement is forced on.

Here, the gate lever acts 2 over the two plain bearing rollers 2c on the pressure surfaces arranged on both sides 3b of the rocker arm 3 a, which in this case is deflected about the axis C3 and the lifting valve 5 maximum opens.

Here, the lower roller rolls 2c of the scenery lever 2 along the control contour of the control eccentric on the adjusting shaft 6 from.

In the further course follows the Abgriff 2h the descending cam edge, wherein the crank lever 2 and the rocker arm 3 due to the restoring forces of valve spring and return spring 7 take back their starting positions.

This is the lifting valve 5 closed again.

In the following it is assumed that the adjusting shaft 6 is rotated by 90 degrees clockwise by the adjusting device. (Part load operation) Here, the gate lever moves 2 its position by a tilting movement in a clockwise direction.

Here, the stationary cam roller rolls 4c along the valve gate section 2d on the gate lever 2 At the same time, the lower roller rolls 2c of the scenery lever 2 along the control contour of the control eccentric and the plain bearing rollers 2i of the scenery lever 2 roll along the pressure surfaces 3b of the rocker arm 3 from.

After relocating is the scenery lever 2 approximately in the middle of the valve latch section 2d with the stationary roller 4a in contact and the lower plain bearing rollers 2i are approximately in the middle of the slot with the pressure surfaces 3b of the rocker arm 3 in contact.

Will now the camshaft 1 again set in a rotation, then again the cam on the Abgriff 2h on the crank lever 2 effective, the gate lever 2 in a first phase is initially deflected only about the pivot axis C2, since the crank lever 2 in this first phase legendary about the valve stop section 2d with the radius R1 with the stationary cam follower 4a in contact.

Only in the further movement sequence runs the control scene 2g in a second phase with the start-up ramp 2e and a subsequent subsection of the lifting section 2f on the cam follower 4a on.

This is the scenery lever 2 a renewed, but shorter downward movement on forced, with the gate lever 2 again over the plain bearing rollers 2i on the printing surfaces 3b of the rocker arm 3 acting, which in turn undergoes a deflection movement about the axis C3, but with a shortened opening duration and a reduced valve lift is generated. (Partial load operation)

With the stroke valve control according to the invention let yourself Of course also represent a zero stroke. (Valve deactivation)

For this the adjusting shaft is rotated by a further 90 degrees clockwise, where the crank lever tilts further in a clockwise direction.

In this position, the cam of the camshaft again on the crank lever 2 effective, this is legendary with the valve-stop section during the entire cam phase 2d in contact with the gate lever 2 Legendally deflected about the pivot axis C2. Here, the drag lever remains 3 in its position and the lift valve 5 remains completely closed.

By any rotation of the adjusting shaft 6 Both the valve lift and the opening duration can be infinitely varied from a maximum lift curve to a valve shutdown.

Substantially different from the known state of the art are in this case, in particular, the lever ratios which are relevant for a relative valve acceleration as a result of the changed contact point between an intermediate element (crank lever 2 ) and a valve actuator (drag lever 3 ) significantly changed by the adjustment.

By moving the axial center C2 of the slide bearing rollers 2i in the direction of the finger follower axis C3, a considerably increased relative valve acceleration is kinematically generated in the partial load, whereby very short opening times in the partial load can be achieved. This allows the use of an additional phase adjustment for the camshaft 1 a very early closing of the lift valve 5 , wherein the charge cycle losses are further reduced compared to the known prior art.

Here, the Hubventilsteuerung is very stiff and compact designed with direct force paths. The valve detent during the cam phase is in this case exclusively by the easy-to-manufacture radius contour R1 of Ventilrastsektion 2d to the pivot axis C2 on the crank lever 2 defined, whereby a low tolerance sensitivity is ensured with respect to the representation of a clear valve latch within a cam phase. Further, the Hubventilsteuerung is very inexpensive to manufacture by the small number of easy-to-manufacture components.

Also in the inventive Hubventilsteuerung given the option, in a version with two adjoining cam followers 3 and globe valves 5 to operate the Hubventilsteuerung with a so-called Ventilphasing.

For this purpose, control contours two adjacent control eccentric of a cylinder on the adjusting 6 be provided with differently designed control contours. As a result, for example, a lift valve can be opened during idling and in the lower part-load range, whereby the other remains closed.

hereby let yourself For example, improved charge mixing by a generated Realizing a twist, resulting in a faster and thus more effective one Burning leads.

Likewise, different from the embodiment 1 a common drag lever with two parallel operated lift valves 5 be provided, which in this case can be designed as a known per se Gabelschlepphebel.

In this case, a single link lever is preferred 2 arranged in the cylinder plane, as an alternative to the plain bearing rollers 2i the gate lever 2 may also be provided at its lower end with a cylinder jacket-shaped sliding surface, which concentric to the axis C2 of the roller 2c is arranged and via a, provided in the cylinder plane pressure surface 3b on the fork rocker arm acts centrally on this. Here is the print area 3b formed on a crossbeam in the lower region of the forked rocker arm. Basically, the roller can 2c also be replaced by another sliding surface, which in this case is directly in contact with the control contour of the control eccentric.

In such an embodiment, this further sliding surface is likewise formed by a cylinder jacket surface which likewise concentric with a pivot axis C2 of the crank lever 2 is located.

This represents the simplest and least expensive embodiment of the Hubventilsteuerung. As a result, the number of components and the Moving mass reduced to a minimum, but with increased friction must be accepted.

To compensate for a deviation caused by manufacturing tolerances of the lift curves of several valves and / or cylinders, the axis of the cam follower 2h designed eccentrically and in the crank lever 2 be executed rotatable and fixable.

The bearing axis of the tiller 2h For this purpose, for example, be designed as eccentric dowel screw, and clamped by a basic setting of Abgriffrollenposition with a nut on the crank lever.

Alternatively, the control eccentric can be designed as a single component and on the adjustment 6 be changeable fixable by a clamping device in its angular position.

In the 2 a further inventive Hubventilsteuerung is shown with which the tasks are also solved.

Essentially a difference to a Hubventilsteuerung according to 1 is the intermediate link 22 but not in one piece, but in two parts by a crank lever 22a and a guide swing 22b educated.

The guide swing 22b is hereby pivotable with its free end via a coupling pin with the center C2 with the crank lever 22a connected.

With its other end is the guide swing 22b pivotable on the control eccentric of the adjusting shaft 6 around the center C Exz. stored.

The gate lever 22a and the guide swing 22b are here forked executed, with axially centrally on the coupling pin a roller bearing roller pressure 2c is located with the center C2.

The gate lever 22a and the guide swing 22b are preferably arranged axially centrally in the cylinder plane, wherein the pressure roller 22c over the printing surface 23b preferably with a fork rocker arm 23 is in drive connection, which via the two adjacent valve clearance compensation elements 23a parallel to two globe valves 5 acts.

Alternatively, the pressure roller 22c also completely omitted, with a sliding surface directly with the pressure surface 23b of the fork rocker arm 23 in contact.

These sliding surface is here as a cylinder surface designed, which arranged concentric to the coupling axis C2 lies.

These sliding surface This can optionally be on the crank lever or on the guide rocker be educated.

Also in this Hubventilsteuerung the pivot axis C2 of the crank lever 22a , Which is formed here by the center C2 of the coupling bolt, along an equidistant to the pressure surface 23b with a radius R2 of the finger lever 23 relocated. The displacement takes place here by the control eccentric of the adjusting 6 out over the guide swing 22b on the coupling pin.

At one, through the gate lever 22a initiated stroke valve actuation becomes the pressure roller 22c , or in the alternative embodiment the concentric with the axis C2 arranged sliding surface, on the pressure surface 23b on the fork rocker arm 23 effective, with the guide rocker 22b with the coupling pin around the center C. Exz. of the control eccentric is deflected.

The advantage of this Hubventilsteuerung to a controller according to 1 is in particular in Wälzabgriff the pressure roller 2c to the printing surface 3b to see the drag lever, which leads to less wear and a reduced friction.

In the alternative embodiment with a sliding contact on the printing surface 23b Advantageously, the number of components and the moving masses can be further reduced.

Likewise, by an axial position of the cam in the Hubventilebene the overall height can be further reduced because the hydraulic valve clearance compensation elements 23a higher order.

Since the basic kinematic arrangements of the bearing axles, the pressure surface, the control link etc with those of a Hubventilsteuerung according to 1 are identical, and the operation here except for the additionally used guide rocker 22a equal to that of a Hubventilsteuerung according to 1 is the stroke valve control using the description of a Hubventilsteuerung according to 1 self-explanatory to the skilled artisan.

Therefore is here, in the interest of a brief version of the description, on further repetitive explanations waived.

In principle, different from the embodiment 2 an adjusting shaft 6 in a Hubventilsteuerung with a two-piece intermediate member according to the invention 22 also on the opposite side of the bearing axis C3 of a finger lever 23 are arranged. This takes over, designed as an eccentric shaft, fixedly mounted adjusting 6 legendary the bearing of the guide rocker 22a on the control eccentric.

The Adjustment is in this case essentially on the opposite Side of the paddle bearing C3 arranged below the camshaft.

The guide rocker is in such an embodiment in the Hubventilbetätigung on train loaded. In such an embodiment, the drag lever optionally on an additional be provided fixed stub axle with the center C3 stored or alternatively on per se known, housing-fixed support elements with hydraulic valve clearance compensation with an articulation point C3 rest.

Such a configuration simplifies the bearing arrangement of the finger lever 23 and brings more space to create a centrally located as possible spark plug hole. When using housing-fixed support elements advantageously the moving masses can be further reduced.

It should be noted in particular that, according to the invention, it is necessary to adjust the pivot axis C2 of the crank lever ( 2 . 22 ) along an equidistant to a radius R2 of a printing surface ( 3b . 23b ) on or in a drag lever ( 3 . 23 ) to relocate.

There are many alternative possibilities of shifting the axis C2 along an equidistant to a "pressure surface" (US Pat. 3b . 23b ), such as arcuate U-profile guides or prisms (V-shaped guide surfaces) in conjunction with slidably mounted around the axis C2 sliding blocks, etc.

Deviating from the exemplary embodiments, such guide surfaces can also be located on the inside or outside of the side parts of a finger lever (FIG. 3 . 23 ) be formed. Here, the drag levers may also be penetrated by recesses through a bearing and / or connecting pin with the center C2 on the side parts.

Therefore, in a broader sense, previously mentioned guide surfaces are of course used as a "printing surface" (US Pat. 3b . 23b ) to watch. Such known from the general state of the art embodiments for the circular arc displacement of an axis C2 are thus included in the claims in terms of a shortened formulation the like.

In principle, of course, the Nockenabgrifrolle 2h and / or the cam follower 4a is replaced by a correspondingly molded or cylindrical sliding surface.

Claims (9)

Fully variable lift valve control of an internal combustion engine ( 1 ) with a camshaft rotating about an axis C1 ( 1 ) and at least one rocker arm pivotable about an axis C3 ( 3 ), which with its free end on at least one lift valve ( 5 ), wherein between the drag lever ( 3 ) and the camshaft ( 1 ) an intermediate member ( 2 ) is arranged, characterized in that that intermediate member ( 2 ) by a pivotable about an axis C2 gate lever ( 2 ) is formed, wherein the crank lever ( 2 ) over a first attack surface ( 2h ) from the cam of the camshaft ( 1 ) is acted upon and at its free end with a control link ( 2g ), wherein the gate lever ( 2 ) over the control gate ( 2g ) on a cylinder jacket surface with a stationary center C4 of a support element ( 4a ) and the rocker arm ( 3 ) over a printing surface ( 3b ) at one with the gate lever ( 2 ) operatively connected, second attack surface ( 2i ) is supported, wherein the pivot axis C2 of the crank lever ( 2 ) over a third, with the gate lever ( 2 ) operatively connected attack surface ( 2c ) by the control contour of a rotatable adjusting shaft ( 6 ) along an equidistant to the printing surface ( 3b ) of the rocker arm ( 3 ) and the rocker arm ( 3 ) pivotally about the axis of rotation C3 of the adjusting shaft ( 6 ) is stored and the crank lever ( 2 ) by a force F in its contact with the camshaft ( 1 ) and the control contour of the adjusting shaft ( 6 ) via a spring ( 7 ) is supported. Fully variable lift valve control of an internal combustion engine ( 2 ) with a camshaft rotating about an axis C1 ( 1 ) and at least one rocker arm pivotable about an axis C3 ( 23 ), which with its free end on at least one lift valve ( 5 ), wherein between the drag lever ( 23 ) and the camshaft ( 1 ) an intermediate member ( 22 ) is arranged, characterized in that that intermediate member ( 22 ) in two parts and by a crank lever ( 22a ) and a guide rocker ( 22b ) is formed, and the crank lever ( 22a ) with the guide rocker ( 22b ) is pivotally connected in a coupling axis C2 and the guide rocker ( 22b On the other hand pivotally about the center C Exz. on a control eccentric of a, about a fixed axis rotatable adjusting shaft ( 6 ) is stored and the crank lever ( 22a ) over a first attack surface ( 2h ) from the cam of the camshaft ( 1 ) is acted upon and at its free end with a control link ( 2g ), wherein the gate lever ( 22a ) over the control gate ( 2g ) on a cylinder jacket surface with a stationary center C4 of a support element ( 4a ) and the rocker arm ( 23 ) over a printing surface ( 23b ) at one with the pontic ( 22 ) operatively connected, second attack surface ( 22c ), wherein the coupling axis C2 of the intermediate member ( 22 ) over the guide rocker ( 22b ) along an equidistant to the printing surface ( 23b ) of the rocker arm ( 23 ) and the gate lever ( 22a ) by a force F in its contact with the camshaft ( 1 ) via a spring ( 7 ) is supported. Fully variable globe valve control according to claim 1 or 2, characterized in that the control link ( 2g ) of the gate lever ( 2 . 22a ) of a valve latch section ( 2d ), which a radius contour R1 about the pivot center C2 of the crank lever ( 2 . 22a ), via a start-up ramp ( 2e ) into an outwardly extending lifting section ( 2f ), wherein the printing surface ( 3b . 23b ) of the rocker arm ( 3 . 23 ) a radius R2 around the center C4 of the support element (FIG. 4a ) during the valve lock. Fully variable globe valve control according to claim 2, characterized in that, the bearing axis C3 of the finger lever ( 23 ) at the same time a bearing axis C3 of the adjusting shaft ( 6 ), wherein the drag lever ( 23 ) pivotable on the adjusting shaft ( 6 ) is stored. Fully variable globe valve control according to claim 2, characterized in that, the bearing axis of the adjusting shaft ( 6 ) at a distance parallel to the bearing axis C3 of the finger lever ( 23 ) is arranged. Fully variable globe valve control according to claim 1 or 2, characterized in that the camshaft ( 1 ) is provided with a phase adjustment device of known type. Fully variable lift valve control according to claim 1 or 2, characterized in that, the drag lever ( 3 . 23 ) with a hydraulic valve clearance compensation element ( 3a . 23a ) known design works together. Fully variable globe valve control according to claim 1, characterized in that, in the case of two globe valves ( 5 ) per cylinder the control contours of two adjacent control eccentric of the adjusting shaft ( 6 ) are designed differently. Fully variable globe valve control according to claim 1 or 2, characterized in that, the support element ( 4a ) by a roller bearing roller ( 4a ) is formed with the rotation axis C4.