WO2016177480A1

WO2016177480A1 - Valve train device

Info

Publication number: WO2016177480A1
Application number: PCT/EP2016/051155
Authority: WO
Inventors: Robert Hermann; Murat Saral
Original assignee: Volkswagen Aktiengesellschaft
Priority date: 2015-05-05
Filing date: 2016-01-20
Publication date: 2016-11-10
Also published as: EP3292280B1; DE112016002045A5; WO2016177479A1; EP3292280A1

Abstract

The invention relates to a valve train device comprising: a camshaft (50) with an axially movably arranged cam piece (10) having at least two cams (12, 14) that allow, in the event of a rotation of the camshaft (50), phase-shifted cam strokes and that are associated with different cylinders; and a slotted guide (20) for the axial movement of the cam piece (10), said slotted guide having a first slotted guide track (22) for the axial movement of the cam piece in a forward direction (V) and a second slotted guide track (24) for the axial movement of the cam piece in a reverse direction (R) counter to the forward direction. The first slotted guide track (22) and the second slotted guide track (24) are axially spaced from each other and have no common track section.

Description

description

Valve drive device

The invention relates to a valve drive device, in particular a motor vehicle, according to the preamble of claim 1. The valve drive device comprises a camshaft with a cam piece arranged axially displaceably on a cam basic shaft with at least two cams which provide camshafts which are phase-displaced during a rotation of the camshaft and are assigned to different cylinders and a shift gate for axially displacing the cam piece, the shift gate having a first cam track for axially displacing the cam piece in a forward direction and a second cam track for axially displacing the cam track in a reverse direction opposite to the forward direction.

Are known variable valve drive devices in internal combustion engines, which can realize both the shutdown of individual cylinders and a valve lift switching by axial displacement of cam pieces with cams of different cam contour (eg. Full cam, half cam and / or zero cam) (so-called.

Variable valve train devices with axially displaceable cam pieces do not have a classic one-piece camshaft, but one

Tooth shaft as a camshaft on which two or more cam pieces are slidably mounted. The torque transmission from the camshaft to the

Cam pieces take place via the teeth of the toothed shaft. The displacement of the cam pieces in the axial direction is effected by means of a stationary actuator, which causes an engagement of an actuating element, such as an adjusting pin in a switching gate of the cam piece. Upon rotation of the cam piece this is forcibly guided by means of the adjusting pin by a defined axial switching travel of a few millimeters, which corresponds to the distance between two adjacent cams of a cam portion of the cam piece moved. When the cam piece in a

is predetermined axial end position, the pin is retracted again or thrown back in the direction of the actuator. In order to effect an adjustment of the cam piece from a first axial position to a second axial position and vice versa, each cam piece two ejectable actuators are assigned to engage in each case a slide track of the shift gate, wherein the first slide track for adjusting the cam piece in an axial forward direction and the second cam track for adjusting the cam piece in an axial reverse direction is provided (activation and deactivation in ACT).

If each cylinder is associated with an axially displaceable cam piece ("single cam piece"), such conventional valve drive devices require, in addition to the cam piece, an actuator together with a shift gate per cylinder

Assembly costs connected.

In valve train devices with a single cam piece are Y-shaped extending link tracks with two side by side extending in the circumferential direction

Einspurbereichen known, which merge at a Y-junction in a common path section with a Auswerfbereich.

The documents DE 10 2007 056 692 A1, DE 10 2007 037 358 A1 and

DE 10 201 1 01 1 457 A1 describes in each case two or three cam pieces arranged axially relative to one another on the cam basic shaft, in which the cams associated with different cylinders are each axially displaceable relative to one another. The individual cam pieces can be pushed by means of two slide tracks either towards or away from each other. The valve train devices described in these documents are particularly complex and thus potentially prone to error.

In view of the problems described, it is the object of the present

Invention, a valve drive device with a double cam piece with a

To provide improved shift gate, which has the longest possible durability, reduces the load on the adjusting pins and eliminates audible abnormalities.

This object is achieved by a valvetrain of o.g. Art solved with the features characterized in claim 1. Advantageous embodiments of the invention are described in the further claims.

The valve drive device according to the invention comprises a camshaft having a cam piece arranged axially displaceably on a cam basic shaft and having at least two cams which provide phase-shifted cam strokes during a rotation of the camshaft and which are assigned to different cylinders. That's it According to the invention possible, the valve lifts two or more cylinders with a

(one-piece) cam piece substantially simultaneously switch

( "Double cam piece").

It should be noted that according to the presently used designation in a cam piece, the individual cams of the cam piece are not axially movable relative to each other, but are held axially rigid relative to each other on the cam piece. If two cams relative to each other axially movable on the

Cam base shaft are held, there are several cam pieces.

A valve lift can be done with a double cam piece only in the base circle of the cam. For the switching of the valve lift of two cylinders with a double cam piece is available for switching a smaller common cam base circle than when switching the valve lifts of two cylinders by means of two individual cam pieces. The valve and thus also the cam strokes are regularly rotated by 90 ° cam rotation angle to each other with two cylinders, which are adjusted with a common cam piece and thus phase-shifted. These 90 ° cam rotation angles correspond to the reduction of the base circle used for

Shift of disposal is available. For this reason, the slide track guide for switching multiple cylinders with a single cam piece is difficult.

In addition, the adjusting pins of the actuator when switching a

Double cam piece due to the higher to be moved cam piece mass and the smaller base circle area are more heavily loaded than in a

Single cam piece associated with a single cylinder only. The shorter cam base circle also leads to a higher axial end speed of the double cam piece, which causes an increasing acoustic conspicuity with increasing speeds.

In the valve drive device according to the invention, the first slide track and the second slide track are so axially spaced from each other that they no

have common track section. In other words, the two have

Gateways no track section, both in a move of the

Cam piece in the forward direction as well as a displacement of the

Cam piece is traversed in the reverse direction of an adjusting pin of the actuator. Rather, the two slide tracks are completely independent of each other and axially spaced from each other, so that a slide track for moving the Cam piece in the forward direction and the second cam track for moving the cam piece in the reverse direction is used.

The invention is based on the knowledge that when gate tracks with a common track section of these passing Verstellpin is potentially heavily stressed at the existing crossing, branching or merging points. In particular, the adjusting pin at the junction point can abut against an opposite wall section of the united slide track without its axial movement component being able to be braked adequately beforehand, which can lead to the acoustic abnormalities described above. Two independent and axially spaced gateways offer

In contrast, the advantage of greater degrees of freedom in determining their course in the circumferential direction and in the axial direction. In particular, the adjusting pin passing Verstellpin can be performed closely over its entire path between two slide web walls, and thus the axial

Movement component of the cam piece are also gently braked after moving through a corresponding web guide, whereby mechanical loads of the adjusting pins can be reduced.

The cam piece of the valve drive device according to the invention is integrally formed such that the two cams associated with the various cylinders and the shift gate are not axially displaceable relative to each other, but axially fixedly arranged on the cam piece. In other words, it is a previously described "double cam piece" or in the case of multiple cams to a one-piece "multiple cam piece", wherein the individual cams are associated with two or more cylinders and each provide phase-shifted cam strokes.

Preferably, the two slide tracks each have a substantially in the circumferential direction Einspurbereich, an axial course component having a displacement portion for axial displacement of the cam piece and a substantially extending in the circumferential direction Auswerfbereich. Thus, the cam piece according to the invention has two axially spaced and separate

Auswerf sections on. Each slide track can rotate the camshaft axis by more than 360 °, the beginning of the Einspurbereichs and the end of the

Auswerfbereichs can be arranged axially adjacent to each other due to a helical course of the slide track. It is important that the circumferential angle range of the shift range is limited to the available base circle. With regard to the good avoidance of acoustic abnormalities in the adjustment and with regard to increasing the durability of the adjusting pins, it has proved to be expedient that the slide tracks each have a braking area between the sliding area and the ejection area, which has such a curved course an axial component of movement of the cam piece is gradually braked when a braking area is traversed by the adjusting pin. In the braking area, the adjusting pin can be guided laterally on both sides closely to a slide track wall whose axial course component gradually decreases in the direction of the ejection area.

With regard to a simple manufacturability of the cam piece as well as with respect to a symmetrical loading of the valve drive device according to the invention with an adjustment in the two axial directions, it has proven to be advantageous that the two slide tracks have a symmetrical course with respect. A centrally extending between the slide tracks radial plane of symmetry , By doing

Shift region, the two slide tracks can thus gradually axially apart or converge with substantially identical axial curvature. Furthermore, both slide tracks can extend at substantially the same angle (preferably more than 360 °) in the circumferential direction.

With regard to a stable guidance of the adjusting pins in the respective slide track, it is advantageous if the single track area of each slide track extends over a circumferential angle of more than 10 °, preferably more than 30 °, in particular 90 ° or more axially next to the ejection region of the respective slide track.

Preferably, the slide tracks in unwound form have a substantially S-shaped course.

As already explained at the beginning, the cam piece is the invention

Valve train device adapted for adjusting two or more cylinders, wherein at least two cams are provided for providing phase-shifted cam strokes. With regard to reliable cylinder control, it has proved to be advantageous that the cam strokes of those cams which are assigned to different cylinders are offset in the circumferential direction by more than 30 ° and less than 180 ° to each other, in particular offset by about 90 ° to each other. The cam piece may have two or more cam portions, each of which cam portion has at least one (full) cam. Immediately adjacent to the (full) cam, a (partial) cam or a (zero) cam can be arranged on the cam piece so that it is possible to switch between different valve actuation modes by displacing the cam piece.

Preferably, the cam piece has at least four axially rigid

arranged cam portions each having at least one (full) cam and a partial or zero cam, each of which two cam sections associated with a cylinder and can be configured to provide phase-identical cam strokes.

Particularly advantageous in terms of a reliable and symmetrical

Valve actuation is a cam piece in which the two slide tracks are arranged between the two cam sections associated with a first cylinder and the two cam sections associated with a second cylinder.

In particular, the two slide tracks are in a central area of the

Cam piece arranged.

Preferably, each slide track of the valve drive device according to the invention is associated with an actuator with an adjusting pin for engagement in the respective slide track, wherein the diameter of the adjusting pins is smaller than 6 mm and preferably less than 5 mm. Due to an axial deceleration of the cam piece

allowing gradients of the slide tracks, the adjustment pins can be made narrower due to the lower load than in conventional

Valve train devices with adjustable double cam pieces, in which the

Diameter of the adjusting pins registrable be 7 or more millimeters.

Further, according to the invention, the camshaft can be switched due to the stable, one-piece double cam pieces at a higher speed of 1800 rev / min, 2000 rpm or more than camshafts with conventional, axially displaceable arranged Einzelelnockenstücken in which the limit speed for switching 1700 U / may be min or less.

According to a further aspect, the invention relates to a cam piece of a valve drive device according to the invention.

The invention will be explained in more detail below with reference to the drawing. This shows in 1 shows a cam piece of a valve drive device according to the invention in a perspective view,

2 shows a valve drive device according to the invention in a longitudinal sectional view,

Fig. 3 is a view from above of an engine block with an inventive

Valve drive device,

Fig. 4 is an explanatory view of a cam piece of a

valve drive device according to the invention, together with the two slide tracks in unwound form (groove development),

FIG. 1 shows a perspective view of a cam piece 10 of FIG

The cam piece is in the form of a double cam piece adapted to actuate valves of two adjacent cylinders, with the first cylinder associated cams 12 out of phase with the second cylinder associated cams 14 projecting from the cam piece 10. The phase shift is approximately 90 ° in the illustrated example. The individual cams 12, 14 are not movable relative to each other; Rather, the cam piece 10 is integrally formed.

The illustrated cam piece 10 has a total of four cam sections 15, each of which comprises on the one hand a full cam and on the other hand either a zero cam or a partial cam. The two associated with the second cylinder

Cam sections each have a full cam 14 and a zero cam 16, so that can be switched between valve full and valve shutdown, and associated with the first cylinder two cam portions 15 each have a full cam 12 and a partial cam 17, so that are switched between valve full and valve subcircuit can.

2, the valve drive device 10 according to the invention is shown in a longitudinal sectional view. In this case, the cam piece 10 shown in FIG. 1 is arranged axially displaceably on a cam base shaft 52, wherein the cam base shaft 52 forms the camshaft 50 together with the cam pieces 10 displaceably arranged thereon. The cam piece 10 also has in a central region a shift gate 20 with two adjacent link tracks 22, 24, wherein the shift gate 20 is provided for axially displacing the cam piece 10 on the cam base shaft 50. For displacing the cam piece 10 in a forward direction V, an axially fixed adjusting pin 42 of an actuator 40 engages in the first slide track 22 of the rotating cam piece 10, whereby it is axially guided and displaced. To move the cam piece 10 in a backward direction R, a second axially fixed adjusting pin of a second actuator engages the second slide track 24 of the rotating cam piece 10, whereby it is axially guided and displaced in the opposite direction.

In the cam piece 10 according to the invention, the two slide tracks 22, 24 axially spaced from each other provided on the cam piece 10 and have no common track section. This allows the cam piece according to the invention despite its large compared to conventional Einzelelnockenstücken mass

Connection to a respective switching process very defined and gradually slowed down axially. For this purpose, each of the two slide tracks 22, 24 has a running in the circumferential direction Einspurbereich 32 with varying groove depth for the alignment of the adjusting 42, adjoining it in the circumferential direction adjustment 34 with axial flow component for moving or

Pushing back the cam piece 10, one in the circumferential direction

subsequent braking portion 36 for braking the axial movement component of the cam piece following an axial displacement, and a subsequent thereto in the circumferential direction Auswerfbereich 38 with an ejection ramp for ejecting the adjusting pins on. These courses of the two cam tracks 22, 24 are particularly clearly visible in Fig. 4, which shows the slide tracks 22, 24 in a developed form (see Fig. 4, center), and on the other the depth profile 85 of the guide tracks shows (see Fig. 4, right). As can also be seen in FIG. 4, the two slide tracks 22, 24 have an essentially S-shaped course in unwound form. Due to the separation of functions between switching back and forth, a close guidance of the adjusting pin is made possible over the entire switching process.

Reference numeral 62 shows the contact area between the wall of the slide track 22 and the Verstellpin 42 when moving the cam piece 10, and reference numeral 63 shows the contact area between the wall of the slide track 22 and the Verstellpin 42 during axial braking of the cam piece 10 following the displacement. In the braking region 36, the axially curved walls of the slide tracks gradually merge again into walls extending in the circumferential direction, so that a defined

Deceleration of the cam piece 10 is possible. Because of this gradual

Abbremsung adjusting 42 can be used with a diameter of only about 4.9 mm and correspondingly narrow slide tracks 22, 24, whereby material can be saved and the cam pieces can be made relatively compact. In addition, the adjustment units can be made smaller, resulting in lower costs and a smaller space occupied.

The adjustment portion 34 of the first slide track 22 curves opposite to the adjustment 34 of the second link 24, whereby on the one hand a displacement of the cam piece 10 in the forward direction V and on the other hand a displacement of the cam piece 10 in the reverse direction R is made possible. Overall, the slide tracks 22 and 24 are symmetrical with respect. A radially symmetrical plane arranged therebetween.

In Fig. 3, an engine block with two camshafts 50 is shown, each having two cam pieces 10.

The valve drive device 100 according to the invention allows the use of

Double cam pieces for switching speeds of 2000 rpm or more. In addition, an increase in component durability over the term and significantly improved acoustics in the switching operation is achieved by the deceleration.

LIST OF REFERENCE NUMBERS

10 cam piece

12, 14 cams

15 cam sections

16 zero cams

17 cams

20 shift gate

22, 24 slide tracks

32 single track area

34 shift range

36 braking range

38 ejection area

40 actuator

42 adjustment pin

50 camshaft

52 Cam basic shaft

62 contact area when moving

63 Contact area during braking

85 depth profile

V forward direction

R reverse direction

Claims

1. Valve drive device, in particular of a motor vehicle, with a camshaft (50) with an axially displaceable on a cam base shaft (52) arranged cam piece (10) with at least two cams (12, 14), with a rotation of the camshaft (50) phase-shifted cam strokes and a plurality of cylinders, and a shift gate (20) for axially displacing the cam piece (10), the shift gate having a first slide track (22) for axially displacing the cam track in a forward direction (V) and a second guide track (24) axial displacement of the cam piece in a forward direction opposite to the reverse direction (R), characterized in that the first slide track (22) and the second slide track (24) are axially spaced apart and have no common track section.

2. Valve drive device according to claim 1, characterized in that the slide tracks (22, 24) each have a substantially circumferentially extending Einspurbereich (32), an axial course component having a sliding portion (34) for axially displacing the cam piece (10) and an in Have substantially extending in the circumferential direction Auswerfbereich (38).

3. Valve drive device according to claim 2, characterized in that the slide tracks each between the displacement region (34) and the Auswerfbereich (38) have a braking region (36) having a curved course such that an axial component of movement of the cam piece when passing through an adjustment (42) is gradually slowed down.

4. Valve drive device according to claim 2 or 3, characterized in that the two slide tracks (22, 24) substantially with respect to a symmetrical course. A centrally extending between the slide tracks radial plane of symmetry.

5. Valve drive device according to one of claims 2 to 4, characterized in that the Einspurbereich (32) of each slide track over a circumferential angle of more than 10 °, preferably more than 30 °, in particular 90 ° or more axially adjacent to the Auswerfbereich (38) of the respective slide track.

6. Valve drive device according to one of the preceding claims, characterized in that the slide tracks (22, 24) in unwound form have a substantially S-shaped course.

7. Valve drive device according to one of the preceding claims, characterized in that the cam strokes of the various cylinders associated cam (12, 14) are offset in the circumferential direction by more than 30 ° and less than 180 ° to each other, in particular offset by about 90 ° to each other.

8. Valve drive device according to one of the preceding claims, characterized in that the cam piece (10) at least four axially rigidly arranged cam portions (15) each having at least one cam (14) and a zero cam (16) or two or more cams (12, 17), of which in each case two cam sections are assigned to a cylinder and are set up to provide phase-identical cam strokes.

9. Valve drive device according to claim 8, characterized in that the two slide tracks (22, 24) between the two cam portions, which are associated with a first cylinder, and the two cam portions, which are associated with a second cylinder, and in particular in a central region of Cam piece (10) are arranged.

10. Valve drive device according to one of the preceding claims, characterized in that each slide track (22, 24) is assigned an actuator (40) with an adjustment pin (42) for engagement in the respective slide track, wherein the diameter of the adjusting pins is smaller than 6th mm and preferably less than 5 mm.