DE102014221136B3 - Hubvariabler valve drive of an internal combustion engine - Google Patents

Abstract

A valve drive of an internal combustion engine is proposed, comprising a camshaft (1) which comprises a carrier shaft (2) and two cam pieces (3, 4), each having a group of adjacent cams (5, 6) with different cam elevations and a cylinder segment at the end ( 10 ', 11', 10 '', 11 '') and which are arranged rotationally fixed and displaceable between two axial positions on the support shaft, wherein the cylinder segments overlap axially and externally circumferentially a groove-shaped Axialkulisse (7 ', 7' ') to specification two slide tracks (12 ', 13', 12 '', 13 '') form, - and two actuator pins (8, 9) which selectively engage in the slide tracks and successively move the cam pieces in the two axial positions, wherein the slide tracks each a radial Nuteinspurbereich (14 ', 15', 14 '', 15 '') and an axial displacement portion (16 ', 17', 16 '', 17 '') with two displacement parts (16'-3, 16'-4 , 17'-4, 17'-3, 16 '' - 3, 16 '' - 4, 17 '' - 4, 17 '' - 3) together are supported, of which a sliding part on a cylinder segment and the other displacement part extends on the other cylinder segment. In each case, the sliding parts running on the same cylinder segment should converge axially until their union.

Description

• – einer Nockenwelle, die eine Trägerwelle und zwei Nockenstücke umfasst, die jeweils eine Nockengruppe benachbarter Nocken mit unterschiedlichen Nockenerhebungen und endseitig ein Zylindersegment aufweisen und die drehfest und zwischen zwei Axialpositionen verschiebbar auf der Trägerwelle angeordnet sind, wobei sich die Zylindersegmente axial überlappen und außenumfänglich eine nufförmige Axialkulisse zur Vorgabe zweier Kulissenbahnen bilden,
• – und zwei Aktuatorstiften, die selektiv in die Kulissenbahnen einspuren und die Nockenstücke sukzessiv in die beiden Axialpositionen verschieben.

The invention relates to a valve train of an internal combustion engine, with

• - A camshaft comprising a carrier shaft and two cam pieces, each having a cam group of adjacent cams with different cam lobes and end a cylinder segment and which are rotatably and slidably disposed between two axial positions on the support shaft, wherein the cylinder segments overlap axially and externally circumferentially a nufförmige Axial backdrop for specifying two slide tracks,
• - And two actuator pins that selectively engage in the slide tracks and successively move the cam pieces in the two axial positions.

The slide tracks are each composed of a radial Nuteinspurbereich and an axial displacement region with two sliding parts, of which a sliding part on a cylinder segment and the other displacement part extends on the other cylinder segment.

A generic valve train is from the DE 10 2007 037 745 A1 known. The stroke variable actuation of the gas exchange valves is effected by a so-called sliding cam system with two cam pieces whose end portions are designed as cylinder half-shells, which complement each other axially overlapping to form a full-circumference cylinder. Depending on the instantaneous axial position of the cam pieces, one of the two actuator pins spurs into the axial slide extending thereon and successively shifts the cam pieces into the other axial position. Thus, for the two-sided displacement of two immediately adjacent cam pieces, only one single actuator is needed, in which the two actuator pins are combined. In the case of a four-cylinder in-line engine, it is even common to control the charge cycle of cylinder pairs # 1 and # 2, and # 3 and # 4, each by a common cam piece, so in this case the complexity of the valvetrain with only two cam pieces for each two engine cylinders and a single actuator is particularly low.

The DE 10 2007 010 149 A1 discloses an axial slide with two axially opposing slide tracks, which unite at the end of their axial displacement ranges.

The object of the invention is to provide a particularly compact valve drive of the type mentioned.

This object is solved by the features of claim 1. Accordingly, each of the running on the same cylinder segment sliding parts converge axially to their union, each of the adjoining the Nuteinspurbereich sliding part starts at a later with respect to the cam rotation circumferential angle than the sliding part associated with this displacement part.

In other words, the axial distance of the slide tracks should be reduced so that the ends of the axially adjacent sliding parts run into each other and merge like v-shaped or y-shaped together, so that the axial space requirement of the axial slide is reduced. Due to the correspondingly small spaced actuator pins so that the actuator can build relatively compact. Due to the axially asymmetrical distortion of the two uniting displacement parts, it is possible to increase the circumferential angle of each groove groove area, so that the actuator pins have sufficient time to fully engage in the axial slide. As a result, either the same safety against faulty switching, the camshaft switching speed or at the same switching speed, the switching reliability or both can be increased together.

Further features of the invention will become apparent from the following description and from the drawings, in which exemplary embodiments of a variable-stroke valve drive are illustrated with reference to the relevant for the understanding of the invention cutouts. Unless otherwise stated, the same or functionally identical features or components are provided with the same reference numerals. Show it:

1 a portion of a camshaft with two adjacent cam pieces and the common Axialkulisse;

2 the schematic development of a known Axialkulisse;

3 the schematic development of a non-invention Axialkulisse with mirror-symmetrical sliding parts;

4 the schematic development of a Axialkulisse invention with unbalanced displacement parts;

5 the processing of the invention according to Axialkulisse 1 ;

6 the switching sequence of the camshaft section according to 1 ,

1 shows a section of a valve train for variable-stroke actuation of the (not shown) gas exchange valves of an internal combustion engine. The valve train includes a partially shown camshaft 1 consisting of an externally toothed carrier shaft 2 and thereon by means of internal toothing rotatably and axially displaceably mounted cam pieces 3 and 4 is composed. The cam pieces each have two groups of axially immediately adjacent cams 5 and 6 on whose different cam lobes are transferred to the gas exchange valves. The two cam pieces actuate 3 . 4 of the illustrated camshaft section respectively the intake or exhaust valve pairs of two immediately adjacent engine cylinders. In the case of a four-cylinder in-line engine, these are either cylinders # 1 and # 2 or cylinders # 3 and # 4.

The operating point-dependent activation of the respective cam 5 or 6 required displacement of the cam pieces 3 . 4 on the carrier shaft 2 takes place via a groove-shaped axial slide 7 '' and two actuator pins 8th . 9 an actuator (not shown) which selectively into the Axialkulisse 7 '' Engage the two cam pieces 3 . 4 successively between two axial positions back and forth to push. The axial positions correlate with the valve actuation by the cams 5 and 6 , The axial backdrop 7 '' is on the outer circumference of two cylinder segments 10 '' and 11 '' formed as axially overlapping cylinder half shells 10 '' and 11 '' each at one end of the cam pieces 3 respectively. 4 are formed and complement each with 180 ° radians to a complete cylinder.

The cylinder half shells 10 '' . 11 '' are with different groove areas for the specification of two axially opposing slide tracks 12 '' and 13 '' for the actuator pins 8th . 9 Mistake. These groove areas are based on 2 which illustrates a schematic development of a known Axialkulisse 7 on the two end cylindrical half shells 10 . 11 the cam pieces 3 respectively. 4 shows.

The groove areas start with respect to the cam direction always indicated by the arrow in each case with a Nuteinspurbereich 14 and 15 , which is axialhubfrei at sections radially sloping groove base. To the radial groove groove area 14 . 15 , which ends approximately at the dashed line, joins a shift range, which is provided with a radially constant groove bottom with an axial stroke. The axial displacement area is on two sliding parts 16-3 and 16-4 respectively. 17-3 and 17-4 split, one of which is a sliding part 16-3 respectively. 17-3 on the one cylinder half shell 10 and the other sliding part 16-4 respectively. 17-4 on the other cylinder half shell 11 runs and whose axial stroke each as large as the distance between the two axial positions of the cam pieces 3 . 4 is. The groove areas each end with a to the displacement area 16 respectively. 17 adjacent groove gauge area 18 respectively. 19 , which is axialhubfrei in sections radially rising groove base.

The successive shifting of the two cam pieces 3 . 4 from the in 1 left axial position in which the gas exchange valves of the cam 5 be actuated, in the right axial position, in which the cams 6 are active, carried out by actuation of the Aktuatorstifts 8th , after the tracks in the slide track 12 '' first the cam piece 3 and then the cam piece 4 shifts. The actual shifting takes place in the displacement area 16 '' (please refer 6d ) through the axial groove wall contact with the actuator pin 8th ,

As it again clearer in 2 is recognizable, first pushes the sliding part 16-3 the cam piece 3 about an axial position upward, leaving the end of the sliding part 16-3 with the beginning of the sliding part 16-4 Aligns, then the Aktuatorstift 8th also displaced upwards by an axial position.

The shifting process ends with the ejection of the actuator pin 8th from the slide track 12 '' due to the radial increase of Nutausspurbereichs 18 '' (please refer 6f ).

Conversely, the successive displacement of the two cam pieces 3 . 4 from their shifted right axial position back to the left axial position according to FIG 1 by actuation of the actuator pin 9 in the gate track 13 '' sprint to first the cam piece 4 and then the cam piece 3 along the sliding parts 17 '' - 4 and 17 '' - 3 to move.

As it is from the synopsis of 2 and 3 becomes clear causes the reduction of the axial distance between the two known slide tracks 12 and 13 on the axial distance between the two slide tracks 12 ' and 13 ' (see also the distance between the actuator pins 8th and 9 ) that on the same cylinder half shell 10 ' or 11 ' extending sliding parts 16'-3 and 17'-3 respectively. 16'-4 and 17'-4 converge axially until the union or fusion of their end portions and unite there y-shaped to form a single groove portion with common groove walls and a common groove bottom. As it is in 3 is shown, thus can be an axially particularly compact design of the Axialkulisse 7 ' Achieve by the axial extent of both the cylinder half shells 10 ' and 11 ' as well as the actuator, the two actuator pins 8th . 9 receives and actuates, is relatively small dimensions.

The according to 4 unwound Axialkulisse 7 '' includes in addition to the pairwise union of the axially mirror-symmetric converging sliding parts 16'-3 and 17'-3 respectively. 16'-4 and 17'-4 according to 3 also their unbalanced, ie not mirror-symmetric course. As shown again by the dashed lines, each begins at the radial Nuteinspurbereich 14 '' respectively. 15 '' adjoining sliding part 16 '' - 3 respectively. 17 '' - 4 the one slide track 12 '' respectively. 13 '' to a later with respect to the cam rotation direction circumferential angle than the thus unifying sliding part 17 '' - 3 respectively. 16 '' - 4 the other slide track 13 '' respectively. 12 '' , As already explained, allows the so distorted course of the slide tracks 12 '' and 13 '' that the actuator pin 8th respectively. 9 an enlarged camshaft angle for safe engagement in the slide tracks 12 '' . 13 '' is available.

The in the 3 and 4 drawn, radial Nutausspurbereiche 18 ' and 19 ' respectively. 18 '' and 19 '' borders on the united sliding parts 16'-4 and 17'-4 . 16'-3 and 17'-3 . 16 '' - 4 and 17 '' - 4 such as 16 '' - 3 and 17 '' - 3 at.

5 shows the true, ie not schematic execution of the according to 4 distorted and in accordance with the 1 and 6 executed axial slide 7 '' , The circles drawn in the settlement mark the relative position of the actuator pin 8th when going through the slide track 12 '' , and the letters contained in these circles correspond to the respective figure designation 6a to 6f in which the camshaft 1 in different rotational angle positions during the displacement of the cam pieces 3 and 4 is shown from left to right.

6a : the actuator pin 8th spurt into the radially sloping portion of Nuteinspurbereichs 14 '' the slide track 12 '' one.

6b : the actuator pin 8th is located in the groove groove area 14 '' on the parting line between the two cylinder half-shells 10 '' and 11 '' ,

6c : the actuator pin 8th is located at the end of Nuteinspurbereichs 14 '' and at the beginning of the sliding part 16 '' - 3 ,

6d : the actuator pin 8th is in the move area 16 '' on the parting line between the two cylinder half-shells 10 '' and 11 '' ,

6e : the actuator pin 8th is located at the end of the sliding part 16 '' - 4 and at the beginning of Nutausspurbereichs 18 '' ,

6f : the actuator pin 8th is located on the parting line between the two cylinder half shells 10 '' and 11 '' and spurt over the radially rising portion of the groove lug portion 18 '' the slide track 12 '' from the axial backdrop 7 '' out.

Claims (2)

Valve train of an internal combustion engine, with - a camshaft ( 1 ), which is a carrier wave ( 2 ) and two cam pieces ( 3 . 4 ), each having a group of adjacent cams ( 5 . 6 ) with different cam elevations and at the end a cylinder segment ( 10 '' . 11 '' ) and the rotationally fixed and displaceable between two axial positions on the carrier shaft ( 2 ) are arranged, wherein the cylinder segments ( 10 '' . 11 '' ) overlap axially and externally circumferentially a groove-shaped Axialkulisse ( 7 '' ) for specifying two slide tracks ( 12 '' . 13 '' ), and two actuator pins ( 8th . 9 ), which selectively into the slide tracks ( 12 '' . 13 '' ) and the cam pieces ( 3 . 4 ) shift successively in the two axial positions, wherein the slide tracks ( 12 '' . 13 '' ) each of a radial groove Einspurbereich ( 14 '' . 15 '' ) and an axial displacement area ( 16 '' ) with two sliding parts ( 16 '' - 3 . 16 '' - 4 . 17 '' - 4 . 17 '' - 3 ), of which one shifting part ( 16 '' - 3 . 17 '' - 3 ) on one of the cylinder segments ( 10 '' ) and the other shift part ( 16 '' - 4 . 17 '' - 4 ) on the other of the cylinder segments ( 11 '' ), characterized in that each on the same cylinder segment ( 10 '' . 11 '' ) extending sliding parts ( 16 '' - 3 . 17 '' - 3 . 16 '' - 4 . 17 '' - 4 ) converge axially until their combination, wherein each of the to the Nuteinspurbereich ( 14 '' . 15 '' ) adjacent sliding part ( 16 '' - 3 . 17 '' - 4 ) begins at a circumferential angle with respect to the cam rotation direction than that with this displacement part ( 16 '' - 3 . 17 '' - 4 ) merging part ( 17 '' - 3 . 16 '' - 4 ). Valve gear according to claim 1, characterized in that the slide tracks ( 12 '' . 13 '' ) each further from a radial Nutausspurbereich ( 18 '' . 19 '' ) which are connected to the combined displacement parts ( 16 '' - 4, 17 '' - 4 . 16 '' - 3 . 17 '' - 3 ) adjoins.

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