DE102015203712A1 - Camshaft for a valve train of an internal combustion engine, and method for producing a camshaft - Google Patents

Abstract

The invention relates to a camshaft (1) for a valve train of an internal combustion engine, comprising a basic shaft (2) on which at least one sliding cam piece is guided in a rotationally fixed and axially displaceable manner on each axial toothing (6, 7). In this case, the at least one sliding cam piece is axially adjacent to at least one axially fixedly arranged cam piece (4, 5). In order to enable a low production cost of the camshaft (1), the fundamental wave (2) is composed as a built shaft of several individual parts (8, 9), which are joined together axially in succession. A respective joint of the individual parts (8, 9) lies axially between the respective one axial toothing (7) and the at least one cam piece (4, 5).

Description

The invention relates to a camshaft for a valve train of an internal combustion engine, comprising a fundamental shaft on which at least one sliding cam piece rotatably and axially displaceably guided on a respective axial teeth, wherein the at least one sliding cam piece is provided axially adjacent to at least one axially fixed cam piece. Furthermore, the invention relates to a method for producing an aforementioned camshaft.

From the DE 10 2012 209 310 A1 goes out a camshaft for a valve train of an internal combustion engine, wherein in this camshaft on a basic shaft in addition to an axially fixed cam piece and a non-rotatable and axially displaceably guided sliding cam piece is provided. Both the sliding cam piece, as well as the axially fixed cam piece are each rotatably arranged on the basic shaft via an axial toothing. The axially fixed positioning of the cam piece on the fundamental shaft is then represented by an axial securing ring, which engages both side of the fundamental shaft, as well as the cam piece in respective grooves and thus prevents the cam piece form-fitting to an axial movement to the fundamental shaft.

Based on the above-described prior art, it is now the object of the present invention to provide a camshaft for a valve train of an internal combustion engine, wherein this camshaft is characterized by a low manufacturing cost.

This object is achieved from a device engineering point of view starting from the preamble of claim 1 in conjunction with its characterizing features. From a procedural point of view, a solution of the problem is based on the preamble of independent claim 6 in conjunction with its characterizing features. The respective subsequent dependent claims give each advantageous embodiments of the invention.

According to the invention, a camshaft comprises a basic shaft on which at least one sliding cam piece is rotatably and axially displaceably guided on an axial toothing, wherein the at least one sliding cam piece is provided axially adjacent to at least one axially fixed cam piece. In this case, this camshaft is produced in that, in addition to the at least one axially fixed cam piece, the at least one sliding cam piece is provided in a rotationally fixed and axially displaceable manner on each of an axial toothing of the fundamental shaft.

Accordingly, the camshaft according to the invention is provided for a valve train in which different opening and closing characteristics of at least one associated gas exchange valve can be represented via the at least one sliding cam piece. On the other hand, a constant opening and closing characteristic of at least one associated gas exchange valve is caused by the at least one axially fixed cam piece. Particularly preferably, the camshaft according to the invention is part of a valve train in which a cylinder shutdown of an associated cylinder of the internal combustion engine can be realized by corresponding representation of a zero stroke on the at least one sliding cam piece.

For the purposes of the invention, the at least one sliding cam piece on the basic shaft via an axial toothing rotatably and axially displaceably guided. The fundamental wave is thus equipped in the corresponding area with a spline toothing, on which the at least one sliding cam piece is then placed with a corresponding spline toothing.

In the sense of the invention, "axial" means an orientation in the direction of a longitudinal central axis of the fundamental wave.

The invention now includes the technical teaching that the fundamental wave as a built shaft composed of several individual parts, which are joined together axially, wherein a respective joint of the individual parts axially between the respective one Axialverzahnung and the at least one cam piece. In other words, the fundamental wave is thus composed of several individual parts, which are connected at axial ends rotatably to each other and thus form the fundamental wave. In this case, a connection of the individual parts is carried out at a respective point which lies axially between the respective one axial toothing for the at least one sliding cam piece and the at least one, axially fixed cam piece.

According to the invention, the camshaft is thus produced by assembling the basic shaft of a plurality of individual parts, which are joined together in a rotationally fixed manner in axial succession after the at least one sliding cam piece has been pushed onto the respective one axial toothing at a respective joint. The joint is then provided axially between the respective one axial toothing and the at least one cam piece.

Such a design of a camshaft has the advantage that the at least one cam piece integral with the respective Item of the fundamental wave can be made, but at the same time a sliding of at least one sliding cam piece can be realized at the same time, since the joint is between the later position of the sliding cam piece on the fundamental shaft and the axially fixed cam piece. Accordingly, the axially fixed cam piece can be manufactured on the associated single part of the fundamental shaft in a conventional manner. A separate production of a through hole for pushing the axially fixed cam piece, as well as its precise attachment to the appropriate location on the fundamental wave can be omitted, which reduces the overall manufacturing cost. Furthermore, a post-processing of the cam piece can be omitted, which would still be necessary in particular when pressing a separate cam piece on a basic shaft due to the expansion of the outer diameter.

Although in the case of DE 10 2012 209 310 A1 can be easily realized an axially adjacent arrangement of an axially movable sliding cam piece and an axially fixed cam piece, but the axial fixed cam piece must also be fixed axially on the fundamental shaft. On the one hand, a corresponding through hole with splined teeth must also be designed on the cam piece for this purpose, on the other hand the installation of a separate axial securing ring is necessary. Overall, this increases the production cost of this camshaft.

According to the invention, the fundamental wave can be realized as a solid shaft by also the individual parts of the fundamental wave are each made as solid shaft parts. Alternatively, it is also conceivable that the fundamental wave is at least partially realized as a hollow shaft by the items are completely or partially realized as a hollow shaft.

According to one embodiment of the invention, in each case a single part, each with an end-side pin in each case a corresponding axial bore of the respective other item is inserted at the respective joint. The items are thus joined together by the one item is inserted with one end-side pin in each case a corresponding axial bore of the other item. This allows a reliable alignment of the individual parts to each other, so that they can then be joined in the following.

According to a further embodiment of the invention a plurality of sliding cam pieces and cam pieces are provided, wherein the sliding cam pieces are axially between the cam pieces. In addition, a first cam piece and the slide cam pieces are placed on a first item of the fundamental shaft, which is connected to a further another cam piece carrying item. A joint of the two individual parts lies axially between the further cam piece and the axial toothing of the adjoining sliding cam piece. In this case, this camshaft is produced in such a way that first the sliding cam pieces are threaded onto respectively associated axial toothings on the first item having the outer cam piece. Following this, the first item is then joined to the further, the further cam piece having individual part. In this case, exactly two cam pieces and two sliding cam pieces are particularly preferably provided, so that the camshaft is suitable for a four-cylinder internal combustion engine with two cylinders which can be switched off. However, the application can be used with appropriate design for engines with any number of cylinders.

As an alternative to the aforementioned design possibility, a plurality of sliding cam pieces and cam pieces are provided, wherein the sliding cam pieces are arranged axially on both sides of the cam pieces. The cam pieces are arranged together on a single part of the basic shaft, which is axially connected on both sides to joints with other, each of the sliding cam pieces having individual parts. To produce this camshaft, the one sliding cam piece is slid onto an associated axial toothing on the first item before it is then non-rotatably connected to a second item having at least one cam piece. The second item in turn is then non-rotatably connected to a third item for another sliding cam piece rotatably, in the following then this further sliding cam piece can be threaded. In turn, preferably two sliding cam pieces and two cam pieces are provided, which makes the camshaft suitable for a four-cylinder internal combustion engine with two cylinders which can be switched off.

In a further development of the invention, the items are joined together by pressing, welding or gluing. The items are thus joined together as a press fit or by welding or gluing. But other possibilities are also, with a spline, by a cross pin, a wedge or polygon shaft connection or similar. to join the individual components. Essential to the invention is only that the items of the fundamental wave are rotatably connected.

The invention is not limited to the specified combination of the features of the independent claims or claims dependent therefrom. There are also possibilities, individual characteristics, even as far as they are Claims, the following description of preferred embodiments of the invention or directly from the drawings, combine with each other. The reference of the claims to the drawings by use of reference numerals is not intended to limit the scope of the claims.

Advantageous embodiments of the invention, which are explained below, are shown in the drawings. It shows:

1 a sectional view of a camshaft according to a first embodiment of the invention;

2 a perspective view of the camshaft 1 , shown before completion;

3 a perspective view of the camshaft 1 shown after completion;

4 a sectional view of a camshaft according to a second embodiment of the invention;

5 a perspective view of the camshaft 4 , shown before completion; and

6 a perspective view of the camshaft 4 shown after completion.

Out 1 is a sectional view of a camshaft 1 according to a first embodiment of the invention, said camshaft 1 is provided for the valve train of an internal combustion engine with four cylinders for the representation of opening and closing movements of gas exchange valves. In this case, the camshaft includes 1 a fundamental wave 2 , which is designed as a solid shaft and at one axial end with a head piece with camshaft bearing 3 equipped with this headpiece with camshaft bearing 3 in conjunction with a pulley, a phaser or a gear inside the valve train driving the camshaft 1 via a toothed belt or chain drive.

The camshaft 1 is with two axially fixed cam pieces 4 and 5 , and two - not shown in the present case - rotatably and axially displaceably guided slide cam pieces equipped. The sliding cam pieces here are each on one axial toothing 6 respectively. 7 the fundamental wave 2 guided and are axially between the cam pieces 4 and 5 , In this case, the sliding cam pieces with the help of an associated Stellaktuators targeted axially to the fundamental 2 be shifted in accordance with a sliding cam system known in principle to those skilled in the art, in order to vary a respective opening and closing characteristic of at least one associated gas exchange valve.

To present a threading the sliding cam pieces in the range of Axialverzahnungen 6 and 7 to enable is the fundamental 2 as a built shaft of two parts 8th and 9 composed. Here is the item 8th with the pulley 3 , the cam piece 4 and the two Axialverzahnungen 6 and 7 provided while at the item 9 the cam piece 5 is designed. The cam pieces 4 and 5 are each in one piece with the realized as full wave parts items 8th and 9 produced.

A manufacture of the camshaft 1 is then accomplished by the sliding cam pieces before joining the items 8th and 9 from one end 10 fro on the item 8th threaded and on the respective associated axial toothing 6 respectively. 7 be deferred. The still separate fundamental wave 2 is in the perspective view in 2 shown. Following the threading of the sliding cam pieces is the camshaft 1 then by merging the items 8th and 9 assembled as in the further perspective view in 3 shown. This is the item 8th with a pin 11 in an axial bore 12 of the item 9 introduced during the introduction by longitudinal or transverse pressing a press fit between the items 8th and 9 can be configured or both items 8th and 9 be joined together by welding or gluing together.

Further shows 4 a sectional view of a camshaft 13 according to a second embodiment of the invention. It is also this camshaft 13 designed for a valve train of a four-cylinder internal combustion engine and serves to initiate opening and closing movements of gas exchange valves of this internal combustion engine. As with the variant after the 1 to 3 , are also on the camshaft 13 two axially fixed cam pieces 14 and 15 , as well as two rotatably and axially displaceably guided - also not shown here - sliding cam pieces provided. The sliding cam pieces can thereby specifically with the help of an associated Stellaktuators axially to a fundamental wave 16 the camshaft 13 be shifted in accordance with a sliding cam system known in principle to those skilled in the art, in order to vary a respective opening and closing characteristic of at least one associated gas exchange valve.

The sliding cam pieces are on the basic shaft 16 again on axial teeth 17 and 18 rotatably and axially displaceable guided and lie, in contrast to the camshaft 1 from the 1 to 3 , axially on both sides of the intermediate cam pieces 14 and 15 , In particular, on the axial toothing 17 to be able to mount guided sliding cam piece, but at the same time a one-piece design of the cam pieces 14 and 15 to allow, is also the fundamental wave 16 in several items 19 . 20 and 21 divided, which are axially successively joined together rotatably.

It carries the item 19 at one end turn a head piece with camshaft bearing 22 and is with the spline 17 equipped for the one sliding cam piece, while on the subsequent item 20 the two cam pieces 14 and 15 are integrally formed and the next following item 21 with the axial toothing 18 equipped for the further sliding cam piece.

For a mounting of the camshaft 13 lie the items 19 . 20 and 21 , as in 5 is shown, initially separately from each other before. In the first step then the associated sliding cam piece on the item 19 in the area of the axial toothing 17 Threaded, then being the item below 19 non-rotatable with the item 20 is added. This is the item 19 with an end-side pin 23 in a corresponding axial bore 24 of the item 20 introduced and both parts 19 and 20 then rotatably joined together. This joining, as already in the variant of the 1 to 3 be realized by forming a press fit or by welding or gluing.

According to the invention, the items could 20 and 21 Also be made as a single item, as a postponement of the associated sliding cam piece on the axial teeth 18 in the in 4 illustrated embodiment of the camshaft 13 easily possible. Should the camshaft 13 but now on one opposite to the pulley 22 lying end may be equipped with another element, such. B. a trigger wheel, a pump cam or the like, so must in the 4 to 6 illustrated subdivision into the two individual parts 20 and 21 be taken. In this case, the corresponding sliding cam piece is then from the free end to the item 21 in the area of the axial toothing 18 postponed and subsequently the two items 20 and 21 rotatably joined together. This is the item 21 with an end-side pin 25 in another axial bore 26 of the item 20 introduced and in turn made a rotationally fixed joining. Ultimately, then the in 6 perspective camshaft 13 receive.

By means of the embodiments of a camshaft according to the invention, as well as the method according to the invention for producing the same, a camshaft production with low production costs is possible.

LIST OF REFERENCE NUMBERS

1

 camshaft

2

 fundamental wave

3

 Head with camshaft bearing

4

 cam piece

5

 cam piece

6

 axial toothing

7

 axial toothing

8th

 detail

9

 detail

10

 The End

11

 spigot

12

 axial bore

13

 camshaft

14

 cam piece

15

 cam piece

16

 fundamental wave

17

 axial toothing

18

 axial toothing

19

 detail

20

 detail

21

 detail

22

 Head with camshaft bearing

23

 spigot

24

 axial bore

25

 spigot

26

 axial bore

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012209310 A1 [0002, 0012]

Claims (10)

Camshaft ( 1 ; 13 ) for a valve train of an internal combustion engine, comprising a fundamental shaft ( 2 ; 16 ), on which at least one sliding cam piece on each of an axial toothing ( 6 . 7 ; 17 . 18 ) rotatably and axially displaceably guided, wherein the at least one sliding cam piece axially adjacent to at least one axially fixed cam piece ( 4 . 5 ; 14 . 15 ), characterized in that the fundamental wave ( 2 ; 16 ) as a built shaft of several parts ( 8th . 9 ; 19 . 20 . 21 ), which are axially successively joined together, with a respective joint of the items ( 8th . 9 ; 19 . 20 . 21 ) axially between the respective one axial toothing ( 7 ; 17 . 18 ) and the at least one cam piece ( 4 . 5 ; 14 . 15 ) lies. Camshaft ( 1 ; 13 ) according to claim 1, characterized in that at the respective joint each one item ( 8th ; 19 . 21 ) each with an end-side pin ( 11 ; 23 . 25 ) in each case a corresponding axial bore ( 12 ; 24 . 26 ) of the other item ( 9 ; 20 ) is introduced. Camshaft ( 1 ) according to claim 1, characterized in that a plurality of sliding cam pieces and cam pieces ( 4 . 5 ) are provided and the sliding cam pieces thereby axially between the cam pieces ( 4 . 5 ), wherein a first cam piece ( 4 ) and the sliding cam pieces on a first item ( 8th ) of the fundamental wave ( 2 ), which with another, another cam piece ( 5 ) carrying item ( 9 ) and a joint of the two parts ( 8th . 9 ) axially between the further cam piece ( 5 ) and the axial toothing ( 7 ) of the adjacent sliding cam piece is .. Camshaft ( 13 ) according to claim 1, characterized in that a plurality of sliding cam pieces and cam pieces ( 14 . 15 ) and the sliding cam pieces axially on both sides of the cam pieces ( 14 . 15 ) are arranged, wherein the cam pieces ( 14 . 15 ) together on a single item ( 20 ) of the fundamental wave ( 16 ), which axially on both sides at joints with other, each of the sliding cam pieces having individual parts ( 19 . 20 ) connected is. Camshaft ( 1 ; 13 ) according to claim 1, characterized in that the individual parts ( 8th . 9 ; 19 . 20 . 21 ) are joined by pressing, welding or gluing together. Method for producing a camshaft ( 1 ; 13 ) for a valve train of an internal combustion engine, wherein in addition to at least one axially fixed cam piece ( 4 . 5 ; 14 . 15 ) at least one sliding cam piece rotationally fixed and axially displaceable on each of an axial toothing ( 6 . 7 ; 17 . 18 ) of a fundamental wave ( 2 ; 16 ), characterized in that the fundamental wave ( 2 ; 16 ) of several parts ( 8th . 9 ; 19 . 20 . 21 ) is assembled, which axially successively after pushing the at least one sliding cam piece on each of a spline ( 6 . 7 ; 17 . 18 ) are joined at a respective joint rotationally fixed to each other, and that the respective joint axially between the respective one axial spline ( 7 ; 17 . 18 ) and the at least one cam piece ( 4 . 5 ; 14 . 15 ) lies. Method according to claim 6, characterized in that each one individual part ( 8th ; 19 . 21 ) each with an end-side pin ( 11 ; 23 . 25 ) in each case a corresponding axial bore ( 12 ; 24 . 26 ) of the other item ( 9 ; 20 ) and both items ( 8th . 9 ; 19 . 20 ; 20 . 21 ) are then added. A method according to claim 6, characterized in that initially on a first, an outboard cam piece ( 4 ) item ( 8th ) Sliding cam pieces on respectively associated axial toothings ( 6 . 7 ), whereby the first item ( 8th ) with another, another cam piece ( 5 ) item ( 9 ) is added. A method according to claim 6, characterized in that on a first item ( 19 ) a sliding cam piece on an associated axial toothing ( 17 ) is postponed before the first item ( 19 ) then with a second, at least one cam piece ( 14 . 15 ) item ( 20 ), whereby the second item ( 20 ) also with a third item ( 21 ) is rotatably connected for another sliding cam piece. Method according to claim 6, characterized in that the individual parts ( 8th . 9 ; 19 . 20 . 21 ) are joined together as a press fit or by welding or gluing.

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