EP3215722B1 - Camshaft having at least one axially fixed sliding element - Google Patents

Description

The present invention relates to a camshaft for a multi-cylinder internal combustion engine with sliding elements comprising at least two cam elements for controlling valves of the internal combustion engine, and having an axially extending tooth shaft, on which the sliding elements are accommodated, and wherein the sliding elements have an internal toothing with an external toothing of the toothed shaft cooperates, so that the sliding elements rotatably seated on the toothed shaft and wherein at least one sliding element is received axially displaceably on the toothed shaft.

STATE OF THE ART

The DE 10 2004 011 586 A1 describes a valve train for a multi-cylinder internal combustion engine, and the valve train has camshafts, which are essentially constructed of a toothed shaft and a plurality of sliding elements. The sliding elements have an internal toothing, which engages in an external toothing on the toothed shaft, so that the sliding elements are rotationally received on the toothed shaft, but remain axially movable. By way of external actuators, the sliding elements can be moved axially between discrete positions during operation in order, for example, to actuate a tapping element via different cam elements, and to correspondingly change the control movement of the valves.

Depending on the design of the valve train and the camshaft axially fixed cam elements are required, and at the same time the camshaft should have axially displaceable cam elements, which are formed for example on sliding elements. The sliding elements are pinned to form the axially fixed cam elements with the toothed shaft, and it can For example, a pin to be passed in a transverse direction through the gear shaft and through the support tube of the sliding element. Thus, the sliding element is fixed axially on the toothed shaft, while, for example, adjacent sliding elements continue to be accommodated axially movable on the toothed shaft.

Disadvantageously, a pinning of the carrier tubes on the toothed shaft is complicated and requires a corresponding adaptation of the pinning. Furthermore, the sliding elements always sit in the subsequent operation of the camshaft on the same portion of the toothed shaft, whereby a larger radial play can form and whereby the concentricity of the sliding elements on the toothed shaft are further deteriorated.

DISCLOSURE OF THE INVENTION

The object of the invention is the development of a camshaft with at least one axially fixed sliding element on a toothed shaft, wherein the axial fixation is to be designed easily. In particular, a residual mobility of an axially fixed sliding element on the toothed shaft should be avoided.

This object is achieved on the basis of a camshaft according to the preamble of claim 1 in conjunction with the characterizing features. Advantageous developments of the invention are specified in the dependent claims.

The invention includes the technical teaching that at least one of the sliding elements for axial fixation with the toothed shaft has a form-fitting formed in the axial direction, which is produced by at least one caulking between the sliding element and the toothed shaft.

The invention is based on the general idea to produce a positive connection between the sliding element and the toothed shaft, which fixes the sliding element in the axial direction on the toothed shaft. The caulking can be 1 or more times between the sliding element and the toothed shaft be provided, and the caulking describes any form of plastic, permanent deformation of a material portion of the support tube through which the positive connection is formed with the toothed shaft. The shape, the geometric design and the size of the caulking is not limited by the concept of caulking itself. For example, a prepared material portion, such as a tongue, a tab or the like, may be formed on the first joining part, ie on the sliding element or on the toothed shaft, which is bent against the respective other joining part. As a result, a simple, cost-minimal and easily executable connection between the sliding element and the toothed shaft is provided, and even minimal movements of the sliding element on the toothed shaft are avoided by the at least one caulking. In particular, no play between the sliding element and the toothed shaft can build up, and the external toothing of the toothed shaft does not have to form a press fit or a transition fit with the internal toothing of the sliding element.

The caulking can be done on the sliding element or on the toothed shaft. For example, the toothed shaft may have an interruption of the external toothing formed at at least one axial position, in which a section-wise material part of the sliding element is caulked and / or it can be provided that the sliding element has a receiving geometry into which a section-wise material part of the toothed shaft is caulked.

With particular advantage, the toothed shaft may have an interruption of the external toothing formed at at least one axial position into which a section-wise material portion of the sliding element and in particular of the carrier tube is caulked. The interruption may be formed with particular advantage as a circumferential groove in the external toothing, and the groove may have a depth corresponding to the depth of the toothing. For example, the groove base may have a radius which coincides with the radius of the Zahnfußkreises the outer toothing of the toothed shaft. Alternatively, the interruption can also be formed by individual teeth of the external teeth having the interruption, and in the interruption, the section-wise material part of the support tube can finally be caulked.

The section-wise material part is preferably formed on the outer edge of the support tube, but this may also be formed spaced from the outer edge, for example, adjacent to the setting point of a cam member on the support tube.

According to an advantageous embodiment of the camshaft according to the invention, the support tube may have at least one end-side section with a reduced tube wall thickness. In this case, the caulking can be formed in the region of the end-side section, so that the section-wise material part lies in this region of the reduced pipe wall thickness.

With further advantage, at least two, preferably at least three, and more preferably four, caulkings can be formed into an interruption of the outer toothing distributed over the circumference of the support tube, and more than four caulkings can also be provided. For example, caulking may be provided in each intermediate space between two teeth of the external toothing, or a caulking is occasionally formed in the interdental spaces. In particular, the caulking can be provided on both end sides of the support tube, so that when two caulking on one end side of the support tube, for example, a total of four caulking between the support tube and the toothed shaft are formed.

According to a further advantageous embodiment, the sliding element may have a bearing portion, by which the sliding element is rotatably supported on a bearing bridge. If the camshaft has sliding elements which are received in an axially displaceable manner on the toothed shaft and if the camshaft has sliding elements which are fixed axially on the toothed shaft by the method according to the invention, a particular advantage is achieved in that the sliding elements which are connected via the method according to the invention the caulking are set on the toothed shaft, in bearing bridges of the camshaft receiving component, such as a hood module or a cylinder head, are stored. The storage section may be, for example located between two settling points on which cam elements are applied to the support tube.

The invention further relates to a method for producing a camshaft for a multi-cylinder internal combustion engine, wherein the camshaft comprises a plurality of sliding elements comprising at least two cam elements for controlling valves of the internal combustion engine, and wherein an axially extending toothed shaft is provided which extends through the sliding elements, wherein the sliding elements have an internal toothing, which cooperates with external toothing of the toothed shaft, so that the sliding elements rotatably seated on the toothed shaft and wherein at least one sliding element is axially displaceable, wherein the method comprises at least the following steps: providing the Sliding elements and the toothed shaft, passing the toothed shaft through the sliding elements and producing a caulking between the sliding element and the toothed shaft to form a positive connection for an axial fixation in the axial direction of at least one sliding element on the toothed shaft.

The method provides in particular that the sliding element is provided with a carrier tube which has at least one end-side section with a reduced tube wall thickness, wherein the caulking is carried out in the region of the end-side section. In addition, the provision of the sliding element can take place in an arrangement in a bearing bridge of a camshaft module, so that the caulking of the support tube is carried out on the toothed shaft in or on the camshaft module. For this purpose, a suitably suitable caulking can be provided, with which the caulking of the sliding element is carried out on the toothed shaft, wherein the caulking is made with particular advantage only when the sliding element is already arranged in a bearing bridge of a camshaft module.

PREFERRED EMBODIMENT OF THE INVENTION

Fig. 1

eine Ansicht einer Nockenwelle in einer nicht montierten Anordnung eines Schiebeelementes auf einer Zahnwelle,

Fig. 2

die Ansicht der Nockenwelle gemäß Fig. 1, wobei das Schiebeelement auf der Zahnwelle angeordnet ist,

Fig. 3

eine Ansicht einer Nockenwelle mit einem Schiebeelement, das über eine Verstemmung des Trägerrohrs mit der Zahnwelle axial auf dieser gesichert ist.

Further, measures improving the invention will be described in more detail below together with the description of a preferred embodiment of the invention with reference to FIGS. It shows:

Fig. 1

a view of a camshaft in a non-mounted arrangement of a sliding element on a toothed shaft,

Fig. 2

the view of the camshaft according to Fig. 1 wherein the sliding element is arranged on the toothed shaft,

Fig. 3

a view of a camshaft with a sliding element which is secured on a caulking of the support tube with the toothed shaft axially on this.

FIG. 1 shows a portion of a toothed shaft 14 and, for example, a single sliding element 10, and the sliding element 10, as well as other sliding elements 10, can be pushed onto the toothed shaft 14 to form a camshaft. For torque transmission between the sliding element 10 and the toothed shaft 14, the sliding element 10 has an internal toothing 15 in one passage, and the toothed shaft 14 has an external toothing 16. Furthermore, it is shown that in the splined shaft 14, two interruptions 18 are introduced, which have an axial distance from each other, which corresponds to the axial distance of end-side sections 20 of the sliding element 10. If the toothed shaft 14 is inserted into the sliding element 10, then the internal toothing 15 engages in the external toothing 16. Thus, the sliding element 10 is rotationally fixed and arranged displaceably in the axial direction 13 on the toothed shaft 14.

The sliding element 10 has a support tube 12, and on the support tube 12 cam elements 11.1 and 11.2 are added. Between the cam elements 11.1 and 11.2 is a bearing bridge 22, which may be part of, for example, a module hood for forming a camshaft module or a cylinder head. In this case, the sliding element 10 is rotatably mounted on the support tube 12 with a bearing portion 21 in the bearing bracket 22.

At the end sides seen in the axial direction 13, in particular outside the setting points for receiving the cam elements 11. 1 and 11. 2, the carrier tube 12 has the end-side sections 20 with a reduced wall thickness. The reduced wall thickness results from the fact that the outer diameter of the support tube 12 is reduced in the end-side sections 20. If the toothed shaft 14 is inserted into the sliding element 10 in the direction of the arrow shown, the arrangement according to FIG FIG. 2 , as described below.

FIG. 2 shows a camshaft 1 in a sectional view, wherein the toothed shaft 14 is guided by a sliding member 10, and wherein the toothed shaft 14 has two interruptions 18 in the form of circumferential grooves, and the interruptions 18 correspond to the axial position along the axial direction 13 with the end-side portions 20. For caulking the support tube 12 to the toothed shaft 14 is a caulking 23, which is shown with two punches that can be fed radially in the direction of arrow on the end-side section 20 for plastic deformation. When the caulking tool 23 is activated, local caulking of the end-side portion 20 into the break 18 of the spline shaft 14 can be achieved, as in the following FIG. 3 shown.

FIG. 3 shows a sectional view of the camshaft 1 with the toothed shaft 14, on which the sliding element 10 is received. The support tube 12 is defined on both end sides in the axial direction 13 with the end-side portion 20, and sections of material parts 19 of the end-side portions 20 have been caulked in the interruption 18 by plastic deformation, by, as in FIG. 2 shown, the caulking 23 has been activated. By forming the section-wise material part 19 in the interruption 18 a positive connection in the axial direction 13 between the support tube 12 and the toothed shaft 14 is generated, whereby the sliding element 10 is fixed immovably on the toothed shaft 14 in the axial direction 13.

The sliding element 10 is taken up by way of example in a bearing bridge 22, and further sliding elements 10 may be accommodated adjacent to the illustrated, fixed sliding element 10 on the toothed shaft 14, which remain axially displaceable and can also be accommodated in bearing bridges 22.

The invention is not limited in its execution to the above-mentioned preferred embodiment. Rather, a number of variants is conceivable, which makes use of the illustrated solution even with fundamentally different types of use. All of the claims, the description or the drawings resulting features and / or advantages, including design details or Rämlicher arrangements may be essential to the invention both in itself and in various combinations.

LIST OF REFERENCE NUMBERS

1

camshaft

10

sliding element

11.1

cam member

11.2

cam member

12

support tube

13

axially

14

splined shaft

15

internal gearing

16

external teeth

17

caulking

18

interruption

19

section-wise material part

20

end-sided section

21

bearing section

22

bearing bridge

23

caulking

Claims (11)

1. Camshaft (1) for a multiple-cylinder internal combustion engine

   - with sliding elements (10) comprising at least two cam elements (11.1, 11.2) for selective control of valves of the internal combustion engine, and

   - with a toothed shaft (14) which extends in an axial direction (13) and on which the sliding elements (10) are received, and

   - the sliding elements (10) having an internal toothing (15) which interacts with an external toothing (16) of the toothed shaft (14), so that the sliding elements (10) are seated in a torque proof manner on the toothed shaft (14), and at least one first sliding element (10) being received in an axially slidable manner on the toothed shaft (14),

   characterized in that, for axial fixing to the toothed shaft (14), at least one second of the sliding elements (10) comprises a positive fit formed in the axial direction (13), which is produced by at least one caulked connection (17) between the sliding element (10) and the toothed shaft (14).
2. Camshaft (1) according to Claim 1, characterized

   - in that the toothed shaft (14) comprises at least one interruption (18) of the external toothing (16), which interruption (18) is configured at at least one axial position and into which a material part (19) of the at least one second sliding element (10) is caulked in sections,
   and/or

   - in that the at least one second sliding element (10) comprises a receiving geometry, into which a material part of the toothed shaft (14) is caulked in sections.
3. Camshaft (1) according to Claim 1 or 2, characterized in that the at least one second sliding element (10) comprises a support tube (12), on which the cam elements (11.1, 11.2) are received, the at least one caulked connection (17) being configured between the support tube (12) and the toothed shaft (14).
4. Camshaft (1) according to Claim 3, characterized in that the support tube (12) comprises at least one end-side section (20) with a reduced tube wall thickness, the at least one caulked connection (17) being configured in the region of the end-side section (20).
5. Camshaft (1) according to one of the preceding claims, characterized in that at least two, preferably at least three and particularly preferably four caulked connections (17) are formed between the sliding element (10) and the toothed shaft (14) in a manner which is distributed on the circumference of the toothed shaft (14), which caulked connections (17) are each provided, in particular, on both axial end sides of the at least one second sliding element (10).
6. Camshaft (1) according to one of the preceding claims, characterized in that the interruption (18) in the toothed shaft (14) is formed by a circumferential groove in the toothed shaft (14).
7. Camshaft (1) according to one of the preceding claims, characterized in that at least the at least one second sliding element (10) has a bearing section (21), by which the at least one second sliding element (10) can be received in a rotatably mounted manner on a bearing bracket (22).
8. Method for producing a camshaft (1) for a multiple-cylinder internal combustion engine, the camshaft (1) comprising a plurality of sliding elements (10) which comprise at least two cam elements (11.1, 11.2) for controlling valves of the internal combustion engine, and a toothed shaft (14) being provided which extends in an axial direction (13) and extends through the sliding elements (10), the sliding elements (10) comprising an internal toothing (15) which interacts with an external toothing (16) of the toothed shaft (14), so that the sliding elements (10) are seated in a torque proof manner on the toothed shaft (14), and at least one first sliding element (10) being axially slidable, the method comprising at least the following steps:

   - provision of the sliding elements (10) and the toothed shaft (14),

   - guiding of the toothed shaft (14) through the sliding elements (10), and

   - production of at least one caulked connection between at least one second sliding element (10) and the toothed shaft (14) in order to form a positive fit for fixing (13) the at least one second sliding element (10) in the axial direction on the toothed shaft (14).
9. Method according to Claim 8, characterized in that the at least one second sliding element (10) is provided with a support tube (12) which comprises at least one end-side section (20) with a reduced tube wall thickness, the caulking being carried out in the region of the end-side section (20).
10. Method according to Claim 8 or 9, characterized in that the provision of the at least one second sliding element (10) takes place in a manner which is arranged in a bearing bracket (22) of a camshaft module, so that the caulking of the support tube (12) on the toothed shaft (14) is performed in or on the camshaft module.
11. Method according to one of Claims 8 to 10, characterized in that a caulking tool (23) is provided, by which the caulking of the at least one second sliding element (10) on the toothed shaft (14) is carried out, the caulking being performed, in particular, when at least the at least one second sliding element (10) is arranged in a bearing bracket (22) of a camshaft module.

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