DE102014109827A1 - Method for grinding machining cam elements of an adjustable camshaft - Google Patents

Abstract

The present invention relates to a method for grinding cam elements (10) of an adjustable camshaft (1), wherein the cam elements (10) to be ground are fixedly mounted on an outer shaft (11) of the adjustable camshaft (1), and on the outer shaft ( 11) rotatable cam elements (12) are rotatably received. According to the invention, the method comprises at least the following steps: clamping the outer shaft (11) with the fixed cam elements (10) and with the rotatable cam elements (12) in a grinding device, providing a gripping device (13) and gripping at least one rotatable cam element ( 12) so that the rotatable cam member (12) is held by the gripping device (13), and - grinding the fixed cam member (10) while rotating the outer shaft (11) and the fixed cam members (10).

Description

The present invention relates to a method for grinding of cam elements of an adjustable camshaft, wherein the cam elements to be ground are fixedly arranged on an outer shaft of the adjustable camshaft, and wherein on the outer shaft further cam elements are rotatably received.

State of the art

The DE 10 2006 044 010 A1 teaches a method of grinding camshaft cam elements of an adjustable camshaft, and to prevent grinding dust resulting from the grinding process from entering the camshaft, it is proposed to press a fluid under pressure into the outer shaft. The fluid acts as a barrier fluid and, for example, an oil or gas is proposed as the fluid.

Adjustable camshafts have an outer shaft and an inner shaft, wherein fixedly arranged on the outer shaft cam elements are provided, and the other rotatably received on the outer shaft cam elements are rotatably connected via bolts with the inner shaft. If the inner shaft is rotated in the outer shaft, the rotatable cam elements can be adjusted in their phase position relative to the fixed cam elements.

The annular gap between the outer side of the inner shaft and the inner side of the outer shaft must remain free of contamination for trouble-free, permanent operation of the adjustable camshaft, so that it is urgent to prevent the grinding dust from entering the annular gap. The bolts for connecting the rotatable cam elements with the inner shaft pass through recesses in the outer shaft, so that even through these recesses grinding dust can get into the interior of the outer shaft. If the outer shaft is pressurized with a fluid, the fluid can act as a barrier fluid and grinding dust can not penetrate through the recesses in the outer shaft in the annular gap between the outer shaft and the inner shaft. Furthermore, it can be at least partially prevented that grinding dust enters the bearing seat between the outer side of the outer shaft and the receiving bore of the rotatable cam elements.

The fixed cam elements are applied in a conventional manner via a pressing process on the outside of the outer shaft, wherein alternately a fixed cam element are threaded with a rotatable cam member on the outer shaft. The fixed cam elements are applied via a longitudinal compression bandage, while the rotatable cam elements are merely pushed and remain freely rotatable on the outer shaft. Subsequently, the rotatable cam elements are connected via bolts with the inner shaft, and in the grinding both the cam elements fixedly mounted on the outer shaft and the cam elements fixedly connected to the inner shaft can be sanded. A final grinding of the fixed cam elements is not possible, since by the pressing of the cam elements on the outer shaft, an insufficient positional accuracy prevails, in particular, the outer shaft bearing rings, which must be machined in one clamping with the cam profiles of the fixed cam elements. A complete assembly of the adjustable camshaft exclusively made of finished components, in particular exclusively from finished cam elements is therefore not possible, and it must be made a grinding machining at least the fixed cam elements, which are already applied to the outer shaft.

The pressurization with a barrier fluid, such as barrier oil or sealing air, requires increased equipment costs, also may have the disadvantage that the barrier fluid may not be reused and must be disposed of. Also, the grinding process can be adversely affected by the barrier fluid.

The US 6, 182, 362 B1 teaches a further variant of a method for grinding camshaft cam elements of an adjustable camshaft, and to prevent the ingress of grinding dust into the camshaft, it is proposed to introduce a viscous or a solid material into the interstices of the individual components of the adjustable camshaft. Disadvantageously, the viscous or solid material must be removed again after grinding. This can be done for example by the use of wax by the adjustable camshaft is heated so that the wax can escape from the interstices of the individual components again. A residue-free removal of the barrier materials in the interstices of the components of the adjustable camshaft, however, is very complicated.

Disclosure of the invention

The object of the invention is the development of a method for grinding of cam elements of an adjustable camshaft, which can be easily performed and in particular to prevent grinding dust can penetrate into intermediate spaces of individual components of the adjustable camshaft.

This object is achieved on the basis of a method for grinding of cam elements of an adjustable camshaft according to the known features of claim 1 in conjunction with the characterizing features. Advantageous developments of the invention are specified in the dependent claims.

• – Einspannen der Außenwelle mit den festen Nockenelementen und mit den drehbaren Nockenelementen in einer Schleifvorrichtung,
• – Bereitstellen einer Greifvorrichtung und Greifen wenigstens eines drehbaren Nockenelementes, so dass das drehbare Nockenelement durch die Greifvorrichtung festgehalten wird und
• – Schleifbearbeiten des festen Nockenelementes unter Rotation der Außenwelle und der festen Nockenelemente.

The invention teaches a method with at least the following steps:

• Clamping the outer shaft with the fixed cam elements and with the rotatable cam elements in a grinding device,
• - Providing a gripping device and gripping at least one rotatable cam member, so that the rotatable cam member is held by the gripping device and
• Grinding the fixed cam member while rotating the outer shaft and the fixed cam members.

The inventive development of a grinding method for grinding of cam elements of an adjustable camshaft with a gripping device has the advantage that the camshaft to be machined no longer has to be completely assembled to the grinding process. Rather, the adjustable camshaft may be limited to the components of the outer shaft, the cam elements fixedly mounted on the outer shaft and the cam elements rotatably mounted on the outer shaft. As a result, no dust-sensitive gaps and gaps between a plurality of components of the camshaft are formed more, and even with an ingress of sanding dust in the interior of the outer shaft, this can easily remove, for example, by a rinsing process, after grinding again. The introduction of a barrier fluid into the interior of the outer shaft is no longer absolutely necessary, but can still be provided as an advantageous development of the method.

The camshaft may be formed with specific cam pairs formed from the fixed and rotatable cam elements on the outer shaft of the adjustable camshaft. This results in an adjacent arrangement of the rotatable cam elements to the fixed cam elements, and only the fixed cam elements are machined with the grinding, it is ensured according to the invention by the gripping device that the rotatable cam elements on the outside of the outer shaft do not come into contact with a grinding wheel. In this case, the rotatable cam element can be held in a rotational position of the gripping device relative to the grinding wheel so that contact of the held with the gripping device cam element is avoided with the grinding wheel. The rotatable and fixed cam members have respective cam profiles which, by the paired arrangement of the fixed and rotatable cam members, form a common cam profile which can cooperate with a single tappet member to control a valve of an internal combustion engine. The cam profile of the fixed cam member is machined by the grinding work, and the cam profile of the rotatable cam member must be kept out of the machining area of the grinding work so as not to come into contact with the grinding wheel.

With particular advantage, the rotatable cam elements can be provided in a finished state prior to grinding machining and arranged on the outer shaft. An abrasive machining of the rotatable cam elements is therefore no longer necessary in arrangement on the outer shaft of the camshaft. Consequently, it is sufficient that the rotatable cam elements are kept away from the grinding process.

The rotatable cam elements may have transverse bores, wherein the gripping device may comprise at least one tensioning element which is at least partially inserted into at least one transverse bore when a rotatable cam element is gripped. The tensioning element may, for example, comprise centering points which have a conical or conical shoulder which can be inserted into the transverse bore from the outside of the cam element. This has the advantage that the transverse bores are closed, and grinding dust can not enter the transverse bores. In particular, the entry of grinding dust into the bearing seat of the rotatable camshaft on the outside of the outer shaft is substantially avoided. With particular advantage, the gripping device can be designed as a collet and two opposing clamping elements can be used in two opposite transverse bores of the rotatable cam element. Alternatively, the clamping element may also consist of a single mandrel which is inserted into only one transverse bore of the rotatable cam element.

According to a further likewise advantageous embodiment of the gripping device, this can have a clamping element, with which a cam profile formed on the rotatable cam element can be clamped, whereby the rotatable cam element is finally held.

The rotatable cam element can be held by the gripping device with particular advantage centered on the outer shaft. At least while the cam element so of the Centering gripping device that no sliding bearing forces between the cam member and the outside of the outer shaft arise. The advantage is in particular that a grinding in the bearing gap between the rotatable cam member and the outer shaft is avoided because residues of grinding dust can penetrate into the bearing gap. Finally, the camshaft is rotated to achieve a full grinding action over the cam profile of the fixed cam members. The rotation of the outer shaft takes place in the receiving bore of the stationary cam elements, which are fixed with the gripping device.

The pairs of cams comprising at least one or two fixed cam members and at least one rotatable cam member may be formed as a two-compartment cam pair or as a triple cam package. In a 2-compartment cam pair, a fixed cam member is adjacent a rotatable cam member so that the rotatable cam member can be axially displaced on the outside of the outer shaft. In a 3-way cam package, two fixed cam members may sandwich a rotatable cam member so that it is not axially displaceable.

In the case of axially displaceable cam elements, the rotatable cam elements can first be displaced axially in order to achieve a distance to the fixed cam elements to be machined. Subsequently, the gripping device can hold the rotatable cam element, so that grinding machining of a fixed cam element can be performed while maintaining an axial distance to a rotatable cam element.

In addition, a blocking fluid can be introduced into the outer shaft, which is preferably introduced into an inner space of the outer shaft. Due to the known per se use of a barrier fluid may possibly be avoided that the outer shaft with the rotatably received cam elements after grinding must still be subjected to a cleaning.

According to a further development of the gripping device, this can have a flushing housing in which the rotatable cam element is seated when gripping the rotatable cam element, wherein the flushing housing is flushed with a barrier fluid at least during the grinding of the fixed cam element. This results in the advantage that the penetration of grinding dust is avoided in the bearing seat between the rotatable cam elements and the outer side of the outer shaft, wherein only locally, that is used in the region of the rotatable cam elements, the barrier fluid, but not in particular the outer shaft on its interior must be rinsed with a barrier fluid. The use of a gripping device with a flushing housing can preferably take place in a camshaft with double cam pairs, since the rotatable cam elements can be better separated from the fixed cam elements to be ground.

The method of completing the camshaft may be performed by sequentially sequentially grinding a plurality of fixed cam members on the outer shaft, wherein the rotatable cam members associated with the fixed cam members are sequentially held during a respective grinding operation with the gripping device.

Following the grinding process may optionally be carried out cleaning of the outer shaft with the cam elements, only then an inner shaft is inserted into the outer shaft, and the rotatable cam elements on the outer shaft are rotationally connected by bolts with the inner shaft.

Preferred embodiments of the invention

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:

1a a cross-sectional view of a first embodiment for grinding an adjustable camshaft with the features of the present invention,

1b a perspective view of the arrangement according to 1a .

1c a plan view of the arrangement according to 1a .

2a a cross-sectional view of a second embodiment for grinding an adjustable camshaft with the features of the present invention,

2 B a perspective view of the arrangement according to 2a .

2c a plan view of the arrangement according to 2a .

3a a cross-sectional view of a third embodiment for grinding an adjustable camshaft with the features of the present invention,

3b a perspective view of the arrangement according to 3a .

3c a plan view of the arrangement according to 3a .

4a a cross-sectional view of a fourth embodiment for grinding an adjustable camshaft with the features of the present invention,

4b a perspective view of the arrangement according to 4a .

4c a plan view of the arrangement according to 4a ,

In the 1a . 1b and 1c a first embodiment of an arrangement is shown, with which a method for grinding of cam elements 10 an adjustable camshaft 1 can be executed. The 1a shows the arrangement in a cross-sectional view along the section line II, as in 1c shown, where 1b a perspective view shows.

In 1a is a grinding wheel 14 in contact with a fixed cam element 10 shown, and the fixed cam member 10 is on an outside wave 11 the adjustable camshaft 1 applied. The camshaft 1 is rotated in the direction of the arrow shown in rotation, so that the fixed cam member 10 with the rotational movement of the outer shaft 11 rotates, and so that the cam profile 22 the fixed cam element 10 through the grinding wheel 14 can be edited.

The gripping device 13 has two clamping elements 16 on, and the clamping elements 16 the gripping device 13 grab in cross hole 15 one, in the rotatable cam element 12 are introduced. The cam element 12 is on the outside 11 rotatably supported, and by the retention of the rotatable cam member 12 through the gripping device 13 can the outside wave 11 be rotated while the rotatable cam element 12 fixed. This ensures that the cam profile 19 the rotatable cam element 12 not in contact with the grinding wheel 14 passes, since only the cam base circle 23 the rotatable cam element 12 towards the grinding wheel 14 shows. Due to the smaller radius of the cam base circle 23 There remains a radial distance between the grinding wheel 14 and the cam base circle 23 the rotatable cam element 12 , As a result, this is not from the grinding wheel 14 edited, although the rotatable cam element 12 on the outside 11 the adjustable camshaft 1 located. The grinding wheel 14 can in double arrowed direction shown a lifting movement to the outer shaft 11 Run to the cam profile 22 the fixed cam element 11 grind according to the required profile. The clamping elements 16 close the interior 20 the camshaft 1 because these are peg-like in the cross holes 15 incarcerated.

The perspective view in 1b and the top view in 1c illustrate the design of the cam elements 10 and 12 as a 3-way cam package, and on the outer shaft 11 are two fixed cam elements 10 arranged between which is a rotatable cam element 12 located. The camshaft 1 thus has 3-fold cam packages, wherein the gripping device 13 made so narrow that this exclusively between the fixed cam elements 10 arranged rotatable cam element 12 attacks.

In the 2a . 2 B and 2c a second embodiment of an arrangement is shown, with which a method for grinding of cam elements 10 an adjustable camshaft 1 can be executed. The 2a shows the arrangement in a cross-sectional view along the section line II-II, as in 2c shown 2 B a perspective view shows.

The embodiment shows a gripping device 13 with only one clamping element 17 , which is designed as a single spike and in only one transverse bore 15 in the rotatable cam element 12 intervenes. This is another variant of the gripping device 13 shown, and it must not be provided two clamping elements in both transverse bores 15 the rotatable cam element 12 engage this on the rotating outer shaft 11 hold, so that the fixed cam element 10 through the grinding wheel 14 can be edited.

By fixing the rotatable cam element 12 with the clamping element 17 in arrangement in the lower transverse bore 15 also ensures that the cam profile 19 out of contact with the grinding wheel 14 is held so that only the cam base circle 23 the rotatable cam element 12 on the side of the grinding wheel 14 is located, and between the cam base circle 23 and the grinding wheel 14 a radial gap remains.

In the 3a . 3b and 3c a third embodiment of an arrangement is shown, with which a method for grinding of cam elements 10 an adjustable camshaft 1 can be executed. The 3a shows the arrangement in a cross-sectional view along the section line III-III, as in 3c shown 3b a perspective view shows.

In the 3a . 3b and 3c is another variant of the gripping device 13 shown, the clamping elements 18 includes. With the clamping elements 18 becomes the cam profile 19 the rotatable cam element 12 on the outside 11 fixed, so that already by clamping the cam profile 19 a co-rotation of the rotatable cam element 12 on the outside 11 is prevented. Consequently, the cam profiles 22 the fixed cam elements 10 with the grinding wheel 14 are machined while the rotatable cam member 12 is held in its angular orientation so that only the cam base circle 23 towards the grinding wheel 14 shows. This is achieved in a particularly simple manner that the gripping device 13 not necessarily in the cross holes 15 the rotatable cam element 12 must intervene.

In the 4a . 4b and 4c a fourth embodiment of an arrangement is shown, with which a method for grinding of cam elements 10 an adjustable camshaft 1 can be executed. The 4a shows the arrangement in a cross-sectional view along the section line IV-IV, as in 4c shown 4b a perspective view shows.

In the 4a . 4b and 4c is another variant of a gripping device 13 shown for carrying out the method according to the invention, with the fixed cam elements 10 on an outside wave 11 an adjustable camshaft 1 with a grinding wheel 14 can be edited. The gripping device 13 has a flushing housing 21 with an upper half of the housing 24 and a lower housing half 25 on, and over flush pipes 26 can the flushing housing 21 be flushed with a barrier fluid, so that in the flushing housing 21 in which the rotatable cam element 12 in arrangement on the outer shaft 11 is seated, no grinding dust can penetrate. It can in Spülkammer 21 an overpressure can be built up with the flushing fluid, whereby in particular a penetration of grinding dust into the flushing housing 21 is prevented.

On the housing halves 24 and 25 are clamping elements 27 attached, which is a co-rotation of the rotatable cam element 12 on the outside 11 by sitting in the transverse bores 15 the rotatable cam element 12 prevent.

The flushing housing 21 consists of two half shells, passing through the housing halves 24 and 25 are formed, and the housing halves 24 and 25 are brought to one another substantially fluid-tight. In this case, the housing halves 24 and 25 have lateral outputs through which the outer shaft 11 extending through only a small gap to the outputs. The advantage is in particular a very low consumption of flushing fluid, since it may be sufficient, the flushing housing 21 only to be placed under slight overpressure with the flushing fluid.

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

LIST OF REFERENCE NUMBERS

1

 adjustable camshaft

10

 fixed cam element

11

 outer shaft

12

 rotatable cam element

13

 gripping device

14

 grinding wheel

15

 cross hole

16

 clamping element

17

 clamping element

18

 clamping element

19

 cam profile

20

 inner space

21

 flushing housing

22

 cam profile

23

 Cam base circle

24

 upper half of the housing

25

 lower half of the housing

26

 flushing line

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 102006044010 A1 [0002]
• US 6182362 B1 [0007]

Claims (10)

Method for grinding of cam elements ( 10 ) an adjustable camshaft ( 1 ), whereby the cam elements ( 10 ) firmly on an outer shaft ( 11 ) of the adjustable camshaft ( 1 ) are arranged, and wherein on the outer shaft ( 11 ) rotatable cam elements ( 12 ) are rotatably received, wherein the method comprises at least the following steps: - Clamping the outer shaft ( 11 ) with the fixed cam elements ( 10 ) and with the rotatable cam elements ( 12 ) in a grinding device, - providing a gripping device ( 13 ) and gripping at least one rotatable cam element ( 12 ), so that the rotatable cam element ( 12 ) by the gripping device ( 13 ) and - grinding the fixed cam element ( 10 ) with rotation of the outer shaft ( 11 ) and the fixed cam elements ( 10 ). Method according to claim 1, characterized in that the rotatable cam elements ( 12 ) are provided in a finished state prior to the grinding operation and on the outer shaft ( 11 ) to be ordered. Method according to claim 1 or 2, characterized in that the rotatable cam elements ( 12 ) with the fixed cam elements ( 10 ) adjacent to each other on the outer shaft ( 11 ) are arranged and form cam pairs for contact with a common tap element and / or wherein the rotatable cam element ( 12 ) in a rotational position of the gripping device ( 13 ) relative to a grinding wheel ( 14 ) is held so that a contact of the with the gripping device ( 13 ) held cam element ( 12 ) with the grinding wheel ( 14 ) is avoided. Method according to one of claims 1 to 3, characterized in that the rotatable cam element ( 12 ) Cross holes ( 15 ), wherein the gripping device ( 13 ) at least one tensioning element ( 16 . 17 ), which upon gripping the rotatable cam element ( 12 ) in at least one transverse bore ( 15 ) is used at least partially. Method according to one of the preceding claims, characterized in that the gripping device ( 13 ) at least one clamping element ( 18 ), with which a rotatable cam element ( 12 ) formed cam profile ( 19 ) is held by clamping, whereby the rotatable cam element ( 12 ). Method according to one of the preceding claims, characterized in that the rotatable cam element ( 12 ) of the gripping device ( 13 ) centered on the outer shaft ( 11 ) is held. Method according to one of the preceding claims, characterized in that the rotatable cam element ( 12 axially spaced from the fixed cam member (FIG. 10 ) by the gripping device ( 13 ) on the outer shaft ( 11 ) is held. Method according to one of the preceding claims, characterized in that the outer shaft ( 11 ) is flushed with a barrier fluid, preferably in an interior ( 20 ) of the outer shaft ( 11 ) is initiated. Method according to one of the preceding claims, characterized in that the gripping device ( 13 ) a flushing housing ( 21 ), in which when gripping the rotatable cam element ( 12 ) the rotatable cam element ( 12 ), wherein the flushing housing ( 21 ) at least during the grinding of the fixed cam element ( 10 ) is rinsed with a barrier fluid. Method according to one of the preceding claims, characterized in that a plurality of fixed cam elements ( 10 ) on the outer shaft ( 11 ) can be processed sequentially one after another, whereby the fixed cam elements ( 10 ) associated with rotatable cam elements ( 12 ) during a respective grinding operation with the gripping device ( 13 ) are recorded one after the other.

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