DE102014222671B3 - Sliding cam system with XS groove and bridge to secure the actuation function at a minimum switching speed - Google Patents

Abstract

The invention relates to a sliding cam system (1) having a sliding cam (2) arranged on a shaft for rotational movement but axially displaceable and having two cam grooves (3, 4) extending along its circumference, a first cam groove (3) being formed by a second cam groove (3). 4) is interrupted in at least one crossing region (6) such that the second guide groove (4) forms a deeper groove base (7, 8) than the first guide groove (3) in this crossing region (6), and wherein at least one actuating pin (5 ) upon immersion in the first or second cam groove (3, 4) forces the sliding cam (2) to displace axially upon rotation of the sliding cam (2), wherein in the crossing region (6) a flexible bridging section (9) is provided for one the actuating pin (5) in its relative sliding along the first guide groove (3) bridging the intersection region (6) supported, on the other such geometric and / or constructive on a, in the actuating pin (5) introduced recess (10) is adjusted, that the actuating pin (5) at a relative sliding along in the second cam groove (4) the crossing region (6) by pushing the bridging section (9) passes through the recess (10) ; and a valve train for an internal combustion engine of a motor vehicle with such a shift cam system (1).

Description

The invention relates to a sliding cam system with a rotationally fixed on a shaft but axially displaceable sliding cam with a first cam groove and a second cam groove extending along the circumference of the sliding cam, wherein the first cam groove is interrupted by the second cam groove in an intersection region such that the second gate groove in the crossing region forms a deeper groove bottom than the first cam groove, and with an actuating pin which forces the sliding cam to an axial displacement during rotation of the sliding cam when immersed in the first or second cam groove. In this case, a bridging portion is provided, which supports the actuating pin in its relative sliding along in the first cam groove for bridging the crossing area and having a nose which projects beyond the groove base of the second cam groove so far from the first cam groove in the crossing region, that a remaining gap in the first slide groove is smaller than a width of the actuating pin at its respective groove bottom contacting end. The invention also relates to a valve train with such a sliding cam system.

Such sliding cam system is from the DE 10 2009 053 116 A1 known.

Electromagnetic actuators are already known from the prior art. Also actuating devices are known therefrom, which usually have actuating pins and, depending on the position of this actuating pin, actuate the sliding cam in a displaceable manner. Such an actor is about from the WO 2008/155119 A1 known, wherein the electromagnetic actuator comprises a plurality of electromagnetic actuator units.

The not pre-published DE 10 2013 220 554 A1 discloses a variable stroke valve train of an internal combustion engine with a camshaft comprising a carrier shaft and a rotationally fixed and slidably disposed between two axial positions cam piece (also referred to as sliding cam) comprising a cam group of adjacent cams with different cam lobes and a groove-like Axialkulisse with outer guide walls to specify two Having in a crossing region crossing gateways. In addition, an engaging in the Axialkulisse actuating pin for moving the cam piece in the direction of both cam tracks is included, the groove bottom of a slide track and the groove bottom of the other slide track radially offset from each other, so that the lower slide track is given after the crossing region by an inner guide rail , which is formed by the height offset. The higher slide track after the crossing area is also defined by a further inner guideway, which rises stationary with the Axialkulisse from the groove bottom of the higher slide track and connects axially without gaps to that outer track, which dictates the higher slide track before crossing area.

In these known sliding cam systems, in particular in embodiments with a classic "XS-groove" often the Aktorpin (actuating pin) in the crossing region between the "X-groove" (first cam groove) and the "S-groove" (second gate groove) is not form-fitting the level of the X-groove (first gate groove) held. In particular, at low speeds of the internal combustion engine (such as at a starter speed <400 revolutions per minute), it is not possible in the classic XS groove design, drive over the intersection / intersection of the two sliding grooves with the Aktorpin over it without the Aktorpin unintentionally in the lower S-groove (second gate groove) moves and thus the cam piece unintentionally switches back to the original starting position. Such a falling in of the Aktorpins (actuating pin) from the first cam groove in the second cam groove (that is, in the lower S-groove) is absolutely to be avoided.

It is therefore the object of the present invention to remedy these known from the prior art disadvantages and to provide a sliding cam system available, in which a targeted switching is to be made possible even at low speeds, at the same time the sliding cam system also be designed cost and robust should.

This is inventively achieved in that the bridging portion is flexible (ie elastically bendable / deformable), resiliently adjusted between a first and a second relative position and geometrically and / or constructively tuned to a recess introduced in the actuating pin that the actuating pin at a relative length sliding in the second cam groove passes through the crossing region by pushing the bridging portion through the recess.

As a result, an unhindered method of the actuating pin is implemented in the respective engaged state of the actuating pin in the sliding cam. On the one hand, the actuating pin does not fall down, especially at low speeds, from the first to the second sliding groove; on the other hand, a simple guidance of the actuating pin in the second sliding groove is implemented particularly cost-effectively with the aid of the recess in the actuating pin, wherein the actuating pin unhindered, ie substantially unrestrained and low friction / wear sliding through the crossing region of the second cam groove along. Therefore, this design is also made particularly inexpensive, since it only requires a relatively easy-to-manufacture recess in the actuating pin and the groove grooves do not have to be great geometric changes / adapted.

The bridging section has a nose which partially overlaps / overlaps the second cam groove (that is to say its groove bottom) extending radially outside the second guide groove. Thus, the bridging area is designed particularly simple. Preferably, the radial outer side of the nose is arranged at the same height level of the (first) groove bottom of the first cam groove and designed as an extension of the first cam groove.

In the intersection region, the nose projects beyond the second guide groove so far from the first guide groove that a remaining gap in the first guide groove (which gap exposes the second guide groove radially inward) is smaller than a width of the actuating pin at its end contacting the respective groove base. his face). Because a bridging of the crossing area is made even easier.

Further advantageous embodiments are claimed in the subclaims and explained in more detail below.

Furthermore, it is also advantageous if the bridging portion is formed as a separate component. Thus, the already produced in mass shift cam can be easily prepared by the respective bridging portion simply on the sliding cam later, namely preferably after molding the slide grooves, is attached.

If the bridging portion is formed from a metal sheet, then the bridging portion is even more cost-effective, preferably by cold forming, producible.

It is also expedient if the bridging section is fastened in a material, force and / or form-fitting manner, preferably in the second sliding groove. As a result, a particularly simple attachment of the bridging section is implemented in the crossing area.

Is in this context, the bridging portion with the groove bottom of the first cam groove, preferably the second cam groove, screwed or riveted or welded, the bridging portion is particularly space-saving attachable.

In this context, it is also particularly advantageous if the bridging portion is formed as a, viewed in cross section, U-shaped ausgestaltetes component. A second leg of the U is preferably fixed in the second groove base, while a first leg of the U preferably forms the nose which allows the bridging. Both legs are further preferably integrally connected to a connecting web. As a result, the bridging portion in its separate embodiment is also advantageously as a stamped and / or bent part, easy to manufacture.

It is also advantageous if the bridging section is arranged to be elastically movable / pivotable between two relative positions. In this context, it is particularly advantageous if the bridging section serves as a bridge in a first relative position and, in a second relative position, enables insertion of the actuating pin from radially outward into the second guide groove. As a result, a fuse is implemented, which makes it possible that even with too slow retraction of the actuating pin in the second cam groove does not lead to a damaging contact between the actuating pin and the bridging section. Too slow retracting z. B. at high speeds, at low engine temperatures (with even high viscosity of the engine oil) or come through dirt in the actuator, since a relationship between engine speed, engine temperature and degree of contamination / aging of the actuator. As a result, the sliding cam system is designed to be particularly durable.

If the nose of the bridging portion is elastically pivotable / movable relative to a fixing portion of the bridging portion, the bridging portion is made more durable.

Furthermore, a valve drive for an internal combustion engine of a motor vehicle, such as a passenger car, truck, bus or agricultural utility vehicle, with such a sliding cam system is also included. As a result, a valve train is designed to be particularly efficient.

In principle, different valve lifts on the engine valves of an internal combustion engine (eg stroke reversal, lift shutoff) can be realized with the aid of the sliding camshaft, these valve lift variations serving to increase the efficiency and performance of the engine / internal combustion engine. The object of the invention includes in detail this displacement groove contour on the cam piece (sliding cam) of a sliding camshaft.

In a first approach, not according to the invention, a kind of "XSI-groove" with a rigid bridge is designed. For this, the usual XS-groove is provided with a fixed bridge. Here, a narrowing (the groove / the second gate groove) is enforced by a bridge in the crossing region of the two grooves on the S-groove (second gate groove). This bridge serves to eliminate the gap, through which the pin (actuating pin) can slip in the crossing area in the deeper S-groove. However, to allow the pin to pass unhindered through the S-groove, a recess (undercut) must be made on the pin, as this allows the bridge to penetrate through this recess in the pin.

To increase system security, an additional backup is integrated in a second approach. In this case, the XSI groove is provided with a flexible bridge which is resilient, namely as a resilient, flexible sheet metal / metal sheet. The further advantage of this solution is that in case of too slow tracking of the Aktorpins in the bottom of the S-groove, the bridge can escape to the rear and thus no crash between pin and groove. It would come in this case only to a partial overlap between pin and groove, but this is classified as uncritical. Another advantage of this solution is that the spring plate must spring back only in case of a crash hazard and thus a time-stability of the sheet seems sufficient. The sheet metal can either be pinned on the groove base, screwed or welded in accordance with previously adjusted heat treatment of the sliding link (the sliding cam) on the groove base.

The invention will now be explained in more detail with reference to figures. The in the 1 to 3 illustrated first embodiment is not inventive.

Show it:

1 4 is an isometric view of a portion of a shift cam of a push cam system according to the first embodiment, wherein in the illustrated state, the actuation pin slides along the second cam groove, pushing the bridging portion through the recess provided in the actuation pin;

2 a detailed view in isometric view of the crossing area similar to the 1 , where now the bridging section can be seen particularly well from the side,

3 a longitudinal sectional view through in the 1 shown sliding cam portion in a peripheral region of the crossing region, wherein particularly well the bridging portion is visible in its inserted into the recess of the actuating pin state,

4 an isometric view of a portion of a sliding cam of a sliding cam system according to the invention according to a second embodiment, wherein, in contrast to the first embodiment, the bridging portion is formed as a separate sheet metal component,

5 a longitudinal sectional view in the crossing region of the sliding cam section of 4 wherein the actuating pin is shown cut in the longitudinal direction and on the one hand the intrusion of the bridging portion into the recess of the actuating pin, on the other hand the attachment of the bridging portion in the (second) groove bottom of the second cam groove can be seen

6 an isometric view of the sliding cam section after the 4 and 5 in a peripheral region of the crossing region, the extension, the course and the arrangement of the bridging section being particularly well recognizable,

7 an isometric representation of the in the 4 to 6 used bridging section, with its underside is particularly well to recognize, are attached to the alignment on the sliding cam portion alignment projections, and

8th another isometric view of the in 7 Bridging section already shown from one side, which shows particularly well the curved course of the bridging section.

The figures are merely schematic in nature and are for the sole purpose of understanding the invention. The same elements are provided with the same reference numerals.

In the 1 to 8th are in principle two different embodiments of the sliding cam system 1 shown. The sliding sock system 1 is always part of a valve drive of an internal combustion engine, not shown here for clarity, such as a gasoline or diesel engine, a motor vehicle, such as a car, truck, bus or agricultural utility vehicle. The sliding sock system 1 also always has a here for clarity not shown and formed as a carrier shaft shaft. Rotationally fixed with this shaft, but axially displaceable on this shaft, in each case at least one sliding cam 2 arranged. The sliding cam 2 each has the in the 1 to 6 illustrated adjustment range 12 on. Also, the pushers 2 a plurality of, at least two differently shaped or out of phase with each other arranged cam, which are not shown here for clarity's sake.

On the carrier shaft are a plurality of identically formed sliding cam 2 arranged side by side in the axial direction. Each inlet and / or outlet valve is such a sliding cam 2 intended. The at least one sliding cam 2 forms together with the shaft of a camshaft of the internal combustion engine, whereby by means of the sliding cam system 1 in the usual way, the valve lift and / or the opening and closing time of the sliding cam 2 associated valve is enabled.

Every sliding cam 2 points (eg 1 ) in the adjustment range 12 two along the circumference extending grooves 3 and 4 on. These two scenes grooves 3 and 4 intersect in a crossing area 6 , Thus, a first Kulissennut 3 (also referred to as X-groove) geometrically through the second gate groove 4 (also referred to as S-groove) interrupted. The first and second scenery grooves 3 and 4 are each for the interaction with at least one actuating pin 5 intended. The second scenery groove 4 points in this crossing area 6 a deeper (second) groove bottom 8th on as the first backdrop groove 3 , In other words, the second gate groove 4 in the crossing area 6 deeper than the first scenery groove 3 running / introduced, so that the (second) groove bottom 8th the second scenery groove 4 deeper than the (first) groove bottom 7 the first scenery groove 3 ,

The actuating pin 5 , which is part of a Betätigungsaktuators also not shown here for clarity, immersed to move the sliding cam 2 such in the radial direction with its the adjustment 12 facing end face / face in the respective groove 3 or 4 radially in that, after dipping, it displaces the sliding cam 2 upon rotation of the shaft or sliding cam 2 relative to the actuating pin 5 comes. In this relative movement of the actuating pin 5 to the respective Kulissennut 3 or 4 it comes because of the pressing of the actuating pin 5 on the respective side flanks of the Kulissennuten 3 or 4 to a shifting of the adjustment range 12 and thus the cam associated with it.

In the crossing area 6 is always a bridging section in the two embodiments 9 provided, on the one hand the actuating pin 5 with a relative sliding along in the first gate groove 3 to bridge the crossing area 6 supports and thus this in the Kulissennut 3 Run without this in the second Kulissennut 4 falls down. On the other hand, the bridging section 9 such relative to one in the actuating pin 5 introduced recess 10 arranged to slide relative relative to the second gate groove 4 the crossing area 6 by pushing the bridging section 9 through the recess 10 happens.

As initially it is particularly well in connection with the first embodiment of the 1 to 3 can be seen, the bridging section 9 a nose 11 on. In this first embodiment, the bridging section is 9 completely through the nose 11 educated. This nose 11 (Also referred to as a projection, extension or survey) extends so from a side edge 13 the second scenery groove 4 in extension of the first gate groove 3 over the second groove bottom 8th that she is the first set of scenes 3 or their groove bottom 7 in the crossing area 6 extended so that the second gate groove 4 partially, namely in a certain section by means of this bridging section / nose 11 bridged / covered / overlapped.

The nose 11 extends, as well as in particularly well 2 can be seen, essentially over the entire width of the first gate groove 3 , along the first side flank 13 , It can therefore also be seen that this nose 11 integral part of the second scenery groove 3 is, where they have the first groove bottom 7 continuous forms.

In 3 is further to realize that the recess 10 the rod-shaped actuating pin 5 (With a circular cross-section) is formed as an annular groove, the outer diameter / the outer circumferential surface of the actuating pin 5 tapered annular. In the area of his face 14 is the actuating pin 5 but opposite the recess 10 thickened again. Ie. the actuating pin 5 shows how particularly good in 3 to recognize, in the area of its face 14 a larger width / diameter (extension transverse to the longitudinal axis of the actuating pin 5 ) than in the area of the recess 10 , The width of the actuating pin 5 in the area of the face 14 is chosen to be greater than a width of one between the nose 11 (from the first side flank 13 ) and one of those nose 11 / the first side flank 13 circumferentially opposite second side edge 15 formed gap 17 , The width of the gap 17 (ie the dimension of the gap 17 across to the second scenery groove 4 ) is greater than the width of the actuating pin 5 in the area of its recess 10 , So it comes with a drive through the actuating pin 5 through the first scenery groove 3 not to fall into the second gate groove 4 but to secure supporting and holding the end face 14 of the actuating pin 5 at the height of the first slot base 7 when sliding along the actuating pin 5 in the first scenery groove 3 over the crossing area 6 time. As continues in 3 It is easy to see that the nose is there 11 arranged at such a height (corresponds to the height of the first groove bottom 7 ) that nose 11 in the recess 10 engages when the actuating pin 5 on the second groove bottom 8th rests. The difference in height between the nose 11 and the second groove bottom 8th is slightly smaller than the height difference between the face 14 and the face 14 opposite end of the recess 10 and slightly larger than the height difference between the face 14 and the face 14 facing the end of the recess 10 ,

The second embodiment is in 4 to 8th good to recognize, this second embodiment is formed substantially like the first embodiment. Therefore, only the differences between the first and second embodiments will be discussed below.

The bridging section 9 is no longer an integral part of a nose 11 formed, but as a separate sheet metal 18 as it is especially good in the alone 7 and 8th can be seen.

The metal sheet 18 again has a nose 11 on, at the same height as well as substantially the same size and equally far beyond the second groove bottom 8th protrudes like the nose 11 according to the first embodiment. The metal sheet 18 is viewed in cross-section substantially U-shaped / J-shaped. A first leg / a first side bar 19 of the metal sheet 18 forms the nose 11 immediately out. Another, second leg / a second side bar 20 is as a mounting area of the bridging section 9 formed and in the second groove bottom 8th the second scenery groove 4 attached. The nose 11 is relative to the attachment area / second side bar 20 resiliently movable between two subsequently explained relative positions movable / swiveled / deformable.

The metal sheet 18 / the bridging section 9 is elastic in this second groove bottom 8th arranged so that it is bendable elastic / resiliently pivotable between two relative positions. In the 4 to 6 is particularly well represented the first relative position, in which case the nose 11 serves as a bridging part and here has the same arrangement as the nose 11 according to the first embodiment. In a second, here for the sake of clarity not shown relative position is then the bridging section 9 pivoted so resiliently relative to the first relative position that a dipping of the actuating pin 5 in the second groove bottom 4 is possible. In this second relative position, therefore, the bridging section 9 especially his nose 11 so swung that the width of the gap 17 ie the distance between the nose 11 and the second side flank 15 (in the crossing area 6 ) is greater than the diameter / width of the end face 14 of the actuating pin 5 so that the actuating pin 5 radially inward into the second gate groove 4 free (ie unhindered by the nose 11 ) can be inserted. As a result, even at relatively fast speeds dipping the actuating pin, if wanted, in the second cam groove 4 possible without the bridging section 9 is damaged.

The metal sheet 18 is preferably material, force and / or positive fit in the second cam groove 8th attached. In this embodiment, by means of the alignment projections 16 initially implemented a positive connection, wherein the alignment projections 16 in corresponding recesses in the second groove bottom 4 are engaged. Alternatively or additionally, however, it is also possible to achieve a non-positive and positive connection by means of screws or rivets, in which case in turn the second groove bottom 8th facing thighs 20 screwed or riveted. Alternatively or additionally, it is also possible here, this leg 20 with the second groove bottom 8th to be welded, possibly before a heat treatment of the second groove bottom 8th or the adjustment range 12 is performed. Alternatively, it is also possible to use the bridging section 9 with the first groove bottom 7 connect to.

In other words, an XS groove is thus used as the basic design, but the modified pin does not allow the pin to retract unintentionally into the deeper S-groove. An additional bridge, which is preferably designed to be flexible, is used to avoid unwanted leaving the X-groove in the S-groove at the intersection at low speeds. The bridge is formed in the rigid variant as an undercut on the groove cheek of the S-groove. In a flexible embodiment, the flexible bridge is formed in the form of an additional spring element which is secured to the groove bottom of the S-groove, wherein the spring element is preferably formed as a stamped and bent part. This spring element can spring back away in the event of a crash and, due to the low likelihood of occurrence of this situation, it only has to be designed for fatigue strength. The Aktorpin is a recess through which the bridge can dive in the crossing point.

LIST OF REFERENCE NUMBERS

1

Sliding cam system

2

pushers

3

first scenery groove

4

second scenery groove

5

actuating pin

6

crossing area

7

first groove bottom

8th

second groove bottom

9

bridging portion

10

recess

11

nose

12

adjustment

13

first side flank

14

face

15

second side flank

16

alignment projection

17

gap

18

metal sheet

19

first side bar

20

second side bar

Claims (7)

Sliding cam system ( 1 ) with a non-rotatably on a shaft but axially displaceable sliding cam ( 2 ) with a first gate groove ( 3 ) and a second gate groove ( 4 ) along the circumference of the sliding cam ( 2 ), wherein the first cam groove ( 3 ) through the second gate groove ( 4 ) in a crossing area ( 6 ) is interrupted such that the second gate groove ( 4 ) in the crossing area ( 6 ) a deeper groove bottom ( 7 . 8th ) as the first gate groove ( 3 ) and with an actuating pin ( 5 ) when diving into the first or second gate groove ( 3 . 4 ) the sliding cam ( 2 ) to an axial displacement upon rotation of the sliding cam ( 2 ), whereby a bridging section ( 9 ) is provided which the actuating pin ( 5 ) in its relative sliding along in the first gate groove ( 3 ) for bridging the crossing area ( 6 ) and a nose ( 11 ) located in the crossing area ( 6 ) the groove bottom ( 8th ) of the second gate groove ( 4 ) so far from the first scenery groove ( 3 ) surmounted that a remaining gap in the first gate groove ( 3 ) smaller than a width of the actuating pin ( 5 ) at its the respective groove bottom ( 7 . 8th ) contacting end, characterized in that the bridging section ( 9 ) flexible, resiliently movable between a first and a second relative position and thus geometrically and / or constructively on a in the actuating pin ( 5 ) introduced recess ( 10 ) that the actuating pin ( 5 ) with a relative sliding along in the second sliding groove ( 4 ) the crossing area ( 6 ) while pushing the bridging section ( 9 ) through the recess ( 10 ) happens. Sliding cam system ( 1 ) according to claim 1, characterized in that the bridging section ( 9 ) is formed from a separate component. Sliding cam system ( 1 ) according to claim 1 or 2, characterized in that the bridging section ( 9 ) is formed from a metal sheet. Sliding cam system ( 1 ) according to one of claims 1 to 3, characterized in that the bridging section ( 9 ) is fixed material, force and / or positive fit. Sliding cam system ( 1 ) according to one of claims 1 to 3, characterized in that the bridging section ( 9 ) with the groove bottom ( 7 . 8th ) of the first or second gate groove ( 3 . 4 ) screwed or riveted or welded. Sliding cam system ( 1 ) according to one of claims 1 to 5, characterized in that the nose ( 11 ) relative to a mounting area of the bridging section (FIG. 9 ) is elastically pivotable. Valve drive for an internal combustion engine of a motor vehicle with a sliding cam system ( 1 ) according to one of claims 1 to 6.

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