EP3014079B1 - Adjustable camshaft - Google Patents

Description

The present invention relates to a camshaft for the valve train of an internal combustion engine with an outer shaft and with a concentric in the outer shaft and rotatably received in this inner shaft, wherein on the outer surface of the outer shaft at least one cam member is rotatably supported to form a sliding bearing gap, and wherein the cam member is rotationally connected to the inner shaft.

STATE OF THE ART

Adjustable camshafts for the valve train of an internal combustion engine with an outer shaft on which a cam element is received and which is rotationally connected to an inner shaft which extends through the outer shaft, serve for the variable control of the intake valves and exhaust valves of the internal combustion engine. On the outer shaft further cam elements are rotationally fixed, and the phase angle of the inner shaft is adjusted relative to the phase angle of the outer shaft, so also changed the phase angle of the cam elements, which are rotatably mounted on the outer shaft to form a sliding bearing gap, to the phase position of the cam elements, which are arranged rigidly on the outer shaft. The nested waves rotate about a common axis of rotation in the cylinder head of the internal combustion engine and can be adjusted to each other via a control member in their phase position. The cam elements interact with the valves of the internal combustion engine directly or via rocker arms, and on the cam elements act on control forces that must be taken on the sliding bearing gap of the rotatable mounting of the cam elements on the outer shaft. It has been found that when there is a lack of lubricating oil supply of the sliding bearing gap between the inner surface of the cam elements and the outer surface of the outer shaft wear can be the result, which must always be avoided.

The post-published patent application DE 10 2012 103 594 A1 shows an adjustable camshaft for the valve train of an internal combustion engine with an outer shaft and a rotatably received in the outer shaft inner shaft. On the outer surface of the outer shaft cam elements are rotatably mounted to form a sliding bearing gap and connected rotationally fixed by a bolt with the inner shaft. In order to convey lubricating oil from the installation environment of the camshaft in the sliding bearing gap, it is proposed to introduce at least one Ölfangbohrung in the cam member, so that by the rotation of the camshaft spray oil from the installation environment of the camshaft through the Ölfangbohrung be performed in the sliding bearing gap between the outer shaft and the cam member can. The oil hole is located in the cam element, resulting in disadvantages in the processing. In particular, the introduction of a Ölleitnut in the inner surface of the cam bore of the cam member is expensive, and it has been shown that due to the centrifugal forces during rotation of the camshaft, the lubricating oil remains predominantly in the Ölleitnut, so that it is desirable, the transition of the lubricating oil from the Ölleitnut in to improve the sliding bearing gap.

Also in the DE 10 2005 014 680 A1 is described an adjustable camshaft, wherein in an outer shaft, a concentrically extending and rotatably received in this inner shaft is arranged. On the outer surface of the outer shaft cam elements are rotatably mounted and rotatably connected by a radial opening in the outer shaft with the inner shaft. An annular gap between the outer shaft and the inner shaft is supplied with lubricating oil by long rings, which feeds a large-sized feed channel 19. Solutions for full lubrication of the annular gap are not shown. The publication GB2431977 discloses a similar adjustable camshaft.

DISCLOSURE OF THE INVENTION

The object of the invention is the improved supply of the sliding bearing gap between a cam member and an outer shaft of an adjustable camshaft with lubricating oil, in particular to avoid operating conditions with deficient lubrication of the sliding bearing gap substantially.

This object is achieved on the basis of an adjustable 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 in the outer surface of the outer shaft at least one Ölleitnut is introduced in a position and with an axial length such that the Ölleitnut is formed at least over the axial width of the sliding bearing gap and at least one side of the cam member from the Sliding bearing gap is led out with a free groove portion.

The inventive introduction of at least one Ölleitnut in the outer surface of the outer shaft creates the possibility of oil, referred to in the linguistic usage as lubricating oil, which can enter via the free groove portion in the Ölleitnut to lead over this in the sliding bearing into it, and the lubricating oil passes in an improved manner in the sliding bearing gap between the outer surface of the outer shaft and the inner surface of the cam member.

The sliding bearing gap is such that the cam member on the outer surface of the outer shaft can perform a movement in the lower micrometer range by the diameter of the outer shaft is slightly smaller than the diameter of the cam bore in the cam member. The interaction of the cam member with a tapping element for valve actuation produces a periodically changing application of force to the cam element, whereby a constant lifting and lowering of the inner surface of the cam bore on the outer surface of the outer shaft is produced. As a result, the micro gap prevailing in the sliding bearing gap is periodically increased and decreased, whereby a pumping action is generated. It has been found that in particular in operative connection with a Ölleitnut, which is introduced in the outer surface of the outer shaft, a particularly favored introduction of lubricating oil can be generated in the plain bearing gap by this pumping action. As a result, even under extreme operating conditions, but especially even with a very slow rotation of the camshaft, the pumping action in interaction with the Ölleitnut invention ensures a permanent lubricating oil supply of the sliding bearing gap, and a surface wear of the outer surface of the outer shaft and / or the inner surface in the cam bore the cam element is effectively avoided.

According to a possible advantageous embodiment for forming the Ölleitnuten invention in the outer surface of the outer shaft, the Ölleitnuten extend in the extension direction of the camshaft. This results in a particularly simple technical production of Ölleitnuten, for example by means of a uniaxial milling. The Ölleitnut can run straight in the outer surface of the outer shaft, wherein for each setting point on which a cam member is disposed on the outer shaft, one or more Ölleitnuten can be introduced in the direction of extension of the camshaft. The extension direction of the Ölleitnuten runs parallel to the axis of rotation of the adjustable camshaft.

According to a further advantageous embodiment, the at least one Ölleitnut with an axial extension component and with a circumferentially extending component in the outer surface of the outer shaft spiral. Due to the helical course of the Ölleitnut the entry of lubricating oil over the free groove portion of the Ölleitnut is favored, which protrudes from the sliding bearing gap between the outer shaft and the cam member, wherein the promotion of the Schmieröleintritts is generated in the Ölleitnut by the rotation of the camshaft. Due to the rotation of the camshaft, one runs on the outer surface of the outer shaft adhering amount of oil approximately in the circumferential direction over the outer surface along, and meets the lubricating oil, for example in droplet form or as a migrating oil film on the free groove portion, the shrinkage of the lubricating oil is promoted in the oil groove by the spiral course of the Ölleitnut. Consequently, a blade effect is generated by the spiral shape, so that a transport effect of the lubricating oil in the Ölleitnut by the twist, which results from the spiraling course in the Ölleitnut favored.

With particular advantage it can be provided that at a setting point of a cam element on the outer shaft, a first Ölleitnut is formed with a first spiral rotation direction and at least a second Ölleitnut with one of the first Spiralrehrichtung oppositely formed second spiral rotation direction. By oppositely spiraling Ölleitnuten in the outer surface of the outer shaft has the advantage that in a first Ölleitnut via a free groove portion on a first side of the cam element lubricating oil can get into the Ölleitnut, and a further amount of oil can over another free groove portion on the opposite Side of the cam element equally enter the other Ölleitnut. The oppositely extending Ölleitnuten are consequently also flowed through in the opposite direction with lubricating oil.

With further advantage, the at least one Ölleitnut be led out on both sides of the cam member from the sliding bearing gap with a respective free groove portion. Thus, the Ölleitnut not only forms a lubricating oil reservoir formed in the sliding bearing gap, but the Ölleitnut can be flowed through with lubricating oil by the lubricating oil on a first side of the cam member via a first free groove portion enters the Ölleitnut and on the opposite side of the cam member via another free Nutabschnitt the Ölleitnut can leave again. Parts of the oil flowing through the Ölleitnut lubricating oil can get in particular supported by the pumping action in the sliding bearing gap. As a result, a permanent replacement of the lubricating oil in the sliding bearing gap is achieved with particular advantage.

For the rotationally fixed connection of the cam element with the inner shaft, a bolt may be provided which extends transversely through the inner shaft and through at least one bolt hole introduced in the outer shaft. In this case, the bolt can be seated with at least one of its ends in the cam member, whereby the rotationally fixed connection between the inner shaft and the cam member is generated. Also, the at least one oil groove may be spaced from the arrangement of the bolt hole in the outer shaft. This avoids that lubricating oil can escape from the Ölleitnut in the bolt opening, also the advantage can be achieved that through the bolt hole also lubricating oil can get into the sliding bearing gap, so supplied by the Ölleitnuten more areas of the sliding bearing gap spaced from the bolt opening additionally with lubricating oil can be.

In particular, critical, i. Highly loaded areas can be supplied by the Ölleitnuten without crossing the at least one bolt hole in the outer shaft. Thus, the lubricating oil can not drain through the openings for the bolts.

According to an advantageous embodiment of the adjustable camshaft, the cam elements may comprise at least one cam collar, wherein the axial width of the sliding bearing gap is determined by the width of the cam collar. The sliding bearing gap thus extends under the actual cam element and under the region of the cam collar, so that the oil guide grooves can also have a corresponding length over the actual cam element and the cam collar. The bolt for connecting the cam member to the inner shaft can thereby be seated in the cam collar, so that the cam member is rotationally connected via the cam collar and the bolt with the inner shaft.

With further advantage, the Ölleitnut have a variable over the length of cross-section, in particular such that the Ölleitnut starting tapers from the free groove portion in the sliding bearing gap, for example. Due to larger dimensions in the region of the free groove portion of the entry of lubricating oil is favored in the groove portion, wherein by the inward in the Sliding bearing gap extending into the region of the Ölleitnut the taper of the Ölleitnut favors the escape of the lubricating oil from the Ölleitnut in the sliding bearing gap.

According to a further advantageous measure for improving the lubricating oil supply of the sliding bearing gap between the outer surface of the outer shaft and the inner surface in the cam bore can be provided that on the outer surface and / or on the inner surface, a surface structuring is provided, which may in particular be such that the Load capacity of a lubricant film forming between the outer surface of the outer shaft and the inner surface in the cam bore is improved. For example, the surface structuring may be generated by a laser beam machining method, a honing method, an electron beam method or by etching methods in the outer surface of the outer shaft and / or in the inner surface in the cam hole. The surface structuring may include grooves or grooves in the surface, which are formed with respect to the longitudinal extent of the camshaft, for example, axially, circumferentially, spirally or mesh-like.

Improving the load-bearing capacity of a lubricating film formed between the surfaces is achieved by the surface structuring providing micro-lubricating pockets into which the lubricating oil enters and provides a small amount of lubricating oil for passage into the journal bearing gap. An outline of the lubricating film to form a mixed friction is thereby effectively delayed. For example, the inner surface in the cam bore comprise a Kreuzhonschliff, as this is also known from the cylinder bore of a reciprocating engine. The Kreuzhonschliff can be applied in the same way on the outer surface of the outer shaft, so that a net-like surface structuring arises.

The surface of the camshaft may also be hardened so that the tips of the surface structure in contact with the cam elements are not worn. Furthermore, so the shrinkage of the cam elements on the Outer shaft in the entire setting area or by edge support effects avoided or reduced.

PREFERRED EMBODIMENTS OF THE INVENTION

Fig. 1

eine ausschnittsweise Ansicht einer Außenwelle einer verstellbaren Nockenwelle mit einer Ölleitnut, die in der Außenoberfläche eingebracht ist,

Fig. 2

eine ausschnittsweise Ansicht einer verstellbaren Nockenwelle mit einem Nockenelement und mit einer Ölleitnut im Bereich der Setzstelle des Nockenelementes,

Fig. 3

eine ausschnittsweise Ansicht einer Außenwelle mit zwei in der Außenoberfläche eingebrachten, entgegengesetzt verlaufenden Ölleitnuten,

Fig. 4

eine ausschnittsweise dargestellte Nockenwelle mit einem Nockenelement, wobei im Bereich der Setzstelle des Nockenelementes zwei Ölleitnuten gemäß Figur 3 in der Außenoberfläche der Außenwelle eingebracht sind,

Fig. 5

ein perspektivischer Abschnitt einer Außenwelle mit zwei Ölleitnuten, die einen geraden Längsverlauf in Erstreckungsrichtung der Nockenwelle aufweisen,

Fig. 6

eine perspektivische Ansicht eines Ausschnittes der Nockenwelle mit einer Außenwelle, einer Innenwelle und einem Nockenelement, wobei in der Außenoberfläche der Außenwelle zwei Ölleitnuten mit einer längs verlaufenden Erstreckungsrichtung,

Fig. 7

eine Querschnittsansicht der Außenoberfläche der Außenwelle mit einer Oberflächenstrukturierung,

Fig. 8

eine perspektivische Ansicht der Außenoberfläche der Außenwelle mit einer Oberflächenstrukturierung,

Fig. 9

eine weitere Querschnittsansicht der Außenoberfläche der Außenwelle mit einer Oberflächenstrukturierung,

Fig. 10

eine Draufsicht auf die Außenoberfläche der Außenwelle mit einer Oberflächenstrukturierung und

Fig. 10a

die Querschnittsansicht der Außenoberfläche der Außenwelle mit der Oberflächenstrukturierung gemäß Figur 10.

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

Fig. 1

a partial view of an outer shaft of an adjustable camshaft with a Ölleitnut, which is introduced in the outer surface,

Fig. 2

1 is a partial view of an adjustable camshaft with a cam element and with a Ölleitnut in the region of the setting point of the cam element,

Fig. 3

a fragmentary view of an outer shaft with two introduced in the outer surface, oppositely extending Ölleitnuten,

Fig. 4

a partially illustrated camshaft with a cam member, wherein in the region of the setting point of the cam member two Ölleitnuten according to FIG. 3 are introduced in the outer surface of the outer shaft,

Fig. 5

a perspective section of an outer shaft with two Ölleitnuten having a straight longitudinal direction in the direction of extension of the camshaft,

Fig. 6

a perspective view of a section of the camshaft with an outer shaft, an inner shaft and a cam member, wherein in the outer surface of the outer shaft two Ölleitnuten with a longitudinal extension direction,

Fig. 7

a cross-sectional view of the outer surface of the outer shaft with a surface structuring,

Fig. 8

a perspective view of the outer surface of the outer shaft with a surface structuring,

Fig. 9

a further cross-sectional view of the outer surface of the outer shaft with a surface structuring,

Fig. 10

a plan view of the outer surface of the outer shaft with a surface structuring and

Fig. 10a

the cross-sectional view of the outer surface of the outer shaft with the surface structuring according to FIG. 10 ,

The Figures 1 and 2 show a first embodiment of an adjustable camshaft 1, wherein in FIG. 1 a section of an outer shaft 10 is shown, and in FIG. 2 is a section of a camshaft 1 with an outer shaft 10 according to FIG. 1 shown. The outer shaft 10 is formed as a hollow shaft, and an inner shaft 11 extends through the outer shaft 10 and is independent of the outer shaft 10 about a common camshaft axis 22 rotatable. In this case, the inner shaft 11 is rotatably mounted in the outer shaft 10. On the outer shaft 10, a cam member 23 is rigidly received, and the cam member 23 may for example be welded to the outer shaft 10 or fixed to a diameter expansion by means of a press fit. Thus, the cam member 23 rotates with the outer shaft 10 in phase.

Another cam member 12 is rotatably received in the region of a setting point 16 on the outer surface 13 of the outer shaft 10 to form a sliding bearing gap. The cam member 12 has a cam collar 12a, and the cam member 12 is rotationally connected by means of a bolt 17 with the inner shaft 11. Thus, a rotation of the inner shaft 11 relative to the outer shaft 10 about the camshaft axis 22 despite passing through the outer shaft 10 therethrough guided bolt 17 remains possible, 10 bolt holes 18 are provided in the outer shaft, which extend over an angular range in the circumferential direction, so that the cam member 12 by a rotation of the inner shaft 11 relative to the phase position of the cam member 23 which is rigidly mounted on the outer shaft 10, can be twisted. As a result, valve control times of an internal combustion engine can be adjusted separately from one another, for example, control times for intake valves and exhaust valves.

In the outer shaft 10, a Ölleitnut 14 is shown, which has a spiral shape with an axial extension component in the direction of the camshaft axis 22 and an extension component in the circumferential direction. The width of the setting point 16 in the direction of the camshaft axis 22 is indicated by dashed lines, and the width of the setting point 16 corresponds to the width of the sliding bearing gap between the outer surface 13 of the outer shaft 10 and the cam member 12. It is shown that the Ölleitnut 14 via extends the entire width of the setter 16 away, and with free groove portions 15 extends beyond this, as in FIG. 2 shown. This ensures that oil adhering to the outer surface 13 of the outer shaft 10 can enter the Ölleitnut 14 via the free groove portions 15, wherein a free groove portion 15 for entry and another free groove portion 15 for the outlet of the lubricating oil in and out of Ölleitnut 14 can serve, which depends on the direction of rotation of the camshaft 1.

In the FIGS. 3 and 4 is a further embodiment of a camshaft 1 is shown. FIG. 3 shows a portion of an outer shaft 10 with two Ölleitnuten 14, wherein the outer shaft 10 with the Ölleitnuten 14 in the partial view of the camshaft 1 according to FIG FIG. 4 is also shown. The introduced into the outer surface 13 of the outer shaft 10 Ölleitnuten 14 have a mutually opposite spiral shape, and free groove portions 15 extend laterally beyond the side portion of the cam member 12 on the outer shaft 10. By rotation of the camshaft 1, lubricating oil can enter both into the first oil guide groove 14 and into the second oil guide groove 14 via the free groove sections 15, wherein the entry into those free groove sections 15 takes place with respect to the spiral rotation direction in the direction of rotation of the camshaft 1 about the camshaft axis 22. As a result, a blade effect is utilized, and lubricating oil can pass through the Ölleitnuten 14. In this case, the lubricating oil from the Ölleitnut 14 reach into the sliding bearing gap over the width of the setting point 16 in order to supply the sliding bearing between the cam member 12 and outer shaft 10 with lubricating oil.

The FIGS. 5 and 6 show in a respective perspective view of another embodiment of Ölleitnuten 14 in the outer surface 13 of the outer shaft 10, and the Ölleitnuten 14 extend in the longitudinal direction of the camshaft 1 parallel to the camshaft axis 22. In FIG. 5 It is shown that the introduced in the outer shaft 10 bolt opening 18 is arranged spaced from the arrangement of the Ölleitnuten 14, so that no lubricating oil can enter directly from the bolt hole 18 in the Ölleitnut 14, also no lubricating oil can pass directly from the Ölleitnut 14 in the bolt hole 18 , The ends of the Ölleitnuten 14 open into free groove portions 15 which run out laterally from the sliding bearing gap between the cam member 12 and the outer shaft 10 to cause lubricating oil can get over the free groove portions 15 in the Ölleitnuten 14.

The illustrations show a camshaft 1, as it can be received in the cylinder head of an internal combustion engine via plain bearings. The plain bearings, not shown, can accommodate the camshaft 1 via the outer shaft 10, wherein the plain bearings can be supplied via oil passages in the stationary bearing shells with lubricating oil. The lubricating oil can emerge laterally at the sliding bearing points, and it can be provided within the meaning of the present invention with further advantage, the sliding bearings relative to the inner shaft 11 rotatably connected cam elements 12 adjacent to arrange, thereby causing the area of the outer surface 13 of the Outer shaft 10, to which the free groove portions 15 protrude, is afflicted with a larger amount of lubricating oil. As a result, lubricating oil from the sliding bearings for receiving the camshaft 1 in the cylinder head can be improved by moving the lubricating oil on the outer surface 13 of the outer shaft 10 via the free groove sections 15 into the oil guide grooves 14.

The FIGS. 7 and 8 show in a cross-sectional view ( FIG. 7 ) and in a schematic perspective view ( FIG. 8 The surface structuring 19 may be introduced into the outer surface 13 of the outer shaft 10, but also into the inner surface of the cam bore, for example, by a laser beam machining method, a honing method, an electron beam method, or by etching methods Microcavities 24 are generated. By creating microcavities 24 in the outer surface 13, the adhesion of the lubricating oil to the outer surface 13 is improved, and the lubricating film between the outer surface 13 of the outer shaft 10 and the cam hole in the cam member 12 is stabilized.

FIG. 9 shows further forms of a surface structure 20 in the form of grooves, which are shown in cross-section of the outer shaft 10. The grooves 20 can be introduced, for example, by a machining process in the surface, for example by a honing process.

FIG. 10 shows by way of example schematically the outer surface 13 with introduced into this surface structures 21, which in the FIG. 10a are shown according to the section line I to I. The surface structuring 21 has a semicircular cavity and extends oblong over portions of the outer surface 13. Such surface structuring 21 can also be introduced into the outer surface 13 via laser beam processing methods, honing methods, electron beam methods or etching methods and also serve for the formation of micro-lubricating oil reservoirs. to stock a lot of lubricating oil for lubrication of the sliding bearing gap. In a manner not shown in more detail, the surface structures 19 may intersect the oil guide grooves 14 in the outer surface 13 or be arranged adjacent thereto, so that lubricating oil can pass from the Ölleitnuten 14 in the surface structures 21.

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

LIST OF REFERENCE NUMBERS

1

camshaft

10

outer shaft

11

inner shaft

12

cam member

12a

cam collar

13

outer surface

14

Ölleitnut

15

free groove section

16

setting point

17

bolt

18

bolt hole

19

surface structuring

20

surface structuring

21

surface structuring

22

camshaft axis

23

cam member

24

microcavities

Claims (10)

1. Adjustable camshaft (1) for the valve gear of an internal combustion engine, having outer shaft (10) and an inner shaft (11) running concentrically in the outer shaft (10) and rotatably mounted therein, wherein at least one cam element (12) is rotatably supported on the outer surface (13) of the outer shaft (10), forming a slide bearing gap, and wherein the cam element (12) is connected to the inner shaft (11) in a rotationally fixed manner,
   characterized in that at least one oil channeling groove (14) is made in the outer surface (13) of the outer shaft (10) in a position and with an axial length such that the oil channeling groove (14) is formed at least over the axial width of the slide bearing gap and is led out of the slide bearing gap with an exposed groove portion (15) on at least one side of the cam element (12).
2. Adjustable camshaft (1) according to Claim 1, characterized in that the oil channeling groove (14) runs in the direction in which the camshaft (1) extends and/or that the oil channeling groove (14) having an axial extent component and an extent component running in a circumferential direction runs helically in the outer surface (13) of the outer shaft (10).
3. Adjustable camshaft (1) according to Claim 1 or 2, characterized in that a first oil channeling groove (14) having a first direction of helical rotation and at least a second oil channeling groove (14) having a second direction of helical rotation opposed to the first direction of helical rotation are formed at a seating point (16) of a cam element (12) on the outer shaft (10).
4. Adjustable camshaft (1) according to one of Claims 1 to 3, characterized in that the oil channeling groove (14) is led out the slide bearing gap with an exposed groove portion (15) on each of the two sides of the cam element (12).
5. Adjustable camshaft (1) according to one of the preceding claims, characterized in that a bolt (17), which extends transversely through the inner shaft (11) and through at least one bolt aperture (18) made in the outer shaft (10) and is seated with at least one end in the cam element (12), is provided for rotationally fixed connection of the cam element (12) to the inner shaft (11), wherein at least the one oil channeling groove (14) runs at a distance from the arrangement of the bolt aperture (18) in the outer shaft (10).
6. Adjustable camshaft (1) according to one of the preceding claims, characterized in that the cam element (12) comprises a cam collar (12a), wherein the axial width of the slide bearing gap is also determined by the width of the cam collar (12a).
7. Adjustable camshaft (1) according to one of the preceding claims, characterized in that the oil channeling groove (14) has a cross section varying over the length, especially in such a way that the oil channeling groove (14) tapers from the exposed groove portion (15) into the slide bearing gap.
8. Adjustable camshaft (1) according to one of the preceding claims, characterized in that a surface texturing (19, 20, 21), which in particular is such that the load-carrying capacity of a lubricating film forming between the outer surface (13) of the outer shaft (10) and the inner surface in the cam bore is improved, is provided on the outer surface (13) of the outer shaft (10) and/or on the inner surface in the cam bore.
9. Adjustable camshaft (1) according to Claim 8, characterized in that the surface texturing (19, 20, 21) is produced in the outer surface (13) of the outer shaft (10) and/or on the inner surface in the cam bore by a laser beam machining process, a honing process, an electron beam process or by an etching process.
10. Adjustable camshaft (1) according to Claim 8 or 9, characterized in that the surface texturing (19, 20, 21) is formed running axially, circumferentially, spirally or in reticulated form in relation to the longitudinal extent of the camshaft (1).

Images