U.S. patent application number 12/124533 was filed with the patent office on 2008-11-27 for cam shaft.
Invention is credited to Thomas Flender, Michael Kreisig, Falk Schneider.
Application Number | 20080289592 12/124533 |
Document ID | / |
Family ID | 39712327 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080289592 |
Kind Code |
A1 |
Flender; Thomas ; et
al. |
November 27, 2008 |
CAM SHAFT
Abstract
The instant invention relates to a cam shaft (1) for internal
combustion engines of motor vehicles, which is supported on a
cylinder head housing (15) via at least one roller bearing (2),
wherein provision is made for at least one thrust bearing (3),
which supports the cam shaft (1) in axial direction (4) and which
is embodied as ball or also as roller bearing (2).
Inventors: |
Flender; Thomas; (Rutesheim,
DE) ; Kreisig; Michael; (Stuttgart, DE) ;
Schneider; Falk; (Korntal-Munchingen, DE) |
Correspondence
Address: |
RADER, FISHMAN & GRAUER PLLC
39533 WOODWARD AVENUE, SUITE 140
BLOOMFIELD HILLS
MI
48304-0610
US
|
Family ID: |
39712327 |
Appl. No.: |
12/124533 |
Filed: |
May 21, 2008 |
Current U.S.
Class: |
123/90.6 ;
384/490; 384/609 |
Current CPC
Class: |
F01L 2001/0476 20130101;
F16C 35/077 20130101; Y10T 74/2101 20150115; Y10T 29/49865
20150115; Y10T 29/49696 20150115; F01L 1/047 20130101; Y10T
29/49293 20150115; F16C 2360/18 20130101 |
Class at
Publication: |
123/90.6 ;
384/609; 384/490 |
International
Class: |
F01L 1/047 20060101
F01L001/047; F16C 19/10 20060101 F16C019/10; F16C 19/04 20060101
F16C019/04 |
Foreign Application Data
Date |
Code |
Application Number |
May 22, 2007 |
DE |
10 2007 024 092.0 |
Claims
1-12. (canceled)
13. A cam shaft assembly comprising: a cam shaft; at least one
roller bearing for supporting the cam shaft in a first direction;
and at least one thrust bearing for supporting the camshaft in a
second direction, the thrust bearing including at least one of a
ball bearing and a roller bearing.
14. The cam shaft assembly of claim 13, wherein the second
direction extends generally parallel to a longitudinal axis of the
cam shaft.
15. The cam shaft assembly of claim 13, further comprising: a
bearing ring that engages the thrust bearing, the bearing ring
including a circumferential groove; and a connecting element
attached to a cylinder head of an internal combustion engine;
wherein the circumferential groove of the bearing ring is
engageable with the connecting element.
16. The cam shaft assembly of claim 15, wherein the connecting
element is at least one of a stud screw and a pin.
17. The cam shaft assembly of claim 13, wherein the at least one
roller bearing comprises at least one roller that directly engages
the cam shaft.
18. The cam shaft assembly of claim 17, wherein a region of the cam
shaft that the roller directly engages is hardened.
19. The cam shaft assembly of claim 13, further comprising a
bushing directly engaging the cam shaft, wherein the at least one
roller bearing comprises at least one roller directly engaging the
bushing.
20. The cam shaft assembly of claim 19, wherein the bushing is
hardened.
21. The cam shaft assembly of claim 19, wherein the bushing is
joined to the cam shaft by at least one of adhesion, an
interference fit, or welding.
22. The cam shaft assembly of claim 13, further comprising at least
two cams attached to the cam shaft, wherein the at least one thrust
bearing is arranged between and engages the at least two cams.
23. The cam shaft assembly of claim 13, further comprising: at
least two cams attached to the cam shaft; and at least two spacers
disposed between and engaging the at least two cams, wherein the at
least one thrust bearing is arranged between and engages the at
least two spacers.
24. The cam shaft assembly of claim 13, further comprising at least
two cams, each cam including a collar, wherein the at least one
thrust bearing is arranged between the two cams and engages the
collar of the at least two cams.
25. The cam shaft assembly of claim 24, wherein the collar is
integrally formed with the cam.
26. The cam shaft assembly of claim 24, wherein the collar is
attached to the cam by at least one of soldering, welding, and
adhering.
27. The cam shaft assembly of claim 13, further comprising at least
one cam attached to the cam shaft by at least one of thermal
joining, an interference fit, and adhesion.
28. The cam shaft assembly of claim 13, wherein the at least one
roller bearing is attached to the cam shaft by at least one of
thermal joining, an interference fit, and adhesion.
29. The cam shaft assembly of claim 13, wherein the at least one
thrust bearing is attached to the cam shaft by at least one of
thermal joining, an interference fit, and adhesion
30. The cam shaft assembly of claim 13, wherein the camshaft is
configured to be supported in an internal combustion engine in at
least one of a tunnel bearing manner and an open bearing
manner.
31. The cam shaft assembly of claim 13, wherein the at least one
roller bearing comprises a closed roller bearing attached to the
cam shaft during assembly of the cam shaft assembly.
Description
[0001] The invention relates to a cam shaft for internal combustion
engines of motor vehicles, which is supported on a cylinder head
housing via at least one roller bearing.
[0002] Typically, cam shafts are supported in cam shaft bearings,
which are normally manufactured as bushings made from materials,
such as aluminum alloys, for example, or as half bearings made of
materials on the basis of copper alloys. However, other types of
bearings, such as a roller bearing, for example, are also known
from the state of the art. A thrust bearing function for the cam
shaft is normally taken over via a so-called washer disk, which is
also known as "trust plate". However, as compared to other bearing
devices, such washer disks have a considerably shorter life
expectancy so that they must typically be replaced on a rotational
basis.
[0003] The invention deals with the problem of specifying an
improved embodiment for a cam shaft, where in particular a thrust
bearing is improved.
[0004] This problem is solved according to the invention by means
of the object of independent claim 1. Advantageous embodiments are
the object of the dependent claims.
[0005] The invention is based on the general idea of embodying a
thrust bearing for a cam shaft for internal combustion engines of
motor vehicles as ball bearings or as roller bearings and to thus
on the one hand considerably extend the life expectancy of the
thrust bearing and to thus on the other hand improve the thrust
bearing as a whole. At the same time, the cam shaft supported in
axial direction in such a manner can be supported on a cylinder
head via further bearing devices, which are embodied as roller
bearings, whereby the entire bearing of the cam shaft can be
improved as compared to bearings known from the state of the
art.
[0006] In an advantageous development of the solution according to
the invention, at least one thrust bearing, which is embodied as a
roller bearing, encompasses a roller, which runs directly on the
cam shaft, wherein a region of the cam shaft, which comes into
contact with the roller, is hardened. Through this, a particularly
effective bearing of the cam shaft can be attained, wherein a
hardening of the region, which comes into contact with the roller,
can be hardened via an inductive and thus highly pinpointed
heating, for example, as well as via a subsequent rapid cooling.
The hardening thereby increases the wear resistance of the cam
shaft, whereby the life expectancy thereof can be extended.
[0007] As an alternative thereto, provision can be made in a
further embodiment in the region of the thrust bearing, which is
embodied as roller bearing, for a bushing, which is arranged
directly on the cam shaft and on which the roller of the roller
bearing rolls. Such a bushing can also be hardened, for example,
and can thus encompass a considerably improved wear resistance as
compared to an unhardened material. At the same time, such a
bushing can be chosen in such a manner with reference to its
material characteristics that particularly good bearing
characteristics can be attained.
[0008] Advantageously, the cams and/or the roller bearing and/or
the at least one thrust bearing are connected to the cam shaft by
means of a thermal joining process, by means of an interference fit
assembly or by means of adhesion, wherein only finished cams and/or
roller bearings and/or thrust bearings are used for joining with
the cam shaft. Due to the finished components, a machine finishing
of the cams and of the cam shaft, respectively, is not necessary
after connecting the afore-mentioned components to the cam shaft,
whereby it can be prevented that swarf, for example, penetrates
into the roller bearings and negatively impacts them during the
future operation.
[0009] Advantageously, the at least one thrust bearing, which is
embodied as a ball or roller bearing, is arranged between two cams
of the cam shaft and is directly supported thereon. The thrust
bearing is thus fixed between the two cams with reference to its
axial direction, without requiring further fixing elements for this
purpose, the production of which is extensive, for example. It is
also possible for the at least one thrust bearing, which is
embodied as a ball or roller bearing, to be indirectly supported on
the two cams via two spacer elements, in particular via two spacer
bushings. Such spacer bushings provide the large advantage that the
thrust bearing must not necessarily be arranged in the region
directly next to the cams, but that, depending on the axial length
of the chosen bushing, it can be arranged in a location, which is
advantageous for the installation of the thrust bearing. In the
alternative, these spacer bushings can also be fixedly connected to
the adjacent cams, which entails a shortened assembly time for the
cam shaft.
[0010] Advantageous exemplary embodiments, which will be defined
below, are illustrated in the drawings.
[0011] In each case in a schematic view,
[0012] FIG. 1 shows a cam shaft according to the invention,
[0013] FIG. 2a to d show different embodiments of thrust bearings,
which are embodied as ball bearings,
[0014] FIG. 3 shows a possible embodiment of thrust bearings of a
cam shaft when assembled,
[0015] FIG. 4 shows a sectional view through a cam shaft comprising
a thrust bearing according to the invention,
[0016] FIG. 5 shows a detailed view of a thrust bearing according
to the invention,
[0017] FIG. 6 shows a view onto a cam shaft according to the
invention,
[0018] FIG. 7 shows a view onto a cam shaft according to the
invention,
[0019] FIG. 8 shows a radial bearing embodied as a roller
bearing,
[0020] FIG. 9 shows an illustration as in FIG. 8, however in a
different embodiment,
[0021] FIG. 10 shows a thrust bearing (held in position by means of
frictional connection) embodied as a roller bearing,
[0022] FIG. 11 to 13 show a sectional view through a cam shaft
according to the invention in a respective other embodiment.
[0023] According to FIG. 1, a cam shaft 1 for internal combustion
engines of motor vehicles according to the invention encompasses at
least one roller bearing 2, via which the cam shaft 1 is supported
on a non-illustrated cylinder head housing 15. Furthermore, the cam
shaft 1 encompasses at least one thrust bearing 3, which supports
the cam shaft 1 in axial direction 4 and which is embodied as a
ball or as a roller bearing. The cam shaft 1 according to FIG. 1 is
a cam shaft for engines comprising a so-called "tunnel bearing".
That is to say, the cam shaft 1 is inserted into the cam shaft
bearing of the crank case in the direction of the cam shaft axis
4.
[0024] According to FIG. 2a to 2d, different embodiments of the
thrust bearings 3, which are embodied as ball bearings, are
illustrated thereby. FIG. 2a shows a thrust bearing 3 embodied as a
ball bearing, which is arranged in axial direction 4 between two
cams 5 and 5' and which is indirectly supported on the cams 5, 5'
via two spacer bushings 6, 6'. The spacer bushings 6, 6' can
thereby generally also be referred to as spacer elements.
[0025] Contrary thereto, FIG. 2b shows a thrust bearing 3, which is
also arranged between two cams 5 and 5', which, however, is
directly supported on the adjacent cams 5, 5', namely in each case
via a collar 7, 7', which is a component of the cams 5, 5'. The
collar 7, 7' in FIG. 2b thereby performs the task of the spacer
bushings 6, 6' in FIG. 2a.
[0026] A part 8 (bushing) of the thrust bearing 3 on the cam shaft
side in axial direction is embodied in FIG. 2c to be so wide that
the thrust bearing 3 can also be directly supported on the adjacent
cams 5 and 5'.
[0027] FIG. 2d shows an embodiment, where the thrust bearing 3,
which is embodied as a ball bearing, is also located between two
cams 5 and 5' of the cam shaft 1 and is supported on a collar 7a
and 7b of the cams 5 and 5', wherein the respective collar 7a and
7b is not a component of the cam 5 and 5', but is soldered, welded
or adhered thereto.
[0028] FIG. 4 illustrates a cam shaft 1 in a sectional view,
wherein the roller bearings 2 as well as the at least one thrust
bearing 3 can be identified well.
[0029] In the thrust bearing 3 according to FIG. 1 to 6, the thrust
bearing 3 is embodied as a ball bearing and encompasses a bearing
ring 9, at the outer jacket surface 10 of which provision is made
for a revolving groove 11, which meshes with a connecting element
12, in particular a stud screw or a pin, at the side of the
cylinder head and thus fixes the cam shaft 1 in axial direction
4.
[0030] This can be identified particularly well in FIG. 5, wherein
the connecting element 12 is embodied herein as a stud screw and
meshes with the groove 11 of the bearing ring 9. A particularly
clear illustration of the groove 11, which is arranged on the
bearing ring 9, is shown in FIG. 6.
[0031] Contrary thereto, the cam shaft 1 according to FIG. 7 does
not encompass a thrust bearing 3, which is embodied as a ball
bearing, but a thrust bearing according to FIG. 8 to 10, which is
embodied as a roller bearing.
[0032] According to FIG. 8, the at least one radial bearing, which
is embodied as a roller bearing, encompasses a roller 13, which
runs directly on the cam shaft 1, wherein the region 14 of the cam
shaft 1, which comes into contact with the roller 13, is hardened.
Contrary thereto, provision is made with the thrust bearing 3
according to FIG. 9 in the region 14 of the thrust bearing 3, which
is embodied as roller bearing, for a bushing 8, which is arranged
directly on the cam shaft 1, on which the roller 13 of the roller
bearing, that is to say the radial bearing, rolls. It goes without
saying that the bushing 8 can also be made of a particularly
wear-resistant material or can be subjected to an aging process,
which increases the wear-resistance.
[0033] FIG. 11 to 13 once again show the thrust bearings 3 from
FIG. 2b to 2d, which are embodied as ball bearings, in their
post-assembly position.
[0034] The cam shafts 1 according to FIG. 7 to 11 are cam shafts 1
for engines comprising a so-called "open bearing". That is to say,
the cam shaft 1 is held in position in the cam shaft bearing of the
cylinder head 15 parallel to the cam shaft axis 4 and by means of
bearing caps.
[0035] As a matter of principle, the cams 5 and/or the roller
bearing 2 and/or the at least one thrust bearing 3 in the cam shaft
1 according to the invention are connected to the cam shaft 1 by
means of a thermal joining process, by means of an interference fit
assembly or by means of adhesion. It is thereby particularly
advantageous that only finished cams 5 and/or roller bearings 2
and/or thrust bearings 3 are used for joining with the cam shaft 1
so that a finishing of the cam shaft 1 is no longer necessary after
the application of the afore-mentioned components and that swarf
and processing dust, respectively, can thus be prevented from
reaching into the bearings and thus from damaging them in the long
run.
[0036] The cam shaft 1 according to the invention makes it possible
to replace a currently conventional washer disk, which is required
for the thrust bearing of the cam shaft 1, with the thrust bearing
3 according to the invention, which, on the one hand, encompasses a
considerably higher life expectancy and which, on the other, helps
to reduce maintenance costs in particular.
[0037] In a particularly preferred method for producing the cam
shaft 1, closed roller bearings 2 are applied to said cam shaft 1
during the cam shaft assembly.
[0038] Either individually as well combined with one another in any
manner, all of the features described in the description and in the
following claims can be substantial for the invention.
* * * * *