U.S. patent application number 14/434644 was filed with the patent office on 2015-10-15 for rotor of a camshaft adjuster, camshaft adjuster with such a rotor, and method for producing a rotor.
The applicant listed for this patent is SCHAEFFLER TECHNOLOGIES AG & CO. KG. Invention is credited to Mario Arnold.
Application Number | 20150292366 14/434644 |
Document ID | / |
Family ID | 49117606 |
Filed Date | 2015-10-15 |
United States Patent
Application |
20150292366 |
Kind Code |
A1 |
Arnold; Mario |
October 15, 2015 |
ROTOR OF A CAMSHAFT ADJUSTER, CAMSHAFT ADJUSTER WITH SUCH A ROTOR,
AND METHOD FOR PRODUCING A ROTOR
Abstract
A camshaft adjuster (1) with a rotor (2) and a stator (3). The
rotor (2) has a connecting region (7) for fixing a camshaft in a
non-rotatable manner, and the rotor (2) is at least partly made of
a sinter material and has an oxide layer (11) which is produced by
supplying steam during the production process.--A method for
producing a rotor (2) for a camshaft adjuster (1), said rotor (2)
being at least partly made of a sinter material, wherein at least
one sinter material application area (7) which is provided for
applying a camshaft is supplied with steam.
Inventors: |
Arnold; Mario; (Aurachtal,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCHAEFFLER TECHNOLOGIES AG & CO. KG |
Herzogenaurach |
|
DE |
|
|
Family ID: |
49117606 |
Appl. No.: |
14/434644 |
Filed: |
July 24, 2013 |
PCT Filed: |
July 24, 2013 |
PCT NO: |
PCT/DE2013/200073 |
371 Date: |
April 9, 2015 |
Current U.S.
Class: |
123/90.17 ;
419/27 |
Current CPC
Class: |
B22F 2998/10 20130101;
F01L 1/344 20130101; B22F 2201/05 20130101; F01L 1/3442 20130101;
B22F 2999/00 20130101; B22F 5/10 20130101; B22F 2998/10 20130101;
B22F 3/10 20130101; B22F 3/26 20130101; B22F 3/24 20130101; B22F
5/00 20130101; B22F 2201/05 20130101; B22F 3/10 20130101; B22F 3/24
20130101; B22F 2999/00 20130101; B22F 3/24 20130101 |
International
Class: |
F01L 1/344 20060101
F01L001/344; B22F 3/10 20060101 B22F003/10; B22F 5/00 20060101
B22F005/00; B22F 3/26 20060101 B22F003/26 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 31, 2012 |
DE |
10 2012 219 949.7 |
Claims
1-10. (canceled)
11. A camshaft adjuster comprising: a rotor; and a stator; the
rotor having a connecting area for the rotationally fixed fastening
of a camshaft, the rotor being made of a sintered material at least
in some sections, the rotor having an oxide layer created by water
vapor application during production.
12. The camshaft adjuster as recited in claim 11 wherein the oxide
layer is a friction-increasing oxide layer present on the surface
of the connecting area.
13. The camshaft adjuster as recited in claim 11 wherein the oxide
layer is formed from a section of a front face of the rotor facing
the camshaft.
14. The camshaft adjuster as recited in claim 13 wherein the
section having the oxide layer is a surface of a bottom of a
central recess in the rotor running transversely to an axis of
rotation of the rotor.
15. The camshaft adjuster as recited in claim 14 wherein the
section having the oxide layer is the surface of the bottom of the
central recess in the rotor running orthogonally to the axis of
rotation of the rotor.
16. The camshaft adjuster as recited in claim 14 wherein the bottom
forms a stop for the camshaft acting in the longitudinal direction
of the rotor.
17. The camshaft adjuster as recited in claim 11 wherein the rotor
is strengthened by water vapor induction in at least some
areas.
18. The camshaft adjuster as recited in claim 11 wherein the rotor
is produced from a sintered material or is prepared for a screw
connection with the camshaft.
19. The camshaft adjuster as recited in claim 11 wherein the rotor
is produced from the sintered material, the sintered material being
metallic.
20. The camshaft adjuster as recited in claim 11 wherein the stator
has the oxide layer, the oxide layer being a friction-increasing
oxide layer on at least one or both front faces due to water vapor
application.
21. A method for producing a rotor for a camshaft adjuster, the
rotor being made of sintered material at least in some sections,
the method comprising treating with water vapor at least one use
area of the sintered material for use with a camshaft.
22. The method as recited in claim 21 wherein an oxide layer
created by the treating with water vapor is left on the surface of
the rotor, so that the oxide layer is connected to the camshaft in
a force-locking manner in the installed state of the rotor inside a
stator.
Description
[0001] The present invention relates to a camshaft adjuster having
a rotor and a stator, the rotor having a connecting area for
rotationally fixed attachment of a camshaft and the rotor being
made of a sintered material at least in sections.
[0002] The present invention also relates to a method for producing
a rotor for a camshaft adjuster.
BACKGROUND
[0003] Generic camshaft adjusters are known from the prior art,
e.g., from DE 100 44 423 A1, which describes a valve timing control
device for internal combustion engines. An internal combustion
engine having a timing chain is described there. A sprocket wheel
is thereby driven synchronously with the rotation of the engine. A
camshaft for actuation of the intake or exhaust valves is
described. The valve timing control device includes a first
rotational part, for example, a stator, on which the sprocket wheel
is formed in one piece, and a second rotational part such as a
rotor, which is capable of rotating relative to the first
rotational part and jointly with the camshaft, a plurality of
working fluid chambers bordered between two rotational parts and a
feed/discharge device for working fluid to and from the working
fluid chambers for inducing a relative rotation between the two
rotational parts. The sprocket wheel and at least one base part of
the first rotational part are formed from a porous metal part.
Working fluid supplied to the working fluid chambers may penetrate
through the base part into the sprocket wheel and induce adequate
lubrication of an engagement section between the sprocket wheel and
the timing chain. The porous metal part may be made of sintered
metal.
[0004] It is basically known that sintered materials such as
sintered iron may be aftertreated in particular to produce a
surface-hardened workpiece. Thus, DE 41 40 148 A1, for example,
describes a method for producing a workpiece made of sintered
material, in particular sintered iron, this being subjected to a
water vapor treatment at temperatures below 500.degree. C., in
particular at 430.degree. C. to 480.degree. C. and a water vapor
partial pressure of 20 mbar to 80 mbar, in particular 30 mbar to 50
mbar, as well as a subsequent surface hardening after sintering to
form an oxide layer on the surface. This yields workpieces, in
particular hollow wheels for starters, having a wear-resistant
surface and properties unchanged at the core due to the
hardening.
[0005] A similar prior art, namely EP 1 400 660 A1, also describes
an integrated annular gear and a housing for use in a variable
valve control mechanism. The integrated annular gear and the
housing include an annular gear component, which is designed
essentially with a circular shape and has teeth on its outer
circumference. Furthermore, it includes a housing component, which
is integrally shaped with the annular gear component as a sintered
body produced from a ferrous powdered material, so that it is
formed inside the annular gear component, which has receptacles
extending from an inner circumference of the housing component. The
complete surfaces of the annular gear component and of the housing
component are covered with a vapor-oxide layer formed by a
vaporization treatment and are also covered with a nitrite layer
formed by a gas-soft-nitriding treatment following the vaporization
treatment.
[0006] Rotors, which are part of a camshaft adjuster, are usually
rotationally fixedly attached to the camshaft in a force-locking
manner with the aid of a screw. Such rotors are often produced from
sintered material, Sint D11 being used as a standard.
[0007] A head screw or a hollow screw having a valve insert is
generally used as the means for fastening the camshaft to the
rotor.
[0008] Sintered steels containing carbon and copper and mixed with
MoS.sub.2 are used in most cases, and sintered material Sint D11 is
particularly popular. However, this material does not have optimal
properties for all applications and a low cost level at the same
time. Improvements are to be achieved in particular with regard to
strength, dimensional stability, processability and friction in the
future contact zone, while the cost level is to be reduced at the
same time.
[0009] The screw used for connecting the camshaft to the rotor is
also always subject to constant function and weight
optimization.
SUMMARY OF THE INVENTION
[0010] Due to the constant increase in the alternating torques to
be transferred during camshaft operation, the interface between the
camshaft and the camshaft adjuster should be adapted. In particular
the area on the rotor should be improved in this regard. The load
capacity of the fastening means and of the braced parts is to be
taken into account in this adaption.
[0011] It is an object of the present invention to provide a
camshaft adjuster due to the fact that the rotor has an oxide
layer, which is created by water vapor application during
production.
[0012] The alternating torque is transferred to the contact zones
of the screw connection via the applied screw pretension and as a
function of the coefficient of friction. With a steady increase in
the alternating torques, this means that the pretension and/or the
coefficient of friction also increase(s) for the screw
connection.
[0013] The screw connection is understood here to refer to the
connection of the camshaft to the rotor with the aid of a
screw.
[0014] The pretension may only be increased to the extent that the
tolerable stresses of the braced parts are reached. It is possible
to transfer an increased amount of stress and force due to the
water vapor application of the rotor.
[0015] On the one hand, weight-reducing measures necessitate a
reduction in the pretension, but this may be counteracted by the
water vapor application of a camshaft adjuster according to the
present invention. This utilizes the effective design option of
increasing the coefficient of friction while the total strength of
the rotor is increased at the same time.
[0016] It is possible to omit measures known previously, such as
the use of diamond disks or diamond coatings or stamping of a
laser-structured surface in the contact zone since these are very
cost-intensive.
[0017] The water vapor application of the rotor and the use of
pairings of materials between the rotor and the camshaft are more
effective and more economical. Thus not only is the coefficient of
friction increased by the water vapor application but also the
basic strength of the sintered material is increased. Therefore,
even a powder of a lower strength may be used, which is less
expensive and easier to shape.
[0018] Advantageous specific embodiments are derived from the
subclaims and explained in greater detail below.
[0019] It is advantageous if the sintered material is Sint D10 or
Sint D11. It is therefore possible to resort to particularly tried
and tested, inexpensive and/or durable materials.
[0020] It is also advantageous if the rotor has been treated with
water vapor in the area of the insertion grooves for vanes, which
greatly increases the strength in this area.
[0021] Furthermore, it is advantageous if the rotor is inserted
into a cover screw connection of the camshaft adjuster.
[0022] An advantageous exemplary embodiment is also characterized
in that the friction-increasing oxide layer is present on the
surface of the connecting area and preferably remains there. It is
possible in this way to omit a form-fitting connection. It is
naturally possible that, in addition to the improved frictional
connection, a form-fitting connection and/or an integral connection
between the camshaft and the rotor may also be used.
[0023] It is also advantageous in particular if the oxide layer is
formed on a section of a front face of the rotor facing the
camshaft. Assembly may be thereby simplified and the production of
the rotor may be carried out less expensively. The camshaft
adjuster with the screw connection integrated therein is then
optimized with regard to its function, its weight and its
installation space.
[0024] If the section having the oxide layer is a surface of the
bottom of a central recess in the rotor running transversely,
preferably orthogonally, to an axis of rotation of the rotor, then
the camshaft may be held centered in the recess and the coefficient
of friction between the contact partners, namely the rotor and the
camshaft, may be increased.
[0025] In order to allow the assembly to be carried out more
reliably, it is advantageous if the bottom forms a stop for the
camshaft, acting in the longitudinal direction of the rotor.
[0026] In order for this friction-increasing oxide layer to be
simple to produce, it is advantageous if the rotor is strengthened
in a water vapor-induced process in at least some areas or as a
whole. As a pleasant side effect, then the total strength of the
rotor is also improved, at least in the areas treated with water
vapor, but preferably the entire component is strengthened as a
whole, i.e., "through and through."
[0027] It is also advantageous for the total strength of the
individual parts of the camshaft adjuster if the stator has a
friction-increasing oxide layer on at least one or both front faces
due to the water vapor application. It is then possible to achieve
a greater transfer of force in the installed state and the
attachment of covers with the aid of screw connections.
[0028] The present invention also relates to a method for producing
a rotor for a camshaft adjuster, which is improved by the fact that
the rotor is constructed of sintered material at least in some
sections, and at least one area of application of the sintered
material, which is provided for use of a camshaft, is treated with
water vapor.
[0029] In such a process sequence, the oxide layer created on the
surface of the rotor may be left in place and may be used as an
active unit which prevents twisting of the camshaft relative to the
rotor.
[0030] It is also advantageous if the oxide layer formed by the
action of water vapor is left on the surface of the rotor, so that
this oxide layer preferably interacts with the camshaft in a
force-transferring manner in the installed state of the rotor
inside a stator.
[0031] It is quite possible for the rotor to be produced only
partially or completely of metallic sintered material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] The present invention is explained in greater detail below
with the aid of a drawing illustrating an exemplary embodiment in
FIG. 1.
[0033] FIG. 1 shows a camshaft adjuster having a rotor which is
inserted rotatably into a stator.
DETAILED DESCRIPTION
[0034] This FIG. 1 shows a camshaft adjuster 1 according to the
present invention, having a rotor 2 which is inserted rotatably
into a stator 3.
[0035] Stator 3 has an integral sprocket wheel section 4 on which
teeth 5 are formed, to come into force-transferring contact with a
traction mechanism; the traction mechanism, such as a chain or a
belt, may be and/or has been brought into a force-transferring
operative contact with a crankshaft in the internal combustion
engine. The traction mechanism and the crankshaft are not shown
here.
[0036] Rotor 2 may rotate about an axis of rotation 6 inside stator
3 and within a fixed angular range. Axis of rotation 6 also
predefines the longitudinal direction of rotor 2 and of stator
3.
[0037] Rotor 2 has a connecting area 7, which is provided for
accommodating a camshaft. The connecting area 7 is formed by a
front-side recess 8, in such a way that a bottom 9 forms a stop 10
for the camshaft, in such a way that a movement of the camshaft in
its longitudinal direction toward rotor 2 is limited by stop 10. At
least in this area, rotor 2, which is made of sintered material,
preferably a sintered material composed of metallic powders, is
treated with water vapor, so that an oxide layer 11 is formed.
[0038] Whereas oxide layer 11 is present on rotor 2 only inside of
recess 8, in particular on the front face of rotor 2 in the area of
bottom 9, such an oxide layer 11 is also formed on both front faces
12 and 13 of stator 3. A cover is screwed onto this oxide layer 11,
which is present on front faces 12 and 13 of stator 3. Joints are
present in a cover screw connection, the cover screw connection
including at least one or two covers and at least two fastening
means 16, such as screws 17, as well as stator 3. At least one
cover is screwed onto stator 3 via at least two screws 17.
[0039] Rotor 2 may also have grooves for insertion of vanes (not
shown), and these grooves may also be treated with water vapor.
[0040] Ultimately it is possible for both rotor 2 and stator 3 to
be treated completely with water vapor and for oxide layer 11 to be
formed and/or left on only one or both front faces 12 and 13 of
stator 3 and on bottom 9 of rotor 2 in recess 8 due to water vapor
application of the metallic sintered material.
LIST OF REFERENCE NUMERALS
[0041] 1 camshaft adjuster
[0042] 2 rotor
[0043] 3 stator
[0044] 4 sprocket wheel section
[0045] 5 tooth
[0046] 6 axis of rotation
[0047] 7 connecting area
[0048] 8 recess
[0049] 9 bottom
[0050] 10 stop
[0051] 11 oxide layer
[0052] 12 first front face of the stator
[0053] 13 second front face of the stator
[0054] 14 first cover
[0055] 15 second cover
[0056] 16 fastening means
[0057] 17 screw
* * * * *