U.S. patent application number 13/738237 was filed with the patent office on 2013-07-18 for camshaft adjuster.
This patent application is currently assigned to SCHAEFFLER TECHNOLOGIES AG & CO. KG. The applicant listed for this patent is SCHAEFFLER TECHNOLOGIES AG & CO. KG. Invention is credited to Holger Brenner, Sven Weisser.
Application Number | 20130180483 13/738237 |
Document ID | / |
Family ID | 48693271 |
Filed Date | 2013-07-18 |
United States Patent
Application |
20130180483 |
Kind Code |
A1 |
Weisser; Sven ; et
al. |
July 18, 2013 |
CAMSHAFT ADJUSTER
Abstract
A camshaft adjuster (1) is provided with a restoring spring (4)
having a spring end (6) for support on the driven element (3) that
has a wavelike shape.
Inventors: |
Weisser; Sven; (Weisendorf,
DE) ; Brenner; Holger; (Obermichelbach, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SCHAEFFLER TECHNOLOGIES AG & CO. KG; |
Herzogenaurach |
|
DE |
|
|
Assignee: |
SCHAEFFLER TECHNOLOGIES AG &
CO. KG
Herzogenaurach
DE
|
Family ID: |
48693271 |
Appl. No.: |
13/738237 |
Filed: |
January 10, 2013 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F01L 1/3442 20130101;
F01L 1/344 20130101; F01L 2001/34483 20130101 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 1/344 20060101
F01L001/344 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 18, 2012 |
DE |
102012200683.4 |
Claims
1. A camshaft adjuster comprising a drive element, a driven
element, and also a restoring spring which are arranged coaxial to
a rotational axis of the camshaft adjuster, the restoring spring
generates a relative rotation of the drive element relative to the
driven element, and a spring end of the restoring spring that is
provided for support on the driven element has a wavelike
shape.
2. The camshaft adjuster according to claim 1, wherein a support
point for the spring end on the driven element has a shape that is
complementary to the wavelike shape of the spring end.
3. The camshaft adjuster according to claim 2, wherein the support
point is formed as part of a hub of a spring cover that is locked
in rotation with the driven element.
4. The camshaft adjuster according to claim 3, wherein the spring
cover is formed from sheet metal.
5. The camshaft adjuster according to claim 3, wherein the support
point is formed integrally with the spring cover and shaped away
from the rotational axis in the radial direction.
6. The camshaft adjuster according to claim 3, wherein the spring
cover has a retaining tab that fixes the spring end in a radial
direction.
7. The camshaft adjuster according to claim 6, wherein the
retaining tab is formed integrally from the spring cover.
8. The camshaft adjuster according to claim 6, wherein the support
point or the retaining tab of the spring cover is provided for
angular positioning of the spring cover relative to the driven
element.
9. The camshaft adjuster according to claim 1, wherein a spring
cover is locked in rotation with the driven element, the driven
element is connectable with a camshaft, and the spring cover is
simultaneously formed as a trigger wheel.
10. A restoring spring of a camshaft adjuster according to claim 1.
Description
INCORPORATION BY REFERENCE
[0001] The following documents are incorporated herein by reference
as if fully set forth: German Patent Application No.
102012200683.4, filed Jan. 18, 2012.
FIELD OF THE INVENTION
[0002] The invention relates to a camshaft adjuster.
BACKGROUND
[0003] Camshaft adjusters are used in internal combustion engines
for varying the timing of combustion chamber valves, in order to
vary the phase relation between a crankshaft and a camshaft in a
defined angular range between a maximum advanced position and a
maximum retarded position. Adjusting the timing to the current load
and rotational speed lowers consumption and emissions. For this
purpose, camshaft adjusters are integrated into a drive train by
which torque is transmitted from the crankshaft to the camshaft.
This drive train can be formed, for example, as a belt, chain, or
gearwheel train.
[0004] In a hydraulic camshaft adjuster, the driven element and the
drive element form one or more pairs of pressure chambers that act
opposite each other and can be charged with hydraulic medium. The
drive element and the driven element are arranged coaxially. By
filling and emptying individual pressure chambers, a relative
movement is created between the drive element and the driven
element. The rotationally acting spring between the drive element
and the driven element forces the drive element in a preferred
direction opposite the driven element. This preferred direction can
be in the same direction or in the opposite direction relative to
the direction of rotation.
[0005] One type of hydraulic camshaft adjuster is the vane cell
adjuster. The vane cell adjuster has a stator, a rotor, and a drive
wheel with external teeth. The rotor is constructed as a driven
element that can be locked in rotation usually with the camshaft.
The drive element includes the stator and the drive wheel. The
stator and the drive wheel are locked in rotation with each other
or are constructed, as an alternative, integrally with each other.
The rotor is arranged coaxial to the stator and within the stator.
With their radially extending vanes, the rotor and the stator form
oppositely acting oil chambers that can be charged by oil pressure
and allow a relative rotation between the stator and the rotor. The
vanes are either formed integrally with the rotor or the stator or
arranged as "inserted vanes" in grooves provided for this reason in
the rotor or the stator. Furthermore, the vane cell adjusters have
various sealing covers. The stator and the sealing covers are
secured with each other by means of multiple threaded
connections.
[0006] Another type of hydraulic camshaft adjuster is the axial
piston adjuster. Here, a displacement element that generates a
relative rotation between a drive element and a driven element via
helical gearing is displaced in the axial direction by oil
pressure.
[0007] Another construction of a camshaft adjuster is the
electromechanical camshaft adjuster that has a triple shaft gear
(for example, a planetary gear). Here, one of the shafts forms the
drive element and a second shaft forms the driven element. Through
the use of the third shaft, rotational energy can be fed to the
system or output from the system by a control device, for example,
an electric motor or a brake. There can also be a spring that
increases or decreases the relative rotation between the drive
element and the driven element.
[0008] JP 2003 120 229 shows different possibilities for supporting
the spring ends of a restoring spring, in particular, of the radial
outer spring end. In all of diagrams, the radial inner spring end
is formed as a hook that is bent away from the rotational axis of
the camshaft adjuster and is suspended on the driven element.
[0009] DE 10 2006 002 993 A1, DE 10 2008 051 142 A1, and DE 10 2008
051 755 A1 disclose camshaft adjusters with a restoring spring,
wherein the radial inner spring end is bent by approx. 180.degree.
and is supported on a pin that is locked in rotation with the
driven element.
SUMMARY
[0010] The object of the invention is to provide a camshaft
adjuster that has a particularly reliable spring support.
[0011] This objective is met with a camshaft adjuster having one or
more features of the invention.
[0012] For meeting this objective, a camshaft adjuster is provided
that has a drive element and a driven element and also a restoring
spring, wherein the mentioned components are arranged coaxial to
the rotational axis of the camshaft adjuster, wherein the restoring
spring generates a relative rotation of the drive element relative
to the driven element, and wherein, according to the invention, the
spring end of the restoring spring that is provided for support on
the driven element has a wavelike shape.
[0013] Due to the wavelike shape of the spring end that is provided
for support on the driven element, it is achieved that, for one,
especially for a radial winding body, packaging space is saved and
the load on the spring wire in the area of the spring support is
reduced in contrast to a hook-shaped spring end known in the prior
art. Advantageously, the bending radius of the spring end can align
with the spring support such that an improved contact is achieved
and Hertzian contact pressure is reduced.
[0014] There are predominantly two types of restoring springs. The
two types of restoring springs are, on one hand, those with radial
winding bodies and, on the other hand, those with axial winding
bodies. The wavelike spring end is to be formed in both types of
restoring springs. The restoring springs with radial winding bodies
are advantageously to be used in axially limited packaging spaces,
wherein, in contrast, the restoring springs with axial winding
bodies are to be used in radially limited packaging spaces.
[0015] A wavelike spring end characterizes itself with the general
understanding of a "wave," that is, with at least one wave peak or
at least one wave valley. Wave peaks and wave valleys can be
arranged one after the other in rows in arbitrary frequency and can
have different or equal amplitudes. A wave peak is viewed here as
the amplitude away from the rotational axis of the camshaft
adjuster, wherein analogously a wave valley is to be viewed as the
amplitude toward the rotational axis of the camshaft adjuster. The
amplitude itself is to be considered as the radial deviation from
the imaginary extension in the continuing course of the winding, as
much as possible in the direction of the wire extension.
[0016] With advancing angle around the rotational axis, the
starting and end points of a wave decrease, approaching the same
reference circle. Alternatively, it is possible to arrange the end
point of a wave on a reference circle that is different from the
starting point.
[0017] In one construction of the invention, the support point on
the driven element has a shape that is complementary to the wave
shape of the spring end. Advantageously, the complementary shape to
the wave shape is formed such that an optimum osculation is
achieved between the spring end and support and Hertzian contact
pressure is significantly reduced. The complementary shape can be
formed on the driven element itself, ideally in the area of its
hub, or on a component locked in rotation with the driven element.
The spring end is advantageously supported on the complementary
support point, biased in the radial direction. Alternatively, the
radial biasing can be eliminated.
[0018] In one advantageous construction, the support point is
formed as part of a hub of a spring cover locked in rotation with
the driven element. The spring cover protects the windings of the
restoring spring from environmental influences and prevents that
parts of a broken spring from being able to move into the internal
combustion engine in the event of the breaking of a spring. The
spring cover is advantageously formed as a thin-wall component with
a hub. The hub is locked in rotation coaxially with the driven
element.
[0019] In one particularly preferred construction, the spring cover
is formed from sheet metal. The support point for the spring end
can be shaped into the spring cover made from sheet metal by deep
drawing, bending, stamping, or other shaping processes.
Alternatively, the spring cover could be formed from a plastic and
the support point could be produced, e.g., by casting or other
shaping processes. The complementary support point can also be
arranged as a separate component on the spring cover made from
sheet metal by means of positive-fit, non-positive-fit, and/or
material-fit connection techniques.
[0020] In one construction of the invention, the support point is
formed integrally with the spring cover and is shaped away from the
rotational axis of the camshaft adjuster. Thus, the support point
of the construction of a wave peak corresponds analogously to that
of the wave peak of the spring end. The formation of the support
point on the spring cover as a wave peak is advantageous, so that,
on the components arranged within the hub, no other modifications
can be performed and the hub can have a very thin shape.
[0021] As an alternative, the construction of a wave valley has the
advantage that, especially for a restoring spring with a radial
winding body, the radial packaging space is better used for the
next winding and the entire winding body can be housed in a smaller
radial packaging space.
[0022] In one preferred construction, the spring cover has a
retaining tab that fixes the spring end in the radial direction.
The retaining tab is provided on the support point as a counter
holder of the wavelike spring end, in order to increase the
security of the contact between the spring end and support point.
Advantageously, slippage of the spring end from the support point,
caused, e.g., by vibrations of the internal combustion engine, is
counteracted in this way. The retaining tab fixes the spring end in
the radial and/or peripheral direction in a positive-fit
connection. Multiple retaining tabs on the spring cover can flank a
wave peak of the spring end or can be arranged centrally relative
to a wave valley of the spring end.
[0023] In another construction of the invention, the retaining tab
is formed integrally from the spring cover. In particular, a
construction of the spring cover made from sheet metal is
advantageous with respect to economy and reliability or service
life. Alternatively, such retaining tabs can be cast on a spring
cover made from metal or plastic.
[0024] In one advantageous construction, the support point or the
retaining tab of the spring cover is provided for the angular
positioning of the spring cover relative to the driven element. By
use of the support point or the retaining tab, a positive-fit
connection of the spring cover relative to the driven element can
be simultaneously formed that guarantees a reliable orientation of
the driven element relative to the spring cover and thus also
relative to the restoring spring and thus ensures a reliable
construction of the desired spring moment between the driven
element and the drive element.
[0025] In another construction of the invention, a spring cover is
locked in rotation with the driven element, wherein the driven
element can be connected, in turn, with a camshaft and the spring
cover is formed simultaneously as a trigger wheel. Especially for
restoring springs with radial winding bodies, these are
advantageously arranged on an end face of the camshaft adjuster and
covered by the spring cover. A trigger wheel function by formed
notches or other markings on the spring cover presents itself
advantageously and can be achieved easily by an angular position
sensor. By the use of a central screw/nut, spring covers with
trigger wheel functions, driven elements, and camshafts can be
locked in rotation with each other.
[0026] A reliable and low-tension connection of the restoring
spring to the driven element is achieved by the construction
according to the invention of the spring end for support on the
driven element in a wavelike shape.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Embodiments of the invention are shown in the figures.
[0028] Shown are:
[0029] FIG. 1 is a view of a camshaft adjuster with a restoring
spring according to the prior art,
[0030] FIG. 2 is a view of a camshaft adjuster with the
construction of the spring end and its support point according to
the invention, and
[0031] FIG. 3 is a view of the spring cover and the restoring
spring of the camshaft adjuster according to FIG. 2 in an
additional view.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] FIG. 1 shows a camshaft adjuster 1 with a restoring spring 4
according to the prior art. The function and the construction of a
hydraulic camshaft adjuster 1 with the arrangement of drive element
2 and driven element 3 in its construction as a vane-cell adjuster
or as an axial piston adjuster is known from the prior art and
explained sufficiently in the introduction. The support point 7 is
formed as a pin and locked in rotation with the driven element 3.
The restoring spring 4 has a radial winding body, i.e., the
windings line up in the radial direction. The spring end 6 that is
supported on the support point 7 has a hook-shaped construction.
The hook was bent from the imaginary extension of the wire of the
restoring spring 4 radially inward, that is, toward the rotational
axis 5, by approximately 90.degree. and extends around the support
point 7. The inner radius of the hook of the spring end 6 is
approximately equal to the radius of the pin of the support point
7.
[0033] Analogous to the inner spring end 6, the outer spring end 12
of the restoring spring 4 is supported on a support point 11,
wherein the support point 11 is locked in rotation with the drive
element 2. The spring end 12 was bent approximately by 180.degree..
The inner radius of the spring end 12 is approximately equal to the
radius of the support point 11.
[0034] FIG. 2 shows a camshaft adjuster 1 with the wavelike
construction according to the invention of the spring end 6 and its
support point 7. The spring cover 9 is arranged coaxial to the
rotational axis 5 of the camshaft adjuster 1. The spring cover 9
has a hub 8 and a ring disk 13 constructed integrally on this hub.
The spring cover 9 is constructed as a thin-wall sheet metal part
and locked in rotation with the driven element 3. The ring disk 13
of the spring cover 9 extends in the radial direction and covers a
part of the winding body of the restoring spring 4. The ring disk
13 has two retaining tabs 10 and a support point 7. The retaining
tabs 10 are oriented relative to the drive element 2 or the driven
element 3 and machined integrally from the sheet metal part. The
support point 7 is constructed as a bead from the outer diameter of
the hub 8 and oriented away from the rotational axis 5 of the
camshaft adjuster 1. The two retaining tabs 10 flank the support
point 7.
[0035] The construction of the outer spring end 12 of the restoring
spring 4 corresponds to the construction of the outer spring end 12
according to FIG. 1.
[0036] FIG. 3 shows the spring cover 9 and the restoring spring 4
of the camshaft adjuster 1 according to FIG. 2 in another view.
This view shows the side of the spring cover 9 that is hidden in
FIG. 2. With the now free view onto the wavelike spring end 6 it is
easily visible that the spring end 6 is constructed as a wave peak.
The start and end of the wave peak are located as much as possible
on the same reference circle. The support point 7 constructed as a
bead projects in its axial extent past the wire thickness of the
restoring spring 4. The retaining tabs 10 are bent at an angle of
approximately 90.degree. away from the ring disk 13.
[0037] If the spring end 12 is now deflected so that the winding
body is tensioned, the retaining tabs 10 prevent slippage of the
spring end 6 past the support point 7 in the peripheral direction.
Due to the feasibility of a larger osculation between the spring
end 6 and support point 7 due to larger radii in the contact point,
the tension load on the spring end 6 is minimized.
[0038] In addition, the spring cover 9 has an integral flange 14
connected to its hub 8. With this flange 14, the spring cover 9 can
be locked in rotation via a central threaded connection, coaxial to
the rotational axis 5, with the driven element 3 and a camshaft.
The support point 7 and/or the positive-fit element 15 are provided
for the angular-oriented fixing of the spring cover 9 relative to
the driven element 3. The support point 7 and/or the positive-fit
element 15 engage in complementary receptacles of the driven
element 3. Advantageously, the support point 7 and the positive-fit
element 15 have the same shape, but are arranged in a pattern for
the clear angular positioning between the spring cover 9 and driven
element 3 on the periphery of the hub 8. The spring cover 9 can be
centered relative to the driven element 3 by means of the hub 8,
especially with its outer diameter.
LIST OF REFERENCE NUMBERS
[0039] 1) Camshaft adjuster [0040] 2) Drive element [0041] 3)
Driven element [0042] 4) Restoring spring [0043] 5) Rotational axis
[0044] 6) Spring end [0045] 7) Support point [0046] 8) Hub [0047]
9) Spring cover [0048] 10) Retaining tab [0049] 11) Support point
[0050] 12) Spring end [0051] 13) Ring disk [0052] 14) Flange [0053]
15) Positive-fit element
* * * * *