U.S. patent application number 13/772418 was filed with the patent office on 2013-08-29 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 Jurgen Weber.
Application Number | 20130220248 13/772418 |
Document ID | / |
Family ID | 48950737 |
Filed Date | 2013-08-29 |
United States Patent
Application |
20130220248 |
Kind Code |
A1 |
Weber; Jurgen |
August 29, 2013 |
CAMSHAFT ADJUSTER
Abstract
Camshaft adjuster for an internal combustion engine with a
cylinder head, with a drive element and a driven element, the drive
element and the driven element can be rotated relative to each
other about a common axis, the drive element and the driven element
form work chambers acting opposite each other, the work chambers
are pressurizable with hydraulic medium, in order to achieve a
relative rotation between the drive element and the driven element,
and a control valve is arranged in the driven element, the control
valve has a valve housing and a control piston that is arranged in
the valve housing and is used for controlling the hydraulic medium,
the control valve is arranged coaxial to the common axis, and a
one-piece radial bearing point constructed by the driven element is
provided for support on the cylinder head outside of the axial area
of the work chambers.
Inventors: |
Weber; Jurgen; (Erlangen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schaeffler Technologies AG & Co. KG; |
|
|
US |
|
|
Assignee: |
SCHAEFFLER TECHNOLOGIES AG &
CO. KG
Herzogenaurach
DE
|
Family ID: |
48950737 |
Appl. No.: |
13/772418 |
Filed: |
February 21, 2013 |
Current U.S.
Class: |
123/90.15 |
Current CPC
Class: |
F01L 1/3442 20130101;
F01L 2001/0475 20130101; F01L 2001/34433 20130101; F01L 2001/0476
20130101 |
Class at
Publication: |
123/90.15 |
International
Class: |
F01L 1/344 20060101
F01L001/344 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 24, 2012 |
DE |
102012202823.4 |
Claims
1. A camshaft adjuster for an internal combustion engine with a
cylinder head, the camshaft adjuster comprising: a drive element
and a driven element, the drive element and the driven element are
rotatable relative to each other about a common axis, the drive
element and the driven element form work chambers acting opposite
each other, the work chambers are pressurizable with hydraulic
medium, in order to achieve a relative rotation between the drive
element and the driven element, and a control valve is arranged in
the driven element, the control valve has a valve housing and a
control piston that is arranged in the valve housing and is used
for controlling the hydraulic medium, the control valve is arranged
coaxial to the common axis, and a one-piece radial bearing point
constructed by the driven element is provided for support on the
cylinder head outside of an axial area of the work chambers.
2. The camshaft adjuster according to claim 1, wherein the control
valve is fixed in the axial direction by a positive-fit in the
driven element.
3. The camshaft adjuster according to claim 1, wherein the control
valve is fixed in the axial direction by a non-positive fit in the
driven element.
4. The camshaft adjuster according to claim 1, wherein the driven
element has an anti-rotation device for the control valve, so that
an installation position defined in a peripheral direction is
given.
5. The camshaft adjuster according to claim 1, wherein the valve
housing is formed in one piece with the driven element, and the
driven element forms a guide surface for guiding the control piston
of the control valve.
6. The camshaft adjuster according to claim 1, wherein hydraulic
medium is fed into the control valve by hydraulic medium channels
formed in the camshaft.
7. The camshaft adjuster according to claim 1, wherein the driven
element has a radially projecting peg for attachment to a
camshaft.
8. The camshaft adjuster according to claim 7, wherein the peg is
formed in one piece with the driven element.
9. The camshaft adjuster according to claim 1, wherein the driven
element has a part of an axial bearing and the part of the axial
bearing is formed in one piece with the driven element.
Description
INCORPORATION BY REFERENCE
[0001] The following documents are incorporated herein by reference
as if fully set forth: German Patent Application No.:
102012202823.4, filed Feb. 24, 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 control times of the combustion chamber valves, in
order to be able to variably shape the phase relation between a
crankshaft and a camshaft in a defined angular range between a
maximum advanced position and a maximum retarded position. The
adaptation of the control times to the current load and rotational
speed reduces consumption and emissions. For this purpose, camshaft
adjusters are integrated in a drive train by means of which a
torque is transferred from the crankshaft to the camshaft. This
drive train can be constructed, for example, as a belt drive, chain
drive, or gearwheel drive.
[0004] In a hydraulic camshaft adjuster, the driven element and the
drive element form one or more pairs of pressure chambers that act
against each other and can be pressurized with hydraulic medium.
The drive element and the driven element are arranged coaxially. By
filling and emptying individual pressure chambers, a relative
movement is generated between the drive element and the driven
element.
[0005] One possible type of hydraulic camshaft adjuster is the vane
cell adjuster. The vane cell adjuster has a drive element formed as
a stator, a driven element formed as a rotor, and a drive wheel
with external teeth. The driven element is usually formed so that
it can be locked in rotation with the camshaft. The drive element
contains the stator and the drive wheel. The drive element and the
drive wheel are locked in rotation with each other or are
alternatively constructed as a single piece. The driven element is
arranged coaxial to the drive element and within the drive element.
The driven element and the drive element form oil chambers that act
in opposite directions with their vanes extending in the radial
direction and these chambers can be pressurized by oil pressure and
allow a relative rotation between the drive element and the driven
element. The vanes are constructed either integrally with the
driven element or the drive element or are arranged as "inserted
vanes" in grooves of the driven element or drive element provided
for this purpose. The vane cell adjusters further have various
sealing covers. The drive element and the sealing covers are
secured with each other by several screw 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
using helical gearing is shifted in the axial direction by oil
pressure.
[0007] DE 10 2004 026 863 A1 discloses a camshaft adjuster with a
drive element and a driven element. The camshaft is connected to
the driven element by means of a non-positive, positive, or
material fit connection.
[0008] In DE 10 2008 050 134, a camshaft adjuster is described in
which a connection element is provided in the driven part. The
connection element is fixed in the driven part by means of a
positive-fit connection. The connection element is further attached
to a camshaft. The connection element has recesses that are used
for the oil supply. The oil supply is controlled by means of a
hydraulic valve that is provided in the connection element.
[0009] A camshaft adjuster with a drive element and a driven
element is disclosed in DE 103 34 690 B4. A peg is formed
integrally from the driven element. The peg is used for connecting
to the camshaft. Several oil supply channels are further arranged
in the driven element.
[0010] DE 10 2009 052 841 A1 discloses a camshaft adjuster in which
a camshaft insert is used for attaching the rotor to the camshaft.
The camshaft insert is locked in rotation with the rotor by means
of a nut. A longitudinal bore that holds a central valve is
provided in the camshaft insert.
[0011] In U.S. Pat. No. 6,871,621 B2, a camshaft adjuster is
described in which the rotor is screwed to the camshaft by means of
a screw. The central valve is inserted from one end of the driven
element and screwed to this driven element.
SUMMARY
[0012] The objective of the present invention is to provide a
camshaft adjuster that can be produced economically.
[0013] This is achieved according to the invention by a camshaft
adjuster for an internal combustion engine with a cylinder head,
with a drive element and a driven element, wherein the drive
element and the driven element can be rotated relative to each
other about a common axis and wherein the drive element and the
driven element form work chambers acting opposite each other,
wherein the work chambers can be pressurized with hydraulic medium,
in order to achieve a relative rotation between the drive element
and the driven element, and wherein a control valve is arranged in
the driven element, wherein the control valve has a valve housing
and a control piston that is arranged in the valve housing and is
used for controlling the hydraulic medium, and wherein the control
valve is arranged coaxial to the common axis, wherein a one-piece
radial bearing point constructed by the driven element is provided
for support on the cylinder head outside of the axial area of the
work chambers.
[0014] Through the integration of the radial bearing point on the
driven element, a compact structural unit is achieved that allows
the camshaft adjuster to be inserted as a structural unit into a
bearing frame of an open cylinder head. Furthermore, a true-running
error can be minimized by the one-piece construction.
[0015] In one advantageous construction, the control valve is fixed
in the axial direction in the driven element by a non-positive fit
connection. In a non-positive fit connection, the parts are held in
their mutual position by an external force, for example, a friction
force. The non-positive fit connection can be, for example, a ring
that is joined to the driven element by a longitudinal or
transverse interference fit.
[0016] In one preferred construction, the control valve is fixed in
the axial direction in the driven element by a positive fit
connection. In a positive-fit connection, the force is transmitted
through the shape of the parts involved in the connection. For this
purpose, a positive-fit connection must be produced between two
active contacting surfaces. The positive-fit connection can be, for
example, a retaining ring or an expansion ring.
[0017] In one construction of the invention, the driven element has
an anti-rotation device for the control valve, so that an
installation position defined in the peripheral direction is
specified. The anti-rotation device is required so that the control
valve and the driven element cannot rotate relative to each other
when the camshaft adjuster is activated. The anti-rotation device
can be, for example, an axial groove, notch, recess, or the like in
the driven element. The anti-rotation device in the driven part is
advantageously produced by pressing, sintering, or calibrating
methods, wherein the high costs due to milling can be avoided.
[0018] The control valve engages in the anti-rotation device of the
driven element. To allow this, projecting flaps, tabs, or other
raised section are provided on the control valve.
[0019] In one construction of the invention, the valve housing is
formed integrally with the driven element, wherein the driven
element forms a guide surface for guiding the control piston of the
control valve. The valve housing can be formed, for example, by a
bore in the driven element, wherein the bore forming the valve
housing is here arranged coaxial to the axis about which the drive
element and the driven element can rotate relative to each other.
The bore can be constructed as a through hole or as a blind hole.
The other components of the control valve, such as the control
piston and a compression spring, can be inserted as "insert pieces"
into this bore.
[0020] By integrating the valve housing in the driven element, the
control piston is consequently guided by the driven element. In the
axial direction, the control piston can move in the driven element
and thus can be positioned in any axial position relative to the
driven element. This has the advantage that the material and
production costs that occur for a control valve with a separate
valve housing can be reduced, just like the assembly costs. Another
advantage of the invention is that the control piston can be used
without tension and deformation in the driven element.
[0021] In a preferred construction, the hydraulic medium can be fed
into the control valve by hydraulic medium channels formed in the
camshaft. Alternatively, a supply of the hydraulic medium into the
control valve can be provided in the axial or radial direction in
the radial bearing position. For the supply and distribution of the
hydraulic medium, hydraulic medium channels are provided in the
camshaft or also in the radial bearing position according to the
embodiment. In addition, the driven element has other hydraulic
medium channels that interact with openings of the control valve.
These hydraulic medium channels can run in the driven element in
the radial or also in the axial direction to the work chambers and
through openings, such as bores or through recesses, such as
channels, grooves, or other formations. Through the axial
positioning of the control piston, the different openings of the
control valve and the hydraulic medium channels are connected to
each other hydraulically or separated from each other.
[0022] In another construction of the invention, the driven element
has a radial projecting peg for attachment to a camshaft. The peg
can be made, for example, from a solid material or like a kind of
sleeve or pipe. By the use of a positive-fit, non-positive fit, or
material fit connection, the peg can be locked in rotation with the
camshaft. According to the kind of connection, the lateral surface
of the peg can be adapted accordingly. Here, the lateral surface of
the peg can be smooth, roughened, or provided with raised
sections.
[0023] In one construction of the invention, the peg is formed
integrally with the driven element. The peg can be locked in
rotation with the driven element by a material fit, positive fit,
or non-positive fit connection. Alternatively, it is also possible
to form the peg as a separate component or as multiple components.
In this way it is possible that the peg is formed from multiple
pins.
[0024] In one advantageous construction, the driven element has an
axial bearing and a part of the axial bearing is formed integrally
with the driven element. Optionally, the axial bearing could also
be formed separately and connected to the driven element by a
non-positive fit, positive fit, or material fit connection. The
other part of the axial bearing can be formed by the camshaft or
the cylinder head.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] An embodiment of the invention is described below with
reference to three figures. Shown are:
[0026] FIG. 1 a section view through the camshaft adjuster
according to the invention,
[0027] FIG. 2 a section view through a driven element of the
camshaft adjuster according to the invention, and
[0028] FIG. 3 a side view of the camshaft adjuster according to the
invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0029] FIG. 1 shows a camshaft adjuster 1 with a camshaft 2 that is
shown partially and is formed with a tubular shape. The camshaft
adjuster 1 has a drive element 3 that is formed as a stator 4 and a
driven element 5 that is formed as a rotor 6. The stator 4 and the
rotor 6 can be rotated about a common axis la relative to each
other. Furthermore, a drive wheel 4a is formed integrally on the
stator 4. In addition, the camshaft adjuster 1 has a cover 7 on
which a spring 8 is suspended. The cover 7 is connected to the
stator 4 by a screw connection 9.
[0030] As can be further seen, the camshaft adjuster 1 has a first
axial bearing point 10 and a second axial bearing point 11 that are
formed with a ring shape. The first axial bearing point 10 is
connected to a section of the rotor. The second axial bearing point
11 is provided on the camshaft end 2a facing the rotor 6.
[0031] For better understanding of the structure of rotor 6, in
addition to FIG. 1, FIG. 2 is also referenced. As can be seen from
FIG. 2, the rotor 6 has a step-shaped structure that forms three
rotor areas 6a, 6b, 6c.
[0032] A first rotor area 6a has vanes 12. The vanes 12 are formed
integrally on the rotor 6. With the stator 4, the vanes 12 of the
rotor 6 form work chambers (not shown) that can be pressurized with
hydraulic medium.
[0033] On the rotor area 6a on which the vanes 10 are formed
integrally, a second rotor area 6b connects that forms a radial
bearing point 13. The radial bearing point 13 is formed integrally
on the rotor 6. As FIG. 2 shows, the radial bearing point is
smaller in diameter than the rotor area 6a that has the vanes 10.
The radial bearing point 11 is provided for the support of a
cylinder head.
[0034] On the rotor area 6b, a third rotor area 6c connects that is
formed by a peg 14. The peg 14 is formed from a solid material and
is smaller in diameter than the rotor area 6b that forms the radial
bearing point 11. The peg 14 is used for the rotationally locked
attachment to the camshaft 2. For this purpose, the peg 14 is
joined by a non-positive fit connection into the open camshaft end
2a.
[0035] The rotor 6 has a blind bore 15 coaxial to the axis 1. The
blind bore 15 extends in the axial direction along the first rotor
area 6a and the second rotor area 6b. As can be seen, several bores
16 are provided in the blind bore 15. The bores 16 form hydraulic
medium channels 17. The hydraulic medium channels 17 extend in the
radial direction and are used to provide the not-shown work
chambers with hydraulic medium. In the area of the bores 16 there
are additional ring channels 18 that guide the hydraulic medium
into the hydraulic medium channels 17.
[0036] As can be further seen from FIG. 2, the rotor 6 has, in the
area of the peg 12, the bore 19. In the embodiment, two such bores
19 are provided. The bores 19 run in the radial direction and are
formed as passage bores. The bores 19 are used in the rotor as
supply 20. This supply 20 is connected to a not-shown compressed
medium pump. The hydraulic medium is led in the direction of a
control valve 21a by the supply 22.
[0037] Furthermore, the blind bore 15 forms a valve housing 21 of
the control valve 21a. In the valve housing 21 integrated in the
rotor 6, a control piston 21b, a not-shown compression spring of
the control valve 21a are inserted as insert parts. The valve
housing 20 formed by the blind bore 15 forms a guide surface for
the not-shown control piston. The control piston 21b can move in
the axial direction into the blind bore 15 and interacts with the
hydraulic medium channels 17 in the rotor 6.
[0038] The rotor 6 has an anti-rotation device 22 for the control
valve. The anti-rotation device 22 is formed as an axial groove 23
in the rotor 6 in which the control valve 21a can engage.
[0039] The securing of the control valve 21a in the axial direction
can be seen from FIG. 3. The axial securing of the control valve
21a is realized with a positive-fit connection by a retaining ring
24.
LIST OF REFERENCE NUMBERS
[0040] 1a Axis
[0041] 1 Camshaft adjuster
[0042] 2 Camshaft
[0043] 2a Camshaft end
[0044] 3 Drive element
[0045] 4 Stator
[0046] 4a Drive wheel
[0047] 5 Driven element
[0048] 6 Rotor
[0049] 6a First rotor area
[0050] 6b Second rotor area
[0051] 6c Third rotor area
[0052] 7 Cover
[0053] 8 Spring
[0054] 9 Screw connection
[0055] 10 First axial bearing point
[0056] 11 Second axial bearing point
[0057] 12 Vane
[0058] 13 Radial bearing point
[0059] 14 Peg
[0060] 15 Blind hole
[0061] 16 Bore
[0062] 17 Hydraulic medium channels
[0063] 18 Ring-shaped channel
[0064] 19 Bore
[0065] 20 Feed
[0066] 21 Valve housing
[0067] 21a Control valve
[0068] 21b Control piston
[0069] 22 Anti-rotation device
[0070] 23 Axial groove
[0071] 24 Retaining ring
* * * * *