U.S. patent application number 11/441408 was filed with the patent office on 2006-10-26 for adjusting device for a camshaft of an internal combustion engine.
Invention is credited to Alexander von Gaisberg-Helfenberg, Matthias Gregor, Jens Meintschel, Thomas Stolk.
Application Number | 20060236967 11/441408 |
Document ID | / |
Family ID | 34706256 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060236967 |
Kind Code |
A1 |
Gregor; Matthias ; et
al. |
October 26, 2006 |
Adjusting device for a camshaft of an internal combustion
engine
Abstract
In an adjusting device for a camshaft of an internal combustion
engine having a drive element which is driven by a crankshaft of
the internal combustion engine, an output element which drives the
camshaft of the internal combustion engine, and an actuating
element controlled by a brake so as to provide for a relative
rotation between the drive element and output element by varying
the braking torque effective on the actuating element.
Inventors: |
Gregor; Matthias;
(Stuttgart, DE) ; Meintschel; Jens; (Esslingen,
DE) ; Stolk; Thomas; (Kirchheim, DE) ;
Gaisberg-Helfenberg; Alexander von; (Beilstein, DE) |
Correspondence
Address: |
Klaus Bach
4407 Twin Oaks Drive
Murrysville
PA
15668
US
|
Family ID: |
34706256 |
Appl. No.: |
11/441408 |
Filed: |
May 25, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP04/12536 |
Nov 5, 2004 |
|
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11441408 |
May 25, 2006 |
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Current U.S.
Class: |
123/90.17 ;
123/90.15 |
Current CPC
Class: |
F01L 1/344 20130101;
F01L 1/352 20130101 |
Class at
Publication: |
123/090.17 ;
123/090.15 |
International
Class: |
F01L 1/34 20060101
F01L001/34 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 28, 2003 |
DE |
103 55 560.9 |
Claims
1. An adjusting device (1) for a camshaft (2) of an internal
combustion engine, including a drive element (3) which is driven by
a crankshaft of the internal combustion engine, an output element
(4) which is connected to the camshaft (2) of the internal
combustion engine, and an actuating element (5) including a brake
(6) for generating relative rotation between the drive element (3)
and output element (4) by varying the braking torque effective on
the actuating element (5), the arrangement permitting the setting
of any desired phase angle between the drive element (3) and output
element (4).
2. The adjusting device as claimed in claim 1, wherein the phase
angle between the drive element (3) and the output element (4) is
adjustable exclusively by means of the brake (6).
3. The adjusting device as claimed in claim 1, wherein the brake
(6) is one of a single-acting and multiple-acting brake.
4. The adjusting device as claimed in claim 1, wherein the brake
(6) is an electrically actuated brake which operates in a
contact-free fashion.
5. The adjusting device as claimed in claim 1, wherein the
adjustment of the phase angle can be limited by means of a
stop.
6. The adjusting device as claimed in claim 1, wherein the
adjusting device (1) is embodied in such a way that the actuating
element (5) and the output element (4) have opposite directions of
rotation.
7. The adjusting device as claimed in claim 1, wherein the
adjusting device (1) is embodied in such a way that the actuating
element (5) and the output element (4) have the same direction of
rotation.
8. The adjusting device as claimed in claim 1, wherein an actuating
spring (17) is effective between two of the three elements (3 to 5)
of the adjusting device (1).
9. The adjusting device as claimed in claim 1, wherein the
adjusting device (1) is embodied as a gear mechanism.
10. The adjusting device as claimed in claim 1, wherein the
adjusting device (1) is embodied as at least one planetary gear
mechanism.
11. The adjusting device as claimed in claim 10, wherein the
adjusting device (1) includes two planetary gear mechanisms (3, 5,
8 and 13, 5, 8) which are coupled to one another, the two planetary
gear mechanisms having common elements (5, 8).
12. The adjusting device as claimed in claim 1, wherein the three
elements (3 to 5) of the adjusting device are each embodied as one
of the elements of a planetary gear mechanism, the planetary gear
mechanism having a ring gear (3, 4, 13), planet carriers (3, 4) and
a sun gear (5).
Description
[0001] This is a Continuation-In-Part Application of International
Application PCT/EP2004/012536 filed Nov. 5, 2004 and claiming the
priority of German Application 103 55 560.9 filed Nov. 28,
2003.
BACKGROUND OF THE INVENTION
[0002] The invention relates to an adjusting device for a camshaft
of an internal combustion engine with a drive element driven by the
crankshaft of the engine and capable of changing the angular
position of the camshaft relative to the crankshaft.
[0003] DE 100 38 354 A1 discloses an adjusting device for a
camshaft of an internal combustion engine which is composed of a
planetary summing gear mechanism and an electric servo-motor. One
of the two inputs of the gear mechanism is connected to the
crankshaft of the internal combustion engine, and the other input
is connected to the servomotor. The camshaft is mounted on the
output of the gear mechanism. When the rotational speed of the
servomotor changes, the rotational speed of the camshaft is changed
compared to the crankshaft and the phase angle of the camshaft with
respect to the crankshaft is adjusted. However, in order to
implement this solution, a two-stage gear mechanism with a high
transmission ratio is required, which entails increased costs. In
addition, relatively high currents flow during the adjustment,
making a power output stage necessary.
[0004] DE 102 47 650 A1 discloses an adjustment device of the
generic type for a camshaft of an internal combustion engine. The
adjusting device has a drive element which is connected fixedly for
rotation with the crankshaft, and an output element which is
arranged on the camshaft side. In order to adjust the phase angle
between the drive element and output element, an actuating element,
which is embodied as a lever mechanism, is arranged between the two
elements, with a brake acting on the actuating element. However,
the lever mechanism is relatively complex and very sensitive to
wear and also only permits a limited adjustment range. As a result
of the direct connection of the camshaft to the crankshaft, the
rotor of the brake, which is connected to the actuating element or
the lever mechanism, must run with a constant phase angle and at
the same rotational speed (transmission ratio 1:1) as the camshaft.
Owing to the transmission ratio of the input and output elements,
components are necessary for the adjustment in both directions. The
adjustment of the phase angle is performed by braking or
accelerating the rotor. In order to be able to rotate the camshaft
for advancing the crankshaft, i.e. accelerate the rotor, a
rotational spring is additionally located on the actuating element
and its continuously acting torque has to be additionally
counteracted by braking when the phase angle is constant or when
retarding is desired and this additional braking adversely affects
the efficiency of the engine.
[0005] For the general technical background, reference is made to
DE 102 47 54 A1, DE 103 01 493 A1 and DE 102 03 621 A1.
[0006] It is the principal object of the present invention to
provide an adjusting device for a camshaft of an internal
combustion engine which permits use in any field of application
while being cost-effective and simple to manufacture.
SUMMARY OF THE INVENTION
[0007] In an adjusting device for a camshaft of an internal
combustion engine, having a drive element which is driven by a
crankshaft of the internal combustion engine, an output element
which drives the camshaft of the internal combustion engine, and an
actuating element controlled by a brake so as to provide for a
relative rotation between the drive element and the output element
by varying the braking torque effective on the actuating
element.
[0008] A substantial advantage of the invention is that the
adjusting device can be used for all applications and all phase
angle ranges since the actuating range is theoretically unlimited
by virtue of the use of a planetary gear mechanism.
[0009] The phase angle between the drive element and the output
element is advantageously adjusted exclusively by means of a brake.
The electrically adjusted brake does not require a power output
stage in the control device since the currents which are necessary
with the interposition of a high-ratio planetary gear mechanism are
very low. A hysteresis brake whose brake torque is independent of
the rotational speed is preferably used.
[0010] The adjusting device can advantageously be used in all
applications. The originally unlimited actuating range can be
adapted to particular application by means of a stop.
[0011] With a suitable selection of the transmission ratio of the
planetary gear mechanism there is advantageously no need for a
restoring spring, i.e. one adjusting element, in this case the
brake, is sufficient for the adjustment in both directions. If the
adjusting device is however configured for particularly high
actuation dynamics, the load torque of the camshaft can be
increased by an actuating spring in order to implement an optimum
adjusting speed of the camshaft adjuster in one direction when the
brake is released.
[0012] The adjusting device is advantageously embodied as two
planetary gear mechanisms which are coupled to one another and
which have common elements, so that certain components can be
eliminated. This results in a narrow design of the adjusting device
which permits a space-saving arrangement.
[0013] The invention will become more readily apparent from the
following description of exemplary embodiments, thereof on the
basis of the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 shows a camshaft adjuster with a drive element, an
output element and an actuating element which are embodied as what
is referred to as a rotating positive gear mechanism, the actuating
element and the output element having the same direction of
rotation, with a brake capable of engaging the actuating
element,
[0015] FIG. 2 shows a camshaft adjuster which is embodied as what
is referred to as rotating negative gear mechanism, the actuating
element and the output element having opposite directions of
rotation, with a brake capable of engaging the actuating
element,
[0016] FIG. 3 shows a camshaft adjuster with a two-stage, coupled
planetary gear mechanism, and with a brake capable of engaging the
actuating element,
[0017] FIG. 4 shows a camshaft adjuster including an actuating
spring disposed between the drive element and the actuating
element,
[0018] FIG. 5 shows a camshaft adjuster including an actuating
spring disposed between the output element and drive element,
and
[0019] FIG. 6 shows a camshaft adjuster including an actuating
spring disposed between the output element and actuating
element.
DESCRIPTION OF THE VARIOUS EMBODIMENTS
[0020] For the sake of simplicity, the same reference symbols have
been used for the designation of corresponding components in the
various figures.
[0021] FIG. 1 shows an adjusting device 1 for a camshaft 2 of an
internal combustion engine for changing the phase angle of the
camshaft 2 with respect to a crankshaft (not shown here) of an
internal combustion engine according to a first exemplary
embodiment, the camshaft 2 being driven by the crankshaft by means
of the adjusting device 1.
[0022] The adjusting device 1 comprises three elements,
specifically, a drive element 3 which is driven by the crankshaft,
an output element 4 which is connected fixedly in terms of rotation
to the camshaft 2 and which drives the camshaft 2, and an actuating
element 5 for adjusting the phase angle between the drive element 3
and output element 4 to which a brake 6 is connected, it being
possible to bring about a relative rotation between the drive
element 3 and output element 4 by varying the torque at the
actuating element 5. The brake 6 is preferably an electromagnetic
brake which operates without wear, in particular in a contactless
fashion. A hysteresis brake whose torque is independent of the
rotational speed is particularly suitable. The currents which are
required to actuate the brake 6 are so low that no power output
stage is needed in the control device. The brake 6 may be a
single-acting brake or a multiple-acting brake. The rotor (not
shown here) of the brake 6 is connected fixedly in terms of
rotation to the actuating element 5. It is also not shown that the
housing (stator) 7 of the brake 6 is supported on a stationary
component of the internal combustion engine such as, for example, a
cylinder head, cylinder head cover, control casing cover etc. The
drive element 3 is embodied in the present case as a chain gear
which is driven by the crankshaft of the internal combustion engine
via a drive chain (not illustrated here).
[0023] In order to permit the adjusting device to be used in any
field of application, a design of the adjusting device 1 is
described which permits any desired phase angles between the drive
element 3 and output element 4.
[0024] The adjusting device 1 is preferably embodied as a gear
mechanism and in particular as a planetary gear mechanism, and in
this case the three elements 3 to 5 of the adjusting device are
each embodied as one of the elements of the planetary gear
mechanism.
[0025] According to FIG. 1, the elements 3 to 5 of the adjusting
device 1 are embodied as a single-stage planetary gear mechanism. A
planetary gear mechanism is composed of a ring gear 3, planet gears
8, a sun gear 5 and at least one planet carrier 4, which forms the
output element. The output element 4 comprises the two planet
carriers in which the planetary gears 8 are mounted by means of
bearing bolts 9 with their axes 10 extending parallel to the axis
12 of the adjusting device 1. Three planetary gears 8, which are
surrounded on the outside by the drive element 3 which forms the
ring gear, are preferably provided, said planetary gears 8 meshing
with the drive element 3. In the center, the planetary gears 8 run
on the actuating element 5 which is embodied as a sun gear. The
shaft 11 of the actuating element (sun gear) 5 is also the common
axis 12 of rotation for the drive element (ring gear) 3 in this
exemplary embodiment, and the output element (planet carrier) 4. On
the output side, the planetary gears 8 are connected to the
camshaft 2 via the planet carriers 4. In this case, the elements 3
to 5 of the adjusting device 1 are embodied as positive gear
mechanisms, i.e. assuming the chain wheel 3 to be stationary the
actuating element 5 and camshaft 2 rotate in the same
direction.
[0026] The adjustment of the phase angle between the drive element
3 and output element 4 is brought about exclusively by means of the
brake 6, specifically by varying the braking torque at the
actuating element 5. In order to bring about a constant phase angle
between the chain wheel 3 and camshaft 2, the brake 6 acts
correspondingly on the actuating element 5. Varying the braking
torque increases or respectively reduces the rotational speed of
the actuating element 5, causing the phase angle of the camshaft 2
to change relative to the crankshaft.
[0027] FIG. 2 shows an adjusting device 1 according to a second
exemplary embodiment. The adjusting device 1 is also embodied as a
single-stage planetary gear mechanism. The drive element (chain
gear) 3 forms the two planet carriers in which planetary gears 8
are mounted by means of bearing bolts 9 with their axes 10. Three
planetary gears 8 are preferably provided, which are surrounded on
the outside by the output element (camshaft) 4 which forms the ring
gear, said planetary gears 8 meshing with the output element 4. In
the interior, the planetary gears 8 run on the actuating element 5
which is embodied as a sun gear. The shaft 11 of the actuating
element (sun gear) 5 has a common axis 12 of rotation with the
output element (ring gear) 4 and the drive element (planetary gear
carrier) 3. On the output side, the ring gear (output element) 4 is
formed integrally with the camshaft 2. In this case, the elements 3
to 5 of the adjusting device 1 are embodied as negative gear
mechanisms, i.e. assuming the chain wheel 3 to be at standstill the
actuating element 5 and camshaft 2 rotate in opposite
directions.
[0028] A phase shift of the camshaft 2 is brought about by varying
the braking torque at the actuating element 5. The transmission
ratio is preferably selected such that, when there is a constant
phase angle between the drive element 3 and output element 4, the
actuating element 5 is braked to a specific rotational speed which
is equal to the rotational speed of the camshaft 2. Increasing the
braking torque reduces the rotational speed of the actuating
element 5 (if appropriate as far as the stationary state) and
causes the camshaft 2 to be advanced with respect to the chain
wheel 3. If the braking torque is reduced (if appropriate as far as
zero, i.e. "actuating element free") the actuating element 5 is
accelerated by the load torque of the camshaft 2 and the camshaft 2
is thus retarded with respect to the chain wheel 3.
[0029] FIG. 3 shows an adjusting device 1 according to a third
exemplary embodiment. The adjusting device 1 is embodied as a
two-stage, coupled planetary gear mechanism, both planetary gear
mechanism units having common elements 5, 8. Each planetary gear
mechanism unit has it own ring gear structure 3, 13 with internal
toothing 14, 15 and each shares both the sun wheel 5 and the planet
gears 8 with the other planetary gear mechanism unit, the
drive-side ring gear being formed by the chain wheel 3. The ring
gears 3, 13 mesh with their toothings 14, 15 with the planet gears
8. The planet gears 8 are arranged distributed circumferentially in
the space between the ring gears 3, 13 and the actuating gear
element 5 which is a sun gear, i.e. the planet gears 8 are merely
inserted loosely without particular bearing. The planet gears 8 are
guided axially by an abutment disk 16 which is connected to the
chain wheel 3, and an output element 4 which is formed on the
camshaft 2 and is firmly connected to the output-side ring gear 13.
The planet gears 8 mesh with the actuating element 5. The axis of
the shaft 11 of the actuating element (sun gear) 5 is also the axis
12 of rotation for the drive-side ring gear 3 and the output-side
ring gear 13. In this case, the adjusting device 1 can be embodied
either as a positive gear mechanism or as a negative gear
mechanism, depending on the number of teeth of the two ring gears
3, 13. After the number of teeth of the ring gears 3, 13 has been
defined it is possible to make a negative gear mechanism from a
positive gear mechanism, and vice versa, by exchanging the two ring
gears 3, 13.
[0030] However, if the adjusting device 1 according to the
invention is to be configured for particularly high actuating
dynamics, the effective load torque of the camshaft 2 can be
decreased or increased by means of an actuating spring 17 according
to the FIGS. 4 to 6 in order to implement an optimum actuating
speed of the adjusting device 1 when the braking torque varies.
[0031] A plurality of possible arrangements of the actuating spring
17 is conceivable. FIG. 4 shows the actuating spring 17 between the
drive element (chain wheel) 3 and actuating element (brake) 5, FIG.
5 shows the actuating spring 17 between the drive element (chain
wheel) 3 and the output element (camshaft) 4 and FIG. 6 shows the
actuating spring 17 between the output element (camshaft) 4 and
actuating element (brake) 5.
[0032] If the unlimited actuating range of the adjusting device is
to be restricted for a specific application, it is possible to
provide a stop limiting the relative rotational movement between
for example the drive element 3 and the output element 4, for
example a positively locking device element. Such a stop may simply
be a projection 3' extending from the output element 3 into a
circumferential recess 4' formed in the output element 4 over a
certain angular range as indicated in FIG. 2.
* * * * *