U.S. patent application number 11/326529 was filed with the patent office on 2006-06-01 for camshaft adjuster with an electrical drive.
This patent application is currently assigned to INA-Schaeffler KG. Invention is credited to Jens Schafer, Martin Steigerwald.
Application Number | 20060112921 11/326529 |
Document ID | / |
Family ID | 29265179 |
Filed Date | 2006-06-01 |
United States Patent
Application |
20060112921 |
Kind Code |
A1 |
Schafer; Jens ; et
al. |
June 1, 2006 |
Camshaft adjuster with an electrical drive
Abstract
The invention relates to a device for releasably connecting and
adjusting the positions between a crankshaft and a cam shaft of an
internal combustion engine, which includes a setting gear (1)
configured as a three-shaft gear, which has a drive shaft (4)
connected to the crankshaft, an output shaft (5) connected to the
camshaft, and an adjusting shaft connected to an electric adjusting
motor (2). A stationary transmission ratio i.sub.o, which has a
base or emergency running position, is present between the drive
and output shafts when the adjusting shaft (6) is idle, the
magnitude of the gear transmission ratio determining the gear type
(positive or negative) and the direction of adjustment of the
camshaft (3). Functional safety of the device is improved due to
the fact that the base or emergency running position of the
camshaft (3) can be reached and maintained in case of an outage or
failure of the adjusting motor (2) and/or the control thereof be a
slow-down or arresting of the adjusting shaft (6), simultaneous
rotation of the drive shaft (4), and an appropriate gear
transmission ratio.
Inventors: |
Schafer; Jens;
(Herzogenaurach, DE) ; Steigerwald; Martin;
(Erlangen, DE) |
Correspondence
Address: |
VOLPE AND KOENIG, P.C.
UNITED PLAZA, SUITE 1600
30 SOUTH 17TH STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
INA-Schaeffler KG
Herzogenaurach
DE
91074
|
Family ID: |
29265179 |
Appl. No.: |
11/326529 |
Filed: |
January 5, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10979487 |
Nov 2, 2004 |
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11326529 |
Jan 5, 2006 |
|
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PCT/EP03/02788 |
Mar 18, 2003 |
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10979487 |
Nov 2, 2004 |
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Current U.S.
Class: |
123/90.31 ;
123/90.17 |
Current CPC
Class: |
F01L 1/024 20130101;
F01L 1/352 20130101; F01L 1/344 20130101; F01L 1/34 20130101 |
Class at
Publication: |
123/090.31 ;
123/090.17 |
International
Class: |
F01L 1/34 20060101
F01L001/34; F01L 1/02 20060101 F01L001/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 10, 2002 |
DE |
102 20 687.2 |
Claims
1. A device for releasably connecting and adjusting a camshaft (3,
3') and a crankshaft of an internal combustion engine, comprising
an adjusting gear (1, 1') formed as a three shaft transmission,
which has a drive shaft (4, 4') connected with the crankshaft, an
output shaft (5, 5') connected with the camshaft, and an adjusting
shaft (6, 6') connected with an electric adjusting motor (2, 2'), a
gear transmission ratio i.sub.o is defined between the drive shaft
and the output shaft (4, 4'; 5, 5') when the adjusting shaft (6,
6') is at rest, and a magnitude of the gear transmission ratio is
determined by a gear type and a direction of setting of camshaft
(3, 3'), which has a base or emergency running position, wherein
upon a failure of the adjusting motor (2, 2') or a controlling
system, the base or emergency running position of camshaft (3, 3')
can be reached and maintained by one of braking or setting the
adjusting shaft (6, 6'), and rotation of drive shaft (4, 4'), as
well as the gear transmission ratio i.sub.o.
2. The device according to claim 1, for a late adjustment of
camshaft (3, 3') a minus gear with i.sub.o<0 or a plus gear with
i.sub.o>1 is provided, and for an early adjustment of camshaft
(3, 3') a plus gear with 0<i.sub.o<1 is provided.
3. The device according to claim 2, wherein the adjusting motor (2)
includes a rotor (8) and a stator fixedly connected to a cylinder
head, the rotor (8) includes a permanent magnet, and for a power
free setting of the adjusting shaft (6) a holding torque of the
adjusting motor is utilized.
4. An adjustment device for an engine including a camshaft and a
crankshaft, the device comprising: an adjusting shaft; a drive
shaft for connection to the crankshaft; an output shaft for
connection to the camshaft; and a gear transmission, connected to
the output shaft, the drive shaft and the adjusting shaft, the gear
transmission configured to rotate the output shaft and the
adjusting shaft at a predetermined rate in response to a given
input from the drive shaft, wherein braking the adjusting shaft
results in at least one of increasing and decreasing a rotation
speed of the output shaft relative to a rotation speed of the drive
shaft.
5. The adjustment device of claim 4, further comprising an electric
motor connected to the adjusting shaft for braking the adjusting
shaft.
6. The adjustment device of claim 4, further comprising a
mechanical brake connected to the adjusting shaft for braking the
adjusting shaft.
7. The adjustment device of claim 4, wherein the gear transmission
includes a gear transmission ratio i.sub.o associated with the
adjusting shaft which is greater than 1, wherein when the
adjustment shaft is braked, the output shaft rotational speed is
increased relative to the drive shaft rotational speed, whereby the
camshaft rotational speed is increased relative to the crankshaft
rotational speed.
8. The adjustment device of claim 4, wherein the gear transmission
includes a gear transmission ration i.sub.o which is less than 1,
wherein when the adjustment shaft is braked, the output shaft
rotational speed is decreased relative to the drive shaft
rotational speed, whereby the camshaft rotational speed is
decreased relative to the crankshaft rotational speed.
9. An engine comprising: a camshaft; a crankshaft; an adjusting
shaft; a drive shaft connected to the crankshaft; an output shaft
connected to the camshaft; and a gear transmission, connected to
the output shaft, the drive shaft and the adjusting shaft, the gear
transmission configured to rotate the output shaft and the
adjusting shaft at a predetermined rate in response to a given
input from the drive shaft, wherein braking the adjusting shaft
results in at least one of increasing and decreasing a rotation
speed of the output shaft relative to a rotation speed of the drive
shaft.
10. The engine of claim 9, further comprising an electric motor
connected to the adjusting shaft for braking the adjusting
shaft.
11. The engine of claim 9, further comprising a mechanical brake
connected to the adjusting shaft for braking the adjusting
shaft.
12. The engine of claim 9, wherein the gear transmission includes a
gear transmission ratio i.sub.o associated with the adjusting shaft
which is greater than 1, wherein when the adjustment shaft is
braked, the output shaft rotational speed is increased relative to
the drive shaft rotational speed, whereby the camshaft rotational
speed is increased relative to the crankshaft rotational speed.
13. The engine of claim 9, wherein the gear transmission includes a
gear transmission ration i.sub.o which is less than 1, wherein when
the adjustment shaft is braked, the output shaft rotational speed
is decreased relative to the drive shaft rotational speed, whereby
the camshaft rotational speed is decreased relative to the
crankshaft rotational speed.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. application Ser.
No. 10/979,487, filed Nov. 2, 2004, which is a continuation of
PCT/EP03/02788, filed Mar. 18, 2003, which are incorporated herein
by reference as if fully set forth.
BACKGROUND
[0002] The invention relates to a device for releasably connecting
and adjusting the camshaft and the crankshaft of an internal
combustion engine, having an adjusting gear created as a three
shaft transmission, which has a drive shaft connected with the
crankshaft, an output shaft connected with the camshaft, and an
adjusting shaft connected with an electric adjusting motor, in
which there is a gear transmission ratio i.sub.o between the drive
shaft and the output shaft when the adjusting shaft is at rest, and
the magnitude of the gear transmission ratio is determined by the
gear type and the direction of setting of the camshaft, which has a
base or emergency running position.
[0003] To ensure a secure starting in motion of an internal
combustion engine with a hydraulic and electrical adjusting system
for the camshaft, the camshaft must find itself in a so-called base
or emergency running position. This position usually lies with the
inlet camshafts in a "late", and the outlet camshafts in "early"
positions. In normally functioning vehicles, the camshaft is set to
the base position by turning off the motor and then fixing and
locking it.
[0004] A conventional, hydraulically activated rotating piston
adjuster, in the form of pivoting vanes or segment wings has a
locking device. This unit fixes the hydraulic adjuster in its base
position until it collects enough oil pressure to be able to set
the camshaft. If an engine stall occurs, the camshaft can be in an
undefined position outside the base position.
[0005] For hydraulic camshaft adjusting systems with a base
position that is "late", during the next starting of the internal
combustion engine, when the oil pressure is not sufficient because
of the friction moment of the camshaft, which works in the opposite
direction, the camshaft is set automatically to the late base
position. If the base position is "early", when the oil pressure is
not sufficient, the camshaft must be adjusted against the friction
moment of camshaft to the early base position. This happens mostly
through the use of a compensating spring, which creates the same
but opposite moment to the camshaft friction moment.
[0006] These methods, common for hydraulically driven camshaft
adjusters to achieve the base position after stalling an internal
combustion engine, cannot be applied for electrically driven
camshaft adjusters. They are also not necessary as long as the
system of adjusting the motor is intact and can adjust the camshaft
to the base position when an internal combustion engine is at rest
or is started again. But in case of electric adjusting systems, the
adjusting motor and/or its controlling system can fail and
therewith impede the reaching of the base position.
[0007] There is a device described in DE 41 10 195 A1 for
releasably connecting and adjusting the camshaft and the crankshaft
of an internal combustion engine with an adjusting gear created as
a three shaft transmission, which has a drive shaft connected with
the crankshaft, a drive shaft connected with the camshaft, and an
adjusting shaft connected with an electric adjusting motor, whereas
there is a gear transmission ratio i.sub.o between the drive shaft
and the output shaft when the adjusting shaft is at rest, and
magnitude of the gear transmission ratio is determined by the type
of gear (minus or plus gear) and the adjusting direction of
camshafts, that have a base or emergency running position.
[0008] In this adjusting device the goal is an easy working and
precise adjusting of the camshaft position. In order to maintain at
least a basic functioning of the internal combustion engine, when
the adjusting motor's system fails, it is designed as a limitation
of the setting angle. Nevertheless, there is no indication in such
a case when the base or emergency running position is reached.
SUMMARY
[0009] The invention is directed to the objective of creating an
electrical camshaft adjuster, in which the camshaft can be adjusted
to the base position even in the case of a failure of the adjusting
motor and/or its controlling system. The object is solved according
to the invention in that when the adjusting motor or its
controlling system fail, the base or emergency running position of
camshaft can be reached and maintained by means of braking or
setting the adjusting shaft and rotation of drive shaft, as well as
through the us of a suitable gear transmission ratio i.sub.o. After
having slowed down or fixed the adjusting shaft, the camshaft will
be adjusted to the base or emergency running position by means of
turning the drive shaft in low idle speed of the internal
combustion engine or--if it stalled--during re-starting, even if
the system of the adjusting motor has failed. In this position the
vehicle can be started and operated with some limitations so that a
repair shop can be reached. A precondition here is a suitable gear
transmission ratio i.sub.o, by means of which the desired gear type
(plus or minus gear) and the adjusting direction (late or early)
are determined.
[0010] When selecting the setting gear, the minus and plus gears
come into question. Minus gears have a gear transmission ratio
smaller than 0, whereas plus gears have a ratio higher than 0. When
the gear transmission ratio i.sub.o is positive, the drive shaft
and output shaft have the same turning direction, when the gear
transmission ratio i.sub.o is negative, they have an opposite
turning direction compared with a standing adjusting shaft and
components connected therewith.
[0011] When in the case of a minus gear on the adjusting shaft, the
drive shaft rotates clockwise so the output shaft and the camshaft
connected with it rotate counter-clockwise, which corresponds to a
late adjusting.
[0012] When in the case of a plus gear with a gear transmission
ratio i.sub.o>1 for the adjusting shaft, when the drive shaft is
turned clockwise, the output drive rotates slower than the drive
shaft, i.e. counter-clockwise and therewith in direction of late
adjusting.
[0013] When in the case of a plus gear with a gear transmission
ratio 0<i.sub.o<1 on the adjusting shaft and the drive shaft
is rotating clockwise, the output drive rotates faster than the
drive shaft, i.e. clockwise and therewith in the direction of early
adjusting.
[0014] These relations are applicable to all setting gears in
question. In summary, when an adjusting motor fails, in order to
achieve a late base position it is necessary to set the adjusting
shaft with a minus gear to i.sub.o<0 or a plus gear with
i.sub.o>1, and to achieve an early base position it is necessary
to set the adjusting shaft with a plus gear with
0<i.sub.o<1.
[0015] It is advantageous if the adjusting motor has a permanent
magnet rotor with a passive holding torque that builds to a maximum
in both directions of rotation from a middle position, and then
again goes down. The holding torque of the adjusting motor,
increased by the changed friction moment of setting gear, must have
only 60%-100% of the changed, maximum, dynamic camshaft torque,
that reacts upon the adjusting shaft, because the energy content of
the peaks of camshaft torque is small, and the necessary holding
torque is more determined by the middle camshaft torque. The usage
of a permanent magnet rotor compared with a permanent magnet stator
has this advantage that power must be fed only into the stator
fixed to the cylinder head.
[0016] In the case that the holding torque is not sufficient in an
adjusting motor with a permanent magnet, and in the case of
separately excited direct current motors without holding torque, to
set the adjusting shift, an additional braking torque is used. This
is created with a cylinder head brake, preferably mechanical, or an
eddy current brake. The brakes are automatically set in motion with
the lowest idle speed of the internal combustion engine, and
automatically loosened with a working adjusting motor. This way the
camshafts are always set in the base position before the internal
combustion engine is stopped. If this is not possible because the
motor was stalled, it will be made up for with the next start.
[0017] It was also advantageous when the adjusting velocity of the
camshaft, because of the chosen gear transmission ratio i.sub.o
with a standing adjusting shaft and low idle speed of the internal
combustion engine is set preferentially between 30.degree. and
60.degree. of a cam angle per second. Here it is not important if
the adjusting motor, when the camshaft is put back into the base
position, is set into one or two directions of rotation.
[0018] It is necessary that in the regular position of camshaft
that the drive shaft, the output shaft, and the adjusting shaft for
the setting gear turn with the same number of revolutions. In this
way there is no relative movement between the crankshaft and the
camshafts.
[0019] For adjusting gears, for example, known eccentric gear or
shaft gear (plus gear) or wobble gear or two planet gear (minus or
plus gear) can be used, and the adjusting motors are designed as
conventional brushless motors with a permanent magnet rotor or as
separately excited direct current motors with brushes.
BRIEF DESCRIPTION OF DRAWINGS
[0020] Further features of the invention will be understood from
the following description and drawings, in which an exemplary
embodiment of the invention is schematically presented. In the
drawings:
[0021] FIG. 1 is a view of a setting gear with an adjusting motor,
whose stator is connected with cylinder head;
[0022] FIG. 2 is a view of a different setting gear with a
different adjusting motor which rotates with the stator.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] In FIGS. 1 and 2, setting gears 1, 1' with electrical
adjusting motors 2, 2' are shown, which are used to adjust the
position of the rotation angle between a crankshaft (not shown) and
camshaft 3, 3' of an internal combustion engine.
[0024] The setting gear 1, 1' is configured as a three shaft
transmission, which has a drive shaft 4, 4', an output shaft 5, 5',
and an adjusting shaft 6, 6'.
[0025] The drive shaft 4, 4' is fixedly connected with a drive gear
7, 7', and through that is connected with the crankshaft by means
of a not shown gearwheel, or a tooth belt, or a toothed chain.
[0026] The output shaft 5, 5' is fixedly connected with the
camshaft 3, 3', and the adjusting shaft 6, 6' is connected with the
rotor 8, 8' of the adjusting motor 2, 2'.
[0027] The stator 9 of the adjusting motor 2 is fixedly connected
with the cylinder head 10 and is at rest. The stator 9' of the
adjusting motor 2' is fixedly connected with the drive gear 7' and
rotates with the setting gear with half of the crankshaft rotation
speed.
[0028] The camshaft 3, 3' has a base or emergency running position,
which must be achieved for a secure starting and a restricted
operation. This is possible without problems with an intact
adjusting motor 2, 2' even after the internal combustion engine
stalls, because the adjusting motor 2, 2' repositions the camshaft
3, 3' at stalling of the internal combustion engine or during a new
starting. But a new starting must be possible even with a failure
of the adjusting motor 2, 2' in order to reach a repair shop at
least.
[0029] The adjusting gears 1, 1' and their gear transmission ratio
i.sub.o are constructed in such a way, that by means of a mere
setting of adjusting shafts 6, 6' the camshafts 3, 3', when
starting, come to their base position and therewith the internal
combustion engine can still be started.
[0030] When the adjusting shaft 6, 6' remains at rest and the drive
shaft turns to the right 4, 4' the following must be explained
about i.sub.o:
[0031] When i.sub.o<0 there is a minus gear with a late advance;
when 0<i.sub.o<1, there is a plus gear with an early advance,
and when i.sub.o>1, there is a plus gear with a late
advance.
[0032] Setting of an adjusting shaft can happen by means of an
unpowered adjusting motor 2 with a permanent magnet rotor 8 or
permanent magnet stator 9. The adjusting motor 2 exhibits a holding
torque that grows from a middle position in both directions of
rotation until a maximum is reached, and then drops down again. The
holding torque is the maximum torque with which a non-excited
adjusting motor can be statically loaded, without having caused a
non-constant but continual rotation.
[0033] The holding torque is strengthened by the changed friction
moment of setting gear 1 to the rest moment, which should lie
between 60% and 100% of the changed maximum, dynamic camshaft
moment at low idle speed of the internal combustion engine.
[0034] If the rest moment of the unpowered adjusting motor 2 is not
sufficient for setting the adjusting shaft, an additional brake
moment will be provided by a mechanical or electric brake connected
to the cylinder head. This acts like the rest moment in both
directions of rotation of the adjusting shaft 6.
[0035] After the internal combustion engine is stalled or the
adjusting motor 2 has failed, the camshaft 3 can find itself in an
undefined position. By means of setting or braking of the adjusting
shaft 6, the camshaft 3 is set to its base position during the
subsequent starting by means of the rotational movement of drive
shaft 4 caused by the starter, so that a start is possible.
[0036] Since the stator 9' of adjusting motor 2' (see FIG. 2)
rotates with its rotor 8', a setting of adjusting shaft 6' through
the holding torque active between stator 9' and rotor 6' is not
possible. In this case the adjusting shaft 6' can be stopped only
with a mechanical or electric brake 11' connected to the cylinder
head. With this, after the internal combustion engine has stalled
or the adjusting motor 2' has failed, it is possible, at the latest
when the next time motor is set in motion, to set the camshaft 3'
to its base position and make it possible to start the motor.
[0037] When the adjusting motors 2, 2' have high temperatures, the
mechanical or electrical braking of adjusting shafts 6, 6' is also
used for thermal relief of the adjusting motors 2, 2'.
LIST OF REFERENCE NUMBERS
[0038] 1 Setting gear [0039] 1' Setting gear [0040] 2 Electric
adjusting motor [0041] 2' Electric adjusting motor [0042] 3
Camshaft [0043] 3' Camshaft [0044] 4 Drive shaft [0045] 4' Drive
shaft [0046] 5 Output shaft [0047] 5' Output shaft [0048] 6
Adjusting shaft [0049] 6' Adjusting shaft [0050] 7 Drive wheel
[0051] 7' Drive wheel [0052] 8 Rotor [0053] 8' Rotor [0054] 9
Stator [0055] 9' Stator [0056] 10 Cylinder head [0057] 10' Cylinder
head [0058] 11 Brake with cylinder head [0059] 11' Brake with
cylinder head
* * * * *