U.S. patent application number 13/635832 was filed with the patent office on 2013-04-18 for method and device for operating an internal combustion engine in the event of a fault in a crankshaft sensor.
The applicant listed for this patent is Carsten Deringer, Ulrich-Michael Nefzer, Elmar Pietsch. Invention is credited to Carsten Deringer, Ulrich-Michael Nefzer, Elmar Pietsch.
Application Number | 20130092114 13/635832 |
Document ID | / |
Family ID | 43799737 |
Filed Date | 2013-04-18 |
United States Patent
Application |
20130092114 |
Kind Code |
A1 |
Pietsch; Elmar ; et
al. |
April 18, 2013 |
METHOD AND DEVICE FOR OPERATING AN INTERNAL COMBUSTION ENGINE IN
THE EVENT OF A FAULT IN A CRANKSHAFT SENSOR
Abstract
A method for operating an internal combustion engine in the
event of a fault in a crankshaft sensor is provided, the internal
combustion engine having at least two camshafts and a speed and/or
a position of the internal combustion engine being derived from a
signal taken from the camshaft. In order to improve the exhaust gas
performance of the internal combustion engine even in a crankshaft
emergency operating mode, only a first camshaft is used to
determine the speed and/or the position of the internal combustion
engine, while the second camshaft. is adjusted in its angle of
rotation in order to set a variable valve operating mechanism on
the intake and exhaust valves of the internal combustion engine
that are driven by the second camshaft.
Inventors: |
Pietsch; Elmar;
(Kornwestheim, DE) ; Nefzer; Ulrich-Michael;
(Waiblingen-Beinstein, DE) ; Deringer; Carsten;
(Aichwald, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Pietsch; Elmar
Nefzer; Ulrich-Michael
Deringer; Carsten |
Kornwestheim
Waiblingen-Beinstein
Aichwald |
|
DE
DE
DE |
|
|
Family ID: |
43799737 |
Appl. No.: |
13/635832 |
Filed: |
March 1, 2011 |
PCT Filed: |
March 1, 2011 |
PCT NO: |
PCT/EP2011/053026 |
371 Date: |
November 29, 2012 |
Current U.S.
Class: |
123/90.17 ;
123/90.1 |
Current CPC
Class: |
F01L 2001/34496
20130101; F01L 2800/11 20130101; F01L 1/34 20130101; F01L 2820/042
20130101; F01L 2800/12 20130101; F01L 2001/0537 20130101; F01L
1/344 20130101; F01L 2820/041 20130101 |
Class at
Publication: |
123/90.17 ;
123/90.1 |
International
Class: |
F01L 1/344 20060101
F01L001/344 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2010 |
DE |
10 2010 003 051.1 |
Claims
1-10. (canceled)
11. A method for operating an internal combustion engine having at
least two camshafts in the event of a fault in a crankshaft sensor,
comprising: determining at least one of a speed and a position of
the internal combustion engine based on a signal from only a first
camshaft; and adjusting an angle of rotation of a second camshaft
in order to set a variable valve operating mechanism on intake
valves and exhaust valves of the internal combustion engine which
are driven by the second camshaft.
12. The method as recited in claim 11, wherein the first camshaft
assumes a reference position with respect to a crankshaft driven by
the internal combustion engine and rotates in a specified
transmission ratio with respect to the crankshaft, the rotary
motion of the first camshaft being detected by a camshaft
sensor.
13. The method as recited in claim 12, wherein the first camshaft
which is in the reference position with respect to the crankshaft
at least one of selectively opens and closes the exhaust valves of
the internal combustion engine, and wherein the second camshaft
which has been adjusted at least one of selectively opens and
closes the intake valves of the internal combustion engine.
14. The method as recited in claim 12, wherein at least three
camshafts are provided, and wherein the respective angles of
rotation of the second and third camshafts are adjusted.
15. The method as recited in claim 14, wherein the respective
angles of rotation of the second and third camshafts are adjusted
as a function of at least one of the speed of rotation of the
internal combustion engine and the position of the internal
combustion engine detected by the camshaft sensor.
16. The method as recited in claim 15, wherein, in the adjustment
of the respective angles of rotation, the second and third camshaft
driven by the crankshaft are each shifted from a specified position
with respect to the crankshaft so as to change the control times of
at least one of the intake and exhaust valves of the internal
combustion engine.
17. The method as recited in claim 13, wherein the adjustment of
the second camshaft occurs between two permanently defined angles
of rotation within an adjustment range of the second camshaft.
18. The method as recited in claim 17, wherein the adjustment of
the second camshaft occurs in a step-less manner within the
adjustment range of the camshaft.
19. A control device for operating an internal combustion engine
having at least two camshafts in the event of a fault in a
crankshaft sensor, comprising: means for determining at least one
of a speed and a position of the internal combustion engine based
on a signal from only a first camshaft; and means for adjusting an
angle of rotation of a second camshaft in order to set a variable
valve operating mechanism on intake valves and exhaust valves of
the internal combustion engine which are driven by the second
camshaft.
20. The device as recited in claim 19, wherein: a control unit
controls respective rotary motions of the first and second
camshafts; the control unit sets the first camshaft in a reference
position with respect to the crankshaft; the control unit is
connected to a camshaft sensor which detects the rotary motion of
the first camshaft; the control unit determines the at least one of
a speed and a position of the internal combustion engine based on
an output signal of the camshaft sensor; and the control unit
controls, as a function of the determined speed of the internal
combustion engine, an adjusting device connected to the second
camshaft for adjusting the angle of rotation of the second camshaft
from an original position.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method for operating an
internal combustion engine in the event of a fault in a crankshaft
sensor, the internal combustion engine having at least two
camshafts and a rotational speed and/or a position of the internal
combustion engine being derived from a signal taken from the
camshaft, and to a device for implementing the method.
[0003] 2. Description of the Related Art
[0004] In today's motor vehicles it is important to determine the
speed of the internal combustion engine precisely since this
parameter enters into numerous open-loop and closed-loop control
processes of the motor vehicle. Usually, this speed is derived from
the rotational speed of a crankshaft, which is driven by the
mechanical energy generated in the combustion process. For this
purpose, the crankshaft is scanned by a crankshaft sensor, which
detects the speed and position of the crankshaft. The signal is
provided by a suitable sensor, which is evaluated in a control unit
as a measure for the speed and/or the position of the internal
combustion engine. In the process, the injection and ignition point
of the internal combustion engine is determined.
[0005] In the event of a failure or a fault of the crankshaft
sensor signal, the control unit switches to a crankshaft emergency
operating mode, in which the position of the internal combustion
engine is determined from the position of a camshaft, which is
likewise driven by the crankshaft. A precondition for this
crankshaft emergency operating mode is that the camshafts must be
fixed in a certain position with respect to the crankshaft so that
it is possible to determine the position of the internal combustion
engine precisely. The camshafts are thus no longer available for a
camshaft adjustment in the various operating ranges of the internal
combustion engine, which results in a deterioration of the exhaust
gas performance of the internal combustion engine.
BRIEF SUMMARY OF THE INVENTION
[0006] The present invention is thus based on the objective of
indicating a method and a device for operating an internal
combustion engine in the event of a fault or the failure of a
crankshaft sensor, in which the exhaust gas performance of the
internal combustion engine is improved even in a crankshaft
emergency operating mode.
[0007] According to the present invention, the objective is
achieved by the fact that only a first camshaft is used to
determine the speed and/or the position of the internal combustion
engine, while the second camshaft is adjusted in its angle of
rotation in order to set a variable valve operating mechanism on
the intake and exhaust valves of the internal combustion engine
that are driven by the second camshaft. This has the advantage that
the speed and/or position of the internal combustion engine
determined during the crankshaft emergency operating mode may be
determined reliably and precisely by a single camshaft. In
addition, variable valve opening times continue to be set with the
aid of the second camshaft. Turning the second camshaft out of its
original position improves the exhaust gas performance of the
internal combustion engine, the positive influence on the exhaust
gas performance remaining in effect even during the crankshaft
emergency operating mode. The adjustment of the valve opening times
allows for an increase in the efficiency of the internal combustion
engine, which is shows its effect in a performance and torque gain
or a reduction in fuel consumption.
[0008] Advantageously, the first camshaft assumes a reference
position with respect to a crankshaft driven by the internal
combustion engine and rotates in a specified transmission ratio
with respect to the crankshaft, the rotary motion of the camshaft
being detected by a camshaft sensor. Setting the reference position
effects a fixed and unambiguous association of the motion of the
camshaft in relation to the motion of the crankshaft such that this
may be used to determine the position of the internal combustion
engine reliably.
[0009] In one variant, the first camshaft situated in the reference
position with respect to the crankshaft opens and/or closes the
exhaust valves of the internal combustion engine, while the second
camshaft that has been turned out of its original position opens
and/or closes the intake valves of the internal combustion engine.
In a camshaft adjustment, the intake and exhaust valve control
times are changed as a function of the rotational speed in order to
achieve the most efficient cylinder charge in all speed ranges. The
desired effect of the exhaust gas reduction may already be achieved
solely by turning the camshaft that controls the intake valves out
of its original position. One camshaft thus suffices for setting
the variable valve operating mechanism.
[0010] In one development, when more than two camshafts are used,
only the first camshaft is held in the reference position with
respect to the crankshaft, while the remaining camshafts are
adjusted in their angle of rotation. Since, with the exception of
one camshaft, all other camshafts are available for actuating the
intake and/or exhaust valves, it becomes possible to achieve an
optimized setting of the variable valve operating mechanism, which
is reflected in an improved exhaust gas performance of the internal
combustion engine in the crankshaft emergency operating mode. When
using multiple camshafts, an adjustment is made not only to an
intake camshaft, but also to an exhaust camshaft, which controls
the exhaust valves of the internal combustion engine. Such an
adjustment of the exhaust camshaft additionally allows for a
variation of the internal exhaust gas recirculation in the form of
reducing the nitrogen oxide emission. In addition, the simultaneous
adjustment of the intake and exhaust camshafts increases the
possibility that the opening times of the intake and exhaust valves
will overlap, which results in an even better optimization of the
gas streams in the internal combustion engine.
[0011] Furthermore, the camshafts are adjusted in their angle of
rotation as a function of the speed of rotation and/or the position
of the internal combustion engine detected by the camshaft sensor.
Since the adjustment of the camshaft effects a change in the angle
of rotation in relation to the crankshaft and since this adjustment
depends on the ascertained speed of the internal combustion engine,
in the event of a crankshaft emergency operating mode, the angle of
rotation is ascertained as a function of the speed determined with
the aid of the first camshaft.
[0012] In one development, in the adjustment of its angle of
rotation, the camshaft driven by the crankshaft is shifted from its
specified position with respect to the crankshaft so as to change
the control times of the intake or exhaust valves of the internal
combustion engine. This adjustment occurs simply in a mechanical
manner since a hydraulic phase adjuster is situated between the
crankshaft and the camshaft, which is situated at the end of each
camshaft for transmitting force.
[0013] In another specific embodiment, the adjustment of the second
camshaft occurs between two permanently defined angles of rotation
within an adjustment range of the second camshaft. This reduces the
control effort required for the phase adjuster. The adjustment
range typically amounts to 60.degree. of the crankshaft.
[0014] Alternatively, the adjustment of the second camshaft occurs
steplessly within the adjustment range of the camshaft. Although it
requires an elaborate control process, the stepless adjustment of
the camshaft makes it possible to react comfortably to various
operating states of the internal combustion engine and thus to
adjust the exhaust gas performance of the internal combustion
engine advantageously.
[0015] A further development of the present invention relates to a
device for operating an internal combustion engine in the event of
a fault in a crankshaft sensor, the internal combustion engine
having at least two adjustable camshafts and a rotational speed
and/or the position of the internal combustion engine being
ascertained from a signal taken from the camshaft rotation. In
order to improve the exhaust gas performance of the internal
combustion engine even in a crankshaft emergency operating mode,
only a first camshaft is used to determine the speed of the
internal combustion engine, while means are provided for adjusting
the second camshaft in its angle of rotation in order to set a
variable valve operating mechanism on the intake or exhaust valves
of the internal combustion engine that are driven by the second
camshaft. This system brings about an improvement of the exhaust
gas performance of the internal combustion engine even in the
crankshaft emergency operating mode.
[0016] In one development, the first and the second camshaft are
controlled in their respective rotary motion by a control unit, the
control unit, which sets the first camshaft in a reference position
with respect to the crankshaft, is connected to a camshaft sensor
that detects the rotary motion of the first camshaft, from which
the control unit determines the speed and/or the position of the
internal combustion engine and as a function of the ascertained
speed or position of the internal combustion engine controls an
adjusting device connected to the second camshaft for turning the
angle of rotation of the second camshaft out of its original
position. In addition to determining precisely the position and/or
speed of the internal combustion engine using only one camshaft,
variable valve opening times are set using the second camshaft even
in a crankshaft emergency operating mode. Turning the second
camshaft out of its original position improves the exhaust gas
performance of the internal combustion engine by optimizing the
ratio of fresh air and fuel, the positive influence on the exhaust
gas performance remaining in effect even in the crankshaft
emergency operating mode. A suitable actuating mechanism is used as
an actuator, which operates electrically or hydraulically and
performs this adjustment simply in a mechanical manner, and which
for transmitting force is situated at the end of each camshaft.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 shows the basic structure of a V-shaped internal
combustion engine having 4 camshafts.
[0018] FIG. 2 shows a basic representation for situating a
crankshaft sensor and a camshaft sensor in a V-shaped internal
combustion engine as shown in FIG. 1.
[0019] FIG. 3 shows a camshaft including a camshaft adjuster.
DETAILED DESCRIPTION OF THE INVENTION
[0020] Identical features are indicated by the same reference
symbols.
[0021] FIG. 1 shows a basic representation of an internal
combustion engine 1 in the shape of a V. In this instance,
cylinders 2 of internal combustion engine 1 are arranged in a
v-shape on two planes 3, 4, a crankshaft 5 being situated at the
intersection of the two planes 3, 4. Each plane 3, 4 is typically
called a bank. Each cylinder 2 is equipped with one or more intake
valves 6 and one exhaust valve 7. Fresh air and fuel are conveyed
through intake valve 6 into the respective cylinder 2 of internal
combustion engine 1, while the combustion products of cylinder 2 in
the form of exhaust gas are discharged from internal combustion
engine 1 via exhaust valve 7. Intake valves 6 of first plane 3 of
cylinders 2 are connected to a first camshaft 8, while exhaust
valves 7 of first plane 3 are operated by a second camshaft 10.
Analogously, intake valves of second plane 4 of cylinders 2 connect
to a third camshaft 9, and exhaust valves 7 of second plane 4 work
together with a fourth camshaft 11. Each camshaft 8, 9, 10, 11 has
an eccentric cam (protrusion) for each valve 2, which cam is not
shown. Since the camshaft rotates about its own axis, this rotary
motion being converted into a short longitudinal movement by the
cam, the intake or exhaust valve 6, 7 associated with the cam is
opened. As the cam continues to rotate, valve 6, 7 is closed again
by a valve spring 19 (FIG. 3).
[0022] A speed sensor wheel 12 in the form of a toothed wheel is
situated at one end of crankshaft 5, which is shown in FIG. 2 next
to the sketched internal combustion engine 1. Speed sensor wheel 12
has a defined number of teeth 13 made of iron or steel, which are
arranged continuously on the circumference of speed sensor wheel 12
and are interrupted by one gap or multiple gaps 14. A crankshaft
sensor 15 is situated across from speed sensor wheel 12, which
scans the teeth and the gap(s) 14 in that a magnetic field, which
crankshaft sensor 15 spans using a magnet, is interrupted by teeth
13, whereby an alternating voltage is induced in a coil of
crankshaft sensor 15, which the latter transmits to a control unit
16 for analysis. Gap 14 of crankshaft sensor wheel 12 signals that
crankshaft 5 has completed one turn, which indicates the end of a
working cycle of a cylinder 2.
[0023] A camshaft sensor wheel 17 is situated on each camshaft 8,
9, 10, 11, which is shown in FIG. 2 only in the example of camshaft
9. This camshaft sensor wheel 17 also has teeth that are
interrupted by gaps. Camshaft sensor wheel 17, however, is not
subdivided in as differentiated a manner as crankshaft sensor wheel
12, which has 60 -2 teeth, while camshaft sensor wheel 17 in the
present example has only 3 teeth.
[0024] Camshafts 8, 9, 10, 11 are driven by crankshaft 5 via a
transmission (not shown), the transmission having a transmission
ratio such that camshafts 8, 9, 10, 11 only rotate half as fast as
crankshaft 5.
[0025] In order to vary the control time of the intake and exhaust
valves by camshaft 8, 9, 10, 11, the respective camshaft 8, 9, 10,
11 is turned by a certain angle out of its original position with
respect to crankshaft 5. The adjustment of camshaft 8, 9, 10, 11
occurs as a function of the rotational speed of internal combustion
engine 1 and means that the opening of the intake or exhaust valve
6, 7 is changed with respect to the crank angle of crankshaft 5.
For this purpose, a hydraulic camshaft adjuster 20 is used, for
example, as is shown in FIG. 3 in connection with camshaft 9. As
already explained, a toothed wheel 21 of the transmission turns
camshaft 9. Camshaft adjuster 20, which is likewise connected to
control unit 16 and is controlled by the latter, shifts the
position of camshaft 9 with respect to toothed wheel 21 such that
valve 2 is closed earlier or later, whereby an increase in the
efficiency of internal combustion engine 1 is achieved.
[0026] In particular overlaps in the opening times of the intake
and exhaust valves fundamentally influence the characteristics of
internal combustion engine 1. An internal combustion engine 1
having little overlap has a rather high torque at low rotational
speeds. By great overlaps it is possible to achieve a higher
maximum performance of internal combustion engine 1.
[0027] If it is now determined that crankshaft sensor 5, by which
not only the speed of internal combustion engine 1 is determined,
but also its position, provides an output signal with high
interference or no signal at all, then control unit 16 will switch
into a so-called crankshaft emergency operating mode. In this
crankshaft emergency operating mode, one of the four camshafts 8,
9, 10, 11 of internal combustion engine 1 is brought into a
reference position with respect to crankshaft 5. In the present
example, this is camshaft 11, which controls exhaust valves 7 of
second plane 4 of cylinders 2. This reference position creates a
fixed relationship between the motion of crankshaft 5 and of
camshaft 11, whereby the engine position may be determined in a
defined manner. A camshaft sensor wheel 17 is situated at one end
on this camshaft 11 as well, which has a camshaft sensor 18 across
from it (FIG. 2). The magnetic field of the camshaft sensor 15,
which is developed as a Hall sensor, is modified by the individual
teeth of camshaft sensor wheel 17, which is transmitted as a signal
to control unit 16, which derives the speed and position of
internal combustion engine 1 from this signal.
[0028] The remaining three camshafts 8, 9, 10, which are not needed
for determining the position and speed of internal combustion
engine 1, are available for adjustment, whereby the exhaust gas
performance of internal combustion engine 1 is improved by
controlling the two intake camshafts 8, 9 and the remaining exhaust
camshaft 10. Because of the fact that multiple camshafts are
available for adjustment in the already described manner, intake
and exhaust control times may be set that bring about a most
efficient cylinder charge in all speed ranges of internal
combustion engine 1.
* * * * *