Reverse-rotation robust synchronization method

Patent metadata

Field	Value
Publication number	US-11313298-B2
Application number	US-201917280776-A
Country	US
Kind code	B2
Filing date	Sep 27, 2019
Priority date	Sep 27, 2018
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

Disclosed is a method for synchronizing an internal combustion engine including at least one camshaft, on which a target is mounted, a position sensor for sensing the position of the camshaft and a processing unit, the method transmitting a synchronization or synchronization fault signal as a function of the determined direction of rotation of the target.

First claim

The invention claimed is:

1. A method for synchronizing an internal combustion engine comprising:
at least one camshaft ( 91 ), on which a target ( 1 ) is mounted in the form of a toothed wheel, each tooth comprising a rising edge and a falling edge, the wheel having rotational asymmetry;
a position sensor ( 2 ) for sensing the position of the camshaft, adapted to detect each rising or falling edge of a tooth of the target; and
a unit ( 21 ) for processing data generated by the sensor ( 2 ), comprising a memory ( 23 ), in which, for each edge of each tooth of the target, a theoretical signature of the edge is stored considering a forward rotation of the target, and a theoretical signature of the edge is stored considering a reverse rotation of the target, each theoretical signature being associated with a range of tolerance values;

the synchronization method being implemented by the processing unit ( 21 ) and comprising the implementation of the following steps:
for each detected tooth edge:
implementing a method ( 100 ) for identifying the detected edge considering a forward rotation of the target;
implementing a method ( 100 ) for identifying the detected edge considering a reverse rotation of the target;

the implementation of a method ( 100 ) for identifying an edge detected for a direction of rotation comprising:
computing ( 110 ) a time signature of the detected edge; and
comparing ( 120 ) the time signature of the detected edge with the ranges of tolerance values of a set of theoretical signatures of edges of the target of the same rising or falling type as the detected edge, corresponding to the direction of rotation of the target;
determining a direction of rotation of the target ( 232 ); and
transmitting a synchronization or synchronization fault signal as a function of the direction of rotation of the determined target.

2. The synchronization method as claimed in claim 1 , wherein, if the detected edge is determined to be corresponding to an edge of the target in forward rotation, and to be corresponding to an edge of the target in reverse rotation, and if the time signature of the detected edge is within the range of tolerance values of a theoretical signature of a single edge ( 140 ), the detected edge is identified as the edge corresponding to the theoretical signature, and if the time signature of the detected edge is within the range of tolerance values of a theoretical signature of more than one candidate edge ( 150 ), the steps of computing a time signature ( 110 ) and of comparing ( 120 ) the time signature with the following edge are repeated, the comparison ( 120 ) only being implemented with the theoretical signatures of the edges following the candidate edges.

3. The synchronization method as claimed in claim 2 , wherein the time signature of a detected edge is defined, for each edge detected from the third, by:

τ
R

⁡

(
n
)

=

T
n

T

n
-
1

where n is the index of a detected edge and T n is the duration between the index edge n−1 and the index edge n; and
the theoretical signature of an edge with which the time signature of a detected edge is compared is defined by:

τ
th

⁡

(
n
)

=

α
n

α

n
-
1

.

4. The synchronization method as claimed in claim 2 , wherein the time signature of a detected edge is defined by:
for each edge detected from the fifth, by:

τ
R

⁡

(
n
)

=

T
n

+

T

n
-
3

T

n
-
1

+

T

n
-
2

where n is the index of a detected edge and T n is the duration between the index edge n−1 and the index edge n; and
the theoretical signature of an edge with which the time signature of a detected edge is compared is defined by:

τ
th

⁡

(
n
)

=

α
n

+

α

n
-
3

α

n
-
1

+

α

n
-
2

where α n is the angle between the index edge n and the preceding edge, which depends on the direction of rotation of the target.

5. The synchronization method as claimed in claim 1 , wherein the range of tolerance values associated with each theoretical signature of the set of theoretical signatures of the edges of the target is reduced when the engine speed drops below a predetermined threshold.

6. The synchronization method as claimed in claim 1 , comprising, if, during the implementation of the method ( 100 ) for identifying the detected edge considering a forward rotation of the target, no correspondence is detected, transmitting ( 220 ) a synchronization fault signal (Wtsyn).

Assignees

• Vitesco Tech Gmbh

Inventors

• Denert Camille
• Marconato Benjamin
• Gouzenes Nora-Marie

Classifications

• F02D41/009 Primary

  using means for generating position or synchronisation signals · CPC title

• F02D2250/06

  Reverse rotation of engine · CPC title

• F02D41/042

  for stopping the engine · CPC title

• F02D2200/101

  Engine speed · CPC title

• F02D2041/0095

  Synchronisation of the cylinders during engine shutdown · CPC title