# US 10,309,854 B2 · Method for processing a signal of a pressure measuring device inside an internal combustion engine

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- Number: US 10,309,854 B2
- Document ID: US10309854B2
- Status: Granted
- Kind: B2
- Application number: 14/427,807
- Filed: 2013-08-26
- Published: 2015-08-13
- Granted: 2019-06-04
- Earliest claimed: 2012-09-20
- Assignees: Continental Automotive France; Continental Automotive GmbH
- Applicants: Continental Automotive France; Continental Automotive GmbH
- Inventors: Laurent Landrevie; Fabrice Tonon
- Web page: https://patentgrep.com/patent/US10309854B2

## CPC

- G01L 23/10: by pressure-sensitive members of the piezoelectric type
- G01L 23/08: operated electrically {(G01L23/22 takes precedence)}
- G01L 23/226: {using specific filtering}
- G01L 23/227: {using numerical analyses}
- G01M 15/08: by monitoring pressure in cylinders
- G01L: MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE (weighing G01G)
- G01M: TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR

## Abstract

A method for processing a signal of a pressure measuring device inside an internal combustion engine, the device including: a pressure measuring sensor supplying an output voltage signal (SB), and a processing unit connected to the pressure measuring sensor, the method including the following steps: I. calculating a duration (Dt1) between a first time (t0) corresponding to a first combustion pressure peak (P0) and a second time (t1) corresponding to a second combustion pressure peak (P1), consecutive to the first combustion pressure peak (P0), II. calculating a correction start time (tc1) defined according to the previously calculated duration (Dt1), III. measuring a value of the signal (VOFF1) at the correction start time (tc1), IV. correcting the signal, on the basis of the correction start time (tc1) in relation to a reference value (VREF) and obtaining a first processed signal (S) such that: S=SB−VOFF1+VREF.

## Claims

### Claim 1

A method of measuring a pressure in a combustion chamber of a cylinder in a precise manner using a device for processing a signal of a pressure measuring device (DP) inside an internal combustion engine, said device including:
a pressure measuring sensor (800) supplying an output voltage signal (SB) representing the pressure within the internal combustion engine, the signal (SB) including “plateau” phases during which the voltage changes according to a more or less linear function as a function of time, and voltage peak phases representing the combustion pressure peaks,
a processing unit (500) connected to said pressure measuring sensor,
the method including the following steps:
I) acquisition of the values of the signal (SB) by the processing unit (500),
II) detection by the processing unit (500) of the voltage peaks of the signal (SB) representing the combustion pressure peaks,
the method being characterized in that it furthermore includes the following steps:
III) calculation by the processing unit (500) of a first duration (Dt1) between a first time (t0) corresponding to a first combustion pressure peak (P0) and a second time (t1) corresponding to a second combustion pressure peak (P1), consecutive to the first combustion pressure peak (P0),
IV) calculation by the processing unit (500) of a correction start time (tc1), located in a plateau phase between two combustion peaks, and defined by:
tc1=t1±x1*Dt1
where:
tc1 is the correction start time,
T1 is a second time corresponding to a second combustion pressure peak,
Dt1 is a first duration between the first time (t0) and the second time (t1),
x1 is a first constant with a value varying between 0.1 and 0.9,
V) measurement by the processing unit (500) of a value of the signal (VOFF1) at the correction start time (tc1),
VI) correction by the processing unit (500) of the signal (SB), on the basis of the correction start time (tc1) in relation to a reference value (VREF) and obtaining of a first processed signal (S) such that:
S=SB−VOFF1+VREF
Where SB is the signal at the pressure measuring sensor output,
VOFF1 is the value of the signal at the correction start time (tc1),
VREF is the reference value.

### Claim 2 (depends on 1)

The method of measuring as claimed in claim 1, wherein:
during step III: calculation by the processing unit (500) of a second duration (Dt2) between the second time (t1) corresponding to the second combustion pressure peak (P1) and a third time (t2) corresponding to a third combustion pressure peak (P2), consecutive to the second combustion pressure peak (P1),
during step IV: calculation by the processing unit (500) of a second correction start time (tc2) defined by:
tc2=t2+x2*Dt2
Where:
tc2 is a second correction start time,
t2 is a third time corresponding to a third combustion pressure peak,
Dt2 is a second duration between the second time (t1) and the third time (t2),
x2 is a second constant with a value varying between 0.1 and 0.9,
during step V: measurement by the processing unit (500) of a second value of the signal (VOFF2) at the second correction start time (tc2), and calculation by the processing unit (500) of a slope (A), defined by:
A
=
(
V
OFF
⁢
⁢
2
-
V
OFF
⁢
⁢
1
)
(
t
c
⁢
⁢
2
-
t
c
⁢
⁢
1
)
Where VOFF2 is the value of the signal at the second correction start time (tc2),
tc2 is a second correction start time,
during step VI: correction of the signal (SB) by the processing unit (500), at a given time (i), located after the second correction start time (tc2) and obtaining of a second processed signal (S′) such that:
S′(i)=S(i)−A*i
Where S′(i) is the second processed signal at the time i,
S (i) is the first processed signal at the time i.

### Claim 3 (depends on 2)

The method of measuring as claimed in claim 2, wherein the value of the second constant x2 is equal to the value of the first constant x1.

### Claim 4 (depends on 3)

The method of measuring as claimed in claim 3, wherein:
step II comprises the second-order offset of the values of the signal (SB) in relation to a time unit (t), and obtaining of an offset signal (SD), such that:
S
D
=
dS
B
2
dt
2
where SD is the offset signal,
step III comprises:
the detection by the processing unit (500) of two consecutive times [(t0, t1), (t1, t2)] corresponding to the passage of the values of the offset signal (SD) below a threshold (S1),
the calculation by the processing unit (500) of a duration (Dt1, Dt2) between these two consecutive times [(t0, t1), (t1, t2)].

### Claim 5 (depends on 2)

The method of measuring as claimed in claim 2, wherein:
step II comprises the second-order offset of the values of the signal (SB) in relation to a time unit (t), and obtaining of an offset signal (SD), such that:
S
D
=
dS
B
2
dt
2
where SD is the offset signal,
step III comprises:
the detection by the processing unit (500) of two consecutive times [(t0, t1), (t1, t2)] corresponding to the passage of the values of the offset signal (SD) below a threshold (S1),
the calculation by the processing unit (500) of a duration (Dt1, Dt2) between these two consecutive times [(t0, t1), (t1, t2)].

### Claim 6 (depends on 2)

The method of measuring as claimed in claim 2, wherein the signal (SB) is a signal filtered and sampled in relation to the time.

### Claim 7 (depends on 2)

The method of measuring as claimed in claim 2, wherein the value of the first constant x1 is determined at a maximum engine speed.

### Claim 8 (depends on 1)

The method of measuring as claimed in claim 1, wherein:
step II comprises the second-order offset of the values of the signal (SB) in relation to a time unit (t), and obtaining of an offset signal (SD), such that:
S
D
=
dS
B
2
dt
2
where SD is the offset signal,
step III comprises:
the detection by the processing unit (500) of two consecutive times [(t0, t1), (t1, t2)] corresponding to the passage of the values of the offset signal (SD) below a threshold (S1),
the calculation by the processing unit (500) of a duration (Dt1, Dt2) between these two consecutive times [(t0, t1), (t1, t2)].

### Claim 9 (depends on 8)

The method of measuring as claimed in claim 8, wherein the value of the threshold (S1) is determined in such a way that, at the detected times (t0, t1, t2), the value of the signal (P0, P1, P2) is more or less maximum.

### Claim 10 (depends on 1)

The method of measuring as claimed in claim 1, wherein the signal (SB) is a signal filtered and sampled in relation to the time.

### Claim 11 (depends on 1)

The method of measuring as claimed in claim 1, wherein the value of the first constant x1 is determined at a maximum engine speed.

### Claim 12 (depends on 11)

The method of measuring as claimed in claim 11, wherein the maximum engine speed value is 5000 rpm.

### Claim 13 (depends on 1)

The method of measuring as claimed in claim 1, wherein the value of the first constant x1 varies between 0.4 and 0.7.