1
FORM – 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
AN INTEGRATED COMBUSTION ANALYSIS SYSTEM FOR AN INTERNAL
COMBUSTION ENGINE
Applicant(s):
VE COMMERCIAL VEHICLES LTD
102, INDUSTRIAL AREA 1, PITHAMPUR- 454775, DIST. DHAR, MP, INDIA
Inventors:
(1) Vinod Kumar Singh
(2) Fata Ram Meghwal
(3) Hemant Rathi
(4) Akhilesh Shukla
(5) Sachin Agarwal
The following specification particularly describes the invention and the manner in which it
is to be performed.
2
AN INTEGRATED COMBUSTION ANALYSIS SYSTEM FOR AN
INTERNAL COMBUSTION ENGINE
FIELD OF THE DISCLOSURE
[0001] This invention generally relates to a field of combustion measurement and
engine diagnostic systems for internal combustion engines, and in particular, to an5
integrated combustion analysis system for an internal combustion engine for a
heavy-duty bus and method thereof.
BACKGROUND
[0002] The subject matter discussed in the background section should not be
assumed to be prior art merely as a result of its mention in the background section.10
Similarly, a problem mentioned in the background section or associated with the
subject matter of the background section should not be assumed to have been
previously recognized in the prior art. The subject matter in the background section
merely represents different approaches, which in and of themselves may also
correspond to implementations of the claimed technology.15
[0003] Engine combustion analysis systems are widely employed in internal
combustion engines to evaluate combustion behavior, optimize engine performance,
and ensure compliance with emission and efficiency requirements. Such systems
typically rely on accurate correlation between in-cylinder pressure measurements
and corresponding crank angle positions to generate pressure versus crank angle (P–20
θ) characteristics, which are fundamental for calculating combustion parameters and
diagnosing engine operation.
[0004] In conventional combustion analysis arrangements, determination of crank
angle is commonly achieved through the use of a dedicated external crank angle
encoder mounted at a front end of a crankshaft, often in conjunction with a damper25
pulley plate. The external crank angle encoder generates high-resolution angular
reference signals that are synchronized with in-cylinder pressure data acquired from
pressure sensors installed in a combustion chamber.
[0005] However, incorporation of a separate crank angle encoder and damper pulley
plate introduces additional mechanical components, sensors, and wiring into the30
3
engine system. These added components increase overall system cost, installation
time, and wiring complexity, and also impose packaging constraints, particularly in
vehicle-mounted engines where available space around the crankshaft front end is
limited.
[0006] Furthermore, installation of an external crank angle encoder typically5
requires mechanical modification of the crankshaft front end, such as removal or
alteration of existing pulleys or dampers. Such mechanical modifications can
adversely affect engine balance and reliability, and may not be feasible on
production engines or during vehicle-level testing, thereby limiting applicability of
conventional combustion analysis systems.10
[0007] In addition, the presence of multiple sensors, connectors, and mechanical
mountings associated with external crank angle encoders introduces additional
potential failure points. Signal integrity issues, misalignment, and mechanical wear
can compromise measurement accuracy and system reliability during prolonged
engine testing or on-road operation.15
[0008] Conventional approaches aimed at achieving accurate crank angle
determination for in-cylinder pressure measurement therefore tend to increase
system complexity and reduce ease of deployment. As a result, there exists a need
for a combustion analysis system that can provide synchronized crank angle and in-
cylinder pressure measurements while minimizing additional hardware, mechanical20
modifications, and installation effort, particularly for production engines and
vehicle-mounted testing applications.
[0009] Another the patent application, “CN105157914A,” titled “System and
method for conversion from time domain to angle domain of internal combustion
engine internal cylinder pressure signal,” describes a system and method for25
conversion from a time domain to an angle domain of an internal combustion engine
internal cylinder pressure signal. The integrated combustion analysis system
comprises a cylinder pressure measurement device and a pulse signal measurement
device. The cylinder pressure measurement device and the pulse signal
measurement device transmit a collected internal cylinder pressure signal and a30
pulse signal corresponding to a flywheel ring gear to an internal clock collection
4
system; the internal clock collection system transmits the received data to a
processor for processing; and a precise zero crossing point of the pulse signal is
determined based on an interpolation algorithm and conversion from a time domain
to an angle domain of the internal cylinder pressure signal is realized. Therefore, a
problem of mistaken triggering caused by coder signal loss or interference according5
to the traditional testing method can be solved effectively; and thus reliability of the
data acquisition process can be effectively improved.
[0010] Another patent application, "CN102003298A," titled "Real-time feedback
device and method of combustion information for controlling engine," describes
real-time feedback device and method of combustion information for controlling an10
engine. The device comprises a singlechip, a signal processing unit and an ECU
(Electronic Control Unit) communication interface circuit, wherein the signal
processing unit is connected with the signal input end of the singlechip and also
connected with the ECU communication interface circuit, the input end of the signal
processing unit is connected with a sensor for collecting an engine signal through a15
sensor wiring harness, and the ECU communication interface circuit is connected
with a control device in the engine. The method comprises the following steps of:
constructing a scheduling mechanism of calculation and collection tasks; and
detecting the effectiveness of combustion information by utilizing an online
correction algorithm to map, sending data to a vehicular ECU through a20
communication interface and receiving a vehicular ECU instruction. With the
singlechip with small size, low cost and strong real-time property as a calculation
platform, the invention can realize a combustion information observing unit capable
of being directly integrated and used with the vehicular ECU and provide important
feedback information for realizing the future combustion closed-loop control of the25
engine.
[0011] In conventional engine combustion analysis systems, accurate determination
of crank angle for correlation with in-cylinder pressure measurements is largely
dependent on the use of dedicated external crank angle encoders and associated
mechanical mounting arrangements. Such systems typically employ encoder wheels30
or damper-mounted encoder plates installed at a front end of a crankshaft, along
5
with additional sensors and wiring harnesses, to obtain high-resolution angular
position data. As a result, installation of conventional combustion analysis systems
often requires mechanical modification of existing engine components, increased
wiring complexity, and careful alignment of multiple sensing elements. These
requirements make conventional systems less adaptable to production engines and5
vehicle-mounted testing environments, particularly where space constraints,
durability considerations, and installation time are critical. While external crank
angle encoders are capable of providing precise angular resolution, they introduce
additional cost, potential failure points, and packaging challenges, thereby limiting
practicality and scalability for routine engine development, calibration, and10
certification testing applications.
OBJECTIVES OF THE INVENTION
[0012] The objective of the present invention is to provide an integrated combustion
analysis system for an internal combustion engine that enables simultaneous
measurement of in-cylinder pressure and determination of crank angle using an15
existing flywheel-mounted crankshaft position sensor.
[0013] The objective of the present invention is to eliminate the requirement for a
separate external crank angle encoder and a damper pulley plate by electrically
interfacing with the existing flywheel-mounted crankshaft position sensor.
[0014] The objective of the present invention is to reduce wiring harness complexity20
and overall sensor count by utilizing an integrated Y-cable interface that branches
crankshaft position signals without interrupting normal engine control unit
operation.
[0015] The objective of the present invention is to improve system reliability and
robustness by minimizing additional mechanical components, connectors, and25
mounting interfaces associated with conventional combustion analysis systems.
[0016] The objective of the present invention is to enable accurate and synchronized
combustion diagnostics, including pressure versus crank angle analysis, for engine
testing, calibration, and diagnostic applications.
[0017] The objective of the present invention is to provide an integrated combustion30
analysis system that is adaptable to both multi-cylinder diesel engines and multi-
6
cylinder gasoline engines without requiring mechanical modification of engine
architecture.
[0018] The objective of the present invention is to provide a compact, cost-
effective, and easily installable combustion analysis solution suitable for both
engine test-bed environments and vehicle-mounted testing applications.5
[0019] The objective of the present invention is to enhance overall combustion
measurement capability and diagnostic efficiency while maintaining compatibility
with existing engine control systems and production engine configurations.
SUMMARY
[0020] The present invention relates to an integrated combustion analysis system10
for an internal combustion engine.
[0021] According to an aspect, an integrated combustion analysis system for an
internal combustion engine is disclosed. The integrated combustion analysis system
comprises a flywheel-mounted crankshaft position sensor configured to generate
speed and position signals corresponding to crankshaft rotation. The integrated15
combustion analysis system further comprises an in-cylinder pressure sensor
configured to generate real-time combustion chamber pressure signals. The
integrated combustion analysis system further comprises an integrated Y-cable
interface electrically connected inline with the flywheel-mounted crankshaft
position sensor, the integrated Y-cable interface defining a primary signal path and20
a secondary signal path. Further, the primary signal path routes the crankshaft
position signal to an engine control unit (ECU) without interruption to normal
engine operation. Further, the secondary signal path routes an identical crankshaft
position signal to a combustion analysis module. The integrated combustion
analysis system further comprises a signal conditioning module configured to filter,25
condition, and time-align the crankshaft position signal and the in-cylinder pressure
signal. The integrated combustion analysis system further comprises a data
acquisition and processing unit configured to reconstruct crank angle information
from a flywheel tooth pattern and missing-tooth reference and to synchronize the
reconstructed crank angle information with the in-cylinder pressure signal to30
generate pressure versus crank angle (P–θ) characteristics. Further, the integrated
7
combustion analysis system enables simultaneous crank angle determination and in-
cylinder pressure measurement without requiring a separate crank angle encoder or
mechanical modification of the internal combustion engine.
[0022] According to another aspect, a method for operating an integrated
combustion analysis system for an internal combustion engine is disclosed. The5
method comprises steps of generating, via a flywheel-mounted crankshaft position
sensor, speed and position signals corresponding to crankshaft rotation. The method
further comprises steps generating, via an in-cylinder pressure sensor, real-time
combustion chamber pressure signals. The method further comprises steps defining,
via an integrated Y-cable interface electrically connected inline with the flywheel-10
mounted crankshaft position sensor, a primary signal path and a secondary signal
path. Further, the primary signal path routes the crankshaft position signal to an
engine control unit (ECU) without interruption to normal engine operation. Further,
the secondary signal path routes an identical crankshaft position signal to a
combustion analysis module. The method further comprises steps filtering,15
conditioning, and time-aligning, via a signal conditioning module, the crankshaft
position signal and the in-cylinder pressure signal. The method further comprises
steps reconstructing, via a data acquisition and processing unit, crank angle
information from a flywheel tooth pattern and missing-tooth reference and to
synchronize the reconstructed crank angle information with the in-cylinder pressure20
signal to generate pressure versus crank angle (P–θ) characteristics. Further, the
integrated combustion analysis system enables simultaneous crank angle
determination and in-cylinder pressure measurement without requiring a separate
crank angle encoder or mechanical modification of the internal combustion engine.
BRIEF DESCRIPTION OF THE DRAWINGS25
[0023] The accompanying drawings illustrate various embodiments of systems,
methods, and embodiments of various other aspects of the disclosure. Any person
with ordinary skills in the art will appreciate that the illustrated element boundaries
(e.g., boxes, groups of boxes, or other shapes) in the figures represent one example
of the boundaries. It may be that in some examples one element may be designed as30
multiple elements or that multiple elements may be designed as one element. In
8
some examples, an element shown as an internal component of one element may be
implemented as an external component in another, and vice versa. Furthermore,
elements may not be drawn to scale. Non-limiting and non-exhaustive descriptions
are described with reference to the following drawings. The components in the
figures are not necessarily to scale, emphasis instead being placed upon illustrating5
principles.
[0024] FIG. 1 illustrates a block diagram of an integrated combustion analysis
system for an internal combustion engine, according to an embodiment of the
present disclosure;
[0025] FIG. 2 illustrates a flowchart showing operations of the integrated10
combustion analysis system for an internal combustion engine, according to an
embodiment of the present disclosure; and
[0026] FIG. 3 illustrates a flowchart showing a method for operating the integrated
combustion analysis system for the internal combustion engine, according to an
embodiment of the present disclosure.15
DETAILED DESCRIPTION
[0027] Some embodiments of this disclosure, illustrating all its features, will now
be discussed in detail. The words “comprising,” “having,” “containing,” and
“including,” and other forms thereof, are intended to be equivalent in meaning and
be open ended in that an item or items following any one of these words is not meant20
to be an exhaustive listing of such item or items or meant to be limited to only the
listed item or items. It must also be noted that as used herein and in the appended
claims, the singular forms “a,” “an,” and “the” include plural references unless the
context clearly dictates otherwise.
[0028] Although any systems and methods similar or equivalent to those described25
herein can be used in the practice or testing of embodiments of the present
disclosure, the preferred, systems and methods are now described. Embodiments of
the present disclosure will be described more fully hereinafter with reference to the
accompanying drawings in which like numerals represent like elements throughout
the several figures, and in which example embodiments are shown. Embodiments30
of the claims may, however, be embodied in many different forms and should not
9
be construed as limited to the embodiments set forth herein. The examples set forth
herein are non-limiting examples and are merely examples among other possible
examples.
[0029] The present invention discloses various embodiments of an integrated
combustion analysis system for an internal combustion engine is disclosed. The5
integrated combustion analysis system comprises a flywheel-mounted crankshaft
position sensor configured to generate speed and position signals corresponding to
crankshaft rotation. The integrated combustion analysis system further comprises
an in-cylinder pressure sensor configured to generate real-time combustion chamber
pressure signals. The integrated combustion analysis system further comprises an10
integrated Y-cable interface electrically connected inline with the flywheel-
mounted crankshaft position sensor, the integrated Y-cable interface defining a
primary signal path and a secondary signal path. Further, the primary signal path
routes the crankshaft position signal to an engine control unit (ECU) without
interruption to normal engine operation. Further, the secondary signal path routes15
an identical crankshaft position signal to a combustion analysis module. The
integrated combustion analysis system further comprises a signal conditioning
module configured to filter, condition, and time-align the crankshaft position signal
and the in-cylinder pressure signal. The integrated combustion analysis system
further comprises a data acquisition and processing unit configured to reconstruct20
crank angle information from a flywheel tooth pattern and missing-tooth reference
and to synchronize the reconstructed crank angle information with the in-cylinder
pressure signal to generate pressure versus crank angle (P–θ) characteristics.
Further, the integrated combustion analysis system enables simultaneous crank
angle determination and in-cylinder pressure measurement without requiring a25
separate crank angle encoder or mechanical modification of the internal combustion
engine.
[0030] FIG. 1 illustrates a block diagram of an integrated combustion analysis
system (100) for an internal combustion engine (102), according to an embodiment
of the present disclosure.30
10
[0031] In some embodiments, the integrated combustion analysis system (100) is
configured for use with an internal combustion engine (102) to enable simultaneous
crank angle determination and in-cylinder pressure measurement during engine
operation. The integrated combustion analysis system (100) utilizes a flywheel-
mounted crankshaft position sensor (104) that is already present on the internal5
combustion engine (102) to generate speed and position signals corresponding to
crankshaft rotation. The integrated combustion analysis system (100) further
includes an in-cylinder pressure sensor (106) configured to generate real-time
combustion chamber pressure signals. The integrated combustion analysis system
(100) operates without mechanical modification of the internal combustion engine10
(102). The integrated combustion analysis system (100) is designed to support
combustion diagnostics while preserving normal engine functionality. The
integrated combustion analysis system (100) is suitable for development,
calibration, and diagnostic applications.
[0032] In some embodiments, the integrated combustion analysis system (100)15
comprises an integrated Y-cable interface (108) electrically connected inline with
the flywheel-mounted crankshaft position sensor (104). The integrated Y-cable
interface (108) defines a primary signal path and a secondary signal path branching
from the same crankshaft position signal source. The primary signal path routes the
crankshaft position signal to the engine control unit without interruption to normal20
engine operation. The secondary signal path routes an identical crankshaft position
signal to a combustion analysis module. The integrated Y-cable interface (108)
enables duplication of the crankshaft position signal without signal degradation. The
integrated Y-cable interface (108) eliminates the need for a separate crank angle
encoder.25
[0033] In some embodiments, the integrated Y-cable interface (108) is configured
with matched electrical impedance and electromagnetic shielding to prevent signal
distortion. The impedance matching ensures that the crankshaft position signal
characteristics remain consistent along both the primary signal path and the
secondary signal path. The electromagnetic shielding minimizes susceptibility to30
electrical noise generated during engine operation. The configuration maintains
11
signal integrity for both the engine control unit and the combustion analysis module.
The integrated Y-cable interface (108) supports reliable signal transmission under
varying operating conditions. The configuration improves robustness of the
integrated combustion analysis system (100).
[0034] In some embodiments, the integrated combustion analysis system (100)5
further comprises a signal conditioning module (110) configured to filter, condition,
and time-align the crankshaft position signal and the in-cylinder pressure signal.
The signal conditioning module (110) performs noise filtering to remove unwanted
electrical disturbances. The signal conditioning module (110) further performs
phase alignment to ensure accurate temporal correlation between signals. The signal10
conditioning module (110) enables real-time synchronization of crankshaft position
information and pressure data. The signal conditioning module (110) supports high-
fidelity combustion measurement. The module ensures stable signal processing
during transient engine operation.
[0035] In some embodiments, the integrated combustion analysis system (100)15
comprises a data acquisition and processing unit (112) configured to receive
conditioned signals from the signal conditioning module (110). The data acquisition
and processing unit (112) reconstructs crank angle information using known
flywheel geometry and engine configuration parameters. The reconstruction utilizes
a flywheel tooth pattern and a missing-tooth reference to determine crankshaft20
angular position. The reconstructed crank angle information provides sufficient
resolution for combustion analysis. The data acquisition and processing unit (112)
synchronizes the reconstructed crank angle information with the in-cylinder
pressure signal. The synchronization enables generation of pressure versus crank
angle characteristics.25
[0036] In some embodiments, the data acquisition and processing unit (112) is
configured to compute combustion parameters based on the synchronized pressure
versus crank angle characteristics. The combustion parameters include indicated
mean effective pressure, mass fraction burned, and rate of heat release. The
computed parameters enable detailed evaluation of combustion performance. The30
data acquisition and processing unit (112) supports real-time combustion
12
monitoring during engine operation. The unit further supports post-processed
combustion analysis after data acquisition. The processing capability enables engine
diagnostics and optimization.
[0037] In some embodiments, the integrated combustion analysis system (100) is
implemented solely through electrical signal-level integration. The integrated5
combustion analysis system (100) does not require modification to a mechanical
layout of the internal combustion engine (102). The integrated combustion analysis
system (100) further does not require modification to software of the engine control
unit. The electrical integration enables rapid installation and removal of the
integrated combustion analysis system (100). The configuration supports use on10
production engines without structural alteration. The approach reduces installation
complexity and validation effort. The implementation improves adaptability across
engine platforms.
[0038] In some embodiments, the integrated combustion analysis system (100) is
configured for use on both engine test-bed installations and internal combustion15
engine (102). The integrated combustion analysis system (100) supports operation
across a range of engine speeds and loads. The compact architecture facilitates
integration within constrained packaging environments. The integrated combustion
analysis system (100) enables combustion diagnostics during stationary testing and
on-road testing. The integrated combustion analysis system (100) supports multi-20
cylinder diesel engines and multi-cylinder gasoline engines. The configuration
enhances applicability across different engine types. The integrated combustion
analysis system (100) maintains consistent performance under varying operational
conditions.
[0039] In some embodiments, elimination of a separate crank angle encoder and25
damper pulley plate reduces system cost and hardware count. The reduction in
mechanical components minimizes potential failure points. The simplified wiring
architecture reduces harness complexity and installation time. The integrated
combustion analysis system (100) improves overall reliability and robustness. The
integrated combustion analysis system (100) reduces calibration effort associated30
with external encoders. The configuration enhances long-term operational stability.
13
The integrated combustion analysis system (100) provides a cost-effective and
scalable combustion diagnostics solution.
[0040] FIG. 2 illustrates a flowchart showing operations (200) of the integrated
combustion analysis system (100) for an internal combustion engine (102),
according to an embodiment of the present disclosure.5
[0041] At operation 202, the integrated combustion analysis system (100) is
initialized for operation with an internal combustion engine (102). During this
operation, system power-up and readiness checks are performed to ensure that all
functional blocks of the integrated combustion analysis system (100) are available
for signal reception and processing. Communication readiness is established10
between the flywheel-mounted crankshaft position sensor (104), the in-cylinder
pressure sensor (106), and downstream processing components. The initialization
prepares the integrated combustion analysis system (100) for continuous monitoring
during engine operation. No mechanical modification of the internal combustion
engine (102) is required at this operation. The integrated combustion analysis15
system (100) remains passive until sensor inputs are received.
[0042] At operation 204, sensor inputs are received from the flywheel-mounted
crankshaft position sensor (104) and the in-cylinder pressure sensor (106) during
operation of the internal combustion engine (102).
[0043] At operation 204A, the flywheel-mounted crankshaft position sensor (104)20
generates speed and position signals corresponding to crankshaft rotation.
[0044] At operation 204B, the in-cylinder pressure sensor (106) generates real-time
combustion chamber pressure signals corresponding to combustion events. Both
sensor inputs are acquired substantially simultaneously. The sensor input operation
forms a basis for synchronized combustion analysis. Normal engine operation25
remains unaffected during signal acquisition.
[0045] At operation 206, signal routing is performed through the integrated Y-cable
interface (108). The crankshaft position signal generated by the flywheel-mounted
crankshaft position sensor (104) is branched into a primary signal path and a
secondary signal path. The primary signal path routes the crankshaft position signal30
to the engine control unit without interruption. The secondary signal path routes an
14
identical crankshaft position signal to the combustion analysis module. The signal
routing operation ensures duplication of the crankshaft position signal without
distortion. Engine control functionality is preserved during this operation.
[0046] At operation 208, signal conditioning is applied to the crankshaft position
signal and the in-cylinder pressure signal by the signal conditioning module (110).5
Noise filtering is performed to remove electrical disturbances arising during engine
operation. Phase alignment is applied to time-align the crankshaft position signal
and the in-cylinder pressure signal. The signal conditioning operation stabilizes
signal quality under varying engine speeds and loads. Accurate temporal correlation
is established between the signals. The conditioned signals are prepared for crank10
angle reconstruction and pressure analysis.
[0047] At operation 210, data acquisition and processing are performed by the data
acquisition and processing unit (112). The data acquisition and processing unit (112)
reconstructs crank angle information using known flywheel geometry and a
missing-tooth reference. The reconstructed crank angle information is synchronized15
with the in-cylinder pressure signal to generate pressure versus crank angle
characteristics. The data acquisition and processing unit (112) computes combustion
parameters including indicated mean effective pressure, mass fraction burned, and
rate of heat release. This operation supports real-time and post-processed
combustion analysis. Accurate diagnostics are achieved without a separate crank20
angle encoder.
[0048] At operation 212, outputs are generated and provided to system endpoints.
The engine control unit continues to receive the crankshaft position signal for
normal engine operation. The combustion analysis module receives synchronized
pressure versus crank angle data and computed combustion parameters. The outputs25
enable combustion diagnostics, calibration, and performance optimization. Data
may be logged, displayed, or transmitted for further analysis. Output delivery is
maintained across operating conditions. The integrated combustion analysis system
(100) supports continuous monitoring.
[0049] At operation 214, the integrated combustion analysis system (100)30
completes a data acquisition cycle or transitions to a standby or logging state. The
15
end operation represents completion of a measurement sequence or controlled
shutdown of data processing. Acquired combustion data remains available for
analysis and reporting. The integrated combustion analysis system (100) may re-
enter operation 200 for subsequent measurement cycles. The operational flow
supports repeated and continuous use. The integrated combustion analysis system5
(100) thereby provides a reliable and efficient combustion diagnostics solution.
[0050] FIG. 3 illustrates a flowchart showing a method (300) for operating the
integrated combustion analysis system (100) for the internal combustion engine
(102), according to an embodiment of the present disclosure.
[0051] At operation 302, the flywheel-mounted crankshaft position sensor (104) is10
configured to generate speed and position signals corresponding to crankshaft
rotation. The integrated combustion analysis system (100) utilizes the flywheel-
mounted crankshaft position sensor (104) that is already present on the internal
combustion engine (102) to generate speed and position signals corresponding to
crankshaft rotation. The integrated combustion analysis system (100) operates15
without mechanical modification of the internal combustion engine (102). The
integrated combustion analysis system (100) is designed to support combustion
diagnostics while preserving normal engine functionality. The integrated
combustion analysis system (100) is suitable for development, calibration, and
diagnostic applications.20
[0052] At operation 304, the in-cylinder pressure sensor (106) is configured to
generate real-time combustion chamber pressure signals.
[0053] At operation 306, the integrated Y-cable interface (108) electrically is
connected inline with the flywheel-mounted crankshaft position sensor (104), the
integrated Y-cable interface (108) defining a primary signal path and a secondary25
signal path. Further, the primary signal path routes the crankshaft position signal to
an engine control unit (ECU) without interruption to normal engine operation.
Further, the secondary signal path routes an identical crankshaft position signal to a
combustion analysis module. The primary signal path routes the crankshaft position
signal to the engine control unit without interruption to normal engine operation.30
The secondary signal path routes an identical crankshaft position signal to a
16
combustion analysis module. The integrated Y-cable interface (108) enables
duplication of the crankshaft position signal without signal degradation. The
integrated Y-cable interface (108) eliminates the need for a separate crank angle
encoder.
[0054] At operation 308, the signal conditioning module (110) is configured to5
filter, condition, and time-align the crankshaft position signal and the in-cylinder
pressure signal. The signal conditioning module (110) further performs phase
alignment to ensure accurate temporal correlation between signals. The signal
conditioning module (110) enables real-time synchronization of crankshaft position
information and pressure data. The signal conditioning module (110) supports high-10
fidelity combustion measurement. The module ensures stable signal processing
during transient engine operation.
[0055] At operation 310, the data acquisition and processing unit (112) is
configured to reconstruct crank angle information from a flywheel tooth pattern and
missing-tooth reference and to synchronize the reconstructed crank angle15
information with the in-cylinder pressure signal to generate pressure versus crank
angle (P–θ) characteristics. Further, the integrated combustion analysis system
(100) enables simultaneous crank angle determination and in-cylinder pressure
measurement without requiring a separate crank angle encoder or mechanical
modification of the internal combustion engine (102).20
[0056] In some embodiments, the data acquisition and processing unit (112) is
configured to compute combustion parameters based on the synchronized pressure
versus crank angle characteristics. The combustion parameters include indicated
mean effective pressure, mass fraction burned, and rate of heat release. The
computed parameters enable detailed evaluation of combustion performance. The25
data acquisition and processing unit (112) supports real-time combustion
monitoring during engine operation. The unit further supports post-processed
combustion analysis after data acquisition. The processing capability enables engine
diagnostics and optimization.
[0057] Various embodiments of the present invention provide significant technical,30
economic, and operational advantages through an integrated combustion analysis
17
system (100) for an internal combustion engine (102) that utilizes an existing
flywheel-mounted crankshaft position sensor (104) in combination with an
integrated Y-cable interface (108). The integrated combustion analysis system (100)
eliminates the requirement for a separate external crank angle encoder and an
associated damper pulley plate, thereby avoiding mechanical fitment, alignment,5
and balancing issues typically encountered in conventional combustion diagnostic
arrangements. By reusing the flywheel-mounted crankshaft position sensor (104),
the integrated combustion analysis system (100) reduces overall hardware count and
wiring complexity while ensuring uninterrupted operation of the engine control unit
(ECU). The integrated Y-cable interface (108) electrically branches the crankshaft10
position signal without degrading signal integrity or affecting normal engine
operation. Elimination of precision encoders and additional mechanical mounting
components significantly lowers system cost and calibration effort. The electrical
signal-level integration enables plug-and-play installation and removal without
permanent modification to a mechanical layout of the internal combustion engine15
(102). Reduction in component count minimizes potential failure points, thereby
improving reliability and robustness of the integrated combustion analysis system
(100). The integrated combustion analysis system (100) is scalable and adaptable
across different internal combustion engine (102) platforms, supporting both engine
test-bed installations and vehicle-mounted testing while enabling accurate,20
synchronized combustion diagnostics for development, calibration, and
performance optimization.
[0058] It has thus been seen the integrated combustion analysis system (100) for an
internal combustion engine (102), as described. The integrated combustion analysis
system (100) in any case could undergo numerous modifications and variants, all of25
which are covered by the same innovative concept; moreover, all of the details can
be replaced by technically equivalent elements. In practice, the components used,
as well as the numbers, shapes, and sizes of the components can be whatever
according to the technical requirements. The scope of protection of the invention is
therefore defined by the attached claims.30

CLAIMS

1. An integrated combustion analysis system (100) for an internal combustion
engine (102), the integrated combustion analysis system (100) comprising:
a flywheel-mounted crankshaft position sensor (104) configured to5
generate speed and position signals corresponding to crankshaft rotation;
an in-cylinder pressure sensor (106) configured to generate real-time
combustion chamber pressure signals;
an integrated Y-cable interface (108) electrically connected inline
with the flywheel-mounted crankshaft position sensor (104), the integrated Y-10
cable interface (108) defining a primary signal path and a secondary signal
path;
wherein the primary signal path routes the crankshaft position signal
to an engine control unit (ECU) without interruption to normal engine
operation;15
wherein the secondary signal path routes an identical crankshaft
position signal to a combustion analysis module;
a signal conditioning module (110) configured to filter, condition, and
time-align the crankshaft position signal and the in-cylinder pressure signal;
and20
a data acquisition and processing unit (112) configured to reconstruct
crank angle information from a flywheel tooth pattern and missing-tooth
reference and to synchronize the reconstructed crank angle information with
the in-cylinder pressure signal to generate pressure versus crank angle (P–θ)
characteristics,25
wherein the integrated combustion analysis system (100) enables
simultaneous crank angle determination and in-cylinder pressure
measurement without requiring a separate crank angle encoder or mechanical
modification of the internal combustion engine (102).
2. The integrated combustion analysis system (100) as claimed in claim 1,
wherein the integrated Y-cable interface (108) is configured with matched
electrical impedance and electromagnetic shielding to prevent signal
distortion of the crankshaft position signal supplied to the engine control unit
and the combustion analysis module.5
3. The integrated combustion analysis system (100) as claimed in claim 1,
wherein the data acquisition and processing unit (112) reconstructs the crank
angle information using known flywheel geometry and engine configuration
parameters to provide crank angle resolution sufficient for combustion
analysis.10
4. The integrated combustion analysis system (100) as claimed in claim 1,
wherein the data acquisition and processing unit (112) is configured to
compute one or more combustion parameters including indicated mean
effective pressure (IMEP), mass fraction burned (MFB), and rate of heat
release based on the synchronized pressure versus crank angle (P–θ)15
characteristics.
5. The integrated combustion analysis system (100) as claimed in claim 1,
wherein the integrated combustion analysis system (100) is implemented
solely through electrical signal-level integration without modification to a
mechanical layout of the internal combustion engine (102) or software of the20
engine control unit.
6. The integrated combustion analysis system (100) as claimed in claim 1,
wherein the signal conditioning module (110) performs noise filtering and
phase alignment to enable real-time synchronization of the crankshaft
position signal and the in-cylinder pressure signal.25
7. The integrated combustion analysis system (100) as claimed in claim 1,
wherein the integrated combustion analysis system (100) is configured for
use on both engine test-bed installations and vehicle-mounted internal
combustion engine (102).
8. The integrated combustion analysis system (100) as claimed in claim 1,
wherein elimination of a separate crank angle encoder and damper pulley
plate reduces system cost, installation complexity, and calibration effort.
9. The integrated combustion analysis system (100) as claimed in claim 1,
wherein the data acquisition and processing unit (112) is configured to5
support real-time combustion monitoring and post-processed combustion
analysis for engine diagnostics and performance optimization.
10. A method (300) for operating an integrated combustion analysis system (100)
for an internal combustion engine (102), the method (300) comprising:
generating, via a flywheel-mounted crankshaft position sensor (104),10
speed and position signals corresponding to crankshaft rotation;
generating, via an in-cylinder pressure sensor (106), real-time
combustion chamber pressure signals;
defining, via an integrated Y-cable interface (108) electrically
connected inline with the flywheel-mounted crankshaft position sensor (104),15
a primary signal path and a secondary signal path;
wherein the primary signal path routes the crankshaft position signal
to an engine control unit (ECU) without interruption to normal engine
operation;
wherein the secondary signal path routes an identical crankshaft20
position signal to a combustion analysis module;
filtering, conditioning, and time-aligning, via a signal conditioning
module (110), the crankshaft position signal and the in-cylinder pressure
signal; and
reconstructing, via a data acquisition and processing unit (112), crank25
angle information from a flywheel tooth pattern and missing-tooth reference
and to synchronize the reconstructed crank angle information with the in-
cylinder pressure signal to generate pressure versus crank angle (P–θ)
characteristics,
wherein the integrated combustion analysis system (100) enables30
simultaneous crank angle determination and in-cylinder pressure
measurement without requiring a separate crank angle encoder or mechanical
modification of the internal combustion engine (102).