FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)


TITLE OF THE INVENTION A SYSTEM FOR ENGINE TORQUE EVALUATION
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. G .S Raju an Indian national, of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in
which it is to be performed.

FIELD OF INVENTION
This invention relates to the engine starting torque evaluation under various operating conditions of engine. Starter motor new drive mechanism is designed to capture the engine torque demand during starting process. Strain experienced by the starter new drive mechanism during starting process is converted into torque demand by the engine.
BACKGROUND OF THE INVENTION
Engine starting torque requirement at various operating ambient temperature conditions is prerequisite input for designing starter motor. At present there is no method available to quantify the engine starting torque demand on the starting system at various operating ambient temperature conditions. Engine test rigs normally have dynamometer shaft coupled with engine flywheel. With this arrangement, it is not possible to quantify the exact starting torque requirement of the engine. At very low speeds of engine, during starting process, conventional test rig dynamometer may encounter resonance condition and may result into shaft breakage. To overcome this problem, a new methodology was invented. Starter motor drive mechanism is redesigned to measure strain experienced by the pinion during starting process. Engine torque requirement is arrived from these strain measurements at various operating ambient temperature conditions. Based on these torque requirements, starter motor design is optimized for various operating conditions of vehicle.

OBJECT OF INVENTION
The object of this invention is, during starting process, to find out the engine starting
torque requirement on the starter motor under various operating temperature
conditions.
Starter motor design can be optimized using this method and vehicle will not face
any starting problem subsequent to this optimization.
STATEMENT OF INVENTION
Accordingly the present invention discloses a system for engine torque evaluation
comprising
starter motor assembly;
an augmented drive shank of said starter motor assembly configured for mounting
radio frequency transmitter, power source and strain gauge;
at least one radio frequency receiver and;
at least one data logging device.
BRIEF DESCRIPTION OF DRAWINGS
In accordance to the present invention,
Figure 1: shows the new drive mechanism assembly of starter motor
Figure 2: shows the new drive mechanism sectional view of starter motor
Figure3: shows a schematic diagram of the data transmission, receiving, data
processing and data recording lodging
Figure 4: shows the Engine cranking characteristics at 27°C
Figure 5: shows the Engine cranking characteristics at 0°C

Figure 6: shows the Engine cranking characteristics at 27°C Figure 7: shows the Engine cranking characteristics at 0°C
DETAILED DESCRIPTION OF THE INVENTION
In the conventional mechanism the torque produced in the starter motor is transmitted to drive. Engine torque demand during starting process is supplied through this drive mechanism.
Figure 1 & 2 shows the new drive mechanism of starter motor. Mounting bracket of starter motor is designed to house this new drive mechanism. Provision to fix strain gauge is made on this new drive mechanism.
The arrangement of starter motor (1) drive mechanism (2) provided with strain gauge (5) and radio frequency (RF) transmitter (7). Constructional features of the invention include the new arrangement of starter motor (1) drive shank (3). The new design to fix radio frequency data transmitter (7) and its source battery (4) is achieved by increasing the length of the shank(3). The strain gauge (5) is affixed on new drive shank (3). Torque produced by the starter motor is transmitted to the engine flywheel through starter motor drive pinion (6).
The variable torsional load experienced by the starter motor drive mechanism during engine starting process is measured by the strain gauge (5) on the drive shank and same is sent to the RF transmitter (7) fixed on it.
Referring to figure 3 and 8 The RF transmitter (7) also acts as the signal conditioning device and transmits corresponding voltage signals to a RF receiver (9). The RF receiver (9) interprets the received signal and amplifies the signal into a proportional

voltage signal which can be used for data processing as well as recording the data by connecting the data logger (10).
Engine torque can be evaluated as mentioned herein. When the starter motor is energized, pinion starts to rotate the flywheel of the internal combustion engine. During cranking of the internal combustion engine the torque demand will be based on the following:
1. Compression load in the cylinders
2. Friction load on the crank shaft due to its angular velocity and due to the piston movement in individual cylinders.
3. Engine oil viscosity changes with temperature. Hence the torque required by Engine during cranking will be dependent on the ambient temperature.
Starter motor experiences varying torque demand while rotating the flywheel. Based on the torque demand by the flywheel rotation, the drive shank will experience various strain patterns and this is captured by the strain gauge, which will be transmitted by the RF transmitter to the RF receiver. Receiver data is captured in data logger.
The test is conducted at ambient temperature of 27°C and 0°C and strain and current drawn by the starter motor during cranking is recorded. The torque characteristic is determined based on the above values.
Based on the calibrated torque values and the measured strain voltages from the data logger, the torque characteristics can be determined by co-relating the values.

Fig 4 and fig 5 gives the characteristics of strain recording pattern (bottom) and current drawn by the starter motor (top) during cranking test at ambient temperature of27DC and at 0°C respectively.
Based on the calibrated torque values and the measured strain voltages from the data logger, the torque characteristics can be determined by co-relating the values in a algebraic equation as mentioned below
T = [m*(V-0.015)] + K
Where,
T Torque, Nm
m gradient or slope of the characteristic curve
Whose value was found to be 22.15 V Strain voltage, V k offset from the origin, whose value is found to be
3.0347
Hence based on the calculation, the following characteristics curve was obtained in proportion to the strain voltage measurements
Fig 6 is the torque verses time characteristics obtained at ambient temperature of 27°C. Torque demand experienced by the starter motor new drive mechanism is 1.8 N-m. Since gear ratio between starter pinion and flywheel ring gear is 10, torque demand by the engine is 18 N-m. Cranking speed of the engine is computed from the same recording and found to be 218rpm.

Fig 7 is the torque verses time characteristics obtained at ambient temperature of 0°C. Torque demand experienced by the starter motor modified drive mechanism is 4.17 N-m. Since gear ratio between starter pinion and flywheel ring gear is 10, torque demand by the engine is 41.7 N-m. Cranking speed of the engine is computed from the same recording and found to be 206rpm.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

WE CLAIM
1. A system for engine torque evaluation comprising
starter motor assembly;
an augmented drive shank of said starter motor assembly configured for mounting radio frequency transmitter, power source and strain gauge; at least one radio frequency receiver and; at least one data logging device.
2. The system for engine torque evaluation as claimed in claim 1, wherein said radio frequency transmitter is activated by said power source.
3. The system for engine torque evaluation as claimed in claim 1, wherein said strain gauge is mounted on said drive shank to measure the variable torsional load on the said drive mechanism.
4. The system for engine torque evaluation as claimed in any one of the preceding claims, wherein said radio frequency transmitter is configured to receive the variable torsional load data input from said strain gauge.
5. The system for engine torque evaluation as claimed in any one of the preceding claims, wherein said radio frequency receiver is configured to amplify the received signals from radio frequency transmitter to a voltage signal.
6. The system for engine torque evaluation as claimed in claim 1, wherein said data logger optimizes said voltage signal for data processing and recording.

7. The system for engine torque evaluation substantially as herein above described in the specification with reference to the accompanying drawings.