FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
TEST DEVICE AND METHOD FOR MEASURING ELECTRICAL CHARGE BALANCE OF AUTOMOTIVE VEHICLE
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. Niranjana Upadhaya 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 provisional specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present invention is related to the field of automotive electrical charging system and more particularly to test device and method for measuring electrical charge balance of automotive vehicle.
BACKGROUND OF INVENTION
Efficient management of the energy resources in the vehicle requires a careful selection of the electrical charging system components. The electrical charging system consists of Alternator and Battery. The electrical charge balance mainly depends on the temperature around the alternator, alternator rating at different temperature, engine to alternator pulley ratio, battery charge acceptance and electrical and electronic loads duty cycle. While deciding the automotive vehicle electrical specifications, especially in the low cost/ small car segment, the development engineer is confronted with the conflicting requirements due to increasing electrical energy needs, demand for reduced alternator load on the engine, packing size constraints, extreme operating temperatures, worsening urban traffic situations, the heavy wattages of electrical radiator cooling fans especially in the diesel engines, anticipation of user adding accessories in the field and cost of the component. These make the charging system design more complex and challenging for development engineers.
The Electrical charge balance of vehicle electrical system design plays critical role in the vehicle normal functioning like vehicle starting, lamps illumination, malfunctioning of different mechanical function controlling
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electronic control unit's. Hence it is important to measure the charging system components performance at extreme conditions. The present method involves running the vehicle on the predefined drive cycle with predefined duty cycle of electrical and electronic loads. These methods require sophisticated hardware in terms of data capturing and analysis. The entire test has to be repeated if there is a change in the any component. As this test is performed in the practical road condition it is difficult to maintain the test condition, hence the need for new test device and method felt.
The present invention proposes a device and method that can simulate different driving pattern and electrical loads duty cycles and helps in deriving the charge balance. Previous inventions tackles charge balance issues but have certain limitations.
DE 35 20 985 discloses a device for monitoring the state of charge of the starter battery of a motor vehicle which continuously measures the battery current and the battery voltage and integrates the measured current to determine the lost charge. In the current-less state of the battery, the device detects the settling equilibrium voltage and calculates a hypothetical battery capacity from this equilibrium voltage and the charge previously extracted while in operation. A measurement for the instantaneous state of charge of the battery is calculated from the charge extracted when the battery current is flowing again and the calculated hypothetical battery capacity according to a predetermined formula, however it considers only one type of drive cycle and there is no control over load duty cycle.
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DE 43 41 826 teaches a method for determining the state of charge of an electrical energy store from which a starter motor of an internal combustion engine influenced by a control device and/or electrical consumers are supplied with electrical energy. In order to be able to describe the state of charge of the electrical energy store as accurately as possible, it is proposed in a first variant of the method that the voltage present at the energy store and the current flowing be detected during the starting operation. In the process, the current in the control device is differentiated according to the time. When relative maxima occur, the appropriate voltage value is detected and a magnitude characterizing the state of charge of the energy store is derived from this. According to a second variant of the method, the variation in time of the internal resistance of the energy store is calculated through a series of successive synchronized current and voltage measurements and this is used to determine the instantaneous state of charge of the energy store on the basis of a reference characteristic stored in the control device.
All the methods of this kind require very accurate detection of the measurement data and complex data processing due to the problem of the accumulation of measuring errors over lengthy periods of time. , however it considers only one type of drive cycle and there is no control over load duty cycle.
US 6291971 teaches a method for detecting the charge balance of a storage battery for an electric drive vehicle by measuring and summing the charge and discharge currents over time, a plurality of current measuring arrangements are provided. Individual electrical power consumers are each assigned to one of these current measuring arrangements, and the currents
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detected by the current measuring arrangements are added over time. The consumers are assigned mainly on the basis of their power draws. It is also possible to replace one or more current measuring arrangements by a pulse generator. The power draw of the corresponding consumer is then multiplied by its operating time, determined with a given factor. The current draw of the electric drive is measured in any case, however it considers only one type of drive cycle and there is no control over load duty cycle.
OBJECTS OF THE INVENTION
The main object of this invention is to provide a test device and method to calculate charge balance of automotive vehicle on real time basis.
Another object of this invention is to provide a test device to simulate different drive cycle with actual temperature observed in and around the Alternator (generator) of the vehicle.
Another object of this invention is to provide a test device to simulate different electrical load duty cycle to arrive worst case charge balance of the vehicle.
BRIEF DESCRIPTION OF THE INVENTION
The test device consists of a high speed spindle motor, a torque sensor, an alternator mounting arrangement with heat enclosure, a load bank and a battery which is all connected to a computer based control panel by suitable cables.
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The computer based control panel controls the electrical load on the alternator through the load bank. The said control panel also controls the speed of the said high speed spindle motor and monitors the voltage and current output from the said alternator. Also, the battery current, voltage and Alternator inlet, outlet temperature is monitored continuously by the computer based control panel. The temperature around the alternator is maintained based on temperature observed on the vehicle by heating enclosure. The load duty cycle data taken from an actual road test is fed to the computer based control panel which in turn controls the load bank parameters accordingly, also the engine rpm and torque from the road test data of the vehicle is fed to the control panel which controls the speed of the high speed spindle accordingly.
Thus, in this way the two variable inputs i.e. engine speed and load on the alternator are controlled through a computer based control panel. At the end of the test the test charge balance calculated by algebraic summation of battery current. Using this device the voltage level during drive cycle across battery and load bank is also recorded. This enables acceleration of testing and flexibility of testing the charge balance for different types of vehicles.
DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.
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Fig 1 shows the schematic layout of the test device in accordance with this
invention.
Fig 2 shows the typical alternator drive cycle.
Fig 3 shows the typical electrical load cycle.
Referring to fig.l the device consists of a high speed spindle motor [1] and a torque sensor [2] mounted on the spindle. The spindle is provided with a cooling arrangement [3] and is coupled to an alternator [5]. The alternator is housed inside a heat chamber [4] and is connected to a load bank [6]. All in turn are connected to computer [7] for control and measurement. The entire drive arrangement of alternator is kept inside the enclosure [8] for better safety and to reduce the noise level. The test battery [9] connected in parallel to alternator as well as load bank [6].
The high speed spindle motor controlled by a variable frequency drive will form the speed source. The speed of this motor will be controlled by a microprocessor based digital variable frequency drive to drive the alternator [5] under test at adjustable speeds. Fig 2 shows the typical drive cycle with time vs speed. The torque sensor is used to measure the input torque to the test alternator. The measured input torque recorded using Computer [7].The alternator [5] under test will be enclosed inside a hot chamber carrying heaters, the temperature sensor and circulating fan to maintain a uniform temperature with in the chamber.
The computer application software is developed on WINDOW-2000/XP OPERATING SYSTEM, USING Labview software. The computer based data acquisition system is used for data logging and sequence control for both
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drive pattern and electrical load duty cycle during the test. Fig 3 shows the typical load cycle with time vs Amperes.
Method for measuring electrical charge balance of automotive vehicle consists following steps
1) Carrying out instrumentation of the vehicle for arriving alternator drive pattern and electrical load pattern. The instrumentation mainly involves connecting thermocouple for measurement of alternator air-inlet temperature, alternator air-outlet temperature, ambient temperature, battery electrolyte temperature. It also involves connecting shunt for measurement of current across battery, alternator and loads. 'W terminal of the alternator is connected to the measuring device to measure the alternator speed. The provision is made to measure the alternator and battery voltage.
2) Writing software codes for data acquisition by using lab view software.
3) Running the vehicle in the test track to collect the customer usage pattern of Electrical load Vs Vehicle speed.
4) Upload the drive pattern and electrical load pattern on the computer.
5) Mount the test alternator on the alternator mouthing fixture and connect the battery parallel to load bank.
6) Run the uploaded program on the test device.
7) After completing the test, calculate the charge balance by algebraic summation of battery current.
The one cycle of drive pattern is of 5 minutes and can be repeated for required number of cycles. The electrical load duty cycle consists of current
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in Ampere Vs time in seconds. The one cycle of electrical load pattern is of 5 minutes and can be repeated for required number of cycles. The electrical loading is done using programmable electronic load bank.
Writing software codes for data acquisition is based on following parameters
1) Controlling the speed of motor to achieve desired speed at alternator.
2) Putting electrical loads.
3) Provision of heater around the alternator to maintain the temperature around the alternator.
4) Acquiring the current of alternator output, battery input/output and electronic load bank.
5) Acquiring the voltage of alternator output, battery input/output and electronic load bank.
6) Acquiring the temperature of alternator air inlet side, alternator air outlet side, battery temperature, ambient temperature.
7) Acquiring the alternator torque input.
8) Calculating the charge balance based on the algebraic sum of battery current.
Dated this 14th day of March 2007
TATA MOTORS LIMITED By their Agent and Attorney

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