CHAPTER 3 Materials and Methods This chapter deals with the materials used (including their selection, development/procurement and manufacturing) and the methods used for conversion of the conventional TATA Indica Diesel car in to Hybrid Electric Vehicle as well as the testing methods with experimental plan. Following main points were considered: i. Conversion should be economical and affordable. ii. Conversion should be easy, such that an unskilled worker/mechanic should be able to carry out the conversion within 4 to 5 hours, after receiving necessary one day training. iii. There should be minimum requirement of special tools for initial conversion as well as for any service maintenance work to be carried out on the HEV in future. iv. Return on investment should be measurable and attractive for the user. v. Convenient to use for the end customer / user / driver. vi. Reliability and ease of maintenance. vii. Ease of implementation even for vehicle manufacturer on the similar new models cars OR newly designed models introduced in future. viii. Satisfactory performance. Part numbering system has been developed and bill of materials is prepared for the conversion of conventional car into hybrid electric car. Process chart is prepared to explain the sequence of operations as well as provides knowledge for possibility of concurrent manufacturing of components and sub-assembly and assembly, for reducing the time required for Conversion of Conventional existing Diesel car in to Hybrid Electric car. This can be useful for 21
understanding the disassembly/assembly procedure for maintenance and service requirements. 3.1. Materials: The material, parts, subassembly and assembly components were segregated into categories in the form of parts newly required for the conversion and those removed from the existing conventional car which are required to be reused without any modification, to be modified before reuse or not required at all. The conversion of existing Diesel car in to Hybrid Electric Vehicle (HEV) was carried out by using categorisation of the material utilization, for simplicity of understanding (as shown in Table: 3.1). There is no separate mention of all the remaining parts of the conventional car, which continue to be part of the HEV. They are neither removed nor required to be modified. Such components are part and parcel of conventional car as well as HEV. In fact the entire car except those parts mentioned in the Bill of Materials (Annexure: 1), are functionally required in Hybrid Electric car as well. Hence, there is no need to dismantle / remove them from the vehicle for conversion. Annexure: 2 is prepared for explanation of the convention for levels in BOM and Annexure:3 shows the elucidation for part numbering system logic. The above concept proved to be cost effective and gave clarity of understanding for the repeatability of the conversion process. 3.2 List of Components: This section covers all the parts required / used for conversion of conventional diesel car into Hybrid Electric Vehicle as well as the test equipments and experimental set up. 3.2.1. Import component: 22
Only certain parts, which are usable as it is and not available in India are developed as per our requirement and imported from China. They are: i. Stator Assembly with winding (fig. 3.1 and Plate. 4) ii. Rotor Assembly with Permanent Magnets (as per Fig. 3.1 and Plate. 4) iii. Controller Assembly (Plate. 12) iv. Accelerator Pedal control (Plate. 13) Table: 3.1: Segregation of Components and assembly parts A B C D E F G TATA make : Indica DLS model, existing Diesel car. Part removed but not used in the finally converted hybrid electric car. Parts dismantled but reused for conversion as it is, without any modifications or rework. Parts dismantled but reused for conversion after due modifications or rework, as required (part no. is mentioned for the new part). New part or assembly directly fitted on to the vehicle, for conversion of the conventional car in to hybrid electric car. Electric wires, Connectors, Battery, Battery Terminals & Switches. Test equipments for Fuel Consumption measurement, combined RPM meter, Speedo meters and Trip meter, Ampere meters, Volt meter and its components. 3.2.2. Standard parts: Following parts are standard parts readily available, chosen according to the functional and performance demand / load characteristics: i. All nut bolts ii. Bearing inner 6206 RS1 (Make: SKF) (as per Fig. 3.1) 23
iii. Bearing outer 805945 (Make: FAG) (as per Fig. 3.1) iv. A set of 4 nos. of 12 Volt DC Batteries and connecting cables (Plate. 11) v. Wiring harness and switches (Annexure: 8) 3.2.3. Other parts: The other parts are designed and manufactured as per the functional and performance requirement, as per optimum dimensions required. i. Axle shaft (as per Fig. 3.2 and Plate. 3) ii. Inner plate (Plate. 1) iii. Grooved spacer (as per Fig. 3.4) iv. Outer plate (as per Fig. 3.3) v. Brake discs, RH and LH (Plate. 2, 3,6,7 and 8) vi. Brake calipers, RH and LH(Plate. 7) vii. Brackets for mounting brake calipers viii. Battery charger (Plate. 14) ix. Axle washers and axle nuts (Plate. 19) 24
Fig. 3.1 25
Fig. 3.2 26
Fig. 3.3 27
Fig. 3.4 28
Plate 1: Cover Inner 29
Plate 2: Cover Inner with Brake Disc 30
Plate 3: Brake Disc, Cover Inner & Retainer with motor shaft assembly on Suspension arm 31
Plate 4: PM BLDC Hub Motors Assembly 32
Plate 5: Existing car with brake drum assembly 33
Plate 6: RH Hub motor with Brake Disc assembly on car 34
Plate 7: Hub motor with Brake Caliper assembly on car 35
Plate 8: LH Hub motor with Brake Disc assembly on car 36
Plate 9: RH and LH Hub motors assembly mounted on car 37
Plate 10: RH and LH Wheels mounted on Hub motor 38
Plate 11: Set of 4 nos. of 12 Volt Batteries 39
Plate 12: Controllers mounted on dickey panel 40
Plate 13: Accelerator Pedal 41
Plate 14: Battery Charger 42
Plate 15: Combined RPM, Speedometer and Trip meter 43
Plate 16: Ampere meter, Volt meter and RPM meter 44
Plate 17: Fuel Consumption measuring set up 45
Plate 18: Laboratory test set up 46
Plate 19: Hybrid Electric Vehicle ready for testing 47
3.2.4. Test equipments & experimental set up: The test equipments and experimental set up was fabricated / developed as per the requirement of measurement of performance parameters /test data, for laboratory testing (Plate no.18) and while the vehicle is in motion (Plate no. 15, 16 and 17). Such gadgets were not readily available (e.g. the measurement of Amperes drawn by each motor operating on 48 Volt - DC, but the meter supply voltage being 12 volt DC, similarly all the other meters operating on 12 Volt, DC vehicular battery of), hence were specially made as per order or fabricated. They are all installed for experimentation only. All or any of these equipments may not be part of mandatory requirement on the HEV usage for routine purpose. 3.2.4.1. Volt meter: Since the main parameter essential for measuring / recording the performance data required for comparison are state of charge (Voltage across the set of 4 nos. 12 Volt batteries connected in series) of batteries from starting of the test till the batteries are not able to provide sufficient current required to run the motors (to develop torque required to propel the car) any further, a digital Voltmeter is developed (Plate. 16). The digital Voltmeter should be able to indicate state charge for 4 nos. of 12 Volt batteries connected in series, but the LED s display of the volt meter is operational on 12 Volt vehicular battery. Because, the pack of 48 Volt batteries is expected to be charged fully for running of motors and it may be depleted as per the usage. If the volt meter is also operating on the same 48 Volt battery, it may show misleading readings and eventually fail prematurely under fluctuating current drawn. It is important for driver to know/note that how much charge is consumed and how much charge is still remaining, at every stage continuously. 3.2.4.2. Ampere meter: Two nos. of Ampere meter (Plate. 16) were developed for measuring the current drawn by each of the motors, to record the level of discharge current drawn at different RPM, load and under varying state of charge of batteries. In production vehicles, total current drawn by both Hub motors can be measured 48
by combined single Ampere meter. Not only these meters will indicate performance, it can help in diagnosis of any malfunction, in case of failures or under performance / deterioration in output v/s input. An independent Ampere meter for each motor can help identifying that which motor has developed fault (e.g. if one of the motor is drawing excessive current as compared to other or stopped working). 3.2.4.3. RPM, Speedometer and Trip meter for Electric motors: Two digital display meters (Plate. 15) working on the principle of Proximity sensor based measurement of Motor RPM, separately for both RH & LH motors are developed. These meters are able to measure the RPM and vehicular speed (in unit of measure as Km/hr) of motor always and display the information on distance covered (in Km unit), whether the vehicle is running on IC engine or electric motors. This measurement will verify the recording of analog meter for conventional vehicle running on IC engine, when the vehicle is moving in straight ahead condition. And it will indicate the vehicle speed when the vehicle is Switched ON to move on electric motors. There is one switch provided for switching ON the display of Trip meter. It means, the Trip meter switch should be put ON along with Hub Motors dc voltage supply switch has been put ON. So that the distance covered by the vehicle on electric battery charge from fully charged condition to low voltage condition can be measured. Two separate proximity sensors and combined RPM, Speedometer & Trip meters are developed and installed for knowledge of variations under different running conditions of straight ahead driving, turning and braking as well as variations in respective hub motor performance due to inherent current drawn conditions of RH & LH Hub motors. Also for the routine usage purpose only one such measurement may be sufficient, if the user wants to have the knowledge of distance/mileage covered in electric mode. 49
3.2.4.4Fuel Consumption Measurement set up: Fuel supply line from fuel tank to fuel feed pump and return fuel line from fuel injection pump to fuel tank are disconnected (both flexible rubber pipes near the engine) at the front end. It was necessary to connect the measuring flask (Plate. 17), so that bleeding of fuel system is achievable and airlock does not occur while running. Also the return line connection is connected to the measuring flask, for accurate measurement of consumption of fuel. 3.3. Part Numbering System: Part numbering system as per (Annexure: 1, 2 and 3) is developed for assisting in identifying the components for reordering, storage, pick and assembly. However, all components are designed such a way that sub-assembly of any components cannot be wrongly done. It means POKA YOKE system is adopted (which is called mistake proofing). The Bill of Materials (BOM) for the conversion kit indicates all the part nos. as per the given part numbering system. 3.4. Methodology for Conversion in to HEV: Methodology adopted for reduction in consumption of fuel in existing diesel cars by fitment of two DC hub motors directly on rear wheels (for front wheel drive vehicles with semi trailing link suspension), for conversion of existing diesel car in to hybrid electric car, is discussed through four heads: i. Process to be followed for assembly of motor on the suspension arm. ii. Installation of suspension arm (with motor assembly) on the vehicle. iii. Installation of test equipments on the test vehicle conventional car converted in to HEV. iv. Testing of vehicle fitted with hub motors by running in IC engine mode and hybrid mode to determine the reduction in consumption of fuel in 50
existing diesel car, after converting it in to HEV, with two hub motors fitted directly in the rear wheels. The complete process sheet is given in Annexure: 4. 3.4.1. Process for Assembly of Motor on the Suspension arm: The details of step by step methodology is given below i. Step by step process for assembly of motor on the suspension arm begins with concurrent production of parts being kept ready as part of preparation for sub assembly of components and then final assembly of all the components and sub assemblies to make the assembly of motor on the suspension arm. The parts that are required to be manufactured are Axle shaft, Inner grooved sleeve spacer, Inner cover plate and Outer cover plate (with outer bearing hub). ii. Initially the suspension arm assembly from the vehicle is made ready by removing the existing axle shaft. The newly designed and machined shaft is press fitted in the suspension arm, at the same location from where the old axle shaft was removed. iii. As a second step the brake disc is inserted on the shaft and then the Inner plate assembly of Inner Plate and Inner bearing 6206 2RS1 is press fitted on the axle shaft. iv. The third step is to insert the Sleeve of set of wires inside the inclined hole in the axle shaft. v. Next step is to insert the grooved sleeve, as a spacer on the axle shaft. vi. Press the woodruff key in the key slot provided on the axle shaft. vii. Assemble the stator winding assembly on the axle shaft (by aligning the key slot with the key on the axle shaft). Pull the stator winding from the center of shaft from inside for clearing of slack, if any. viii. Assemble outer bearing sleeve by press fitting on the axle shaft (against stator hub). 51
ix. Then insert the assembly rotor housing (sub assembly of rotor housing and permanent magnets), very carefully. x. Fix inner plate assembly to the Rotor housing using six Allen key screws. xi. Fix brake disc plate to the inner plate assembly with six counter sinking screws. xii. Assemble the outer plate assembly (sub assembly of outer plate and outer bearing 805945) by press fitting. xiii. Fix outer plate assembly to the rotor housing using six Allen key screws. xiv. Use the special washer and fix axle nut. Tighten the axle nut with adequate torque. Tighten lock nut. xv. Fix the bracket for caliper mounting with the lower end of suspension arm. xvi. Last step is to mount caliper assembly on the bracket. (Steps from 3.4.1.i to 3.4.1.xvi are to be performed in the serial sequence only, as mentioned above). 3.4.2. Installation of Suspension arm (with Motor assembly) on the Test vehicle: The assembly of suspension arm with motor RH and assembly of suspension arm with motor LH are to be located in RH and LH side of the rear suspension respectively. i. For installation of the assembly of suspension arm with motor for converting the conventional car in to hybrid electric car, we have to prepare the car by removing certain parts which are not to be used in the hybrid car. Hence, the complete process includes removal of existing parts, discard non usable parts and refit usable along with new parts. In the beginning the steps for removal of parts /assembly parts are mentioned, followed by installation of suspension arm with motor and other parts. Subsequently, steps required to be followed for fitment of the parts removed but, required to be used with the Hybrid car are explained. Some of the steps as part of safety requirement are also list at appropriate locations. ii. Disconnect battery ve terminal connection. 52
iii. Put wheel chokes in front and rear of the both front wheels. iv. Put the rear end of vehicle chassis on firm and steady props with both RH & LH wheels clear from the ground. v. Remove wheel rim assembly (with tyre) by loosening four wheel bolts. All four wheel bolts and wheel rim assembly (with tyre) are to be retained for reuse with hybrid conversion. vi. Dismantle shock absorber assembly lower mounting bolt and nuts. Shock absorber and lower mounting bolt nut should be retained for reuse. vii. Dismantle hydraulic brake pipes and hand brake cable connections. Hydraulic pipe and banjo bolts to be reused (but hand brake cable will remain unused for test vehicle only). viii. Dismantle front suspension arm nut bolts for mounting suspension arm with the chassis. The entire suspension arm assembly will be totally disassembled from vehicular chassis. This entire set of assembly of parts including Suspension arm, axle shaft, brake drum assembly, and brake back plate (with brake shoe & wheel cylinder) is to be discarded (Plate. 5). Only the mounting /fixing nut bolts / hardware parts will be reused. ix. Assemble the suspension arm assembly with motor by using / fixing front end mounting nut bolts. x. Assemble the shock absorber lower end mounting nut bolt to the new suspension arm assembly with motor. xi. Connect hydraulic pipe connection with banjo bolt and new banjo washers to the brake calipers. xii. Fix wheel rim with tyre on the outer plate of motor, with the help of 4 wheel bolts. xiii. Carryout the bleeding of hydraulic brake system, as per the standard process, specified by vehicle manufacturer. xiv. Mount the controller in proper position with positive fixing and make connect in to motor connectors. xv. Connect 48 Volt battery bank (4 nos. of 12 Volt each battery connected in series) + ve and ve terminal cables connections to controller, motor, and 53
accelerator pedal controller as well as ON OFF switch. Ensure that all the connections are properly insulated and securely fastened, to avoid short circuit problem. 3.4.3. Installation of Test equipments: (contacts as per the fig. no. 3.21) i. Connect SHUNT on the battery positive cable in series connection. ii. Connect + ve and ve connections of Ampere meter RH as designated on the SHUNT. iii. Repeat these two steps above for connecting Ampere meter LH, also. iv. Connect Voltmeter + ve and ve connections to the + ve and ve terminal connection of 48 V battery bank. v. Connect all the three (two Ampere meters Rh & LH and one Volt meter to + ve and ve terminals of 12 V vehicular battery (or auxiliary 12 Volt battery), because the power source for (LED lights) all the meters is 12 V DC. vi. Mount proximity sensor in appropriate position. vii. Connect sensor and the combined display of RPM/Vehicle speed & Trip meter. viii. Connect power source for this meter also from 12 Volt DC vehicular battery. ix. Finally the set up for measurement of Fuel consumption (Plate. 16): Importantly the main objective of this research project is reduction in consumption of fuel in existing diesel car. The set up is consisting of a Glass bulb of 1 liter capacity having two necks, one used for supplying diesel (connected to the fuel filter inlet, by disconnecting supply line from fuel tank to fuel filter and block it, so that fuel from the tank does not leak) and another neck connected to the return fuel line from fuel injection pump to inverted measuring flask (with its lower most outlet location is above the top level of bulb). A measuring cylinder is connected to the flask reservoir. When the tests are being conducted the bulb must be completely full without any air pocket, so that the measured quantity consumed for a definite distance covered in IC engine power mode OR Electric Motor driving mode as per the test fuel consumption can be measured and recorded for comparison and analysis. 54
The return of over flow of diesel from fuel injection pump is dropped back in the measuring flask. Any simple type of flow meter or electronic flow meters for can be also used. 55