Development of Compact Chassis Dynamometer System for Two Wheeler Vehicle

ISSN 2395-1621 Development of Compact Chassis Dynamometer System for Two Wheeler Vehicle #1 K.A. Tapre, #2 K.M.Narkar 1 krunal.tapre@gmail.com 2 knarkar@gmail.com #12 Department of Mechanical Engineering, D. Y. Patil College of Engineering, Akurdi, Pune, Maharashtra, India. ABSTRACT This paper deals with design and development of compact chassis dynamometer for two wheeler vehicle. In comparison to prior chassis dynamometers, the current work aims to check the performance of the vehicle by using air cooled eddy current retarder instead of wet eddy current retarder to achieve the compact size dynamometer and reduce the volume and cost. The chassis dynamometer consists of three major components roll set, the absorption unit and a torque indication system. In this paper the focus is on designing aspects of the chassis dynamometer system to avoid its complexity. Design of Test rig equipment like Roller, Bed, Plummer blocks, Cardan shaft, Mechanical coupling and Pneumatic arrangement for front wheel clamping is the objective of this paper. The design validation of dynamometer and other parts is considered. The chassis dynamometer is used to study the performance of vehicle under different load condition and to perform different test on the vehicle. ARTICLE INFO Article History Received :18 th November 2015 Received in revised form : 19 th November 2015 Accepted : 21 st November, 2015 Published online : 22 nd November 2015 Keywordswheeler. a Air cooled eddy current retarder, dynamometer system, roll set and two I. INTRODUCTION In this paper different aspects of automotive chassis dynamometer test system are explained in details. The topics that will cover in this paper will include: what is chassis dynamometer is, its importance, how it is operated and a process of how to design, develop and validate a chassis A dynamometer is a general term for any device that can apply a resistance load and measure that load and loaded speed to determine the power output. Dynamometer can measure wide range of power for different system but a specific type of dynamometer must be selected or designed. In this paper the chassis dynamometer is designed. II.CHASSIS DYNAMOMETER A chassis dynamometer is primarily used in the automotive industry to measure the power that an automobile puts to the ground or to the tires. Measuring the power at the tires gives the designer a better understanding of actual vehicle performance characteristics. Unlike the engine dynamometer the chassis dynamometer includes the transmission and differential losses to help designer s better understanding of the end power and torque capabilities of the vehicle. Therefore it can be decide that the current engine, transmission and differential configurations are suitable to achieve the desired vehicle performance. Chassis dynamometer is a service tool that allows to safely placing controlled load on a vehicle through a load changing device. It is a tool to evaluate a vehicles performance under various load conditions. In this paper the design part of the chassis dynamometer is focused in order to reduce its complexity the small air cooled eddy current retarder is used and according to the retarder the design of test rig equipment like bed, roller, cardan shaft, mechanical coupling is carried out. III.MAJOR COMPONENTS i. Roll set ii. Absorption unit iii. Torque indication system. i. Roll set - Roll sets come in variety of diameters Selection depends on vehicle application Automotive application- smaller diameter roll set and large truck dyno- larger diameter roll set is used. 2015, IERJ All Rights Reserved Page 1

All the members of roll set are dynamically balanced Rollers are of Stainless Steel tube with steel end discs welded & fitted into a center shaft. Complete roller assembly is stress relieved, prior to precision machining. Roller assembly is both statically & dynamically balanced to make whole structure vibration free. Roll sets are placed in a specially designed frame. They are either to directly couple to the dynamometer absorption unit or to a belt drive system. Roll sets may be of fixed dimensions to suit a single vehicle. It can be with adjustable version to accommodate a variety of wheelbases. With adjustable wheelbase, multiple vehicles can be tested with a single machine. Rollers are supported on the central shaft by heavy Plummer block bearings. Dynamometer rolls vary in size from 20cm to 127cm. The smaller rollers have a greater potential for damaging the tires. During a dynamometer check, there is little weight on the tires and only a small area of the tread face usually the centre rib or centre portion of the tread is in contact with the roll. Excessive heat builds up in this small area. If the test runs too long, the excessive heat can damage the tire to the point where it could fail later on the highway. The roll diameter should be as large as possible to avoid the damage of the tyre. The tyre diameter is in the range of 43 to 47 cm for the two wheelers. The diameter of roller can be considered according to the analysis carried out for tyre. Design of Roller- The functions of roller are as follows- it receives the power provided by the vehicle wheel and it absorbs and stores this energy in form of angular velocity, acts of inertial wheel. The characteristics that must have an optimal roller are: Inertia must be maximum. Roller RPM at the end of the test must be maximum. Material Selected Stainless Steel Properties- Density 7900 kg/m Configuration A Configuration B Out of the above two configurations A & B, for achieving the Compactness of the system configuration B has been selected so that the retarder can mount below the test bed platform instead of sideways. The space can be optimized by using the configuration B. Fig 1. 30 cm roller & 40 cm roller So as the roller size increases the stress value in the tyre decreases. Therefore the larger roller size i.e. 40 cm is selected for the roller of the chassis ii. Absorption unit The power absorption units used in chassis dynamometer are as follows- - Hydraulic dynamometer - Eddy current dynamometer From the above mentioned power absorption unit Eddy current dynamometer is used because of the following reason- In hydraulic dynamometer, water is used for torque coupling, while it is magnetic coupling in E C Dynamometer Hydraulic dynamometers are unidirectional, while E C dynamometers are bi-directional Theoretically E C Dynamometer can be run without water, but not hydraulic, as loading depends on water in hydraulic E C dynamometers are well adapted to computer control, while hydraulic are not. Response is quick in E C machines as compared to Hydraulic machine. E C absorption unit is selected considering the compactness of the system. These are electromagnetic load devices It uses the magnetic field generated by an energizing coils The toothed rotor rotating in this field applies the load on the vehicle 2015, IERJ All Rights Reserved Page 2

Load can be varied by changing current in the energizing coil. iii. Torque indication system In all cases, a torque arm is attached to the absorption unit, at a fixed distance from its center. The load cell at the end of the torque arm experiences the force due to the reaction on the casing of the unit Torque can be measured by : Torque = Force x Distance Knowing the speed of the vehicle, H P can be found by the relationship H P = (torque * rpm) / Dyno constant The dynamometer specified here is designed to permit the operation of checking the performance of two wheeler vehicles in a compact space in a manner which simulates actual road load operating conditions such as vehicle frictional loss, vehicle and rider inertia, tyre rolling resistance and aerodynamic resistance. Torque measurement:- Inertia of dynamometer rotor I kg/m 2 Rate of increase in speed N rpm/s Input torque to dynamometer T 1 Nm Torque measured by dynamometer T 2 Nm\ T 1 -T 2 = 2ΠNI / 60 Nm IV.DESIGN REQUIREMENTS The two wheeler chassis dynamometer is primarily being concentrated on the testing for different parameters and accordingly tuning of the two wheeler vehicle. The dynamometer must be capable of simulating road load and of one of the following classifications: A) Dynamometer with fixed load curve, i.e., a dynamometer whose physical characteristics provide a fixed load curve shape. Chassis Dynamometer with fixed load curve: the load simulator shall be adjusted to absorb the power exerted on the driving wheels at a steady speed of 40 km/h. This is not a preferred type of B) Dynamometer with adjustable load curve, i.e. a dynamometer with at least two road load parameters that can be adjusted to shape the load curve. Dynamometer with adjustable load curve: the load simulator shall be adjusted in order to absorb the power exerted on the driving wheels at various steady speeds. This is a preferred type of C) It shall be equipped with means to simulate inertia and load. These simulators shall be connected to the front roller, in the case of a two roller V. AIR COOLED E C DYNAMOMETER a Air-Cooled Eddy-Current Absorbers offer very quick load control, moderate inertia, and high specific load capacity, especially in the lower RPM working ranges of most industrial-type engines. Its self-cooled rotors require no external water supply. It is researched and developed based on need of automobile test equipments like two wheeler chassis dynamometer, emission testing equipment and in instruments which uses a load and torque measurement. The parameters used for selecting the absorption unit are as follows- - Power requirement - Torque requirement - Compactness of the system For two wheel vehicle specification the torque and power requirement is considered. The specifications of 149 cc vehicles are collected as maximum torque in the range of 12Nm at 5500 rpm. For this specification the air cooled power absorber unit having maximum torque of 27 Nm at maximum admissible rpm is selected. D) The roller shall be fitted with a revolution counter with reset facility to measure the distance actually covered. Performance Curve 2015, IERJ All Rights Reserved Page 3

Fig 2: Isometric view of retarder in Creo 2.0 Steel AISI 1020 Cold Rolled Aluminum 1050-H14 Aluminum Steel ASTM A36 Stainless steel AISI 1020 Cold Rolled Fig 3: Expanded view of power absorber unit Fig 5 Two wheeler on Test Bed Platform Fig 4 Assembly Drawing of the Retarder Fig 6- Arrangement of roller retarder below the bed VI.TEST BED PLATFORM a. Test Bed Platform designed considering all the types of loads which are produced by vehicle and retarding forces of The major design requirements of test bed platform are: a. - Vehicle weight and carriage b. - Rotating forces generated by retarder c. - Space reduction (compactness) The design of platform is taken in to consideration of compactness of the system. It is made suitable to accommodate, roller, power absorption unit, pneumatic cylinders for wheel clamping arrangement. Selecting Materials- The total weight exerted on the platform of the chassis dynamometer is approximately around 2943N. Accordingly materials selected based on their mechanical properties are- Fig.7 Conceptual drawing of test bed platform. Front wheel clamping arrangement- It consists of brackets moving in-out (Clamp-de clamp position). Clamping brackets are mounted on the sliding guides & are moved pneumatically. Brackets are provided with sliding base to adjust the wheelbase, if required when the test vehicle is changed. Rack and pinion arrangement is provided to synchronize the clamps bracket motion. The air supply is 5.5 bars to operate the pneumatic mechanism. 2015, IERJ All Rights Reserved Page 4

Drive Shafts- Also known as propeller shaft or cardan shaft & used for mechanical power transmission from engine to Data required for calculation to select a suitable shaft is -Speed range & torque characteristic of engine to be tested -Rotational inertia of engine - Load factor with reference to nominal rating of shaft -Maximum engine torque -Whirling of shaft -Degree of misalignment of engine & dynamometer Wrong choice of cardan shaft may give rise to following problems- -Torsional oscillations - Vibration of engine or dynamometer - Whirling of shaft - Imposition of axial load on bearings of engine or dynamometer Never make any alteration in the original shaft. Never re-weld the cardan shaft. VII.CHASSIS DYNAMOMETER OPERATION Vehicle is driven onto the roll set of the chassis Vehicle is secured either using a strap/chains or free wheel clamping device As a safety, rotating wheels should be covered with a wire net to prevent accident due to escaping of a boulder stuck in the tire. The vehicle then performs a series of tests. These conditions are those the vehicle would face during its intended use. Automated tests are also possible depending on the control system, supplied with the chassis Two wheeler engines are air cooled Tests on two wheeler for Brake testing. Speedometer testing. Acceleration Time Measurement. To measure the maximum velocity of the vehicle The retarder is mounted below the test bed platform so the system becomes compact. The use eddy current retarder instead of hydraulic retarders is the reason for the compactness of the dynamometer system. ACKNOWLEDGMENT I would like thank the many people who have contributed to this research. I would like to thanks my advisor Prof. K.M. Narkar for sharing his knowledge with me and for providing me with much guidance, support and encouragement. a REFERENCE [1] Martyr, A and Plint, M.A., Engine Testing: Theory and Practice, 3 rd ed., Elsevier Ltd. Burlington, 2007, pp. 452-480. [2] Mate, N.R and Dhande, D.Y., A study of the two wheeler retarder type dynamometer system, Int. Journal of Innovative Research in Science, Engineering and Technology, 2014, 3(2), pp. 9057-9061. [3] Su, D.T., Shiao.,Y.S. and Yang., J.L.,Design and implementation of a chassis dynamometer for testing battery-powered motorcycle, WSEAS Trans.,2008, 7(10), pp. 879-889. [4] Jirawattanasomkul, J., and Koetniyom, S., Design and development of road load conditions for chassis dynamometer, International Conference on Production, Materials and Automobile Engineering, King Mongkut University North Bangkok, Bangkok, Thailand, 2012, pp. 153-157. [5] Yunda, H.U., The research on test-bed test system of automobile eddy current retarder, International Conference on Future Electrical Power and Energy Systems, zhejiang industry &trade vocational college, Wenzhou,China,2012,pp.1351 1357. [6] Patent no. 3,940,978, United States,Mar.2,Motorcycle Dynamometer, 1976. VIII.FUTURE WORK Assembly of all fabricated parts. Testing of the assembly. Testing vehicle performance on chassis Results and conclusions. IX.CONCLUSIONS In this paper the designing aspects of the chassis dynamometer system are considered to avoid its complexity. The roller is which is driven by vehicle wheel is absorbing the power. This power is drive by belt drive to the retarder. 2015, IERJ All Rights Reserved Page 5