BRAKING SYSTEM DESIGN FOR ALL TERRIAN VEHICLE (ATV)

Transcription

1 International Journal of Mechanical Engineering and Technology (IJMET) Volume 9, Issue 4, April 2018, pp , Article ID: IJMET_09_04_112 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed BRAKING SYSTEM DESIGN FOR ALL TERRIAN VEHICLE (ATV) Boddu Raviteja, Nakirikanti Nitesh, Ganti Pavan Kumar and Gujjula Haravind Reddy B.Tech, Department of Mechanical Engineering, Sreenidhi Institute of Science and Technology, Yamnampet, Ghatkesar, Hyderabad, Telangana, India ABSTRACT This main objective of this paper is to explain the Optimized design of Braking system for an ATV by using the Reverse Engineering Technique and enable us to obtain the various performance parameters. This also includes the Design Methodology which follows the order as Introduction, Selection of types of Brakes, Calculations, Benchmarking, Comparison Graphs, Conclusion and References. Key words: Braking System, ATV, Reverse Engineering, Braking Torque, Braking Force, Pedal Effort, Rolling Resistance. Cite this Article: Boddu Raviteja, Nakirikanti Nitesh, Ganti Pavan Kumar and Gujjula Haravind Reddy, Braking System Design for All Terrian Vehicle (ATV), International Journal of Mechanical Engineering and Technology, 9(4), 2018, pp INTRODUCTION A general misconception is that brakes are used to stop the vehicle but it s to decelerate the vehicle. Law of Conversation of energy is the main principle behind this system i.e. Kinetic energy is converted into heat energy via generation of friction. Brakes are classified into two categories namely a) Drum Brakes b) b. Disc Brakes But based on the actuation they are classified into many as illustrated below 1. Mechanical Brakes: Actuation by means of linkages / wires. This type can be seen in Bi-cycles and Motor-cycles. 2. Hydraulic Brakes: Actuation by means of liquid. This type can be seen in Motorcycles, Cars and Auto-rickshaw. 3. Pneumatic Brakes: Actuation by means of compressed gas. This can be seen in Heavy Commercial Vehicles and locomotives. 4. Electrical/Regenerative brakes: Actuation by means of electricity. This mostly seen in locomotives editor@iaeme.com

2 Braking System Design for All Terrian Vehicle (ATV) 5. Magnetic Brakes: Actuation by means of Magnetism power. 2. SELECTION OF TYPE OF BRAKES All the above mentioned types have their uniqueness but mostly Hydraulic brakes suits the most as they are easy to install, effective and less cost. Mechanical brakes are exceptional for ATV. Coming to Hydraulic brakes disc type is more efficient because less weight, easy to install, water drain capability and effective heat dissipation which cannot be find in drum brakes. Also most of ATV s are rear driven so inboard brakes are sufficient for rear side of vehicle and out board brakes for front side. Doing this improves the performance of the vehicle and also reduces the unsprung mass of vehicle. 3. CALCULATIONS 3.1. Pre-requisites (Assume) Track width- 50 and Wheel base- 54 Stopping Distance- 3mts Speed of vehicle- 60Kmph Centre of gravity location along 3-D axes longitudinally from the front wheels, 26 laterally from the left wheels and 14.5 vertically from ground. Weight of vehicle including driver Kg = 220Kg 3.2. Let s calculate the following step by step Total Kinetic Energy Angular displacement of wheel Total Braking force followed by its distribution to the front and rear side of the vehicle Parts dimensions abstraction and finally plotting performance graphs Total Kinetic Energy As it is previously assumed that weight of vehicle including driver is 220Kg. Total Kinetic Energy =Translational KE+ Rotational KE = 0.5xmxv xIxω 2 = 32, J (Approx.) m- Mass of vehicle v- Max. Velocity of vehicle I-Mass moment of Inertia ω- Angular velocity of rotating parts Angular displacement of wheel We have this from law of conservation of energy KE=BTx θ editor@iaeme.com

3 Boddu Raviteja, Nakirikanti Nitesh, Ganti Pavan Kumar and Gujjula Haravind Reddy BT- Braking Torque θ- Angular displacement = (BT f + BT r ) xθ = (r 1 * x BF f +r 2 * x BF r ) xθ = (r 1 * x k bf x BF t +r 2 * x k br x BF t ) xθ Here r 1 * =r 2 * =r * (Disc effective radius) = r * x BF t x θ x (k bf +k br ) = r * x BF t x θ x 1 KE= r * x BF t x θ (1) BT f & BT r Braking toque for front wheels and rear wheels We have a = dv/dt = dvxds/dsxdt = dv x (ds/dt) /ds a x ds = v x dv Integrating on both sides we get a x s = v 2 /2 (BF t /m) x s = v 2 /2 BF t = m x v 2 /2 x s (2) a Deceleration s Dtopping distance = 220 x /2 x 3 BF t = 10, N θ = c from (1) Brake force distribution If this is not distributed properly there are two situations can occur a) Only front wheels gets locked and it leads to loose direction control b) Only rear wheels gets locked and it leads to loose directional stability For avoiding these all the four wheels has to lock simultaneously and this is achieved by the following distribution Ideal brake force distribution K bf /k br = (b + h x (µ + f r ))/(a - h x (µ + f r )) (3) a,b,h are the locations of C.O.G longitudinally, laterally and vertically µ - Coefficient of friction f r Coefficient of rolling resistance Substituting all these we get k bf = & k br = editor@iaeme.com

4 Braking System Design for All Terrian Vehicle (ATV) Now BF f =k bf x BF t = N BF r =k br x BF t = 2, N Parts Dimensions abstraction Let s convert these values at wheels to rotor side as follows BF f = µ x BF fd (4) µ - Coefficient of friction between tyre and ground BF fd Braking force at rotor at front side of vehicle Similarly for rear side BF fd = BF f / µ = /0.6 = 12, N Similarly for rear side BF rd = BF r / µ = 4, N a. First let s find out the front side parts dimensions BF fd1 = 6, N BF fd1 = 2 x µ x CF CF Clamping force = 2 x 0.4 x CF CF = 7, N Let s consider dual piston caliper for the front side Then we have CF p = CF/2 = Clamping force per piston = 3, N F pr /A mcp = CF p /A cp (5) F pr /d 1 2 = CF p /d 2 2 d 2 2 /d 1 2 = CF p /F pr (6) F pr Master cylinder push rod force d 1 Diameter of mc piston d 2 Diameter of caliper piston = /2,646.9 = 2.95 d 2 2 /d 1 2 = 2.95 d 2 /d 1 = 1.71 (7) b. Rear side parts dimensions BF rd = 4, N editor@iaeme.com

5 Boddu Raviteja, Nakirikanti Nitesh, Ganti Pavan Kumar and Gujjula Haravind Reddy Let s have single acting caliper for rear CF p = 5, N d 2 /d 1 = 1.45 (8) 4. BENCHMARKING In this various parts are compared with others based on availability, cost & specification. Table 1 Rotor S.No. Diameter(mm) DER(m) Type Availability Cost(INR) Drilled Medium Drilled Medium Drilled Medium Drilled High Drilled High 1200 Note: We have selected 150mm for front side and 160mm for rear side Table 2 Brake Fluid S.No. Type Dry Boiling point Availability Wet Boiling point 1 DOT High DOT Medium DOT Low DOT Low 180 Note: DOT 3 suits our requirement Table 3 Master Cylinder S.No. Bore Diameter (cm) Type Availability Cost(INR) SP High SP High DP High DP Medium DP Low Note: SP Single piston DP Double piston Third one suits our requirement Table 4 Caliper S.No. Bore Diameter (cm) Type Availability Cost(INR) 1 2 SA, TA Low DA High SA, DA High Note: SA Single acting DA Double acting TA Triple Acting Second and third one suits our requirement editor@iaeme.com

6 Braking System Design for All Terrian Vehicle (ATV) Here the various combinations of parts are selected and assessed for its finalization and finally installed in the vehicle. 5. STOPPING DISTANCE VS SPEED Stopping distance is the distance travelled by the vehicle from the moment of deceleration to its final stop and it s the combination braking distance and reaction distance. Braking distance is the distance travelled by the vehicle from the moment of application of brake to its final stop. Note: Aerodynamic Effect is ignored in this calculation because it has no significant effect. And the values are obtained by assuming that the driver always applies constant pedal effort irrespective of speed i.e Figure 1 Stopping Distance (m) VS Speed (Kmph) BF t = m x v 2 /2 x s from (2) s = m x v 2 /2 x BF t m= 220Kgs v= Varies from 60 Kmph to 0 Kmph BF t = remains same always since the applied effort is constant. 6. DECELERATION VS SPEED It s very important factor for determining the load transfer and according to which parameters can be adjusted. During braking condition the following forces comes into picture i.e. Inertia force, Braking force and rolling resistance. Figure 2 Component of forces during braking condition editor@iaeme.com

7 Boddu Raviteja, Nakirikanti Nitesh, Ganti Pavan Kumar and Gujjula Haravind Reddy Balancing horizontal forces we get, md = BF f +BF r +RR f +RR r = BF t +RR t (Total Braking force + Total Rolling Resistance) d = BF t +RR t /m (9) From the above equation we can plot the following graph Figure 3 Deceleration (m/sec 2 ) VS Speed (Kmph) 7. WEIGHT TRANSFER VS SPEED It is the amount of load transferred to the front axle during braking condition(deceleration process) and we can also reduce this by implementing the Anti-Dive geometry in the vehicle and it reduces the chances of toppling(if any). Figure 4 Component of forces at the moment of deceleration Considering the moment equation w.r.t to any point can able to find out the Load transferred to the front and similarly we can also find the amount of load transferred to rear during acceleration case just by reversing the forces at C.O.G Figure 5 Weight Transfer (Kg) VS Speed (Kmph) editor@iaeme.com

8 Braking System Design for All Terrian Vehicle (ATV) REFERENCES Table 5 Overall Technical Specifications Parameter Value Stopping Distance 3 mts Pedal Ratio 6:1 Pedal Effort N 32 (longitudinal from front wheels) COG Location 26 (laterally from the right wheel) 14.5 (height) Mass of vehicle 268Kgs Master Cylinder Bore 19 mm Push Rod Force N Clamping Force Front N/disc Rear N/disc Braking Force Front N/disc Rear N/disc Rotor Diameter Front-150 mm Rear-160 mm Braking Torque Required per Wheel Front N-m/wheel Rear N-m/Wheel Deceleration 4g Stopping time 0.42Sec Pedal Travel 70 mm Max. Temperature raise in rotor Front K/Single stop Rear K/Single stop Brake Fluid DOT 3 Braking Circuit F/R Split Braking Circuit Balancing Simultaneous locking [1] [2] William F Milliken and Doglus L Milliken Wheel loads. Racecar vehicle dynamics, Society of Automotive engineers, Inc [3] ve_antilock_brake_systems_through_pi_and_neural_network_arithmetic. [4] Carroll Smith The Brakes. Tune To Win. Aero publishers, Inc [5] Dattatraya K Chavan, Anish S Gorantiwar, Kunal R Nalamwar and Ritesh G Deokar, A Comparative Study and Analysis of the Performance of Various Regenerative Braking Systems. International Journal of Mechanical Engineering and Technology, 8(3), 2017, pp [6] Aditya Patankar, Rohit Kulkarni, Sanket Kothawade and Sameer Ingale, Design and Development of a Transmission System for an All - Terrain Vehicle. International Journal of Mechanical Engineering and Technology, 7(3), 2016, pp [7] Dattatraya K Chavan, Anish S Gorantiwar, Kunal R Nalamwar and Ritesh G Deokar, A Comparative Study and Analysis of the Performance of Various Regenerative Braking Systems. International Journal of Mechanical Engineering and Technology, 8(3), 2017, pp [8] Gaurav A. Chandak and A. A. Bhole. An Electric Braking System Controller for Brushless DC Motor in Electric Vehicle Application. International Journal of Electrical Engineering & Technology, 8(4), 2017, pp editor@iaeme.com