Project

All Terrain Vehicle

An all terrain Vehicle (ATV) is defined as a motorized off highway vehicle designed to travel on four low pressure or non pneumatic tires, having a seat designed to be starddled by the operator and handelbars for streeing control.

Study #1

Case 1:

SIMULINK MODEL FOR BAJAJ ATV WITH CVT:

Major Components in the Model:

Continuously Variable Transmissin Drive (CVT)

It is better to have more gears in a transmission, since it can optimize engine speed in a variety of driving conditions. That means low gears can provide better acceleration while higher gears can maximize fuel economy. CVTs differ from traditional automatic transmissions in that they don't have gears that provide steps between low and high speed operations. Instead the majority of them work via a pair of variable diameter, cone shaped pulleys connected by a steel or composite belt. The halves of each pulley are aligned with with the pointed ends of the cones touching. These form a V shaped groove in which the connecting belt rides. One side of the pulley is fixed, and the other side is movable, actuated by a hydraulic cylinder. The cylinder can increase or decrease the amount of space between the two sides of the pulley. This allows the belt to ride lower or higher along the walls of the pulley, depending on driving conditions, thereby changing the gear ratio.

CVT Block:

Variable Transmission Ratio

Represents a variable ratio gearbox such as implemented by mechanical belt CVT, electric or hydraulic transmissions. The physical signal input r defines the ratio of input to output angular shaft velocities.

Connection B(base) and F(follower) are mechanical rotational conserving ports. Specify the relation between base and follower rotation directions with the Output shaft rotates parameter.

Engine

Represents a system level model of spark ignition and diesel engines suitable for use at initial stages of modelling when only the basic parameters are available. Optional idle speed and red line controllers are included. The throttle input signal T lies between zero and one and specifies the torque demanded from the engine as a fraction of the maximum possible torque.

Input Signal

A signal builder is used to create signals for brake and throttle

CVT gear Ratio Input

Torque Vs Engine Speed Input

VEHICLE BODY

Output for Case 1:

VEHICLE SPEED

It is clear from the graph that the vehicle attains its maximum speed (V= 55km/hr) at full throttle = 1 after 30 seconds and then remains constant. The brake input value is zero, hence it has no effect on velocity.

CVT SHAFT RPM

This graph shows the variation in angular velocities of input and output shafts of the variable gear transmission system. These values differ with respect to the gear ratio.

STUDY # 1

CASE 2 

SIMULINK MODEL FOR BAJAJ ATV WITH CVT USING DASHBOARD

In this model we have dashboard which contains knobs to control the inputs. In this case the inputs - Throttle and Brake are not provided using signal builder. A knob is provided to control both the parameters in real time for the user.

OUTPUT FOR CASE 2

VEHICLE SPEED

It can be observed from the graph that the velocity of the vehicle increases drastically from 0 to 50 Kmph when throttle value is 0.5 and brake input is 0. Once the braking value increases from 0.1 to 0.5, the velocity of the vehicle decreases to 0 at constan throttle value. This explains the direct relation of vehicle velocity with respect to throttle and brake inputs.

CVT SHAFT ARAM

STUDY #2

CASE 1

SIMULINK MODEL FOR BAJAJ ATV WITH CVT USING LOOKUP TABLE 

CVT BLOCK

The only difference between this model and the first model is that in this model, the gear ratio input to CVT is provided using a lookup table. The vehicle velocity and shaft RPM outputs are same as before.

CVT GEAR RATIO

LOOKUP TABLE VISUALISATION

OUTPUT FOR CASE 1

VEHICLE SPEED

CVT SHAFT RPM

Both results are same as that of the first case - SIMULINK MODEL FOR BAJAJ ATV WITH CVT since the input parameters are same.

STUDY #2

CASE 2

SIMULINK MODEL FOR BAJAJ ATV WITH CVT USING LOOKUP TABLE AND DASHBOARD

In this model a dashboard is used to control the inputs - Throttle and brakes with Knobs.

OUTPUT FOR CASE 2

VEHICLE SPEED

This graph is similar to that of CVT dashboard case. The variation in the vehicle velocitycan be observed with change in throttle and brake inputs. With increase in braking value , the speed of vehicle decreases. On the other hand, increasing the throttle leads to increase the vehicle velocity.

CVT SHAFT RPM

This graph indicates the variation in rpm of primary and secondary shafts with respect to input parameters.

CONCLUSION

Thus we have successfully analysed 4 different models of BAJAJ ATV WITH CVT and recorded the outputs (Vehicle velocity and CVT shaft RPM) with respect to variations in input throttle and brake.