Challenge

Project

KKiran Jadhav16 Jun 2022

System level simulation of all terrain vehicle.

Simulink model for Bajaj ATV with CVT

Major components in the model -

Continuously Variable Transmission drive(CVT) :

It is better to have a more gears in a transmission, since it can optimize engine speed in a variety of driving conditions. That means low gear can provide better acceleration while higher gears can optimize fuel economy. CVT's differ from traditional automatic transmission in that they dont have a gear that provide steps between low and high speed operation. Instead, the majority of them work via a pair of veriable diameter, cone-shaped pulleys connected by a steel or composite bellt. The halves of each pulley are alligned 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.

Connections 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 controller are included. The throttle input signal T lies between zero and one and one and specifies the torque demanded from the engine as a fraction of the maximum possible torque.

Connection F and B are mechanical rotational conserving parts associated with the engine crankshaft and engine block, respectively. Connection P and FC are physical signal output ports through which engine power and fuel consumption rate are reported.

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 -

Vehicle speed :

It is clear from the graph that vehicle reach at maximum speed at full throttle and after few seconds and reamin constant. The brake input value is zero hence no effect on the velocity.

CVT SHAFT RPM:

These graph shows the variation in angular velocity of the input and output shaft of the variable gear transmission system. These values is differ with respect to gear ratio.

SIMULINK MODEL FOR BAJAJ ATV WITH CVT USING DASHBOARD :

In this model we have a dashboard which contains knobs to control the input. In this case, the input Throttle and Brake are not provided using signal builder. A knob is provided to control both the parameter in ral time for the user.

Output -

Vehicle speed:

It can be obsereved from the graph that the velocity increases drastically from 0 to 50 kmph when throttle value is 0.5 and brake input is 0. After the some point velocity decreases at 0 constant throttle value. This explain the direct relation of vehicle velocity with respect to throttle and brake input.

CVT SHAFT RPM -