Project
An all-terrain vehicle (ATV) is a motorized off-highway vehicle specifically designed for travel on four low-pressure or non-pneumatic tires. It features a seat that is designed to be straddled by the operator and is controlled using handlebars for steering.
Study 1;
Case 1;
Simulation model for BAJA ATV WITH CVT;
Major components in the model:
Continuously Variable Transmission (CVT):
A Continuously Variable Transmission (CVT) optimizes engine speed across various driving conditions by adjusting the gear ratio seamlessly. Unlike traditional automatic transmissions with fixed gears, CVTs utilize a pair of variable-diameter, cone-shaped pulleys connected by a steel or composite belt. Each pulley consists of movable and fixed halves, with the movable half controlled by a hydraulic cylinder. By adjusting the hydraulic pressure, the distance between the pulley halves changes, altering the effective diameter and allowing the belt to ride higher or lower along the pulley's walls. This variability in the gear ratio optimizes performance for acceleration and fuel efficiency without discrete gear steps found in traditional transmissions
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.
NGINE:
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 torque
Connection F & B are mechanical rotational conserving port associate with the engine crankshaft & engine block respectively connection p & Fc are physical output port through which engine power and fuel consumption rate are reported
Input signal
A signal builder are use to create break and throttle signal
CVT gear Ratio Input
Torque vs engine speed input
Vehicle body
For vehicle speed in Output case 1
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
Both the result same in 1st case
STUDY 1
CASE 2
Simulation Model for BAJA with CVT Using dashboard Table
OUTPUT FOR CASE 2
VEHICLE SPEED
It can be observed from the graph that the velocity of the vehicle increases drastically from 0 to 50kmph when throttle value is 0.5 & brake input is O. Once the braking value increases from 0.1 to 0.5, the velocity of the vehicle decreases to O at constant throttle value. This explains the direct relation of vehicle velocity with respect to throttle and brake inputs.
CVT SHAFT RPM
Study 2
Case 2
SIMULINK MODEL FOR BAJA ATV WITH CVT USING LOOKUP TABLE
CVT BLOCK
The only difference between this model and first model in that model CVT ratio in this input is provided using the lookup table.Vehicle velocy and shaft RPM are same in both case
CVT gear Ratio
LOOKUP table VISUALISATION
OUTPUT for Case 1
Vehicle speed
CVT SHAFT RPM
Both result are same as that the first case
SIMULINK MODEL WITH LOOKUP TABLE AND DASHBOARD
OUTPUT FOR CASE 2
VEHICLE SPEED
This graph similar to that cvt dashboard case. The variation in vehicle velocity can be observed with the change in throttle and brake input with increasing breaking value the speed oh vehicle decreases that is inversely proportional
CVT RPM
This graph indicates the variation in rpm of primary and secondary shafts with respect to input parameters
Conclusion:
In our analysis of four different models of BAJA ATVs equipped with CVT, we systematically recorded and compared the outputs—vehicle velocity and CVT shaft RPM—across varying throttle and brake inputs. Our findings consistently showed similar patterns of variation in both velocity and shaft RPM across all models tested. This exploration underscores the robustness and consistency of CVT performance in handling diverse driving conditions and input scenarios