Project

AIM: To Evaluate the vehicle velocity and studied behaviour of the primary rpm and secondary rpm by changing the CVT Ratio.

Requirements: Matlab, Simulink, Simscape, excel for Lookup tables.

By using the default model from the mathsworks. we are download the zipfile related to the matlab simulink models.From the zip file we are extract the simulink models. and then run the simulink for the models with the different methods.

CVT ( Continuously Variable Transmisson) Model:

In this model we have the generic engine block, CVT block,simple gear, vehicle body, engine sensor, mechanical rotational reference, solver, signal builder. The input signal from the signal builder block to the generic engine. In the cvt block we hve the input shaft inertia and output shaft inertia blocks and variable gear ratio. In the vehicle body block we have the tyre model, wind speed, Inclination an brake.The engine torque vs speed curve are plotted.The simple gear is set a default value as example(10). Click on the run icon. the sample time of the simulation time period is 200 sec.

output: The output of the waveform of vehicle speed is straight line at the start and aftersome time it is exponetially increase say 35 sec .from 35 sec to 200sec the vehicle speed as constant as per the wave form.

The input of the signal builder 1 is given to the engine the input of the signal builder is 0.3 to 20 sec it is low and after 20 sec to 200 sec linear at 1. The signal builder 2 is at zero .we assignthe brake input as zero.

In the CVT it is consists of primary pulley and variator and the secondary pulley and belt.so the variator which is connected to the primary pulley goes outward the variator of the secondary pulley moves inward such that the radius of the secondary pulley is more than the radius of the primary pulley that will lead to the speed reduction.

On the other hand when the variator of primary pulley move inward and the variator of the secondary pulley moves outwards and it will lead to over drive.

For this example the engine torque and speed is at 3840rpm as shown in the plot of the enginetorque-speed block.

This model is also called as open loop model. There is another model called closed loop model. for this the input of the cvt is given from the feed back of the output of the vehicle body.

In this a block is added called the lookup table visualization. In this table we will have a script in the matlab command window.click on the run after that go to the simulink model.

In the simulink dashboard we have the throttle input and brake input roatary switch and the velocity and rpm display are present. By click on the run icon the simulation is running for the infinty time period. At that time the knob of the throttle is set to 0.3 and brake input to 0 and plot the graph.

The throttle input at 0.3 and brake input at zero and the velocity of the vehicle at slightly above 40kmhr are shown in the graph.

In the CVT Model of the ct ratio of the rpm. In this the lookup table is given to the cvt input ,click to run icon and simulate for the 50 sec.the gear ratio is set to 10.after simulation the graph is velocity of the vehicle islinearly increasing and runs constant at 60.In this model we assign the throttle value is 1. and the brake value is zero(0). so the distance repesents in the graph is linearly increases up to the sample time.

we want to see the parameter of the cvt ratio primary and secondary and velocity in one plot and we may click on the data inspector.so that the data inspector will shown the graph accordingly. For that we may need to lock the signal.

For the above said models for cvt model i had simulate for the 10gear ratio and 15 gear ratio.For the lookup table the run simulation and the graph are obtained for the throttle input 0.3 and 0.5.For the lookup tabele and lookupdata should be implement in the matlab script file then only the simulink model is run. otherwise it shows a error signal. By changing the throttle input the vehicle speed is incerased.

Conclusion:

The behaviour of the primary rpm and the secondary rpm, vehicle velocity are changing by the CVT ratio is/are studied/observerd.

For the case: I had noticed that we change the gear input and obtianed values. And also in the dashboard. when the simulink of the (cvt-model--mapped-dashboards-lookuptable) output of the vehicle is feed back to the input of the cvt than we change the throttle input the vehicle speed is increased as dhown in the graphs.

These are observation i had noticed in this model/simulink files as per my knowledge.