Project

AIM:-

Carry out a system-level simulation of an all-terrain vehicle.

Keywords: CVT, Lookup table, Dashboard, baja ATV

SOFTWARE: MATLAB AND SIMULINK

OBJECGTIVE:-

1. Study Baja ATV model without dashboard.
2. Study the baja ATV model with dashboard.
3. Study the baja ATV model using Lookup table without dashboard.
4. Study the baja ATV model using Lookup table with dashboard.

INTRODUCTION:- Transmission, which transmits the power from engine to wheel through the shafts. It consist of four types only.

1. Manual transmission.
2. Continous variable transmission.
3. Semi-automatic transmission.
4. Automatic transmission.

A continous variable transmission, or CVT, is a type of automation transmission that provides more usable power, better fuel economy and a smoother driving experience then a tradetional automatic transmission. the CVT is a system that makes it to possible very stepless the transmission ratio without interruption of the torque flow. Therefore an infinite number of ratios (between a minimum and maximum value) are possible. it is an automatic,single speed, and gearless transmission that can shift throught an infinite number of gear ratios. This ability to seamlessly shift through these different gear provides a number of benefits including extremly smooth shifts and exceptional fuel economy. A CVT draw top engine power from a small engine, which gives drivers quicker acceleration than standerd automatic transmissions. Because of their greater ability to control the engine speed range,CVTs produce fewer emission. CVTs are also lighter weight than traditional automation transmissions.

STUDY 1:

By using simulink model of CVT consists of Signal builder, generic engine, motion sensor,vehicle transmission, vehicle body,tyres and solver configuration blocks etc., as shown in figure-1. The CVT subsystem includes Transmission block,input and output shaft interia and motion sensors as shown in figure-2 The vehicle body sybsystem includes vehicle body block,double drum brake and tyre as shown in fig-3. The initial engine speed is given as 2100 rpm, mechanical rotation for driver pulley as 0.8 & 0.7 respectively. The mass of the vehicle as 250kg and 2 axels which connects 4 wheel accordingly.

Figure-1

Figure-2

Figure-3

The signal builder is used as input for broke,throttle and gear ratio. Brake input is maintained as 0 for overall simulation. The throttle input is given as 0.3 for 20 secs and increases to 1 for overall simultauion. The throttle valve is mainly to control the flow or amount of fuel into the engine. if the throttle valve increases the flow of fuel increases to the IC engine which intum increases the power of the engine. The gear ratio is maintained as 2.3 for 5 secs and linearly decreases to 1.8 and maintained constant for overall simultation as shown in figure (4-5).

Figure-4

Figure-5

Study 2:-

The above figure shows 'Baja ATV with dashboard' model which constains throttle meter and broke input in the dash board instead of giving input through sognal builder. Rest of the blocks and subsystem are common in the above baja ATV model without dash board as shown in fig 2 & fig 3. The main concept of using dash board is study the result by varying the input of broke and throttle. which shows that the velocity and speed of the engine. The gear ratio is maintained as 2.3 for 5 secs and linearly decreases to 1.8 and maintained constant for overall simulation as shown in fig 5. As the broke input varies from 0-0.5, the velocity and speed decreases accordingly. BY increasing the throttle, the velocity and speed of the engine & shaft increases.

Study 3:-

By using simulink model of CVT consists of step time,generic engine, motion sensors, vehicle transmission, vehicle body,tyres and solver configuration blocks etc. as shown in figure-7. The CVT subsystem includes look up table, Transmission block, input and output shaft interia and motion sensors as shown in figure-8. The vehicle body subsystem includes vehicle body block, double drum brake and tyres as shown in figure-9 The initial engine speed is given as 2100 rpm, mechinical rotation for driven pulley as 0.8 & 0.7 respectively. The mass of the vehicle as 250kg and 2 axles which connects 4 wheels accordingly.

A lookup table is an array of the data that maps input values to output values, therby approximately a mathematical function. Given a set of input values,a lookup operation retrieves the corresponding output values from the table if the lookup table does not explicity define the input values,simulink can estimate an output value using interpolation extrapolation, or rounding, where:

• An interpolation is a process for estimating values that lie between known data points.
• An extrapolation is a process for estimating values that lie beyond the range of known data points.
• A rounding is a process for approximating a value by altering its digits according to a known rule.

Figure-1

Figure-2

Figure-3

The brake input and throttle input is given by step time, Which depends on the run time and varies accordingly. By using Lookup table for gear ratio which takes as input to the CVT and works according to the user input gear ratio and obtained the output. this method is very effective which can avoid the unusual torque at the certain speed and very easy to archieve greater velocity & engine speed. it works as closed loop when the input is given by lookup table. The simulink get the input value from lookup table and obtained the result according to the input values of gear ratio. The gear ratio varies from 2.3 to 1.8 as taken as input and output interms of velocity. The maximum velocity reached as 57 kmph approximately.

Figure-4

Study 4:-

The above figure shows 'Baja' A TV with dashboard model using lookup table which contains throttle meter and break input in the dash board and indicated as constant block. Rest of the blocks and subsystems are common in the above baja A TV model without dash board as shown in figure 8 & figure 9. The main concept of using dash board is study the result by varying the input of break and throttle, which shows that the variation of the velocity and speed of the engine. The gear ratio is given by lookup table, simulink get the input value from the lookup table and obtain the result according to the lookup table. As the break input varies from 0- 0.5, the velocity and speed decreases accrodingly which inturn the gear ratio also decreases engine & shaft increases. the trannsmission as primrary pulley and secondary pulley, in which the radius of primrary pulley increases by compacting and the radius of secondary pulley decreases. As the gear ratio varies, the torque also varies. Gear ratio is directly propotional to the torque, which increases by increasing the gear ratio. At the max torque, the speed and velocity is decreases.

OUTPUT:

Study 1:- Variation of Velocity & Shaft Speed

In the above figure, the break is maintained as constant and increases in throttle which shows increases in velocity. The flow is increases when the throttle increases from 0.3 to 1, thus the power in the engine increases. the torque reaches approximately 7N-m at 1.8 gear ratio, which defines that gear ratio is directly propotional to the torque. By this gear ratio, the speed & velocity can archive maximum.

In the above figure, the primrary shaft reaches high and secondary shaft as low rotational speed because the radius of the primary shaft as move than the secondary shaft, the speed is directly propotional to the radius of the shaft. As the radius increases the speed of the shaft also increases.

Study 2: Variation of Velocity and Shaft Speed

In the above figure, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 and varying by increasing the value of throttle which increases the velocity of the vehicle, By increasing the brake input, the velocity of the vehicle decreasing accordingly which shown in figure14.

In the above figure, the primary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft. The radius of the primrary shaft as more than the secondary shaft, the speed is directly propotional to the radius of the shaft. As the radius the speed of the speed of the shaft also increases.

Study 3:- Variation of velocity & shaft speed

In the above figure, the broke is maintained as constant and increase in the throttle which shows increase in the velocity. the flow of fuel is increases when the throttle increases from 0.3 to 1, thus the power in the engine increases. The torque reaches approximately 7N-m at 1.8 gear ratio is directly proportional to the torque. By this gear ratio, the speed & velocity can achieve maximum. The gear ratio is assigned in lookup table and given as input to simulink which reads every input value and obtained the result according to the input.

In the above figure, the primrary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft. The radius of the primrary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the radius increases the speed of the shaft also increases.

Study 4:- Variation of velocity & shaft speed

In the above figure, the velocity of the vehicle is maintained as constant for constant throttle value as 0.3 and varying by increasing the value of throttle which increases the velocity of vehicle. By increasing the brake input, the velocity of the vehicle decreasing accordingly which shown in figure18. By using lookup table, it works as closed loop by recording the value and we can get at any particular value of gear ratio which is beyond the range or any random value within the range by using extrapolation by lookup table.

In the above figure, the primrary shaft speed increases by increasing throttle and decreasing by increasing brake input value, which defines that the throttle can flow more amount of fuel which increases the power of the engine and similar to the secondary shaft. The radius of the primrary shaft as more than the secondary shaft, the speed is directly proportional to the radius of the shaft. As the radius increases the speed of the shaft also increases. The throttle value and brake input value can be varying in dashboard, so we can get any particular value for input.

CONCLUSION:

1. As the throttle increases, the velocity also increases which inturn the power in the engine also increases.

1. In the above figure, at the beginning the speed reducing because of the gear ratio and torque output. when the gear ratio increases, the torque increasses.
2. As the brake input increases, the velocity decreases and engine power also decreases.At a certain brake input value the engine may shut down and there is no power output. The engine power is inversly proportional to the brake input.

3. As the gear ratio increases, torque increases which inturn the velocity decreases.

   In the above figure, the torque is increasing by increasing in engine speed. At a particular point the torque is decreasing when the gear ratio increases in order to archieve maximum velocity.

   In the above figure, the velocity is varying wrt the gear ratio. for the high gear ratio, the torque is more which decrease the velocity. By changing to high gear, the gear ratio become less paralelly the torque also less which can get high velocity.

4. With help of lookup tabe, we can vary any input value and also get the output value by using interpolation and extrapolation method which the simulink can solve.