Front suspension of motor vehicle

Contents

Terms of Reference

Contents

Introduction

1. Overview of Quadrocycle Designs

1.1 Types of ATVs

1.2 Analysis of suspension prototype structures

1.2.1 Purpose and main parts of suspension

1.2.2 Dependent suspensions

1.2.3 Independent suspensions

1.2.4 Design Features

2. Select quad cycle nodes

2.1 Engine

2.2 Variator

2.3 Suspension

2.4 Gearbox

2.5 Wheel propeller

3. Calculation of the compression system

3.1 Construction of kinematic diagram

3.2 Spring calculation

3.2.1 Calculation of suspension parameters

3.2.2 Calculation of spring parameters

4. Calculation of damper parameters

5. Calculation of suspension lever by finite element method

Conclusion

List of literature

Introduction

The purpose of this project is to review the modern design of ATVs and develop a front wheel compression system for a two-seat tourist ATVs with a loaded mass of 500 kg, developing a speed of 6080km/h.

1.2 Analysis of suspension prototype structures

1.2.1 Purpose and main parts of suspension

The suspension elastically communicates between the vehicle carrier system and the bridges or directly with the wheels, softening the shocks and shocks that occur when hitting the irregularities of the road.

Vehicle suspension consists of elastic, guide and damping devices.

The elastic suspension device serves to reduce dynamic loads, mainly due to the action of part of the weight of the car on the wheels. When the wheel hits the irregularity of the road, the elastic suspension device is compressed, significantly softening the impact transmitted from the wheel to the body. When loosened, it imparts to the body vibrations which, by selecting an appropriate elastic device characteristic, can be given the desired character. Application of elastic device makes it possible to exclude copying profile of road irregularities by body and to improve smooth running of car, at the same time it is possible to move without unpleasant sensations and fast fatigue of people and damage of transported goods .

When a car moves, as a result of impacting the wheels on the irregularity of the road, body and wheel fluctuations occur. These vibrations are quenched by means of a shock absorber. The principle of operation of the hydraulic shock absorber is reduced to the conversion of mechanical energy of vibrations due to liquid friction into thermal energy and its subsequent scattering.

The guiding device transmits longitudinal and transverse forces and their moments. It determines the movement of the wheels relative to the vehicle frame. By the type of guide device, suspensions are divided into two main groups: dependent and independent.

1.2.2 Dependent suspensions

Dependent suspensions are most often installed on cargo trucks, where their large sizes are not so important, in our case it is not advisable to use them.

Benefits:

1. simplicity and cost-effectiveness of manufacture

2. no changes in track, descent and collapse during suspension, which causes a decrease in tire wear and improved stability of the car on icy and slippery roads.

3. No change in wheel collapse during body roll during cornering.

Disadvantages:

1. large beam mass if the main gear is in it

2. tendency to take away on a road with transverse waves

3. interconnectedness of wheel positions.

1.2.3 Independent suspensions

Consider independent suspensions as the most common on cars and most often used on motor vehicles.

Benefits:

1. Reduced tendency of front wheels to oscillations around pivots and body tilts

2. when the wheel hits an obstacle, movement of one wheel caused by road irregularities does not cause movement of the other wheel;

3. suspension makes it possible to use elastic elements of lower rigidity, since the value of oscillations in independent suspension is not limited by the distance between the axle and the frame;

4. reduced weight of unsprung parts;

5. higher stability.

Considering all the advantages, we will develop an independent suspension for a four-wheeled car.

1.2.4 Design Features

In connection with the small weight and dimensions of the quad cycle, we will develop an independent two-lever suspension with the support of the elastic element and the shock absorber on the lower lever.

The front suspension is independent, on A-shaped steel levers, with helical coil springs, single-tube telescopic hydraulic shock absorbers of two-sided action.

The upper and lower levers have a similar structure: at the ends on the side of the frame, cylindrical eyes are made for rubber-metal hinges (silentblocks), and on the opposite side - a platform with two holes for attaching a ball support. Ball supports of upper and lower levers are interchangeable and unified with lower ball supports of suspension of A-class VAZ vehicles (OKA family). Support is attached to lever together with anther and pressure plate by two bolts with spring washers and nuts. Threaded ends of pins of both upper and lower supports are directed downwards and enter cone holes of turning cam. Fingers are attached by self-locking nuts. Thus, the pivot cam can rotate about an axis passing through the centers of the ball pins.

Suspension levers, in turn, can be turned in fasteners to the frame within the travel of rubber-metal hinges (limited by their elasticity). The levers are welded to the frame and made identical for the upper, lower levers and shock absorber for unification purposes.

Suspension spring rests from below on cup welded to shock absorber body and from above on support cup welded to shock absorber rod .

The convergence of the wheels contributes to the correct position of the controlled wheels at different speeds and angles of rotation. The convergence of the wheels is controlled by changing the length of the side steering rods by rotating the adjustment clutches with weakened clamps.

2. Selection of quad-cycle units

2.1 Engine

The engine is four-stroke, two cylinder, liquid-cooled.

A four-stroke engine compared to a two-stroke engine has a longer life, it is more economical than a two-stroke engine, as well as its noise level is much lower. The four-stroke engine does not require the use of a complex exhaust system, and the purity of the exhaust is higher.

Engine grade - BRP650

Volume - 650cm3

Type - 4-stroke

Number of cylinders - 2

Cooling - Liquid

Maximum power - 40.5kW (55l.s.) at n = 7500rpm.

Maximum torque - 58 Nm at n = 5500 rpm

2.3 Suspension

The front suspension is two-lever. Upper A-shaped forged levers made of aluminum alloy. Travel of the front suspension is 208mm.

The rear suspension is independent and forms a clearance of 210 mm. Anthers and SHRUS are covered with shields - they extend their lifespan. Rear suspension shock absorbers are adjusted by spring pre-tension.

The rear suspension stroke is 228mm.

The choice of suspension is based on its good possibility of arrangement on a quad bike, increased stability, ensuring high smoothness of travel, due to a strong decrease in lateral swing .

2.4 Gearbox

Reverse box with chain gear.

Reverse gearbox is intended for transmission of torque from gear shaft of gearbox to shafts of main gear, by means of cardan gears, and also for realisation of reverse travel of quadrocycle at constant direction of rotation of engine crankshaft and disconnection of engine with running gear.

2.5 Wheel propeller

Wheel dimensions and tyre dimensions were selected in accordance with the specification. These tires are used on tourist ATVs of various companies.

Wheel dimensions: 640x260mm R13.

Conclusion

As a result of this work, a two-lever independent suspension was developed for a quad bike with a maximum loaded weight of 500 kg, this suspension scheme was chosen after reviewing modern quad bike designs. The kinematics of the suspension in the SolidWorks program was worked out. A calculation was made of the elastic and damping suspension elements, which showed the operability of this structure. A three-dimensional model of the lower suspension lever was created, with the help of which a strength calculation of this suspension element was carried out.