Rear suspension for rear vehicles 433180 - drawings

Contents

Content.

Introduction

1. Information on the prototype of the designed car

2. Theoretical justification of suspension type selection

1.1. Purpose, design requirements, classification

2. Main suspension parameters.......................................................................... 7 2.1. Calculation of suspension operating properties

3. Calculation of lateral stability of the car

3.1. Calculation of stabilizer

3.2. Calculation of springs

Conclusion

List of literature

Graphics Applications

Introduction

It is required to calculate the rear suspension for the ZIL 433180 car. Car suspension is necessary primarily to reduce the dynamic effects transmitted from road irregularities to the driver and passengers, transported goods and the car itself. The quality of the suspension not only determines the smoothness of the car, but also has a significant impact on other performance indicators: stability, cross-country ability, reliability, durability, etc. The speed of cars on uneven roads is usually limited not by the available engine power, but by the quality of the suspension. Thus, insufficient smoothness leads to a decrease in the performance of the car. The initial data for optimal design are: the total mass of the vehicle ma; parameters of layout scheme, running gear, ground clearance, number and diameter of wheels, hardness module of suspension in static position, selected on the basis of estimate of smoothness of running. The modern theory of vehicle compression has an apparatus that allows you to cordon off the smoothness parameters according to the given parameters and characteristics of the suspension elements. In design calculation, stiffness and resistance of shock absorbers are chosen approximately, their values are specified after design estimate of smoothness of travel under specified operating conditions .

2. Theoretical justification of suspension type selection

2.1 Purpose, design requirements, classification.

The suspension elastically connects the frame or body with the bridges (wheels) of the car, taking up vertical forces and ensuring the necessary smoothness of travel. In addition, it serves to perceive longitudinal and transverse forces, as well as reactive moments and consists of elastic elements, guide devices and shock absorbers. Elastic elements soften dynamic loads, perceive and transmit to the frame normal forces acting from the road, ensure smooth running of the car. In order to obtain good smoothness of travel, the natural frequency of oscillations of the sprung mass of the car on the suspension in the entire range of operational loads must be low:

cars: 50÷70 stake/min. (0.8÷1.2 of Hz);

trucks: 70÷100 stake/min. (1.2÷1.9 of Hz).

This corresponds to the level of beating of the human pulse with fast walking.

Guide device receives longitudinal and lateral (lateral) forces acting on wheels and their moments. The kinematics of the guide determines the nature of movement of the wheels relative to the frame and affects the stability and pivotability of the car.

Shock absorbers dampen vibrations of compressed and unsprung masses. In some suspensions, side roll stabilizers are strengthened, which reduce the transverse tilts of the body when turning the car.

Suspension requirements are as follows:

ensure optimal characteristics of elastic elements, guide devices, shock absorbers and stabilizers;

optimal natural frequency of body oscillations, determined by static deflection value fst, which, in turn, determines smoothness when driving on roads with a flat and hard surface;

sufficient dynamic factor fd, which excludes impacts to deflection limiters. This parameter determines the limit speed of the car on uneven roads without hitting the limiter;

the most rational design forms and dimensions of all suspension units and parts, sufficient strength, reliability and durability of parts and other suspension elements;

fast attenuation of body and wheel vibrations;

counteracting roll during turning, "clues" during braking and "squats" during acceleration of the car;

constant track and angle of installation of pivots of controlled wheels, correspondence of kinematics of wheels movement to kinematics of steering drive, which excludes oscillations of controlled wheels;

reduced weight of unsprung parts of the vehicle and adaptation of wheels to irregularities of the track when crossing obstacles.

Suspension classification:

By elastic element type:

metal (leaf springs, coil springs, torsion bars);

pneumatic (rubber-cord cylinders, diaphragm, combined);

hydraulic (without back pressure, with back pressure);

rubber elements (compression, torsion).

According to the control device diagram:

dependent with a continuous bridge (autonomous, balancer for pressing 2 closely located bridges);

independent with cut bridge (with wheel movement in longitudinal plane, with wheel movement in transverse plane, candle, with wheel vertical movement).

According to the vibration damping method:

hydraulic shock absorbers (lever, telescopic);

mechanical friction (friction in elastic element and guide device). To obtain a soft suspension, it is necessary that the friction loss does not exceed 5%. Increased smoothness leads to deterioration of wheel motion kinematics, deterioration of stability and increase of wheels side roll.

According to the method of transmitting the forces and moments of the wheels: spring, rod, lever.

By the presence of a pivot: pivotal, pivotal.

Conclusion

During the course work, the following objectives were achieved:

- Familiarization, design and calculation of suspension

- Execution of assembly drawing of rear suspension, specifications and 3 parts of suspension.

During the course project, the software on the Personal Computer was widely used:

MS Word;

MS Excel;

KOMPAS V10;

Electronic Auto Catalog AutoSoft.

As a result of the calculations, the rear suspension was designed that meets the requirements of reliability, and smoothness of travel.