BMW Car Calculation

Contents

Project Task

Technical specifications

Introduction

1. Terms of Reference

1.1 Selection and justification of initial data

1.1.1 Determination of the total weight of the vehicle

1.1.2 Determination of the number of car axles

1.1.3 Determination of vehicle axle load

1.1.4 Determination of center of gravity coordinates

1.1.5 Tyre selection

1.1.6 Mechanical transmission efficiency

1.1.7 Vehicle streamlining factor

1.2 Vehicle traction calculation

1.2.1 Determination of effective engine power and construction

engine external speed characteristic

1.2.2 Calculation of transmission gear ratios

1.3 Traction and operational properties of the vehicle

1.3.1 Traction and speed characteristics of the car

1.3.2 Dynamic characteristic (dynamic passport) of the car

1.3.3 Braking properties of the vehicle

1.3.4 Vehicle stability

1.3.5 Vehicle handling

1.3.6 Smooth running

1.3.7 Vehicle cross-country

1.3.8 Fuel economy

2. Sketched Design

2.1 Vehicle Layout

3. Technical Project

3.1 Kinematic calculation of steering gear

3.2 Steering Gear Design and Calculation

3.3 Steering Gear Design and Calculation

Conclusion

Literature

Applications: computer calculation results, graphics on A4 and A3 formats, car layout on A1 format, Main transmission on A2 format, detail on A3 format, specification on A format

Introduction

The purpose of the course project is to consolidate knowledge of the "Cars" discipline, acquire the skills to perform traction calculation of the car, learn to evaluate the perfection of the design of the main functional elements of the car and perform the necessary calculations to determine their design parameters.

Each student performs a course project according to an individual assignment, which he selects from the Appendix 1 (page 47, [1]). The job number corresponds to the last two digits of the workbook. In the task variant, the initial data for the design and the type of the designed car are indicated. In addition, according to Appendix 2 (page 51, [1]), the course project manager determines individually for each student the type of car unit design being developed.

The project consists of an explanatory note and a graphic part. The explanatory note must have all the sections that are in these guidelines. Its volume is 25-35 pages of A4 format. Necessary graphs and kinematic diagrams should be drawn on millimeter paper or computer graphics.

Graphic part - drawings of the structure of the unit (unit) specified in the task should be made in a pencil on sheets of A1 format. Drawings shall comply with ESKD requirements. It is allowed to perform separate drawings, schedules and development units using computer graphics, while complying with all the requirements of the ESKD. The graphic part of the coursework includes four sheets of the graphic part, which include the following:

- graphs to car traction calculation (external ICE speed characteristic, power characteristic, dynamic characteristic or dynamic passport, acceleration graph, time and acceleration path graph of the car) - 1 sheet of A3 format;

- layout diagram of the car in two projections - 1 sheet of A1 format;

- unit (unit) design - A1A2 sheet;

- unit development based on the results of patent search or literature review and working drawings of 2-3 original parts.

The final stage is conclusions and conclusions that help consolidate theoretical and practical knowledge of car design.

Terms of Reference:

Passenger capacity-5 people;

Maximum speed, m/s 45;

Rolling resistance coefficient, f0 - 0.014;

Wheel formula - 4x2;

Car class - middle class coupe.

Determine the number of car axles.

The number of axles of the designed car is selected, focusing on significant structural features, but at the same time, based on permissible loads on the axle due to the strength of road surfaces. The number of axes of the car is assigned from the specified conditions for heading work: 4x2 2 axes.

Mechanical transmission efficiency.

The mechanical efficiency of the transmission depends on the number and properties of kinematic pairs that transfer mechanical energy from the crankshaft to the driving wheels of the car. Its value can be selected from the table: efficiency is selected from the range for cars: 0.920.96.

We accept transmission efficiency - 0.92

The streamlining factor of the car.

The streamlining factor of the car kF characterizes the specific (per unit square speed) aerodynamic drag of the car. The smaller it is, the less the loss of power of the car to overcome air resistance.

I choose the streamlining factor of the designed car, focusing on literary data. I also choose it from the range for cars from the table. Range for small class cars... kF=0,6 0.7.

I accept the streamlining factor kF=0,6 H2/m2.

Sketched Design

2.1 Vehicle layout.

The layout of the car provides for the mutual arrangement of the main elements of the car - the engine, transmission, driver's workplace, passenger compartment and cargo.

The location of the engine depends on the accepted general transmission layout and the location of the engine. Depending on the accepted general layout, the engine will burn to be located in the front compartment of the car or behind. when the engine is placed forward, it can be located along the longitudinal axis of the car or across. Longitudinal placement of the engine is used in the classical layout (engine front-rear drive bridge). The longitudinal arrangement of the engine can also be used for front-wheel drive cars, but at the same time the volume and size of the engine compartment increases.

At front longitudinal arrangement of engine, its external overall dimensions and dimensions of engine compartment are determined. It is necessary that the overall dimensions of the engine allow it to be placed in the engine compartment without changing the external shapes and plumage of the front of the car and deteriorating its aerodynamic qualities. It should be provided that the distance from the rear of the cylinder block to the partition of the engine compartment allows the removal of the cylinder head without removing the engine from the car. So that the tunnel from the driveshaft in the drawing is inclined by 5... 7 degrees, the position of the engine in the drawing is set as the point of intersection of the crankshaft axis with the plane of the front end of the cylinder block and the angle of inclination of the crankshaft axis .

When the engine is located transversely, it is necessary to take into account the possibility of its placement in the engine compartment according to the overall width and layout of the radiator and fan behind the front lining of the hood in the area of ​ ​ the highest air head.

The transmission of the car is arranged depending on its wheel scheme. At the same time, the most attention is paid to the placement of the cardan transmission, which should provide a minimum mutual change in the inclination angles of the cardan shafts among themselves.

The length of the cardan shaft structure determines the ability of this structure to provide critical revolutions without breaking the shaft, the transmission units are placed on the condition that the minimum length of the cardan shaft and the rigidity of the connection of the clutch units and the gearbox are provided.

Layout of the driver's workplace and car interior. The driver's workplace should provide the possibility of his effective work during the working shift without fatigue and good visibility of the road situation, instrumentation, ease of use of controls.

The dimensions of the cab should allow for unhindered and convenient work by the driver.

If there is a power supply in the steering gear or brake system, the machine control shall be provided in case of failure.

The dimensions of the passenger compartment are chosen for reasons of convenience of accommodating passengers according to anthropological requirements to ensure the need for a long ride.

Conclusion:

The theme and purpose of my course design is to carry out the design of a middle-class car coupe, capacity - 5 people, wheel formula - 4X2, maximum speed 45 m/s. In addition to calculating the car, there is also a task for designing the Steering unit.

The explanatory note contains:

1. Selection and basis of initial data;

2. Traction calculation of the car, which includes the determination of the data necessary for plotting the external speed characteristic;

3. Technical and operational properties of the car, which included calculations for the traction and speed characteristics of the car, dynamic passport, braking properties, stability of the car, controllability, smoothness of travel, fuel economy.

4. The main technical and operational indicators of the car.