Automobile Inspection Technology

Chapter 2 Introduction (1)
UT knowledge points
1. The purpose and function of vehicle inspection;

2. Development overview and trend of automobile inspection technology;
3. Basic knowledge and relevant laws and regulations of automobile inspection;
4. The basic composition and functions of automobile testing equipment;

5. Measurement error and precision concepts.

Learn
1. Clarify the purpose and function of automobile inspection, and understand the concept of automobile inspection;

2. Understand the development situation and trend of automobile inspection technology;
3. Understand the concept of testing parameters, testing standards and testing cycle; familiar with common testing parameters of automobiles;
4. Understand the relevant regulations and management systems of automobile inspection;
5. Understand the composition and functions of automobile testing equipment;

6. Understand the concepts of measurement error and precision.

(Section [-]) Development Status of Automobile Inspection Technology

[-]. The purpose and significance of vehicle inspection

A car is a machine with a variety of modern technologies and a complex structure. During operation, various parts will be subjected to various physical and chemical effects, and the operating status will change continuously.Timely testing and mastering the technical status of automobiles can greatly improve the reliability of automobiles, give full play to the performance of automobiles, reduce maintenance costs, and obtain greater economic and social benefits.Cars have brought a series of problems such as air pollution, noise pollution, and traffic safety while benefiting people.

In March 1990, Order No. 3 of the Ministry of Communications promulgated the "Regulations on Vehicle Technology Management in the Automobile Transportation Industry", requiring vehicle management to adhere to the principles of prevention first and the combination of technology and economy, and implement comprehensive management throughout the entire process. The auto repair system of "compulsory maintenance and conditional repair" has introduced auto inspection technology and developed my country's auto repair system.Among them, "regular inspection" refers to the regular comprehensive performance inspection of vehicles engaged in automobile transportation to determine the technical status of the automobile after a certain mileage or time. Depending on the situation, repair operations of different items and depths are arranged.

The purpose and significance of vehicle inspection are summarized as follows:
1. Ensure traffic safety

With the increasing number of motor vehicles and the increasing number of road traffic accidents, the casualties and economic losses caused are astonishing.Among the many factors that cause traffic accidents, accidents caused by technical reasons such as vehicle braking, steering, and lighting account for about 1/4 of the total number of accidents.Therefore, it is essential for traffic safety to carry out regular and irregular inspections, timely adjustments, and maintenance of automobiles to keep them in good technical condition.

2. Reduce environmental pollution
Exhaust gas from automobiles contains hundreds of compounds, among which the substances that are directly harmful to humans and organisms mainly include CO, HC (the general name of hydrocarbons), NOX (the general name of carbon oxides), lead compounds, and soot.These harmful gases pollute the atmosphere and destroy the human living environment.Especially in areas with dense population and traffic congestion in big cities, automobile exhaust pollution is relatively serious, causing nearby residents to suffer greatly.The noise of cars is another kind of environmental pollution. At intersections with heavy traffic, the noise of vehicles can reach more than 0dB.The state strictly limits the exhaust pollution and noise pollution of automobiles through the method of regular inspection of automobiles.Establish a vehicle environmental pollution monitoring system to ensure that vehicles operate within the allowable range of environmental pollution.

3. Improve maintenance efficiency, supervise maintenance quality, and maintain good technical condition of vehicles

In vehicle technical support, according to statistics, the time spent on finding faults is about 70%, while the time spent on troubleshooting and maintenance accounts for 30%.The increasingly complex structure of vehicles makes fault diagnosis more and more important.

It can be said that in vehicle technical support, vehicle detection and diagnosis technology is inseparable.Without detection and diagnosis technology, an important link is missing in the automobile technical support system; without detection and diagnosis technology, the technical condition of the vehicle cannot be quickly restored; without detection and diagnosis technology, the vehicle maintenance support system will only stay in the aftermath maintenance and periodic maintenance.Therefore, it is necessary to adopt new technologies, develop modern testing and diagnostic equipment, and shorten maintenance time.Improve the maintenance efficiency, realize "conditional repair", scientifically maintain the good technical condition of the car, and prolong the service life of the car.

[-]. The development situation and development trend of automobile inspection technology at home and abroad

1. Overview of foreign development
Automobile inspection technology has gradually developed from scratch. Some developed countries in foreign countries have appeared as early as the 20s and 40s with some single-item inspection technologies and inspection equipment mainly focusing on fault diagnosis and performance debugging. After the 50s, the application of testing equipment has been greatly developed, and the utilization rate of equipment has been greatly increased. Gradually, individual testing and diagnostic equipment is connected to build stations (automobile testing stations appear), forming a system that can not only monitor safety and environmental protection, but also perform maintenance and diagnosis. comprehensive detection technology.In the 20s, with the development of computer technology, automobile performance testing instruments and equipment with functions such as automobile inspection and diagnosis, automatic data collection and processing, and direct printing of inspection results appeared. After the 60s, modern testing and diagnostic technologies in some advanced countries have reached the stage of widespread application. Not only are there many full-time car testing stations for in-use cars in the society, which institutionalizes car testing, but also the assembly line terminals of car manufacturers and cars Maintenance enterprises also have built vehicle inspection lines, which have brought obvious social and economic benefits to traffic safety, environmental protection, energy conservation, reduction of transportation costs and improvement of transportation capacity.

The detection technology of western developed countries has formed:

(1) The inspection of institutionalized cars is managed by the transportation department. There are automobile inspection stations certified by the transportation department all over the country, which are responsible for the registration of new cars and the safety inspection of in-use cars. Inspection by automobile inspection stations to determine whether its safety performance and emissions meet national standards.

(2) There is a whole set of standards for standardized vehicle testing.Judging whether the technical condition of the inspected vehicle is good or not is based on the data stipulated in the standard, and the inspection results are displayed in numbers with quantitative indicators to avoid subjective errors.In addition to test results

In addition to strict and complete standards, there are also standards for testing equipment, such as testing performance, specific structure, and testing accuracy of testing equipment.There are also specific requirements for the service life of testing equipment and technical updates.

(3) Intelligent and automated automobile testing equipment has widely used optical, mechanical and electrical integration technology, and adopts computer detection and control. Some testing equipment has expert systems and intelligent functions, which can detect the technical status of automobiles and can Diagnose the location and cause of the car failure, and guide the maintenance personnel to quickly eliminate the failure.With the advancement of science and technology, automobile testing equipment has new developments in terms of intelligence, automation, precision, and integration. New technologies are constantly applied, new testing fields are developed, and new testing equipment is developed.

2. Overview of domestic development
my country began to study automobile inspection technology in the 20s, and developed engine cylinder air leakage detectors, ignition timing lights, automobile brake test benches, inertial automobile brake test benches, and engine comprehensive testing equipment in the 60s. Detectors, automobile performance comprehensive test benches and other testing equipment.At the same time, a small amount of advanced testing equipment has been introduced from abroad, but due to various reasons, this technology has been developing slowly.Entering the 20s, with the continuous deepening of reform and opening up, the national economy and various fields of science and technology have developed rapidly, and automobile detection and diagnosis technology has also developed rapidly. In addition, my country's automobile manufacturing industry and With the rapid development of the highway transportation industry, the demand for vehicle detection and diagnosis technology and equipment is increasing day by day.

The number of motor vehicles in my country has increased rapidly, and a series of social problems such as traffic safety and environmental protection have followed.How to ensure the good performance of vehicles and avoid social pollution as much as possible has been gradually mentioned on the agenda of relevant government departments, thus promoting the development of automobile diagnosis and testing technology.During the "Sixth Five-Year Plan" period, the state focused on promoting the vehicle detection and diagnosis technology.The Ministry of Communications presided over the research and development of automobile brake test benches, sideslip test benches, axle (wheel) weight instruments, speed test benches, light detectors, engine comprehensive analyzers, and chassis dynamometer test benches.At the same time, since 1980, the transportation department has planned to build automobile comprehensive performance testing stations in the national highway transportation system, and has achieved good results.The public security department has also built many safety performance testing stations in cities above the middle level in the country.By the early 90s, in addition to the two departments of transportation and public security, machinery, petroleum, metallurgy, coal, forestry, foreign trade and other systems and some colleges and universities had also built a considerable number of vehicle inspection stations.At present, the automobile inspection stations of the two departments of transportation and public security have been established in cities and counties, basically forming a nationwide automobile inspection network.Automobile detection and diagnosis technology has begun to take shape.The detection and diagnostic equipment used by automobile maintenance enterprises all over the country is also increasing day by day.At the same time, in order to cooperate with the automobile inspection work, more than 100 national standards and industry standards related to automobile inspection have been issued and implemented in China.From the construction of the automobile comprehensive performance inspection station to the specific inspection items of automobile inspection, there are basically laws to follow.

3. The development trend of automobile inspection technology
① Testing equipment and testing methods are constantly being updated.With the continuous emergence of new technologies for automobiles, the continuous improvement of automobile testing equipment and testing methods is required.If the filter paper smoke meter cannot measure blue smoke and white smoke, this requires the use of a more powerful opaque smoke meter.Another example is the improvement of automobile emission standards, not only to detect the content of HC and CO in automobile exhaust, but also to detect the content of NOx, which requires the use of five-gas emission analyzers.

The dynamic detection method can more truly reflect the technical status of the vehicle.Therefore, the dynamic detection method is also the development direction of the vehicle detection technology in the future.For example, when the dual-idle speed method is used to detect the emission status of the car, the car is in a stationary state, which is far from the actual operating status of the car. However, the simple working condition method for the car can simulate the actual operating status of the car and realize dynamic detection. The emission level of automobiles can more truly reflect the actual emission status of automobiles.

② Automobile testing equipment is developing in the direction of automation, intelligence, precision and integration.auto testing equipment

Automation means that with the development of electronic computer technology, automobile testing equipment has emerged that integrates the functions of testing process, operation, data collection, test result display and printing.The computer network technology can be used to remotely control the measuring instruments of the testing equipment, and realize the automatic measurement of multiple testing equipment at the same time, thus realizing the full automation of the automobile testing line.The intelligence of automobile testing equipment mainly refers to the intelligence of measuring instruments, which is mainly reflected in the functions of self-diagnosis, self-calibration, data processing, intelligent control, and expansion functions.The precision of automobile testing equipment refers to the increasing use of high-precision sensing technology in modern automobile testing equipment to continuously improve the testing accuracy.The integration of automobile inspection equipment refers to the integration of some inspection functions of automobile inspection equipment, which can conveniently carry out multiple automobile inspections, thereby saving inspection time.

③Standardization and networking of automobile inspection technology.Formulate and improve the testing methods and limit standards of vehicle testing items; formulate the detailed rules for testing and evaluating the technical status of commercial vehicles, and agree to standardize testing requirements and operating techniques throughout the country; designate the formal certification rules for large equipment used in comprehensive testing stations, and Ensure that the comprehensive performance testing station fulfills its duties.At present, my country's automobile comprehensive performance testing stations all use computer management systems, which have realized networking inside.With the progress of technology and management, in the future, automobile testing will be truly networked, so as to share information resources and software and hardware resources.

(Second Section) Basic Theory of Automobile Inspection
[-]. The concept and classification of vehicle inspection

Automobile inspection refers to the inspection and measurement of automobiles by using automobile inspection equipment to determine the technical condition or working ability of automobiles.Automobile inspection usually includes regular performance inspection stipulated by the automobile maintenance system and inspection for diagnosing faults after the automobile breaks down.

Automobile diagnosis refers to the analysis and judgment to determine the technical status of the automobile or find out the location and cause of the failure without dismantling (or only removing individual small parts) after the automobile fails.Automobile diagnosis includes two ways of manual experience diagnosis and diagnosis by using modern detection and diagnosis equipment.

The two concepts of car inspection and car diagnosis are to check the car to understand the technical condition of the car, but the focus of the two is different.Automobile inspection focuses on the use of automobile inspection equipment, and automobile diagnosis focuses on the analysis and judgment of automobile failures.The regular inspection before the car breaks down is an active inspection behavior, and the car diagnosis is a passive inspection act. The meanings of the two are different; when the car breaks down, the use of detection equipment to diagnose the fault has similar meanings. Detection, the purpose of detection is diagnosis.

There are three main types of automobile inspections: automobile safety and environmental protection inspections, automobile comprehensive performance inspections, and fault diagnosis and maintenance inspections. Different types have different inspection purposes.The safety and environmental protection inspection of automobiles is to ensure that the automobiles in use have the required appearance and appearance, good safety performance and emission performance, and reduce the various hidden dangers that induce traffic accidents to the minimum, so that the automobiles are efficient, safe and run in an environmentally friendly manner.Comprehensive performance testing of vehicles is to determine the technical status and working ability of the vehicles in use, find out the location and causes of faults or hidden dangers, and ensure that the vehicles have good performance in terms of reliability, power, economy, environmental protection, and safety. technical condition.The purpose of vehicle maintenance inspection is to perform inspections before and after vehicle maintenance from the perspective of maintenance.Determine the location and cause of the fault before maintenance, improve the quality and efficiency of maintenance, and check whether the various performances of the car have been repaired after maintenance, and whether the indicators meet the technical standards.

[-]. Vehicle inspection parameters, standards and cycles
1. Vehicle detection parameters

Automobile detection parameters include working process parameters, accompanying process parameters and geometric dimension parameters.

(1) Working process parameters These parameters are some measurable physical and chemical quantities output during the working process of automobiles, assemblies and mechanisms.For example, engine power, output power or driving force of driving wheels, vehicle fuel consumption, braking distance or braking force or braking deceleration, gliding distance, etc., mainly reflect the overall technical status in the working process.

(2) Accompanying process parameters This parameter is some measurable output accompanying the working process of the vehicle, assembly and mechanism.For example, the vibration, noise, abnormal sound, overheating, etc. that occur during the working process of automobiles, assemblies, and mechanisms mainly provide local information and are often used for in-depth inspection of complex systems.

(3) Geometric dimension parameter This parameter can provide the technical status of the assembly and the matching parts in the mechanism or the independent parts.For example, fit clearance, free travel, roundness, cylindricity, end face circular runout, radial circular runout, etc. in the assembly and mechanism.Although the amount of information they provide is limited, they can reflect the specific status of the parts. Commonly used detection parameters for automobiles are shown in Table 1-1.

2. Automobile testing standards

Automobile testing standards are unified regulations on the methods, technical requirements and limits of automobile diagnosis.

(1) The types of automobile inspection standards are divided into four types: national standards, industry standards, local standards and enterprise standards.

①National standard.A national standard is a standard formulated by the state and is labeled with the words "National Standard of the People's Republic of China".National standards are generally proposed by a certain industry ministry and approved and issued by the State Bureau of Technical Supervision.All relevant units and individuals at all levels across the country must implement it. It is mandatory and authoritative, and relevant units and individuals must implement it.

②Industry standard.Industry standards are standards formulated and promulgated by ministerial or national committees and departments and filed by the State Bureau of Quality and Technical Supervision. They are implemented within the ministerial system or within the industry.

The standard is mandatory and authoritative within a certain range, and relevant units and individuals must also implement it.

③ Local standards.This standard is formulated and issued by provincial (autonomous region, municipality directly under the central government), prefecture-level, and county-level departments. It is implemented locally and is mandatory and authoritative within a certain range.

④Enterprise standards.The standard includes the standards recommended by automobile manufacturers, the internal standards formulated by automobile transportation enterprises and automobile maintenance enterprises, and the reference standards recommended by testing equipment manufacturers.In general, enterprise standards should meet the requirements of national standards and higher-level standards, while allowing them to exceed the requirements of national standards and higher-level standards.

The formulation and revision of any first-level standards must consider both technical and economical aspects, as well as advanced nature, and try to be as close as possible to the same type of international standards.

(2) The detection parameter standard consists of three parts: initial value, allowable value and limit value.

①Initial value.This value is equivalent to the detection parameter value of a fault-free new car and overhauled car, and is often the best value. It is generally formulated by the manufacturer and can be used as a testing standard for new cars and overhauled cars.When the measured value of the detected parameter is within the range of the initial value, it indicates that the diagnostic object is in good technical condition and can continue to operate without maintenance.

(End of this chapter)