This article starts with the four basic structures of automotive connectors, introduces the design standards of automotive connectors, and analyzes the three failure modes of automotive connectors for the stability assessment of automotive connectors, and interprets automotive connections The development and changes of the connector, and finally, in response to the market demand brought by this development and change, a corresponding application example of the car connector is given.
The form and structure of automobile connectors are ever-changing, and they are mainly composed of four basic structural components: contacts, shells (depending on the variety), insulators, and accessories. These four basic structural components enable automobile connectors to act as bridges and operate stably.
The contact is the core part of the automobile connector to complete the electrical connection function. Generally, a contact pair is composed of a male contact piece and a female contact piece, and the electrical connection is completed by the insertion of the female and male contact pieces. The male contact piece is a rigid part, and its shape is cylindrical (round pin), square cylinder (square pin) or flat (insert piece). The male contact is generally made of brass or phosphor bronze. The female contact piece, namely the socket, is the key part of the contact pair. It relies on the elastic structure to be elastically deformed when it is inserted into the pin to generate elastic force to form close contact with the male contact piece to complete the connection. There are many types of jack structures, including cylindrical (split, necked), tuning fork, cantilever type (longitudinal slot), folding type (longitudinal slot, 9-shaped), box-shaped (square jack) And the hyperboloid wire spring jack and so on.
The shell, also called the shell, is the outer cover of the car connector. It provides mechanical protection for the built-in insulating mounting plate and pins, and provides the alignment of the plug and socket when mating, and then fixes the connector to the device on.
The insulator is also often called the car connector base or mounting plate. Its function is to arrange the contacts according to the required position and spacing, and to ensure the insulation performance between the contacts and between the contacts and the shell. Good insulation resistance, withstand voltage performance and easy processing are the basic requirements for selecting insulating materials to be processed into insulators.
The accessories are divided into structural accessories and installation accessories. The attachment structure of the collar, positioning key, the positioning pin, the guide pin, coupling ring, cable clamps, seals, gaskets and the like. Install accessories such as screws, nuts, screws, spring rings, etc. Most of the accessories have standard parts and common parts.
With the rapid development of the automobile industry, various functional parts and various parts of automobiles are constantly developing in the direction of intelligence, refinement and reliability. The structural design, appearance design and materials of automobile connectors have also been proposed. With higher requirements, there are certain design standards.
Design standards for automotive connectors
Automotive connectors must comply with the USCAR-20 standard, which is the performance standard for automotive electrical connector systems. It stipulates that the electrical connector contact surface of automotive connectors must always be reliable during the entire life cycle, including the following nine factors:
1) The material of the connector contact is stable and reliable;
2) The positive force is stable;
3) The voltage and current of the circuit are stable;
4) The temperature requirement is within the specified range, including the surrounding temperature and its own temperature rise;
5) Better robustness;
6) It must be the same as the connector used in the high-speed and long-distance communication computer, and the car connector must be able to work reliably under harsh conditions;
7) Connector insertion force: 20.5kg or less;
8) connector holding force: 2.5kg above;
9) Heat resistance: -40~120℃
A typical light car has approximately 1,500 connection points, of which 50% to 60% are used for critical power distribution functions. Automotive connectors are used in increasingly harsh environments, including temperature (as low as minus 40°C, as high as minus 155°C), vibration, oxidation, and friction corrosion, which shows the importance of design research.
In fact, it’s not easy to do this. Most commercial electronic components make people feel frustrated at most when they fail. However, if there is a problem with the connection of key auto parts, it will cause the fire alarm, brake or airbag to fail. Lead to serious consequences.
The connector manufacturer must identify and analyze the physical and mechanical phenomena in the environment that may affect the performance of the connector. In accordance with the application conditions specified by the car manufacturer, in order to evaluate the stability of the connector, the connector manufacturer has implemented a sophisticated test procedure. If a connector failure occurs, it can mostly be determined as one of the following three failure modes: friction corrosion, electrical failure, and connector insertion problems. The following is an introduction to these three failure modes.
Three failure modes of automotive connectors
Corrosive gas, high humidity and strong oscillation are the three major conditions that cause oxidation and friction corrosion, and lead to connector failure. These environmental factors will have a great impact on the contact surface of tin and lead-tin, which is the case for 90% of the connector surface.
The connection problem of the cable and the terminal is one of the main reasons for the failure of the warranty and the connector system. For automotive wiring systems, crimping is a very common method for connecting terminals to cables. This process has proven to be reliable. Compared with the welding method, it is more economical and simple to operate in terms of improving crimping reliability.
When installing wiring into a car in an assembly plant, improper connection of the connector may cause the connector to malfunction. To overcome this problem, design engineers have developed various connector locking devices. Another solution is to use a plug-in auxiliary device to simplify the plug-in process for larger connectors.
For detailed understanding of the failure modes of automobile connectors, please refer to the analysis of the three failure modes of connector durability. As consumers have more and more requirements for the internal electronic functions of automobiles, and the electronic functions that can be provided in automobiles are becoming more and more abundant. Make automotive connectors become the fastest growing market segment in auto parts. The following is a summary of the development status of automotive connectors.
The development and changes of automotive connectors
At present, global automotive connectors account for about 15% of the connector industry. In the future, driven by automotive electronic products, it is expected to occupy a larger proportion. In terms of product cost structure, the average connector cost per car in China is only a few hundred yuan. Compared with foreign countries, the connector cost per car is about US$125 to US$150. China’s automotive connector market still has Great development potential. In the future, each car will use 600-1,000 electronic connectors, far greater than the number used today.
The huge potential of the market has attracted great attention from foreign manufacturers. Major automotive electronics companies such as Tyco, Delphi, FCI, etc. have stepped up their investment and layout in the Chinese connector market. Delphi even moved the center of its automotive connector business to Shanghai. China is expected to become an important production base for global automotive connectors in the future. In addition to the existing first-line well-known international manufacturers, other manufacturers that have not yet set up factories in China will gradually establish production bases in China to supply local automobile component manufacturers due to the increasing local demand, localized procurement, cost advantages and other factors. need.
In addition, electric vehicles and hybrid vehicles use large-capacity lithium batteries, and their operating voltage ranges from 14V to 400V-600V in traditional vehicles. Therefore, a comprehensive improvement in the automotive electrical and electronic architecture is required, and connectors are the first to bear the brunt. The new energy vehicle connector market has become a major niche market.
The development of new energy automotive connectors of three major trends: First, green, and second, security, third is connectivity.
Since new energy vehicles are "green" vehicles, connectors are also required to be green and environmentally friendly. In terms of safety, due to the ability of new energy vehicle connectors to withstand up to 250A current and 600V voltage, the need for high-standard protection against electric shock is obvious. At the same time, under such high power, electromagnetic interference is another important issue. In addition, the plugging and unplugging operations of the connector will generate arcs, which will seriously harm the electrical connections and electronic equipment, and may cause the car to burn. All of these require special design and development of the connector.
New energy vehicle connectors must meet their high-performance requirements mainly by strict design specifications. For example, in the case of exposure, it is necessary to prevent high voltage from breaking down the air, which requires a certain air gap; in the case of high voltage and high current, its The temperature rise should not exceed the rated value; the weight, strength and ease of processing should be considered when selecting the shell material, and how to maintain the stability of the material properties of the connector terminals at different temperatures and how to ensure the necessary conductivity must be considered.
In terms of connectivity, due to the continuous expansion of car entertainment systems, the importance of high-speed data transmission has become increasingly prominent. For example, on some models, a camera is installed on the reversing mirror, which allows the driver to have a wider field of view, which requires the connector to transmit more data. Sometimes a connector is needed to solve the problem of transmitting GPS signals and broadcast signals at the same time, which requires improving its data transmission capabilities. At the same time, the connector also needs to withstand high temperatures, because the car engine is usually placed in front of the car. Although there is a firewall to protect it, some heat will be conducted, so the connector must be able to withstand high temperatures.
With more and more applications of automotive connectors, the integration trend of automobiles has made the integration of connectors higher and higher. Due to the requirements of the car’s space design, the connectors are also required to have a smaller volume. Occupying a larger space, a single connector has to receive more and more signals. In general, the automotive connection system will develop in the direction of electronic control modules. On the basis of safety and connectivity, miniaturization, intelligence and integration are the future development trends of connectors. Here are some application cases of automotive connectors that meet market needs.