Positive hitch can be used in automobiles, the body and frame of the car are not easy to corrode, right?

Why cars use negative hitch method, negative hitch or positive hitch on the car

Business Information By: Wuji - 2022-10-27 21:07:58 - 10 Reads - 0 Comments

It is well known that the automotive electrical system is characterized by a low-voltage, direct-current, single-wire system, and tensioning of the negative pole. Low voltage means that the electrical system voltage is 12V or 24V, which is below the safe voltage of 36V. DC means that the car battery, generator and all electrical appliances use DC. Single-wire system means that all electrical appliances in the car can be controlled by a positive wire negative means that all the power supply, electrical equipment in the car, their negative poles are directly connected to the body, the body as the electrical system of the public **** circuit.

Low voltage, DC, single wire systems are easy to understand. Some of it is for safety, some of it is to reduce cost and complexity of the system, but why does it have to be negatively tensioned steel? Can't you use positive tensioning material?

Actually, when cars were first invented, they used positive iron for quite some time. That is, the positive terminals of the power supply and electrical appliances were connected directly to the body of the car, and the negative terminals were connected to the negative terminals of the power supply via wires. However, with the increase of electrical parts of the car, people soon found a problem - the car body corrosion is serious, and this corrosion has nothing to do with the degree of corrosion resistance of the car steel plate. Automotive engineers carefully studied and found that the root cause of the disease falls on the positive pole of the electrical system, the body of the steel plate electrochemical corrosion rate will be faster. Subsequently, the technicians changed the car's electrical system to a negative pole and iron, the degree of electrochemical corrosion is greatly reduced. Since then, all automotive electrical systems have used negative iron and have become an international standard.

So why does the use of positive iron in automobiles accelerate the corrosion of the body? Let's briefly analyze this question.

First, let's look at the principle of body corrosion. Automobile body all made of steel plate, the basic composition of the iron element. Iron is also a relatively active metal, at room temperature will be with the oxygen in the air and water chemical reaction. Iron atoms lose the outer layer of electrons, become iron ions, and oxygen combined to generate hydrated iron oxide, which is commonly known as rust. This is the root cause of auto body corrosion, obviously the faster the iron atoms lose electrons, the faster the car corrosion, the greater the degree of corrosion. This corrosion process, essentially by iron, oxygen and water constitute a tiny primary battery, so this corrosion is also called electrochemical corrosion.

In order to prevent body corrosion, slow down the corrosion rate of the body, the car in the production process using galvanized steel, electrophoresis, painting, cavity waxing and other anti-corrosion measures, the main purpose is to block the contact of iron, oxygen, water, the degree of this blocking also makes the body of the car corrosion resistance is great However, the car body can not be 100% isolation of air and water. Because in some parts must keep the metal exposed. For example, the hitch points of each electrical component. Also, when tightening the bolts, the separator can be damaged. So many cars tend to rust where the brakes are for this reason.

So, how do the positive and negative sides of a car's electrical system affect this corrosion process and the rate of corrosion? Try analyzing them separately.

First, let's look at the workings of the car's power source, the battery. Almost all batteries carried in cars are lead batteries, whose positive plates are lead dioxide, negative plates are pure lead, and the electrolyte is dilute sulfuric acid. The lead on the positive plates exists in the state of lead ions, and the lead on the negative plates exists in the state of ionization. In other words, lead ions and electrons are formed, and there is a potential difference of about 2.1V between the positive and negative plates. This is the basic principle of the battery to generate electric potential. The charging and discharging process of the battery is actually a mutual conversion process of several substances, including lead, lead dioxide, lead sulfate, sulfuric acid, and water, in which the electric current is formed with the flow of electrons.

With the addition of positive iron to the electrical system of a car, the body of the car is connected to the positive terminal of the battery. The lead in the positive terminal of the battery exists in an ionic state and the lead is not as metal active as the iron, in which case the electrons from the body will continue to be attracted to the battery. The iron atoms in the body will lose their electrons and become iron ions, which will quickly combine with hydrated iron trioxide when they encounter water and oxygen in the air, and corrosion will occur. Therefore, applying positive iron will increase the activity of the body metal and make it prone to galvanic corrosion, so the body corrodes faster and more severely.

What would happen if a negative steel bar was used, meaning the car body was connected to the battery's negative terminal? Just watch it again. The negative plate of the battery has lead ions and electrons in the free state, with a potential of -0.1V. In other words, there is an abundance of electrons on the negative plate. In this case, the negative battery electrode can supply electrons to the body steel plate at any time, which means that it is very difficult for the body steel plate to lose electrons and be oxidized. This means that it is difficult for the body steel to lose electrons and oxidize. Just as metal is "passivated" by changing its shape, the body is less susceptible to galvanic corrosion, and corrosion of the body is also reduced. Nowadays, there are also machines that use anti-corrosion measures by attaching active metals to the metal casing, and the principle is actually the same.

So, the car using negative side iron way can effectively avoid and slow down the rate of electrochemical corrosion of the body, so that the body has a better anti-corrosion performance. This is the most fundamental reason for cars to hang negative side iron. An interesting phenomenon is that in the 1950s and 1960s, China's production of automobiles basically use positive iron. The slogan at the time was "East wind overrides West wind", so we made things differently from the West. They made negative steel, we made positive steel, they made alternators, we made DC engines, so the cars of that era couldn't be replaced with domestic electrical parts. Only, later on, it was found that this was really not in line with scientific principles, and after the 1970s, it was gradually corrected. It also shows that science has no borders or ideologies.

Also, there is the phenomenon that confuses many people. Cars in common use generally have a hard time rusting, but cars that have been parked for a long time will rust quickly. This is known as "water does not rot, the cardinal does not rot". In fact, this phenomenon is also related to the electrochemical corrosion of the body. Commonly used cars, the body at any time there is a current through the body metal at any time to get electrons, not easy to be oxidized corrosion, oxidation corrosion process slows down. And long time parking car, the battery is dead, the body no current, the body of the metal in the body to replenish the electrons will also be reduced if the oxygen and water damage to the body of the rust layer, the car's steel plate will be further corrosion, steel will oxidize, rust. This is the main reason why parking is easy to rust.

Cars have single-wire electrical systems with iron negative terminals, so many electrical devices require only their metal housings to be mounted directly to the body. If the housing is non-metallic, pull out the wires and connect them to the body. Such wires are called "turnouts". Theoretically, all electrical devices require a turnout, but in order to minimize the number of turnouts in a car, many electrical devices have their negative terminals connected together and are connected to the body by a single male **** wire. This conductor is the male **** turnout.

The turnout plays a very important role in automobile circuits. If the turnout is rusty or loose, the resistance in this area will increase dramatically. This is like having a large resistor in series with the car circuit, making it difficult to start the car, dimming the lights, and inaccurate signals. Therefore, the wire is also known as the "lifeline" of the automobile electrical system. A lot of electrical faults in automobiles are due to poor cable contact. When troubleshooting automotive electrical problems, we first check whether the cable is corroded or loose. This can greatly reduce our labor and shorten the inspection time.

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Qingdao Hengjiang Petrochemical Equipment Engineering Company Limited is mainly committed to the petrochemical pipeline pipe bracket and adiabatic pipe bracket design and manufacture. Ltd. is mainly engaged in the design and manufacture of petrochemical pipeline pipe supports and insulated pipe supports. We provide users with polyurethane insulated pipe supports, red pine insulated pipe supports, ...Enter website

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