1 overview

 

After casting the market to move from the car of drive of the first gasoline engine, people discovery, the powerful electromagnetic wave that ignition system of gasoline engine high pressure generates, disturb its of the radiobroadcast all around and business of radio news report move normally, and cause pollution to electromagnetism environment. Consequently people takes this pollution line one of causes of 3 big pollution that cause to the car. From this, international radio organizes those who begin form of pulse of high to this kind energy to annoy a source to undertake method and limitation ask consider and offerringed measure. Current, in the technical code that the control that this kind of electromagnetism pollutes asks to already was listed to enter world each country. Through old technical standard, the car that runs on the market realized the effective control of noise of ignition pulse electromagnetism basically.

 

But, as the ceaseless progress of car technology and development, a large number of application of car electron wiring, the characteristic that car electromagnetism annoys and the effect that its produce also had tremendous change. The car generates the source that electromagnetism annoys, not pure it is ignition system, all sorts of electron wiring that apply on car in great quantities produce electromagnetism to annoy as much.

 

The electromagnetism that car produces is annoyed not only cause an effect to the radio equipment of car outside, and also can be opposite all sorts of electron components of car interior cause undesirable effect. What inchoate people cares generally is the major effect that car electromagnetism annoys pair of electromagnetism environments, as effective processing, this kind of influence had gotten controlling. Some closer year, the car appeared a lot of because car is in-house what electromagnetism annoys pair of car is normal move reach the security and dependability phenomenon that produces major effect, caused people to pay close attention to particularly. Current, the generation that people begins to study car interior electromagnetism is annoyed and influence reach his to control a technology.

 

The electromagnetism inside 2 cars annoys a phenomenon

 

The car produces the source that electromagnetism annoys to have: High-pressured ignition system; All sorts of sensibility are laden (be like, electric machinery kind electric equipment component) ; All sorts of switch kind component (be like, flashy relay) ; All sorts of electrons control unit ECU; Even all sorts of lamps and lanterns, radio equipment. The ado that these components produce can cause mutual effect in car interior. A few phenomena that produce actually are listed below.

 

Phenomenon 1, some kind in car of high quality scales, by abroad company of group of some famous car industry is designed, in Chinese churchyard production, have high-powered ABS system. Model car came up against wet in test of what is actually happening, the rain that start is blown implement, when some speed moves, ABS is broken suddenly went to action.

 

Phenomenon 2, the car of some model miniature that home produces, its dynamo adjuster often appears easy by puncture attaint phenomenon. Via checking, blow when rain implement when the job, phenomenon of this kind of attaint happens easily.

 

Analyse two afore-mentioned example, the main reason that creates this kind of appearance is rain is blown implement. Rain is blown implement drive electric machinery serves as perceptual load, in retrorse electricity can produce when dump and transmitting power supply system through power supply cord, disturb pulse in the generation in power source system thereby, component of a few electrons disturbs pulse condition to fall in this kind, cannot work normally, cause damage even.

 

Phenomenon 3, a kind of home develops safe gasbag of production, in the car truckload detonate suddenly on assembly line. Undertake experimenting checking via detonating controller to the electron of safe gasbag, discover its cannot bear magnetic field of stronger environmental radiate report, when electrostatic discharge happens, can have misoperation.

 

The characteristic that the electromagnetism inside 3 cars annoys

 

The electromagnetism of car interior annoys a characteristic to be opposite unlike car external annoy. The electromagnetism inside the car is annoyed can travel through all sorts of jumper cable, the way that also can shoot with radiate of coupling means, space has transmission. Typical form has: Edge power supply cord is conducted annoy; Electrostatic discharge is opposite human body the ado of electronic component; Annoy energy to wait through dimensional radiate. The characteristic that the source annoys with respect to a few models below undertakes an analysis.

 

(1) the ado that generation of engine ignition system conducts along power supply cord

 

Graph at 1 o’clock block diagram of principle of igneous system report (coil of ignition of B— of switch of K— of R0— circuitry impedance)

 

If the circuit block diagram of engine ignition system pursues 1. Sensor gets ignition signal Va, the Ib of pulse electric current that elementary generation breaks is encircled in ignition line by drive circuit, coil is sub pulse of generation high pressure makes sparkplug discharges, ignite motor fuel to mix gas to do work. When coil low return opens metabolic process when, elementary winding can produce twinkling to change voltage, sub winding produces tall voltage to make sparkplug discharges, leftover energy forms radiate of high frequency electromagnetic wave to arrive in the space. The twinkling in low return changes voltage is passed in power source system along power supply cord, violate power source system, produce ΔV of one fluctuant voltage.

 

If pursue 2. Usually, experimental measure gets ΔV is 2 ～ 4V.

 

 

Graph igneous system is departmental at 2 o’clock a signal sequential chart

 

All sorts of electrons that apply in the car control unit, the requirement has the power supply of power source voltage of a stability, ability works normally. Voltage should appear to fluctuate in power supply system (be like, ΔV) , can produce an effect to the regular job of electronic module.

 

(2) the ado that perceptual and laden generation conducts along power supply cord

 

The electric machinery of all sorts of types that use inside the car belongs to perceptual load. Be like: Rain is blown implement drive electric machinery, the car starts electric machinery, sirocco electric machinery. If circuit of this kind of load performance pursues 3. When when sensibility laden power supply is cut off suddenly, can produce retrorse twinkling to change voltage Vc, if pursue 4. Coil is initiative store can bigger, involve rate faster, twinkling changes overvoltage is taller. Actual measurement result, general Va is – 100 ～ – 300V, ts is 0.2 ～ 0.5s.

 

Graph circuit of 3 perceptual load performance pursues (sensibility of L— of switch of K— of R0— circuitry impedance is laden internal resistance of RL— perceptual load)

 

Graph 4 perceptual and laden twinkling change voltage

 

Of this kind of type annoy do not have admittedly successional, but its twinkling changes the amplitude of voltage is quite big, accidental occurrence meeting causes serious effect to electronic module, damage even. What the dynamo adjuster breakdown that allows first in preamble damages even if voltage causes is serious and sequential.

 

(3) the electrostatic discharge ado to component of the electron inside the car

 

Person experience generation is electrostatic, be in the northern region of our country especially, winter weather is dry, human body arises easily electrostatic. Human body is electrostatic come up against a few conductor to come out with respect to meeting acquit. Have direct discharge, people does not feel. When electrostatic store after certain level, can pass air discharge, can have scintilla generation even, people can have intense discharge to feel. When people is using a car, this kind of electrostatic discharge seems inevitably meeting to arise now.

 

Electrostatic discharge process, may be to discharging already process, also may be negative discharge process, if its discharge character pursues 5. Spark voltage U is highest amount to 15 ～ 25kV; Discharge time Ts, contact discharge: 0.7 ～ 1ns, air discharge: 0.7 ～ 5ns; Discharge electric current is very small, NA class.

 

 

Graph 5 electrostatic discharge are characteristic

 

Of this kind of type annoying a characteristic is: Tall voltage; Short time; Small electric current. It is tremendous that its annoy influence degree, can make a few electrons control unit to produce misoperation, serious meeting attaint electron is unit. The electron of the safe gasbag that describes like preamble detonates the misoperation of controller.

 

(4) the mutual coupling between component or wire cable is annoyed

 

All sorts of wire cable in the car often bind them inside of car of a bundle of edge to decorate, the twinkling in power supply cord changes annoy meeting coupling to arrive in line or control line, form difference to touch signal, can produce an effect to the electronic module such as the ECU inside the car. This often are ignored by people place.

 

(5) radiation is annoyed

 

Annoy the form of electromagnetic wave radiate of energy, people is more familiar. The frequency limits that people pays close attention to is 150kHz ～ 1000MHz. Other frequency paragraph annoying also is existence, people is undertaking study.

 

The inhibition that 4 electromagnetism annoy

 

The inhibition that electromagnetism annoys of measure choose, consider to annoy a source above all, the characteristic that should annoy a source according to what differ adopts different inhibition means. Be like: The ado of ignition system; The ado of power source power supply system; Inductance sex load or switch sex load cause annoy etc. Next, consider ado transmission way, it is very important that this restrains measure effectively. Annoying a way can be: Pass the cable of power supply system; Pass aerial or all sorts of lead; Pass coupling; Pass a space the means such as direct radiate electromagnetic wave.

 

In addition, annoy restrain should mature control capital. General processing pattern, inside the fair scope that limits those who annoy source generation to annoy noise to obtain a provision; Be annoyed at the same time the capacity that body should have certain resistance to annoy, in order to obtain the position that mutual coexistence, each other does not affect. Boundless make the ground increase annoy restrain meeting twice ground to increase control capital, this is the way that cannot take very much in actual application.

 

The ado of component of car electron electric equipment controls fashion, stipulate a certain number of grade are restricted to be worth commonly, different component is mixed according to its characteristic of use means different, the grade that chooses a kind of justice is restricted to be worth, control capital in order to reduce.

 

To coming from inside the car the ado of power supply system, a kind of simple and effective method is to use accumulator to change as the twinkling of an extremely low impedance, high capacity voltage is restrained implement, absorb all sorts of twinkling to change the ado that voltage produces energy. Best means is to make sure accumulator cable wiring is good. If negative pole takes iron, should make sure the resistance that take iron is the least. See a picture 1 with the graph 3, answer to make sure circuit impedance R0 amounts to the least value as far as possible, it is even 0.

 

To the ado that the coupling between wire cable causes, the method of a kind of economic capital is mature when the wiring inside the car decorate wire cable effectively. Best means is decorated to part ECU control line or line and power supply cord, enter with reducing what cause because of coupling to annoy signal to invade. In addition, use the means of screen cable, also be to avoid outside electromagnetism to annoy invade the good method that takes control line and line.

Annoy to what inductance sex load causes, restrain means to be able to use parallel connection the capacitor of a proper numerical value, in order to eliminate retrorse overvoltage. Overall tell, annoy the fashion that controls measure to have a lot of kinds, but answer accept to arrange for: Wave of screen, filter, ground connection, damp.

 

5 last words

 

Anyhow, it is great that the electromagnetism inside the car annoys the influence that reachs its to arise, matter to sex of car on the safe side. People should realize contemporary electron changes a lot of new titles that appear in the car, in quite the influence that annoys with electromagnetism on degree is concerned.

 

Author brief introduction: Xu establishs Chinese car research center