東風(fēng)標(biāo)致空調(diào)系統(tǒng)故障分析,東風(fēng),標(biāo)致,美麗,空調(diào),系統(tǒng)故障,分析 無(wú)錫職業(yè)技術(shù)學(xué)院畢業(yè)設(shè)計(jì)說(shuō)明書(shū) 原 文： Guards against holds dead braking system (ABS) ABS development histories and introduces ABS is an item only then starts the application in the end of the 80's the new technology, now already became the common passenger vehicle to have the support. Statistics have indicated, the automobile meets suddenly when the situation sends the braking, 90% above drivers often meet a foot the brake pedal to step on come slam on the brakes, this time vehicle to be extremely easy to produce slip and have the side-slipping, namely the people are named “fling the tail”, this will be one kind extremely easy to create the traffic accident the phenomenon. Creates the automobile side-slipping the reason to be very many, for example the moving velocity, the state of ground, the tire structure and so on can create the side-slipping, but the most basic reason is the automobile when the emergency brake the wheel tire and the ground rolling friction can become the sliding friction suddenly, the tire stresses the soil fertility to lose nearly, although this very moment driver sways from side to side the steering wheel also to be able not to help matters. Has the side-slipping phenomenon basic reason in view of this kind, the automobile expert dispatches a vehicle on the development with the ABS this kind of set of skid prevention arresting gear. The automobile guards against holds the dead braking system to have many types, now common is four channel ABS system and three channel ABS type. These types guard against hold the dead braking system the sensor through to examine the wheel the rotational speed to adjust the hydraulic pressure to prevent the wheel hugs dies. Some people thought the automobile assembles ABS to think drives may the capriciousness, the blind drive fast did not fear, this is the extremely wrong understanding. The automobile installed ABS not to install ABS in the brake effect aspect to be more ideal than, this was affirmative, but ABS also only could under certain condition, be able to play its role fully. For example gets on the brakes suddenly on the wet slippery path, the ABS system may enable the pilot to maintain the vehicles travel to be steady, stops in the short distance the automobile. But in not the wet slippery road surface, cannot reduce the stopping distance generally, but may reduce and avoid “flinging the tail” the phenomenon. The road surface test research indicated that, in the sand rock road or other soft road surfaces, the ABS system even can increase the vehicles the stopping distance, because the stopping distance length and the road surface friction coefficient concerns with the tire. Therefore, in order to reduce the stopping distance effectively, on many automobiles all installs has EBD (Electric Brake force Distribution), Chinese translates “the electronic braking force assignment”. EBD in front of ABS movement the sixth branch after balanced the wheel ground according to the vehicles load to stress the soil fertility, carried on the rational distribution to the trailing wheel braking force, might reduce the automobile stopping distance effectively, in fact got up the ABS enlarged function. Therefore many automobiles all have “ABS+EBD” the installment, improves and enhances ABS the effect. Now the automobile assembles ABS is one kind of electrically controlled installment, it only can mechanically after the procedure which establishes carry out the movement according to the sixth branch. If the driver did not understand ABS the function, is very possibly contrary to what expects. The automobile applies the brake when ABS checks the way with the spot to be possible to prevent vehicles when brake loses changes ability, plays time the control vehicles stopping role. But plays the operation role is radically the driver, when the driver steps on the brake pedal while the emergency case the also jerk steering wheel (many to be insufficiently experienced or being panic-stricken instinct movement often is fiercely jerk steering wheel).If the vehicles have not installed ABS to cause the braking system to hug die, cannot have an effect to the steering wheel extreme response, this time the driver cannot control the direction through the steering wheel which the vehicles move; But if installed the ABS system to let the driver be able to control the steering wheel, then could cause the situation in the flurried situation to the steering wheel extreme response to become worse. Because the sudden jerk steering wheel, often can produce the automobile the side-slipping to occur suddenly the accident. American Highway Safety control Association (NHTSA) believed through the test that, the installment has ESP to control the vehicles to the driver to be possible to have the very big help. ESP (electrically controlled travel steady system, English full title Electronic Stab lit Program) contains ABS and ASR, is in these two kind of system function extending, it can prevent wheel when brake hugs dies with in the start time slips. The unceasing surveying examines the vehicles the travel condition ,when has the emergency case it can rapidly respond, adjusts each wheel through the hydraulic pressure regulator the brake pressure and intervenes the engine the force of traction, reduces the vehicles to ides slip the danger. Some research indicated that, ESP can cause the traffic accident to reduce 50%. 10 year before last, if the passenger vehicle installment has ABS (to guard against hugs dies braking system), not only explain ad this vehicle the security performance stands out, moreover the scale quite is also high-level. Today, installed ABS the passenger vehicle already quite to be common, the economy vehicle also installed has ABS. Along with is more and more high to the auto safety performance quest, some center, the high link passenger vehicle already did not satisfy ABS, but also installed ASR (actuation skid prevention system, also called force of traction control system) or ESP (electrically controlled travel steady system),makes the automobile the security performance further to enhance. The ASR function is when pick-up skidding rate control in curtains cope, thus prevented the driving gear fast skids. Its function one enhances the force of traction; Two, maintains the automobile the travel to be stable. The travel when the easy slippery road surface ,does not have ASR the pick-up the driving gear to be easy to slip; If after is the vehicles which actuates is easy to fling the tail, like is the vehicles easy direction which front actuates to lose control When has ASR, auto mobile when acceleration cannot have or can reduce this kind of phenomenon. When curve, if has the driving gear to slip can cause the entire vehicles to a side displacement, when has ASR can cause the vehicles to change along the correct route. 5th, 2 ABS structure and the principle 1,the ABS system can prevent the wheel hugs dies, has applies the brake when the yawing stab ility is good, applies the brake when still to have changes the ability ,reduces merit and so on stopping distance. The rich advantage card ABS system, is three channels ABS adjustment return routes, the front wheel alone adjusts, trailing wheel take a two turns of center grounds coefficients of adhesion low side as basis unification adjustment. The ABS system mainly by the ABS controller (including electronic control unit, hydraulic pressure unit, hydraulic pump and so on), four wheels tachometer generator, the ABS breakdown tell-tale light, applies the brake the tell-tale light and so on to be composed. The ABS system basic principle of work is: The automobile in applies the brake in the process, the wheel tachometer generator unceasingly each wheel rotational speed signal prompt transportation for the ABS electronic control unit (ECU), the control logic which ABS the ECU basis establishes the signal which inputs to 4 tachometer generators carries on processing, calculates the automobile the reference vehicle speed, various wheels speed and reduces the speed, determines various wheels the slipping rate. If some wheel slipping rate surpasses supposes the definite value, ABS ECU sends out the command control hydraulic control unit, causes in this wheel brake wheel cylinder the brake pressure to reduce; If some wheel slipping rate had not achieved supposes the definite value, ABS ECU on the control hydraulic pressure unit, causes this wheel the brake pressure to increase; When some wheel slipping rate approaches to supposes the definite value, ABS ECU on the control hydraulic control unit, causes this wheel brake pressure maintenance to be certain. Thus causes each wheel the slipping rate maintenance in the ideal scope, prevented 4 wheels completely hug die. In applies the brake in the process, if the wheel has not held the dead tendency, the ABS system will not participate in the brake pressure control, this time will apply the brake the process and the convention braking system is same. If ABS will appear the break down, the electronic control unit no longer will carry on the control to the hydraulic pressure unit, and will lighten the display board on ABS breakdown tell-tale light, will send out the warning signal to the pilot, this time ABS will not play the role, will apply the brake the process and does not have ABS the convention braking system work to be same. 5th, the ABS system major component structure and the principle of work (1) wheel tachometer generator wheel tachometer generator function is bequeaths the wheel rotational speed signal the ABS electronic control unit. MK20- I ABS system altogether has 4 wheels tachometer generator, the front wheel tooth ring (43 teeth) installs on the drive shaft, the tachometer generator installs in knuckle on, like the chart 8-2 shows. The trailing wheel tooth ring (43 teeth) install on the after wheel hub, the tachometer generator installs on the fixed support. The sensor and the magnetic tooth ring is composed by electromagnetism induction type transmit. transmit the reason permanent magnetic core and the induction coil composition, the tooth ring is made by the ferromagnetic material. When the tooth ring revolves ,addendum and space between teeth in turn in turn to magnetic core, when the tooth ring changes to the addendum and transmit a magnetic core relative, between transmit magnetic core and tooth ring gap smallest, has the magnetic line of force by the permanent magnetic core on through the tooth ring, around the induction coil magnetic field is easily strong, like the chart 8-4 (a) shows; But when the tooth ring rotates to the space between teeth and transmit the magnetic core relative, between transmit magnetic core and tooth ring gap biggest, has the magnetic line of force by the permanent magnetic core not easily through the tooth ring, around the induction coil magnetic field is weak, like the chart 8-4 (b) shows. This time, the magnetic flux rapid in turn changes, will be able to produce the alternating voltage in the induction coil, the alternating voltage frequency with the vehicle rotates the intensive proportion change. The electronic control unit may the voltage pulse frequency which inputs through the tachometer generator carry on processes determines the wheel the rotational speed, the automobile reference velocity and so on. (2) ABS the controller ABS controller by the ABS electronic control unit (J104), the hydraulic control unit (N55), the hydraulic pump (V64) and so on is composed. 1st, the electronic control unit electronic control unit is the ABS system control center, it is a microcomputer in fact, therefore often is called ABS (ECU) the computer. ABS ECU by the input circuit, the digital controller, the output circuit and the warning electric circuit is composed. The primary mission is the continuous monitoring accepts the pulse signal which 4 wheels tachometer generator sends, and carries on the Urey comparison, the analysis enlarges and distinguishes processing, the idea figures out the wheel rotational speed, the wheel reduces the speed as well as applies the brake the slipping rate, again carries on the logical comparison to analyze 4 wheels to apply the brake the situation, once judges the wheel to be going to hug dies, it enters immediately guards against holds the dead control condition, sends out the instruction through the electronic control unit to the hydraulic pressure unit, controls on the brake wheel cylinder oil duct the solenoid valve to pass breaks adjusts the brake pressure with the hydraulic pump work, prevented the wheel hugs dies. ABS ECU also unceasingly carries on the monitoring to own work. Because in ABS ECU has two quite same not less than microprocessors, they carry on processing according to the similar procedure to the input signal, and the intermediate result and the final outcome which produces it carry on the comparison, one also the discovery result is in consistent namely determines own existence breakdown, it can the automatic shut-off ABS system. In addition ABS ECU also unceasingly monitors in the ABS system other parts working conditions, once the ABS system appears the breakdown, like the wheel rate signal vanishes, hydraulic pressure pre sure drop and so on, ABS ECU can send out the instruction to close the ABS system, and causes the convention braking system work, simultaneously remembered the breakdown information storage, and lightens the display board on ABS breakdown lights, sends out the police to the pilot to show the signal, this time should promptly inspect the repair. When the ignition lock puts through, ABS ECU starts to carry on the self-checking procedure, carries on self-checking to the system, this time the ABS breakdown lights lighten. If self-checking later discovered the ABS system existence interferes with its normal work the breakdown, it will close the ABS system, will restore the convention braking system, on the display board the ABS breakdown lights continuously lightens, warns the pilot ABS system existence breakdown. After self-checking had ended, the ABS breakdown lights extinguish, indicated the system work is normal Because the self-checking process probably needs 2s, therefore in normal condition, when the ignition lock puts through, the ABS breakdown lights lighten 2s, then automatically extinguishes again, is normal. Otherwise if the ignition lock puts through time, the ABS breakdown lights are not bright, explained the ABS breakdown lights or its line existence breakdown, should carry on the overhaul to it. 2nd,hydraulic control unit and the hydraulic pump hydraulic control unit installs in the brake master cylinder with the brake wheel cylinder between, uses the integral-type structure (like chart 8-5 to show).The primary mission is the transformation carries out the ABS ECU instruction, in automatic control brake low pressure. The low pressure pot and the electrically operated hydraulic pump gather is a body installs on the hydraulic control unit. The low pressure oil tank function is uses in the temporary storage the brake fluid which flows out from the wheel cylinder, the pulsation which relaxes the brake fluid flows out from the brake wheel cylinder when produces. Electrically operated hydraulic pressure .The electrically operated hydraulic pump function is promptly delivers in the brake pressure stage inflow low pressure pot brake fluid to the brake master cylinder, simultaneously in exerts the pressure stage, absorbs surplus from the low pressure pot brake, pumps into applies the brake the circulatory system, for the hydraulic system by the pressure support, the increase applies the brake the potency. The electrically operated hydraulic pump revolution is by the electronic control unit control. The hydraulic control unit (N55) valve in vivo including 8 solenoid valves, each return route each pair, often advances the oil valve, often shuts the delivery valve. It in the brake master cylinder, the brake wheel cylinder and returns to between the oil duct to establish the relation, realization pressure lifting, the pressure maintenance and the pressure drop function, prevented the wheel hugs dies, its principle of work as follows: (1)starts when the de boost phase (system flowing tubing head pressures abolishment) starts to apply the brake, the pilot steps on the brake pedal, the brake pressure by the brake master cylinder production, frequently opens does not bring the voltage the charging valve to affect to the wheel brake wheel cylinder on, this time, does not bring the voltage the delivery valve still to close, the ABS system has not participated in the control, the entire process and the convention hydraulic brake system is same, the brake pressure unceasingly rises. 翻 譯： 防抱死制動(dòng)系統(tǒng)（ABS） ABS的發(fā)展歷史及簡(jiǎn)介 ABS是一項(xiàng)在80年代末才興起應(yīng)用的新技術(shù)，現(xiàn)在已經(jīng)成為一般轎車的必裝件了。 據(jù)統(tǒng)計(jì)，汽車突然遇到情況發(fā)剎車時(shí)，百分之九十以上的駕駛者往往會(huì)一腳將剎車踏板踩到底來(lái)個(gè)急剎車，這時(shí)候的車子十分容易產(chǎn)生滑移并發(fā)生側(cè)滑，即人們俗稱的“甩尾”，這是一種非常容易造成車禍的現(xiàn)象。造成汽車側(cè)滑的原因很多，例如行駛速度，地面狀況，輪胎結(jié)構(gòu)等都會(huì)造成側(cè)滑，但最根本的原因是汽車在緊急制動(dòng)時(shí)車輪輪胎與地面的滾動(dòng)摩擦?xí)蝗蛔優(yōu)榛瑒?dòng)摩擦，輪胎的抓地力幾乎喪失，此時(shí)此刻駕駛者盡管扭動(dòng)方向盤(pán)也會(huì)無(wú)濟(jì)于事。針對(duì)這種產(chǎn)生側(cè)滑現(xiàn)象的根本原因，汽車專家就研制出車用ABS這樣一套防滑制動(dòng)裝置。 汽車防抱死制動(dòng)系統(tǒng)有許多類型，現(xiàn)在常見(jiàn)是四通道ABS系統(tǒng)和三通道ABS類型。這些類型的防抱死制動(dòng)系統(tǒng)的transmit器通過(guò)檢測(cè)車輪的轉(zhuǎn)速以調(diào)整液壓來(lái)防止車輪抱死。 有人以為汽車裝配 ABS就以為開(kāi)車可以隨意性，盲目開(kāi)快車也不怕，這是非常錯(cuò)誤的認(rèn)識(shí)。汽車安裝了ABS在制動(dòng)的效果方面比沒(méi)有安裝 ABS理想，這是肯定的，但ABS也只能在一定的條件下，才能充分發(fā)揮它的作用。例如在濕滑的道路上突然剎車，ABS系統(tǒng)可以使駕駛員能夠保持車輛行駛平穩(wěn)，在較短的距離內(nèi)將汽車剎住。但在不濕滑的路面上，一般不能縮短剎車距離，但可以減少和避免“甩尾”現(xiàn)象。路面的測(cè)試研究表明，在沙石路或其他松軟的路面上，ABS系統(tǒng)甚至?xí)龃筌囕v的剎車距離，因?yàn)閯x車距離的長(zhǎng)短與路面的摩擦系數(shù)和輪胎有關(guān)。因此，為了有效減小剎車距離，許多汽車上都安裝有EBD（Electric Brakeforce Distribution），中文譯“電子制動(dòng)力分配”。EBD在ABS動(dòng)作之前巳經(jīng)根據(jù)車輛載荷平衡了車輪的地面抓地力，對(duì)后輪的制動(dòng)力進(jìn)行合理分配，可以有效地縮短汽車制動(dòng)距離，實(shí)際上起到ABS的增補(bǔ)功能。因此許多汽車都有“ABS＋EBD”的裝置，改善和提高ABS的功效。 現(xiàn)在汽車裝配的ABS是一種電控裝置，它只能機(jī)械地按照巳經(jīng)編制好的程序來(lái)執(zhí)行動(dòng)作。如果駕駛者不了解ABS的功能，很可能事與愿違。汽車制動(dòng)時(shí)ABS用點(diǎn)剎方式可以防止車輛在制動(dòng)時(shí)喪失轉(zhuǎn)向能力，起到控制車輛制動(dòng)狀態(tài)時(shí)的作用。但根本起到操縱作用是駕駛者，當(dāng)駕駛者在緊急情況下猛踩制動(dòng)踏板的同時(shí)又急扭方向盤(pán)（許多經(jīng)驗(yàn)不足或驚慌失措者的本能動(dòng)作往往是急扭方向盤(pán)）。如果車輛沒(méi)有安裝ABS導(dǎo)致制動(dòng)系統(tǒng)抱死，對(duì)方向盤(pán)的過(guò)激反應(yīng)就不會(huì)起作用，此時(shí)駕駛者不能通過(guò)方向盤(pán)來(lái)控制車輛移動(dòng)的方向；但如果安裝了ABS系統(tǒng)讓駕駛者能夠控制方向盤(pán)，那么在慌亂的情況下對(duì)方向盤(pán)的過(guò)激反應(yīng)就會(huì)使情況變得更糟。由于突然急扭方向盤(pán)，往往會(huì)令汽車突然產(chǎn)生側(cè)滑而發(fā)生事故。美國(guó)高速公路安全管理協(xié)會(huì)（NHTSA）通過(guò)測(cè)試認(rèn)為，安裝有ESP對(duì)駕駛者控制車輛可以有很大幫助。ESP（電控行駛平穩(wěn)系統(tǒng)，英文全稱Electronic Stabilty Program）包含ABS及ASR，是這兩種系統(tǒng)功能上的延伸，它能防止車輪在制動(dòng)時(shí)抱死和在啟動(dòng)時(shí)打滑。ESP不斷地測(cè)檢車輛的行駛狀態(tài)，當(dāng)發(fā)生緊急情況時(shí)它會(huì)迅速反應(yīng)，通過(guò)液壓調(diào)節(jié)器調(diào)節(jié)每個(gè)車輪的制動(dòng)壓力和干預(yù)發(fā)動(dòng)機(jī)的牽引力，以降低車輛的側(cè)滑危險(xiǎn)。有研究表明，ESP能使交通事故降低50%。ABS防抱死系統(tǒng)專題：從ABS到ASR、ESP 10前年，如果轎車安裝有ABS（防抱死制動(dòng)系統(tǒng)），不但說(shuō)明該車的安全性能出類拔萃，而且檔次也相當(dāng)高級(jí)。今天，安裝ABS的轎車已經(jīng)相當(dāng)普遍，經(jīng)濟(jì)型車也安裝有ABS。隨著對(duì)汽車安全性能的要求越來(lái)越高，一些中、高檔級(jí)的轎車已經(jīng)不滿足于ABS，還安裝了ASR（驅(qū)動(dòng)防滑系統(tǒng)，又稱牽引力控制系統(tǒng)）或者ESP（電控行駛平穩(wěn)系統(tǒng)），使汽車的安全性能進(jìn)一步提高。 ASR的作用是當(dāng)汽車加速時(shí)將滑動(dòng)率控制在一定的范圍內(nèi)，從而防止驅(qū)動(dòng)輪快速滑動(dòng)。它的功能一是提高牽引力；二是保持汽車的行駛穩(wěn)定。行駛在易滑的路面上，沒(méi)有ASR的汽車加速時(shí)驅(qū)動(dòng)輪容易打滑；如是后驅(qū)動(dòng)的車輛容易甩尾，如是前驅(qū)動(dòng)的車輛容易方向失控。有ASR時(shí)，汽車在加速時(shí)就不會(huì)有或能夠減輕這種現(xiàn)象。在轉(zhuǎn)彎時(shí)，如果發(fā)生驅(qū)動(dòng)輪打滑會(huì)導(dǎo)致整個(gè)車輛向一側(cè)偏移，當(dāng)有ASR時(shí)就會(huì)使車輛沿著正確的路線轉(zhuǎn)向。 ABS的結(jié)構(gòu)及原理 ABS系統(tǒng)能夠防止車輪抱死，具有制動(dòng)時(shí)方向穩(wěn)定性好、制動(dòng)時(shí)仍有轉(zhuǎn)向能力、縮短制動(dòng)距離等優(yōu)點(diǎn)。富利卡ABS系統(tǒng)，是三通道的ABS調(diào)節(jié)回路，前輪單獨(dú)調(diào)節(jié)，后輪則以兩輪中地面附著系數(shù)低的一側(cè)為依據(jù)統(tǒng)一調(diào)節(jié)。ABS系統(tǒng)主要由ABS控制器 (包括電子控制單元、液壓?jiǎn)卧?、液壓泵?、四個(gè)車輪轉(zhuǎn)速transmit器、ABS故障警告燈、制動(dòng)警告燈等組成。 ABS系統(tǒng)的基本工作原理是:汽車在制動(dòng)過(guò)程中， 車輪轉(zhuǎn)速transmit器不斷把各個(gè)車輪的轉(zhuǎn)速信號(hào)及時(shí)輸送給ABS電子控制單元(ECU),ABS ECU根據(jù)設(shè)定的控制邏輯對(duì)4個(gè)轉(zhuǎn)速transmit器輸入的信號(hào)進(jìn)行處理，計(jì)算汽車的參考車速、各車輪速度和減速度，確定各車輪的滑移率。如果某個(gè)車輪的滑移率超過(guò)設(shè)定值，ABS ECU就發(fā)出指令控制液壓控制單元，使該車輪制動(dòng)輪缸中的制動(dòng)壓力減小;如果某個(gè)車輪的滑移率還沒(méi)達(dá)到設(shè)定值，ABS ECU就控制液壓?jiǎn)卧?，使該車輪的制?dòng)壓力增大;如果某個(gè)車輪的滑移率接近于設(shè)定值時(shí)，ABS ECU就控制液壓控制單元，使該車輪制動(dòng)壓力保持一定。從而使各個(gè)車輪的滑移率保持在理想的范圍之內(nèi)，防止4個(gè)車輪完全抱死。 在制動(dòng)過(guò)程中，如果車輪沒(méi)有抱死趨勢(shì)，ABS系統(tǒng)將不參與制動(dòng)壓力控制，此時(shí)制動(dòng)過(guò)程與常規(guī)制動(dòng)系統(tǒng)相同。如果ABS出現(xiàn)故障，電子控制單元將不再對(duì)液壓?jiǎn)卧M(jìn)行控制，并將儀表板上的ABS故障警告燈點(diǎn)亮，向駕駛員發(fā)出警告信號(hào)，此時(shí)ABS不起作用，制動(dòng)過(guò)程將與沒(méi)有ABS的常規(guī)制動(dòng)系統(tǒng)的工作相同。 ABS系統(tǒng)主要部件結(jié)構(gòu)與工作原理 （一）車輪轉(zhuǎn)速transmit器 車輪轉(zhuǎn)速transmit器的作用是將車輪的轉(zhuǎn)速信號(hào)傳給ABS電子控制單元。MK20-Ⅰ型ABS系統(tǒng)共有4個(gè)車輪轉(zhuǎn)速transmit器，前輪的齒圈(43齒)安裝在傳動(dòng)軸上，轉(zhuǎn)速transmit器安裝在轉(zhuǎn)向節(jié)上，如圖8-2所示。后輪的齒圈(43齒)安裝在后輪轂上，轉(zhuǎn)速transmit器則安裝在固定支架上。transmit器由電磁感應(yīng)式transmit頭和磁性齒圈組成。transmit頭由永久磁芯和感應(yīng)線圈組成，齒圈由鐵磁性材料制成。當(dāng)齒圈旋轉(zhuǎn)時(shí)，齒頂與齒隙輪流交替對(duì)向磁芯，當(dāng)齒圈轉(zhuǎn)到齒頂與transmit頭磁芯相對(duì)時(shí)，transmit頭磁芯與齒圈之間的間隙最小，由永久磁芯產(chǎn)生的磁力線就容易通過(guò)齒圈，感應(yīng)線圈周圍的磁場(chǎng)就強(qiáng)，如圖8-4(a)所示;而當(dāng)齒圈轉(zhuǎn)動(dòng)到齒隙與transmit磁芯相對(duì)時(shí)，transmit頭磁芯與齒圈之間的間隙最大，由永久磁芯產(chǎn)生的磁力線就不容易通過(guò)齒圈，感應(yīng)線圈周圍的磁場(chǎng)就弱，如圖8-4(b)所示。此時(shí)，磁通迅速交替變化，在感應(yīng)線圈中就會(huì)產(chǎn)生交變電壓，交變電壓的頻率將隨車輪轉(zhuǎn)速成正比例變化。電子控制單元可以通過(guò)轉(zhuǎn)速transmit器輸入的電壓脈沖頻率進(jìn)行處理來(lái)確定車輪的轉(zhuǎn)速、汽車的參考速度等。 （二）ABS控制器 1、電子控制單元 電子控制單元是ABS系統(tǒng)的控制中心，它實(shí)際上是一個(gè)微型計(jì)算機(jī)，所以又常稱為ABS(ECU)電腦。ABS ECU由輸入電路、數(shù)字控制器、輸出電路和警告電路組成。主要任務(wù)是連續(xù)監(jiān)測(cè)接受4個(gè)車輪轉(zhuǎn)速transmit器送來(lái)的脈沖信號(hào)，并進(jìn)行測(cè)量比較、分析放大和判別處理，計(jì)算出車輪轉(zhuǎn)速、車輪減速度以及制動(dòng)滑移率，再進(jìn)行邏輯比較