有关汽车ABS防抱死系统的英文资料
发布网友
发布时间：2022-04-19 09:48
共4个回答
热心网友
时间：2023-07-01 16:32
An Anti-lock Braking System (ABS) (translated from German, Anti-Blocker System) is a safety system on motor vehicles which prevents the wheels from locking while braking. A non-locking braking system allows the driver to maintain steering control under heavy braking, by preventing a skid, and allowing the wheel to continue to forward roll and create lateral control, as directed by driver steering inputs. Disadvantages of the system include increased braking distances under some limited circumstances (ice, snow, gravel, "soft" surfaces), and the creation of a "false sense of security" among drivers who do not understand the operation, and limitations of ABS.
Since it came into widespread use in proction cars (with "version 2" in 1978), ABS has made considerable progress. Recent versions not only handle the ABS function itself (i.e. preventing wheel locking under braking), but also traction control (TCS or ASR), brake assist (BA, EBA or HBA), and electronic stability control (ESP, ESC or DSC), amongst others. Not only that, but the Bosch 8.0 version now weighs less than 1.5 kilograms, compared with the 6.3 kg version 2.0 in 1978.
Contents
[hide]
* 1 History
* 2 Operation
o 2.1 Additional developments
+ 2.1.1 Traction control
* 3 Effectiveness
* 4 Risk compensation
* 5 Design and selection of components
* 6 References
* 7 See also
* 8 External links
[edit] History
Anti-lock braking systems were first developed for aircraft in 1929, by the French automobile and aircraft pioneer, Gabriel Voisin, as threshold braking an airplane is nearly impossible. An early system was Dunlop's Maxaret system, introced in the 1950s and still in use on some aircraft models.
A fully mechanical system saw limited automobile use in the 1960s in the Ferguson P99 racing car, the Jensen FF and the experimental all wheel drive Ford Zodiac, but saw no further use; the system proved expensive and, in automobile use, somewhat unreliable. However, a limited form of anti-lock braking, utilizing a valve which could adjust front to rear brake force distribution when a wheel locked, was fitted to the 1964 Austin 1800.
ABS brakes on a BMW motorcycle
ABS brakes on a BMW motorcycle
Chrysler, together with the Bendix Corporation, introced a crude, limited proction ABS system on the 1971 Imperial. Called "Sure Brake", it was available for several years, and had a satisfactory performance and reliability record. Ford also introced anti lock brakes on the Lincoln Continental Mark III and the Ford LTD station wagon, called "Sure Trak". The German firms Bosch and Mercedes-Benz had been co-developing anti-lock braking technology since the 1930s, and introced the first completely electronic 4-wheel multi-channel ABS system in trucks and the Mercedes-Benz S-Class in 1978. ABS Systems based on this more modern Mercedes design were later introced on other cars and motorcycles.
[edit] Operation
The anti-lock brake controller is also known as the CAB (Controller Anti-lock Brake).
A typical ABS is composed of a central electronic control unit (ECU), four wheel speed sensors (one for each wheel), and two or more hydraulic valves within the vehicle brake circuit. The ECU constantly monitors the rotational speed of each wheel. When it senses that any number of wheels are rotating considerably slower than the others (a condition that is likely to bring it to lock - see note below), it actuates the valves to decrease the pressure on the specific braking circuit for the indivial wheel, effectively recing the braking force on that wheel. The wheel(s) then turn faster; when they turn too fast, the force is reapplied. This process is repeated continuously, and this causes the characteristic pulsing feel through the brake pedal. A typical anti-lock system can apply and release braking pressure up to 20 times a second.
Note: The ECU needs to determine when some of the wheels turn considerably slower than any of the others because when the car is turning the two wheels towards the center of the curve inherently move slightly slower than the other two – which is the reason why a differential is used in virtually all commercial cars.
The sensors can become contaminated with metallic st, or other contaminants, and fail to correctly detect wheel slip; this is not always picked up by the internal ABS controller diagnostic.[citation needed] In this occurence, the ABS warning light will usually be illuminated on the instrument panel, and the ABS will be disabled until the fault is rectified.
[edit] Additional developments
One step beyond ABS are modern Electronic Stability Control (ESC or ESP) systems. Here, two more additional sensors are added to help the system work: these are a steering wheel angle sensor, and a gyroscopic sensor. The theory of operation is simple: when the gyroscopic sensor detects that the direction taken by the car doesn't coincide with what the steering wheel sensor reports, the ESC software will brake the necessary indivial wheel(s) (up to three with the most sophisticated systems), so that the vehicle goes the way the driver intends. The steering wheel sensor also helps in the operation of Cornering Brake Control (CBC), since this will tell the ABS that wheels on the inside of the curve should brake more than wheels on the outside, and by how much.
[edit] Traction control
Main article: Traction control system
The ABS equipment may also be used to implement traction control system (TCS, ASR) on acceleration of the vehicle. If, when accelerating, the tire loses traction, the ABS controller can detect the situation and take suitable action so that traction is regained. Manufacturers often offer this as a separately priced option even though the infrastructure is largely shared with ABS.[citation needed] More sophisticated versions of this can also control throttle levels and brakes simultaneously.
Mercedes-Benz was the first to offer this electronic traction control system in 1985.
[edit] Effectiveness
A 2003 Australian study[1] by Monash University Accident Research Centre found that ABS:
* Reced the risk of multiple vehicle crashes by 18 percent,
* Reced the risk of run-off-road crashes by 35 percent.
On high-traction surfaces such as bitumen, or concrete, many (though not all) ABS-equipped cars are able to attain braking distances better (i.e. shorter) than those that would be easily possible without the benefit of ABS. Even an alert, skilled driver without ABS would find it difficult, even through the use of techniques like threshold braking, to match or improve on the performance of a typical driver with an ABS-equipped vehicle, in real world conditions. ABS reces chances of crashing, and/or the severity of impact. The recommended technique for non-expert drivers in an ABS-equipped car, in a typical full-braking emergency, is to press the brake pedal as firmly as possible and, where appropriate, to steer around obstructions. In such situations, ABS will significantly rece the chances of a skid and subsequent loss of control.
In gravel, sand and deep snow, ABS tends to increase braking distances. On these surfaces, locked wheels dig in and stop the vehicle more quickly. ABS prevents this from occurring. Some ABS calibrations rece this problem by slowing the cycling time, thus letting the wheels repeatedly briefly lock and unlock. The primary benefit of ABS on such surfaces is to increase the ability of the driver to maintain control of the car rather than go into a skid — though loss of control remains more likely on soft surfaces like gravel or slippery surfaces like snow or ice. On a very slippery surface such as sheet ice or gravel, it is possible to lock multiple wheels at once, and this can defeat ABS (which relies on comparing all four wheels, and detecting indivial wheels skidding). Availability of ABS relieves most drivers from learning threshold braking.
A June 1999 National Highway Traffic Safety Administration (NHTSA) study found that ABS increased stopping distances on loose gravel by an average of 22 percent.[2]
According to the NHTSA,
"ABS works with your regular braking system by automatically pumping them. In vehicles not equipped with ABS, the driver has to manually pump the brakes to prevent wheel lockup. In vehicles equipped with ABS, your foot should remain firmly planted on the brake pedal, while ABS pumps the brakes for you so you can concentrate on steering to safety."
When activated, some earlier ABS systems caused the brake pedal to pulse noticeably. As most drivers rarely or never brake hard enough to cause brake lock-up, and a significant number rarely bother to read the car's manual,[citation needed] this may not be discovered until an emergency. When drivers do encounter an emergency that causes them to brake hard, and thus encounter this pulsing for the first time, many are believed to rece pedal pressure, and thus lengthen braking distances, contributing to a higher level of accidents than the superior emergency stopping capabilities of ABS would otherwise promise. Some manufacturers have therefore implemented a brake assist system that determines that the driver is attempting a "panic stop" and the system automatically increases braking force where not enough pressure is applied. Nevertheless, ABS significantly improves safety and control for drivers in most on-road situations.
[edit] Risk compensation
This section does not cite any references or sources. (May 2008)
Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed.
ABS brakes are the subject of some widely cited experiments[citation needed] in support of risk compensation theory, which support the view that drivers adapt to the safety benefit of ABS by driving more aggressively.
The two major examples are from Munich and Oslo.[citation needed] In both cases taxi drivers in mixed fleets were found to exhibit greater risk-taking behaviour when driving cars equipped with ABS, with the result that collision rates between ABS and non ABS cars were not significantly different.
[edit] Design and selection of components
This section does not cite any references or sources. (May 2008)
Please help improve this section by adding citations to reliable sources. Unverifiable material may be challenged and removed.
Given the required reliability, it is illustrative to see the choices made in the design of the ABS system. Proper functioning of the ABS system is considered of the utmost importance, for safeguarding both the passengers within, and people outside of the car. The system is therefore built with some rendancy, and is designed to monitor its own working and report failures. The entire ABS system is considered to be a hard real-time system, while the sub-system that controls the self diagnosis is considered soft real-time. As stated above, the general working of the ABS system consists of an electronic unit, also known as ECU (electronic control unit), which collects data from the sensors and drives the hydraulic control unit (HCU), mainly consisting of the valves that regulate the braking pressure for the wheels.
The communication between the ECU and the sensors must happen quickly and at real time. A possible solution is the use of the CAN bus system, which has been, and is still in use in many ABS systems today (in fact, this CAN standard was developed by Robert Bosch GmbH, for connecting electronic control units). This allows for an easy combination of multiple signals into one signal, which can be sent to the ECU. The communication with the valves of the HCU is usually not done this way. The ECU and the HCU are generally very close together. The valves, usually solenoid valves, are controlled directly by the ECU. To drive the valves based on signals from the ECU, some circuitry and amplifiers are needed (which would also have been the case if the CAN-bus was used).
The sensors measure the position of the tyres, and are generally placed on the wheel-axis. The sensor should be robust and maintenance free, not to endanger its proper working, for example an inctive sensor. These position measurements are then processed by the ECU to calculate the differential wheel rotation.
The hydraulic control unit is generally integrated with the ECU (or the other way around), and consists of a number of valves that control the pressure in the braking circuits. All these valves are placed closely together, and packed in a solid aluminium alloy block. This makes for a very simple layout, and is thus very robust.
The central control unit generally consists of two microcontrollers, both active simultaneously, to add some rendancy to the system. These two microcontrollers interact, and check each other's proper working. These microcontrollers are also chosen to be power-efficient, to avoid heating of the controller which would rece rability.
The software which runs in the ECU has a number of functions. Most notably, the algorithms that drive the HCU as a function of the inputs, or control the brakes depending on the recorded wheel spin. This is the obvious main task of the entire ABS-system. Apart from this, the software also needs to process the incoming information, e.g. the signals from the sensors. There is also some software that constantly tests each component of the ABS system for its proper working. Some software for interfacing with an external source to run a complete diagnosis is also added.
As mentioned before the ABS system is considered hard real-time. The control algorithms, and the signal processing software, certainly fall in this category, and get a higher priority than the diagnosis and the testing software. The requirement for the system to be hard real-time can therefore be reced to stating that the software should be hard real-time. The required calculations to drive the HCU have to be done in time. Choosing a microcontroller that can operate fast enough is therefore the key, preferably with a large margin. The system is then limited by the dynamic ability of the valves and the communication, the latter being noticeably faster. The control system is thus comfortably fast enough, and is limited by the valves.
参考资料：http://en.wikipedia.org/wiki/Anti-lock_braking_system
热心网友
时间：2023-07-01 16:32
【作者】 魏朗、王囤
【所属类别】 实用汽车维修丛书
【开本】 16
【页数】 230
【版数】 1
【ISBN号】7-114-03935-2
【装帧】 平
【定价】25元
【销售价】 25元
内容简介
本书是一部关于汽车ABS技术与实例的专业书籍。主要内容包括现代汽车帛动防抱死系统的典型结构和工作原理，ABS的理论基础和基本控制原理，ABS系统的基本组成，ABS系统的控制方式，ABS系统三大主要部件的结构及工作原理，汽车驱动防滑系统(SAR)的控制原理、控制方式和控制效果，ABS系统试验评价方法和性能评价指标，典型ABS系统工作原理、结构、电路控制系统、故障诊断与排除。
本书可供从事汽车技术的专业人士阅读，也可供汽车维修人员和大专院校师生参考。
此书对你有帮助
热心网友
时间：2023-07-01 16:33
你自己去下面的网页看
参考资料：http://en.wikipedia.org/wiki/Anti-lock_braking_system
热心网友
时间：2023-07-01 16:33
http://www.howstuffworks.com/anti-lock-brake.htm
http://autorepair.about.com/cs/generalinfo/a/aa052001a.htm
http://minivans.about.com/od/glossary/g/abs.htm
http://trucks.about.com/cs/repairmaintenance/a/antilock_brakes.htm
http://web.mit.e/2.972/www/reports/anti_lock_brakes/anti_lock_brakes.html
http://www.automotive-online.com/articles/2008/02/an-overview-of-anti-lock-braki.html
http://www.freescale.com/webapp/sps/site/application.jsp?nodeId=02Wcbf07jSKy5P
http://www.google.com.sg/search?q=Antilock+Braking+System+&hl=en&start=10&sa=N
How Antilock Brake Systems Work
Since most cars on the road today have some form of Antilock Brakes (ABS) I think we should take a look at how they work and clear up some mis-information about them.
As always, what I describe here is how most systems work in general. Since different manufactures have their own versions of ABS their values, specifications and part names will differ. If you are having a problem with the ABS on your vehicle you should always refer to the specific service and repair manuals for your vehicle.
The ABS is a four-wheel system that prevents wheel lock-up by automatically molating the brake pressure ring an emergency stop. By preventing the wheels from locking, it enables the driver to maintain steering control and to stop in the shortest possible distance under most conditions.
During normal braking, the ABS and non-ABS brake pedal feel will be the same.
During ABS operation, a pulsation can be felt in the brake pedal, accompanied by a fall and then rise in brake pedal height and a clicking sound.
Vehicles with ABS are equipped with a pedal-actuated, al-brake system. The hydraulic system consists of the following:
ABS hydraulic control valves and electronic control unit
Power brake booster
Brake master cylinder
Necessary brake tubes and hoses
The anti-lock brake system consists of the following components:
Hydraulic Control Unit (HCU).
Anti-lock brake control mole.
Front anti-lock brake sensors / rear anti-lock brake sensors.
Anti-lock Brake System (ABS) operates as follows:
When the brakes are applied, fluid is forced from the brake master cylinder outlet ports to the HCU inlet ports. This pressure is transmitted through four normally open solenoid valves contained inside the HCU, then through the outlet ports of the HCU to each wheel.
The primary (rear) circuit of the brake master cylinder feeds the front brakes.
The secondary (front) circuit of the brake master cylinder feeds the rear brakes.
If the anti-lock brake control mole senses a wheel is about to lock, based on anti-lock brake sensor data, it closes the normally open solenoid valve for that circuit. This prevents any more fluid from entering that circuit.
The anti-lock brake control mole then looks at the anti-lock brake sensor signal from the affected wheel again.
If that wheel is still decelerating, it opens the solenoid valve for that circuit.
Once the affected wheel comes back up to speed, the anti-lock brake control mole returns the solenoid valves to their normal condition allowing fluid flow to the affected brake.
The anti-lock brake control mole monitors the electromechanical components of the system.
Malfunction of the anti-lock brake system will cause the anti-lock brake control mole to shut off or inhibit the system. However, normal power-assisted braking remains.
Loss of hydraulic fluid in the brake master cylinder will disable the anti-lock system.
The 4-wheel anti-lock brake system is self-monitoring. When the ignition switch is turned to the RUN position, the anti-lock brake control mole will perform a preliminary self-check on the anti-lock electrical system indicated by a three second illumination of the yellow ABS wanting indicator.
During vehicle operation, including normal and anti-lock braking, the anti-lock brake control mole monitors all electrical anti-lock functions and some hydraulic operations.
Each time the vehicle is driven, as soon as vehicle speed reaches approximately 20 km/h (12 mph), the anti-lock brake control mole turns on the pump motor for approximately one-half second. At this time, a mechanical noise may be heard. This is a normal function of the self-check by the anti-lock brake control mole.
When the vehicle speed goes below 20 km/h (12 mph), the ABS turns off.
Most malfunctions of the anti-lock brake system and traction control system, if equipped, will cause the yellow ABS warning indicator to be illuminated.
参考资料：希望能帮助你
