ABS catalog
ABS anti-lock braking system
ABS application
ABS function
Get out of ABS misunderstanding
ABS use common sense
ABS function
ABS plastic
Asset-backed securities
[edit This paragraph]ABS anti-lock braking system
"ABS" is translated as "anti-lock braking system" in Chinese. It is a car safety control system with the advantages of anti-skid and anti-lock. ABS is an improved technology based on conventional braking devices, and can be divided into two types: mechanical and electronic. Anti-lock braking systems are installed on a large number of modern cars. ABS not only has the braking function of ordinary braking systems, but also prevents the wheels from locking, allowing the car to still turn under braking and ensuring the stability of the car's braking direction. , to prevent sideslip and deviation, is currently the most advanced braking device with the best braking effect in automobiles.
In the past, when consumers bought cars, whether they had ABS was an important indicator. With the development of technology, currently, most cars in my country have ABS as standard configuration. However, many drivers are still not very clear about ABS and how to use it correctly, and there are even some misunderstandings about ABS. Some drivers think that ABS is a device that shortens the braking distance. The braking distance of a vehicle equipped with ABS on any road surface is definitely shorter than that of a vehicle without ABS. Some even mistakenly believe that the braking distance on icy and snowy roads can be shorter. The braking distance is equivalent to that on asphalt roads; some drivers believe that as long as ABS is equipped, the vehicle will not lose control even when driving at high speed on rainy days or icy and snowy roads. ABS does not greatly improve the limits of a car's physical performance as some people think. Strictly speaking, the function of ABS is mainly to ensure the maneuverability and stability of the vehicle itself during braking within the performance of physical limits. At the same time, it can also prevent pure tire slippage when accelerating, improving acceleration performance and operational stability.
[Edit this paragraph] Application of ABS
The full name of ABS is Anti-lock Brake System (anti-lock braking system) or Anti-skid Braking System (anti-skid braking system) Dynamic system), it can effectively control the wheels to keep in a rotating state, improve the stability of the car during braking and the braking performance of the car under poor road conditions. ABS continuously detects the rotation speed of each wheel through the rotation speed sensor installed on each wheel or transmission shaft. The computer calculates the wheel slip rate at that time and compares it with the ideal slip rate to increase or decrease the brake braking. The pressure is determined and the actuator is ordered to adjust the brake pressure in time to keep the wheels in an ideal braking state.
ABS was first patented in 1906, and in 1936 Bosch registered a "mechanical" patent for preventing wheel locking of motor vehicles. All early designs had the same problems: they were too complex and prone to failure, and they were too slow. In 1947, the world's first ABS system was first used on the B-47 bomber. Teldix began research on this project in 1964, and its ABS research was soon taken over by Bosch. Within two years, the first ABS test vehicles had the function of shortening braking distances. Vehicle steering and stability were also ensured when turning, but the approximately 1,000 analog components and safety switches applied at the time meant that the reliability and durability of the electronic control unit, known as the ABS 1 system, was not yet sufficient for large-scale Production requirements need to be improved. The technology acquired by Bosch during the development of electronic engine management, digital technology and the arrival of integrated circuits (ICs) allowed the number of electronic components to be reduced to 140.
In 1968, ABS began to be studied and applied to automobiles. Due to the passage of the U.S. Federal Motor Vehicle Safety Standard No. 121 in 1975, many heavy-duty trucks and buses were equipped with ABS. However, due to many technical problems with the braking system and opposition from the truck industry, this standard was withdrawn in 1978. . In the same year, Bosch, as the first company in the world to launch an ABS system with electronic control functions, began to install this ABS 2 system as an optional configuration and installed it on the Mercedes-Benz S-Class, and then soon equipped it. On the BMW 7 Series luxury sedan.
After this period, further research and design work on ABS in the United States decreased, but European and Japanese manufacturers continued to carefully develop ABS.
After entering the 1980s, because cars imported into the United States were equipped with ABS, American automobile manufacturers showed new interest in ABS in the American automobile market. With the rapid development of microelectronics technology and people's strong requirements for automobile driving safety, ABS devices have been further widely used in the world's automobile industry. In 1987 about 3% of cars in the United States were equipped with highly reliable ABS. In the ensuing period, developers focused on simplifying the system. In 1989, Bosch engineers succeeded in attaching a hybrid control unit directly to the hydraulic module. This eliminates the need for wiring harnesses and connectors to connect the control unit to the hydraulic module, significantly reducing the overall weight of the ABS 2E.
Bosch engineers created ABS 5.0 using a new solenoid valve in 1993, and developed versions 5.3 and 5.7 in subsequent years. The main features of the new ABS 8 generation are once again a significant reduction in weight, volume and memory, while adding further functions such as electronic distribution of brake pressure, which replaces the mechanical reduction of brake pressure on the rear axle. mechanism. The predictions made by some automobile industry analysts at that time were confirmed: by the mid-1990s, most cars and trucks on the world market will be equipped with ABS.
[Edit this paragraph] Function of ABS
The main function of ABS is to improve the braking performance of the vehicle, improve driving safety, and prevent wheel locking during braking ( i.e. stop rolling), thereby ensuring that the driver can still control the direction when braking and preventing the rear axle from slipping. Its working principle is: during emergency braking, it relies on the highly sensitive wheel speed sensor installed on each wheel. Once a wheel is found to be locked, the computer immediately controls the pressure regulator to release the pressure of the brake cylinder of the wheel, causing the wheel to brake. Restore rotation to prevent wheel locking. The working process of ABS is actually a cyclic working process of "locking - releasing - locking - releasing", which keeps the vehicle in a critical locking clearance rolling state, effectively overcoming the vehicle's risk of wheel locking during emergency braking. Deviation phenomenon, preventing the car body from losing control and other situations.
There are two types of ABS: mechanical and electronic. Mechanical ABS has a simple structure and mainly uses its own internal structure to achieve the effect of simply adjusting the braking force. The working principle of the device is simple. There are no sensors to feedback signals such as road friction and wheel speed. It relies entirely on preset data to work. Whether it is a waterlogged road, an icy road, a muddy road or a good cement asphalt road, it The way they work is the same. Strictly speaking, this kind of ABS can only be called "Advanced Brake System". At present, only some low-end pickup trucks and other models in China still use mechanical ABS.
Mechanical ABS only uses the physical characteristics of components to perform mechanical movements, while electronic ABS uses computers to analyze and calculate various data to obtain results. Electronic ABS consists of wheel speed sensors, wiring harnesses, computers, ABS hydraulic pumps, indicator lights and other components. According to the signal of the wheel speed sensor of each wheel, the computer applies different braking force to each wheel respectively, thereby achieving the effect of scientific and reasonable distribution of braking force.
The earliest ABS system was a two-wheel system. The so-called two-wheel system is to install ABS on the two rear wheels of the car. Because the two rear wheels share a brake hydraulic pipeline and a control valve, it is also called a "single-channel control system." This system selects the brake pressure based on the condition of the wheel with the smaller adhesion of the two rear wheels, which is called the "low selection principle." In other words, when one rear wheel of an ABS vehicle using the low-selection principle has a tendency to lock, the system can only relieve pressure on both rear wheels at the same time. And since the front wheel does not have an anti-lock function, it is difficult for the two-wheel system to achieve the best braking effect.
With the development of related technologies, the "three-channel control system" later appeared. This system is based on the two-wheel system, and the two front wheels are independently controlled by two separate pipelines. Although the rear wheel still adopts the "low selection principle", this system has the main characteristics of modern ABS because it realizes the steering function during emergency braking and the function of preventing the rear axle from slipping. So far, there are still vehicles on the market that use this three-channel controlled ABS system.
Currently, the most common equipment on vehicles is the four-sensor four-channel ABS system. Each wheel is controlled by an independent hydraulic pipeline and solenoid valve, which can achieve independent control of a single wheel. This structure can achieve good anti-lock braking function.
[Edit this paragraph] Get out of ABS misunderstandings
The misunderstandings about ABS in the opening article need to be explained. If a car's wheels lock while braking, the car will have minimal lateral traction. At this time, due to factors such as the imbalance of road adhesion coefficient, the imbalance of the car's own braking force, the imbalance of the suspension, the tire pressure of the car, the curvature of the road, bumps or slopes, etc., the car may slip, drift or lose control. . In addition, due to the locking of the front wheels of the vehicle, the car will lose its steering ability. A car anti-lock braking system with excellent performance can control the slip rate of the car wheels between 20% and 30% during braking. In this state, the wheels can take into account the relatively maximum longitudinal braking force and The lateral grip effectively ensures that the vehicle will not lose control. In addition, when the front wheels are not locked, due to a certain amount of grip, the car can also turn according to the driver's wishes, thereby controlling the vehicle. In order to control the wheel slip rate under an ideal state and pursue vehicle stability, some longitudinal braking force may be sacrificed. Therefore, when ABS is activated, the braking distance will not be shortened on all road surfaces.
On ice and snow roads, the adhesion provided by the ground is much smaller than that of ordinary roads. ABS can only adjust the car's braking force based on this adhesion, and will not generate additional braking factors. Therefore, the braking distance on ice and snow roads can only be said to be shorter than when the wheels are locked, but still much longer than the braking distance on ordinary roads.
The actual road is actually very complex, such as: unbalanced road adhesion coefficient, road curvature or road cross slope, and even car tire pressure and other reasons of the car itself. There are many factors that can cause the car to brake when braking. These factors that produce a tendency to slide sideways cannot be overcome by ABS itself. Therefore, if you brake suddenly when the vehicle speed is too fast on an icy or snowy road, and encounter one of the above factors, when the centrifugal force of the vehicle is greater than the maximum lateral force that the ground can provide, the vehicle will tend to lose control, which is very dangerous.
In short, no equipment is omnipotent, and drivers must use their own subjective initiative to achieve safe driving. Even ABS with excellent performance has limited effect in stabilizing the vehicle under working conditions. Especially when driving on gravel roads or ice and snow roads, you should maintain sufficient distance between vehicles, slow down and drive slowly, and do not rely entirely on the ABS system.
[Edit this paragraph] Common sense on the use of ABS
Basically all passenger cars are now equipped with ABS systems, which plays a great role in improving the active safety performance of the vehicle. , but if used improperly, the effect will be greatly reduced. Here, our principles for using ABS are summarized as “four do’s and seven don’ts”.
Four essentials
1. Always press the brake pedal and never relax, so as to ensure sufficient and continuous braking force and make ABS work effectively.
2. Keep a sufficient safe distance between vehicles. Under normal circumstances, the minimum distance between vehicles should not be less than 50m. When the vehicle speed exceeds 50km/h, the minimum distance between vehicles is the same as the vehicle speed. For example, at 100km/h, the minimum distance between vehicles is 100m, and at 120km/h, the minimum distance between vehicles is 120m. .
3. Be familiar with ABS in advance so that you can be prepared and adaptable to the vibration of the brake pedal when ABS is working.
4. Read the car driver's manual in advance to further understand the various operating instructions provided by the car manufacturer that installs ABS.
Seven Don’ts
1. Don’t think that you can drive as you like with ABS. ABS is not absolutely safe. When the vehicle speed is too high and the turn is too sharp, if the vehicle brakes too quickly or too hard, the car will still slide. Therefore, even if your car is equipped with ABS, you still need to drive carefully.
2. Do not use "point braking" braking. When vehicles without ABS are braking on slippery roads and at high speeds, they need to use "point braking" to achieve safe braking. After installing ABS, because ABS can automatically adjust the braking force, when implementing emergency braking, you can press the pedal to the bottom without releasing it. Don't worry about the wheels locking and slipping, otherwise the braking distance will be greatly extended.
3. Don’t be frightened by the vibration of ABS. When ABS is working, you will hear the noise it makes. This noise is produced by the solenoid valve and hydraulic pump in the hydraulic control system. Do not panic because you think there is something wrong with the braking system, and do not move your feet from it. Remove the brake pedal, but still depress the brake pedal and ignore it.
4. Do not ignore the inspection of the ABS indicator light. Under normal circumstances, this light should come on after the ignition switch is turned on; it will automatically go out after about 3 seconds. This process is essentially the electronic control device performing a power check on the wheel sensor and the control valve of the hydraulic regulator according to the self-test procedure. If the light remains off, it means that the ABS is faulty.
5. Don’t panic if the ABS indicator light does not go out. When the ABS fails while driving, the anti-lock braking system automatically connects the oil circuit of the original braking system. The original braking system on the car still works, but without ABS. Just pay attention to maintenance.
6. Do not replace the ABS computer unit without permission. If the computer detects a fault, the entire ABS unit should be replaced.
7. For vehicles that are equipped with ABS but wish to be modified, do not disassemble and install the nuts connecting the brake pipes to the ABS unit.
ABS is divided into electronic ABS and mechanical ABS
1. Electronic ABS is designed according to different models. Its installation requires professional technical force. If it is replaced, To use it in another vehicle, you must change its circuit design and battery capacity, and there is no universality; mechanical ABS is highly versatile and can be used on any vehicle with a hydraulic brake device, and can be changed from one vehicle to another. on the car, and installation only takes 30 minutes.
2. Electronic ABS is large in size, and the finished vehicle may not have enough space to install electronic ABS. In contrast, mechanical ABS is smaller in size and takes up less space.
3. Electronic ABS starts working when the wheels are locked, and works 6 to 12 times per second; mechanical ABS starts working when the brakes are applied, and works every second depending on the vehicle speed. Can be used 60 to 120 times.
The applicable characteristics of mechanical ABS need to be set in advance. On watery roads, ice and snow roads, gravel roads, and asphalt roads, the friction coefficients of tires are different, the vehicle speeds are different, and the required braking force is also different. . There is no real-time measurement feedback system, and it only relies on preset threshold values. The applicable range is narrow and the braking effect will be reduced.
Be very careful when purchasing a mechanical ABS anti-lock braking system. Counterfeit ABS products are similar in appearance and structure to genuine products, but inferior products cannot withstand the corrosion and high pressure of brake fluid for a long time. Over time, the rubber will age and deform, losing its proper performance.
The genuine rubber valve bag can withstand a high pressure of 11,000 pounds per square inch when soaked in brake fluid and will not deform for a long time. The price of imported mechanical ABS is around 2,000 yuan, while the domestic one only costs more than 200 yuan.
[Edit this paragraph]ABS function
C
Function name: abs
Function: Find the absolute value of an integer
Usage: int abs(int i);
Program example:
#include
#include
int main(void)
{
int number = -1234;
printf("number: %d absolute value : %d\n", number, abs(number));
return 0;
}
Pascal
Function Abs ( ( (Longint) 111222333 }
Writeln( Abs(-1112223334324445556) ); {(Int64) 1112223334324445556 }
End.
[Edit this paragraph]ABS plastic
ABS plastic
Chemical name: Acrylonitrile-butadiene-styrene polymer
English name: Acrylonitrile Butadiene Styrene (ABS)< /p>
Applications: Automotive accessories (dashboards, tool hatches, wheel covers, mirror boxes, etc.), radio cases, phone handles, heavy-duty tools (vacuum cleaners, hair dryers, blenders, lawn mowers) etc.), typewriter keyboards, entertainment vehicles such as golf carts and jet sleds, etc.
Specific gravity: 1.05 g/cubic centimeter
Combustion identification method: continuous combustion, blue with yellow Flame, black smoke, light marigold smell
Solvent experiment: cyclohexanone can soften, aromatic solvents have no effect
Drying conditions: 80-90°C for 2 hours
Molding shrinkage rate: 0.4-0.7%
Mold temperature: 25-70℃ (mold temperature will affect the finish of the plastic part, lower temperature will lead to lower finish)
Melting temperature: 210-280℃ (recommended temperature: 245℃)
Molding temperature: 200-240℃
Injection speed: medium to high speed
Injection pressure: 500-1000bar
Features:
1. Good comprehensive performance, high impact strength, chemical stability, and good electrical properties.
2. Compared with 372 Plexiglas has good weldability and can be made into two-color plastic parts, and the surface can be chrome-plated and spray-painted.
3. It has high impact resistance, high heat resistance, flame retardant, reinforced, transparent and other levels.
4. The fluidity is slightly worse than HIPS, better than PMMA, PC, etc., and has good flexibility.
5. Use: Suitable for making general mechanical parts, wear-reducing and wear-resistant parts, transmission parts and telecommunications parts.
6. Same as PVC (polyvinyl chloride) at the inflection point Whitening will occur.
Molding characteristics:
1. Amorphous material, medium fluidity, high moisture absorption, must be fully dried, plastic parts requiring glossy surface must be preheated and dried for a long time at 80-90 degrees , 3 hours.
2. It is advisable to use high material temperature and high mold temperature, but if the material temperature is too high, it will easily decompose (the decomposition temperature is >270 degrees). For plastic parts with higher precision, the mold temperature should be Take 50-60 degrees. For high-gloss and heat-resistant plastic parts, the mold temperature should be 60-80 degrees.
3. If you need to solve the problem of water marks, you need to improve the fluidity of the material and use high-quality materials. temperature, high mold temperature, or changing the water inlet level.
4. If heat-resistant or flame-retardant materials are formed, plastic decomposition will remain on the mold surface 3-7 days after production, causing the mold surface to shine. The mold needs to be cleaned in time, and the mold surface needs to be cleaned. Increase the exhaust position.
ABS resin is currently the polymer with the largest output and the most widely used. It organically unifies the various properties of PS, SAN, and BS, and has excellent mechanical properties with balanced toughness, hardness, and rigidity. . ABS is a terpolymer of acrylonitrile, butadiene and styrene. A represents acrylonitrile, B represents butadiene, and S represents styrene.
ABS engineering plastics are generally opaque, have a light ivory appearance, are non-toxic and odorless, and have tough, hard and rigid properties. They burn slowly, with a yellow flame and black smoke. After burning, the plastic Softened, burnt, with a special cinnamon smell, but no melting or dripping.
ABS engineering plastics have excellent comprehensive properties, including excellent impact strength, good dimensional stability, electrical properties, wear resistance, chemical resistance, dyeing properties, and are good for molding and machining. . ABS resin is resistant to water, inorganic salts, alkali and acids, insoluble in most alcohols and hydrocarbon solvents, but easily soluble in aldehydes, ketones, esters and certain chlorinated hydrocarbons.
Disadvantages of ABS engineering plastics: low heat distortion temperature, flammable, and poor weather resistance.
ABS classification society certification icon
ABS: abbreviation of American Bureau of Shipping.
[Edit this paragraph] Asset-backed securities
ABS: Asset-backed securities (also called asset-backed securities or asset-backed securities, English: Asset-backed security) are provided by banks and credit card companies A bond or note issued as security under a loan agreement or receivable from another credit provider; it is distinguished from a mortgage.
ABS is a securitization financing method supported by non-housing mortgage loan assets. It is actually the promotion and application of MBS technology to other assets. Since one of the basic conditions for securitization financing is that the underlying assets can generate predictable and stable cash flows, in addition to housing mortgage loans, there are many assets that also have this characteristic, so they can also be securitized. With the continuous development of securitization technology and the expansion of the securitization market, the types of ABS are becoming increasingly diverse, which can be subdivided into the following types: (1) securitization of automobile consumer loans and student loans; (2) commercial, agricultural, Securitization of medical real estate mortgages; (3) Securitization of credit card receivables; (4) Securitization of trade receivables; (4) Securitization of equipment rental fees; (5) Securitization of infrastructure charges; (6) Ticket revenue Securitization; (7) Securitization of club dues income; (8) Securitization of premium income; (9) Securitization of small and medium-sized enterprise loan support; (10) Securitization of intellectual property rights, etc. And with the continuous development of asset securitization technology, the scope of securitized assets is constantly expanding.