Since the German Karl Benz successfully developed the first single-cylinder three-wheeled vehicle in 1885, the automobile has accompanied the development of human society for more than 120 years. As the key safety system of the automobile, the braking system has been constantly updated and developed with the development and progress of the automobile. As the output heart of the working energy of the hydraulic braking system, the automobile hydraulic brake master cylinder is also constantly being developed and improved.
Figure 1 shows the position of the hydraulic brake master cylinder of the whole vehicle. Its development and changes mainly experienced the compensation type brake master cylinder, the center valve type brake master cylinder, the plunger type brake master cylinder and the automobile anti-lock brake. The development process of the brake master cylinder of the ABS system has developed different structural forms for different use requirements at different stages.
①Compensated brake master cylinder
(Such a brief introduction below)
Structure:
The main cup is located between the compensation hole and the oil supply hole, the pressure chamber and the oil supply chamber are connected through these two holes, and the master cylinder has no oil pressure output in the initial state.
Features:
1. The longest use history
2. Because the leather bowl is easy to cut with the compensation hole, the service life is low
3. The pressure build-up time of the two chambers is different
②Central valve brake master cylinder
This type of master cylinder is mainly developed to cooperate with automobile ABS. The layout of its braking system is shown in Figure 10. It is mainly used for automobiles with anti-lock braking system ABS.
Structural features:
The central valve type brake master cylinder is developed and designed to solve the shortcomings of the original brake master cylinder sealed main cup which is easy to damage and has a relatively short life, especially for high-end cars equipped with ABS (anti-lock braking system). When the ABS works, the brake fluid removed during the decompression process needs to be re-pumped into the brake master cylinder, and the brake master cylinder piston moves back and forth repeatedly due to changes in the hydraulic pressure in the master cylinder, especially when braking on a road with a low adhesion coefficient. The movement area of the main cup is very close to the compensation hole, and even reciprocates at the compensation hole. The high-pressure pulsation can easily damage the main cup of the brake master cylinder, resulting in brake failure. However, this product adopts a central valve structure due to the cancellation of the compensation hole, so this form of damage to the main leather cup is eliminated. Make driving safer and more reliable.
(While this type of master cylinder meets the manufacturing points of the tandem double-chamber brake master cylinder, it is also necessary to pay special attention to the size and shape tolerances of the control center valve assembly and the sealing surface of the piston valve to prevent the center valve from being low pressure 0.02Mpa. The following leaks, and the central valve must be able to move freely without jamming after assembly. The tightness of the central valve is very sensitive to the deviation of cleanliness, and the internal cleanliness of the master cylinder should meet the requirements of the following figure to ensure the sealing performance of the central valve )
③Plunger brake master cylinder
Structural:
The plunger-type dual-chamber brake master cylinder with the compensation hole on the piston (hereinafter referred to as the plunger-type master cylinder) is designed to solve the problem of some cars with small layout space and cannot install the traditional brake master cylinder. It has a compact structure. , Short and powerful, its internal structure is like the antenna of a TV set, and the parts are nested together, so it can be stretched and retracted like an antenna, effectively saving the axial space of the product, and its length is only about half of the traditional master cylinder. . At the same time, it can meet the requirements of car installation ABS (Anti-lock Braking System) and ESP (Electronic Stability System). It has the incomparable advantages of the traditional master cylinder. However, due to the difficulty of processing this master cylinder and the difficulty of the process, the current application scope is not large, and there are very few domestic companies that are currently doing this master cylinder. However, through the efforts of nearly one or two years, the master cylinder of this structure has increasingly shown the trend of replacing all other master cylinders through continuous structural optimization and process improvement, and has become the preferred structure of all automobiles.
Features:
(1) Short axial installation length
Because its internal parts are all nested together, the length of the assembly can be made very short, and the length is only about half of the traditional master cylinder.
⑵ Plunger master cylinder can be directly used with ABS
Brake master cylinder working （Video source blogger: Thomas Schwenke）