Classification Of Brake Master Cylinder
01-Single Chamber or Dual Chamber?
The main function of the brake master cylinder is to convert the mechanical energy exerted on the brake pedal into brake hydraulic energy, and transfer the brake fluid with a certain pressure through the brake pipeline to the brake wheel cylinder of each wheel, and then from the wheel brakes are converted into wheel braking force. Brake master cylinders are divided into single-chamber type and double-chamber series types, which are respectively used in single-circuit and dual-independent circuit systems . The double-chamber series is divided into compensation hole type and center valve type. Due to safety factors and mechanical complexity, at present, the dual-chamber series compensation type is widely used in the master cylinder.
02-How does the brake master cylinder work?
The principle is as follows: when braking, when the driver steps on the foot pedal, the foot pedal pushes the piston forward through the push rod. The forward-moving piston drives the main cup to pass the compensation hole. At this time, the hydraulic pipeline is closed, and the pedal force continues to be transmitted downward through the brake fluid.
When the driver quickly releases the brake pedal, the return spring will push the piston to return quickly, because the return speed is often smaller than the return speed of the piston. Then during this process, there will be a short-term negative pressure (vacuum) phenomenon in the pressure chamber (making the piston unable to return). Negative pressure will force the cup to deform downward. The brake fluid in the reservoir flows into the negative pressure area from the compensation chamber through the gap and the small hole on the piston to relieve the negative pressure condition and prevent air from entering. The excess brake fluid that continues to flow back in the pipe returns to the reservoir through the compensation hole to prepare for the next braking stroke.
A traditional master cylinder consists of two main parts: the reservoir and the master cylinder. The reservoir provides the brake fluid required for the master cylinder to operate. All liquid storage tanks today are of split design, which means that two independent piston chambers are supplied with oil by two independent liquid storage areas. The split design divides the hydraulic system supply fluid into the front wheel and the rear wheel, or one front wheel and one rear wheel to prevent the failure of one hydraulic system from affecting the other hydraulic system.
If a failure occurs in the second circuit, the pressure generated in the first circuit will push the second piston to the bottom of the chamber. Once this happens, the first chamber will still build pressure, and the accompanying pedal stroke will Increased when both piston chambers are active.
If the first circuit fails, since there is no pressure generated, the push rod will directly push the first piston to press on the second piston to generate pressure, and this will also produce an abnormal pedal feeling, and the driver will have a feeling of stepping on the air.
Generally speaking, the the differential pressure in the master cylinder or hydraulic system causes the brake warning light on the dashboard to light up,alerting the driver that there is a pressure loss in the brake system circuit.
03-Conclusion
Finally, the stroke and volume of the brake master cylinder should be determined according to the whole vehicle braking parameters. When designing the brake master cylinder stroke (to meet the pedal stroke standard requirements) and volume, the volume of the vehicle braking system should be considered. The amount of compression of the hydraulic fluid under high pressure, the expansion amount of the brake pipeline, the amount of fluid when the brake system is working, the pipeline layout of the whole vehicle and the idle stroke of the brake master cylinder and so on.