Emergency braking response characteristics of polyol ether borate (PEB) brake fluid in a wide temperature range

In order to further expand the application of polyol ether borate (PEB) brake fluid in the vehicle braking system in the wide temperature range, and explore the impact of PEB brake fluid on the vehicle emergency braking response, three PEB brake fluid samples with different formulations are prepared with PEB as the base fluid and polyol ether (PE) as the diluent. The brake master cylinder test system and vehicle braking performance test bench are built, and the emergency braking response time of the brake master cylinder and the 80 km/h emergency braking distance of the vehicle are tested at different temperatures. The test results show that the higher the mass ratio of diluent in the PEB brake fluid or the higher the ambient temperature, the lower the viscosity of the PEB brake fluid. Low viscosity PEB brake fluid can shorten the emergency brake response time of the brake master cylinder and the emergency braking distance of the vehicle at the same temperature, and this rule becomes more obvious with the decrease of temperature. The brake master cylinder response time was reduced by 41.7% (−30°C) and the vehicle emergency braking distance was reduced by 2.92 m (−10°C) at most. The reduction of viscosity reduces the resistance of viscous force to the flow field when the PEB brake fluid flows in the hydraulic pipe. The smaller the pressure loss in the transmission process, the faster the brake response can be made. At low temperatures (<0°C), temperature has a greater influence on the viscosity of PEB brake fluid, and the reduction of temperature magnifies the viscosity difference between three PEB brake fluid samples.