Light Duty Truck Brake System Problem Analysis And Optimization Design

So far,hydraulic braking system has been used in most domestic light duty truck.The problem of brake cotton,brake pedal force and braking direction stability appearing during brake,affects the running safety of the light duty truck.It is necessary to fundamentally solve the above-mentioned key technical problems.Based on the current situation of the light duty truck,the paper analyzes the root cause that makes the brake soft,the brake pedal light and sink,and the stability of the steering direction poor.In view of the problem of brake 'cotton' and the brake pedal lightness,through the braking system matching calculation,list the ideal braking force of the front and rear brake of the prototype in different adhesion coefficient road under the empty and full load condition and different hydraulic pipeline.Through the contrast analysis,conclude that the front axle brake power shortage is the fundamental cause of the problem.By adjusting the front axle brake wheel cylinder diameter and effective working radius of the brake lining block,improve the braking force of the front axle brake.Then,recalculate the braking force of the front and rear brake,analyze and verify the displacement of the brake master cylinder to meet the design requirements.In view of the problem of brake "cotton" and brake pedal sinking,compared with a domestic brand benchmark car,we found the different structure of the brake master cylinder,and then analyzed the structure of vacuum booster with test data and active master cylinder,and found the root cause of brake cotton and brake pedal sinking.Then the brake master cylinder is optimized,and the brake master cylinder is replaced with a new generation of plunger type brake master cylinder,and the actual vehicle is verified to meet the design requirements.In view of the problem of poor directional stability when braking,take a light duty truck A1A11K1DE01 of our company for example,do in-depth analysis of the back wheel tail phenomenon when emergency braking under no-load condition,by using EXCEL tools,programme to establish the braking system matching calculation template of the vehicle,analyze the force,draw out the ideal and actual brake force distribution curve(I curve)and line(? line)of the front and rear brake,found that the inflection point of the line ? under no-load condition is always above the curve I,resulting in the rear wheel locked first when braking with tail phenomenon.The unreasonable matching of hydraulic load sensing proportional valve is the root cause of the poor directional stability of the vehicle under no-load condition.Distribution of the load sensing valve to adjust the hydraulic ratio on vehicle re matching calculation,draw the curve using the adhesion coefficient and braking intensity,and the use of national laws and regulations GB 12676-2014<commercial vehicle and trailer braking system technical requirements and test methods>requirements of the adhesion coefficient is compared to the regulations limit,to make it fully meet the braking regulations.In order to further improve the light duty truck brake directional stability and solve the problem of losing the steering ability,when braking,the front wheel is locked,adjust the model of the hydraulic load-sensing proportional valve to hydraulic ABS,and take the winter and summer matching test of the prototype Up to one year.The performance indicators can meet and exceeded requirement of the national regulations GB/T 13594 'Motor vehicle and trailer anti-lock braking performance and test methods'requirements.