A) Threshold load B) Loop in (tolerance range) C) Boost ratio ( i ) D) 90 % kneepoint pressure E) Kneepoint pressure F) Efficiency G) Beginnig of air absorbtion H) Hysteresis I) 10 % residual pressure J) Push back force K) Auxiliary force L) Higher vacuum level M) Function without vacuum
Brakes Applied 实施制动
- Force applied to the input rod opens theair valve - Vacuum in the rear chamber decreases,hence increasing the pressure differential - Diaphragm moves forward until the output rod force is equal to the input force multiplied by the boost ratio - Reaction disc extrudes around ratio disc - When the output force becomes greater than the input force multiplied by the boost ratio, the reaction disc extrudes further pushing the plunger valve back and closing the air valve
Pic. 12
Just after kneepoint 略高于拐点
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 13
Plunger pushed VB 柱塞顶在阀体上
P F
Principle of function –Actuation
Actuation Principle of function
真空助力器制动主缸功能原理
No Vacuum Condition 无真空状态
Working Chamber Vacuum Chamber 真空腔 工作腔 Vacuum Valve 真空阀
Air Valve Open Vacuum Valve Closed Key seated against rear shell Plunger valve seated on reaction disc 空气阀打开 真空阀关闭 键靠在后壳体上 柱塞阀顶在反作用盘上
第一活塞
Vac. non return valve
真空单向阀
Principle of function –Actuation
真空助力器制动主缸功能原理
Sniffle holes 补偿孔 Reaction disc 反作用盘
Pic. B
Symbolism 符号
0,8 bar Vak
真空
Split linie booster – mc 助力器主缸分界线
LSC 115 T HE DR shown in balance position LSC 115 HE DR 平衡状态示意图
Principle of function –Actuation
真空助力器制动主缸功能原理
Fluid reservoir 制动液贮液罐 Vacuum chamber 真空腔 Brake fluid 制动液 Reaction piston 反作用杆 Booster housing 助力器壳体 Dilag bush 前围板 Poppet 提升阀
Principle of function –Actuation
真空助力器制动主缸功能原理
主要功能曲线
室温性能.
主缸第一腔压力 (bar)
特性曲线
• 加力速度约 3,5 mm/s • 升压速度 15 +/- 5 bar/s
原始图表
助力器输入力( N )
A) 起始力 B) 圆弧段上点 (允差范围) C) 助力比 ( i ) D) 90 % 拐点压力 E) 拐点压力 F) 效率 G) 开始抽大气 H) 滞后 I) 10 % 剩余压力 J) 回推力 K) 助力 L) 更高真空度 M) 无真空曲线
Air Valve 空气阀
At Balance 平衡状态
- Vacuum in front chamber pulls the diaphragm plate forward - Air valve closes - Vacuum valve opens - Vacuum in the working chamber increases until the pressure differential has reduced to ‘balance’ the diaphragm plate with both the air and vacuum valves closed -真空腔的真空吸引膜片盘向前运动
Patm - Ambient Atmospheric Pressure
Pw - Working Chamber Pressure
Pvac - Vacuum Chamber Pressure
Brakes Released 释放制动（减轻制动）
-Vacuum valve opens -真空阀打开 - Vacuum in the rear chamber increases, hence reducing the pressure differential -工作腔真空增加，因此两腔压力差降低 -Diaphragm plate assembly returns to the ‘balance’ (vacuum and air valves both closed) position due to the action of the main spring -在主回位弹簧的作用下，膜片盘组件回 复到“平衡状态”（空气阀及真空阀均为 关闭状态）。
Atmospheric
大气压
Diaphragm 膜片
Poppet and springs 提升阀及弹簧
Brake fluid (pressure less) 制动液（小压力）
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 1
Without vac. 不通真空
功能曲线的变化
Input load 输入力 ( N )
Principle of function –Actuation
Pic. 10
Nom. control range 正常控制范围
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 11
Just below kneepoint 拐点之下
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
真空助力器制动主缸功能原理
Pic. 4
First air intake 首次进入空气
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 5
MC closed 主缸关闭空行程
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 8
Sec. Pressure 第二腔建压
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 9
Loop in range 圆弧段
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
真空助力器制动主缸功能原理
Pic. 14
High above kneepoint 远高于拐点
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Primary pressure MC (bar)
Main function curve
Characteristic
Function at room temp / With volume displac.
• Application speed about 3,5 mm/s • Pressure rise 15 +/- 5 bar/s
Booster input load ( N ) Original diagram
B) 10“-Booster / 0,8 bar A) 9“-Booster / 0,8 bar
150
I =5,
60
3,8 5
I=
I=
3 ,2
100
0
Control range 控制范围
Without vacuum 无真空
MC - Ø = 20,64 mm 100 200
Variations of function curve
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 2
Evacuated 通真空
P F
Principle of function –Actuation
真空助力器制动主缸功能原理
Pic. 3
Lost stroke 空行程