Vacuum Brake Booster Throttle Control Valve Assembly
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Solution Overview
Problem
Vacuum brake boosters experience instabilities and noise due to air stream instabilities at the control valve assembly, which are exacerbated by high flow rates, and existing solutions using materials prone to contamination and wear lead to functional degradation over time.
Innovation Solution
A control valve assembly with a flow restricting sleeve that is preloaded and displaceable, featuring a flow restricting window and a stop flange, which restricts airflow when the actuating piston is displaced within a predetermined functional path, reducing the need for rubber-elastic materials and minimizing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the first valve seat is opened to connect the working chamber to the atmosphere, then air flow rate increases to build pressure difference, but air stream instabilities occur causing vibrations and noise
Solution Approach 1:
The patent changes the parameter of airflow cross-section by using a changeable inflow cross-section design. The baffle plate with protruding stop edge and flexible air filter create a variable opening area that adapts to different operating conditions, restricting airflow during unstable conditions while allowing higher flow when stable
Solution Approach 2:
The patent applies dynamics by making the air filter flexible and the baffle plate displaceable. The flexible air filter deforms with airflow pressure changes, and the baffle plate can move relative to the housing, creating a dynamic flow restriction system that automatically adapts to pressure differentials and flow conditions
2Ease of operation
If rubber-elastic materials are used in the control valve assembly to control airflow, then flexibility and sealing are improved, but contamination and wear increase leading to functional degradation
Solution Approach 1:
The patent changes the material parameter from rubber-elastic to metal materials for the baffle plate and valve seats. This substitution eliminates the contamination and wear issues associated with rubber while maintaining flow control capability through the geometric design of the changeable inflow cross-section
Solution Approach 2:
The patent replaces the rubber-elastic material-based flow control mechanism with a mechanical system consisting of a metal baffle plate and flexible air filter. The flow control is achieved through the relative displacement and geometric configuration of rigid components rather than material elasticity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces instabilities and noise by ensuring controlled airflow, maintaining robustness and wear resistance, and enabling rapid pressure build-up during high brake force applications.
Implementation Method 1
the flow restricting sleeve is provided with at least one flow restricting window and wherein the flow restricting sleeve is displaceable by a predetermined functional path from the normal position relative to the control valve housing upon an actuation of the force input member
Implementation Method 2
a return spring acting on the flow restricting sleeve in the actuating direction of the actuating piston
Implementation Method 3
By fluidically connecting the at least one working chamber either to a vacuum power source, for example the intake manifold of a combustion engine, or to the surrounding atmosphere by means of the control valve assembly, a pressure difference can be built up at the at least one movable wall
Data Source
AI summary
A vacuum brake booster for a motor vehicle brake system, comprising a displaceable force input member that is coupled to or can be coupled to a brake pedal, a chamber arrangement arranged in a booster housing having at least one working chamber and at least one vacuum chamber, which are separated from one another via at least one movable wall, a control valve assembly that can be actuated by the force input member, and a force output member for transmitting an operating force to a downstream brake system. The at least one working chamber can be fluidically connected optionally to a negative pressure source or the atmosphere by way of the control valve assembly. The control valve assembly comprises a control valve housing, in which an actuating piston that is coupled with the force input member s displaceably arranged, and a first valve seat, and a second valve seat. Upon an actuation of the force input member, a throttle sleeve can be displaced from the initial position relative to the control valve housing by a predetermined functional path. During the displacement, the throttle sleeve is in abutment with the actuating piston such that a fluidic connection between the at least one working chamber and the ambient atmosphere by way of a throttle window is present. Upon exceeding the functional path, the throttle sleeve lifts off the actuating piston.