Brake System Master Cylinder Electric Booster Dynamics

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Solution Overview

Problem

Existing brake systems lack freedom of translation between the brake servo and the assistance piston, limiting braking dynamics, especially in cases of transmission failure or when driver input is more dynamic than the transmission can respond.

Innovation Solution

The brake system incorporates a boost piston guided within an actuator piston forming a guide cylinder, with a support flange for a return spring acting on the master cylinder housing, and an assistance piston with a unidirectional drive stop, allowing independent movement between the brake servo and assistance piston, enhanced by a differential stroke sensor and secure rotation connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rigid transmission connection is used between the brake servo and assistance piston, then the mechanical strength and reliability are improved, but the braking dynamics deteriorate due to inertia and friction losses

Engineering Contradiction:
Improvetransmission reliabilityVSAvoidbraking dynamics
Core Design Contradiction:
ReliabilityVSSpeed

Solution Approach 1:

The rigid transmission connection is segmented into two independent piston movements: the actuator piston movement driven by the brake servo, and the assistance piston movement driven by the spring. This allows each piston to move independently, eliminating the inertia and friction losses of a rigid connection while maintaining reliability through the direct action mechanism.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system transitions from a static rigid connection to a dynamic flexible connection where the assistance piston can move independently. The spring-based connection allows the assistance piston to follow the actuator piston movement dynamically without the constraints of a rigid mechanical link, improving braking response speed.

Inventive Principle:
Principle #15Dynamics

2Strength

If a rigid transmission connection is used between the brake servo and assistance piston, then the mechanical strength is improved, but the loss of energy due to inertia and friction increases

Engineering Contradiction:
Improvetransmission strengthVSAvoidenergy loss in transmission
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The rigid transmission connection is extracted and replaced with a direct action mechanism. The assistance piston is directly acted upon by the actuator piston through the spring mechanism, eliminating the intermediate rigid transmission components that cause energy losses due to inertia and friction.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The spring-based direct action mechanism serves as an intermediary between the actuator piston and assistance piston. This intermediary allows force transmission without the energy losses associated with rigid mechanical connections, as the spring can transmit force while allowing independent piston movement.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Stability of the object's composition

If the assistance piston is constrained to move only with the actuator piston, then the mechanical stability is improved, but the adaptability to dynamic driver input deteriorates

Engineering Contradiction:
Improvemechanical stabilityVSAvoidadaptability to driver input
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The constrained single-movement system is segmented into two independent piston movements. The actuator piston responds to the brake servo while the assistance piston responds independently to spring forces and direct action, allowing the system to adapt to dynamic driver input while maintaining mechanical stability through the direct action mechanism.

Inventive Principle:
Principle #1Segmentation

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

This design improves braking dynamics during transmission failures or dynamic driver input without loss of effort due to inertia or friction, maintaining efficiency and preventing dynamic limitations at the brake servo output.

Implementation Method 1

the boost piston has a support flange for a return spring, the other end of which is pressed against the housing of the master cylinder and which acts in the direction of the return of the assistance piston

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

the skirt which extends the assistance piston towards the rear houses a differential stroke sensor cooperating with the control rod and detecting the differential movement of the control rod

Methodology Applied
Scientific EffectDifferential movement detection:

Data Source

PatentEP2475560B1Braking system comprising a master cylinder and an electric brake booster
Publication Date: 2016.10.12 ROBERT BOSCH GMBH
  • EP2475560B1 patent drawingFigure 1
  • EP2475560B1 patent drawingFigure 2

AI summary

The invention relates to a brake system (1) including a master cylinder (10) and an electric brake booster (20) and comprising an actuator piston that acts on the push rod (47) which is applied against the reaction disc (46), controlled by the plunger (60) which is connected to the control rod (70) and housed in a sleeve (55) of the booster piston (50). The booster piston (50) is returned by a return spring (45) and the plunger by a spring (63) between the booster piston and a collar (62).