Brake Booster Piston Segmentation for Emergency Actuation
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Solution Overview
Problem
Existing brake systems with electric brake boosters are complex, large, and costly, with inefficiencies in emergency operations where the motor fails, requiring excessive force to overcome multiple return springs for brake actuation.
Innovation Solution
The brake system simplifies the electric brake booster design by incorporating a bearing shoulder for the return spring, a retaining member for the actuator piston, and a stop collar for unidirectional driving of the assistance piston, allowing independent advancement to actuate the master cylinder in failure scenarios, with a return spring between the actuator and plunger piston stops to limit control stroke and prevent spring destruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric brake booster uses multiple return springs (return spring 45 and return spring 63) to ensure reliable brake actuation, then the reliability of brake operation is improved, but the force required to actuate the brakes in emergency failure mode increases excessively
Solution Approach 1:
The return spring 63 is segmented into two separate return springs: one acting on the plunger piston 60 and another acting on the actuator piston 40. This segmentation allows each spring to independently perform its return function, eliminating the need for the plunger piston to overcome the cumulative force of both springs during emergency actuation.
Solution Approach 2:
The actuator piston 40 serves as an intermediary element between the plunger piston 60 and the master cylinder piston 11. In normal operation, it transmits force from the motor 30. In emergency failure mode, it independently returns via its own return spring 45 while allowing the plunger piston to directly actuate the master cylinder, mediating the force transmission to avoid cumulative spring resistance.
2Adaptability or versatility
If the brake booster housing includes a guide sleeve 55 and intermediate piston 61 for direct control rod action, then the adaptability for emergency failure operation is improved, but the device complexity increases
Solution Approach 1:
The actuator piston 40 is designed with dual functionality: it serves as the driven element during normal motor-assisted operation and as an independent return mechanism during emergency failure. The bearing shoulder 41 and retaining member 123 provide universal support structures that function in both normal and emergency modes, reducing the need for separate dedicated emergency components.
Solution Approach 2:
The control mechanism is inverted so that during emergency failure, the plunger piston 60 directly actuates the master cylinder piston 11 through the reaction disc 46, bypassing the normal motor-driven actuator piston pathway. This inversion allows the system to use existing components in reverse or alternative configurations to achieve emergency braking without adding complex dedicated emergency systems.
3Manufacturing precision
If the actuator piston 40 directly drives the assistance piston 50 with a stop flange 51, then the manufacturing precision requirements are reduced, but the ease of operation during emergency failure is worsened due to gap S
Solution Approach 1:
The stop flange 51 forming the internal shoulder 41 is extracted from the actuator piston 40 and repositioned as a separate bearing shoulder 41 on the actuator piston. This extraction allows the actuator piston to have a simpler cylindrical structure that can independently return via the return spring 45, while the bearing shoulder provides the necessary support for the plunger piston without creating operational gaps during emergency failure.
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 reduces system size, increases efficiency in failure modes by minimizing forces needed for brake actuation, and lowers costs by simplifying structure and assembly, ensuring effective brake operation with reduced risk of component damage.
Implementation Method 1
the actuator piston has a bearing shoulder for a return spring, the other end of which presses against the master cylinder housing and which acts in the direction of the return of the actuator piston
Implementation Method 2
The brake booster 20 consists of a housing 21 carrying an electric motor 30 driven by a transmission 31 not detailed, an actuator piston 40 sliding in the cylinder 22 of the housing 21
Data Source
Figure 1
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AI summary
The system (100) has an actuator piston (140) including a rear shoulder (151) forming a stop against which a thrust flange (143) of the piston rests, for driving the piston during normal operation. An assistance piston (150) freely advances with respect to the actuator piston under the thrust of a control rod (170) for actuating a piston (111) of a master cylinder (110) in case of failure of an electric brake booster (120). A return spring (163) is arranged between the thrust flange and the actuator piston.