Single-Actuator Brake Expansion for Service and Parking Modes
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Solution Overview
Problem
Existing brake devices for motor vehicles require two actuators and expansion units to achieve both service brake and parking brake functions, leading to a complex construction.
Innovation Solution
A single actuator with a single expansion unit is used, employing different driving directions to generate either a smooth-running service brake with self-release or a self-locking mechanism for the parking brake function, utilizing a driven nut/spindle unit and non-rotatable expansion thrust pieces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If two actuators with respective expansion units are used to achieve both service brake and parking brake functions, then the brake device can perform both functions, but the construction becomes complex
Solution Approach 1:
A single actuator with a single expansion unit is designed to perform both service brake and parking brake functions by utilizing different driving directions. The actuator can generate a service brake in one driving direction and generate a self-locking mechanism for parking brake in the other driving direction, eliminating the need for two separate actuators and their respective expansion units.
Solution Approach 2:
The system dynamically switches between two different braking modes by changing the driving direction of the single actuator. In one driving direction, the expansion unit generates a service brake with self-release mechanism; in the opposite driving direction, it generates a self-locking mechanism for parking brake, allowing one component to adapt to multiple functional requirements.
2Device complexity
If a single actuator is used for both service brake and parking brake functions, then the construction is simplified, but the device must generate different braking functions from one actuator
Solution Approach 1:
The single actuator dynamically adapts to provide different braking functions by reversing its driving direction. The expansion unit responds differently to actuator movement in opposite directions: in one direction it generates service brake force with self-release capability, while in the opposite direction it creates a self-locking mechanism for parking brake, thus achieving functional versatility through dynamic behavior.
Solution Approach 2:
The system changes the operational parameters of the single actuator by reversing its driving direction to achieve different braking functions. The same actuator and expansion unit generate different mechanical outcomes (service brake vs. parking brake) by altering the direction parameter, allowing one component to fulfill multiple functional roles.
3Ease of operation
If the nut/spindle unit is supported on axial bearing for smooth force transmission, then service brake performance is improved, but parking brake self-locking capability may be compromised
Solution Approach 1:
The support configuration of the nut/spindle unit dynamically changes based on the actuator's driving direction. When the actuator drives in the service brake direction, the nut/spindle unit is supported on the axial bearing for smooth force transmission. When the actuator drives in the parking brake direction, the nut/spindle unit is supported on the coupling unit which provides self-locking capability through friction, thus adapting the support mechanism to the required function.
Solution Approach 2:
The coupling unit acts as an intermediary mechanism that provides self-locking support for the nut/spindle unit during parking brake operation. The coupling unit includes a friction pair that generates self-locking by force-fit between the nut/spindle unit and the expansion thrust piece, mediating the force transmission to achieve reliable parking brake holding without requiring continuous actuator power.
4Reliability
If friction pair is used in coupling unit for self-locking, then parking brake holding capability is improved, but energy loss increases
Solution Approach 1:
The friction-based self-locking mechanism is activated periodically only when parking brake function is required, rather than operating continuously. The actuator is energized to position the nut/spindle unit against the coupling unit's friction pair, creating self-locking. Once positioned, the system maintains holding capability without continuous energy input, and the friction action occurs only during the brief actuation period, minimizing overall energy loss while ensuring reliable parking brake holding.
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 simplifies the brake device construction by eliminating the need for dual actuators and expansion units, while maintaining effective braking performance for both service and parking brake functions.
Implementation Method 1
the coupling unit has a friction pair disposed on the nut/spindle unit and on one of the expansion thrust pieces. As a result of this design, the coupling unit generates self-locking by a force-fit.
Data Source
AI summary
A brake device for a motor vehicle has an expansion unit which is designed to, proceeding from a neutral position, in the one driving direction generate a service brake, and in the other driving direction generate a self-locking of a function of a parking brake. For this purpose, the expansion unit has a nut/spindle unit which optionally interacts with an axial bearing or a friction-fitting coupling unit.