Selectable Clutch Parking Lock to Prevent Vehicle Freewheeling
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Solution Overview
Problem
Conventional vehicle parking lock systems face issues such as poor user perception, high strength requirements, excessive energy consumption, complex control systems, and increased costs due to freewheeling before the brake engages, and the inability to independently switch between different operating modes.
Innovation Solution
A vehicle parking lock system utilizing a selectable clutch with four operating modes (two-way lock, forward lock, reverse lock, and two-way free) controlled by sensors to prevent unintended vehicle movement, reducing freewheeling and energy consumption, and simplifying the control process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional parking pawl system is used, then the output shaft can be locked, but the vehicle experiences freewheeling and rolls away before the pawl engages, causing poor user perception and requiring high strength to withstand impact
Solution Approach 1:
The selectable clutch is activated before the parking pawl engages with the parking gear, preliminarily locking the output shaft to prevent freewheeling and vehicle rollback. This preliminary action eliminates the impact shock that would otherwise occur when the pawl engages, reducing the strength requirements for parking lock components.
2Ease of operation
If the drive force of the engine or motor is used for temporary stops on slopes, then the vehicle can be held at halt, but significant energy is consumed and heavy burden is placed on transmission components
Solution Approach 1:
The selectable clutch provides a mechanical locking solution that replaces the need to rely on continuous engine or motor drive force for holding the vehicle on slopes. By mechanically locking the transmission output, the system eliminates energy consumption associated with maintaining temporary stops through powertrain engagement.
3Reliability
If conventional hill start assist using foot or parking brake is used, then the vehicle can be temporarily stopped, but extra energy is required to generate hydraulic pressure or wire tension
Solution Approach 1:
The selectable clutch provides a direct mechanical locking mechanism that replaces the need for hydraulic brake systems or cable-based parking brakes. This mechanical substitution eliminates the energy required to generate hydraulic pressure or wire tension, while providing more reliable hold capability for hill start assist functionality.
4Adaptability or versatility
If selectable clutches are used to engage shaft with two gear trains, then parking lock can be established, but complex control of operating modes and increased number of components is required
Solution Approach 1:
A single selectable clutch is designed to provide multiple operating modes (two-way lock mode, forward lock mode, reverse lock mode, and two-way free mode), making it a universal component that replaces what would otherwise require multiple separate clutches. This multi-functionality reduces the number of components and simplifies control system complexity while maintaining adaptability for various parking lock scenarios.
Data Source
AI summary
An object of the present invention is to provide a vehicle parking lock system that realizes a parking lock with a positive user perception, and enables energy and cost reductions without complex control and with a simple configuration. The object is achieved by a selectable clutch configured to be switchable between four operating modes and provided to one of an input shaft, an output shaft, and an intermediate shaft of a transmission. The operating mode of the selectable clutch is controlled based on detection signals of a plurality of sensors to prevent an unintended movement of the vehicle when the vehicle is stationary.