Differential Rear-Wheel Steering with Clutch-Switched Dual Modes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing active rear-wheel steering systems face reliability issues due to multiple actuators, leading to uncoordinated steering when one motor fails, and are limited in improving both steering and braking performance.
Innovation Solution
A dual-mode active rear-wheel steering device utilizing a differential principle with two electromagnetic clutches and a single motor to control rear-wheel steering, allowing independent or synchronized steering based on clutch states, and incorporating a modified differential mechanism for enhanced reliability and simplicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two independent steering motors are used to control rear wheels to steer in opposite directions for braking mode, then directional stability during braking is improved, but system cost increases and reliability decreases
Solution Approach 1:
The patent merges the steering control function into a single actuator system that controls both rear wheels through a differential mechanism. Instead of using two independent motors, one motor drives a differential mechanism that distributes torque to both rear wheels, enabling independent steering angles while reducing component count and improving reliability.
Solution Approach 2:
The single actuator system is designed to perform multiple functions: it can control both rear wheels to steer in the same direction for normal steering mode, and in opposite directions for braking mode to enhance directional stability. This multi-functionality eliminates the need for separate actuators for different operating modes.
2Reliability
If two distributed actuators are employed to control rear wheels to simultaneously turn inward for braking mode, then directional stability when braking at high speed is improved, but system cost and complexity increase
Solution Approach 1:
The patent combines the control of both rear wheels into a single actuator system with a differential mechanism. This ensures coordinated steering action between the two rear wheels while avoiding the complexity and reliability issues of using two separate actuators.
Solution Approach 2:
The differential mechanism acts as an intermediary between the single actuator and the two rear wheels. It translates the single actuator's output into differential steering angles for the left and right rear wheels, enabling precise control for both steering and braking modes without requiring two independent actuators.
3Device complexity
If a single actuator is used to control rear-wheel steering through a steering mechanism, then system simplicity is improved, but the ability to independently control steering angles of two rear wheels is limited
Solution Approach 1:
The differential mechanism serves as an intermediary that enables a single actuator to independently control the steering angles of both rear wheels. By incorporating this mechanism, the system maintains simplicity with one actuator while gaining the versatility to control each rear wheel's steering angle independently for different driving conditions.
Solution Approach 2:
The system dynamically adjusts the steering angles of the rear wheels based on driving conditions. The differential mechanism allows the system to switch between steering mode (both wheels turn same direction) and braking mode (wheels turn opposite directions) by controlling the distribution of torque to each wheel, providing adaptability with a single actuator.
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 system provides reliable, energy-efficient steering and braking modes with reduced complexity, ensuring coordinated steering and improved safety by avoiding uncoordinated steering failures and enhancing vehicle stability.
Implementation Method 1
a first electromagnetic clutch; and a second electromagnetic clutch; wherein the first electromagnetic clutch is arranged between the differential mechanism assembly and the speed-reduction mechanism; and the first electromagnetic clutch is configured to control connection between a differential housing of the differential mechanism assembly and the housing assembly
Data Source
AI summary
A dual-mode active rear-wheel steering device, including: a steering angle control motor, a speed-reduction mechanism, a differential mechanism assembly, two steering motion conversion mechanisms, a first electromagnetic clutch and a second electromagnetic clutch. An output end of the steering angle control motor is connected to the speed-reduction mechanism. The differential mechanism assembly is a bevel gear differential, in which center holes at outer ends a two half shafts are respectively provided with a raceway to form an inner cyclical ball-lead screw-nut pair with a first lead screw and a second lead screw of the steering motion conversion mechanisms. The first lead screw and the second lead screw are the same in parameters but with opposite rotation direction. The first electromagnetic clutch controls connection between a differential housing and a frame. The second electromagnetic clutch controls connection between the differential housing and the second half shaft.