Four-Wheel Steering Control via Inverted Rear Wheel Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing four-wheel steering systems for vehicles, such as self-propelled sprayers, do not allow wheel passage in reverse gear and pose safety risks during high-speed two-wheel steering, as they lack the ability to prevent inadvertent switching to four-wheel steering mode.
Innovation Solution
A hydraulic steering system with an orbitrol, first and second steering cylinders, and sensors that utilize a four-port, three-state valve and additional three-port, two-state valves to control the steering angles of both front and rear wheels, enabling wheel passage in both forward and reverse gears while maintaining safety by preventing unintended mode switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If steering angle information is transmitted from front wheels to rear wheels, then wheel passage is enabled in forward gear, but wheel passage is prevented in reverse gear
Solution Approach 1:
The patent inverts the traditional steering control architecture by making the rear wheels the primary controlled elements and the front wheels the secondary elements. The rear steering cylinder is controlled directly by the orbitrol based on rear wheel steering angle, while the front steering cylinder is controlled by copying the rear wheel's steering angle information. This inversion enables bidirectional wheel passage capability in both forward and reverse gears.
2Ease of operation
If four-wheel steering mode is enabled, then wheel passage capability is improved, but safety risk increases due to potential inadvertent mode switching
Solution Approach 1:
The patent implements feedback mechanisms through sensors that continuously monitor the steering angles of both front and rear wheels. The first sensor measures the steering angle of the front wheels and provides information to the orbitrol, while the second sensor measures the steering angle of the rear wheels and provides feedback to the four-port three-state valve. This closed-loop feedback ensures accurate control and prevents inadvertent mode switching by continuously verifying the actual steering state against the commanded state.
Solution Approach 2:
The patent introduces a four-port three-state valve as an intermediary control element between the orbitrol and the steering cylinders. This valve acts as a mediator that receives steering angle information from sensors and translates it into appropriate hydraulic control signals for the steering cylinders. The valve's three-state capability (forward gear, reverse gear, and neutral) provides an additional layer of safety by ensuring that mode switching only occurs when properly commanded, preventing accidental activation of four-wheel steering mode.
3Power
If orbitrol controls front steering wheels, then power steering is achieved, but control flexibility is reduced
Solution Approach 1:
The patent makes the orbitrol a universal power source that can control either the front or rear steering wheels depending on the operating mode. In forward gear, the orbitrol controls the front steering cylinder; in reverse gear, it controls the rear steering cylinder. This multi-functionality is achieved through the four-port three-state valve that redirects hydraulic power from the orbitrol to the appropriate steering cylinder based on the selected gear mode, providing both power steering capability and control flexibility.
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 allows for smooth wheel passage in both directions and enhances safety by ensuring the rear wheels remain in a neutral position during two-wheel steering mode, preventing unintended mode changes and ensuring stable vehicle operation.
Implementation Method 1
a hydraulic steering system for a vehicle, in particular a self-propelled sprayer, comprising an orbitrol powered by a hydraulic source
Implementation Method 2
a four-port, three-state valve powered by a hydraulic source, a first chamber of the first cylinder being hydraulically connected to a first output of the orbitrol and to a first output of the four-port, three-state valve by a first valve with three ports and two states
Data Source
Figure 1
Figure 2~5
AI summary
The system has a sensor (16) measuring steering lock angle of front wheels (12) of a vehicle, and a sensor (17) measuring steering lock angle on rear wheels (11) of the vehicle. The sensor (17) controls a distributor (14) with three states and four openings to supply power, using a hydraulic source (2), to a steering cylinder (20) on the rear wheels in vehicle movement direction, so that the steering lock angle in the direction is equal to a setpoint value according to a direction mode of the vehicle, and value of the steering lock angle measured by the sensor (16) in the direction.