Electrohydraulic Steer-by-Wire Actuator Circuit Redundancy
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Solution Overview
Problem
Existing steer-by-wire steering systems require multiple expensive components for redundancy, which are often unused in normal operation, limiting steering speed and response, while systems with two steering cylinders are more efficient but complex.
Innovation Solution
An electrohydraulic steer-by-wire system using a single steering actuator with two chambers connected to both electrohydraulic circuits for normal operation, allowing both circuits to contribute to steering, and employing check valves to isolate faulty circuits, ensuring continued functionality with reduced power in case of failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single hydraulic circuit is used for steering, then the device complexity is reduced, but the steering speed and response are limited
Solution Approach 1:
The patent merges both electrohydraulic circuits to simultaneously supply a single steering actuator with two chambers. Each circuit can independently drive the steering actuator, and during normal operation both circuits work together to provide enhanced steering speed and response while maintaining system simplicity through the use of one actuator rather than two separate systems.
2Reliability
If redundant components (two motors and two pumps) are provided for safety, then the reliability is improved, but the energy consumption increases and components remain unused during normal operation
Solution Approach 1:
The system dynamically switches between operating modes: during normal operation both electrohydraulic circuits are actively engaged to provide full steering capability and speed, while in the event of a fault the system automatically reconfigures to use only the functional circuit. This dynamic operation ensures redundancy is available when needed but does not permanently increase energy consumption or component idle time.
3Speed
If two steering cylinders are used to enable both circuits to operate simultaneously, then the steering speed is improved, but the device complexity and cost increase
Solution Approach 1:
The steering actuator is segmented into two chambers that can be independently supplied by the two electrohydraulic circuits. Each chamber receives hydraulic fluid from both circuits through appropriate valve control, allowing the circuits to work simultaneously on a single actuator. This segmentation enables full utilization of both circuits' capacity without requiring two separate steering cylinders, thereby maintaining simpler mechanics while achieving enhanced steering performance.
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 configuration achieves fast steering speed with reduced energy consumption and simpler component usage, allowing operators to recognize and react to errors, while maintaining sufficient steering capability during faults.
Implementation Method 1
a hydraulic pump (54, 72), the connections of which are connected or can be connected to one chamber (36, 38) of the steering actuator (26)
Implementation Method 2
The connections of the hydraulic pumps (54, 72) are each connected to the chambers (36, 38) of the steering actuator (26) by means of preferably spring-loaded check valves (58, 64, 78, 82) assigned to them
Data Source
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AI summary
The invention relates to an electrohydraulic steer-by-wire steering system comprising an operator interface (20) for specifying a steering angle, with which operator interface a sensor (22) for detecting a position and/or motion of the operator interface (20) is associated, an electronic control device (44), which is connected to a first electrohydraulic circuit (46) and a second electrohydraulic circuit (48) and is designed to control the two electrohydraulic circuits (46, 48) in dependence on the signals of the sensors (22), and a steering actuator (26) for adjusting the steering angle of a steerable wheel (14), which steering actuator has two chambers (38, 36), which are both simultaneously connected to both electrohydraulic circuits (46, 48) in normal operation of the steering system.