Hydrostatic Steering Torque Control for Agricultural Vehicles
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Solution Overview
Problem
Hydrostatic steering devices for agricultural utility vehicles suffer from hydraulic losses due to system-induced leaks, leading to reduced steering cylinder extension and wheel steering angle, as well as drifting of the steering wheel position, which affects directional stability.
Innovation Solution
A method for operating a hydrostatic steering device that includes an electric drive unit actuated by a control unit to generate an actuating torque on the steering column, supporting driver-side steering actuation and improving self-centering of the steering wheel, especially in emergency operating modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a hydrostatic steering device with a steering orbitrol and hydraulic pump is used, then comfortable steering of heavy utility vehicles is achieved, but hydraulic losses occur due to system-induced leaks leading to reduced steering cylinder extension and wheel steering angle
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the steering wheel position and wheel steering angle, detecting deviations caused by hydraulic leaks. The system then generates compensating actuating torque through the electric drive unit to counteract the drift, maintaining accurate steering control despite ongoing hydraulic losses.
Solution Approach 2:
The patent introduces an electric drive unit as an intermediary between the driver's steering input and the steering cylinder. This electric intermediary compensates for hydraulic losses by generating additional torque to maintain the intended steering angle, effectively mediating between the degraded hydraulic system and the desired steering performance.
2Ease of operation
If a hydrostatic steering device is used, then steering of heavy utility vehicles is achieved, but the steering wheel position drifts in relation to the wheel steering angle over time, affecting directional stability
Solution Approach 1:
The control unit continuously monitors both the steering wheel position and the actual wheel steering angle, detecting deviations caused by hydraulic leaks. The system generates compensating actuating torque to counteract the drift, maintaining accurate alignment between steering wheel position and wheel steering angle throughout operation.
3Reliability
If the hydraulic pump fails or operates faultfully, then the hydrostatic steering device cannot be operated normally, but the steering orbitrol can take over by generating hydraulic volume flow
Solution Approach 1:
The electric drive unit serves as an intermediary that can operate independently of the hydraulic pump. When the hydraulic pump fails, the electric drive unit takes over completely, using its electric motor to drive the steering orbitrol and generate the necessary hydraulic volume flow, ensuring continuous steering operation.
Solution Approach 2:
The system changes its operating parameters dynamically: during normal operation, the hydraulic pump provides the primary power source; upon failure detection, the system switches to electric drive mode, fundamentally changing the energy source and operational characteristics to maintain steering functionality.
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 method enhances the operating behavior of the hydrostatic steering device by reducing hydraulic losses, maintaining accurate steering wheel position alignment with the wheel steering angle, and ensuring reasonable effort is required to operate the steering device even in emergency conditions.
Implementation Method 1
an electric drive unit which can be actuated by a control unit for generating an actuating torque acting on the steering column
Implementation Method 2
a hydraulic pump with pressurized hydraulic fluid
Implementation Method 3
the pressure gradient present between the first and second orbitrol connections leads to the occurrence of hydraulic losses
Data Source
AI summary
A method for operating a hydrostatic steering device for an agricultural utility vehicle, includes controlling a steering orbitrol of the hydrostatic steering device by a steering wheel via a steering column, deflecting a steering cylinder in accordance with a driver-side steering actuation of the steering wheel, detecting a steering actuation variable via a first sensor, detecting a steering position variable via a second sensor, in a normal operating mode, the control unit is configured to actuate the electric drive unit such that an actuating torque which increases continuously with the wheel steering angle is generated at the steering column and thus at the steering wheel, and in an emergency operating mode, the control unit is configured to control the electric drive unit such that an actuating torque is generated on the steering column and thus on the steering orbitrol to support driver-side steering actuation.