Electric Power Steering Torque Adjustment via Weight Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Off-road vehicles, particularly agricultural tractors, face challenges in maintaining consistent steering torque due to variations in weight distribution, which existing power steering systems fail to adequately compensate for, leading to unpredictable steering feel and control.
Innovation Solution
An electric assisted power steering system that uses a rotary electric motor connected to the steering column, controlled by an electronic control unit (ECU) and sensors, to adjust steering torque based on real-time weight distribution data from various sources, including fluid pressure sensors and ISOBUS network information, ensuring the steering feel remains consistent and appropriate for the current operating conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-reactive hydraulic steering unit (HSU) is used to provide steering assistance, then the steering assistance is generally constant in operation, but the steering torque becomes inconsistent when vehicle weight distribution varies
Solution Approach 1:
The patent applies dynamics by transitioning from a static, constant steering assistance system to a dynamic system that continuously adjusts steering torque based on real-time weight distribution measurements. The electric motor controller modifies the steering assistive torque dynamically in response to changing vehicle conditions, enabling the system to adapt to varying weight distributions while maintaining consistent steering characteristics.
Solution Approach 2:
The patent changes the parameter of steering assistive torque based on weight distribution measurements. The controller adjusts the torque parameter in response to sensor feedback about vehicle weight distribution, allowing the steering system to compensate for changes in loading conditions and maintain consistent steering effort across different operating scenarios.
2Force
If additional weight and inertia are attached to the front of the tractor, then the steering feels stiffer and requires more steering torque, but the existing steering system cannot compensate for this
Solution Approach 1:
The patent applies the counterweight principle by using the electric motor to generate compensating torque that offsets the increased steering effort required when front weight is added. The controller measures the actual steering torque required and applies an opposing torque through the electric motor, effectively counterbalancing the additional weight and restoring comfortable steering effort despite changed vehicle loading conditions.
Solution Approach 2:
The patent implements feedback control by continuously monitoring steering torque requirements and weight distribution, then adjusting the electric motor output accordingly. The controller receives feedback from torque sensors and weight distribution measurements, comparing actual conditions against desired operating parameters, and modifies motor torque to maintain consistent steering characteristics under varying load conditions.
3Force
If weight is transferred from the front to the rear axle through towing or rear attachments, then the steering feels softer and requires less steering torque, but the steering system cannot automatically adjust
Solution Approach 1:
The patent applies dynamics by enabling the steering system to adapt in real-time to changing weight distribution conditions. When weight is transferred to the rear axle through towing or rear attachments, the weight distribution sensors detect this change and trigger dynamic adjustments to the electric motor torque output, allowing the steering characteristics to automatically adapt to the new loading condition and maintain consistent steering effort.
Solution Approach 2:
The patent uses feedback control to automatically adjust steering torque based on measured weight distribution. The controller continuously monitors weight distribution sensors and adjusts the electric motor output in response to detected changes, creating a closed-loop system that automatically compensates for weight transfer conditions without requiring manual intervention or pre-programmed responses.
4Device complexity
If the steering system does not compensate for weight distribution variations, then the structure remains simple, but the steering feel becomes unpredictable and control is compromised
Solution Approach 1:
The patent merges the electric motor steering assistance system with the existing hydraulic steering unit, combining their torque outputs to provide overall steering assistance. This integrated approach allows the system to leverage both the hydraulic system's raw power and the electric motor's controllable, adjustable torque, creating a unified steering system that maintains consistent characteristics across varying weight distribution conditions while managing complexity through functional integration.
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 effectively adjusts steering torque to match the vehicle's weight distribution, providing a consistent and appropriate steering feel, alerting operators to overload conditions and ensuring proper ballasting, thereby enhancing control and safety.
Implementation Method 1
a rotary electric motor connected to or integrated with the steering column to add to or subtract from the steering torque
Implementation Method 2
a hydraulic pump, which provides power needed to assist an operator in turning the very large and heavy front wheels
Implementation Method 3
a servovalve within the HSU, which may be a double acting, bidirectional proportional valve having a rotary input
Implementation Method 4
hydraulic flow and pressure then proceeds from the double acting, bidirectional proportional valve to the double acting hydraulic cylinder, in order to steer the agricultural tractor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A power steering system (52) for an off-road vehicle (10) includes an electric assisted power steering (EPS) unit (102) controlled by an electronic control unit (ECU) (108) for adding and subtracting torque to a rotatable steering column (54). At least one sensor (36a, 38a, 152a, 162a, 170) is configured to sense at least one of pressure, proximity, strain, and displacement in at least one component or attachment of the vehicle (10). The EPS unit (102) ECU (108) may be connected to the sensor (36a, 38a, 152a, 162a, 170) by way of an ISOBUS or CANbus network (40), and is configured to use information from the sensor (36a, 38a, 152a, 162a, 170) to determine a weight distribution of the vehicle (10). The ECU (108) controls the EPS unit (102) to adjust the torque of the rotatable steering column (54) as a function of the weight distribution of the vehicle (10).