Power Steering Gain Reduction for Smooth Force
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power steering apparatuses experience a shortage in hydraulic fluid flow during rapid steering at high speeds, leading to obstruction feelings and rapid changes in steering force, which affect the smoothness of steering.
Innovation Solution
A power steering apparatus that includes an oil pump, an electric motor, vehicle speed and steering speed detectors, and a feedback control system with gain reduction mechanisms to adjust the motor's rotational speed based on detected deviations and steering speed changes, ensuring smooth steering assistance without obstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the slope of rotational speed/steering speed is increased to obtain high rotational speed even with low steering speed, then the hydraulic fluid flow rate shortage is solved, but the steering assistance force changes rapidly and the smoothness of steering force deteriorates
Solution Approach 1:
The patent applies dynamics by making the feedback control gain variable rather than fixed. The gain is dynamically adjusted based on the rate of change of steering speed and the current steering speed magnitude. When steering speed changes rapidly, the gain is reduced to prevent excessive rotational speed changes, while when steering speed is stable, the gain is increased to ensure sufficient hydraulic fluid flow. This dynamic adjustment resolves the contradiction between maintaining high flow rate and ensuring smooth steering force.
Solution Approach 2:
The patent changes the parameter of feedback control gain based on operating conditions. Specifically, the gain is modified according to the rate of change of steering speed (|Δω/Δt|) and the absolute value of steering speed (|ω|). By changing this control parameter adaptively, the system can provide high rotational speed when needed while preventing rapid changes in steering assistance force, thus resolving the contradiction between hydraulic fluid flow rate and steering force smoothness.
2Speed
If feedback control with high gain is used to respond quickly to steering demands, then steering responsiveness is improved, but the steering force changes rapidly causing obstruction feeling during rapid steering
Solution Approach 1:
The patent makes the feedback control gain dynamic rather than static. The gain is adjusted in real-time based on the rate of change of steering speed and the magnitude of steering speed. During rapid steering maneuvers, the gain is automatically reduced to prevent excessive and abrupt changes in electric motor rotational speed, thereby eliminating obstruction feelings. During normal steering, the gain remains high to ensure responsive steering assistance, thus resolving the contradiction between responsiveness and smoothness.
Solution Approach 2:
The patent employs feedback control where the actual electric motor rotational speed is continuously monitored and compared with the target rotational speed. The feedback gain is adjusted based on the deviation and the rate of change of steering speed. This feedback mechanism ensures that the system responds appropriately to steering demands while preventing excessive corrections that would cause obstruction feelings, thereby resolving the contradiction between steering responsiveness and smoothness.
Data Source
AI summary
A power steering apparatus according to the present invention is constructed to calculate a rate of change of steering speed detected by steering speed detecting means and judge whether the calculated rate of change is smaller than or equal to 0 or not, and reduce a gain of feedback control in comparison with a gain at the time of judgment when it is judged that the rate of change remains smaller than or equal to 0 for a predetermined time period and keep the reduced gain of feedback control until the deviation between target rotational speed and actual rotational speed of an electric motor becomes larger than 0.