Power Steering Pump Slope Control
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Solution Overview
Problem
Power steering systems face issues with jerky feelings due to insufficient steering force in slope descent and lack of response due to excessive steering force in slope ascent, particularly in vehicles like cab-over trucks with short wheelbases and high centers of gravity, where front axle load changes significantly.
Innovation Solution
A power steering system with an electric pump that adjusts its hydraulic oil supply based on slope angles or vehicle body angles by calculating an on-slope standby rotation speed, increasing or decreasing the flow rate accordingly to maintain optimal assist force during slope operations, thereby correcting the steering force imbalance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the standby rotation speed is increased to provide sufficient steering force in slope descent, then steering force in slope descent is improved, but electric energy consumption increases and steering force becomes excessive in slope ascent
Solution Approach 1:
The patent applies dynamics by making the standby rotation speed adjustable based on operating conditions. The control device dynamically changes the standby rotation speed from a basic value to an increased value when slope descent is detected through sensor input, allowing the system to adapt to varying load conditions rather than operating at a fixed speed
Solution Approach 2:
The patent changes the rotational speed parameter of the electric pump based on detected slope conditions. When the vehicle is descending a slope, the control device increases the standby rotation speed parameter from the basic value to a higher value, thereby adjusting the hydraulic pressure and steering force to match the increased front axle load
2Force
If the standby rotation speed is reduced to decrease excessive steering force in slope ascent, then steering force in slope ascent is improved, but steering force becomes insufficient in slope descent
Solution Approach 1:
The system dynamically adjusts the standby rotation speed based on real-time detection of slope direction and magnitude. When slope descent is detected, the rotation speed is increased to provide sufficient steering force; when slope ascent is detected, the basic rotation speed is maintained to avoid excessive steering force
Solution Approach 2:
The patent employs feedback control by using sensors to detect the vehicle's slope condition and feeding this information back to the control device. The control device then adjusts the electric pump's standby rotation speed accordingly, creating a closed-loop system that responds to actual operating conditions
3Use of energy by moving object
If the supply amount of fluid is set to zero to reduce energy consumption, then electric pump energy consumption is reduced, but seizure phenomenon occurs in power steering unit and response delay occurs in abrupt steering
Solution Approach 1:
The patent applies partial action by maintaining a basic standby rotation speed that provides minimal but sufficient hydraulic pressure to prevent seizure and ensure readiness. Rather than completely stopping the pump (zero supply), the system maintains a low-level operation that prevents harmful effects while still reducing energy consumption compared to full operation
Solution Approach 2:
The system performs preliminary action by maintaining a basic standby rotation speed that prepares the power steering unit for potential abrupt steering operations. This preliminary maintenance of hydraulic pressure prevents the need for delayed response when steering input is required
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 solution effectively suppresses jerky feelings in slope descent and lack of response in slope ascent, improving fuel efficiency by reducing pump drive loss and enhancing steering responsiveness without increasing electric power consumption.
Implementation Method 1
an electric pump configured to supply hydraulic oil to a steering assisting device configured to assist a steering performance of a steering wheel
Data Source
AI summary
Provided is a power steering system including: an electric pump 11 configured to supply fluid to a power steering unit 13 configured to assist a steering performance of a steering wheel 4a; and an ECU 5 configured to control a supply amount of the fluid by means of a rotation speed of the electric pump 11. The ECU5 includes first means for calculating an on-slope standby rotation speed N0' and controlling the electric pump 11 such that the electric pump 11 is set to the on-slope standby rotation speed NO', when a vehicle 1 is descending or ascending a slope, the on-slope standby rotation speed N0' calculated by correcting a standby rotation speed N0 of the electric pump 11 corresponding to a vehicle speed Vn with a slope correction value Nx calculated according to a slope angle θ or a vehicle body angle θn. Accordingly, it is possible to supply the fluid with the electric pump 11 and assist a steering operation to suppress both of jerky feeling in the steering operation due to insufficient steering force in slope descent and lack of response in the steering operation due to excessive steering force in slope ascent.