Electric Power Steering Reverse Connection Detection
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Solution Overview
Problem
The existing electric power steering apparatuses face safety issues due to intermediate breakdown states caused by reverse battery connections, leading to potential undesirable driver behaviors during travel, as the fuse blows and normal operation cannot be guaranteed even after resolving the reverse connection.
Innovation Solution
An electric power steering apparatus with a reverse connection storage unit that detects and stores the occurrence of reverse connections, preventing power assist during subsequent travel by restricting or prohibiting the drive of the electric motor, using a diode, fuse, and pull-up resistor to prevent reverse current and detect overcurrent states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a conventional structure with a housing, piston, and separate return line is used, then the steering device is simple to manufacture, but the device occupies a large installation space and has complex routing requirements
Solution Approach 1:
The patent combines the return line function directly into the piston structure by forming a return line communication hole through the piston body, eliminating the need for separate return line routing and reducing installation space requirements while maintaining manufacturing feasibility
Solution Approach 2:
The communication hole is formed by nesting multiple processing steps within the piston manufacturing process, including drilling, expanding, and forming operations that create the return line pathway directly within the piston structure
2Ease of manufacture
If the communication hole is formed by drilling and expanding with a tapered expanding tool, then manufacturing is simplified, but the hole diameter varies along the length causing fluid flow issues
Solution Approach 1:
A pilot hole is drilled first as a preliminary action to establish the correct position and diameter, followed by expanding operations that maintain uniform diameter throughout the hole length, preventing fluid flow issues caused by diameter variation
Solution Approach 2:
The patent changes the processing parameters during hole formation, using a drill bit for initial hole creation with controlled depth and diameter, then transitioning to an expanding tool with specific geometry to achieve the final uniform diameter without creating tapered sections
3Loss of energy
If the communication hole diameter is increased to improve fluid flow, then flow resistance decreases, but the piston structure becomes weaker and sealing becomes more difficult
Solution Approach 1:
The patent uses a flexible sealing ring that can deform to seal effectively in the enlarged communication hole, maintaining piston strength while allowing sufficient fluid flow through the larger diameter opening
Solution Approach 2:
The piston is constructed as a composite structure combining the piston body material with a sealing ring material, where the sealing ring provides both sealing function and structural reinforcement around the communication hole, enabling larger hole diameter without compromising piston strength
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 significantly reduces the probability of assist abnormalities and enhances safety by detecting and storing reverse connection occurrences, preventing secondary breakdowns and ensuring safe operation by restricting or prohibiting power assist.
Implementation Method 1
a diode, fuse and pull-up resistor attached to the battery in parallel with the inverter to prevent reverse connection
Implementation Method 2
a fuse arranged in the vehicle is blown when the battery and the controller (ECU) are reverse connected
Implementation Method 3
the fuse is blown when the battery and the controller (ECU) are reverse connected, thus preventing smoking and ignition of the controller (ECU)
Implementation Method 4
an excitation current flowing through the electromagnetic coil makes the coil an electromagnet thus attracting an iron piece of the switch
Data Source
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AI summary
There is provided an electric power steering apparatus that detects and stores occurrence of a reverse connection when the reverse connection has occurred, and restricts a power assist at the next startup of a controller. Specifically, in an ECU (14) for controlling an electric motor (13) that applies a steering assist torque on a steering mechanism, a microcomputer (14a) transmits a drive signal to a driver (14b) that drives an inverter (14c), which controls current of the electric motor, in accordance with the drive signal. A reverse connection storage circuit (14d) is attached in parallel with the inverter (14c), and detects and stores the occurrence of the reverse connection when the reverse connection of the ECU (14) and a battery (15) has occurred, and notifies the microcomputer (14a) of the occurrence of the reverse connection at the next startup of the ECU (14). The microcomputer (14a) transmits a signal indicating non-permission to the driver (14b) in accordance with the notification. The driver (14b) restricts the power assist upon receiving the signal.