Electric Power Steering Mounting for Straddle Vehicle Durability
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Solution Overview
Problem
Conventional straddle type vehicles with electric power steering apparatuses face issues such as reduced durability due to exposure to muddy water and dust, heat from the engine, poor assembling workability, and difficult maintenance, especially when the electric motor is positioned in the lower portion of the vehicle body.
Innovation Solution
The electric power steering apparatus is mounted in an intermediate portion of the steering shaft, with an electric motor, gear unit, input shaft, and output shaft, and is supported by a tubular upper steering shaft and a case body, which is integrated with a bracket, allowing for improved maintenance and assembling workability while being protected from external forces and environmental factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the electric motor is arranged in the lower portion of the vehicle body, then the power steering apparatus can be compactly arranged, but the durability is reduced due to exposure to muddy water, dust, and engine heat
Solution Approach 1:
The patent repositions the electric motor from the lower portion to the upper portion of the vehicle body, changing the spatial dimension of arrangement. This dimensional shift moves the motor away from harmful environmental factors (muddy water, dust, engine heat) while maintaining compact integration through the support member structure that connects to the vehicle frame
Solution Approach 2:
The electric motor is extracted from the lower portion arrangement and relocated to the upper portion, separating it from the harmful environment. The support member structure provides the extraction mechanism, allowing the motor to be independently positioned in a cleaner, cooler area while maintaining functional connection to the steering shaft
2Reliability
If the electric motor is arranged to cross the upper side of the front suspension support portion, then the durability is improved by avoiding muddy water and dust, but the freedom of suspension actuation is limited and assembling workability is poor
Solution Approach 1:
The support member is designed with differentiated local qualities: the first support portion provides structural support for the motor, the second support portion allows suspension movement freedom, and the connecting portion bridges these functions. This local differentiation enables the motor to be protected from mud and dust while maintaining full suspension actuation freedom in the critical area
3Volume of moving object
If the electric motor is arranged in the lower portion, then the arrangement is compact, but the maintenance ability is difficult
Solution Approach 1:
The power steering apparatus is segmented into distinct functional modules: the electric motor, the support member, and the connection to the steering shaft. This segmentation allows the motor to be independently accessed and maintained. The support member acts as a modular interface that can be detached, enabling easy maintenance without disassembling the entire steering system
Data Source
AI summary
A straddle type vehicle is provided with a body frame of a vehicle, a bar handle provided in a front portion of the vehicle body frame, a steering shaft transmitting a turning operation of the bar handle to a pair of right and left front wheels, and an electric power steering apparatus mounted in an intermediate portion of the steering shaft for assisting a steering motion of the bar handle. The electric power steering apparatus includes, in a state of the vehicle capable of being traveled, an electric power steering main body including an electric motor, a gear unit, an input shaft and an output shaft, an upper steering shaft in which the bar handle is attached to an upper end portion and an upper end of the input shaft is connected to a lower end portion, and a support member supporting the upper steering shaft.