Steering Gear Layout With Separated Lubrication and Low Backlash
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Solution Overview
Problem
Conventional electric power steering systems face challenges in weight reduction due to the use of oil lubrication in the oil chamber, which increases the amount of oil and causes friction, hindering operational efficiency.
Innovation Solution
The steering device incorporates a first gear mechanism lubricated with grease and a second gear mechanism with a separation space from the oil chamber, reducing the overall oil amount and using a belt-type transmission mechanism to minimize backlash and friction, while eliminating the need for oil in the transmission mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the speed reducer is lubricated with oil stored in the case, then the lubrication effect is improved, but the amount of oil increases which hinders weight reduction
Solution Approach 1:
The patent divides the housing into two separate spaces: an oil chamber for the speed reducer and a separation space for the first gear mechanism. This segmentation allows oil to be confined only where needed (in the speed reducer), eliminating the need to store large amounts of oil in the entire housing and thereby reducing overall weight while maintaining adequate lubrication.
Solution Approach 2:
The patent extracts the first gear mechanism from the oil chamber environment by creating a separate space for it. This extraction allows the first gear mechanism to be lubricated with grease instead of oil, further reducing the total oil quantity required and contributing to weight reduction.
2Reliability
If a large amount of oil is stored in the oil chamber, then the lubrication coverage is improved, but the friction caused by oil agitation increases which hinders operability
Solution Approach 1:
By segmenting the housing into an oil chamber and a separation space, the patent minimizes the volume of oil required for lubrication. This reduces oil agitation and associated friction, thereby improving operability while still providing adequate lubrication coverage within the confined oil chamber space.
Solution Approach 2:
The patent applies different lubrication methods to different parts: oil is used specifically in the speed reducer where high-speed rotation generates heat, while grease is used in the first gear mechanism. This localized approach optimizes lubrication effectiveness while minimizing oil agitation friction.
3Power
If the transmission mechanism is of gear type, then the power transmission is efficient, but the backlash effect increases which hinders operational accuracy
Solution Approach 1:
The patent replaces the gear-type transmission mechanism with a belt-type transmission mechanism. This substitution eliminates the backlash effect inherent in gear meshing, thereby improving operational accuracy, while the belt transmission maintains sufficient power transmission efficiency for the steering application.
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 configuration achieves weight reduction and improved operational accuracy by minimizing oil usage and friction, enhancing the reliability and efficiency of the steering system.
Implementation Method 1
the gear case forms an oil chamber that houses the reduction mechanism parts. The case forms a separation space separated from the oil chamber by a seal member
Implementation Method 2
a belt-type transmission mechanism that couples the drive device to the second gear mechanism
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A steering device (10) according to one aspect of the invention includes: a first gear mechanism (11) configured to receive rotation of steering wheel operation, convert a direction of the rotation, and output converted rotation as primary rotation; and a second gear mechanism (20) configured to receive the primary rotation output from the first gear mechanism (11), decelerate the primary rotation, and output decelerated rotation. The first gear mechanism (11) includes: conversion mechanism parts (11d) configured to convert the direction of the rotation; and a case (12) that houses the conversion mechanism parts (11d). The second gear mechanism (20) includes: reduction mechanism parts (20d) configured to decelerate the primary rotation; and a gear case (21) that houses the reduction mechanism parts (20d). The gear case (21) forms an oil chamber (R1) that houses the reduction mechanism parts (20d). The case (12) forms a separation space (K2) separated from the oil chamber (R1) by a seal member (16c).