Electric Power Steering Intermediate Plate Assembly
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Solution Overview
Problem
Existing electric power steering apparatuses face challenges in efficient assembly and long-term performance maintenance, with complex manufacturing processes and potential degradation of torque measuring device precision due to elastic material deterioration.
Innovation Solution
An electric power steering apparatus design featuring an intermediate plate with a rearwardly facing step surface and circumferential projections, press-fitted into the gear housing for stable positioning, and supported by rolling bearings to maintain the output shaft's posture and prevent decelerator engagement degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the output shaft is supported by rolling bearings held on the inner peripheral surface of the gear housing, then the assembly process becomes complex and time-consuming, but the structural stability and long-term performance are improved
Solution Approach 1:
An intermediate plate is introduced as a mediator component between the gear housing and the rolling bearings. The intermediate plate has a cylindrical outer peripheral surface that is press-fit into the gear housing, while the rolling bearings are held on the inner peripheral surface of this intermediate plate. This intermediary structure simplifies the assembly process by providing a dedicated mounting platform for the bearings, eliminating the need for complex direct installation into the gear housing, while still ensuring stable positioning and long-term performance.
2Ease of manufacture
If elastic material is used for positioning the output shaft, then the initial positioning is achieved, but the torque measuring device precision degrades over time due to material deterioration
Solution Approach 1:
The intermediate plate is designed as a rigid positioning structure that replaces elastic materials. Although the intermediate plate requires press-fit installation, it provides stable, non-deteriorating positioning over time. The rigid structure maintains constant geometric relationships between the output shaft and housing, ensuring long-term precision of the torque measuring device without the degradation issues associated with elastic material aging.
3Device complexity
If the output shaft posture is not properly maintained, then the assembly is simpler, but the decelerator engagement state degrades
Solution Approach 1:
The intermediate plate serves as a precision intermediary structure that maintains the correct posture of the output shaft. The plate's rigid structure and precise geometric features ensure that the output shaft remains properly positioned and oriented, which is critical for maintaining the engagement state of the decelerator. This intermediary structure provides the necessary stability without requiring overly complex support mechanisms.
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
Facilitates easy assembly and long-term performance maintenance by ensuring the rolling bearings' correct posture, thus maintaining the engaged state of the decelerator and torque measuring device precision.
Implementation Method 1
an output shaft (13), which transmits the rotation of the input shaft (12) to the intermediate shaft (16); a first rolling bearing (22), which supports the output shaft (13) to the gear housing (20); and a second rolling bearing (23), which supports the output shaft (13) to the gear housing (20)
Implementation Method 2
An intermediate plate (28), on which the first rolling bearing (22) and the second rolling bearing (23) are held, is fixed in the gear housing (20)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An electric power steering apparatus has a first rolling bearing and a second rolling bearing rotatably supporting an output shaft. The first rolling bearing is provided between an inner peripheral surface of a through-hole of a gear housing and an outer peripheral surface of the output shaft. The second rolling bearing is provided between an inner peripheral surface of an intermediate plate and the outer peripheral surface of the output shaft. The intermediate plate has an outer peripheral portion supported and fixed in an opening portion of the gear housing.