Motorcycle Wheel Support Structure with Magnetic Encoder
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Solution Overview
Problem
Existing wheel support structures for two-wheeled motor vehicles face challenges in precise rotational speed detection due to compact size and outer ring rotating type configurations, leading to issues like reduced magnetic flux density, assembly complexity, and reliability concerns such as creep between the outer ring and hub.
Innovation Solution
A wheel support structure with a rolling bearing and magnetic encoder where the magnetic encoder is mounted on an inner circumferential surface of a cylindrical section extending from the outer ring, increasing the axial length and surface area per magnetic pole, and using a rotation restraining member to prevent creep, simplifying processing and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic encoder is mounted on a conventional ball bearing for rotational speed detection, then rotational speed detection is enabled, but the compact size of two-wheeled motor vehicle ball bearings reduces magnetic flux density and detection precision
Solution Approach 1:
The magnetic encoder is mounted on the outer ring of the ball bearing, utilizing the circumferential dimension of the outer ring surface. This allows the encoder to be positioned in a space that does not increase the overall volume of the ball bearing assembly, while still providing sufficient surface area for magnetic flux generation and detection.
Solution Approach 2:
The magnetic encoder is integrated into the ball bearing structure by mounting it on the outer ring, effectively nesting the encoder within the existing ball bearing footprint. This nesting approach allows the encoder to share the same spatial envelope as the ball bearing, avoiding volume increase while enabling rotational speed detection.
2Reliability
If a magnetic encoder is mounted on the outer ring of a rotating outer ring type ball bearing, then rotational speed detection is achieved, but creep between the outer ring and hub reduces reliability
Solution Approach 1:
A rotation restraining member is introduced as an intermediary element between the outer ring and the hub. This member acts as a mediator that prevents relative rotation (creep) between the outer ring and hub while allowing the ball bearing to function normally, thereby eliminating the harmful creep effect without compromising the rotational speed detection functionality.
Solution Approach 2:
The rotation restraining member is installed in advance to prevent creep from occurring. By providing preliminary restraint against relative rotation, the system proactively eliminates the creep problem before it can affect the reliability of rotational speed detection, rather than attempting to correct it after the fact.
3Measurement precision
If a magnetic encoder with increased axial length is used to improve magnetic flux density, then detection precision improves, but assembly complexity increases
Solution Approach 1:
The outer ring of the ball bearing serves multiple functions: it supports the ball bearing operation and simultaneously serves as the mounting surface for the magnetic encoder. This multi-functionality allows the encoder to be mounted without requiring additional components or complex assembly procedures, as the outer ring already provides the necessary structural support and positioning.
Solution Approach 2:
The functions of the ball bearing outer ring and the encoder mounting surface are merged into a single component. By combining these functions, the design eliminates the need for separate mounting structures or additional assembly steps, thereby maintaining simplicity while providing sufficient surface area for the encoder.
4Reliability
If a rotation restraining member is added to prevent creep, then reliability improves, but device complexity increases
Solution Approach 1:
The rotation restraining member is designed as a simple, inexpensive component that can be easily manufactured and installed. Although it adds a component to the system, its simplicity and low cost mean that the overall complexity and cost increase is minimal, while the reliability improvement from preventing creep is significant.
Solution Approach 2:
The rotation restraining member is designed to automatically perform its function of preventing creep without requiring external control or adjustment mechanisms. It self-regulates the relative rotation between the outer ring and hub, eliminating the need for complex control systems or additional adjustment components.
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
Improves the precision of rotational speed detection without sacrificing ease of assembly, enhances reliability by preventing creep, and reduces manufacturing costs through simplified processing and reduced resistance to rotation.
Implementation Method 1
a magnetic encoder (34) which is mounted on the outer ring (22) of the rolling bearing (21a)
Implementation Method 2
a magnetic sensor (17) which detects the rotational speed of the wheel (7) by way of the magnetic encoder (34)
Data Source
AI summary
In a wheel support structure for a motorcycle, a magnetic encoder 34 for detecting rotational speed is mounted and fastened to the inner circumferential surface of a cylindrical section 36a, which extends outward in the axial direction from the outer ring 22, of an encoder installation plate 35a that is attached to the end section in the axial direction of the outer ring 22 of the one of the rolling bearings 21a on the side toward the other rolling bearing 4, or is mounted and attached to the side surface toward the side of the other rolling bearing 4 of a slinger 73, which is attached to the end section in the axial direction of the outer ring 22b of the one of the rolling bearings 21a on the side toward the other rolling bearing 4 such that the end surface on the inner diameter side closely faces the outer surface of the inner ring 24 to form labyrinth space 42. Preferably, a rotation restraining member 86 is fastened to the outer circumferential surface of the outer ring 82a, which is the rotating ring, and there is engagement between this rotation restraining member 86 and the inner circumferential surface of the hub 6, which is the rotating member.