Motor Shaft Contact Layout for Low-Resistance Resolver Assemblies
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Solution Overview
Problem
Conventional motors with brushes connected to rotor shafts experience high electric resistance and potential differences due to small contact areas, leading to inefficient current flow and potential corrosion issues.
Innovation Solution
A motor assembly design featuring a conductive contact fixed to the housing, in contact with a conductive portion of the rotor shaft, alongside a resolver, to enhance conductivity and reduce potential differences, while maintaining efficient rotation and cooling with lubricating oil circulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a brush is used to electrically connect the rotor shaft to the housing, then electrical connection is achieved, but the contact area is small causing high electric resistance
Solution Approach 1:
The invention transitions from a point-contact brush connection to a surface-contact connection by utilizing the end face of the rotor shaft. The conductive member contacts the shaft along a circumferential direction, creating a two-dimensional contact area that significantly reduces electrical resistance compared to traditional brush point contact.
Solution Approach 2:
A conductive member (such as a conductive ring or plate) is introduced as an intermediary between the rotor shaft and the housing. This conductive member provides a stable electrical connection path, replacing the traditional brush and eliminating the high resistance issue while maintaining reliable electrical connectivity.
2Reliability
If a brush is used for electrical connection, then connection is established, but potential difference and electric corrosion occur due to high resistance
Solution Approach 1:
The conductive member serves as an intermediary that provides a low-resistance electrical path between the rotor shaft and housing. By eliminating high resistance, it prevents potential difference buildup and the subsequent electric corrosion that would damage the brush and surrounding components.
Solution Approach 2:
The invention changes the electrical resistance parameter by transitioning from high-resistance brush contact to low-resistance surface contact. This parameter change eliminates the conditions that lead to potential difference and electric corrosion, ensuring long-term connection stability.
3Reliability
If brushless design is implemented with conductive contact, then current flow is improved, but space arrangement must be optimized
Solution Approach 1:
The end face of the rotor shaft serves multiple functions: it provides mechanical support for the rotor assembly and simultaneously serves as an electrical contact surface. This multi-functionality eliminates the need for separate brush components and simplifies the spatial arrangement while improving current flow efficiency.
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
The design improves current flow and reduces electric corrosion, ensuring stable motor operation and prolonged lifespan by maintaining conductive contact and effective cooling within the motor assembly.
Implementation Method 1
a contact that has conductivity, is fixed to the housing, and is in contact with a contacted portion at an end portion on one axial side of the shaft
Implementation Method 2
a bearing that is fixed to the housing and rotatably supports the shaft
Data Source
AI summary
A motor assembly includes a motor including a rotor including a shaft rotatable about a rotation axis and a stator surrounding the rotor from radially outside, a housing that accommodates the motor, a bearing that is fixed to the housing and rotatably supports the shaft, a resolver including a resolver rotor fixed to the shaft and a resolver stator fixed to the housing, and a contact that has conductivity, is fixed to the housing, and is in contact with a contacted portion at an end portion on one axial side of the shaft. The housing includes an accommodation space in which the contacted portion of the shaft is accommodated. The contact and the resolver are side by side in a direction along a rotation axis in the accommodation space.