Automotive Starter Brush Commutator Vibration Control
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Solution Overview
Problem
Existing automotive engine starters face issues with axial vibrations of the armature shaft, leading to wear, seizing, and increased manufacturing costs due to the need for specialized bearings and flanges to manage thrust loads, which also affect the starter's weight and torque output.
Innovation Solution
The use of an oil-impregnated bearing and protrusions on the commutator surface to minimize axial vibrations of the armature shaft, eliminating the need for a flange and reducing thrust loads, thereby decreasing production costs and maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flange is added to increase the bearing contact area, then wear and seizing are avoided, but manufacturing cost increases and the structure becomes more complex
Solution Approach 1:
The invention changes the material parameter of the bearing from a standard bearing to an oil-impregnated bearing. This material change allows the bearing itself to provide lubrication and reduce friction, eliminating the need for a flange structure while maintaining wear resistance and reliability.
Solution Approach 2:
The invention removes the flange component from the structure by using an oil-impregnated bearing that inherently handles thrust loads through its lubricated surface. This extraction of the flange simplifies the structure and reduces manufacturing cost while maintaining the necessary wear protection.
2Reliability
If the bearing size is increased to reduce pressure on the shoulder, then wear is avoided, but the overall size and weight of the armature increase
Solution Approach 1:
The invention changes the material parameter to an oil-impregnated bearing, which provides self-lubrication and reduces friction. This allows the bearing to handle thrust loads effectively without requiring an increased size, thereby maintaining armature weight while ensuring wear resistance.
3Weight of moving object
If the end diameter of the armature shaft is decreased to reduce weight, then the overall weight decreases, but mechanical strength is compromised
Solution Approach 1:
The invention changes the bearing material parameter to an oil-impregnated bearing, which compensates for the reduced shaft diameter by providing superior lubrication and thrust load handling. This allows the shaft to be lighter while maintaining overall structural strength and reliability through the enhanced bearing performance.
4Reliability
If an oil-impregnated bearing is used to reduce thrust load, then wear is avoided and structure is simplified, but manufacturing precision requirements increase
Solution Approach 1:
The oil-impregnated bearing is designed to self-lubricate through oil reservoirs within its structure. This self-service capability reduces the need for external lubrication systems and complex machining features, thereby maintaining manufacturing precision while ensuring reliable wear protection.
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 solution effectively reduces axial vibrations, decreases manufacturing costs, and maintains the mechanical strength of the starter, ensuring stable electrical contacts and efficient torque transmission without the need for additional components like washers or increased bearing sizes.
Implementation Method 1
an oil-impregnated bearing which retains an end of the armature shaft to be rotatable
Implementation Method 2
an oil-impregnated bearing which retains an end of the armature shaft to be rotatable; protrusions extending on the commutator surface substantially in parallel to each other in a direction of rotation of the commutator surface; urging mechanisms each of which works to urge a surface of one of the brushes into constant engagement with the protrusions to establish the electrical contacts between the brushes and the commutator surface and minimize movement of the armature shaft relative to the bearing
Data Source
AI summary
An electric rotary machine which may be employed as a dc motor in an automotive engine starter. The motor includes an armature equipped with an armature shaft, a commutator, brushes, and a bearing retaining an end of the armature shaft. The surface of the commutator has a plurality of protrusions extending in parallel to each other in a direction of rotation of the commutator. Each of the brushes has formed in the bottom thereof grooves in which the protrusions of the commutator are fit. The brushes are urged into constant engagement of the grooves with the protrusions on the commutator to establish electrical contacts between the brushes and the commutator and minimize movement of the armature shaft relative to the bearing.