Pigtail Harness Segmentation for Valve Timing Stress
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Solution Overview
Problem
The existing valve-timing control apparatus for internal combustion engines experiences reduced durability of the pigtail harness due to stress concentration from alternating torque, which is exacerbated by the need for a longer harness to prevent brush dislodgment, thereby compromising assembly efficiency.
Innovation Solution
A valve-timing control apparatus with a power-feeding mechanism that includes a retaining member with a brush retaining portion and protruding portions to securely hold the power-feeding brush, and a pigtail harness with contact points to absorb deformation, ensuring the brush remains in contact with the slip ring and preventing stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pigtail harness is made longer to prevent stress concentration, then the durability of the pigtail harness is improved, but the power-feeding brush may dislodge from the retaining portion, reducing assembly efficiency
Solution Approach 1:
The pigtail harness is segmented into multiple sections with different lengths, where the first pigtail harness connects the power-feeding brush to the slip ring with a longer length to prevent stress concentration, and the second pigtail harness connects to the control unit with a shorter length, optimizing both durability and assembly efficiency
Solution Approach 2:
Different sections of the pigtail harness have different lengths tailored to their specific functional requirements. The section near the power-feeding brush has greater length to absorb vibration and prevent stress concentration, while other sections have appropriate lengths for their specific connections, achieving localized optimization
2Productivity
If the pigtail harness is made shorter to improve assembly efficiency, then the power-feeding brush remains securely retained, but stress concentration occurs at the harness, reducing durability
Solution Approach 1:
The pigtail harness system is divided into multiple independent harnesses with different lengths. The first pigtail harness specifically connects the power-feeding brush to the slip ring with optimized longer length to prevent stress concentration, while the second pigtail harness connects to the control unit, allowing each segment to be optimized independently for its specific function
Solution Approach 2:
The pigtail harness has non-uniform length distribution where the section most susceptible to vibration and stress (near the power-feeding brush and slip ring) has greater length to absorb deformation, while other sections have shorter lengths appropriate for their connections, achieving local optimization of both durability and assembly 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
This design enhances the assembly efficiency of structural members while maintaining the durability of the pigtail harness by preventing stress concentration and disconnection, thus improving long-term fatigue resistance and preventing electrical shorts.
Implementation Method 1
a permanent magnet provided along an inner circumference of the accommodating space of the motor housing, the permanent magnet having a plurality of magnetic poles in a circumferential direction thereof; a rotor provided inside the permanent magnet and configured to rotate relative to the permanent magnet, wherein a coil is wound on the rotor and is configured to form a plurality of magnetic poles in a circumferential direction of the rotor by energization
Data Source
AI summary
A valve-timing control apparatus includes a motor housing formed with an accommodating space; a permanent magnet provided along an inner circumference of the accommodating space of the motor housing; a rotor configured to rotate relative to the permanent magnet; a transmitting mechanism configured to transmit a rotational force of the rotor to a cam shaft; a switching brush mounted on the motor housing and configured to switch an energization of coil; a power-feeding brush provided to one of the motor housing and a fixed member and configured to feed electric power to the switching brush; a slip ring provided to another of the motor housing and the fixed member and being in contact with the power-feeding brush; a pigtail harness connecting the power-feeding brush with a power-feeding terminal; and contact portions bending the pigtail harness at a plurality of spots of the pigtail harness by contact with the pigtail harness.