Linear Motor Segment Spacing for Thermal Expansion Compensation
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Solution Overview
Problem
Long-stator linear motors face challenges in compensating for thermal expansion of transport segments due to temperature fluctuations, leading to uneven magnetic flux and mechanical stresses when transport segments are directly adjacent, which disrupts the uniform movement of transport units.
Innovation Solution
Spacing adjacent transport segments by less than half the slot pitch of their end coils, with a segment distance that allows thermal expansion compensation and vibration decoupling, and using an elastic material with high magnetic conductivity between segments to maintain a uniform magnetic flux.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If transport segments are directly adjacent to each other, then a uniform magnetic field is formed, but thermal expansion cannot be compensated leading to mechanical stresses
Solution Approach 1:
A gap is introduced between adjacent transport segments as an intermediary space. This gap serves dual purposes: it allows thermal expansion of segments without generating mechanical stresses, and simultaneously maintains magnetic field uniformity through carefully positioned drive coils that extend into the gap region. The gap acts as a buffer zone that decouples the thermal expansion of segments while preserving the continuity of the magnetic field.
Solution Approach 2:
The slot pitch of drive coils is varied in the region of the gap between transport segments. By changing the coil spacing parameter locally (making it smaller than the standard slot pitch), the magnetic field distribution is optimized to compensate for the discontinuity introduced by the gap. This parameter change ensures that the magnetic field remains uniform across the gap region, preventing disruptions to transport unit movement while allowing thermal expansion.
2Stress or pressure
If a gap is introduced between transport segments, then thermal expansion can be compensated, but the magnetic field becomes uneven causing disruptive influences
Solution Approach 1:
The slot pitch of drive coils is reduced in the gap region compared to the standard slot pitch used within transport segments. This local parameter change increases the density of drive coils in the gap area, creating a stronger and more uniform magnetic field that compensates for the discontinuity. The modified coil spacing ensures that the magnetic flux density remains consistent across the gap, preventing uneven magnetic fields and disruptive influences on transport units.
Solution Approach 2:
The drive coil arrangement is made non-uniform in the specific region of the gap between transport segments. While standard segments have uniform coil spacing, the gap region features adjusted coil positioning with smaller slot pitches. This local modification of coil quality (spacing and distribution) creates a tailored magnetic field distribution that specifically addresses the needs of the gap region, maintaining field uniformity despite the physical discontinuity.
3Ease of manufacture
If drive coils are spaced evenly, then manufacturing is simplified, but thermal expansion causes deformation of the transport section
Solution Approach 1:
The transport route is divided into discrete transport segments that are separated by gaps. Each segment can expand or contract independently within its gap boundaries, preventing the accumulation of thermal stresses that would lead to deformation of the entire transport section. The segmentation allows localized thermal management while maintaining overall system integrity.
Solution Approach 2:
The slot pitch parameter is selectively modified in the gap regions between transport segments while maintaining uniform spacing within segments. This creates a piecewise uniform coil distribution that is easier to manufacture than a completely non-uniform arrangement, while still accommodating thermal expansion. The parameter change is localized to only where needed, preserving manufacturing simplicity in the majority of the system.
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 configuration minimizes the impact of thermal expansion on the magnetic field, reduces mechanical stresses, and ensures smooth operation by maintaining a uniform magnetic flux and allowing for thermal expansion without compromising the magnetic field uniformity.
Implementation Method 1
The (electro)magnetic fields of the drive magnets and the drive coils interact to generate a propulsion force on the transport unit
Implementation Method 2
using an elastic material with high magnetic conductivity between segments to maintain a uniform magnetic flux
Implementation Method 3
compensating for thermal expansion of transport segments due to temperature fluctuations
Data Source
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AI summary
In order to provide a transport device (1) in the form of a long stator linear motor with which the negative effects of a non-uniform magnetic flux in the impact area (10) of two adjacent transport segments (TSk, TSk+1) can be at least mitigated, it is provided according to the invention that the distance (I) between the coil center of an end coil (7e) of a transport segment (TSK, TSk+1) and the respective end of the transport segment (TSK, TSk+1) is less than half the slot pitch τne2 of the two adjacent end coils (7e) of the transport segments (TSk, TSk+1), wherein the slot pitch (τne) of the two adjacent end coils (7e) corresponds to the slot pitch (τη) of the drive coils (7, 8) of at least one of the transport segments (TSk, TSk+1).