Electromagnet Pole Tube Centering and Extrusion Coating
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Solution Overview
Problem
In automatic transmissions, electromagnetically operated pressure control valves require precise force-current characteristics with low variance and minimal magnetic hysteresis to achieve high pressure precision and low friction, which existing pole tube designs fail to consistently provide due to radial air gaps and eccentricities causing transverse forces.
Innovation Solution
A method involving concentric configuration and centering of two magnetic pole tube components with a nonmagnetic ring, using a form-fitting connection through extrusion coating or casting to minimize air gaps and prevent movement, thereby reducing friction and transverse forces, and employing knurls or grooves for improved material connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If radial air gaps are reduced to achieve high force level, then magnetic force increases, but manufacturing precision requirements increase due to sensitivity to eccentricities
Solution Approach 1:
The patent applies preliminary centering of the pole tube components and nonmagnetic ring on a common centering pin before the extrusion coating process. This preliminary action establishes precise concentric relationships in advance, allowing the subsequent coating to lock in these precise positions without requiring extremely tight manufacturing tolerances on the individual components themselves.
Solution Approach 2:
The extrusion coating acts as an intermediary substance that bonds the pole tube components and nonmagnetic ring together while maintaining their pre-established concentric positions. The coating fills and secures the interfaces between components, preventing any relative movement or decentering that would create air gaps, thus achieving both high magnetic force and acceptable manufacturing precision.
2Strength
If pole tube components are connected with thermal joining methods, then structural strength increases, but armature bearing surface quality deteriorates due to introduced stresses
Solution Approach 1:
The patent replaces thermal joining methods (welding, brazing) with a mechanical extrusion coating process. The extrusion coating material is forced under pressure into the interfaces between components, creating a strong mechanical bond without the thermal stresses that would distort or damage the precision armature bearing surfaces. This substitution maintains structural strength while preserving surface quality.
3Reliability
If nonmagnetic ring is added to prevent magnetic short circuit, then magnetic circuit performance improves, but device complexity increases
Solution Approach 1:
The patent merges the nonmagnetic ring with the pole tube components into a single integrated assembly that is jointly coated with extrusion coating material. The ring, pole core, and magnet tube are positioned concentrically on a centering pin and coated together as one unit, creating a unified magnetic circuit structure. This merging approach maintains the functional benefits of the nonmagnetic ring while reducing overall complexity compared to separately manufactured and assembled 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
This approach allows for high magnetic forces with low friction armature bearing, minimizing air gaps and preventing decentering, resulting in precise pressure control and reduced component stress.
Implementation Method 1
a nonmagnetic ring situated axially between the pole tube components for an electromagnet
Implementation Method 2
Form-fitting connection, in particular extrusion coating and/or casting an exterior lateral surface of the pole tube components and of the ring
Implementation Method 3
the radial air gaps between the pole tube and the armature to be configured small... a high force level of the electromagnets
Implementation Method 4
a low-friction bearing... friction in the armature bearing... transverse forces, which burden the armature bearing and cause increased friction
Data Source
AI summary
A method for manufacturing a pole tube having two magnetic pole tube components and having one nonmagnetic ring, which is situated axially between the pole tube components, for an electromagnet, in particular for a solenoid valve of an automatic transmission in a motor vehicle, including the following: concentric configuration and/or centering of the pole tube components and of the ring, in particular on a centering pin; form-fitting connection, in particular by extrusion coating and/or casting an exterior lateral surface of the pole tube components and of the ring.