Solenoid Drive Bypass Device Reduces Pinion Wear
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Solution Overview
Problem
Existing solenoid drives for internal combustion engine starters experience high magnetic forces that lead to increased wear on the pinion and gearwheel teeth during the starting process, due to the intense magnetic field required for axial adjustment, resulting in friction and potential damage.
Innovation Solution
The solenoid drive incorporates a bypass device that diverts magnetic field lines away from the axial gap between the plunger and plunger stop, reducing the magnetic forces required for initial adjustment and allowing for a simpler, less costly construction with broader production tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high magnetic forces are used to adjust the pinion from non-engagement to engagement position, then the pinion can be reliably transferred into the gearwheel, but wear on the pinion and gearwheel teeth increases
Solution Approach 1:
The solenoid drive operates in two distinct phases: first applying high magnetic forces to overcome static friction and initiate movement, then reducing forces once movement begins. This periodic application of force prevents continuous high-stress contact between teeth while ensuring reliable engagement initiation
Solution Approach 2:
The magnetic force parameter is dynamically adjusted during the engagement process. The control unit modifies the electrical power supplied to the coil arrangement, transitioning from high force mode for initial engagement to reduced force mode for maintaining position, thereby minimizing tooth wear while ensuring reliable engagement
2Reliability
If high electrical power is supplied to the coil arrangement to hold the plunger static in active position, then the pinion can be securely engaged, but energy consumption increases
Solution Approach 1:
The coil arrangement operates intermittently rather than continuously. High electrical power is supplied only during the brief period needed to establish engagement, then power is reduced or interrupted while the plunger position is maintained by mechanical constraints and residual magnetic effects
Solution Approach 2:
The solenoid drive performs the energy-intensive engagement action in advance, transferring the pinion into the gearwheel position before the starting operation begins. Once engaged, the system maintains position with minimal energy input, separating the high-energy engagement phase from the low-energy maintenance phase
3Force
If the bypass device is positioned close to the coil arrangement to effectively divert magnetic field lines, then magnetic forces are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The bypass device is designed to automatically position itself relative to the coil arrangement through its interaction with the magnetic field. The device self-adjusts to optimal positions where it effectively diverts magnetic field lines without requiring precise pre-positioning, eliminating the need for tight manufacturing tolerances
Solution Approach 2:
The bypass device is made axially movable rather than fixed, allowing it to dynamically adjust its position during operation. This mobility enables the device to find and maintain optimal positions for magnetic field diversion without requiring precise manufacturing, as the position can vary within a range while maintaining effectiveness
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 reduces wear on the pinion and gearwheel by minimizing the initial magnetic forces needed for tooth engagement, enhancing the reliability and reducing production costs while maintaining effective engagement and disengagement of the pinion with the gearwheel.
Implementation Method 1
the coil arrangement has to transmit comparatively large electromagnetic forces to the plunger in order to draw the latter into the coil interior space and hold said plunger therein
Implementation Method 2
a bypass device that diverts magnetic field lines away from the axial gap between the plunger and plunger stop, reducing the magnetic forces required for initial adjustment
Data Source
AI summary
A solenoid drive may include a ferromagnetic housing having a coil receiving chamber axially limited by opposing first and second face side walls, and a cylindrical coil arrangement having at least one electric coil, and being arranged in the coil receiving chamber and coaxially surrounding a cylindrical coil interior space. The solenoid drive may also include a ferromagnetic plunger stop having a central region projecting axially in the coil interior space, and a ferromagnetic plunger arranged at the housing opposing the plunger stop. The plunger may project axially into the coil interior space, and may be adjustable axially bi-directionally between an active position proximal to the central region and a passive position distal to the central region. The solenoid drive may further include a ferromagnetic bypass device arranged coaxially to the coil arrangement, radially within the at least one coil, and spaced apart axially from the face side walls.