Bistable Actuator Spring Gradient and Magnetic Overlap
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Solution Overview
Problem
Existing bistable electromagnetic actuating devices have limited travel range and fast return time due to steep magnetic force-travel curves, requiring high spring constant springs for efficient camshaft adjustment, which restricts the use of magnetic force for prestressing and results in narrow return path.
Innovation Solution
The use of spring means with a small spring pitch and high maximum prestress, combined with axial overlapping of the core region and permanent magnet means to maintain a higher magnetic force over a longer travel, allowing for a flat spring characteristic and earlier return of the actuating element to the core region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If spring means with large spring characteristic gradient are used to ensure fast return of actuating element, then return time is improved, but travel range in which permanent magnetic force is available is reduced to very narrow range
Solution Approach 1:
The invention changes the spring characteristic from large gradient to small gradient (flat spring characteristic), allowing the spring to provide accelerating force over a longer travel range. This parameter change enables the spring to maintain useful force over the extended distance where permanent magnetic force is available, resolving the contradiction between fast return and adequate travel range.
Solution Approach 2:
The invention creates a dynamic interaction where the flat spring characteristic allows progressive force delivery throughout the travel range. The spring force dynamically complements the permanent magnetic force, with the spring providing acceleration over the extended distance rather than requiring extremely steep characteristics for fast return.
2Length of moving object
If axial overlapping of core region and permanent magnet means is implemented to maintain higher magnetic force over longer travel, then travel range is improved, but device complexity increases
Solution Approach 1:
The invention introduces axial overlapping between the core region and permanent magnet means, utilizing the axial dimension to extend the magnetic interaction distance. This dimensional approach maintains magnetic force over longer travel without requiring complex lateral mechanisms or additional components.
Solution Approach 2:
The invention merges the core region and permanent magnet means in the axial direction, creating an overlapping configuration where the magnetic circuit components are combined along the travel path. This merging extends the effective magnetic interaction zone without adding separate complex subsystems.
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 enables faster travel to the end position away from the core region and earlier return, using spring force over a longer distance, improving switching times and tolerance range in camshaft adjustment devices.
Implementation Method 1
permanent magnet means interact with a stationary core region, generating an attractive force together
Implementation Method 2
a compression spring loading the actuating element with force away from the core region is maximally prestressed
Data Source
AI summary
A bistable electromagnetic actuating apparatus (1) having an actuating element (2), which forms an engagement region (4) at the end and can be moved axially between two end positions, in particular for engaging in a control groove in a cam of an internal combustion engine, and having a coil device (11) which is provided in a stationary manner relative to the actuating element (2) and is designed to exert a force on said actuating element, wherein the actuating element (2) has permanent magnets (5) which are designed to interact with a core region (3) which is provided in a stationary manner relative to the actuating element (2), and wherein the coil device (11) is designed to generate a counterforce, which counteracts a retaining force of the permanent magnets (5) and releases said permanent magnets from the core region (3), in response to an electronic actuation signal, and wherein a spring is arranged such that it applies a spring force to the actuating element (2) in an axial direction which faces away from the core region (3).