Valve Drive Actuator Eliminates H-Bridge Complexity
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Solution Overview
Problem
Conventional valve drive devices for internal combustion engines require complex and costly control units with multiple outputs and H-bridges to reverse the polarity of electric motors, leading to increased installation space, weight, and the risk of faulty switching during valve actuation.
Innovation Solution
A valve drive device with an electrically controllable actuator that alternately moves a cam piece between positions using the same electrical polarity, eliminating the need for H-bridges and reducing the number of outputs required, and utilizing a linear actuator with a single coil and armature to achieve cost-effective and space-saving valve actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control units with H-bridges and multiple outputs are used to reverse motor polarity, then valve actuation control is achieved, but device complexity and installation space increase
Solution Approach 1:
The patent extracts and eliminates the H-bridge circuit from the control system. Instead of using an H-bridge to reverse motor polarity, the system uses a single-sided PWM output that directly controls the motor in one direction while mechanical elements (cam piece with different cam profiles, follower) provide the bidirectional motion. This removes the complex polarity reversal hardware while maintaining full valve actuation control.
Solution Approach 2:
The patent replaces the electrical mechanism (H-bridge polarity reversal) with a mechanical mechanism (cam piece with multiple cam profiles, follower, and spring). The motor rotates in one direction to advance the cam piece axially, and the cam profiles mechanically translate this unidirectional rotation into bidirectional valve motion, substituting electrical complexity with mechanical functionality.
2Adaptability or versatility
If H-bridges and multiple outputs are used in control units, then motor polarity reversal is achieved, but installation space and weight increase
Solution Approach 1:
The H-bridge circuit is completely extracted from the control unit. The system achieves motor control versatility through a single PWM output that drives the motor in one direction, while the mechanical cam-follower system provides the polarity reversal effect mechanically, eliminating the need for heavy H-bridge components.
Solution Approach 2:
The single PWM output and unidirectional motor serve multiple functions: they drive the cam piece axially, the cam profiles convert this to rotational and bidirectional motion, and the spring provides reset functionality. This multi-functional mechanical system replaces what would traditionally require multiple electrical outputs and an H-bridge.
3Reliability
If conventional control units with H-bridges are used, then valve actuation is controlled, but cost of manufacture increases
Solution Approach 1:
The expensive H-bridge circuit is extracted from the control unit, significantly reducing component count and manufacturing cost. The control unit now requires only a single PWM output capability, eliminating the need for complex power switching hardware while maintaining full valve actuation control through the mechanical cam system.
Solution Approach 2:
The patent employs simpler, cheaper mechanical components (cam piece with profiles, follower, spring) that can be manufactured cost-effectively through conventional machining, replacing expensive electronic power control components. The mechanical elements are durable and can be produced at lower cost than H-bridge assemblies.
4Ease of operation
If H-bridges are used for polarity reversal, then motor direction control is achieved, but risk of faulty switching increases
Solution Approach 1:
The patent replaces the electrical switching mechanism (H-bridge) with a mechanical transmission system (cam piece, follower, spring). The motor rotates in one direction to advance the cam piece, and the cam profiles mechanically ensure bidirectional valve motion without any electrical switching, eliminating the risk of H-bridge faulty switching entirely.
Solution Approach 2:
The spring element provides a mechanical cushioning and reset mechanism. When the cam piece advances axially through unidirectional motor rotation, the spring is compressed; when the cam profile releases, the spring automatically returns the follower and cam piece to their initial positions, providing fail-safe mechanical reset functionality without electrical switching.
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
The solution reduces the complexity and cost of the control unit, minimizes installation space, and lowers the risk of faulty switching, enabling a reliable and efficient valve actuation with reduced weight and increased reliability.
Implementation Method 1
the actuator is designed to push the cam piece alternately back and forth between the positions in the case of successive controls with the same, in particular electrical, polarity
Data Source
AI summary
A valve drive device has a camshaft which includes a shaft element and a cam piece which can be driven by the shaft element and a first cam effecting a first stroke of a valve and a second cam effecting a second stroke of the valve, and is displaceable in the axial direction of the camshaft relative to the shaft element between a first position, in which the valve can be actuated by the first cam, and a second position in which the valve can be actuated by the second cam, and has an electrically controllable actuator via which the cam piece is displaceable relative to the shaft element in the axial direction as a result of an electrical control of the actuator. The actuator pushes the cam piece alternately back and forth between the positions in the case of successive electrical controls occurring with the same polarity.