Electromagnetic Clutch Actuation with Bias Current Pre-Energizing
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Solution Overview
Problem
Conventional powertrain systems with electromagnetic actuators face challenges in quickly actuating the clutch due to the temporal limitations of current build-up and resistance, which cannot be improved without increasing the maximum control current, leading to higher component costs.
Innovation Solution
A method that involves energizing the actuator with a bias current before initiating synchronization of clutch components, allowing the actuator to build up from a non-zero value, thereby reducing the time required to reach the end position of the piston by using a significantly greater actuating current once synchronization is achieved.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the maximum control current is increased to improve the current build-up speed, then the closing switching time of the clutch assembly is reduced, but the component costs increase due to higher current load requirements
Solution Approach 1:
The patent applies preliminary action by pre-charging the capacitor with a first voltage level before the clutch actuation event occurs. This stored electrical energy is then rapidly discharged through the solenoid actuator when actuation is required, enabling fast piston movement without needing to increase the maximum control current rating of the power electronics. The capacitor acts as an energy reservoir that is prepared in advance, allowing the system to deliver high peak power only when needed rather than requiring the entire power train to be sized for peak conditions continuously.
2Speed
If the maximum control current is increased to reduce the closing switching time, then the piston reaches the end position faster, but the power electronics design must correspond to the higher maximum current load
Solution Approach 1:
The capacitor is pre-charged to a first voltage level before actuation, storing electrical energy in advance. When clutch actuation is required, this stored energy is rapidly discharged through the solenoid, generating the high current needed for fast piston movement without requiring the power electronics to be continuously rated for this peak current.
Solution Approach 2:
The system changes the voltage parameter dynamically by switching from a first voltage level (during charging) to a second, higher voltage level (during actuation). This voltage step-change enables the delivery of high peak power for fast piston movement while the average power requirements remain lower, allowing the use of smaller, less expensive power electronics components rated for average rather than peak conditions.
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 method shortens the switching time of the clutch by approximately 20 milliseconds, without increasing the maximum control current, thereby improving torque transmission efficiency without the need for more expensive power electronics.
Implementation Method 1
The actuation unit comprises an electromagnetic actuator with a piston, wherein the piston is displaced from a starting position into an end position to actuate the clutch
Data Source
AI summary
A powertrain of a vehicle can be operated. The powertrain can have at least one transmission housing, a clutch assembly which is arranged therein and which comprises a clutch that operates in a positively locking manner, and an actuation unit for actuating the clutch. The clutch comprises at least one first clutch component, which can be moved along an axial direction, and a second clutch component, said clutch components being connected together in a form-fitting manner upon actuating the clutch; wherein the actuation unit comprises an electromagnetic actuator with a piston, and the piston is moved from a starting position into an end position along the axial direction upon actuating the clutch, thereby moving the first clutch component.