Inductive Coupling in Rocker Arm Assemblies
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Solution Overview
Problem
Hydraulically actuated valvetrain systems for variable valve lift (VVL) and cylinder deactivation (CDA) face complexity and high oil demand, leading to limitations in existing supply systems, and there is a need for diagnostic sensors to provide operational information.
Innovation Solution
The implementation of an electrically latched rocker arm assembly with mutually inductively coupled coils for power transfer and communication, utilizing AC power in the range of 50 kHz to 1 MHz, and an electromagnetic latch assembly with a bi-stable mechanism for valve actuation, allowing for efficient power transfer and diagnostic capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulically actuated latches are used in rocker arm assemblies, then valve actuation function is achieved, but system complexity and oil demand increase
Solution Approach 1:
The patent replaces the hydraulic actuation system with an electromagnetic latch mechanism. The electromagnetic latch uses electrical fields and magnetic forces to achieve the same valve actuation function that previously required hydraulic pressure, oil pumps, and complex fluid control systems. This substitution eliminates the need for hydraulic feeds while maintaining reliable valve actuation.
2Reliability
If hydraulically actuated latches are used in rocker arm assemblies, then valve actuation function is achieved, but oil demand approaches limits of supply systems
Solution Approach 1:
The electromagnetic latch mechanism replaces the hydraulic system, eliminating the need for oil delivery infrastructure. Instead of requiring pressurized oil feeds and pumps, the system uses electrical power to generate magnetic fields that actuate the latch, thereby reducing oil demand to zero for latch operation.
3Device complexity
If electrically latched rocker arm assemblies are used, then system complexity and oil demand are reduced, but power consumption increases
Solution Approach 1:
The electromagnetic latch operates periodically rather than continuously. Power is applied only during the brief moments when valve switching is required, and the latch maintains its state without continuous energy input. This periodic actuation significantly reduces overall power consumption compared to continuous hydraulic pumping systems.
Solution Approach 2:
The latch mechanism uses dynamic electromagnetic fields to achieve actuation with minimal energy. The system exploits the transient nature of electromagnetic induction, where a brief electrical pulse generates a magnetic field strong enough to switch the latch state, after which no further energy is required to maintain that state.
4Reliability
If inductive coupling is used for power transfer, then wire-related failures are eliminated, but coupling factor requirements increase
Solution Approach 1:
The patent introduces magnetic fields as an intermediary for power and signal transfer between the stationary base and the moving rocker arm. Instead of direct electrical contact through wires that can fail, the system uses inductive coupling where electrical signals are converted to magnetic fields, transmitted through the air gap, and converted back to electrical signals on the other side.
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 solution reduces system complexity, enhances power transfer efficiency, and enables reliable diagnostic monitoring, improving the operational flexibility and reliability of valvetrain systems while minimizing oil demand.
Implementation Method 1
The first and second conductors are inductively coupled to an extent that enables effective power transfer or communication between the first and second circuits. In these teachings, the first and second conductors are mutually-inductively coupled. In some of these teachings, the mutually-inductively coupled conductors are coils
Implementation Method 2
In some of these teachings, the second circuit is configured to drive the second coil with AC power in the range from 50 kHz to 1 MHz. AC power transfer through inductive coupling may be most efficient in that range
Implementation Method 3
In some of these teachings, one or more pole pieces are configured to facilitate inductive power transfer between the first and second coils. The pole pieces may guide magnetic fields generated by the second coil toward the first coil
Data Source
AI summary
An internal combustion engine includes a cylinder head and a valvetrain including a poppet valve, a cam shaft on which is mounted a cam, and a rocker arm assembly. The rocker arm assembly includes a rocker arm and a cam follower configured to engage the cam as the cam shaft rotates. The rocker arm assembly is operative to transmit force from the cam to actuate the valve and includes an electrical device mounted to the rocker arm. A first electrical circuit includes the electrical device and a first conductor mounted to the rocker arm and a second electrical circuit includes a second conductor mounted off the rocker arm. The first and second conductors are inductively coupled to an extent that enables effective power transfer or communication between them. Inductive power transfer avoids the use of wires that could become caught, clipped, or fatigued and consequently short out.