Engine Brake Hydraulic Capsule with Plunger Retraction Latch
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Solution Overview
Problem
Conventional hydraulic capsules for engine brakes face challenges such as spatial constraints, lack of flexibility in coupling, and inability to maintain the plunger in a retracted state during mode transitions, necessitating an improved engine brake mechanism.
Innovation Solution
The engine brake mechanism and actuation mechanism are separated into distinct components, housed in separate bores within the rocker arm, allowing for reduced size and height, accommodating various engine platforms, and incorporating a built-in mechanism to keep the plunger retracted during mode transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the hydraulic actuation portion and plunger portion are arranged vertically in the same assembly, then the capsule can be compact, but the dimensions exceed the available space in certain engine platforms
Solution Approach 1:
The hydraulic capsule is divided into two separate assemblies: a hydraulic actuation assembly and a plunger assembly. The hydraulic actuation assembly is mounted to the rocker arm, while the plunger assembly is mounted to the exhaust valve. This segmentation allows each assembly to be optimized independently for space constraints, eliminating the need for a tall vertical arrangement while maintaining compact overall dimensions.
2Reliability
If a larger lost motion spring is used to absorb inertia from rocker arm and valve movement, then the spring can handle the inertia, but the capsule becomes bulkier
Solution Approach 1:
The lost motion spring is extracted from the hydraulic capsule assembly and mounted separately on the plunger assembly. This allows the spring to be optimized for inertia absorption without increasing the capsule volume, as the spring is positioned externally on the plunger rather than being contained within the capsule structure.
3Device complexity
If the plunger component does not have a return mechanism, then the structure can be simpler, but the plunger cannot return and stay in the retracted state when switching from engine braking mode to drive mode
Solution Approach 1:
The plunger assembly incorporates a self-return mechanism using a return spring and latch pin system. When hydraulic pressure is released, the return spring automatically pushes the plunger back to its retracted position, and the latch pin engages with a latch hole to maintain the retracted state. This self-service mechanism ensures reliable position control without requiring external intervention or complex additional components.
4Ease of manufacture
If the capsule is designed with fixed coupling requirements, then the manufacturing can be standardized, but the capsule lacks flexibility to accommodate different coupling requirements for securing the capsule to the rocker arm
Solution Approach 1:
The coupling mechanism is designed with adjustable components, including a threaded rod with variable length and a clamp assembly with adjustable positioning. This allows the coupling to be dynamically adjusted to accommodate different rocker arm configurations and coupling requirements while maintaining standardized manufacturing processes for the individual components.
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 reduces size and height requirements, enhances coupling flexibility, and ensures the plunger remains retracted when switching from engine-brake mode to drive mode, improving packaging and operational efficiency.
Implementation Method 1
an actuation mechanism disposed within a second bore and configured to direct a fluid to the engine brake mechanism to hydraulically move the plunger to the extended position
Implementation Method 2
the plunger contains a spring disposed between latch pins, the spring being configured to bias the latch pins in an outward direction
Data Source
AI summary
A rocker assembly for a valvetrain comprises a rocker arm comprising a cam end, a center pivot bore, and a valve end, the valve end comprising a first bore. The engine brake actuator comprises an engine brake mechanism disposed within the first bore, the engine brake mechanism comprising a body and a plunger disposed within the body. The plunger is configured to translate between a retracted position and an extended position. The plunger contains a spring disposed between latch pins, the spring being configured to bias the latch pins in an outward direction. The body defines seats for receiving the latch pins. The rocker assembly further comprising an actuation mechanism disposed within a second bore and configured to direct a fluid to the engine brake mechanism to hydraulically move the plunger to the extended position and hydraulically move the latch pins toward each other.