Engine Cylinder Decompression via Inner Piston Actuation
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Solution Overview
Problem
Existing engine braking systems face challenges in efficiently decompressing engine cylinders during start-up, particularly in cold weather conditions, leading to increased battery power requirements and difficulty in engine turnover, while also requiring additional components and potentially increasing emissions.
Innovation Solution
A system comprising a vertically moveable member with a horizontally moveable inner piston and a hydraulic or pneumatic fluid supply passage, which actuates an engine valve to decompress the cylinder, allowing for easier engine start-up and reduced battery power consumption, and also enables bleeder braking by controlling exhaust valve opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If exhaust valves are held open during engine start-up to decompress the cylinder, then engine starting becomes easier and battery power requirements are reduced, but additional valve actuation components and control systems are required
Solution Approach 1:
The cam mechanism is designed to serve multiple functions: during normal operation it actuates exhaust valves for standard engine cycles, while during start-up it holds the exhaust valve open to decompress the cylinder. This multi-functionality eliminates the need for separate decompression mechanisms, reducing overall system complexity while maintaining ease of engine starting.
Solution Approach 2:
The valve actuation system utilizes the engine's own cam mechanism and valve train components to provide decompression during start-up, rather than requiring an external or separate actuation system. The existing mechanical infrastructure serves the dual purpose of normal valve operation and start-up decompression, minimizing additional components needed.
2Power
If compression-release engine braking is used to provide retarding force, then effective braking is achieved, but high force requirements and noise generation occur
Solution Approach 1:
Instead of fully opening the exhaust valve for compression-release braking, the system employs partial opening of the valve during the compression stroke. This partial action provides sufficient retarding force for engine braking while avoiding the high noise levels and extreme force requirements associated with complete valve opening, thus reducing harmful effects while maintaining effective braking capability.
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 system facilitates easier engine start-up, reduces battery and starter system requirements, lowers weight, and improves fuel efficiency, while providing effective engine braking with reduced noise and lower force requirements.
Implementation Method 1
A system comprising a vertically moveable member disposed above an engine valve and having an inner piston bore extending horizontally into the vertically moveable member; a horizontally moveable inner piston disposed in the inner piston bore; a first spring provided in the inner piston bore, the first spring biasing the inner piston into a predefined position in the inner piston bore; and a hydraulic or pneumatic fluid supply passage communicating with the inner piston bore
Implementation Method 2
a first spring provided in the inner piston bore, the first spring biasing the inner piston into a predefined position in the inner piston bore
Implementation Method 3
one or more exhaust valves may be selectively actuated to provide compression-release, bleeder, and/or partial bleeder engine braking
Data Source
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AI summary
A system for actuating an engine valve to decompress an engine cylinder for engine start up and/or engine braking is disclosed. The system may include a first member, such as an outer piston, disposed above an engine valve, which receives an inner piston extending into a bore provided in the first member. One or more springs may bias the inner piston into a predefined position in the first member. The inner piston may include a lower surface that directly, or through an intervening sliding pin, actuates an engine valve in response to the application of fluid pressure on the inner piston. The inner piston may be used to decompress an engine cylinder for engine start up and/or to provide engine braking.