Pneumatic Valve Spring for Combustion Engine
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Solution Overview
Problem
Conventional combustion engines with camshafts require large, power-consuming valve springs to ensure proper valve closure across varying engine speeds, and alternative solutions like pneumatic valve springs are costly and complex, making them unsuitable for passenger vehicles or heavy vehicles.
Innovation Solution
A combustion engine design featuring a pneumatic valve spring with a gas spring volume that adjusts pressure by fluid communication with an adjacent gas volume, using a telescopically displaceable valve spring cover to reduce return spring force and power consumption, allowing hydraulic liquid presence without compromising performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a strong coil spring is used to ensure proper valve closure at high engine speeds, then valve closure reliability is improved, but power consumption increases and unnecessary valve spring force is applied during normal operation
Solution Approach 1:
The valve spring system transitions from a static coil spring with constant high force to a dynamic pneumatic system where the gas spring force varies with compression. The pneumatic valve spring provides high force only when needed (at high engine speeds or large valve lifts) and reduces force during normal operation, thereby improving reliability when required while reducing power consumption during normal operation.
Solution Approach 2:
The system changes the physical state and parameters of the spring force by using compressed gas instead of a mechanical coil spring. The gas pressure can be adjusted and varies dynamically with volume changes, allowing the spring force parameter to be optimized for different operating conditions rather than being fixed at the highest required force level.
2Speed
If a pneumatic valve spring with oxygen-free gas is used to achieve fast response at high engine speeds, then valve response speed is improved, but system complexity and cost increase due to complicated sealing requirements
Solution Approach 1:
Hydraulic liquid is introduced as an intermediary substance within the pneumatic valve spring system. The liquid serves multiple functions: it lubricates moving parts, cools the gas spring, and most importantly provides sealing between the gas and the external environment. This eliminates the need for complex seals while allowing the use of breathable air or less restrictive gas compositions.
Solution Approach 2:
The system combines pneumatic and hydraulic principles by using compressed gas for the spring force and hydraulic liquid for sealing and lubrication. This hybrid approach leverages the advantages of both fluid types: gas compressibility for energy storage and hydraulic liquid incompressibility for reliable sealing and lubrication.
3Reliability
If the valve spring force is increased to prevent unintentional valve opening, then valve control reliability is improved, but energy consumption increases unnecessarily during normal operation
Solution Approach 1:
The pneumatic valve spring provides dynamic force adjustment based on operating conditions. During normal operation, the gas spring expands and provides minimal force, reducing energy loss. When high reliability is needed (high engine speeds, large valve lifts), the gas compression increases and provides higher force automatically, maintaining valve control reliability without continuous high energy input.
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 design reduces energy needed to open the engine valve, provides an adjustable return spring force, and allows hydraulic liquid in the gas spring without negative effects, resulting in improved efficiency and cost-effectiveness compared to traditional systems.
Implementation Method 1
a pneumatic valve spring with a gas spring volume that adjusts pressure by fluid communication with an adjacent gas volume
Implementation Method 2
it is desirable that the hydraulic liquid is present in the gas that usually is constituted by air, for lubricating, cooling, and sealing purposes
Implementation Method 3
it is desirable that the hydraulic liquid is present in the gas that usually is constituted by air, for lubricating, cooling, and sealing purposes
Data Source
AI summary
A combustion engine includes an engine valve arranged to selectively open/close a combustion chamber of the engine, a cylinder head adjacent the combustion chamber, arranged to guide a valve stem of the engine valve, the engine valve being axially displaceable relative to the cylinder head between the combustion chamber closed position and the combustion chamber fully opened position, and a valve spring retainer connected to the valve stem. The valve spring retainer partly delimits a gas spring volume, which is in fluid communication with an adjacent gas volume via a port when the engine valve is in the combustion chamber closed position, and which is separated from the adjacent gas volume when the engine valve is in the combustion chamber fully open position, the port being open during at least 25% of the maximal stroke of the engine valve and being closed due to a displacement of the engine valve.