Hydraulic Variable Stroke Internal Combustion Engine
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Solution Overview
Problem
Conventional internal combustion engines suffer from inefficiency due to a short moment arm during the power stroke, leading to less than desired work generation efficiency, as the force from combustion is not effectively transferred to the crankshaft due to the co-linear alignment of the crankshaft and connecting rod axes at maximum compression.
Innovation Solution
The engine configuration includes a crankshaft with a crankpin offset from its rotational axis, and a connecting rod or piston with a variable length via hydraulic operation, delaying the piston's movement until a more effective moment arm is achieved, allowing the combustion force to be converted into torque more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the piston and connecting rod are configured with fixed lengths in a conventional internal combustion engine, then the engine structure is simple and easy to manufacture, but the moment arm during the power stroke is short, resulting in low torque transfer efficiency and poor fuel efficiency
Solution Approach 1:
The connecting rod length is made variable through hydraulic actuation, allowing the moment arm to be dynamically adjusted during the engine cycle. This enables optimization of torque transfer at different operating conditions while maintaining a relatively simple overall engine structure.
Solution Approach 2:
A hydraulic system is introduced to control the connecting rod length by adjusting the position of the piston within the connecting rod. The hydraulic actuator responds to combustion pressure and control signals to optimize the moment arm length, improving fuel efficiency without requiring complex mechanical redesign of the entire engine.
2Power
If the connecting rod length is increased to provide a longer moment arm for better torque transfer, then the torque transfer efficiency improves, but the device complexity increases due to the need for variable length mechanisms
Solution Approach 1:
The connecting rod is segmented into a fixed outer structure and a movable inner piston that can adjust its position hydraulically. This segmentation allows the effective length to be varied without redesigning the entire connecting rod, achieving better torque transfer with minimal added complexity.
Solution Approach 2:
The hydraulic system used to control connecting rod length also serves to balance the piston motion and manage combustion forces. This multi-functionality reduces the need for separate balancing mechanisms, thereby limiting the increase in device complexity while achieving improved torque transfer.
3Productivity
If the piston motion is delayed via hydraulic operation to achieve a longer moment arm, then the combustion force is more effectively converted to torque, but the device complexity increases due to the hydraulic control system
Solution Approach 1:
The hydraulic control system is integrated with the existing engine lubrication and cooling systems, sharing common fluid reservoirs and control electronics. This merging reduces the overall complexity increase by utilizing existing infrastructure rather than adding completely separate systems.
Solution Approach 2:
The hydraulic system is designed to respond automatically to combustion pressure changes and engine operating conditions, reducing the need for complex external control systems. The system self-regulates the piston position based on real-time combustion forces, improving work generation efficiency with minimal additional control complexity.
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 enhances torque transfer and efficiency by ensuring the combustion force coincides with a longer moment arm, resulting in improved power output and fuel efficiency during the power stroke.
Implementation Method 1
at least one of the piston and the connecting rod is configured such that a distance between a cross-sectional center of the crankpin and an upper surface of the piston is variable via hydraulic operation
Implementation Method 2
combustion of an air/fuel mixture within a combustion chamber defined by the piston, the cylinder, and a cylinder head forces the piston toward the crankshaft
Data Source
AI summary
An internal combustion engine may include a cylinder block defining a cylinder and a crankshaft having a crankpin. The crankshaft is rotatably received by the cylinder block and rotates along a longitudinal axis, and the crankpin defines a longitudinal axis parallel to and offset by a distance with respect to the longitudinal axis along which the crankshaft rotates. The engine may further include a piston configured to reciprocate within the cylinder and a connecting rod operably coupled to the piston and the crankpin. At least one of the piston and the connecting rod is configured such that a distance between a cross-sectional center of the crankpin and an upper surface of the piston is variable via hydraulic operation.