Crosshead Engine Hydraulic Compression Ratio Adjustment
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Solution Overview
Problem
Existing crosshead engines require shutdown to change the compression ratio, as the shim plate between the piston rod and crosshead pin needs replacement with a different thickness, complicating the engine structure and operation.
Innovation Solution
A crosshead engine with a hydraulic pressure adjustment mechanism that varies the relative position of the piston rod and crosshead, allowing for adjustable compression ratios while the engine is operational, using a plunger pump and spill valve to control hydraulic pressure in the hydraulic pressure chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a shim plate is replaced with another shim plate having a different thickness to change the compression ratio, then the compression ratio can be adjusted, but the engine must be stopped and the structure becomes complicated
Solution Approach 1:
The patent applies hydraulic principles by introducing a hydraulic pressure chamber between the piston rod and crosshead pin. A hydraulic pressure adjustment mechanism supplies or discharges hydraulic oil to this chamber, using fluid pressure to move the piston rod relative to the crosshead, thereby changing the compression ratio while the engine is running without requiring shutdown or complex mechanical reconfiguration
2Adaptability or versatility
If multiple links are used to connect the piston rod and crankshaft to vary the compression ratio, then the compression ratio can be adjusted, but the connecting structure becomes complicated
Solution Approach 1:
The patent extracts the compression ratio adjustment function from the complex mechanical link structure and relocates it to the piston rod-crankshaft connection point. By using the hydraulic pressure chamber at this specific location, the invention eliminates the need for multiple variable-length links while achieving the same functional outcome of adjustable compression ratio
Solution Approach 2:
The hydraulic oil acts as an intermediary substance that enables compression ratio adjustment. Instead of using multiple mechanical links with varying postures, the hydraulic fluid transmits force through the pressure chamber to achieve smooth, continuous adjustment of the piston rod position relative to the crosshead, simplifying the overall connecting structure
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
Enables the change of compression ratio in a simple structure without stopping the engine, enhancing operational flexibility and reducing maintenance downtime.
Implementation Method 1
a hydraulic pressure adjustment mechanism which supplies hydraulic oil to the hydraulic pressure chamber or discharges the hydraulic oil from the hydraulic pressure chamber and which adjusts an entering position at which the end of the piston rod is inserted into the hydraulic pressure chamber in the stroke direction
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Provided is a crosshead engine that includes: a cylinder; a piston sliding in the cylinder; a piston rod (112a) having one end fixed to the piston; a crosshead (crosshead pin (114a)) connected to the other end side of the piston rod and reciprocating together with the piston; a connecting rod having one end supported by the crosshead; a crankshaft connected to the connecting rod and rotating in coordination with the reciprocation of both the piston and the crosshead; and a variable mechanism varies positions of top and bottom dead centers of the piston by changing a relative position between the piston rod and the crosshead in a stroke direction of the piston. The variable mechanism includes: a hydraulic pressure chamber (168a) which is provided in the crosshead and into which an end of the piston rod is inserted; and a hydraulic pressure adjustment mechanism which supplies hydraulic oil to the hydraulic pressure chamber or discharges the hydraulic oil from the hydraulic pressure chamber and which adjusts an entering position at which the end of the piston rod is inserted into the hydraulic pressure chamber in the stroke direction.