Variable Compression Device Piston Rod Regulation
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Solution Overview
Problem
The existing adjustment mechanisms in large reciprocating piston combustion engines experience unintended fluctuations in compression ratio due to elastic compression of hydraulic oil and inertia forces, leading to potential engine performance deterioration and sealing issues.
Innovation Solution
A variable compression device with a regulation member that includes a movable pin or supporting portion to regulate the piston rod's movement, ensuring consistent compression ratio by supporting the piston rod from above or below, thereby preventing unintended changes in compression ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the piston rod is lifted using oil pressure to increase compression ratio, then the compression ratio can be adjusted, but the hydraulic oil is elastically compressed by combustion pressure causing instantaneous decrease in compression ratio
Solution Approach 1:
A regulation member (regulation pin or supporting portion) is introduced as an intermediary mechanical element between the piston rod and the hydraulic system. This regulation member physically constrains the piston rod's position, mediating between the hydraulic pressure forces and the piston rod movement, thereby preventing unwanted fluctuations caused by oil elasticity while still allowing controlled compression ratio adjustment.
Solution Approach 2:
The regulation member applies a preliminary counteracting force to the piston rod before unwanted movement can occur. By positioning the regulation member to abut or support the piston rod at critical points, it preemptively prevents the instantaneous decrease in compression ratio that would otherwise result from hydraulic oil elastic compression during combustion.
2Adaptability or versatility
If the piston rod is lowered without sufficient combustion chamber pressure increase, then the compression ratio can be decreased, but inertia force of the piston rod causes unintended increase in compression ratio
Solution Approach 1:
The regulation member serves as a mechanical intermediary that decouples the piston rod movement from direct hydraulic control during the lowering phase. By providing physical support or constraint, it ensures that the piston rod follows the intended movement path without being influenced by inertia forces, thereby improving control reliability.
Solution Approach 2:
The regulation member provides beforehand cushioning support to the piston rod during compression ratio decrease operations. This support acts as a mechanical cushion that absorbs or counteracts inertia forces before they can cause unintended compression ratio increases, ensuring smoother and more reliable control.
3Adaptability or versatility
If hydraulic oil is used to move the piston rod, then compression ratio can be changed, but combustion pressure transmitted to hydraulic oil causes elastic compression and compression ratio fluctuation
Solution Approach 1:
The regulation member introduces a mechanical intermediary layer between the hydraulic oil and the piston rod. This intermediary physically supports the piston rod, isolating it from the elastic compression effects of the hydraulic oil during combustion pressure cycles, thereby making compression ratio maintenance easier and more stable.
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 solution effectively maintains a stable compression ratio, preventing engine performance deterioration and sealing issues by regulating the piston rod's movement during changes in compression ratio, ensuring consistent engine operation.
Implementation Method 1
a combustion pressure transmitted from a combustion chamber is applied to hydraulic oil, and thus the hydraulic oil is elastically compressed
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A variable compression device includes a piston rod (6), a connection member (7a) which is connected to the piston rod, a fluid chamber (R3) which is provided between the connection member and the piston rod and is configured to move the piston rod, in a direction in which a compression ratio is increased, with respect to the connection member by supplying a boosted working fluid thereto, and a regulation member (15) which is capable of abutting and being separated from the piston rod, and when the piston rod is moved in a direction in which a compression ratio is increased, abuts the piston rod to regulate movement of the piston rod such that a compression ratio is maintained