Fluid-Controlled Crankshaft for Fast Variable Compression Response
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Solution Overview
Problem
Existing variable compression ratio engine technologies face challenges with complex and expensive mechanical control methods, significant acoustic emissions, rapid wear, high inertia, and sensitivity to engine speed due to hydraulic control systems, particularly in controlling connecting rod length adjustments.
Innovation Solution
A crankshaft with a fluidic control circuit that allows the control element to move translationally along the longitudinal axis, independent of the lubrication circuit, enabling continuous contact with the connecting rod adjustment actuator regardless of crankshaft angular position, using a gas or liquid fluid to reduce inertia and allow pressure and vacuum control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical control by impact is used to control connecting rod length, then the control response is fast, but the manufacturing complexity and cost increase significantly due to extremely precise positioning requirements
Solution Approach 1:
The patent replaces the mechanical impact-based control system with a hydraulic control system. Instead of using mechanical impact to actuate the control element, hydraulic pressure is applied to a piston that moves the control element axially. This substitution eliminates the need for extremely precise mechanical positioning while maintaining fast control response, as the hydraulic system can rapidly build and release pressure to move the control element.
Solution Approach 2:
The patent employs a hydraulic circuit to control the axial position of the control element. A piston subjected to variable hydraulic pressure moves the control element along the crankshaft axis, enabling precise and rapid control of the connecting rod length adjustment actuator without the mechanical complexity and positioning precision requirements of impact-based mechanical control.
2Adaptability or versatility
If hydraulic control through the lubrication circuit is used, then the control system is integrated, but the control inertia increases due to the large volume of the lubrication circuit
Solution Approach 1:
The patent segments the hydraulic control system from the main engine lubrication circuit. Instead of using the entire lubrication circuit volume for control, a dedicated, small-volume hydraulic circuit is created specifically for controlling the connecting rod length. This segmentation allows the control system to respond rapidly without being constrained by the large inertia of the full lubrication system, while still achieving integration with the engine's existing hydraulic infrastructure.
3Device complexity
If hydraulic control through the lubrication circuit is used, then the system is simplified, but the sensitivity to engine speed increases due to the inertia of oil columns driven by the rotating crankshaft
Solution Approach 1:
The patent introduces a control element with a piston as an intermediary between the hydraulic pressure source and the connecting rod length adjustment actuator. This intermediary isolates the control system from the rotational dynamics of the crankshaft, preventing the inertia of rotating oil columns from directly affecting control stability. The piston translates hydraulic pressure changes into controlled axial movement, filtering out the destabilizing effects of engine speed variations.
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 solution reduces control inertia, eliminates impact-based control issues, and allows for selective cylinder-to-cylinder control, improving the precision and durability of variable compression ratio engine operations while minimizing acoustic emissions and wear.
Implementation Method 1
The fluidic control circuit is configured to move the control element along the longitudinal axis
Implementation Method 2
using a gas or liquid fluid to reduce inertia and allow pressure and vacuum control
Data Source
AI summary
A crankshaft for a controlled variable compression ratio engine has an axis of rotation defining a longitudinal axis and comprises at least one crank pin, at least one journal connected by a connecting web, and at least one control element able to move translationally along the longitudinal axis in order to cooperate with an actuator of a system for adjusting the length of a connecting rod. The crankshaft is notable in that the control element, positioned at the connecting arm, comprises an annular part coaxial with the crank pin and capable of establishing continuous contact with the actuator of the system for adjusting the length of the connecting rod, regardless of the angular position of the crankshaft. The crankshaft comprises a fluidic control circuit for moving the control element along the longitudinal axis.