Split-Torque VCR Engine Assembly for Smaller Actuator Loads
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Solution Overview
Problem
Conventional variable compression ratio (VCR) engines require large and expensive actuators with high torque output to adjust compression ratios, leading to high parasitic losses and increased system complexity and cost due to the need for high ratio reducers.
Innovation Solution
A split-torque gearbox is introduced, where one torque path carries a higher amount of torque than the other, allowing the actuator to operate against only a fraction of the total torque, enabling the use of smaller actuators and reducing parasitic losses by utilizing existing engine components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional gearbox is used with a single torque path, then the actuator can adjust the compression ratio, but the actuator must be large and expensive with high torque output requirements
Solution Approach 1:
The patent divides the single torque path into two separate torque paths: a first torque path from the crankshaft to the control shaft through the connecting rod and bell crank, and a second torque path from the actuator to the control shaft through the gearbox. This segmentation allows the actuator to operate against only a fraction of the total torque, reducing the required actuator size and torque output while maintaining the ability to adjust compression ratio.
2Power
If a high ratio reducer is used to couple the actuator to the transfer shaft, then the actuator can provide sufficient torque, but parasitic losses increase and system cost increases
Solution Approach 1:
The patent applies partial action by having the actuator provide only a portion of the total torque required to adjust the compression ratio. The first torque path from the crankshaft provides the remaining torque, so the actuator operates at reduced power levels. This eliminates the need for high ratio reducers and associated parasitic losses while maintaining full compression ratio adjustment capability.
3Adaptability or versatility
If the actuator operates against full torque of the crankshaft, then compression ratio adjustment is achieved, but the actuator size and cost increase
Solution Approach 1:
The patent segments the torque requirements into two paths, allowing the actuator to handle only a fraction of the total torque. The first torque path from the crankshaft handles the majority of the torque through the connecting rod and bell crank mechanism, while the second torque path from the actuator provides the additional torque needed for compression ratio adjustment. This segmentation enables the use of a smaller, lighter actuator while maintaining full adaptability for compression ratio control.
Data Source
AI summary
An engine assembly including a crankshaft, a bell crank pivotally mounted on the crankshaft, the bell crank having a first end and a second end opposite of the first end, a connecting rod connected to the first end of the bell crank, a control shaft, a control link mounted on the control shaft and connected to the second end of the bell crank, a driven gear fixed to the crankshaft, a drive gear fixed to the control shaft, an actuator, and a split-torque gear box splitting the torque from the driven gear between the drive gear via a first torque path and the actuator via a second torque path.