Cranktrain Phase Adjuster Using Ball Splines for VCR Control
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Solution Overview
Problem
Current systems for adjusting the compression ratio in internal combustion engines are either costly, high in friction, or lack control, making them inefficient and unreliable for achieving variable compression ratios.
Innovation Solution
A phase adjuster assembly that includes an input gear connected to an input shaft via a ball spline interface, a piston plate with spiral bidirectional raceways, and an output gear with matching raceways, allowing for axial movement and rotational locking, assisted by hydraulic pressure to adjust the phase between the input and output gears, enabling a variable compression ratio with reduced friction and improved control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional compression ratio adjustment systems are used, then compression ratio can be varied, but the systems are costly, high in friction, and lack control
Solution Approach 1:
The patent replaces conventional complex mechanical adjustment systems with a ball spline mechanism that uses hydraulic pressure to achieve phase adjustment. The ball spline interface between the input shaft and piston plate provides controlled axial movement with reduced friction, eliminating the need for complex mechanical linkages and improving reliability while reducing overall system complexity.
Solution Approach 2:
The patent uses hydraulic pressure from an oil control valve to assist in axially displacing the piston plate, enabling precise control of the phase adjustment mechanism. This hydraulic assistance provides smooth, controlled movement with minimal friction, directly addressing the control and friction issues in conventional systems.
2Ease of operation
If conventional phase adjusters are used, then phase adjustment is possible, but friction is high and control is poor
Solution Approach 1:
The ball spline mechanism replaces high-friction mechanical sliding interfaces with rolling element contacts. The ball spline interface allows axial movement of the input shaft relative to the piston plate while maintaining rotational coupling, significantly reducing friction and improving ease of operation through smoother, more controlled movement.
Solution Approach 2:
Hydraulic pressure from the oil control valve assists in moving the piston plate axially, providing precise control with minimal applied force. This hydraulic assistance reduces the effort required for phase adjustment and eliminates binding or sticking that would increase friction in purely mechanical systems.
3Adaptability or versatility
If existing VCR mechanisms are implemented, then variable compression ratio is achieved, but the profile is high and cost is increased
Solution Approach 1:
The phase adjuster assembly integrates multiple functions into a single compact unit: the ball spline provides both rotational coupling and axial movement, the piston plate serves as both a structural component and a phase adjustment element, and the spiral raceways enable controlled movement in both directions. This multi-functionality reduces the number of separate components needed, lowering manufacturing cost and simplifying assembly.
Solution Approach 2:
The ball spline mechanism is nested within the piston plate assembly, with the input shaft passing through the piston plate. The spiral raceways are integrated into the piston plate and output gear structures. This nested arrangement creates a compact, low-profile design that reduces material usage and manufacturing complexity, directly addressing cost concerns.
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 provides a cost-effective, reliable, and low-friction mechanism for adjusting the compression ratio by up to 70 degrees, enhancing engine efficiency and fuel consumption while maintaining control over the phasing process.
Implementation Method 1
The ball spline can be configured to rotationally lock the input gear to the input shaft while facilitating relative axial movement between the input gear and the input shaft
Implementation Method 2
The piston plate is moved axially by engine torque and assisted by hydraulic pressure from an oil control valve
Implementation Method 3
The output gear, the piston plate, and the ramp ring can each include a spiral bi-directional raceway with balls disposed therebetween to facilitate phasing of the input gear relative to the output gear via axial movement of the piston plate
Data Source
AI summary
A phase adjuster assembly is disclosed that includes an input gear connected to an input shaft via an interface assembly configured to provide both axial movement and rotational locking between the input gear and the input shaft. A piston plate is connected to the input shaft, and the piston plate defines at least one inner spiral bidirectional raceway. An output gear is configured to be driven by the input shaft, and the output gear at least partially defines at least one outer spiral bidirectional raceway. At least one first rolling element is arranged between the at least one inner bidirectional raceway and the at least one outer spiral bidirectional raceway. Axial movement of the piston plate adjusts a phase between the input gear and the output gear. The input shaft is configured to be axially displaced via axial movement of the piston plate.