Variable-Ratio Supercharger Drive for Smooth Engine Torque Delivery
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Solution Overview
Problem
Existing drive arrangements for superchargers in internal combustion engines, particularly in passenger cars and light road vehicles, face inefficiencies due to the use of fixed ratio gear trains, leading to wasted energy and potential torque reduction when accelerating, as they struggle to balance engine torque delivery at varying speeds.
Innovation Solution
A supercharging arrangement utilizing a rolling race type variator with a control system that adjusts the operating ratio and rate of change of the variator to optimize supercharger speed and torque delivery, ensuring efficient engine torque output while minimizing cost, weight, and complexity, by employing a control system that calculates and adjusts the variator ratio based on engine conditions and driver inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed ratio gear train is used to drive the supercharger, then the supercharger operates at a constant speed ratio relative to the engine, but energy is wasted at high engine speeds and torque delivery is insufficient at low engine speeds
Solution Approach 1:
The patent applies a continuously variable transmission (CVT) system that dynamically adjusts the speed ratio between the engine and supercharger based on operating conditions. The variator mechanism allows continuous variation of the transmission ratio, enabling the supercharger speed to be optimally adapted to engine speed across the entire operating range, thereby eliminating energy wastage at high speeds while maintaining sufficient torque delivery at low speeds.
2Productivity
If a variable ratio drive is immediately swept from low to high ratio during sudden acceleration, then the supercharger can deliver maximum torque, but a substantial part of engine torque is consumed to accelerate the supercharger, reducing torque available for vehicle acceleration
Solution Approach 1:
The control system performs preliminary action by predicting the driver's acceleration demand and beginning to adjust the variator ratio in advance. When sudden acceleration is detected, the control system modulates the rate of ratio change to ensure that supercharger torque builds up smoothly without creating excessive inertial loads that would compete with vehicle acceleration torque, thereby optimizing the balance between supercharger performance and vehicle responsiveness.
Solution Approach 2:
The patent employs a control system with feedback mechanisms that continuously monitor engine torque, supercharger speed, and vehicle acceleration demand. This feedback allows the system to adjust the variator ratio rate of change in real-time, preventing the supercharger from consuming excessive torque during transient conditions while ensuring maximum torque delivery when needed, thus resolving the contradiction between supercharger productivity and available power for vehicle acceleration.
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 enables efficient engine torque output at low engine speeds, reduces energy wastage, and maintains smooth torque delivery, preventing transient torque reductions during sudden accelerations, thus enhancing driving performance and reducing emissions.
Implementation Method 1
a plurality of rolling elements (20, 22) disposed between and being in driving engagement with the input and the output surfaces at respective contact regions
Implementation Method 2
each rolling element being free to pivot about a tilt axis, the tilt axis passing through the rolling element perpendicular to the rolling axis, and intersecting the rolling axis at a roller centre, whereby a change in the tilt angle causes a change in the operating ratio of the variator
Data Source
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AI summary
A supercharging arrangement for an internal combustion engine is disclosed. The supercharging arrangement comprises a supercharger having a rotational drive input, and a transmission having a rotational drive input to receive drive from an internal combustion engine, and a rotational drive output connected to the input of the supercharger. The transmission includes a variator operatively connected between the input and the output of the transmission, which variator has an output that is driven at an operating ratio from an input. There is a control system that operates to cause an engine to deliver an amount of torque that is indicated by the state of an input to the control system. The control system is further operative to set the operating ratio of the variator.