Variable Pulley Accessory Drive for Flywheel Energy Transfer
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Solution Overview
Problem
Existing power systems for machines, such as vehicles and construction equipment, face inefficiencies in transferring power to accessories due to the limitations of constant speed ratios in accessory drives, which restrict the ability to adapt to varying operating modes and energy storage/recovery capabilities.
Innovation Solution
A variable drive system that includes a first and second variable pulley mechanically coupled to the engine output and flywheel, respectively, and a clutch system to enable bidirectional power transfer, allowing power to be sourced from either the engine or flywheel based on the machine's operating mode, thereby optimizing energy usage and storage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a constant speed ratio transmission is used to drive accessories, then the structure is simple, but the system cannot adapt to varying operating modes and energy storage/recovery capabilities
Solution Approach 1:
The patent employs a continuously variable transmission (CVT) with variable pulleys instead of a fixed gear ratio transmission. The variable pulleys can dynamically adjust their effective diameters to change the transmission ratio continuously, enabling the system to adapt to different operating modes (engine-driven, flywheel-driven, or hybrid) and optimize performance across varying conditions.
Solution Approach 2:
The drive system is designed to perform multiple functions: it can operate in engine-driven mode, flywheel-driven mode, or hybrid mode where both power sources work together. The CVT mechanism serves as a universal interface that accommodates different power sources and operating conditions, making the system versatile rather than dedicated to a single function.
2Loss of energy
If power is transferred from engine to flywheel for energy storage, then kinetic energy is recovered, but clutch slip and wear increase
Solution Approach 1:
The variable pulley system continuously adjusts the transmission ratio during energy transfer operations. By optimizing the ratio between engine speed and flywheel speed, the system minimizes speed differential across the clutch interface, thereby reducing slip and associated wear while still enabling effective kinetic energy recovery.
Solution Approach 2:
The system changes operational parameters (transmission ratio) dynamically during power transfer. By adjusting the effective diameters of the variable pulleys, the system optimizes the speed relationship between engine and flywheel, reducing clutch slip and wear during energy storage operations.
3Productivity
If a fixed gear ratio is used, then manufacturing is simpler, but the system cannot optimize power transfer for different operating conditions
Solution Approach 1:
The patent replaces fixed gear ratios with a dynamic CVT mechanism that can continuously vary the transmission ratio. This allows the system to optimize power transfer efficiency for different operating conditions (different speeds, loads, and power sources) rather than being constrained to predetermined fixed ratios.
Solution Approach 2:
The system changes the transmission ratio parameter dynamically based on operating conditions. By adjusting the effective diameters of the variable pulleys, the system optimizes the speed and torque relationship between engine and accessories, maximizing power transfer efficiency across varying operating conditions.
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 variable drive system enhances power transfer efficiency by allowing adaptive power sourcing from either the engine or flywheel, improving energy storage and usage, and reducing wear on clutch components by minimizing slip, thus extending their lifespan.
Implementation Method 1
a first variable pulley to be mechanically coupled to the accessory drive and an engine output of an engine; a second variable pulley to be mechanically coupled to a flywheel; and a drive element to rotate, according to a clutch system, about the first variable pulley and the second variable pulley
Implementation Method 2
a flywheel configured to store kinetic energy; a clutch system configured to at least one of: enable, via a first clutch, a transfer of power from the engine output, or enable, via a second clutch, a transfer of power associated with the flywheel
Data Source
AI summary
A variable drive system, to drive an accessory drive of a machine may include a first variable pulley to be mechanically coupled to the accessory drive and an engine output of an engine. The variable drive system may also include a second variable pulley to be mechanically coupled to a flywheel. The variable drive system may include a drive element to rotate, according to a clutch system, about the first variable pulley and the second variable pulley to at least one of: drive the second variable pulley to charge the flywheel with kinetic energy or drive the first variable pulley via kinetic energy from the flywheel.