Variable Speed Accessory Drive Radial Pulley Adjustment
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Solution Overview
Problem
Vehicle engine accessories experience energy losses due to operating at higher rotational speeds than optimal, as they are designed for idling speeds, leading to inefficiencies when rotational speed of the crankshaft increases.
Innovation Solution
A variable speed drive mechanism with a shaft, fixed disk, and moveable disk featuring a spiral groove, allowing pulley segments to adjust radially and maintain optimal rotational speed for accessories by changing pulley diameter, coupled with an adjustable tensioner to maintain constant tension in the endless rotatable device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the rotational speed of the crankshaft increases, then the power output of the engine increases, but the rotational speed of the accessories increases leading to increased energy losses
Solution Approach 1:
The patent applies the dynamics principle by making the pulley diameter variable rather than fixed. The pulley segments can move radially to change the effective diameter of the drive pulley, allowing the system to dynamically adjust the speed ratio between the crankshaft and accessories. This enables the accessories to operate at optimal speeds even when the engine operates at higher power levels.
Solution Approach 2:
The patent changes the physical parameter of pulley diameter from a fixed value to a variable parameter. By adjusting the diameter of the drive pulley through radial movement of pulley segments, the system can modify the transmission ratio to maintain optimal accessory speeds across different engine operating conditions, thereby reducing energy losses.
2Loss of energy
If the pulley diameter is changed to maintain optimal accessory speed, then energy efficiency improves, but the complexity of the drive mechanism increases
Solution Approach 1:
The patent divides the pulley into multiple segments that can move independently relative to each other. These pulley segments are arranged around the circumference of the pulley and can be positioned radially to change the effective diameter. This segmentation allows for relatively simple adjustment mechanisms compared to completely redesigning the pulley structure.
Solution Approach 2:
The pulley segments are nested within the pulley structure, with each segment capable of radial movement while remaining contained within the overall pulley assembly. This nesting approach allows the variable diameter functionality to be integrated into the existing pulley design without requiring external adjustment mechanisms, thereby limiting the increase in device complexity.
Data Source
AI summary
A variable speed drive mechanism includes a fixed disk concentric with, attached to, and rotatable with a shaft about a central axis. A plurality of pulley segments are supported by the fixed disk, and are moveable relative to the fixed disk in a radial direction relative to the central axis. A moveable disk is concentric with the shaft, and is rotatably moveable about the shaft relative to the fixed disk. The moveable disk defines a spiral groove having a center concentric with the shaft. The pulley segments include a guided groove portion engaged with and moveable along the spiral groove. Rotation of the moveable disk relative to the fixed disk rotates the spiral groove about the central axis relative to the pulley segments, thereby moving the guided groove portions along the spiral groove to move the pulley segments radially relative to the central axis.