Aircraft PDU Shock Absorber Assembly for Torque Energy Dissipation
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Solution Overview
Problem
Existing shock absorber systems for power drive units in aircraft are costly and heavy due to the use of numerous parts, such as ring springs, which add weight and expense while being inefficient in absorbing shocks during mechanical malfunctions.
Innovation Solution
A shock absorber assembly featuring a bull gear sandwiched between two hubs with brake lining and helical springs, allowing the bull gear to rotate independently and dissipate torque energy during malfunctions, reducing the need for multiple shock absorbers and minimizing part count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ring springs are used in shock absorbers, then shock absorption capability is provided, but weight and cost increase significantly
Solution Approach 1:
The patent combines the shock absorption function with the torque brake assembly by integrating the spring mechanism into the existing brake structure. The spring is positioned within the torque brake housing and works in conjunction with the brake plates, eliminating the need for separate shock absorber components and reducing overall weight while maintaining shock absorption capability.
Solution Approach 2:
The torque brake assembly is designed to perform multiple functions: torque limitation, shock absorption, and kinetic energy dissipation. The spring mechanism within the torque brake provides shock absorption during normal operation, while the brake plates engage to limit torque during malfunctions, creating a multi-functional component that reduces weight by eliminating dedicated shock absorbers.
2Reliability
If multiple shock absorbers are used at each torque brake, then shock absorption is improved, but device complexity and part count increase
Solution Approach 1:
The patent merges the shock absorption function into the torque brake assembly itself. A single spring mechanism is integrated within the torque brake housing, eliminating the need for separate shock absorber components. This integration reduces part count while maintaining the required shock absorption function through the coordinated action of the spring and brake plates.
3Strength
If the distance between motor and torque brake is reduced, then drive line stiffness increases, but kinetic torque magnitude increases
Solution Approach 1:
The spring mechanism within the torque brake assembly provides beforehand cushioning for kinetic energy absorption. When the motor rotor decelerates and generates kinetic torque, the spring compresses to absorb the energy before it can cause damage. This cushioning effect allows the drive line to maintain stiffness while protecting against excessive kinetic torque forces.
Solution Approach 2:
The patent converts the harmful kinetic torque into beneficial spring compression. The spring mechanism captures the kinetic energy from the motor rotor deceleration and transforms it into elastic potential energy through compression. This conversion protects the drive line from damage while utilizing the kinetic energy in a controlled manner.
4Loss of energy
If brake lining material is selected for high friction, then torque energy dissipation is improved, but heat generation increases
Solution Approach 1:
The spring mechanism provides continuous torque absorption and energy dissipation through compression and expansion cycles. Rather than relying solely on friction-based brake lining that generates heat during intermittent engagement, the spring continuously absorbs and dissipates torque energy through elastic deformation, reducing peak heat generation while maintaining effective torque limitation.
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 efficient shock absorption with reduced weight and cost, preventing dynamic instability and effectively managing torque energy during mechanical malfunctions, thereby protecting PDU components.
Implementation Method 1
brake lining secured to one or more of the first hub, the second hub, and the bull gear. The brake lining provides a frictional interface between the bull gear and the first and/or second hubs. The brake lining provides a coefficient of friction that causes the bull gear to rotate along with the first and second hubs during normal operation of the PDU. The brake lining dissipates at least a portion of torque energy during the mechanical malfunction.
Implementation Method 2
Each of the first hub, the second hub, and the bull gear may include a plurality of channels. The channels of the first hub align with the channels of the second hub and those of the bull gear. The channels retain force-resisting elements that are configured to dissipate at least a portion of torque energy during the mechanical malfunction. For example, the force-resisting elements may be or include helical springs.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A shock absorber assembly is configured to be operatively connected to a drive shaft of a power drive unit (PDU) of an aircraft. The shock absorber assembly may include a first hub, a second hub, and a bull gear having at least a portion sandwiched between the first and second hubs. The bull gear is configured to rotate independently of the first and second hubs a controlled distance in response to a mechanical malfunction of the PDU. (Fig. 2)