Deployable Shock Strut with Motor-Driven Lead Screw
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Solution Overview
Problem
Aircraft and hyperloop vehicles face challenges in efficiently utilizing limited space for deployable wheel systems and landing gear, as existing shock strut systems either diminish shock absorption functionality when shortened for stowage or require complex mechanisms that compress the shock absorber, leading to stress and reduced fatigue life.
Innovation Solution
A deployable shock absorbing strut system with a pivotably mounted housing, a motor-driven shaft, and a geared nut mechanism that allows axial movement of the cylinder within the housing, maintaining shock absorption characteristics while adjusting length without compressing the shock absorber, using a trapezoidal thread and supported by bearing assemblies for radial and thrust motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the shock strut is compressed or shortened for stowage, then the landing gear can be stored in limited space, but the shock absorption functionality is diminished and fatigue life is reduced
Solution Approach 1:
The shock strut system is segmented into two independent functions: the shock absorber (cylinder and piston) that maintains shock absorption capability, and the lead screw mechanism that adjusts the effective length. By separating the shock absorption function from the length adjustment function, the invention allows the strut to be shortened for stowage while keeping the shock absorber intact and functional, thus resolving the contradiction between compact stowage volume and maintained reliability/fatigue life.
2Length of moving object
If the middle portion of the shock absorber is used for lead screw engagement, then the strut length can be adjusted, but the shock absorbing and energy dissipation functionality is reduced
Solution Approach 1:
The lead screw is nested within the center channel of the shock absorber cylinder, allowing the length adjustment mechanism to be housed within the existing shock absorber structure without compromising its shock absorption functionality. The nut is positioned at the top end of the cylinder and engages the lead screw, enabling length adjustment while keeping the middle portion of the shock absorber available for its primary function.
3Length of moving object
If a dedicated center channel is used for lead screw engagement, then the strut can be adjusted in length, but the middle portion is not available for shock absorbing, diminishing functionality
Solution Approach 1:
The center channel of the shock absorber cylinder serves multiple functions: it provides the structural pathway for the lead screw to enable length adjustment, and simultaneously maintains the integrity of the shock absorption system. The nut positioned at the top end engages the lead screw while allowing the middle portion of the cylinder to remain available for shock absorbing and energy dissipation, thus achieving multi-functionality without increasing overall structural complexity.
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 system provides a compact, integrated, and electrically controllable length adjustment of the shock strut, maintaining shock absorption performance, increasing fatigue life, and avoiding stress associated with compression, while allowing active length adjustment during vehicle operation.
Implementation Method 1
A motor is fixed to the motor mount and configured to controllably drive a shaft and a pinion gear mounted on the shaft
Implementation Method 2
A shock absorber includes a cylinder with an external screw thread that extends through the housing through channel... A geared nut threadably engages the cylinder screw thread... The motor is configured to rotate the geared nut such that the cylinder moves axially with respect to the housing
Implementation Method 3
Upper and lower bearing assemblies rotatably support the geared nut in the housing
Implementation Method 4
An oleo strut (oleo-pneumatic shock absorbing strut) converts kinetic energy into heat by the use of a gas, providing elastic spring characteristics, and oil for dampening
Implementation Method 5
An oleo strut (oleo-pneumatic shock absorbing strut) converts kinetic energy into heat by the use of a gas, providing elastic spring characteristics, and oil for dampening
Data Source
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AI summary
A shock strut (100) for a vehicle includes a housing (130) with a through channel (131) and a motor mount (134), and a motor (150) fixed to the housing (130). The cylinder (106) of a shock strut (100) is configured to define a lead screw (107) on its outer surface. The cylinder (106) extends through the housing (130). The piston (104) of the shock strut (100) is attached to a ground engaging assembly (110). A gear nut (140) rotatably mounted in the housing (130) threadably engages the threaded cylinder (106), and is configured to be driven by the motor (150). The housing (130) is attached to the vehicle, and the gear nut (140) is controllably rotated to extend and retract the shock strut (100). A sensor (155) provided on the assembly monitors the position of the shock strut (100). A torsion link assembly (120) reacts rotational forces on the cylinder (106).