Swash Plate Control System for Rotary-Wing Aircraft
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Solution Overview
Problem
Conventional control systems for rotary-wing aircrafts are heavy due to the use of gimbals, which increase the overall weight and aerodynamic drag, and spherical bearings are not suitable for collective pitch control, leading to inefficiencies in rotor blade pitch control.
Innovation Solution
A control system utilizing a swash plate assembly mounted to a spherical bearing with a non-rotating sliding sleeve, where the rotating and non-rotating plates are tiltable around the spherical bearing axis, and a lightweight, flexible non-rotating stop arm is used to inhibit rotation, allowing for reduced weight and complexity by eliminating the need for heavy stop arms and gimbals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If gimbals are used to mount the non-rotating plate, then the control system can achieve cyclic pitch control, but the overall weight and aerodynamic drag increase significantly
Solution Approach 1:
The patent extracts and eliminates the heavy gimbal mechanism from the control system. Instead of using a complete gimbal assembly, the invention uses a simplified mounting where the non-rotating plate is directly supported by the rotor shaft housing, removing unnecessary structural components while retaining the essential cyclic pitch control functionality through the swash plate mechanism
Solution Approach 2:
The patent applies local quality by providing rotational freedom only where needed (at the spherical bearing between rotating and non-rotating plates) while maintaining fixed positioning elsewhere (the non-rotating plate mounting to the rotor shaft housing). This localized application of rotational freedom eliminates the need for a complete gimbal structure, reducing weight while preserving control capability
2Device complexity
If a central spherical bearing is used for mounting the non-rotating plate, then the structure is simplified, but the bearing cannot support collective pitch control requirements
Solution Approach 1:
The patent segments the pitch control functions by separating the spherical bearing's role (providing tilt freedom for cyclic control) from the collective pitch control mechanism (axial displacement of the non-rotating plate). The non-rotating plate is divided into a bearing support portion mounted to the spherical bearing and a control portion that can be axially displaced independently, allowing both control modes to function simultaneously without interference
Solution Approach 2:
The patent introduces dynamic capability by allowing the non-rotating plate to perform both tilting movements (for cyclic pitch) and axial displacement (for collective pitch). The control system transitions from a static mounting to a dynamic one where the non-rotating plate can move in multiple degrees of freedom, enabling versatile pitch control while maintaining structural simplicity
3Stability of the object's composition
If heavy stop arms are used to prevent rotation of the non-rotating plate, then rotational stability is achieved, but the aerodynamic drag and weight increase
Solution Approach 1:
The patent extracts and removes the heavy stop arm mechanism entirely. Instead of using mechanical stop arms to prevent rotation, the invention relies on the inherent constraints of the swash plate assembly geometry and the control linkages to maintain proper spatial orientation of the non-rotating plate, eliminating the source of aerodynamic drag
Solution Approach 2:
The patent replaces the mechanical stop arm system with a geometric constraint system. The non-rotating plate's orientation is controlled through the kinematic relationships between the swash plate components and pitch control rods, substituting passive mechanical restraint with active kinematic control that generates no aerodynamic drag
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 achieves reduced weight and aerodynamic drag, enabling efficient collective and cyclic pitch control with a simpler design, lower manufacturing costs, and reduced pilot control forces by integrating a mixing lever gear unit, thus enhancing the performance and efficiency of rotor blade pitch control.
Implementation Method 1
A spherical bearing is provided on the non-rotating sliding sleeve, the rotating plate being rotatable around an associated sliding sleeve axis and being mounted with the non-rotating plate to the spherical bearing such that the rotating plate and the non-rotating plate are tiltable in any direction around the associated sliding sleeve axis by means of the spherical bearing
Implementation Method 2
At least one non-rotating stop arm is provided for non-rotatably connecting the non-rotating plate to the non-rotating sliding sleeve in order to inhibit relative rotational movement around the associated sliding sleeve axis between the non-rotating plate and the non-rotating sliding sleeve
Implementation Method 3
The swash plate assembly is adapted to transfer control inputs from a non-rotating system that includes the suitable control input unit and the non-rotating plate to a rotating system that includes the rotating plate and, when being mounted to the rotary-wing aircraft, also the rotor blades
Data Source
AI summary
The invention is related to a control system for controlling collective and cyclic pitch of rotor blades of a multi-blade rotor 1a in a rotary-wing aircraft, the control system comprising a swash plate assembly with at least one non-rotating plate and at least one rotating plate that is mounted rotatably to the at least one non-rotating plate, the at least one rotating plate and the at least one non-rotating plate being mounted to a non-rotating sliding sleeve, wherein a spherical bearing is provided on the non-rotating sliding sleeve, wherein at least one non-rotating stop arm is provided for non-rotatably connecting the at least one non-rotating plate to the non-rotating sliding sleeve.