Self-Erecting Cargo Drive Unit Traction via Cog Belt
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Solution Overview
Problem
Existing self-erecting power drive units in cargo carriers suffer from limited traction due to small contact area between rollers and cargo/pallets, and this issue is exacerbated by moisture, leading to reduced force and movement efficiency.
Innovation Solution
A self-erecting power drive unit with a directional drive motor, auto-braking, and a toothed drive sprocket that engages a cog belt, providing a larger contact area with the cargo/pallet and incorporating a rugged, simple design for enhanced traction, especially in moist conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a roller contact mechanism is used in self-erecting power drive units, then the device can be self-erecting and simple in structure, but the contact area with cargo is small leading to limited traction
Solution Approach 1:
The patent transitions from point/line contact (roller) to surface contact (flat plate), effectively adding a dimensional aspect to the contact interface. The flat plate contact surface engages with the cargo over a broad area, transforming the contact geometry from one-dimensional (roller circumference) to two-dimensional (plate surface), thereby significantly increasing friction and traction capability while preserving the self-erecting mechanism's simplicity
2Device complexity
If a roller contact mechanism is used, then the device structure remains simple, but traction is reduced when moisture is present on contacting surfaces
Solution Approach 1:
By expanding the contact interface from a narrow roller surface to a broad flat plate, the patent creates a larger surface area that distributes moisture effects. The increased dimensional footprint of the contact surface reduces the impact of localized moisture contamination, maintaining more consistent friction coefficients and traction reliability in humid or wet cargo hold environments
3Force
If the contact area between power drive unit and cargo is increased, then traction is improved, but the device complexity increases
Solution Approach 1:
The patent segments the power drive unit into distinct functional components: the self-erecting mechanism (hinges and springs), the drive mechanism (motor, sprocket, chain), and the contact surface (flat plate). This segmentation allows each component to be optimized independently, with the flat plate serving solely as a traction surface without requiring complex internal structures, thus achieving large contact area with minimal added complexity
Solution Approach 2:
The flat plate contact surface extends in the horizontal plane perpendicular to the direction of motion, utilizing unused spatial dimensions. This dimensional expansion provides large contact area without increasing the vertical profile or requiring additional mechanical complexity, as the plate simply spreads out laterally to engage the cargo bottom surface
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 significantly increases traction and reduces traction loss in moist environments, enabling more efficient cargo handling by expanding the contact area and using a robust design for reliable operation.
Implementation Method 1
a directional drive motor with auto-braking
Implementation Method 2
toothed drive sprocket that engages the cogs of the cog belt
Implementation Method 3
directional drive motor with auto-braking
Data Source
AI summary
This disclosed Self-Erecting Cargo Handling Power Drive Unit (PDU) assembly is one of several such units installed in the load area of a cargo carrier at the below floor level for the propose of facilitating cargo movement in either forward or aft direction and is intended for larger individual pieces or cargo loaded on pallet. This self-erecting power drive unit (PDU) consists primarily of a mounting base unit, reversible drive motor with self-activating brake and toothed drive sprocket assembly, hinged drive motor mount, cog (toothed) belt with teeth on one side and a smooth side opposite, idler pulleys and pivot arms for the flanged idler pulleys. The reversible drive motor with self-activating brake and toothed drive sprocket assembly power the cog belt and many be operated in either forward or aft direction by selectively energizing the reversible drive motor. The reversible drive motor and toothed drive sprocket are assembled to the motor mount which is double hinged transversely to the power drive unit mounting base unit with the axes of both hinges parallel to the motor and toothed sprocket center line and displaced to either side and downward to form a triangular configuration. This double hinge is configured such that only one side will disengage at a time during operation, which permits the drive motor and toothed drive sprocket to rotate in either direction in an upward arc and around the engaged side of the hinge.Displaced laterally, one on either side of the reversible drive motor and toothed drive sprocket, are smooth idler pulleys with their axes of rotation parallel to that of the reversible rive motor and toothed drive sprocket. The idler pulleys are mounted between pivot arms that extend laterally along the power drive unit assembly. The ends of the pivot arms opposite the idler pulleys are moveably fastened to the power drive unit mounting base and are free to rotate in vertical arc around this axis. The idler pulleys are provided with a slight resistance to rotation, which results in a small torque load on the reversible drive motor. This generates a reaction about either of the motor mount hinge axes depending upon the direction of reversible drive motor rotation. This reaction drives the motor and toothed drive sprocket assembly in an upward arc about the engaged side of the motor mount hinge, which deploys the power drive unit.A cog belt of nominal width operates over the toothed drive sprocket with the cogs engaging teeth on the toothed drive sprocket and with the smooth side of the cog belt engaging the idler pulleys. The cog belt provides the tractive force to the cargo or cargo pallets, with the cogs engaging the bottom side of the cargo or cargo pallets. As the reversible drive motor is energized in either direction the upward arc of the reversible drive motor and toothed drive sprocket assembly moves the toothed drive sprocket toward the flanged idler pulley at the end of the power drive unit which is toward the direction of cargo or pallet travel. As this movement occurs, the flanged idler pulley rotates about the axis of the connected pivot arms and pushes the cog belt upward into contact with the lower side of the cargo or cargo pallet. This provides the self-erecting feature of this power drive unit. Because the reversible drive motor and toothed drive sprocket assembly operate in an upward arc, this assembly will first approach the idler pulley located at the end of the power drive unit which is toward the direction of cargo or cargo pallet travel. This reduces the shock of power drive unit and cargo or cargo pallet initial contact. The trailing end idler then moves upward as upward force from the toothed drive sprocket is maintained. The upward arc of the motor and drive sprocket in the direction of cargo movement produces greater upward force and traction from the power drive unit to the cargo or cargo pallet as the difficulty in moving the cargo increases. The power drive unit will remain deployed as the reversible drive motor with self-activating brake is de-energized. This will hold the cargo or cargo pallet in position to reduce the incidence of inadvertent motion. The cog belt will retract to below the cargo carrier floor level by momentarily reversing the drive motor to the retracted position prior to de-energizing the reversible drive motor. Prior art is already aware of circuitry to accomplish drive motor braking and control modes of operation.