Heliostat Drive and Multi-Stage Mounting for Low-Backlash Tracking
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Solution Overview
Problem
Heliostat assemblies face challenges in maintaining precise positioning of reflective surfaces due to environmental factors and manufacturing tolerances, leading to undesirable movement and flexing of the reflectors, which affects the efficiency of sunlight redirection in solar thermal power plants.
Innovation Solution
A heliostat system with a drive assembly that includes a shaft connected to a mirror frame, a spur gear, and a worm gear biased by a spring, which reduces backlash to less than one thousandth of a radian, and a multi-stage mounting mechanism to secure the drive assembly to the reflector frame, minimizing deformation and accommodating manufacturing tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If smaller heliostat reflectors are used to improve installation efficiency and reduce manufacturing costs, then more heliostats are required to achieve the same sunlight redirection capacity, but this increases the total number of drive assemblies needed and multiplies installation steps
Solution Approach 1:
The patent divides the drive assembly into modular components: a motor unit, a gear reduction unit with worm gear and spur gear, a shaft, and a mounting bracket. This segmentation allows for standardized mass production of individual modules while maintaining complete functionality when assembled, resolving the contradiction between using multiple smaller heliostats and the increased complexity of managing numerous drive assemblies.
2Manufacturing precision
If manufacturing tolerances are reduced to minimize backlash and improve positioning precision, then positioning accuracy improves, but manufacturing costs increase significantly
Solution Approach 1:
The patent introduces a spring-loaded mechanism as an intermediary element between the worm gear and spur gear. This spring applies controlled pressure to eliminate backlash without requiring ultra-precise gear manufacturing tolerances. The spring acts as a mediator that compensates for manufacturing variations, achieving high positioning accuracy while maintaining economical manufacturing standards.
Solution Approach 2:
The patent changes the operational parameters of the gear system by introducing a variable spring pressure mechanism. Instead of relying solely on tight manufacturing tolerances, the system adjusts the contact pressure between gears dynamically, allowing for standard manufacturing tolerances while maintaining precise positioning through controlled parameter adjustment during operation.
3Weight of moving object
If the reflector is made thinner to reduce weight and simplify installation, then installation becomes easier, but the reflector becomes more flexible and prone to unwanted movement under environmental loads
Solution Approach 1:
The patent introduces a rigid frame structure as an intermediary support system between the thin reflector surface and the drive assembly mounting points. This frame provides the necessary structural rigidity to prevent unwanted reflector movement under wind and operational loads, while allowing the reflector itself to remain thin and lightweight for easier installation.
Solution Approach 2:
The patent employs a composite structure combining the thin reflector material (for light weight) with a rigid frame material (for structural stability). This composite approach allows each component to fulfill its optimal function: the thin reflector for weight reduction and the rigid frame for maintaining positional stability under environmental loads.
4Strength
If bolts are tightened to secure the drive assembly to the reflector frame, then connection strength improves, but this causes the frame and reflector to flex and deform
Solution Approach 1:
The patent segments the connection system into multiple distributed mounting points around the reflector perimeter rather than concentrating fastening forces at a single location. This distribution of connection points reduces localized stress and prevents frame deformation while maintaining overall connection strength. The segmented approach allows the rigid frame to support the mounting brackets without causing reflector surface distortion.
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 enables precise and controlled positioning of the reflector surfaces, reducing the impact of environmental loads and manufacturing tolerances, thereby enhancing the efficiency of sunlight redirection and simplifying the installation process while maintaining cost-effectiveness.
Implementation Method 1
the backlash between the worm and the spur reduced to less than one thousandth of a radian in spur rotation
Implementation Method 2
To provide support for the reflector and reduce flexing, a frame is attached to the back side of the reflector
Implementation Method 3
a drive assembly configured to rotate the reflector assembly with respect to the ground mount about a predetermined angular range
Implementation Method 4
a shaft connected to the drive assembly, wherein the drive assembly is configured to rotate the shaft about a longitudinal axis of rotation
Data Source
AI summary
A comprising a ground mount, a reflector assembly comprising a mirror and a frame rigidly connected to the mirror, a drive assembly configured to rotate the reflector assembly with respect to the ground mount about a predetermined angular range, and a mounting mechanism configured to connect the drive assembly to the reflector assembly and comprising a shaft connected to the drive assembly, where the drive assembly is configured to rotate the shaft about a longitudinal axis of rotation, an attachment for connecting the frame to the shaft at a fixed angle about the longitudinal axis; and a clamp for connecting the shaft to the frame.