Speed-Summing Transmission for Constant-Speed Compressor Modulation
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Solution Overview
Problem
Existing systems require complex and costly variable frequency drivers to modulate the rotational speed of large compressors, which are inefficient and cumbersome, especially in industrial applications where compressors need to operate between 70% and 105% of rated speed.
Innovation Solution
A system comprising a constant-speed driver, a rotating load, and a variable speed transmission with a continuous variable transmission device, which includes a speed summing gear arrangement and a controller to modulate the rotation speed of the load while maintaining the driver's constant speed, using mechanisms like magnetic coupling, hydro viscous drivers, or epicyclic gear trains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a variable frequency driver is used to modulate the rotational speed of large compressors, then the rotational speed can be controlled, but the system becomes complex, costly and cumbersome
Solution Approach 1:
The power transmission is segmented into two separate paths: a main power path that transmits the majority of power directly from the driver to the load, and a speed modulation path that transmits only a fraction of power through a variable speed mechanism. This segmentation allows speed control without requiring the entire power transmission system to be variable speed capable, thereby reducing complexity.
Solution Approach 2:
A variable speed transmission mechanism is introduced as an intermediary component between the constant-speed driver and the load. This intermediary handles only a fraction of the total power (less than 50%, preferably less than 30% or 20%) and is responsible for speed modulation, while the main power flow bypasses it. This allows speed control functionality to be added without making the entire power transmission system complex.
2Ease of operation
If a variable frequency driver is used to modulate the rotational speed of large compressors, then the rotational speed can be controlled, but the cost increases
Solution Approach 1:
By segmenting the power transmission into main and modulation paths, the variable speed mechanism only needs to handle a fraction of the total power. This reduces the size, power rating, and cost of the variable speed transmission component compared to a system where the entire power flow would need to be variable speed capable.
Solution Approach 2:
The variable speed transmission handles only a partial portion of the total power requirement (less than 50%, preferably less than 30% or 20%). This partial action approach allows the use of smaller, less expensive variable speed components while still achieving the required speed modulation capability for the full power load.
3Adaptability or versatility
If a variable frequency driver is used, then speed modulation is achieved, but the system becomes cumbersome
Solution Approach 1:
The system is divided into a compact variable speed transmission unit that handles only speed modulation for a fraction of the power, separate from the main power transmission path. This segmentation allows the variable speed components to be smaller and more compact, reducing the overall system bulk while maintaining full speed modulation capability.
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
Enables efficient modulation of the rotating load's speed without the need for variable frequency drivers, reducing complexity and cost, while maintaining the driver's constant rotational speed, thus improving operational efficiency and flexibility in industrial applications.
Implementation Method 1
The magnetic coupling can be comprised of a circular array of magnets co-acting with an electrically conductive member, wherein eddy currents are generated when the magnets and the electrically conductive member rotate one with respect to the other. The eddy currents co-act with the magnetic field generated by the magnets such that a torque is transmitted from the magnets arrangement to the electrically conductive member or vice-versa.
Implementation Method 2
The eddy currents co-act with the magnetic field generated by the magnets such that a torque is transmitted from the magnets arrangement to the electrically conductive member or vice-versa.
Implementation Method 3
The gaps are filled with a viscous liquid, which transmits by viscous friction the torque from the driving discs to the driven discs.
Data Source
AI summary
The system includes: a driver; a rotating load configured to be driven into rotation by the driver; a controller, for controllably changing a rotation speed of the load; and a variable speed transmission, arranged between the driver and the load. The variable speed transmission includes a speed summing gear arrangement with a first input shaft, a second input shaft and an output shaft. The output shaft is drivingly coupled to the rotating load. The first input shaft is drivingly coupled to the driver. A continuous variable transmission device is mechanically coupled to the driver and to the second input shaft of the speed summing gear arrangement. The continuous variable transmission device is functionally coupled to the controller.