Variable Speed Accelerator Torque Control

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Solution Overview

Problem

The existing variable speed accelerators using a combination of constant-speed and variable-speed motors with planetary gear transmission devices face issues with reverse contact between drive and driven gears, particularly when the load or rotation rate of the compressor changes suddenly, leading to unintended torque direction reversals.

Innovation Solution

Incorporating a sun gear, planetary gear, internal gear, and gear carriers with a rotation rate controller and torque measuring device to manage the speed instruction of the variable-speed motor, ensuring the torque direction is aligned with the normal torque direction, and reducing the rate of change of the speed instruction to prevent reverse contact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the rotation rate of the variable-speed motor is suddenly lowered or the load of the compressor suddenly drops, then the responsiveness and adaptability of the system is improved, but the torque direction of the variable-speed motor reverses causing reverse contact between drive and driven gears

Engineering Contradiction:

Improveresponsiveness to load changesVSAvoidgear contact integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The control device predicts the torque direction based on the current operating state and speed instruction changes before the actual torque reversal occurs. When reverse contact is predicted, the control device restricts further speed instruction changes in advance, preventing the torque reversal and reverse gear contact before they happen.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device continuously monitors the operating state and speed instruction changes, uses this feedback to predict torque direction, and adjusts speed instructions accordingly to prevent torque reversal and reverse gear contact while maintaining system responsiveness.

Inventive Principle:

Principle #23Feedback

2Productivity

If the speed instruction of the variable-speed motor is changed rapidly, then the productivity and response time is improved, but the torque direction reverses leading to reverse contact of gears

Engineering Contradiction:

Improvespeed adjustment rateVSAvoidreverse contact force

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The control device predicts torque direction and potential reverse contact before rapid speed changes are executed. When reverse contact is predicted, the control device restricts further speed instruction changes in advance, preventing the harmful reverse contact force while allowing controlled speed adjustments.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control device uses feedback from operating state and speed instruction changes to predict torque direction, then adjusts speed instructions in real-time to prevent reverse contact, balancing productivity with harm prevention.

Inventive Principle:

Principle #23Feedback

3Reliability

If the torque direction control is added to prevent reverse contact, then the gear reliability is improved, but the device complexity increases due to torque measuring device and control logic

Engineering Contradiction:

Improvegear operation reliabilityVSAvoidcontrol system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control device replaces physical mechanical protection mechanisms with a control-based torque direction prediction system. By using computational prediction and electronic control to prevent reverse contact, the system achieves gear reliability protection without adding complex mechanical safeguard components.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS10663039B2Variable speed accelerator and method for controlling variable speed accelerator

Publication Date: 2020.05.26 MITSUBISHI HEAVY INDUSTIES COMPRESSOR CORP

AI summary

A variable speed accelerator includes: an electric driving device; and a transmission device changing the speed of a rotational driving force generated by the electric driving device and transmits the changed rotation driving force to a driving target. The transmission device includes: a sun gear; a sun gear shaft fixed to the sun gear; a planetary gear that meshes with the sun gear; an internal gear that meshes with the planetary gear; a planetary gear carrier including a planetary gear carrier shaft; and an internal gear carrier including an internal gear carrier shaft. The electric driving device includes: a constant-speed motor including a constant-speed rotor; and a variable-speed motor including a variable-speed rotor. The variable speed accelerator further includes: a rotation rate controller that issues a speed instruction; a torque measuring device; and a control device holding an instruction value of the speed instruction.