Helical Gear Speed Reducer Torque Response

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Solution Overview

Problem

The existing two-shaft gas turbine power generation equipment experiences reduced responsiveness in torque transmission due to backlash in speed reducers with spur gears, particularly when the direction of torque transmission between the motor and compressor changes, which is a challenge in meeting sudden changes in demand output.

Innovation Solution

The use of helical gears in the speed reducer minimizes the delay in torque transmission by ensuring point contact between gears, reducing the time for compressor-side and motor-side gears to mesh when the torque direction changes, and includes a diaphragm coupling to absorb displacement and thermal expansion, allowing for efficient power management between the induction motor and power system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If spur gears are used in the speed reducer, then the structure is simple and easy to manufacture, but the responsiveness of torque transmission is reduced due to backlash when the direction of torque transmission changes

Engineering Contradiction:

Improveease of manufactureVSAvoidresponsiveness of torque transmission

Core Design Contradiction:

Ease of manufactureVSSpeed

Solution Approach 1:

The patent changes the gear type parameter from spur gears to helical gears. This parameter change eliminates the backlash problem inherent in spur gears while maintaining the speed reducer's functionality. Helical gears provide continuous tooth contact and smoother torque transmission, thereby improving responsiveness without significantly complicating the manufacturing process.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent inverts the conventional approach by using helical gears instead of the more common spur gears in speed reducers. This inversion of the gear type selection resolves the backlash issue that plagues conventional designs, particularly when torque transmission direction changes, while still maintaining manufacturing feasibility.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If the rotational speed of the motor is reduced using a speed reducer, then a general-purpose motor can be used and equipment costs are reduced, but the responsiveness to sudden changes in demand output is degraded due to backlash

Engineering Contradiction:

Improveadaptability of motorVSAvoidresponsiveness to demand output changes

Core Design Contradiction:

Adaptability or versatilityVSSpeed

Solution Approach 1:

The patent changes the gear type parameter from spur gears to helical gears in the speed reducer. This eliminates backlash while maintaining the speed reduction functionality, allowing general-purpose motors to be used without sacrificing responsiveness to sudden demand output changes.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the direction of torque transmission between the motor and compressor changes, then the motor can accommodate sudden changes in demand output, but the torque transmission is delayed due to backlash in the speed reducer

Engineering Contradiction:

Improveability to accommodate demand output changesVSAvoiddelay of torque transmission

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent changes the gear type from spur gears to helical gears, which eliminates backlash. This allows the motor to accommodate sudden changes in demand output without experiencing torque transmission delays, as helical gears maintain continuous contact and eliminate the play present in spur gear systems.

Inventive Principle:

Principle #35Parameter changes

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

This solution minimizes the delay in torque transmission when the torque direction changes and suppresses the allowable maximum rotational speed required for the motor, enhancing responsiveness to demand output changes while reducing equipment costs by using standard motors.

Implementation Method 1

a first compressor-side helical gear (43) that is mounted on the compressor-side shaft (41) and is rotated integrally with the compressor-side shaft (41); a first motor-side helical gear (45) that is mounted on the motor-side shaft (42), is rotated integrally with the motor-side shaft (42), and meshes with the first compressor-side helical gear (43)

Methodology Applied

Scientific EffectHelical gear meshing: Gear

Implementation Method 2

includes a diaphragm coupling to absorb displacement and thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 3

a diaphragm coupling to absorb displacement and thermal expansion

Methodology Applied

Scientific EffectElastic deformation: Elasticity

Data Source

PatentUS11181045B2Two-shaft gas turbine power generation equipment

Publication Date: 2021.11.23 MITSUBISHI POWER LTD

AI summary

Provided is a two-shaft gas turbine power generation equipment that includes: an induction motor which receives/transmits power from/to a power system; and a speed reducer that makes a rotational speed of a motor rotor of the induction motor lower than a rotational speed of a compressor rotor of a two-shaft gas turbine. The speed reducer includes: a compressor-side shaft; a motor-side shaft; a first compressor-side helical gear and a second compressor-side helical gear which are mounted on the compressor-side shaft; and a first motor-side helical gear and a second motor-side helical gear which are mounted on the motor-side shaft. The first compressor-side helical gear meshes with the first motor-side helical gear, and the second compressor-side helical gear meshes with the second motor-side helical gear.