Screw compressor

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Solution Overview

Problem

Existing screw compressors with a gate rotor rotating at an angle greater than 180° face limitations in controlling rotational speed, leading to high compression loss and inefficiencies in refrigerant handling, particularly when unloading compressed refrigerant back to the suction side.

Innovation Solution

A screw compressor design featuring a screw rotor with adjustable rotational speed via an inverter circuit, combined with a gate rotor having a teeth-to-screw grooves ratio greater than or equal to 2.5, allowing for higher rotational speeds and optimized compression strokes from start to completion, reducing leakage and pressure loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the screw rotor rotates at a fixed speed controlled by unloading, then the capacity is controlled, but compression loss increases and operational efficiency decreases

Engineering Contradiction:

Improvecompression lossVSAvoidoperational efficiency

Core Design Contradiction:

Loss of energyVSProductivity

Solution Approach 1:

The patent applies dynamics by transitioning from fixed-speed rotation controlled by unloading to variable-speed rotation controlled by a speed adjuster. The screw rotor's rotational speed can be dynamically adjusted according to actual operating conditions, eliminating the need to unload compressed refrigerant and thereby reducing compression loss while maintaining optimal operational efficiency across varying loads.

Inventive Principle:

Principle #15Dynamics

2Loss of energy

If the gate rotor has a teeth-to-screw grooves ratio greater than or equal to 2.5, then leakage and pressure loss are reduced, but the structural complexity increases

Engineering Contradiction:

Improvepressure lossVSAvoidstructural complexity

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the teeth-to-screw grooves ratio parameter to be greater than or equal to 2.5. This specific parameter adjustment optimizes the meshing between the gate rotor teeth and screw rotor grooves, improving sealing performance and reducing pressure loss without requiring fundamental structural redesigns.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If the screw rotor rotational speed is increased, then displacement increases and COP improves, but control difficulty increases

Engineering Contradiction:

ImprovedisplacementVSAvoidcontrol difficulty

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical unloading control system with an electrical speed control system using a speed adjuster. This substitution allows precise control of the screw rotor's rotational speed, enabling increased displacement and improved COP while maintaining ease of operation through electronic control rather than mechanical complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11913452B2Screw compressor

Publication Date: 2024.02.27 DAIKIN INDUSTRIES LTD

AI summary

A screw compressor includes a screw rotor, a gate rotor, and a speed adjuster. The screw rotor has an outer peripheral surface with a plurality of screw grooves. The screw rotor is configured to be rotated. The gate rotor has a plurality of teeth. A ratio T/S of a number T of the teeth to a total number S of the screw grooves is greater than or equal to 2.5. The gate rotor meshes with the screw rotor. The speed adjuster is configured to adjust a rotational speed of the screw rotor. Rotation of the screw rotor at an angle greater than 180° allows the screw compressor to perform a stroke from start of compression to completion of discharge.