Screw Compressor Slide Valve for Variable Internal Volume Ratio

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Solution Overview

Problem

Fixed-frequency screw compressors suffer from inefficiencies and high energy consumption due to a fixed internal volume ratio, leading to under-compression or over-compression states, resulting in low operating efficiency and high noise.

Innovation Solution

A slide valve with a slider mechanism and spring system that adjusts the discharge position of the compressed medium, allowing the internal volume ratio to match external pressure, reducing power loss and noise by varying the exhaust aperture size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a fixed internal volume ratio is used in a fixed-frequency screw compressor, then the structure is simple and easy to manufacture, but the operating efficiency is low and energy consumption is high due to under-compression or over-compression states

Engineering Contradiction:
Improvestructural simplicityVSAvoidoperating efficiency
Core Design Contradiction:
Ease of manufactureVSProductivity

Solution Approach 1:

The patent applies the dynamics principle by transforming the fixed slide valve position into a movable one. The slide valve is driven to move along the axial direction of the rotor through a driving mechanism (such as a cam mechanism or motor-driven mechanism), enabling the internal volume ratio to be dynamically adjusted according to different working conditions. This resolves the contradiction by making the previously static parameter (slide valve position) dynamic, thereby improving operating efficiency without significantly complicating the manufacturing process.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies the parameter changes principle by varying the internal volume ratio parameter according to different operating conditions. By adjusting the slide valve position, the internal volume ratio can be changed to match the external pressure requirements, avoiding under-compression or over-compression states. This parameter adjustment enables the compressor to adapt to varying load conditions, improving overall operating efficiency while maintaining reasonable structural complexity.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If a fixed internal volume ratio is used, then the device structure is simple, but additional power consumption occurs due to isochoric compression or expansion

Engineering Contradiction:
Improvestructure complexityVSAvoidadditional power consumption
Core Design Contradiction:
Device complexityVSLoss of energy

Solution Approach 1:

The patent uses the dynamics principle to make the slide valve position adjustable, allowing the internal volume ratio to be optimized for different operating conditions. This dynamic adjustment prevents isochoric compression or expansion by ensuring the compression process matches the actual demand, thereby reducing additional power consumption. The added complexity of the driving mechanism is justified by the significant energy savings achieved.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent applies parameter changes by adjusting the internal volume ratio parameter to match external pressure requirements. By changing the slide valve position parameter, the system avoids energy-wasting isochoric processes and optimizes the compression efficiency, reducing additional power consumption while accepting moderate increases in device complexity.

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If a fixed internal volume ratio is used, then the design is simple, but noise is high due to pressure mismatch between internal and external pressure

Engineering Contradiction:
Improvedesign complexityVSAvoidnoise
Core Design Contradiction:
Device complexityVSObject-generated harmful factors

Solution Approach 1:

The patent applies the dynamics principle by enabling dynamic adjustment of the slide valve position, which allows the internal pressure to be continuously matched with the external pressure. This dynamic pressure matching prevents sudden pressure imbalances that cause noise, resolving the contradiction between design simplicity and noise reduction by introducing a controlled adjustment mechanism.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent uses parameter changes by adjusting the internal volume ratio parameter to maintain pressure balance between the compression chamber and the discharge environment. By varying the slide valve position, the system prevents pressure mismatch-induced noise while accepting moderate design complexity increases. The parameter adjustment ensures smooth pressure transitions, reducing harmful noise generation.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If the slide valve is in a fixed position, then the manufacturing cost is low, but the compressor cannot adapt to different working conditions

Engineering Contradiction:
Improvemanufacturing costVSAvoidadaptability to working conditions
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent applies the dynamics principle by transforming the fixed slide valve into a movable one with a driving mechanism. This enables the compressor to adapt to different working conditions by adjusting the internal volume ratio according to actual demand. The added manufacturing cost is offset by the significant improvement in adaptability and operational flexibility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent uses parameter changes by adjusting the internal volume ratio parameter through slide valve position control. This allows the compressor to adapt to varying working conditions such as different load requirements and pressure demands. The moderate increase in manufacturing cost is justified by the enhanced versatility and ability to optimize performance across different operating scenarios.

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

The slide valve improves operating efficiency and reduces noise by dynamically adjusting the internal volume ratio to match external pressure, enhancing performance under varying conditions.

Implementation Method 1

a spring connected to the slider and configured to drive the slider to slide to a position where the outer edge of the slider is flush with the pressure discharge surface

Methodology Applied
Scientific EffectElastic force: Spring

Data Source

PatentEP4686830A1Screw compressor and its slide valve
Publication Date: 2026.02.04 CARRIER CORP
  • EP4686830A1 patent drawingFigure 1~2
  • EP4686830A1 patent drawingFigure 3~4
  • EP4686830A1 patent drawingFigure 5

AI summary

This application provides a screw compressor (1) and a slide valve (2) thereof. The slide valve (2) includes: a valve body (21) having a cylindrical shape extending in an axial direction, with a side surface having a pressure discharge surface (211) that matches an outer peripheral contour of a rotor of the screw compressor (1); a discharge chamber (22) provided at an end of the pressure discharge surface (211) along the axial direction; a slider (23) provided in the discharge chamber (22), and configured to slide along a radial direction of the valve body (21), a shape of an outer edge of the slider (23) matching a shape of the pressure discharge surface (211); and a spring (24) connected to the slider (23) and configured to drive the slider (23) to slide to a position where the outer edge of the slider (23) is flush with the pressure discharge surface (211). According to the above structure of the slide valve (2), a discharge position of a compressed working medium can be adjusted, an internal volume ratio can be changed, an internal pressure can match an external pressure at the end of compression, an additional power loss can be reduced, an operating efficiency of the compressor can be improved, and noise caused by pressure mismatch can be reduced.