Plasma Torch Inner Cap Layout for Uniform Cooling Flow

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Solution Overview

Problem

Existing plasma arc torches often require significant driving force to propel coolant through a circuitous path, leading to uneven cooling and deadspots in the coolant flow.

Innovation Solution

The inner cap of the plasma arc torch features an interleaved series of apertures and slots that create a cross-flow of liquid coolant and shield gas, allowing for direct routing of coolant to consumables and minimizing the required driving force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If coolant is routed through a circuitous path within the torch, then the coolant can contact both the shield and the nozzle, but a significant driving force is required to propel the coolant

Engineering Contradiction:
Improvecoolant coverageVSAvoiddriving force
Core Design Contradiction:
ReliabilityVSForce

Solution Approach 1:

The patent inverts the traditional coolant routing approach by routing coolant directly from the nozzle to the shield in a single direction, rather than requiring the coolant to travel back and forth through the torch. This reversal of the cooling path eliminates the need for high driving force while ensuring both components are cooled effectively.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent extracts the complex multi-directional coolant routing from the torch body and relocates it to the inner cap component. By concentrating the cooling function in the inner cap with direct pathways, the system eliminates the need for high driving force while maintaining comprehensive coolant coverage.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If coolant flows through a circuitous path with multiple trips, then both shield and nozzle are cooled, but deadspots and unidirectional flow occur causing uneven cooling

Engineering Contradiction:
Improvecooling coverageVSAvoidcooling uniformity
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies local quality by providing dedicated cooling pathways in the inner cap that deliver coolant directly to specific locations (nozzle and shield) with optimized flow distribution. This ensures uniform cooling across all components without deadspots, as each component receives coolant through purpose-designed channels rather than relying on general circulation.

Inventive Principle:
Principle #3Local quality

3Device complexity

If the inlet and outlet are oriented with respect to each other in previous designs, then the torch structure is simple, but dead spots and uneven cooling in the torch tip are common

Engineering Contradiction:
Improvestructural simplicityVSAvoidcooling uniformity
Core Design Contradiction:
Device complexityVSStability of the object's composition

Solution Approach 1:

The patent transitions from a simple linear inlet-outlet orientation to a three-dimensional network of cooling channels within the inner cap. This dimensional expansion allows coolant to reach all surfaces of the nozzle and shield uniformly, eliminating dead spots while maintaining overall structural simplicity through integrated design.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 configuration reduces the driving force needed to move coolant, provides even and symmetrical cooling, and allows for a more compact and efficient design, including the ability to manufacture the shield cap as a single piece.

Implementation Method 1

coolant travels along a circuitous path within the torch... requiring a significant driving force to propel the coolant within the torch

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

coolant flows from a source through the plasma arc torch to a surface of the shield and back through the plasma arc torch

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3443817B1Inner cap for a plasma arc cutting system
Publication Date: 2025.03.05 HYPERTHERM INC
  • EP3443817B1 patent drawingFigure 1A
  • EP3443817B1 patent drawingFigure 1B
  • EP3443817B1 patent drawingFigure 2

AI summary

The invention features an inner cap for a liquid-cooled plasma arc torch. The inner cap includes a body having a longitudinal axis, a first end, and a second end. The first end includes an annular portion disposed proximate a torch tip. A liquid passage is formed within the body, is shaped to convey a liquid therethrough, and has a first set of ports formed in the annular portion. A gas passage is formed within the body, is shaped to convey a gas therethrough, and includes a second set of ports formed in the annular portion. The annular portion is configured such that subsets of ports in the first set of ports direct the liquid in a radial direction with respect to the longitudinal axis and alternate, in a rotational direction about the longitudinal axis, with subsets of ports in the second set of ports.