Rechargeable Traps with Variable-Weight Piston Cores

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Solution Overview

Problem

Existing traps cause non-target bycatch issues, such as capturing birds, lizards, and kittens, and are bulky or inefficient, leading to animal suffering and public backlash due to indiscriminate use of toxins and inefficient designs.

Innovation Solution

A rechargeable trap with a piston or spear of varying weights, featuring a replaceable core and inserts to regulate entry size, combined with a hallway and serrated protrusions to prevent non-target species, and a scent attractant to lure target species.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed-weight piston or spear is used in the trap, then the trap structure is simple, but the trap cannot selectively target different rodent species and causes non-target bycatch

Engineering Contradiction:
Improveselectivity for different rodent speciesVSAvoidtrap structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The piston or spear is divided into a permanent outer shell and a replaceable inner core. The core contains the weight-regulating functionality through interchangeable inserts, separating the killing mechanism from the weight adjustment mechanism. This allows selective targeting of different rodent species by changing only the core component rather than redesigning the entire trap.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The trap is designed with a universal piston/spear shell that can accommodate multiple types of cores with different weights and insert configurations. A single trap body can selectively target different rodent species (e.g., mice, rats, voles) by swapping the core assembly, making the trap multi-functional without requiring multiple separate trap designs.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Force

If heavier piston or spear is used, then larger animals like rats can be killed effectively, but smaller animals like mice may not be killed humanely or at all

Engineering Contradiction:
Improvekilling forceVSAvoidadaptability to different target species
Core Design Contradiction:
ForceVSAdaptability or versatility

Solution Approach 1:

The weight parameter of the piston or spear is made variable through interchangeable inserts of different masses. Users can select appropriate weight combinations to match the target species - lighter inserts for mice, heavier inserts for rats or larger rodents. This parameter adjustment ensures the killing force is always appropriate for the intended target, preventing both insufficient killing power and excessive cruelty.

Inventive Principle:
Principle #35Parameter changes

3Area of moving object

If the trap entrance is made large to accommodate larger rodents, then larger animals can enter, but non-target species like birds and lizards are also caught

Engineering Contradiction:
Improveentrance sizeVSAvoidnon-target bycatch
Core Design Contradiction:
Area of moving objectVSObject-affected harmful factors

Solution Approach 1:

The entrance structure is segmented into a fixed outer frame and removable inner inserts with species-specific aperture sizes. The inserts act as adjustable screens that can be selected based on the target species, allowing the trap to maintain an appropriately sized entrance while preventing non-target species from entering.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the entrance are made selectively accessible through inserts with varying aperture patterns. The insert material and opening configuration are locally optimized for the target species - smaller openings for mice that exclude birds, larger openings for rats that still prevent lizard entry through combination with weight-based killing mechanisms.

Inventive Principle:
Principle #3Local quality

4Object-affected harmful factors

If live capture cage traps are used, then animal suffering is reduced, but the trap becomes much bulkier and requires regular checking to prevent stress and suffering

Engineering Contradiction:
Improveanimal sufferingVSAvoidtrap size
Core Design Contradiction:
Object-affected harmful factorsVSVolume of moving object

Solution Approach 1:

The mechanical restraint system of live capture traps is replaced with a mechanical killing system using a weighted piston or spear. Instead of confining the animal in a cage, the trap delivers a controlled mechanical impact that instantly incapacitates the target. This substitution eliminates the need for large cage structures and frequent checking intervals, while still addressing animal welfare through immediate action.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

Reduces non-target bycatch by allowing selective targeting of rodents, minimizing animal suffering and public concern through efficient and humane killing.

Implementation Method 1

a piston or spear with a replaceable core... adapted for replacing said replaceable core. Kit of cores of varying weights

Methodology Applied
Scientific EffectKinetic energy:

Implementation Method 2

killing means that strikes the rodent and almost instantly kills the rodent

Methodology Applied
Scientific EffectImpact force: Impact Force

Implementation Method 3

The killing means in mechanical traps are normally spring driven or gas pressure driven

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 4

spring driven or gas pressure driven

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Data Source

PatentEP4164380B1A rechargeable trap with pistons or spears of varying weights
Publication Date: 2025.10.15 CAMRO AS
  • EP4164380B1 patent drawingFigure 1
  • EP4164380B1 patent drawingFigure 2
  • EP4164380B1 patent drawingFigure 3

AI summary

The present invention relates to the use of a kit of pistons or spears of varying weights for preparing a rechargeable trap for a specific target species, and to a rechargeable trap with pistons or spears of varying weights.