Crossbow Trigger Safety Lever for Unintentional Discharge Prevention

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Solution Overview

Problem

Simpler crossbows, particularly 'edge lifters,' lack a reliable trigger safety mechanism, leading to unintentional discharges due to mechanical impacts or shocks, and existing safety mechanisms are often bypassed, compromising safety.

Innovation Solution

A safety lever is coupled to the trigger, ensuring the drawn string is held in the retaining groove until the trigger is actuated, using a hook-shaped end to close the groove and a compression spring to maintain the safety position, preventing unintentional discharge.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a trigger mechanism is added to hold the string in a retaining groove, then the crossbow is secured against unintentional discharge, but the device complexity increases

Engineering Contradiction:
Improvesafety against unintentional dischargeVSAvoidmechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The trigger mechanism is divided into separate functional components: a trigger member that the shooter actuates, a safety lever that directly blocks the retaining groove opening, and a connection element that links them. This segmentation allows each component to have a specific, simple function while collectively providing reliable safety against unintentional discharge.

Inventive Principle:
Principle #1Segmentation

2Reliability

If a safety mechanism is added to prevent unintentional discharge, then reliability improves, but manufacturing cost increases

Engineering Contradiction:
Improvesafety against unintentional dischargeVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The safety lever is designed as a simple, inexpensive component that can be manufactured from common materials like plastic or metal using standard processes such as injection molding or stamping. The design prioritizes functional effectiveness over material prestige, using straightforward geometries that minimize manufacturing complexity and cost while providing reliable safety functionality.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

3Device complexity

If the string is held in a retaining groove without a safety lever, then the device complexity is reduced, but the crossbow becomes vulnerable to mechanical impacts causing unintentional discharge

Engineering Contradiction:
Improvemechanism simplicityVSAvoidvulnerability to mechanical impacts
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The safety lever proactively blocks the retaining groove opening before any unintentional discharge can occur. By positioning the safety lever to directly obstruct the groove opening in the cocked state, the design prevents mechanical impacts or shocks from dislodging the string, addressing the vulnerability to harmful factors before they can cause damage.

Inventive Principle:
Principle #9Preliminary anti-action

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

Provides a simple and cost-effective automatic safety mechanism that prevents unintentional firing without requiring manual deactivation before each shot, enhancing safety and suitability for less expensive crossbows.

Implementation Method 1

a compression spring (13) is provided for the locking lever (11)

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

a compression spring (13) is provided for the locking lever (11)

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP4537042B1Crossbow
Publication Date: 2025.11.19 STEAMBOW GMBH
  • EP4537042B1 patent drawingFigure 1
  • EP4537042B1 patent drawingFigure 2
  • EP4537042B1 patent drawingFigure 3

AI summary

The invention relates to a crossbow (1) for firing projectiles (5), said crossbow comprising: a stock (2) and a guide rail (9) arranged thereon for accelerating a projectile (5); limbs (3) between which a tensionable string (4) is arranged; a retaining groove (6) for retaining the string (4) in a tensioned state in a holding position; and a trigger (7) for moving the tensioned string (4) out of the retaining groove (6) in order to fire the crossbow and to accelerate the projectile (5) along the guide rail (9). In order to prevent the crossbow (1) from firing accidentally, a safety lever (11) is provided for holding the tensioned string (4) in the retaining groove (6), which safety lever (11) is coupled with the trigger (7) so that, when the trigger (7) is moved from the holding position to fire the crossbrow, the safety lever (11) and thus the string (4) can be moved out of the retaining groove (6).