Socket Spanner Retaining Sleeve for Impact Driver Torque Stability

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Solution Overview

Problem

Existing socket wrenches with spring elements fail to maintain effective radial force when used on rotary impact wrenches, leading to the spring element's rotational position change and potential loss of the ball from the window, resulting in insufficient holding force on screw heads or nuts.

Innovation Solution

A shrink tube made of plastic is shrunk onto the socket wrench's wall, creating a tight frictional or adhesive contact with both the spring element and the outer wall, preventing rotation and maintaining the spring element's position, while a metal strip spring washer with a zigzag gap design ensures the ball is held securely.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spring element with a ball is used to hold the polygonal screw head or nut in the polygonal opening, then the socket wrench can effectively grip and transmit torque, but under rotational impacts from a rotary impact wrench, the spring element changes its rotational position causing the gap to lie over the ball, resulting in loss of radial force and potential ball ejection

Engineering Contradiction:
Improveholding forceVSAvoidrotational position stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

A restraining element is introduced as an intermediary component between the spring element and the polygonal opening. This restraining element prevents rotational movement of the spring element relative to the polygonal opening, ensuring the gap remains positioned away from the ball. The intermediary component resolves the contradiction by decoupling the spring element's gripping function from its rotational stability, allowing reliable torque transmission without rotational displacement under impact loads.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The restraining element applies a preliminary constraining action on the spring element to prevent rotational displacement before it can occur during operation. By pre-positioning and securing the spring element in the correct orientation, the system proactively counteracts the rotational impacts that would otherwise cause the gap to move over the ball and lose holding force.

Inventive Principle:
Principle #9Preliminary anti-action

2Stability of the object's composition

If a restraining element in the form of a lug is used to prevent rotation of the spring element, then rotational stability is improved, but the restraining element may fail under high torque conditions of rotary impact wrenches

Engineering Contradiction:
Improverotational position stabilityVSAvoidtorque resistance
Core Design Contradiction:
Stability of the object's compositionVSStrength

Solution Approach 1:

The restraining element's geometric parameters are optimized to withstand high torque conditions. The specific dimensions, thickness, and engagement features of the restraining element are designed to resist the rotational forces generated by rotary impact wrenches, transforming the previously insufficient lug design into a torque-resistant constraint mechanism.

Inventive Principle:
Principle #35Parameter changes

3Force

If the ball diameter is made larger than the window material thickness to ensure engagement, then gripping force is improved, but the ball becomes more prone to falling out when the spring element rotates

Engineering Contradiction:
Improvegripping forceVSAvoidball retention
Core Design Contradiction:
ForceVSReliability

Solution Approach 1:

The restraining element serves as a mediator that prevents the spring element from rotating, thereby keeping the gap positioned away from the ball. This intermediary constraint allows the ball to maintain its larger diameter for effective gripping while eliminating the rotational movement that would cause ball ejection, simultaneously improving both gripping force and ball retention reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 solution effectively prevents the spring element from rotating and maintains sufficient radial force on the ball, ensuring secure engagement with screw heads or nuts even under torque from rotary impact wrenches, with the shrink tube providing long-term anti-rotation security through friction and potential adhesive reinforcement.

Implementation Method 1

The sleeve according to the invention is in close contact with both an outer wall of the socket wrench itself and the spring element. This is preferably a frictional contact, with the frictional force resulting from a pretensioned surface contact.

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

Alternatively or in combination with this, the sleeve can also be in adhesive contact with the two surface sections of the outside of the wall or spring element.

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 3

The spring element is acted upon in a wall inside forward position... the spring element pushes it against a polygonal surface of the screw head or the nut

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2828037B1Socket spanner
Publication Date: 2020.09.09 WERA WERKZEUGE GMBH
  • EP2828037B1 patent drawingFigure 1~4
  • EP2828037B1 patent drawingFigure 5

AI summary

The invention relates to a socket spanner (1) comprising a drive head (2), which, together with an essentially annular wall (18), forms a polygonal profile opening (17) that can be plugged onto a polygonal bolt head or a polygonal screw nut, and comprising a retaining element (8) enclosed in a window (7) of the wall (18) of the polygonal profile opening (17), which retaining element is acted on by a spring element (9) arranged outside the wall to an advanced position inside the wall, and having a restraining element (19) for restraining the spring element (9) in the position thereof acting on the retaining element (8). According to the invention, in order to keep the spring element in position, even if the socket spanner is used on a rotary impact driver, the restraining element is a sleeve (19), which tightly abuts on the outside of the spring element (9) and on the outside of the wall (18).