Piston Rod Joint Clip Device for 360 Rotation

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Solution Overview

Problem

Existing actuating devices for hydraulic brake or clutch systems face challenges in preventing the piston rod from being lost during transport, especially when the piston rod needs to rotate 360°, as the preload spring can cause the latching elements to separate from the stop ring, leading to the captive device coming loose.

Innovation Solution

The actuating device incorporates a clip device with a spring arm and latching projection that engages behind the stop ring, ensuring the remaining play is smaller than the latching projection's grip length, preventing the clip element from detaching and allowing the piston rod to rotate securely.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the piston rod is allowed to rotate 360° through the clip connection, then the actuating device can be used in both left-hand drive and right-hand drive vehicles, but the latching elements may separate from the stop ring due to preload spring force, causing the captive device to come loose

Engineering Contradiction:
Improveadaptability to different vehicle configurationsVSAvoidsecurity of captive device attachment
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The invention applies preliminary anti-action by designing the clip element with a latching projection that engages behind the stop ring in advance, creating a preventive mechanism against the separation caused by preload spring force during rotation. The latching projection is positioned to engage the stop ring before the harmful separation effect can occur, thus preventing the captive device from coming loose while allowing 360° rotation for adaptability to different vehicle configurations.

Inventive Principle:
Principle #9Preliminary anti-action

2Ease of operation

If the clip element is designed to allow 360° rotation of the piston rod, then installation flexibility is improved, but the remaining play becomes large enough to allow the latching projection to detach from the stop ring

Engineering Contradiction:
Improveinstallation flexibilityVSAvoidretention of latching projection on stop ring
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention applies parameter changes by carefully designing the dimensions of the latching projection and the stop ring engagement geometry. The latching projection is dimensioned with sufficient length and engagement depth to maintain reliable connection throughout the 360° rotation range. By optimizing these geometric parameters, the design achieves both installation flexibility and retention reliability, ensuring the latching projection remains securely engaged with the stop ring even when the piston rod rotates through its full range of motion.

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

This design effectively prevents the piston rod from being lost during transport and rotation, maintaining a secure mechanical connection by ensuring the clip element cannot deform enough to detach from the stop ring, even under the force of the preload spring.

Implementation Method 1

the clip device has at least one clip element with (i) a spring arm fastened to the base body and extending through the interior of the stop ring parallel to the piston rod

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3123034B1Piston rod joint
Publication Date: 2018.01.31 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3123034B1 patent drawingFigure 1~2
  • EP3123034B1 patent drawingFigure 3~4
  • EP3123034B1 patent drawingFigure 5~6

AI summary

The invention relates to an actuating device for mechanical connection to a piston of a working cylinder, comprising a piston rod (12), which has a piston-rod base (14) at one end, a stop ring (16) for the piston-rod base (14), which stop ring accommodates the piston rod (12) in the interior of the stop ring with play, wherein the piston-rod base can pass through the stop ring (16) in at least one angular position of the piston rod (12) in relation to the stop ring, and a retaining device (24) to prevent such passing through, which retaining device has a main body (28) and a clip device. The clip device has at least one clip element (36, 38) comprising a spring arm (40, 42), which is fastened to the main body (26) and reaches through the interior of the stop ring (16) parallel to the piston rod, and comprising a latching projection (44, 46), which is arranged on the spring arm, wherein the remaining play S of the assembly of the piston rod and the at least one spring arm in the interior of the stop ring, with the piston-rod base lying against the stop ring or the clip element and being in the angular position permitting the passing through, is less than the rearward-engagement length L of the at least one latching projection.