Pneumatic Return Mechanism for Percussion Foot Pedals

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Solution Overview

Problem

The existing pneumatic return mechanisms for drum pedals, such as those using rolling diaphragms and cylindrical pistons, face issues like premature failure due to friction and limited adjustability, leading to reduced cycle life and inconsistent feel compared to traditional spring mechanisms.

Innovation Solution

The use of a flat diaphragm with a spherical piston and an adjustable cam-shaped track hub, along with a stiffener to prevent slack in the flexible connector, enhances reliability and playability by reducing friction and allowing for customizable return speed and feel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rolling diaphragm is used in the pneumatic return mechanism, then the pedal can achieve smooth and quiet operation, but the diaphragm fails after many uses due to friction, distortion and side loads

Engineering Contradiction:

Improvediaphragm durabilityVSAvoidfriction and distortion

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the rolling diaphragm with a spherical piston that rotates within a cylindrical chamber. The spherical geometry eliminates the rolling motion that causes friction and distortion, allowing the piston to rotate freely while maintaining sealed pneumatic contact with the chamber wall through a circumferential groove.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If a cylindrical piston is used in the pneumatic return mechanism, then the pedal can provide pneumatic return force, but the piston must remain perfectly parallel to the cylinder axis to minimize friction, requiring two pivot points and a linear bearing

Engineering Contradiction:

Improvepiston friction reductionVSAvoidpivot points and linear bearing

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The spherical piston eliminates the need for multiple pivot points and linear bearings. The sphere can rotate freely within the cylindrical chamber while maintaining pneumatic sealing through the circumferential groove, simplifying the mechanism while reducing friction points.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The spherical piston allows dynamic rotation within the cylinder rather than requiring fixed parallel alignment. This dynamic capability enables the piston to adapt its orientation during operation, eliminating the need for complex alignment mechanisms like linear bearings.

Inventive Principle:

Principle #15Dynamics

3Ease of operation

If a flexible chain, strap or belt is used to connect the footboard and beater, then the pedal can provide a lighter and more sensitive feel, but the connector becomes momentarily slack and loose during use

Engineering Contradiction:

Improvepedal sensitivityVSAvoidconnector slackness

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent applies different structural qualities to different parts of the connector system. The portion of the chain or strap that contacts the track hub is made rigid through a rigid connector, while other portions can remain flexible to maintain the desired pedal feel. This localized rigidity eliminates slack at the critical connection point while preserving flexibility elsewhere.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The connector is divided into segments with different properties: a rigid connector portion that contacts the track hub to eliminate slack, and flexible chain/strap portions that provide sensitivity. This segmentation allows each part to perform its specific function optimally.

Inventive Principle:

Principle #1Segmentation

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 provides a longer-lasting, more reliable, and customizable pneumatic return mechanism with a unique 'bouncy' feel, improving pedal playability and allowing for adjustments not possible with traditional spring or pneumatic setups.

Implementation Method 1

pressing the footboard downward causes the spherical piston to compress the flat diaphragm, thereby generating a pneumatic pressure

Methodology Applied

Scientific EffectPneumatic pressure: Pressure Increase

Implementation Method 2

the flat diaphragm follows a 'trampoline' type motion vs. a rolling diaphragm inversion motion

Methodology Applied

Scientific EffectElastic deformation: Elastic Recovery

Implementation Method 3

The compressed air inside the compression chamber pushes back against the diaphragm and piston

Methodology Applied

Scientific EffectPneumatic force: Pressure Increase

Data Source

PatentUS11450299B1Pneumatic return for foot pedals associated with percussion instruments

Publication Date: 2022.09.20 RUPRECHT DAVID S

AI summary

This improvement to a pneumatic return mechanism for percussion foot pedals incorporates a flat or bowl-shaped diaphragm rather than a rolling diaphragm, and a piston which is spherical rather than cylindrical, producing a bouncy feel for the player. A further improvement to the track hub of a percussion foot pedal enables bump fasteners to be removably inserted, to add lift and alter beater acceleration. A further improvement is a removable stiffener which prevents slack in the connector between the footboard and track hub of the percussion foot pedal, which may occur during fast drumming.