Percussion Mechanism Check Valve for Hammer Drill Guidance

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Solution Overview

Problem

High-powered hand-held pneumatic hammer drills face difficulties in controlling the guidance of the tool when reapplying pressure, leading to inefficient operation.

Innovation Solution

A percussion mechanism with a check valve and closure mechanism, including resilient flaps and a throttle opening, which allows air to flow into the pneumatic chamber when the tool is not in use, creating counterpressure that aids in guiding the drill effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the pneumatic chamber is open to allow air flow, then the percussion mechanism can be deactivated easily, but the tool cannot maintain stable guidance when reapplying pressure

Engineering Contradiction:

Improvedeactivation of percussion mechanismVSAvoidguidance stability when reapplying pressure

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

A check valve is introduced as an intermediary component between the pneumatic chamber and the external environment. The check valve allows air to enter the pneumatic chamber to deactivate the percussion mechanism, but prevents air from escaping, thereby maintaining counterpressure for stable guidance when the user reapplying pressure to the tool.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Force

If the check valve remains closed during percussive operation, then the pneumatic chamber maintains counterpressure, but the percussion mechanism cannot start

Engineering Contradiction:

Improvecounterpressure in pneumatic chamberVSAvoidstart-up of percussion mechanism

Core Design Contradiction:

ForceVSProductivity

Solution Approach 1:

The check valve transitions from a static closed state to a dynamic open state during percussive operation. The valve is designed to open when the percussion means generates sufficient force during striking, allowing air to escape and the percussion mechanism to start, while remaining closed during non-operational states to maintain counterpressure.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The check valve is prestressed into a closed position by default to prevent accidental start-up of the percussion mechanism. This preliminary closure creates a safety barrier that must be actively overcome by the percussive force itself, ensuring the mechanism only starts when properly activated by user pressure and striking action.

Inventive Principle:

Principle #9Preliminary anti-action

3Reliability

If a closure mechanism with large pressure gradient is used, then the check valve closes securely, but the closure mechanism becomes heavy and slow to operate

Engineering Contradiction:

Improveclosure security of check valveVSAvoidweight of closure mechanism

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The closure mechanism utilizes pneumatic pressure differential rather than mechanical weight or springs. The small resilient flaps are actuated by air pressure differences across them, allowing lightweight components to achieve reliable closure. The pressure gradient itself becomes the actuating force, eliminating the need for heavy springs or complex mechanical actuators.

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 enables more precise control and effective guidance of the hammer drill by maintaining constant counterpressure, preventing accidental start-ups and enhancing percussive power as pressure equalizes, thus improving user handling and operational efficiency.

Implementation Method 1

The closure mechanism can open and close quickly and with a small pressure gradient

Methodology Applied

Scientific EffectPressure gradient: Pressure Gradient

Implementation Method 2

The throttle opening preferably allows for a small, but therefore continuous, airflow between the pneumatic chamber and the surrounding area in order to ensure that the pressure is equalized

Methodology Applied

Scientific EffectPressure equalization: Pressure Gradient

Implementation Method 3

The check valve allows air to flow into the pneumatic chamber and deactivates the air spring of the pneumatic chamber

Methodology Applied

Scientific EffectGas compression: Compression

Data Source

PatentUS10821589B2Percussive power tool

Publication Date: 2020.11.03 HILTI AG

AI summary

A percussion mechanism contains a guide tube, an exciter piston, a hammer, a pneumatic chamber for coupling the hammer to the motion of the exciter piston, a striker, and a seat for the striker. The hammer has a striking point, defined by a striking surface of the striker when the striker lies against the seat. A check valve has an outlet opening and a closing mechanism for closing the check valve against an air flow from the interior of the guide tube. The outlet opening is arranged in such a way that the outlet opening is closed by the hammer during striking operation and otherwise is open.