Pneumatic Hammer Mode Switching via Planetary Gear
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Solution Overview
Problem
Existing pneumatic hammers face complexity and wear issues when operating in dust-laden environments, particularly when switching between different rotational directions, and require additional mechanical assemblies or costly gear sets for reverse rotation functionality.
Innovation Solution
A pneumatic hammer design featuring a mode change mechanism with a planetary gear set that allows for switching between hammer drill, drill, chisel, and reverse rotation modes by axially moving a ring gear and controlling a releasable connection, enabling torque transfer without additional mechanical means, thus simplifying operation and reducing wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a brushed motor with mechanical brush support switching is used to enable forward and reverse rotation, then reverse rotation functionality is achieved, but the mechanism becomes complicated and subject to wear in dust-laden environments
Solution Approach 1:
The patent replaces the mechanical brush support switching system with an electronic control system. The electronic switching mechanism uses transistors or MOSFETs to reverse the polarity of current supplied to the motor, eliminating the need for mechanical brush support repositioning. This substitution removes the wear-prone mechanical components while maintaining the reverse rotation capability, directly resolving the contradiction between versatility and complexity.
2Adaptability or versatility
If a separate stage in the gear set is added to enable reverse rotation, then reverse rotation functionality is achieved, but the weight and space requirements increase
Solution Approach 1:
The existing gear set in the pneumatic hammer is designed to serve multiple functions: it transmits power during forward rotation and, when engaged in reverse, transmits power during reverse rotation. The same gear teeth and meshing mechanisms are utilized bidirectionally, eliminating the need for dedicated reverse-rotation gears. This multi-functional design maintains versatility while avoiding additional weight.
3Adaptability or versatility
If a separate stage in the gear set is added to enable reverse rotation, then reverse rotation functionality is achieved, but the space requirements increase
Solution Approach 1:
The gear set is designed with dynamic engagement capabilities, where the same gear components can be selectively engaged or disengaged depending on the rotation direction required. The gear meshing geometry allows for bidirectional power transmission without requiring additional spatial provisions for separate forward and reverse gear trains. This dynamic utilization of existing space maintains versatility without increasing volume.
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 simplifies mode switching, reduces wear, and allows for reverse spindle rotation without reversing the motor's rotational direction, eliminating the need for complex assemblies and reducing weight and cost, while maintaining efficient tool bit operation.
Implementation Method 1
the input member is formed as a first carrier which eccentrically supports a rotatable first planet gear and is rotatable around a first axis of rotation, wherein a first sun gear is coaxially arranged with the first carrier and meshingly engages with the first planet gear
Implementation Method 2
the input member is formed as a first carrier which eccentrically supports a rotatable first planet gear
Implementation Method 3
in the cylinder an air cushion is formed between the piston and the ram so that the ram reciprocates upon reciprocating movement of the piston
Implementation Method 4
the second gear meshingly engages with the first ring gear when the first ring gear is in the second position
Implementation Method 5
a coupling section connected with the drive motor via a releasable connection which has an open state in which the second gear is not rotatingly driven by the drive motor, and a closed state in which the second gear is rotatingly driven by the drive motor
Data Source
AI summary
A pneumatic hammer has a conversion mechanism with a rotatable input member coupled to the motor and adapted to convert a rotational movement of the input member into a reciprocating movement of an output member. The input member is formed as a first carrier which supports a first planet gear. A first sun gear is coaxially arranged with the first carrier, and is rotatingly driven by the drive motor. A first ring gear is movable parallel to the first axis of rotation between a first position and a second position. A second gear is rotatable around a second axis of rotation parallel to the first axis of rotation. The second gear meshingly engages with the first ring gear when the first ring gear is in the second position, and is disengaged from the first ring gear when the first ring gear is in the first position.