Impact Wrench Planetary Transmission for Tight-Space Torque Control
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Solution Overview
Problem
Existing impact wrenches face challenges in being compact and easy to control, especially when working in narrow spaces, and there is a need for improved design to enhance their operational efficiency and usability.
Innovation Solution
The impact wrench features a housing with an electric motor, a transmission assembly including planetary gears, and an impact assembly, where the rear cover is integrally formed with an inner ring gear, and the axial overlap length of the contact region between the rear cover and the main shaft is greater than or equal to 1.5 mm, enhancing the compactness and control of the tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the impact wrench is designed to be compact for working in narrow spaces, then the tool size is reduced, but the transmission of power and impact force becomes more difficult
Solution Approach 1:
The patent employs a planetary gear transmission system where planet gears are nested around a central sun gear within the motor housing. This nested configuration allows multiple gear elements to occupy the same radial space, achieving compact power transmission without increasing the overall tool volume. The planet gears engage with both the sun gear and the output shaft, efficiently transmitting motor power to the impact mechanism.
Solution Approach 2:
The patent utilizes the radial dimension by arranging planet gears around the central sun gear, converting what would traditionally be a linear transmission path into a radial configuration. This dimensional change allows the transmission assembly to fit within the compact motor housing while maintaining effective power transmission capability.
2Length of moving object
If the impact wrench is designed to be compact, then the overall length is reduced, but the control and maneuverability may be compromised
Solution Approach 1:
The patent integrates the battery pack, motor housing, and transmission assembly into a unified compact structure. The motor is positioned centrally within the housing, and the transmission components are arranged around it, merging multiple functional elements into a cohesive compact unit that maintains control accessibility.
Solution Approach 2:
The impact mechanism incorporates a movable impactor that can dynamically adjust its position and movement characteristics. This dynamic design allows the compact tool to maintain effective impact force delivery while preserving maneuverability in confined spaces.
3Stability of the object's composition
If the axial overlap length of the contact region between the rear cover and the main shaft is increased, then the structural stability is improved, but the manufacturing complexity increases
Solution Approach 1:
The rear cover is designed to serve multiple functions: it provides structural support, houses the planetary gear transmission, and creates the necessary contact region with the main shaft for stability. By combining these functions into a single component, the design achieves structural stability without proportionally increasing manufacturing complexity.
Solution Approach 2:
The patent specifies a minimum axial overlap length of 1.5mm between the rear cover and main shaft contact region. This parameter optimization ensures adequate structural stability while maintaining manufacturability, as the required overlap is sufficient for stability but not excessive to complicate manufacturing.
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 design allows for a more compact and controllable impact wrench, capable of delivering high torque and impact frequency, suitable for use in confined spaces, with improved operational efficiency and ease of use.
Implementation Method 1
an electric motor accommodated in the housing and including a stator assembly and a rotor assembly, where the rotor assembly includes a rotor shaft
Implementation Method 2
multiple planet gears are disposed around the multiple planetary shafts, respectively, and the gear extends into the main shaft and drives the multiple planet gears
Implementation Method 3
When the multiple planet gears rotate in the inner ring gear, the rear cover is in sliding contact with the main shaft
Data Source
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AI summary
An impact wrench includes a housing, an electric motor, an anvil, a grip, an impact assembly, and a transmission assembly, where the transmission assembly is disposed between the electric motor and the impact assembly. The transmission assembly includes a main shaft disposed in the extension direction of the rotor shaft and including multiple planetary shafts, where multiple planet gears are disposed around the multiple planetary shafts, respectively, and a gear extends into the main shaft and drives the multiple planet gears; and a rear cover surrounding at least part of the main shaft from the rear to the front, where the rear cover is formed with an inner ring gear, and the inner ring gear meshes with the multiple planet gears. When the multiple planet gears rotate in the inner ring gear, the rear cover is in sliding contact with the main shaft.