Compact Hammer Drill Clutch Mechanism Design
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Solution Overview
Problem
The existing hammer drills with two clutches require a long intermediate shaft due to the placement of a coil spring between them, making the device less compact.
Innovation Solution
A hammer drill design that includes an intermediate shaft with rotatable and axially slidable first and second clutches, where an elastic element urges the clutches apart, and clutch operation members are guided and restrained to allow for compactness without a long intermediate shaft, enabling selection of different operation modes by sliding the clutches from outside the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two clutches are provided with a coil spring interposed between them to urge the clutches apart, then the clutches can be reliably engaged and disengaged, but the intermediate shaft becomes longer in the axial direction, making the hammer drill less compact
Solution Approach 1:
The patent combines the functions of two separate clutches (first clutch for impact transfer member and second clutch for rotation transfer member) into a single integrated clutch structure that can selectively engage with either member. This merging eliminates the need for a coil spring to separate two clutches, thereby reducing the axial length of the intermediate shaft while maintaining reliable engagement through the single clutch's selective positioning.
Solution Approach 2:
The single clutch is designed with multi-functionality to perform the roles of both the first and second clutches. It can selectively engage with the impact transfer member or the rotation transfer member based on the operational mode selected, thereby eliminating the need for separate clutches and the coil spring between them, achieving compactness without sacrificing engagement reliability.
2Reliability
If the intermediate shaft is made longer to accommodate the coil spring between two clutches, then the clutches can be properly engaged, but the overall device size increases, hindering compactness
Solution Approach 1:
By merging two separate clutches into one integrated clutch structure, the patent eliminates the coil spring component and reduces the axial space required, thereby decreasing the overall volume of the hammer drill while ensuring reliable engagement through the unified clutch's selective engagement mechanism.
Solution Approach 2:
The single clutch structure is designed to nest within a compact space on the intermediate shaft, allowing it to selectively engage with either the impact transfer member or the rotation transfer member without requiring additional axial space for separate clutch mechanisms, thus reducing the overall device volume.
3Length of moving object
If a single clutch is used instead of two clutches, then the hammer drill can be made compact, but the selection of operation modes becomes more complex
Solution Approach 1:
The single clutch is designed with dynamic engagement capabilities, allowing it to be selectively positioned to engage with either the impact transfer member or the rotation transfer member based on the desired operational mode. This dynamic positioning mechanism, while compact, provides the necessary complexity for mode selection without requiring multiple separate clutch components.
Solution Approach 2:
The patent introduces an intermediary mechanism (such as a positioning member or actuator) that controls the single clutch's engagement with either the impact transfer member or the rotation transfer member. This intermediary element manages the complexity of mode selection within the compact single-clutch structure, eliminating the need for two separate clutches while maintaining operational versatility.
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 compact hammer drill with improved assembly ease, reduced heat generation, and proper engagement of clutches, maintaining performance across different operation modes without the need for a lengthy intermediate shaft.
Implementation Method 1
An elastic element is held between a first clutch operation member and a second clutch operation member... The elastic element urges the first clutch and the second clutch in directions away from each other.
Data Source
AI summary
In a hammer drill, a coil spring that urges a first clutch and a second clutch in directions away from each other is held between a first change plate that engages with the first clutch to be slidable in the axial direction of an intermediate shaft and a second change plate that engages with the second clutch to be slidable in the axial direction of the intermediate shaft. The first change plate is slidably guided by a gear housing.