Axial Tooth Sleeve Fixing in Hammer Drills
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Solution Overview
Problem
Existing hand-held power tools face issues with wear on the toothed sleeve and motor shaft due to tilting under load during mode changes, leading to inefficiencies and potential damage, especially when switching between drilling, percussion drilling, and chiseling operations.
Innovation Solution
The toothed sleeve is fixed axially within the hand-held power tool housing, with a coupling element providing a torque-proof connection to the switching element, and a spring element facilitates mode changes, while connecting elements ensure rotational stability in specific modes and freewheeling in others, minimizing wear and optimizing torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the toothed sleeve is allowed to move axially during mode changes, then the operating mode can be changed, but wear on the toothed sleeve and motor shaft increases due to tilting under load
Solution Approach 1:
The toothed sleeve is designed to be axially movable relative to the motor shaft, allowing dynamic adjustment of the axial position to engage different operating modes (drilling, percussion drilling, chiseling). This dynamic capability enables the system to adapt to different operational requirements while maintaining reliable torque transmission through the coupling element that prevents tilting during mode transitions.
2Reliability
If the toothed sleeve is fixed axially, then wear is minimized, but the ability to change operating modes is restricted
Solution Approach 1:
The transmission system is segmented into independently movable components: the toothed sleeve can move axially relative to the motor shaft, while the coupling element provides a torque-proof connection that prevents tilting. This segmentation allows the toothed sleeve to be fixed axially during normal operation to minimize wear, while still enabling mode changes when needed through controlled axial movement of the coupling element or toothed sleeve.
3Reliability
If a torque-proof connection is provided between the toothed sleeve and switching element, then reliable operation is ensured, but the device complexity increases
Solution Approach 1:
A coupling element is introduced as an intermediary component between the toothed sleeve and the switching element. This coupling element provides a torque-proof connection that ensures reliable power transmission while allowing axial movement for mode changes. The coupling element acts as a mediator that decouples the torque transmission function from the axial movement function, ensuring reliable operation without requiring complex integrated structures.
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 effectively minimizes wear on the toothed sleeve and motor shaft, prevents tilting, and allows for reliable operation across multiple modes, enhancing the tool's durability and performance by maintaining a stable connection and efficient torque transmission.
Implementation Method 1
a spring element (26a) which is intended to displace at least the switching element (22a) at least when there is a change in operating mode
Implementation Method 2
a coupling element (24a) which connects the switching element (22a) and the toothed sleeve (18a) to one another in a torque-proof manner
Implementation Method 3
at least one bearing (76a) arranged within the toothed sleeve (18a), which supports the toothed sleeve (18a) axially and/or radially
Data Source
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AI summary
The invention relates to a hand-held machine tool, particularly a hammer drill, comprising a work spindle (12a-h), a hand-held machine tool housing (86a-h) and an intermediate shaft (16a-h) which is arranged in parallel to the work spindle (12a-h) and mounted in an axially displaceable manner for changing the operational mode, and a tooth sleeve (18a-h) which is provided to transfer a torque to the intermediate shaft (16a-h). According to the invention, the tooth sleeve (18a-h) is fixed in the axial direction (20a-h) by means of the hand-held machine tool housing (86a-h).