Elastic Thread Section for Lawn Mower Vibration Damping
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lawn mowers, particularly autonomous ones, suffer from increased noise emissions during operation due to vibration and unbalanced cutting devices, which affect performance and user experience.
Innovation Solution
The implementation of an elastically displaceable thread section in the height adjustment device of the lawn mower, featuring threads with varying pitch and flank widths, and offset flanks, reduces axial play between rotating and sliding components, thereby dampening vibrations and noise. This design ensures the cutting device and motor are securely supported while allowing for precise height adjustment without unintended movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a standard thread connection is used in the height adjustment device, then the structure is simple and easy to manufacture, but axial play occurs between rotating and sliding components causing increased noise and vibration
Solution Approach 1:
The thread connection is designed with elastic displaceability, allowing dynamic adjustment and compensation of axial play between the rotating body and sliding seat. The elastic element enables the thread connection to adapt to operational variations while maintaining tight engagement, thereby reducing noise and vibration without requiring a completely complex rigid structure.
Solution Approach 2:
The thread geometry is modified by varying the thread tooth width and pitch width along the thread engagement. This parameter variation creates an optimized thread profile that reduces axial play and improves engagement stability. The changed thread parameters allow better load distribution and reduced clearance, directly addressing the noise and vibration issues while maintaining manufacturability.
2Object-affected harmful factors
If thread tooth width is increased to reduce axial play, then noise and vibration are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The thread structure implements local quality variation by having different thread tooth widths and pitch widths at different locations along the thread engagement. This allows critical sections to have tighter effective engagement for vibration reduction, while other sections maintain standard tolerances. The localized modification of thread parameters achieves vibration control without requiring high precision across the entire thread structure.
Solution Approach 2:
The thread connection combines rigid thread elements with elastic displacement capability, creating a composite mechanical system. This composite approach allows the rigid threads to provide structural strength while the elastic element accommodates manufacturing tolerances and provides continuous contact, reducing vibration without demanding extremely tight manufacturing precision on all components.
3Object-affected harmful factors
If an elastically displaceable thread section is implemented, then axial play is reduced and noise is dampened, but the device complexity increases
Solution Approach 1:
The elastic displacement capability is merged directly into the thread connection itself, rather than being a separate component. The thread structure incorporates elastic elements or elastic geometry that provides the displacement capability as an integrated feature. This merging approach reduces the number of separate components and simplifies the overall device structure while still achieving noise dampening through elastic compliance.
Solution Approach 2:
The thread parameters (tooth width, pitch width) are varied to create inherent elastic displacement capability within the thread engagement. By changing the geometric parameters of the thread, the connection gains the ability to elastically deform and compensate for axial play. This parameter-based solution achieves the desired noise reduction through geometric design rather than adding complex mechanical elastic components.
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 effectively reduces noise emissions and vibration transmission, enhancing the operational quietness and stability of the lawn mower, while maintaining easy height adjustment and self-locking functionality, thus improving user experience and reducing maintenance needs.
Implementation Method 1
one thread section, in particular an elastically displaceable thread section, preferably a thread section that is elastically displaceable radially to the thread axis
Implementation Method 2
reduces axial play between the threads, thereby dampening vibrations and noise
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a lawnmower (11), in particular an autonomous lawnmower (11), comprising at least a chassis (45), a motor (15) for driving a cutting device (200) and a height adjustment device (16) for displacing the cutting device (200) and the motor (15) relative to the chassis (45), at least for setting a working height (h) of the cutting device (200) relative to the chassis (45), in particular for setting a cutting height (s) of a cutting tool (18) of the cutting device (200), wherein the height adjustment device (16) comprises a rotating body (118), in particular a hollow cylindrical body, and a sliding seat (204) surrounding the rotating body (118), the sliding seat having corresponding threads (206, 208), so that a rotation of the rotating body (118) causes a linear displacement of the sliding seat (204).It is proposed that at least one of the threads (206, 208) has at least two thread sections (236, 238), wherein one thread section (236), in particular an elastically displaceable thread section (236), preferably a thread section (236) that is elastically displaceable radially to the thread axis, comprises means which increase a thread tooth width (b1) of the one thread section (236) and/or decrease a thread pitch width (g1) of the one thread section (236) and/or cause an offset (a1) of a flank (242) and/or an offset of a pitch (P1) of the one thread section (236) compared to the further thread section (238).