Handle Height Adjustment Device Using Toothed Disk Mechanism

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Solution Overview

Problem

Existing handle height adjustment devices for walk-behind power tools are complex, costly, and require additional components like springs for active separation, making them difficult to manufacture and assemble.

Innovation Solution

A handle height adjustment device using toothed disk members and a disk interconnecting member with interconnection mechanisms, allowing for easy rotation and separation without a spring, featuring a snap-fit connection and threaded interconnection, which simplifies manufacturing and assembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a spring element is used to achieve active separation of disk members, then the handle height adjustment device can separate disk members automatically, but the device complexity increases and manufacturing cost increases

Engineering Contradiction:

Improveautomatic separation of disk membersVSAvoidnumber of parts

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent removes the spring element from the system entirely, extracting the problematic component that caused complexity. Instead of using a spring for active separation, the invention uses a threadable rod that can be manually operated to separate and engage the toothed disk members, thereby simplifying the device while maintaining the core functionality of height adjustment.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The handle height adjustment device is designed to be self-servicing through the threadable rod mechanism. The operator directly manipulates the rod to engage or disengage the toothed disks, eliminating the need for additional actuating mechanisms like springs. The system serves itself through direct manual operation, reducing overall device complexity.

Inventive Principle:

Principle #25Self-service

2Ease of operation

If a spring element is used to achieve active separation of disk members, then the handle height adjustment device can separate disk members automatically, but the manufacturing cost increases

Engineering Contradiction:

Improveautomatic separation of disk membersVSAvoidmanufacturing cost

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

By removing the spring element from the design, the patent eliminates the associated manufacturing costs of sourcing, assembling, and maintaining spring components. The threadable rod mechanism uses simpler, more cost-effective parts that are easier to manufacture and assemble, directly reducing production costs.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention employs simpler, less expensive components such as the threadable rod and toothed disks made from durable but cost-effective materials. These components are designed for straightforward manufacturing and assembly, reducing overall production costs compared to spring-based mechanisms.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Adaptability or versatility

If multiple separate parts are used in the handle assembly, then the handle height adjustment device can be flexible and adjustable, but the assembly becomes more complex and time-consuming

Engineering Contradiction:

Improvehandle height adjustabilityVSAvoidnumber of separate parts

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple functions into integrated components. The threadable rod serves both as a positioning mechanism and as a direct engagement tool for the toothed disks. The toothed disks themselves are integrated with the handle arms, reducing the number of separate parts while maintaining full adjustability functionality.

Inventive Principle:

Principle #5Merging (Combining)

4Ease of operation

If a spring element is used in the handle height adjustment device, then active separation is achieved, but the assembly process becomes more difficult

Engineering Contradiction:

Improveactive separation of disk membersVSAvoidassembly process

Core Design Contradiction:

Ease of operationVSEase of manufacture

Solution Approach 1:

The patent eliminates the spring element that complicated the assembly process. The threadable rod mechanism allows for straightforward assembly where components are simply threaded together and engaged, without requiring precise installation of spring elements or additional fastening steps.

Inventive Principle:

Principle #2Taking out (Extraction)

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 provides a robust, cost-effective, and easy-to-use handle height adjustment mechanism that reduces the number of parts, enhancing rigidity and ease of assembly while eliminating the need for springs, resulting in a more efficient and affordable manufacturing process.

Implementation Method 1

Rotation of the disk interconnecting member in a first direction about the axis of rotation moves the handle height adjustment device towards the locked state, and rotation of the disk interconnection member in a second direction, opposite to the first direction, moves the handle height adjustment device towards the open state

Methodology Applied

Scientific EffectRotation:

Implementation Method 2

The disk interconnecting member is arranged to be connected to the first toothed disk member by means of a first interconnection mechanism, which first interconnection mechanism inhibits relative movement between the disk interconnecting member and the first toothed disk member along the axis of rotation

Methodology Applied

Scientific EffectMechanical constraint:

Implementation Method 3

The disk interconnecting member is arranged to be threadably connected to the second toothed disk member by means of a second interconnection mechanism

Methodology Applied

Scientific EffectThreaded connection: Screw

Implementation Method 4

a first toothed disk member arranged to be affixed to a first arm element of the handle assembly, a second toothed disk member arranged to be affixed to a second arm element of the handle assembly

Methodology Applied

Scientific EffectGear meshing: Gear

Data Source

PatentUS8984718B2Handle height adjustment device of walk-behind power tool, a handle assembly and a walk-behind power tool comprising such a device

Publication Date: 2015.03.24 HUSQVARNA AB

AI summary

A handle height adjustment device of a handle assembly (2) of a walk-behind power tool (1). The handle height adjustment device (100) comprises a first toothed disk member (200), a second toothed disk member (300), and a disk interconnecting member. The disk interconnecting member (400) is arranged to be connected to the first toothed disk member (200) by means of a first interconnection mechanism (401), which first interconnection mechanism (401) inhibits relative movement between the disk interconnecting member (400) and the first toothed disk member (200) along an axis of rotation (500) of the handle height adjustment device (100), and which first interconnection mechanism (401) allows the disk interconnecting member to rotate relative the first toothed disk member about the axis of rotation (500). The disk interconnecting member (400) is arranged to be threadably connected to the second toothed disk member (300) by means of a second interconnection mechanism (402). The application also concerns a handle assembly and a walk-behind power tool comprising such a device.