Movable Switch Bridge Vibration Gap in Handheld Work Apparatus
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Solution Overview
Problem
Handheld work apparatuses with internal-combustion engines face challenges in accurately setting throttle and choke valve positions due to relative movement between the carburetor and operator-controlled switch, leading to increased assembly and servicing work, as well as the need for complex electric leads that are prone to mechanical stress and re-routing during maintenance.
Innovation Solution
Incorporating an anti-vibration element and contact springs that bridge the vibration gap between assemblies, eliminating the need for electric leads and allowing the switch to compensate for positional tolerances, resulting in a simpler and more robust structure with reduced assembly and servicing work.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the carburetor is decoupled from the internal-combustion engine via antivibration elements, then vibration is reduced, but the position of the operator-controlled switch relative to the carburetor changes during operation, making it impossible to set throttle and choke valve positions with required accuracy
Solution Approach 1:
The patent makes the operator-controlled switch movable relative to the carburetor instead of fixed. The switch can move within a limited range to compensate for relative position changes between the carburetor and engine caused by vibrations. This dynamic adjustment capability ensures that the switch maintains accurate alignment with the throttle and choke valves despite vibration-induced displacement.
2Manufacturing precision
If the operator-controlled switch is fixed relative to the carburetor, then precise setting of throttle elements is possible, but electric leads must be routed via the vibration gap, requiring large amounts of assembly work and making leads susceptible to mechanical loads
Solution Approach 1:
The switch is designed to move relative to the carburetor, allowing it to maintain accurate positioning without requiring fixed mounting. This eliminates the need for electric leads to bridge the vibration gap, as the switch moves with the carburetor assembly. The movable design simplifies the electrical connection system while preserving positioning accuracy.
3Reliability
If electric leads are used to connect the switch to the ignition module, then electrical connection is established, but the leads are subjected to very high mechanical loads due to relative movement, requiring detachment and re-laying during servicing
Solution Approach 1:
The operator-controlled switch is designed to move together with the carburetor assembly relative to the engine, eliminating the need for long electric leads that would be subjected to repeated mechanical stress. The switch maintains electrical connection through its movable design, and the reduced lead length or integrated connection minimizes mechanical loads, allowing the leads to remain intact during routine servicing operations.
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 solution ensures reliable electrical contact across varying positions, reduces assembly and maintenance work, and prevents permanent deformations of contact springs, thereby enhancing the operational accuracy and durability of the handheld work apparatus.
Implementation Method 1
an anti-vibration element; the first assembly and the second assembly movably mounted with respect to the first assembly via the anti-vibration element
Implementation Method 2
the at least one first contact element and the at least one second contact element being configured to bridge the vibration gap when the switch is closed
Implementation Method 3
the switch including at least one first contact element and at least one second contact element... the at least one first contact element and the at least one second contact element being configured to bridge the vibration gap when the switch is closed
Implementation Method 4
Contact elements of an electric switch can easily be configured such that, besides the usual production tolerances, the positional tolerances that ensue because of the relative movement over the vibration gap are also compensated
Data Source
AI summary
A work apparatus has a first and a second assembly. The second assembly is mounted movably in relation to the first assembly via at least one antivibration element. Formed between the first assembly and the second assembly is a vibration gap, which is bridged by the antivibration element. The work apparatus has a switch, for actuation by an operator, which includes a first contact element and a second contact element. When the switch is closed, the first contact element and the second contact element contact each other. When the switch is open, the first and second contact element do not establish an electrically conductive contact. The second contact element is part of the second assembly. The first contact element is part of the first assembly and, when the switch is closed, the first contact element and the second contact element bridge the vibration gap between the first and second assembly.