Handheld Trigger Interlock Using a Selective Transfer Linkage
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Solution Overview
Problem
The existing handheld work apparatuses face damage to the first actuating element due to forceful actuation when the device falls, as the second actuating element is not pressed, leading to unintended actuation of the first actuating element with high force.
Innovation Solution
The first actuating element acts on the blocking device via a transfer unit, and the second actuating element controls the transfer unit to establish an operative connection between the first actuating element and the blocking device, allowing independent actuation of both elements, with the blocking device being enabled only when both are in their actuated positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the first actuating element is directly connected to the blocking device, then the structure is simple, but the first actuating element can be damaged by forceful actuation when the device falls
Solution Approach 1:
The patent introduces a transfer unit as an intermediary component between the first actuating element and the blocking device. This transfer unit includes a transfer element that can be acted upon by the first actuating element, and a second actuating element that controls whether the transfer element can transmit force to the blocking device. The intermediary structure prevents direct force transmission from the first actuating element to the blocking device, thereby protecting against damage while maintaining operational functionality.
2Reliability
If the second actuating element controls the transfer unit to establish operative connection, then the first actuating element is protected from damage, but the device complexity increases
Solution Approach 1:
The transfer unit is designed with a nested structure where the transfer element can be positioned in different states. When the second actuating element is not actuated, the transfer element is held in a position that prevents force transmission. When the second actuating element is actuated, it releases the transfer element to allow force transmission. This nested arrangement allows the protective mechanism to be integrated within the existing actuating element structure, minimizing additional complexity.
3Reliability
If both actuating elements must be actuated to enable the operator-controlled element, then the first actuating element is protected, but the ease of operation is reduced
Solution Approach 1:
The second actuating element performs a preliminary action by controlling the state of the transfer unit before the first actuating element can effectively actuate the blocking device. By requiring the second actuating element to be in its actuated position first, the system prepares the transfer unit to either allow or prevent force transmission. This preliminary control mechanism ensures that even if the first actuating element is actuated forcefully, the protective function is already in place, while the dual-actuation requirement maintains operational safety.
Data Source
AI summary
A first actuating element acts on a blocking device for an operator-controlled element for controlling the drive motor. In an enabled position of the blocking device, the operator-controlled element is enabled to control the drive motor. In a blocking position the blocking device mechanically blocks any actuation of the operator-controlled element. The first element acts on the blocking device via a transfer unit. In an actuated position of a second actuating element, the transfer unit establishes an operative connection between the first element and the blocking device, such that the blocking device is in the enabled position in the actuated position of the first element and is in the blocking position in the non-actuated position of the first element. In the non-actuated position of the second actuating element, the transfer unit is ineffective so that the blocking device is in the blocking position regardless of the first element's position.