Trigger Mechanism with Lost-Motion Coupling for Cordless Nailers
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Solution Overview
Problem
Existing cordless nailers are often cumbersome due to their size and weight, require expensive non-refillable fuel cartridges, and have complex designs that lead to inconsistent fastening performance.
Innovation Solution
A hand-held fastening tool with a housing, motor, control unit, and trigger mechanism that includes a microswitch, actuator arm, and spring for precise control, allowing for a lost-motion coupling that enables efficient power transmission and consistent fastener driving without the need for external hoses or complex fuel systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If cordless nailers use large battery packs and motor assemblies to provide sufficient power, then power delivery is improved, but weight and size increase making the tool cumbersome
Solution Approach 1:
The power system is segmented into a reusable battery pack and a separate motor assembly that can be independently optimized. The motor assembly contains the motor, flywheel, and driver mechanism, while the battery pack is a removable power source, allowing users to carry multiple lightweight battery packs rather than one large heavy battery.
Solution Approach 2:
The flywheel mechanism dynamically stores and releases energy during operation, allowing the motor to operate at lower average power levels while still delivering high peak power when needed. The flywheel accumulates kinetic energy during the return stroke and releases it during the driving stroke, reducing the continuous power requirements of the motor.
2Ease of operation
If cordless nailers use complex fuel cartridge systems to provide power, then portability is improved, but cost increases and reliability decreases due to expensive non-refillable cartridges
Solution Approach 1:
The system uses rechargeable battery packs that can be recharged at the work site using standard electrical outlets, eliminating the need to leave the work site to purchase additional fuel cartridges. The battery packs are designed to be user-replaceable and rechargeable, providing self-service capability.
Solution Approach 2:
Instead of discarding exhausted fuel cartridges, the system recovers energy through rechargeable battery packs that can be recharged and reused multiple times. The modular design allows exhausted battery packs to be replaced with charged ones and then recharged later, recovering the value of the power source.
3Weight of moving object
If cordless nailers use simplified designs to reduce weight and cost, then portability and affordability are improved, but fastening consistency deteriorates
Solution Approach 1:
The flywheel is pre-charged with kinetic energy before each driving cycle, ensuring that sufficient energy is available for consistent fastener driving. The return mechanism pre-positions the driver and charges the flywheel during the return stroke, so that when the trigger is pulled, the fastening operation has the necessary energy储备 for consistent performance.
Solution Approach 2:
The trigger mechanism incorporates a safety interlock system that monitors the position of the driver and the charge state of the flywheel before allowing operation. The contact trip mechanism ensures that the nosepiece is in proper contact with the workpiece before the fastening cycle initiates, providing feedback control to ensure consistent fastening results.
4Reliability
If cordless nailers use heavy-duty motors and robust mechanisms to ensure reliable fastening, then fastening reliability is improved, but device complexity increases leading to higher manufacturing costs
Solution Approach 1:
The fastening mechanism operates in periodic cycles consisting of a power stroke and a return stroke. During the return stroke, the driver is reset and the flywheel is recharged. This periodic operation allows the use of lighter components that can handle the repeated cyclic loads rather than requiring continuously heavy-duty components.
Solution Approach 2:
The high-stress components such as the motor, flywheel, and driver mechanism are extracted into a separate motor assembly that can be optimized independently from the rest of the tool. This allows the use of robust components only where needed while keeping the overall tool design simpler and lighter.
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 tool provides improved flexibility, reduced weight, and cost-effectiveness by using a rechargeable battery pack and a simplified design that ensures consistent and reliable fastening performance, addressing the limitations of existing cordless nailers.
Implementation Method 1
The actuator arm is biased by the spring toward the microswitch. The spring is configured to move the actuator arm against the microswitch to cause the microswitch to operate in an actuated switch state.
Implementation Method 2
A hand-held fastening tool with a housing, motor, control unit, and trigger mechanism that includes a microswitch, actuator arm, and spring for precise control
Data Source
AI summary
A driving tool with a housing, a motor received in the housing, a control unit and a trigger. The housing defines a handle. The control unit is configured to operate the motor and has a microswitch, an actuator arm and a spring. The actuator arm is biased by the spring toward the microswitch. The spring is configured to move the actuator arm against the microswitch to cause the microswitch to operate in an actuated switch state. The trigger is coupled to the handle and is movable between a first trigger position and a second trigger position. The trigger has a switch arm that cooperates with the actuator arm to form a lost-motion coupling that permits a predetermined amount of movement of the trigger from the first trigger position to the second trigger position before coupling the switch arm to the actuator arm. The actuator member does not contact the microswitch when the trigger is in the second trigger position so that the microswitch operates in a nominal switch state.