Router Switch Control with Selective NVR Disable
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Solution Overview
Problem
When a power tool, such as a router, is used in a configuration where the switching mechanism is inaccessible, the no-voltage release (NVR) function of the primary switch is triggered by a power outage, preventing the secondary switch from being used to turn the tool back on, posing safety and convenience issues for the operator.
Innovation Solution
A selective disabling mechanism is provided to disable the NVR function of the primary switch when the power tool is in a predetermined configuration, allowing the secondary switch to function independently, ensuring the NVR function is maintained only when the tool is in that configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary switch with NVR function is provided on the power tool housing, then safety is improved through automatic power cutoff during power outages, but the switch becomes inaccessible and creates operational difficulties when the tool is used in certain configurations
Solution Approach 1:
The switching function is segmented into two independent switches: a primary switch on the power tool housing and a secondary switch on the switchbox. Each switch can independently control the power supply to the motor, allowing the tool to be operated safely from either location depending on the working configuration.
Solution Approach 2:
A control circuit acts as an intermediary between the two switches and the motor. The control circuit receives signals from either switch and controls the power supply accordingly, enabling coordinated operation of both switches while maintaining the NVR function of the primary switch.
2Reliability
If the NVR function is activated on the primary switch, then automatic power cutoff during power outages is achieved, but the secondary switch cannot be used to turn the tool back on after a power outage
Solution Approach 1:
The control circuit dynamically responds to signals from either switch based on the current state of the system. When the secondary switch is used during normal operation, it controls power supply independently. When a power outage occurs, the primary switch's NVR function activates, and the control circuit ensures the tool can be restarted through either switch.
Solution Approach 2:
The control circuit provides feedback about the operational state of the motor and power supply to both switches. This feedback mechanism allows the system to understand whether a power interruption was caused by a power outage or by the secondary switch, enabling appropriate response behavior.
Data Source
AI summary
The invention relates to a power tool (2), a kit of parts, and method of controlling the operation of the same depending upon the configuration of use of the power tool (2) at an instant of time. The power tool (2) can, in one embodiment be a router power tool to perform work on a workpiece (32), and switching means (28, 42) allow the selective operation of the power tool (2) by controlling an electrical power source. First switching means (28) include a no Voltage release (NVR) function and means are provided to selectively disable the NVR function of the first switching means (28) when the power tool (2) is used in at least one predetermined configuration. Typically, this allows second switching means (42) which include a NVR function to be used to control the power to the tool (2). A fence body for use with a router is also disclosed.