Reciprocating Tool Motor Control for Low-Battery Stroke Completion
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Solution Overview
Problem
In reciprocating tools like electric nailers, when battery voltage falls below a certain threshold during operation, the reciprocating member can stop in an inappropriate position, leading to operational inefficiencies.
Innovation Solution
A control circuit adjusts the drive signal to reduce motor current, allowing the electric motor to continue operating even when battery voltage drops below a threshold, ensuring the reciprocating member does not stop in an inappropriate position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motor is stopped when battery voltage falls below the first threshold voltage, then power consumption is reduced and battery is protected, but the reciprocating member stops in an inappropriate position causing operational inefficiency
Solution Approach 1:
The control circuit detects the battery voltage before the motor stops and preliminarily adjusts the drive signal to reduce motor current when voltage falls below the first threshold. This preliminary action allows the motor to continue operating at reduced power, preventing the reciprocating member from stopping in an inappropriate position while still protecting the battery from complete depletion
Solution Approach 2:
The system changes the operating parameters by switching from normal drive signal operation to reduced power operation when battery voltage drops. The control circuit modifies the drive signal parameters (duty cycle, frequency) to reduce motor current consumption, enabling the motor to continue functioning at lower power levels and complete the reciprocating member's stroke cycle
2Productivity
If the motor continues to operate at full power when battery voltage drops, then the reciprocating member completes its stroke cycle, but the battery depletes faster and may cause voltage instability
Solution Approach 1:
The system dynamically adjusts motor power consumption based on real-time battery voltage conditions. The control circuit continuously monitors battery voltage and dynamically modifies the drive signal characteristics, transitioning from full power operation to reduced power operation as voltage drops, thereby optimizing the balance between completing the stroke cycle and conserving battery energy
Solution Approach 2:
The control circuit implements feedback control by continuously monitoring battery voltage and adjusting the drive signal accordingly. When voltage falls below the first threshold, the feedback mechanism triggers reduced power operation mode, and when voltage recovers above the second threshold, it restores normal operation, creating a closed-loop system that optimizes battery usage while ensuring task completion
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 prevents the reciprocating member from stopping inappropriately, maintaining tool functionality despite battery voltage fluctuations.
Implementation Method 1
an electric motor configured to generate a driving force
Implementation Method 2
a drive circuit configured (i) to receive a drive signal for driving the electric motor, and (ii) to deliver a motor current from a battery to the electric motor
Data Source
AI summary
One aspect of the present disclosure provides a reciprocating tool including a reciprocating member, an electric motor, a transmission device, a drive circuit, and a control circuit. The transmission device transmits a driving force of the electric motor to the reciprocating member at least in a stroke of the reciprocating member from second dead center to first dead center. The drive circuit delivers a motor current from a battery to the electric motor to thereby drive the electric motor in accordance with a drive signal received. The control circuit adjusts the drive signal, in response to a first condition being satisfied, such that the drive circuit reduces the motor current to thereby continue to drive the electric motor. The first condition is satisfied in response to (i) the drive circuit driving the electric motor, and (ii) a battery voltage falling below a first threshold voltage.