Electric Screwdriver Startup Circuit with Shaft-Driven Detection

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Solution Overview

Problem

Current electric screwdrivers require continuous operation of a switch assembly for extended use, which is inconvenient and reduces user efficiency.

Innovation Solution

An electric screwdriver design featuring a startup circuit with a switch assembly and an activation assembly, where the output shaft drives a detection element to rotate and interact with an activation element, allowing the motor to start only when the detection element is activated and the switch is on.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a switch assembly is continuously operated to drive the output shaft to rotate, then the electric screwdriver can maintain continuous operation, but the user convenience deteriorates and working efficiency reduces due to the need to keep operating the switch assembly for extended periods

Engineering Contradiction:
Improveworking efficiencyVSAvoiduser convenience
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The electric screwdriver automatically detects when the output shaft is being driven and activates the motor accordingly, eliminating the need for continuous manual switch operation. The detection element senses the rotational motion of the output shaft and automatically starts the motor when driven, allowing the system to serve itself without constant user intervention.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The detection element provides feedback about the state of the output shaft to the control circuit. When the output shaft is driven (indicating work is needed), the detection element activates the motor through the control circuit, creating a feedback loop that automatically responds to operational needs without requiring continuous switch input.

Inventive Principle:
Principle #23Feedback

2Ease of operation

If the motor starts automatically when the output shaft is driven, then user convenience and working efficiency improve, but the device complexity increases due to the addition of detection elements and control circuits

Engineering Contradiction:
Improveuser convenienceVSAvoidstructure complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the purely mechanical switch assembly with a sensor-based detection element that automatically detects the state of the output shaft. This substitution of mechanical operation with sensor detection and electronic control reduces the need for continuous manual intervention while managing the added complexity through automated sensing and control mechanisms.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If the detection element is activated by the output shaft during rotation, then the motor starts automatically reducing power consumption, but the manufacturing precision requirements increase for the detection element and activation element alignment

Engineering Contradiction:
Improvepower consumptionVSAvoidalignment precision
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The detection element and activation element are pre-positioned and pre-aligned during manufacturing so that when the output shaft rotates during normal operation, the detection element automatically activates the motor. This preliminary positioning ensures that the automatic activation occurs at the correct moment without requiring high-precision alignment adjustments during operation.

Inventive Principle:
Principle #10Preliminary action

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 design enhances user convenience and efficiency by allowing the electric screwdriver to start automatically when the output shaft is driven, reducing the need for continuous switch operation and minimizing power consumption.

Implementation Method 1

an activation assembly including a detection element connected to the electric motor electrically or through a signal, and an activation element configured to activate the detection element. The output shaft is capable of driving the detection element, and the detection element includes at least one activated state during movement

Methodology Applied
Scientific EffectMagnetic field interaction: Magnetic Field

Data Source

PatentEP4257289B1Electric screwdriver
Publication Date: 2025.05.07 NANJING CHERVON IND
  • EP4257289B1 patent drawingFigure 1
  • EP4257289B1 patent drawingFigure 2
  • EP4257289B1 patent drawingFigure 3

AI summary

Provided is an electric screwdriver. The electric screwdriver includes a housing; an electric motor including a motor shaft rotatable about a motor axis; an output assembly including an output shaft movable forward and backward along a direction of a first axis; and a transmission assembly configured to transmit the power outputted by the motor shaft to the output shaft. The electric screwdriver further includes a startup circuit configured to start the electric motor. The startup circuit includes a switch assembly controlling the on state of the startup circuit; and an activation assembly including a detection element electrically connected to the electric motor or connected to the electric motor through a signal and an activation element configured to activate the detection element. The output shaft is capable of driving the detection element to move. The detection element includes one activated state during movement. When the detection element is in the activated state and the switch assembly is on, the electric motor starts.