Electrostatic Clutch Assembly for Adjustable Power Tool Torque
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power tools face issues with mechanical and electronic clutches that suffer from wear, bulkiness, weight, complexity, inaccuracy, and continuous power requirements, leading to inefficiencies and increased costs.
Innovation Solution
An electrostatic clutch assembly for power tools that uses a control circuit to apply varying voltages across electrodes, generating attractive forces to manage torque transmission, allowing for adjustable torque settings and efficient power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical clutch is used to interrupt power transmission when torque exceeds a threshold, then torque limiting is achieved, but the device adds excessive bulk and weight to the power tool
Solution Approach 1:
The patent replaces the traditional mechanical clutch system with an electrostatic clutch that uses electrostatic forces between charged electrodes to control torque transmission. This substitution eliminates heavy mechanical components like springs, balls, and clutch plates, significantly reducing the weight and bulk of the power tool while maintaining torque limiting functionality through electrical field control
2Adaptability or versatility
If a mechanical clutch with adjustable torque settings is used, then user-adjustable torque control is achieved, but the components wear over time
Solution Approach 1:
The electrostatic clutch replaces mechanical wear components with electrostatic fields for torque control. The adjustable torque settings are achieved by varying the voltage applied to the electrodes rather than through mechanical adjustment mechanisms, eliminating wear from friction, springs, and moving parts while maintaining full adjustability
Solution Approach 2:
The patent changes the physical state from mechanical contact to electrostatic field interaction. By varying the electrical voltage parameter applied to the electrodes, the torque threshold is adjusted without any mechanical movement or contact, eliminating wear while preserving adaptability across multiple torque settings
3Reliability
If an electronic clutch is used to sense and interrupt power transmission, then torque control is achieved, but the system becomes overly complex and inaccurate due to latency in sensing current at the motor module
Solution Approach 1:
The electrostatic clutch provides direct torque control at the transmission level without relying on current sensing and electronic processing. By using electrostatic forces to directly engage and disengage torque transmission, the system eliminates the complexity of torque sensors, microcontrollers, and communication protocols while improving response time and accuracy
Solution Approach 2:
The electrostatic clutch acts as an intermediary between the motor and output shaft, providing direct mechanical coupling control through electrostatic fields. This intermediary approach eliminates the need for complex electronic sensing and processing systems, simplifying the overall control architecture while maintaining precise torque control
4Power
If electromagnetic or magnetorheological clutches are used to provide fast activation and large torques, then torque density is improved, but continuous electrical power is required which increases weight due to large batteries
Solution Approach 1:
The electrostatic clutch operates by applying voltage only when torque control is needed, rather than requiring continuous power. The electrostatic field can be rapidly activated and deactivated, providing fast response similar to electromagnetic clutches but without the need for continuous power consumption, thereby reducing battery size and weight
Solution Approach 2:
The patent changes the energy state from continuous electromagnetic field maintenance to on-demand electrostatic field activation. By storing energy in capacitors and releasing it only when needed for torque control, the system achieves high torque density with intermittent power usage, significantly reducing the continuous power requirements and associated battery weight
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 electrostatic clutch provides precise torque control, reduces weight and complexity, and eliminates the need for continuous power, enhancing the performance and efficiency of power tools.
Implementation Method 1
A control circuit is operatively cooperable with the electrostatic clutch assembly to control electrical power delivery from the electrical power source to the first and second electrodes. In a first mode of operation, the control circuit causes a first voltage to be applied to the first electrode and a different second voltage to be applied to the second electrode, generating a first attractive force between the first and second electrodes
Data Source
AI summary
A power tool that includes a housing, a motor, an end effector, an electrostatic clutch assembly, and a control circuit is provided. In a first mode of operation, the control circuit causes a first voltage to be applied to a first electrode and a different second voltage to be applied to a second electrode, generating a first attractive force between the first and second electrodes, which causes an output member to rotate together with an input member when a torque on the output member is less than or equal to a first threshold value and which causes the output member to rotationally slip relative to the input member when the torque on the output member exceeds the first threshold value, interrupting torque transmission from the input member to the output member.