Rotary Input Control for Power Tool Intuitive Operation
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Solution Overview
Problem
Current power tools require users to linearly actuate a switch to control rotational motion, making it difficult to intuitively compare trigger travel to output rotation and adjust speed, and also struggle with assessing joint tightness, leading to reactionary torque and inefficient control.
Innovation Solution
A power tool design that includes a rotational motion sensor to monitor and control the output member's rotation based on detected rotational motion, allowing for intuitive operation similar to a manual screwdriver, with a controller driving the motor in the same direction as the tool's rotation and providing feedback mechanisms for improved control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a linear trigger switch is used to control rotational motion, then the tool can be operated with simple switch actuation, but the user cannot intuitively compare trigger travel to output rotation and make quick speed adjustments
Solution Approach 1:
The patent combines the control input mechanism with the output mechanism by allowing the user to directly rotate the tool housing to control the output member's rotation. This merging of control and output axes eliminates the need for separate trigger actuation and provides intuitive control where the user can directly compare input rotation to output rotation, resolving the contradiction between ease of operation and device complexity
Solution Approach 2:
Instead of using linear trigger actuation to control rotational output, the patent inverts the control method by using rotational input of the housing to control rotational output of the member. This inversion allows the user to directly manipulate the tool in the same motion type (rotation) that produces the output, achieving intuitive control without complex mechanisms
2Reliability
If the user increases bias force to maintain tool stationarity against reactionary torque, then the tool can remain stationary, but the user experiences increased wrist strain and delayed assessment of joint tightness
Solution Approach 1:
The patent incorporates feedback mechanisms including tactile feedback from the rotational control and visual feedback from indicators that show the relationship between input rotation and output position. This feedback allows the user to assess joint tightness immediately through the control mechanism itself rather than waiting for reactionary torque to build up in the wrist, maintaining reliable control while improving ease of operation
Solution Approach 2:
The rotational control mechanism acts as an intermediary between the user and the output member, providing a mechanical advantage system that reduces the force the user must apply. The gear train and other transmission elements serve as intermediaries that translate small rotational inputs into precise output control without requiring the user to directly counteract full reactionary torque, thereby reducing wrist strain while maintaining control reliability
3Speed
If a digital switch provides full output immediately, then the tool responds quickly to activation, but the user lacks fine control for speed adjustments
Solution Approach 1:
The patent implements dynamic control where the output speed is continuously adjustable based on the user's rotational input speed and position. Rather than providing fixed full output or discrete speed levels, the system dynamically adapts the output speed to match the user's manual rotation speed, providing both quick response when rotated rapidly and fine control when rotated slowly, thereby resolving the contradiction between response speed and ease of operation
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 control by allowing direct comparison of rotational motion and speed adjustments, reducing reactionary torque and improving the assessment of joint tightness, resulting in more intuitive and efficient operation.
Implementation Method 1
a rotational motion sensor arranged in the housing at a location spatially separated from the output member and operable to detect rotational motion of the housing about the longitudinal axis of the output member
Data Source
AI summary
A power tool includes a housing, a motor, an output member driven by the motor, and a reaming attachment coupled to the output member. The reaming attachment has a front end portion selectively driven in rotation by the output member to drive a fastener into a workpiece, and a reaming portion selectively driven in rotation by the output member to remove material from an end surface of a conduit. A rotational motion sensor in the housing is operable to detect rotational motion of the housing about an axis. A controller receives a signal indicative of rotational motion from the sensor, determines a direction of the rotational motion of the housing, and drives the motor in a direction corresponding to the direction of rotational motion of the housing.