Variable Speed Tool Automatic Gearshift via Torque Sensing Ring
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Solution Overview
Problem
Existing variable speed tools, such as electric drills and hammer drills, require manual operation to adjust rotational speed and torque, which is not user-friendly and lacks stability at varying load conditions.
Innovation Solution
A variable speed tool with a gearshift device that automatically adjusts rotating speed and torque using a torque sensing ring and gearshift fork, driven by springs, which moves along a sliding groove to change engagement with a multistage gear train, allowing for automatic speed and torque adjustments based on load torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a manual speed changing mechanism is used, then the operator can adjust rotational speed, but the operator must constantly watch the operation condition and variation of load to determine timing for adjustment
Solution Approach 1:
The gearshift device automatically adjusts the transmission ratio based on load torque variations without requiring operator intervention. The torque sensing ring detects load changes and triggers axial movement of the gearshift fork to change gear engagement, making the system self-regulating and eliminating the need for constant operator monitoring.
Solution Approach 2:
The system incorporates a torque sensing ring that continuously monitors load torque and provides feedback to the gearshift mechanism. When load torque reaches a predetermined value, the torque sensing ring rotates and activates the gearshift fork to automatically change the transmission ratio, creating a closed-loop control system that responds to actual operating conditions.
2Ease of operation
If a manual speed changing mechanism is used, then the operator can adjust rotational speed, but the operation is not friendly to the operator
Solution Approach 1:
The gearshift device automatically adjusts the transmission ratio based on load torque variations without requiring operator intervention. The torque sensing ring detects load changes and triggers axial movement of the gearshift fork to change gear engagement, making the system self-regulating and eliminating the need for constant operator monitoring.
3Reliability
If the gearshift device automatically adjusts speed based on load torque, then the tool can stably work at high speed low torque and low speed high torque states, but the mechanism becomes more complex
Solution Approach 1:
The torque sensing ring acts as an intermediary between the load torque and the gearshift mechanism. It converts torque variations into rotational movement that triggers the gearshift fork's axial displacement, providing a smooth and reliable transition between different transmission ratios without requiring complex control systems.
Solution Approach 2:
The patent replaces manual mechanical operation with an automatic mechanical sensing and actuation system. The torque sensing ring and spring mechanism automatically detect load changes and trigger gear shifts, eliminating the need for manual intervention while maintaining a relatively simple mechanical structure.
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
Enables stable operation at both high-speed low-torque and low-speed high-torque conditions without manual intervention, ensuring consistent performance by automatically adjusting the gearshift mechanism in response to changing load torque.
Implementation Method 1
a first spring member which drives the gearshift fork in an axial direction of the gearshift ring
Implementation Method 2
A second spring member is arranged between the torque sensing ring and the housing. When a load of the outputting shaft reaches a predetermined value, the torque sensing ring overcomes a spring force of the second spring member and rotates
Data Source
AI summary
The present invention has disclosed a variable speed tool and a variable speed control method. The tool includes a switch; a gearbox housing; a motor; an outputting shaft; a multistage transmitting gear train and a gearshift ring which are mated with the motor and the outputting shaft, the gearshift ring having inner teeth; a gearshift fork mated with the gearshift ring; a tension spring arranged between the gearbox housing and the gearshift fork; and a torque sensing ring provided with a sliding groove in which the gearshift fork is movably disposed. When the load of the outputting shaft has reached to a predetermined value, the torque sensing ring makes the gearshift fork move axially in the sliding groove under the action of the tension spring, thus bringing the gearshift ring to move axially. The variable speed tool of the present invention may automatically adjust the rotating speed and the torque of the outputting shaft according to a variation of the load torque.