Stepper-Motor Gear Selection for Core Drill Speed-Torque Matching
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Solution Overview
Problem
Core drilling machines face challenges in precisely coordinating the rotational speed and torque of the tool bit with varying core bit diameters and material hardness, leading to inefficient or damaging drilling processes due to the complexity of selecting the appropriate gear.
Innovation Solution
A method involving an operating device with a signal transmitter and sensor system, a stepping motor, and a shift fork to electronically change the gear and rotational speed of the electric motor, allowing for precise gear selection and torque adjustment without mechanical gear changes, using a shifting energy storage means to preselect gears for engagement when mechanical alignment is not possible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual gear selection is used in core drilling machines, then the device structure remains simple, but the coordination of rotational speed and torque with varying core bit diameters becomes imprecise and complicated for the user
Solution Approach 1:
The patent replaces the purely mechanical gear selection system with an electromechanical system. A sensor detects the position of the operating device (rotary switch), and this positional information is transmitted to a control unit that automatically adjusts the rotational speed of the electric motor. This substitution of mechanical linkage with electronic sensing and control achieves precise coordination between gear position and motor speed without requiring complex mechanical coupling mechanisms.
Solution Approach 2:
The patent implements a feedback mechanism where a sensor continuously monitors the position of the operating device and transmits this information to the control unit. The control unit uses this feedback to automatically adjust the motor rotational speed to match the selected gear ratio. This closed-loop feedback system ensures precise coordination between gear selection and motor speed without requiring the user to manually calculate or adjust multiple parameters.
2Adaptability or versatility
If multiple gears are provided for varying rotational speed and torque, then adaptability to different core bit diameters improves, but the complexity of selecting the appropriate gear increases
Solution Approach 1:
The patent enables the system to serve itself by automatically matching motor rotational speed to the selected gear ratio. When the user rotates the operating device to select a gear, the sensor detects this position and the control unit automatically adjusts the motor speed accordingly. This self-service mechanism eliminates the need for the user to manually coordinate gear selection with speed adjustment, making the system adaptable to different core bit diameters while maintaining ease of operation.
Solution Approach 2:
The patent introduces an intermediary control unit that mediates between the mechanical gear selection and the electric motor control. The control unit receives positional information from the sensor about the selected gear and translates this into appropriate motor speed commands. This intermediary layer simplifies the user interface while maintaining full adaptability across multiple gear ratios, as the user only needs to select the gear without worrying about speed coordination.
3Productivity
If precise coordination of rotational speed with core bit size is achieved, then drilling efficiency improves, but the device requires complex control mechanisms
Solution Approach 1:
The patent replaces complex mechanical speed control mechanisms with electronic control. Instead of using mechanical variable speed drives or complex gear train adjustments, the system uses a simple rotary switch detected by a sensor, with the control unit electronically adjusting the motor speed. This substitution achieves precise coordination for optimal drilling efficiency while keeping the control mechanisms relatively simple and inexpensive.
Solution Approach 2:
The patent controls drilling efficiency by changing the rotational speed parameter of the electric motor based on the selected gear position. The control unit adjusts the motor speed parameter dynamically to match the mechanical gear ratio, ensuring optimal circumferential speed at the core bit for different diameters. This parameter-based control approach achieves precise coordination without requiring complex mechanical speed control mechanisms.
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 efficient and gentle core drilling by allowing precise adaptation of rotational speed and torque to the core bit diameter, improving drilling efficiency and reducing the risk of tool bit damage across varying material conditions.
Implementation Method 1
a stepping motor for transmitting a movement of the operating device to the shift fork
Data Source
AI summary
A method for selecting a gear in the transmission of a power tool having an electric motor. The method includes the following steps of changing an operating device from a first position to a second position in order to select a gear in the transmission; detecting a signal via at least one sensor corresponding to the second position of the operating device; sending the signal to a controller; changing the rotational speed of the electric motor from a first value to a second value via the controller; changing the operating device from the second position to a third position; changing the stepping motor from a first position to a second position corresponding to the third position of the operating device; and changing a shift fork from a first position to a second position in order to change from a first gear to a second gear.