Two-Stage Planetary Drill Drive for High Speed and Torque Control
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Solution Overview
Problem
Existing electric drills and handheld power tools face challenges in achieving high rotational speeds and torque while maintaining efficiency and environmental sustainability, particularly with advancements in rotational speed leading to increased energy consumption and complexity.
Innovation Solution
The design incorporates a two-stage deceleration mechanism with a multi-stage planetary transmission group and field-oriented control (FOC) to adjust rotational speed and torque, utilizing a brushless electric motor and a controller to manage power supply, enabling high-speed and low-speed gears with a maximum rotational speed of 2800 rpm and torque of 6-8 newton-meters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If rotational speed of the handheld power tool is increased to deliver better user experience, then speed performance is improved, but energy consumption increases
Solution Approach 1:
The patent applies field-oriented control (FOC) to dynamically adjust motor parameters including rotational speed, torque, and current. The controller modifies motor operating parameters in real-time based on load conditions and selected gear mode, optimizing the balance between speed and energy consumption. This allows the motor to operate efficiently across different speed ranges rather than consuming maximum energy at all times.
Solution Approach 2:
The system implements dynamic speed and torque control through a controller that adjusts motor parameters based on operational requirements. The two-stage deceleration mechanism with variable gear ratios (first stage: 3.5:1, second stage: 2.5:1) enables dynamic adaptation between high-speed and high-torque modes, allowing the system to optimize energy consumption by selecting appropriate transmission ratios based on the working conditions.
2Speed
If a two-stage deceleration mechanism is added to achieve high rotational speed and torque, then speed and torque performance are improved, but device complexity increases
Solution Approach 1:
The patent employs a nested planetary transmission structure where a first-stage planetary deceleration mechanism is integrated within a second-stage planetary deceleration mechanism. The planet carriers and gears of the first stage are positioned within the housing of the second stage, creating a compact nested arrangement. This nested configuration achieves two stages of deceleration (total ratio 8.75:1) while minimizing the overall size and reducing the number of separate components compared to conventional multi-stage transmissions.
Solution Approach 2:
The patent combines multiple transmission functions into a single integrated planetary gear system. The first-stage and second-stage planetary mechanisms are merged into one compact unit with shared housing and aligned rotation axes. The sun gears, planet gears, and ring gears of both stages are coordinated to provide simultaneous deceleration and torque multiplication, eliminating the need for separate transmission assemblies and reducing overall structural complexity.
3Use of energy by moving object
If field-oriented control is used to manage power supply and adjust rotational speed, then energy efficiency is improved, but control system complexity increases
Solution Approach 1:
The field-oriented control system implements feedback mechanisms where the controller continuously monitors motor current, rotational speed, and load conditions. Based on this feedback, the controller adjusts the stator winding current phases and magnitudes to optimize motor performance. The system uses feedback from the planetary transmission mechanism's gear selection to adapt control parameters, ensuring efficient energy utilization across different operating modes while maintaining manageable control complexity through standardized control algorithms.
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 solution allows for efficient operation at high rotational speeds and torque levels, enhancing user experience and reducing energy consumption, while maintaining a compact and environmentally friendly power tool design.
Implementation Method 1
an electric motor disposed in the housing and including a stator and a rotor
Implementation Method 2
a transmission mechanism connected between the rotor and the output shaft, where the transmission mechanism is a two-stage deceleration mechanism and includes a first-stage deceleration mechanism and a second-stage deceleration mechanism
Implementation Method 3
field-oriented control (FOC) to adjust rotational speed and torque, utilizing a brushless electric motor and a controller to manage power supply
Data Source
AI summary
An electric drill includes an electric motor, having a stator and a rotor, disposed in a housing; a driver circuit including multiple switches disposed on a current path from a battery pack to the electric motor; a controller configured to switch on and off the multiple switches to adjust power supply from the battery pack to the electric motor; an output shaft for mounting a working head; and a transmission mechanism connected between the rotor and the output shaft. The transmission mechanism is a two-stage deceleration mechanism and includes a first-stage deceleration mechanism and a second-stage deceleration mechanism. The electric motor drives the working head to rotate via the transmission mechanism and the output shaft and the maximum rotational speed of the working head is greater than or equal to 2800 rpm.