Motor-Driven Shift Drum Control for Low-Shock Gear Changes
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Solution Overview
Problem
Conventional variable-speed transmissions face challenges in reliably and gently managing changeover processes for selecting different gear ratios, particularly in electric motor-driven shift drums, leading to potential wear and mechanical stress.
Innovation Solution
A method for controlling a torque- and/or speed-converting variable-speed transmission using an electric motor-driven shift drum, which includes shifting elements acting on sliding sleeves connected to gear pairs, and a brushless DC motor or permanent magnet synchronous motor for precise control and high power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional variable-speed transmissions use manual or automatic gear shifting mechanisms, then gear ratio changes can be achieved, but mechanical wear and shock loads increase during changeover processes
Solution Approach 1:
The patent replaces the conventional mechanical shift drum actuation system with an electric motor-driven system. The electric motor directly rotates the shift drum to precise angular positions, eliminating the need for complex mechanical linkages, springs, and cam mechanisms that cause shock loads and wear during gear changes.
Solution Approach 2:
The patent implements precise control of the shift drum's rotational position and speed through electric motor control. By controlling the angular position of the shift drum with high precision and managing the rotational speed profile, the system achieves smooth gear engagement without shock loads, and maintains reliable operation across varying operating conditions.
2Manufacturing precision
If electric motors are used to drive the shift drum, then precise control of gear ratio changes is achieved, but the complexity of the control system increases
Solution Approach 1:
The patent incorporates feedback control mechanisms that monitor the actual rotational position and speed of the shift drum, comparing these values with the desired target values. The control system automatically adjusts the electric motor's operation to eliminate deviations, ensuring precise gear engagement while managing system complexity through closed-loop control.
Solution Approach 2:
The control system pre-calculates and executes optimal rotation profiles for the shift drum before gear engagement occurs. By planning the rotational motion in advance and preparing the gear engagement sequence beforehand, the system achieves precise control without requiring overly complex real-time control algorithms.
3Volume of moving object
If high power density motors are used in the shift drum, then compact design is achieved, but heat generation and mechanical stress increase
Solution Approach 1:
The electric motor operates in periodic cycles, delivering high torque only during the brief moments when gear engagement is required, rather than continuous operation. This intermittent high-power delivery allows the use of compact, high power density motors while managing heat generation, as the motor has time to cool between engagement events.
Solution Approach 2:
The control system manages mechanical stress by implementing smooth acceleration and deceleration profiles for the shift drum, avoiding sudden torque applications. The electric motor's controlled torque delivery acts as a cushion, preventing shock loads on the gear engagement mechanism while maintaining compact motor dimensions.
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 method enables precise and reliably reproducible gearshift operations with reduced mechanical loads and wear, minimizing shock loads and impulse loads during gear changes.
Implementation Method 1
an electromotive direct drive, formed in particular by a brushless DC motor 22 or by a permanent magnet synchronous motor
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
The invention relates to a variable-speed transmission which converts a torque and/or a rotational speed, comprising an input shaft, an output shaft, and at least two transmission stages. Each of the transmission stages is associated with at least one respective exchangeable gear pair. Shifting elements act on sliding sleeves (24) which are connected to the gear pairs and can change same. The shifting elements are in engagement with a shift drum (10) which can be brought into defined angular positions and can be rotated between said angular positions. The shift drum (10) has an electric motor-driven direct drive (12) which rotates the shift drum (10) and can bring the shift drum into the respective defined angular positions. The invention also relates to a method for controlling a variable-speed transmission which converts a torque and/or a rotational speed and which has an input shaft, an output shaft, and at least two transmission stages, each of which is associated with at least one exchangeable gear pair. According to the method, the rotations of the shift drum (10) are adapted to the respective rotational speeds of the gears (28) to be brought into engagement or out of engagement with the sliding sleeves (24) upon activating or deactivating a transmission stage and/or upon changing transmission stages of the variable-speed transmission, wherein in each case at least the rotational energies of the gears (28) in question and/or gear pairs meshing therewith are taken into consideration.