Muscle-Powered Vehicle Drive Control via Output Gear Speed Detection
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Solution Overview
Problem
Existing muscle-powered vehicle drive systems require complex sensor systems to accurately control the rotational speed of the pedal shaft, which is inefficient and costly, and do not effectively assist the rider without potentially uncomfortable operation.
Innovation Solution
A method for operating a muscle-powered vehicle drive device that detects the actual rotational speed of the output gear and determines the target rotational speed of the pedal shaft, allowing for the control of an electric machine without needing to detect the pedal shaft's rotational speed, using a superposition gear unit and freewheel units to assist the rider's pedaling effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensor systems are used to detect the rotational speed of the pedal shaft, then the control precision of the electric machine is improved, but the device complexity and cost increase
Solution Approach 1:
The patent uses the output gear as an intermediary element to indirectly measure the pedal shaft rotational speed. By detecting the rotational speed of the output gear (which is mechanically connected to the pedal shaft through the superposition gear unit), the system obtains the necessary control information without directly sensing the pedal shaft, thereby avoiding complex sensor installations on the pedal shaft itself
Solution Approach 2:
The patent replaces direct mechanical sensing of the pedal shaft with an electrical detection method applied to the output gear. The control device electronically calculates the pedal shaft rotational speed based on the detected output gear rotational speed and the known gear ratios, substituting direct mechanical measurement with an indirect computational approach that reduces sensor requirements
2Force
If the electric machine provides strong assistance torque, then the rider effort is reduced, but the rider may feel uncomfortable due to excessive or unnatural assistance
Solution Approach 1:
The patent implements a feedback control mechanism where the control device continuously monitors the actual rotational speed of the output gear and compares it with the target rotational speed calculated from the desired pedal shaft speed. Based on this feedback, the control device adjusts the electric machine's assistance torque dynamically, ensuring that the assistance is proportional to the rider's actual pedaling behavior and maintains natural riding comfort
Solution Approach 2:
The patent employs dynamic control of the electric machine assistance by continuously adjusting the assistance torque based on real-time detection of the output gear rotational speed and the rider's pedaling cadence. This dynamic adjustment ensures that the assistance characteristics adapt to varying riding conditions, maintaining comfort while providing necessary support
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 approach simplifies the control of the electric machine, reduces the need for additional sensors, and ensures comfortable assistance to the rider by accurately adjusting the pedal shaft's rotational speed, maintaining efficient operation and power management.
Implementation Method 1
The drive device has a superposition gear unit in the form of a planetary transmission
Implementation Method 2
The drive device has an electric machine, which can include a stator and a rotor
Implementation Method 3
In the torque transmission path between the output gear and the wheel of the vehicle, a freewheel unit can be provided
Data Source
AI summary
A method for operating a drive device (1) for a muscle-powered vehicle is provided. The drive device (1) includes a pedal shaft (2), a superposition gear unit (6) as a planetary transmission with a first element (7), a second element (8), and a third element (10), an output gear (5) mechanically operatively connectable to a wheel (42) of the muscle-powered vehicle, and an electric machine (12). The pedal shaft (2) is mechanically connected to the second element (8), the output gear (5) is mechanically connected to the third element (10), and the electric machine (12) is mechanically connected to the first element (7). The method includes detecting (I) the actual rotational speed of the output gear (5), determining (II) a target rotational speed of the pedal shaft (2), and controlling (III) the electric machine (12) based on the detected actual rotational speed and the determined target rotational speed.