Electric Motorcycle Torque Control for Low-Speed Reverse Maneuvering
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Solution Overview
Problem
Vehicles, particularly motorcycles lacking a reverse gear, face challenges in maneuvering in reverse due to torque fluctuations in internal combustion engines, leading to unsafe conditions and potential damage from sudden torque increases, while using starter motors for propulsion results in excessive wear and battery drain.
Innovation Solution
A two-wheeled electric vehicle system with an electric motor, energy storage device, and controller that allows low-speed operation with controlled torque and direction switching, enabling safe and efficient reverse and forward movement without gear changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the driver further depresses the accelerator to overcome an obstacle at very low vehicle speed, then the driving torque increases to overcome the obstacle, but the torque response of the engine may result in a disproportionate increase in driving torque, causing the vehicle to hurtle unexpectedly in the reverse direction
Solution Approach 1:
The system dynamically switches between a first operating mode with higher maximum driving torque and a second operating mode with lower maximum driving torque based on vehicle speed. At low speeds, the system limits torque to prevent sudden hazardous movements, while at higher speeds, full torque is available for normal operation. This dynamic adjustment resolves the contradiction by adapting torque characteristics to operational context.
Solution Approach 2:
The controller changes the torque parameter based on vehicle speed conditions. When vehicle speed is below a threshold, the maximum driving torque is reduced to a lower value, preventing disproportionate torque increases at low speeds. This parameter change ensures safe operation during low-speed maneuvers while maintaining full performance capability at normal operating speeds.
2Adaptability or versatility
If a starter motor is used to propel the vehicle in reverse direction, then the vehicle can be moved backward without a reverse gear, but the starter motor experiences excessive or premature wear and failure
Solution Approach 1:
The electric motor is designed to perform multiple functions: it serves as the primary propulsion motor during normal operation and also functions as the reversing mechanism when needed. This eliminates the need for a separate starter motor to be used for reversing, thereby preventing excessive wear and failure of the starter motor while maintaining reverse movement capability.
3Force
If a starter motor is used for propulsion, then high torque is provided at the engine's minimum cranking speed, but significant battery power consumption and motor overheating occur
Solution Approach 1:
The system dynamically adjusts torque output based on vehicle speed and operational mode. In the second operating mode during low-speed reverse maneuvers, the maximum driving torque is limited to a lower value, reducing battery power consumption and preventing motor overheating. The controller manages power delivery to match actual propulsion needs rather than providing constant high torque.
Solution Approach 2:
The system applies partial torque action by limiting the maximum driving torque to a lower value during low-speed reverse operation. This partial torque is sufficient for controlled reverse maneuvering but prevents excessive battery drain and motor overheating that would occur with full torque output. The torque limitation is lifted when vehicle speed exceeds the threshold, restoring full power capability.
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 safe, low-speed maneuvering and parking with reduced battery consumption and motor wear, improving control and safety by limiting speed and torque based on vehicle conditions.
Implementation Method 1
an electric motor adapted to drive at least one wheel of the vehicle to propel the vehicle, the electric motor having a predetermined maximum torque output
Implementation Method 2
a controller adapted to control the supply of electrical energy to the electric motor to control an amount of torque output by the electric motor
Data Source
AI summary
A vehicle, e.g., a two-wheeled electric vehicle, is operable in a low-speed mode, in which the vehicle can be propelled selectively in the forward or reverse direction, at a speed limited to approximately an average person's walking speed, e.g., approximately 3 mph. The amount of torque driving the vehicle is controlled so that higher torque is available to propel the vehicle at lower speeds and lower torque is available to propel the vehicle at higher speeds. The maximum torque of the vehicle's electric motor is available to propel the vehicle at a standstill.