Electric Vehicle Brake Control With Transit Stop State
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Solution Overview
Problem
Electric travelling vehicles face high power consumption and unnecessary load on motors due to continuous excitation of electromagnetic power-off brakes, and drivers struggle to monitor the mower unit's state in grass mowers, leading to potential overheating and inefficient braking.
Innovation Solution
Implementing a control system that optimizes the excitation of electromagnetic brakes based on travel states, introducing a transit stopped state between travelling and stopped states to manage brake and motor control timing, and incorporating sensors to detect mower unit abnormalities and adjust power transmission accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electromagnetic power-off brake is continuously excited during vehicle travel, then the brake remains in a released state ensuring smooth operation, but power consumption increases significantly
Solution Approach 1:
The electromagnetic coil is excited periodically rather than continuously. The control unit determines excitation based on travel state (travelling, stopped, or transit stopped), creating a periodic on-off pattern that maintains brake reliability when needed while reducing power consumption during periods when braking is not required
Solution Approach 2:
The brake system transitions dynamically between three states: travelling state (released), stopped state (braking), and transit stopped state (intermediate). This dynamic state management allows the system to adapt excitation levels to actual operational needs, optimizing the balance between reliability and energy efficiency
2Reliability
If the electromagnetic power-off brake is continuously excited, then the brake remains responsive, but unnecessary load is placed on the electric motor and brake shaft
Solution Approach 1:
By applying periodic excitation rather than continuous excitation, the brake maintains responsiveness during critical periods (travelling and stopped states) while reducing mechanical load during transitional periods, thereby protecting the motor and brake shaft from unnecessary stress
Solution Approach 2:
The system transitions to the transit stopped state as an intermediate step before full stopping, allowing preliminary brake engagement that prepares the system for stopping while avoiding sudden full-load engagement that would stress the motor and shaft
3Ease of operation
If the driver sits on the driver's seat in an upper portion, then the driver has good visibility and control, but it becomes difficult to check the driving state of the mower unit located in the lower portion
Solution Approach 1:
A detection signal system acts as an intermediary between the mower unit and the driver. Sensors detect the driving state of the mower unit and transmit this information to the control unit, which then provides feedback to the driver, eliminating the need for direct visual inspection while maintaining ease of operation
Solution Approach 2:
The system implements feedback by detecting the mower unit's driving state through sensors and using this information to control the vehicle's operation. This closed-loop feedback allows the driver to maintain good positioning while still having accurate information about the mower unit's state
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 reduces power consumption, prevents unnecessary brake excitation, ensures safe and balanced power saving and safety, and detects mower unit abnormalities to prevent overheating and inefficient operation.
Implementation Method 1
an electromagnetic coil that releases the armature from the brake disk using an electromagnetic force
Implementation Method 2
a brake spring that presses an armature against a brake disk using a biasing spring force
Data Source
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AI summary
An electric travelling vehicle including: a motor controller (61) configured to control an electric motor (20) based on displacement of a steering operation part (15) to a forward travel position, a neutral position, and a rearward travel position, a brake controller (62) configured to bring an electromagnetic power-off brake (5) into a released state or a braking state; and a travel state detector (63) configured to detect a travelling state that is accompanied with the released state, a stopped state that is accompanied with the braking state, and a transit stopped state that is accompanied with the braking state. In the travelling state, the steering operation part (15) has deviated from the neutral position, the electromagnetic brake is in the released state, and the electric motor (20) is in an excited state. In the transit stopped state, the steering operation part (15) is at the neutral position, the electromagnetic brake is in the braking state, and the electric motor (20) is in an unexcited state. A transition to the transit stopped state occurs on a condition that, in the travelling state, the steering operation part (15) has been returned to the neutral position and a predetermined period of time has elapsed upon a rotational speed of the electric motor (20) decreasing to a very low rotational speed.