Vehicle Speed Limiting System with Dynamic Gear Ratio Adjustment
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Solution Overview
Problem
Agricultural tractors using different tire diameters face challenges in maintaining a constant maximum speed due to varying tire circumferences, leading to engine inefficiency, increased costs, and legal compliance issues, as existing speed regulation systems rely on tire size-dependent calculations.
Innovation Solution
A system that determines actual vehicle speed independently of tire size using radar or GPS signals, adjusting engine speed and driveline gear ratio to maintain a constant maximum speed, allowing flexible use of different tire sizes without additional effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the engine speed is limited to ensure maximum vehicle speed compliance, then the maximum speed can be controlled, but the engine cannot operate at optimal speed, causing reduced torque, increased fuel consumption, and higher emissions
Solution Approach 1:
The system dynamically changes the parameters of engine speed and driveline gear ratio based on the detected tyre diameter. By adjusting these parameters in real-time according to the actual tyre size, the system ensures the vehicle reaches the legally permitted maximum speed while allowing the engine to operate in its optimal range, thereby avoiding increased fuel consumption and emissions that would result from constant engine speed limitation.
2Speed
If the gearbox output rotation speed is limited to comply with maximum speed regulations, then the maximum speed can be controlled, but the engine loses flexibility in operation range
Solution Approach 1:
The system dynamically adjusts the gearbox output rotation speed limit based on the detected tyre diameter rather than using a fixed limitation. This dynamic approach allows the engine to operate flexibly across its optimal range while still ensuring the vehicle speed remains within legal limits, as the control unit continuously adapts the speed parameters to match the actual tyre size installed on the vehicle.
3Speed
If tyre size is fixed to maintain constant maximum speed, then speed control is simplified, but the vehicle loses operational flexibility and requires additional registration procedures
Solution Approach 1:
The system automatically detects the tyre diameter using sensors (such as RFID tags on the tyres or acoustic measurement) and self-adjusts the speed control parameters without requiring manual intervention, dealer registration, or additional administrative procedures. This self-service capability allows farmers to freely change tyres according to their operational needs while the system automatically ensures legal speed compliance, eliminating the need for fixed tyre size specifications in vehicle documentation.
4Productivity
If larger diameter tyres are installed to increase working width, then operational efficiency improves, but the vehicle exceeds maximum speed limits
Solution Approach 1:
When larger diameter tyres are installed to increase working width and productivity, the system detects the increased tyre diameter and automatically adjusts the engine speed and driveline gear ratio parameters accordingly. This allows the vehicle to maintain the legally permitted maximum speed while operating with larger tyres that provide greater working width efficiency, thus resolving the conflict between productivity improvement and speed limit compliance.
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 consistent maximum velocity across varying tire sizes, optimizing engine operation, reducing costs, and ensuring legal compliance by automatically adjusting speed settings based on real-time tire data, allowing easy tire changes and flexible use.
Implementation Method 1
The means for determining the actual vehicle speed can be via a radar sensor
Implementation Method 2
The means for determining the actual vehicle speed can be via a radar sensor or GPS signal
Data Source
Figure 1
Figure 2
AI summary
A system for regulating the maximum speed of a vehicle (10) having wheels (11, 12) fitted with tyres and driven from an engine (13) via a driveline (14, 15, 16) with a total overall gear ratio, the system including a means such as a GPS or radar based system for determining the actual vehicle speed of the vehicle without using a calculation based on engine speed. A control unit (18) is also provided which adjusts the engine speed and/or overall driveline gear ratio so that the maximum speed which the vehicle can attain remains substantially constant at a predetermined value irrespective of the diameter of the tyres fitted to the wheels.