Gearbox Speed Control Preventing Gear Pumping on Uphill Grades
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Solution Overview
Problem
Existing methods for controlling automatic or manual gearboxes with cruise control in uphill situations often result in gear pumping, where the vehicle frequently loses and regains speed due to engine protection requirements, leading to inefficient gear changes and fuel consumption.
Innovation Solution
A method that regulates vehicle speed by estimating resistance forces and calculating maximum possible acceleration, activating a speed restriction function when acceleration is negative in higher gears, and deactivating it when acceleration is positive, to maintain a stable gear ratio and prevent unnecessary gear shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the vehicle uses conventional cruise control with automatic gear shifting in uphill situations, then the vehicle attempts to maintain the set speed, but the vehicle experiences frequent gear pumping and speed loss due to engine protection limits
Solution Approach 1:
The control system performs preliminary calculation of maximum possible acceleration in the next higher gear before gear shifts occur. By estimating resistance forces from speed values and engine tachometer data, the system predicts whether the engine will reach maximum speed and trigger protection-based upshifts, allowing proactive prevention of gear pumping cycles
Solution Approach 2:
The system continuously monitors vehicle speed, engine torque, and engine speed to estimate resistance forces. This feedback loop allows the control system to adapt gear shift decisions in real-time, comparing actual performance against calculated maximum acceleration to prevent unnecessary gear changes and maintain stable operation
2Speed
If the vehicle downshifts to maintain speed when approaching maximum engine speed, then the vehicle can accelerate again, but this causes frequent gear changes and increased fuel consumption
Solution Approach 1:
Before executing a downshift, the system calculates the maximum possible acceleration in the current gear using estimated resistance forces and engine torque data. This preliminary assessment allows the system to determine whether a downshift is truly necessary or if the vehicle can maintain speed without gear changes, thereby reducing unnecessary fuel consumption
Solution Approach 2:
The system applies partial action by only downshifting when the calculated maximum acceleration indicates that speed maintenance is not possible in the current gear. This selective approach avoids excessive gear changes and the associated fuel consumption, performing only the minimum necessary action to maintain vehicle speed
Data Source
AI summary
The invention relates to a method for controlling a driven manual or automatic gearbox with a speed regulator pertaining to a vehicle traveling uphill, said method consisting in: regulating the speed to a nominal value set by the driver of the vehicle; acquiring the immediate values of the speed and the engine torque; estimating the resistive efforts based on values of speed and engine RPM; calculating, on the basis of the estimation of the resistive efforts and the maximum torque of the heat engine, the maximum vehicle acceleration possible in the gearbox gear ratio above the one that is engaged; and activating, or not, a vehicle speed limiting function (BVV) at a speed set value corresponding to the maximum speed for the heat engine according to whether the maximum acceleration possible in the higher gear ratio is negative or positive, respectively.