High Speed Downshift Management via Pre-Braking
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Solution Overview
Problem
Existing systems for managing downshifting in machines fail to control wear on drivetrain components due to sudden increases in engine and drivetrain angular velocity, particularly when downshifting at high speeds, leading to potential damage and undue wear on components like differentials, transmissions, and engines.
Innovation Solution
A system comprising a transmission, electronically coupled gear selector, remote-activatable brake mechanism, and a controller that calculates target engine revolutions per minute (rpm) and machine speed, activating the brake to slow the machine to the target speed before engaging a new, lower gear, thereby reducing drivetrain component stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the machine downshifts while running at a high rate of speed to achieve faster deceleration, then the deceleration performance is improved, but the engine and drivetrain component angular velocity increases suddenly causing damage or undue wear
Solution Approach 1:
The system applies braking force before the downshift occurs to reduce the machine's speed to a safe level. The controller determines a target machine speed based on the current gear, requested lower gear, and machine mass, then activates the brake mechanism to achieve this target speed before allowing the gear change. This preliminary speed reduction prevents the sudden angular velocity spike that would otherwise occur during high-speed downshifting.
Solution Approach 2:
The brake mechanism applies a counteracting force to oppose the tendency of the drivetrain components to experience excessive angular velocity during downshift. By applying brakes in advance and maintaining braking force through the gear transition, the system counteracts the harmful effect of sudden torque changes and rotational speed spikes in the drivetrain.
2Speed
If braking force is applied during downshift to achieve a pre-determined target deceleration value, then the deceleration control is improved, but the system requires the brake to already be applied when downshift is requested which limits flexibility
Solution Approach 1:
The controller calculates the target machine speed in advance based on the current operating conditions (current gear, requested gear, machine mass) and applies braking force to achieve this target before the downshift. This allows the system to prepare the optimal braking action in advance rather than reacting after the downshift request, improving both control precision and operational flexibility.
Solution Approach 2:
The system continuously monitors the machine's actual speed during the braking process and compares it to the target speed. The controller adjusts the brake mechanism's force accordingly to ensure the machine reaches the precise target speed before downshifting, providing closed-loop control that adapts to actual operating conditions.
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
The solution effectively manages drivetrain wear by controlling engine rpm during downshifts, reducing maintenance costs and extending operating times between servicing, minimizing component stress and wear, especially in high-speed downhill operations.
Implementation Method 1
The brake mechanism may then be activated to slow the machine to the new speed prior to the transmission engaging the new gear
Data Source
AI summary
In order to reduce drivetrain component wear and tear, a machine monitors for an impending downshift and automatically slows the machine to a speed that keeps engine rpm below a target engine rpm before the downshift is completed. A controller in the machine determines the current speed of the machine and then slows the machine to a new speed associated with the target rpm in the new gear. The controller may simply apply the brakes to slow the machine to the new speed independently of the process of changing gears or may actively delay the gear change until the new speed is achieved.