Vehicle Control Method Preventing Unwanted Stops on Steep Inclines
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Heavy-duty vehicles face challenges with unwanted stops on steep uphill road sections and poor road conditions, where limited traction can lead to difficulties in restarting, necessitating towing or reversing, which are undesirable.
Innovation Solution
A method for controlling a vehicle with an internal combustion engine and automatic transmission that maintains engine rotational speed above a predetermined threshold to prevent unwanted downshifts, ensuring traction by engaging the driveline and avoiding transmission gear downshifts, even when the accelerator pedal is released, with adaptive threshold values based on road inclination and vehicle weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the transmission automatically downshifts in response to accelerator pedal release, then the vehicle speed control responds to driver input, but the vehicle may stop unintentionally on steep uphill sections
Solution Approach 1:
The system changes the threshold parameter for downshift activation based on road inclination. When a steep uphill section is detected, the threshold for accelerator pedal release that triggers downshift is adjusted, preventing automatic downshifts that would cause vehicle stop. This resolves the contradiction by modifying the downshift trigger parameter to distinguish between intentional speed control and conditions that would lead to unwanted stops.
2Force
If the transmission downshifts to provide higher torque, then the vehicle can overcome steep inclines, but the driveline disengages causing loss of traction
Solution Approach 1:
The system applies preliminary anti-action by detecting the risk of driveline disengagement before it occurs. When steep uphill conditions are detected, the control system preemptively prevents downshifts that would cause the engine speed to drop below the threshold for maintaining driveline engagement. This counteracts the potential harmful effect of driveline disengagement before it can occur, maintaining both torque and continuous driveline connection.
3Ease of operation
If the accelerator pedal is released to control vehicle speed, then the driver can regulate speed without braking, but the engine speed drops causing transmission downshift
Solution Approach 1:
The system changes the operational parameters by introducing a minimum engine speed threshold that overrides the normal downshift logic. When the engine speed approaches this threshold during accelerator release, the transmission control system modifies the downshift timing or prevents downshift entirely. This parameter change allows speed regulation through accelerator release while preventing the automatic downshift that would otherwise occur.
Data Source
AI summary
The invention provides to a method for controlling a vehicle (1) with an internal combustion engine (2) and a transmission (3), the transmission being arranged to automatically provide shifts between a plurality of gear ratios between the engine and at least one driven wheel (5) of the vehicle, characterized by the steps of: —registering (S1, S108) a decrease of a demanded torque from an engine control input device (8) of the vehicle, —controlling (S2, S109) in response to the demanded torque decrease the rotational speed of the engine so as to not be below a rotational speed threshold value which is above an idle speed of the engine, and where said rotational speed threshold value is determined so as for a transmission gear down shift to be avoided.