A method for operating an automatic or semi-automatic transmission of a heavy vehicle when in idle-driving mode

Abstract

A method for operating a semi-automatic or automatic mechanical transmission (310) of a heavy truck when driving at idle speed. The method includes supplying fuel to the engine (300) of the heavy truck at a rate that facilitates engine-idle operation. In another step, the method engages the automatic or semi-automatic transmission in a gear higher than the starting gear of the transmission and permits the truck to operate at a first substantially uniform driving velocity (S1) under engine-idle power. Depending upon traffic and environmental requirements which require a higher speed, the driver upshifts the semi-automatic or automatic transmission by depressing a control device (350) for manual gear selection arranged on a gear shift lever (340) of the truck and then drives the truck at a second substantially uniform driving velocity (S2) under engine-idle power. The second (S2) substantially uniform driving velocity is greater than the first (S1) substantially uniform driving velocity.

Description

technical field [0001] The present invention relates to commercial vehicles, and more particularly to drive train control strategies for vehicles such as heavy trucks, buses and the like. Background technique [0002] In the course of driving, for example, overland trucks and buses (which, for the purposes of the description contained herein, should be considered interchangeable), often require driving at relatively low speeds, often for extended periods of time. Exemplary situations are driving in slow, congested traffic and maneuvering around loading yards where high speed driving is not possible. In modern heavy vehicles it is often the case that such vehicles are equipped with a semi-automatic transmission or automatic mechanical transmission (AMT) or automatic transmission with power shift. In any of the above cases, a computer control strategy is used to select the gear engagement and transition strategy between the different gear selections of the transmission. In a...

AI Technical Summary

Problems solved by technology

[0006] This trial and error of gear selection and accelerator pedal position selection by the driver has obvious disadvantages; especially if the truck is operating at low speeds, the driver is rendered unnecessary by this selection process ground fatigue

Furthermore, operating economy can suffer, not only because of the inefficiencies associated with the constant gear changes and adjustments of the accelerator pedal position, but also because if the optimum engine idle speed is not selected to maintain the desired vehicle speed gear

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