US 10,647,320 B2Granted

Method and a system for controlling vehicle speed

AssigneeVolvo Truck Corporation

InventorsTobias Carlsson, Anders Eriksson, Lars Karlsson, Henrik Andersson

Life of this patent

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Abstract

A device and a method for controlling vehicle speed in a vehicle equipped with cruise control while traveling downhill. The method involves driving a vehicle downhill with the cruise control set to a brake speed; detecting a current vehicle speed; applying the auxiliary brake to maintain the brake speed; detecting a request for a downshift from a current gear to a lower gear; and determining if a downshift is permissible at the current speed. If a downshift is not permissible, then a control unit automatically applies the service brakes to retard the vehicle speed; retarding the vehicle from a current speed to a lower speed at which a downshift to a lower gear is permissible; and performing a downshift to a lower gear when the second vehicle speed is reached. The cruise control is set to a second brake speed lower than the first brake speed.

Claims11

Dependent claims

Method for controlling vehicle speed in a vehicle equipped with cruise control when the vehicle is travelling downhill, which method comprises:

driving a vehicle downhill with the cruise control set to a first brake set speed value;
detecting a current vehicle speed;
applying a brake torque using at least one auxiliary brake to maintain the first brake set speed, which brake torque is dependent on a currently engaged gear;
detecting a manual request for a downshift from a currently engaged gear to a lower gear, in order to decrease vehicle speed;
determining if a downshift is permissible at the current vehicle speed;
and
when a control unit determines that a downshift is not permissible, then the control unit is automatically arranged to perform the steps of:
applying a brake torque using at least a vehicle service brake to retard the vehicle speed;
retarding the vehicle from a current, first vehicle speed to a lower, second vehicle speed at which a downshift to a lower gear is permissible;
performing a downshift to a lower gear when the second vehicle speed is reached;
setting the cruise control brake set speed to a second brake set speed that is lower than the first cruise control brake set speed value;
and
applying a brake torque using at least the auxiliary brake if a detected current vehicle speed exceeds the second brake set speed.

10 more elements

Vehicle speed control system in a vehicle equipped with cruise control when the vehicle is travelling downhill, which system comprises;

a sensor arranged to detect a current vehicle speed;
a transmission having multiple selectable gears a service brake;
at least one auxiliary brake, having a brake torque that is dependent on a currently engaged gear;
a cruise speed control unit having a user selectable input for receiving a brake set speed, the control unit being arranged to compare the current vehicle speed with a first brake set speed and control the at least one auxiliary brake to maintain the first brake set speed;
wherein the control unit has a user selectable input for receiving a manual request for a downshift from a currently engaged gear to a lower gear, in order to decrease vehicle speed, wherein the control unit is arranged to determine if a downshift is permissible at the current vehicle speed;
and if a downshift is not permissible;
wherein the control unit is arranged to apply the service brake to retard the vehicle speed from the current, first vehicle speed to a lower, second vehicle speed if a downshift is not permissible;
wherein the control unit is arranged to perform a downshift to a lower gear when the second vehicle speed is reached;
wherein the control unit is arranged to set the cruise control brake set speed to a second brake set speed that is lower than the first cruise control brake set speed value;
and
wherein the control unit is arranged to apply a brake torque using at least the auxiliary brake if the current vehicle speed exceeds the second brake set speed.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 15/755,185Filed 28 Aug 2015
Published: US 2018/0244269 A130 Aug 2018
Granted: 12 May 2020
Term ends: Not estimatedThe source records don’t support an estimate.

Classification18 codes

B60W 30/143
Adaptive cruise control: speed control
B60T 7/12
Brake-action initiating means: for automatic initiation; for initiation not subject to will of driver or passenger
B60W 10/11
Including control of change-speed gearings: stepped gearings
B60W 10/18
Conjoint control of vehicle sub-units of different type or different function: including control of braking systems