A CRUISE CONTROL SYSTEM AND A METHOD FOR CONTROLLING A POWERTRAIN

Abstract

An automatic cruise control system for controlling at least a powertrain of a vehicle, the cruise control system being configured to automatically control a vehicle speed to a target speed determined based on a set speed and on information relating to a road topography along an expected travelling route of the vehicle. The automatic cruise control system is configured to: while automatically controlling the vehicle speed to the target speed, receive an indication that a slippery road condition applies or is expected to apply, in response to receiving said indication, activate a predefined slippery road condition driving mode in which predetermined restrictions apply, said restrictions relating to at least one of the vehicle speed, an allowable vehicle acceleration, and a gear selection of the powertrain, control at least the powertrain in accordance with the slippery road condition driving mode.

Claims

1. An automatic cruise control system for controlling at least a powertrain of a vehicle, the cruise control system being configured to automatically control a vehicle speed to a target speed determined based on a set speed and on information relating to a road topography along an expected travelling route of the vehicle, the automatic cruise control system is configured to: while automatically controlling the vehicle speed to the target speed, receive an indication that a slippery road condition applies or is expected to apply, in response to receiving said indication, activate a predefined slippery road condition driving mode in which predetermined restrictions apply, said restrictions relating to at least one of the vehicle speed, an allowable vehicle acceleration as the vehicle approaches and/or enters a detected uphill road section along the expected travelling route, and a gear selection of the powertrain, control at least the powertrain in accordance with the slippery road condition driving mode.

2. (canceled)

3. The automatic cruise control system according to claim 1, wherein the predetermined restrictions are set so as to disable a positive vehicle acceleration as the vehicle approaches and/or enters the detected uphill road section.

4. The automatic cruise control system according to claim 1, wherein the predetermined restrictions are set so as to disable a positive vehicle acceleration as the vehicle approaches and/or enters the detected uphill road section unless a first predetermined condition is fulfilled.

5. The automatic cruise control system according to claim 4, wherein the first predetermined condition is considered fulfilled if it is determined that the positive vehicle acceleration will prevent a gear shift of the powertrain.

6. The automatic cruise control system according to claim 1, wherein the predetermined restrictions are set so as to restrict an allowable vehicle speed during downhill travel.

7. The automatic cruise control system according to claim 1, wherein the predetermined restrictions are set so as to disable rolling of the vehicle with a propulsion unit of the powertrain disconnected from drive wheels of the vehicle during downhill travel.

8. The automatic cruise control system according to claim 1, wherein the predetermined restrictions are set so as to limit the vehicle speed to a speed equal to or smaller than the set speed.

9. The automatic cruise control system according to claim 1, wherein the automatic cruise control system is configured to, as the vehicle approaches and/or enters a detected uphill road section, select a gear of the powertrain and/or set the target speed such that a gear shift during travel along the uphill road section is avoided.

10. A method for controlling at least a powertrain of a vehicle, the vehicle comprising an automatic cruise control system configured to automatically control a vehicle speed to a target speed determined based on a set speed and on information relating to a road topography along an expected travelling route of the vehicle, the method comprising: while automatically controlling the vehicle speed to the target speed using the automatic cruise control system, receiving an indication that a slippery road condition applies or is expected to apply, in response to receiving said indication, activating a predefined slippery road condition driving mode in which predetermined restrictions apply, said restrictions relating to at least one of the vehicle speed, an allowable vehicle acceleration as the vehicle approaches and/or enters a detected uphill road section along the expected travelling route, and a gear selection of the powertrain, controlling at least the powertrain in accordance with the slippery road condition driving mode.

11. (canceled)

12. The method according to claim 10, wherein the predetermined restrictions are set so as to disable a positive vehicle acceleration as the vehicle approaches and/or enters the detected uphill road section.

13. The method according to claim 10, wherein the predetermined restrictions are set so as to disable a positive vehicle acceleration as the vehicle approaches and/or enters the detected uphill road section unless a first predetermined condition is fulfilled.

14. The method according to claim 13, wherein the first predetermined condition is considered fulfilled if it is determined that the positive vehicle acceleration will prevent a gear shift of the powertrain.

15. The method according to claim 10, wherein the predetermined restrictions are set so as to restrict an allowable vehicle speed during downhill travel.

16. The method according to claim 10, wherein the predetermined restrictions are set so as to disable rolling of the vehicle with a propulsion unit of the powertrain disconnected from drive wheels of the vehicle during downhill travel.

17. The method according to claim 10, wherein the predetermined restrictions are set so as to limit the vehicle speed to a speed equal to or smaller than the set speed.

18. The method according to claim 1, further comprising: as the vehicle approaches and/or enters a detected uphill road section, selecting a gear of the powertrain and/or setting the target speed such that a gear shift during travel along the uphill road section is avoided.

19. The method according to claim 10, wherein receiving the indication that a slippery road condition applies or is expected to apply comprises receiving a request from a driver of the vehicle, or detecting road slip, or receiving information from other vehicles.

20. A computer program comprising program code means for performing the steps of claim 10 when said computer program is run on a computer.

21. A computer readable medium carrying a computer program comprising program code means for performing the steps of claim 10 when said computer program is run on a computer.

22. A vehicle comprising the automatic cruise control system according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0047] In the drawings:

[0048] FIG. 1 shows a vehicle according to an embodiment of the invention,

[0049] FIG. 2 is a flow chart illustrating a method according to an embodiment of the invention,

[0050] FIG. 3 schematically shows a road on which a vehicle according to an embodiment of the invention is travelling, and

[0051] FIG. 4 shows a control device according to an embodiment of the invention.

[0052] The drawings show diagrammatic exemplifying embodiments of the present invention and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the invention is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the invention. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0053] A vehicle 1 in the form of a heavy-duty truck is schematically shown in FIG. 1. The vehicle 1 includes an automatic cruise control system 10 for controlling a powertrain 2 of the vehicle 1. The powertrain 2 includes a propulsion unit 3, which in the shown embodiment is an internal combustion engine although other propulsion units may also or alternatively be provided, such as one or more electric machines. The propulsion unit 3 is connected to drive wheels 4 of the vehicle 1 via a transmission 5 and a driveshaft 6.

[0054] The automatic cruise control system 10 is a predictive cruise control system configured to automatically control the vehicle speed v to a target speed v.sub.target, which target speed V.sub.target is set based on a set speed v.sub.set set by a user, usually a driver, of the vehicle 1, and based on information relating to a road topography along an expected travelling route of the vehicle 1. The automatic cruise control system 10 is equipped with a slippery road condition driving mode in which predetermined restrictions apply. The restrictions relate to at least one of the vehicle speed v, an allowable vehicle acceleration, and a gear selection of the powertrain 2. Thus, the automatic cruise control system 10 is configured to control the powertrain 2 of the vehicle 1, including setting restrictions relating to gear selection. It may also be configured to control a braking system (not shown) of the vehicle 1.

[0055] The automatic cruise control system 10 is configured to carry out the steps of a method according to an embodiment of the invention illustrated in FIG. 2.

[0056] In a first step S1, carried out while the automatic cruise control system 10 automatically controls the vehicle speed v to the target speed v.sub.target, an indication that a slippery road condition applies or is expected to apply is received via a communication interface of the automatic cruise control system 10. The indication may be a request from a user/driver of the vehicle 1, or a signal from a sensor configured for detecting road slip/wheel slip, or information received from another vehicle.

[0057] In a second step S2, carried out in response to receiving said indication, the predefined slippery road condition driving mode is activated.

[0058] In a third step S3, the powertrain, and optionally also the braking system of the vehicle 1, is controlled in accordance with the slippery road condition driving mode, that is, by applying the predetermined restrictions.

[0059] Two different exemplary driving scenarios will now be described with reference to FIG. 3, in which the vehicle 1 is travelling along a road 100 as it approaches an uphill road section 101 followed by a crest 102 and a downhill road section 103. The vehicle speed v is in both driving scenarios controlled by the automatic cruise control system 10 to a target speed v.sub.target as described above. For simplicity, the automatic cruise control system 10 will herein be referred to as the cruise control 10.

[0060] In a first driving scenario, a case is considered in which the slippery road condition driving mode is not activated, i.e. the predetermined restrictions do not apply. This may be considered a standard driving mode of the cruise control 10. In this scenario, as the vehicle 1 approaches the uphill road section 101, the cruise control 10 sets the target speed v.sub.target to a value which is higher than the set speed v.sub.set set by the driver such that the vehicle 1 may gain momentum and such that down-shifting when travelling along the uphill road section 101 may be prevented. The vehicle speed v is thereafter allowed to decrease below the set speed v.sub.set along the uphill road section 101 and when reaching the crest 102. As the downhill road section 103 starts, the cruise control 10 controls the transmission 5 to a neutral gear, such that the vehicle 1 rolls with the propulsion unit 3 disconnected from the drive wheels 4. The vehicle speed v is now allowed to increase above the set speed v.sub.set by a predetermined amount. As the vehicle 1 moves further down along the downhill road section 103, the powertrain 2 is controlled such that engine braking is used to brake the vehicle 1, thereby preventing the vehicle speed v from exceeding the target speed v.sub.target. Finally, as the vehicle 1 leaves the downhill road section 103, the cruise control 10 allows the vehicle speed v to increase by rolling with the neutral gear engaged.

[0061] In a second exemplary driving scenario, a case is considered in which the slippery road condition driving mode is activated, i.e. the predetermined restrictions apply. In this scenario, as the vehicle 1 approaches the uphill road section 101, the cruise control 10 sets the target speed V.sub.target to a value which is equal to or lower than the set speed v.sub.set set by the driver such that the vehicle 1 is not allowed to gain momentum prior to the uphill road section 101. In this case, the predetermined restrictions are set so as to disable a positive vehicle acceleration as the vehicle 1 approaches and/or enters the detected uphill road section 101. Alternatively, if it is determined by the cruise control 10 that a speed increase by a certain amount prior to the uphill road section 101 may prevent an otherwise necessary down-shift, such a speed increase may be allowed. The vehicle speed v is thereafter allowed to decrease below the set speed v.sub.set along the uphill road section 101 and when reaching the crest 102. Optionally, when reaching the crest, the cruise control 10 may additionally reduce the vehicle speed v by applying brakes of the vehicle 1 or by engine braking. As the downhill road section 103 starts, the cruise control 10 controls the vehicle speed to a target speed V.sub.target which is equal to or lower than the set speed v.sub.set. In this case, the predetermined restrictions are set so as to restrict the allowable vehicle speed during downhill travel. Alternatively, the restrictions may be set such that the target speed V.sub.target is smaller than a target speed V.sub.target used in the standard driving mode. Engine braking may be used to brake the vehicle 1 during downhill travel, thereby preventing the vehicle speed v from exceeding the target speed V.sub.target. If necessary, the braking system of the vehicle 1, including e.g. wheel brakes, may be used. Finally, as the vehicle 1 leaves the downhill road section 103, the cruise control 10 controls the vehicle speed to a target speed V.sub.target which is lower than in the standard driving mode, such as equal to or lower than the set speed v.sub.set.

[0062] Thus, according to some embodiments, the target speed V.sub.target may in the slippery condition driving mode be set to never exceed the set speed v.sub.set. In other embodiments, the target speed V.sub.target may be allowed to exceed the set speed v.sub.set by a smaller amount than in the standard driving mode. For example, the vehicle speed v may be allowed to exceed the set speed v.sub.set by a predetermined amount during downhill travel, if such a speed increase may prevent engine braking, which may in very slippery conditions lead to wheel slip.

[0063] The control functionality of the example embodiments may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwire system. Embodiments within the scope of the present disclosure include program products comprising machine-readable medium for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0064] FIG. 4 shows a control device 400 configured for carrying out the method according to embodiments of the invention, comprising a non-volatile memory 420, a data-processing unit 410 and a read and write memory 460. The memory 420 has a first memory part 430, in which a computer program for controlling the control device 400 is stored. The computer program in the memory part 430 for controlling the control device 400 can be an operating system.

[0065] The control device 400 can be comprised in the automatic cruise control system 10 described above. The data-processing unit 410 can comprise, for example, a microcomputer. The memory 420 also has a second memory part 440, in which a program for controlling at least the powertrain according to the invention is stored. In an alternative embodiment, the program for controlling at least the powertrain is stored in a separate non-volatile storage medium 450 for data, such as, for example, a CD or an exchangeable semiconductor memory. The program can be stored in an executable form or in a compressed state. When it is stated below that the data-processing unit 410 runs a specific function, it should be clear that the data-processing unit 410 is running a specific part of the program stored in the memory 420 or a specific part of the program stored in the non-volatile storage medium 450. The data-processing unit 410 is tailored for communication with the non-volatile storage medium 450 through a data bus 414. The data-processing unit 410 is also tailored for communication with the memory 420 through a data bus 412. In addition, the data-processing unit 410 is tailored for communication with the memory 460 through a data bus 411. The data-processing unit 410 is also tailored for communication with a data port 490 by the use of a data bus 415.

[0066] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.