Method and system for controlling a vehicle cruise control

ES 2 532 467 T3

DESCRIPTION

Procedure and system to control a cruise control of a vehicle

Technical field

The present invention relates to a method for controlling a cruise control in a vehicle, according to the first part of appended claims 1 and 3. The invention also relates to a cruise control system of a vehicle intended for such method of controlling said cruise control, according to appended claim 6.

The present invention also relates to a computer program, computer program product and storage medium for a computer, all of them for use with a computer to execute said procedure.

Previous technique

Motor vehicles, such as cars, trucks, trailer vehicles, and buses, are often provided with a so-called cruise control system, also called a speed control system, to automatically control the speed of the vehicle. Such a cruise control system comprises means, such as a speed sensor, for monitoring the actual speed of the vehicle. The cruise control system compares the actual speed of the vehicle with a set target speed. The target speed can be entered into the cruise control system, for example, as the actual prevailing speed of the vehicle when a setting switch is operated by the driver. The cruise control system generates an error signal by comparing the actual speed of the vehicle with the target speed. The error signal is then used, for example, to control an actuator coupled with the fuel pump or the vehicle's throttle in order to change the engine speed until the error signal is substantially zero, i.e. until the actual speed of the vehicle equals the target speed.

Documents EP 1439976, US6990401 and US 6 199 001 B, which constitute the closest prior art, disclose two examples of the prior art where the cruise control system has been further developed. Here the cruise control system is a predictive cruise control system, which uses information about the current position of the vehicle and the topography of the road to be reached, that is, for example gradients or elevation values ​​of the road to be reached. in order to control the throttle opening in such a way as to increase the fuel consumption efficiency.

One problem with prior art cruise controls is that unnecessary downshifts can occur during certain driving conditions of the vehicle. Three examples of such vehicle driving conditions are disclosed in Figures 1 to 3. Each of said Figures discloses a typical example of a road section profile 1, 21 and 31, where such reductions in unnecessary gear. The road section profile 1 in Figure 1 discloses a downward slope followed by an upward slope. An upper curve 2 discloses how the speed of the vehicle varies when driving on said road section profile 1 and a cruise control set at a target speed vcc target speed set. In the example disclosed, a maximum allowable runaway speed vbcc is set for when a braking cruise activates auxiliary brakes and / or service brakes of said vehicle in order not to exceed said vbcc when driving on a downhill slope. With the prevailing vehicle condition, a certain gear is engaged in a transmission of that vehicle and a lower vehicle speed limit is determined for when downshifting occurs (v downshift speed) to a lower gear (with a ratio of higher gear ratio). Said engaged gear can be a direct gear or a gear in which a torque is transmitted by means of pairs of sprockets in the transmission (gearbox). In figure 1, when the vehicle is in position A, the vehicle is accelerating, and will eventually accelerate to slightly above the target speed vcc set after position A. When the vehicle is in position B, the slope of The climb has started and the vehicle speed decreases. In the example shown, the incline is so steep that the available driving force of the vehicle is not sufficient to maintain the target speed vcc set with the current gear engaged. In position C the vehicle speed has decreased to said downshift speed and a downshift is performed. In the example shown, such downshifting results in the vehicle speed starting to increase. One drawback is that fuel efficiency is lost due to the interruption of the prime mover during such downshifting. Even more fuel efficiency will be lost if the downshift is a downshift from direct gear, as driving in a direct gear engaged is more fuel efficient compared to a gear transmitting torque. by means of pairs of toothed wheels.

The examples disclosed in Figures 2 and 3 disclose corresponding downshifts C for two additional possible road section profiles 21 and 31. The road section profile 21 part of a

ES 2 532 467 T3 horizontal road followed by an uphill slope. The road section profile of 31 starts from a slight uphill slope, which is followed by an uphill slope.

The object of the present invention is to further develop such a cruise control system where information about the current position of the vehicle and the topography of the road to be reached is used by the cruise control system to control the speed of the vehicle.

Summary of the invention

Thus, the main object of the present invention is to present an improved method for cruise control that can avoid unnecessary downshifts on uphill slopes. This is achieved by a method as discussed in the introduction, the characteristics of which are defined by claims 1 and 3. The object is also achieved by a system as discussed in the introduction, the characteristics of which are defined by claim 6.

The method according to the invention is a method for controlling a cruise control while driving a vehicle. Said procedure comprises (includes, but is not necessarily limited to) the steps of:

• driving said vehicle with said cruise control active and set to maintain a set target vehicle speed;

• record the current vehicle condition, comprising at least a current vehicle position, a currently engaged gear ratio, available gear ratios, current vehicle speed, maximum available propulsion torque, and road topography of a road ahead comprising a next uphill slope to be reached;

• based on said current vehicle condition, predicting a downshift at a vehicle position to be reached on said uphill slope to be reached due to a decrease in vehicle speed and selecting at least one activity that results in said downshifting gait can be postponed or avoided;

• control said cruise control according to said selected activity.

According to a first alternative embodiment of said invention, said activity comprises the step of:

• temporarily decreasing a downshift limit of said currently engaged gear by a possible predetermined amount up to a decreased downshift speed limit.

According to a further embodiment of said invention, said process, said activity further comprises the steps of:

• predict whether such downshifting will be postponed long enough or avoided;

• if it is predicted that said downshifting will not be postponed long enough or will not be avoided, then performing said temporary downshifting limit;

• and additionally based on said current vehicle condition, calculate a minimum vehicle speed for a first vehicle position where the vehicle will begin to lag behind said uphill slope and which will result in said downshifting can be postponed long enough or avoid;

• based on said current condition of the vehicle, controlling said cruise control in order to, while driving the vehicle towards said first position of the vehicle, increasing the speed of the vehicle to said minimum vehicle speed when said vehicle has finally reached said first position vehicle.

In another embodiment of the invention, said activity comprises the steps of:

• based on said current vehicle condition, calculate a minimum vehicle speed for a first vehicle position where the vehicle will begin to lag on said uphill slope which will result in said downshifting can be postponed or avoided;

ES 2 532 467 T3 • based on said current vehicle condition, control said cruise control in order to, while driving the vehicle towards said first vehicle position, increase the vehicle speed to said minimum vehicle speed when said vehicle has finally reached said first position of the vehicle.

In a further embodiment of the invention, said increase in a vehicle speed up to said minimum vehicle speed is only allowed if the difference between said set target vehicle speed and said minimum vehicle speed is below a predetermined value .

The invention also relates to a vehicle cruise control system comprising (including, but not necessarily limited to) a control unit, a driver input interface, a vehicle position identification device, a road topography identification device. Said system is characterized in that said control unit is arranged to carry out the aforementioned procedural steps of said first embodiment.

Further advantageous embodiments of the invention emerge from the dependent patent claims which follow patent claim 1.

Description of the drawings

The present invention will be described in greater detail below with reference to the accompanying drawings which, for the purposes of exemplification, show further preferred embodiments of the invention and also the technical background, and in which:

Figures 1 to 3 schematically show vehicle speed diagrams and corresponding driving conditions, and where said speed diagrams disclose a cruise control according to the known art.

Figures 4 to 9 schematically show vehicle speed diagrams and corresponding driving conditions, and where said speed diagrams disclose a cruise control according to different embodiments of the invention.

Figure 10 discloses an embodiment of the invention applied in a computer environment.

Description of the invention

A cruise control system for automatically controlling the speed of a vehicle can be arranged in a vehicle according to the known art. Said cruise control system comprises a control unit for continuously processing input signals and supplying output signals to, for example, a drive unit control to control a drive unit and, if installed, also to a drive unit. braking control for controlling braking devices on said vehicle in order to maintain a set vehicle speed. Said braking devices can be a service brake and / or an auxiliary brake and / or an electric motor / generator (if the vehicle is equipped, for example, with a hybrid propulsion system). Said vehicle cruise control system further comprises at least one driver input interface. Said control unit is arranged to perform steps of inventive functions described below with the use of information about the current condition of the vehicle.

Said drive unit control may be arranged to control a drive unit comprising at least one drive unit drivenly connected to wheels driven by means of an automated mechanical transmission (AMT). When said AMT is in an automatic mode, the most suitable gear (between various gears) is automatically selected and engaged while driving said vehicle.

A cruise control on said vehicle is set to maintain the set target speed vcc. This can be set by the driver. Thus, said control unit in said cruise control system is arranged to maintain said fixed target speed vcc. A maximum vehicle runaway speed vbcc can also be set by the driver in order for the control unit to initiate braking of said vehicle if the vehicle speed approaches said vbcc. This functionality is known as such and is also called braking cruise control. Said maximum vehicle runaway speed vbcc for said vehicle cruise control may be set to be at least equal to or greater than said set target speed vcc. In the inventive embodiments described below vbcc is set to be greater than vcc set target speed.

According to an embodiment of the invention, said control unit in said cruise control system is programmed to drive said vehicle with said cruise control active and to perform the following steps:

ES 2 532 467 T3 • drive said vehicle with said cruise control active and set to maintain a target speed of the Vehicle ^{fixed (v}cc target speed set / • record the current vehicle condition, comprising at least one current vehicle position (A), a currently engaged gear ratio, available gear ratios, current vehicle speed, maximum available propulsion torque and topography of the road of a road to be reached that includes a next uphill slope to be reached;

• based on said current vehicle condition, predict a downshift at a vehicle position to be reached (C) on said uphill slope to be reached due to the decrease in vehicle speed and select at least one activity that results in said downshifting can be postponed or avoided;

• control said cruise control according to said selected activity.

Thus, a downshift is predicted to arrive on an uphill slope to arrive when the vehicle is in position A and an activity is selected in order to postpone or avoid such downshifting. In this way, an unnecessary downshifting can at least be postponed or completely avoided while driving on said uphill slope. If that currently engaged gear is a direct gear, fuel will be saved if driving time can be increased with a direct gear engaged. If said currently engaged gear is a gear in which torque is transmitted by pairs of sprockets, fuel will be saved if downshifting can be avoided.

With reference to Figure 4, the same downward slope followed by an upward slope as in Figure 1 is disclosed. Similarly, the speed of the vehicle is controlled in the same way as in the example of Figure 1. According to a mode of carrying out the invention, said activity comprises the step of:

- temporarily decreasing a downshift limit of said currently engaged gear by a predetermined possible amount up to a slowed downshift speed limit (downshift speed decreased /

In figure 4 said reduced gear reduction speed limit is disclosed by the line v diminished gear reduction speed · As can be seen, the diminished gear reduction speed limit is in this example shown lower than the speed predicted minimum vehicle 42 on said incline. Since the downshifting speed limit is below the predicted minimum vehicle speed, no downshifting will take place at position C. The difference between said minimum predicted vehicle speed and said downshifting speed limit downshift can be predetermined. Said difference may depend, for example, on the configuration of the drive unit, the resistance of the vehicle on said uphill slope, and the efficiency of the engine in the area between the normal downshift speed and the downshift speed. downshift (if engine efficiency were to drop dramatically, there would be no point in slowing down the engine as it would lead to additional fuel consumption). The amount of decrease in said downshift speed may depend, for example, on the estimated time for the engine to rotate at a rotational speed below said (ordinary) downshift limit v downshift speed. A typical difference between v downshift speed and v decreased downshift speed can be 100 rpm. Correspondingly, a decreased downshifting speed can be used for road section profiles 21 and 31. For road profile 21 this is disclosed in Figure 6 and for road profile 31 this is disclosed in Figure 8. Thus, in the embodiments of Figures 6 and 8, the corresponding decreased downshift speed v speed is used as in Figure 4.

In a further embodiment of the invention, said activity may alternatively comprise the steps of:

• based on said current vehicle condition, calculate a minimum vehicle speed for a first vehicle position (B) where the vehicle will begin to lag on said uphill slope, which results in said downshifting can be postponed or avoided ;

• based on said current vehicle condition, controlling said cruise control in order to, while driving the vehicle towards said first vehicle position (B), increase the vehicle speed to said minimum vehicle speed when said vehicle has finally reached said first position of the vehicle (B).

This embodiment is disclosed in Figure 5, where the vehicle speed curve 52 is identical to the vehicle speed curves 42 and 2 in Figures 4 and 1, respectively. A vehicle speed curve 55 discloses a vehicle speed curve where it is predicted, with the knowledge of the

ES 2 532 467 T3 current vehicle conditions, that if the vehicle passes through said position B with a minimum vehicle speed of v_pendingand then it will be possible to drive along said uphill slope without the vehicle speed decreasing below the Downshift Speed ​​· In this way, a downshifting in position C can be avoided. As can be seen in Figure 5, as soon as it is predicted, for example, in position A that a minimum vehicle speed on the slope is needed in position B to avoid downshifting, the vehicle will accelerate accordingly between said gear. position A and B in order to reach the slope at position B. A simulation with the current vehicle condition can be used as input data in order to identify the minimum speed of the vehicle on the slope · If the current vehicle condition results in that it is not possible to avoid or sufficiently postpone said downshifting and that a worse fuel efficiency is achieved than if it were not accelerated to a v_pendinge, then said control unit can be programmed to control the speed of the vehicle according to curve 52, that is, no acceleration is performed up to a slope · Correspondingly, a slope can be used for road section profiles 21 and 31. For road profile 21 this is disclosed in Figure 7 and for road profile 31 this is disclosed in Figure 9. Thus, in the embodiments of Figures 7 and 9, the corresponding slope is used as in Figure 5.

In a further embodiment of the invention, said control unit can be programmed to combine said activities described in Figures 4 and 5 or 6 and 7 or 8 and 9. Thus, said control unit can be programmed to carry out the steps from:

• predict whether such downshifting will be postponed long enough or avoided;

• if it is predicted that said downshifting will not be postponed long enough or will not be avoided, then performing said temporary lowering of said downshifting limit;

• and additionally based on said current vehicle condition, calculate a minimum vehicle speed for a first vehicle position where the vehicle will begin to lag behind said uphill slope and which will result in said downshifting can be postponed long enough or avoid;

• based on said current vehicle condition, controlling said cruise control in order to, while driving the vehicle towards said first vehicle position, increasing the speed of the vehicle to said minimum vehicle speed when said vehicle has finally reached said first vehicle position.

The activity where the downshift speed temporarily decreases is more efficient in fuel consumption compared to the activity where the vehicle speed increases to said minimum speed of the vehicle on the slope. Therefore, it is predicted in the first place whether the temporarily decreased downshifting speed will be sufficient or not, and whether both activities will not be able to be used.

In another embodiment of the invention, said increase of a vehicle speed up to said minimum speed of the pending vehicle is only allowed if the difference between said target vehicle speed set vcc target speed set and said minimum speed of the vehicle on slope is below of a default value. Said control unit can also be programmed not to allow a v_pendinge above a default value, such as v_bcc.

In a further embodiment of said invention, said temporary reduction of a downshift limit of said currently engaged gear is activated while driving on said uphill slope, which means, for example, from position B and up to a crest (not shown), or to a position where the vehicle speed has started to accelerate again and the engine rotational speed has increased to ^{above v}downshift speed^.

In a further embodiment, the vehicle can be equipped with an adaptive cruise control (ACC). ACC will record if another vehicle is relatively close ahead of said vehicle when, for example, it is driven in one of the above-mentioned vehicle conditions. Said control unit can be programmed not to initiate said increase in vehicle speed up to said minimum speed of the pending vehicle according to one of the aforementioned embodiments as long as said ACC registers another relatively close vehicle ahead of said vehicle.

Figure 10 shows an apparatus 500 according to an embodiment of the invention, comprising a non-volatile memory 520, a processor 510 and a read and write memory 560. The memory 520 has a first memory part 530, in which is stored a computer program to control apparatus 500. The computer program in memory portion 530 to control apparatus 500 may be an operating system.

ES 2 532 467 T3

The apparatus 500 may be enclosed, for example, in a control unit, such as the aforementioned control unit in such a control system. The data processing unit 510 may comprise, for example, a microcomputer.

The memory 520 also has a second memory part 540, in which a program for controlling a cruise control of a vehicle according to the invention is stored. In an alternative embodiment, the program for controlling said vehicle cruise control is stored in a separate non-volatile data storage medium 550, such as, for example, a CD or interchangeable semiconductor memory. The program can be stored in an executable form or in a compressed state.

When it is stated in the following that the data processing unit 510 executes a specific function, it should be clear that the data processing unit 510 executes a specific part of the program stored in memory 540 or a specific part of the program stored in the non-volatile recording medium 550.

The data processing unit 510 is designed to communicate with the memory 550 via a data bus 514. The data processing unit 510 is also designed to communicate with the memory 520 via a data bus 512. In addition, the data processing unit Data processing 510 is designed to communicate with memory 560 via a data bus 511. The data processing unit 510 is also designed to communicate with a data port 590 through the use of a data bus 515.

The method according to the present invention can be executed by the data processing unit 510, by the data processing unit 510 which executes the program stored in the memory 540 or the program stored in the non-volatile recording medium 550.

The invention should not be considered limited to the embodiments described above, but rather a number of further variants and modifications are conceivable within the scope of the following patent claims.