WO2023025528A1

WO2023025528A1 - Support method and support device for uphill starting-off processes of a vehicle combination, and vehicle combination comprising the support device

Info

Publication number: WO2023025528A1
Application number: PCT/EP2022/071543
Authority: WO
Inventors: Horst Eckert
Original assignee: Zf Cv Systems Europe Bv
Priority date: 2021-08-24
Filing date: 2022-08-01
Publication date: 2023-03-02
Also published as: DE102021121832A1

Abstract

The present invention relates to support methods (800, 900) and support devices (23) for uphill starting-off processes of vehicle combinations (1), and to a towing vehicle (2). In order to spatially separate the functions "brake" and "motor" from each other as much as possible and to be gentle on the vehicle clutch, during starting off uphill, and in order to keep the front axle of the towing vehicle (2) as steerable as possible, according to the invention, the starting braking force (11) required for holding against the downhill force (10) is provided, with first priority, and, if possible, exclusively, by means of the brake system of the trailer assembly (3). Only with second priority is the brake system of the towing vehicle (2) also used, in particular the brakes on non-driven wheels. As the instantaneous drive force (15, 304, 401, 404, 501, 504) increases, the set braking forces (11) are reduced in succession, in reverse order of their priority, until at the end the vehicle combination (2) is held only by the instantaneous drive force (15, 304, 401, 404, 501, 504) and, as the instantaneous drive force (15, 304, 401, 404, 501, 504) rises further, the vehicle combination starts off in the desired direction of travel (19).

Description

Support method and support device for uphill starting processes of a vehicle combination, vehicle combination comprising the support device

The present invention relates to a hill start assist method according to the preamble of claim 1, to a hill start assist device according to the preamble of claim 7, and to a towing vehicle.

As any motorist knows, starting uphill, especially in manual vehicles, is a difficult and potentially dangerous task: the right foot must switch from the brake pedal to the "accelerator" pedal and the left foot is "bound" to the clutch pedal, momentarily engaging the service brake is not engaged and the motor vehicle begins to roll downhill. Metered addition of the hand or parking brake during this "braking gap" is a well-known makeshift.

DE 196 30 870 A1 discloses a method for starting a motor vehicle, in which the stationary state of the motor vehicle is ensured by braking intervention using an external force if the braking force exerted by the vehicle operator is not sufficient for this. The engine torque is then recorded and the braking intervention is terminated above a specific engine torque. The special cases of an uphill approach and a downhill approach are also considered. It is not disclosed how the method could be applied to a team.

DE 198 02 217 A1 discloses model-based devices and methods with which the drive torque available for the vehicle drive can be determined in a motor vehicle in the transition between idling operation and running under load, which is typical for starting. Further model-based devices and methods are disclosed, with which external influence variables driving or braking the motor vehicle, such as a downhill slope torque, for example, can be determined. Based on the so determined Drive torque and downhill torque is proposed for a method and a device to support starting uphill, to influence a service brake and/or a parking brake of the motor vehicle in such a way that the sum of braking torque and drive torque is greater than the downhill torque. It is not disclosed how the method could be applied to a team.

DE 199 25 249 A1 discloses control methods to support a starting process of a motor vehicle. After clear detection of a desire to start off, the braking force initially applied is reduced in a dosed manner over a period of time dt in accordance with a function that is constant over time. It is not disclosed how the method could be applied to a team.

For combinations of towing vehicle and towed vehicle (trailer), DE 44 12 430 C1 discloses a method and a device for the brake force distribution between towing vehicle and trailer, taking into account the coupling force between them, based on an energy balance established at several points in time. Nothing is disclosed regarding the special case of starting off, in particular on a longitudinally inclined roadway.

DE 10 2015 115 851 A1 discloses a method for operating a vehicle combination in which—together with other input variables—information about the gradient angle of the roadway beneath the vehicle combination is read. Output variables, including front-axle load information and rear-axle load information, are determined from the input variables. The output variables are used to control a brake system of the vehicle combination. Nothing is disclosed regarding the special case of starting off, in particular on a longitudinally inclined roadway.

The object of the invention is therefore to specify a support method and a support device for uphill starting processes of a vehicle combination. A further object of the invention is to specify a vehicle comprising such a support device.

These objects are solved with the features of the independent claims. Dependent claims are directed on preferred embodiments of the invention.

Accordingly, the support method and the support device are set up for use in a vehicle combination comprising a towing vehicle and a trailer arrangement, the towing vehicle having an electronic control unit and a valve arrangement connected to the control unit in a signal-conducting manner for setting a trailer brake pressure that is independent of the driver's will, and the control unit is equipped and configured to adjust trailer brake pressure and tow vehicle brake pressures by increasing, holding, or decreasing as needed.

At the beginning of each uphill start-up process, when no engine torque and no resulting driving force is acting on the vehicle combination, i.e. when a momentary driving force is equal to zero, the vehicle combination only stands still if the starting brake pressures have been set in such a way that a total of them results Starting braking force prevents the vehicle combination from rolling downhill.

The basic idea of the invention is to provide this starting braking force primarily and as far as possible exclusively by the braking system of the trailer arrangement as a trailer braking force. In the case of an incipient and constantly increasing effectiveness of the engine torque and the resulting instantaneous driving force, an instantaneous trailer brake pressure is then continuously adjusted in such a way that the sum of the trailer braking force and the instantaneous driving force prevents the vehicle from rolling downhill. For this purpose, the trailer braking force is reduced until the vehicle combination is only supported by the current driving force is maintained and then starts to move in the desired direction as the current driving force continues to increase.

The support method should expediently allow the driver of the vehicle to cause a higher trailer brake pressure than the instantaneous trailer brake pressure by actuating the service brake valve. When the service brake valve is then released, the instantaneous trailer brake pressure is set again as described above.

In an advantageous development, if the braking capacity of the trailer arrangement is not sufficient to prevent the vehicle combination from rolling downhill, in addition to the trailer arrangement that is braked and applying a first partial braking force, the braking system of the towing vehicle is also controlled in such a way that it uses the remaining, still missing braking force as residual braking force and applies second partial braking force.

Here, too, the braking pressures involved are generally adjusted continuously at the onset and steadily increasing effectiveness of the engine torque and the resulting instantaneous driving force so that at least the rolling downhill is prevented and the vehicle combination is enabled to start. For this purpose, the partial braking forces are reduced to zero in the reverse order of their ranking. The residual braking force on the towing vehicle is therefore first reduced, and only when this has been completely dissipated is the trailer braking force reduced until the vehicle combination is finally only held by the current driving force and then drives off in the desired direction as the current driving force continues to increase.

In a further advantageous development, if part of the starting braking force has to be provided by the towing vehicle as residual braking force, the braking system of the towing vehicle is controlled in such a way that the residual braking force is provided secondarily by brakes on non-driven axles of the towing vehicle. Only if the braking capacity of the brakes on the non-driven axles of the If the towing vehicle is not sufficient to provide the residual braking force, the brakes on the driven axles of the towing vehicle are also controlled as a third priority. Here, too, in the case of an incipient and steadily increasing effectiveness of the engine torque and the resulting instantaneous driving force, the partial braking forces are successively lowered to zero in reverse order of their rank. So here in succession first the braking force applied by brakes on driven towing vehicle axles, then the braking force applied by brakes on non-driven towing vehicle axles, and finally the braking force applied by the brake system of the trailer arrangement.

In a further advantageous development, the towing vehicle has a trailer detection unit. The support method is then only active when the trailer detection unit has detected the presence of a trailer arrangement.

In a further advantageous development, the towing vehicle has an actuating element in the driver's cab, with which the vehicle driver can activate or deactivate the support method. If the driver of the vehicle has activated the support method, the support method remains active until it has successfully ensured that the vehicle combination was able to move off. It can advantageously be deactivated again when a deactivation driving speed of, for example, 20 km/h is reached.

In a further advantageous development, the support method is expanded in such a way that misuse as a service brake or parking brake or as a stretch braking function is prevented. Criteria are checked for this. These can be positive criteria, which directly indicate misuse, or negative criteria, the presence of which indicates that the support procedure is being used properly. If at least one positive criterion is met, or if at least one negative criterion is not met, this can be interpreted as an indication of misuse. Examples of positive criteria can be:

- The assistance process is activated at speeds well above zero, e.g. above 2 km/h,

- the drive motor has been switched off intentionally,

- the driver has left his driver's seat.

Examples of negative criteria can be:

- a driving gear has been engaged within e.g. 5 seconds after activation of the support process,

- the accelerator pedal has been pressed within e.g. 5 seconds after activation of the support process,

- The vehicle clutch has been actuated within, for example, 5 seconds after activation of the support method.

If misuse is indicated, a warning signal can be output to the driver of the vehicle as the first warning stage, such as a continuous honking, flashing and/or a haptic warning. If the first warning level is unsuccessful, the parking brake can be automatically engaged as a second warning level, if possible.

An advantage of the support method and the support device according to the invention is that on the axles of the vehicle combination, ie the towing vehicle and the trailer arrangement, the “brake” and “motor” functions are spatially separated from one another as far as possible. Only the engine driving the vehicle combination acts on a drive axle of the vehicle combination, and braking takes place as far as possible only on non-driven axles, primarily on those of the trailer arrangement. As a result, when starting off on an incline, the engine does not first have to work “against the brakes” in order to generate a first effective drive torque on the drive axle or axles. The advantageous consequence of this is that the vehicle clutch between the vehicle engine and the driving gear is protected. A further advantage of the support method and the support device is that the front axle of the towing vehicle, which is usually the steering axle of the towing vehicle, is not braked or only to an unavoidable extent. This has the advantage that even with low coefficients of friction between the tire surfaces and the road (e.g. on icy ground), the vehicle combination remains fully steerable within the bounds of the physical conditions, especially when starting off; the front axle wheels will not lock, or at least not as quickly, due to braking, and the vehicle will not "push over the front axle" as quickly when starting off, ie it will not be steerable.

A vehicle combination is to be understood here as meaning both a truck and a semi-trailer combination. Accordingly, the term "trailer assembly" is used herein to include configurations of one or more trailers and/or semi-trailers.

Here, the term “uphill launch” is intended to include both a forward launch on a roadway that is ascending in the direction of travel and a reverse launch on a roadway that is descending in the direction of travel. The latter may be necessary if another vehicle is parked directly in front of the parked vehicle combination, or parking the vehicle combination was only possible directly in front of an obstacle. Correspondingly, the downhill roll to be prevented can include both a reverse downhill roll on a roadway that is uphill in the direction of travel and a forward downhill roll on a roadway that is downhill in the direction of travel.

Other characteristics and advantages of the invention will now be explained by means of the description given by way of non-limiting example and with reference to the drawings. show in it

1 in a symbolic representation components of a vehicle combination,

2 shows the forces acting on the center of gravity of the vehicle combination in a symbolic representation, 3 variables involved in a first embodiment of the invention,

4 variables involved in a second embodiment of the invention,

5 variables involved in a third embodiment of the invention,

6 in symbolic form steps of a misuse prevention method,

7 a symbolic representation of further components of the towing vehicle,

8 shows a first support method according to the invention in a symbolic representation, and

9 shows a second support method according to the invention in a symbolic representation.

1 shows a symbolic representation of a vehicle combination 1 that includes a towing vehicle 2 and a trailer arrangement 3 . The towing vehicle 2 has an electronic control unit 4 and a valve arrangement 5, which is connected to the control unit 4 in a signal-conducting manner, for setting a trailer brake pressure 6 that is independent of the driver's will. As an alternative to the arrangement of the valve arrangement 5 in the towing vehicle 2, a valve arrangement 5' for adjusting the trailer brake pressure 6 can also be arranged in the trailer arrangement 3. The control unit 4 is equipped and configured to adjust the trailer brake pressure 6, in particular a trailer starting brake pressure 14, by increasing, holding or decreasing as required. At the brakes of the towing vehicle 2, the control unit 4 can set, increase or decrease a towing vehicle brake pressure 7, in particular a towing vehicle starting brake pressure 13.

The towing vehicle 2 can, of course, have more than the two axles shown symbolically in FIG.

As indicated by dashed lines in FIG. 1, the trailer assembly 3 comprises one or more trailers or semi-trailers as components. In the following, "trailer braking pressure" or "trailer braking force" should always mean the sum of the respective values of all components. The components of the trailer arrangement 3 can, of course, also have more than the two axles shown symbolically in FIG. If the components are of the semi-trailer type, they can also have only one axle.

2 shows the forces acting on the center of gravity 12 of an imaginary vehicle combination 1 at rest in a symbolic and not quantitative representation. The direction of travel 19 is from right to left. The roadway 17 is inclined relative to the horizontal 18 by a roadway inclination angle 16; in the case shown in FIG. 2, the roadway is uphill in the direction of travel 19. Due to this inclination 16 of the roadway 17 under the vehicle combination 1, the weight force 8 of the vehicle combination acting in the center of gravity 12 can be mentally broken down into a normal force 9 acting perpendicular to the roadway and a downhill force 10 acting parallel to the roadway 17. A force that may be acting on the vehicle combination 1 instantaneous driving force 15 and a combination braking force 11 resulting from all braking pressures 6, 7, 13, 14 also act parallel to the roadway 17, but in the opposite direction. The vehicle combination 1 is at a standstill when the downhill slope force 10 and the sum of the combination braking force 11 and the instantaneous driving force 15 balance out to the extent that the area of static friction is not left.

If the instantaneous driving force 15 is zero, the trailer braking force 11 alone must counteract the downhill force 10 . The slope force 10 and thus also the initial braking force required to compensate for it can be determined at the start of the support method 800, 900 on the basis of information about the mass of the vehicle and the road gradient 16. The road gradient 16 can be determined, for example

• from received GPS data,

• from (locally stored or currently received) map data containing height information,

• slope data received from nearby transmitters, or • from a combination of longitudinal acceleration data and engine acceleration data.

The current engine torque can be called up via the CAN bus. With knowledge of the gear engaged, the drag braking effects involved and the effective tire diameter, the engine torque can be converted into a really effective instantaneous driving force 15 .

Figure 3 comprises sub-diagrams 308, 309 and 310, and shows entities involved in a first embodiment of the invention. Above a horizontal axis 302 that is common to all three sub-diagrams 308, 309 and 310, the course of the instantaneous driving force 301 is shown in the upper, first sub-diagram 308, the course of the trailer braking force 303 in the middle, second sub-diagram 309, and the course of the first trailer speed 305 shown.

The three partial diagrams 308, 309 and 310 can be interpreted in two different ways: In a first interpretation, the horizontal axis 302 represents time second time range 312 corresponding to times from and above the first time limit 307 indicated. In this interpretation, the three partial diagrams together describe the time sequence of an uphill starting process according to the invention. As shown in the first partial diagram 308 , the momentary driving force 301 increases linearly over time 302 during this starting process. In this case, as shown in partial diagram 309, according to the invention, trailer braking force 303 is reduced linearly over time until it has dropped to the value zero at first time limit 307.

In the first time period 311, the reduction in the trailer braking force 303 is measured in such a way that it just compensates for the increase in the instantaneous driving force 301. The total force counteracting the slope force 10 The instantaneous driving force 301 and trailer braking force 303 therefore remains constant, in fact so large that the vehicle combination 1 is prevented from rolling downhill: As the third partial diagram 310 shows, the first combination speed 305 is therefore constantly equal to zero in the first time range 311.

In the second time range 312, the assumed instantaneous driving force 301 continues to grow, but the trailer braking force 303 remains equal to zero. On balance, a driving force that increases linearly over time 302 in the starting direction acts on the vehicle combination, so that, as shown in the third partial diagram 310, a first combination speed 305 that starts at zero and then increases non-linearly is set.

In a second interpretation, both the horizontal axis 302 and the vertical axis 301 represent the instantaneous driving force. The auxiliary line 307 then represents a first force limit, namely that instantaneous driving force that alone is capable of compensating for the slope force 10 . In this interpretation, the first partial diagram 308 shows the dependence of the current drive force 301 on itself 302, and is therefore meaningless. The second sub-diagram 309 now illustrates how, depending on the instantaneous driving force 304, the trailer braking force 303 must be selected so that the force balance prevents the vehicle combination 1 from rolling downhill. This relationship applies to drive force values that are less than or equal to first force limit 307 . In this interpretation, nothing is assumed or stated about the course over time of the instantaneous driving force 301 and the trailer braking force 303 . In the third partial diagram 310, only the part between zero force and the first force limit 307 can be interpreted in this interpretation. It states that if trailer braking force 303 is selected as a function of instantaneous driving force 302 according to second partial diagram 309, first combination speed 305 is always zero, ie the vehicle combination is stationary. Figure 4 comprises four sub-diagrams 411, 412, 413 and 414 and shows quantities involved in a second embodiment of the invention. Above a horizontal axis 402 that is common to all four sub-diagrams 411, 412, 413 and 414, from top to bottom, is the course of the instantaneous driving force 401 in the fourth sub-diagram 411, the course of the towing vehicle braking force 403 in the fifth sub-diagram 412, and the course of the towing vehicle braking force 403 in the sixth sub-diagram 413 the course of the trailer braking force 405 and in the seventh partial diagram 414 the course of the second trailer speed 407 are shown.

The four partial diagrams 411, 412, 413 and 414 can be interpreted in two different ways: In a first interpretation, the horizontal axis 402 represents the time. For the time 402 there is a third time range 415 corresponding to times between zero and a second time limit 409 , a fourth time range 416 corresponding to times between the second time limit 409 and a third time limit 410, and a fifth time range 417 corresponding to times from and above the third time limit 410 indicated. In this interpretation, the four partial diagrams 411, 412, 413 and 414 together describe the chronological sequence of an uphill starting process according to the invention. As the four sub-diagrams 411, 412, 413 and 414 show at the time zero point, at the beginning of the starting process a traction vehicle braking force 403 different from zero and a trailer braking force 405 different from zero are acting here. This starting process also increases, as in the fourth sub-diagram 411 shows the instantaneous driving force 401 over time 402 linearly. In this case, as shown in the fifth partial diagram 412, the traction vehicle braking force 403 is linearly reduced over time in the third time range 415 according to the invention, until it has dropped to the value zero at the time limit 409. As shown in partial diagram 413, trailer braking force 405 remains constant in third time range 415.

In the third time period 415, the reduction in the towing vehicle braking force 403 is dimensioned in such a way that it just compensates for the increase in the instantaneous driving force 401. The total force from the instantaneous drive force 401 , towing vehicle braking force 403 and Trailer braking force 405 thus remains constant, in fact so large that the vehicle combination 1 is prevented from rolling downhill: as in the seventh partial diagram

414 shows, the second trailer speed 407 is therefore in the third time range

415 constantly equal to zero.

In fourth time range 416, traction vehicle braking force 403 remains constantly equal to zero. Here, according to the invention, trailer braking force 405 is reduced linearly over time until it has reached the value zero at third time limit 410 . The reduction in trailer braking force 405 is dimensioned such that it just compensates for the increase in instantaneous driving force 401 . The total force of the instantaneous drive force 401, towing vehicle braking force 403 and trailer braking force 405 that counteracts the slope force 10 remains constant, and so large that the vehicle combination 1 is prevented from rolling downhill: As the seventh partial diagram 414 shows, the second combination speed 407 is therefore also constantly equal to zero in the fourth time range 416 .

In the fifth time period 417, the assumed instantaneous driving force 401 continues to grow, but both the towing vehicle braking force 403 and the trailer braking force 405 remain equal to zero. On balance, a driving force that increases linearly over time 402 in the starting direction acts on the vehicle combination, so that, as shown in the seventh partial diagram 414, a second combination speed 407 that begins at zero and then increases non-linearly is set.

In a second interpretation, both the horizontal axis 402 and the vertical axis 401 represent the instantaneous driving force. The auxiliary line 409 then represents a second force limit, namely that driving force which corresponds to the amount of the towing vehicle braking force 403 prevailing at driving force zero. The auxiliary line 410 then represents a third force limit, namely that driving force which alone is capable of compensating for the downhill force 10 . In this interpretation, the fourth partial diagram 411 shows the dependence of the driving force on itself, and is therefore meaningless. However, partial diagrams 412 and 413 now illustrate how, depending on the instantaneous driving force 404, the towing vehicle braking force 403 and the trailer braking force 405 must be selected so that the force balance prevents the vehicle combination from rolling downhill. This relationship applies to drive force values that are less than or equal to third force limit 410 .

In this interpretation, nothing is assumed or stated about the time profile of the driving force 401, the towing vehicle braking force 403 and the trailer braking force 405. In the seventh partial diagram 414, only the part between zero force and the third force limit 410 can be interpreted. It states that if, depending on the driving force 402, the towing vehicle braking force 403 according to the fifth sub-diagram 412 and the trailer braking force 405 according to the sixth sub-diagram 413 are selected, the combination speed is always zero, the vehicle combination is therefore stationary.

Figure 5 comprises five sub-diagrams 514, 515, 516, 517 and 518, and shows quantities involved in a third embodiment of the invention. Above a horizontal axis 502 that is common to all five sub-diagrams 514, 515, 516, 517 and 518, from top to bottom, in the eighth sub-diagram 514 is the progression of the driving force 501, in the ninth sub-diagram 515 the progression of the towing vehicle braking force on driven wheels 503, the tenth partial diagram 516 shows the course of the traction vehicle braking force on non-driven wheels 505, the eleventh partial diagram 517 shows the course of the trailer braking force 507, and the twelfth partial diagram 518 shows the course of the third trailer speed 509.

The five partial diagrams 514, 515, 516, 517 and 518 can be interpreted in two different ways: In a first interpretation, the horizontal axis 502 represents the time. For the time 502 there is a sixth time range 519 corresponding to times between zero and a fourth Time limit 511, a seventh time range 520 corresponding to times between the fourth time limit 511 and a fifth time limit 512, an eighth time range 521 corresponding to times between the fifth time limit 512 and a sixth time limit 513, and a ninth Time range 522 corresponding to times from and above the sixth time limit 513 are indicated.

In this interpretation, the five partial diagrams 514, 515, 516, 517 and 518 together describe the time sequence of an uphill starting process according to the invention. As they show at the time zero point, at the beginning of the starting process, a non-zero traction vehicle braking force acts on driven wheels 503, a non-zero traction vehicle braking force on non-driven wheels 505, and a non-zero trailer braking force 507. Also in this case As shown in the eighth partial diagram 514 , the drive force 501 increases linearly over time 502 .

In this case, as shown in the ninth partial diagram 515, the traction vehicle braking force at the driven wheels 503 is linearly reduced over time in the sixth time range 519 according to the invention, until it has dropped to the value zero at the fourth time limit 511. The towing vehicle braking force at non-driven wheels 505 and the trailer braking force 507 remain constant in sixth time range 519, as shown in partial diagrams 516 and 517. In the sixth time period 519, the reduction in the traction vehicle braking force on the driven wheels 503 is dimensioned in such a way that it just compensates for the increase in the driving force 501. The total force of driving force 501, traction vehicle braking force on driven wheels 503, traction vehicle braking force on non-driven wheels 505, and trailer braking force 507 that counteracts the downhill slope force 10 remains constant, and is so large that the vehicle combination 1 is prevented from rolling downhill: as in the partial diagram 518 shows, the third vehicle-vehicle speed 509 is therefore constantly equal to zero in the sixth time range 519.

In the seventh time period 520, the traction vehicle braking force at the driven wheels 503 remains constantly equal to zero. Here, according to the invention, the traction vehicle braking force on non-driven wheels 505 is reduced linearly over time until it has reached the value zero at fifth time limit 512 . As shown in the eleventh sub-chart 517, the trailer braking force 507 remains in the seventh Time range 520 constant. The reduction in traction vehicle braking force at non-driven wheels 505 is proportioned to just offset the increase in driving force 501 . The total force of driving force 501, traction vehicle braking force on driven wheels 503, traction vehicle braking force on non-driven wheels 505 and trailer braking force 507, which counteracts the slope force 10, remains constant, and so large that the vehicle combination 1 is prevented from rolling downhill: like the twelfth Partial diagram 518 shows that third vehicle-vehicle speed 509 is therefore also constantly equal to zero in seventh time period 520 .

In the eighth time period 521, the traction vehicle braking force at driven wheels 503 and the traction vehicle braking force at non-driven wheels 505 remain constantly equal to zero. Here, according to the invention, trailer braking force 507 is reduced linearly over time until it has reached the value zero at sixth time limit 513 . The reduction in trailer braking force 507 is proportioned to just compensate for the increase in driving force 501 . The total force of driving force 501, traction vehicle braking force on driven wheels 503, traction vehicle braking force on non-driven wheels 505 and trailer braking force 507, which counteracts the slope force 10, remains constant, and so large that the vehicle combination 1 is prevented from rolling downhill: like the twelfth Partial diagram 518 shows that third vehicle-vehicle speed 509 is therefore also constantly equal to zero in eighth time range 521 .

In the ninth time period 522, the assumed driving force 501 continues to increase, but both the towing vehicle braking force at driven wheels 503 and the towing vehicle braking force at non-driven wheels 505 and the trailer braking force 507 remain equal to zero. On balance, a driving force that increases linearly over time 502 in the starting direction acts on the vehicle combination, so that, as shown in the twelfth partial diagram 518, a third combination speed 509 that starts at zero and then increases non-linearly is set. In a second interpretation, both the horizontal axis 502 and the vertical axis 501 represent the driving force. The auxiliary line 511 then represents a fourth force limit, namely the driving force that corresponds to the magnitude of the traction vehicle braking force at driven wheels 503 when the driving force is zero. The auxiliary line 512 then represents a fifth force limit, and the auxiliary line 513 then represents a sixth force limit, namely that driving force which alone is capable of compensating for the downhill slope force 10 . In this interpretation, the eighth partial diagram 514 shows the dependence of the driving force on itself, and is therefore meaningless.

However, partial diagrams 515, 516 and 517 now illustrate how, depending on the current driving force 504, the tractor vehicle braking force at driven wheels 503, the tractor vehicle braking force at non-driven wheels 505 and the trailer braking force 507 must be selected so that the balance of forces The vehicle combination is prevented from rolling downhill. This relationship applies to drive force values that are less than or equal to sixth force limit 513 .

This interpretation neither assumes nor says anything about the time profile of the driving force 501, the towing vehicle braking force at the driven wheels 503, the towing vehicle braking force at the non-driven wheels 505 and the trailer braking force 507. In the twelfth partial diagram 518, only the part between zero force and the sixth force limit 513 can be interpreted. It says that if, depending on the driving force 502, the towing vehicle braking force on driven wheels 503 according to the ninth sub-diagram 515, the towing vehicle braking force on non-driven wheels 505 according to the tenth sub-diagram 516, and the trailer braking force 507 according to the eleventh sub-diagram 517 can be selected, the vehicle combination speed is always zero, i.e. the vehicle combination is stationary.

6 shows the steps of a misuse prevention method 600 in symbolic form. In an advantageous development, the support method 800, 900 can be expanded in such a way that misuse as a parking brake/parking brake is ruled out. Such abuse could be sought to protect the brake system of the towing vehicle at the expense of the brake system of the trailer assembly.

Criteria are checked for this. These can be positive criteria, which directly indicate misuse, or negative criteria, the presence of which indicates proper application of the support procedure 800, 900. If at least one positive criterion is met, or if at least one negative criterion is not met, this can be interpreted as an indication of misuse.

Examples of positive criteria can be:

- The support method 800, 900 is activated at speeds well above zero, e.g. above 2 km/h,

- the drive motor has been switched off intentionally,

- the driver has left his driver's seat.

Examples of negative criteria can be:

- within e.g. 5 seconds after activation of the support process 800, 900 a driving gear has been engaged,

- the engaged driving gear drives the vehicle combination against the effective direction of the downhill force,

- within e.g. 5 seconds after activation of the support method 800, 900 the accelerator pedal has been actuated,

- within e.g. 5 seconds after activation of the support method 800, 900 the vehicle clutch has been actuated.

If misuse is indicated, a warning signal can be output 602 to the driver of the vehicle as the first warning level, such as a continuous honking, continuous flashing and/or a haptic warning. If the first warning level is unsuccessful, the parking brake can be automatically engaged as a second warning level if possible 603. A further possibility of misuse consists in misusing the support method 800, 900 for possibly inadmissible extension braking. Here, too, the motivation would be to protect the braking system of the towing vehicle at the expense of the braking system of the trailer arrangement. This type of misuse can also be prevented by the fact that the support method 800, 900 can only be activated from the state of a standstill or a very low speed of the vehicle combination. This is not shown in FIG.

FIG. 7 shows further components of the towing vehicle 2 from FIG. 1 in a symbolic representation. According to advantageous developments of the invention, the towing vehicle 2 can also include a trailer detection unit 20 and/or an actuating element 21 and preferably a support device 23 . The support device 23 for an uphill drive-off process comprises an electronic control unit 4 of a towing vehicle 2, and a valve arrangement 5, which is connected to the control unit 4 in a signal-conducting manner, for setting a trailer brake pressure 6 that is independent of the driver's will, with the control unit 4 being equipped and configured to control towing vehicle brake pressures 7 and the Set trailer brake pressure 6 as needed by increasing, holding, or decreasing.

If a trailer detection unit 20 is present, the control unit 4 is advantageously equipped and configured in such a way that the trailer detection unit 20 is used to determine whether a trailer arrangement 3 is coupled to the towing vehicle 2, and that the support method 800, 900 according to the invention is only carried out if a trailer assembly 3 is coupled.

If an actuating element 21 is present, the control unit 4 is advantageously equipped and configured in such a way that the actuating element 21 is used to determine whether the vehicle driver is using the support method 800, 900 activated. Only when or only when the vehicle driver has activated the support method 800, 900 is this carried out. In an advantageous development, after the start of support process 800, 900, when a deactivation driving speed is reached for the first time, support process 800, 900 can be deactivated again. This advantageously means that the vehicle driver has to actively initiate each application of the support method 800, 900. This is a safety gain, especially with frequently changing drivers.

8 shows a first support method 800 according to the invention in a symbolic representation. In a first method step “Setting” 801, at the beginning of the uphill start-up process, the towing vehicle brake pressure 7 and the trailer brake pressure 6 are set as instantaneous brake pressures 7, 6 to starting brake pressures 13, 14, which are selected in such a way that a combination braking force 11 at least one of the vehicle combination 1 is prevented from rolling downhill. In a second method step “Reduce” 802, during the uphill starting process, the instantaneous brake pressures 7, 6 are reduced with a constantly increasing driving force 15 to such an extent that the sum of the combination braking force 11 and the driving force 15 at least prevents the vehicle combination 1 from rolling downhill. To achieve the advantages of the invention, in the setting step 801 only the trailer brake pressure 6 is set 803 as far as possible, and in the reducing step 802 only the trailer brake pressure 6 is reduced as far as possible 804.

9 shows a second support method 900 according to the invention in a symbolic representation. In a third method step 901, at the beginning of the uphill starting process, a check is made once to determine whether the test criterion applies that the trailer brake pressure 6 alone can produce the trailer brake force 11, which at least prevents the vehicle from rolling downhill. In the event that the test criterion does not apply 905, the trailer brake pressure 6 is set to a maximum possible trailer brake pressure 902 and the towing vehicle brake pressure 7 is set so that the trailer brake pressure 6 and the towing vehicle Brake pressure 7 resulting trailer brake force 11 at least prevents the downhill roll 903. In the event that the test criterion applies 907, the trailer brake pressure 6 is adjusted so that the trailer brake pressure 6 resulting trailer brake force 11 at least prevents the downhill roll 906. In both cases, during the uphill -Starting process with constantly increasing drive force 15, if necessary, first reduce the towing vehicle brake pressure 7 to zero and then reduce the trailer brake pressure 6 904.

List of reference symbols (part of the description)

vehicle combination

towing vehicle

trailer arrangement

control unit

valve assembly

trailer brake pressure

Towing vehicle brake pressure

Weight force roadway normal force

downhill force

Vehicle combination starting braking force/trailer combination braking force

main emphasis

Towing vehicle starting brake pressure

Trailer starting brake pressure

driving force

roadway inclination angle

roadway

horizontal

driving direction

trailer detection unit

actuator

trailer hitch

support device

Driving force horizontal axis, time or driving force

Trailer braking force instantaneous driving force first trailer speed first time limit, first force limit first sub-diagram second partial diagram third partial diagram first time range second time range instantaneous driving force horizontal axis, time or driving force

Towing vehicle braking force instantaneous driving force

Trailer braking force second trailer speed second time limit, second force limit third time limit, third force limit fourth sub-diagram fifth sub-diagram sixth sub-diagram seventh sub-diagram third time area fourth time area fifth time area instantaneous driving force horizontal axis, time or driving force

Braking force on driven wheels of the towing vehicle instantaneous driving force

Braking force on non-driven wheels of the towing vehicle

Trailer braking force third trailer speed fourth time limit, fourth force limit fifth time limit, fifth force limit sixth time limit, sixth force limit eighth partial diagram ninth partial diagram tenth partial diagram eleventh partial diagram twelfth partial diagram sixth time range seventh time range eighth time range ninth time range

Abuse Prevention Procedures

Process step "Check criteria"

Process step “Warn driver”

Method step "engage parking brake" first support method

“Setting” process step

Process step “reduce”

Method step “Adjust trailer brake pressure”

Method step “Reduce trailer brake pressure” second support method

Process step “Check”

Process step "Adjust maximum possible trailer brake pressure"

Method step "Setting the towing vehicle brake pressure"

Process step “reduce”

Test criterion does not apply

Method step “Adjust trailer brake pressure”

test criterion applies

Claims

25 patent claims

1 . Support method (800) for an uphill starting process of a vehicle combination (1) comprising a towing vehicle (2) and a trailer arrangement (3), the towing vehicle (2) having an electronic control unit (4) and a valve arrangement connected to the control unit (4) in a signal-conducting manner (5, 5') for setting a trailer brake pressure (6) that is independent of the driver's will, and the control unit (4) is equipped and configured to set towing vehicle brake pressures (7) and the trailer brake pressure (6) as required by increasing, maintaining or lowering, the support method (800) comprising the steps: a) at the beginning of the uphill starting process, setting a towing vehicle brake pressure (7) and the trailer brake pressure (6) as instantaneous brake pressures (7, 6) to starting brake pressures (13, 14) that are selected in this way are that a combination braking force (11) resulting from them at least prevents the vehicle combination (1) from rolling downhill (801), b) during the uphill starting process ganges with a constantly increasing instantaneous driving force (15) reducing the instantaneous braking pressures (7, 6) to such an extent that the sum of the combination braking force (11) and the instantaneous driving force (15) at least prevents the vehicle combination (1) from rolling downhill (802 ), and characterized in that c) in the setting step (801) only the trailer brake pressure (6) is set as far as possible (803), and d) in the reducing step (802) only the trailer brake pressure (6) is reduced as far as possible (804 ).

2. Support method (900) according to Claim 1, characterized by the additional steps: e) at the beginning of the uphill starting process, check (901) whether the test criterion applies that the trailer brake pressure (6) alone produces the trailer brake force (11) which is at least prevents rolling downhill f) if the test criterion does not apply (905), setting the trailer brake pressure (6) to a maximum possible trailer brake pressure (902) and setting the towing vehicle brake pressure (7) so that the trailer brake pressure (6) and the towing vehicle brake pressure ( 7) the resulting trailer braking force (11) at least prevents rolling downhill (903), g) if the test criterion applies (907), adjusting the trailer brake pressure (6) such that the trailer braking force (11) resulting from the trailer braking pressure (6) at least prevents rolling downhill (906), and in both cases h) during the uphill starting process with steadily increasing instantaneous driving force (15), possibly first reducing the towing vehicle brake pressure (7) to zero and then reducing the trailer brake pressure (6) (904).

3. Support method (900) according to claim 2, characterized in that in step f) the setting of the towing vehicle brake pressure (7) is carried out as far as possible by setting brake pressures on non-driven wheels of the towing vehicle (2), and in step h) reducing the towing vehicle brake pressure (7) is reduced as far as possible by reducing the braking pressures on the non-driven wheels of the towing vehicle (2).

4. Support method (800, 900) for an uphill starting process of a towing vehicle (2), which has an electronic control unit (4), a valve arrangement (5) connected to the control unit (4) in a signal-conducting manner for setting a trailer brake pressure (6) that is independent of the driver's will , and has a trailer detection unit (20), wherein the control unit (4) is equipped and configured to adjust towing vehicle brake pressures (7, 13) and a trailer brake pressure (6) as required by increasing, maintaining, or decreasing, the support method (800, 900) including the steps:

Determining with the trailer detection unit (20) whether a trailer arrangement (3) is coupled to the towing vehicle (2), if a trailer arrangement (3) is coupled, carrying out the support experience (800, 900) according to one of Claims 1 to 3.

5. Support method (800, 900) for an uphill start-up process of a towing vehicle (2), which has at least one electronic control unit (4), a valve arrangement (5) connected to the control unit (4) in a signal-conducting manner for setting a trailer brake pressure (6 ), and has an actuating element (21), wherein the control unit (4) is equipped and configured to set towing vehicle brake pressures (7, 13) and a trailer brake pressure (6) as required by increasing, holding or decreasing, the support method (800, 900 ) comprising the steps:

Determining with the actuating element (21) whether the vehicle driver has activated the support method (800, 900) when the vehicle driver has activated the support method (800, 900), carrying out the support experience (800, 900) according to one of claims 1 to 4, when a deactivation driving speed is reached: deactivation of the support method (800, 900).

6. support method (800, 900) according to any one of the preceding claims, characterized by the additional steps:

Checking criteria indicative of abuse of the assistance process (800, 900), if abuse is detected, warning the vehicle operator and/or terminating the assistance process (800, 900).

7. Support device (23) for an uphill starting process, comprising an electronic control unit (4) of a towing vehicle (2), and a signal-conducting valve arrangement (5) connected to the control unit (4) for setting a trailer brake pressure (6) that is independent of the driver's will, wherein the control unit (4) is equipped and configured to adjust towing vehicle brake pressures (7) and trailer brake pressure (6) as required by increasing, maintaining, or decreasing, characterized in that the control unit (4) is equipped and 28 is configured to perform the support method (800, 900) according to any one of claims 1 to 3.

8. Support device (23) for an uphill starting process, comprising an electronic control unit (4) of a towing vehicle (2), a signal-conducting valve arrangement (5) connected to the control unit (4) for setting a trailer brake pressure (6) that is independent of the driver's will, and a Trailer detection unit (20), wherein the control unit (4) is equipped and configured to adjust towing vehicle brake pressures (7) and the trailer brake pressure (6) as required by increasing, maintaining, or lowering, characterized in that the control unit (4) is equipped and configured to carry out the support method (800, 900) according to claim 4.

9. Support device (23) for an uphill starting process, comprising at least one electronic control unit (4) of a towing vehicle (2), a valve arrangement (5) connected to the control unit (4) in a signal-conducting manner for setting a trailer brake pressure (6) that is independent of the driver's will and an actuating element (21), the control unit (4) being equipped and configured to set the towing vehicle brake pressures (7) and the trailer brake pressure (6) as required by increasing, holding or lowering, characterized in that the control unit (4) is equipped and configured is to perform the support method (800, 900) according to claim 5.

10. Support device (23) according to any one of claims 7 to 9, characterized in that the control unit (4) is equipped and configured to carry out the following additional steps:

Checking criteria indicative of abuse of the assistance process (800, 900), if abuse is detected, warning the vehicle operator and/or terminating the assistance process (800, 900). 29

11 . Towing vehicle (2), characterized in that there is a

A support device (23) as claimed in any one of claims 7 to 10.