DE102012002690A1 - Method for controlling anti-lock braking system acting on braking force and anti-slip regulation system acting on engine power of all-wheel-driven motor car, involves determining car speed and providing speed values to control system - Google Patents

Abstract

The method involves determining motor car speed by a global positioning system (GPS) such that values of the speed are provided to a control system. Rotation speed sensors are provided at anti-lock braking system (ABS) for forwarding a slippage of a driving wheel to an ABS control system. The rotation speed sensors are provided at anti-slip regulation (ASR) systems for forwarding the slippage of the driving wheel to an ASR control system. The slippage of the driving wheel is forwarded to a common control system, when the speed sensors are provided at the ABS and ASR systems.

Description

The invention relates to a method for controlling both the ABS system for acting on the braking force and the ASR system for acting on the engine power of a motor vehicle according to the preamble of patent claim 1.

Motor vehicles of modern design have an anti-lock braking system (ABS) and usually an anti-slip regulation (ASR). Both systems are designed to improve driving safety and prevent excessive wear on the running surfaces of the wheels. With heavy braking, the ABS prevents overriding the brake pressure with the risk of blocking wheels. When braking the steerability and directional stability of the motor vehicle is maintained and the braking distance is shortened both on dry and wet roads.

Traction Control (ASR) is a traction control system that prevents a motor vehicle from starting with too much gas (cavalier start) or when starting off on a bad surface, such as on ice, snow or chippings, etc. due to one or more spinning wheels breaks out laterally. The ASR specifically intervenes in the brake and / or engine management if there is too much slip of the drive wheels and the wheels are in danger of turning over. It is the task of the ASR to maintain the traction and the driving stability of the motor vehicle during the acceleration phase both on straight and cornering. Under slip is to be understood on the one hand, the slip of the tire contact patch and on the other hand, the behavior of the slipping wheel when braking or when accelerating the motor vehicle. To determine the slip, the rotational speed of a driven wheel is set in relation to the rotational speed of a non-driven wheel. The slip is therefore in a dependency ratio of the speed and the transmitted forces. If a vehicle wheel is accelerated or braked so much that the maximum static friction force is exceeded, the slip increases up to a maximum in which the drive wheel uncontrollably rotates or slips or blocks. The ABS has z. For example, at 20 percent brake slip, the effect that in the period in which the vehicle travels a distance of one meter, the wheels roll only 0.8 meters. After reaching the maximum deceleration, the slip continues to increase with decreasing braking force until the wheel finally locks up. In the locked state, the wheel is braked only by the sliding friction.

It is also conceivable that both driven wheels spin an axle. If a driven wheel continues to be accelerated, its torque and consequently also the drive torque increase, as a result of which the wheel slip increases overall. As the drive torque increases, the transmittable torque on the driven wheel continues to drop and the wheel tends to spin. The slip can occur on any driven wheel, regardless of whether one, two or more axles of the motor vehicle are driven.

The invention relates to the known Global Positioning System (GPS). Due to the continuous recalculation of the current position, a GPS receiver present in the motor vehicle can calculate the speed and the direction of movement of the motor vehicle exactly.

From the DE 10 2007 037 346 A1 a control device for a brake system of a commercial vehicle and a method for controlling a brake system is known, wherein the brake system includes service brake cylinder and spring brake cylinder for braking the utility vehicle. An electronic control unit and associated sensors detect the state of motion of the vehicle. The control unit takes over both the influence of the anti-lock braking system and the regulation of the electrically controlled parking brake. In motor vehicles, where not every axle is individually driven, the vehicle speed is determined on the non-driven wheels. However, a corresponding reference value for determining the slip on the driven wheel is omitted in four-wheel vehicles or in vehicles that are moved in a switchable four-wheel drive mode, as in a vehicle in which all the wheels are driven, not freely rotating and proportional to the actual Speed of the vehicle rotating wheel exists. To determine the vehicle speed acceleration sensors are used. Nevertheless, the calculation of the actual vehicle speed as a reference value to the speed of a spinning driven wheel is often limited.

It is therefore an object of the invention to provide a method in which regardless of the number of driven axles the ABS system or the ASR system of the vehicle to determine the slip always the exact vehicle speed is provided.

The object is solved by the features of patent claim 1.

The exact vehicle _speed is referred to below as V _Fzg . The value of the exact vehicle _speed (V _Fzg ), which is calculated using the GPS system, is received by the control system _{according to} the invention and the ABS system and the ASR system to act on provided the braking force or for acting on the engine power of the motor vehicle. A signal from a first satellite takes 4 seconds to bridge the distance to the vehicle. In this case, a vehicle is in an example on a circle with the "distance" 4 seconds in the vicinity of the first satellite. To bridge the distance from a second satellite to the motor vehicle, a second signal takes a supposed 5 seconds. Be the two distance circles (distance circle: satellite 1 or distance circle: satellite 2 ) pushed over each other, so there are two intersections, in which the distance circle (satellite 1 ) with the distance circle (satellite 2 ) cuts. The intersections designate possible positions of the motor vehicle on the distance circles. If one superimposes an image of the earth with the two intersecting distance circles, then the point of intersection, which comes to lie above the image of the earth, designates the position of the motor vehicle on the earth.

For example, at a GPS update rate of 10 Hz, the control system transmits updated vehicle _{speed values} (V _Fzg ) in a time _frame of 100 ms. The above values are merely exemplary and not meant to be exclusive. The advantage of the invention is that in four-wheel vehicles, regardless of the selected non-positive coupling of the axles exact and current wheel slip values are present, so that the braking force or the engine power of the motor vehicle is always adapted to the current slip of the wheels. The method according to the invention reduces the loss of driving energy caused by the slip on the driven wheel and thus improves the locomotion of the vehicle. In addition, the fuel consumption of the vehicle is reduced. Starting on loose ground, such as in a construction site and braking on a road surface, the z. B. is covered with precipitation (rain, snow, ice, etc) is significantly facilitated using the method according to the invention.

According to another embodiment of the invention, speed sensors are provided in the ABS system, which forward the slip of at least one drive wheel to an ABS control system. In this way it can be determined in a timely manner, which rotates the braked wheels, and to what extent the maximum deceleration at the wheel is exceeded.

In an alternative embodiment, it is conceivable that speed sensors are provided in the ASR system, which forward the slip of at least one drive wheel to an ASR control system. If a driven wheel continues to be accelerated, its torque and consequently also the drive torque increase, as a result of which the wheel slip increases overall. As the drive torque increases, the transmittable torque on the driven wheel continues to drop and the wheel tends to spin. The slip can occur on any driven wheel, regardless of whether one, two or more axles of the motor vehicle are driven. In the case of ASR and ABS, rotational speed sensors in each case transmit the slip of at least one drive wheel to a control unit. It is also conceivable that both driven wheels spin an axle.

An additional embodiment provides that in the motor vehicle, a control system is provided, which accomplishes both the control of the ABS system and the control of the ASR system.

The invention will now be described by way of example with reference to the accompanying drawings by way of particularly preferred embodiments.

Hereby show:

1 a comparison of speed and time of a four-wheel drive vehicle on loose ground,

2 a comparison of speed and time of a four-wheel drive vehicle on loose ground with GPS,

3 a comparison of the speed and time of a four-wheel drive vehicle when braking on snow,

4 a comparison of speed and time of a four-wheel drive vehicle when braking on snow with GPS and

5 a schematic representation of a control system network.

In the 1 to 4 In each case, a coordinate system is shown in which the vehicle _speed (V _Fzg ) in kilometers per hour (km / h) is plotted on the ordinate. The abscissa shows the time sequence in seconds (time [s]).

The speed values in [km / h] and time periods in [time (s)] mentioned below in the figures are by no means meant to be exclusive but merely exemplary. Of course, other values can be assumed. Furthermore, there is a simplifying assumption that in the prior art the vehicle speed is determined on the basis of the rotational speed measurement on the drive shaft. In 1 and 2 the motor vehicle is off accelerates the state, which is why the curves 1 to 9 at zero point take their exit. In accordance with the accelerator pedal position in curve 5 , accelerates the motor vehicle within one second from standstill gradually up to a certain speed, in the present example, 5 km / h. Over the next 3 seconds, the accelerator pedal position (curve 5 ) about constant. Due to the loose background is actually driven by the motor vehicle and determined, for example, with a Preiseler measuring wheel actual speed (V _Fzg-real ; curve 7 ) about 3 km / h. At each of the in 1 shown four driven wheels (curves 1 to 4 ) is a speed sensor, which determines a calculated speed individually for each wheel. During the period of 0 to 0.75 seconds, the four wheels, measured at each wheel speed sensor, accelerate (curves 1 to 4 ) and turn faster due to the loose ground than the actually driven speed of the vehicle (V _Fzg-real ; 7 ) corresponds. The calculated vehicle _speed (V _{Fzg-calculated} ; 8th ) is based respectively on the value of the speed sensor of the slowest rotating wheel, which is also the wheel with the lowest slip. In the time window of 0 to 0.75 seconds and 1.5 to 2 seconds and in the time window 3 to 3 . 2 Seconds turn the driven wheels (curve 1 to 4 ) on loose ground so much faster than the actually driven speed of the motor vehicle (V _Fzg-real ; curve 7 ) corresponds. The wheels are therefore each individually braked by throttling the individual drive power or by controlling a braking force on each wheel. This situation is reflected in the valleys of the curves (curve 1 to 4 ) again. In the areas of maximum speeds of the four wheels (curve 1 to 4 ) are therefore also the tips of the curve 6 , which shows the individual wheel brake pressure as an example for the rear right driven wheel.

In 1 a situation is shown in which a four-wheel drive motor vehicle starts on loose ground from a standstill and accelerates. Due to the in 1 calculated vehicle _speed (V _{Fzg-calculated} ; 8th ) results in a curve 9 showing the respective fuel injection quantity for the engine, wherein high speeds at the individual wheels (curve 1 to 4 ) associated with a high drive torque surplus and as a result reduce the desired vehicle forward movement or completely prevent.

2 also refers to a four-wheel drive motor vehicle that accelerates on loose ground from the state out. The difference to 1 is that the actual vehicle _speed (V _Fzg-real , curve 7 ) is determined exactly with the aid of the GPS and the speed of the motor vehicle to be calculated (V _{Fzg-calculated} ; 8th ) this is equated. The accelerator (curve 5 ) is pressed to accelerate the motor vehicle gradually and then remains approximately in a constant position. Due to the exact measurement of vehicle _speed (V _Fzg-real curve 7 and V _{Fzg-calculated} 8th ) is a more accurate and faster response to the respective slip of the individual wheels. The wheel (curve 1 to 4 ), which already has slippage and whose traction is reduced or which is completely spinning, can be lowered in its speed by reducing the driving force on the wheel or by individually braking it (see curve 6 ). The control system, which controls the ABS system and the ASR system of the motor vehicle and determines the braking force or the drive power at the individual wheels, receives the exact vehicle _speed (V _Fzg-real ; 7 ) from the GPS. The lower course of the peaks of the curves 1 to 4 in 2 in relation to the ordinate shows that due to the exact calculation of the vehicle speed the ABS and / or the ASR system the speed (curve 1 ; 2 ; 3 ; 4 ) of a driven wheel whose traction is reduced or already spinning, can be lowered as needed. For an overall analysis of the time windows of the two 1 and 2 It should be noted that the actually driven speed of the vehicle (V _Fzg-real ; 7 ) in 1 during the comparison period initially settles to a low value, then due to the slip again against 0 (zero) drop. The determination of the actual vehicle _speed (V _Fzg-real ; 7 ) by GPS, as in 2 shown, out of state at constant accelerator pedal position (curve 5 ) over time to a continuous increase in the actual vehicle _speed (V _Fzg-real ; 7 ). Depending on the speed reached, the fuel consumed in each case develops (curve 9 ).

3 and 4 each show a situation in which a four-wheel drive vehicle is braked on snow. In 3 is the actually driven vehicle _speed (V _Fzg-real , curve 14 ) determined with a Peiseler measuring wheel. In contrast, the calculated vehicle _speed (V _{Fzg-calculated} ; 15 ) in 3 calculated from the speed information of the speed sensors. With the ABS, the fastest turning wheel, with the ASR system, the slowest turning wheel. Based on the calculation of the vehicle _speed (V _{Fzg-calculated} ; 15 ) with the help of additional sensors such. B. longitudinal acceleration, yaw rate and steering angle sensors gives way to the actual vehicle speed (curve 14 ) from the calculated vehicle speed (curve 15 ) clearly. This leads to the fact that the ABS due to the supposedly lower vehicle _speed (V _{Fzg-calculated} ; Curve 15 ) reduces the pressure on the brakes of the driven wheels too late and too low (see curves 12 and 13 ). The slip on the wheels increases up to the blocking of one or more wheels. Furthermore, there is a risk that the vehicle will skid and get out of control. In the in 4 shown situation, the actual vehicle speed (curve 14 ; V _Fzg-real ) determined exactly by GPS. Based on the position of the brake pedal (curve 17 ) is the motor vehicle in the 3 and 4 each decelerated to the same extent. Each with a curve 16 shown accelerator pedal is not operated in both cases. Due to the deviation of the actual vehicle speed (curve 14 ) from the calculated vehicle speed (curve 15 ) the motor vehicle is in 3 opposite the 4 slowed significantly less from the time of 0.75 s (curves 12 and 13 ). This is due to the lower steepness of the curve 14 in the representation of an ABS braking ( 3 ) compared to the curve 14 in the representation of an ABS braking with GPS support ( 4 ) can be seen. In comparison of both curves, the braking distance of the vehicle increases considerably in the first case and there is an increased risk of collision in the relevant traffic situation.

In 4 the values of the actual vehicle _speed (V _Fzg-real , curve 14 ) because of its exact determination by the GPS system with the calculated vehicle _speed (V _{Fzg-calculated} ; 15 ) match. The presence of exact actual speed values on the ASR system allows in 4 a more timely and accurate metered control of the braking energy at the front and rear wheels (curves 12 and 13 ) as in 3 whenever a slip begins to stop on a braked wheel. The negative acceleration of the driven front and rear wheels runs according to the curves 10 and 11 of the 4 flatter and with less slippage than in 3 , In 4 is compared in the time window between 1.5 seconds and 3.5 seconds 3 supplied to the wheels to a lesser extent and even braking energy (see curves 12 and 13 ).

5 shows a schematic representation of a system network for a control system 18 in which a unified regulator 19 controls both the ASR system and the ABS system. According to the invention processes the control system 18 a GPS signal 20 , the actual vehicle _speed (V _Fzg-real ; curve 14 ). The on the GPS signal 20 based actual speed values can from the control system according to the invention 18 be combined with other data, the control system 18 be transmitted by other sensors. Such sensors measure, for example, the wheel speed 21 , the position of the accelerator or brake pedal 22 or the steering angle sensor 23 , For further control of the ASR and / or the ABS system 30 it is conceivable the GPS signal 20 to combine with appropriate data to the control system 18 from a yaw rate sensor 24 , an acceleration sensor 25 , a brake cylinder or a control pressure sensor 26 be transmitted. The control system according to the invention 18 the above-mentioned data can be calculated using the actual vehicle _speed (V _Fzg-real ; curve 14 ) and other vehicle systems, such as engine control 27 , the transmission control 28 , the suspension and / or the driving dynamics 29 respectively.

LIST OF REFERENCE NUMBERS

Curve 1

Acceleration wheel front left,

Curve 2

Acceleration wheel front right,

Curve 3

Acceleration wheel rear left,

Curve 4

Acceleration wheel rear right,

Curve 5

Accelerator position,

Curve 6

Deceleration pressure for rear right wheel,

Curve 7

determined vehicle speed real,

Curve 8

Vehicle speed calculated,

Curve 9

Injection quantity for engine,

Curve 10

negative acceleration front wheels,

Curve 11

negative acceleration rear wheels,

Curve 12

Braking energy in front,

Curve 13

Braking energy behind,

Curve 14

determined vehicle speed real,

Curve 15

Vehicle speed calculated,

Curve 16

Accelerator position,

Curve 17

Brake pedal position,

18

Control system

19

regulators,

20

GPS signal

21

Wheel speed sensor,

22

Sensor for position of the gas or the brake pedal,

23

Sensor for steering angle sensor,

24

Yaw rate sensor,

25

Accelerometer,

26

Brake cylinder or a control pressure sensor,

27

Motor control,

28

Transmission control,

29

Chassis and / or driving dynamics and

30

ASR and / or ABS system

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007037346 A1 [0006]

Claims (4)

Method for controlling both the ABS system for acting on the braking force and the ASR system for influencing the engine power of a motor vehicle in each case depending on the speed of the vehicle, characterized in that the vehicle speed is determined by a GPS system and its values fed into the control system. A method according to claim 1, characterized in that the ABS system speed sensors are provided which forward the slip of at least one drive wheel to an ABS control system. A method according to claim 1, characterized in that speed sensors are provided in the ASR system, which forward the slip of at least one drive wheel to an ASR control system. A method according to claim 1, characterized in that the ABS system and the ASR system speed sensors are provided which forward the slip of at least one drive wheel to a common control system.

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