Determination of a Possible Deceleration Variable

Abstract

A method and device for determining a possible deceleration variable of a brake system of a vehicle, wherein the brake system has at least one brake, includes providing a possible control variable value that corresponds to an actual control variable value that can be set by the brake system, wherein the at least one brake is designed to generate a deceleration variable in response to a control variable of said actual control variable value; providing a brake system model that is designed to determine a deceleration variable of the at least one brake from an input control variable value; inputting the possible control variable value into the brake system model; and determining a possible deceleration variable of the at least one brake that corresponds to the possible control variable value by way of the brake system model.

Claims

1. A method for determining a possible deceleration variable of a vehicle brake system having at least one brake, the method comprising the steps of: providing a possible control variable value that corresponds to an actual control variable value that is settable by the brake system, wherein the at least one brake is designed to generate a deceleration variable in response to a control variable of said actual control variable value; providing a brake system model that determines a deceleration variable of the at least one brake from an input control variable value; inputting the possible control variable value into the brake system model; determining a possible deceleration variable of the at least one brake that corresponds to the possible control variable value by way of the brake system model.

2. The method according to claim 1, wherein the possible control variable value includes a maximum possible control variable value.

3. The method according to claim 1, wherein the possible control variable value includes a value of a contact force, an application force, an actuator force, an actuator pressure, an actuator current, and/or an actuator voltage.

4. The method according to claim 1, wherein the at least one brake of the brake system comprises a friction brake.

5. The method according to claim 1, wherein the brake system model includes as a further input variable, a temperature of the at least one brake, a travel, and/or an actuating angle.

6. The method according to claim 1, further comprising at least one of the following steps: (i) comparing the determined possible deceleration variable with a limit value; or (ii) determining a possible vehicle deceleration from the determined possible deceleration variable, wherein the limit value and/or the possible vehicle deceleration is determined depending on a vehicle weight, a force transfer ability between tire and road, a route gradient, an operating state of a drive train of the vehicle, and/or an availability of other brake systems.

7. The method according to claim 1, wherein the possible deceleration variable is assigned to one brake, a plurality of brakes, or all brakes of the vehicle.

8. The method according to claim 1, wherein the vehicle comprises at least one further brake system having at least one further brake, the possible deceleration variable of which is not determined by the brake system model, wherein the possible deceleration variable of the at least one further brake is determined from an achieved brake effect in case of braking actually being effected.

9. The method according to claim 8, wherein the at least one further brake is provided in a further vehicle part that is connected to a first vehicle part in an articulated manner, wherein a force is measured between the first and the further vehicle part.

10. The method according to claim 1, wherein the brake system model is updated based on a history of brake interventions.

11. The method according to claim 1, wherein the brake system model comprises a characteristic map and/or a physical model of the at least one brake.

12. A device for determining a possible deceleration variable of a vehicle brake system having at least one brake, comprising: an interface for receiving input variables; an interface for outputting the possible deceleration variable of the at least one brake; and a data processing unit configured to: provide a possible control variable value that corresponds to an actual control variable value that is settable by the brake system, wherein the at least one brake is designed to generate a deceleration variable in response to a control variable of said actual control variable value; provide a brake system model that determines a deceleration variable of the at least one brake from an input control variable value; input the possible control variable value into the brake system model; and determine a possible deceleration variable of the at least one brake that corresponds to the possible control variable value by way of the brake system model.

13. A vehicle comprising the device of claim 12.

14. The vehicle according to claim 13, wherein the vehicle is a commercial vehicle, a lorry, a trailer, a bus and/or as a combination of a towing vehicle and a trailer, and/or the vehicle is a vehicle driven purely by electric motor, by hybrid drive, or by conventional drive.

15. A computer product comprising a nontransitory computer readable medium having stored thereon program code configured so that, when executed on a data processing unit, the program code causes said data processing unit to: provide a possible control variable value that corresponds to an actual control variable value that is settable by the brake system, wherein the at least one brake is designed to generate a deceleration variable in response to a control variable of said actual control variable value; provide a brake system model that determines a deceleration variable of the at least one brake from an input control variable value; input the possible control variable value into the brake system model; determine a possible deceleration variable of the at least one brake that corresponds to the possible control variable value by way of the brake system model.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0063] FIG. 1 is a basic design of a brake and the actuation thereof;

[0064] FIG. 2 shows influencing parameters on the brake process; and

[0065] FIG. 3 is a schematic plan view of a vehicle.

DETAILED DESCRIPTION OF THE DRAWINGS

[0066] FIG. 1 shows a basic design of a brake and the actuation thereof.

[0067] The exact illustration of all of the components has been omitted here. The drawing in FIG. 1 shows only a function principle.

[0068] The brake 1 is designed here as a friction brake that comprises brake pads 2 and a brake disc 3 that is able to rotate about an axis A. The brake pads are provided in a brake caliper 4 that straddles the brake disc 3. The brake pads 2 and the brake disc 3 function as frictional elements that can be brought into contact with one another in a frictional manner in order to generate a deceleration variable.

[0069] An actuator 5 is provided to actuate the brake 1. The actuator comprises an actuating element 6 that can be shifted to the left in a translational manner in the drawing.

[0070] A transmission mechanism 7, which comprises an actuating lever 8 that is designed so as to be able to pivot in the plane of the drawing, is provided between the actuator 5 and the brake 1. The transmission mechanism 7 is connected on one side to the actuator 5 so that a displacement of the actuating element 6 is introduced into the transmission mechanism 7, as a result of which the actuating lever 8 is pivoted in the anti-clockwise direction. The transmission mechanism 7 is in contact on the other side with the brake 1 in order to introduce a displacement or force resulting from the displacement of the actuating element 6 into the brake 1 in order to make contact with the brake pads 2 by way of the brake disc 3 in order to generate the deceleration variable of the brake 1.

[0071] In the case of a disc brake, the deceleration variable may be a brake torque that results from an application force, that is to say a force with which the brake pads 2 are pressed against the brake disc 3, and an average friction radius.

[0072] The transmission mechanism 7 provides a transmission ratio that describes the transmission of an actuator force or the resulting displacement of the actuating element 6 to the application force.

[0073] In order to determine a deceleration variable that can be generated using the brake 1 in response to a control variable, a brake system model that takes these conditions into account can therefore be provided. In particular embodiments, a proportionality factor is provided here, which maps a conversion of the control variable to the deceleration variable. If an efficiency, for example of the entire arrangement shown or parts thereof, is known, a possible brake force can be calculated by a possible control variable being input into the brake system model:

M.sub.B=c*×i×F.sub.z×η×R.sub.m

M.sub.B: deceleration variable
c*: proportionality factor
i: transmission ratio
F.sub.z: actuator force
η: efficiency
R.sub.m: average friction radius

[0074] The actuator 5 is generally held here. In some embodiments, the actuator 5 is designed as a fluidically actuated, in particular pneumatically or hydraulically actuated, actuator. According to other embodiments, the actuator 5 is electrically actuated, that is to say a brake 1 that is actuated in such a way can be attributed to an electromechanical brake system. In the case of fluidic actuation, the actuator 5 may comprise a cylinder with pistons in order to displace the actuating element 6 by means of pressure. In the case of electrical actuation, the actuator 5 may comprise a linear motor or a rotatory electric motor, with the rotary movement thereof then preferably being converted to a translational movement by means of a corresponding mechanism in order to displace the actuating element 6.

[0075] According to other embodiments, the transmission mechanism 7 may be omitted. It is therefore also possible for the actuator 5 or the actuating element 6 thereof to act directly on the brake 1, that is to say without transmission, and there to cause the friction elements 2, 3 to be pressed against one another.

[0076] The brake 1 can finally also be based on another technical or physical principle. For example, a drum brake or a friction brake that comes into contact with a friction element that is stationary in relation to the vehicle, such as for example in the case of a magnetic rail brake, is conceivable.

[0077] FIG. 2 shows a basic illustration of influencing parameters on the braking process of a vehicle.

[0078] Shown is a vehicle 10 that is travelling on an incline that has the gradient angle 12. The gradient angle can be determined for example by slope measurement or digital map material. In addition to an inclination angle 12, other suitable variables can also be used, such as a pitch, for example.

[0079] The vehicle 10 comprises a drive train 11 and brakes 1. The brakes 1 can be designed correspondingly to the brakes in FIG. 1. The drive train 11, which is depicted here only schematically, may be a conventional, hybrid or electric drive train. For example, the drive train 11 influences the braking by way of electrical energy stores that are no longer capable of receiving energy, such that it is no longer possible to brake in generator operation.

[0080] A downward gradient force 13 is also shown. This depends on the gradient angle 12 and the weight of the vehicle, which can be defined or determined as described above.

[0081] The vehicle deceleration 14 is oriented counter to the downhill direction of travel. The vehicle deceleration can be determined given knowledge of the possible deceleration variable, that is to say for example a possible brake torque, of the brake 1 or the brakes 1 and vehicle parameters, such as a vehicle weight. If the vehicle deceleration is too low in comparison with a limit value that is stipulated for example by legislation, suitable countermeasures must be taken, such as a warning, maintenance or else termination of the driving operation.

[0082] FIG. 3 shows a schematic plan view of a vehicle.

[0083] The vehicle 10 comprises a towing vehicle 20 and a trailer 21, which are connected to one another at a coupling point 22 such that the trailer 21 can be towed by the towing vehicle 20 in the direction of travel 19. The towing vehicle 20 and the trailer 21 each have at least one brake (not illustrated). The towing vehicle 20 forms a first vehicle part that is connected in an articulated manner to a further vehicle part, the trailer 21. The vehicle parts shown here are connected to one another in a releasable manner. However, it is also contemplated that this connection is not of releasable design, that is to say that both vehicle parts function not as a towing vehicle 20 and trailer 21 but, for example, form an articulated vehicle, such as an articulated bus.

[0084] The coupling point 22 is designed to ascertain a coupling force 23 between the vehicle parts, for example by means of a coupling force detection device, in particular by means of a coupling force sensor. In particular, it is possible to make a statement here about the braking effect of the vehicle parts.

[0085] If it is determined that the coupling force 23 during a braking process indicates sliding of the rear vehicle part, in this case the trailer 21, it is thus possible to infer a greater braking or a greater braking effect of the front vehicle part when comparing both vehicle parts. In contrast, if it is determined that there is pulling at the coupling point 22, this indicates a greater braking or a greater braking effect of the rear vehicle part.

[0086] If, for example, the deceleration variable of the at least one brake is able to be determined only in one vehicle part, that is to say only in the towing vehicle 20 or in the trailer 21, the deceleration variable of the at least one brake of the vehicle part that cannot be detected by the brake system model can be inferred based on the coupling force 23 by determining the actual braking effect during braking as described above and inferring the deceleration variable of the at least one brake of said vehicle part from the coupling force 23 when the control variable is known or when the control variable value is known.

[0087] The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.

LIST OF REFERENCE SIGNS

[0088] 1 Brake [0089] 2 Brake pads [0090] 3 Brake disc [0091] 4 Brake caliper [0092] 5 Actuator [0093] 6 Actuating element [0094] 7 Transmission mechanism [0095] 8 Actuating lever [0096] 9 Actuating angle [0097] 10 Vehicle [0098] 11 Drive train [0099] 12 Gradient angle [0100] 13 Downward gradient force [0101] 14 Vehicle deceleration [0102] 19 Direction of travel [0103] 20 Towing vehicle [0104] 21 Trailer [0105] 22 Coupling point [0106] 23 Coupling force [0107] A Axis