DE102015224531A1 - Brake system and method for controlling a brake booster with an electromechanical engine for a brake system of a vehicle - Google Patents

Abstract

The invention provides a brake system (100; 200) and a method for controlling a brake booster (110) with an electromechanical motor (112) for a brake system (100; 200) of a vehicle. The method comprises the steps of: providing (S01) a maximum permissible admission pressure value for a pre-pressure in a brake system (100; 200); Determining (S03) a current driver force value for a driver force currently being exerted by a driver on a driver-operated part (114) of the brake system (100; 200); Calculating (S04) a current maximum value for a driving force of an electromechanical motor (112) of the brake booster (110) based on the determined current driver force value; and limiting (S05) the driving force of the motor (112) to the calculated current maximum value.

Description

The present invention relates to a method for controlling a brake booster with an electromechanical motor for a brake system of a vehicle and a brake system with a brake booster with an electromechanical motor, in particular for a vehicle.

State of the art

Brake systems for vehicles usually have brake booster. Brake boosters are used to supplement a force exerted by a driver of the vehicle on a driver-operated part of the brake system with a force exerted by the brake booster force. As a result, the force to be exerted by the driver can be reduced while maintaining the desired braking effect. The force exerted by the driver is e.g. Actuating force, input power or driver force called. The force exerted by the brake booster is indicated e.g. Supporting force or driving force called. The actuating force is usually brought together by a power transmission unit of the brake booster with the driving force to a brake actuation force. The brake operating force is transmitted to an output member. The output member is coupled to a piston of a master cylinder of the brake system.

For example, electromechanical brake booster are known in which the supporting force is exerted by an electric motor as a drive, and which are therefore also called electromotive brake booster.

In the DE 10 2010 043 203 A1 For example, a brake booster and a method for operating a brake booster are described.

Disclosure of the invention

The present invention discloses a method with the features of claim 1 and a brake system with the features of claim 7.

Accordingly, there is provided a method of controlling a brake booster having an electromechanical engine for a brake system of a vehicle, comprising the steps of: providing a maximum allowable pre-pressure value in a brake system; Determining a current driver force value for a driver force currently being exerted by a driver on a driver-operated portion of the brake system; Calculating a current maximum value for a driving force of an electro-mechanical motor of the brake booster based on the determined current driver force value; and limiting the driving force of the motor to the calculated current maximum value.

It should be understood that whenever the term "force" is used in the preceding and following, it is intended to include both a linear force and a torque. The present invention will thus be described with reference to a generalized concept of force for the sake of simplicity. The brake system and method of the present invention may be readily provided for exerting, receiving, and converting both linear forces and torques, or both.

The admission pressure can in particular be a form provided on a master brake cylinder, one provided for a master brake cylinder or one provided by a master brake cylinder for one or more brake circuits of the vehicle. The master brake cylinder may be designed, for example, as a tandem master cylinder ("tandem main cylinder", TMC) or tandem master cylinder.

Furthermore, a braking system, in particular for a vehicle, is provided, comprising: a brake booster with an electromechanical engine; a driver-operated part of the brake system; a supply device which is designed to provide a maximum permissible admission pressure value for a pre-pressure in the brake system; a driver force determination device configured to determine a current driver force value for a driver force currently being exerted by a driver on a driver-operated part of the brake system; a computing device configured to calculate a current maximum value for a drive force of the electromechanical engine of the brake booster based on the determined current driver force value; and a controller configured to control the engine and further configured to limit the drive force of the engine to the calculated current maximum value.

Advantages of the invention

The finding underlying the present invention is that overloading of a brake system, in particular a master cylinder, may occur due to inertia of a brake booster.

For example, in brake booster with electromechanical motor gear hysteresis lead to undesirable effects. If, for example, a constant first moment M1 is set, which leads to a first pressure p1, the Motor at constant torque M1 hold a much higher pressure p2. If an increase in pressure is caused externally, for example by a pump which pumps a fluid into the master cylinder, an overload may occur if the brake booster requires a certain reaction time in order to reduce the moment M1.

The idea underlying the present invention is now to take this knowledge into account and to provide a method and a brake system which prevents or reduces such an overload. At the same time, however, the restrictions imposed on the brake system should be as low as possible in order to allow maximum support of braking by the motor of the brake booster. The solution according to the invention is particularly reliable and advantageously requires no additional components.

Advantageously, it is possible to fully rely on a measured value for a pre-pressure in the braking system, e.g. a form provided by the master cylinder form, be waived. Thus, the braking system can be operated with a particularly short time delay and be formed without a discrete pre-pressure sensor. In addition, the brake system is thus particularly combinable with vehicle electronics from different manufacturers.

Advantageous embodiments and further developments emerge from the dependent claims and from the description with reference to the figures.

According to a preferred development, the determination of the current driver force value comprises the step of determining a current drive force value for a drive force which is currently provided by the motor of the brake booster. The current driver force value can thus be determined based on the determined current drive force value.

According to a further preferred development, the determination of the current driver force value comprises the step of determining a current deformation of a power transmission device whose deformation represents a measure of a relationship between the driver force and the drive force. The current driver force value can thus be determined based on the determined current deformation of the force transmission device and the determined current drive force value. The power transmission device can be, for example, a reaction disk.

According to a further preferred development, the method comprises the step of determining a current admission pressure value for the admission pressure in the brake system. The ascertaining of the current driver force value can thus additionally take place on the basis of the ascertained admission pressure value.

According to a further preferred refinement, the determination of the current driver force value takes place by means of a dedicated sensor system of the brake system for detecting the current driver force value.

According to a further preferred development, the method comprises the steps of determining a current admission pressure value for the admission pressure in the brake system; Providing a time threshold; and determining a minimum period of time within which the pre-pressure may increase from the determined current pre-pressure value to the provided maximum permissible pre-pressure value. At least limiting the driving force of the motor to the calculated current maximum value is advantageously carried out only in the case that the determined minimum period of time is shorter than the time threshold provided. Optionally, further steps, e.g. determining the current driver force value and / or calculating the current maximum value to be performed only in this case. The time threshold may also be referred to as the grace period.

According to a preferred refinement, the brake system according to the invention comprises a form pressure determination device which is designed to determine a current admission pressure value for the admission pressure in the brake system.

According to a further advantageous development, the computing device is designed to additionally calculate the current maximum value for the driving force of the engine based on the ascertained current admission pressure value.

According to a further advantageous development, the provisioning device is designed to provide a time threshold value; wherein the brake system further comprises an activation device, which is designed to determine a minimum period of time, within which the form pressure can increase from the determined current admission pressure value to the provided maximum admissible admission pressure value; and wherein the control device is designed to limit the drive force of the motor to the calculated maximum current value only in the event that the minimum time interval determined by the activation device is shorter than the provided time threshold value.

Brief description of the drawings

The present invention will be described below with reference to the schematic figures of Drawings illustrated embodiments explained in more detail. Show it:

1 a schematic block diagram of a brake system according to an embodiment of the present invention;

2 a schematic block diagram of a brake system according to another embodiment of the present invention; and

3 a schematic flowchart for explaining a method for controlling a brake booster with an electromechanical motor for a brake system according to another embodiment of the present invention.

In all figures, the same or functionally identical elements and devices - unless otherwise stated - provided with the same reference numerals. The numbering of method steps is for the sake of clarity and, in particular, should not, unless otherwise indicated, imply a particular chronological order. In particular, several method steps can be carried out simultaneously.

Description of the embodiments

1 shows a schematic block diagram of a brake system 100 according to an embodiment of the present invention.

The brake system 100 includes, among other things, a driver-operated part 114 and a brake booster 110 , An actuator 113 of the driver-operated part 114 is operable by a driver with an actuating force to the brake system 100 to specify a braking request. The actuator 113 may be, for example, a brake pedal, a brake lever or the like. The actuator 113 is eg with a power transmission device of the brake booster 110 connected.

The brake booster 110 has a motor as drive 112 , in particular an electric motor, on. The motor 112 can act on the power transmission device, directly or via a (not shown) gearbox, so that by the power transmission device, the actuating force with a through the engine 112 provided driving force merge and to a master cylinder 116 of the brake system 100 is transferable.

The brake system 100 also has a provisioning device 120 , which is designed to a maximum allowable form value p_max for a form in the brake system 100 provide, for example, for a form in the master cylinder 116 or between the master cylinder 116 and one or more brake circuits of the brake system 100 , At the provisioning facility 120 it may be, for example, a memory device in which some or all of the parameters to be provided, such as the maximum permissible form pressure value p_max, are stored. Alternatively or additionally, the provision device 120 have an interface or be designed as an interface, by means of which the parameters to be provided can be received by an external parameter source, for example by a CAN bus or a computing device of the vehicle.

The brake system 100 is also equipped with a driver force detection device 122 configured to determine a current driver force value F_fahrer for a driver force, which a driver of the vehicle currently on the driver-operated part 114 of the brake system 100 exercises. Furthermore, the brake system 100 a computing device 124 which is adapted to a current maximum value F_antrieb_max for a driving force of the electromechanical motor 112 of the brake booster 110 based on the determined current driver force value F_fahrer to calculate. In addition, the brake system points 100 a control device 126 on which to control the engine 112 is designed and which is further designed to the driving force of the engine 112 - towards the top - to limit to the calculated current maximum value F_antrieb_max.

2 shows a schematic block diagram of a brake system 200 according to another embodiment of the present invention. The brake system 200 is a variant of the braking system 100 and has additional features compared to this.

The brake system 200 comprises a form detection device 228 , which is adapted to a current form value p0 for the form in the brake system 100 to investigate. For this purpose, the form determination device 228 eg a position of an input rod and / or the motor 112 determine. The admission pressure value p0 can then be determined by means of a pressure-volume characteristic of the braking system 200 which eg by a provisioning device 220 of the brake system 200 can be calculated from the determined positions.

The determined current form pressure value p0 can be sent to an activation device 230 of the brake system 200 which is adapted to determine a minimum period of time within which the form pressure can increase from the ascertained current admission pressure value p0 to a provided maximum permissible admission pressure value p_max.

The provisioning device 220 of the brake system 200 is like the provisioning device 120 of the brake system 100 and is additionally designed to provide a time threshold, a so-called grace period.

A control device 226 of the brake system 200 is like the controller 126 of the brake system 100 trained and is additionally designed to the driving force of the engine 112 only in the case of limiting to the calculated current maximum value F_antrieb_max, that by the activation device 230 determined minimum period of time is shorter than the provided time threshold value. Thus, it can be considered that the brake booster can respond to a possible externally caused overloading of the brake system only after the grace period. Hereinafter, as an example, the external overload will be considered as the volume flow q of a fluid in the master cylinder 116 stated.

A total stiffness c of the master cylinder 116 can be defined as dF_output / ds_output. dF_ausgang is one by the driver and the brake booster 110 together on the master cylinder 116 acting output power. For this purpose, for example by means of a power transmission device 218 of the brake system 200 the driver force F_fahrer with the drive force F_antrieb the engine 112 be merged to the initial force. Due to the effect of the output force F_ausgang on the master cylinder 116 results in the master cylinder, a shift ds_ausgang a piston of the master cylinder 116 ,

A feared maximum volume flow q leads within a time span dt to a shift ds_ausgang a piston of the master cylinder 116 of ds_output = q / A · dt, where A is a corresponding area of the piston. With the relation dp = dF_ausgang / A and the definition of the total stiffness follows dt = A ^ 2dp / (qc). Using the maximum pre-pressure value p_max and the determined current pre-pressure value p0, the minimum time span dt in which the pre-pressure can rise from the current pre-pressure value p0 to the maximum pre-pressure value p_max can thus be determined as: dt = A ^ 2 (p_max-p0) / (qc).

Is this through the activation device 230 determined minimum time span dt less than the provided time threshold, ie as the grace period, so limits the controller 226 the support force F_antrieb the engine 112 to the calculated current maximum value F_antrieb_max. If the determined minimum time span dt is greater than the grace period, the control device limits 226 the support force F_antrieb the engine 112 Not. Thus, there is a particularly small limitation of the operation of the brake booster 110 by the solution according to the invention instead. Optionally, other units, such as the computing device 124 of the brake system 200 , are only activated in each case if the respectively currently determined minimum time interval dt is greater than the grace period.

A driver force detection device 222 of the brake system 200 is configured to determine a current driver force value F_driver for a driver force that a driver of the vehicle currently has on the driver-operated part 114 of the brake system 200 exercises. For this purpose, the driver force determination device 222 For example, have a sensor which directly the driving force of the engine 112 detected.

Alternatively or additionally, for example, for plausibility, the driver force determination device 222 a driving force value detecting means 221 which is adapted to a driving force value F_antrieb a driving force, which by the motor 112 of the brake booster 110 exercised. The driving force value F_drive may be the driving force value detecting means 221 for example by the control device 226 to be provided. From the driving force value F_antrieb and the current form pressure value p0 can by the driver force determination device 222 be closed to the driver force value F_fahrer.

The driver force detection device 222 may also be a deformation detection device 223 which is adapted to a current deformation of the power transmission device 218 to detect whose deformation is a measure of a relationship between the driver force and the driving force. After ascertaining the drive force value F_drive and the current deformation, the driver force value F_driver can thus be calculated by the driver force determination device.

3 shows a schematic flowchart for explaining a method for controlling a brake booster 110 with an electromechanical motor 112 for a brake system 100 ; 200 according to another embodiment of the present invention. The method according to 3 is in particular by means of the brake system according to the invention feasible and is adaptable according to all variants and developments described in relation to the brake system according to the invention and vice versa.

In a step S01, a maximum permissible admission pressure value p_max for a pre-pressure in a brake system is determined 100 ; 200 provided, for example, by the previously described delivery device 120 ; 220 ,

In an optional step S02, a current admission pressure value p0 for the admission pressure in the brake system 200 ; 200 be determined, for example, by the form detection device 228 Like previously described.

In a step S03, a current driver force value F_ driver is determined for a driver force which a driver currently has on a driver-operated part 114 of the brake system 100 ; 200 exercised, such as by the driver force value determination device 122 ; 222 , In a step S04, a current maximum value F_antrieb_max for a driving force of an electromechanical motor 112 of the brake booster 110 calculated based on the determined current driver force value F_fahrer, such as by the computing device 124 , In a step S05, the driving force of the engine becomes 112 - towards the top - limited to the calculated current maximum value F_antrieb_max, such as by the control device 126 ,

The determining S03 of the current driver force value F_driver may include determining S31 a current drive force value F_drive for a driving force generated by the engine 112 of the brake booster 110 currently provided or exercised include, as above with respect to the driving force value detecting means 221 described. The current driver force value can thus also be determined based on the determined current drive force value.

The determining S03 may include determining S32 of a current deformation of a power transmission device 218 whose deformation is a measure of a relationship between the driver's power and the driving force include. The current driver force value can thus be based on the determined current deformation power transmission device 218 and the determined current drive force value F_antrieb be determined.

In addition, when the determination S02 of the current form pressure value p0 is performed as described above, the following optional steps S06 and S07 may be performed:
In a step S06, a time threshold may be provided, for example by the providing means 220 , In a step S07, a minimum time interval dt within which the form pressure can rise from the ascertained current admission pressure value p0 to the provided maximum permissible admission pressure value p_max can be determined, for example by means of the activation device 230 , Like previously described. Limiting S05 of motive power of the engine 112 to the calculated maximum current value F_antrieb_max is preferably performed only in the case that the determined minimum time dt is shorter than the provided time threshold value. Advantageously, further method steps can be carried out only in this case.

Although the present invention has been described above with reference to preferred embodiments, it is not limited thereto, but modifiable in a variety of ways. In particular, the invention can be varied or modified in many ways without deviating from the gist of the invention.

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 102010043203 A1 [0004]

Claims (10)

Method for controlling a brake booster ( 110 ) with an electromechanical motor ( 112 ) for a brake system ( 100 ; 200 ) of a vehicle, comprising the steps of: providing (S01) a maximum permissible admission pressure value for a pre-pressure in a brake system ( 100 ; 200 ); Determining (S03) a current driver force value for a driver force which a driver currently has on a driver-operated part ( 114 ) of the braking system ( 100 ; 200 ) exercises; Calculating (S04) a current maximum value for a driving force of an electromechanical motor ( 112 ) of the brake booster ( 110 ) based on the determined current driver force value; and limiting (S05) the driving force of the engine (S05) 112 ) to the calculated current maximum value. The method of claim 1, wherein determining (S03) the current driver force value comprises the step of: determining (S31) a current driving force value for a driving force generated by the engine ( 112 ) of the brake booster ( 110 ) is currently provided; wherein the current driver force value is additionally determined based on the determined current drive force value. The method of claim 2, wherein determining (S03) the current driver force value comprises the step of: determining (S32) a current deformation of a power transmission device ( 218 ) whose deformation is a measure of a relationship between the driver force and the driving force; wherein the current driver force value is determined based on the determined current deformation and the determined current drive force value. Method according to one of Claims 1 to 3, with the step: determining (S02) a current admission pressure value for the admission pressure in the brake system ( 100 ; 200 ); wherein determining (S03) the current driver force value is additionally based on the determined pre-pressure value. Method according to one of claims 1 to 4, wherein the determination (S03) of the current driver force value by means of a dedicated sensor ( 122 ) for detecting the current driver force value. Method according to one of Claims 1 to 5, with the following steps: determining (S02) a current admission pressure value for the admission pressure in the brake system ( 100 ); Providing (S06) a time threshold; and determining (S07) a minimum amount of time within which the pre-pressure may increase from the determined current pre-pressure value to the provided maximum permissible pre-pressure value; wherein at least limiting (S05) the driving force of the engine (S05) 112 ) is performed on the calculated current maximum value only in the case that the determined minimum period of time is shorter than the provided time threshold value. Brake system ( 100 ; 200 ) with: a brake booster ( 110 ) with an electromechanical motor ( 112 ); a driver-operated part ( 114 ) of the braking system ( 100 ; 200 ); a provisioning device ( 120 ; 220 ), which is adapted to a maximum allowable form value for a form in the brake system ( 100 ; 200 ) to provide; a driver force detection device ( 122 ; 222 ) which is adapted to determine a current driver force value for a driver force that a driver currently has on a driver-operated part ( 114 ) of the braking system ( 100 ; 200 ) exercises; a computing device ( 124 ), which is adapted to a current maximum value for a driving force of the electromechanical motor ( 112 ) of the brake booster ( 110 ) based on the determined current driver force value; and a control device ( 126 ; 226 ), which are used to control the engine ( 112 ) and which is further adapted to the driving force of the engine ( 112 ) to the calculated maximum current value. Brake system ( 200 ) according to claim 7, with a form detection device ( 228 ), which is adapted to a current form value for the form in the brake system ( 200 ) to investigate. Brake system ( 200 ) according to claim 8, wherein the computing device ( 226 ) is adapted to the current maximum value for the driving force of the engine ( 112 ) additionally on the determined current form pressure value. Brake system ( 200 ) according to claim 8 or 9, wherein the provision device ( 220 ) is additionally designed to provide a time threshold; the braking system ( 200 ) an activation device ( 230 ) configured to determine a minimum amount of time within which the pre-pressure may increase from the determined current pre-pressure value to the provided maximum allowable pre-pressure value; and wherein the control device ( 226 ) is designed to increase the driving force of the engine ( 112 ) only in the case of the calculated maximum current value limit that by the activation device ( 230 ) is shorter than the provided time threshold.

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