WO2013000598A1

WO2013000598A1 - Method for operating an electrically actuable brake, electrically actuable brake, and brake system

Info

Publication number: WO2013000598A1
Application number: PCT/EP2012/056898
Authority: WO
Inventors: Kai Schade; Paul Linhoff
Original assignee: Continental Teves Ag & Co. Ohg
Priority date: 2011-06-29
Filing date: 2012-04-16
Publication date: 2013-01-03
Also published as: DE102011078272A1

Abstract

A method for operating an electrically actuable brake (4) having an electric motor (8) and having a power transmission arrangement which transmits the torque of the motor (8) to an actuator which converts a rotary movement into a translatory movement of a brake element, wherein, for a build-up of pressure, the motor (8) rotates in a pressure build-up direction and thereby presses the brake element against a brake body, wherein a clutch (60) is incorporated into the power transmission arrangement, should allow for different demands on electrically actuable brakes and the operation thereof with regard to intense and/or fast pressure build-up and dissipation. For this purpose, for the build-up of pressure, the clutch (60) is substantially fully engaged and the motor (8) is rotated in the pressure build-up direction, and for the dissipation of pressure, the clutch (60) is substantially fully disengaged.

Description

Method for operating an electrically operated

Brake, electrically operated brake and brake system

The invention relates to a method for operating an electrically actuated brake with an electric motor and a power train, which transmits the torque of the motor to an actuator, which converts a rotational movement into a translational movement of a brake element, wherein the pressure buildup of the motor in

Pressure build-up direction rotates and thereby presses the brake element against a brake body. It further relates to an associated electrically actuated brake and an associated brake system.

In brake-by-wire brake systems, the brakes are controlled electronically ("by wire") by means of a control and regulation unit The driver's braking request in such systems is determined by an actuation unit with a brake pedal, for example the pedal travel the way that the brake pedal ^¬ inserted by pressing the driver's back, as measured by an appropriate sensor and the control and regulating unit is used as an input variable to the SET ^¬ development of the corresponding brake pressure or the corresponding tightening force in the brakes. the driver's braking intention is to a certain extent in a target braking torque is converted, which the control and regulating unit as a target size for Adjustment of the corresponding brake pressure is used. In such systems, the driver is characterized by the

Actuation of the brakes decoupled. This allows z. As the implementation of safety routines such as ABS, ESP, TCS, etc., in which the brake pressure is wheel individually and briefly increased and decreased several times without the driver feels these processes on the foot. The so-called "pumping" of the brake pedal can be avoided in this way.

Electromechanically actuated or electromechanical brakes (EMB) are often used in the abovementioned brake systems. The application of such brakes is carried out by the driving of an electric motor whose rota ^¬ toric movement of the motor shaft is converted by an actuator in a translational movement. By this trans ^¬ latory movement then, for example, a brake piston is driven against a brake pad, which then presses against a brake disc. The actuator may be configured, for example, as a ball screw (KGT), wherein upon rotation of the spindle by the rotor (via an intermediate gear) a rotatably mounted on the spindle Spindelmut ^¬ ter is placed in a translational movement, whereby then the brake piston is moved. From DE 10 2004 012 35 AI, for example, an operating unit for a

Electromechanically actuated disc brake known.

From WO 2011/029812 AI a "brake-by-wire" - brake system is known, in which the hydraulic

actuatable wheel brakes of the brake system can be actuated electrically by means of an electrically controllable pressure supply device. For this is the

Pressure delivery device as a hydraulic

Cylinder-piston arrangement formed, the piston of an electric motor with the interposition of a rotary Translation gear is actuated. By means of the pressure provided by the pressure supply device, the wheel brakes are actuated.

With electromechanical brakes, powerful ones can be used compared to conventional hydraulic brake systems

Brake pressures are generated on small time scales. In known systems, the motor and the actuator are directly coupled via a power train. In other words: The mechanical output quantity (pressure force) and the mechanical input quantity (motor position or speed) are direct

coupled.

Especially as a rule (for example by an anti-lock braking system (ABS), electronic stability program (ESP),

Traction Control System (TCS), ...) are both extremely large and fast pressure or force strokes as well as fast

Change of characters (pressure increase / pressure reduction / pressure increase / ...) required. The obvious contradiction between a large pressure stroke or pressure build-up, i. | dF / dt | »0, where F denotes the tension force and t the time and its

repeated rapid change of sign, | d ² F / dt ² | >> 0, becomes particularly well recognizable if one considers the temporal

Considered speed curve of the motor shaft: On the one hand, namely large stroke requires a high engine speed.

On the other hand, a fast sign change, i. a quick change of Druckauf- and pressure reduction a low engine speed or steady re-acceleration.

Based on the following requirements for the construction of a corresponding electrically actuated brake with an electric motor, the resulting design conflict becomes obvious: For high pressure or force strokes, large, heavy, torque-strong actuator motors are necessary. For the realization of a fast dynamics (pressure build-up / pressure reduction), on the other hand, small, lightweight motors with low rotational torque are advantageous.

Such a conflict is avoided in today's brake designs or dealt with by a compromise in the design of the corresponding engine, which does not offer optimal performance in both cases.

The invention is therefore based on the object to improve this Situ ^¬ tion and the different requirements for electrically actuated brakes and their operation in

In view of strong or rapid pressure build-up and -down simultaneously, so that common compromises do not need to be taken.

With respect to the method, the above object is, in particular in fast control operations achieved in a first variant in that for pressure build the Kupp ^¬ lung is substantially completely engaged, and the motor rotates in the direction of pressure buildup, and that to reduce the pressure, the clutch is substantially is completely disengaged. By substantially complete engagement or disengagement is meant that disengages completely or almost completely, which means ranges of about 90 to 100%.

Advantageous embodiments of the invention are the subject of the dependent claims.

It is preferably an electrically actuated brake with an electric motor and a power train, which transmits the torque of the motor to an actuator, which rotates a movement in one

Spindle nut rotatably mounted spindle in one

translatory movement of a spindle nut pelten Bremselementes converted.

Alternatively, it is preferably an electrically actuated brake with an electric motor and a power train, the torque of the engine to a

Actuator transmits, which converts a rotary motion via a hydraulic pump into a translational movement of a brake element.

The invention is based on the consideration that an essential reason for the above design compromises in the design of the electric motor of an electric

operable brake is in the direct or rigid coupling of the motor and actuator. As has now been recognized, this design conflict or compromise can be avoided by resolving this rigid or direct connection and by switching a clutch into the power train which transfers the torque of the electric motor to the actuator, the latter being controlled in this way in that the pressure build-up is almost or completely engaged, so that the full torque of the engine is available, but that it is almost or completely decoupled for pressure reduction.

In this way, a pressure reduction can be achieved without the motor has to change its direction of rotation. That is, in order to enable a short-term pressure reduction, it is sufficient to decouple the actuator from the engine. Once disengaged, the speed and direction of rotation of the motor are arbitrary in some ways, as they are irrelevant due to the non-existing frictional connection. The decoupling can be achieved in ^¬ example by a controllable coupling in the form of a (mechanical) coupling. In this way, the pressure / actual force can decrease (pressure build-up) while the engine speed is maintained, increases or only slightly sinks. Thus, the engine can be large, heavy and powerful designed, without compromises must be made in the rapid pressure reduction.

The above-described method for driving an electrically actuated brake also has opposite

conventional systems advantages in one after one

Pressure reduction needed subsequent pressure rebuilding. In this case, instead of the usual and required reversing or restart of the motor armature in Zuspann- or pressure buildup direction of the frictional connection on the engagement of the clutch can be restored. The engine speed drops only briefly below the nominal level, and then rise again. The engine speed i also needs to be ramped up / rotational torque to nominal speed these cases not only of zero or even opposite direction against resistance (the ruling brake ^¬ pressure or tension) and motor armature.

In particular, in fast control operations, it is advantageous ^¬ way, when the engine (on) to rotate at the pressure reduction in pressure build-up direction. That is, the brake pressure is reduced in ^{Wesentli ¬} Chen by the decoupling of the engine and actuator. Advantageously, when rebuilding pressure, the ^{motor is} rotated in the pressure ^build-up direction and the clutch is engaged. During a sequence of pressure increase and pressure ^¬ degrading thus the direction of rotation of the motor must not be reversed. Such control or regulation of the brake is particularly advantageous in fast control processes such as ABS, ESP TCS, etc.

In a second variant of the process the ge ^¬ above-mentioned object, in particular dissolved in normal operation of the brake by the pressure reduction, the clutch is substantially fully engaged and the motor is rotated in reverse to the pressure buildup direction. In contrast to the first variant of the method so here the direction of rotation of the motor between pressure build-up and pressure reduction is reversed. Both the pressure build-up and the pressure reduction, the clutch is substantially fully engaged. In this case, both the pressure build-up and the pressure reduction, a direct coupling or almost complete coupling zwi ^¬ 's actuator and motor is given.

The above object is further achieved by a method for operating an electrically actuated

Brake, where to build up pressure in the engine

Pressure build-up direction rotates and thereby the brake element is pressed against a brake body, wherein in the power train, a clutch is connected, wherein in ordinary

Braking operations for pressure reduction, the clutch is substantially fully engaged and the motor rotates in the opposite direction to the pressure build-up direction, and wherein during braking operations with automatic brake control for pressure reduction, the clutch is substantially completely disengaged and the engine rotates in the pressure build-up direction.

That is, in ordinary braking situations in which the driver brings the vehicle to a standstill, and that happen to ge ^¬ genüber control operations comparatively large time scales, a direct connection between the motor and the actuator is provided by the substantially clutch fully input to go through the Reversal of the direction of rotation to make the pressure reduction via the engine. In such situations, extremely rapid reversal of the direction of rotation of the engine is not required in a pressure reduction. By reversing the direction of rotation of the motor between pressure build-up and -down can also reduce the pressure on a normal braking the brake piston to the stop be reduced.

In fast control operations, however, the direction of rotation is not reversed and the pressure reduction exclu ^¬ Lich realized by a complete or nearly complete From ^¬ coupling of the clutch. In this way, pressure can be quickly built up again by engaging the clutch. This can also happen several times in a sequence. Only when the control process is completed and the driver no longer expresses a braking request, the direction of rotation of the motor is set opposite to the pressure build-up direction to reduce the pressure in the brake. Advantageously, in an automatic control operation of the brake, the motor is rotated in the pressure build-up direction until the control process is completed.

The above object is further achieved by an electrically operable brake with an electric motor and a power train, which transmits the torque of the motor to an actuator, which converts a rotational movement into a translational movement of a brake element, wherein the pressure buildup of the engine in pressure ^{build ¬} rotates direction and thereby presses the brake element against a brake body, wherein in the power train, a clutch is connected.

The brake may be an electromechanically or hydraulically actuated brake. In the case of a hydraulically actuated brake, the actuator comprises an at least partially hydraulic coupling between

Spindle nut and brake element. In case of a

electromechanically actuated brake, the spindle nut is purely mechanically coupled to the brake element. The electrically actuated brake advantageously has a power train with a transmission, wherein the clutch is arranged in the power train between the engine and transmission. This point in the power path deals with comparatively high speeds and comparatively small torques, which allows a compact design of the clutch.

The clutch is advantageously designed as rheological Kupp ^¬ lung with a magneto or elektrorheologi-'s material. Such a rheological material changes its state of aggregation depending on the strength of an applied magnetic or electric field. If there is no electromagnetic field, at ordinary operating temperatures in the range from -40 to 150 ° C, the rheological material is in liquid aggregate ^¬ state before. By applying an electromagnetic field, the physical state of this material can be changed from liquid to solid in an analogous, ie continuous, manner. Such a clutch has the advantages over other clutches such as friction clutches or multi-plate clutches that it is extremely maintenance-free and reliable. The amendments ^¬ conclusions of the states of matter from liquid to solid liquid again, etc., are for all practical purposes and use during the typical life of an EMF of about 15 years completely reversible. Such a coupling also has no wear ^parts .

The above object is further achieved by a braking system with an electrical described above

operable brake and a control unit with means for carrying out a method mentioned above. The control unit can also be integrated in the brake, whereby an advantageous embodiment of a

electromechanical brake is realized. The advantages of the invention are, in particular, that an adjustable clutch in the power train which decouples the motor from the actuator, an improvement in the speed of braking force build-up and degradation can be achieved in electro-hydraulic or mechatronic brake systems. In the electro-hydraulic brake systems to the eccentric shaft end of the pump motor from the Mo ^¬ door shaft by said coupling can be separated. As ^¬ by such braking systems can be cost-effectively constructed with ^¬ space, weight and power consumption advantages. By decoupling the motor and actuator during

Brake pressure reduction, the clamping force and the brake pressure ra ^¬ pide can be lowered, regardless of the engine speed or direction. This feature can be used to improve the control performance of the corresponding brakes. By applying the method of the invention are the elimination of the need for rapid reversal of rotation of the engine, thereby eliminating usually entste ^¬ Henden current peaks and abrupt board network loads. Due to the elimination of the need ^¬ speed of rapid reversal of the motor in fast control operations, ie by eliminating the dynamic requirements of the engine, this must not be designed for appropriate high dynamics.

An embodiment of the invention will be explained in more detail with reference to a drawing. In it show in a highly schematic view:

FIG. 1 is an electromechanical brake according to the prior

Technology with an electric motor, a gearbox, a ball screw, a brake piston and a brake pad, FIG. FIG. 2 shows a typical application or pressure buildup characteristic, FIG.

FIG. 3 an electrically actuated brake in one

preferred embodiment with an electric motor, a clutch, a transmission, a

Ball screw, a brake piston and a

Brake pad,

FIG. 4 Pressure buildup characteristic for a brake according to

FIG. 1, and

FIG. 5 is a generalized pressure buildup curve for egg ^¬ ne brake according to FIG. Third

Identical parts are provided in all figures with the same Bezugszei ^¬ chen.

In the in FIG. 1 illustrated electromechanical brake 2 according to the prior art, the electric motor 8 via a motor shaft (not shown) with an affiliated ^¬ pinion 10, an engine torque Mi from. Here, φ denotes the rotation angle of the motor shaft and ω _1, the corresponding Win ^¬ kelgeschwindigkeit. After a gear 14 are then the power train, the torque M ₃ and the angular velocity ω ₃ before. By a ball screw (KGT) 20, this rotational movement is translated into a linear force Fi, with a brake piston 26 is pressed against a brake pad 32. The force Fi or F generated in this way is one

Function of the angle of rotation cp, ie F = f (φ), where: F> 0 during pressure build-up and F <0 during pressure reduction. The force F or Fi as a function of the angle of rotation φ is shown in FIG. 2 darge ^¬ represents. On the abscissa 46, the angle of rotation φ and on the ordinate 40, the force F is plotted. Curve 50 verdeut ^¬ light the force curve as a function of the angle of rotation cp. The mechanical torque M _{/ mechanically} by the engine which corresponds to the abge ^¬ given engine torque Mi, is composed of the originally generated by the motor torque M _Mot, less consumed by the speed-dependent Rei ^¬ bung and the acceleration torques, ie

^M Mech = ^M M _O , - ^M R _e , bu " _g - ^M BescMeu _mg u" _g It can be further expressed as M _Mech = k _Mot * I _phase (t) - k _friction * ω ₁ - M ₁ . Here, I _Mot _phase k and k _Re u i _ng _b denote a constant, respectively the current, ω ₁ is the angular velocity, ώ ₁ whose time derivative and the rotational moment J of the armature, the pinion and the gear, that is, the total rotation torque.

Based on the above equation, it is seen that the mechanical torque M _Mech decreases when magnification ßert ^¬ ώ. ₁ In other words, the greater ώ ₁ , ie the time change of ώ ₁ , becomes, the lower the available torque M _MeCh - Since control functions such as ABS, TCS, ESP, etc. naturally rapid power and force reduction in a very short time require, ie | dF / dt | »0, must on

Actuator motor very often and fast the direction of rotation

reversed or reversed and immediately be ^¬ accelerated again, ie | ώ ₁ \ >> 0. This leads to a clotting ^¬ gen output torque M _mech and therefore a low maxi ^¬ paint tone.

The in FIG. 1 system is limited in principle by the direct coupling of motor 8 and ball screw 20 and Bremskol ^¬ ben 26 and the consequent direct reduction of the mechanical braking torque M _MeCh with increasing ώ ₁ . From a certain quotient F / t or a certain time derivation of the force F, F, either certain forces are no longer or only at all approachable very slowly.

The in FIG. 3 is shown in a highly schematic manner

Electrically actuated brake 4 according to the invention comprises, in a preferred disclosed embodiment, an electric motor 8 with pinion 10, a gear 14, a ball screw 20, a brake piston 26 and a brake pad 32. Optionally, a hydraulic operative connection / coupling 22 is arranged between the ball screw 20 and the brake piston 26.

Ball screw 20 and optionally active connection / coupling 22 thus form an actuator, which rotates a movement of the spindle nut rotatably mounted in the spindle of the ball screw in a

translational movement of the with the spindle nut

operatively coupled brake piston 26 converted.

In contrast to the in FIG. 1 illustrated brake 2 is connected between the electric motor 8 and gear 14, a clutch 60. As a result, the brake 4 according to FIG. 3 designed to allow a pressure reduction, without the direction of rotation of the electric motor 8 must be reversed.

In the following, the parameter shall designate the degree of coupling. Here, = 1 indicates a complete clutch engagement or heat- and a = 0 indicates a complete Entkopp ^¬ lung, AEIF {0 ... l}. As a target for a clutch operation, which is suitable for fast control operations, applies

- 1 / (5 ms) &<d&<+ \ / (\ 0ms). The torque which, viewed from the electric motor 8, is now behind the clutch 60 is denoted by M ₂ , the corresponding angular speed by ω ₂ . The associated angle of rotation is designated here by γ. Behind the gear 14 are then a rotary moment M ₃ and an associated angular velocity co ₃ ago. Due to the coupling 60, the direct coupling between the electric motor 8 and ball screw 20 and the translational movement of the brake piston 26 is achieved. A rigid coupling is still present at a = 1, the motor 8 is completely decoupled at a = 0.

In the following, the operation of the brake 2 of FIG. 1 and the brake 4 of FIG. 3 at two different

Operating situations are compared. First of all, the fastest possible pressure reduction from a strong force build-up should take place with the respective brake. In the

Brake 2 of FIG. 1 applies during heavy pressure build-up:

| | »0, ^^» O. In the brake 4 according to FIG. 3 applies:

| | 0, \ ω ₁ \ = I ω ₂ I »0, α = 1. That is, to the strong

Pressure build-up, the clutch 60 is fully engaged here. In both cases, the pressure should be reduced as quickly as possible, d. H. the nominal state \ F | << 0 can be reached as quickly as possible.

Now applies to the brake 2 according to FIG. 1 that the force F is a direct function of the rotation angle φ and a direct function of the angular velocity ω ₁ , ie F = f (φ) = g (ω ₁ ). In the brake 4 according to FIG. 3 is the force F due to the

Presence of the coupling 60 and the fact that in this case is now disengaged for pressure reduction, d. H.

from the value 1, which it had set to a lower value during the fast pressure build-up, is no longer a direct function of cp, but rather a function (/), ie a function of the angle of rotation behind the clutch 60 or a function g (FIG. (0 ₂ ) and thus a function

, ie F = f (y) = g (β » ₂ ) ⁼ cifjO _j ). Since it is now possible to decouple the motor and actuator or KGT 20, the amounts of the functions g (ω ₁ ) in the case of the brake according to FIG. 1 and {, (o _l ) in the brake according to FIG. 3 \ g (c) _l ) \ <\ h (a, (o _l ) \. That is, the magnitude temporal change of the function {, (o _l ) is greater because of the ability to decouple through the coupling 60 amount applies and the time derivative of the force

F is negative when pressure is reduced, ie _J F «0, it now holds true that the time change of the force for the brake according to FIG. 3 from the amount greater and thus faster negative than the brake according to FIG. 1. That is, by the use of Kupp ^¬ ment 60, ie the decoupling, in the brake 4 according to FIG. 3 are reduced after a rapid pressure build-up faster pressure than the brake 2 shown in FIG. 1.

Next, consider the case that after a

Pressure reduction as quickly as possible pressure is to be built up, as happens, for example, during an ABS control ge ^¬ . For the brake 2 according to FIG. 1 applies: F «0, ω _ι « 0, ie, the electric motor 8 rotates opposite to the feed direction or pressure build-up direction to reduce brake pressure. In the brake 4 according to FIG. 3: F «0, ω ₁ » 0, ω ₂ «0, a = 0. That is, the reduction of the pressure is realized here by a complete decoupling a = 0. By this decoupling is achieved that the brake piston 26 releases from the brake pad 32 and the brake piston 26 moves back, ie ω ₂ «0. The rotational speed of the electric motor 8, however, is not reversed during pressure reduction, ie ω ₁ » 0 and the sign opposite to ω ₂ .

The target state for the fastest possible pressure build-up is now »!}. Since, as shown above, \ g {o _l ) \ <\ h {a, o _l ) \ in this case can be built with the brake 4 of the invention faster pressure than the EMB 2 shown in FIG. 1. The reason is that the pressure build-up only needs to be engaged on the electric motor 8, which continues to rotate in the application direction during the pressure reduction phase. In contrast to the brake according to FIG. 1, therefore, a reversal of the direction of motor rotation is not necessary, ie ω ₁ does not have to change its sign.

The processes described above will be illustrated by two diagrams. In FIG. 4 is plotted on the abscissa 46 of the rotation angle φ and on the ordinate 40, the corresponding ^¬ de force exerted by a brake force F. The curve 110 illustrates between the points P _lf P ₂ , P3 and P ₄ = Pi the force curve in a preferred version of the method, in which both the pressure build-up and the

Pressure reduction, the clutch 60 wholly or almost completely eingekup ^¬ pelt and the pressure build-up of the motor 8 rotates in the pressure build-up direction and opposite to the pressure reduction to Druckab ^{¬ construction} direction rotates. From Pi, the rotation angle is increased to P ₂ , that is, the motor rotates in the pressure build-up direction, so that at P _2, a high clamping force is achieved. In order to come to a state with a lower clamping force, ie to come from P ₂ to P ₃ , the engine speed is reversed so that the rotation angle φ is reduced. The hysteresis behavior results from the setting behavior of the covering material.

A similar diagram for operating a brake 4 according to the invention with a coupling 60 is shown in FIG. 5 is shown. On the x-axis 90 is the rotation angle cp, on the y-axis 96 is the degree of coupling and on the z-axis 102, the force F is plotted. Here P ₂ again corresponds to the presence of a high clamping force, for example during the Blocking the wheel. To reduce the pressure or the ^clamping force ^¬ force starting from P ₂ , the characteristic along the y-axis 96 to the point P ₃ ^{* is} now followed. How depicting ^¬ development can be seen at this, the engine speed need not be reduced in pressure reduction in this way. The degradation of the Dru ^¬ ckes so happens here to some extent along the y-axis 96 perpendicular to the x-axis 90 is entirely due to the Ansteue- tion of the clutch 60th

During an ABS control process, the points of the in FIG. 5 correspond to the following states:

Pi: idle state

P ₂ : built-up clamping force, wheel blocked

P ₃ ^* : Tension reduced, wheel moves again

P ₂ : built-up clamping force

When using a coupling 60 based on magnetorheological or electrorheological materials / liquids, the mechatronic drive can be dropped as quickly as possible in the event of a failure of the higher-level control unit, for example because of a defect in the hardware, a loss of the supply voltage, a fault in the software or the like further pressure build-up can be prevented, because when switching off (de-energized state), the electromagnetic excitation of the clutch is eliminated and then opens due to their normally open property.

By the inventive method and the inventive ^¬ SSE electrically actuable brake or the associated

Brake system can be an improvement for any type

engine-actuated application can be achieved, in which both repeated rapid reversal of the actuator motor as well as high speeds and speed gradients occur equally. Fields of application are, for example, purely electromechanically actuated brakes with a corresponding electric motor for clamping force, electro-hydraulic brake systems with a pressure supply device with an electric motor or electro-hydraulically / electromechanically combined braking systems. Here quick position ^¬ change can be achieved in ABS operations. In electrohydraulic brake systems with one by means of a

Electric motor operable piston of a piston-cylinder arrangement, the electric motor for recovering delivery volume can be quickly reduced and so a regular, rapid pressure build-up can be achieved. Even with electrohydraulic brake systems with a piston pump, the concepts presented here can find application. Thus, e.g. the pump motor eccentric activating the piston pump are decoupled from the pump motor shaft, so that they can assume variable relative speeds (also with opposite sign / direction of rotation) due to the decoupling degree which can be controlled analogously. Thus, e.g. the pump motor is kept at a predetermined speed, e.g. because a continuous control intervention is expected while the piston pump is temporarily disconnected, and does not need to start up at a resumption. In these systems can be provided by the introduction of a clutch in the power train for a rapid pressure reduction, which

In particular, therefore, is advantageous because the corresponding electric motors must be designed for a high torque for high pumping pressure and correspondingly required speed for the pumping volume. LIST OF REFERENCE NUMBERS

2 electromechanical brake

4 electrically operated brake

8 electric motor

10 pinions

14 gears

20 ball screw

26 brake pistons

32 brake pad

40 ordinates

46 abscissa

50 curve

60 clutch

66 curve

72 curve

90 x-axis

96 y-axis

102 z axis

110 curve

Mi engine torque

φ rotation angle

GOI angular speed

M ₃ torque

ω ₃ angular velocity

F, Fi force

M _MeC h mechanical torque

Total ROtatίΟΠSülOIIient

degree of coupling

M ₂ torque

ω ₂ angular velocity

γ rotation angle

M ₃ torque ŗinkelgeschwindigkeit

Claims

claims

A method of operating an electrically actuated brake (4) having an electric motor (8) and a power train that transmits the torque of the motor (8) to an actuator that converts a rotational motion into a translational motion of a braking element, wherein Pressure build-up of the engine (8) in

Pressure build-up direction rotates and thereby presses the brake element against a brake body, characterized in that in the power train, a clutch (60) is connected, wherein the pressure buildup, the clutch (60) in

Essentially fully engaged and the motor (8) rotates in the pressure buildup direction, and wherein the

Pressure reduction, the clutch (60) is substantially completely disengaged.

2. The method of claim 1, wherein the motor (8) during

Pressure reduction in pressure build-up direction turns.

3. The method of claim 2, wherein in the reconstruction of pressure of the motor (8) rotates in the pressure build-up direction and the clutch (60) is engaged.

4. A method for operating an electrically actuated brake (4) with an electric motor (8) and a power train, which transmits the torque (Mi) of the motor (8) to an actuator, which rotates in a translational movement of a

Brake element converts, wherein the pressure buildup of the motor (8) rotates in the pressure build-up direction and thereby presses the brake element against a brake body, characterized in that in the power train, a clutch (60) is connected, wherein the pressure to build the clutch (60) is substantially fully engaged and the engine (8) rotates in the direction of pressure buildup, and wherein for pressure reduction, the clutch (60) substantially

is fully engaged and the engine (8)

opposite to the pressure buildup direction turns.

A method of operating an electrically actuated brake (4) having an electric motor (8) and a power train that transmits the torque of the motor (8) to an actuator that converts a rotational motion into a translational motion of a brake element, into the power train a clutch (60) is connected, wherein the pressure buildup of the motor (8) rotates in the pressure build-up direction and thereby presses the brake member against a brake body, wherein in the power train, a clutch (60) is connected, wherein at

Ordinary braking operations, the method steps are carried out according to claim 4, and wherein at

Braking operations with automatic brake control (4) the method steps according to claims 1 or 2 are performed.

The method of claim 5, wherein in an automatic control operation of the brake (4), the motor (8) is rotated in the direction of pressure build-up until the control process is completed.

Electrically operable brake (4) having an electric motor (8) and a power train, which transmits the torque of the motor (8) to an actuator, which converts a rotational movement into a translational movement of a brake element, wherein the pressure buildup of the motor (8) rotates in pressure build-up direction and thereby the brake element presses against a brake body, wherein in the power train, a clutch (60) is connected.

8. Electrically actuated brake (4) according to claim 7, wherein the power train comprises a transmission (14) and wherein the coupling (60) in the power train between the engine (8) and transmission (14) is arranged.

9. Electrically actuated brake (4) according to claim 7 or 8, wherein the coupling (60) is designed as a rheological coupling with a magnetorheological or electrorheological material.

10. Electrically actuated brake (4) according to one of

Claims 7 to 9, wherein the actuator converts a rotational movement of a spindle rotatably mounted in a spindle nut in a translational movement of a coupled with the spindle nut brake element.

11. Electrically actuated brake (4) according to one of

Claims 7 to 9, wherein the actuator is a rotational movement via a hydraulic pump in a

translational movement of a brake element converts.

12. A braking system with an electrically operable brake (4) according to any one of claims 7 to 11 and a control and regulating unit with means for carrying out a method according to one of claims 1 to 6.