DE19831838B4 - braking device - Google Patents

Abstract

Braking device for a vehicle, with
A brake disc (8) connected to a rotating part to be braked,
A brake pad plate (39) having a brake lining (40), which is arranged opposite to the brake disk (8) with its brake lining (40),
An actuator having an electric motor for actuating a threaded spindle (2) in order to press the brake lining plate (39) against the brake disk (8),
- means (45, 48, 50, 55, 60, 61) for guiding the brake pad plate (39), wherein the means for guiding the brake pad plate (39) are formed independently of the threaded spindle (2), so that during a braking operation the threaded spindle (2) occurring lateral loads are reduced, characterized in that the means as two guide bracket (50) are formed, each having a guide hole (55) through which in each case a guide pin (48) extends, at one of the threaded spindle enclosing housing (1) is fixed, wherein the threaded spindle (2) approximately midway between the two ...

Description

The The invention relates to a braking device for a vehicle, comprising a brake disk, which is connected to a rotating part to be braked, a brake pad having a brake lining plate, with their Brake pad is arranged opposite the brake disc, an actuator having an electric motor for actuating a threaded spindle has to press the brake pad plate against the brake disc, means to the leadership of Brake lining plate, wherein the means for guiding the brake lining plate independently are formed by the threaded spindle, so that during a braking operation On the threaded spindle occurring transverse loads are reduced.

Such a braking device is z. B. from the earlier priority, but not previously published DE 196 48 581 A1 known. In the known brake device, the brake lining is provided with a retaining spring, which is connected to the brake lining plate and which serves to fasten the brake lining in a recess of a hydraulically actuable brake piston. A guide of the brake pad thus takes place by means of the brake piston, which in turn is guided in a bore of a brake housing. However, the prior art arrangement is not able to perform a torque transmission between the brake pad plate and the brake housing.

Another such brake device is from the DE 40 21 572 A1 known. This brake device has a hollow piston in which a rotary shaft is supported, wherein the rotary shaft is formed as a ball screw, with which a rotational movement can be converted into a sliding movement of the piston. The rotary shaft is driven by a worm gear by an electric motor.

Of the Piston is outside flattened on two sides and on these surfaces by means of plain bearings on casing stored so that he is secured against twisting. In addition, the piston is on the housing means Linear ball bearings that support the frictional forces when moving the piston to minimize.

Basically for braking devices that to generate sufficient braking forces in a short actuation path a high operating force to press a brake pad must be transmitted against a brake disc. For an electromechanical brake device This means that a considerable Moment of force in the conversion of the rotational movement generated by the electric motor in a translational movement to generate the clamping force must be provided.

at Use of a ball screw is the maximum transferable Clamping force due to geometric dimensions and number of supporting balls limited. In electromechanical braking devices therefore uses a roller screw instead of a ball screw, because the roller screw with the same space transfer a significantly larger clamping force can. The efficiency of a roller screw with feedback is however, much lower than that of a ball screw.

electromechanical Braking devices are therefore either with a roller screw and a correspondingly large Electric motor designed to compensate for the low efficiency and can the desired Provide clamping force, or have a ball screw and a corresponding small electric motor, can but then often do not provide the desired clamping force. There is therefore a significant need for a braking device with high clamping force and high efficiency, that is after a compact braking device with a relatively small electric motor, while still the desired Clamping force can be generated should.

Further On the one hand during a braking operation, the brake pads Piece taken, On the other hand, the clamping forces expand the brake disc cross-over Fist, causing lateral forces be transferred to the threaded spindle. this leads to to a deterioration of the mechanical efficiency of the Threaded spindle having gear.

Farther Electromechanical braking devices have been developed at which the brake lining plate by means of a pressure piece and a bellows is connected to the spindle. Through the bellows and the pressure piece the bending moment is kept away from the spindle. The bellows but means a restriction in the selection of the transmission for the conversion of the rotational movement of the Electric motor in a translational movement of the spindle for actuating the Brake pad plate insofar as the pitch of the spindle a certain Do not exceed the measurement allowed to allow the bellows with the maximum occurring spindle torque not overloaded becomes.

The invention has for its object to form the brake device mentioned above so that they still in a compact design can provide a high clamping force.

The The object is achieved by a braking device with the features of the claim 1 solved. Advantageous embodiments of the invention are specified in the subclaims.

The solution according to claim 1 provides means for guiding the brake lining plate before, which formed as two guide bracket are each a leadership hole have, through which each extends a guide pin, the is attached to a threaded spindle enclosing housing, wherein the Threaded spindle is arranged approximately centrally between the two guide pins. By reducing the lateral loads, the efficiency becomes for the Conversion of a rotational movement of the electric motor in a translational movement the threaded spindle increases, allowing a compact electric motor to generate the necessary Clamping force is sufficient. This in turn allows a compact design of the braking device, where all mechanical requirements regarding. The clamping force and of the response can be.

The solution According to claim 10 sees a special ball nut for actuating the Ball screw before, the lower on the load input side Stiffness than otherwise Has area. As a result, the load is distributed over several threads, whereby the generated by such a ball screw Clamping force and very high demands of braking devices heavy vehicles is enough.

The The invention will now be described by way of example with reference to the accompanying drawings explained in more detail. It demonstrate:

1 a region of a brake device according to the invention with independently of a threaded spindle for actuating a brake pad plate guide means formed in perspective view,

2a schematically a horizontal section through the brake device 1 .

2 B schematically a vertical section through the brake device 1 .

3 the brake pad plate of the brake device after 1 in front view together with guide pins,

4 a further embodiment of the braking device according to the invention with independently of the threaded spindle formed guide means,

5 a further braking device according to the invention with independently of the threaded spindle formed guide means,

6a the pressure plate of the brake device 1 together with two guide pins and a threaded spindle,

6b a section through the pressure plate along the line AA 6a .

7 a further braking device according to the invention with independently of the threaded spindle formed guide means,

8th a vertical section through a braking device according to the invention,

9 in the 8th shown braking device in side view,

10 schematically a top view of in 8th shown braking device,

11 schematically a conventional ball screw in longitudinal section together with a graphical representation of the load distribution,

12 a ball screw according to the invention in longitudinal section together with a graphical representation of the load distribution,

13a and 13b in each case a section through a conventional ball screw, and

14a and 14b in each case a section through a ball screw according to the invention.

The braking device according to the invention has a housing 1 in which an electromechanical transducer means (actuator) for actuating a ball screw 2 is provided ( 1 . 8th ). On the case is one from a bridge 4 and a clamp arm 5 existing fist 6 arranged on the edge of a brake disc 8th embraces. The housing 1 and the fist 6 are by means of a bending and torsion-resistant, thin-walled sheet metal ring 7 connected with each other.

The electromechanical transducer device or the actuator has an electric motor which consists of a winding 10 , which forms the stator, and a rotor 12 is trained. The rotor is tubular, wherein on the lateral surface of the armature 11 is attached. The tubular rotor is inside the magnet 10 arranged, with at both ends of the anchor 11 each a needle roller bearing or a ball bearing 13 between the rotor and the out the magnet 10 and the housing 1 trained stator is provided so that between the rotor and the stator always a predetermined air gap 14 is complied with. The tubular body 12 is at his from the brake disc 8th bent away from the end bent outwards, the bend as a gear 15 is trained. The gear 15 stands with the drive side of one on the housing 1 arranged planetary gear 17 engaged. The planetary gear 17 is designed as a one-or two-stage reduction gear. The output side of the planetary gear 17 forms an annular disk 18 that have a bellows 19 with a tubular rotary body 21 connected is. The bellows 19 is flexurally elastic, but torsionally stiff, so that he the rotational movement of the annular disc 18 directly on the tubular rotary body 21 transfers.

The tubular rotary body 21 is with his to the brake disc 8th pointing end rotatably with a ball nut 23 connected. The ball nut 23 is at its front, to the brake disc 8th pointing edge region is bent radially outward. This bend 24 is stepped from one in cross-section in the area between the tubular rotary body 21 and the body 12 of the rotor extending body of revolution of the fist 6 engaged behind. This rotational body points on the side facing away from the brake disc side of the bend 24 the ball nut arranged ring segment 25 on, being between this ring segment 25 and the bend 24 an axial ball bearing 27 and between the inwardly facing end face of the ring segment 25 and the main body of the ball nut 23 a radial fixing ball bearing 28 are arranged. The radial fixing ball bearing 28 is preferably in the region of the longitudinal center of the ball nut 23 , The ball nut 23 sits with a set of bullets 30 on the ball screw 2 ,

The ball screw 2 has at its facing the brake disc end face a central, elongated recess 32 on, in the a bolt-shaped pressure piece 33 is loosely inserted, which is rounded at both end regions and between the bottom of the recess 32 and a printing plate 35 is trapped. In the peripheral area of the brake disc 8th pointing end face of the ball screw 2 is the ball screw 2 by means of another bellows 37 with the pressure plate 35 flexurally elastic, but torsionally connected. The pressure piece 33 Holds the pressure plate 35 and the ball screw 2 at a predetermined distance, with the pressure plate 35 around the loosely inserted pressure piece 33 can be pivoted.

The printing plate 35 is preferably designed as a so-called point load / Gleichstrecken load converter plate (PGKP), that is, that the shape is designed so that the pressure piece 33 on the printing plate 35 applied, applied at one point compressive force evenly on one to the brake disc 8th showing pressure surface 36 is transmitted. The shape of the printing plate 35 is determined by a finite element calculation, which is usually on the brake disc 8th facing away from a shape with a concave from the outside towards the center rising curvature and in the center of the pressure plate 35 a dent is formed, in which the pressure piece 33 outsourced. At the printing surface 36 is releasably a brake pad plate or brake pad back plate 39 attached, on which a brake pad 40 is attached. For a printing plate designed as a PGKP 35 can be a thin brake pad plate 39 be used. The brake lining plate 39 is one together with the respective brake pad 40 Exchanging wear part, which can be saved with a thin brake lining plate considerable costs.

At the clamp arm 5 the fist 6 is another brake pad plate 39 ' with one to the brake disc 8th pointing brake pad 40 ' attached and for example by means of a screw 42 attached.

By providing the bellows 19 between the annular disc 18 and the rotary body 19 the actuator containing the electric motor is decoupled from the structural deformation occurring during braking. This allows in the long term a precise function of the electric motor and in particular a permanently narrow air gap between the rotor and stator.

In 1 is shown a perspective view of the housing and the displacement mechanism of the housing-side brake pad. At the housing 1 are outside two guide grooves 45 formed, each by two from the housing outwardly projecting wall strip 46 are limited. The guide grooves 45 are parallel to the ball screw and are at about the same height as the ball screw 2 arranged. At the brake pad 40 facing end face of the housing 1 are two guide pins 48 educated. The guide pins 48 are in turn arranged parallel to the ball screw. They are on the housing adjacent to the guide grooves 45 formed, with their height position of the middle between the two conversion strips 46 the guide grooves 45 equivalent.

The brake pad plate is equipped with two guide brackets 50 provided at the height of the guide grooves 45 are arranged and at right angles to the brake pad plate 39 are connected. The guide bracket 50 consist essentially of a strip-shaped wall part, which is a distance from the brake lining plate 39 twice stu fenced at right angles. The guide bracket 50 thus has a short, right angle to the brake pad plate 39 connected connection section 52 , a short tangential guide section adjoining it at a right angle 53 and a long radial guide section 54 on. At the tangential guide section 53 is a leadership hole 55 introduced by each one of the guide pin 48 extends. The radial guidance section 54 is located at least partially in one of the guide grooves 45 and preferably has at its longitudinal edges downwardly or upwardly projecting nipples, which directly on the wall strip 46 the guide groove 45 issue. These nipples 56 Prevent the guide bracket from corrosion in the guide grooves 45 stuck.

The guide bracket 50 are thus through the radial guide sections 54 slidable in the guide grooves 45 stored, with respect to the housing 1 can not move up or down. This means that the brake lining plate 39 and thus the brake pad 40 guided in the horizontal direction, so that the position of the brake pad 40 in the radial direction with respect to the brake disc 8th is clearly defined. With the radial guide sections 54 thus becomes the radial position of the brake lining 40 with respect to the brake disc 8th established.

The guide pins 48 sit with a small clearance with respect to the tangential direction of the brake disc 8th in the leadership holes 55 the guide bracket 50 ( 3 ), so that the pad is pulled up to a circumferential force corresponding to a deceleration of z = 0.2, and the guide bar 50 only when exceeding this peripheral force to the respective opposite in the circumferential direction guide pin 48 supported.

The tangential guide section 53 is with respect to the brake pad plate 39 a piece towards the housing 1 staggered. This offset corresponds at least to the thickness of an unused brake pad 40 and ensures that when adjusting the brake device due to the pad wear the engagement between the guide pin 48 and the guide holes 55 is ensured even with heavily worn brake pads.

In the brake device according to the invention thus the brake lining plate 39 and the brake pad attached thereto 40 regardless of the ball screw 2 through the guide bracket 50 both in the tangential and in the radial direction with respect to the brake disc 8th guided. As a result, the transverse forces occurring during braking are not on the ball screw 2 transferred or at least greatly reduced. Because these lateral forces from the ball screw 2 to be held, the works out of the ball screw 2 , the ball bearing nut 23 and the balls in between 30 trained ball screw always in the ideal efficiency range, whereby a relatively small drive unit is sufficient to provide a sufficient clamping force available.

In 4 a further embodiment of the braking device according to the invention is shown, in turn, two guide bracket 50 but which are not formed on a brake pad plate, but on the pressure plate. This is advantageous because when the brake lining is worn, only the brake pad needs to be worn 40 together with the brake pad plate 39 be replaced, with the guide bracket 50 remain in their arrangement on the brake device.

Another embodiment in which the guide means directly on the pressure plate 35 are arranged in 5 shown. The guide means in this case guide pins 60 on, each with one end to the pressure plate 35 are attached and with their other end in one on the housing 1 trained guide bush 61 to store. The guide bush is used to reduce the frictional resistance between the guide pins 60 and the guide bush 61 with a lubricious coating 62 lined, such as a Teflon layer.

To prevent distortion of the two guide pins 60 due to manufacturing tolerances or temperature expansion of the printing plate 35 the outflow-side guide bushing can be formed with a hole of oblong cross-section, so that the guide bolt bears with play therein. An alternative embodiment is in the 6a and 6b shown at the outlet side guide pin 60 in a slot 63 the guide plate 35 sitting. The slot 63 extends in the width direction of the guide plate and has at its two lateral edges narrow inwardly projecting webs 64 on, which are undercut to the brake pad side. The one in this slot 63 bearing guide pins 60 is at its end with grooved cuts 65 provided, in which the inwardly projecting webs 64 engage the slot, so that the bolt 60 is stored in the longitudinal direction of the slot with clearance and perpendicular to the printing surface 36 is fixed essentially free of play. This movement game of the bolt 60 in the printing plate 35 allows a compensation of the distance between the two guide pins 60 , so that these without play forces in the two jacks 61 can be stored.

The brake lining plate 39 is via a clamping spring (not shown) with the pressure plate 35 connected. The clamping spring allows a radial movement of the brake lining plate 39 opposite the pressure plate 35 so that between the brake pad plate 39 and the printing plate 35 an interface with axial forced operation and radial degree of freedom exists. The brake lining plate 39 can occur when circumferential force against the pressure plate 35 move and is supported on a holder (not shown). To reduce the friction between the brake lining plate 39 and the printing plate 35 and thus to reduce the bolt load, the brake pad plate 39 as well as the printing plate 35 be formed of a material or with a surface treatment with a low coefficient of friction.

A simplified embodiment of the braking device according to the invention is in 7 shown, essentially those of 1 corresponds, but wherein the radial guide portion of the guide bracket 50 and the corresponding guide groove 45 are omitted. The guide bracket 50 have only the connection section 52 and the tangential guide section 53 on that with the guide holes 55 are provided, through which the guide bolts 48 extend. This simplified embodiment may be configured to provide a radial guide with guide bushes (not shown) received in the guide holes 55 stuck and in the longitudinal direction of the guide pin 48 are extended so that they tilt the guide bracket 50 opposite the guide pins 48 prevent.

Another solution according to the invention for increasing the clamping force by increasing the load capacity of the ball screw of a braking device is described below with reference to 8th to 14b explained.

11 shows schematically in cross section a conventional ball screw with a ball nut 68 , a ball screw 69 and several balls in between 70 , The ball nut 68 is single-ended on a thrust bearing 71 stored. A clamping force F is to the spindle 69 on the side of the thrust bearing 71 created. The load generated by the clamping force F is for the most part of the load entry-side first three rounds 72 the thread of the ball screw 69 and the recirculating ball nut 68 recorded, so that the other rounds contribute only slightly to the load transfer. because of the small number of revolutions, which take over the substantial part of the load, the clamping force generated at the ball drive is limited.

The reason for this is that at the axial load of the ball drive a compression of the ball screw and an elongation of the ball nut occur, so that the remote from the load application side, opposing grooves of the respective revolutions do not match exactly and are offset from one another. The load entry side grooves of the circulations are slightly offset from the other circulations, so that they have to take over the substantial part of the load ( 13a . 13b ).

According to the invention therefore a ball drive is provided, the ball nut 23 Load input side has a lower stiffness than in the remaining area of the ball nut. This is easiest by a ball nut 23 realized, the load entry side has a smaller wall thickness than in the remaining area.

12 shows a two-piece recirculating ball nut 23 the one inner bearing bush 74 and an outer cylindrical nut housing 75 having. The bushing has in cross-section from the load input side to Lastaustragsseite increasing profile, wherein lastaustragsseitig a radially outwardly projecting annular projection 76 is trained. The ring protrusion 76 is from a corresponding ring segment 75 of the mother housing 75 engaged behind. Load entry side, the nut housing is bent radially outward to a contact surface 79 for a thrust bearing 80 provide. Through this two-part design of the ball nut 23 becomes the bearing bush loaded on pressure 74 from the loaded on train nut housing 75 biased, with the ball screw 2 engaged bodies, namely the bearing bush 74 , is formed with a stiffness distribution according to the invention and yet a zugbelastete recirculating ball nut 23 is created. As from the in 12 shown diagram, the individual load of the respective revolutions is significantly lower than in the conventional embodiment and is at most about 17%, so that the total load distributed evenly over the individual rounds. This makes it possible to transmit higher forces with the ball drive according to the invention and thus to provide a higher clamping force.

Alternative embodiments of the recirculating ball nut according to the invention 23 are in the 14a and 14b shown. The embodiment according to 14a has a pressure-loaded nut in which the wall thickness of the load input side to Lastaustragsseite increases substantially continuously.

The embodiment according to 14b has a tensile load nut, the spindle load by means of a spindle sleeve 82 is diverted so that they are attached to the thrust bearing 71 removed side of the ball nut is introduced.

A preferred, one-piece embodiment of the ball nut 23 is in 8th shown. This ball nut already described above 23 is with the bend 24 provided so that they can be loaded from the outside to train. In the area of the bend 24 from the load entry side is a slot into which the ball screw 2 Circumferential tubular body of recirculating ball nut 23 introduced so that the brake disc 8th pointing region of the ball nut has a smaller wall thickness than the area removed from the brake disc. Since the load input side on the side of the brake disc or the pressure plate 35 is located, this ball screw load input side has a lower rigidity than the load discharge side, whereby the effect according to the invention of the uniform distribution of the load of the individual revolutions is achieved.

hereby the load of the single round is reduced and the load can on several rounds be distributed. In conventional Ball drives, the main load was taken from two to three rounds, whereas in the case of the ball drive according to the invention the load can be spread over up to 8 or more rounds. hereby can with a high efficiency ball screw Transmit forces be, as it was previously only known from roller screw drives. It is thus created a transmission part, the high efficiency the for the brake device can transmit necessary application forces, causing it possible is to provide relatively small drive units and the entire braking device compact form.

at the embodiments described above inventive ball drives the recirculating ball nuts have areas with different wall thickness. For the Invention is essential that the Stiffness of the ball nut to that of the ball screw customized is. This can also be similar Way by forming a hollow ball screw, the one correspondingly variable wall thickness owns or by providing different materials to the Ball screw or be created on the ball nut.

Furthermore, in an advantageous embodiment ( 9 . 10 ) The support of the housing in which the pads are supported in the circumferential direction, by means of retaining arms 84 attached noses 85 , The noses 85 are arranged on over the brake disc center and in the line of action of a z = 0.2 peripheral force-resultant and formed of a hard wear-resistant material. As a result, the tangential inclination of the fist is minimized or eliminated to the brake disc, since the friction forces act on both sides of the brake disc on the same length lever arms. This special arrangement is advantageously both inlet and outlet side provided to ensure this function in forward and reverse.

In the axial direction, that is in the direction of movement of the Ge threaded spindle 2 is the case 1 by means of axially extending housing pins 87 in cylindrical rubber bushes 88 stored so that the housing pins 87 in the rubber bushes 88 can be moved to the axial wear adjustment and are fixed against tumbling. As it is in 10 is shown, the housing is formed so that it is mainly loaded on train, whereby radial deformations are reduced and the radial oblique wear is reduced.

Claims (18)

Brake device for a vehicle, with - a brake disc ( 8th ), which is connected to a rotating part to be braked, - a brake pad ( 40 ) having brake pad plate ( 39 ), with their brake pad ( 40 ) of the brake disc ( 8th ) is arranged opposite, - an actuator having an electric motor for actuating a threaded spindle ( 2 ) to the brake pad plate ( 39 ) against the brake disc ( 8th ), - means ( 45 . 48 . 50 . 55 ; 60 . 61 ) for guiding the brake lining plate ( 39 ), wherein the means for guiding the brake pad plate ( 39 ) independent of the threaded spindle ( 2 ) are formed, so that during a braking operation on the threaded spindle ( 2 ) occurring lateral loads, characterized in that the means as two guide bracket ( 50 ) are formed, each having a guide hole ( 55 ), through which in each case a guide pin ( 48 ), which on a threaded spindle enclosing housing ( 1 ), wherein the threaded spindle ( 2 ) approximately in the middle between the two guide pins ( 48 ) is arranged. Braking device according to claim 1, characterized in that the means ( 45 . 48 . 50 . 55 ; 60 . 61 ) for guiding the brake lining plate ( 39 ) directly on the brake pad plate ( 39 ) attack or are formed on this. Braking device according to claim 1, characterized in that the means ( 45 . 48 . 50 . 55 ; 60 . 61 ) for guiding the brake lining plate ( 39 ) directly on one between the brake pad plate ( 39 ) and the spindle ( 2 ) arranged pressure plate ( 35 ) attack or are formed on this. Braking device according to one of claims 1 to 3, characterized in that the means for guiding the brake lining plate ( 39 ) Radial guide means ( 45 . 50 ; 60 . 61 ) exhibit. Braking device according to claim 4, characterized in that the radial guide means at least one guide element ( 50 ; 60 ), which in the direction of movement of the threaded spindle ( 2 ) is displaceable and mounted substantially free of play in the radial direction of the rotating part. Braking device according to one of claims 1 to 5, characterized in that the means for guiding the brake lining plate ( 39 ) Tangential guiding means ( 48 . 50 ; 60 . 61 ) exhibit. Braking device according to claim 6, characterized in that the tangential guide means at least one guide element ( 50 ), which in the direction of movement of the threaded spindle ( 2 ) is displaceable and stored in the tangential direction of the rotating part substantially free of play or with little play. Braking device according to one of claims 1 to 7, characterized in that the pressure plate ( 35 ) has two holes, in each of which a guide pin ( 60 ) is arranged with one end, wherein the guide pins ( 60 ) approximately parallel to the threaded spindle ( 2 ) and on the housing ( 1 ) are mounted in the direction of movement of the threaded spindle. Braking device according to claim 8, characterized in that the outlet-side hole is formed in the pressure plate as a slot in which the guide pin ( 60 ) is mounted with a game in the longitudinal direction of the elongated hole. Braking device for a vehicle according to one of claims 1 to 9, characterized in that the threaded spindle ( 2 ) is formed as a ball screw, which by a ball nut ( 23 ) is actuated, wherein the ball nut ( 23 ) and the threaded spindle ( 2 ) have a corresponding thread in which balls ( 30 ) are arranged, and with their rigidity are adapted to each other so that the load is distributed as evenly as possible over several revolutions of the thread. Braking device according to claim 10, characterized in that the ball nut ( 23 ) a lower load on the load input side stiffness than in the remaining area of the ball nut ( 23 ) having. Braking device according to claim 11, characterized in that the recirculating ball nut ( 23 ) Load input side has a smaller wall thickness than in the remaining area. Braking device according to claim 12, characterized in that the ball screw ( 2 ) in which with the ball nut ( 23 ) engaging area load input side has a higher rigidity than load discharge side. Braking device according to one of claims 1 to 13, characterized in that the actuator of the electric motor and a transmission ( 17 ) is formed and in a housing ( 1 ), wherein the housing ( 1 ) with a sheet metal ring ( 7 ) to a brake disc ( 8th ) overarching fist ( 6 ) is coupled and the transmission with a bellows ( 19 ) is coupled to the ball screw, so that the actuator of deformations of the fist ( 6 ) is decoupled. Braking device according to claim 14, characterized in that the recirculating ball nut ( 23 ) with an axial roller bearing ( 27 ) and a radial fixing ball bearing ( 28 ) on the fist ( 6 ), wherein the radial fixing ball bearing in the region of the longitudinal center of the ball nut ( 23 ) is arranged. Braking device according to claim 14 or 15, characterized in that the electric motor comprises a rotor and a stator, wherein between the rotor and the stator at least one ball bearing ( 13 ) is provided, so that a predetermined air gap ( 14 ) is formed between the rotor and the stator. Braking device according to one of claims 14 or 16, characterized in that the transmission ( 17 ) is a planetary gear. Braking device according to one of claims 1 to 17, characterized in that between the ball screw ( 2 ) and the brake pad plate ( 39 ) a point load / DC load converter plate as a pressure plate ( 35 ) is arranged.