CN113525324A

CN113525324A - Electromechanical brake booster

Info

Publication number: CN113525324A
Application number: CN202110411012.3A
Authority: CN
Inventors: E·普蒙塔尔; A·洛佩斯甘杜尔; M·米勒; T·埃格尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2020-04-16
Filing date: 2021-04-16
Publication date: 2021-10-22
Also published as: DE102020204834A1; JP2021176747A

Abstract

A brake booster having a housing; a spindle nut; a motor; two pull rods; a hook frame; and a pressure piston which can be coupled at a first end to the brake pedal and at a second end to the brake master cylinder and to which a return spring is assigned, which pressure piston carries a follower element at the second end, which follower element engages behind the hook bracket and in the rest position bears against the end face of the spindle nut with a spacer through the hook bracket, so that the follower element is spaced apart from the hook bracket and in the operating position is spaced apart from the hook bracket by a movement of the pressure piston relative to the spindle and from the end face with the spacer. On the side of the follower element facing the hook carrier, an elastomer element is arranged which projects axially in the direction of the hook carrier and/or on the end side of the hook carrier facing the follower element, an elastomer element is arranged which projects axially in the direction of the follower element.

Description

Electromechanical brake booster

Technical Field

The invention relates to an electromechanical brake booster for a vehicle, comprising a housing; having a rotatably supported spindle nut operatively engaged with an axially movable spindle; a motor for rotationally driving the spindle nut so as to move the spindle; two tie rods fastened to the housing and extending parallel to the main shaft; a hook frame fastened at the main shaft, the hook frame being slidably supported at the draw bar; and a pressure piston which extends through the spindle and is movable relative to the spindle, can be coupled at a first end to a brake pedal and at a second end to a master cylinder, and to which a return spring is assigned, wherein the pressure piston carries a follower element at the second end, which engages behind the hook bracket and, in the rest position, bears against the end face of the spindle nut by means of at least one spacer which passes through the hook bracket in such a way that: the follower element is arranged at a distance from the hook carrier and, in the operating position, at a distance from the hook carrier by a displacement of the pressure piston relative to the spindle and at a distance from the end face by means of the at least one spacer.

The invention further relates to a vehicle, in particular a motor vehicle, having a brake booster which is designed as described above.

Background

Electromechanical brake boosters of the type mentioned at the outset are known from the prior art. For example, DE 102015217528 a1 discloses an associated brake booster. If the driver of the vehicle operates the brake pedal during operation, the pressure piston is displaced axially relative to the spindle, so that the master cylinder is directly mechanically operated. Thereby, the distance between the follower element and the hook holder becomes large. In order to achieve the brake force amplification, the electric motor is actuated, which, as a result of the actuation, drives the spindle nut in order to also move the spindle and the hook bracket fastened thereto axially. The spindle therefore follows the electromechanical operation in time, so that a distance is produced at least temporarily between the follower element and the spindle with the hook bracket and between the spacer and the spindle nut. If in this case the driver takes his foot off the brake pedal or slips off the brake pedal, the return spring assigned to the pressure piston is responsible for displacing the pressure piston back against the spindle movement in order to press the pressure piston into the initial position. As a result, the follower element strikes against the hook rack, which may lead on the one hand to a loading of the hook rack and of the follower element and on the other hand to undesired noise generation.

Disclosure of Invention

The brake booster according to the invention with the features of claim 1 has the following advantages: in this case, the impact of the follower element on the frame is reduced, so that on the one hand the impact does not lead to damage of the hook and/or of the follower element, and on the other hand impact noise is reduced or avoided, thus ensuring a further comfort advantage for the user of the brake booster or of the vehicle. The advantage of reduced collision noise is also exhibited, for example, in the following cases: an automated braking demand of the motor vehicle, for example of an autopilot system, is achieved and the hook holder is moved by the spindle in the direction of the following element, which is no longer displaced or operated from now on, as a result of the brake pedal, until it strikes against the following element. According to the invention, for this purpose: at least one elastomer element is arranged on the side of the follower element facing the hook carrier, said elastomer element projecting axially in the direction of the carcass. The elastic element located between the follower element and the hook carrier thus reduces the impact of the follower element on the hook carrier or the impact of the hook carrier on the follower element, and thus advantageously reduces the kinetic energy during the impact. Alternatively, the elastomer element is arranged on the side of the hook holder facing the follower element, which elastomer element projects axially in the direction of the follower element. The advantages mentioned above are likewise achieved thereby. The advantageous embodiment of the brake booster furthermore provides that: the pedal is prevented or damped from vibrating by the reduced collision of the hook carrier and the follower element with one another due to the elastomer element. If the follower element has, for example, a measuring sensor assigned to a measured value sensor or measured value receiver on the housing side, a powerful design solution avoids: the measured value receiver detects an error signal without actuating the brake pedal, due to the vibration of the pedal and thus of the follower element.

According to a preferred development of the invention, at least two, preferably exactly two, or more elastomer elements projecting axially in the direction of the hook carrier or of the follower element are arranged on the follower element or on the hook carrier. According to a further embodiment of the invention, only one elastomer element is arranged at the follower element, which elastomer element extends for this purpose, for example, onto the surface of the follower element facing the hook carrier or onto the surface of the hook carrier facing the follower element. The elastomer element is, for example, sprayed onto the follower element or the hook carrier, wherein it is particularly preferred if the follower element is injection-molded or surrounded by the elastomer element (umspritzen), or at least partially surrounded.

It is furthermore advantageously provided that the follower element or the hook carrier has a receiving recess for each of the elastomer elements. The elastomer element is therefore arranged in the receiving recess of the hook bracket or the follower element, as a result of which the elastomer element is fastened particularly loss-proof at the respective element and thus also reliably ensures that the elastomer element stays in the desired position in the event of higher crash forces. By arranging the respective elastomer element in the receiving recess, the following advantages are furthermore achieved: the radial displacement space of the elastomer element is advantageously limited by the inner diameter of the receiving recess or the inner cross section of the receiving recess, whereby the stiffness of the elastomer element under load is advantageously influenced (Steifigkeit). The respective receiving recess is particularly preferably designed as a slit, so that it extends completely through the follower element and thus forms a passage opening or the slit mentioned. When the receiving recess is configured in accordance with an alternative embodiment in the manner of a blind hole, the following advantages result from the design of the split: the elastomer element can be displaced axially when loaded, as a result of which the characteristic line of action, in particular the damping characteristic line (D ä mpfunkskennlienie), of the elastomer element can be advantageously adjusted.

It is particularly preferred that the respective receiving recess has an undercut which can be engaged behind by the elastomer element for locking the respective elastomer element. When mounted in the receiving recess, the elastomer element can be pushed by its elastic deformability past a locking position engaging behind the undercut, so that the elastomer element returns to its original shape when it reaches the undercut due to its inherent elasticity and thereby advantageously engages behind the undercut. In particular, the respective elastomer element engages the associated undercut axially at the rear, so that a loss-proof arrangement of the elastomer element at the follower element or the hook bracket is ensured. By means of an advantageous embodiment, a simple mounting of the elastomer element on the follower element or on the hook bracket is also ensured.

It is furthermore preferably provided that each elastomer element has a contact end projecting from the follower element or the hook bracket, and a locking portion engaging in the receiving recess, wherein the locking portion has a radially projecting collar for engaging behind the undercut. Each elastomer element therefore has a portion provided for axial locking, which is designed as a radially protruding collar and thus ensures a reliable axial locking at the hook or the follower element also in the relaxed state of the elastomer element. By means of the elastic deformation of the flange or of the locking portion of the follower element, the elastomer element can be mounted inexpensively and simply and also disassembled inexpensively and simply.

It is furthermore preferably provided that an axial recess is formed in the elastomer element for material weakening at the end side of the locking portion, in particular at least at the level of the flange. By means of the material weakening, it is achieved that: the locking part can be deformed in particular in the region of the flange in such a way with little force consumption that: so that the elastomer element can be fitted into the position engaging behind the undercut with little effort. Furthermore, this advantageous embodiment of the elastomer element makes it easier to release the elastomer element from a tool (entform) by which the elastomer element is produced, for example, by injection molding (Spritzgussverfahren). By the subsequent form-fitting axial fixing of the elastomer element at the follower element or the hook bracket, a permanent arrangement of the elastomer element at the follower element or the hook bracket is reliably ensured.

Preferably, the axial recess is configured as a groove extending over the entire width of the elastomer element or as a cup-shaped recess. In both cases, an advantageous material weakening is achieved which ensures the advantages mentioned above. Both the groove and the cup-shaped recess can be produced inexpensively, wherein the rigidity in the region of the flange is comparatively higher by the cup-shaped recess, so that the groove or the cup-shaped recess needs to be selected preferably as a function of the load to be expected.

It is particularly preferred that the elastomer element is configured as a rotary body. The elastomer element can thus be produced inexpensively and with a high number of parts. In addition, the advantage is obtained that improper installation is precluded.

It is furthermore preferably provided that the contact end has an axial stop for bearing on an end face of the follower element or of the hook holder facing the hook holder or the follower element. By means of the axial stop, it is ensured that: the elastomer element can be pressed incompletely through the receiving recess, in particular if the follower element and the hook carrier collide with one another. In particular, the largest outer diameter of the axial stop is greater than the largest inner diameter of the receiving recess, and the collar preferably has a radius or diameter which is at least greater than the inner diameter of the undercut, so that the elastomer element is permanently held in the receiving recess against loss.

According to a preferred refinement of the invention, the at least one spacer has a lateral projection for bearing on the hook carrier, in particular on a bottom part of the hook carrier, wherein the lateral projection, the return spring and the elastomer element are configured in such a way that: after the end of the brake pedal operation performed, when the user no longer operates the brake pedal or no longer applies a force, and in particular the hook frame moves axially to such an extent: in such a way that the at least one stop element cannot come into contact with the spindle nut, the lateral projection of the at least one spacer is moved by the return spring with elastic deformation of the elastomer element until it comes into contact with the hook bracket.

The vehicle according to the invention with the features of claim 11 is characterized by an electromechanical brake booster which is designed according to the invention. The advantages already mentioned are thereby obtained.

Further advantages and preferred features and feature combinations result, in particular, from the content of the preceding description and from the claims. The invention shall be further explained below with the aid of the drawings.

Drawings

Wherein:

fig. 1 shows an advantageous electromechanical brake booster in a simplified longitudinal section;

FIG. 2 shows a detailed arrangement of the brake booster in an enlarged perspective view; and is

Figure 3 shows a cross-sectional view through the arrangement of figure 2.

Detailed Description

Fig. 1 shows an advantageous brake booster 1 in a simplified longitudinal section. The brake booster 1 can be coupled at one end to a brake master cylinder 2 and at the other end to a brake pedal 3, not shown here, of the motor vehicle. The brake booster 1 is used to adjust the hydraulic pressure in the brake master cylinder 2 according to the brake pedal operation. For this purpose, the brake booster 1 has an actuator 4 which has a not shown electric motor and a spindle drive (Spindelgetriebe) 5, by means of which the torque of the electric motor can be applied as a thrust force to the connection of the brake pedal 3 to the master cylinder 2.

The brake booster 1 has a pressure piston 6 which is assigned to the brake master cylinder 2 at one end and is mechanically coupled to a coupling rod 7 at the other end, which is connected to the brake pedal 3 and is moved by actuation of the brake pedal 3. One end of the pressure piston 6 is assigned an elastically deformable coupling disk 8, which is connected (schalten) between the pressure piston 6 and a further pressure piston 9 acting on the brake master cylinder 2. The coupling disk 8 is located on the end side of a hook 10 facing the brake master cylinder 2, which hook is mounted so as to be longitudinally displaceable in a housing 11 of the brake booster 1. For this purpose, two

tie rods

12, 13 are fastened in the housing 11, said tie rods extending parallel to the longitudinal center axis M of the pressure piston 6 and of the brake master cylinder 2. The hook frame 10 has a receiving

opening

14, 15 at its end assigned to the

tie rod

12, 13, in each case, in which a

plain bearing

16, 17 for the

respective tie rod

12, 13 is formed. The

plain bearings

16, 17 are located here at an axial height approximately corresponding to the following: the end face is located at this level, against which the coupling disk 8 rests. The bracket is essentially V-shaped or U-shaped, wherein a portion 18 of the bracket 10, which carries the coupling disk 8, projects axially from a bottom portion 19 of the bracket 10 in the direction of the master cylinder 2. The portion 18 is preferably formed by an element separate from the hook stock 10, which is fastened to the hook stock 10 or to the hook stock base of the hook stock 10, which is formed in a V-or U-shape, in particular is clamped (clamped) thereto. Alternatively, the portion 18 can be formed integrally with the hook holder 10 or with the base of the hook holder. As is shown in fig. 1, in particular in the case of a central connection (zwischenschultchun) of the further crash element, the pressure piston 6 passes through an opening 20 of the portion 18, so that, when the brake pedal 3 is actuated, a compressive force (druckraft) can be applied manually by the pressure piston 6 to the coupling element 8, the further pressure piston 9 and manually to the master brake cylinder 7.

Coaxially to the pressure piston 6, a main shaft 21 of the actuator 4 is arranged, wherein the pressure piston 6 is mounted in a sleeve-like manner in the main shaft 21 in a longitudinally or axially displaceable manner. The spindle 21 is operatively engaged with a spindle nut (Spindelmutter) 22 (Wirkeingriff). When the spindle 21 is arranged in the housing 11 in a rotationally fixed manner, the spindle nut 22 is arranged in the housing in a rotationally fixed manner and for this purpose in an axially fixed manner. The motor is connected to the spindle nut for driving the spindle nut so that when the spindle nut 22 is rotated, the spindle 21 is axially moved.

At its free end facing the brake master cylinder 2, the spindle nut 22 has a radially projecting collar 23, which is assigned to the bottom part 19 of the hook member 10 on the end side. If the electric motor is actuated and the spindle 21 is displaced, the hook 10, which is fixedly connected to the spindle 21, in particular welded, is displaced by means of the spindle 21 in the direction of the brake master cylinder 2, as long as the hook 10 and the spindle 21 axially abut against one another. In this way, a braking force generation can also be effected independently of a brake pedal actuation, for example by means of a braking force demand which is not effected by the driver but by the drive system of the motor vehicle.

A follower element 24 is fastened at the pressure piston 6 at the end facing the brake master cylinder 2 or at the end facing the coupling disk 8. According to the present embodiment, the follower element 24 is configured as a follower disk which is plugged (ausstecken) onto the end of the pressure piston 2 and is fastened in particular at this end. The follower element 24 carries two, three or more spacers 25 which extend in the direction of the flange 23 of the spindle nut 22. For this purpose, the base part 19 of the hook carrier 10 fastened to the main shaft 21 has a recess for each of the spacers 25, through which the spacers 25 pass in the rest position shown in fig. 1, so that the spacers 25 rest on the end faces of the radial projections 23, wherein the follower elements 24 are axially spaced apart from the base part 19 of the hook carrier 10.

The portion 18, against which the coupling disk 8 rests, is axially spaced from the bottom portion 19 of the hook frame 10 by such an extent that: so that the follower element 24 has an axial clearance between the two

portions

18 and 19.

If the brake pedal is actuated, the coupling disk 8 and the further pressure piston 9 are axially displaced by the pressure piston 6. If the actuator 4 is actuated for the purpose of amplifying the braking force, the hook stock 10 displaced by the spindle 21 follows the movement, in particular with a time delay. As a result, the spacer 25, which moves together with the follower element 24, is likewise axially spaced from the end face of the radial projection 23. If the driver merely takes his foot off the brake pedal, the follower element is pulled back by means of the return spring 26, so that the follower element 24 is moved in the direction of the bottom part 19 of the hook frame 10. In order to minimize the impact impulse of the follower element 8 at the bottom part 19 of the hook frame 10, or in the opposite direction, according to the present exemplary embodiment a plurality of elastomer elements 27 are arranged, which project in the direction of the bottom part 19 of the hook frame 10 and are assigned thereto in such a way that: so that the elastomeric element is located between the follower element 24 and the bottom portion 19 to attenuate a collision.

Fig. 2 furthermore shows, in an enlarged perspective view, the follower element 24, which according to the present exemplary embodiment has a cross-shaped cross section, wherein one of the spacers 25 is arranged on each of the four

arms

28, 29, 30 and 31. Optionally, a measuring sensor 32 is also arranged on one of the arms 31, which sensor interacts with a measuring sensor arranged fixedly on the housing in order to monitor the position of the follower element 24 during operation.

In the exemplary embodiment of fig. 2, the elastomer element 27 is arranged in an exploded manner at a distance from the follower element 24. There are currently exactly two elastomeric elements arranged diametrically opposite each other on said

arms

28 and 30.

Fig. 3 shows a cross-sectional view through the arrangement of fig. 2 according to the tangent line a-a marked in fig. 2. The elastomer element 27 is made of an elastically deformable material as a rotary body and has a contact end 33 facing the spindle drive and a locking portion (arrestiendend) 34 assigned to the follower element 24. At its free end, the locking part 34 has a radially projecting collar 35 for engaging axially behind an undercut 36 of a receiving recess 37 of the follower element 24. The receiving recess 37 furthermore has a taper 38, through which the undercut 36 is formed on the side of the receiving recess 37 facing away from the bottom part 19. The contact end 33 furthermore has an axial stop 42 for bearing against the end face of the follower element 24 facing the base part 19. The distance of the axial stop 39 from the flange 35 corresponds approximately to the axial extension of the taper 38. As a result, the elastomer element 33 is held axially on the one hand by the axial stop 42 and on the other hand by the flange 35 at the follower element 24. For assembly, the elastomer element 27 is pressed forward with the flange 35 into the receiving recess 37, wherein the flange 35 is pushed past the taper 38 with elastic deformation thereof until the flange 35, due to its inherent elasticity, again expands radially after passing through the taper 38 and thereby engages behind the undercut 38. This ensures a simple assembly of the elastomer element 27 at the follower element 24.

Advantageously, the elastomer element 27 has, at its locking portion 34 with the flange 35, an axial recess 39 formed in its free end face, which serves to weaken the material of the locking portion 34 in the region of the flange 35, so that the flange 35 is deformed more easily when inserted into the receiving recess 34.

Advantageously, exactly two of the elastomer elements 27 are held at the follower element 24, as shown in fig. 2. Optionally, more than two, in particular three or four, of the elastomer elements 27 are present, so that a particularly stable abutment of the follower element 24 on the base part 19 by means of the elastomer elements 27 is ensured.

As an alternative to the embodiment shown, the elastomer element 27 is fastened not to the follower element 24 but to the bottom part 19 of the hook frame 10. According to a further embodiment, a respective elastomer element 27 is fastened not only at the follower element 24 but also at the bottom portion 19 of the hook frame 10.

According to the exemplary embodiment shown in fig. 2 and 3, two of the spacers 25 have lateral projections 40, which project axially from the follower element 24 and thus define a stop surface 41, up to which the follower element 24 can be moved to the bottom part 19 of the hook bracket. This means that the spacer 25 defines, by means of the respective projection 40, a spacer between the follower element 24 and the bottom portion 19 of the hook frame 10, which spacer limits the maximum deformation of the elastomer element 27. For this purpose, the projection 40 projects laterally to such an extent that: so that it can project beyond the opening 26 into which the spacer 25 furthermore penetrates and can thereby reach a bearing on the base part 19. The projection 40, the return spring 26 and the elastomer element 27 cooperate with one another, in particular with regard to their dimensions, elasticity and deformability, in such a way that: in the event that the stop element 25 cannot come into contact with the spindle nut 23, the follower element 24 is moved in the direction of the base part 19 by the return spring 26 to such an extent that: the elastomer element 27 is deformed to the greatest possible extent until the contact of the follower element 24 with the projection 40 at the stop face 41 at the base part 19 is reached. The return spring 26 thus moves the follower element to the base part 19 with maximum deformation of the elastomer element 27. This is for example the case: after the braking process, the driver takes his foot off the brake pedal and the hook carrier 10 has been moved out in the direction of the master cylinder 2 by the spindle 21.

When the projections 40 are arranged radially outside the spacer 25 according to the exemplary embodiment of fig. 2 and 3, according to an alternative exemplary embodiment: the projections 41 are formed on the inner sides of the spacers 25 facing each other, i.e. project radially inward. This is exemplarily shown in fig. 1.

Claims

1. An electromechanical brake booster (1) for a vehicle, having a housing (11); a spindle nut (22) operatively engaged with an axially movably supported spindle (21); a motor for rotationally driving the spindle nut (22) so as to move the spindle (21); two tie rods (12, 13) fastened to the housing (11) and extending parallel to the main shaft (21); a hook (10) fastened to the spindle (21) and slidingly supported at the tie-rods (12, 13); and a pressure piston (9) which extends through the spindle (21) and is movable relative to the spindle (21) and which can be coupled at a first end to a brake pedal and at a second end to a master cylinder (2) and to which a return spring (26) is assigned, wherein the pressure piston (9) carries a follower element (24) at the second end, which engages behind the hook bracket (10) and in the rest position bears against the end face of the spindle nut (22) by means of at least one spacer (25) which passes through the hook bracket (10): in such a way that the follower element (24) is present at a distance from the hook carrier (10) and, in the operating position, at a distance from the hook carrier (10) by a displacement of the pressure piston (9) relative to the spindle (21) and at a distance from the end face by means of the at least one distance holder (23), characterized in that at least one elastomer element (27) projecting axially in the direction of the hook carrier (10) is arranged on the side of the follower element (24) facing the hook carrier (10) and/or at least one elastomer element (27) projecting axially in the direction of the follower element (24) is arranged on the end face of the hook carrier (10) facing the follower element (24).

2. Electromechanical brake booster according to claim 1, characterized in that at least two, in particular exactly two or more, elastomer elements (27) which protrude axially in the direction of the hook carrier (10) or of the follower element (24) are arranged at the follower element (24) or at the hook carrier (10).

3. Electromechanical brake booster according to one of the preceding claims, characterized in that the follower element (24) or the hook carrier (10) has for each elastomer element (27) a receiving recess (37) for fastening the elastomer element.

4. Electromechanical brake booster according to one of the preceding claims, characterized in that the respective receiving recess (37) has an undercut (26) for locking the respective elastomer element (27) which can be engaged behind by the elastomer element (27).

5. Electromechanical brake booster according to one of the preceding claims, characterized in that the respective elastomer element (27) has a contact end (33) projecting from the follower element (24) and a locking portion which engages in the receiving recess (37), wherein the locking portion (34) has a radially projecting flange (35) for engaging the undercut (36) at the rear.

6. Electromechanical brake booster according to one of the preceding claims, characterized in that an axial recess (39) is formed in the elastomer element (27) for material weakening in the free end side of the locking portion (34), in particular at least at the level of the flange (35).

7. Electromechanical brake booster according to one of the preceding claims, characterized in that the axial recess (39) is configured as a groove extending over the entire width of the elastomer element (27) or as a cup-shaped recess.

8. Electromechanical brake booster according to one of the preceding claims, characterized in that the elastomer element (27) is configured as a rotary body.

9. Electromechanical brake booster according to one of the preceding claims, characterized in that the contact end (33) has an axial stop (40) for the bearing on the end side of the follower element (24) facing the hook carrier (10) or for the bearing on the end side of the hook carrier (10) facing the follower element (24).

10. Electromechanical brake booster according to one of the preceding claims, characterized in that the at least one spacer (25) has a lateral projection (40) for bearing on the hook bracket (10), wherein the return spring (26) and the elastomer element (27) are configured such that: so that a lateral projection (40) of the at least one spacer (25) can be moved by the return spring (26) after the end of a brake pedal operation, with elastic deformation of the elastomer element (27), until it rests on the hook bracket (10).

11. Vehicle, in particular motor vehicle, having a brake booster according to one of claims 1 to 10.