JP7538320B2 - Electromechanical brake booster - Google Patents

Description

The present invention relates to an electromechanical brake booster for a vehicle, comprising a spindle nut which is axially supported and engages with a spindle, an electric motor for rotating the spindle nut to slide the spindle in an operating direction, and a pressure piston which is movable in the operating direction by the spindle, the pressure piston being connectable at one end to a master brake cylinder and at the other end to a connecting rod which is connected to the spindle by a coupling device and which is connectable to a brake pedal, at least one preloadable or preloaded return spring acting against the operating direction, in particular on the pressure piston, a housing, in particular consisting of several parts, which accommodates at least the pressure piston, the coupling device and the at least one return spring, at least one tension rod which is fixed to the housing and extends through the housing parallel to the spindle, and anti-rotation means for the spindle.

Electromechanical brake boosters of the type mentioned at the beginning are already known from the prior art. For example, EP 1 299 633 A1 discloses an electromechanical brake booster of the type mentioned at the beginning. When the driver of the vehicle operates the brake pedal during driving, a pressure piston is caused to slide axially relative to the spindle, whereby the master brake cylinder is directly mechanically actuated by the driver. To achieve the brake force boost, an electric motor is driven, which, when actuated, drives a spindle nut, which in turn causes the spindle to slide axially in a direction toward the master brake cylinder, thereby applying an additional actuation force to the master brake cylinder. In order to prevent the spindle from being rotated by the rotation of the spindle nut without being axially slidable, a rotation prevention means is correspondingly arranged on the spindle. In this case, the spindle is guided by a bracket extending transversely perpendicular to the spindle along a tensile rod extending parallel to the spindle through the housing. For this purpose, the bracket has radially protruding tongues through which a tension rod is guided in each case, and an elastomer element is integrated for a substantially play-free plain bearing between the respective tension rod and the tongue to form a suitable plain bearing. The bracket is connected to the spindle in a non-rotatable manner, so that when the electric motor applies a torque to the spindle nut, the spindle is supported in the rotational direction on the tension rod, thereby preventing the rotational movement, and the force exerted by the electric motor is thus converted into a pushing movement of the spindle in the actuation direction or in the direction towards the master brake cylinder.

DE 10 2015 217 528 A1

The brake booster according to the invention with the features of claim 1 has the advantage that the anti-rotation mechanism is decoupled from the tension rod, which in particular simplifies assembly and reduces the number of individual parts. According to the invention, the anti-rotation mechanism has at least one rotation stop fixed on the spindle and at least one rotation counter stop formed by the housing, which at least limits and preferably prevents the spindle from rotating in the housing. The anti-rotation mechanism therefore does not act between the tension rod and the spindle, but directly between the housing and the rotation stop or the spindle. This ensures that the anti-rotation mechanism is independent of the tension rod, and a joint between the tension rod and the anti-rotation mechanism during assembly is avoided. This also makes it possible to dispense with sliding elements that allow an improved guidance of the conventional bracket on the tension rod. This also allows the position of the anti-rotation mechanism or the point of action of the anti-rotation mechanism to be realized independently of the tension rod or rods, which allows for greater design freedom in the design of the brake booster and in particular improves the efficient use of the installation space. The rotation prevention stop can be formed, for example, by the shape of the housing, for example by a recess in the housing or a peripheral wall section that protrudes inward. In this way, the rotation prevention stop is formed integrally with the housing, ensuring the above-mentioned advantages.

According to a preferred development of the invention, the anti-rotation means has at least one lateral projection forming a rotation stop. This projection is arranged or fixed in particular directly on the spindle or arranged or fixed to a coupling device. In particular, the lateral projection is preferably arranged at least on the end of the spindle facing the master brake cylinder, which normally protrudes axially from the spindle nut. This ensures that the projection may protrude radially beyond the spindle nut in order to cooperate reliably with the rotation counter stop of the housing.

It is furthermore provided that the rotational stop is arranged at a distance from at least one tension rod such that, viewed in the direction of rotation of the spindle nut, the rotational stop is located between the tension rod and the rotational stop of the rotation prevention means in the direction of rotation of the spindle nut for operating the master brake cylinder. This ensures that the rotational stop of the rotation prevention means does not come into contact with the tension rod itself. In a preferred manner, the rotational stop of the housing extends parallel to the tension rod in the longitudinal direction of the housing and along at least the maximum possible movement of the spindle in the housing, in order to ensure the rotation prevention, regardless of the axial position of the spindle or the linkage.

According to a preferred development of the invention, the projection has an opening through which the tension rod extends at a distance from the projection. In this case, the projection of the anti-rotation means is fitted over the tension rod, so that the anti-rotation is achieved by the tension rod regardless of the direction of rotation of the spindle. The opening is preferably designed to be closed on the edge side, so that the projection completely surrounds the tension rod. In particular, the opening and the tension rod are designed in such a way that a play is provided between the opening and the tension rod in the direction of rotation such that the rotation stop can reach the rotation counter stop without the projection hitting the tension rod.

It is furthermore preferably provided that the rotational stop of the housing is formed by the contour of the peripheral wall of the housing, as described above. This ensures easy installation of the rotational stop in the housing.

It is furthermore preferably provided that the coupling device has a bracket, in particular a metal bracket, fixed to the spindle, which extends in a transverse direction generally perpendicular to the longitudinal direction of the spindle and has a projection at least at one end. The bracket is welded in a suitable manner to the spindle in order to ensure a robust connection between the spindle and the bracket, which ensures a continuous transmission of the torque applied to the spindle to the bracket. Due to the bracket extending in a transverse direction perpendicular to the longitudinal direction of the spindle, the projection of the bracket formed at one end is already directed towards the housing in order to cooperate suitably with the rotation counter stop as a rotation stop.

In a preferred embodiment, the anti-rotation means has at least two rotation stops and at least two rotation counter stops, in particular arranged diametrically opposite each other. For this purpose, the bracket preferably has a projection on each of its two ends, which projections each form a rotation stop.

According to a preferred development of the invention, two tension rods are arranged in the housing, which extend through the housing. Due to the presence of two tension rods, the load-bearing capacity of the housing and the connection with the master brake cylinder are optimized.

Furthermore, it is preferably provided that each tension rod can be threadably connected at one end to the master brake cylinder, thereby ensuring proper assembly or connection of the tension rods and transmission of the force of the brake booster to the master brake cylinder.

According to a preferred development of the invention, each rotary stop has a wear protection layer, in particular a plastic coating or plastic covering, which is arranged in correspondence with the rotary stop. When the rotary stop rests against the rotary stop and the spindle is axially slid, the wear protection layer ensures low friction between the rotary stop and the rotary stop, which results in reduced power losses. Furthermore, the wear protection layer ensures low wear of the anti-rotation means and thus an overall high service life of the brake booster.

1 is a schematic longitudinal section of a preferred electromechanical brake booster; FIG. FIG. 2 is an enlarged cross-sectional view showing an enlarged detail of the brake booster;

The present invention will be explained in detail below with reference to the drawings.

Figure 1 shows a schematic longitudinal section of a suitable brake booster 1. The brake booster 1 can be connected at one end to a master brake cylinder 2 and at the other end to a brake pedal 3 of a motor vehicle, not shown here. The brake booster 1 is used to adjust the hydraulic pressure in the master brake cylinder 2 depending on the brake pedal actuation. For this purpose, the brake booster 1 has an actuator 4, which has an electric motor (not shown) as well as a spindle transmission 5, by means of which the torque of the electric motor can be applied as a pushing force to the connection between the brake pedal 3 and the master brake cylinder 2.

The brake booster 1 has a pressure piston 6, one end of which is arranged in correspondence with the master brake cylinder 2 and the other end of which is mechanically connected by a coupling device 14 to a connecting rod 7, which is connected to the brake pedal 3 and is moved by the operation of the brake pedal 3. One end of the pressure piston 6 is arranged in correspondence with an elastically deformable connecting disc 8, which is connected between the pressure piston 6 and another pressure piston 9 acting on the master brake cylinder 2. The connecting disc 8 rests on the end face facing the master brake cylinder 2 of a bracket 10, which is longitudinally slidably supported in a housing 11 of the brake booster 1. Two tensile rods 12, 13 are fixed in the housing 11 and extend parallel to the longitudinal central axis M of the pressure piston 6 and the master brake cylinder 2. The tensile rods 12, 13 connect the brake booster 1 to the master brake cylinder 2. For this purpose, the tension rods 12, 13 are each provided with a thread at their end, which, as shown in FIG. 1, passes through the fixing flange of the master brake cylinder 2 for tightening a fixing nut on the side opposite the brake booster 1. The tension rods 12, 13 ensure that the actuating forces generated by the brake booster 1 during operation of the brake booster 1 are transmitted to the master brake piston or hydraulic pistons 16, 17, which are slidably supported in the master brake cylinder 2 in this embodiment. The hydraulic pistons 16, 17 are arranged next to each other in the master brake cylinder 2 in the actuating direction, so that the master brake cylinder 2 constitutes a so-called tandem master brake cylinder.

The bracket 10 and the connecting disk 8 are each part of a suitable connecting device 14. The connecting device 14 further comprises a transmission member 15 which is located between the pressure piston 6 and the connecting member 8 and is configured generally U-shaped in longitudinal section and which grips the peripheral wall of one end section of the pressure piston 6 on the edge side.

The bracket is essentially V- or U-shaped, and the transmission member 15 supporting the connecting disc 8 protrudes from the bottom section 19 of the bracket 10 in the axial direction towards the master brake cylinder 2. In a preferred form, the transmission member 15 is formed by a separate member from the bracket 10, which is fixed, in particular clip-connected, to the bracket 10 or to the V- or U-shaped bracket base of the bracket 10. Alternatively, the transmission member 15 is formed integrally with the bracket 10 or its base. The pressure piston 6 engages in the opening 20 of the transmission member 15, in particular via a separate damping member, as shown in FIG. 1, so that when the brake pedal 3 is operated, pressure can be applied manually by the pressure piston 6 to the connecting member 8, the further pressure piston 9 and the master brake cylinder 7.

The spindle 21 of the actuator 4 is arranged coaxially to the pressure piston 6, in which the pressure piston 6, which is configured as a sleeve, is supported so as to be able to slide longitudinally or axially. The spindle 21 is operatively connected to the spindle nut 22. The spindle 21 is arranged in the housing 11 so as not to rotate relative to it, whereas the spindle nut 22 is rotatable and is therefore arranged axially immovable in the housing. An electric motor is connected to the spindle nut 22 to drive it, so that when the spindle nut 22 is rotated, the spindle 21 is axially slidable.

The spindle nut 22 has a radially projecting flange 23 at its free end facing the master brake cylinder 2, which flange 23 is arranged at its end face in correspondence with the bottom section 19 of the bracket 10. When the motor is driven and the spindle 21 is slid, the bracket 10, which is firmly connected to the spindle 21 and is in particular welded, is slid together with the spindle 21 in the direction towards the master brake cylinder 2, as long as the bracket 10 and the spindle 21 are in axial contact with each other. This makes it possible to obtain a braking force generation without depending on the brake pedal operation, for example, by a braking force request made by the driving system of the vehicle and not by the driver.

A linking member 24 is fixed to the end of the pressure piston 6 facing the master brake cylinder 2 or to the end facing the connecting disc 8. According to the present embodiment, the linking member 24 is configured as a linking disc that is fitted onto the end of the pressure piston 6, in particular fixed to the pressure piston 6. The linking member 24 supports two, three or more spacer holders 25 that extend in a direction toward the flange 23 of the spindle nut 22. For this purpose, the bottom section 19 of the bracket 10 fixed to the spindle 21 has a recess for each spacer holder 25, through which the spacer holders 25 are engaged in the non-operating position shown in FIG. 1, whereby the spacer holders 25 rest on the end faces of the radial projections 23, the linking member 24 being spaced axially from the bottom section 19 of the bracket 10.

The transmission member 15, which forms section 18 of bracket 10 and against which the connecting disc 8 abuts, is spaced axially from the bottom section 19 of bracket 10 to such an extent that the interlocking member 24 has axial play between the two sections 18, 19.

When the brake pedal is operated, the pressure piston 6 causes the coupling disc 8 and the further pressure piston 9 to slide in the axial direction. When the actuator 4 is driven to amplify the brake force, the bracket 10 is likewise moved by the spindle 21 against the force of the return spring 41 following the sliding of the actuator 4, particularly with a time lag. As a result, the spacer holder 25, which is moved together with the interlocking member 24, is likewise kept spaced axially from the end face of the radial projection 23. When the driver releases his foot from the brake pedal, the brake pedal is pushed back by the return spring 26, which causes the interlocking member 24 to move in the direction toward the bottom section 19 of the bracket 10.

In order to prevent the spindle 21 from rotating and sliding axially when a torque is applied to the spindle nut 23, a rotation prevention means 27 is correspondingly arranged on the spindle. In a conventional brake booster, the rotation prevention means 27 is formed by the bracket 10 being supported at its free end in an axially sliding manner on the tensile rods 12, 13 without radial play, so that a torque is introduced into the tensile rods 12, 13, which prevents the spindle 21 from rotating.

In contrast, according to the preferred configuration of the brake booster 1 shown here, it is provided that the anti-rotation means 27 is formed directly between the bracket 10 and the housing 11 or housing part 11. For this purpose, the housing 11 has two lateral recesses 39, 40, which also protrude into the interior space of the housing 11 in the direction towards the tensile rods 12, 13. The recesses 39, 40 are therefore formed diametrically opposite one another in the housing 11.

At its free ends 28, 29, the bracket 10 has lateral projections 30, 31 in the form of tongues, respectively. These projections 30, 31 each have an opening 32, 33 through which the respective tensile rods 12, 13 are guided.

2 further shows an enlarged detail of the brake booster 1 in the region of the tensile rod 12 and the projection 30 in a schematic cross-sectional view along the line A-A in FIG. 1. The opening 32 has such a cross-section that it is ensured that there is a relatively large radial play (relative to the tensile rod 12) between the projection 30 and the tensile rod 12, so that the projection 30 can be pivoted around the central axis M regionally independent of the tensile rod 12. The projection 30 forms a rotation stop 34 at its free end located on the outside, which is arranged in correspondence with a recess 39 in the housing 11. The recess 39 protrudes into the movement path of the projection 30 so that, when driving the spindle to operate the master brake cylinder 2, the projection 30 hits the peripheral wall of the housing 11 in the region of the recess 39. The recess 39 thereby forms a rotation counterstop 35 for the rotation stop 34. When the actuator 4 is driven to operate the master brake cylinder 2, the rotation stopper 34 hits the rotation counter stopper 35 of the housing 11, thereby preventing the bracket 10 from rotating in a form-locking manner.

The protrusion 31 is formed similarly to the protrusion 30 to form a rotational stop 34 that cooperates with the rotational counter stop 35 formed by the recess 17.

This ensures a reliable and stable anti-rotation protection for the brake booster 1 or for the spindle 21 of the brake booster 1.

According to another embodiment, the projections 30 and 31 are arranged offset relative to the tensile rods 12, 13 in the direction of rotation, so that it is possible to dispense with forming the openings 32, 33 in the projections 30, 31. Instead, the projections 30, 31 are located at a distance from the tensile rods 12 or 13 as a whole for this purpose. For this purpose, a region of the projection 30 is shown in FIG. 2, for example, by dashed lines 36, which can be provided as an alternative configuration of the projection 30 and which can also be arranged at a further distance from the tensile rod 12, especially in an angular position, in order to cooperate there with correspondingly formed recesses 16, 17 or corresponding rotational counter stops 35.

By moving the projections 30, 31 away from the tensile rods 12, 13, the degree of freedom in the configuration when assembling the brake booster 1 can be increased, and this increased degree of freedom in the configuration allows for improved utilization of the mounting space.

In order to reduce wear that occurs when the bracket 10 is moved axially and the rotation stop 34 is axially slid along the rotation counter stop 35, the bracket 10 has a wear protection layer 37 on the projections 30, 31, in particular at least in the region of each rotation stop 34, which is formed, for example, as a plastic covering 38 that at least partially, optionally completely, surrounds the projection 30 to form a contact surface with the housing 11.

REFERENCE SIGNS LIST 1 brake booster 2 master brake cylinder 3 brake pedal 4 actuator 5 spindle transmission 6 pressure piston 7 connecting rod 8 connecting disc, connecting member 9 further pressure piston 10 bracket 11 housing, housing part 12, 13 tension rod 14 connecting device 15 transmission member 16, 17 master brake piston or hydraulic piston 18 section 19 bottom section 20 opening 21 spindle 22 spindle nut 23 flange, radial projection 24 interlocking member 25 spacer holder 26 return spring 27 anti-rotation means 30, 31 projection 32, 33 opening 34 rotation stop 35 rotation counter stop 36 dashed line 37 wear protection layer 38 plastic coating 39, 40 recess 41 return spring M longitudinal central axis, central axis

Claims (8)

The electromechanical brake booster (1) for a vehicle includes a spindle nut (22) that meshes with and moves with a spindle (21) that is slidably supported in an axial direction, an actuator (4) for rotating the spindle nut (22) to slide the spindle (21) in an operating direction, and a pressure piston (9) that can be slid by the spindle (21) in the operating direction, the pressure piston (9) having one end that can be connected to a master brake cylinder (2) and the other end that can be connected to a connecting rod (14) that is operatively connected to the spindle (21) and can be connected to a brake pedal. a brake booster (1) operatively connected to a spindle (6) and further comprising at least one preloaded return spring (26) acting against the actuation direction, a single, in particular multi-part, housing (11) accommodating at least the pressure piston (9), the coupling device (14) and the return spring (26), at least one tension rod (12, 13) fixed to the housing (11) and extending through the housing (11) parallel to the spindle (21), and anti-rotation means (27) for the spindle (21),
the anti-rotation means (27) has at least one rotation stop (34) rigidly connected to the spindle (21) and at least one rotation counter stop (35) formed by the housing (11), and the anti-rotation means ( 27 ) at least limits the rotation of the spindle (21) within the housing (11) ;
the coupling device (14) or the spindle (21) has at least one lateral projection (30, 31) forming the rotation stop (34),
The electromechanical brake booster (1), characterized in that the projections (30, 31) have openings (32, 33) through which the tensile rods (12, 13) extend at a distance from the projections (30, 31) . The electromechanical brake booster (1) for a vehicle includes a spindle nut (22) that meshes with and moves with a spindle (21) that is slidably supported in an axial direction, an actuator (4) for rotating the spindle nut (22) to slide the spindle (21) in an operating direction, and a pressure piston (9) that can be slid by the spindle (21) in the operating direction, the pressure piston (9) having one end that can be connected to a master brake cylinder (2) and the other end that can be connected to a connecting rod (14) that is operatively connected to the spindle (21) and can be connected to a brake pedal. a brake booster (1) operatively connected to a spindle (6) and further comprising at least one preloaded return spring (26) acting against the actuation direction, a single, in particular multi-part, housing (11) accommodating at least the pressure piston (9), the coupling device (14) and the return spring (26), at least one tension rod (12, 13) fixed to the housing (11) and extending through the housing (11) parallel to the spindle (21), and anti-rotation means (27) for the spindle (21),
the anti-rotation means (27) has at least one rotation stop (34) rigidly connected to the spindle (21) and at least one rotation counter stop (35) formed by the housing (11), and the anti-rotation means (27) at least limits the rotation of the spindle (21) within the housing (11);
Electromechanical brake booster (1) , characterized in that the rotational stop (35) of the housing is formed by the contour of the peripheral wall of the housing (11) . The electromechanical brake booster (1) for a vehicle includes a spindle nut (22) that meshes with and moves with a spindle (21) that is slidably supported in an axial direction, an actuator (4) for rotating the spindle nut (22) to slide the spindle (21) in an operating direction, and a pressure piston (9) that can be slid by the spindle (21) in the operating direction, the pressure piston (9) having one end that can be connected to a master brake cylinder (2) and the other end that can be connected to a connecting rod (14) that is operatively connected to the spindle (21) and can be connected to a brake pedal. a brake booster (1) operatively connected to a spindle (6) and further comprising at least one preloaded return spring (26) acting against the actuation direction, a single, in particular multi-part, housing (11) accommodating at least the pressure piston (9), the coupling device (14) and the return spring (26), at least one tension rod (12, 13) fixed to the housing (11) and extending through the housing (11) parallel to the spindle (21), and anti-rotation means (27) for the spindle (21),
the anti-rotation means (27) has at least one rotation stop (34) rigidly connected to the spindle (21) and at least one rotation counter stop (35) formed by the housing (11), and the anti-rotation means (27) at least limits the rotation of the spindle (21) within the housing (11);
the coupling device (14) or the spindle (21) has at least one lateral projection (30, 31) forming the rotation stop (34),
Electromechanical brake booster (1), characterized in that the coupling device (14) comprises a bracket (10), in particular a metal bracket, fixed to the spindle (21), which extends in a transverse direction generally perpendicular to the longitudinal direction of the spindle (21) and which has the projections (30, 31) at least at one end . 4. Brake booster according to claim 1, characterized in that the rotational stop (35) is located in the direction of rotation between the tension rod (12, 13) and the rotational stop (34) . 5. The brake booster according to claim 1, wherein the anti-rotation means (27) comprises at least two rotation stops (34) and two counter-rotation stops (35), each arranged diametrically opposite one another . 6. Brake booster according to claim 1, characterized in that the housing (11) is arranged with two tension rods (12, 13) which extend through the housing (11) . 7. Brake booster according to claim 1, characterized in that each of said tension rods (12, 13) is threadably connectable at one end to said master brake cylinder (2) . 8. Brake booster according to claim 1, characterized in that the rotary stop (34) has a wear protection layer, in particular a plastic coating or a plastic covering (38).

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