Electromechanical brake booster

Abstract

To inhibit noise from occurring when a driver pulls its foot away from a brake pedal or the foot slips from the brake pedal.SOLUTION: At least one spacer holder (25) which engages with an arch-shaped portion in a penetrating manner contacts with an end surface of a spindle nut (22) so that a linkage member (24) is located spaced apart from the arch-shaped part (10). Further, in an operation position, the linkage member (24) is located spaced apart from the arch-shaped portion by sliding of a pressure piston (6) relative to a spindle (21) and spaced apart from the end surface by the at least one spacer holder.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an electromechanical brake booster for a vehicle, comprising a housing, a rotatably supported spindle nut operatively connected to an axially slidable spindle, an electric motor for driving the spindle nut in rotation to slide the spindle, two tie rods fixed to the housing and extending parallel to the spindle, an arched portion fixed to the spindle and bearing-mounted in the tie rods, and a pressure piston extending through the spindle and slidable relative to the spindle, the pressure piston being connectable at a first end to a brake pedal and at a second end to a master cylinder. a pressure piston connectable to a starter brake cylinder and having a return spring associated with it, the pressure piston supporting at its second end an interlocking member which engages at the rear of the arched portion and abuts against the end face of the spindle nut by at least one spacer holder which penetrates the arched portion so that in the inoperative position the interlocking member is spaced from the arched portion, and in the operative position the interlocking member is spaced from the arched portion by sliding of the pressure piston relative to the spindle and is spaced from the end face by at least one spacer holder.

[0002] The present invention further relates to a vehicle, particularly an automobile, equipped with a brake booster constructed as described above. [Background technology]

[0003] Electromechanical brake boosters of the type mentioned above are already known in the prior art. For example, Patent Document 1 discloses a brake booster described in the generic part. When the driver of a vehicle operates the brake pedal during driving, the pressure piston slides axially relative to the spindle, thereby directly mechanically operating the master brake cylinder. This increases the gap between the linkage member and the arched portion. To achieve the brake force boost, an electric motor is controlled, which subsequently drives the spindle nut to axially slide the spindle and the arched portion fixed to the spindle. As a result, the spindle performs its mechanical operation with a time delay, so that a gap between the linkage member and the spindle with the arched portion, as well as a gap between the spacer holder and the spindle nut, is at least temporarily created. In this case, when the driver releases his / her foot from the brake pedal or his / her foot slides off the brake pedal, a return spring associated with the pressure piston moves the pressure piston back against the spindle movement to force the pressure piston to its initial position. This causes the linking member to butt up against the arched portion, which on the one hand causes loads on the arched portion and the linking member, and on the other hand can cause undesirable noise emissions. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] German Patent Application Publication No. 102015217528 Summary of the Invention [Effects of the Invention]

[0005] The brake booster according to the invention, having the features of claim 1, has the advantage that in such cases, the collision between the linkage member and the arched portion is damped so that, on the one hand, the collision does not cause damage to the arched portion and / or the linkage member, and, on the other hand, collision noise is reduced or avoided, thereby ensuring more comfortable conditions for the brake booster or vehicle user. For example, the advantage of reduced collision noise is also shown when an automated braking request is made, such as from an autonomous driving system of a motor vehicle, and the arched portion is moved by the spindle in a direction toward the linkage member that is no longer moved or operated by the brake pedal, until the arched portion strikes the linkage member. For this purpose, the invention provides for at least one elastomeric element to be arranged on the side of the linkage member facing the arched portion, protruding axially toward the arched portion. Thus, the elastomeric element located between the linkage member and the arched portion damps the collision of the linkage member with the arched portion or the collision of the arched portion with the linkage member, thereby advantageously reducing the kinetic energy of the collision. Optionally, the elastomer element is arranged on the side of the arched portion facing the linkage member, and this elastomer element projects axially toward the linkage member, thereby again achieving the aforementioned advantages. A preferred configuration of the brake booster also avoids or reduces pedal vibrations, since the mutual impact between the arched portion and the linkage member is damped by the elastomer element. If the linkage member has, for example, a measurement value transmitter associated with a measurement value sensor or receiver on the housing side, a preferred configuration prevents the measurement value receiver from detecting false signals due to pedal vibrations and thus vibrations of the linkage member without the brake pedal being actuated.

[0006] According to a preferred embodiment of the invention, at least two, more preferably two or more, elastomeric elements are arranged on the linking element or arched portion, protruding axially toward the arched portion or linking element. According to another embodiment of the invention, only one elastomeric element is arranged on the linking element, for example, extending over the surface of the linking element facing the arched portion or over the surface of the arched portion facing the linking element. For this purpose, the elastomeric element is, for example, injection-molded onto the linking element or arched portion, with the linking element being particularly preferably injection-molded or surrounded or at least regionally surrounded by the elastomeric element.

[0007] It is further preferred that the interlocking member or the arched portion have a respective receiving recess for the respective elastomeric element. The elastomeric element is thus arranged in the receiving recess of the arched portion or interlocking member, so that the elastomeric element is fixed to the respective member, particularly non-releasably, thereby ensuring that the elastomeric element remains securely in place even under higher impact forces. Furthermore, arranging the respective elastomeric element in the receiving recess has the advantage that the inner diameter or inner cross section of the receiving recess preferably defines a radial escape space for the elastomeric element, thereby favorably influencing the stiffness of the elastomeric element under load. It is particularly preferred that each receiving recess is designed as an opening, so that it extends completely through the interlocking member, thereby forming a through-opening or said opening. According to an alternative embodiment, the receiving recess is designed as a blind hole, which has the advantage that the elastomeric element can escape axially under load, thereby favorably adjusting the operating characteristic curve, particularly the damping characteristic curve, of the elastomeric element.

[0008] Particularly preferably, each receiving recess has an undercut for locking the respective elastomeric element therein, which can be rear-locked by the elastomeric element. When the elastomeric element is assembled into the receiving recess, its elastic deformation pushes it past the locking position for rear-locking into the undercut, and when it reaches the undercut, the inherent elasticity of the elastomeric element causes it to return to its initial shape, thereby locking it rearward in a manner suitable for the undercut. In particular, each elastomeric element locks axially from the rear into the correspondingly arranged undercut, ensuring a non-releasable positioning of the elastomeric element in the interlocking member or arched portion. The preferred configuration also ensures easy assembly of the elastomeric element in the interlocking member or arched portion.

[0009] More preferably, each elastomeric element has a contact end protruding from the linking member or arch portion and a locking end that locks into the receiving recess, the locking end having a radially protruding flange for rearward locking into the undercut. Each elastomeric element therefore has a section provided for axial locking, which section is configured as a radially protruding flange, so that secure axial locking in the arch portion or linking member is guaranteed even in the stress-relieved state of the elastomeric element. Due to the elastic deformation of the locking end or flange of the linking member, the linking member can be assembled and disassembled inexpensively and simply.

[0010] Furthermore, an axial recess for material reduction is preferably formed in the elastomeric element at the end face of the locking end, particularly at least at the level of the flange. By material reduction, the locking end, particularly in the region of the flange, can be deformed with little energy consumption, thereby bringing the elastomeric element into a rear-locking position in the undercut with little energy consumption. Furthermore, this preferred configuration of the elastomeric element facilitates demolding of the elastomeric element from a tool in which it is produced, for example, by injection molding. The subsequent positive-locking axial fixation of the elastomeric element in the interlocking member or arched section reliably ensures a permanent positioning of the elastomeric element in the interlocking member or arched section.

[0011] Preferably, the axial recess is formed as a groove extending over the entire width of the elastomeric element or as a cup-shaped recess. In both cases, a suitable material reduction is achieved, which ensures the above-mentioned advantages. Both grooves and cup-shaped recesses can be manufactured inexpensively, and since the cup-shaped recess results in a relatively large loss of stiffness in the area of ​​the flange, it is preferable to select a groove or a cup-shaped recess depending on the expected loads.

[0012] The elastomer element is particularly preferably configured as a body of revolution, which allows it to be produced inexpensively and in a large number of parts, with the further advantage that mounting errors are eliminated.

[0013] It is furthermore preferred that the contact end has an axial stop for abutting against the end face of the linking element or the arched portion facing the arched portion or linking element. Such an axial stop ensures that the elastomeric element is not pushed completely through the receiving recess, in particular when the linking element and the arched portion are not in contact with each other. In particular, the maximum outer diameter of the axial stop is greater than the maximum inner diameter of the receiving recess, and the flange preferably has a radius or diameter that is at least greater than the inner diameter of the undercut, so that the elastomeric element is permanently and irreleasably held in the receiving recess.

[0014] According to a preferred development of the invention, at least one spacer holder has a lateral protrusion for abutting against the arched portion, in particular the bottom section of the arched portion, and the lateral protrusion, the return spring and the elastomer element are configured in such a way that the lateral protrusion of the at least one spacer holder is moved by the return spring until it abuts against the arched portion due to elastic deformation of the elastomer element after brake pedal actuation has ended, i.e. when the user no longer operates the brake pedal or no longer applies force to the brake pedal, in particular when the arched portion has been axially slid far enough that the at least one stop element no longer abuts against the spindle nut.

[0015] A vehicle according to the invention having the features of claim 11 is characterized by an electromechanical brake booster constructed according to the invention, which provides the advantages already mentioned above. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic longitudinal cross-sectional view of a preferred electromechanical brake booster; [Figure 2] FIG. 2 is an enlarged perspective view showing details of the brake booster. [Figure 3] FIG. 3 is a cross-sectional view of the device shown in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0017] Further advantages and preferred features and feature combinations emerge particularly from the description and claims.The invention will be explained in more detail below with reference to the drawings.

[0018] 1 shows a schematic longitudinal section of a preferred 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). The brake booster 1 is used to adjust the hydraulic pressure in the master brake cylinder 2 depending on the brake pedal operation. For this purpose, the brake booster 1 has an actuator 4, which has an electric motor (not shown) and 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.

[0019] 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 to a connecting rod 7, 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 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 an arched section 10, which is mounted so as to be longitudinally movable in a housing 11 of the brake booster 1. For this purpose, two tie 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 arched portion 10 has a receiving opening 14, 15 at each end corresponding to the tie rod 12, 13, in which a plain bearing 16, 17 is formed for the respective tie rod 12, 13. The plain bearings 16, 17 are located at an axial height that roughly corresponds to the height of the end face against which the connecting disc 8 abuts. The arched portion is essentially V- or U-shaped, with a section 18 of the arched portion 10 that supports the connecting disc 8 projecting axially from a bottom section 19 of the arched portion 10 toward the master brake cylinder 2. Preferably, the section 18 is formed by a component separate from the arched portion 10, which is fixed to the arched portion 10 or to a base body of the V- or U-shaped arched portion 10, in particular by clip connection to the base body. Alternatively, the section 18 is integral with the arched portion 10 or its base body. As shown in particular in FIG. 1 , the pressure piston 6 is adapted to be engaged through an opening 20 in the section 18 via another pressing member, so that when the brake pedal 3 is operated, the pressure of the pressure piston 6 can be manually applied to the connecting member 8, the other pressure piston 9 and the master brake cylinder 7.

[0020] A spindle 21 of the actuator 4 is arranged coaxially with the pressure piston 6, the pressure piston 6 being mounted in the sleeve-like spindle 21 so as to be longitudinally or axially movable. The spindle is operatively connected to a 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 axially fixedly arranged 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 moved axially.

[0021] The spindle nut 22 has a radially protruding flange 23 at its free end facing the master brake cylinder 2, with its end face arranged to correspond to the bottom section 19 of the arched portion 10. When the electric motor is controlled to move the spindle 21, the spindle 21 moves the arched portion 10, which is fixed to the spindle 21, in particular welded to it, in the direction towards the master brake cylinder 2, as long as the arched portion 10 and the spindle 21 are in axial contact with each other. This allows braking force to be generated without relying on brake pedal operation, for example, by a brake force request made by the vehicle's driving system rather than by the driver.

[0022] A link element 24 is fastened to the end of the pressure piston 6 facing the master brake cylinder 2 or the end facing the connecting disc 8. In the illustrated embodiment, the link element 24 is configured as a link disc that is fitted over the end of the pressure piston 6 and is fastened to this end. The link element 24 supports two, three or more spacer holders 25, which extend toward the flange 23 of the spindle nut 22. For this purpose, the bottom section 19 of the arched portion 10, which is fastened to the spindle 21, has a recess for each spacer holder 25, through which the spacer holders 25 are engaged in the inoperative position shown in FIG. 1 , so that the spacer holders 25 rest against the end faces of the radial projections 23, the link element 24 being spaced axially apart from the bottom section 19 of the arched portion 10.

[0023] The section 18 against which the connecting disc 8 abuts is spaced axially widely from the bottom section 19 of the arched portion 10 so that the interlocking member 24 has axial play between the two sections 18 and 19 .

[0024] When the brake pedal is operated, the pressure piston 6 moves the connecting disc 8 and the further pressure piston 9 in the axial direction. For braking force amplification, the actuator 4 is controlled so that the arched portion 10, which is moved by the spindle 21, follows the movement of the actuator 4, particularly with a time lag. This ensures that the spacer holder 25, which is moved together with the linkage member 24, is likewise spaced axially from the end face of the radial projection 23. When the driver simply releases his foot from the brake pedal, the brake pedal is pulled back by the return spring 26, so that the linkage member 24 moves in the direction towards the bottom section 19 of the arched portion 10. In order to minimize the impact of a collision of the interlocking member 8 on the bottom section 19 of the arched portion 10 or vice versa, according to the embodiment described herein, a plurality of elastomeric elements 27 are arranged, which protrude in a direction towards the bottom section 19 of the arched portion 10 and are disposed in correspondence with this bottom section 19 such that the elastomeric elements 27 are located between the interlocking member 24 and the bottom section 19 to cushion the impact.

[0025] 2 shows an enlarged perspective view of the link element 24, which according to the embodiment shown has a cross-shaped cross section, with one spacer holder 25 arranged on each of the four arms 28, 29, 30, 31. Optionally, one further measurement value transmitter 32 is arranged on one of the arms 31, which cooperates with a measurement value sensor arranged fixedly on the housing in order to monitor the position of the link element 24 during operation.

[0026] The elastomeric elements 27 are spaced apart relative to the linking member 24 in the exploded view in the embodiment of Figure 2. Here, there are exactly two elastomeric elements 27 arranged diametrically opposite each other on the arms 28 and 30.

[0027] Figure 3 shows a cross-section of the device shown in Figure 2 along the section line AA indicated in Figure 2. The elastomeric element 27 is made of an elastically deformable material and is a rotary body. It has a contact end 33 facing the spindle drive and a locking end 34 corresponding to the linkage member 24. At its free end, the locking end 34 has a radially protruding flange 35 that serves to axially lock into an undercut 36 of a receiving recess 37 of the linkage member 24 from the rear. For this purpose, the receiving recess 37 has a tapered portion 38, which defines the undercut 36 on the side of the receiving recess 37 opposite the bottom section 19. The contact end 33 also has an axial stop 42 that rests on the end face of the linkage member 24 facing the bottom section 19. The distance of the axial stop 42 from the flange 35 corresponds approximately to the axial extension of the tapered portion 38. The elastomeric element 33 is thereby held axially in the linking element 24 by the axial stop 42 on the one hand and by the flange 35 on the other hand. For assembly, the elastomeric element 27 with the flange 35 is first pressed into the receiving recess 37, during which the elastic deformation of the flange 35 causes it to slide past the tapered section 38 until, due to its inherent elasticity, it radially expands again after passing over the tapered section 38 and thereby locks from the rear into the undercut 36. This ensures easy assembly of the elastomeric element 27 in the linking element 24.

[0028] In a preferred form, the elastomeric element 27 has an axial recess 39 formed in its free end face at the locking end 34 with its flange 35, which axial recess 39 is used to reduce the material of the locking end 34 in the area of ​​the flange 35 so that the flange 35 can be easily deformed when inserted into the receiving recess 34.

[0029] 2, in a preferred manner, exactly two elastomeric elements 27 are held on the linking member 24. Optionally, more than two, in particular three or four, elastomeric elements 27 are provided, so that the elastomeric elements 27 ensure a particularly stable abutment of the linking member 24 on the bottom section 19.

[0030] As an alternative to the embodiment shown, the elastomeric element 27 is not fixed to the interlocking member 24 but to the bottom section 19 of the arched portion 10. According to another embodiment, corresponding elastomeric elements 27 are fixed both to the interlocking member 24 and to the bottom section 19 of the arched portion 10.

[0031] 2 and 3, the two spacer holders 25 have lateral projections 40 that project axially from the interlocking member 24 and define stop surfaces 41, up to which the interlocking member 24 can move onto the bottom section 19 of the arched portion. The spacer holders 25 thus define, by means of their respective projections 40, a single spacer holder that limits the maximum deformation of the elastomeric element 27 between the bottom section 19 of the arched portion 10 and the interlocking member 24. For this purpose, the projections 40 project out of the openings 26 into which the spacer holders 25 would otherwise extend, thereby projecting laterally to such an extent that they can abut against the bottom section 19. The projection 40, the return spring 26 and the elastomeric element 27 are adapted to one another, particularly with regard to their size, elasticity and deformability, in such a way that when the stop element 25 cannot abut against the flange 23 of the spindle nut 22, the linking member 24 is moved by the return spring 26 to a great extent in the direction towards the bottom section 19, so that the elastomeric element 27 is deformed to a great extent until the linking member 24 abuts against the bottom section 19 with the projection 40 of the stop surface 41. The return spring 26 therefore moves the linking member towards the bottom section 19 based on the maximum deformation of the elastomeric element 27. This is the case, for example, when the driver releases his foot from the brake pedal after braking and the arched portion 10 has already been moved by the spindle 21 in the direction towards the master brake cylinder 2.

[0032] 2 and 3, the projections 40 are arranged radially outward of the spacer holder 25, whereas in an alternative embodiment, the projections 40 are provided to be configured to project radially inwardly, i.e., towards the opposite inner sides of the spacer holder 25. This is shown, for example, in FIG. [Explanation of symbols]

[0033] 1 Brake booster 2 Master brake cylinder 3. Brake pedal 4 Actuators 5 Spindle transmission 6 Pressure Piston 7 Connecting rod 8 Connecting disc, connecting member 9 Different Pressure Pistons 10 Arched section 11. Housing 12,13 Tie rod 14,15 Receptacle opening 16,17 Plain bearings 18 arched sections 10 segments 19 bottom section of arched portion 10 21 Spindle 22 Spindle nut 23 Flange, protrusion 24 Interlocking members 25 Spacer holder, stopper element 26 Return spring 27 Elastomer element 28, 29, 30, 31 Arms 32 Measurement value transmitter 33 Contact end, elastomer element 34 Locking end 35 flange 36 Undercut, notch 37 Receiving recess 38 Tapered section 39 Axial recess 40 Lateral protrusion 41 Stopper surface 42 Axial stopper AA cutting line M Vertical center axis

Claims

1. An electromechanical brake booster (1) for a vehicle, comprising: a housing (11); a spindle nut (22) operatively connected to an axially slidably supported spindle (21); an electric motor for driving the spindle nut (22) in rotation to slide the spindle (21); two tie rods (12, 13) fixed to the housing (11) and extending parallel to the spindle (21); an arch-shaped portion (10) fixed to the spindle (21) and plain-bearing in the tie rods (12, 13); and a pressure piston (6) extending through the spindle (21) and slidable relative to the spindle (21), the pressure piston being connectable at a first end to a brake pedal and at a second end to a master brake. a pressure piston (6) connectable to a pressure cylinder (2), a return spring (26) is associated with the pressure piston (6), the pressure piston (6) supports at its second end an interlocking member (24) which engages behind the arcuate portion (10) and abuts against an end face of the spindle nut (22) by at least one spacer holder (25) which penetrates the arcuate portion (10) so that the interlocking member (24) is spaced from the arcuate portion (10) in an inoperative position, and is spaced from the arcuate portion (10) by sliding of the pressure piston (6) relative to the spindle (21) and is spaced from the end face by at least one spacer holder (25), 1. An electromechanical brake booster, characterized in that at least one elastomer element (27) is arranged on the side of the linking member (24) facing the arched portion (10) and projects axially towards the arched portion (10) and / or at least one elastomer element (27) is arranged on the end face of the arched portion (10) facing the linking member (24) and projects axially towards the linking member (24).

2. 2. An electromechanical brake booster according to claim 1, characterized in that at least two, in particular two or more, elastomer elements (27) are arranged on the linking member (24) or on the arched portion (10), which project axially towards the arched portion (10) or the linking member (24).

3. 3. An electromechanical brake booster according to claim 1 or 2, characterized in that the linking member (24) or the arched portion (10) has a receiving recess (37) for each of the elastomeric elements (27) to fix each of the elastomeric elements (27).

4. 4. An electromechanical brake booster according to claim 3, characterized in that the receiving recess (37) has an undercut (36) for locking each of the elastomer elements (27) and which can be locked from the rear by the elastomer elements (27).

5. 5. An electromechanical brake booster according to claim 4, characterized in that each of the elastomeric elements (27) has a contact end (33) projecting from the interlocking member (24) and a locking end that locks in the receiving recess (37), the locking end (34) having a radially projecting flange (35) for locking from the rear into the undercut (36).

6. 6. An electromechanical brake booster according to claim 5, characterized in that an axial recess (39) for material reduction is formed in the elastomer element (27) on the free end face of the locking end (34), in particular at least at the level of the flange (35).

7. 7. An electromechanical brake booster according to claim 6, characterized in that the axial recess (39) is formed as a groove extending over the entire width of the elastomer element (27) or as a cup-shaped recess.

8. 8. Electromechanical brake booster according to claim 1, characterized in that the elastomer element (27) is designed as a body of revolution.

9. 8. An electromechanical brake booster according to claim 5, wherein the contact end (33) has an axial stop (42) for abutting against an end face of the linking member (24) facing the arched portion (10) or for abutting against an end face of the arched portion (10) facing the linking member (24).

10. 10. An electromechanical brake booster according to claim 1, characterized in that at least one spacer holder (25) has a lateral projection (40) for abutting against the arched portion (10), and the return spring (26) and the elastomeric element (27) are configured in such a way that the lateral projection (40) of the at least one spacer holder (25) can be moved by the return spring (26) after brake pedal actuation has ended, based on elastic deformation of the elastomeric element (27), until it abuts against the arched portion (10).

11. A vehicle equipped with a brake booster device described in any one of claims 1 to 10.

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