Vehicle braking system

Abstract

The invention relates to a vehicle braking system for a vehicle axle of a two-track vehicle, comprising a multi-disk brake or clutch (3) for each side of the vehicle, with an electrically controllable actuator (21) with which a braking function for vehicle braking while driving or a parking function when the vehicle is parked can be engaged / disengaged in the multi-disk brake or clutch (3). According to the invention, the vehicle braking system additionally comprises a parking lock (41), the locking pawl (43) of which can be brought into locking engagement with a locking gear (45). Each of the two actuators (21) is in a driving connection (50) with the locking pawl (43), such that when the parking function is engaged by at least one of the actuators (21), the locking pawl (43) can be adjusted into locking engagement.

Description

[0001] The invention relates to a vehicle braking system according to the preamble of claim 1.

[0002] A generic vehicle braking system has, instead of conventional disc or drum brakes, at least one multi-disk brake acting on the vehicle axle, by means of which a braking function for vehicle braking while driving or a parking function when the vehicle is parked can be engaged or disengaged. For this purpose, the multi-disk brake has two separately operating actuators, namely a brake actuator and a parking actuator, which can be controlled by a control unit using electrical or hydraulic signals. For safety reasons, the brake actuator can be designed to be normally open or non-self-locking, while the parking actuator can be normally closed or self-locking. Installing these two actuators on the multi-disk brake requires additional space and involves additional design effort.

[0003] DE 10 2014 102 831 A1 discloses a parking lock assembly with a pawl and a cooperating locking gear. When the parking function is engaged, the pawl can be brought into locking engagement with a locking gear. EP 3 428 021 A1 discloses another parking lock assembly that can be actuated by an electric motor.

[0004] The object of the invention is to provide a vehicle braking system which can be implemented with reduced installation space and reduced design effort compared to the prior art.

[0005] The object is solved by the features of claim 1. Preferred developments of the invention are disclosed in the subclaims.

[0006] The invention is based on a vehicle braking system having a multi-disk brake or clutch acting on a vehicle axle for each side of the vehicle, by means of which a braking function for vehicle braking while driving and a parking function when the vehicle is parked can be engaged / disengaged. Each of the multi-disk brakes or clutches is assigned precisely one electrically controllable actuator. The actuator can engage / disengage both the braking function and, alternatively, the parking function. This results in a braking concept that is simplified in terms of cost, installation space, and component weight compared to the prior art. For safety reasons, the electrically controllable actuator is de-energized when the braking function is engaged, i.e., not self-locking, whereas it is de-energized when the parking function is engaged.

[0007] According to the characterizing part of claim 1, the vehicle braking system additionally comprises precisely one parking lock, the locking pawl of which can be brought into locking engagement with a locking gear. The locking pawl is in driving connection with each of the two actuators, so that when the parking function is engaged by at least one of the actuators, the locking pawl can be adjusted into locking engagement.

[0008] The drive connection between the two actuators and the pawl is designed in such a way that disengagement of the parking lock, i.e. return of the pawl from its locking position to its release position, only occurs under the condition that both actuators disengage the parking function.

[0009] Conversely, when the parking function is engaged, each of the actuators can engage the multi-plate clutch or brake as well as move the pawl toward its locking position.

[0010] The parking lock can support the parking function engaged by the electrically controllable actuator. According to the invention, the parking function is therefore implemented not only by the electrically controllable actuator, but also by the parking lock. The holding torque requirements for the electrically controllable actuator are therefore reduced compared to a vehicle braking system that does not have a parking lock. Alternatively, the parking function can also be implemented solely by means of the locking pawl.

[0011] In one technical implementation, the actuator can have at least one ball-ramp unit. This allows the multi-disk brake or clutch to be subjected to contact pressure when the brake function or the parking function is engaged. Conversely, the multi-disk brake or clutch can be pressure-relieved when the brake or parking function is disengaged. The ball-ramp unit consists of a pair of discs, consisting of a stationary disc and a coaxially rotating disc. The ball can roll between the discs' facing, inclined brake ball tracks.

[0012] In this case, the braking function can be engaged as follows: An electric rotary drive (i.e., a spindle drive) of the actuator moves the rotating disc from a zero rotation position in a braking direction by a braking angle into a braking setting range. This causes the ball to roll along the braking ball tracks, axially expanding the pair of discs over an axial expansion distance. This applies a contact pressure to the multi-disk brake / clutch. This pressure varies depending on the magnitude of the braking angle.

[0013] When the brake function is engaged, rolling resistance occurs between the ball and the brake ball tracks of the disc pair. This low rolling resistance, compared to a sliding system, means that the ball-ramp unit is not self-locking, meaning it remains open when de-energized. In the event of a power failure, the actuator's braking effect is automatically canceled, thus meeting safety requirements.

[0014] Conversely, the pressure mechanism according to the invention is designed so that when the parking function is engaged, the actuator is self-locking, meaning it remains closed without power. In the event of a power failure, the parking function – unlike the braking function – remains permanently active, ensuring that the parking function also meets safety requirements.

[0015] The braking and parking functions can be implemented as follows: The ball-ramp unit can have corresponding, inclined sliding bevels. These are formed on both discs and can be brought into sliding contact with one another. To engage the parking function, the electric rotary drive (i.e., the spindle drive) of the actuator moves the rotating disc from the zero rotation position in a parking direction opposite to the braking direction, through a parking angle, into a parking setting range. In the parking setting range, the sliding bevels of the two discs come into sliding contact, with the disc pair axially spreading by the axial spreading distance, which exerts contact pressure on the multi-disk brake / clutch.

[0016] When the parking function is engaged, a sliding resistance acts between the corresponding sliding slopes of the discs. This resistance is significantly greater than the rolling resistance between the ball and the brake ball tracks of the disc pair. Therefore, when the parking function is engaged, the ball-ramp unit is designed to be self-locking (unlike the braking function), meaning it remains closed without power. When the parking function is engaged, the braking effect can be maintained despite a power failure.

[0017] To ensure reliable engagement of the parking function, the following measure is preferred: The parking setting range can be divided into a first sub-range and a second sub-range following in the parking direction of rotation. In the first sub-range, the ball can roll between facing parking ball tracks of the disc pair. In contrast, in the second sub-range, the ball is no longer in rolling contact with the disc pair. To engage the parking function, the rotatable disc is adjusted from the zero rotation position in the parking direction by a parking rotation angle into the first sub-range until a transfer point is reached. When adjusted in the first sub-range, the ball rolls on the parking ball tracks of the disc pair. This occurs with axial expansion of the disc pair over an axial expansion path. In this way, any clearance in the multi-disk brake / clutch is eliminated.When the transfer point is exceeded, the rotating disc is adjusted with a further increasing parking angle in the second sub-range until the parking function is engaged.

[0018] During the adjustment process in the first partial range, the sliding slopes of the two discs remain out of contact. Only when the transfer point is exceeded do the two sliding slopes come into sliding contact with each other, while at the same time the ball is no longer in rolling contact with the pair of discs.

[0019] The pitch angle of the two sliding slopes is preferably larger than the pitch angle of the parking ball tracks. This ensures that when the transfer point is exceeded, the ball safely lifts off the parking ball tracks of the pair of discs, meaning that the ball is no longer rolling contact with the parking ball tracks. When the parking function is engaged, this ensures that only the sliding resistance of the corresponding sliding slopes acts between the discs.

[0020] The parking ball tracks and the brake ball tracks can merge into one another at a ramp recess along the disc's circumference. This defines the zero rotation position. The parking ball tracks can be mirror-symmetrical to the brake ball tracks with respect to a symmetry running through the ramp recess. Starting from the zero rotation position, as the braking or parking angle increases, the clearance of the multi-disk brake / clutch is initially eliminated. A kiss point is then reached, at which the multi-disk brake / clutch transmits a measurable or predefined torque. To ensure reliable engagement of the parking function, it is preferable if the transfer point is exceeded in the parking setting range shortly before the kiss point is reached.

[0021] Operational reliability is further increased when the parking function is engaged, ensuring that the ball remains in a predefined free-running position (after lifting off the two parking ball tracks). In the free-running position, the ball can roll between the parking ball tracks of the pair of discs with some play, i.e., without rolling contact.

[0022] The predefined ball freewheel position can be achieved, for example, as follows: Each of the parking ball tracks of the two discs, viewed in the parking direction of rotation, can end at a ball track runout, which forms a ball movement stop. When the parking function is engaged, the two ball track runouts can be spaced apart from each other by a ball freewheel, viewed in the disc's circumferential direction, which defines the ball freewheel position. When the parking function is disengaged, the rotating disc is adjusted counter to the parking direction of rotation until it reaches the zero rotation position.

[0023] By providing the ball freewheel position, it is ensured that the ball comes into rolling contact with the parking ball tracks at least approximately at the transfer point and that the ball is in the ramp recess when the rotational zero position is reached.

[0024] A core of the invention is that the electrically controllable actuator not only controls the pressure mechanism acting on the multi-disk brake or clutch, but also additionally controls the locking pawl of the parking lock between a locking position in which the locking pawl can be brought into locking engagement with the locking gear, and a release position in which the locking pawl is out of locking engagement with the locking gear.

[0025] For simple pawl control, the rotating discs of the two actuators are mechanically connected to the pawl. The drive connection is designed so that when at least one of the rotating discs rotates into the parking range, the pawl is automatically moved into the locked position. Conversely, when the two rotating discs rotate from the parking range to the braking range, the pawl is automatically moved into the released position.

[0026] In a specific embodiment, the vehicle axle can have an axle differential. Its output sides drive to the vehicle wheels via output shafts. A multi-disk brake or clutch is arranged on each output side, acting on the respective output shaft. The locking gear of the parking lock can, for example, be connected in a rotationally fixed manner to a differential housing of the axle differential. In this design, the parking lock is arranged at an axial distance from the respective multi-disk brake or clutch.

[0027] The drive connection formed between the respective rotating disc and the pawl can be implemented in a structurally simple manner as follows: The pawl can be part of a two-armed lever arm pivoting about a pawl rotation axis. This lever arm is seated on a central lever arm shaft, which rotates about a pawl rotation axis and is aligned coaxially with the two parking lock shafts. The lever arm has a first lever arm, which forms the pawl, and a second lever arm opposite the pawl rotation axis, which is coupled to a rocker element with its end face remote from the axis at a force introduction point.

[0028] One of the parking lock shafts is arranged axially on either side of the pawl, aligned coaxially with the central pawl rotation axis. The spatial position of the rotation axes of the parking lock shafts and the pawl rotation axis remains unchanged in all operating states of the parking lock. A control lever and an axially spaced-apart driver lever are non-rotatably connected to each of the parking lock shafts. Each of the two control levers is spring-loaded and in sliding contact with a control contour formed on the rotatable disc. The two driver levers are each connected to a coupling point on the rocker element. Each of the two coupling points is spaced from the central force introduction point of the rocker element by a lever arm length.

[0029] The force application point of the rocker element can be implemented as a pivot point, allowing the rocker element to rotate about a rocker axis of rotation aligned perpendicular to the pawl axis of rotation. Furthermore, the pawl is preloaded toward the locking engagement by a spring element, whereby the two control levers are preloaded toward the control contour by the spring element effect.

[0030] An embodiment of the invention is described below with reference to the attached figures.

[0031] They show: Fig. 1 to 14 different views describing the structure and operation of the vehicle braking system according to the invention.

[0032] In the Fig. 1 shows an electrified vehicle axle with an electric motor EM and a transmission. The electric motor EM is connected to a high-voltage battery (not shown). Conventional vehicle wheel disc or drum brakes are omitted from the vehicle axle. Instead of such conventional vehicle wheel brakes, the vehicle axle has a multi-disk brake 3 on each side of the vehicle, by means of which vehicle braking can be carried out. In addition, the vehicle axle has a Fig. 1 or Fig. 2 not shown parking lock 41, the structure and function of which will be explained later on the basis of the Fig. 9 to 14.

[0033] The electric motor EM is connected via its rotor shaft 5 with the interposition of a reduction gear stage 7 to the input side of an axle differential 9. The output sides of the differential are connected to the vehicle wheels via output shafts 11. Fig. 1, the electric motor EM is installed transversely in the vehicle axle. Accordingly, the rotor shaft 5 and the output shafts 11 are axially parallel to each other. Likewise, the multi-disk brakes 3 installed in the vehicle axle are aligned axially parallel to each other in the vehicle's transverse direction y.

[0034] The vehicle axle has one of the multi-disk brakes 3 on each side of the vehicle, viewed in the vehicle transverse direction y. These can be controlled by an electronic control unit (not shown) in order to perform uniform or uneven vehicle braking on both vehicle wheels.

[0035] The intermediate gear stage 7 is in driving connection with an input-side axle differential gear 13. The axle differential gear 13 is connected in a rotationally fixed manner to a rotating differential housing 15. According to the Fig. 1 drives the axle differential 9 when the multi-disk brakes 3 are open in the vehicle transverse direction y in a 50 / 50 distribution on both sides to the two output shafts 11 leading to the vehicle wheels.

[0036] In the Fig. 1, the two multi-disk brakes 3 each act directly on the output shafts 11. This means that the multi-disk brake 3 is connected to the respective output shaft 11 with its inner disc carrier 18, while the outer disc carrier 17 is fixed to a transmission housing wall 19. The disc pack located between the outer disc carrier 17 and the inner disc carrier 18 can be subjected to contact pressure via an actuator 21. The two actuators 21 can be controlled by the control unit using electrical signals.

[0037] One of the actuators 21 is in the Fig. 2 to 3c. This consists of a spindle drive (not shown) with an electric motor, which is in driving connection with a toothing 31 of a rotatable disc 27. The rotatable disc 27, together with a non-rotatable disc 25, is part of a pressing mechanism. The non-rotatable disc 25 can be supported in the circumferential direction by an indicated torque support 14. In addition, the non-rotatable disc 25 is supported in the axial direction on a counterholder 12. The pressing mechanism has a total of four circumferentially distributed ball-ramp units 23, as can be seen from the Fig. 3a to 3b. Each ball-ramp unit 23 has a ball 29 that rolls between the two discs 25, 27.

[0038] The plate pack located between the outer plate carrier 39 and the inner plate carrier can be subjected to contact pressure by means of the actuator 21. Depending on the control of the actuator 21, a braking function for vehicle braking while driving, or alternatively a parking function when the vehicle is parked, can be engaged or disengaged. A core of the invention is that both the braking function and the parking function can be engaged / disengaged by means of the actuator 21. For safety reasons, the electrically controllable actuator 21 is de-energized when the braking function is engaged, i.e., not self-locking. In contrast, the electrically controllable actuator 21 is de-energized when the parking function is engaged, i.e., self-locking.

[0039] As can be seen from the Fig. 3a to 3c, each of the ball-ramp units 23 has ball ramps 34 and spaced-apart sliding bevels 38 which act between the discs 25, 27. The balls 29 of the four ball-ramp units 23 are arranged according to the Fig. 3b in a cage 30. In the Fig. 4a and Fig. 4b shows one of the ball-ramp units 23 in a developed view. Fig. 4a shows two corresponding sliding slopes 38 of the pair of discs, while Fig. 4b shows two corresponding ball ramps 34 of the disc pair with an intermediate ball 29. Each of the ball ramps 34 consists of a brake ball track 35 and a parking ball track 37, which merge into each other at a ramp recess 39. In the Fig. 4a, the ball 29 is located in the ramp recess 39. The ramp recess 39 defines a zero rotational position 0, in which the pair of discs exerts no contact pressure on the disk pack. The ball ramps 34 of the two discs 25, 27 are point-symmetrical to each other with respect to the ball 29. Furthermore, the parking ball track 37 and the braking ball track 35 of each ball ramp 34 are symmetrical to each other with the same pitch angles with respect to an axis of symmetry passing through the ramp recess 39.

[0040] A core of the invention is that depending on a direction of rotation D B , D PThe rotatable disc 27 can be used to engage / disengage either a braking function for vehicle braking while driving, or alternatively, a parking function when the vehicle is stationary. An important aspect of the invention is that the pair of discs of the actuator 21 is open when de-energized when the braking function is engaged, i.e., is not self-locking. In contrast, the pair of discs of the actuator 21 is closed when de-energized when the parking function is engaged, i.e., is self-locking.

[0041] In the Fig. 4a and Fig. 4b shows the pair of discs in its zero rotation position 0. In the zero rotation position 0 (unlike in the Fig. 4a) the two sliding bevels 38 are out of contact. The ball 29 is located according to the Fig. 4b in the ramp recesses 39 of the ball ramps 34 of the two discs 25, 27.

[0042] The following is based on the Fig. 5a to 6b, the engagement of the brake function is described. Starting from the Fig. 4a and Fig. 4b shown rotation zero position 0, the rotatable disc 27 is rotated in a braking direction D B via a brake rotation angle to the left into a brake setting range S B adjusted. As a result, the ball 29 rolls on the two brake ball tracks 35 of the disc pair, axially spreading the disc pair over an axial spreading distance s. In this way, the disc pack of the multi-disk brake 3 is subjected to contact pressure. The contact pressure varies depending on the size of the brake rotation angle. Immediately after leaving the zero rotation position 0, the rotatable disc 27 is adjusted by an axial spreading distance s, by means of which any clearance in the disc pack is eliminated. Upon further rotational adjustment of the rotatable disc 27 in the brake adjustment range S B becomes a Kisspoint KP ( Fig. 5b) is reached, where the multi-disk brake 3 transmits a measurable, predefined torque. At the kiss point KP, the rotating disc 27 (starting from the zero rotation position 0) is rotated by a first axial spreading distance Δs1. Fig. 6a and Fig. 6b, the rotatable disc 27 is adjusted to an end position in which the rotatable disc 27 is adjusted by a second axial spreading path Δs2.

[0043] When the braking function is engaged, a comparatively low rolling resistance acts between the ball 29 and the brake ball tracks 35 of the disc pair. This low rolling resistance means that the ball-ramp units 23 are not self-locking, i.e., they remain open when de-energized. Accordingly, in the event of a power failure, the braking effect of the actuated actuator 21 would decrease, thus fulfilling safety requirements.

[0044] To disable the braking function, the rotating disc 27 (starting from its end position ( Fig. 6a and Fig. 6b) opposite to the braking direction D B back to the zero position 0 ( Fig. 4a and Fig. 4b) is adjusted.

[0045] During the adjustment movement in the brake adjustment range S B the corresponding, inclined sliding bevels 38 remain out of contact with each other, so that a smooth rotational adjustment of the rotatable disc 27 is ensured.

[0046] Based on the Fig. 7a to 8b, the following describes how to engage the parking function. Starting from the Fig. 4a and Fig. 4b shown rotation zero position 0, the rotating disc 27 is rotated to engage the parking function in a direction opposite to the braking rotation direction D B opposite parking direction of rotation D P via a parking angle into a parking area S P twisted to the right.

[0047] According to the Fig. 7b is the parking area S Pdivided into a first sub-area S P1 and into a second sub-area S P2 . In the first section S P1 The ball 29 rolls between the facing parking ball tracks 37 of the pair of discs, while the corresponding sliding slopes 38 are still out of sliding contact. In contrast, in the second sub-area S P2 the sliding bevels 38 are in sliding contact with each other, while the ball 29 is out of rolling contact with the pair of discs. To engage the parking function, the rotating disc 27 is rotated from the zero position 0 in the parking direction D P by a parking angle into the first sub-area S P1 until a transfer point U is reached, as described in the Fig. 7a and Fig. 7b is indicated. According to the Fig. 7a and Fig. 7b the pair of discs generates a third axial spreading path Δs3 at the transfer point U.

[0048] During the adjustment movement in the first part of the range S P1 the ball 29 rolls on the parking ball tracks 37 of the disc pair, with axial expansion of the disc pair, so that any clearance in the multi-disk brake 3 is eliminated. When the transfer point U is exceeded, the rotating disc 27 is moved into the second sub-area S with a further increasing parking angle of rotation. P2 turned until the parking function is engaged.

[0049] In order to ensure reliable engagement of the parking function, the parking brake in the parking area S PThe transfer point U is positioned between the rotational zero position 0 and the kiss point KP. When the parking function is engaged, the transfer point U is therefore exceeded shortly before the kiss point KP is reached. Upon reaching the kiss point KP, the two corresponding sliding slopes 38 are already in sliding contact with each other, while the ball 29 is out of rolling contact with the two parking ball tracks 37.

[0050] In the Fig. 8a and Fig. 8b, the rotating disc 27 is rotated to its parking end position, in which the parking function is fully engaged. In the engaged parking function, the ball 29 is in a predefined ball freewheel position P ( Fig. 8b). The ball freewheel position P is in the Fig. 8b is defined by means of ball track outlets 41 of the parking ball tracks 37. When the parking function is engaged, the ball track outlets 41 are spaced apart from each other in the disc circumferential direction by a ball freewheel f, in which the ball 29 rolls with play, i.e., without rolling contact, between the parking ball tracks 37 of the disc pair. The contact pressure of the disc pair is therefore generated exclusively by means of the sliding bevels 38 in sliding contact.

[0051] To disable the parking function, the rotating disc 27 is turned against the parking direction D P rotated back to the rotational zero position 0. The retention of the ball 29 in the ball freewheel position P ensures that the ball 29 comes into rolling contact with the parking ball track 37 at least approximately at the transfer point U and is again in the ramp recess 39 when the rotational zero position 0 is reached.

[0052] An essential core of the invention is that the vehicle braking system according to the Fig. 9 to 14 additionally has a parking lock 41, which is constructed from a pawl 43 and a cooperating locking gear 45, which according to the Fig. 9 is connected to the differential housing 15. When the parking function is engaged, the pawl 43 can be brought into locking engagement with the locking gear 45, whereby the parking lock 41 supports the electrically controllable actuators 21 when engaging the parking function.

[0053] The pawl 43 and the actuator 21 are coupled to each other via a drive connection 50. These are constructed as follows: The pawl 43 is part of a two-armed lever arm 61 ( Fig. 10), which sits on a central lever arm shaft that rotates about the pawl rotation axis A1 and is aligned coaxially with the two parking lock shafts 47. The lever arm 61 has a first lever arm, which forms the pawl 43, and a second lever arm 63 opposite it with respect to the pawl rotation axis A1, which is coupled with its end face remote from the axis to a rocker element 67 at a force introduction point 65.

[0054] Axially on both sides of the pawl 43, one of the parking lock shafts 47 is arranged, which is aligned coaxially with the central pawl rotational axis A1. The spatial position of the rotational axes of the parking lock shafts and the pawl rotational axis A1 remains unchanged in all operating states of the parking lock 41. A control lever 49 and an axially spaced-apart driver lever 69 are connected in a rotationally fixed manner to each of the parking lock shafts 47. Each of the two control levers 49 is in sliding contact with a control contour 53 formed on the rotatable disk 27 under spring preload. The two driver levers 69 are each connected to a coupling point 71 on the rocker element 67. Each of the two coupling points 71 is according to Fig. 9 is spaced from the central force introduction point 65 of the rocker element 67 by a lever arm length I1, I2.

[0055] The force introduction point 65 is in the Fig. 10 is realized as a pivot point at which the rocker element 67 rotates around a rocker axis of rotation A2 ( Fig. 10), which is aligned perpendicular to the pawl rotation axis A1. In addition, the pawl 43 is connected to a Fig. 10 only indicated as an arrow) spring element 51 is preloaded in the direction of the locking engagement, whereby the two control levers 49 are preloaded in the direction of the control contour 53 by means of the spring element effect.

[0056] In the Fig. 10 and Fig. 11, the control contour 53 has a recess or a small diameter contour section 55, which merges into a large diameter contour section 59 at a transition flank 57. In the Fig. 11, the control lever 49 is in sliding contact with the large diameter contour section 59, directly adjacent to the transition flank 57. As can be seen from the Fig. 11, each of the balls 29 is in its zero rotation position 0. When the rotating disc 27 rotates into the braking range S B (according to the Fig. 11 a counterclockwise rotation), the control lever 49 remains in sliding contact with the large-diameter contour section 59. Accordingly, the pawl 43 also remains out of locking engagement with the locking gear 45.

[0057] In the Fig. 12 to 14 is the drive connection 50 in a in the Fig. 10 indicated direction B in different operating states. In the Fig. 12, the parking lock 41 is designed. When the parking function is correctly engaged, a synchronous adjustment movement of the two control levers 49 takes place, as shown in the Fig. 14. In this case, the two pivot levers 49 are pivoted into the small-diameter contour sections 55 of the control contour 53 of the rotatable discs 27. The force introduction point 65 is therefore due to the lever arm ratios I1, I2 ( Fig. 9) by a full swivel path h voll adjusted upwards. Accordingly, the pawl 43 comes into complete tooth engagement Z voll with the locking gear 45.

[0058] In the Fig. 13, an incorrect engagement of the parking function is indicated, in which only the left control lever 49 is pivoted into the small-diameter contour section 55 of the control contour 53 of the rotatable disc 27, while the right control lever 49 incorrectly remains unchanged in contact with the large-diameter contour section 59 of the control contour 53 of the rotatable disc 27. In this case, the force introduction point 65 (starting from the designed state according to Fig. 12) due to the lever arm ratios I1, I2 only by a reduced swivel path h red adjusted upwards. The reduced swivel range h red However, it is still dimensioned so large that the pawl 43 in partial tooth overlap Z red with the locking gear 45. The parking lock function can therefore also be engaged with only one functional control lever 49.

[0059] If the parking function is correctly configured, a synchronous adjustment movement of the two control levers 49 also occurs. The force introduction point 65 is therefore moved by the full swivel path h voll reset. As a result, the pawl 43 is completely out of tooth engagement with the locking gear 45. If the parking function is incorrectly designed, the actuating movement is only carried out by one of the two control levers 49. In this case, the force introduction point 65 is only rotated by the reduced pivoting path h due to the lever arm ratios I1, I2. redThe reduced swivel range h red However, this is not sufficient to eliminate the tooth engagement of the pawl 43 with the locking gear 45. Rather, the pawl 43 and the locking gear 45 remain in reduced tooth engagement Z red The parking function therefore remains engaged in the event of a fault. Only when both pivoting levers 49 are moved can the tooth engagement between the pawl 43 and the locking gear 45 be removed.

[0060] In addition, during a rotational movement of the rotatable disc 27, Fig. 11 shown rotary zero position 0 into the park setting range S P (according to the Fig.11 a clockwise rotation) the following two cases result: In the first case, the control lever 49 slides from the large-diameter contour section 59 into the transition flank 57, whereby the pawl 43 comes into tooth-to-tooth contact with the locking gear 45. With a further rotation of the rotatable disc 27, the control lever 49 no longer slides along the transition flank 57 to the small-diameter contour section 55, but rather the control lever 49 lifts off the control contour 53. Only when the vehicle continues to roll does the pawl 43 engage in the locking gear 45, so that the parking lock 41 is engaged and the control lever 49 comes into contact with the small-diameter contour section 55 again. In the second case, the pawl 43 comes into tooth-to-gap contact with the locking gear 45 immediately after the start of the disk rotation of the rotatable disk 27.The pawl 43 is therefore immediately engaged, while the control lever 49 slides along the transition flank 57 to the small-diameter contour section 55. LIST OF REFERENCE SYMBOLS: 3-disk brake 5 Rotor shaft 7 countershafts 9 axle differential 11 Output shaft 12 counterholders 13 Axle differential gear 14 Torque support 15 Differential housing 17 outer disc carrier 18 inner disc carriers 19 Gearbox housing 21 Actuator 23 Ball ramp unit 25 fixed disc 27 rotating disc 29 ball 30 cage 31 Gearing 34 ball ramp 35 brake ball track 37 Park Marble Run 38 sliding bevels 39 Ramp deepening 41 Parking lock 43 pawl 45 locking gear 47 Parking lock shaft 49 control levers 50 instinctual connection 51 spring 53 Control contour 55 small diameter contour section 57 transition flank 59 diameter contour section 61 two-armed lever arm 63 second lever arm 65 Force introduction point 67 Rocker element 69 Driving lever 71 coupling point A1 Pawl rotation axis A2 Rocker element rotation axis B Direction of view I1, I2 lever arm lengths h1 full swivel range h red reduced swivel range Z voll complete tooth coverage Z red reduced tooth coverage 0 Rotary zero position U Transfer point KP Kisspoint P Ball freewheel position I1, I2 lever arms s axial expansion path S BBrake adjustment range S P Parking area S P1 , S P2 Sub-areas D B Braking direction D P Park rotation direction f ball freewheel

Claims

[1] Vehicle braking system for a vehicle axle of a two-track vehicle, which has a multi-disk brake or clutch (3) for each side of the vehicle with an electrically controllable actuator (21) with which a braking function for vehicle braking during driving or a parking function when the vehicle is parked can be engaged / disengaged in the multi-disk brake or clutch (3), characterized by that the vehicle braking system additionally has a parking lock (41), the locking pawl (43) of which can be brought into locking engagement with a locking gear (45), and that each of the two actuators (21) is in driving connection (50) with the locking pawl (43), so that when the parking function is engaged by at least one of the actuators (21), the locking pawl (43) can be adjusted into locking engagement. [2] Vehicle braking system according to claim 1, characterized bythat the drive connection (50) between the two actuators (21) and the pawl (43) is designed in such a way that a disengagement of the parking lock (41), i.e. a return of the pawl (43) from its locking position to its release position, only takes place under the condition that both actuators (21) disengage the parking function. [3] Vehicle braking system according to claim 1 or 2, characterized by that each of the actuators (21) engages the multi-disk clutch or brake (3) when the parking function is engaged and also controls the locking pawl (43) in the direction of its locking position, or that each of the actuators (21) disengages the multi-disk clutch or brake (3) and also controls the locking pawl (43) in the direction of its release position when the parking function is disengaged. [4] Vehicle braking system according to claim 1, 2 or 3, characterized bythat each of the actuators (21) has a pressing mechanism acting on the multi-disk brake or clutch (3), and that the pressing mechanism consists of a pair of discs consisting of a fixed disc (25) and a coaxially rotatable disc (27), and that to engage the braking function, an electric rotary drive of the actuator (21) rotates the rotatable disc (27) starting from a zero rotation position (0) in a braking rotation direction (D B ) via a braking angle into a braking setting range (S B ) and that to engage the parking function the rotating disc (27) is rotated from the zero position (0) in a direction opposite to the braking rotation direction (D B ) opposite parking direction of rotation (D P ) into a parking area (S P ) is adjustable. [5] Vehicle braking system according to claim 4, characterized bythat for a pawl control, the rotatable disc (27) of each of the two actuators (21) is in driving connection (50) with the pawl (43), so that upon rotation of at least one of the rotatable discs (27) into the parking setting range (S P ) the locking pawl (43) can be automatically brought into the locking position, and that upon rotation of the two rotatable discs (27) from the parking setting range (S P ) into the brake adjustment range (S B ) the locking pawl (43) can be automatically brought into the release position. [6] Vehicle braking system according to one of the preceding claims, characterized bythat the vehicle axle has an axle differential (9), the output sides of which drive onto the vehicle wheels via output shafts (11), and that on each output side a multi-disk brake or clutch (3) acts on the respective output shaft (11), and / or that the locking gear (45) of the parking lock (41) is connected in a rotationally fixed manner to an axle differential housing (15), and / or that the parking lock (41) is arranged at an axial distance from the respective multi-disk brake or clutch (3). [7] Vehicle braking system according to claim 5 or 6, characterized by that the drive connection (50) formed between the rotatable disc (27) and the pawl (43) has a parking lock shaft (47) to which a control lever (49) and the pawl (43) axially spaced therefrom are connected in a rotationally fixed manner, and that the control lever (49) is in sliding contact with a control contour (53) formed on the rotatable disc (27). [8] Vehicle braking system according to one of claims 4 to 7, characterized by , that the pressure mechanism acting on the multi-disk brake or clutch (3) has at least one ball-ramp unit (23) with which the multi-disk brake or clutch (3) can be subjected to contact pressure when the brake function or parking function is engaged and can be depressurized when the brake or parking function is disengaged, and that the ball-ramp unit (23) has a ball (29) which rolls between mutually facing, inclined ball tracks (35, 37) of the pair of discs, and that When the braking function is engaged, the ball (29) rolls on braking ball tracks (35), specifically with axial spreading of the pair of discs over an axial spreading path (s), in order to apply contact pressure to the multi-disk brake / clutch (3) which varies depending on the size of the braking rotation angle. [9] Vehicle braking system according to claim 8, characterized bythat when the braking function is engaged, a rolling resistance acts between the ball (29) and the brake ball tracks (35) of the pair of discs, and that the rolling resistance results in the ball-ramp unit (23) not being self-locking, i.e. being open when de-energized, so that in the event of a power failure the braking effect of the actuator (21) is canceled out.

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