Actuator for a mechanical brake system

Description

[0001] The invention relates to an adjusting device for a mechanical braking system, in particular an adjusting device for delivering a brake pad to a brake disc.

[0002] Motor vehicles and elevators, in particular, use electromechanical brakes or actuators for mechanical brakes, which are becoming increasingly smaller. Among other things, the power requirements of the electric drive motors or actuators for mechanical brakes are to be reduced by using an energy swing.

[0003] Energy swings are known from the state of the art, for example from EP2005022 (Knorr 2006) or EP1244879B1 (Wabco 1999). The principle is based on the exchange of energy between the braking system, in particular the brake caliper which is tensioned during braking, and an additional energy storage device. During braking, the brake caliper is elastically deformed by the braking forces. When the brake is released, the energy stored in the brake caliper is transferred or temporarily stored to an energy storage device and used for the application of the brake in a subsequent braking operation. The energy storage devices are also known as energy accumulators or force cartridges. They are designed, for example, as spring elements integrated into the actuator of the electromechanical brake. The actuator is in an approximately bistable state, which can be deflected to one side (application) or the other (release of the brake) by small forces.

[0004] EP2005022 (Knorr 2006) shows such an energy swing with an energy storage device connected to a lever arrangement. The energy storage device is controlled via an eccentrically mounted cam, with the lever position and cam contour adjusted to ensure a bistable state at all times. A disadvantage of this solution is the large installation space. Furthermore, the mass inertia of the lever arrangement must be moved with each adjustment. This is detrimental to fast response times.

[0005] EP1244879B1 (Wabco 1999) shows an energy swing with a fixed energy storage device 128 and two lever-like contours 101, 102, which is actuated via a double roller (roller 126 - contour 108, roller 127 - contour 109).

[0006] A disadvantage is the additional space required for the energy storage system. A particular disadvantage is that wear adjustment is not possible.

[0007] DE10140076A1 (WABCO 2006) shows an energy swing with rotatable cams 4, 5. The cams are nested and have different outer diameters. The cams are radially and axially rigidly connected, meaning that both cams always have the same angle of rotation and the same adjustment height. The braking process is initiated by rotation about the axis 17, 19 of the roller holder with rollers 15, 15a. The brake is applied via a lever 18". A disadvantage is the additional space that must be reserved for the energy storage device. A particular disadvantage is the point of application 17 of a drive (not shown) in the immediate vicinity of the brake disc 21.

[0008] From DE 10 2007 055637 A1, an electromechanical friction brake is also known, comprising an electromechanical actuating device and a friction brake lining which, in order to actuate the friction brake, can be pressed against a brake body to be braked by means of the actuating device, and comprising a spring element which has a falling spring characteristic and which acts parallel to the actuating device and acts on the friction brake lining in the sense of a brake actuation, wherein the actuating device has an electric motor and a ramp mechanism which converts a rotary drive movement of the electric motor into a translatory movement for pressing the friction brake lining against the brake body.

[0009] Also known from DE 10 2009 055265 A1 is a wheel brake for a land vehicle, comprising a friction brake lining and two redundant actuating devices, with which the friction brake lining can be pressed against the brake body to brake a rotatable brake body, wherein one actuating device is electromechanical and the other actuating device is pressure-actuated, wherein the wheel brake has an energy accumulator which stores energy when the wheel brake is released and releases energy when the wheel brake is actuated and supports the actuation of the wheel brake.

[0010] It is an object of the present invention to overcome the aforementioned disadvantages, or at least to reduce them, and in particular to provide an actuating device with an energy swing in a compact design.

[0011] The invention thus provides an actuating device for a mechanical braking system according to claim 1. In detail, this is an actuating device with an energy swing for a mechanical braking system, wherein the actuating device has an actuating drive for delivering a braking part for a service braking function. The actuating device has a force cartridge with a preloaded spring and a ramp bearing as an energy swing, wherein the ramp bearing is fastened to the actuating drive on one side and to the spring on the other side. The force cartridge interacts with the actuating drive in such a way that, depending on the adjustment position of the actuating drive, a force component is made available to assist the actuating drive. Furthermore, the force cartridge is mounted in particular on a force line of action of the actuating drive.

[0012] This support makes it possible to reduce the size of the actuators and provide a lower speed or, consequently, a lower torque (with a gearbox). This allows for the use of more cost-effective actuators. Furthermore, the required energy consumption of the actuators is reduced.

[0013] Preferably, the ramp bearing has a curved path with one or more linear and / or non-linear sections. The curved path can be adjusted depending on the desired braking behavior and / or force assistance. The curved path can also be adjusted depending on the torque curve of the actuator, since the torque curve is not linear.

[0014] The curved path(s) is / are preferably designed to be continuously differentiable in its gradients.

[0015] According to the invention, the actuator has a second ramp bearing for the brake application, wherein the second ramp bearing has a curved path with one or more linear and / or non-linear regions.

[0016] The different areas can be designed accordingly for different tasks, as the following advantageous embodiment shows: the second ramp bearing has a first area with a high gradient for quickly overcoming an air gap and a second area with a low gradient for generating high delivery forces.

[0017] Preferably, the cam track(s) of the first and second ramp bearings are coordinated in such a way that a bistable or unstable position for the positioning device can be achieved through specific rotation angles of the positioning device. This allows for self-releasing or self-tightening / self-reinforcing braking functions to be implemented as required.

[0018] To combine and thus amplify the effects of the correspondingly designed regions, the first ramp bearing can have two regions corresponding to the second ramp bearing via the angle of rotation, a first and a second region A and B. The first region A has a zero gradient for neutral behavior when overcoming an air gap, and the second region B has a tuned nonlinear characteristic such that a bistable position can be generated across the entire range of braking intervention. As a result, the feed force to be applied by the drive is essentially limited to overcoming system losses (friction losses) and moments of inertia.

[0019] Advantageously, the actuating device is designed with two actuators that can perform braking action jointly or independently of each other. This provides a redundant solution that allows for continued braking or application of the brake pad should one of the two actuators or servomotors fail.

[0020] Preferably, the first or second ramp bearing has a locking position, in particular in the form of a recess or trough, which forms a locking position for a parking brake function. This can serve as a parking brake function, in particular if a locking adjustment function is implemented by rotating the actuators in opposite directions.

[0021] Furthermore, it has proven advantageous if the pre-tensioned spring is attached at one end to the first ramp bearing and at an opposite end to a brake caliper.

[0022] The following features of further advantageous embodiments were not mentioned in the claims: Parts of the actuator are preferably enclosed by the spring, in particular in the form of a spiral spring, or are arranged within the inner circumference of the spiral spring. This allows for a more compact arrangement.

[0023] The ramp bearing of the energy swing has rings arranged axially one above the other, between which three or more rolling elements, particularly in the form of balls, are movably mounted. For this purpose, the lower ring has a continuous annular recess, and the upper ring has one or more annular recesses. This can also be reversed or mirrored. The two rings have a common axis of rotation at their center and can rotate or pivot around it.

[0024] The ramp bearing of the brake adjustment also has three or more rolling elements, particularly in the form of balls, which are movably mounted between two annular components. The recesses in the two components can be shaped like those of the ramp bearing of the energy swing.

[0025] The figures described below relate to preferred embodiments of the combination cable according to the invention and the axle drive unit according to the invention. These figures are not intended to be limiting, but rather to illustrate the invention. Elements from different figures, but with the same reference numerals, are identical; therefore, the description of an element from one figure also applies to elements with the same designation or number from other figures.

[0026] It shows Figure 1 shows a perspective view of a mechanical braking system with an actuating device according to an embodiment of the invention; Figure 2 shows a cross-sectional view of the mechanical braking system from Figure 1 ; Figure 3 an exploded view of the mechanical braking system from Figure 1 ; Figure 4 shows a schematic cross-sectional view of an actuating device according to the invention in an initial position; Figure 5 shows a schematic cross-sectional view of the actuating device according to the invention according to Figure 4 in a service brake; Figure 6 a schematic cross-sectional view of an actuating device according to the invention according to Figure 5 during wear adjustment.

[0027] Figure 1shows a perspective view of a mechanical braking system with an adjusting device according to an exemplary embodiment of the invention. Braking occurs by advancing and pressing a brake pad 2 against a brake disc 1. The brake pad 2 is part of a brake shoe. An adjusting device is used to adjust the brake pad 2. The adjusting device has an axially displaceable adjusting bolt 7, a spiral spring 8 as an energy store, a first gear 4 for a first actuator 3, a second gear 6 for a second actuator 5, and a receiving plate 9 as an axial bearing and connection to a brake caliper (not shown in full). The brake caliper has the brake pad 2 as a braking part and the adjusting device, wherein in particular the adjusting device is arranged in a housing. The brake caliper is arranged on or around the brake disc 1.

[0028] Figure 2shows a cross-sectional view of the mechanical braking system from Figure 1 , where the cross-sectional plane AA in Figure 1is drawn in. Additional details are shown here. The brake pad 2 can be advanced plane-parallel to the brake disc 1. The advance is achieved in particular by the axial displacement of an adjusting nut 10, on which an annular part of the ramp bearing 16 is arranged in a rotationally secure manner as a brake advance. The ramp bearing 16 has spherical rolling elements and is fastened on its other or opposite side to the adjusting bolt 7 in a rotationally secure manner. This means that a rotation of the adjusting nut 10 during its axial displacement is not transmitted to the adjusting bolt 7. The adjusting nut 10 is in operative engagement with both an adjusting spindle 20 and an adjusting sleeve 11 and can be moved (or locked - parking function) via one or both of these components 20, 11. The adjusting spindle 20 has a spindle-shaped external thread that is in operative engagement with an internal thread of the adjusting nut 10.This allows rotation of the adjusting spindle 20 to be transformed into axial movement of the adjusting nut 10. The adjusting sleeve 11 has a plurality of linear grooves on its inner circumference, arranged parallel to the axis, which operatively engage with the diametrically opposed outer grooves of the adjusting nut 10. Rotation of the adjusting sleeve 11 can result in axial movement of the adjusting nut 10. The adjusting sleeve 11 is attached to a gear 12, which can be driven and set in rotation via a drive pinion 13 of the servo motor 3. The gear 12 shown in . Figure 1The gear mechanism 4 described (also referred to as gear mechanism A) is formed by the gearwheel 12 and the drive pinion 13. A first, lower, annular component of the ramp bearing 17 of the energy swing is fastened to the upper side of the gearwheel 12. The second, upper, annular component of the ramp bearing 17 is mounted on the first component by means of spherical rolling elements. The second annular component is pressed onto the rolling elements and thus onto the first component by means of a preloaded spiral spring 8 that acts as an energy store. The second component of the ramp bearing 17 is only firmly connected to the spiral spring 8 or is in operative engagement with the spiral spring 8 and the rolling elements so that, among other things, the adjusting sleeve 11 can rotate independently of this component. The gear A 12 is rotatably mounted on a gear B 19 by means of an axial bearing or needle bearing 14, wherein the needle bearing 14 is arranged on the upper side of the gear B 19 and is fastened to it. Figure 1 The gear 6 described above (also referred to as gear B) is formed by the gear 19 and the drive pinion 18. The gear 19 is firmly connected to the adjusting spindle 20 and rotates it by means of the servo motor 5. The gear B 19 is rotatably connected to the receiving plate 9 by means of an axial bearing or ball bearing 15. The receiving plate 9 serves as a mount for the ball bearing 15 and is firmly connected to the brake caliper (not shown). All components of the adjusting device are arranged coaxially around the axis of rotation of the spindle 20.

[0029] Figure 3 shows an exploded view of the mechanical braking system from Figure 1 or Figure 2. In addition to the elements or components described above, a first sliding sleeve 23 and a second sliding sleeve 24 are shown in detail. The first sliding sleeve 23 is arranged between the adjusting spindle 20 and the adjusting sleeve 11 and, as a sliding contact / surface, enables a rotatable mounting of the spindle 20 and the adjusting sleeve 11. The second sliding sleeve 24 is arranged between the adjusting spindle 20 and the adjusting bolt 7 and, as a sliding contact / surface, enables a rotatable mounting of the spindle 20 relative to the adjusting bolt 7. The sliding sleeves 23, 24 serve in particular to stabilize the position and tilt of the components in contact with the sliding sleeves. The ramp bearing 17 is formed by an upper annular component with three arcuate recesses, three spherical rolling elements arranged in the recesses, and by a lower annular component (in particular as an insert in the gear 12) with an annular recess (not visible).The upper component of the ramp bearing 17 additionally has an anti-twist device 21 and an upper support surface 22 for the spring 8. The anti-twist device 21 is fastened, for example, to an axially extending rod or rail (not shown) so that the upper part of the ramp bearing 17 can be axially displaced and the force of the spring 8 can be transmitted to the rolling elements, via the gear 12 and finally to the adjusting sleeve 11. Similar to the ramp bearing 17 of the energy swing, the ramp bearing 16 of the brake feed has an upper annular component with three curved recesses, three spherical rolling elements arranged in the recesses and a lower annular component with an annular recess (not visible). The upper component and the lower component of the ramp bearing 16 are each connected to the adjusting bolt 7 and the adjusting nut 10 with three pins in a rotationally secure manner.

[0030] The Figures 4, 5 and 6each show a schematic cross-sectional view of an actuating device according to the invention; first in an initial position, then during service braking and finally during wear adjustment. The cross-sectional view illustrates in particular the forces acting on the components of the actuating device and their force directions. The components have already been described in the Figures 1 to 3 The function of the adjusting nut 10 is clearly visible. It can be moved by actuating the adjusting drive A with the adjusting sleeve 11 (starting with the actuator A 3) as well as by actuating the adjusting drive B with the adjusting spindle 20 (starting with the actuator B 4). By moving the adjusting nut 10, e.g. by horizontal displacement using the adjusting drive B (see Fig. 5 ) or by vertical displacement using the actuator A (see Fig. 6) the adjusting bolt 7 is moved and the brake pad 2 is applied. When braking in Fig. 5 the force of the force cartridge with the pre-tensioned spring 8 and the ramp bearing 17 supports the actuator B. The cross-sectional views illustrate the two brake pads 2, which are arranged in the brake calliper 25 and are moved or delivered by means of the adjusting device. List of reference symbols

[0031] 1Brake disc 2Brake shoe with brake pad 3Actuator A 4Gearbox A 5Actuator B 6Gearbox B 7Adjusting bolt 8Spring as energy storage 9Support plate axial bearing / connection to brake calliper 10Adjusting nut 11Adjusting sleeve 12Gear A 13Drive pinion A 14Axial bearing / needle bearing 15Axial bearing / ball bearing 16Ramp bearing (brake feed) 17Ramp bearing (energy swing) 18Gear B 19Drive pinion B 20Adjusting spindle 21Anti-twist device for cam ramp bearing 22Support surface spring / energy storage 23Sliding sleeve for sliding contact adjusting spindle-adjusting bolt 24Sliding sleeve for sliding contact adjusting spindle-adjusting sleeve 25Brake calliper

Claims

1. Actuating device with an energy swing for a mechanical brake system, wherein the actuating device has an actuating drive for adjusting a brake part for a service brake function, wherein the actuating device has a force cartridge with a pretensioned spring (8) and a first ramp bearing (17) as an energy swing, the first ramp bearing (17) being fastened to the actuating drive on one side and to the spring (8) on the other side, the force cartridge being mounted on a force-action line of the actuating drive and interacting with the actuating drive in such a way that a force component is made available to support the actuator drive as a function of the adjustment position of the actuator drive, characterised in that the actuator drive has a second ramp bearing (16) for the brake feed, the second ramp bearing (16) having a cam track with one or more linear and / or non-linear region(s).

2. Actuating device according to claim 1, characterised in that the first ramp bearing (17) has a curved path with one or more linear and / or non-linear region(s).

3. Actuating device according to claim 1, characterised in that the second ramp bearing (16) has a first region with a high pitch for quickly overcoming an air gap and a second region with a low pitch for generating high feed forces.

4. Actuating device according to claim 1 or 3, characterised in that the cam track(s) of the first and second ramp bearing (17; 16) are matched to one another in such a way that a bistable or unstable position can be achieved for the actuating drive for infeed via certain angles of rotation of the actuating device.

5. Actuating device according to claim 4, characterised in that the first ramp bearing (17) has two regions corresponding to the second ramp bearing (16) via the angle of rotation, a first and a second region A and B, wherein the first range A has a zero gradient for neutral behaviour during the overcoming of an air gap and the second range B has a non-linear characteristic tuned in such a way that a bistable position can be generated over the entire range of the brake application.

6. Actuating device according to one of claims 1 to 5, characterised in that the actuating device is designed with two actuators which can perform a brake application jointly or independently of one another.

7. Actuating device according to one of claims 1 to 6, characterised in that the first or second ramp bearing (17; 16) has a detent position, in particular in the form of a dent or trough, which forms a detent position for a parking brake function.

8. Actuating device according to one of claims 1 to 7, characterised in that the pretensioned spring (8) is fastened with one end to the first ramp bearing (17) and with an opposite end to a brake caliper (25).