DE102021201344A1 - Electromechanical wheel brake for a wheel unit of a motor vehicle - Google Patents

Abstract

The invention relates to an electromechanical wheel brake (100) for a wheel unit of a motor vehicle, the wheel brake (100) having control electronics (116), a drive unit (102) functionally connected to the control electronics (116) with a gear unit (102) connected downstream of the drive unit (102). 104) and a parking brake module (124), the transmission (104) being designed to convert a torque caused by the drive unit (102) on a drive shaft (118) into a clamping force (120) of the wheel brake (100) and wherein the The parking brake module (124) is designed to block a rotation of the drive shaft (118) controllably by the control electronics (116) in at least one direction of rotation (160). According to the invention it is provided that the parking brake module (124) has an actuating tappet (128), the actuating tappet (128) between a release position in which the drive shaft (118) is free by means of a bistable reversing lifting magnet (130) controllable by the control electronics (116) can rotate and a locking position, in which a rotation of the drive shaft (118) in at least one direction of rotation (160) is blocked by the parking brake module (124), is displaceable.

Description

The invention relates to an electromechanical wheel brake for a wheel unit of a motor vehicle according to the preamble of claim 1.

Such wheel brakes are known in the prior art. For example, describes the DE 10 2017 206 798 A1 an electromechanical wheel brake for a wheel unit of a motor vehicle, the wheel brake having control electronics, a drive unit functionally connected to the control electronics with a gearbox connected downstream of the drive unit, and a parking brake module, the gearbox being designed to convert a torque caused by the drive unit to a drive shaft to convert an application force of the wheel brake and wherein the parking brake module is designed to block a rotation of the drive shaft controllably by the control electronics in at least one direction of rotation.

The present invention is based on the object of creating a wheel brake with a parking brake module that enables the wheel brake to be safely locked in a parking brake position using simple means, while at the same time reducing the risk of the parking brake function failing, for example as a result of an electrical defect.

This object is achieved with a wheel brake with the features of claim 1. Advantageous configurations are the subject of the dependent claims.

In the case of an electromechanical wheel brake for a wheel unit of a motor vehicle, the wheel brake having control electronics, a drive unit functionally connected to the control electronics with a transmission connected downstream of the drive unit, and a parking brake module, the transmission being designed to apply a torque produced by the drive unit to a drive shaft To convert into an application force of the wheel brake and wherein the parking brake module is designed to block a rotation of the drive shaft controllably by the control electronics in at least one direction of rotation, it is provided according to the invention that the parking brake module has an actuating tappet, the actuating tappet by means of a bistable controllable by the control electronics Reversing lifting magnets between a release position in which the drive shaft can rotate freely and a blocking position in which the drive shaft can rotate in at least one direction of rotation rch the parking brake module is blocked, can be moved. The direction of rotation that is blocked by the parking brake module in the locking position is preferably that direction of rotation of the drive shaft that leads to the wheel brake being opened. This direction of rotation is also referred to below as the “application direction”

A “bistable reversing lifting magnet” is to be understood as a magnetic arrangement that has at least two clearly definable end positions that can be set by a corresponding energization or activation of the magnetic arrangement. The use of such an arrangement is characterized in that the locking mechanism of the parking brake module can be safely controlled with simple means. The actuating tappet can block a rotation of the drive shaft both directly and indirectly. It can thus be provided that the blockage acts directly on the drive shaft and that the blockage acts on an element that is rotationally connected to the drive shaft, for example on the gearbox of the wheel brake.

According to a preferred embodiment, the reversing solenoid has an armature mounted movably along an actuating direction and a magnetic coil, the armature being arranged within the coil and the actuating plunger being mounted at least in sections within the armature. By reversing the polarity of the current supply to the reversing lifting magnet, it is possible to switch between the different operating states of the fixed brake module, since the position of the armature within the magnet coil changes accordingly.

In order to reduce the wear of the actuating plunger during locking processes, a further embodiment provides that a spring arrangement is arranged within the armature, the spring arrangement pushing the actuating plunger out of a neutral position with a force in the direction of the neutral position when the actuating plunger is deflected relative to the armature applied. Consequently, the actuating tappet does not necessarily follow every movement of the armature, but can rather be displaced with respect to the armature, for example when the actuating tappet encounters an obstacle that blocks further displacement. The spring arrangement is preferably a pretensioned spring assembly, which consists of at least two springs, which are arranged symmetrically around a point of articulation of the springs on the actuating plunger.

A defined range of motion within which the armature and therefore the actuating plunger can move is achieved according to a further embodiment in that the armature has projections on its end faces which extend perpendicular to the actuating direction and limit movement of the armature relative to the magnet coil by means of a stop on the magnet coil. The projections are preferably made in one piece with the anchor. Furthermore, the projections preferably extend around the entire circumference of the anchor. The movement of the armature is preferably limited in that from a certain displacement of the armature relative to the magnet coil, the armature projections hit corresponding elements of the magnet coil, so that further displacement of the armature is blocked.

In order to ensure that the actuation position of the parking brake module does not accidentally change even in the event of a failure of the bistable lifting magnet, for example as a result of an electrical defect, a further embodiment provides that permanent magnets and correspondingly magnetizable elements are arranged on both sides between the projections and the magnet coil, so that the armature is acted upon by the arrangement of permanent magnets and magnetizable elements with a force in the direction of the respective stop.

The permanent magnets and / or the magnetizable elements are preferably designed in a ring shape. The arrangement of permanent magnets can be arranged on the armature, while the magnetizable elements can be arranged on the magnetic coil. Likewise, the reverse arrangement is also possible, so that the permanent magnets are arranged on the magnet coil, while the magnetizable elements are arranged on the armature. The connection of such an arrangement ensures that even in the event of a failure of the electronics, the armature and consequently the actuating tappet remain in a position that has once been set.

In order to continue to enable safe actuation of the parking brake module despite the armature being secured in the end positions of the actuation positions by the permanent magnets, a further embodiment provides that the force generated by the magnetic coil is greater than the force generated by the permanent magnets.

According to a further embodiment it is further provided that a ratchet wheel is arranged on the drive shaft, which is positively and / or non-positively secured against rotation about the longitudinal axis of the drive shaft relative to the drive shaft, the blocking of the rotation of the drive shaft by blocking a rotation of the Ratchet wheel is reached.

It is preferably provided that the parking brake module has a locking pawl, the locking pawl being switchable between the locking position and the release position by the actuating plunger, the locking pawl engaging the ratchet wheel in the locking position and a rotation of the ratchet wheel in at least one direction, in particular against the Application direction, blocked.

A simple construction of the parking brake module is achieved according to a further embodiment in that the pawl is pivotably mounted about a pivot axis, the pivot axis being aligned parallel to the axis of rotation of the drive shaft.

According to a preferred embodiment it is further provided that the ratchet wheel has teeth with an undercut geometry so that as soon as the pawl is in the locking position, rotation of the ratchet wheel is prevented by a positive fit between the teeth and the pawl in one direction of rotation. The undercut geometry is preferably designed in such a way that when the drive shaft rotates against the blocked direction, i.e. in the application direction, the pawl can slide off the undercut geometry, so that if the pawl is deflected slightly from the blocking position, the ratchet wheel can rotate against the blocked direction is. In this way, the wheel brake can be re-tensioned if necessary without the parking brake module having to switch to the release position. Such a trailer may be necessary, for example, if the vehicle is parked with the brakes warm, whereupon the brakes subsequently cool down and the set application force is reduced.

In order to detect a secure locking of the wheel brake by the parking brake module, it is further provided according to a further embodiment that the parking brake module has means for determining a position of the actuating tappet.

According to a further embodiment it is provided that the means have magnetic sensors, the magnetic sensors being designed to detect the position of a sub-area of the actuating plunger relative to the magnetic sensors.

• 1 eine perspektivische Ansicht einer Radbremse für eine Radeinheit eines Kraftfahrzeugs,
• 2 verschiedene Ansichten einer beispielhaften elektromechanischen Radbremse,
• 3 eine schematische Darstellung des funktionalen Aufbaus einer solchen elektromechanischen Radbremse,
• 4 eine schematische Darstellung eines beispielhaften Feststellbremsmoduls,
• 5 eine schematische Darstellung eines bistabilen Umkehrmagneten, und
• 6 ein Diagramm von in dem Feststellbrems Modul wirkenden Kräften.

In the following, preferred embodiments of the invention are explained in more detail with reference to the drawings. Show:

• 1 a perspective view of a wheel brake for a wheel unit of a motor vehicle,
• 2 various views of an exemplary electromechanical wheel brake,
• 3 a schematic representation of the functional structure of such an electromechanical wheel brake,
• 4th a schematic representation of an exemplary parking brake module,
• 5 a schematic representation of a bistable reversing magnet, and
• 6th a diagram of forces acting in the parking brake module.

In the following, features that are similar or identical to one another are identified by the same reference symbols.

the 1 shows a perspective view of a known wheel unit, which is suitable, for example, for use in BEV motor vehicles (Battery Electric Vehicle), with a wheel disk shown in partial section 1 . The wheel dish 1 has a mounting flange 2 for connection to a chassis component (not shown) of the motor vehicle, a rim ring 3 for holding a tire, not shown, and a rim star 4th for connecting the mounting flange 2 with the rim ring 3 . The mounting flange 2 has a cover panel 5 to cover components, not shown, of a wheel bearing. On the wheel dish 1 is about a fastening device 6th a disc-shaped brake rotor that is exposed radially inwards 7th attached. The brake rotor 7th is radially on the inside of a vehicle-mounted brake actuator 8th (Fixed saddle) encompassed. It should be pointed out that the invention also allows a design as a floating caliper disc brake, and wherein the floating caliper housing is mounted relatively displaceably and non-rotatably on a brake holder which is designed for non-rotatable and axially displaceable mounting of the brake linings.

The brake actuator 8th decrees according to 1 Via a fixed caliper brake housing with two the brake rotor 7th opposing brake pads. The brake rotor 7th is still on the rim star 4th and the fixed caliper housing 9 is attached to a chassis component, not shown.

By way of example, an EPB actuator system is implemented and explained below in a configuration or cooperation with an EMB floating caliper disc brake encompassed on the inside, with one just as well
EMB fixed caliper assembly and / or another externally encompassed EMB disc brake concept or, alternatively, one
EMB drum brake system is conceivable without departing from the invention.

the 2 shows examples of different views of an electromechanical wheel brake 100 trained brake actuator. The 2 a) a side view while the 2 B) Figure 9 shows a perspective view.

The wheel brake shown as an example 100 has a drive unit 102 in the form of an electric motor, in particular a brushless DC motor, to which a multi-stage gear is attached 104 connects. The gear 104 is divided into two gear stages 106 and 108 on. The first gear stage 106 that attach directly to the drive unit 102 is used essentially to adapt the speed of rotation by the drive unit 102 driven gear shaft by a step-up or step-down and a redirection of the power flow. The second gear stage 108 serves to convert the rotation of the drive shaft or a part of the first gear stage driven by the drive shaft 106 , in a translational motion.

This translational movement is then applied to friction linings 110 a saddle fist 112 the wheel brake 100 transmitted, so that by responsive control of the drive unit 102 the friction linings 110 with a defined force on one between the friction linings 110 arranged friction body 114 be pressed. As a result of the resulting frictional force, there is a rotation of the friction body 114 , in particular a brake disc, delayed.

the 3 shows a schematic representation of the functional structure of a wheel brake 100 as previously described. The illustrated drive unit 102 is done by control electronics 116 controlled so by the wheel brake 100 a defined braking force can be provided in a targeted manner. There is a drive shaft 118 by the drive unit 102 can be applied with a torque, with a first gear stage 106 connected in the form of a rotation-rotation gear. To the first gear stage 106 a second gear stage then closes 108 in the form of a rotation-translation gear, so that a through the drive unit 102 generated torque into one on the friction linings 110 acting clamping force 120 can be implemented. It is in the second gear stage 108 also a force sensor 122 arranged, the determined application force or a variable describing the application force to the control electronics 116 transmitted so that a targeted control of the drive unit 102 is possible.

the 3 also shows that the wheel brake 100 a parking brake module 124 has that directly on the drive shaft 118 acts. With the parking brake module 124 it is a mechanical component that deliberately causes the drive shaft to rotate 118 can block, so one by the wheel brake 110 set in the saddle fist Clamping force 120 is maintained without the drive unit 102 must continue to be energized. The parking brake module is for this purpose 124 designed to cause a rotation of the drive shaft 118 to block in the direction of rotation that causes the brake to be released, i.e. a reduction in the applied application force 120 would lead. The configuration according to the invention of such a parking brake module 124 is explained in more detail below by way of example.

The parking brake module 124 is also signaling with the control electronics 116 connected so through the control unit 116 blocking of the drive shaft 118 through the parking brake module 124 can be triggered. The control electronics are used for this 116 also with a parking brake button 126 connected, which can be operated by a vehicle driver, so that a parking brake function is triggered.

In the 3 is shown that the parking brake module 124 directly on the drive shaft 118 acts on the drive unit 102 connects. However, within the scope of the present invention it is also possible for the parking brake module to act on elements of the gear stages 106 or 108 , or other elements for power transmission between the drive unit 102 and friction lining 110 acts so that a release of the brake is effectively prevented.

The structure of such a parking brake module is now exemplified below with reference to FIG 4th described.

the 4th shows two schematic representations of an exemplary parking brake module 124 in different operating states. The 4 a) the parking brake module 124 in a locked position while the 4 b) the parking brake module 124 shows in a release position.

The parking brake module has an actuating tappet 128 by a bistable reversing solenoid 130 can be switched between the locked position and the release position. The bistable reversing stroke magnet is used for this purpose 130 a solenoid 132 and one in the solenoid 132 along an actuation direction 134 displaceable anchor 136 on. By reversing the polarity of the current supply to the magnet coil 132 can do the anchor 136 be moved between the locked position and the release position.

The anchor points 136 at its end faces 138 Cantilevers 140 which extend radially outward. These cantilevers 140 limit over a stop 144 on the solenoid 132 a possible displacement of the armature 136 in the solenoid 132 . Thereby are in the area of the cantilevers 140 Permanent magnets 142 at the anchor 136 arranged while at the stop 144 magnetizable elements 146 , for example rings made of a magnetic material, in particular metal, are arranged. However, this arrangement is only an example. Conversely, it could also be provided that the permanent magnets 142 on the solenoid 132 are arranged while the magnetizable elements 146 at anchor 136 are arranged.

By the arrangement of permanent magnets described 142 and magnetizable elements 146 this ensures that the armature remains in an end position that has been set, even if the solenoid 132 , for example due to a fault in the power supply. However, it must be ensured that the magnetic coil 132 on the anchor 136 achievable force is always greater than the holding force of the permanent magnets 142 so that a safe switching of the parking brake module 124 is always possible. The arrangement of solenoid 132 and anchor 136 is in a common housing 148 arranged.

In addition to the described arrangement of permanent magnets 142 and magnetizable elements 146 can optionally also secure the end positions of the armature 136 be made with mechanical locking elements, such as spring elements.

The actuating tappet 128 is there with the anchor 136 connected so that a movement of the anchor 136 along the direction of actuation 134 is transmitted to the actuating plunger. The actuating tappet is used for this purpose 128 line by line within the anchor 136 arranged and via a preloaded spring arrangement 150 at the anchor 136 supported. In the in 4th shown neutral position of the actuating tappet 128 opposite the anchor 136 becomes the actuating tappet 128 by the spring arrangement 150 acted upon by forces of the same magnitude from both directions, so that the actuating plunger 128 remains stable in its current position. When the actuating tappet is moved 128 from this position relative to the anchor 136 acts due to the spring arrangement 150 a force on the actuating plunger 128 which drives the actuating tappet back into the neutral position.

On the actuating tappet 128 is also a pawl 152 hinged, with the pawl 152 around a pivot axis 154 is pivotably mounted. By moving the actuating plunger 128 along the direction of actuation 134 is doing the pawl 152 pivoted between the locked position and the release position. The pawl 152 works with a ratchet wheel 156 together, rotatably on the drive shaft 118 is arranged. The ratchet wheel 156 has for this purpose an external toothing with a Undercut geometry 158 so that when the pawl engages 152 into the undercut geometry 158 a rotation of the ratchet wheel 156 and therefore the drive shaft 118 in a first direction of rotation 160 , which would lead to a release of the brake, is blocked. The one from the ratchet wheel 156 force transmitted to the pawl 160 is on by storing the pawl 152 on the swivel axis 154 recorded.

The undercut geometry 158 is also designed so that a rotation of the ratchet wheel in the locking position 156 and therefore the drive shaft 118 in a second direction of rotation 162 is still possible. When the drive shaft rotates 118 in the second direction of rotation 162 becomes the clamping force of the wheel brake 100 increased, which may be necessary, for example, in the course of a retensioning process of the wheel brake when the parking brake function is set. This is where the undercut geometry is 158 designed so that when the ratchet wheel rotates 156 in the second direction of rotation 162 the pawl 152 on the outer contour of the ratchet wheel 156 slides off. Thereby the pawl 152 easily around the pivot axis 154 pivoted, which is due to the connection between the pawl 152 and actuating tappets 128 to a displacement of the actuating plunger 128 along the direction of actuation 134 leads. Due to the storage of the actuating plunger 128 in the anchor 136 by means of the spring arrangement 150 however, such a shift is possible without the anchor 136 in the solenoid 132 having to move. The pawl acts when the pawl is deflected 156 by the spring arrangement 150 a force on the actuating plunger 128 and therefore the pawl 156 that the pawl on the outer contour of the ratchet wheel 156 presses. As a result, the brake can be re-tensioned at any time, even when the parking brake is set, without having to switch the parking brake module to the release position.

The parking brake module 124 also has means 164 to determine a current position of the actuating plunger 128 on. The parking brake module 124 magnetic sensors 166 which are designed to indicate the location of a sub-area 168 of the actuating tappet 128 relative to the magnetic sensors 166 capture. In this way it can be ensured whether the parking brake function is set so that this is done by the drive unit 102 The torque generated can be reduced without releasing the wheel brake 100 to effect.

the 5 shows again a schematic representation of the bistable reversing lifting magnet 130 to explain the when the parking brake module is activated 124 acting forces. The corresponding force curves are in the 6th shown.

In the force-displacement diagram ( 6th ) of the bistable reversing solenoid 130 is the force curve of the magnetic holding force 170 the permanent magnets 142 over the displacement path 172 of the anchor 136 applied as an example. The force curve 174 represents the behavior of the bistable reversing solenoid 130 with an energized solenoid 132 This results in the maximum energized holding force 176 in the mechanical end position, determined by the stop 144 and the cantilevers 140 . The two characteristics 170 and 174 apply to the two basic positions of the parking brake, i.e. the locked position and the release position, and are therefore reflected on the diagram axis 178 . The force-displacement curve shown in the diagram 180 also provides the spring characteristics of the spring arrangement 150 represent, with the maximum. Spring force is always functionally reliable below the magnetic armature holding force. In the activated parking brake position, i.e. the locked position, this guarantees that the wheel brake is re-tensioned 100 without activation of the bistable reversing solenoid 130 . The pawl lifts 152 against the force of the spring assembly 150 and skips the ratchet wheel rotating in the second direction of rotation 156 . Is the creation of a sufficient holding force required clamping force of the wheel brake 100 reached again, this can be done by the drive unit 102 provided torque can be reduced again and the pawl 152 locks again securely through the undercut geometry 158 in the ratchet wheel 156 . This safe end position is now established by the sensor means 164 confirmed, the torque of the drive unit can 102 by means of the control electronics 116 be driven down to zero.

QUOTES INCLUDED IN THE DESCRIPTION

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Patent literature cited

• DE 102017206798 A1 [0002]

Claims (12)

Electromechanical wheel brake (100) for a wheel unit of a motor vehicle, the wheel brake (100) having control electronics (116), a drive unit (102) functionally connected to the control electronics (116) with a transmission (104) connected downstream of the drive unit (102) and a The parking brake module (124), the transmission (104) being designed to convert a torque caused by the drive unit (102) on a drive shaft (118) into an application force (120) of the wheel brake (100) and the parking brake module (124) is designed to block a rotation of the drive shaft (118) controllably by the control electronics (116) in at least one direction of rotation (160), characterized in that the parking brake module (124) has an actuating tappet (128), the actuating tappet (128) by means of a bistable reversing stroke magnet (130) controllable by the control electronics (116) between a release position in which the drive shaft ( 118) can rotate freely and is displaceable to a locking position in which rotation of the drive shaft (118) in at least one direction of rotation (160) is blocked by the parking brake module (124). Wheel brake (100) Claim 1 , characterized in that the reversing lifting magnet (130) has an armature (136) mounted movably along an actuation direction (134) and a magnetic coil (132), the armature (136) being arranged within the magnetic coil (132) and the actuating plunger ( 128) is mounted at least in sections within the armature (136). Wheel brake (100) Claim 2 , characterized in that a spring arrangement (150) is arranged within the armature (136), the spring arrangement (150) exerting a force on the actuating plunger (128) when the actuating plunger (128) is deflected relative to the armature (136) from a neutral position applied in the direction of the neutral position. Wheel brake (100) Claim 2 or 3 , characterized in that the armature (136) has projections (140) on its end faces (138) which extend perpendicular to the actuation direction (134) and a movement of the armature (136) relative to the magnetic coil (132) by a stop (144) ) at the solenoid (132). Wheel brake (100) Claim 4 , characterized in that permanent magnets (142) and correspondingly magnetizable elements (146) are arranged between the projections (140) and the magnetic coil (132) on both sides, so that the armature (136) is formed by the arrangement of permanent magnets (142) and magnetizable elements ( 146) is acted upon by a force in the direction of the respective stop (144). Wheel brake (100) Claim 5 , characterized in that the force that can be generated by the magnetic coil (132) is greater than the force generated by the permanent magnets (142). Wheel brake (100) according to one of the preceding claims, characterized in that a ratchet wheel (156) is arranged on the drive shaft (118), which is positively and / or non-positively against rotation about the longitudinal axis of the drive shaft (118) relative to the drive shaft (118) ) is secured, the blocking of the rotation of the drive shaft (118) being achieved by blocking a rotation of the ratchet wheel (156). Wheel brake (100) Claim 7 , characterized in that the parking brake module (124) has a pawl (152), the pawl (152) being switchable between the locked position and the release position by the actuating plunger (128), the pawl (152) in the locked position in the ratchet wheel (156) engages and blocks rotation of the ratchet wheel (156) in at least one direction (160). Wheel brake (100) Claim 8 , characterized in that the pawl (152) is mounted pivotably about a pivot axis (154), the pivot axis (154) being aligned parallel to the axis of rotation of the drive shaft (118). Wheel brake (100) Claim 8 or 9 , characterized in that the ratchet wheel (156) has teeth with an undercut geometry (158) so that, as soon as the pawl (152) is in the blocking position, the ratchet wheel (156) rotates through a form fit between the teeth and pawl (152 ) is prevented in one direction of rotation (160). Wheel brake (100) according to one of the preceding claims, characterized in that the parking brake module (124) has means for fixing a position of the actuating tappet (128). Wheel brake (100) Claim 11 , characterized in that the means have magnetic sensors (166), the magnetic sensors (166) being designed to detect the position of a partial area (168) of the actuating plunger (128) relative to the magnetic sensors (166).

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