Electromechanical service brake, unlocking tool and assembly

Abstract

The invention relates to an electromechanical service brake, an unlocking tool and an assembly. The electromechanical service brake (10) has an integrated electric parking brake (12) and comprises an electric motor (14) and a control unit (16). The parking brake (12) has a blocking element (46) which, in the locked state of the parking brake (12), mechanically blocks a transmission (50) of the electromechanical service brake (10). The electric motor (14) and the transmission (50) are surrounded by a housing (18) having a cutout (24) that allows the blocking element (46) to be manually actuated from the outside so that the blocking element (46) can be mechanically transitioned from the locked state to the open state from the outside. In the open state, the transmission (50) is free to move. The cut-out (24) is a non-circular structure having at least one axially extending guide groove (28) and / or at least one axially extending guide rib. The assembly includes an electromechanical service brake (10) and an unlocking tool (44).

Description

Technical Field

[0001] The invention relates to an electromechanical service brake with an integrated electric parking brake, with an electric motor and with a control unit, an unlocking tool for manually unlocking a blocking element of the electric parking brake and an assembly comprising the electromechanical service brake and the unlocking tool. Background Art

[0002] Electromechanical service brakes with an integrated electric parking brake are known in the prior art. However, faults may occur in the electronics, with the result that the parking brake cannot be released and further travel is prevented. Such faults are caused, for example, by a defective solenoid, a defective motor, a defective control unit or an electrical fault.

[0003] The problem is that before the electric parking brake opens, a certain amount of tension must be built up in the electromechanical service brake to release the electric parking brake. However, if the current is prevented from flowing, this is not possible and the parking brake cannot be released. In this case, it is currently necessary to remove the entire electrical control unit from the electromechanical service brake or to tow the vehicle so that it can be repaired in a workshop. This is very expensive for the vehicle owner. Summary of the invention

[0004] It is therefore an object of the present invention to provide an electromechanical service brake with an integrated electric parking brake, in the case of which, in the event of a blocking of the parking brake, at least further travel to the nearest workshop is possible.

[0005] According to the invention, this problem is solved by an electromechanical service brake with an integrated electric parking brake and comprising an electric motor and a control unit, wherein the electric parking brake comprises a blocking element which mechanically blocks the transmission of the electromechanical service brake in the stopped state of the electric parking brake. Here, the electric motor and the transmission are surrounded by a housing having a cutout which allows the blocking element to be manually actuated from the outside so that the blocking element can be mechanically transferred from the stopped state to the open state from the outside. In the open state, the transmission can move freely. The cutout is a non-circular structure having at least one axially extending guide groove and / or at least one axially extending guide rib. In other words, the cutout allows access to the blocking element and thus allows the blocking element to be mechanically transferred from the stopped state to the open state by manual actuation. Thus, the problem of a blocked parking brake can be solved quickly, easily and cheaply without the need to tow the vehicle.

[0006] In particular, the cutout allows access from the outside using a tool provided for actuating the blocking element.The basic concept is therefore to allow manual actuation of the blocking element in technical emergencies by providing a cutout in the housing of the electromechanical service brake.

[0007] At least one axially extending guide groove and / or at least one axially extending guide rib are guide aids which simultaneously serve as preventive safety measures. These guide aids ensure that a tool can only be inserted in one specific direction and also ensure that only one specific tool can be used which also engages precisely in the optimal position for unlocking the blocking element.

[0008] The housing also has an end wall and a side wall, wherein the side wall can have the cutout. The cutout is thus oriented orthogonally with respect to the armature and with respect to the motor shaft and is arranged symmetrically above the actuator plunger of the parking brake. Since the circuit board is arranged directly below and adjacent to the end wall, frontal access to the electric parking brake is not possible, and the cutout does not simply constitute an opening in the housing cover or the end wall. The cutout is only a small opening in the side wall, making it difficult or even impossible to access the blocking element without tools. The cutout arranged on the side wall is still easily accessible and thus allows the blocking element to be released.

[0009] Preferably, the cutout tapers conically and is surrounded by a sleeve-like protrusion, which is integrally formed on the housing and protrudes outward. In particular, the guide aid is integrated into the protrusion, wherein the protrusion serves to protect the cutout and the electric parking brake at the same time.

[0010] In one embodiment, the cutout is covered by a cover, in particular a mushroom-shaped cover. The cover is received in the cutout and in the protrusion such that an opening tool is required to remove the cover.

[0011] To this end, the projection preferably has at least one slot, by means of which the opening tool can engage laterally on the cover in order to remove the cover. The cover serves to protect the electric motor and the transmission and also prevents undesired direct access to the blocking element. Since an opening tool is required to remove the cover, accidental or unauthorized access is prevented, which prevents theft.

[0012] The opening tool is preferably a special tool that can be used specifically for breakdown service, towing service and workshop. It can therefore be ensured that the parking brake can only be released by a selected person or service.

[0013] Alternatively, the opening tool may be a flat head screwdriver which is inserted into a slot in the protrusion so that the cover can be pried open. It is also conceivable that the cover is provided with a safety lock.

[0014] In order to achieve a higher level of protection with regard to the tightness, a sealing element can be provided between the housing and the cover, which sealing element is clamped between the conical area of ​​the cutout and the cover. The sealing element preferably consists of an elastomer and is preloaded in its installed state. The sealing element thus seals primarily against the conical shoulder.

[0015] In one embodiment, the cover is a pressure equalization element between the interior of the housing and the surroundings. For this purpose, a diaphragm is integrated into the cover. The diaphragm is provided to prevent the ingress of liquids and / or dirt and still allow air and / or pressure equalization. For this purpose, the diaphragm preferably consists of expanded polytetrafluoroethylene (ePTFE), which has a microporous structure and hydrophobic and / or oleophobic properties. Due to the fact that the cover can be used as a pressure equalization element, the number of required components is reduced, which in turn reduces costs.

[0016] The cover may have a detent hook that engages behind the narrowest point of the incision. This ensures a reversible fastening of the cover to the incision. However, the cover may alternatively be screwed to the housing. With this screw connection, the slot in the projection is not necessary.

[0017] In one embodiment, an electromagnetic actuator, in particular a bistable solenoid, is provided for moving the blocking element into the stopped state and the open state. During normal operation, the electromagnetic actuator is responsible for actuating the parking brake and providing the tension for releasing the parking brake. The cutout is therefore only used to transfer the blocking element into the released state in the event of an electrical failure of the electromechanical service brake.

[0018] Bistable solenoids are particularly suitable as electromagnetic actuators, since the armature of the solenoid assumes a stable position only in the fully extended or fully retracted extreme settings. Here, stable intermediate positions of the armature are excluded, since the magnetic force determines the stroke position and thus moves the armature and immobilizes it when the electromagnetic actuator is not energized.

[0019] The electromagnetic actuator of the parking brake preferably has a load-free connection with the transmission. This load-free connection enables the actuator to be unloaded when the parking brake is in the stopped state, in particular also due to the fact that there is no electrical connection between the actuator and the electromechanical service brake. Thus, no damage to the force sensor arrangement occurs during the mechanical transition to the open state of the parking brake, which would be equal to the total losses.

[0020] In a preferred embodiment, the blocking element is a pawl, which engages in a toothing of the transmission. In particular, the pawl has a pivot bearing end and a tooth that engages in the toothing. In addition, the pawl can have an opening, in particular a slot, through which the blocking element is connected to the electromagnetic actuator. Here, a pin connected to the actuator plunger can engage in the opening so that a slotted guide is formed, whereby the blocking element can be pivoted from the open state to the stopped state and from the stopped state to the open state.

[0021] In addition, the above object is achieved by an unlocking tool, which is used to manually transform the blocking element of the electric parking brake as described above from the stopped state to the open state. Here, the unlocking tool is rod-shaped and has an insertion part and a holding part. The insertion part includes at least one axially extending guide rib and / or at least one axially extending guide groove.

[0022] The unlocking tool is preferably a special tool, ie a tool which is not defined in a standard and is therefore not commercially available in hardware stores or in the tool trade.

[0023] In one embodiment, if a plurality of guide ribs and / or a plurality of guide grooves are provided, the plurality of guide ribs and / or a plurality of guide grooves are arranged asymmetrically on the circumference of the unlocking tool relative to the longitudinal center axis of the unlocking tool. In this way, a circumferential orientation of the unlocking tool is ensured. In other words, if the unlocking tool has, for example, two guide ribs or guide grooves, the angular spacing is not equal to 180 degrees. Due to this circumferential orientation, it can be ensured that the unlocking tool is correctly inserted.

[0024] In one embodiment, the unlocking tool has a laterally protruding end stop which separates the insertion portion from the retaining portion. Here, the end stop limits the insertion of the unlocking tool into the electric parking brake. Thus, the end stop also serves to signal to a person that the locking element has been completely released. This is the case when the end stop abuts against the electromagnetic actuator. Thus, the end stop accurately indicates when the motor shaft has been unlocked.

[0025] Preferably, the insertion section of the unlocking tool is of fork-shaped design and / or tapers in a wedge shape. By means of the fork-shaped insertion section, the unlocking tool can engage around the actuator plunger, whereby the two are locked together, so that the force can always be introduced precisely. By means of the wedge-shaped taper of the insertion section, the unlocking tool can be introduced more easily between the electromagnetic actuator and the connection to the blocking element. Furthermore, by means of the wedge shape, a precisely predefined spreading action can be achieved, which ensures a precise pivoting of the blocking element.

[0026] Furthermore, according to the invention, the object is also achieved by an assembly comprising an electromechanical service brake as described above and an unlocking tool according to the above description. Here, the insertion of the unlocking tool into the cutout in the housing of the electromechanical service brake produces a form fit by means of one or more guide grooves and / or one or more axially extending guide ribs in the cutout and a complementary guide rib or guide groove on the unlocking tool coming into engagement. This ensures a unique circumferential orientation of the unlocking tool. The unlocking tool is correctly introduced into the housing without any angular deviation, thus ensuring that the unlocking tool can actually release the parking brake.

[0027] In one embodiment of the assembly, the insertion portion of the unlocking tool is forked and tapers in a wedge shape. The unlocking tool can be inserted into the cutout in a single axial orientation until the end stop and is configured to pivot the pawl to an open state. Here, the forked insertion portion of the unlocking tool enters the gap between the electromagnetic actuator and the pawl and increases the size of the gap. To this end, the forked insertion portion receives the actuator plunger so that an axial force and an axial stroke can be applied to the actuator plunger similar to a wedge thrust mechanism. Here, the unlocking tool is supported against the end side of the actuator so that the blocking element can be radially pivoted in opposition to the acting retaining force and disengaged from the engagement with the transmission.

[0028] Furthermore, the problem can be solved by a method for emergency unlocking of a parking brake, wherein the parking brake is integrated in an electromechanical service brake. Here, the electric motor and the transmission of the electromechanical service brake are surrounded by a housing having a cutout, wherein a blocking element of the parking brake is mechanically released from the outside through the cutout from a blocking state in which the blocking element blocks the transmission. In other words, the parking brake can be unlocked in an emergency by mechanically releasing the blocking element.

[0029] To release the actuator, an unlocking tool is preferably used which pivots the blocking element out of engagement with the transmission. This is possible because the transmission is unloaded so that the release of the blocking element does not result in a total loss of the sensor arrangement.

[0030] The electromechanical service brake further comprises a cover for covering the cutout, so that the cover must first be removed from the cutout before the parking brake can be released. As already mentioned, the cover serves to prevent the ingress of dust and moisture and to prevent theft, since access to the blocking element and thus to the parking brake is blocked, so that only selected persons or services can access it. An opening tool is usually required to open the cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Other advantages and features of the invention will be apparent from the following description and the accompanying drawings, which are described with reference to the accompanying drawings. In the drawings:

[0032] Figure 1 is an exploded view of an electromechanical service brake according to the present invention;

[0033] Figure 2 The invention has an unlocking tool according to the invention. Figure 1 A plan view of an actuator of a service brake;

[0034] Figure 3 is a cross section through the service brake in the area of ​​the cutout and cover;

[0035] Figure 4 is a cross section through the electric service brake in the stopped state;

[0036] Figure 5 is a perspective view of an electromagnetic actuator and a blocking element used in a service brake;

[0037] Fig. 6A and Figure 6B is a perspective view of an unlocking tool according to the present invention;

[0038] Figure 7 shows a cross section of the actuator in a stopped state with an unlocking tool; and

[0039] Figure 8 A cross section of the actuator with the unlocking tool is shown in its open state. DETAILED DESCRIPTION

[0040] Figure 1 An electromechanical service brake 10 with an integrated electric parking brake 12 is shown. Here, the parking brake 12 and the electric motor 14 as well as the control unit 16 are surrounded by a housing 18. The housing 18 can also be Figure 2 Seen in.

[0041] The housing 18 is screwed to a bracket 19 of the electromechanical service brake 10 to be fastened to the vehicle and comprises an end wall 20 and a side wall 22. The end wall 20 and the side wall 22 have a connection to each other that cannot be released non-destructively. This means that the end wall 20 cannot be simply separated from the side wall 22 without causing damage to the parking brake 12 or at least its housing 18.

[0042] Additionally, a circuit board, not shown in the figures, is attached directly below the end wall 20, making front access to the electric parking brake 12 and its mechanism impossible.

[0043] The side wall 22 also has a cutout 24 which is covered by a cover 26 . Figure 2 The cutout 24 is shown without the cover 26, and Figure 3 A cross section is shown through the cutout 24 with a cover 26. As will be discussed in more detail further below, the cutout 24 is provided for allowing manual access to a blocking element of the parking brake in situations where electrical actuation of the parking brake is not possible.

[0044] The cutout 24 is a non-circular structure having at least one axially extending guide groove 28. In the embodiment shown in the figure, the cutout 24 has two guide grooves 28 (see Figure 2 As an alternative to the guide groove 28 , the cutout 24 can also have at least one axially extending guide rib.

[0045] The cutout 24 tapers conically toward the inside of the housing and is surrounded by a sleeve-like protrusion 30 which is integrally formed on the housing 18 and protrudes outward. The protrusion 30 has at least one slot 32.

[0046] The cutout 24 is covered by a cover 26. This cover is in particular a mushroom-shaped cover, which can also be referred to as a "plug". Due to its mushroom-shaped form, the cover 26 closes the cutout 24 and protrudes into the tapered portion of the cutout 24, more specifically, beyond said tapered portion.

[0047] The cover 26 has a hook 34 which engages behind the narrowest point of the cutout 24. This ensures that the cover 26 cannot accidentally come off. To remove the cover 26, the cover 26 has at least one notch 36 on the edge of the mushroom head, into which an opening tool (for example a special tool or a flat-head screwdriver) inserted via the slot 32 can engage.

[0048] A sealing element 38 is provided between the housing 18 and the cover 26. The sealing element 38 is preferably composed of an elastomer and is, for example, an O-ring. The sealing element 38 is clamped between the conical area of ​​the cutout 24 and the cover 26 to prevent the ingress of dust and / or moisture.

[0049] Figure 3 The cover 26 shown in FIG. 2 is additionally a pressure equalization element 40 between the interior of the housing 18 and the surrounding environment. For this purpose, a diaphragm 42 is integrated into the cover 26. The diaphragm 42 preferably consists of expanded polytetrafluoroethylene with a microporous structure and hydrophobic and / or oleophobic properties. Thus, the diaphragm 42 allows air and pressure to be exchanged between the interior of the housing 18 and the surrounding environment, but prevents the ingress of liquids and dirt.

[0050] Figure 2 Also shown is an unlocking tool 44 which is introduced into the cutout 24 in order to switch the parking brake 12 into the open state.

[0051] The unlocking tool 44 will be described in more detail after the electric parking brake 12 is described. However, the unlocking tool 44 is usually a special tool that can be used exclusively for breakdown services, towing services and workshops. This is to ensure that not just anyone can change the parking brake 12 from the stopped state to the open state, and in particular to prevent theft.

[0052] Figure 4 and Figure 7 and Figure 8 The housing 18 is shown without the end wall 20 so that the mechanism of the parking brake 12 is visible. In particular, the parking brake 12 comprises a single-arm lever forming a blocking element 46; in the closed state, the blocking element engages in a toothing 48 of a transmission 50 of the electromechanical service brake 10 and thus blocks the electromechanical service brake 10 in an effective manner. This locking state of the electric parking brake 12 can be achieved in Figure 4 and Figure 7 Seen in.

[0053] The blocking element 46 is moved to the stopped state and the open state by an electromagnetic actuator 52. The electromagnetic actuator 52 is preferably a bistable solenoid 54, such as Figure 5 As shown in the cross section.

[0054] The solenoid 54 includes two permanent magnets 56 and two series-connected coils 58. An armature 60 and an actuator plunger 62 are disposed within the coils 58 and permanent magnets 56.

[0055] Only the actuator plunger 62 projects out of the actuator housing 64; said actuator plunger is connected to a head 66 in which a pin 68 is supported.

[0056] The pin 68 provides a connection to the blocking element 46 , wherein the blocking element 46 shown here is a pawl. The pawl has a pivot bearing end 70 and teeth 72 that engage with the toothing 48 of the transmission 50.

[0057] The pawl also has an opening 74 in a region remote from the teeth 72 and located further from the pivot bearing end 70 than the teeth 72. The opening 74 is preferably a slot into which the pin 68 of the electromagnetic actuator 52 engages, so that a slot guide is formed. In the stopped state, the cutout 24 is symmetrically arranged above the head 66 of the actuator plunger 62 so that the cutout 24 is oriented orthogonally relative to the armature 60 and the motor shaft.

[0058] In the event of a malfunction of the parking brake 12, the cutout 24 allows manual actuation of the blocking element 46 from the outside in order to switch the parking brake 12 to the open state. Such a malfunction may be caused, for example, by a defective solenoid, a defective electric motor 14, a defective control unit 16 or an electrical malfunction.

[0059] The problem in the event of such a fault in the electronics is in particular the residual clamping forces which arise in the blocked state of the parking brake 12. These residual clamping forces may lie in the kilonewton range and thus make further travel impossible. However, since the transmission 50 is unloaded, the residual clamping forces can be reduced mechanically from the outside without damaging the force sensor arrangement in the process. Total losses are thus prevented and further travel is made possible relatively quickly.

[0060] In order to transfer the parking brake 12 into the released state, it is therefore necessary to build up a tension force by means of the electromechanical service brake 10 , which is no longer possible in the case of such a defect.

[0061] In order to manually switch the parking brake 12 to the open state in the event of an electrical failure, a Fig. 6A and Figure 6B An unlocking tool 44 is shown.

[0062] The unlocking tool 44 is a rod-shaped special tool. This means that the unlocking tool 44 is not defined by a standard and therefore cannot be purchased in a hardware store or tool trade. It can therefore be ensured that the parking brake 12 can only be released by a selected person or service.

[0063] Unlocking tool 44 (see Fig. 6A and Figure 6B ) has an insertion portion 76 and a retaining portion 78. Here, the insertion portion 76 comprises at least one axially extending guide rib 80, which forms a counterpart to the at least one guide groove 28 of the cutout 24. Alternatively, the insertion portion 76 may also comprise at least one axially extending guide groove.

[0064] Similar to the guide grooves 28, the guide ribs 80 are also arranged asymmetrically on the circumference of the unlocking tool 44 relative to the longitudinal center axis of the unlocking tool 44. In this way, a circumferential orientation of the unlocking tool 44 is ensured.

[0065] exist Fig. 6A and Figure 6B In the illustrated embodiment of the unlocking tool 44 , two guide ribs 80 are provided, and the angular interval between the two guide ribs 80 is not equal to 180 degrees.

[0066] In addition, the insertion portion 76 of the unlocking tool 44 is of fork-shaped design. Figure 6B As can be seen in FIG. 1 , the fork-shaped insertion portion 76 tapers in a wedge shape on one side and is flat on the other side. Thus, an end stop 82 is formed, which protrudes laterally and separates the insertion portion 76 from the retaining portion 78.

[0067] If the parking brake 12 needs to be manually switched to the open state due to an electrical defect of the electromechanical service brake 10, the cover 26 of the cutout 24 is first removed. To this end, an opening tool is inserted into the slot 32 of the projection 30 so that the opening tool can engage in the recess 36 of the cover 26 so that the cover 26 can be removed.

[0068] The unlocking tool 44 is then introduced into the interior of the housing 18 through the cutout 24. This creates a form fit between the unlocking tool 44 and the cutout 24 in the housing 18 of the electromechanical service brake 10, since the guide grooves 28 of the cutout 24 and the complementary guide ribs 80 on the unlocking tool 44 come into engagement. Thus, a unique circumferential orientation of the unlocking tool 44 is provided and it is ensured that the unlocking tool 44 is inserted into the housing 18 at the correct angle. This can be achieved in the case of a brake. Figure 7 Seen in.

[0069] Here, the fork-shaped insertion portion 76 of the unlocking tool 44, which tapers in a wedge shape, enters the gap between the electromagnetic actuator 52 and the head 66, so that the fork-shaped insertion portion 76 receives the actuator plunger 62. Due to the wedge-shaped insertion portion 76, similar to the wedge-shaped thrust mechanism, as the unlocking tool 44 is pushed in, an axial force and an axial stroke are applied to the actuator plunger 62. Therefore, the actuator plunger 62 moves in the opposite direction to the stroke application force, whereby the tooth 72 of the blocking element 46 pivots and disengages from the engagement with the toothed member 48 of the transmission 50.

[0070] The unlocking tool 44 is pushed into the housing 18 of the electromechanical service brake 10 until the end stop 82 is supported against the end side of the electromagnetic actuator 52. At this point, the engagement of the blocking element 46 is completely released and the transmission 50 can be rotated again, as shown in FIG. Figure 8 shown.

[0071] In an embodiment not shown in the figures, the cover 26 can also be screwed to the housing 18 of the electromechanical service brake 10. In this case, in particular, the cutout 24 has a thread. In the case of such a screw fastening, neither the recess 36 and the hook 34 of the cover 26 nor the slot 32 in the projection 30 are required. Furthermore, an opening tool is not necessary to open the cover 26, since this can simply be loosened.

[0072] Alternatively, the cover 26 can also be equipped with a safety lock in order to ensure a certain degree of protection against accidental and unauthorized opening. Therefore, an opening tool, which in principle can be a special tool, is again required to open the cover 26. The safety lock can, for example, involve a coding as in the case of locking wheel bolts or nuts. Alternatively, the cover 26 can also be designed so that it can be released only using a key (in particular a vehicle key), similar to a fuel tank lock.

Claims

1. An electromechanical service brake (10) having an integrated electric parking brake (12) and comprising an electric motor (14) and a control unit (16), wherein: The electric parking brake (12) comprises a blocking element (46) which, in the stopped state of the electric parking brake (12), mechanically blocks a transmission (50) of the electromechanical service brake (10), wherein the electric motor (14) and the transmission (50) are surrounded by a housing (18), the housing (18) having a cutout (24), the cutout (24) allowing the blocking element (46) to be manually actuated from the outside so that the blocking element (46) can be mechanically transferred from the outside from the stopped state to an open state, wherein in the open state the transmission (50) can move freely, and wherein the cutout (24) is a non-circular structure having at least one axially extending guide groove (28) and / or at least one axially extending guide rib.

2. The electromechanical service brake according to claim 1, characterized in that The cutout (24) tapers conically and is surrounded by a sleeve-like protrusion (30) which is integrally formed on the housing (18) and protrudes outward.

3. The electromechanical service brake (10) according to claim 1 or 2, characterized in that The cutout (24) is covered by a cover (26), in particular a mushroom-shaped cover (26), which is received in the cutout (24) and in the projection (30), wherein an opening tool is required to remove the cover (26), and wherein the projection (30) preferably has at least one slot (32) through which the opening tool can be laterally engaged on the cover (26) in order to remove the cover (26).

4. The electromechanical service brake (10) according to claim 3, characterized in that The cover (26) is a pressure equalization element (40) between the interior of the housing (18) and the surrounding environment, wherein a diaphragm (42) is integrated into the cover (26).

5. The electromechanical service brake (10) according to claim 3 or 4, characterized in that The cover (26) has a hook (34) that engages behind the narrowest point of the cutout (24).

6. Electromechanical service brake (10) according to any one of the preceding claims, characterized in that An electromagnetic actuator (52), in particular a bistable solenoid (54), is provided for moving the blocking element (46) into the resting state and the open state.

7. Electromechanical service brake (10) according to any one of the preceding claims, characterized in that The blocking element (46) is a pawl, wherein the pawl engages in a toothing (48) of the transmission (50), wherein in particular the pawl has a pivot bearing end (70) and has teeth (72) that engage in the toothing (48).

8. An unlocking tool (44) for transferring a blocking element (46) of an electric parking brake (12) according to any one of the preceding claims from the stopped state to the open state, wherein: The unlocking tool (44) is rod-shaped and has an insertion portion (76) and a holding portion (78), wherein the insertion portion (76) includes at least one axially extending guide rib (80) and / or at least one axially extending guide groove.

9. The unlocking tool (44) according to claim 8, characterized in that: If a plurality of guide ribs (80) and / or a plurality of guide grooves are provided, the plurality of guide ribs (80) and / or the plurality of guide grooves are arranged asymmetrically on the circumference relative to the longitudinal center axis of the unlocking tool (44), thereby ensuring a circumferential orientation of the unlocking tool (44).

10. The unlocking tool (44) according to claim 8 or 9, characterized in that: The unlocking tool (44) has a laterally protruding end stop (82) separating the insertion portion (76) from the retaining portion (78), wherein the end stop (82) limits the insertion of the unlocking tool (44) into the electric parking brake (12).

11. The unlocking tool (44) according to any one of claims 8 to 10, characterized in that The insertion section (76) of the unlocking tool (44) is of fork-shaped design and / or tapers in a wedge shape.

12. An assembly comprising an electromechanical service brake (10) according to any one of claims 1 to 7 and an unlocking tool (44) according to any one of claims 8 to 10, wherein: Insertion of the unlocking tool (44) into the cutout (24) in the housing (18) of the electromechanical service brake (10) produces a form fit by means of one or more guide grooves (28) in the cutout (24) and / or one or more axially extending guide ribs and complementary guide ribs (80) or guide grooves on the unlocking tool (44) coming into engagement, thereby resulting in a unique circumferential orientation of the unlocking tool (44).

13. The assembly according to claim 12, characterized in that The insertion portion (76) of the unlocking tool (44) is of fork-shaped design and tapers in a wedge shape, wherein the unlocking tool (44) can be inserted into the cutout (24) in a single circumferential orientation until the end stop (82), and is configured to pivot the pawl to the open state, wherein the fork-shaped insertion portion (76) of the unlocking tool (44) enters the gap between the electromagnetic actuator (52) and the pawl and increases the size of the gap.

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