Pawl device for blocking a ratchet wheel of an electromechanical brake of a motor vehicle

Abstract

The invention relates to a pawl device (1) for blocking a ratchet wheel of an electromechanical brake of a motor vehicle, comprising: • a pawl unit (2), which comprises a first housing (3) and a rotatably mounted shaft (4), from which a pawl (5), connected to the shaft (4) for conjoint rotation, for engaging a ratchet wheel (11) projects; • an actuator unit (6), which is separate from the pawl unit (2) and comprises a second housing (7) and an actuator (8) mounted so as to be displaceable along an adjusting direction (V), preferably linearly, and which is drivingly connected to the shaft (4) in order to adjust same, • wherein a (first) material (M1) of the pawl unit (2) has a higher strength than a (second) material (M2) of the actuator unit (6).

Description

[0001] R. 412631

[0002] 1

[0003] Description

[0004] Title:

[0005] Locking pawl device for blocking a ratchet wheel of an electromechanical brake of a motor vehicle

[0006] The present invention relates to a pawl device for blocking a ratchet wheel of an electromechanical brake of a motor vehicle. The invention further relates to a ratchet wheel assembly with such a pawl device and to an electromechanical brake with such a ratchet wheel assembly.

[0007] A pawl assembly for an electromechanical brake, particularly an electromechanical parking brake, of a motor vehicle typically comprises a pawl and a rotatable ratchet wheel, typically connected to a spindle for actuating a braking effect. The pawl's rotation can be selectively blocked or released. To block the ratchet wheel, the pawl engages with a locking tooth typically provided on the ratchet wheel. To release the ratchet wheel, this engagement of the pawl with the locking tooth is disengaged, for example, by moving the pawl away from the ratchet wheel or by disengaging a self-locking mechanism by actuating the ratchet wheel. The movement of the pawl is effected by an actuator unit, which includes an adjustable actuator that interacts with the pawl.

[0008] When the pawl is engaged with the ratchet wheel, very high forces in the kilonewton range can be exerted. This necessitates the use of materials with very high strength for the pawl and ratchet wheel or ratchet teeth. Therefore, steel is often used for both the pawl and the ratchet wheel. This results in correspondingly high R. 412631

[0009] 2

[0010] This entails additional costs, which has a negative impact on the manufacturing costs of the entire pawl assembly or the electromechanical brake using this pawl assembly.

[0011] It is therefore an object of the present invention to demonstrate new approaches in the development of pawl devices. In particular, an improved embodiment of such a pawl device is to be created that is cost-effective to manufacture and requires little installation space. At the same time, the unrestricted functionality of the pawl device, even during long-term operation in an electromechanical brake, is to be guaranteed.

[0012] This problem is solved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent claims.

[0013] The basic idea of ​​the invention is therefore to manufacture the components of the aforementioned actuator unit in a pawl mechanism from a material with lower strength than the material of the pawl unit itself. This takes advantage of the fact that the components of the pawl unit are subjected to significantly greater forces during operation than the components of the actuator unit. The forces acting on the pawl unit, and in particular on the ratchet wheel with its locking teeth and on the pawl itself, can, as mentioned above, be in the kilonewton range. In contrast, the forces acting on the actuator of the actuator unit are considerably lower and often only in the double-digit newton range. In practice, values ​​between 10 N and 50 N are achieved. It follows that the material of the actuator unit is subjected to considerably lower loads than the material of the pawl unit.Therefore, it is sufficient to design only the pawl unit with a correspondingly high strength if the pawl mechanism is to be designed for reliable operation. This is not necessary for the actuator unit (R. 412631).

[0014] 3

[0015] In the pawl device according to the invention, the strength of the material used is thus adapted to the forces ultimately acting on the material during operation.

[0016] According to the above invention, a pawl device comprises a pawl unit and an actuator unit designed separately from the pawl unit. The pawl unit comprises a first housing and a shaft rotatably mounted on the first housing, from which a pawl protrudes and is non-rotatably connected to the shaft for engaging a ratchet wheel. The actuator unit comprises a second housing designed separately from the first housing and an actuator mounted on the second housing so as to be adjustable along an adjustment direction, preferably linearly. The actuator is connected to the shaft for driving or adjusting it.

[0017] According to the invention, a first material of the pawl unit exhibits higher strength than a second material of the actuator unit. This applies in particular when the pawl, locking teeth, and first housing of the pawl unit are made of a single material, and alternatively or additionally when the actuator and second housing of the actuator unit are made of a single material.

[0018] In any case, in the pawl assembly according to the invention, the first material of the pawl and the locking teeth of the ratchet wheel, and in particular of the entire ratchet wheel, of the pawl assembly exhibits a higher strength than the material of the actuator of the actuator unit. Preferably, the material of the first housing of the pawl assembly can exhibit a higher strength than the material of the second housing of the actuator unit. This results in cost advantages.

[0019] In another preferred embodiment, the at least (first) material of the pawl has a higher strength than the second material of the actuator. This results in further cost advantages. R. 412631

[0020] 4

[0021] In another preferred embodiment, the first material of the first housing has a higher strength than the second material of the second housing. This results in cost advantages in the manufacture of the second housing.

[0022] In a further preferred embodiment, the first material can be a metal, in particular 100Cr6 steel. Alternatively or additionally, in this embodiment, the second material can be a light metal, in particular aluminum, or a plastic.

[0023] Preferably, the metal can be 100Cr6 steel, including MIM steel. Alternatively or additionally, the lightweight metal aluminum can be used in this variant. Alternatively or additionally, the plastic PA6.6 can be used in this embodiment.

[0024] According to an advantageous embodiment, the pawl unit and the actuator unit can be detachably connected to one another. This facilitates the assembly of the entire pawl assembly, even if, in accordance with the inventive concept, materials with different strengths are used for the pawl unit and the actuator unit.

[0025] In another preferred embodiment, the pawl can be connected to the shaft in a rotationally fixed manner by means of a positive-locking connection. This simplifies the manufacture of the pawl unit and thus leads to a further reduction in manufacturing costs. At the same time, such a positive-locking connection allows very high forces to be transmitted from the shaft to the pawl, as required because they regularly occur in practical operation.

[0026] A recess can be particularly useful in forming a positive-locking connection between the shaft and the pawl on the shaft. A connecting section of the pawl, designed to be complementary to the recess, can engage in this recess. Alternatively, see R. 412631

[0027] 5

[0028] The recess on the pawl is designed to form the aforementioned positive-locking connection, so that a connecting section of the shaft, designed to complement this recess, engages in it. Both variants are very easy to implement and therefore offer further cost advantages.

[0029] According to another, yet also cost-effectively implementable, advantageous further development, a toothing can be provided for the formation of the positive locking connection on the actuator and on the shaft for realizing the drive connection between actuator and shaft, wherein the two toothings engage positively with each other.

[0030] The invention further relates to a ratchet wheel assembly for an electric parking brake of a motor vehicle. The ratchet wheel assembly comprises a rotatable ratchet wheel having locking teeth. Furthermore, the ratchet wheel assembly according to the invention includes a locking pawl device as previously described, so that the advantages of the locking pawl device explained above are transferred to the ratchet wheel assembly according to the invention. In the ratchet wheel assembly according to the invention, the shaft of the locking pawl device is rotatably mounted about an axis of rotation between a locking position and a release position by means of the actuator. In the locking position, the pawl engages in the locking teeth of the ratchet wheel to lock it. In the release position, the pawl is arranged at a distance from the ratchet wheel to release it.

[0031] Finally, the invention relates to an electromechanical brake, in particular a parking brake, with a ratchet wheel arrangement according to the invention as described above, so that the advantages of the pawl device according to the invention, explained above, are also transferred to the electromechanical brake or parking brake according to the invention. R. 412631

[0032] 6

[0033] Further important features and advantages of the invention will become apparent from the dependent claims, the drawings and the associated description of the figures based on the drawings.

[0034] It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0035] Preferred embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0036] They show, schematically:

[0037] Fig. 1 and in a perspective view an example of a ratchet device according to the invention,

[0038] Fig. 2 shows a partial representation of an example of a ratchet wheel arrangement according to the invention.

[0039] Figure 1 shows, in a highly simplified perspective view, an example of a pawl device 1 according to the invention for blocking a ratchet wheel (not shown in Figure 1, see Figure 2) of an electromechanical brake of a motor vehicle. The pawl device according to the invention comprises a pawl unit 2 and an actuator unit 6 designed separately from the pawl unit 2. The pawl unit 2 and the actuator unit 6 can be detachably fastened to one another, for example by means of a screw connection (not shown). R. 412631

[0040] 7

[0041] The pawl unit 2 comprises a first housing 3 and a shaft 4 rotatably mounted on the first housing 3. A pawl 5, which engages with a ratchet wheel 11 (not shown in Figure 1, see Figure 2), projects from the shaft 4 and is non-rotatably connected to it. The actuator unit 6, in this example, comprises a second housing 7, which is separate from the first housing 3, and an actuator 8 mounted on the second housing 7 so as to be linearly adjustable along an adjustment direction V. The actuator 8 is connected to the shaft 4 for driving or adjusting it.

[0042] The first material M1 of the pawl unit 2 with shaft 4 and pawl 5 has a higher strength than the second material M2 of the actuator unit 6. In the example, the first material M1 of the pawl 5 has a higher strength than the second material M2 of the actuator 8. Similarly, in the example scenario, the first material M1 of the first housing 3 has a higher strength than the second material M2 of the second housing 7. The first material M1 can be a metal, for example, steel. The second material M1 can be a light metal, for example, aluminum, or a plastic, for example, XXX (©Inventor: please provide an example).

[0043] The pawl 5 can be connected to the shaft 4 in a rotationally fixed manner by means of a positive-locking connection (not shown in Figure 1). To form the positive-locking connection between shaft 4 and pawl 5, a recess is formed on the shaft (not shown). A connecting section of the pawl, designed to be complementary to the recess, engages in this recess. Alternatively, instead of providing a recess, it is also conceivable to provide a toothed section on both the actuator 8 and the shaft 4 to form the aforementioned positive-locking connection between the actuator 8 and the shaft 4, with the two toothed sections engaging positively with each other (not shown).

[0044] The pawl assembly 1 described above can be part of a ratchet wheel assembly 10 according to the invention, shown in a partial view in Figure 2, for an electric parking brake of a motor vehicle 10. The ratchet wheel assembly 10 comprises, in addition to the pawl assembly 1, a rotatable ratchet wheel R. 412631

[0045] 8

[0046] 11, which has a locking tooth 12 on its outer circumference 13. The shaft 4, and thus also the pawl 5 of the pawl assembly 1, is rotatable by means of the actuator 8 between a locking position, in which the pawl 5 engages in the locking tooth 12 to lock the ratchet wheel 11 (not shown in Figure 2), and a release position shown in Figure 2, in which the pawl 5 is arranged at a distance from the ratchet wheel 11 to release it. In the release position, the ratchet wheel 11 can therefore rotate; in the locking position, however, no rotational movement is possible.

Claims

R. 412631 9 Patent claims 1. Locking pawl device (1) for blocking a ratchet wheel (11) of an electromechanical brake of a motor vehicle, - with a pawl unit (2) comprising a first housing (3) and a rotatably mounted shaft (4), from which a pawl (5) protrudes and is non-rotatably connected to the shaft (4) for engaging the ratchet wheel (11), with an actuator unit (6) designed separately from the pawl unit (2), comprising a second housing (7) and an actuator (8) adjustable along an adjustment direction (V), preferably linear, which is connected to the shaft (4) for driving adjustment, - wherein a first material (M1) of the pawl unit (2) has a higher strength than a second material (M2) of the actuator unit (6).

2. Locking pawl device according to claim 1, characterized in that at least the first material (M1) of the locking pawl (5) has a higher strength than the second material M2 of the actuator (8).

3. Locking pawl device according to claim 1 or 2, characterized in that at least the first material (M1) of the first housing (3) has a higher strength than the second material (M2) of the second housing (7).

4. Locking pawl device according to one of claims 1 to 3, characterized in that the first material (M1) is a metal, in particular XXX (©Inventor: please give examples); and / or the second material (M2) is a light metal or a plastic 5. Locking pawl device according to claim 4, characterized in that R. 412631 10. that the metal is steel and / or that the light metal is aluminum and / or that the plastic is PA 6.6 6. Locking pawl device according to one of the preceding claims, characterized in that the locking pawl unit (2) and the actuator unit (6) are detachably connected to each other.

7. Pawl device according to one of the preceding claims, characterized in that the pawl (5) is connected to the shaft (4) in a rotationally fixed manner by means of a positive locking connection.

8. Pawl device according to claim 7, characterized in that, to form the positive locking connection between shaft (4) and pawl (5), a recess is formed on the shaft (4) into which a connecting section of the pawl (5) designed complementary to the recess engages; or that, to form the positive locking connection, a recess is formed on the pawl (5) into which a connecting section of the shaft (4) designed complementary to the recess engages.

9. Pawl locking device according to claim 7, characterized in that a toothing is provided on the actuator (8) and on the shaft (4) to form the positive locking connection and that the two toothings engage positively with each other.

10. Ratchet wheel arrangement (10) for an electric parking brake of a motor vehicle, comprising a rotatable ratchet wheel (11) having a locking tooth (12), R. 412631 11. A pawl assembly (1) according to one of the preceding claims, wherein the shaft (4) with the pawl (5) of the pawl assembly (1) is rotatably adjustable by means of the actuator (8) between a locking position in which the pawl (5) engages in the locking teeth (12) of the ratchet wheel (11) to lock it, and a release position in which the pawl (5) is arranged at a distance from the ratchet wheel (11) to release it.

11. Electromechanical brake, in particular parking brake, with a ratchet wheel assembly according to one of the preceding claims.

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