Ratchet wheel assembly and electromechanical brake

Abstract

The invention relates to a ratchet wheel assembly (1) for blocking a ratchet wheel (6) of an electromechanical brake of a motor vehicle, - with a rotatable ratchet wheel (2) having a locking tooth (3), - with a shaft (4) rotatable about an axis of rotation (D), from which a pawl (5) protrudes to engage the locking teeth (3), - with an actuator (6) that is adjustable by electrical current, preferably linearly, and connected to the shaft for drive, - wherein the shaft (4) is rotatably adjustable by means of the actuator (6) between a blocking position in which the pawl (5) engages in the locking teeth (3) of the ratchet wheel (2) to block it, and a release position in which the pawl (5) is arranged at a distance from the ratchet wheel (2) to release it, - wherein the pawl (5) is connected to the shaft (4) in a rotationally fixed manner by means of a positive locking connection.

Description

[0001] The present invention relates to a ratchet wheel assembly for blocking a ratchet wheel of an electromechanical brake of a motor vehicle and to an electromechanical brake with such a ratchet wheel assembly.

[0002] A ratchet wheel assembly for an electromechanical brake, particularly an electromechanical parking brake, of a motor vehicle typically comprises a pawl with locking teeth and a rotatable ratchet wheel, the rotation of which can be selectively locked or unlocked by means of the pawl. To lock the ratchet wheel, the pawl engages with locking teeth typically provided on the ratchet wheel. To release the steering wheel, this engagement of the pawl with the locking teeth is disengaged by moving the pawl away from the ratchet wheel. The movement of the pawl is usually achieved by means of an adjustable actuator that interacts with the pawl.

[0003] Often, the pawl is pre-tensioned away from the ratchet wheel by means of a spring-loaded component to prevent the ratchet wheel from locking unintentionally during operation. By electrically energizing the actuator, it can precisely adjust the pawl towards the ratchet wheel until the pawl engages the ratchet wheel's locking teeth, thereby locking the ratchet wheel.

[0004] A disadvantage of such conventional ratchet wheel assemblies is that their design, with actuator, pawl and ratchet wheel, and possibly with a spring-elastic preload element, requires a comparatively large amount of installation space, which is often only available to a very limited extent, especially in a motor vehicle.

[0005] It is therefore an object of the present invention to demonstrate new approaches in the development of a ratchet wheel assembly as described above. In particular, an improved embodiment of a ratchet wheel assembly is to be created, which is characterized in particular by a reduced installation space requirement while maintaining high operational reliability.

[0006] This problem is solved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent patent claims.

[0007] The basic idea of ​​the invention is therefore to attach said pawl in a rotationally fixed manner to a shaft rotatable about an axis of rotation, wherein the pawl is attached to the shaft by means of a positive locking connection between the pawl and the shaft.

[0008] To adjust the pawl, the necessary adjusting force is not applied directly to the pawl by the actuator. Instead, in the proposed solution, the actuator exerts its force on the shaft. The resulting rotation of the shaft by the actuator allows the pawl to be adjusted between a locked position, in which the pawl engages the ratchet wheel and locks it, and an unlocked position, in which the pawl is positioned at a distance from the ratchet wheel, releasing it so that it can rotate.

[0009] Due to the positive-locking connection between the pawl and the shaft, high torques can be transmitted. This allows the pawl to be held stably in the set position. Furthermore, very little installation space is required, as the preload element described above is no longer needed. Likewise, the drive connection between the actuator and the shaft can be designed more simply than a conventional drive connection between an actuator and a pawl, since the actuator only needs to cause the shaft to rotate around its axis of rotation through a specific angle. Because the actuator can be positioned at a distance from the pawl, more flexible use of the available installation space is also possible.

[0010] Following the preceding concept of the invention, a ratchet wheel assembly according to the invention comprises a rotatable ratchet wheel and a locking toothing, preferably arranged on the outer circumference. Furthermore, the ratchet wheel assembly comprises a shaft rotatable about an axis of rotation, preferably cylindrical in shape, from which a pawl projects radially outwards for engaging the locking toothing. The shaft and the pawl are formed separately, i.e., as two parts. Advantageously, the axis of rotation can extend along a central longitudinal axis of the shaft.

[0011] Furthermore, the ratchet wheel assembly according to the invention comprises an actuator that is adjustable by means of an electrical current, preferably linear, and is connected to the shaft for drive purposes. The shaft is designed to be rotatably adjustable by means of the actuator between a locking position, in which the pawl engages in the ratchet wheel's locking teeth to lock it, and a release position, in which the pawl is positioned at a distance from the ratchet wheel to allow it to rotate. According to the invention, the pawl is connected to the shaft in a rotationally fixed manner by means of a positive locking connection.

[0012] According to an advantageous further development, a recess can be formed on the shaft to create the positive-locking connection between the shaft and the pawl. A connecting section of the pawl, designed to be complementary to the recess, engages in this recess. Alternatively, the same recess can be formed on the pawl to create the positive-locking connection, with a connecting section of the shaft, designed to be complementary to the recess, engaging in this recess. Both alternatives simplify the manufacture of the ratchet assembly and thus enable further cost reductions. At the same time, such a positive-locking connection allows the high torques typically encountered during operation to be transmitted from the shaft to the pawl.

[0013] In a preferred embodiment of the ratchet wheel assembly according to the invention, the shaft with the pawl has a center of mass in a cross-section perpendicular to the axis of rotation, which coincides with the pivot point defined in the cross-section by the axis of rotation. Alternatively, in this embodiment, the center of mass can be located at a distance from the pivot point of at most 5 mm. In both alternative variants, a spring-elastic preload element can optionally be provided, which preloads the pawl towards the release position to prevent unintentional locking of the ratchet wheel. By designing the pawl with its center of mass in or near the axis of rotation, it is possible to reduce the force level required for said spring-elastic preload element to reliably prevent unintentional locking by interfering forces, and thus to make it more cost-effective.In this embodiment, components of a valve assembly can therefore be used particularly preferably for the spring-elastic preload element and also for the actuator.

[0014] In another preferred embodiment of the ratchet wheel assembly according to the invention, in addition to the positive-locking connection between the shaft and the pawl that is essential to the invention, the actuator is also positively connected to the shaft. This not only allows reliable and precise adjustment of the shaft during rotation about its axis of rotation, but also, due to the permanently present connection between the shaft and the actuator, ensures that the shaft is reliably held in the (target) rotational position set by the actuator. This increases the operational reliability of an electromechanical brake equipped with the ratchet wheel assembly according to the invention.Since the actuator and shaft are connected in all positions of the pawl, it is also unnecessary to provide a spring-elastic component for pre-tensioning the pawl, as is often the case with conventional ratchet wheel assemblies, to prevent unwanted adjustment of the pawl due to virtually "random" external forces exerted on the pawl.

[0015] According to an advantageous further development, a projection connected to the actuator can extend from the shaft to form said positive-locking connection. Particularly preferably, this projection can engage in a recess provided on the actuator. This embodiment provides a technically very simple and therefore cost-effective drive connection between the actuator and the shaft.

[0016] In another preferred embodiment, the actuator can have an axially extending sleeve in which an adjusting element is arranged so as to be axially adjustable. In this embodiment, a through-opening is formed in the sleeve, which is penetrated by the extension. Furthermore, the extension penetrating the through-opening is connected to the adjusting element by means of a press fit. In this way, a particularly stable drive connection between the actuator and the shaft can be achieved.

[0017] The sleeve can preferably be formed from a deep-drawn part. Alternatively or additionally, in this variant, the adjusting element can be formed by a roller bearing pin. This variant results in particularly low manufacturing costs.

[0018] According to another advantageous embodiment, a toothed connection can be provided on both the actuator and the shaft to create a positive-locking connection between them. In this embodiment, the two toothed connections interlock positively. This also allows for a reliable, yet simple and therefore cost-effective drive connection between the shaft and the actuator.

[0019] In another preferred embodiment, the actuator can be part of an electrically powered valve device, in particular an exhaust valve, which can be adjusted between an open state and a closed state.

[0020] 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.

[0021] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0022] 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.

[0023] They show, schematically: Fig. 1 in a partial view an example of a ratchet wheel assembly according to the invention, Fig. 2an enlarged view of the ratchet wheel assembly in the area of ​​the shaft and the pawl, Fig. 3 a variant in which the actuator has a sleeve and an adjusting element movably arranged in the sleeve, Fig. 4The pawl in a cross-section perpendicular to the axis of rotation.

[0024] The Fig. Figure 1 illustrates in a partial view an example of a ratchet wheel assembly 1 according to the invention for locking a ratchet wheel 2 of an electromechanical brake of a motor vehicle. The ratchet wheel assembly 1 comprises a ratchet wheel 2 rotatable about a pivot axis, which has a locking toothing 3 on its outer circumference 13.

[0025] According to Fig. 2 The ratchet wheel assembly 1 also includes a shaft 4 rotatable about a rotational axis D with a cylindrical geometric shape, from which a pawl 5 projects radially outwards for engaging with the locking teeth 3. The Fig. Figure 2 shows an enlarged view of the ratchet assembly 1 in the area of ​​the shaft 4. Accordingly, the ratchet assembly 1 also includes an actuator 6, which is adjustable by means of an electrical current and is connected to the shaft 4 for adjusting its position. The shaft 4 can be rotated about the axis of rotation D by means of the actuator 8, which in this example corresponds to a central longitudinal axis M of the shaft 4. This allows the shaft 4 to be moved between a locking position (not shown in the figures), in which the pawl 5 engages in the locking teeth 3 of the ratchet wheel 2, and a position in Fig. The release position shown in 1 can be adjusted, in which the locking pawl 5 is arranged at a distance from the ratchet wheel 2 to release it.

[0026] Advantageously, the pawl 5 can be connected to the shaft 4 in a rotationally fixed manner by means of a positive locking connection (not shown). To form this positive locking connection between the shaft 4 and the pawl 5, a recess (not shown) can be formed on the shaft 4, into which a connecting section of the pawl 5, designed to be complementary to the recess, engages (also not shown).

[0027] How the representation of Fig. As illustrated in Figure 2, the actuator 8 can also be positively connected to the shaft 4. To form this positive connection, a projection 9 connected to the actuator 8 can extend from the shaft 4. The projection 9 can then engage in a recess provided on the actuator 8 (in the perspective of the Fig. 2. not recognizable) intervene.

[0028] According to a Fig. In the variant shown in example 3, the actuator 8 can have an axially extending sleeve 10 in which an adjusting element 6 of the actuator 8 is arranged so as to be axially adjustable. The sleeve 10 can, in turn, have a through-opening (not shown) through which the extension 9 passes. Furthermore, the extension 9, which passes through the through-opening, is connected to the adjusting element 6 by means of a press fit. The sleeve 10 can be formed by a deep-drawn part. The adjusting element 6 can be formed by a roller bearing pin.

[0029] In a variant not shown in the figures, a toothed section can be provided on both the actuator 8 and the shaft 4 to form the positive-locking connection between the actuator 8 and the shaft 4. In this further development, the two toothed sections mesh positively with each other.

[0030] The Fig.Figure 4 shows the pawl 5 in a cross-section perpendicular to the axis of rotation D. Accordingly, the pawl 5 has a center of mass MS in this cross-section, which coincides with the pivot point DP defined by the axis of rotation D. In an alternative variant (not shown), the center of mass in the cross-section can be located at a distance from the pivot point DP of at most 5 mm.

Claims

[1] Ratchet wheel assembly (1) for locking a ratchet wheel (2) of an electromechanical brake of a motor vehicle, - with a rotatable ratchet wheel (2) having a locking tooth (3), - with a shaft (4) rotatable about an axis of rotation (D), from which a pawl (5) protrudes to engage the locking teeth (3), - with an actuator (6) which is adjustable by electrical current, preferably linearly, and which is connected to the shaft (4) for drive purposes, - wherein the shaft (4) is rotatably adjustable by means of the actuator (6) between a blocking position in which the pawl (5) engages in the locking teeth (3) of the ratchet wheel (2) to block it, and a release position in which the pawl (5) is arranged at a distance from the ratchet wheel (2) to release it, - wherein the pawl (5) is connected to the shaft (4) in a rotationally fixed manner by means of a positive locking connection. [2] Ratchet wheel assembly according to claim 1, characterized by , that - to form a 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 complementarily to the recess engages; or that - to form the positive locking connection on the pawl (5) a recess is formed into which a connecting section of the shaft (4) designed complementary to the recess engages. [3] Ratchet wheel assembly according to claim 1 or 2, characterized by , that in a cross-section perpendicular to the axis of rotation (D) the pawl (5) has a center of mass which coincides with the pivot point (DP) defined by the axis of rotation (D) or is located at a distance from the pivot point (DP) which is at most 5 mm. [4] Ratchet wheel assembly according to any one of claims 1 to 3, characterized by, that the actuator (6) is positively connected to the shaft (4). [5] Ratchet wheel assembly according to claim 4, characterized by , that to form the positive locking connection between shaft (4) and actuator (8) a projection (9) connected to the actuator (8) extends from the shaft (4). [6] Ratchet wheel assembly according to claim 5, characterized by , that - the actuator (8) has an axially extending sleeve (10) in which an adjusting element (6) is arranged in an axially adjustable manner, - a through-opening is formed in the sleeve (10) through which the extension (9) passes, - the extension (9) is connected to the adjusting element (6) by means of a press connection. [7] Ratchet wheel assembly according to claim 6, characterized by , that - the sleeve (10) is formed by a deep-drawn part; or / and that - the adjusting element (6) is formed by a roller bearing pin. [8] Ratchet wheel assembly according to claim 4, characterized by , that to form the positive locking connection between actuator (8) and shaft (4) a toothing is provided on the actuator (8) and on the shaft (4) respectively and that the two toothings engage positively with each other. [9] Ratchet wheel assembly according to one of the preceding claims characterized by , that - the actuator (8) is part of an electrically powered valve assembly adjustable between an open state and a closed state, in particular an outlet valve. [10] Electromechanical brake, in particular parking brake, with a ratchet wheel assembly according to one of the preceding claims.

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