Drum brake and drive brake unit

Abstract

The present invention relates to a drum brake (3) for a drive brake unit (1), comprising at least one brake shoe (4), a brake drum (5), an actuator mechanism (6), and a base plate (7). The actuator mechanism (6) is configured to move the brake shoe (4) against the brake drum (5) to generate a braking torque. The integration of such a drum brake into a drive brake unit with a wheel-integrated electric motor is to be improved. For this purpose, at least one sliding element (8) is arranged between the base plate (7) and the at least one brake shoe (4), which guides the brake shoe (4) during its movement against the brake drum (5). This eliminates the need for a heavy base plate made of a wear-resistant material. The invention further relates to a drive brake unit (1) comprising a wheel-integrated electric motor (2) and a drum brake (3) of this type arranged axially overlapping with the electric motor (2).

Description

[0001] The present invention relates to a drum brake for a drive brake unit, comprising at least one brake shoe, a brake drum, an actuator mechanism, and a base plate, wherein the actuator mechanism is configured to displace the brake shoe against the brake drum to generate a braking torque. The invention further relates to a drive brake unit comprising a wheel-integrated electric motor and a drum brake of the aforementioned type arranged axially overlapping with the electric motor.

[0002] Such a drum brake is known, for example, from EP2741933B1, in which a drum brake is combined with a wheel-integrated electric motor to form a drive brake unit. An actuator mechanism and the brake shoes of the drum brake are attached to an axially outer base of a pot-shaped stator housing. The brake drum is integrally formed with the drive rotor.

[0003] When integrating drum brakes and wheel-integrated electric motors into drive brake units, the question arises as to what the actuator mechanism and brake shoes should be attached to. While the steel base plate typically used for this purpose is stable and abrasion-resistant, it also significantly increases the weight of the drive brake unit. At the same time, wheel-integrated electric motors often use lighter but less abrasion-resistant materials for stator elements or stator plates, which therefore cannot always be readily used as a replacement for the drum brake base plate. This is problematic because the brake shoes are usually in sliding contact with the underlying base plate during relocation, and depending on the material combination, this can lead to considerable abrasion, reducing the service life of the drive brake unit.

[0004] The invention is therefore based on the objective of providing a drum brake of the type mentioned above with improved integrability into a drive brake unit.

[0005] According to the invention, this problem is solved by a drum brake of the type mentioned above, which is characterized in that at least one sliding element is arranged between the base plate and the at least one brake shoe, which guides the brake shoe when it is moved against the brake drum.

[0006] This design means that the base plate itself no longer has to perform the function of guiding the brake shoe and is therefore not exposed to the abrasion stress caused by the brake shoe, which is usually made of a hard material.

[0007] In this document, "axial" or "axial direction" refers to the direction parallel to the axis of rotation of the vehicle wheel or brake drum, while "radial" or "radial direction" refers to the direction(s) perpendicular to said axis of rotation. In this document, a drive brake unit is defined as a combination of a friction brake and a wheel-integrated electric motor. A brake shoe is defined as the carrier of one or more brake linings.

[0008] The drum brake preferably comprises two brake shoes. Preferably, a brake lining is attached circumferentially to each brake shoe, which can be brought into contact with the brake drum to generate a braking torque. The term "brake shoe" therefore refers in particular to the supporting structure of the brake lining. The actuator mechanism and a return mechanism can be connected to the brake shoe. Preferably, no brake lining is arranged on the brake shoe in the area of ​​the sliding element.

[0009] Preferred embodiments and further developments of the invention can be found in the respective dependent claims.

[0010] Preferably, the base plate is made essentially of a first material and the at least one brake shoe is made essentially of a second material, wherein the hardness of the first material is lower than the hardness of the second material. The drum brake according to the invention is particularly advantageous for such material combinations, since the at least one sliding element prevents abrasion of the softer material of the base plate.

[0011] In one embodiment, the base plate consists essentially of aluminum and the brake shoe consists essentially of steel. "Essentially" here can be understood to mean that the base plate or the brake shoe consists of more than 50 percent by weight of the aforementioned materials. The drum brake according to the invention is particularly advantageous for these material combinations, since sliding of steel on aluminum would lead to considerable abrasion, which is prevented by the sliding element.

[0012] Preferably, the sliding element consists substantially of a wear-resistant material. "Substantially" here can be understood to mean that the sliding element consists of more than 50 percent by weight of a wear-resistant material. The term "wear-resistant" can be defined, for example, according to DIN 50320.

[0013] It is preferred if the sliding element consists substantially of one of the following materials: acetal, nylon, ultra-high molecular weight polyethylene, polyphenylene sulfide, polyetheretherketone, polyamide-imide, polytetrafluoroethylene, steel, or a ceramic material. These materials exhibit high wear resistance. "Substantially" can also be understood here to mean that the sliding element consists of more than 50 percent by weight of one of the aforementioned materials.

[0014] In one embodiment, at least two, preferably three, sliding elements are arranged between the brake shoe and the base plate for each brake shoe. Therefore, with two brake shoes, at least four, preferably six, sliding elements are arranged between the brake shoes and the base plate.

[0015] Preferably, the sliding elements are arranged along a circle around the axis of rotation of the brake drum. Preferably, the sliding elements cover less than 20%, and particularly preferably less than 10%, of the radial outer circumference of the brake shoe(s). This limits friction and saves material.

[0016] In one embodiment, the sliding element is attached to the base plate, in particular by a frictional connection and / or a positive-locking connection. The sliding element (or elements) can, by virtue of its attachment to the base plate, act as a spacer between the base plate and the brake shoe.

[0017] Preferably, a connecting section is attached to the sliding element, which is designed to be guided through a connecting opening in the base plate to create a frictional and / or positive locking connection between the sliding element and the base plate. The connecting section may include a thread that fits a mating thread in the connecting opening to create a screw connection. Alternatively, the connecting section may be designed as a plug connector, e.g., with a circumferential locking projection that is designed to engage on a side of the base plate opposite the sliding element.

[0018] Preferably, at least two sliding elements are connected by a connecting bridge. The connecting bridge serves, among other things, as a retaining device, thus reducing the number of small individual parts to handle during assembly. The connecting bridge is preferably designed as a web with a smaller cross-section than the sliding elements. The connecting bridge can be formed integrally with the sliding elements.

[0019] Preferably, all sliding elements of each brake shoe are connected in series by connecting bridges. Particularly preferably, for each pair of brake shoes, a group of three sliding elements is provided, arranged in series along a chain connected by two connecting bridges.

[0020] The invention further relates to a drive brake unit comprising a wheel-integrated electric motor and a drum brake arranged axially overlapping with the electric motor according to one of the preceding embodiments. The drum brake according to the invention can be particularly well integrated into such a drive brake unit. This allows the overall weight of the drive brake unit to be kept low without negatively affecting its service life. The electric motor can comprise a drive stator and a drive rotor.

[0021] Preferably, a winding section of the drive stator is also attached to the base plate. The base plate then serves both as a guide for the brake shoes and as a support for the winding section. The winding section can extend from the base plate essentially in the axial direction. The winding section is preferably arranged on the same side of the base plate as the brake drum.

[0022] Preferably, the electric motor is a double-rotor radial flux motor comprising a winding section arranged radially between an outer rotor and an inner rotor. The electric motor may include a drive rotor that is essentially cup-shaped, with the outer rotor forming the radial outer wall of the drive rotor and the inner rotor forming a flange on a cup base of the drive rotor. The drive rotor may be attached, together with the brake drum, to a rotatable inner section of the wheel bearing.

[0023] In one embodiment, the drum brake is arranged radially inside and axially essentially at the same level as the winding section and / or the outer rotor and / or the inner rotor. This allows for a particularly space-efficient arrangement of the drum brake, which is especially well-suited for combination with radially large twin-rotor radial flux motors. "Axially essentially at the same level" means that the drum brake overlaps the respective other component for at least 50% of its axial length.

[0024] Preferably, a wheel bearing is arranged radially inside the at least one brake shoe and axially overlapping with the at least one brake shoe, with a stationary outer ring of the wheel bearing being connected to the base plate. A rotatable inner section of the wheel bearing may be connected to the brake drum and / or the drive rotor.

[0025] Further details of the invention will become apparent from the description of the illustrated embodiments and the attached claims.

[0026] The drawings show: Fig. 1 an isometric partial sectional view of a drive brake unit according to the invention, Fig. 2 a detailed view of a brake shoe on a sliding element, Fig. 3 a first embodiment of a base plate with sliding elements, and Fig. 4 a partial representation of a second embodiment of a base plate with sliding elements.

[0027] In the following detailed description of preferred embodiments, the same reference numerals denote essentially identical or identical parts in or on these embodiments. However, for better clarity of the invention, the preferred embodiments shown in the figures are not always drawn to scale.

[0028] Fig. Figure 1 shows a drive brake unit 1 according to the invention comprising a wheel-integrated electric motor 2 and a drum brake 3 arranged axially overlapping with the electric motor 2. The drum brake 3 comprises two brake shoes 4, a brake drum 5, an actuator mechanism 6, and a base plate 7. The actuator mechanism 6 is configured to displace the brake shoes 4 against the brake drum 5 to generate a braking torque. The actuator mechanism 5 and the brake shoes 4 are at least partially attached to the base plate 7.

[0029] Between the base plate 7 and the brake shoes 4, several sliding elements 8 are arranged (here a total of six), which guide the brake shoes 4 when they are moved against the brake drum 5.

[0030] The drum brake comprises two brake shoes 4. A brake lining 9 is attached circumferentially to each brake shoe 4, which can be brought into engagement with the brake drum 5 to generate a braking torque. The term brake shoe 4 therefore refers in particular to the supporting structure of the brake lining 9. The actuator mechanism 6 and one or more return mechanisms can be connected to the brake shoes 4. Preferably, no brake lining 9 is arranged on the respective brake shoe 4 in the areas of the sliding element 8.

[0031] The base plate 7 is essentially made of a first material (e.g., aluminum), and the brake shoes 4 are essentially made of a second material (e.g., steel). The sliding elements 8 prevent abrasion of the softer material of the base plate 7. The base plate 7 can also be made entirely of aluminum and / or the brake shoe can be made entirely of steel.

[0032] For clarity, one winding section is not shown, but it can be attached to the base plate 7 as an axially extending flange and extend into a drive rotor 10, in particular radially between an outer rotor 11 and an inner rotor 12. The winding section is preferably arranged on the same side of the base plate 7 as the brake drum 5. The drive rotor 10 can be attached together with the brake drum 5 to a rotatable inner section 13 of the wheel bearing.

[0033] Fig. Figure 2 shows a detailed view of another embodiment of a drum brake 3 according to the invention. The only difference from the previous embodiment is that Fig. 1. Here, the sliding elements 8 have a rectangular shape with rounded corners, while in Fig. 1. have a circular disk shape.

[0034] Furthermore, it can be seen here that a fixed outer ring 14 of the wheel bearing is connected to the base plate 7. A counter bearing 15 supports the brake shoes 4 and is arranged 180° to the brake cylinder of the actuator mechanism 6 in the direction of rotation (compare Fig. 1) A return mechanism 16 in the form of a coil spring is arranged between the brake shoes 4.

[0035] Fig. Figure 3 shows a base plate 7 according to the embodiment of the Fig. 1, while Fig. Figure 4 shows an alternative embodiment. Fig. 3 and Fig. 4. Three sliding elements 8 are arranged between each brake shoe 4 and the base plate 7. The sliding elements 8 are arranged along a circle around the axis of rotation of the brake drum 5. Preferably, the sliding elements 8 cover less than 20%, and more preferably less than 10%, of the radial outer circumference of the brake shoe(s).

[0036] The sliding elements 8 are attached to the base plate 7, in particular by a force-fit connection and / or a positive-locking connection. A connecting section (not visible) connects each sliding element 8 to the base plate 7 and is designed to be guided through a connecting opening (not visible) in the base plate 7 in order to establish a force-fit connection and / or a positive-locking connection between the sliding element 8 and the base plate 7.

[0037] Accordingly Fig. Four adjacent sliding elements 8 of the same brake shoe 4, arranged in the direction of rotation around the axis of rotation, are connected by a connecting bridge 17. The connecting bridge 17 serves, among other things, as a locking mechanism to prevent loss, thus reducing the number of small individual parts to handle during assembly. Reference symbol list 1 drive brake unit 2 wheel-integrated electric motor 3 drum brakes 4 brake shoe 5 brake drums 6 Actuator mechanism 7 Base plate 8 sliding element 9 brake pads 10 drive rotor 11 Outer rotor 12 inner rotor 13 rotating inner section 14 fixed outer ring 15 counter bearings 16 Return mechanism 17 Connecting bridge QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2741933B1

[0002]

Claims

[1] Drum brake (3) for a drive brake unit (1), comprising at least one brake shoe (4), one brake drum (5), one actuator mechanism (6) and one base plate (7), wherein the actuator mechanism (6) is arranged to displace the brake shoe (4) against the brake drum (5) to generate a braking torque, characterized by , that at least one sliding element (8) is arranged between the base plate (7) and the at least one brake shoe (4), which guides the brake shoe (4) when it is moved against the brake drum (5). [2] Drum brake (3) according to claim 1, characterized by that the base plate (7) is substantially made of a first material and the at least one brake shoe (4) is substantially made of a second material, wherein the hardness of the first material is less than the hardness of the second material. [3] Drum brake (3) according to claim 2, characterized by, that the base plate (7) is essentially made of aluminium and the brake shoe (4) is essentially made of steel. [4] Drum brake (3) according to any one of the preceding claims, characterized by , that the sliding element (8) consists essentially of a wear-resistant material. [5] Drum brake (3) according to claim 4, characterized by , that the sliding element (8) consists essentially of one of the following materials: acetal, nylon, ultra-high molecular weight polyethylene, polyphenylene sulfide, polyetheretherketone, polyamide imide, polytetrafluoroethylene, a steel or a ceramic material. [6] Drum brake (3) according to any one of the preceding claims, characterized by that at least two, preferably three, sliding elements (8) are arranged between the brake shoe (4) and the base plate (7) for each brake shoe (4). [7] Drum brake (3) according to any one of the preceding claims, characterized by, that the sliding element (8) is attached to the base plate (7), in particular by force-fit connection and / or form-fit connection. [8] Drum brake (3) according to claim 7, characterized by , that a connecting section is connected to the sliding element (8) which is designed to be guided through a connecting opening in the base plate (7) in order to create a force-fit connection and / or form-fit connection between the sliding element (8) and the base plate (7). [9] Drum brake (3) according to any one of the preceding claims, characterized by , that at least two sliding elements (8) are connected by a connecting bridge (17). [10] Drum brake (3) according to claim 9, characterized by , that all sliding elements (8) of each brake shoe (4) are connected in series by connecting bridges (17). [11] Drive brake unit (1) comprising a wheel-integrated electric motor (2) and a drum brake (3) arranged axially overlapping with the electric motor (2) according to one of the preceding claims. [12] Drive brake unit (1) according to claim 11, characterized by , that a winding section of the drive stator is also attached to the base plate (7). [13] Drive brake unit (1) according to claim 11 or 12, characterized by , that the electric motor (2) is a double-rotor radial flux motor comprising a winding section arranged radially between an outer rotor (11) and an inner rotor (12). [14] Drive brake unit (1) according to claim 12 or 13, characterized by , that the drum brake (3) is arranged radially inside and axially essentially at the same level as the winding section and / or the outer rotor (11) and / or the inner rotor (12). [15] Drive brake unit (1) according to one of claims 11 to 14, characterized by , that a wheel bearing (13, 14) is arranged radially inside the at least one brake shoe (4) and axially overlapping with the at least one brake shoe (4), wherein a stationary outer ring (14) of the wheel bearing is connected to the base plate (7).

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