Brake drum for a drum brake, drum brake and motor vehicle

Abstract

The present invention relates to a brake drum (1) comprising a support pot (3) with a pot base (4) and a pot wall (5), and a cylindrical sleeve (9) which is received in a pot volume (10) of the support pot (3). Essentially, a recess (17) is formed on the support pot (3) between an inner wall surface (12) of the pot wall (5) and an inner bottom surface (16) of the pot base (4), the recess being open towards the pot volume (10). An end face (24) of the cylindrical sleeve (9) facing the inner bottom surface (16) is arranged at an axial distance (15) from the inner bottom surface (16), and a thickening (18) is provided on the pot base (4) extending around the central axis (8). The present invention further relates to a drum brake (2) comprising such a brake drum (1) and to a motor vehicle comprising at least one such drum brake (2).

Description

[0001] The present invention relates to a brake drum for a drum brake according to the preamble of claim 1. The invention further relates to a drum brake with such a brake drum and a motor vehicle with at least one such drum brake.

[0002] A brake drum of the type mentioned above is known from US patent 3,005,259 A. It comprises a cast support cup and a cylindrical sleeve arranged therein, which is fixed to the support cup in a rotationally fixed manner by means of a toothed section on the outer circumference of the cylindrical sleeve. Furthermore, the cylindrical sleeve is integrally formed with an axial end face against a cup base of the support cup.

[0003] In a transition area between a pot wall of the support pot projecting away from the bottom of the pot and the said pot bottom, a sharp, circumferential inner edge is formed, acting as a notch, which poses a risk of cracking in the support pot, which is undesirable.

[0004] Furthermore, for manufacturing reasons, the end face of the cylinder sleeve—unlike the outer circumference—is not equipped with a special toothing or connecting structure, resulting in a comparatively weak mechanical connection between the cylinder sleeve and the carrier pot in the area of ​​the end face. Tests have shown that this comparatively weak mechanical connection between the end face of the cylinder sleeve and the carrier pot, combined with the relatively high temperature and / or mechanical loads typically encountered during braking, can lead to an undefined connection state. In this state, the mechanical connection of the end face of the cylinder sleeve, viewed circumferentially, can be locally or completely interrupted in an unpredictable manner, for example, due to thermal expansion of the cylinder sleeve.This can lead to locally varying stresses on the support pot and a noticeable increase in the risk of cracking in the support pot.

[0005] Another brake drum is described, for example, in the publication EP 2 497 967 A1.

[0006] The object of the invention is to provide an improved or at least a different embodiment of a brake drum compared to the prior art described above. Furthermore, an improved drum brake and an advantageous motor vehicle are to be described.

[0007] In the present invention, these problems are solved by the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims, the description, and the drawings.

[0008] The first problem is solved by a brake drum for a drum brake comprising a support cup, which can be arranged, for example, on a wheel hub of a motor vehicle and defines a central axis, has a pot base oriented transversely to the central axis, a pot wall circumferential to the central axis and integrally formed at one edge of the pot base, and a pot volume bounded by the pot base and the pot wall, and a cylindrical sleeve which is received within the pot volume and is rotationally fixed to a radially inward-oriented inner surface of the pot wall via a radially outward-oriented outer surface of the cylindrical sleeve. The cylindrical sleeve is designed to engage frictionally with the brake shoes of the drum brake when the drum brake is actuated in order to generate a braking torque.

[0009] It is essential that, during the manufacture of the brake drum, the cylinder sleeve rests against an inner surface of the drum base facing the drum's volume, and that a circumferential recess is machined into the carrier drum and the cylinder sleeve, or that the carrier drum and the cylinder sleeve define a circumferential recess, such that a depression extending around the central axis of the carrier drum and opening towards the drum's volume is formed between the inner surface of the drum wall and the inner surface of the drum base, and that an end face of the cylinder sleeve facing the inner surface of the drum base is axially spaced from this inner surface. Furthermore, it is essential that a thickening extending around the central axis is provided on the drum base, forming an end face of the drum base axially opposite the inner surface of the drum base and opposite the depression.The purpose of the "thickening" is to ensure a load-bearing wall thickness in the area where the pot base meets the pot wall. This thickening can be achieved by increasing the wall thickness of the pot base and / or by locally increasing the wall thickness of the pot base.

[0010] The invention recognizes that the interaction of the circumferential recess and the circumferential thickening significantly reduces the risk of cracking in the support pot. Specifically, the circumferential recess reduces stress peaks occurring in the support pot, while the circumferential thickening at the edge of the pot base reinforces or stiffens the base only in the area weakened by the recess, thereby minimizing the risk of cracking with minimal additional weight. Furthermore, the end face of the cylindrical sleeve is positioned at a distance from the pot base and, in particular, is not, as previously, pressed against or molded into the pot base.This means that any axial length change of the cylinder sleeve that may occur during braking, resulting from temperature stress and / or mechanical stress, has no influence on the connection condition of the cylinder sleeve or the carrier pot, thus further reducing the risk of cracking.

[0011] It may be provided that the recess or cavity is mechanically machined into the brake drum housing during manufacturing or produced by casting. The mechanical machining of the recess or cavity can, for example, be achieved by a machining process, making the recess or cavity relatively inexpensive and potentially automatable. The fact that the recess or cavity is produced by casting can mean that the brake drum housing and / or the cylinder sleeve are advantageously cast components produced within a casting process, with the recess or cavity being created during the casting process, for example, using a lost core, in particular a salt core or a sand core, or by an insert.

[0012] It is also conceivable that the recess or indentation is implemented as an undercut. The undercut can preferably be designed in accordance with DIN 509.

[0013] Furthermore, it may be provided that the recess or indentation has a cross-section that is at least partially round or oval. This ensures that the circumferential recess or indentation has no sharp edges, thus avoiding unfavorable stress concentrations in the support pot.

[0014] In a further embodiment, the recess or indentation can be opened to the pot volume via a circumferential opening and has a recess base that is expediently formed by a connecting surface between the inner surface of the pot wall and the inner surface of the pot base. In other words, the circumferential recess is incorporated into the support pot. The recess base, and in particular the connecting surface, can be concavely curved and / or have a round or oval contour. This also ensures that the circumferential recess has no unfavorable sharp edges and that unfavorable stress concentrations in the support pot are avoided.

[0015] In particular, the support pot may be designed as a cast component, especially an aluminum casting. Alternatively or additionally, the cylinder sleeve may be designed as a cast component, especially a cast iron component.

[0016] Furthermore, it can be provided that the cylinder sleeve is cast into the carrier pot or axially pressed in. Advantageously, at least the outer surface or exclusively the outer surface of the cylinder sleeve is cast into the carrier pot, or at least the outer surface or exclusively the outer surface of the cylinder sleeve is supported against the cylinder sleeve. This allows the cylinder sleeve to be fixed to the carrier pot in a rotationally fixed manner, so that the braking torques generated during operation of the drum brake can be reliably transmitted from the cylinder sleeve to the carrier pot.

[0017] The second problem mentioned at the outset is solved by a drum brake comprising a brake drum according to the preceding description and brake shoes, wherein the drum brake is arranged such that the brake shoes, when the drum brake is actuated, engage frictionally with a cylindrical sleeve of the brake drum in order to generate a braking torque.

[0018] The third problem mentioned at the outset is solved by a motor vehicle, in particular an electric vehicle, having at least one drum brake as described above.

[0019] In summary, the present invention relates to a brake drum comprising a support pot with a pot base and a pot wall, as well as a cylindrical sleeve which is received within a pot volume of the support pot. Essentially, a recess extending around a central axis of the support pot and opening towards the pot volume is formed on the support pot between an inner wall surface of the pot wall and an inner surface of the pot base; an end face of the cylindrical sleeve facing the inner surface of the base is arranged at an axial distance from the inner surface of the base; and a thickening extending around the central axis is provided on the pot base. The present invention further relates to a drum brake comprising such a brake drum and to a motor vehicle comprising at least one such drum brake.

[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 individually, without departing from the scope of the present invention. The components of a higher-level unit, such as a device, apparatus, or arrangement, mentioned above and those to be mentioned below, which are designated separately, can form separate parts or components of this unit or be integral areas or sections of this unit, even if this is depicted differently in the drawings.

[0022] A preferred embodiment of the invention is shown in the drawing and explained in more detail in the following description, wherein identical reference numerals refer to identical or similar or functionally identical components.

[0023] This schematically illustrates, Fig. 1 a sectional view of a drum brake with a brake drum according to the invention.

[0024] The Fig. Figure 1 shows a drum brake, designated as a whole by reference numeral 2, for a motor vehicle not illustrated. The drum brake 2 comprises a brake drum 1, described below, and adjustable brake shoes 13, which, when the drum brake 2 is applied, interact with the brake drum 1 to generate a braking torque 14 for decelerating the motor vehicle.

[0025] The brake drum 1 has a monolithic support cup 3, formed as an aluminum casting component, which defines a central axis 8 and has a cup base 4 oriented transversely to the central axis 8 and a cup wall 5 coaxially circumferentially around the central axis 8, which is integrally arranged at an edge 6 of the cup base 4. The cup base 4 and the cup wall 5 define a cup volume 10 open on one side, which is open to the environment via a cup opening 25 defined by the cup wall 5.

[0026] The brake drum 1 further comprises a monolithic cylindrical sleeve 9, which is matched to the carrier pot 3 and has a hollow cylindrical body. The cylindrical sleeve 9 is coaxially received in the pot volume 10 and is fixed against rotation, for example by friction and / or positive locking, via a radially outwardly oriented outer surface 11 of the cylindrical sleeve 9 to a radially inwardly oriented inner wall surface 12 of the pot wall 5. In a preferred embodiment, not shown here, the cylindrical sleeve 9 may have a toothed section on its outer surface 11, and the pot wall 5 may have a complementary mating toothed section on its inner wall surface 12. These interlock when the brake drum 1 is assembled, thus fixing the cylindrical sleeve 9 against the carrier pot 3 and the pot wall 5, respectively, in a rotationally fixed manner. The toothed section may, in particular, be formed by a rough cast structure that increases the outer surface area 11.Furthermore, the cylinder sleeve 9 is designed to engage frictionally with the aforementioned brake shoes 13 of the drum brake 2 when the drum brake 2 is actuated, in order to realize the aforementioned braking torque 14.

[0027] During the manufacture of the brake drum 1, the cylinder sleeve 9 is cast into the carrier pot 3, or axially inserted, or axially pressed in, whereby an original axial end face 24' of the cylinder sleeve 9, which is in Fig. 1 is indicated by a dashed line, on an original inner surface 16' of the pot base 4 facing the pot volume 10, which is in Fig. 1, which is also indicated by a dashed line, is added to the facility.

[0028] Due to the relatively high temperature and / or mechanical stress typically occurring on the cylinder sleeve 9 during braking, the cylinder sleeve 9 can undergo a certain axial change in length. To prevent an undefined connection state and / or load state of the cylinder sleeve 9 caused by this, respectively,To avoid damage to the support pot 3, it is provided here that a circumferential recess is incorporated into the support pot 3 and the cylinder sleeve 9, or that the support pot 3 and the cylinder sleeve 9 define a circumferential recess, such that a recess 17, coaxially circumferential around the central axis 8 of the support pot 3 and open to the pot volume 10, is formed on the support pot 3 between the inner wall surface 12 of the pot wall 5 and the inner bottom surface 16 of the pot base 4, and that an original end face section of the cylinder sleeve 9 facing the inner bottom surface 16 of the pot base 4 is removed, thereby creating an end face 24 of the cylinder sleeve 9 facing the inner bottom surface 16 of the pot base 4, which has an axial distance 15 to the inner bottom surface 16.Furthermore, it is provided that a thickening 18 is formed on the base of the pot 4, extending around the central axis 8 and axially opposite the depression 17 on an end face 19 of the base of the pot 4 opposite the inner surface 16 of the base. The thickening 18 can, for example, be bead-like and / or project axially beyond the end face 19 of the base of the pot 4.

[0029] In Fig.It is further evident from Figure 1 that the recess 17, or the recess bounded by the recess 17 and the end face 24 of the cylinder sleeve 9, has a cross-section 23 that is at least partially round or oval. Furthermore, the recess 17 is open to the pot volume 10 via a circumferential recess opening 20 and has a recess base 21 formed by a connecting surface 22 between the inner wall surface 12 of the pot wall 5 and the inner bottom surface 16 of the pot base 4. The recess base 21 of the recess 17 can be concavely curved and / or have a round or oval contour. Reference symbol list 1. Brake drum 2. Drum brake 3. Carrier pot 4. Pot bottom 5. Pot wall 6th margin 8. Center axis 9. Cylinder sleeve 10. Pot volume 11. Outdoor area 12. Interior wall surface 13. Brake shoes 14. Braking torque 15. Distance 16. Interior floor area 16' original floor area 17. In-depth study 18. Thickening 19. Bottom edge 20. Recess opening 21. Reason for further study 22. Connecting surface 23. Cross-section 24. Front surface 24' original frontal area 25. Pot opening 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] US 3,005,259 A

[0002] EP 2 497 967 A1

[0005]

Claims

[1] brake drum (1) for a drum brake (2) comprising - a support pot (3) defining a central axis (8), which has a pot base (4) oriented transversely to the central axis (8), a pot wall (5) circumferentially surrounding the central axis (8) and integrally arranged at an edge (6) of the pot base (4), and a pot volume (10) bounded by the pot base (4) and the pot wall (5), - a cylindrical sleeve (9) which is received in the pot volume (10) and is fixed in a rotationally fixed manner via a radially outwardly oriented outer surface (11) of the cylindrical sleeve (9) to a radially inwardly oriented inner wall surface (12) of the pot wall (5) and is designed to interact frictionally with brake shoes (13) of the drum brake (2) when the drum brake (2) is actuated in order to generate a braking torque (14), characterized by , that - during the manufacture of the brake drum (1), the cylinder sleeve (9) rests against an inner surface (16) of the bottom of the drum (4) facing the drum volume (10), and a circumferential recess is machined into the carrier drum (3) and the cylinder sleeve (9) such that - on the support pot (3) between the inner wall surface (12) of the pot wall (5) and the inner surface (16) of the bottom of the pot (4) a depression (17) is formed which surrounds the central axis (8) of the support pot (3) and is open to the pot volume (10) and - one end face (24) of the cylinder sleeve (9) facing the inner surface (16) of the pot base (4) has an axial distance (15) to the inner surface (16) of the base, - a thickening (18) is provided on the bottom of the pot (4) circumferentially around the central axis (8), which is formed axially opposite the depression (17) on a bottom end face (19) of the bottom of the pot (4) opposite the inner bottom surface (16) of the bottom of the pot (4). [2] Brake drum (1) according to claim 1, characterized by , that the recess (17) or the indentation is mechanically machined into the carrier pot (3) and / or the cylinder sleeve (9) during the manufacture of the brake drum (1). [3] Brake drum (1) according to claim 1 or 2, characterized by , that the depression (17) or the recess is produced by casting in the manufacture of the brake drum (1). [4] Brake drum (1) according to one of the preceding claims, characterized by , that the depression (17) or the recess is realized as a relief cut. [5] Brake drum (1) according to any one of the preceding claims, characterized by that the depression (17) or the recess has a cross-section (23) which is at least partially round or oval. [6] Brake drum (1) according to one of the preceding claims, characterized by, that the depression (17) is opened to the pot volume (10) via a circumferential depression opening (20) and has a depression base (21) formed by a connecting surface (22) between the inner wall surface (12) of the pot wall (5) and the inner bottom surface (16) of the pot base (4). [7] Brake drum (1) according to claim 6, characterized by , that the base (21) of the depression (17) is concavely curved and / or has a round or oval contour. [8] Brake drum (1) according to one of the preceding claims, characterized by , that - the support pot (3) is designed as a cast component, and / or - the cylinder sleeve (9) is designed as a cast component. [9] Brake drum (1) according to any one of the preceding claims, characterized by that the cylinder sleeve (9) is cast into the carrier pot (3) or pressed in axially. [10] Drum brake (2) comprising a brake drum (1) according to any one of the preceding claims 1 to 9 and brake shoes (13), wherein the drum brake (2) is arranged such that the brake shoes (13) when the drum brake (2) is actuated engage frictionally with a cylinder sleeve (9) of the brake drum (1) to generate a braking torque (14). [11] Motor vehicle, in particular an electric vehicle, comprising at least one drum brake (2) according to claim 10.

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