SYSTEM CONSISTING OF CLUTCH DISC OR FRICTION DISC AND CLUTCH BELL TO EFFECT REDUCED TOWING POWER

Description

[0001] The present invention relates to a system comprising a clutch disc or friction disc and a clutch bell for achieving reduced drag.

[0002] Commercial vehicles have compressed air consumers, such as a pneumatic braking system, an air suspension system, or a pneumatic clutch. A compressed air generator, such as a compressor, is provided for these compressed air consumers. Such a compressor is usually driven by the vehicle engine, for example, by a commercial vehicle's internal combustion engine.

[0003] Commercial vehicles also have compressed air reservoirs. These reservoirs temporarily store the compressed air generated by a compressed air generator until it is used by a compressed air consumer.

[0004] When a compressed air reservoir is filled with compressed air to a corresponding cut-off pressure, the compressed air generator is temporarily disconnected from its drive according to the state of the art to save energy. Such decoupling is achieved by means of a multi-plate clutch, which is installed between the vehicle engine and the compressed air generator to interrupt and restore the torque transmission.

[0005] For this purpose, this multi-plate clutch is designed so that torque can be transmitted between a radially outer clutch housing and a radially inner shaft by means of frictional engagement and disengaged again. This frictional engagement is achieved by means of clutch discs (e.g., made of steel) and friction discs (e.g., with an embossed friction lining). The clutch discs engage positively and torque-tightly with the clutch housing, and the friction discs engage positively and torque-tightly with the shaft (although an alternative arrangement is also possible).

[0006] Such a multi-plate clutch is also preferably oil-flooded or designed to be wet-running to dissipate frictional heat. Even when the clutch is engaged, oil flows between the individual clutch discs and friction discs from radially inside to radially outside (due to centrifugal force) to absorb and dissipate frictional heat. To enable such flow (between the closed or adjacent clutch discs and friction discs), all friction discs have structured friction linings to form radially outward-running channels between the individual clutch discs and the friction discs in frictional contact with them. These channels enable oil flow even when the clutch is engaged.

[0007] State-of-the-art oil-flooded (wet-running) multi-plate clutches pose a problem with drag performance. Particularly after repeated and frequent engagement and disengagement, the disengaged clutch discs or friction discs rotate in the oil bath, causing undesirable torque transfer between them due to the viscosity of the oil.

[0008] Oil-lubricated (wet-running) multi-plate clutches according to the prior art, as already described in the introduction, comprise a clutch bell housing and clutch discs that transmit torque with the clutch bell housing by means of positive engagement. For this purpose, the clutch discs have radially outwardly projecting teeth on their circumference, with the clutch bell housing having grooves on its inner surface for receiving the teeth. Alternatively, according to the "reverse arrangement," the friction discs (instead of the clutch discs) transmit torque with the clutch bell housing by means of positive engagement, and the clutch discs (instead of the friction discs) transmit torque with the shaft by means of positive engagement.

[0009] In the context of this patent application, a system consisting of a clutch bell housing and clutch disc(s) is described below, wherein the clutch bell housing and clutch disc(s) engage with each other in a form-fitting and torque-resistant manner. As already described in the introduction as a "reverse arrangement," configurations are also conceivable in which the friction discs, rather than the clutch discs, engage with the clutch bell housing. For simplicity, however, only one of these two variants is described below. Nevertheless, the described features are also disclosed analogously for a friction disc according to the "reverse arrangement."

[0010] To solve the above-mentioned problem regarding drag performance, it is necessary to ensure that the oil can flow as freely as possible between the individual clutch discs and friction discs. Since the oil is forced radially outward due to centrifugal force in a rotating clutch, the oil must be able to flow out of the spaces between the individual clutch discs and friction discs in the area of ​​the (radially outer) interaction between the teeth and grooves.

[0011] In this regard, Fig. 1 which shows a separating contour Tk between a clutch disc 1 (radially inside) and a clutch bell 2 (radially outside). Fig. 1 an area B of the interaction between a tooth Z (of the clutch disc 1) and a groove (of the clutch bell 2) is marked with a circle, whereby this area in Fig. 1a is presented in detail.

[0012] Fig. 1a shows the above-mentioned area of ​​interaction between a tooth Z (of the clutch disc 1) and a groove N (of the clutch bell 2) in detail. The illustrated groove N of the clutch bell 2 has lateral flanks 21, 23 extending in the radial direction, as well as a radially outer circumferential edge 22 extending in the circumferential direction. The groove N is designed to receive the illustrated tooth Z of the clutch disc 1.

[0013] The tooth Z shown has lateral flanks 11, 13 running in the radial direction, as well as a radially outer circumferential edge 12 running in the circumferential direction and connecting the lateral flanks 11, 13.

[0014] Between the circumferential edge 12 of the clutch disc 1 and the lateral flanks 21, 23 of the clutch bell 2 as well as the radially outer circumferential edge 22 of the clutch bell 2, an oil return cross-section Ar is formed, which in Fig. 1a is shown hatched. The oil return cross-section in the area of ​​interaction between all teeth Z (of clutch disc 1) and all grooves (of clutch bell housing 2) is defined as the total oil return cross-section.

[0015] When the clutch is separated in the manner described above, the oil located radially outward due to centrifugal forces must therefore pass through the total oil return cross-section in order to be able to flow out of the spaces between the individual clutch discs 1 of the clutch.

[0016] It is known in the prior art that an increase in the total oil return cross-section leads to a reduction in drag performance, since, as described above, the oil can pass more quickly through the increased total oil return cross-section to flow between the individual clutch discs 1 of the clutch. However, this leads to the problems described below.

[0017] In Fig. 1a Furthermore, a radially extending contact area X is shown between the lateral flanks 11, 13 of the clutch disc 1 and the lateral flanks 21, 23 of the clutch bell 2. In this contact area X, surface contact occurs for torque transmission between the clutch disc 1 and the clutch bell 2. To increase the overall oil return cross-section, it would now be possible to shorten the contact area X, for example by shortening the teeth Z, which would correspond to shortening the lateral flanks 11, 13. However, this would create a wear problem, since in such a case the entire torque-transmitting area (between clutch disc 1 and clutch bell 2) would be reduced, which would lead to a higher load in the reduced contact area X.

[0018] It is known in the prior art to provide clutch discs 1 with "missing teeth" in order to increase the overall oil return cross-section. However, this also results in a wear problem, since in this case, the total torque-transmitting surface (= the sum of the contact surfaces between clutch disc 1 and clutch bell housing 2) is reduced due to the missing teeth.

[0019] To avoid the aforementioned wear problem while still increasing the overall oil return cross-section, it is known in the art to provide additional grooves in the clutch bell housing 2. However, this increases the manufacturing costs of the clutch bell housing 2.

[0020] Alternatively, WO 2009 / 112243 A2 discloses a wet-running multi-plate clutch with annular clutch plates arranged in a clutch housing, which are alternately divided into steel plates and friction discs. The steel plates are connected to the clutch housing in a form-fitting manner in the circumferential direction by means of radially outer toothing, with recesses provided in the steel plates as oil return cross-sections. To reduce any drag torque that may occur when the multi-plate clutch is disengaged, it is proposed that the recesses be machined into at least some of the teeth of the toothing, essentially radially outside the effective, annular friction surfaces of the steel plates.

[0021] It is therefore an object of the invention to provide a clutch disc or friction disc as well as a system comprising a clutch disc or friction disc and a clutch bell for effecting a reduced drag power, which are inexpensive to manufacture and durable.

[0022] This problem is solved by the subject matter of the independent claim. Preferred developments are the subject matter of the dependent claims.

[0023] The claimed clutch disc or friction disc of the independent claim defines and claims the component that engages the clutch bell housing in a form-fitting and torque-resistant manner, regardless of whether this component has the friction lining (according to the aforementioned "reverse arrangement") and is thus considered a friction disc or not. However, the following only discusses a claimed clutch disc. The statements made apply analogously to a claimed friction disc according to the "reverse arrangement."

[0024] As described above, a clutch disc has a plurality of radially outwardly projecting teeth with lateral flanks for transmitting torque between the clutch disc and a clutch bell. The clutch disc further has circumferentially extending, radially outward peripheral edges connecting the lateral flanks of each tooth.

[0025] Furthermore, the clutch bell housing has lateral flanks for transmitting torque between it and the clutch disc. Furthermore, the clutch bell housing has radially outer, i.e., radially inwardly directed, circumferential edges that connect its lateral flanks. A single groove of the clutch bell housing is formed by two lateral flanks and a radially outer circumferential edge connecting these flanks.

[0026] When assembled, the teeth of the clutch disc are located within the grooves of the clutch bell housing. An oil return cross-section is formed between each groove containing a tooth and that tooth. Furthermore, an oil return cross-section is also formed through each groove that does not contain a tooth. The sum of all oil return cross-sections is referred to as the total oil return cross-section.

[0027] An oil return cross-section is formed between a groove containing a tooth and this tooth, as described below. A cross-section is formed between the radially outer peripheral edge of the tooth and the lateral flanks of the groove, as well as the radially outer peripheral edge of the groove, which is considered the oil return cross-section.

[0028] According to the invention, a recess is provided in the radially outer peripheral edge of at least one tooth of the clutch disc in order to increase the oil return cross-section between this tooth and the groove in which it is located.

[0029] This means that the contact area between the lateral flanks of the tooth and groove is not reduced despite the increase in the oil return cross-section, thus improving unhindered oil flow without worsening wear. This reduces the drag of a clutch without increasing wear.

[0030] Furthermore, providing a recess in a clutch disc is more cost-effective than in a clutch bell, thus reducing manufacturing costs.

[0031] By forming the recess in an arc shape, the increase in the oil return cross-section is maximized while simultaneously minimizing material stresses.

[0032] Preferably, not just a single tooth of the clutch disc has a recess according to the invention, but rather several teeth of the clutch disc. The teeth having a recess are preferably arranged opposite one another.

[0033] Preferably, all teeth of the clutch disc have a recess according to the invention.

[0034] Preferably, all grooves of a clutch bell housing are filled by a tooth of a clutch disc. At least one of these teeth has a recess according to the invention. This minimizes wear despite an increase in the overall oil return cross-section.

[0035] Alternatively, according to another preferred embodiment, in addition to a clutch disc having at least one tooth with a recess according to the invention, at least one tooth is also "omitted." This means that, due to this at least one omitted tooth, at least one groove of the clutch bell housing is not filled by a tooth. This also increases the overall oil return cross-section.

[0036] Preferably, a system comprising a clutch bell and clutch discs has exactly three clutch discs. Fig. 1 shows a separating contour Tk between a clutch disc 1 and a clutch bell 2 according to the prior art. Fig. 1a shows an enlarged section B of Fig. 1 (Prior art). Fig. 2 shows a separating contour Tk between a clutch disc 1 and a clutch bell 2 according to an embodiment of the invention. Fig. 3 shows a separating contour Tk between a clutch disc 1 and a clutch bell 2 according to an embodiment of the invention. Fig. 4 shows a clutch disc 1 in interaction with a clutch bell 2 according to an embodiment of the invention. Fig. 4a shows an enlarged section C from Fig. 4 .

[0037] The Fign. 1 und 1a show embodiments according to the state of the art and have already been acknowledged in the introduction to the description.

[0038] Fig. 2 shows a separating contour Tk between a clutch disc 1 and a clutch bell 2 according to an embodiment of the invention. In comparison to Fig. 1 The separating contour Tk differs only in that two teeth Zx, shown here in black, are omitted from the design. An omitted tooth Zx represents a groove in the clutch bell housing 2 in which no teeth are located when the clutch disc is mounted.

[0039] Furthermore, the Fig. 2 The construction shown differs from that shown in Fig. 1 or in Fig. 1a shown construction that all teeth Z* in Fig. 2 have a recess according to the invention, as detailed in Fig. 4 shown.

[0040] Fig. 3 shows analogous to Fig. 2 a separating contour Tk between a clutch disc 1 and a clutch bell 2 according to an embodiment of the invention. In the Fig. 3 In the embodiment shown, four teeth Zx, shown in black, are omitted from the design, in contrast to two omitted teeth Zx in Fig. 2 . Further differences lie between the designs of the Fign. 2 und 3 not present.

[0041] Fig. 4 shows again the clutch disc 1 from Fig. 3 , compared to the Fign. 1 , 2 und 3 However, the separating contour between clutch disc 1 and clutch bell 2 is not merely shown schematically. Rather, Fig. 4 the teeth Z* according to the invention can be recognized by their recesses, whereby these recesses are described in the description of the following Fig. 4a with reference to section C (see Fig. 4 ) will be explained in detail.

[0042] All teeth in Fig. 4 The clutch disc 1 shown furthermore has a recess according to the invention.

[0043] Fig. 4a shows analogous to Fig. 1a The above-mentioned area (section C) of the interaction between a tooth Z* (of the clutch disc 1) and a groove N (of the clutch bell 2) in detail. The illustrated groove N of the clutch bell 2 has lateral flanks 21, 23 extending in the radial direction, as well as a radially outer, circumferential edge 22 extending in the circumferential direction. The groove is designed to receive the illustrated tooth Z* of the clutch disc 1.

[0044] The circumferential direction in this detailed view corresponds to the horizontal direction in Fig. 4a , where the radial direction is the vertical direction in Fig. 4a The same applies to Fig. 1a analogue.

[0045] The tooth Z* shown has lateral flanks 11, 13 running in the radial direction, as well as a radially outer circumferential edge 12 running in the circumferential direction, which, however, is interrupted by a recess 12* according to the invention.

[0046] An (enlarged) oil return cross-section Ar* is formed between the two-part circumferential edge 12 and the recess 12* of the clutch disc 1 and the lateral flanks 21, 23 of the clutch bell housing 2, as well as the radially outer circumferential edge 22 of the clutch bell housing 2, which is shown hatched. The oil return cross-section in the area of ​​the interaction between all teeth Z (of the clutch disc 1) and all grooves N (of the clutch bell housing 2) is defined as the total oil return cross-section. If teeth have been omitted as described above, the total oil return cross-section is further increased.

[0047] The recess 12* is arcuate in this embodiment. Furthermore, the recess 12* is arranged in this embodiment such that the lateral flanks 11, 13 are not shortened by the recess 12*. This means that the recess 12* does not intersect the lateral flanks 11, 13.

[0048] According to a further embodiment not shown, the recess 12* is indeed curved, but is not necessarily arranged in such a way that the lateral flanks 11, 13 are not shortened by the recess 12*.

[0049] According to a further embodiment not shown, the recess 12* is not necessarily curved, but is arranged such that the lateral flanks 11, 13 are not shortened by the recess 12*.

[0050] The remaining features of these two variations correspond to those described with reference to the Fign. 4 und 4a described characteristics.

Claims

1. System consisting of at least a clutch disc (1) and / or a friction disc as well as a clutch case (2) for effecting a reduced drag resistance, wherein the clutch disc (1) and / or the friction disc has: - multiple radially outwardly projecting teeth (Z) with lateral flanks (11, 13) for transmitting a torque between the clutch disc (1) and / or friction disc and grooves (N) provided in the clutch case (2) with lateral flanks (21, 23) and radially outer circumferential edges (22) connecting the latter, wherein each tooth (Z) of the clutch disc (1) and / or friction disc has a radially outer circumferential edge (12) connecting its lateral flanks (11, 13), and an oil return cross section (Ar) is formed between this circumferential edge (12) of a tooth (Z) and the lateral flanks (21, 23) of a groove (N) as well as the radially outer circumferential edge (22) of the groove (N), wherein an overall oil return cross section consists of the individual oil return cross sections (Ar) at each groove (N), characterized in that the circumferential edge (12) of at least one tooth (Z*) of the clutch disc (1) and / or friction disc has a recess (12*), in order to form an enlarged oil return cross section (Ar*).

2. System according to claim 1, wherein the recess (12*) is arc-shaped.

3. System according to any one of the preceding claims, wherein the recess (12*) is arranged between the lateral flanks (11, 13) of the tooth (Z) and designed such that the lateral flanks (11, 13) are not shortened as a result, so that a radially extending contact region (X) between the lateral flanks (11, 13) of the tooth (Z) and the lateral flanks (21, 23) of the groove (N) is maximal.

4. System according to any one of the preceding claims, which has a plurality of teeth (Z*) with a recess (12*), or only has teeth (Z*) with a recess (12*).

5. System according to any one of the preceding claims, wherein the number of teeth (Z, Z*) of the clutch disc (1) and / or friction disc is equal to the number of grooves (N) in the clutch case (2).

6. System according to claim 5, wherein the number of teeth (Z, Z*) of the clutch disc (1) and / or friction disc is lower than the number of grooves (N) in the clutch case (2), as a result of which the overall oil return cross section is increased.

7. System according to any one of the preceding claims, with a total of three clutch discs (1) and / or friction discs.