transmission

Abstract

Transmission (1), in particular a dual-clutch transmission, with a venting arrangement (7) having a venting element (9) which has at least one inlet opening (24) facing the interior of the transmission and an outlet opening (40) facing outwards, wherein the venting arrangement (7) further comprises at least one oil trapping element (8) which is arranged between the venting element (9) and a source of sprayed oil, characterized in that the venting element (9) is arranged between the oil trapping element (8) and the inner wall of the transmission.

Description

[0001] The invention relates to a transmission, in particular a dual-clutch transmission, with a breather arrangement with a breather element which has at least one inlet opening facing the transmission interior and an outlet opening facing outwards.

[0002] In order to achieve pressure equalization in the gearbox when temperatures change, it is known to provide an opening, also called a breather, on the gearbox housing.

[0003] Particularly in sports cars with high torque, oil can be forced through the vent opening. To prevent this, more complex vent arrangements are also known. For example, DE 10 2014 215 203 A1 discloses a vent arrangement that has a T-shaped section and an adjoining line section. Vent arrangements with a labyrinth are also known.

[0004] What these structures have in common is that they can delay oil leakage from the gearbox, but cannot completely prevent it.

[0005] Generic transmission configurations are known from the documents DE 10 2014 215 203 A1, US 3 422 982 A, US 2015 / 0 362 024 A1, JP H06- 33 240 Y2, DE 910 496 B, and from the document TVS: multitronic gearbox. May 18, 2021, www [online]. In: https: / / tvsengineering.com / en / multitronic-gearbox.

[0006] Based on this, it is the object of the present invention to provide a transmission with a breather arrangement from which no transmission oil escapes even in extreme driving situations.

[0007] To solve this problem, it is proposed that the breather arrangement comprises at least one oil collecting element which is arranged between the breather element and a spray oil source.

[0008] The invention is defined by the subject matter of the appended claims, whereby the description and the drawings are to be used to interpret the claims. As described, the breather element has at least one inlet opening and one outlet opening. Air, oil foam, and splash oil enter the breather element through the inlet opening, while only air should escape through the outlet opening. This applies when higher temperatures and pressures exist inside the gearbox than outside. In the opposite case, air enters through the outlet opening and via the inlet opening into the gearbox. This case is unproblematic because the air flow forces the oil back into the gearbox.

[0009] The term "inlet" opening therefore simply refers to the position of the opening facing the transmission interior, while the outlet opening refers to the opening facing the space surrounding the transmission. It has been shown that even extremely complex breather element designs cannot prevent oil from escaping from the transmission, but can only delay it. To completely prevent oil from escaping, an oil trap is provided between the breather element and a splash oil source. The breather element is thus shielded so that only as little oil enters the breather element as the breather element can prevent from escaping.

[0010] In principle, the breather element can be designed like a conventional breather element. However, a breather element optimized for the described arrangement is also presented below. First of all, it is essential that the breather element is shielded from splash oil by an additional oil trap.

[0011] Sources of splash oil can be clutches, gears, or other rotating components in the transmission. In dual-clutch transmissions, this can be a clutch of the dual-clutch transmission and / or gears of the gear set, or the transmission shafts. At high speeds, the splash oil accumulates into a kind of oil stream, which is why the venting elements described above are unable to completely prevent the oil entering the venting element from escaping.

[0012] Instead of further optimizing the breather elements as before, the new approach is to prevent splash oil from reaching the breather element in the first place, meaning it no longer has to cope with such large oil quantities as before. The described arrangement does not achieve 100 percent sealing of the breather element. However, the amount of oil entering the breather element can be reduced to such an extent that it is not problematic. In particular, no oil will then escape from the interior of the gearbox; instead, the oil entering the breather element can be completely expelled from it again. In this case, both oil in droplet form and oil foam are considered to be entering oil.

[0013] The breather assembly can advantageously be located in the clutch bell housing. Alternatively, the breather assembly can be located in the gear box housing. Typically, the transmission housing essentially consists of two components: the clutch bell housing, which accommodates the clutch, and the gear box housing. Due to space constraints, the breather assembly is usually located in the gear box housing. For the intended use of the oil trap element, a location in the clutch bell housing has proven to be a further alternative.

[0014] Advantageously, the oil catcher element can have a circular cross-section. The oil catcher element can also have passages for transmission components. In particular, the oil catcher element can have an annular cross-section. In this case, the transmission input shafts can pass through the oil catcher element.

[0015] Advantageously, the oil collection element can be cup-shaped. This collects the splashed oil at the edge or bottom of the cup and directs it to the bottom of the oil collection element.

[0016] Advantageously, a sealing element can be located on the edge of the oil collecting element, which seals the oil collecting element from the interior of the transmission.

[0017] Preferably, the oil catcher element can be made at least partially of plastic. In particular, the oil catcher element can be manufactured by plastic injection molding. This allows for cost-effective production of the oil catcher element, which is usually irregularly shaped.

[0018] Advantageously, the oil trap can be arranged in such a way that it shields the breather element from splash oil. This means that it is not intended to create a completely oil-tight space. It is merely intended to keep splash oil away from the breather element. However, this is entirely sufficient to ensure that virtually no oil reaches the breather element at all.

[0019] This is particularly feasible if the oil catch element separates a space from the rest of the transmission interior. As already described, this can be a space in the clutch bell housing or in the gear set housing. This space houses the breather and can therefore also be referred to as the breather chamber. This breather chamber is shielded to prevent splash oil from entering the breather chamber. This means that oil and splash oil can still get into the breather chamber. However, the openings in the oil catch element are arranged in such a way that the oil or splash oil only reaches the transmission wall or the wall of the breather element, but not the inlet openings. If oil foam gets through the air passage openings in the oil catch element and collects in the breather chamber, oil can also get into the breather element.The breather element is designed to process these small amounts of oil by separating the oil foam into oil and air, allowing only the air to escape from the breather element. The oil is then released back into the transmission interior.

[0020] Advantageously, the oil catcher element can have air passages only in the lower half. Accordingly, splash oil can only enter the venting chamber in the lower half of the oil catcher element. The venting element is preferably arranged in the upper half of the oil catcher element.

[0021] Furthermore, it can be provided that the through-openings or air passages of the oil collection element are arranged at a distance from the inlet opening(s) of the venting element. Furthermore, the inlet openings of the venting element can be arranged such that oil passing through the oil collection element does not directly impinge on the inlet openings.

[0022] The venting element can be provided with two inlet openings and one outlet opening. As already described, the inlet openings are the openings facing the interior of the transmission.

[0023] The vent element can advantageously be curved. In particular, it can be designed as a ring segment. The vent element preferably has an annular cross-section, but it can also have a rectangular or other cross-section. It is thus shaped similarly to a banana.

[0024] Since the oil trap prevents most of the oil from reaching the venting element, the design can be simplified. For example, it only has one base body on which the two inlet openings are located. This base body is curved or shaped like a ring segment. The multiple sections described in the prior art are no longer necessary.

[0025] To achieve a separation of oil and air when oil foam enters through one of the inlet openings, the venting element can be provided with a variable cross-section. In particular, the cross-section can increase at least in sections toward the center. This can be implemented in various ways.

[0026] Firstly, the ends of the vent element or the base body of the vent element can be tapered. Thus, there are only smaller inlet openings in the middle compared to the cross-sectional area. However, it can also be provided that, starting from the inlet openings, the cross-section increases significantly, extending over a fifth of the length of the base body. Starting from the area of ​​the inlet opening, a cross-sectional area ten times or even larger can be achieved. Oil foam bubbles entering the base body of the vent element then expand, causing them to burst, and the oil to flow to the bottom of the base body, while the air collects above the oil.

[0027] Advantageously, the inlet opening(s) of the vent element can face downward in the installed position. This allows oil foam entering the vent element, which has condensed back into oil, to easily exit the vent element. For the air, however, the location of the openings is unimportant.

[0028] The vent element can advantageously be arranged between the oil collecting element and the inner wall of the transmission. The vent element can advantageously be arranged on the wall between the clutch bell housing and the gear box housing. The vent chamber is then located between the oil collecting element and the intermediate wall of the transmission. To create a connection to the space outside the transmission, the vent element can have a vent channel that surrounds the outlet opening and can be inserted into the inner wall of the transmission, for example the intermediate wall between the clutch bell housing and the gear box housing. To achieve a complete connection to the outside, the vent arrangement can have a connecting piece, in particular a hose connection, to the outside. This can be connected to the vent channel or simply inserted into the wall of the transmission.

[0029] Furthermore, an oil barrier can be located in the vent channel. This can be designed as a pressed-in or molded-on orifice that protrudes into the base body. It can also be designed as an orifice in the vent channel.

[0030] Further advantages, features, and details of the invention will become apparent from the following description of exemplary embodiments and figures. These show: Fig. 1 a gearbox, Fig. 2 a gearbox in a second view, Fig. 3 a vent arrangement in a first view, Fig. 4 a vent arrangement in a second view, Fig. 5 a vent arrangement in a third view, and Fig. 6 a vent arrangement in a fourth view.

[0031] Fig. 1 shows a transmission 1 with a transmission housing 2. The transmission housing 2 is divided into two parts: a clutch bell housing 3 and the gear set housing 4. The gear set housing 4 is often also referred to as the transmission housing, but this becomes ambiguous at the latest when the clutch bell housing 3 is taken into account. In the present application, the transmission housing 2 is therefore understood to mean the entire housing consisting of the clutch bell housing 3 and the gear set housing 4. Between the clutch bell housing 3 and the gear set housing 4 is an intermediate wall 5. This serves, for example, to support the transmission input shafts, which is why the intermediate wall 5 is also called the bearing bracket.

[0032] The clutch assembly 6 of the transmission 1 is located in the clutch bell housing 3. Preferably, the transmission 1 can be designed as a dual-clutch transmission. In this case, the clutch assembly 6 is designed, for example, as a double clutch. Particularly in hybridized powertrains, the clutch assembly can also be designed as a triple clutch assembly. In this case, two clutches are powershift clutches of the dual-clutch transmission, and the third clutch serves to disconnect the combustion engine from the rest of the powertrain during electric motor operation. It is therefore a separating clutch.

[0033] The breather assembly 7 is located in the clutch bell housing 3. This assembly comprises an oil collecting element 8 and a breather element 9. The breather assembly 7 also has a hose connection 10 on the outside of the transmission.

[0034] Fig. Figure 2 shows the transmission housing 2 in a further view, namely a top view of the intermediate wall 5. The arrangement of the vent element 9 can be seen. This element is positioned above the passage opening 12 for the transmission input shafts and, in particular, as high up as possible.

[0035] Fig. Figure 3 shows the breather assembly 7 in a perspective view. This shows the cup-shaped oil catcher element 8 and its ring-like configuration. A through-opening 14 for the transmission input shafts is also visible. Several bushings 16 for screwing the oil catcher element 8 are located around the through-opening 14.

[0036] An O-ring 18 for radial sealing is arranged on the radially outer edge of the oil collecting element 8. This seals the oil collecting element 8 from the transmission housing 2 and, more precisely, the clutch bell housing 3.

[0037] In addition, the oil collection element 8 has air passages 20 through which air can enter the vent chamber 22. Oil foam and possibly also small amounts of splash oil can also enter the vent chamber 22 via the air passages 20. However, these are spaced apart from the inlet openings 24 of the vent element 9 and are also arranged in such a way that they prevent splash oil from entering the vent element 9.

[0038] The vent element is greatly simplified and essentially comprises only a base body 26 with two inlet openings. For external connection, the vent element 9 has a vent channel 28 branching off from the base body 26.

[0039] The vent element 9 is annular and designed as a circular segment. It tapers at the ends 30. In other words, the cross-section of the base body 26 widens toward the inlet openings 24. This causes the oil foam to expand, the oil bubbles to burst, and the oil foam is separated into oil and air.

[0040] Fig. 4 shows the vent arrangement compared to Fig. 3 from the opposite side. This shows that the breather element 9 is sealed off from the transmission interior by the oil trap element 8.

[0041] Fig. 5 shows an extension of the breather arrangement 7 by an oil barrier 32 in the form of a baffle 34. The baffle 34 is pressed in or injection-molded and extends from the breather channel 28 into the base body 26. Since the oil or the oil foam moves into or out of the blade in this view during the main movement, the baffle 34 prevents the oil foam located on the inner wall of the base body 26 from penetrating. In fact, in order for any oil to reach the breather channel 28 at all, the oil foam must pile up high in the middle of the base body 26. This is not the case due to the oil catch element 8 and the resulting only small amounts of oil in the breather element 9. This reliably prevents oil from escaping from the gearbox 1.

[0042] Fig. 6 shows an alternative design of an oil barrier 32 in the form of the orifice 36. The orifice 36 reduces the diameter of the vent channel 28.

[0043] The vent channel 28 is, as in all other designs, pressed into the intermediate wall 5. The vent channel 28 is sealed by an O-ring 38.

[0044] For connection to the outside, the outlet opening 40 is located at the end of the ventilation duct 28.

Claims

[1] Transmission (1), in particular a dual-clutch transmission, with a breather arrangement (7) with a breather element (9) which has at least one inlet opening (24) facing the transmission interior and an outlet opening (40) facing outwards, wherein the breather arrangement (7) further comprises at least one oil collecting element (8) which is arranged between the breather element (9) and a spray oil source, characterized by that the breather element (9) is arranged between the oil collecting element (8) and the inner wall of the gearbox. [2] Transmission according to claim 1, characterized by that the oil collecting element (8) has a circular, in particular annular, cross-section. [3] Transmission according to claim 1 or 2, characterized by that the oil collecting element (8) is cup-shaped. [4] Transmission according to one of the preceding claims, characterized by that the oil collecting element (8) is made of plastic. [5] Transmission according to one of the preceding claims, characterized by that the oil collecting element (8) shields the breather element (9) against splash oil. [6] Transmission according to one of the preceding claims, characterized by that the oil collecting element (8) separates a breather chamber (22) from the rest of the transmission interior. [7] Transmission according to one of the preceding claims, characterized by that the oil collecting element (8) has air passage openings (20) in the lower half. [8] Transmission according to one of the preceding claims, characterized by that the venting element (9) has two inlet openings (24) and one outlet opening (40). [9] Transmission according to one of the preceding claims, characterized by that the vent element (9) is bent. [10] Transmission according to one of the preceding claims, characterized by that the venting element (9) has a variable cross-section. [11] Transmission according to one of the preceding claims, characterized bythat the cross-section increases at least in sections towards the middle. [12] Transmission according to one of the preceding claims, characterized by that the inlet opening (24) or inlet openings (24) of the venting element (9) point downwards in the installed position. [13] Transmission according to one of the preceding claims, characterized by that the venting element (9) has a venting channel (28) which surrounds the outlet opening and can be inserted into the transmission wall. [14] Transmission according to one of the preceding claims, characterized by that the bleeder arrangement (7) is arranged in the clutch bell (3).

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