Transmission with improved pressure equalization between an interior and an exterior and improved oil outlet
The pressure equalization element in transmissions integrates channels above and below the oil level to simplify the gearbox design, allowing efficient oil drainage and pressure equalization without additional seals or space, addressing the complexity of existing designs.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- VALEO ELECTRIFICATION SAS
- Filing Date
- 2025-12-08
- Publication Date
- 2026-06-18
AI Technical Summary
Existing transmissions require separate space and seals for pressure equalization elements, complicating the gearbox design and necessitating periodic oil changes through a separate oil drain plug, which is inefficient and complex.
A single component, the pressure equalization element, functions both to equalize pressure and drain transmission oil by integrating channels above and below the oil level, allowing air exchange and gravity-driven oil drainage without additional seals or space.
The design is simplified by integrating pressure equalization and oil drainage functions into a single component, reducing complexity and eliminating the need for separate seals and additional space, enabling compact transmission design and efficient oil drainage.
Smart Images
Figure EP2025085950_18062026_PF_FP_ABST
Abstract
Description
[0001] Transmission with improved pressure equalization between interior and exterior and improved oil outlet
[0002] TECHNICAL AREA
[0003] The invention relates to a transmission comprising a housing, gears, transmission oil, and a pressure equalization element. The housing separates an interior space located within the housing from an exterior space located outside the housing. The gears are arranged in the interior space and mesh there, and the interior space is filled with transmission oil up to a certain level. The pressure equalization element allows pressure equalization between the interior and the exterior space. The invention further relates to a drive unit with an electric machine and a transmission of the type coupled thereto, a vehicle with such a drive unit, and a method for operating such a transmission.
[0004] STATE OF THE ART
[0005] Such a transmission, such a drive unit, such a vehicle and such an operating method are known from the prior art.
[0006] For example, the gearbox gears and, if applicable, the gearbox shaft bearings can be lubricated by the gearbox oil, which causes it to become contaminated over time and lose at least some of its lubricating properties. Depending on the gearbox design, the gearbox oil must therefore be changed periodically, which is usually done via an oil drain plug located in an oil sump or pan. The oil drain plug is typically located at the lowest point of the housing, but in any case, below the gearbox oil level. The pressure equalization element, on the other hand, is usually located above this level and installed in a separate opening in the housing. Sufficient space must be provided within the gearbox for the pressure equalization element, and both this separate opening and the oil drain plug must be carefully sealed to prevent gearbox oil from leaking out.The design of the gearbox is therefore comparatively complex.
[0007] REVELATION OF THE INVENTION
[0008] One object of the invention is therefore to provide an improved transmission, an improved drive unit, an improved vehicle, and an improved operating method for a transmission. In particular, the design of the transmission is to be simplified.
[0009] The object of the invention is achieved with a transmission of the type mentioned above, which additionally comprises: a first channel connecting the interior with the exterior, wherein a first opening of the first channel located in the interior is arranged above the level of the transmission oil and a second opening of the first channel opening into the exterior is arranged below the level; a second channel connecting the interior with the first channel, wherein the second channel opens into the first channel at an inlet arranged below the level of the transmission oil and an opposing third opening of the second channel is arranged below the level, wherein the pressure equalization element closes the inlet and is movable without damage (relative to the inlet), whereby the second channel is opened.
[0010] Furthermore, the object of the invention is achieved with a drive unit comprising an electric machine and a transmission of the type mentioned above coupled thereto. In addition, the object of the invention is achieved with a vehicle equipped with such a drive unit, which is intended for propelling the vehicle.
[0011] Finally, the object of the invention is solved by a method for operating a gearbox of the type mentioned, in which the pressure equalization element (relative to the inlet) is moved to drain the gearbox oil, whereby the second channel is opened.
[0012] The proposed measures allow for both pressure equalization between the interior and exterior and the drainage of the transmission oil using a single component or assembly. This pressure equalization element also functions as an oil drain element, which, during transmission operation, is inserted into the first channel and seals the opening of the second channel into the first. The transmission design is therefore particularly compact. For example, the pressure equalization element can be screwed into the first channel. To seal the opening, the pressure equalization element can protrude into the first channel.
[0013] Because the first opening of the first channel is located above the level of the transmission oil, and the second opening of the first channel, which leads to the outside, is located below this level, the first channel spans the level of the transmission oil. Therefore, an air connection exists between the interior and the exterior via the first channel, allowing pressure equalization between the two spaces.
[0014] Because the inlet of the second channel to the first channel and the opposite third opening of the second channel are located below ground level, the second channel lies below the level of the transmission oil. A connection to the transmission oil therefore exists between the interior and exterior via the second channel, allowing oil drainage through this channel. Specifically, the second channel lies entirely below the level of the transmission oil, enabling the transmission oil to drain by gravity. Furthermore, the second opening can be located at the lowest point of the housing and / or the third opening at the lowest point of the interior, allowing the transmission oil to drain completely by gravity alone.
[0015] Compared to the prior art, the design of such a gearbox is therefore significantly simplified. Firstly, there is no need to provide a separate space within the gearbox for the pressure equalization element, and secondly, there is no need for a separate seal for the pressure equalization element.
[0016] To drain the transmission oil, the pressure equalization element can be removable from the inlet, (completely) removable from the first channel, and / or rotatable and / or displaceable, whereby a third channel provided in the pressure equalization element and leading to the outside is connected to the inlet via the movement.
[0017] If the pressure equalization element itself provides a third channel, the transmission oil can drain through this third channel without having to remove the pressure equalization element from the first channel. For example, the opening of the third channel could be aligned with the inlet by rotating or slightly pulling the pressure equalization element out of the first channel, thus connecting the third channel provided in the pressure equalization element to the second channel and allowing the transmission oil to drain. It should also be noted that the transmission oil level and the proposed measures refer specifically to the stationary transmission or, in particular, to a state at least ten minutes after the transmission has been operated. In other words, in the given state, the first opening is above the level, and the second and third openings, as well as the inlet, are below the level.During operation of the transmission, the oil level may drop due to the distribution of the transmission oil within the interior. In particular, the second and third openings, as well as the inlet, may therefore be above the oil level during transmission operation.
[0018] The first channel and / or the second channel can be formed integrally with the housing (i.e., integrated into the housing) or be formed separately (and therefore exist as separate components). In particular, the first channel can be tubular or formed by a tube. If the first channel is integrated into the housing, it can be advantageous to have the pressure equalization element screwed to the housing. If the first channel is formed by a tube, the pressure equalization element can be screwed to the tube.
[0019] The electric machine and the gearbox can also be housed in a common casing, resulting in a compact drive unit. In this case, the drive unit forms a geared motor. In particular, the interior of the electric machine can be connected to the interior of the gearbox, meaning that the proposed measures and the resulting advantages can also apply to the interior of the electric machine. In other words, pressure equalization can also occur with the interior of the electric machine, and motor oil can be drained, if necessary, by removing the pressure equalization element. However, it is also conceivable that the electric machine and the gearbox have separate casings and thus constitute separate assemblies, which are nevertheless rotaryally coupled via a shaft (especially the rotor shaft of the electric machine).
[0020] Further advantageous embodiments and developments of the invention will become apparent from the dependent claims and from the description in conjunction with the figures.
[0021] It is advantageous if the pressure equalization element has a membrane that is permeable to air and vapor. This means that the membrane separates the interior from the exterior, while still allowing air exchange and / or the exchange of (water) vapor. The membrane can be made of organic material. Pressure equalization elements are known per se and will therefore not be described in detail here.
[0022] It is also advantageous if the gearbox has a labyrinth arranged at the first opening. In particular, a connecting path between the interior and exterior of the labyrinth can have an upward-pointing branch. This prevents gearbox oil from unintentionally entering the first channel through the first opening. For example, the labyrinth can be formed by or with a cover cap. In particular, this cap can have a downward-curving edge to create a vertical branch in the aforementioned connecting path. Alternatively, the labyrinth could also be formed with an arc placed on top of the first channel. This also creates an upward-pointing branch in the aforementioned connecting path. In a further embodiment, the labyrinth can be integrated into the gearbox housing.
[0023] BRIEF DESCRIPTION OF THE FIGURES Exemplary embodiments of the invention are shown in the accompanying schematic figures. They show:
[0024] Fig. 1 shows a sectional view of an exemplary and schematically represented drive unit;
[0025] Fig. 2 shows the first and second channels and the pressure equalization element in detail and
[0026] Fig. 3 shows an exemplary vehicle with an electric machine of the proposed type.
[0027] DETAILED DESCRIPTION OF THE INVENTION
[0028] It is stated in the introduction that identical parts in the different embodiments are provided with the same reference numerals or component designations, possibly with different indices. The disclosure of a component contained in the description can be applied analogously to another component with the same reference numeral or component designation. Furthermore, the positional indications chosen in the description, such as "top," "bottom," "back," "front," "side," and so on, refer to the figure directly described and illustrated and, in the event of a change in position, must be applied analogously to the new position.
[0029] Fig. 1 shows a sectional view of an exemplary and schematically represented drive unit 1, which comprises an electric machine 2 and a coupled gearbox 3, housed in a common casing 4. In this example, the common casing 4 is constructed in three parts, but its construction can also be different. The electric machine 2 comprises a stator 5 and a rotor 6, which is rotatably mounted in the casing 4 relative to the stator 5 about a rotor axis or stator axis A. The drive unit 1 comprises a rotor shaft 7, on which the rotor 6 is arranged, an intermediate shaft 8, and an output shaft 9. The gearbox 3 comprises several gears 10a, 10b, 10c, and 10d, which are mounted on the intermediate shaft 8 and the output shaft 9, with gears 10a, 10b and 10c, 10d meshing with each other. The rotor 6 and the gearbox 3 are (rotatably) coupled to each other via the rotor shaft 7.The rotor shaft 7, the intermediate shaft 8, and the output shaft 9 are rotatably mounted in the housing 4 by means of several (rolling) bearings 11a to 11e. The gearbox 3 is purely exemplary and can also be designed differently. The coupling between the rotor 6 and the gearbox 3 can also be designed differently.
[0030] The drive unit 1 further comprises a pressure equalization element 12, which allows pressure equalization between an interior space B located inside the housing 4 and an exterior space C located outside the housing 4. In addition, the interior space B is filled with gear oil 13 up to a level h. The gears 10a..10d, which are also located in the interior space B, and, if applicable, the bearings 11a..11e, are lubricated by the gear oil 13. In the given example, the gear 10b immerses in the gear oil 13 and distributes it within the interior space B during operation of the drive unit 1. This type of lubrication is purely exemplary, and the lubrication of the
[0031] The lubrication of gears 10a..1 Od (and, if applicable, the bearings 11 a..11 e) could also be done differently, for example by pumping the gear oil 13 to the points where lubrication is required using a pump (not shown).
[0032] In addition to the components already mentioned, the drive unit 1 comprises a first channel D and a second channel E, which are explained in more detail with the aid of Fig. 2, which shows a detailed view of the first and second channels D, E.
[0033] The first channel D connects the interior B with the exterior C, wherein a first opening F1 of the first channel D, located in the interior B, is positioned above the level h of the transmission oil 13, and a second opening F2 of the first channel D, opening into the exterior C, is positioned below the level h. The second channel E connects the interior B with the first channel D, wherein an inlet G of the second channel E into the first channel D and a third opening F3 opposite the second channel E are positioned below the level h. The pressure equalization element 12 closes the inlet G but is movable relative to the inlet G without causing damage, thereby opening the second channel E.In other words, the pressure equalization element 12 not only serves to equalize the pressure between the interior B and the exterior C, but also functions as an oil drain element, which is inserted into the first channel D during operation of the transmission 3 and closes the opening G and is moved relative to the opening G to drain the transmission oil 13, thereby opening the second channel E.
[0034] The proposed measures allow pressure equalization between interior B and exterior C, as well as the drainage of the transmission oil 13, to be achieved by a single component or assembly. The design of the transmission 3 is therefore particularly compact. For example, the pressure equalization element 12 can be screwed into the first channel D. To close the opening G, the pressure equalization element 12 can protrude into the first channel D, as is the case in the example shown.
[0035] Specifically, the first channel D spans above the level h of the transmission oil 13, thus creating an air connection between the interior B and the exterior C via the first channel D, allowing the aforementioned pressure equalization to occur. Furthermore, the second channel E provides a connection to the transmission oil 13, which can be used for draining the oil. In particular, the second channel E lies entirely below the level h of the transmission oil 13, allowing the transmission oil 13 to be drained by gravity. Specifically, it can also be provided that the second opening F2 is located at the lowest point of the housing 4 and / or the third opening F3 is located at the lowest point of the interior B, allowing the transmission oil 13 to be completely drained solely by gravity.
[0036] In this example, the pressure equalization element 12 has a base body 14 in which an optional, air- and vapor-permeable membrane 15 is arranged. That is, the membrane 15 separates the connection between the interior space B and the exterior space C, but allows air exchange and / or water vapor exchange. The membrane 15 can, in particular, be made of organic material. The design of the pressure equalization element 12 shown is purely illustrative, and the pressure equalization element 12 can also be constructed differently, although the basic operating principle of the pressure equalization element 12 is known.
[0037] The pressure equalization element 12 can be removed from the inlet G or (in particular, completely) from the first channel D to drain the transmission oil 13. However, it is also conceivable that the pressure equalization element 12 itself includes or provides a third channel H through which the transmission oil 13 can drain without having to remove the pressure equalization element 12 from the first channel D. For example, an opening I could be provided in the base body 14 of the pressure equalization element 12 (preferably below the diaphragm 15) which can be brought into alignment with the inlet G by rotating the pressure equalization element 12, allowing the transmission oil 13 to drain via the central third channel H in the base body 14 (see the rotational movement of the pressure equalization element 12 indicated by arrows in Fig. 2).It would also be conceivable that an opening l' is provided in the base body 14 (again preferably below the diaphragm 15), which can be brought into alignment with the inlet G by pulling down the pressure equalization element 12, thereby allowing the transmission oil 13 to flow out via the central third channel H in the base body 14 (see the linear movement of the pressure equalization element 12 indicated by arrows in Fig. 2). Combined solutions are also conceivable. However, it should be noted that if the pressure equalization element 12 is removed from the inlet G or from the first channel D to drain the transmission oil 13, such openings I, l' and a third channel H are not necessary (although they may be present, allowing the pressure equalization element 12 to be used in various ways to drain the transmission oil 13).
[0038] In the example shown in Figures 1 and 2, the first channel D is formed by a pipe 16. That is, the first channel D is tubular and designed as a separate component. The second channel E is formed by a cutout in the pipe 16 and is therefore also designed separately. Alternatively, the first channel D and / or the second channel E could be formed integrally with the housing 4, i.e., integrated into it. A separate pipe 16 would then be unnecessary.
[0039] It is advantageous if the gearbox 3 has a labyrinth arranged at the first opening F1, as is the case in the example shown in Figures 1 and 2. Specifically, in the example shown, the labyrinth is formed with an optional cover cap 17. This prevents gearbox oil 13 from unintentionally entering the first channel D through the first opening F1. Advantageously, the labyrinth or the cover cap 17 can also cause a connecting path J between the interior B and the exterior C to have an upward-pointing branch, as is the case in Figures 1 and 2. Alternatively, the labyrinth could also be formed by an arc placed on the first channel D. In a further embodiment, the labyrinth can be integrated into the housing 4.
[0040] In particular, it may be provided that an interior space of the electric machine 2 is connected to the interior space B of the gearbox 3, whereby the proposed measures and the resulting advantages can also apply to the interior space of the electric machine 2. In other words, pressure equalization can also take place with the interior space of the electric machine 2, and, if necessary, engine oil can be drained by removing the pressure equalization element 12.
[0041] It should also be noted here that the level h of the transmission oil 13, and the proposed measures, can refer in particular to the stationary drive unit 1, or especially to a state at least ten minutes after the drive unit 1 has been switched off. In other words, the first opening F1 is above level h in the given state, and the second and third openings F2, F3, and the inlet G are below level h. During operation of the drive unit 1, level h can also be lower due to the distribution of the transmission oil 13 in the interior B. In particular, the second and third openings F2, F3, and the inlet G can therefore also be above level h during operation of the drive unit 1.
[0042] Figure 3 shows the drive unit 1 installed in a vehicle 18. The vehicle 18 has two axles, one of which is driven. Specifically, the drive unit 1 is connected to the half-axles 19 of the rear axle. The driven wheels 20 are mounted on the half-axles 19. The vehicle 18 is driven at least partially or temporarily by the drive unit 1. That is, the drive unit 1 can serve as the sole drive for the vehicle 18 or, for example, be used in conjunction with an internal combustion engine (hybrid drive).
[0043] It should be noted here that the drive unit 1 does not necessarily have to have a common housing 4 for the electric machine 2 and the gearbox 3, but that the electric machine 2 and the gearbox 3 can also have separate housings and thus form separate assemblies that are, however, rotatably coupled via a shaft (in particular via the rotor shaft 7). Finally, it is stated that the scope of protection is defined by the patent claims. However, the description and the drawings are to be used for the interpretation of the claims. The features contained in the figures can be freely exchanged and combined with one another. In particular, it is also noted that the devices shown may in reality comprise more or fewer components than depicted.In some cases, the devices shown or their components may be depicted not to scale and / or enlarged and / or reduced in size.
[0044] Reference symbol list
[0045] 1 drive unit
[0046] 2 electric machine
[0047] 3 gearboxes
[0048] 4 cases
[0049] 5 Stator
[0050] 6 Rotor
[0051] 7 Rotor shaft
[0052] 8 Intermediate shaft
[0053] 9 Output wave
[0054] 10a..10d gear
[0055] 11 a..11e (rolling) bearing
[0056] 12 Pressure equalization element
[0057] 13 Gear oil
[0058] 14 Basic body pressure equalization element
[0059] 15 Membran
[0060] 16 pipe
[0061] 17 Cover cap
[0062] 18 vehicles
[0063] 19 Semi-axis
[0064] 20 rad h Gear oil level
[0065] A Rotor axis / Stator axis
[0066] B Interior
[0067] C Exterior
[0068] The first channel
[0069] E second channel F1 , F2 opening first channel
[0070] F3 Opening second channel
[0071] G Junction
[0072] H third channel I, l' opening pressure equalization element
[0073] J Connecting path
Claims
Patent claims 1. Gearbox (3) comprising a housing (4) which separates an interior space (B) arranged inside the housing (4) from an exterior space (C) arranged outside the housing (4), several gears (10a..10d) arranged in the interior space (B) and engaged in mesh, Gear oil (13), with which the interior (B) is filled up to a level (h), and a pressure equalization element (12), which allows pressure equalization between the interior (B) and the exterior (C), characterized by a first channel (D) which connects the interior (B) with the exterior (C), wherein a first opening (F1) of the first channel (D) located in the interior (B) is arranged above the level (h) and a second opening (F2) of the first channel (D) opening into the exterior (C) is arranged below the level (h), a second channel (E) which connects the interior (B) with the first channel (D), wherein the second channel (E) opens into the first channel (D) at an inlet (G) arranged below the level (h) and an opposing third opening (F3) of the second channel (E) is arranged below the level (h), wherein the pressure equalization element (12) closes the inlet (G) and can be moved without damage,where the second channel (E) is opened.
2. Transmission (3) according to claim 1, characterized in that the pressure equalization element (12) for draining the transmission oil (13) is removable from the inlet (G), is removable from the first channel (D), and / or is rotatable and / or displaceable, whereby a third channel (H) provided in the pressure equalization element (12) and leading into the outside space (C) is connected to the inlet (G) via the movement.
3. Gearbox (3) according to claim 1 or 2, characterized in that the pressure equalization element (12) has a membrane (15) that is permeable to air and vapor.
4. Gearbox (3) according to one of the preceding claims, characterized by a labyrinth arranged at the first opening (F1 ).
5. Gearbox (3) according to claim 4, characterized in that the labyrinth is formed with a cover cap (17).
6. Gearbox (3) according to one of the preceding claims, characterized in that the first channel (D) and / or the second channel (E) are formed integrally with the housing (4) or separately.
7. Gearbox (3) according to one of the preceding claims, characterized in that the second opening (F2) is located at the lowest point of the housing (4) and / or the third opening (F3) is located at the lowest point of the interior (B).
8. Gearbox (3) according to one of the preceding claims, characterized in that the first channel (D) is tubular.
9. Gearbox (3) according to one of the preceding claims, characterized in that the pressure equalization element (12) projects into the first channel (D).
10. Gearbox (3) according to one of the preceding claims, characterized in that the pressure equalization element (12) is screwed to the housing (4).
11. Drive unit (1) with an electric machine (2) and a gearbox (3) coupled thereto according to one of claims 1 to 10.
12. Drive unit (1 ) according to claim 11 , characterized in that an interior space of the electric machine (2) is connected to the interior space (B) of the transmission (3).
13. Vehicle (18) with a drive unit (1 ) according to claim 11 or 12, which is provided for driving the vehicle (18).
14. Method for operating a transmission (3) according to one of claims 1 to 10 or a drive unit (1 ) according to claim 11 or 12, characterized in that the pressure equalization element (12) is moved to drain the transmission oil (13), whereby the second channel (E) is opened.
15. Method according to claim 14, characterized in that the pressure equalization element (12) for draining the transmission oil (13) is removed from the inlet (G), is removed from the first channel (D), and / or is rotated and / or displaced, wherein a third channel (H) provided in the pressure equalization element (12) and leading into the outside space (C) is connected to the inlet (G) via the movement.