E-AXLE TRANSMISSION, SUITABLE FOR FORWARD AND REVERSE DRIVE

Description

Technical area

[0001] The invention relates to an electric axle transmission suitable for forward and reverse travel, comprising a housing formed from adjacent housing halves along a joint, and a differential gear. Furthermore, the invention relates to the use of the electric axle transmission in a drive train of an electrically powered vehicle or in the drive train of a hybrid drive of a motor vehicle equipped with an internal combustion engine. State of the art

[0002] DE 10 2018 211 360 A1 relates to a lubricant supply system for a drive device of an electrically powered vehicle. At least one electric machine is provided, the rotor shaft of which drives onto at least one flange shaft of a vehicle wheel via a gear arrangement. The gear arrangement has at least one gear stage for torque conversion. The lubricant supply system comprises a transmission hydraulic circuit in which a lubricant tank is connected via a suction line to a pressure pump, by means of which, in a dry sump lubrication system, the lubricant is guided in a transmission supply line to a transmission lubricant point, such as a gear mesh of the gear stage. The lubricant dripping from the transmission lubricant point collects in a lubricant sump and from there is guided back into the lubricant tank via a return line by means of a return pump.The lubricant supply system features a rotor hydraulic circuit for internal rotor cooling in addition to the transmission hydraulic circuit. To activate the internal rotor cooling of the rotor hydraulic circuit, an overpressure builds up in the lubricant tank.

[0003] DE 10 2019 102078 B3 discloses an electric axle transmission. Previous drive concepts, primarily implemented using internal combustion engines, utilize oil pans to collect a lubricant, such as transmission oil—usually during forward travel—and distribute it to relevant components such as bearings or radial shaft seals. Solutions that simultaneously ensure adequate lubrication of all transmission components during both forward and reverse travel of the vehicle are rare. With regard to electromobility, the requirements for reversing electrically powered vehicles are increasingly increasing. For example, reversing times of 60 minutes are required, at a specific speed n or, for example, at a speed of 80 km / h or over a distance of 65 km, for example, when towing in reverse.These requirements can be imposed with or without torque loads and can be requested at different frequencies and for different lengths of time over the vehicle's lifetime. Description of the invention

[0004] According to the invention, an electric axle transmission is proposed that is suitable for forward and reverse travel, comprising a housing formed from housing halves that are adjacent along a joint and equipped with a differential gear. A collecting device for a lubricating medium is provided within the housing, which can be filled with the lubricating medium in both directions of rotation of the electric axle transmission, namely forward and reverse, when the electric axle transmission is driving a vehicle.

[0005] The solution proposed according to the invention therefore makes it possible to lubricate mechanical components in the electric axle transmission even when reversing, so that the requirements for reversing of electrically powered vehicles mentioned at the beginning can be met.

[0006] In one embodiment of the e-axle transmission proposed according to the invention, the collecting device for the lubricating medium is essentially T-shaped. Such a collecting device, which is arranged inside a transmission housing, can form a reservoir of lubricating medium, which, due to the effect of gravity, drips from the upper region of the housing of the e-axle transmission according to the invention into the areas below, thus lubricating the components to be lubricated.

[0007] In the electric axle transmission proposed according to the invention, the collecting device is provided with a trough-shaped base. A lubricant reservoir collects in the trough-shaped base both when the electric axle transmission is operating in the forward direction of rotation and when the electric axle transmission is operating in the opposite direction of rotation for reverse travel.

[0008] In the solution proposed according to the invention, it is provided in the electric axle transmission that the trough-shaped base part is divided or interrupted by a web part and comprises a first part and a second part.

[0009] In the e-axle transmission according to the invention, the first part of the trough-shaped base part is filled via a first lubricant feed path when the e-axle transmission is rotating in the forward direction, while the second part of the trough-shaped base part is filled via a second lubricant feed path when the e-axle transmission is rotating in the reverse direction.

[0010] The proposed solution eliminates the need for a return pump, which would be used to supply the lubricant accumulating in an oil pan to the collecting device. By appropriately designing the lubricant delivery paths in both directions of rotation of the electric-axle transmission, the solution proposed by the invention enables the lubricant to be transported to the collecting device, which is preferably located in the upper area of the electric-axle transmission housing.

[0011] In one embodiment of the e-axle transmission proposed according to the invention, the collecting device has, in particular, drain openings embedded in the trough-shaped base part, through which the lubricant drains, for example, between a first bearing of an input shaft of the e-axle transmission and a second bearing and a radial shaft seal of the input shaft. Through a cascade-shaped path, the lubricant dripping from the collecting device can be conveyed to the respective components within the e-axle module to be lubricated by gravity, without the need for a delivery unit in the form of a feed pump or a lubricant return pump.

[0012] According to the invention, the collecting device is pocket-shaped and incorporated into one of the two housing halves of the housing.

[0013] In one embodiment of the e-axle transmission proposed according to the invention, the lubricant in the first lubricant feed path and in the second lubricant feed path is conveyed into the collecting device through a differential cage and a differential gear arranged thereon and / or an intermediate gear or pinion of an intermediate shaft and / or a pinion on an input shaft. The proposed solution ensures that the collecting device arranged in the upper area of the housing of the e-axle transmission is supplied with lubricant in both directions of rotation of the e-axle transmission.

[0014] Furthermore, the invention relates to the use of the e-axle transmission in the drive train of an electrically powered vehicle or in the drive train of a hybrid drive of a motor vehicle provided with an internal combustion engine. Advantages of the invention

[0015] With the solution proposed by the invention, the initially mentioned increasingly stringent requirements for reversing an electrically powered vehicle can be met by the electric axle transmission. The costs for a return pump or a feed pump for the lubricating medium within the housing of the electric axle transmission can be reduced and, ideally, completely avoided, since the lubricating medium is pumped in both directions of rotation, i.e., for forward and reverse travel, through rotating components such as gears and the differential carrier within the housing of the electric axle transmission into the collecting device arranged in the upper region of the housing according to the invention. Thus, lubrication costs in the form of feed units, return pumps, lines, and the like can be eliminated.

[0016] Furthermore, the solution proposed by the invention can significantly extend the service life through appropriate lubrication of the radial shaft seal and bearings, even during extended reversing at medium to high speeds. Furthermore, the continuous supply of lubricant to the components of the electric axle transmission according to the invention can improve cooling, particularly at the radial shaft seal and at the bearing points of the input shaft, intermediate shaft, and in the area of the differential gear components.

[0017] The solution proposed according to the invention makes it possible to provide a collecting device with two reservoirs, which allows the lubricating medium thrown up by the gears to be collected from both sides, i.e., during forward and reverse travel, in order to supply the lubricating medium in deliberately different quantities to, for example, the radial shaft seal and the bearing, depending on whether the vehicle is moving forward or backward. Alternatively, the two reservoirs can also be connected to one another, for example, by an opening within a partition wall. This allows, for example, lubrication of the components during forward travel through oil guides that are normally only supplied with oil during reverse travel, and vice versa.For example, for a reverse drive, for example, for 60 minutes at a speed n—as well as for a reverse drive lasting 60 seconds—a large or small amount of lubricant can be directed to the radial shaft seal, for example, which ensures tightness by supplying a specific amount of oil, even if the oil flow direction is usually optimized for forward drive. The appropriate oil quantity for the radial shaft seal, for example, can be determined by the diameter or the general design of the oil supply from the oil pan to the radial shaft seal.

[0018] The collecting device for the lubricating medium, which is preferably T-shaped and is proposed according to the invention, presents a solution with which, after carrying out lubrication tests, a specific quantity of lubricating medium, determined in each case by the tests, can be conveyed to the radial shaft seal in order to ensure tightness when reversing - as is increasingly required by vehicle manufacturers - over a certain period of time at a certain speed.

[0019] Instead of a separate, T-shaped component as a collecting device for the lubricant, the collecting device can also be implemented through the casting mold of the housing or cover. A cost advantage can be achieved by designing the collecting device as a cast-in pocket in one of the housing halves. On the other hand, a greater degree of design freedom can be achieved by designing the collecting device as a separate component, for example, made of plastic or metal. Short description of the drawings

[0020] Embodiments of the invention are explained in more detail with reference to the drawings and the following description.

[0021] They show: Figure 1 a non-claimed Figure 2 collecting device for a lubricating medium, a side view of the collecting device for a lubricating medium according to Figure 1, Figure 3 shows a possible embodiment of the collecting device for a lubricating medium in one half of the housing and Figure 4 shows a side view of the Figure 3 illustrated design variant of the collecting device for a lubricating medium. Embodiments of the invention

[0022] In the following description of the embodiments of the invention, identical or similar elements are designated by the same reference numerals, whereby a repeated description of these elements is omitted in individual cases. The figures only schematically illustrate the subject matter of the invention.

[0023] According to the illustration Figure 1 an electric axle gearbox 10 can be seen, in whose housing 12 a collecting device 46 for lubricating medium is integrated.

[0024] The E-axle transmission 10 according to Figure 1comprises a housing 12 and an oil pan 14 located in the lower area including a differential gear 16. On the differential gear 16, a differential gear 18 is located on the differential carrier 22, which encloses a number of meshing bevel gears 20. On the output side, the differential gear 16 comprises a first output shaft 24 and a second output shaft 26. In the housing 12 of the electric axle transmission 10, an intermediate shaft 28 is also accommodated, on which an intermediate gear 30 is accommodated. Furthermore, in the housing 12 of the electric axle transmission 10, as shown in Figure 1 an input shaft 32 is included.

[0025] From the representation according to Figure 1It is further apparent that a collecting device 46 for lubricating medium is located in the upper region of the housing 12. The collecting device 46 can be manufactured as a separate component from plastic or metallic material and essentially comprises a vertically extending web part 48, at the lower ends of which a base part 50 is located. The base part 50 is flat or trough-shaped and comprises a first part 50.1 and a second part 50.2. Furthermore, drains 54 are provided on the sides of the flat or trough-shaped base part 50.

[0026] In the electric axle transmission 10, the lubricant is conveyed from the oil pan 14 along a first lubricant conveying path 42 in the direction of rotation 38 for forward travel. The lubricant is conveyed from the oil pan 14 through the differential cage 22 rotating therein, as well as the differential gear 18, an intermediate shaft pinion 29, the intermediate gear 30, and a pinion on an input shaft 32, corresponding to the first lubricant conveying path 42, into the first part 50.1 of the flat or trough-shaped base part 50 of the collecting device 46.

[0027] In contrast, the lubricating medium is conveyed in the direction of rotation 40 during reverse travel, starting from the differential cage 22, which rotates in the lubricating medium supply stored in the oil pan 14, further via the differential gear 18, the intermediate shaft pinion 29, the intermediate gear 30, which are received on the intermediate shaft 28, and via the pinion on the input shaft 32 into the second part 50.2 of the flat or trough-shaped bottom part 50 of the collecting device 46.

[0028] Figure 2 shows a side view of the E-axle transmission 10 as shown in Figure 1 .

[0029] Out of Figure 2It can be seen that outlets 54 are provided in the flat or trough-shaped bottom part 50 of the collecting device 46. Both during forward travel and during reverse travel, i.e. in the direction of rotation 38 as well as in the opposite direction of rotation 40, the lubricating medium drips through the outlets 54 due to the effect of gravity towards the oil pan 14 at the bottom of the housing 12. The outlets 54 are positioned so that, for example, the lubricating medium runs directly to a first bearing 34 of the input shaft 32 as well as to its second bearing 36 and a radial shaft seal 52. From the input shaft 32 to be lubricated, the lubricating medium reaches the intermediate shaft 28, the intermediate gear 30 there and the corresponding bearing points of the intermediate shaft 64 up to the differential gear 16 and is finally collected in the oil pan 14 in the lower area of the housing 12. By the web part 48, which is in Figure 2As shown in a side view, the flat or trough-shaped base part 50 is divided into the first part 50.1 and the second part 50.2. In each of the two parts 50.1 and 50.2 of the flat or trough-shaped base part 50, lubricant is conveyed according to the lubricant conveying paths 42, 44.

[0030] The proposed collecting device 46 generates two parts 50.1 and 50.2, which allow the lubricating medium thrown up by the gears 30, 18 and 62 as well as by the differential carrier 22 to be collected from both sides, i.e. in the direction of rotation 38 for forward travel and in the direction of rotation 40 for reverse travel, in order to deliver the lubricating medium in different quantities to, for example, the radial shaft seal 52 and to the second bearing 36 or the first bearing 34 of the input shaft 32, depending on the forward or reverse travel. In this way, a large or small amount of oil can be directed, for example, to the radial shaft seal 52 for a reverse travel, for example, lasting 60 minutes at a speed n, as well as for a reverse travel of more than 60 seconds. This ensures tightness when supplied with a certain amount of oil, even if this has an oil delivery direction which - as is generally the case - is suitable for forward travel, i.e.the direction of rotation 38 is optimized. The amount of oil determined in tests for the radial shaft seal 52, for example, can be determined by the diameter or the general design of the oil guide from the oil pan 14 to the radial shaft seal 52. The essentially T-shaped collecting device 46 represents a solution by means of which, when carrying out lubrication tests, a specific amount of lubricating medium determined by these tests can be conveyed to the radial shaft seal 52, placed on the input shaft 32, in order to ensure tightness when driving backwards, i.e. in the direction of rotation 40 of the E-axle transmission 10, as required by the customer, over a certain period of time or at a certain speed.

[0031] In the Figures 3 and 4 a variant of the e-axle transmission 10 proposed according to the invention is shown.

[0032] Figure 3 essentially corresponds to the already described Figure 1 , but with the difference that the collecting device 46 for the lubricating medium, which is arranged in the upper area of the housing 12 of the E-axle transmission 10, is located in only one housing half of the housing 12. In the illustration according to Figure 3 the collecting device 46 is not manufactured as a separate component made of metallic material or plastic material, but is pocket-shaped in one of the housing halves (see illustration according to Figure 4 ) was inserted. Figure 3also shows the first lubricant feed path 42 for the direction of rotation 38 for forward travel and the second lubricant feed path 44 for the direction of rotation 40 when the electric axle transmission 10 is traveling backwards. The lubricant is essentially fed from the oil pan 14 via the differential gear 18, the intermediate shaft pinion 29 and the intermediate gear 30 of the intermediate shaft 28 and via the pinion 62 of the input shaft 32, either into the first part 50.1 or into the second part 50.2 of the flat or trough-shaped base part 50 of the collecting device 46 for the lubricant.

[0033] According to the illustration Figure 4 is a side view of the Figure 3 illustrated embodiment of the e-axle transmission 10 according to the invention.

[0034] From the side view according to Figure 4It is clear that the housing 12 comprises the first housing half and the second housing half. The two housing halves lie sealingly against each other along a joint 56. From the side view according to Figure 4 It can be seen that the collecting device 46 for the lubricant is located in the second housing half in this embodiment. The collecting device 46 is cast into the second housing half in a pocket-like manner, i.e., it is manufactured directly during its production, eliminating the need for a separate component.

[0035] A pocket-shaped design of the collecting device 46 enables lower costs on the one hand and, on the other hand, less weight, since less material and, if necessary, improved oil flow in the electric axle transmission 10 can be achieved. A pocket-shaped collecting device 46 can ideally be produced at no additional cost - provided it is incorporated directly into the casting model. A pocket-shaped collecting device 46 produced only on one of the two housing halves of the housing 12 can also protrude beyond the parting line 56 between the two housing halves in order to create an enlarged collecting area for the conveyed lubricant, if necessary by a correspondingly larger design of the flat or trough-shaped base part 50.

[0036] Alternatively, the pocket can be positioned depending on the bearing and axle deflection angle of the e-axle gearbox 10.

[0037] In the versions of the Figures 1 and 2Such a collecting device 46 is realized as a separate component made of plastic material or metallic material.

[0038] The invention is not limited to the embodiments described here and the aspects highlighted therein. Rather, numerous modifications are possible within the scope of the claims, which are within the scope of expert practice.

Claims

1. E-axle gearbox (10), suitable for driving a vehicle forwards and in reverse, having a housing (12), which is formed from housing halves situated next to each other along a separating joint (56), having a differential gearbox (16), wherein a collecting device (46) for a lubricating medium is provided inside the housing (12), which collecting device can be filled with the lubricating medium in the two rotation directions (38, 40) of the E-axle gearbox (10), which are for forward travel and for reverse travel, when the E-axle gearbox drives a vehicle, wherein the collecting device (46) has a flat or a tub-like bottom part (50), wherein the flat or tub-like bottom part (50) is designed in a manner divided or interrupted by a web part (48) and comprises a first part (50.1) and a second part (50.2), wherein the E-axle gearbox (10) is configured to fill the first part (50.1) of the flat or tub-like bottom part (50) via a first lubricating medium conveying path (42) in the rotation direction (38) of the E-axle gearbox (10) for forward travel, and wherein the E-axle gearbox (10) is configured to fill the second part (50.2) of the flat or tub-like bottom part (50) via a second lubricating medium conveying path (44) in the rotation direction (40) of the E-axle gearbox (10) for reverse travel, characterized in that the collecting device (46) is incorporated in a pocket-like manner in one of the two housing halves of the housing (12).

2. E-axle gearbox (10) according to Claim 1, characterized in that the collecting device (46) is substantially T-shaped.

3. E-axle gearbox (10) according to Claims 1 and 2, characterized in that it has an input shaft (32) and a radial shaft sealing ring (52), and in that the collecting device (46) comprises drains (54), via which lubricating medium drains between a second bearing (36) of the input shaft (32) and a radial shaft sealing ring (52) and above a first bearing (34) of the input shaft (32).

4. E-axle gearbox (10) according to Claims 1 to 3, characterized in that lubricating medium is conveyed into the collecting device (46) through a differential cage (22) and through a differential gear (18), an intermediate gear (30), an intermediate shaft pinion (29), an intermediate shaft (28) and an input shaft (32) in the first lubricating medium conveying path (42) and in the second lubricating medium conveying path (44).

5. Use of the E-axle gearbox (10) according to any of Claims 1 to 4 in the drive train of an electrically driven vehicle or in the drive train of a hybrid drive of a motor vehicle, the hybrid drive being provided by means of an internal combustion engine.