Transmission having a displacement body for a drivetrain

Abstract

The invention relates to a transmission (10) for a drivetrain (100) of a motor vehicle (K), comprising: a transmission housing (20); at least two drive elements (30, 40) which are in engagement with one another and accommodated in a housing interior (22) of the transmission housing (20); at least one displacement body (60) designed to displace lubricant (12) which is accommodated in the housing interior (22) and is used for lubricating the at least two drive elements; and a lubricant exchange opening (24) via which the lubricant (12) is can be exchanged between the housing interior (22) and a peripheral region (P) surrounding the housing interior (22). The at least one displacement body (60) has at least one lubricant-guiding region (62) which is designed to guide the lubricant (12), at least in regions, along the displacement body (60) and within the housing interior (22) to the lubricant exchange opening (24). A further aspect of the invention relates to a motor vehicle (K) having a drivetrain (100) that comprises a drive motor (110) and a transmission (10) that is to be driven by means of the drive motor (110).

Description

[0001] Gearbox with a displacement body for a drive train

[0002] The invention relates to a transmission for a drive train of a motor vehicle, comprising a transmission housing, at least two mutually engaging drive elements which are accommodated in a housing interior of the transmission housing, at least one displacement body which is designed to displace lubricant accommodated in the housing interior and used to lubricate the at least two drive elements, and a lubricant exchange opening via which the lubricant can be exchanged between the housing interior and a peripheral region surrounding the housing interior. A further aspect of the invention relates to a motor vehicle with such a transmission.

[0003] Such displacement bodies serve to reduce the amount of lubricant carried within the transmission, whereby the displacement allows a high lubricant fill level within the transmission even with small amounts of lubricant. For example, DE 10 2010 010 816 A1 shows a transmission comprising at least functional parts and a transmission housing, wherein a displacement body is arranged between the functional parts and the transmission housing and is designed as a hollow body.

[0004] EP 1 389697 A2 discloses a transmission for a motor vehicle, comprising at least one gear set for power transmission and a housing in which the gear set is mounted. The transmission contains a fluid lubricant for the gear set and a gas. The desired quantity of lubricant in the housing is selected such that at least one lower wheel of the gear set is immersed in the lubricant even under unfavorable operating conditions. A displacement body for the lubricant is arranged in the housing and is at least predominantly immersed in the lubricant. The displacement body is a part of a housing cover facing into the interior of the housing.

[0005] The object of the present invention is to further develop a transmission with a displacement body and a motor vehicle of the type mentioned above in such a way that improved lubricant movement is possible. This object is achieved by a transmission with the features of patent claim 1 and by a motor vehicle with the features of patent claim 10. Advantageous embodiments with expedient further developments of the invention are specified in the subclaims.

[0006] A first aspect of the invention relates to a transmission for a drive train of a motor vehicle, comprising a transmission housing, at least two mutually engaging drive elements which are accommodated in a housing interior of the transmission housing, at least one displacement body which is designed to displace lubricant accommodated in the housing interior and used to lubricate the at least two drive elements, and a lubricant exchange opening via which the lubricant can be exchanged between the housing interior and a peripheral region surrounding the housing interior. The drive elements can preferably be elements for torque transmission, such as gears, which are engaged with one another.

[0007] According to the invention, the at least one displacement body has at least one lubricant guide region, which is designed to guide the lubricant at least partially along the displacement body and within the housing interior toward the lubricant exchange opening. This is advantageous because the displacement body can specifically displace the lubricant contained in the housing interior, usually in the form of gear oil. This allows the lubricant to reach the machine elements to be lubricated and / or cooled by the lubricant, which may include the drive elements, even with a low lubricant content in the housing interior.The lubricant guide region enables targeted, low-resistance, and active suction of the lubricant, for example, using a lubricant pump, without the lubricant exchange opening being narrowed or blocked by the displacement body during suction. This improves lubricant movement during exchange via the lubricant exchange opening. Preferably, the lubricant guide region can be designed to guide the lubricant along several different spatial directions, which can be perpendicular to one another, for example. This is possible, for example, because the lubricant guide region can have interconnected lubricant channels oriented at an angle to one another. These lubricant channels can, for example, be designed as respective through-openings for guiding the lubricant or as respective grooves for guiding the lubricant.The lubricant guide area can particularly preferably be open in the direction of the housing interior, so that the lubricant can be led out of or into the housing interior without hindrance via the lubricant guide area and the lubricant exchange opening.

[0008] The invention is based on the finding that conventional vehicle transmissions, particularly transmissions designed to be driven by electric motors as drive motors, contain large air volumes in the corresponding housing interiors. Accordingly, conventional systems require large quantities of lubricant, which are introduced into the housing interior to supply the machine elements that require lubrication and / or cooling.

[0009] The use of the displacement body with its lubricant guide area allows, on the one hand, the displacement of lubricant within the housing interior to such machine elements even with small quantities of lubricant in the housing interior and, on the other hand, due to the lubricant guide area, a reliable exchange of the lubricant with improved lubricant movement.

[0010] In order to ensure sufficient cooling of a transmission cooled by lubricant, in particular oil, which may, for example, be associated with an electric machine in a motor vehicle's drivetrain, it is advantageous to provide a sufficient volume flow of lubricant, for example, at a main snorkel of a lubricant pump, which may preferably be designed as a pressure pump, in particular as a pressure oil pump. In sport-oriented electric machines (e-machines for short), also called electric motors, this can preferably be achieved by active lubricant suction pumps, which actively suck lubricant from defined areas of the electric machine during dynamic driving maneuvers (lateral / longitudinal dynamics, i.e., high lateral and / or longitudinal acceleration) of the motor vehicle, whereby the lubricant can be fed back in near the main snorkel.

[0011] The basic principle of the invention lies in the reduction of an air volume via displacement bodies in the transmission area, which are intended to reduce the lubricant volume in the transmission, i.e. in the housing interior of the transmission. In this way, the potentially available volume for lubricant accumulation (oil accumulation) within this area of ​​the electric motor is reduced. This leads, particularly under transverse dynamics with a displacement body arranged in the housing interior, to significantly improved lubricant availability at an active extraction point of the transmission due to at least a largely avoided dead air volume. The essential goal of this invention is the reduction of the lubricant volume and the associated cost and weight savings on one or more electric motors while optimizing the lubricant supply at the active extraction points using the principle of volume displacement by filler bodies.

[0012] In an advantageous development of the invention, the at least one displacement body is different from a machine element. This advantageously allows a particularly weight-optimized design of the displacement body. The displacement body can therefore be relieved of the tasks of torque transmission, fastening, bearing, support and / or housing functions within the housing interior. For example, the displacement body does not have to support a gear shaft or another machine element, nor does it have to contribute to torque transmission by engaging with a gearing, to name just a few examples. The term machine element includes, for example, axles, shafts, bearings, gears, switching elements (such as clutch elements or claws), and fastening elements such as screws.

[0013] In a further advantageous development of the invention, the displacement body fills at least 20%, preferably at least 40%, and particularly preferably at least 60% of the housing interior. This is advantageous because the displacement body can thus be dimensioned particularly according to requirements. The larger the percentage of the housing interior occupied by the displacement body, the more reliable the lubricant supply to machine elements, such as the drive elements of the transmission, even at high longitudinal and lateral accelerations during vehicle operation. At lower longitudinal and lateral accelerations, however, it may be sufficient for the displacement body to occupy only a small portion, for example, between 20% and 40% of the housing interior, so that the displacement body can be dimensioned accordingly smaller and weight can be saved.Overall, the displacement body can therefore occupy, for example, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% or 60% of the housing interior. In a further advantageous development of the invention, the displacement body encompasses at least one of the drive elements, at least in part. This is advantageous because the displacement body can thereby occupy a particularly large proportion of the housing interior and / or the lubricant can be guided by the displacement body in a particularly needs-based and targeted manner to points to be lubricated, for example gears or bearing points. The displacement body can preferably be arranged, at least in part, between the outer circumference of at least one of the drive elements and a housing area of ​​the transmission housing closest to the outer circumference.

[0014] Preferably, the displacement body can at least predominantly, preferably completely, enclose the circumference of at least one of the drive elements. The term "predominantly enclosing the circumference" is understood here to mean that the displacement body encompasses more than 50% of the circumference of the corresponding drive element. If the drive element is designed, for example, as a shaft or a gear, the displacement body can extend along such a drive element, preferably by more than a central angle of 180° lying on a rotational axis of the drive element, for example, 181° or more.

[0015] In a further advantageous development of the invention, the transmission comprises at least one additional displacement body, which is different from the displacement body and, like the displacement body, encompasses at least one of the drive elements, at least in part. Advantageously, the displacement body and the additional displacement body can together almost completely enclose the at least one drive element, so that the displacement body and the additional displacement body together occupy a particularly large portion of the housing interior. The required lubricant volume in the housing interior can be correspondingly low.

[0016] In a further advantageous development of the invention, the displacement body and / or the additional displacement body comprises at least one recess for at least partially inserting at least one of the drive elements. This is advantageous because the displacement body and / or the additional displacement body can thereby almost completely enclose the corresponding drive element, since the displacement body can extend along the circumference of the drive element over a central angle of 360° relative to the axis of rotation of the drive element. This can be achieved, for example, if the displacement body has a cylindrical recess into which a drive element, for example designed as a gear, is inserted and thereby circumferentially surrounded.Preferably, a gap can be provided between the displacement body and the additional displacement body, through which a circulation of the lubricant within the housing interior is improved.

[0017] In a further advantageous development of the invention, the lubricant guide region comprises a through-hole for guiding the lubricant and / or a groove for guiding the lubricant. This is advantageous because the lubricant can be guided to the lubricant exchange opening in a targeted manner with minimal flow resistance. For this purpose, the through-hole and the lubricant exchange opening can particularly preferably overlap.

[0018] In a further advantageous embodiment of the invention, the displacement body is made of a non-metallic material, in particular plastic. This is advantageous because it allows the displacement body to be designed to be particularly lightweight.

[0019] In a further advantageous development of the invention, the transmission comprises a lubricant pump which is connected to the lubricant exchange opening for sucking lubricant out of the housing interior. This is advantageous because the lubricant pump can be used to specifically suck the lubricant out of the housing interior. The displacement body can be used to form lubrication gap areas between the displacement body and a housing wall of the transmission housing, in which lubrication gap areas a high flow velocity of the lubricant can be achieved by sucking out the lubricant, which can lead, for example, to a high heat transfer coefficient at the housing wall and / or promote improved removal of any contaminants, e.g. abrasion. The lubricant pump can preferably be designed as a lubricant suction pump.

[0020] A second aspect of the invention relates to a motor vehicle with a drive train comprising a drive motor and a transmission driven by the drive motor according to the first aspect of the invention. This motor vehicle enables improved lubricant movement while requiring a small amount of lubricant. The drive motor can be an electric motor. In principle, however, a design of the drive motor as an internal combustion engine is also conceivable. The preferred embodiments presented with respect to one of the aspects and their advantages apply accordingly to the other aspects of the invention, and vice versa.

[0021] The features and combinations of features mentioned above in the description as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention.

[0022] Further advantages, features and details of the invention emerge from the claims, the following description of preferred embodiments and from the drawings.

[0023] The invention is explained once again below using a specific embodiment. This shows:

[0024] Fig. 1 is an abstract representation of a motor vehicle and its drive train, which has a drive motor and a transmission to be driven by the drive motor, shown in a schematic sectional view; and

[0025] Fig. 2 is an enlarged view of an area A outlined in Fig. 1.

[0026] Fig. 1 shows a schematic representation of a motor vehicle K with a drive train 100, which comprises a drive motor 110 and a transmission 10 driven by the drive motor 110. Fig. 2 shows a partial area A outlined in Fig. 1 in an enlarged view. The drive motor 110 is designed as an electric drive machine and is connected to the transmission 10 in a torque-transmitting manner. The respective arrows in Fig. 1 illustrate a drive 18 and an output 19.

[0027] The transmission 10 comprises a transmission housing 20 with a housing wall 21, mutually engaging drive elements 30, 40 which are accommodated in a housing interior 22 of the transmission housing 20, a displacement body 60 and an additional displacement body 70 which are designed to displace lubricant 12 which is accommodated in the housing interior 22 and serves to lubricate the drive elements. Furthermore, a lubricant exchange opening 24 is provided, via which the lubricant 12 can be exchanged between the housing interior 22 and a peripheral region P surrounding the housing interior 22. The displacement body 60 has a lubricant guide region 62 which is designed to guide the lubricant 12 at least partially along the displacement body 60 and within the housing interior 22 towards the lubricant exchange opening 24.

[0028] In addition to the displacement body 60, an additional displacement body 70 is also provided. Both the displacement body 60 and the additional displacement body 70 are each separate machine elements and can each be formed from a non-metallic material. In the present variant of the transmission 10, the displacement body 60 and the additional displacement body 70 are formed from a plastic. The displacement body 60 and the additional displacement body 70 form respective lubrication gap regions 16 between the displacement body and the housing wall 21 of the transmission housing 20. The displacement body 60 and the additional displacement body 70 displace the lubricant contained in the housing interior 22, so that a high lubricant level is achieved even with a small amount of lubricant contained in the housing interior 22.In addition, the displacement ensures that even at high values ​​of acceleration a occurring during driving operation of the motor vehicle K, which is indicated by an arrow in Fig. 1, sufficient lubricant reaches the respective machine elements to be lubricated, such as the drive elements 30, 40 or the respective rolling bearings of the transmission 20. The acceleration a can be a longitudinal acceleration and / or a lateral acceleration.

[0029] The displacement body 60 and the additional displacement body 70, which is different from the displacement body 60, can together fill at least 20%, preferably at least 40%, and particularly preferably at least 60% of the housing interior 22. The remaining portions of the housing interior are filled by the drive elements 30, 40, which are designed as gears, and other machine elements, such as rolling bearings, as can be seen schematically in Fig. 1.

[0030] The displacement body 60 and the additional displacement body 70 each partially encompass the two drive elements 30, 40. For this purpose, the displacement body 60 and the additional displacement body 70 have respective recesses 64, 74 for at least partially inserting at least one of the drive elements 30, 40. The recesses 64, 74 can, for example, be cylindrical in shape at least partially or hollow-cylindrical in shape at least partially, whereby a lubrication gap of uniform thickness can be formed in the region of the toothing of the drive elements 30, 40, which are here designed as gears, at least partially circumferentially along the toothing. This enables a homogeneous lubricant distribution over the outer circumference of the drive elements 30, 40, at least partially.The displacement body 60 and the additional displacement body 70 can engage the drive elements 30, 40 from opposite directions and thus on different sides. This allows, on the one hand, the respective drive elements 30, 40 to be located between the displacement body 60 and the additional displacement body 70, and, on the other hand, a gap 76 can remain between the displacement body 60 and the additional displacement body 70, as can be seen in Fig. 1. The gap 76 ensures that the lubricant can reach the drive elements 30, 40 and flow away from these drive elements 30, 40. This ensures a direct exchange of lubricant at the drive elements 30, 40.

[0031] The lubricant guide region 24 comprises at least one through-opening 26 for guiding the lubricant 12 and additionally or alternatively a groove (not shown further) for guiding the lubricant 12. The through-opening 26 is formed in the present case from channels oriented at an angle, in particular at right angles, to one another, which extend through the displacement body 60.

[0032] To discharge the lubricant from the housing interior 22 via the lubricant guide area 24, the transmission 10 comprises a lubricant pump 14, which is connected to the lubricant exchange opening 24 for sucking lubricant 12 out of the housing interior 22. The lubricant exchange opening represents a suction point of the transmission 10, wherein active lubricant suction (here: oil suction) can be performed at the suction point using the lubricant pump 14. Suctioning by the lubricant pump 14 creates a lubricant volume flow 13, which is indicated by the respective arrows in Fig. 2. List of Reference Symbols

[0033] 10 gearboxes

[0034] 12 Lubricants

[0035] 13 Lubricant volume flow

[0036] 14 Lubricant pump

[0037] 16 Lubrication gap area

[0038] 18 Drive

[0039] 19 downforce

[0040] 20 Gearbox housing

[0041] 21 Housing wall

[0042] 22 Housing interior

[0043] 24 Lubricant exchange opening

[0044] 26 passage opening

[0045] 30 drive element

[0046] 40 drive element

[0047] 60 displacement bodies

[0048] 62 Lubricant guide area

[0049] 64 recess

[0050] 70 additional displacement bodies

[0051] 74 recess

[0052] 76 gap

[0053] 100 Powertrain

[0054] 110 drive motor

[0055] K Motor vehicle

[0056] P Peripheral area a Acceleration

Claims

Claims 1. Transmission (10) for a drive train (100) of a motor vehicle (K), comprising a transmission housing (20), - at least two drive elements (30, 40) which are in engagement with one another and are accommodated in a housing interior (22) of the transmission housing (20), at least one displacement body (60) which is designed to displace lubricant (12) which is accommodated in the housing interior (22) and serves to lubricate the at least two drive elements, and a lubricant exchange opening (24) via which the lubricant (12) can be exchanged between the housing interior (22) and a peripheral region (P) surrounding the housing interior (22), characterized in that the at least one displacement body (60) has at least one lubricant guide region (62) which is designed to guide the lubricant (12) at least partially along the displacement body (60) and within the housing interior (22) towards the lubricant exchange opening (24).

2. Transmission (10) according to claim 1, characterized in that the at least one displacement body (60) is different from a machine element.

3. Transmission (10) according to claim 1 or 2, characterized in that the displacement body (60) fills at least 20%, preferably at least 40% and particularly preferably at least 60% of the housing interior (22).

4. Transmission (10) according to one of the preceding claims, characterized in that the displacement body (60) surrounds at least one of the drive elements (30, 40) at least in regions.

5. Gearbox (10) according to one of the preceding claims, characterized in that the gearbox (10) comprises at least one additional displacement body (70) which is different from the displacement body (60) and at least partially encompasses at least one of the drive elements (30, 40) as well as the displacement body (60).

6. Transmission (10) according to claim 5, characterized in that the displacement body (60) and / or the additional displacement body (70) comprises at least one recess (64, 74) for at least partially inserting at least one of the drive elements (30, 40).

7. Gearbox (10) according to one of the preceding claims, characterized in that the lubricant guide region (24) comprises a through opening (26) for guiding the lubricant (12) and / or a groove for guiding the lubricant (12).

8. Gearbox (10) according to one of the preceding claims, characterized in that the displacement body (60) is formed from a non-metallic material, in particular plastic.

9. Gearbox (10) according to one of the preceding claims, characterized in that the gearbox (10) comprises a lubricant pump (14) which is connected to the lubricant exchange opening (24) for sucking lubricant (12) out of the housing interior (22).

10. Motor vehicle (K) with a drive train (100) which comprises a drive motor (110) and a transmission (10) to be driven by the drive motor (110) according to one of the preceding claims.

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