Transmission for motor vehicles

Abstract

The present invention provides a transmission for a motor vehicle and a motor vehicle, wherein the transmission has a housing and a gear set surrounded by the housing, oil can be supplied to the gear set for lubrication, and the oil is collected in an oil sump of the transmission driven by gravity, wherein an oil drain groove is formed by the housing and / or by an element connected to the housing, and the oil drain groove is spatially arranged below the gear set, wherein the oil drain groove has at least one inlet opening on the gear set side, a closed bottom side, and an outlet opening on the oil sump side at one end of the oil drain groove, the outlet opening being designed and arranged so that oil flows from the gear set through the at least one inlet opening into the oil drain groove and is guided along the closed bottom side to the outlet opening, and wherein a suction opening of a hydraulic unit of the transmission is spatially arranged in the oil sump below the closed bottom side of the oil drain groove and is arranged axially offset from the outlet opening.

Description

Technical Field

[0001] The invention relates to a transmission for a motor vehicle and to a motor vehicle having such a transmission. Background Art

[0002] Such a transmission is described in DE 10 2016 217 242 A1. The housing of the transmission encloses a cavity, and the oil pool is connected to the housing. Figure 3 In an embodiment of the invention, a separating element is provided, which separates the cavity from another cavity assigned to the oil sump. The passage between the two cavities and the suction opening of the transmission hydraulic device are arranged in a common plane. Summary of the invention

[0003] The object of the present invention is now to improve the transmission known from the prior art.

[0004] This object is achieved by the features described herein. Advantageous embodiments emerge from the description and the drawings.

[0005] To achieve this object, a transmission for a motor vehicle is proposed, wherein the transmission has a housing and a gear set surrounded by the housing. The gear set is adapted to provide different transmission ratios between a drive shaft and an output shaft of the transmission. The gear set can be composed of a plurality of spur gear sets and / or a planetary gear set, for example. The transmission has a hydraulic system that supplies oil to the gear set for lubrication. The lubricating oil supplied to the gear set is collected in an oil pan of the transmission by gravity drive. The hydraulic system has a pump that sucks oil out of the oil pan and supplies it to the gear set and, if necessary, to other hydraulic consumers of the transmission.

[0006] The oil drain groove is formed by the housing and / or by an element connected to the housing. The oil drain groove is spatially arranged below the gear set and has at least one inlet opening on the gear set side, a closed bottom side, and an outlet opening on the oil sump side at one end of the oil drain groove. The oil drain groove is arranged and designed so that the oil flows from the gear set through the at least one inlet opening into the drain groove and is guided to the outlet opening along the closed bottom side of the oil drain groove. The suction opening of the hydraulic system arranged in the oil sump is spatially arranged below the closed bottom side of the oil drain groove and is arranged to be axially offset from the outlet opening. The term "axial" here refers to the axis of rotation of the transmission drive shaft.

[0007] This arrangement ensures that even when a motor vehicle with such a transmission is accelerated hard, no air reaches the intake opening. Since the bottom side of the oil drain groove is closed, oil cannot flow unhindered from the oil sump into the gear set during acceleration, so that more oil remains in the oil sump.

[0008] Preferably, the at least one inlet opening is arranged axially offset from the outlet opening. The term "axial" here relates to the axis of rotation of the transmission drive shaft. As a result, the oil can reach the oil drain groove from the gear set over a shorter path, thereby reducing flange losses of the rotating parts of the gear set.

[0009] Preferably, the oil drain groove has a plurality of inlet openings. As a result, the oil flow from the gear set into the oil drain groove can be influenced in a targeted manner.

[0010] Preferably, the oil drain groove has an outlet opening at only one end. Thus, under certain operating conditions of the motor vehicle, oil cannot flow unimpeded from the oil pan into the gear set, so that more oil remains in the oil pan.

[0011] Preferably, the closed bottom side of the oil drain groove is at least partially formed by the hydraulic unit connected to the housing. As a result, the housing, which is usually produced by casting, can be produced more easily.

[0012] According to a preferred design, the housing has a housing wall, wherein the outlet opening is spatially arranged directly below the housing wall. The housing wall can be arranged between the gear set and a cavity of the transmission located upstream of the gear set, wherein this cavity located upstream is at least partially surrounded by the housing. This cavity located upstream can, for example, accommodate an electric machine and / or a torque converter, wherein one or both of these elements can be connected to the drive shaft of the transmission. This cavity can be designed as a wet space, wherein the oil flowing out of the cavity is collected in the oil pan driven by gravity. Openings can be provided in the housing wall to ensure pressure balance between the gear set space and the mentioned cavity.

[0013] Preferably, the transmission for a motor vehicle is provided with a drive train oriented parallel to the direction of travel of the motor vehicle, so that the drive shaft and the output shaft of the transmission are oriented parallel to the direction of travel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The following is a detailed description of the embodiments with reference to the accompanying drawings. In the accompanying drawings:

[0015] Figure 1 A schematic diagram showing a motor vehicle;

[0016] Figure 2a schematic representation showing a powertrain of a motor vehicle; and

[0017] Figures 3 to 6 Each shows a schematic sectional view of a transmission of a motor vehicle. DETAILED DESCRIPTION

[0018] Figure 1 A motor vehicle K is shown schematically, wherein an arrow illustrates the forward travel direction X of the motor vehicle K. The front wheels NDW of the motor vehicle K are not driven; the rear wheels DW of the motor vehicle K are driven.

[0019] Figure 2 The powertrain of a motor vehicle K is shown schematically. The combustion engine VM is coupled to a transmission G. The output shaft GW2 of the transmission G is connected to a differential AG. Via the differential AG, the torque of the output shaft GW2 is distributed to the rear wheels DW of the motor vehicle K. The arrow shows the forward driving direction X of the motor vehicle K.

[0020] Naturally, the invention is not limited to a transmission G for such a drivetrain configuration. The transmission G may be used, for example, in an all-wheel drive drivetrain or in a drivetrain with front-wheel drive. Alternatively or in addition, the combustion engine VM and / or the transmission G may be arranged in the region of the vehicle's rear axle, or even between the front axle and the rear axle.

[0021] Figure 3 Schematic cross-sectional view of a transmission G is shown. The transmission G has a housing GG. The housing GG accommodates Figure 3 The gear set RS is shown only schematically in the figure. Different transmission ratios can be provided between the drive shaft GW1 and the output shaft GW2 by means of the gear set RS. For this purpose, for example, a planetary gear set and / or a spur gear set can be used. In order to lubricate the elements of the gear set RS, oil is supplied to the gear set RS. For example, the oil can be supplied through the drive shaft GW1 and / or through the output shaft GW2, or it can also be supplied through an oil channel in the housing GG. The oil supplied to the gear set RS is collected in the oil sump S of the transmission G driven by gravity. The oil sump S consists of a cavity, which is composed of the housing GG and an oil tank OW fastened to the housing GG. A hydraulic unit HY, such as a hydraulic control device and / or a hydraulic filter, is arranged in the oil sump S. The hydraulic unit HY has a suction opening OF. The oil is sucked out of the oil sump S through the suction opening OF and is supplied to the gear set RS and, if necessary, to other hydraulic consumers of the transmission G. For this purpose, a hydraulic pump is provided, which is Figure 3 Not shown.

[0022] The housing GG has a housing wall ZP. The housing wall ZP separates the gear set RS from the cavity G1 of the transmission G. The cavity G1 is at least partially delimited by the housing GG. A torque converter TC is arranged in the cavity G1, which has a pump wheel PR, a turbine wheel TR and a stator wheel LR. The pump wheel PR is connected to the connecting shaft AN. The crankshaft of the combustion engine VM can be connected to the connecting shaft AN, and if necessary, a gear wheel is connected in the middle. Figure 3 Device for reducing torsional vibrations not shown in the drawing. The turbine TR is connected to the drive shaft GW1. The stator LR is supported on the housing wall ZP via a free wheel F. The pump wheel PR, the turbine TR and the stator LR interact hydrodynamically in a known manner. The turbine TR and the pump wheel PR can be mechanically connected to each other via a locking clutch WK. Instead of the torque converter TC, a dual clutch unit or a conventional starting clutch may be arranged in the cavity G1. As an alternative to this, one of the switching elements of the gear set RS can be used as a starting element, so that the torque converter TC or other starting devices in the cavity G1 can be omitted.

[0023] An electric machine EM is also arranged in the cavity G1, which has a stator ST and a rotor RO. The stator ST is fastened to the housing GG in a rotationally fixed manner. The rotor RO is connected to the connecting shaft AN. This arrangement is to be regarded as exemplary only. Alternatively, the rotor RO could be connected to the drive shaft GW1. It is also possible to completely eliminate the electric machine EM.

[0024] The cavity G1 constitutes a wet space. The oil flowing out of the cavity G1 is collected in the oil pan S driven by gravity. An opening ZPA is provided in the housing wall ZP to ensure pressure balance between the gear unit space and the cavity G1.

[0025] Below the gear set RS, the housing GG together with the hydraulic unit HY fastened to the housing GG forms an oil drain groove D. The oil drain groove D has three inlet openings DE1, DE2, DE3, a closed bottom side DL, and an outlet opening DA. The outlet opening DA is arranged directly below the housing wall ZP and is arranged axially offset to the inlet openings DE1, DE2, DE3. The suction opening OF of the hydraulic unit HY is spatially arranged below the closed bottom side DL and is arranged axially offset to the outlet opening DA.

[0026] exist Figure 3 The oil level OL in the oil sump S is shown in Figure 1. Naturally, the oil level varies depending on the temperature of the oil and on the operating state of the motor vehicle K having the transmission G. Figure 31 shows the oil level OL at a medium operating temperature of the oil and in a stationary state of the motor vehicle K on a flat surface, wherein in this operating state the oil drain groove D is at least partially filled with oil. Naturally, if the motor vehicle K is parked on a slope, for example, a slope may be formed. Figure 3 Different oil levels are shown in .

[0027] Figure 4 A schematic cross-sectional view of a transmission G is shown, which is connected to the transmission in FIG. Figure 3 . The figure now shows the oil level OL obtained with a moderate acceleration of the motor vehicle K in the direction X. In this operating state, the oil flows from the oil sump S via the oil drain groove D to the rear section of the gear set RS. In this case, the suction opening OF is in the oil anyway, so that no air is sucked in via the suction opening OF.

[0028] Figure 5 A schematic cross-sectional view of a transmission G is shown, which is connected to the transmission in FIG. Figure 3 The diagram corresponds to the diagram shown in FIG. Now, the oil level OL obtained in the case of a strong acceleration of the motor vehicle K in the direction X is shown in this figure. The acceleration is greater here than in Figure 4 . In this operating state, due to the arrangement of the outlet opening DA and the closed bottom side DL of the oil drain groove D, no oil can reach the gear set RS from the oil sump S. The oil that is already in the gear set RS at this point in time accumulates in the rear region of the gear set RS. In this case, the suction opening OF is in the oil anyway, so that no air can be sucked in via the suction opening OF.

[0029] For this mode of operation, complete sealing between the rear gear unit space and the rear region of the oil pan S is advantageous, but not a prerequisite. If complete sealing is not possible, the oil flow from the rear region of the oil pan S to the rear gear unit space can be delayed, for example, by forming a labyrinth and intentionally reducing the gap size. This is usually sufficient, since the duration of intense acceleration processes is not long.

[0030] Figure 6 A schematic cross-sectional view of a transmission G is shown, which is generally similar to the transmission shown in FIG. Figure 3 A folding mechanism KK is added to the transmission G, which makes it more difficult for oil to flow from the oil pan S into the cavity G1 during heavy braking of the motor vehicle. With the help of such a device, it can also be ensured during heavy deceleration of the motor vehicle K that the suction opening OF is always in the oil and therefore no air is sucked in.

[0031] The dimensional ratios shown in the drawings are for illustration purposes only and should not be considered to be to scale.

[0032] List of Reference Numerals

[0033] K Motor Vehicles

[0034] X Forward driving direction

[0035] NDW front wheel

[0036] DW rear wheel

[0037] VM combustion engine

[0038] G Transmission

[0039] AN connecting shaft

[0040] GW1 drive shaft

[0041] GW2 output shaft

[0042] AG Differential

[0043] RS Gear Set

[0044] GG Housing

[0045] G1 Cavity

[0046] ZP Housing wall

[0047] ZPA opening

[0048] S Oil sump

[0049] OW oil pool

[0050] HY Hydraulic Unit

[0051] OF suction opening

[0052] TC Torque Converter

[0053] PR pump impeller

[0054] TR Turbine

[0055] LR Guide Wheel

[0056] F Freewheel

[0057] WK Lock-up Clutch

[0058] EM Electric Machine

[0059] ST Stator

[0060] RO rotors

[0061] D Oil drain tank

[0062] DE1 Inlet opening

[0063] DE2 Inlet opening

[0064] DE3 Inlet opening

[0065] DL bottom side

[0066] DA outlet opening

[0067] OL Oil level

[0068] KK Folding Mechanism

Claims

1. A transmission (G) for a motor vehicle (K), characterized in that The transmission (G) comprises a housing (GG) and a gear set (RS) enclosed by the housing (GG), wherein the gear set (RS) is adapted to provide different transmission ratios between a drive shaft (GW1) and an output shaft (GW2) of the transmission (G), wherein the gear set (RS) can be supplied with oil for lubrication, the oil being collected in an oil sump (S) of the transmission (G) driven by gravity, wherein an oil drain groove (D) is formed by the housing (GG) and / or by an element connected to the housing (GG), the oil drain groove being spatially arranged below the gear set (RS), wherein the oil drain groove (D) comprises: at least one inlet opening (DE1, DE2) on the gear set side; DE2, DE3), a completely closed bottom side (DL) and a single outlet opening (DA) on the oil sump side at one end of the oil drain groove (D), the outlet opening being designed and arranged so that oil flows from the gear set (RS) through the at least one inlet opening (DE1, DE2, DE3) into the oil drain groove (D) and is guided along the completely closed bottom side (DL) to the outlet opening (DA), and wherein a suction opening (OF) of a hydraulic unit (HY) of the transmission (G) is spatially arranged in the oil sump (S) below the completely closed bottom side (DL) of the oil drain groove (D) and is arranged axially offset from the outlet opening (DA).

2. The transmission (G) according to claim 1, characterized in that: The at least one inlet opening (DE1 , DE2, DE3) is arranged axially offset from the outlet opening (DA).

3. The transmission (G) according to claim 1 or 2, characterized in that: The oil drain groove (D) has a plurality of inlet openings (DE1, DE2, DE3).

4. The transmission (G) according to claim 1 or 2, characterized in that: The oil drain groove (D) has an outlet opening (DA) at only one end.

5. The transmission (G) according to claim 1 or 2, characterized in that: The completely closed bottom side of the oil drain groove (D) is formed at least in sections by the hydraulic unit (HY) connected to the housing (GG).

6. The transmission (G) according to claim 1, characterized in that The housing (GG) has a housing wall (ZP), wherein the outlet opening (DA) is arranged spatially directly below the housing wall (ZP).

7. The transmission (G) according to claim 6, characterized in that The housing wall (ZP) is arranged between the gear set (RS) and a cavity (G1) of the transmission (G) located upstream of the gear set (RS), wherein the cavity (G1) is at least partially surrounded by the housing (GG).

8. The transmission (G) according to claim 7, characterized in that The cavity (G1) accommodates an electric machine (EM) and / or a torque converter (TC).

9. The transmission (G) according to claim 7 or 8, characterized in that The cavity (G1) is designed as a wet space, wherein the oil flowing out of the cavity (G1) is collected in the oil sump (S) driven by gravity.

10. The transmission (G) according to claim 7 or 8, characterized in that An opening (ZPA) is provided in the housing wall (ZP) in order to ensure pressure balance between the gear set (RS) and the cavity (G1).

11. A transmission (G) according to claim 1 or 2, characterized in that The transmission (G) for a motor vehicle (K) is provided with a drive train oriented parallel to a driving direction (X) of the motor vehicle (K), so that a drive shaft (GW1) and an output shaft (GW2) are oriented parallel to the driving direction (X). 12 . A motor vehicle (K) having a transmission (G) according to claim 1 .

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