DE102022112058A1 - Oil reservoir in a drive housing of a motor vehicle - Google Patents

Abstract

The invention relates to a drive housing for a motor vehicle drive unit with an electric drive machine and an output gear, having an outer housing wall for delimiting a housing interior in which oil lubrication is provided, an inner housing wall which delimits an oil reservoir, so that an oil sump arranged therein is away from everyone lubricating and/or components to be cooled are arranged.

Description

The invention relates to a drive housing for a motor vehicle drive unit and a method for lubricating and cooling a motor vehicle drive unit in a drive housing.

In the present case, interest is focused on electrically powered motor vehicles, for example electric or hybrid vehicles. Such motor vehicles usually have one or two or more electric drive units. A drive unit has, for example, an electric machine (hereinafter also referred to as an electric machine) with a stator arrangement and a rotor arrangement, as well as an output gear connected thereto via the rotor shaft for translating and/or converting the drive torque or the rotor speed, possibly with a differential gear, on.

These components are often arranged within a jointly formed housing interior of a drive housing of the motor vehicle drive unit and must be lubricated and cooled there in many operating cases, in particular during driving.

The stator core outer jacket of the electric drive machine can typically be indirectly cooled indirectly from a housing jacket in which it is accommodated. For cooling the other drive components arranged in the housing, hereinafter also referred to as the stator core periphery, direct and indirect cooling variants are already known from the prior art.

The direct cooling variants for the electric machine include, for example, the application or spraying of oil droplets onto winding heads of the windings of a stator and/or rotor of the electric machine and onto the gears of the output transmission, with the stator core also being cooled on the housing side by means of this oil cooling.

In the known direct cooling variants in the drive housing, the components of the output gear are lubricated and cooled either as splash lubrication or as injection lubrication.

Classic splash lubrication has a significant efficiency disadvantage compared to injection lubrication. In an electric drive unit, in which the electric machine is cooled using gear oil, there is a simple and cost-effective design for an oil circuit between the gearbox and the electric motor, in which the electric motor part does not have to be switched by switching valves (active/passive). etc. can be separated. This means that without further measures, oil is pumped into the electric machine even in the low-load range, in which no cooling is necessary. This oil also leads to efficiency disadvantages in the electric machine, among other things due to high shear friction of the oil in the gap between the rotor and stator.

Against this background, it is an object of the invention to improve cooling of an electric drive unit in a motor vehicle.

Each of the independent claims, with its characteristics, defines an object that solves this problem. The dependent claims relate to advantageous developments of the invention.

1. (a) eine Gehäuseaußenwand zur Abgrenzung eines, insbesondere bis auf vorgesehene Zu- und Ableitungen Schmieröl-dichten, Gehäuseinnenraums, in welchem eine Ölschmierung zur Schmierung und/oder zur Kühlung des Getriebes und/oder der Antriebsmaschine vorgesehen ist. Insbesondere ist also in dem Gehäuseinnenraum ein offener Teil eines Schmierölkreislaufs ausgebildet, der zudem in dem oder außerhalb des Gehäuses eine Ölpumpe vorsieht. Unter einem offenen Teil des Schmierölkreislaufs ist vorliegend insbesondere das Gehäuseinnere oder ein Teil davon zwischen einem oder mehreren Spitzölauslässen eines geschlossenen Teils des Schmierölkreislaufs und einem Ölsumpf in dem Gehäuseinneren zu verstehen, wobei das Schmieröl aus dem Ölsumpf oder einer anderen Förderstelle in einem weiteren geschlossenen Teil des Schmierölkreislaufs der Ölpumpe zugefördert werden kann; und/oder
2. (b) eine Gehäusebinnenwand, die, insbesondere alleine oder im Zusammenwirken mit einem Teil der Gehäuseaußenwand, ein Ölreservoir abgrenzt, das insbesondere für einen Ölsumpf der Ölschmierung und/oder innerhalb des Gehäuseinnenraums ausgebildet ist, sodass der darin angeordnete Ölsumpf abseits, d.h. insbesondere beabstandet, von allen zu schmierenden und/oder zu kühlenden Komponenten angeordnet ist.

According to one aspect, a drive housing for a motor vehicle drive unit with at least one electric drive machine and at least one output gear for torque transmission from a rotor shaft to road-side components of a drive train of the motor vehicle, in particular to drivable wheels, is disclosed. The drive housing has at least:

1. (a) an outer housing wall for delimiting a housing interior that is lubricating oil-tight, in particular except for the provided inlet and outlet lines, in which oil lubrication is provided for lubricating and/or cooling the transmission and/or the drive machine. In particular, an open part of a lubricating oil circuit is formed in the housing interior, which also provides an oil pump in or outside the housing. In the present case, an open part of the lubricating oil circuit is to be understood in particular as meaning the interior of the housing or a part thereof between one or more pointed oil outlets of a closed part of the lubricating oil circuit and an oil sump in the interior of the housing, with the lubricating oil from the oil sump or another delivery point in a further closed part of the Lubricating oil circuit can be fed to the oil pump; and or
2. (b) an inner housing wall which, in particular alone or in cooperation with a part of the outer housing wall, delimits an oil reservoir, which is designed in particular for an oil sump for oil lubrication and/or within the housing interior, so that the oil sump arranged therein is apart, ie in particular spaced apart, of all components to be lubricated and/or cooled.

A throttle recess is arranged on the inner housing wall, possibly in cooperation with a part of the outer housing wall, by means of which, in particular through the throttle recess and/or along the throttle recess, an oil mass flow of a component to be lubricated and/or cooled, in particular a gear ring a gear that can be supplied to the output gear.

This means that continuous lubrication can be achieved even without splash lubrication, which reduces the efficiency, of a rotating component to be lubricated/cooled, even if injection lubrication is switched off. Passive lubrication can therefore be implemented.

An internal housing wall is to be understood in particular as a wall within a housing interior, which can, for example, separate a part of the housing interior from another part of the housing interior. In particular, the inner wall of the housing is designed in such a way that it forms the oil reservoir, for example in the sense of a trough; then the inner housing wall extends in the vertical direction in the installation position, in particular only in part of the vertical extension, so that, for example, the oil reservoir could at least theoretically overflow.

According to one embodiment, the supply of lubricating oil from the oil reservoir to the component to be lubricated/cooled takes place passively through the throttle recess, in particular by means of gravity and/or a weight of lubricating oil that is accommodated in the oil reservoir. This means that lubrication in the low-load range can be achieved without energy consumption for pumping the lubricant, for example using an oil pump.

According to a further aspect, a method is disclosed for lubricating and cooling a motor vehicle drive unit in a drive housing, which can be designed according to an embodiment of the invention, by means of a lubricating oil circuit which is completely or partially open in the drive housing and which can be operated by means of an oil pump.

The method has at least the following method steps, which can be carried out in the specified order or in another professional order: (i) switching a continuous pumping operation of the oil pump during high-load operation of the drive unit, i.e. in particular when high-load operation of the drive unit has been detected, and / or (ii) switching intermittent pumping operation of the oil pump during standard operation of the drive unit, and/or (iii) switching off the oil pump during low load operation.

This means that sufficient lubrication and cooling of the electric drive machine and the output transmission can be achieved across all load conditions with optimized energy consumption.

The invention is based, among other things, on the idea that with a single lubricating oil circuit for the electric drive machine and the output gear or with a single oil pump for all lubricating oil circuits, neither a conventional replacement lubrication nor a conventional injection lubrication of the drive unit can be designed to be energetically optimal.

The invention is based, among other things, on the idea of collecting the lubricating oil in a reservoir and from there passively directing it to all essential lubrication points, in particular to the tooth meshes and possibly to a differential gear. Oil nozzles also enable the same areas to be actively cooled as needed.

The oil pump can be switched off during normal customer operation at low load or operated intermittently, i.e. switched off temporarily, depending on the required cooling capacity or amount of lubrication. This largely avoids friction losses caused by the oil in the electric machine.

When the oil pump is switched off, all essential lubrication points in the transmission are passively lubricated, especially the gearing and the differential. In contrast to classic splash lubrication, not all of the oil is in circulation, but rather the oil is collected in a reservoir and only the amount of oil necessary for lubrication is supplied to the wheel set via a throttle point. This concept also achieves a significant efficiency advantage in the transmission.

During high loads or dynamic driving, the oil pump can be switched on as needed for cooling or lubrication. Requesters of the active cooling and lubrication requirement by the oil pump can, for example, be the following component or operating states: a high oil temperature and/or a high component temperature in the electric motor or in the transmission and/or a high torque requirement and/or a wheel differential speed (generates cooling requirement in the differential).

Furthermore, the oil pump can be switched on briefly at predetermined intervals, in particular as needed, in order to oil peripheral lubrication points, for example the bearings and sealing rings of the electric machine.

According to one embodiment, the component to be lubricated and/or cooled on the one hand and, on the other hand, the outer housing wall and/or the inner housing wall, in particular due to their geometric design and/or rotation relative to one another, are coordinated with one another in such a way that the lubricating oil supplied through the throttle recess, in particular directly , is discharged. This minimizes any loss of efficiency caused by unnecessarily circulating lubricating oil.

According to one embodiment, the throttle recess has a dimension, in particular a diameter and/or a geometry, which enables a predetermined oil mass flow towards the component to be lubricated/cooled. This allows an application-specific oil mass flow required for pure lubrication in the low-load range to be set.

According to one embodiment, the drive housing has an adjusting means for adjusting a diameter and/or a geometry of the throttle recess, and thus in particular the predetermined oil mass flow. With such an active adjustment of the throttle recess, the oil mass flow can be adjusted with an unchanged effect of gravity and/or mass forces. In this way, energy-consuming operation of the oil pump of the lubricating oil circuit can be avoided in a wider range of operating cases; For example, if the cooling effect would still be sufficient in an increasing load case, but without the adjustment there would no longer be sufficient oil mass flow available for reliable lubrication of the gears, which now mesh more quickly, or if in operating cases with higher torques.

According to one embodiment, the throttle recess is arranged in the inner wall of the housing. This means that a lubrication point that is spaced from the outer wall of the housing can also be selected.

According to one embodiment, the throttle recess is arranged at a transition between the inner housing wall and the outer housing wall and/or at a lowest point of the oil reservoir, particularly in the installation position. This ensures that the oil flow through the throttle recess is optimized in terms of the weight forces acting.

• - einer Schmieröltemperatur, und/oder
• - einer Komponententemperatur innerhalb des Antriebsgehäuses, und/oder
• - einer Drehmomentanforderung an die Antriebseinheit, und/oder
• - einer Raddifferenzdrehzahl an der Achse, welche mittels der Antriebseinheit angetrieben wird.

According to one embodiment, a switch is made between the different types of pumping operation (ie continuous pumping operation or intermittent pumping operation or no pumping operation) depending on measurement and/or model values:

• - a lubricating oil temperature, and/or
• - a component temperature within the drive housing, and/or
• - a torque requirement for the drive unit, and/or
• - a wheel differential speed on the axle, which is driven by the drive unit.

According to one embodiment, the oil pump is switched on independently of the type of pump operation, in particular at predetermined intervals and/or as needed (i.e. depending on a stored lubrication plan and/or on measured or modeled values of at least one wetting influencing variable), for example for a few seconds each time. switched on to lubricate peripheral lubrication points, such as the bearings and sealing rings of the electric motor. This allows optimal lubrication of all components in the drive housing to be lubricated with reduced energy consumption.

According to one embodiment, when a criterion for switching to a stronger pumping operation is reached - in particular a criterion for switching from a shutdown to an intermittent pumping operation or from an intermittent pumping operation to a continuous pumping operation - a diameter and / or a geometry of the throttle recess is first adjusted, and Only later, at a time interval, in particular a predetermined one, is switched to the stronger pumping mode. The energy-consuming, more powerful pumping operation can thus be delayed while still providing sufficient lubrication.

• Fig. zeigt in einer schematischen Schnittansicht ein Antriebsgehäuse gemäß einer beispielhaften Ausführung der Erfindung, mittels dessen ein beispielhaftes Verfahren durchgeführt werden kann.

Further advantages and possible applications of the invention result from the following description in connection with the figure:

• Fig. shows a schematic sectional view of a drive housing according to an exemplary embodiment of the invention, by means of which an exemplary method can be carried out.

In the figure, exemplary oil mass flows in the drive housing are shown with double line arrows, with solid arrows symbolizing directly injected lubricating oil and dashed arrows symbolizing passively pumped lubricating oil. The directions of rotation of the individual gears 9, 24 and 26 are shown with triple line arrows. The pitch circles of the individual gears 9, 24 and 26 are symbolized by dashed lines.

The figure shows a drive housing 1 for a motor vehicle drive unit 2.

The motor vehicle drive unit 2 accommodated in the drive housing 1 has an electric drive machine 4, shown only by its rotor shaft 8, and an output gear 6, which - for transmitting torque from the rotor shaft 8 to a differential gear 10, shown only in outline - next to a rotor spur gear 9 the rotor shaft 8 has an intermediate gear 24 and a final drive gear 26. The rotor spur gear 9 meshes with the intermediate gear 24, which in turn meshes with the final drive gear 26.

The drive housing 1 has an outer housing wall 12 for the lubricating oil-tight delimitation of a housing interior 14, in which an oil lubrication 16 is formed for lubrication and cooling of the output gear 6 and the drive machine.

The drive housing has a lubricating oil circuit 40, which can be operated by means of an oil pump 42. In the housing interior 14, the lubricating oil circuit 40 is designed to be partially open; That means here: open oil lines from spray nozzles 28, 29 upstream and closed. Away from this open section in the housing interior 14, the lubricating oil circuit 40 is designed to be closed.

In addition, the drive housing 1 has an internal housing wall 18, which extends from the housing outer wall 12 into the housing interior 14, and is designed, in cooperation with a part of the housing outer wall 12, to form an oil reservoir 20 for an oil sump 22 of the oil lubrication 16 from the remaining housing interior 14 in such a way that the oil sump arranged therein is arranged away from all components of the output gear 6 to be lubricated and / or cooled (i.e. at a distance from the rotor spur gear 9, the intermediate gear 24 and the final drive gear 26).

A throttle recess 30 is arranged on the inner housing wall 18 - here in its lower area close to the outer housing wall 12 - through which an oil mass flow 32 can be supplied to the gear ring of the final drive gear 26. The supply of lubricating oil from the oil reservoir 20 to the final drive gear 26 through the throttle recess 30 takes place purely passively by means of gravity and/or a weight of the lubricating oil in the oil sump 22, which is accommodated in the oil reservoir 22.

This means that continuous lubrication can be achieved even without splash lubrication, which reduces the efficiency, of a rotating component to be lubricated/cooled, even if injection lubrication is switched off. Passive lubrication can therefore be implemented.

The final drive gear 26 on the one hand and the housing outer wall 12 on the other hand are coordinated with one another due to their coordinated radii (outer radius of the gear and inner radius of the housing wall) and due to their rotation relative to one another in such a way that the lubricating oil supplied through the throttle recess 30 is immediately removed, i.e. in the present case through the Rotation of the gear ring is promoted against the resistance of the housing wall.

So that an application-specific oil mass flow required for pure lubrication in the low-load range is available, the throttle recess has a dimension 34, here a diameter, which enables this predetermined oil mass flow. This means that any loss of efficiency due to unnecessarily circulated lubricating oil can be minimized to the amount acutely required for lubrication.

In order to be able to carry out an exemplary method for lubricating and cooling the motor vehicle drive unit 2 with this drive housing 1, the motor vehicle has a drive control with a control means S, which is set up to carry out the method.

In the method, depending on measurement and/or model values that are determined and processed by means of the control means S, between the different types of pumping operation, here between continuous pumping operation, intermittent pumping operation and switching off the oil pump (“no pumping operation”) ) switched. The values taken into account can be a lubricating oil temperature, a component temperature within the drive housing, a torque requirement for the drive unit, and/or a wheel differential speed on the axle that is driven by the drive unit.

According to these predetermined dependencies, the control means S switches as follows: (i) during high-load operation of the drive unit 2: switching on a continuous pumping operation of the oil pump 42. (ii) during a standard operation of the drive unit 2: switching on an intermittent pumping operation of the oil pump 42. (iii). a low-load operation of the drive unit 2: switching off the oil pump 42.

Regardless of the switched type of pump operation, the oil pump 42 is switched on at predetermined intervals for a few seconds as needed in order to lubricate peripheral lubrication points such as the bearings and sealing rings of the electric machine.

This allows optimal lubrication of all components in the drive housing to be lubricated with reduced energy consumption.

REFERENCE SYMBOL LIST

1

Drive housing

2

Motor vehicle drive unit

4

electric drive machine

6

Output gear

8th

Rotor shaft

10

Differential gear

12

Housing outer wall

14

Housing interior

16

Oil lubrication

18

Internal housing wall

20

Oil reservoir

22

Oil sump

24

intermediate wheel

26

Final Drive gear

28, 29

spray nozzles

30

Throttle recess

32

Oil mass flow

34

Dimension of the throttle recess, especially diameter

40

Lubricating oil circuit

42

Oil pump

S

Tax funds

Claims (11)

Drive housing (1) for a motor vehicle drive unit (2) with an electric drive machine (4) and an output gear (6). - an outer housing wall (12) for delimiting a housing interior (14), in which oil lubrication (16) is provided, - an internal housing wall (18) which delimits an oil reservoir (20), so that an oil sump (22) arranged therein is arranged away from the components to be lubricated and/or cooled, a throttle recess (30) being arranged on the internal housing wall (18). is, by means of which an oil mass flow (32) can be supplied to a component (26) of the output transmission (6). Drive housing according to Claim 1 , characterized in that the feed through the throttle recess (30) takes place passively. Drive housing according to one of the preceding claims, characterized in that the component (26) to be lubricated and/or cooled and the outer housing wall (12) and/or the inner housing wall (18) are coordinated with one another in such a way that the throttle recess (30) supplied lubricating oil is removed. Drive housing according to one of the preceding claims, characterized in that the throttle recess has a dimension (34) which enables a predetermined oil mass flow. Drive housing according to one of the preceding claims, characterized in that the drive housing (1) has an adjusting means for adjusting a diameter and/or a geometry of the throttle recess. Drive housing according to one of the preceding claims, characterized in that the throttle recess is arranged in the inner wall (18) of the housing. Drive housing according to one of the preceding claims, characterized in that the throttle recess is arranged at a transition between the inner housing wall (18) and the outer housing wall (12) and/or at a lowest point of the oil reservoir. Method for lubricating and cooling a motor vehicle drive unit (2) in a drive housing (1), which can be designed according to one of the preceding claims, by means of a lubricating oil circuit (40) which is completely or partially open in the drive housing and which is operated by means of an oil pump (42). is operable, comprising: - Switching continuous pumping operation of the oil pump during high-load operation of the drive unit, and/or - Switching an intermittent pumping operation of the oil pump during standard operation of the drive unit, and / or - Switching off the oil pump during low load operation. Procedure according to Claim 8 , characterized in that switching between the different types of pump operation depends on measurement and/or model values: - a lubricating oil temperature, and/or - a component temperature within the drive housing, and/or - a torque request to the drive unit, and / or - a wheel differential speed on the axle, which is driven by the drive unit. Procedure according to Claim 8 or 9 , characterized in that regardless of the switched type of pump operation, the oil pump is switched on in order to lubricate peripheral lubrication points. Procedure according to one of the Claims 8 until 10 , characterized in that when a criterion for switching to a stronger pumping operation is reached, a diameter and / or a geometry of the throttle recess is first adjusted, and only later with a time interval is the switch to the stronger pumping operation.

Images