WO2012159787A1

WO2012159787A1 - Electric traction drive for a vehicle

Info

Publication number: WO2012159787A1
Application number: PCT/EP2012/054862
Authority: WO
Inventors: Stephan Scharr; Timo Wehlen; Michael Donaubauer
Original assignee: Zf Friedrichshafen Ag
Priority date: 2011-05-26
Filing date: 2012-03-20
Publication date: 2012-11-29
Also published as: DE102011076527A1

Abstract

Proposed is an electric traction drive for a vehicle, having an electric machine (3) which is coupled via an intermediate transmission (4) to a drive output, wherein a drive housing (2) is provided which accommodates the electric machine (3) and the intermediate transmission (4) and in which there is provided a common, passively operated oil circuit for lubrication and/or cooling.

Description

Electric drive for a vehicle

The present invention relates to an electric traction drive for a vehicle according to the closer defined in the preamble of claim 1. Art.

From the vehicle technology, an electric traction drive for a vehicle is known. Usually, the existing coolant and lubricant circuits of an electric drive unit are operated by means of associated pumps in order to ensure sufficient cooling and lubrication of the electrical machine and the transmission components. It has been shown that in the known traction drive due to the required pumps and the associated power loss, the efficiency of the traction drive is reduced. In addition, due to the necessary pumps and the necessary housing designs high production costs.

The present invention is based on the object to propose an electric traction drive of the type described above, which has the lowest possible manufacturing costs and the highest possible efficiency.

This object is achieved by the features of claim 1, wherein advantageous embodiments of the dependent claims and the drawings.

Thus, an electric traction drive for any vehicle is proposed, wherein an intermediate gear is provided to transmit the drive power of the electric machine to the output. According to the invention it is provided that the electric machine and the intermediate gear are taken with the output in a common drive housing, wherein for cooling and / or lubricating a common coolant and / or lubricant circuit or oil circuit is provided, which is operated passively without in Advantageously, a pump is required. To realize a passively operated oil circuit while an axial oil passage is realized by the entire drive housing between the two housing side covers, for example, the proposed waves of the electric machine and the intermediate gear are each designed as hollow shafts or the like, so that the oil in the simplest way axially the coaxially successively arranged hollow shafts is guided.

In this way, a traction drive can be realized as a final drive or as a single-wheel drive, which ensures sufficient coverage of the cooling and lubricating demand on all relevant areas, such as the bearings, the teeth or the like in the drive housing. In addition, the heat sources of the electric machine can be selectively cooled by the targeted control or management of the coolant and lubricant or the oil, so that a higher performance of the drive is realized due to the larger possible power loss.

For example, in a trained as a final drive drive, the output side spur gear of the intermediate gear, which is coupled, for example, with an axle differential, are used for Olförderung from the bottom of the drive housing or the like, so that the oil is supplied to the inlet region of the axial hollow shaft bushing. This reduces the oil level in the sump of the drive housing, thereby minimizing any possible churning losses.

In order to optimally supply the oil conveyed by means of the spur gear in the upper region of the drive housing to the inlet region of the axial oil passage, can be provided according to a next embodiment of the invention that, for example, a suitable collecting device is provided in the drive housing such that the oil delivered preferably on Side wall portion of the drive housing can be collected or collected. The collected oil can then be fed in the simplest way a reservoir for the entry area of the oil passage. As constructive embodiments of the collecting device can be introduced, for example, in the housing side cover area Bulges, recesses or the like may be provided. It is also conceivable that separate components, such as sheets or the like are provided on the wall portion. A collecting device integrated in the housing cover would be particularly cost-effective.

In order to improve the oil flow through the formed as an oil passage hollow shafts, correspondingly adapted cross-sectional shapes of the hollow shafts can be provided. For example, the implementation can be performed as a thread provided at least in sections, whereby the oil flow is accelerated correspondingly with rotating hollow shafts. But there are also other structural forms and components possible that affect the flow of oil accordingly positive.

After the cooling and lubrication of the components of the electric machine provided in this area, the oil emerging at the exit region of the oil feedthrough can be returned to the sump via corresponding guide elements in the drive housing so that the coolant and lubricant circuit is closed.

The proposed electric traction drive can be used for any drive systems, such as axle drives, single-wheel drives or for additions to hybrid systems, such as axle hybrid drives or the like.

Hereinafter, the present invention will be further explained with reference to the drawings. Show it:

Figure 1 is a schematic, sectional view of a possible embodiment of a traction drive according to the invention;

Figure 2 is a schematic plan view of the inside of a first housing side cover of the drive housing of the traction drive according to Figure 1; Figure 3 is a schematic, partial sectional view of a first embodiment of an axial oil passage formed as a hollow shaft intermediate shaft and the rotor shaft of the traction drive;

Figure 4 is a schematic, partial sectional view of a second embodiment of the axial oil passage; and

Figure 5 is a schematic, partial sectional view of a third embodiment of the axial oil passage.

In the figures, an electric traction drive 1 is exemplified as a final drive for a vehicle. The traction drive 1 comprises a drive housing 2, in which an electric machine 3 and an intermediate gear 4 is provided, which is coupled to the output shaft designed as an axle differential 5 for driving the drive axles of the vehicle.

The electric machine 3 comprises a stator 6, which surrounds a rotor 7. The rotor 7 is rotatably supported by two bearings 8, 9 with a rotor shaft 10 in the drive housing 2. The intermediate gear 4 comprises a planetary stage 1 1 and a spur gear 12, wherein the sun gear 13 of the planetary stage 1 1 is rotatably connected to the rotor shaft 10 of the electric machine 3. The ring gear 14 is fixed to the housing, wherein the planet 15 is connected to an intermediate shaft 16 of the intermediate gear 4 and the spur gear 12. The intermediate shaft 16 is formed as a hollow shaft. The output-side spur gear 17 of the spur gear 12 is coupled to the axle differential 5 and promotes oil from a sump 18 in the upper region of the drive housing. 2

In the traction drive 1 according to the invention, it is provided that a common, passively operated cooling circuit for lubricating and / or cooling is provided for the electric machine 3, for the planetary stage 1 1 and for the spur gear 12 and for the axle differential 5 in the common drive housing 2. In this way, an improved cooling and lubricating concept for the traction drive 1 according to the invention is realized. The common drive housing 2 is laterally sealed with a first housing side cover 19 and a second, opposite housing side cover 20, wherein a common sump 18 for the coolant and lubricant circuit is present. The oil delivered from the sump 18 via the output-side spur gear 17 is collected via a collection device 21 provided as a bulge in the first housing side cover 19 and supplied to a reservoir 22, which is likewise provided as a bulge in the first housing side cover 19. By splashing the spur gear 17 in the sump 18 is additionally distributed in the drive housing 2, an oil-air mixture, which ensures adequate lubrication of all moving parts. The internal oil production by the spur gear 17 also reduces the gear oil sump level during operation and thereby reduces the churning losses of the spur gear 17th

In Figure 1, the collector 21 is only schematically indicated by a dashed line, as this bulge protrudes in this perspective from the plane of the drawing. From Figure 2, the concrete design of the intended as a bulge in the housing side cover 19 collecting device 21 is clear, which is in communication with the well 22 also designed as a bulge reservoir. The bulges are preferably directed outwards, so that they protrude in Figure 2 in the plane or bulge.

In order to use the collected in the reservoir 22 oil for cooling and lubricating the provided in the drive housing 2 components, an axial oil passage 23 is provided, the oil from the reservoir 22 through the passage 23 in the second housing cover 20 associated Area of the drive housing 2 leads. The oil passage 23 is essentially formed by the intermediate shaft 16 designed as a hollow shaft and the adjoining rotor shaft 10. The fact that the oil is passed through the formed as a hollow shaft intermediate shaft 16 and rotor shaft 10, in addition, a targeted cooling of the rotor shaft 10 and thus the rotor 7 of the electric machine 3 can be realized so that compared to a pure external cooling, the performance of the electric machine 3 can be increased. In order to ensure the transfer of the oil from the reservoir 22 into the passage 23, an example, sleeve-shaped oil transfer 24 is provided. Between the mutually facing ends of the intermediate shaft 16 and the rotor shaft 10, a further oil transfer 25 is provided. Thus, the oil from the reservoir 22 to the second housing side cover 20 associated bearing 9 of the electric machine 3 can be performed. For the return of the oil in the sump 18 corresponding guide and guide elements 29 z. B. as sheets or the like on the housing side cover 20 and provided on the rotor shaft 10 so that the oil along the arrows is returned via an only partially indicated return passage on the electric machine 3 over, in Figure 1, the bottom side of the drive housing 2 with the integrated return channel for the sake of simplicity is only partially indicated.

In the region of the planetary stage 1 1 and the bearing 8 of the electric machine 3 assigned to the intermediate gear, the bushing 23 has one or more radial bores 26, 27, so that the oil can pass from the bushing 23 to the components to be lubricated and cooled, in FIG it is distributed by the forces acting on the rotating rotor shaft 10 centrifugal forces.

In the figures 3 to 5 different versions are shown quasi as a single-part view of the provided in the drive housing 2 oil passage 23 enlarged. As already described, the bushing 23 consists of the hollow shaft section of the intermediate shaft 16 and the hollow shaft section of the rotor shaft 10 of the electric machine 3.

FIG. 3 shows a first embodiment of the bushing 23 in which, as transfer 25 between the intermediate shaft 16 and the rotor shaft 10, an at least sectionally conically shaped sleeve is provided, as it were, as a funnel. Due to the widened cross-section in the area of the rotor shaft 10, the lead-through 23 in the area of the rotor shaft 10 is provided with a larger bore diameter than in the intermediate shaft 16. As a result, the oil flow is accelerated starting from the intermediate shaft 16 in the direction of the rotor shaft 10. FIG. 4 shows a second embodiment, in which, unlike the first embodiment according to FIG. 3, the transfer 25 is approximately cylindrical. In order to increase the flow rate of the oil in the second embodiment, a threaded sleeve 28 is inserted into the passage 23. The threaded sleeve 28 has an internal thread along which the oil is guided. Due to the selected thread pitch results in a rotation of the rotor shaft 10 quasi a conveyor spiral, so that the oil is conveyed in the drawing plane to the right.

According to Figure 5, a third embodiment of the bushing 23 is shown, in which, in contrast to the second embodiment shown in Figure 4, only a predetermined portion of the bushing 23 is provided in the rotor shaft 10 with a threaded sleeve 28, wherein in the further course of the implementation as a bore without Thread is provided.

REFERENCE CHARACTERS

traction drive

drive housing

electric machine

intermediate gear

axle differential

stator

rotor

Bearing of the electric machine

rotor shaft

planetary stage

spur gear

sun

ring gear

planet

intermediate shaft

output-side spur gear

swamp

first housing side cover

second housing cover

collecting device

reservoir

Oil-carrying

Oil-handover

radial bore

threaded sleeve

Guiding and guiding elements

Claims

claims

1 . Electric drive for a vehicle, comprising an electric machine (3) which is coupled to an output via an intermediate gear (4), wherein a drive housing (2) receiving the electric machine (3) and the intermediate gear (4) is provided a common, passively operated oil circuit is provided for lubricating and / or cooling, characterized in that an intermediate shaft (16) formed as a hollow shaft coaxial with a rotor shaft designed as a hollow shaft (10) of the electric machine (3) are arranged one behind the other such that the two hollow shafts form an axial oil passage (23) in the drive housing (2) from a first housing side cover (19) to a second, opposite housing side cover (20).

2. Electric traction drive according to claim 1, characterized in that the intermediate gear (4) one of the rotor shaft (10) associated planetary stage (1 1) and one of the intermediate shaft (16) associated spur gear (12), wherein a driven side spur gear (17) the spur gear (12) with an axle differential (5) is coupled as an output and oil from a sump (18) of the drive housing (2) to a first housing side cover (19) facing the inlet region of the passage (23) promotes.

3. Electric traction drive according to claim 2, characterized in that the first housing side cover (19) as a reservoir (22) has a bulge, which is supplied via a collecting device (21) with the driven side spur gear (12) funded oil.

4. Electric traction drive according to claim 3, characterized in that the collecting device (21) is provided as a sheet or as an elongated bulge in the first housing side cover (19).

5. Electric traction drive according to one of the preceding claims, characterized in that the axial passage (23) each have an oil transfer (24, 25) between the reservoir (22) of the first transmission side cover (19) and the intermediate shaft (16) and between the intermediate shaft (16) and the rotor shaft (10).

6. Electric drive according to claim 5, characterized in that the transfer (24, 25) is formed as a sleeve at least partially conical or cylindrical.

7. Electric traction drive according to one of the preceding claims, characterized in that the passage (23) is formed as a bore with an at least partially extending in the axial direction of thread.

8. Electric traction drive according to one of the preceding claims, characterized in that the passage (23) is formed as a bore with an at least partially introduced threaded sleeve (28).

9. Electric traction drive according to one of the preceding claims, characterized in that the passage (23) has at least one radial bore (26, 27) for oil supply.

10. Electric traction drive according to claim 9, characterized in that a radial bore (26) in the region of the planetary stage (1 1) of the intermediate gear (4) and a further radial bore (27) in the region of the intermediate gear (4) facing bearing (8). the rotor shaft (10) are provided.

1 1. Electric traction drive according to one of the preceding claims, characterized in that the second housing side cover (20) facing the end of the passage (23) to the intermediate gear (4) facing away from the bearing (9) of the rotor shaft (10) is assigned to the oil supply.

12. Electric traction drive according to one of the preceding claims, characterized in that on the inside of the second housing side cover (20) and / or the rotor shaft (10) guide and guide elements (29) for oil return in the sump (18) of the drive housing (2) are provided.