Patent ID: 12244212

DETAILED DESCRIPTION

FIG.1shows a drive device for a vehicle axle of a two-track vehicle. The drive device has an electric machine which, when installed transversely, is arranged axially parallel to the flange shafts3guided to the vehicle wheels. A stator4with a rotor5interacting therewith is arranged in a stator housing2of the electric machine. The rotor shaft6is rotatably mounted in bearing openings on axially opposite housing walls8,9of the stator housing2. The rotor shaft6of the electric machine is connected in a rotationally fixed manner to a transmission input shaft17of a transmission19, for example via a spline. InFIG.1, the transmission19is realized as a two-stage spur gear that drives an axle differential20. InFIG.1, the axle differential20is positioned outside a transmission housing21for reasons of clarity. In fact, the axle differential20can be positioned within the gear housing21together with the two-stage spur gear.

InFIG.1, the stator4has a plurality of stator windings, of which only two stator windings21are roughly indicated inFIG.1. Each stator winding21has a winding head on both axial sides, which projects into a winding head space27. Each winding head space27is integrated into an electric machine hydraulic circuit E described later, with the help of which the respective winding head space27can be supplied with coolant in order to cool the winding heads of the stator4. In each of the winding head spaces27, a coolant/air mixture moves in a vortex flow around the rotor shaft5, which rotates at high speed.

As shown inFIG.1, the electric machine hydraulic circuit E has a coolant tank35, which is connected to a suction pump37via a suction line. A pressure line leads from the suction pump37to coolant supply lines41,43. By means of the supply line41, coolant is fed into a radially outer circumferential annular gap45. From there, the coolant is guided via radially outer stator channels47to a further annular gap49in the right winding head space27. The two annular gaps45,47are separated from the respective winding head space27via splash rings44. Each of the splash rings44has nozzles46distributed in the circumferential direction, via which coolant (i.e. oil) can be injected into the respective winding head space27.

By means of the supply line43, coolant is guided through the rotor shaft6and passed via a flow connection51into radially inner stator channels53into the right winding head space27. In addition, coolant is projected radially outwards towards the winding heads starting from the flow connection51and starting from the right mouth opening of the radially inner stator channels53.

The two winding head spaces27are separated from one another in a substantially coolant-tight manner in the interior of the stator housing via the rotor/stator arrangement. In order to provide a flow connection between the two winding head spaces27, there is a respective drain opening54on each of the two stator housing axial sides. These are positioned in the housing bottom of the stator housing2. The coolant collecting on the bottom side in the respective winding head space27can flow out into an underlying stator housing sump55via the two drain openings54. In the installed position, the stator housing sump55is positioned centrally, that is in vertical alignment with the rotor axis, at the lowest point below the stator housing2, so that the coolant can flow under gravity from the inside of the stator housing into the stator housing sump55.

InFIG.1, the stator housing sump55extends approximately over the entire length of the stator housing in the axial direction. In addition, a transmission-side suction point A1and a transmission-remote suction point A2are provided on each of the two axial sides in the stator housing sump55. At the transmission-side suction point A1, the coolant is extracted by a transmission return pump59. At the suction point A2remote from the transmission, the coolant is extracted by an electric machine return pump56.

The transmission return pump59is part of a transmission hydraulic circuit G of the coolant supply system. In the transmission hydraulic circuit G, the coolant tank35is connected to the suction pump37via the suction line. By means of the suction pump37, the coolant coming from the coolant tank25can be guided through a transmission supply line to a tooth engagement point Z of the transmission19in order to lubricate transmission components. From there, the coolant drips off and collects on the bottom of the transmission in a transmission sump65. In the transmission sump65, the coolant is guided back into the coolant tank35in a return line67using the transmission return pump59.

InFIG.1, the suction pump37, the transmission return pump59and the electric machine return pump56are components of a multiple pump (combination pump). With such a multiple pump, the individual pumps are driven by a common drive shaft. The common drive shaft is in turn connected to an electric motor that acts as a drive.

As already mentioned, inFIG.1the electric machine is installed transversely parallel to the vehicle axle. Therefore, the transmission-side suction point A1is positioned on the left side of the vehicle, while the transmission-remote suction point A2is positioned on the right side of the vehicle. When the vehicle curves to the left, the coolant in the stator housing sump55is displaced towards the right suction point A2due to centrifugal force. When the vehicle curves to the right, the coolant in the stator housing sump55is displaced towards the left suction point A1due to centrifugal force. Therefore, when cornering, the coolant can be reliably returned to the coolant tank35either via the left suction point A1or via the right suction point A2.

A core idea of the invention is that a flow connection68to the transmission sump65is formed on the side of the stator housing sump55close to the transmission. When cornering to the right, the coolant in the stator housing sump55is transferred via the flow connection68into the transmission sump65. In this case, with double functionality, at the transmission-side suction point A1, not only the coolant collected in the transmission sump65is sucked off in the direction of the coolant tank35, but the coolant is also transferred from the stator housing sump55. A separate stator housing suction point A3(as indicated inFIG.3) can therefore be dispensed with on the side of the stator housing sump55close to the transmission.

As can be seen fromFIG.1, all pumps37,56,59are positioned on the left axial side of the stator housing2in a space-saving manner. The suction point A2arranged on the stator housing axial side remote from the pump is connected to the electric machine return pump56via a return line69. The return line69is positioned axially parallel to the stator housing sump55according toFIG.2. The stator housing2can be realized as a cast part, on which both the stator housing sump5and the return line69are formed in one piece using the same material.

InFIG.2, the return line69is also offset upwards by a height offset relative to the stator housing sump55. In order to ensure an operationally reliable flow connection, the stator housing sump55and a mouth opening75of the return line69are connected via a suction nozzle77indicated by dashed lines. The suction nozzle77has a mouth opening79, which lies in a horizontal plane and is immersed in the coolant.

A second exemplary embodiment is shown inFIG.3, which essentially has the same structure and the same functionality as the exemplary embodiment shown inFIG.1. Therefore, reference is made to the previous description. In contrast toFIG.1, inFIG.3there is no flow connection68between the stator housing sump55and the transmission sump65. Instead, the left side of the stator housing sump55has its own suction point A3on its side close to the transmission. This is connected via a return line73to a second electric machine return pump71, which returns coolant from suction point A3into the coolant tank35.

As noted, the stator housing2can be realized as a cast part, on which both the stator housing sump5and the return line69are formed in one piece using the same material.FIG.4depicts such an embodiment as a variation of the embodiment shown inFIG.2.

LIST OF REFERENCE NUMERALS

2stator housing3flange shafts4stator5rotor6rotor shaft8,9housing walls17transmission input shaft19transmission21stator windings27winding head space35coolant tank37suction pump41,43coolant supply lines44coolant spray rings45annular gap46nozzles47radially outer stator channels49annular gap51flow connection53radially inner stator channels54drain openings55stator housing sump56electric machine return pump59transmission return pump65transmission sump67return line68flow connection69return line71second electric machine return pump73return line75mouth opening77suction nozzleA1left suction pointA2right suction pointA3additional suction pointG transmission hydraulic circuitE electric machine hydraulic circuitZ tooth meshing point