Electric drive for a vehicle
An electric drive for a vehicle comprises: an electric machine, a stator connected to a housing and comprising stator end-windings, a rotor rotatable relative to the stator, and a driveshaft connected to the rotor; a transmission to transmit a rotary movement from the driveshaft to a driveline; a sump containing fluid to cool and/or lubricate the electric machine and the transmission; a hydraulic arrangement comprising at least one bi-directional pump, a first suction line hydraulically connected with the pump, a stator path for cooling the stator, a second suction line connected with the pump, and a transmission path for cooling the transmission; a valve arrangement with multiple valves configured such that fluid is either supplied from the sump through the first suction line to the stator path, or through the second suction line to the transmission path.
1 . Electric drive for a vehicle, comprising:
a housing,
an electric machine with a stator connected to the housing and comprising stator end-windings, a rotor rotatable relative to the stator, and a driveshaft connected to the rotor in a rotationally fixed manner, wherein the driveshaft is supported in the housing so as to be rotatable about an axis of rotation,
a transmission for transmitting a rotary movement from the driveshaft to a driveline of the motor vehicle,
a sump with fluid for cooling and/or lubricating at least one of the electric machine and the transmission,
a hydraulic arrangement comprising at least one bi-directional pump, a first suction line arranged between the sump and the pump, a stator path arranged between the pump and the electric machine to supply fluid for cooling the stator, a second suction line arranged between the sump and the pump, and a transmission path arranged between the pump and the transmission to supply fluid for cooling the transmission, and
a valve arrangement with multiple valves configured such that, depending on the direction of rotation of the bi-directional pump fluid is either supplied from the sump through the first suction line to the stator path to cool the electric machine, or fluid is supplied from the sump through the second suction line to the transmission path to cool the transmission.
2 . The electric drive according to claim 1 , wherein the valve arrangement comprises a first check valve arranged in the first suction line, a second check valve arranged in the second suction line, a third check valve arranged in a first pressure line that is part of the transmission path, and a fourth check valve arranged in a second pressure line that is part of the stator path.
3 . The electric drive according to claim 1 , wherein the hydraulic arrangement comprises a first bi-directional pump and a second bi-directional pump that are hydraulically arranged in parallel between the sump at a suction side, and the electric machine and the transmission at a pressure side.
4 . The electric drive according to claim 3 ,
wherein the hydraulic arrangement is controllable such that at least one of:
in a low speed mode both the first bi-directional pump and the second bi-directional pump are driven so as to supply fluid from the sump to the stator path to cool the electric machine,
in a medium speed mode, one of the first and second bi-directional pump is driven so as to supply fluid from the sump to the stator path to cool the electric machine, and the other one of the first and second bi-directional pump is driven so as to supply fluid from the sump to the transmission path to cool the transmission, and
in a high speed mode both the first bi-directional pump and the second bi-directional pump are driven so as to supply fluid from the sump to the transmission path to cool the transmission.
5 . The electric drive according to claim 1 ,
wherein the sump is configured as a joint sump in which fluid of the electric machine and the transmission is contained, with only one sump line hydraulically connected thereto, and
wherein the first suction line and second suction line of both the first bi-directional pump and the second bi-directional pump are hydraulically connected with said joint sump through said sump line.
6 . The electric drive according to claim 3 ,
wherein the sump comprises a motor-side reservoir associated with the electric machine and a transmission-side reservoir associated with the transmission,
wherein the first suction lines of both the first bi-directional pump and the second bi-directional pump are hydraulically connected with the motor-side reservoir, and
wherein the second suction lines of both the first bi-directional pump and the second bi-directional pump are hydraulically connected with the transmission.
7 . The electric drive according to claim 6 ,
wherein a motor sump line is hydraulically connected with the first suction line of the first bi-directional pump and with the first suction line of the second bi-directional pump, and
wherein a transmission sump line is hydraulically connected with the second suction line of the first bi-directional pump and with the second suction line of the second bi-directional pump.
8 . The electric drive according to claim 6 ,
wherein the hydraulic arrangement is controllable such that:
in a low speed mode both the first bi-directional pump and the second bi-directional pump are driven so as to supply fluid from the motor-side reservoir to the stator path to cool the electric machine,
in a medium speed mode, the first bi-directional pump is driven so as to supply fluid from the transmission-side reservoir to the transmission path for cooling the transmission, and the second bi-directional pump is driven so as to supply fluid the motor-side reservoir to the stator path for cooling the electric machine, and
in a high speed mode both the first bi-directional pump and the second bi-directional pump are driven so as to supply fluid from the transmission-side reservoir to the transmission path for cooling the transmission.
9 . The electric drive according to claim 1 ,
wherein the hydraulic arrangement comprises only one bi-directional pump and
wherein the sump comprises a motor-side reservoir associated with the electric machine and a transmission-side reservoir associated with the transmission, and
wherein the first suction line of the bi-directional pump is hydraulically connected with the motor-side reservoir, and the second suction line of the bi-directional pump is hydraulically connected with the transmission-side reservoir.
10 . The electric drive according to claim 9 , wherein the hydraulic arrangement is controllable such that:
in a low speed mode the bi-directional pump is driven so as to supply fluid from the motor-side reservoir to the stator path for mainly cooling the electric machine, and
in a high speed mode the bi-directional pump is driven so as to supply fluid from the transmission-side reservoir to the transmission path for mainly cooling the transmission.
11 . The electric drive according to claim 4 ,
wherein, in the low speed mode, the transmission is supplied with fluid passively from the sump, and
wherein a fluid level in the transmission-side reservoir can be higher in the low speed mode than in the high speed mode.
12 . The electric drive according to claim 1 , wherein the hydraulic stator path comprises a branched-off jacket line to a jacket cooling structure of the electric machine arranged in the housing.
13 . The electric drive according to claim 4 , wherein the hydraulic transmission path comprises a branched-off shaft line to an inner longitudinal bore of the driveshaft.
14 . The electric drive according to claim 13 , wherein, in the high speed mode, the electric machine is supplied with fluid via radial bores of the driveshaft connecting the inner longitudinal bore with at least one of the rotor and the stator of the electric machine.
15 . The electric drive according to claim 1 , wherein the housing includes an intermediate wall which separates an inner space into a motor-side chamber and a transmission-side chamber, wherein a through-opening is arranged in the intermediate wall through which fluid can flow from the transmission-side reservoir to the motor-side reservoir.
16 . The electric drive according to claim 1 , wherein a heat exchanger is arranged in the stator path.