Coolant supply system for electrically operated axles

Abstract

The invention relates to a coolant supply system for a power unit of an electrically operated axle of a two-track vehicle, the power unit having an electric motor, the coolant supply system having an electric motor hydraulic circuit (E), in which a coolant tank (35), the interior space of a cylindrical stator housing (2) and a stator housing sump (55) are incorporated, in which coolant flowing out of the stator housing (2) is collected, from which the coolant can be returned to the coolant tank (35) by means of at least one return pump (56, 59, 71). According to the invention, the stator housing sump (55) has a suction point (A1, A2, A3) on its two axially opposite axial sides, at which the coolant can be sucked out by means of the return pump (56, 59, 71).

Description

Technical Field

[0001] The invention relates to a coolant supply system for a power device of an electrically operated axle of a two-track vehicle, the power device having an electric motor, wherein the coolant supply system has an electric motor hydraulic circuit, in which the inner space of a cylindrical stator housing and a stator housing sump are incorporated, in which coolant flowing out of the stator housing is collected, and the coolant is returned from the stator housing sump to a coolant storage tank by means of at least one return pump. Background Art

[0002] In electrically operated two-track vehicles, the electrically driven axle can have an electric motor, for example. The electric motor can be arranged parallel to the axis of the flanged shaft leading to the wheels. In this case, the electric motor can drive the axle differential via a single-stage or double-stage spur gear transmission stage and further drive the flanged shaft of the axle leading to the wheels.

[0003] Such an electric machine can be implemented as a wet-running electric machine in which the stator, in particular the winding heads of the stator winding, are actively cooled. For such active stator cooling, a coolant supply system is provided which has a motor hydraulic circuit, in which a coolant tank, the interior of a cylindrical stator housing of the electric machine and a stator housing sump extending in the axial direction along the stator housing are incorporated. Coolant flowing out of the stator housing can be collected in the stator housing sump and can be returned from there to the coolant tank by means of at least one motor return pump.

[0004] In the prior art, the stator housing sump extends centrally below the stator housing in the axial direction. Viewed in the axial direction, the stator housing sump also has a suction point approximately in the middle, at which the collected coolant is sucked out by the motor return pump in the direction of the coolant tank. Depending on the driving operating state, for example, when accelerating, turning, driving uphill or downhill, the coolant collected in the stator housing sump may be moved away from the sump suction point due to centrifugal force. In this case, the reliable return of the coolant from the stator housing sump in the direction of the coolant tank is adversely affected.

[0005] An oil pan with a collecting space divided into two parts is known from DE 10 2019 114 476 A1. An oil pan for an electric motor is known from DE 2 139 740 A. A transmission oil chamber is known from DE 10 2008 040691 A1. Summary of the invention

[0006] The object of the present invention is to provide a coolant supply system for a drive unit of an electrically operated axle of a two-track vehicle, in which the coolant can be circulated in an operationally reliable manner in different driving operating states.

[0007] This object is achieved by the following features.

[0008] The present invention proposes a coolant supply system for a power device of an electrically operated axle of a two-track vehicle. The power device has a wet-operated motor. The coolant supply system includes a motor hydraulic circuit. The motor hydraulic circuit includes a coolant tank, an inner space of a cylindrical stator housing of the motor, and a stator housing sump extending in an axial direction along the cylindrical stator housing. The coolant flowing out of the stator housing is collected in the stator housing sump. From here, the coolant is returned to the coolant tank by means of at least one motor return pump. According to the present invention, the stator housing sump has a suction portion on each of its axially opposite axial sides, at which the collected coolant can be sucked out by the return pump, and an outflow opening is constructed on the bottom of the stator housing at each axial side of the stator housing, through which the coolant is led from the corresponding winding head space to the stator housing sump. Compared to the prior art, the two suction points ensure an operationally reliable suction of coolant in the direction of the coolant tank in a wide variety of driving operating states, whereby a reliable circulation of the coolant in the hydraulic circuit of the motor is possible.

[0009] In a technical implementation, the motor can be installed in a transverse manner parallel to the axle axis. In this case, one suction point of the stator housing sump is located on the right side of the vehicle, and the other suction point of the stator housing sump is located on the left side of the vehicle. When the vehicle turns left, the coolant in the stator housing sump moves to the right suction point due to centrifugal force. In contrast, when the vehicle turns right, the coolant in the stator housing sump moves to the left suction point due to centrifugal force. Therefore, in particular when turning, the coolant can be reliably guided back to the coolant tank from at least one of the two suction points of the stator housing sump.

[0010] In a first embodiment variant, the right suction point and the left suction point are arranged directly in the stator housing sump. An independent motor return pump can be assigned to each of the two suction points.

[0011] In the axle, the electric machine can drive the axle differential via a single-stage or double-stage spur gear transmission stage and from there further drive the flange shaft of the axle leading to the wheels. In this case, it is preferred that the coolant supply system additionally has a transmission hydraulic circuit that is separated as much as possible from the motor hydraulic circuit. The transmission hydraulic circuit can include a coolant tank, a transmission interior, and a transmission sump formed at the bottom of the transmission. In the transmission sump, the coolant flowing out of the transmission components is collected at the transmission suction point and from there is returned to the coolant tank by means of a transmission return pump. The transmission can be flange-connected directly to the axial side of the stator housing of the electric machine, so that the stator housing extends axially together with the transmission housing.

[0012] For the above-mentioned transmission mechanism device, the following embodiment variant can be realized: Therefore, a flow connection can be provided for the axial side of the stator housing close to the transmission mechanism, and the flow connection connects the stator housing sump with the transmission mechanism sump in terms of flow technology. For example, the coolant collected on the side of the stator housing sump close to the transmission mechanism due to cornering is guided to the transmission mechanism sump through the flow connection. In this case, the suction part on the transmission mechanism side can not only return the coolant collected in the transmission mechanism sump to the coolant tank in a dual-function manner, but also additionally return the coolant transferred from the stator housing sump to the coolant tank. Therefore, it is possible to eliminate the need to set a separate stator housing suction part on the side of the stator housing sump close to the transmission mechanism.

[0013] Alternatively, there is no flow connection between the stator housing sump and the transmission mechanism sump, and a separate stator housing suction point is provided on the side of the stator housing sump close to the transmission mechanism. A motor return pump is assigned to the stator housing suction point, which returns the coolant from the stator housing suction point in the direction of the coolant tank.

[0014] In a variant embodiment that is advantageous for the structural space, at least one motor return pump - in particular, it can be arranged together with the transmission return pump and / or the transmission - on the same axial side of the stator housing. Here, the stator housing sump can extend in the axial direction to the corresponding axial side of the stator housing. The stator housing can be realized as a casting, and the stator housing sump is formed on the stator housing with the same material and in one piece. The suction area arranged on the axial side of the stator housing away from the pump can be connected to the motor return pump via an additional return line. In a variant embodiment that is advantageous for the structural space, the return line is parallel to the axis of the stator housing sump. In addition, the return line can preferably be formed on the stator housing with the same material and in one piece together with the stator housing sump. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following is an explanation of the embodiments of the present invention with reference to the accompanying drawings.

[0016] Figure 1 An electric machine equipped with a coolant supply system is shown in a simplified schematic cross-sectional view;

[0017] Figure 2 One of the two suction locations in the stator housing sump is shown in detail; and

[0018] Figure 3 Corresponding to Figure 1 The figure shows a second embodiment of the present invention. DETAILED DESCRIPTION

[0019] exist Figure 1 , a power unit for an axle of a two-track vehicle is shown. The power unit has an electric motor which is arranged in a transversely mounted manner parallel to the axis of a flange shaft 3 leading to the wheel. A stator 4 and a rotor 5 interacting with the stator are arranged in the stator housing 2 of the electric motor. The rotor shaft 6 is rotatably supported in a bearing opening at axially opposite housing walls 8, 9 of the stator housing 2. The rotor shaft 6 of the electric motor is connected to a transmission input shaft 17 of a transmission 19 in a rotationally fixed manner, for example, by a key connection. Figure 1 In the embodiment, the transmission mechanism 19 is realized as a two-stage spur gear transmission mechanism, which is transmitted to the axle differential 20. Figure 1 In the figure, for the sake of clarity, the axle differential 20 is positioned outside the transmission housing 22. In fact, the axle differential 20 can be positioned inside the transmission housing 22 together with the two-stage spur gear transmission.

[0020] exist Figure 1 In the embodiment, the stator 4 has a plurality of stator windings. Figure 1 Only two of the stator windings 21 are roughly shown in the figure. Each stator winding 21 has winding heads on both sides of the axial direction, and the winding heads extend into the winding head space 27. Each winding head space 27 is incorporated into the motor hydraulic circuit E described later, with the help of which the corresponding winding head space 27 can be loaded with coolant to cool the winding heads of the stator 4. In each winding head space 27, the coolant / air mixture moves in the form of a vortex around the rotor shaft 6 rotating at high speed.

[0021] Also like Figure 1As shown, the motor hydraulic circuit E has a coolant tank 35, which is connected to a suction pump 37 via a suction line. The pressure line leads from the suction pump 37 to the coolant supply lines 41, 43. The coolant is provided to the annular gap 45 surrounding radially on the outside by means of the supply line 41. From there, the coolant is guided to another annular gap 49 in the right winding head space 27 through a radially outer stator channel 47. The two annular gaps 45, 47 are separated from the corresponding winding head space 27 by a splash ring 44. Each splash ring 44 has nozzles 46 distributed in the circumferential direction, through which the coolant (ie, oil) can be splashed into the corresponding winding head space 27.

[0022] The coolant is guided by means of the supply line 43 through the rotor shaft 6 and through the flow connection 51 into the radially inner stator channel 53 until it is guided into the right-hand winding head space 27. Furthermore, the coolant is ejected radially outwards in the direction of the winding head starting from the flow connection 51 and from the right-hand junction opening of the radially inner stator channel 53.

[0023] The two winding head spaces 27 are separated from each other in the interior space of the stator housing by the rotor / stator assembly in a substantially coolant-tight manner. In order to provide a flow connection between the two winding head spaces 27, outflow openings 54 are provided respectively on both axial sides of the stator housing. These outflow openings are positioned in the housing bottom of the stator housing 2. Through the two outflow openings 54, the coolant collected at the bottom in the corresponding winding head space 27 can flow out into the stator housing sump 55 located below. In the installed position, the stator housing sump 55 is located in a central position, that is, it is positioned at the lowest point below the stator housing 2 in vertical alignment with the rotor axis, so that the coolant can flow out from the inside of the stator housing into the stator housing sump 55 under the action of gravity.

[0024] exist Figure 1 In the embodiment, the stator housing sump 55 extends approximately over the entire stator housing length in the axial direction. In addition, at each of the two axial sides, a suction portion A1 on the transmission side and a suction portion A2 away from the transmission are respectively provided in the stator housing sump 55. The coolant is sucked out by the transmission return pump 59 at the suction portion A1 on the transmission side. The coolant is sucked out by the motor return pump 56 at the suction portion A2 away from the transmission.

[0025] The transmission return pump 59 is a component of the transmission hydraulic circuit G of the coolant supply system. In the transmission hydraulic circuit G, the coolant tank 35 is connected to the suction pump 37 via a suction line. With the help of the suction pump 37, coolant from the coolant tank 35 can be guided into the transmission supply inlet until it is guided to the tooth meshing point Z of the transmission 19 in order to lubricate the transmission components. The coolant drips from the tooth meshing point and is collected in the transmission sump 65 at the bottom of the transmission. In the transmission sump 65, the coolant is guided back to the coolant tank 35 in the return line 67 by means of the transmission return pump 59.

[0026] exist Figure 1 In the embodiment, the suction pump 37, the transmission mechanism return pump 59 and the motor return pump 56 are components of a multi-pump (combination pump). For this multi-pump, the individual pumps are driven by a common drive shaft. The common drive shaft is in turn connected to the motor drive used as a power device.

[0027] As mentioned above, in Figure 1 In the embodiment, the motor is installed in a transverse manner parallel to the axle axis. Therefore, the suction portion A1 on the transmission side is located on the left side of the vehicle, and the suction portion A2 away from the transmission is located on the right side of the vehicle. When the vehicle turns left, the coolant in the stator housing sump 55 moves toward the right suction portion A2 due to centrifugal force. In contrast, when the vehicle turns right, the coolant in the stator housing sump 55 moves toward the left suction portion A1 due to centrifugal force. Therefore, when turning, the coolant can be reliably introduced back into the coolant tank 35 through the left suction portion A1 or through the right suction portion A2.

[0028] The core of the present invention is that a flow connection 68 leading to the transmission mechanism sump 65 is constructed on the side of the stator housing sump 55 close to the transmission mechanism. Therefore, when turning right, the coolant in the stator housing sump 55 is transferred to the transmission mechanism sump 65 through the flow connection 68. In this case, at the suction portion A1 on the transmission mechanism side, not only the coolant collected in the transmission mechanism sump 65 is sucked out in the direction of the coolant storage tank 35, but also the coolant transferred from the stator housing sump 55 is sucked out in a dual-function manner. Therefore, a separate stator housing suction portion A3 (such as 200A) can be eliminated on the side of the stator housing sump 55 close to the transmission mechanism. Figure 3 shown).

[0029] In addition, Figure 1 As shown, all pumps 37, 56, 59 are advantageously positioned on the left axial side of the stator housing 2 in terms of installation space. The suction point A2 arranged on the axial side of the stator housing facing away from the pump is connected to the motor return pump 56 via a return line 69. Figure 2 The return line 69 is parallel to the axis of the stator housing sump 55. The stator housing 2 can be realized as a casting, and the stator housing sump 55 and the return line 69 are made of the same material and are formed in one piece on the stator housing.

[0030] In addition, Figure 2 In the embodiment of the present invention, the return line 69 is offset upwards by a height offset relative to the stator housing sump 55. In order to ensure an operationally reliable flow connection, the stator housing sump 55 and the junction opening 75 of the return line 69 are connected by a suction connection 77 indicated by a dashed line. The suction connection 77 has a junction opening 79 which is located in a horizontal plane and is immersed in the coolant.

[0031] exist Figure 3 A second embodiment is shown in FIG. 1 , which has essentially the same Figure 1 The same structure and the same functions as the embodiment shown. Therefore, reference is made to the previous description. Figure 1 ,exist Figure 3 The flow connection 68 between the stator housing sump 55 and the transmission sump 65 is eliminated. Instead, the left side of the stator housing sump 55 has a separate suction point A3 on its side close to the transmission. The suction point is connected to the second motor return pump 71 through a return line 73, which returns the coolant from the suction point A3 to the coolant storage tank 35.

[0032] List of reference numerals:

[0033] 2 Stator housing

[0034] 3 Flange shaft

[0035] 4 Stator

[0036] 5 Rotor

[0037] 6 Rotor shaft

[0038] 8, 9 Shell wall

[0039] 17 Transmission input shaft

[0040] 19 Transmission mechanism

[0041] 21 Stator winding

[0042] 27 Winding head space

[0043] 35 Coolant tank

[0044] 37 Suction pump

[0045] 41, 43 Coolant supply lines

[0046] 44 Coolant Splash Ring

[0047] 45 Annular gap

[0048] 46 Nozzle

[0049] 47 Radially outer stator channel

[0050] 49 Annular gap

[0051] 51 Flow connection

[0052] 53 Radially inner stator channel

[0053] 54 Outflow opening

[0054] 55 Stator housing sump

[0055] 56 Motor return pump

[0056] 59 Transmission return pump

[0057] 65 Transmission mechanism sump

[0058] 67 Return pipeline

[0059] 68 Flow connection

[0060] 69 Return pipeline

[0061] 71 Motor second return pump

[0062] 73 Return pipeline

[0063] 75 Confluence opening

[0064] 77 Suction pipe

[0065] A1 Left suction area

[0066] A2 Right suction site

[0067] A3 Other suction sites

[0068] G Transmission hydraulic circuit

[0069] E Motor hydraulic circuit

[0070] Z tooth meshing area.

Claims

1. A coolant supply system for a power unit of an electrically operated axle of a two-track vehicle, the power unit having an electric motor, wherein: The coolant supply system comprises a motor hydraulic circuit (E), in which the inner space of a cylindrical stator housing (2) and a stator housing sump (55) are incorporated, in which coolant flowing out of the stator housing (2) is collected, and the coolant is returned from the stator housing sump to a coolant storage tank (35) by means of at least one return pump (56, 59, 71), characterized in that the stator housing sump (55) has suction points (A1, A2, A3) on its two axially opposite axial sides, at which the coolant is sucked out by means of the return pump (56, 59, 71), and at each axial side of the stator housing, an outflow opening (54) is constructed on the bottom of the stator housing, through which the coolant is led from the corresponding winding head space (27) to the stator housing sump (55).

2. The coolant supply system according to claim 1, characterized in that: The motor is installed in a transverse manner so as to be parallel to the axle axis, the first suction position (A1) of the stator housing sump (55) is located on the left side of the vehicle, and the second suction position (A2) of the stator housing sump (55) is located on the right side of the vehicle. When the vehicle turns left, the coolant in the stator housing sump (55) moves to the right suction position (A2) due to centrifugal force. When the vehicle turns right, the coolant in the stator housing sump (55) moves to the left suction position (A1) due to centrifugal force, so that the coolant can be reliably guided back to the coolant storage tank (35) from the first suction position (A1) or from the second suction position (A2) when turning.

3. The coolant supply system according to claim 1 or 2, characterized in that: In the power device, the motor drives the flange shaft (3) leading to the wheel through the transmission mechanism (19), and the coolant supply system has a transmission mechanism hydraulic circuit (G), in which a transmission mechanism space and a transmission mechanism collecting tank (65) constructed at the bottom of the transmission mechanism are included. The coolant flowing out of the transmission mechanism components is collected in the transmission mechanism collecting tank at a suction point (A1) on the transmission mechanism side. The coolant is returned from the suction point to the coolant storage tank (35) through a transmission mechanism return pump (59). The transmission mechanism (19) is arranged on the axial side of the stator housing.

4. The coolant supply system according to claim 3, characterized in that: A flow connection (68) is constructed between the stator housing sump (55) and the transmission mechanism sump (65). The coolant collected in the stator housing sump (55) is transferred to the transmission mechanism sump (65) at the flow connection (68) due to turning, so that the suction portion (A1) on the transmission mechanism side sucks the coolant collected in the transmission mechanism sump (65) and the coolant transferred from the stator housing sump (55) into the coolant storage tank (35) in a dual-function manner.

5. The coolant supply system according to claim 3, characterized in that: There is no flow connection between the stator housing sump (55) and the transmission mechanism sump (65), and a separate stator housing suction point (A3) is provided on the side of the stator housing sump (55) close to the transmission mechanism. A motor return pump (71) is assigned to the stator housing suction point (A3), which returns the coolant from the stator housing suction point (A3) to the coolant storage tank (35).

6. The coolant supply system according to claim 1 or 2, characterized in that: The return pumps (56, 59, 71) are arranged on the same axial side of the stator housing, and the stator housing sump (55) extends in the axial direction to the corresponding axial side of the stator housing.

7. The coolant supply system according to claim 6, characterized in that: A suction point (A2) arranged on the axial side of the stator housing (2) facing away from the pump is connected to the motor return pump (56) via a return line (69).

8. The coolant supply system according to claim 7, characterized in that: The return line (69) is parallel to the axis of the stator housing sump (55), and the return line (69) is made of the same material and is formed in one piece on the stator housing (2).

9. The coolant supply system according to claim 8, characterized in that: The return line (69) is formed together with the stator housing sump (55) from the same material and in one piece on the stator housing (2).

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