CN114544168A

CN114544168A - Drive unit for a drive train test stand and drive train test stand

Info

Publication number: CN114544168A
Application number: CN202111402969.8A
Authority: CN
Inventors: C·黑尔
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2020-11-26
Filing date: 2021-11-24
Publication date: 2022-05-27
Also published as: DE102020214884A1; DE102020214884B4

Abstract

The invention relates to a drive unit for testing a drive train test stand of an electric motor vehicle drive train, comprising an electric motor with a housing and a carrier device for carrying the electric motor, wherein the housing comprises a mechanical front yoke integrally connected with a front bearing cover of the electric motor and a mechanical rear yoke integrally connected with a rear bearing cover of the electric motor, wherein the front and rear yokes respectively extend from the electric motor in two transverse directions above the electric motor, and wherein the carrier device carries the electric motor by means of the front and rear yokes, such that a free space is formed below and to the side of the electric motor. The drive unit according to the invention is characterized in that the drive unit further comprises at least one support module, which additionally supports the housing on the carrier device. The invention also relates to a corresponding power train test bench.

Description

Drive unit for a power train test stand and power train test stand

Technical Field

The present invention relates to a drive unit for testing a powertrain test stand of an electric motor vehicle powertrain according to the preamble of claim 1 and to a corresponding powertrain test stand for testing an electric motor vehicle powertrain.

Background

Transmission or drivetrain test stands for testing motor vehicle transmissions or complete motor vehicle drivetrains are known from the prior art. Such test stands are used, on the one hand, to identify functional faults in the drive train directly after its manufacture by means of a series of load tests in the context of so-called end-of-line tests. Typical malfunctions result, for example, from components with play, such as gears, synchronizer rings, synchronizer bodies, multi-plate clutch disks and shafts, which can shift or even excite vibrations. Within the scope of functional verification, acoustic behavior and switching quality are also often tested. On the other hand, however, such test stands are also used in the development of continuous improvements for motor vehicle powertrains. Typically, such a powertrain test stand comprises an electric motor as a drive.

In this case, DE 102012018359 a1 describes a transmission test stand with a first servomotor serving as a drive motor and a second servomotor serving as a brake motor. The drive motor is connected via a clutch to the drive shaft of the motor vehicle transmission to be tested and is controlled in terms of its rotational speed by a PC, wherein an arbitrary rotational speed profile can be simulated. The brake motor is connected to the driven shaft of the motor vehicle transmission to be tested via a further clutch. The rotational speed of the second motor is also controlled by the PC. The rotation speed curve simulated by the PC is a rotation speed curve measured in an actual running test.

Furthermore, in the prior art, electric motor vehicle drivetrains are increasingly emerging whose construction differs in various respects from that of an internal combustion engine-driven drivetrain. In particular, electric motor vehicle drivetrains must be designed for significantly higher input rotational speeds, which places particular demands on the noise behavior and in particular on the vibration damping at very high rotational speeds. A drive train test stand for an electric motor vehicle drive train must be able to provide correspondingly high rotational speeds and also have a drive unit which generates or introduces only minimal mechanical vibrations into the test piece even at high and very high rotational speeds. Another important criterion of an electric drive-train test stand is that it is also possible to test an electric, axis-parallel axle drive, in which at least one axle must pass immediately below or to the side of the drive motor of the test stand. Accordingly, sufficient free construction space must be provided laterally and below the drive motor of the drive unit.

An electric machine is known from DE 1915896 a1, in which a stator plate is stamped such that the carrying structure of the electric machine, or at least a part of the electric machine, is obtained from the same plate. By means of the carrying structure, the electric machine can be supported such that the free space is located below the electric machine.

DE 102016224138 a1 describes an electric motor for a drive unit of an electric drive-train test stand, in which a housing can be supported by a mechanical front yoke and a mechanical rear yoke. The yoke arms extend laterally in radial direction from the upper region of the housing, so that there is a free space below and laterally to the motor, through which the driven shaft of the test piece can pass by the electric motor, for example. Here, the front yoke is formed integrally with a front bearing cover of the electric motor, and the rear yoke is formed integrally with a rear bearing cover of the electric motor. Since the bearing of the motor shaft is thus very firmly and rigidly connected to the suspension of the electric motor, a pronounced damping effect on occurring vibrations occurs, in particular even at very high motor speeds (as is required for testing an electric motor vehicle drive train).

However, the known drive train test stands are disadvantageous because at increasingly high rotational speeds, these drive units are still somewhat prone to vibrations caused by the electric motor, which may then be transmitted to the test piece and adversely affect the test results.

Disclosure of Invention

The object of the present invention is to propose an improved drive unit for testing a drive train test stand of an electric motor vehicle drive train.

According to the invention, this object is achieved by a drive unit for testing a powertrain test stand of an electric motor vehicle powertrain according to claim 1. Advantageous embodiments emerge from the dependent claims.

The invention relates to a drive unit for testing a powertrain test stand of an electric motor vehicle powertrain, comprising an electric motor with a housing and a carrier device for carrying the electric motor, wherein the housing comprises a mechanical front yoke integrally connected with a front bearing cap of the electric motor and a mechanical rear yoke integrally connected with a rear bearing cap of the electric motor, wherein the front and rear yokes extend from the electric motor in two transverse directions above the electric motor, respectively, and wherein the carrier device carries the electric motor by means of the front and rear yokes, such that a free space is formed below and to the side of the electric motor. The drive unit according to the invention is characterized in that the drive unit further comprises at least one support module which additionally supports the housing on the carrier.

The invention therefore relates to a drive unit for a power train test bench designed for testing an electric motor vehicle power train. The test specimen to be tested is therefore an electric motor vehicle drive train. Electric motor vehicle drivetrains differ from conventionally driven motor vehicle drivetrains in particular by a much higher input rotational speed, which in turn places relatively high demands on the vibration damping or stiffness of the motor vehicle drivetrain and on the noise behavior of the motor vehicle drivetrain.

In addition to the drive unit, such a power train test bench typically comprises a holder for holding the test piece and possibly one or more driven units which are capable of generating an adjustable load of the test piece relative to the drive unit.

The drive unit provided according to the invention itself comprises an electric motor with a housing, wherein the electric motor is capable of applying an input rotational speed and an input torque to the test piece in dependence on the actuation of the electric motor. The housing is comprised of an outer housing and front and rear bearing caps that axially enclose the outer housing. The front bearing cover and the rear bearing cover are therefore integral parts of the housing. Furthermore, the front bearing cover holds the front bearing of the motor shaft and the rear bearing cover correspondingly holds the rear bearing of the motor shaft. The motor shaft is thus supported at the front or rear bearing cover by means of the front or rear bearing.

Here, the front bearing cap is formed integrally with a mechanical front yoke which is located above the electric motor and extends from the electric motor symmetrically in two lateral directions. Likewise, the rear bearing cap is formed integrally with a mechanical back yoke, which is also located above the electric motor and extends from the electric motor in both lateral directions, likewise symmetrically. The advantage of this embodiment is that the connection of the front or rear yoke to the electric motor is designed to be particularly rigid, which is advantageous for improving the vibration damping and thus the test accuracy of the test piece.

The carrier device serves to support the electric motor by means of the front and rear yokes and has a bearing surface adapted thereto. Advantageously, the front and rear yokes can be screwed or clamped to the support device on the bearing surface, so that a particularly firm and particularly vibration-damping connection is obtained. It is furthermore preferably provided that the support device is at least partially made of mineral concrete, polymer concrete or similar highly damping materials, which are likewise very suitable for damping vibrations. Such suitable materials are known, for example, under the protected name "Hydropol". Particularly preferably, the support device also has a metal skeleton which is surrounded, in particular cast, with a damping material. The carrier device itself is therefore also designed to be vibration-damped. Due to the very high rotational speeds typical of electric motors compared to combustion engines, the vibration damping of the drive unit according to the invention is of great significance, since otherwise the vibrations generated by the electric motor would propagate into the test piece and adversely affect its test behavior.

The front and rear yokes of the electric motor are preferably designed to be metallic and solid, in particular made of steel or a steel alloy. Alternatively, the front and rear yokes are preferably formed of aluminum or an aluminum alloy. Furthermore, the front and rear yokes are also designed for supporting the electric motor on a carrier device. Particularly preferably, the front and rear yokes, like the carrier, comprise a metal skeleton which is surrounded by mineral concrete, polymer concrete or similar high damping materials, in particular "Hydropol".

Since the electric motor is supported on the carrier device via the front and rear yokes, in particular via the lateral outer ends of the front and rear yokes, a relatively large free space is created below and laterally of the electric motor, through which the driven shaft of the test piece can pass by the electric motor, for example. This is a frequently occurring requirement in connection with the testing of electric motor vehicle powertrains, because of their design as axle drives or as so-called axis-parallel drives with electric drives arranged parallel to the axle. In an electric motor vehicle drive train with a parallel-axis design, the output shaft is arranged outside the electric drive, i.e. axially parallel to the motor shaft of the electric drive.

According to the invention, it is now proposed that the drive unit further comprises at least one support module which additionally supports the housing on the carrier device. The support module, by virtue of the additional support of the housing of the electric motor relative to the support device, enables a further stiffening of the drive unit and thus a more precise test of the test piece, in particular even at very high rotational speeds and at further increasing rotational speeds of the future electric motor vehicle drive train.

It is preferably provided that the drive unit is designed such that the first natural frequency of the drive unit is higher than the first rotational stage of the electric motor. Thus, at a motor speed of 15,000 rpm, the natural frequency of the drive unit is higher than about 350 Hz. This has proven to be particularly suitable for testing an electric motor vehicle drive train rotating at high speeds.

According to a preferred embodiment of the invention, it is provided that the at least one support module is designed as a vibration damper. Advantageously, the at least one support module is designed for this purpose as a cylinder-piston module which comprises a damping medium in the cylinder which flows past or past the piston. The vibrations occurring can therefore be damped particularly effectively despite the high stiffness of the drive unit.

According to a further preferred embodiment of the invention, it is provided that the at least one support module is clampable by means of a thread, by means of a spring or by means of an insertable wedge. This results in the advantage that the at least one support module reinforces the electric motor with a settable or predetermined pretensioning force relative to the support device. In the case of the use of a thread, the length of the at least one support module is adjustable by screwing in or out the foot of the at least one support module, so that the at least one support module can be arranged between the electric motor and the carrier device, and then the foot can be screwed out of the at least one support module by means of the thread, so that the at least one support module has the desired pretensioning force between the electric motor and the carrier device and is held between the electric motor and the carrier device as a result of the pretensioning force. In the case of springs, the pretensioning force is predetermined by the spring strength, which presses the legs of the at least one support module into the final position. By compression of the spring, the at least one support module may be arranged between the electric motor and the carrier device. When the spring is no longer compressed, the at least one support module is clamped between the electric motor and the carrier device. The spring is preferably a coil spring. If the at least one support module is to be clamped between the housing and the carrier by means of insertable wedges, the required number of wedges can be inserted, for example, into receptacles provided for this purpose of the at least one support module, so that the axial ends of the at least one support module are spread apart from one another. It is likewise conceivable and preferred to arrange a wedge between the housing and the at least one support module or between the carrying device and the at least one support module in order to achieve a firm clamping in this way. In both cases, the wedges can be arranged, for example, by a short and targeted stroke of a hammer or similar tool.

According to a further preferred embodiment of the invention, it is provided that the at least one support module is screwable to the housing and the carrier by means of threaded bores provided for this purpose. The threaded holes are advantageously located in the housing and the carrier. The at least one support module can therefore be held securely in the position provided for this purpose and is secured against loosening or sliding, in particular even in the event of vibrations.

According to a further preferred embodiment of the invention, it is provided that the at least one support module rests on the front bearing cap or the rear bearing cap. Since the bearing of the motor shaft is held by the front or rear bearing cap of the electric motor and the vibrations generated by the rotation of the motor shaft are conducted directly into the bearing, the vibration damping of the electric motor can be improved particularly effectively by further reinforcing the electric motor in the region of the bearing cap relative to the carrier device. In addition to the already mentioned advantageous reinforcement by the at least one support module, an additional advantage is achieved when the at least one support module is arranged on the front or rear bearing cover in that an idealisation of the force flow of the mechanical vibrations of the electric motor is achieved in such a way that it can be conducted directly from the respective bearing, i.e. the point of vibration generation, into the carrier device by the at least one support module. This achieves an additional improvement of the vibration behavior.

According to a further preferred embodiment of the invention, it is provided that the at least one support module rests either exactly horizontally or exactly vertically on the housing. This has proven to be advantageous in terms of the supportability of the at least one support module relative to the carrier, since the carrier is usually dominated by horizontal and vertical planes. As a result, a relatively greater pretensioning force can be generated between the electric motor and the support device by means of the at least one support module due to the better supportability, which in turn contributes to a correspondingly better improvement of the rigidity of the drive unit according to the invention.

According to a further preferred embodiment of the invention, it is provided that at least one support module is respectively attached to the front bearing cap or the rear bearing cap. The improvements mentioned in terms of the stiffness and the damping of the drive unit according to the invention are therefore achieved on both axial ends of the electric motor, which overall achieves greater stiffness or better damping. A further great advantage resulting from the contact of more than one support module on the front and rear bearing caps is the fact that the contact pressure exerted by the support modules on the housing does not lead to an elastic deformation of the housing, since the support modules are preferably arranged on the front or rear bearing cap in such a way that the contact pressure from the support modules is opposed and thus no further induced bending forces act on the housing. The housing is therefore kept substantially untensioned, so that even at very high contact pressures, a misalignment of the front bearing relative to the rear bearing does not occur, which would lead to increased friction, increased wear and increased vibrations. Since the rotational speed of the electric motor is very high, a precise orientation of the two bearings relative to each other over a few micrometers is required.

According to a further preferred embodiment of the invention, two support modules are respectively attached to the front bearing cap and the rear bearing cap. This achieves a further improvement in the rigidity of the drive unit and a further improvement in the vibration damping of the drive unit.

According to a further preferred embodiment of the invention, three support modules are respectively attached to the front bearing cap and the rear bearing cap. This achieves a still further improvement of the stiffness of the drive unit and a still further improvement of the vibration damping of the drive unit.

According to a further preferred embodiment of the invention, it is proposed that the drive unit further comprises a terminal box, wherein the terminal box is placed flush on the top side of the front yoke and on the top side of the rear yoke, and wherein the terminal box has additional reinforcing struts. The use of so-called terminal blocks for receiving electrical leads and, if appropriate, power electronics modules of an electric motor is known from the prior art. However, since the terminal block contains an additional stiffening web which is in particular solid and formed from steel and is placed flush on the top side of the yoke, an additional damping effect and yet further stiffening of the drive unit are produced.

According to a further preferred embodiment of the invention, it is provided that the front yoke and/or the rear yoke have a bearing fluid cooling device. The bearing fluid cooling device can effectively discharge waste heat generated in the front bearing or the rear bearing of the motor shaft, and thus reduce the wear of the respective bearings. The fluid used for cooling is preferably a liquid, such as water or oil.

According to a further preferred embodiment of the invention, it is provided that the housing has a radial diameter of less than 270 mm. The advantage is thereby obtained that the electric motor is constructed relatively slim in order to ensure as much free space as possible below and to the side of the electric motor. This further facilitates testing of an electric motor vehicle drive train, which is designed in an axially parallel manner, in particular without an additional steering gear.

According to a further preferred embodiment of the invention, it is proposed that the electric motor is designed to achieve a rotational speed of up to 25000 revolutions per minute. Particularly preferably, the electric motor is designed to achieve a rotational speed of more than 15000 to 25000 revolutions per minute, and particularly preferably, the electric motor is designed to achieve a rotational speed of more than 20000 to 25000 revolutions per minute. This rotational speed corresponds to the rotational speed which is generated by the electric drive of the electric motor vehicle, i.e. by the electric motor thereof, during operation of the latter. As a result, a near-actual test of the electric motor vehicle drive can be achieved.

The electric motor may also be designed to achieve a rotational speed of greater than 25000 revolutions per minute.

The invention also relates to a drive train test bench for testing an electric motor vehicle drive train, comprising a drive unit according to the invention. The advantages described in connection with the drive unit according to the invention thus also apply to the powertrain test bench according to the invention.

Drawings

The invention is explained below by way of example with the aid of embodiments shown in the drawings.

In the drawings:

figure 1 shows schematically and exemplarily a possible design of a drive unit according to the invention for testing a powertrain test stand of an electric motor vehicle powertrain,

figure 2 shows schematically and schematically a further possible design of the drive unit according to the invention,

fig. 3 shows, by way of example and schematically, yet another possible design of a drive unit according to the invention, and

fig. 4 shows an exemplary and schematic illustration of a further possible embodiment of the drive unit according to the invention.

List of reference numerals

1 electric motor

2 drive unit

3 case

4 bearing device

5 front bearing cover

6 front yoke

7 terminal box

8 support module

8' support module

Detailed Description

Identical objects, functional units and similar components are denoted by the same reference numerals throughout the figures. These objects, functional units and similar components are embodied in the same way in terms of their technical features, unless explicitly or implicitly derived from the description, for example in other forms.

Fig. 1 shows an exemplary and schematic illustration of a possible embodiment of a drive unit 2 according to the invention for testing a drive train test stand, not shown in fig. 1, of an electric motor vehicle drive train. The drive unit 1 comprises an electric motor 1 with a housing 3 and a carrier device 4 for carrying the electric motor 1. The housing 3 comprises, on its side, a mechanical front yoke 6 integrally connected to a front bearing cap 5 of the electric motor 1 and a mechanical rear yoke (also not shown in the perspective view of fig. 1) integrally connected to a rear bearing cap (not shown in the perspective view of fig. 1) of the electric motor 1. As can be seen, the front yoke 6 extends out from the electric motor 1 in two lateral directions above the electric motor 1. Likewise, a back yoke, not shown in fig. 1, extends out of the electric motor 1 also in both lateral directions above the electric motor 1. The electric motor 1 is placed on the carrier 4 by means of the axial ends of the front and

rear yokes

6, 4, so that the carrier 4 thus carries the electric motor 1. For example, the axial ends of the front yoke 6 and the rear yoke are connected to the carrier 4 by a threaded connection. By means of the electric motor 1 being carried by the carrier device 4 via the front yoke 6 and the rear yoke as in fig. 1, free spaces are formed below the electric motor 1 and on both sides of the electric motor 1, through which free spaces, for example, the driven shaft of a test piece (not shown in fig. 1) can pass by the electric motor. Furthermore, a terminal box 7 can be seen, which is placed, for example, flush on the top side of the front yoke 6 and the top side of the rear yoke and has additional reinforcing struts in its interior.

Fig. 1 also shows a support module 8, which rests precisely horizontally on the front bearing cap 5. By means of the thread of the support module 8, the support module 8 can be clamped between the electric motor 1 and the support device 4 with a pretensioning force that can be set by the thread. Thereby further improving the rigidity of the drive unit 2. Thus, since the support module 8 can be removed relatively simply and arranged again on the drive unit 2, it can be arranged in a free space below or to the side of the electric motor 1, which free space is accordingly not required for the test piece, depending on the individual constructional space requirement of the respective test piece to be tested.

The support module 8 can be designed, for example, as a vibration damper, which is formed by a cylinder-piston module and a damping medium in the cylinder.

Fig. 2 shows an exemplary and schematic illustration of a further possible embodiment of the drive unit 2 according to the invention. The design of fig. 2 differs from the design shown by way of example in fig. 1 in that a further support module 8' is provided. This further support module 8' is, for example, identical to the support module 8 and is arranged on the side of the electric motor 1 opposite the support module 8. A further improved vibration damping and a further increased stiffness of the drive unit 2 are thereby obtained. Furthermore, an undesired tensioning of the housing 3 can advantageously be avoided, since the pressing forces generated by the support modules 8 and 8' oppose one another, so that no bending forces act on the housing 3 overall.

Fig. 3 shows an exemplary and schematic illustration of a further possible embodiment of the drive unit 2 according to the invention. The design of fig. 3 differs from the design illustrated by way of example in fig. 1 and 2 in that a further support module 8 ″ is provided. This further support module 8 "is of the same design as the

support modules

8, 8" and is arranged on the bottom side of the electric motor 1. This results in a still further improved vibration damping and a still further increased stiffness of the drive unit 2.

Fig. 4 shows an exemplary and schematic illustration of a further possible embodiment of the drive unit 2 according to the invention. The support module 8' ″, which rests exactly horizontally against the rear bearing cap of the electric motor 1, can be seen from the perspective view in fig. 4.

Claims

1. A drive unit (2) for testing a powertrain test stand of an electric motor vehicle powertrain, comprising an electric motor (1) having a housing (3) and a carrier device (4) for carrying the electric motor (1), wherein the housing (3) comprises a mechanical front yoke (6) integrally connected with a front bearing cover (5) of the electric motor (1) and a mechanical rear yoke integrally connected with a rear bearing cover of the electric motor (1), wherein the front yoke (5) and the rear yoke respectively extend in two transverse directions from the electric motor (1) above the electric motor (1), and wherein the carrier device (4) carries the electric motor (1) by means of the front yoke (6) and the rear yoke, forming a free space below and to the side of the electric motor (1), characterized in that the drive unit (2) further comprises at least one support module (8, 8', 8 ", 8"') additionally supporting the housing (3) on the carrier device (4).

2. Drive unit (2) according to claim 1, characterized in that the at least one support module (8, 8', 8 ", 8"') is designed as a vibration damper.

3. Drive unit (2) according to at least one of claims 1 and 2, characterized in that the at least one support module (8, 8', 8 ", 8"') is clampable by means of a thread, by means of a spring or by means of an insertable wedge.

4. Drive unit (2) according to at least one of claims 1 to 3, characterized in that the at least one support module (8, 8', 8 ", 8"') is screwable with the housing (3) and the carrier device (4) by means of threaded holes provided for this purpose.

5. Drive unit (2) according to at least one of claims 1 to 4, characterized in that the at least one support module (8, 8', 8 ", 8"') abuts against the front or rear bearing cap (5).

6. Drive unit (2) according to at least one of claims 1 to 5, characterized in that the at least one support module (8, 8', 8 ", 8"') abuts either exactly horizontally or exactly vertically against the housing (3).

7. Drive unit (2) according to at least one of claims 1 to 6, characterized in that at least one support module (8, 8', 8 ", 8"') is respectively applied to the front or rear bearing cap (5).

8. Drive unit (2) according to at least one of claims 1 to 7, characterized in that two support modules (8, 8', 8 ", 8"') are respectively applied to the front and rear bearing caps (5).

9. Drive unit (2) according to at least one of claims 1 to 8, characterized in that three support modules (8, 8', 8 ", 8"') are respectively applied to the front and rear bearing caps (5).

10. Drive unit (2) according to at least one of claims 1 to 9, characterized in that the drive unit (2) further comprises a junction box (7), wherein the junction box (7) is placed flush on the top side of the front yoke (6) and the top side of the rear yoke, and wherein the junction box (7) has additional stiffening struts.

11. Drive unit (2) according to at least one of claims 1 to 10, characterized in that the front yoke (6) and/or the rear yoke has bearing fluid cooling means.

12. Drive unit (2) according to at least one of claims 1 to 11, characterized in that the housing (3) has a radial diameter of less than 270 mm.

13. Drive unit (2) according to at least one of claims 1 to 12, characterized in that the electric motor (1) is designed to achieve a rotational speed of up to 25000 revolutions per minute.

14. Drive unit (2) according to at least one of claims 1 to 13, characterized in that the carrier (4) and/or the front yoke (6) and/or the rear yoke are at least partially composed of mineral or polymer concrete surrounding a metal skeleton.

15. A powertrain test bench for testing an electric motor vehicle powertrain, characterized in that it comprises a drive unit (2) according to at least one of claims 1 to 14.