Measuring device for testing an electric drive motor of a motor vehicle, and method for testing an electric drive motor of a motor vehicle

Abstract

Measuring device for testing an electric drive motor (2) of a motor vehicle, comprising - an electric drive motor to be tested (2), - a first drive shaft (5) and a second drive shaft (9) extending from the drive machine (2) to opposite sides and which can be driven by the drive machine (2), - a first gearbox (7), wherein the first drive shaft (5) is connected to a gearbox input (6) of the first gearbox (7), - a second gearbox (11), wherein the second drive shaft (9) is connected to a gearbox input (10) of the second gearbox (11), - a first output shaft (14) connected to a gearbox output (13) of the first gearbox (7) and an input (15) of a first electric load machine (16) which is identical in construction to the drive machine (2), - a second output shaft (18) connected to a gearbox output (17) of the second gearbox (11) and an input (19) of a second electric load machine (20) which is identical in construction to the drive machine (2), as well as - a power supply (23) connected to the drive machine (2) and the first and second load machines (16, 20).

Description

[0001] The invention relates to a measuring device for testing an electric drive motor of a motor vehicle.

[0002] Electrically powered vehicles have at least one electric drive motor, which propels the vehicle and is designed with sufficient power for this purpose. Such an electric drive motor typically consists of an electric motor with associated power electronics and a gearbox, which is also electrically controlled. The power electronics are connected to a power supply that provides the operating current and also handle the control functions for the operation of the drive motor.

[0003] During the development of a drive system, and before its installation in a motor vehicle, the drive system must be tested accordingly, meaning its function and durability must be verified. This occurs both in the development phase, when a new type of engine is being developed, and in the production phase, when the drive system is tested before assembly. A suitable measuring device, also known as a test bench, is used for this testing.

[0004] In a simple configuration of such a measuring device, the electric drive motor is connected to a so-called wheel motor via two drive shafts extending in opposite directions. These wheel motors serve to simulate the drive wheels of the vehicle. They generate resistance to simulate driving operation. Ultimately, the drive train is replicated in this way. The drive motor is coupled to a power supply. It operates as a motor, thus generating torque during operation, which is transmitted to the wheel motors via the drive shafts. These are separate electric motors that generate a load torque against which the drive motor works to simulate the influence of the vehicle's drive wheels.

[0005] The two drive branches, each leading to one side of the drive machine and comprising a drive shaft and a wheel motor, can be considered separately. This means that each wheel motor can be operated independently as a generator, consequently generating different load torques and / or speeds. This can even extend to a point where one wheel motor is completely locked, meaning no output is generated from it, but only from the other drive branch. This design also allows for testing of the differential integrated into the drive machine. However, a disadvantage of this configuration is the requirement for separate wheel motors—that is, separate, very powerful electric motors and specific inverter systems, which are correspondingly large and expensive.

[0006] It is also known, see for example CN 117233508 A, to design the measuring device as a so-called back-to-back test bench. Here, two identical electric drive machines are arranged virtually in parallel. Each drive machine is connected to a gearbox via two drive shafts extending to opposite sides, with each gearbox being assigned to both drive machines; that is, the two drive shafts of the two drive machines are coupled to a common gearbox. Both drive machines are powered by a single power supply. The operation is such that one drive machine operates as a motor and the other as a generator; that is, one generates torque while the other generates load torque, and the mode can also be reversed. Since both machines are coupled to each other via the gearboxes, they can interact accordingly.The advantage of this arrangement is that separate, correspondingly powerful wheel machines with separate inverter systems are not required. Instead, a single power supply can be used for both drive machines, both of which are machines under test. A lower power supply is also sufficient, since a significant portion of the energy required to power the motor-driven test specimen is generated during the generator operation of one drive machine. However, a disadvantage is that the rigid coupling via the two gearboxes prevents testing the differential of each drive machine, as the rotational speeds of the two sides are determined by the mechanical characteristics of the coupled gearboxes.

[0007] The invention is based on the problem of providing an improved measuring device in comparison.

[0008] To solve the problem, the invention provides a measuring device for testing an electric drive motor of a motor vehicle, comprising: - an electric drive motor to be tested, - a first drive shaft and a second drive shaft, which extend from the drive machine to opposite sides and which can be driven by the drive machine, - a first gearbox, wherein the first drive shaft is connected to a gearbox input of the first gearbox, - a second gearbox, wherein the second drive shaft is connected to a gearbox input of the second gearbox, - a first output shaft connected to a gearbox output of the first gearbox and an input of a first electric load machine, which is identical in construction to the drive machine, - a second output shaft connected to a gearbox output of the second gearbox and an input of a second electric load machine, which is identical in construction to the drive machine, as well as - a power supply connected to the drive motor as well as the first and second load motors.

[0009] The measuring device according to the invention is characterized in that at least three electric machines are integrated, one of which is the drive machine to be tested and the other two function as load machines. Furthermore, two separate drive trains are implemented. The electric drive machine to be tested is positioned virtually at the center of the arrangement. A first and a second drive shaft extend from it to opposite sides, simulating the wheel axles. The first drive shaft is connected to the input of a first gearbox, the output of which is connected via a first output shaft to the input of a machine that is identical in construction, at least with regard to the electric machine, but which functions as the first load machine.On the other side, the second drive shaft is connected to the input of a second gearbox, whose output is connected via a second output shaft to the input of another machine that is identical in construction, at least with regard to the electric motor, but which functions as a second load machine. The two load machines are not coupled to each other. Thus, the two load machines are identical in construction, and therefore have the same power output as the drive machine under test, at least with regard to their electric motor and power electronics, but they do not necessarily have other typical drive machine components such as a gearbox and differential. However, they could also be two identical load machines, meaning they are identical in construction to the drive machine under test and could be tested interchangeably with it.

[0010] All three machines are operated via a common power supply, which in turn can have a correspondingly small power output, since in the present case, when the two load machines are operated as generators, a correspondingly large amount of electricity is produced, which in turn can be used to power the working machine to be tested.

[0011] Since, in the present case, two identical electric machines—that is, electric motors with power electronics, or preferably even identical drive machines—are used as load machines, there is consequently no need to provide correspondingly powerful, separate wheel machines with associated converter systems. A further significant advantage is that, in principle, the differential of the drive machine under test can also be tested, since the two load machines are independent of each other and can therefore generate different load torques.

[0012] According to a further development of the invention, the two load machines can be operated completely independently of each other, so that each load machine can generate virtually any load torque within its typical power range when operating as a generator. During this generator operation, one load machine can also be locked, i.e., it cannot rotate, so that no torque is derived via this drive branch and the differential of the drive machine under test is locked on that side. The output then only occurs via the other drive branch, provided the differential is functioning correctly. Of course, the arrangement can also be reversed so that the differential can also be tested with regard to the output via the other branch.

[0013] It is particularly advantageous if both load machines can be operated as both generators and motors. In generator mode, they act as a true load, generating a load torque as described above, against which the drive machine under test operates. However, if the operating mode of both the load machines and the drive machine under test is switched, and the load machines are operated as motors and the drive machine as generators, the drive machine can also be tested for its functionality as a generator, since in this case it ultimately generates a load torque.

[0014] As described, the two load machines are preferably identical in construction to the drive machine, i.e., there are three identical machines. This allows the two load machines to be tested, at least partially, with regard to their functionality, especially their operation as generators.

[0015] Alternatively, it is also conceivable that the two load machines are integrated into a single machine. This means that only one machine is provided, which ultimately comprises only two electric machines that, together with their respective power electronics, are identical to the electric machine and power electronics of the drive machine under test.

[0016] The power supply for all three machines can be a simple DC power source, or alternatively, a battery simulator can be used. The drive motor is installed in an electric vehicle, where it is powered by a storage battery. Using a battery simulator that replicates the function of such a battery storage system allows for the simulation of a real-world operating scenario, making the test even more realistic.

[0017] Furthermore, it is conceivable that first and second measuring devices are provided, whereby at least the torque and / or speed of the first drive shaft can be detected via the first measuring device, and at least the torque and / or speed of the second drive shaft can be detected via the second measuring device. For this purpose, a corresponding flange can be provided on each drive shaft, at which the torque and speed can be measured.

[0018] In addition to the measuring device, the invention further relates to a method for testing an electric drive motor for a motor vehicle, wherein the electric drive motor is connected via a first drive shaft to a first gearbox and via a second drive shaft to a second gearbox, wherein the first gearbox is connected via a first output shaft of a first electric load motor and the second gearbox is connected via a second output shaft to a second electric load motor, and wherein the drive motor and the first and second load motors are identical in construction and are connected to a power supply. The method provides that the first and second load motors are operated separately as generators and that either the same load torque or different load torques are generated via the first and second load motors.The two load machines are therefore identical in construction, at least with regard to their electric motor and power electronics, and thus have the same performance as the drive machine being tested, but do not have to have other typical elements of the drive machine such as gearbox and differential.

[0019] It may be provided that both load machines are operated as generators to generate a load torque as well as motors to generate torque or corresponding speeds, and that the drive machine is operated as a generator.

[0020] Finally, it may be provided that identical machines are used as the drive machine and as the load machine, i.e., that three identically constructed machines are used according to the procedure.

[0021] Further advantages and details of the present invention will become apparent from the exemplary embodiment described below and from the drawing.

[0022] The figure shows a schematic diagram of a measuring device 1 according to the invention for testing an electric drive motor, i.e., a correspondingly configured test bench. The measuring device 1 comprises an electric drive motor 2 to be tested, which represents the test specimen. It includes an electric motor, associated power electronics, and a differential via which two outputs, a first output 3 and a second output 4, are coupled. A first drive shaft 5 is connected to the first output 3 and is coupled to an input 6 of a first gearbox 7. A first measuring device 8 is interposed between these components and serves to measure a torque or rotational speed applied to the first drive shaft 5.

[0023] The second output 4 is connected to a second drive shaft 9, which in turn is coupled to an input 10 of a second gearbox 11, with a second measuring device 12 being interposed here as well, which serves to detect a torque or speed applied to the second drive shaft 9.

[0024] A gearbox output 13 of the first gearbox 7 is connected via a first output shaft 14 to an input 15 of a first load machine 16. Similarly, a gearbox output 17 of the second gearbox 11 is connected via a second output shaft 18 to an input 19 of a second load machine 20. Thus, two separate load circuits 21 and 22 are implemented, which are connected to each other via the drive unit 2 under test, or are operated by it. The first load circuit runs from the drive machine 2 via the first drive shaft 5, the first gearbox 7, and the first output shaft 14 to the first load machine 16. The second load circuit runs from the drive machine 2 via the second drive shaft 9, the second gearbox 11, and the second output shaft 18 to the second load machine 20.

[0025] The machine to be tested, 2, comprises, as described, an electric motor, associated power electronics, a gearbox, and a differential. The first and second load machines 16, 20 are preferably identical to the machine to 2, meaning they have an identically designed electric motor, identically designed power electronics, an identically designed gearbox, and an identically designed differential. Thus, three identical machines are integrated. These differentials are functionally blocked or locked, or, in the case of non-identical machines, are not even installed.

[0026] The drive machine 2 and the two load machines 16, 20 are supplied via a common power supply 23. Significantly less power needs to be provided by this supply, since in test operation the two load machines 16, 20 are switched and operate as generators, thus producing electricity that is used to supply the driven machine 2 under test. This means that the power, or rather the amount of current, that the power supply 23 needs to provide is relatively low.

[0027] In operation, the two load machines 16, 20 are operated as generators, thus producing a load torque. The drive machine 2 is operated as a motor, thus generating a driving torque which is applied to the respective drive shafts 5, 9 and the respective gearboxes 7, 11, and which is counteracted by the load torque of the two load machines 16, 20, since the respective gearboxes 7, 11 couple the torques accordingly.

[0028] The two load machines 16, 20 can generate an identical load moment, i.e., the generated torque / speed, which is distributed via the two drive shafts 5, 9, counteracts an identical load moment, whereby the torques applied to the two drive shafts 5, 9 are also identical due to the identical load moments.

[0029] The two load machines 16, 20 are separately controllable, meaning that each load machine 16, 20 can generate an individual load torque, ranging from a minimum to a maximum torque at which the respective load machine 16, 20 is locked, i.e., does not operate or rotate. This allows the differential of the drive machine to be tested, as the output via the respective load circuit 21, 22 (i.e., the respective drive circuit) is different. If one load circuit is locked by locking the respective load machine 16, 20, the output occurs only via the other load circuit, and vice versa. The differential can therefore be actively tested, and the rotational speeds on both sides (i.e., in both load circuits 21, 22) can be actively influenced, allowing for the testing of a wide variety of operating scenarios.

[0030] As explained above, the two load machines 16 and 20 are identical in design to the corresponding drive machine 2. They can therefore be used equally well as drive machine 2 in a subsequent test, since they too are ultimately suitable and intended for installation in a motor vehicle. If they are integrated into the measuring device 1 as load machines, they can nevertheless also be tested in their function as load machines, i.e., with regard to their generator operation.

[0031] However, it is also conceivable that the two load machines 16, 20 are operated as motors, thus generating a drive torque, while the drive machine 2 is operated in generator mode, so that this operating mode can also be tested. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 117233508 A

[0006]

Claims

[1] Measuring device for testing an electric drive motor (2) of a motor vehicle, comprising: - an electric drive motor to be tested (2), - a first drive shaft (5) and a second drive shaft (9) extending from the drive machine (2) to opposite sides and which can be driven by the drive machine (2), - a first gearbox (7), wherein the first drive shaft (5) is connected to a gearbox input (6) of the first gearbox (7), - a second gearbox (11), wherein the second drive shaft (9) is connected to a gearbox input (10) of the second gearbox (11), - a first output shaft (14) connected to a gearbox output (13) of the first gearbox (7) and an input (15) of a first electric load machine (16) which is identical in construction to the drive machine (2), - a second output shaft (18) connected to a gearbox output (17) of the second gearbox (11) and an input (19) of a second electric load machine (20) which is identical in construction to the drive machine (2), as well as - a power supply (23) which is connected to the drive machine (2) and the first and second load machines (16, 20). [2] Measuring device according to claim 1, characterized by that the two load machines (16, 20) can be operated independently of each other. [3] Measuring device according to claim 1 or 2, characterized by , that the two load machines (16, 20) can be operated both as generators and as motors. [4] Measuring device according to one of the preceding claims, characterized by that the two load machines (16, 20) are identical in construction to the drive machine (2) or different from it. [5] Measuring device according to any one of claims 1 to 3, characterized by, that the two load machines (16, 20) are integrated into a common machine. [6] Measuring device according to one of the preceding claims, characterized by , that the power supply (23) is a DC power source or a battery simulator. [7] Measuring device according to one of the preceding claims, characterized by , that first and second measuring means (8, 12) are provided, wherein at least a torque and / or a speed of the first drive shaft (5) can be detected via the first measuring means (8) and at least a torque and / or a speed of the second drive shaft (9) can be detected via the second measuring means (12). [8] Method for testing an electric drive machine (2) for a motor vehicle, wherein the electric drive machine (2) is connected via a first drive shaft (5) to a first gearbox (7) and via a second drive shaft (9) to a second gearbox (11), wherein the first gearbox (7) is connected via a first output shaft (14) of a first electric load machine (16) and the second gearbox (11) is connected via a second output shaft (18) to a second electric load machine (20), and wherein the drive machine (2) and the first and second load machines (16, 20) are identical in construction and are connected to a power supply (23), wherein the first and second load machines (16, 20) are operated separately as generators and either the same load torque or a different load torque is generated via the first and second load machines (16, 20). [9] Method according to claim 8, characterized by, that both load machines (16, 20) are operated both as generators to generate a load moment and as motors to generate a torque, and the drive machine is operated as a generator. [10] Method according to claim 8 or 9, characterized by , that identical or different machines are used as the drive machine and as the load machine.

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