Drive unit for a drivetrain test stand for testing drivetrains of motor vehicles and drivetrain test stand

Abstract

The present invention relates to a drive unit (10) for a drivetrain test stand for testing drivetrains of motor vehicles. The drive unit (10) comprises a frame member (20), an electric motor (30) with a motor shaft, a clutch (40) and a driven shaft (50). The electric motor (30) is arranged in the frame member (20), the driven shaft (50) is rotatably held in a bearing of the frame member (20), and the motor shaft is non-rotatably connectable to the driven shaft (50) via the clutch (40). The drive unit (10) according to the invention is characterized in that it further comprises a brake (60), the first friction partner of which is radially outside (61) of the clutch (40) and the second friction partner of which is at least one brake pad (62, 63). The present invention further relates to a corresponding drivetrain test stand.

Description

[Technical field]

[0001] The invention relates to a drive unit for a drivetrain test stand for testing drivetrains of motor vehicles according to the preamble of claim 1 and to a corresponding drivetrain test stand. [Background technology]

[0002] Transmission test stands and drivetrain test stands for testing motor vehicle transmissions or entire motor vehicle drivetrains are known from the prior art. Test stands of this kind are used, for example, for early detection of malfunctions in the drivetrain with a series of load tests. Typical malfunctions are caused, for example, by parts with play that can deflect or vibrate. These parts are, for example, gears, synchronizer rings, synchronizer bodies, disks of multi-plate clutches, shafts, etc. Within the scope of such functional tests, the acoustic behavior and shift quality are usually also tested. However, test stands of this kind are also used in the development and continuous improvement of motor vehicle drivetrains.

[0003] In this context, DE 4328537 C2 describes a transmission test stand with a first servo motor serving as a drive motor and a second servo motor serving as a brake motor. The drive motor is connected via a clutch to the drive shaft of the transmission of the vehicle to be tested and is controlled in terms of its rotational speed via a PC, in particular so that any rotational speed curve can be simulated. The brake motor is connected via another further clutch to the output shaft of the transmission of the vehicle to be tested. The rotational speed of the brake motor is also controlled via a PC. The rotational speed curve simulated by the PC is the rotational speed curve measured in a real road test. The transmission of the vehicle can thus be tested in accordance with DE 4328537 C2 before it is installed in the vehicle.

[0004] Furthermore, from DE 10 2016 224 138 A1 a drive unit of a drivetrain test stand with an electric motor is known. The electric motor comprises a housing with a front yoke and a rear yoke. The yoke arms each extend radially laterally from the electric motor. The front yoke is arranged in the region of the bearing in front of the motor shaft, and the rear yoke is arranged in the region of the bearing in rear of the motor shaft. This makes it possible to ensure a relatively high stiffness and vibration damping. As a result, the drive unit can provide high rotational speeds of more than 25,000 rpm. This drive unit is therefore particularly suitable for testing electric drivetrains.

[0005] Furthermore, in the described drive test stand, it is known that the brake disk can be arranged on the motor shaft of the drive motor or on a suitable position on the drive train, and its rotation can be blocked by the brake caliper, which increases the required axial space and reduces the torsional stiffness, which can result in undesirable vibrations.

[0006] Finally, DE 102020203071 A1 discloses a drive test stand for a drive of an electric vehicle. The drive test stand comprises a test stand electric motor. The test stand electric motor can be coupled with its motor shaft directly or via a drive train to an output shaft of the drive of the electric vehicle to be tested. A torque sensor is arranged on the motor shaft or on the drive train. The motor shaft or the drive train can be locked against rotation by means of a locking device. Either the motor shaft of the test stand electric motor or the drive train, which is coaxially connected with the motor shaft of the test stand electric motor, is provided with a clamping device. The clamping device has a radial clamping surface which extends radially concentrically with respect to the rotation axis of the motor shaft or the drive train. The radial clamping surface is surrounded by a clamping ring. In the release position, an annular gap exists between the clamping ring and the radial clamping surface. In the locking position, on the other hand, the clamping ring clamps the radial clamping surface against rotation.

[0007] However, the known automotive test benches are disadvantageous in that they have to be time-consuming and manually adapted when, instead of a drivetrain test at rpm, a so-called Stall Torque test of the drivetrain is to be carried out, in which only a maximum torque is applied without rpm, or when there is only a relatively small air gap in the release position, apparently less than 1 mm, which can result in a negative effect on the measurement at rpm. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] DE4328537C2 [Patent Document 2] DE102016224138A1 [Patent Document 3] DE102020203071A1 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE DISCLOSURE The object of the invention is to propose an improved drive unit for a drive train test stand for testing drive trains of motor vehicles. [Means for solving the problem]

[0010] This problem is solved according to the invention by a drive unit for a drivetrain test stand for testing drivetrains of motor vehicles according to claim 1. Advantageous embodiments emerge from the dependent claims.

[0011] The invention relates to a drive unit for a drivetrain test stand for testing drivetrains of motor vehicles. The drive unit comprises a frame member, an electric motor with a motor shaft, a clutch and a driven shaft. The electric motor is arranged in the frame member. The driven shaft is rotatably held in a bearing of the frame member. The motor shaft is non-rotatably connectable to the driven shaft via the clutch. The drive unit according to the invention is characterized in that the driven unit further comprises a brake, the first friction partner of which is radially outside the clutch and the second friction partner of which is at least one brake pad.

[0012] The invention therefore describes a drive unit designed to be used as a component of a drivetrain test stand, i.e. as a drive unit thereof. The drivetrain test stand is designed to test a motor vehicle drivetrain. The drivetrain test stand not only tests the entire motor vehicle drivetrain, but also individual or multiple components of the motor vehicle drivetrain, in particular those that are combined into modules. The motor vehicle drivetrain or components of the motor vehicle drivetrain therefore constitute the test objects to be tested.

[0013] The vehicle drivetrain may be an electric vehicle drivetrain as well as a conventional vehicle drivetrain.

[0014] In particular, the test object is an electric drive motor of the drive train of an electric vehicle or an electric motor-driven axle module comprising an electric drive motor, a transmission and two wheel shafts. In the latter case, two drive units according to the invention can be used to provide a drive unit for each of the two wheel shafts.

[0015] The drive unit firstly comprises a frame member which advantageously consists of a particularly rigid material, such as a mineral casting, in particular with a metal skeleton structure.

[0016] The frame member preferably comprises a receiving portion for the electric motor, so that the electric motor can be arranged in a particularly firm and rigid receiving portion in the frame member, for example via a relatively large contact surface of the frame member for the electric motor.

[0017] Furthermore, the frame member comprises a bearing for the driven shaft, and in particular also for the motor shaft, so that both the driven shaft, and in particular the motor shaft, are held in a low-vibration and rigid manner by the frame member.

[0018] The electric motor supplies mechanical power in the form of torque and rotational speed for testing the test object at rotational speed, the electric motor in this case being of relatively compact construction and having a wide speed range, in particular in comparison with an internal combustion engine, and advantageously with a maximum torque over a wide speed range.

[0019] Advantageously, an inverter is assigned to the electric motor, which is for example designed as a three-phase inverter.

[0020] With regard to the electric motor, it comprises a motor housing which encloses the electric motor and is designed, for example, in a cylindrical shape.

[0021] The motor housing may also include a water cooling system.

[0022] The electric motor can then output mechanical power in the form of rotational speed and torque via a motor shaft.

[0023] The motor shaft can be non-rotatably connected to the driven shaft via a clutch.

[0024] The clutch correspondingly also allows the motor shaft to be decoupled from the driven shaft, so that, for example, the electric motor or the driven shaft, respectively, can be individually removed from the frame member and replaced.

[0025] The driven shaft is provided with a connection, for example preferably in the form of a flange or a positively locking clutch, at its axial end facing the test object opposite the electric motor, in order to create a non-rotatable connection to the test object.

[0026] According to the invention, the driven unit further comprises a brake, the first friction partner of which is the radially outer side of the clutch and the second friction partner of which is at least one brake pad. This provides the advantage that a pure torque measurement without rotational speed can be carried out without setup efforts and associated setup times, during which the drive unit is naturally not available for testing the test object. Furthermore, it has the advantage that the at least one brake pad can be moved away from the outer side of the clutch in the released state to such an extent that it does not affect the rotational behavior during measurements at rotational speed. For example, the at least one brake pad can be brought into and out of contact with the outer side of the clutch via a corresponding mechanism.

[0027] According to a preferred embodiment of the invention, the brake comprises two second friction partners, which are held floating on the outside of the clutch via a brake frame. This allows the outside of the clutch to be clamped, for example, from two opposite sides. This increases the applicable braking force. Since the two second friction partners are supported floating, furthermore, no complex adjustment or positioning of the second friction partners is required in the applied or released state relative to the first friction partner.

[0028] The two second friction partners are preferably two brake pads.

[0029] According to a particularly preferred embodiment of the invention, the brake frame is arranged floatingly on the bearing plate of the electric motor. Since the brake frame is held floatingly, the second friction partners do not each have to be arranged floatingly on the brake frame individually, but rather the second friction partners can be arranged floatingly as well via the floating-supported brake frame. The brake frame is advantageously a metal frame with a corresponding mechanism that allows simultaneous actuation of the two second friction partners.

[0030] Since the brake frame is arranged on the bearing plate of the electric motor, it is on the one hand firmly and stably held on the electric motor and, on the other hand, is already located in the area of ​​the motor shaft and thus also in close proximity to the clutch, the outer side of which constitutes the first friction partner.

[0031] According to a further particularly preferred embodiment of the invention, the brake frame at least partially surrounds the clutch in the radial direction. This means that the brake frame is arranged radially around the clutch and does not require any particular axial installation space. Axial elongation is usually disadvantageous, since it introduces undesirable elasticity into the drive train, which elasticity leads to vibrations that in turn can have a negative effect on the measurements and tests carried out. In addition, the brake frame does not rotate with the clutch, so that no imbalances or vibrations are caused by the mass of the brake frame and the second friction partner.

[0032] According to a further preferred embodiment of the invention, the brake can be hydraulically actuated. For example, the brake can comprise for this purpose a hydraulic reservoir, a hydraulic cylinder and a piston arranged in the hydraulic cylinder. The piston activates the brake when a corresponding hydraulic pressure is applied in the hydraulic cylinder. Within the scope of actuation, the brake pads are guided and pressed against the outer periphery of the clutch, for example along a linear guide. As a result, a corresponding strong static friction is generated in order to establish a non-rotatable connection.

[0033] According to a further preferred embodiment of the invention, the drive unit further comprises a torque measuring flange, which is arranged in the drive train, preferably in the region between the clutch and the test object. All transmitted torques are normally conducted via the torque measuring flange. Thus, the torque acting between the clutch or the electric motor and the test object can be reliably measured at any time.

[0034] The rotational speed of the electric motor is preferably detected via its drive electronics, in particular a three-phase inverter, so that, for example, the power can be determined from the rotational speed and the torque.

[0035] According to a further preferred embodiment of the invention, the clutch is designed as a flange connection. The flange connection allows a reliable transmission of high and very high torques. In addition, the flange connection is relatively easy to dismantle. As a result, the driven shaft and the electric motor can be separated from each other and, for example, replaced.

[0036] According to a further preferred embodiment of the invention, the electric motor is designed as a three-phase synchronous motor, which is usually very well suited for operation at high rotational speeds, such as those provided in the drive train of electric vehicles.

[0037] The invention further relates to a drive train test stand comprising at least one drive unit according to the invention, whereby the advantages already mentioned in connection with the drive unit according to the invention are also provided for the drive train test stand according to the invention.

[0038] The drive train test stand preferably comprises a drive unit for each driven shaft of the test object. Furthermore, the drive train test stand preferably also comprises a test object holder on which the drive train test stand can be arranged in as rigid and stiff a manner as possible.

[0039] In the following, the invention is explained exemplarily using the embodiments shown in the drawings. [Brief description of the drawings]

[0040] [Figure 1] 3A to 3C are exemplary schematic diagrams of possible designs of a drive unit according to the invention; [Diagram 2] FIG. 2 is a cross-sectional view of the drive unit of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] Identical objects, functional units and comparable components are designated with the same reference symbols throughout the figures. These objects, functional units and comparable components are identical with respect to their technical characteristics, unless otherwise stated explicitly or implicitly in the description.

[0042] 1 shows diagrammatically a possible design of a drive unit 10 according to the invention. The drive unit 10 comprises a frame member 20, an electric motor 30 (hidden in FIG. 1), a clutch 40, a driven shaft 50 and a brake 60.

[0043] The frame member 20 is made, for example, of a mineral casting with a metal skeleton structure cast therein, which makes the frame member 20 relatively rigid and effectively prevents the occurrence of vibrations.

[0044] The electric motor 30 is, for example, designed as a three-phase synchronous motor 30 and is arranged between two lateral jaws of a frame member. The electric motor 30 is assigned a terminal box 31 which receives an electric cable for supplying the electric motor 30 with power. An inverter for controlling the electric motor 30 is, for example, arranged in a separate control cabinet, which is not shown in FIG.

[0045] An output shaft (hidden in FIG. 1) of the electric motor 30 is connected via a clutch 40 to a driven shaft 50. The driven shaft 50 is rotatably supported in the frame member 20 and is provided with a flange connection 51 at its axial end facing a test object (not shown in FIG. 1).

[0046] Furthermore, the drive unit 10 comprises a torque measuring flange 41 drivingly arranged between the clutch 40 and the driven shaft 50. Thereby, all torques transmitted from the driven shaft 50 to the clutch 40 and vice versa are transmitted via the torque measuring flange 41. These torques can therefore be detected by the torque measuring flange 41.

[0047] The brake 60 comprises a first friction partner 61 constituted by the radial outside 62 of the clutch 40. Furthermore, the brake 60 comprises two second friction partners 62,63 designed for example as so-called brake pads 62,63.

[0048] The brake pads 62, 63 are arranged in a brake frame 64 in a manner operable towards the clutch 40. With respect to the brake frame 64, the brake frame 64 is arranged radially around the clutch 40 and is floatingly mounted on a bearing plate of the electric motor 30.

[0049] The brake 60 can be hydraulically actuated, for example, via a cylinder-piston unit (not shown in FIG. 1 ), so that, when the brake 60 is in an actuated state, the brake pads 62, 63 are pressed against the radially outer side of the clutch 40, holding the clutch 40 immovable through static friction.

[0050] Figure 2 shows in cross section the drive unit 10 of Figure 1 already described. The components of the drive unit already described, namely the frame member 20, the electric motor 30, the clutch 40, the driven shaft 50 and the brake 60, are again visible.

[0051] The terminal box 31 is arranged on the electric motor 30. The output shaft 32 of the electric motor 30 is connected to a driven shaft 50 via a clutch 40. The driven shaft 50 is rotatably supported in the frame member 20 via a bearing 21 and is provided with a flange connection 51 at its axial end facing a test object (not shown in FIG. 1 ).

[0052] The torque measuring flange 41 is disposed between the clutch 40 and the driven shaft 50 .

[0053] Furthermore, a brake frame 64 can be seen which radially surrounds the clutch 40 and is arranged floating on the bearing plate of the electric motor. [Explanation of symbols]

[0054] 10 Drive unit 20 Frame members 21 Bearings 30 Electric motor, three-phase synchronous motor 31 Terminal box 32 Output shaft 40 Clutch 41 Torque measurement flange 50 Driven shaft 51 Flange connection 60 Brake 61 First friction partner, radially outside of the clutch 62 Second friction partner, brake pad 63 Second friction partner, brake pad 64 Brake frame

Claims

1. A drive unit (10) for a drivetrain test stand for testing drivetrains of motor vehicles, comprising: a frame member (20); an electric motor (30) having a motor shaft; a clutch (40); and a driven shaft (50), the electric motor (30) being arranged in the frame member (20), the driven shaft (50) being rotatably held in a bearing of the frame member (20), and the motor shaft being non-rotatably connectable to the driven shaft (50) via the clutch (40), The drive unit (10) further comprises a brake (60), the first friction partner of which is radially outside (61) of the clutch (40) and the second friction partner of which is at least one brake pad (62, 63).

2. A drive unit (10) according to claim 1, The drive unit (10), characterized in that the brake comprises two second friction partners (62, 63), the two second friction partners (62, 63) being held in a floating state on the outer side (61) of the clutch (40) via a brake frame (64).

3. A drive unit (10) according to claim 2, A drive unit (10), characterized in that the brake frame (64) is arranged in a floating manner on a bearing plate of the electric motor (30).

4. A drive unit (10) according to claim 2 or 3, A drive unit (10), characterized in that the brake frame (64) at least partially radially surrounds the clutch (40).

5. A drive unit (10) according to any one of claims 1 to 4, A drive unit (10), characterized in that said brake (60) is hydraulically actuable.

6. A drive unit (10) according to any one of claims 1 to 5, The drive unit (10), further comprising a torque measuring flange (41).

7. A drive unit (10) according to any one of claims 1 to 6, A drive unit (10), characterized in that the clutch (40) is designed as a flange connection.

8. A drive unit (10) according to any one of the preceding claims, A drive unit (10), characterized in that the electric motor (30) is designed as a three-phase synchronous motor (30).

9. A drivetrain test stand comprising at least one drive unit (10) according to any one of the preceding claims.

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