Test device for measuring torques, and test system for testing vehicle axles

Abstract

Test devices for measuring torques, comprising an input shaft (20), an output shaft (26), a clutch (24) by means of which the rotation of the input shaft (20) can be transmitted to the output shaft (26), and a torque sensor (22) by means of which a torque transmitted from the input shaft (20) to the output shaft (26) can be measured, are known. According to the invention, the input shaft (20) is in the form of a hollow shaft through which the output shaft (26) extends from the clutch (24) to the opposite output side (28) of the output shaft (26). A test system having a test device (18) of this type is also proposed. By means of these test devices and assciated test systems, a small angular offset and a small radial offset can be compensated and the cantilever load on the clutch can be reduced because the lengths of the shafts can be reduced since they no longer have to project beyond the region of the wheel mounts of the vehicle axles.

Description

[0001] Test device for measuring torques and test system for testing vehicle axles

[0002] The invention relates to a test device for measuring torques with a drive shaft, an output shaft, a coupling via which the rotation of the drive shaft can be transmitted to the output shaft, and a torque sensor via which a torque transmitted from the drive shaft to the output shaft can be measured, as well as a test system for testing vehicle axles with a drive dynamometer, a vehicle axle to be tested, and two load-generating dynamometers connected to the two axial ends of the vehicle axle.

[0003] Such test devices and systems are known and can be used, for example, to test drive axles of electrically powered vehicles, as well as in other test scenarios. The drive shaft, usually driven by an electric motor or drive dynamometer, transmits its torque to the output shaft via the clutch. Various torque sensors can be used to measure the drive torque. When measuring torque and load on a vehicle's drive components, torque is applied to the drive axle via the drive motor, while two load-generating dynamometers simulate driving resistance.

[0004] The problem with these test fixtures and systems is their increased space requirements and / or the limited accessibility of the axle drive. For example, in electrically driven vehicle axles, the driving electric motor is typically positioned parallel to the drive axle. If the drive axle is to be tested without the electric motor, there is often insufficient space to connect a drive dynamometer and a torque sensor. Furthermore, it is very difficult to prevent even a slight angular or axial misalignment between the shaft driven by the drive dynamometer and the input shaft of the intermediate gearbox located in front of the drive axle. This would require highly precise alignment, which is extremely complex and costly.For testing purposes, it would therefore be necessary, on the one hand, to install a compensating clutch between the driven shaft and the input shaft, and on the other hand, to make the driven shaft long enough to extend into the installation space beyond the wheel hubs, brake discs, and dynamometer connected to the drive axle. However, this has the disadvantage that heavy clutches must be used, resulting in a high load on the bearings of the test bench gearbox.

[0005] The challenge therefore lies in providing a test fixture and test system for testing vehicle axles, particularly for electric vehicle axles, that can compensate for small radial or angular axle misalignments while minimizing the force loads, even for axle-parallel drives. Accordingly, the required installation space should also be kept to a minimum.

[0006] This problem is solved by a test device with the features of main claim 1 and a test system for testing vehicle axles with the features of main claim 1.

[0007] The test device according to the invention for measuring torques has a drive shaft via which an output shaft is driven, at least indirectly. This is achieved via a coupling, through which the rotation of the drive shaft is transmitted to the output shaft. Furthermore, the test device has a torque sensor via which a torque transmitted from the drive shaft to the output shaft can be measured. The drive shaft is designed as a hollow shaft through which the output shaft projects from the coupling to the opposite output side of the output shaft. A radial gap exists between the drive shaft and the output shaft along its entire length, which compensates for any tilting, i.e., a slight angular misalignment or axial misalignment between the two shafts.This arrangement of the output shaft within the hollow input shaft significantly reduces the required space and the load-bearing capacity, as the shorter shaft length allows for the use of a smaller, lighter coupling. Nevertheless, the coupling can compensate for axial and angular misalignment. This also enables the use of smaller bearings due to their reduced weight, allowing for a significantly smaller overall test setup or making it better suited for testing at very high speeds.

[0008] The test system according to the invention for testing vehicle axles has a drive dynamometer via which a vehicle axle to be tested can be driven at least indirectly.

[0009] A load-generating dynamometer is connected to each of the two axial ends. According to the invention, the drive dynamometer is connected to the vehicle axle via a test device. The test device, in turn, consists of a drive shaft, which is designed as a hollow shaft, and an output shaft connected to the drive shaft in a torque-transmitting manner. The output shaft is connected to the drive shaft via a coupling and extends through the hollow shaft from the coupling to the opposite output side. Additionally, a torque sensor is provided, which measures the torque transmitted from the drive shaft to the output shaft. This test device is located between the drive dynamometer and the vehicle axle under test and thus transmits the torque of the drive dynamometer to the vehicle axle, which is at least indirectly connected to the output side of the output shaft of the test device.Accordingly, the torque transmitted to the vehicle axle can be measured via the torque sensor. The two load dynamometers generate the force opposing the drive. This allows for the simulation of various load conditions acting on the vehicle axle. Thanks to the arrangement according to the invention, it is possible to position the drive dynamometer close to the vehicle axle. Here, too, small couplings can be used due to the short lever arms and wavelengths and the low force loads. However, larger couplings could also be used. Nevertheless, small existing axle or angular misalignments can be compensated for, thus reducing setup times. Accordingly, electrically driven axles can also be tested, where the electric motor is arranged parallel to the axle in the immediate vicinity of the vehicle axle under test during operation.

[0010] In a preferred embodiment of the test device, the torque sensor is designed as a hollow torque measuring shaft, via which the drive shaft is connected to the coupling. This simplifies the mounting of the torque sensor and prevents the need for additional shaft sections between the individual components, thereby reducing the overall length and thus the length of the existing lever arms. It also minimizes the weight acting on the bearings.

[0011] The output shaft preferably protrudes through the hollow torque measuring shaft, resulting in a particularly compact design.

[0012] In a further embodiment, the hollow torque measuring shaft has a first flange at its first axial end, which is connected to a flange of the drive shaft. This direct connection again minimizes the length of the overall apparatus and thus the forces acting on the bearings.

[0013] It is particularly preferred if the hollow torque measuring shaft also has a second flange at its opposite axial end, which is connected to a flange of the coupling. The connection between the torque measuring shaft, the coupling, and the drive shaft is thus achieved without any further intermediate components, thereby reducing the axial length and simplifying assembly. A test bench gearbox output gear is preferably mounted non-rotatably on the drive shaft, through which the torque can be transmitted to the drive shaft. The drive shaft is thus part of the test bench gearbox and is driven directly by it.

[0014] Furthermore, it is advantageous if the clutch is a multi-plate clutch. This allows for reliable torque transmission and simultaneously compensates for both slight angular misalignment and a lack of coaxiality between the input and output shafts up to a certain degree.

[0015] In a further development, the multi-plate clutch has a splined connection, which prevents slippage of the clutch or the output shaft to the clutch output member while simultaneously compensating for any angular misalignment.

[0016] Furthermore, the hollow drive shaft is supported on both sides within a housing by a rolling or sliding bearing. These bearings exhibit very low frictional torque, even during start-up, and very low wear, ensuring reliable torque transmission.

[0017] The bearings in the housing are advantageously sealed on both sides by a labyrinth seal, which provides a low-wear seal for the rolling or sliding bearings without abrasion and therefore without friction losses, and enables high speeds.

[0018] In a further embodiment of the test system, the axis of rotation of the drive dynamometer is arranged perpendicular to the vehicle axis. This arrangement allows the drive dynamometer to be positioned on the test bench without causing space constraints in the area of ​​the wheel hubs and brake discs on the drive axle. In another preferred embodiment, the test bench gearbox is designed as a bevel gear connected to the drive dynamometer, with its output gear fixed to the drive shaft of the test device. This easily enables the drive dynamometer to be positioned perpendicular to the vehicle axis, while still requiring minimal installation space.

[0019] Preferably, the output side of the test device's output shaft is connected to a drive axle, which is connected to the vehicle axle via an intermediate gearbox. The intermediate gearbox is the transmission already present in the vehicle, which is typically located between the vehicle's drive motor and the drive axle and, in electrically powered vehicles, is aligned coaxially with the electric motor and the vehicle axle. This direct connection eliminates the need for additional intermediate components, resulting in a short setup time.

[0020] Furthermore, it is advantageous if the output shaft of the test device is connected to the drive axle in a rotationally fixed manner by a positive fit. The form of this positive fit can be specified by the customer and enables the transmission of the drive torque from the test bench gearbox to the vehicle axle.

[0021] Preferably, the output shaft is supported exclusively by the splined connection of the multi-plate clutch and the rotationally fixed, positive-locking connection with the drive shaft. Since additional bearings are unnecessary, angular and radial shaft misalignments can be compensated for.

[0022] In a further embodiment of the invention, the drive axle is supported by an intermediate bearing unit attached to the intermediate gearbox connected to the vehicle axle. Accordingly, the output shaft is indirectly supported by the bearing unit of the drive axle, achieving frictionless torque transmission despite potential angular misalignment. This creates a test device for measuring torques and a test system for testing vehicle axles, which, within a compact installation space, allows the connection of the test bench gearbox and the drive dynamometer even to vehicle axles that have an intermediate gearbox located directly on the axle and are intended to be operated without the axle's drive motor. These test systems can be used for various test scenarios, such as performance tests, brake tests, or axle tests.A slight angular or axial misalignment between the vehicle transmission's drive shaft and the test bench transmission is reliably compensated for via the output shaft and its connection to the drive shaft by means of the multi-plate clutch and the freely suspended output shaft. Furthermore, the design addresses the space constraints in the area of ​​the brakes and wheel suspensions on the vehicle axle, as the drive dynamometer can be positioned perpendicular to the vehicle axis.

[0023] An embodiment of a test device according to the invention for measuring torques and a test system for testing vehicle axles is shown in the figures and is described below by way of example.

[0024] Figure 1 shows a schematic representation of a test system according to the invention in a top view.

[0025] Figure 2 shows a perspective side view of a section of a test device according to the invention.

[0026] Figure 3 shows a side view of the test device according to the invention from Figure 2 in a cutaway view.

[0027] The test system shown in Figure 1 consists of a drive dynamometer 10, which is connected via a disc coupling 12 to an input shaft 14 of a test bench gearbox 16, which is designed as a bevel gear. The test bench gearbox 16 is part of a test device 18 according to the invention and drives a drive shaft 20, which is designed as a hollow shaft.

[0028] The drive shaft 20 is connected via a torque sensor 22 to a clutch 24, which is designed as a multi-plate clutch 25, and via which a rotary connection to an output shaft 26 is established, which extends through the drive shaft 20, designed as a hollow shaft, to the opposite side through the test bench gearbox 1 6.

[0029] The output shaft 26 is connected on this output side 28, opposite the clutch 24, to a drive axle 30 via a rotationally fixed positive connection. The drive axle 30 is supported in an intermediate bearing unit 31. This drive axle 30 is connected to an intermediate gearbox 32, which drives a vehicle axle 34 to be tested. This axle can also incorporate the vehicle's wheel hubs and brakes and is connected at both its axial ends 36 to a load-generating dynamometer 38. Accordingly, various load conditions acting on the vehicle axle 34 can be generated, simulating, for example, the rolling resistance of the vehicle wheels.

[0030] Various tests of the vehicle axle 34 can therefore be carried out with this test system, in which a defined torque, measurable via the torque sensor 22, is applied.

[0031] The test device 1 8 according to the invention is shown in Figures 2 and 3. It has a housing 40 in which the test bench gearbox is arranged, the output gear 42 of which can be seen in Figure 3, and which is rigidly connected to the drive shaft 26, which is designed as a hollow shaft, so that the rotation of the drive dynamometer 1 0 is transmitted to the drive shaft 20 via the test bench gearbox 16. By choosing the test bench gearbox 16 as a right-angle gearbox, an axis of rotation 44 of the drive dynamometer 1 0 is perpendicular to the drive shaft 20 and thus also to the vehicle axis 34.

[0032] The drive shaft 20 is supported in the housing 40 by two rolling bearings 46, these two rolling bearings 46 being sealed to the outside by two labyrinth seals 48, which are attached to the housing 40 and are in turn each covered to the outside by a cover plate 50, in which holes are formed through which screws 52 are inserted, via which the cover plates 50 and the labyrinth seals 48 are screwed to the housing 40.

[0033] The drive shaft 20 has a flange 54 at each of its axial ends, which in this case is manufactured separately and attached to the hollow shaft, for example, by a press fit. On the side facing the coupling, this flange 54 of the drive shaft 20 is fastened by screws 52 to a first flange 56 on a first axial end 58 of a torque measuring shaft 60, which serves as part of the torque sensor 22. This torque measuring shaft 60 is also designed as a hollow shaft and has a second flange 64 at its second axial end 62, which in turn is connected by screws 52 to a flange 66 of the coupling 24, which is attached to a first coupling disc 68 or manufactured as an integral part of it.Between this first clutch disc 68 and a second clutch disc 70, which limits the clutch 24 on the opposite axial side, lamellar packs 72 are arranged, via which the torque is transmitted from the first clutch disc 68 to the second clutch disc 70. The lamellar packs 72 can compensate for a small angular misalignment or a small radial misalignment in a known manner.

[0034] The second clutch disc 70 has a splined connection 74, via which a torque-transmitting connection to the output shaft 26 is established. The output shaft 26 has a radial extension 76 at this axial end. On the opposite outer side, an inner through-hole 80 of the clutch disc 70 has an extension 82 against which a cover plate 84 is pressed by screwing it into a corresponding bore 86 of the output shaft 26. This also establishes the axial position of the second clutch disc 70 relative to the output shaft 26. This connection is secured by a retaining ring 88 in a groove of the clutch disc 70.

[0035] The output shaft 26 extends from this end pointing towards the coupling 24 through the hollow torque measuring shaft 60 and the hollow drive shaft 20 to its output side 28, where it is provided with a customer-specific connection 88, which is in particular positive-locking and in the present case is designed as an internal toothing, so that the drive shaft 30 to be connected is provided with a corresponding connection, which in the present case is formed by a corresponding external toothing.

[0036] By positioning the output shaft within the input shaft, the axial installation space of the test device parallel to the vehicle axle is significantly reduced, so that the available installation space is located within the two wheel hubs and brakes of the vehicle axle. This shortening of the shafts results in a considerably lower shear load on the coupling, which can also compensate for a small angular or radial misalignment of the output shaft relative to the input shaft. A separate bearing for the output shaft can and should therefore be completely omitted. Furthermore, the use of the angle gearbox also provides sufficient installation space for the drive dynamometer.

Claims

PATENT CLAIMS 1. Test device for measuring torques comprising a drive shaft (20), an output shaft (26), a coupling (24) via which the rotation of the drive shaft (20) can be transmitted to the output shaft (26), a torque sensor (22) via which a torque transmitted from the drive shaft (20) to the output shaft (26) can be measured, characterized in that the drive shaft (20) is designed as a hollow shaft through which the output shaft (26) projects from the coupling (24) to the opposite output side (28) of the output shaft (26).

2. Test device for measuring torques according to claim 1, characterized in that the torque sensor (22) is designed as a hollow torque measuring shaft (60) via which the drive shaft (20) is connected to the coupling (24).

3. Test device for measuring torques according to claim 2, characterized in that the output shaft (26) projects through the hollow torque measuring shaft (60).

4. Test device for measuring torques according to one of claims 2 or 3, characterized in that the hollow torque measuring shaft (60) has a first flange (56) at its first axial end (58) which is connected to a flange (54) of the drive shaft (20).

5. Test device for measuring torques according to one of claims 2 to 4, characterized in that the hollow torque measuring shaft (60) has a second flange (64) at its opposite second axial end (62) which is connected to a flange (66) of the coupling (24).

6. Test device for measuring torques according to one of the preceding claims, characterized in that an output gear (42) of a test bench gearbox (16) is arranged non-rotatably on the drive shaft (20), via which the torque can be introduced into the drive shaft (20).

7. Test device for measuring torques according to one of the preceding claims, characterized in that the clutch (24) is a multi-plate clutch (25).

8. Test device for measuring torques according to claim 7, characterized in that the lamellar coupling (25) has a plug-in toothing (74).

9. Test device for measuring torques according to one of the preceding claims, characterized in that the drive shaft (20) designed as a hollow shaft is supported on both sides in a housing (40) by a rolling or sliding bearing (46).

10. Test device for measuring torques according to claim 9, characterized in that the rolling or sliding bearings (46) in the housing (40) are sealed on both sides by a labyrinth seal (48). 1 1 . Test system for testing vehicle axles with a drive dynamometer (1 0 ), a vehicle axle (34) to be tested, two load-generating dynamometers (38) connected to the two axial ends (36) of the vehicle axle (34), characterized in that the drive dynamometer (1 0 ) is connected to the vehicle axle (34) via a test device (1 8) according to one of the preceding claims. 1 2. Test system for testing vehicle axles according to claim 1 1 , characterized in that a rotation axis (44) of the drive dynamometer (1 0) is arranged perpendicular to the vehicle axis (34). 1 3. Test system for testing vehicle axles according to claim 1 1 or 1 2, characterized in that the test stand transmission (1 6) is designed as an angle transmission which is connected to the drive dynamometer (10) and whose output gear (42) is arranged non-rotatably on the drive shaft (20) of the test device (1 8).

14. Test system for testing vehicle axles according to one of claims 1 1 to 1 3, characterized in that the output side (28) of the output shaft (26) of the test device (1 8) is connected to a drive axle (30) which is connected to the vehicle axle (34) via an intermediate gear (32). 1 5. Test system for testing vehicle axles according to claim 14, characterized in that the output shaft (26) of the test device (1 8) is connected to the drive axle (30) in a rotationally fixed manner by positive locking.

16. Test system for testing vehicle axles according to one of claims 14 or 15, characterized in that the output shaft (26) is supported exclusively by the splined connection (74) of the multi-plate clutch (25) and the rotationally fixed positive locking connection with the drive axle (30). 1 7. Test system for testing vehicle axles according to one of claims 14 to 1 6, characterized in that the drive axle (30) is mounted via an intermediate bearing unit (31) which is attached to the intermediate gearbox (32) connected to the vehicle axle (34).

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