TEST BENCH FOR A MOTOR VEHICLE'S POWERTRAI

Description

[0001] The invention relates to a test bench for a powertrain of a motor vehicle according to the preamble of claim 1.

[0002] Transmission test benches or powertrain test benches for testing motor vehicle transmissions or complete motor vehicle powertrains are known from the prior art. Such test benches are typically used for quality control to detect malfunctions in powertrains at an early stage through a series of load tests. Typical malfunctions arise, for example, from components with play, such as gears, synchronizer rings, synchronizer bodies, multi-plate clutch discs, and shafts, which can be deflected and excited into vibrations. As part of such quality control, the acoustic behavior and shift quality are also usually tested. Furthermore, such test benches are also used in the development and continuous improvement of motor vehicle powertrains.

[0003] In this context, DE 43 28 537 C2 describes a transmission test bench 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 coupling to the drive shaft of a vehicle transmission under test and its speed is controlled, among other things, by a PC, so that any desired speed profile can be simulated. The brake motor is connected via another coupling to an output shaft of the vehicle transmission under test. The speed of the brake motor is also controlled by the PC. The speed profiles simulated by the PC are speed profiles measured in actual driving tests. Thus, according to DE 43 28 537 C2, the vehicle transmission can be tested before installation in a vehicle.

[0004] German patent DE 103 28 461 A1 discloses a vehicle test stand with a load machine for each driven wheel of a motor vehicle. The load machines are connected directly, for example via wheel bolts, or indirectly, for example via a belt drive, to the rims of the vehicle wheels, so that the load machines can both drive and brake the drive train. The vehicle test stand of DE 103 28 461 A1 further comprises a frame structure by which the motor vehicle and the load machines can be lifted and aligned relative to each other. During the test procedure, the motor vehicle is held completely by the frame structure, so that the vehicle wheels do not have contact with the ground.

[0005] From US patent 2020 / 284695 A1, a test specimen testing apparatus is known that tests a vehicle or a vehicle part. The test specimen testing apparatus includes a loading device whose rotating shaft is connected to a rotating shaft of the test specimen, rotates at the same speed, and imparts a driving resistance to the rotating shaft of the test specimen. The test specimen testing apparatus further includes a memory that stores tire diameter data indicating a relationship between a driving condition of the test specimen and a tire diameter, as well as a load control unit that calculates a tire diameter corresponding to a driving condition of the test specimen from the tire diameter data and controls the loading device using a driving resistance derived from the calculated tire diameter.

[0006] However, the known vehicle test benches have disadvantages in that they require a comparatively large setup area, especially when they are intended for testing a powertrain already installed in the vehicle, and above all depend on a complex and expensive mechanical support structure.

[0007] It is an object of the present invention to propose an improved test bench for a powertrain of a motor vehicle.

[0008] This problem is solved according to the invention by the test bench for a powertrain of a motor vehicle according to claim 1. Advantageous embodiments are described in the dependent claims.

[0009] The invention relates to a test rig for a motor vehicle's powertrain, comprising at least one load motor with a motor housing and a motor shaft, at least one torque sensor, and at least one shutdown module, wherein the motor shaft is configured to be drivenly connected to a hub of the motor vehicle, and wherein the torque sensor is configured to detect a torque generated by the motor. The test rig according to the invention is characterized in that the at least one torque sensor is arranged on the motor housing in such a way that it rotationally blocks a rotational movement of the motor housing relative to a surface and supports the torque against the surface via the motor housing.

[0010] The invention describes a test bench suitable for testing the powertrain of a motor vehicle. The motor vehicle can be either electrically powered or conventionally powered.

[0011] The test bench includes at least one load motor. Advantageously, this load motor is an electric motor. Electric motors are comparatively compact, have a wide speed range, especially compared to combustion engines, and advantageously exhibit maximum torque over a broad speed range. Only when the so-called "peak point" is reached in the comparatively high speed range does the torque decrease inversely proportional to the further increase in speed due to the increasing field weakening.

[0012] Preferably, the at least one load motor is designed as a permanent magnet synchronous motor. It is particularly advantageous for the synchronous motor to comprise a comparatively large number of magnetic pole pairs, for example, twelve or more. Such synchronous motors are also known as synchro-torque motors. This offers the advantage that the load motor can be designed to be comparatively compact and axially short, which consequently also allows the load motor's center of gravity to be positioned very close to the vehicle's chassis.

[0013] It is advantageous to assign each load motor its own inverter. The inverter is, for example, a three-phase design.

[0014] The at least one load motor comprises a motor housing that encloses the load motor. The motor housing is, for example, cylindrical in shape.

[0015] The engine housing may, for example, have water cooling.

[0016] Finally, the at least one load motor also includes a motor shaft, which provides the torque and rotational speed generated by the load motor. The motor shaft can be non-rotatably connected to one of the wheel hubs of the vehicle, so that torque and rotational speed can be transmitted from the motor shaft to the hub. The torque and rotational speed together represent a mechanical power with which the drivetrain under test can be loaded. Thus, the torque and rotational speed constitute the load placed on the drivetrain during the test.

[0017] In the context of the invention, a drive connection is understood to be a mechanical connection for the transmission of mechanical power, wherein the torque and rotational speed can be converted during the transmission from the load motor to the hub. This means that the load motor, for example, provides a first rotational speed and a first torque, with the first rotational speed and the first torque representing the first power. During the transmission of the first power, the first torque can be converted to a second torque, and the first rotational speed can be converted to a second rotational speed. However, the first power remains unchanged by the transmission. Therefore, the definition that the motor shaft is drive-connected to the hub, or can be connected to it, does not stipulate that there must be a direct mechanical connection, and in particular, a non-rotatable connection, between the motor shaft and the hub.Rather, the driving connection can also include a gearbox or individual transmission stages or other intermediate elements.

[0018] Furthermore, the test bench includes at least one torque sensor, wherein the torque sensor is designed to detect a torque generated by the load motor.

[0019] The torque sensor preferably comprises one or more force-sensitive elements, in particular one or more strain gauges, which initially detect a force acting on the force-sensitive element or forces acting on the multiple force-sensitive elements. The acting torque can then be determined from the detected force(s) via the geometry of the torque sensor.

[0020] Preferably, the rotational speed of the load motor is also recorded, for example via its control electronics, in particular via its inverter. From the known rotational speed and torque, the power or load can then be determined.

[0021] The support module is advantageously mounted on the hub of the vehicle in place of, or like, a vehicle wheel. The vehicle under test rests on the ground via the support module located on the hub. The ground can have a particularly high coefficient of friction compared to the support module in order to enable the transmission of high torques from the load motor to the support module.

[0022] Furthermore, it may be provided that at least one support module can be connected to the substrate by a force-fit or form-fit connection. For example, the adhesion of the support module to the substrate can be further increased by clamping the support module over its running surface using a tension strap whose ends are firmly attached to the substrate. To improve the adhesion of the support module to the substrate even further, the support module can also be positioned on the substrate, for example, by means of a bolt that is located in the substrate and penetrates radially into the support module from the outside.

[0023] Preferably, the at least one shutdown module comprises a radial outer part and a radial middle part, wherein the middle part is rotatably held in the outer part and is designed to be rotationally fixed to an axial end of the motor housing. The at least one shutdown module is thus a two-part design, with the radial middle part of the shutdown module being rotatable relative to the radial outer part of the shutdown module. The load motor is held to the middle part of the shutdown module via its motor housing, for example, by means of a screw or flange connection. The radial outer part is therefore rotatable relative to the load motor.

[0024] In this case, the standby module is not mounted to the vehicle's hub like a wheel, but instead features a central opening through which the load motor's drive shaft can be directly connected to the hub, for example, via the wheel flange. This also means that the standby module is only indirectly connected to the hub via the load motor, since the load motor is connected to the central part of the standby module via its motor housing and to the vehicle's hub via its drive shaft.

[0025] Alternatively, and preferably, the parking module can, in addition to the radial outer part and the radial middle part, also have a central inner part, which in turn is rotatably held in the radial middle part. In this case, the parking module can be mounted to the hub of the vehicle in a rotationally fixed manner via the central inner part. Likewise, the motor shaft of the load motor can then also be arranged in a rotationally fixed manner on the central inner part, so that the motor shaft and the hub of the vehicle are in drive connection with each other via the central inner part.

[0026] It is particularly advantageous that the rotation of the central section relative to the outer section can be blocked. This blocking can be achieved, for example, by moving designated bolts or slides, or by positioning a clamping element, thus preventing any relative movement of the outer section to the central section. This offers the advantage that the vehicle can even move under its own power and can therefore be easily positioned and aligned for testing. For example, a lockable support module can be mounted on each wheel to be tested, and the vehicle can then be driven within the testing area, such as a large hall, from the point where the support module is mounted to the testing location.

[0027] According to the invention, the at least one torque sensor is arranged on the motor housing in such a way that it blocks any rotational movement of the motor housing relative to a surface and supports the torque against the surface via the motor housing. In other words, the load motor is supported against the surface via the torque sensor in such a way that it can transmit rotational speed and torque to the hub of the vehicle. The torque sensor can therefore be attached to both the motor housing and the surface. Thus, the load generated by the load motor can be transmitted in the direction of force flow into the hub of the vehicle and thus into the drivetrain, and against the direction of force flow, the load motor can support the load against the surface via the motor housing and the torque sensor.

[0028] Since the load motor and the radial central part of the shutdown module, which is connected to the load motor via its motor housing in a rotationally fixed manner, do not rotate during the test procedure, the advantage arises that the vehicle remains stationary on the ground during a test procedure, as only the motor shaft and the hub of the vehicle are rotatable during the test procedure.

[0029] Furthermore, this has the advantage that the torque sensor is not subjected to a rotational movement during the testing process, which could otherwise adversely affect the sensor's measured values ​​due to centrifugal forces resulting from the rotation.

[0030] Since at least one torque sensor is advantageously not located in the torque flow from the load motor to the hub, the mechanical connection from the load motor to the hub can be comparatively very short, which also improves the stiffness of the connection.

[0031] The invention thus describes a very compact test bench for testing the powertrain of a motor vehicle, in which the load motor can be directly connected to a hub of the vehicle without an intermediate shaft. This also offers the advantage that the required test space is comparatively much smaller than is usual in the prior art, and in particular, no bulky and expensive test rig or corresponding frame construction is required to hold and align the vehicle and the load motors. In particular, no complex and time-consuming alignment or adjustment of the powertrain or the vehicle to the test bench is necessary.A further significant advantage of the invention lies in the fact that the testing process using the test rig according to the invention leaves the chassis characteristics of the vehicle under test largely unaffected, since the vehicle is supported on the ground solely by its own chassis during the test. Thus, chassis-specific characteristics such as suspension behavior, steering behavior, and similar properties can be tested very realistically.

[0032] Preferably, the base is provided to be a device for holding the at least one load motor, which holds the at least one load motor, for example, at its axial ends in the area of ​​the motor shaft, so that the motor housing remains rotatable.

[0033] According to the invention, the at least one torque sensor is arranged in a strut, the strut being attached to the motor housing via a first articulated eye and to the substrate via a second articulated eye. The strut is preferably a metallic strut whose mechanical load-bearing capacity is adapted to the performance of the load motor, so that it can reliably support the torque applied by the load motor, whether under compression or tension. The use of articulated eyes for connecting the strut to the motor housing and the substrate offers the advantage that no lateral forces can adversely affect the torque measurement. By advantageously arranging the torque sensor within the force flow of the strut, it can thus reliably detect the full torque.

[0034] According to a further preferred embodiment of the invention, a torque sensor is arranged on each of two lateral sides of the motor housing. Thus, each of the two torque sensors is subjected to only half the torque, which can lead to improved measurement accuracy.

[0035] When the torque sensors are arranged on the lateral sides of the housing, it is advantageously taken into account that the torque detected by the torque sensors is recorded as a "thrust torque" on a first lateral side of the motor housing and as a "traction torque" on the second lateral side. Preferably, the magnitudes of the detected "thrust torques" and the detected "traction torques" are added to obtain the total torque, which corresponds to the total torque supplied by the load motor.

[0036] According to a further preferred embodiment of the invention, the test rig also includes a pneumatic tire arranged on a radial outer circumference of the at least one support module. In this case, the support behavior of the support module on the surface largely corresponds to the support behavior occurring during normal driving of the vehicle. This improves the quality of the test, as the behavior of the powertrain in the test situation is even closer to the behavior of the powertrain during regular driving of the vehicle.

[0037] Preferably, a pneumatic tire is arranged on the parking module, which is approved for road use of the motor vehicle.

[0038] According to an alternative preferred embodiment of the invention, the test rig further comprises a rubber coating arranged on a radial outer circumference of the at least one support module. The rubber coating also enables a comparatively realistic support of the support module on the surface, but unlike a pneumatic tire, it does not require the separate selection and mounting of a suitable pneumatic tire on the support module. Instead, the rubber coating can be permanently and securely attached to the support module.

[0039] According to a further preferred embodiment of the invention, the test rig further comprises at least one support ram, wherein the support ram is adjustable in three spatial directions and / or rotatable about an axis, and wherein the support ram is designed to support the support module and represent the ground surface. By appropriately actuating the support ram, for example along a vertical axis, uneven ground surfaces during a vehicle journey can thus be simulated. Likewise, virtually all other influences of a possible ground surface can be simulated via the support ram, particularly in conjunction with steering movements of steerable wheels of the vehicle. Since the support ram in this case also represents the ground surface to which the at least one torque sensor is advantageously connected, it preferably has a corresponding connection option, in particular for a swivel joint.

[0040] The invention is explained below by way of example with reference to embodiments shown in the figures.

[0041] They show: Fig. 1 shows, by way of example and schematically, a test bench known in the prior art for testing a powertrain of a motor vehicle, as well as the motor vehicle to be tested; Fig. 2 shows, by way of example and schematically, a possible embodiment of a test bench according to the invention for a powertrain of a motor vehicle, as well as the motor vehicle to be tested; Fig. 3 shows, by way of example and schematically, a possible embodiment of a test bench according to the invention in detail; Fig. 4 shows, by way of example and schematically, another possible embodiment of a test bench according to the invention; and Fig. 5 shows, by way of example and schematically, yet another possible embodiment of a test bench according to the invention.

[0042] Identical objects, functional units, and comparable components are designated across all figures using the same reference symbols. These objects, functional units, and comparable components are identical in their technical characteristics unless explicitly or implicitly stated otherwise in the description.

[0043] Fig. 1 Figure 10 shows, by way of example and schematically, a test rig 10 known in the prior art for testing the powertrain of a motor vehicle 20, as well as the motor vehicle 20 to be tested. The powertrain is already fully installed in the motor vehicle 20. The known test rig 10 comprises two load units 11, each connected via connecting shafts 12 to the hubs 21 of driven wheels of the motor vehicle 20. However, test rigs 10 of the same type with four load units 11 are also known, particularly for all-wheel-drive vehicles. The load units 11 each comprise a terminal box 14 arranged on the electric drive motor 13 for receiving the cables that supply the electric drive motor 13 with electrical energy. The drive motors 13 are each arranged on a frame 15, which is laterally adjustable to accommodate the track width of different vehicle types.The motor vehicle 20 is typically lifted onto the support elements 16 using a lifting device, such as a crane, and placed there. The support elements 16 each have a mounting bracket for attachment to the hubs of the vehicle's wheels. The design and thus the space requirement of the known test stand 10 are comparatively large. Since no wheels are mounted on the hubs 21 of the motor vehicle 20, the motor vehicle 20 cannot be moved into the test position in the test stand 10 either under its own power or by pushing.

[0044] Fig. 2 Figure 1 shows, by way of example and schematically, a possible embodiment of a test rig 100 according to the invention for a powertrain of a motor vehicle 20, as well as the motor vehicle 20 to be tested. As can be seen, the test rig 100 according to the invention comprises two load motors 110, which are mounted directly on the hubs 21 (not shown in Figure 1). Fig. 2 ) of the motor vehicle 20. This makes the test stand 100 according to the invention significantly more compact and cost-effective compared to known test stands 10. In particular, no complex alignment of load units 11 or load motors 110 relative to the motor vehicle 20 is required. Furthermore, the motor vehicle 20 can be moved to the required test position under its own power using the support modules 130. A further particular advantage is that the test stand 100 according to the invention, due to its design, does not require any space-consuming frame structures 15.

[0045] Fig. 3 Figure 1 shows, by way of example and schematically, another possible embodiment of a test rig 100 according to the invention in detail. The load motor 110, designed as an electric motor 110, is shown, comprising a motor housing 111 and a motor shaft 112. The electric motor 110 is, for example, a permanent magnet synchronous torque motor 110 with a liquid-cooled motor shaft 112. For example, the motor shaft 112 has a Fig. 3 The rotary feedthrough (not shown) allows glycol to be introduced as a coolant. Through bores (also not shown) in the motor shaft 112, the motor shaft 112 is cooled by the glycol flowing through it. The synchro-torque motor 110 is designed as a synchronous motor 110 and, for example, has twelve permanent magnet pole pairs. The comparatively large number of pole pairs gives the load motor 110 a comparatively very high torque even when subjected to relatively low currents. This design also has the advantage that the load motor 110 has a comparatively large radial width compared to its axial length. Such electric motors 110 are also known as "torque motors." An inverter 117 is, for example, arranged directly on the motor housing 111. Alternatively, the inverter 117 can also be arranged at a distance from the motor housing 111.

[0046] Also shown is a shutdown module 130. The load motor 110 is directly connected to the hub 21 of the vehicle 20 via a central opening in the shutdown module 130, for example, via the wheel flange of the hub 21. Since the hub 21 is an end member of the drive train of the vehicle 20, there is also a drive connection to the drive train of the vehicle 20, so that the drive train can be loaded and tested via the load motor 110. The motor housing 111 is in turn rotationally fixed to the radial central section 136 of the shutdown module 130. The central section 136 is rotatably held in the radial outer section 135 of the shutdown module 130 by means of a first bearing 140. This makes it possible to move the vehicle 20 under test relatively easily via the rotatable outer section 135, for example, to shift it, since the central section 136 does not rotate with it.On the other hand, it is possible to test the drive train by applying a torque and speed to the hub 20 from the load motor without the outer part 135 rotating, i.e., the motor vehicle 20 remaining stationary during the test procedure.

[0047] For example, a pneumatic tire 138 is arranged on the support module 130. This pneumatic tire 138 is, for example, a pneumatic tire 138 that is also approved for use on the road by the motor vehicle 20. Since the motor vehicle 20 rests on the pneumatic tire 138 during a test procedure, this results in a very realistic test behavior of the drive train of the motor vehicle 20.

[0048] A torque sensor 120 is arranged laterally on the motor housing 111 and is located in the force path of a strut 118 that encompasses the torque sensor. The strut 118 has, for example, a ball joint 118', 118" at each axial end, with the first ball joint 118' being attached to the motor housing and the second ball joint 118" being attached to the base 119. In this case, the base 119 is designed as a base plate 119, which has a connection for the second ball joint 118". Thus, the torque sensor 120 not only detects the torque generated by the load motor 110 but also blocks rotational movement of the motor housing 111 by providing rotational support to the base. Depending on the direction of rotation of the load motor 110, the torque sensor 120 is subjected to either tensile or compressive stress.

[0049] The load motor 110, the torque sensor 120, and the shutdown module 130 together represent one possible embodiment of the test bench 100 according to the invention. Only a portion of the motor vehicle 20 is shown, of which in Fig. 3 For the sake of clarity, only a hub 21, a vibration damper 22 and a wheel steering system 23 are shown.

[0050] Fig. 4 The figure shows, by way of example and schematically, another possible embodiment of a test rig 100 according to the invention. The test rig 100 of the Fig. 4 This differs from test bench 100. Fig. 3 firstly by the design of the parking module 130. For example, a rubber coating 139 is arranged on the parking module 130 instead of a pneumatic tire 138.

[0051] Another difference of the test bench 100 of the Fig. 4 compared to the test bench of Fig. 3 The design consists of providing a central inner part 137 instead of a central opening 137. This inner part is rotatable relative to the radial central part 136, which radially surrounds the central inner part 141, via a second bearing 141. Furthermore, a compensating coupling 121 is provided to compensate for angular and radial misalignments.

[0052] The motor housing 111 is connected to the radial central part 136 at its axial end facing the shutdown module in a rotationally fixed manner.

[0053] Fig. 5 Figure 1 shows, by way of example and schematically, a further possible embodiment of a test rig 100 according to the invention. The test rig 100 of Fig. 5 This differs from test bench 100. Fig. 4 primarily due to the presence of a support ram 133, which is adjustable in three spatial directions and rotatable about an axis (each represented by arrows). During the test procedure, the shutdown module 130 and the load motor 110 can be supported on the support ram 133. By appropriately actuating the support ram 133 during the test procedure, uneven ground conditions during a journey of the vehicle 20 can be simulated, for example. Likewise, almost all other influences of a possible surface can be simulated, especially in conjunction with steering movements of the steerable wheels of the vehicle 20. Furthermore, the test stand 100 differs from the Fig. 5 by the presence of an engine support 150, which, for example, engages the engine housing 111 from above and absorbs a tilting moment of the load engine 110, which would otherwise have to be supported by the shutdown module 130. For example, the engine support 150 is a wire rope 150, which is attached to a suitable structure above the test stand 100. For example, the engine support 150 also includes a compensation element 151, which contains a pre-tensioned spring and, by means of a set spring pre-tension, precisely supports the tilting moment of the load engine 110. Bezugszeichen

[0054] 10 Test stand 11 Load unit 12 Connecting shaft 13 Drive motor 14 Terminal box 15 Frame 16 Support element 20 Vehicle 21 Hub 22 Vibration damper 23 Wheel steering 100 Test stand 110 Load motor, electric motor, permanent magnet synchronous motor 111 Motor housing 112 Motor shaft 117 Inverter 118 Strut 118 First ball joint 118 Second ball joint 119 Base, floor plate, holding device 120 Torque sensor 121 Compensating coupling 130 Shut-off module 132 Locking device 133 Support ram 135 Radial outer part 136 Radial center part 137 Central inner part, central opening 138 Pneumatic tire 139 Rubber coating 140 First bearing 141 Second bearing 150 Engine support, wire rope 151 Compensation element

Claims

1. Test stand (100) for a drive train of a motor vehicle (20), comprising at least one load motor (110) with a motor housing (111) and a motor shaft (112), at least one torque sensor (120) and at least one parking module (130), the motor shaft (112) being designed to be drivingly connected to a hub (21) of the motor vehicle (20), and the torque sensor (120) being designed to detect a torque generated by the load motor (110), characterized in that the at least one torque sensor (120) is arranged on the motor housing (111) in such a way that it rotationally blocks a rotational movement of the motor housing (111) relative to a base (119) and supports the torque via the motor housing (111) on the base (119) and in that the at least one torque sensor (120) is arranged in a strut (118), the strut being attached to the motor housing (111) via a first joint eye (118') and being attached to the base via a second joint eye (118").

2. Test stand (100) according to Claim 1, characterized in that a respective torque sensor (120) is arranged on two lateral sides of the motor housing (111).

3. Test stand (100) according to at least one of Claims 1 and 2, characterized in that the at least one parking module (130) has a radial outer part (135) and a radial middle part (136), the middle part (136) being held rotatably in the outer part (135) and the middle part (136) being designed to be connected to an axial end of the motor housing (111) for conjoint rotation.

4. Test stand (100) according to Claim 3, characterized in that rotation of the middle part (136) relative to the outer part (135) can be blocked.

5. Test stand (100) according to at least one of Claims 1 to 4, characterized in that the motor shaft (112) can be connected to a hub (21) of the motor vehicle (20) for conjoint rotation.

6. Test stand (100) according to at least one of Claims 1 to 5, characterized in that the test stand (100) further comprises a pneumatic tyre (138), which is arranged on a radial outer circumference of the at least one parking module (130).

7. Test stand (100) according to at least one of Claims 1 to 5, characterized in that the test stand (100) further comprises a rubber coating (139), which is arranged on a radial outer circumference of the at least one parking module (130).

8. Test stand (100) according to Claims 1 to 7, characterized in that the at least one parking module (130) can be connected to the base in a force-fitting or form-fitting manner.

9. Test stand (100) according to Claims 1 to 8, characterized in that the at least one load motor (110) is designed as a permanently excited synchronous motor (110).

10. Test stand (100) according to at least one of Claims 1 to 9, characterized in that the test stand (100) further comprises at least one support jack (133), the support jack (133) being adjustable in three spatial directions and / or rotatable about an axis and the support jack (133) being designed to support the parking module (130) and forming the base (119).

11. Test stand (100) according to at least one of Claims 1 to 10, characterized in that the test stand (100) comprises a respective load motor (110), a respective torque sensor (120) and a respective parking module (130) for each drivable wheel of the motor vehicle (20).