CLUTCH MODULE FOR A DRIVETRAIN TEST BENCH, OUTPUT MODULE AND DRIVETRAIN TEST BENCH

Description

[0001] The invention relates to a coupling module for a powertrain test bench for connecting a driveshaft to a drive shaft according to the preamble of claim 1, a corresponding output module for a powertrain test bench and a corresponding powertrain test bench.

[0002] Powertrain test benches for testing automotive powertrains are known from the prior art. Such powertrain test benches are typically used to detect powertrain malfunctions 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 or excited to vibrate.

[0003] In this context, DE 10 2012 018 359 A1 describes a driving cycle for a driving simulation, which is performed by a real motor vehicle on a chassis dynamometer. The motor vehicle's drive system operates in such a way that the wheel speed corresponds to the respective speed requirement of the driving cycle, without the motor vehicle actually moving. This allows the motor vehicle's powertrain to be tested after installation in the vehicle.

[0004] EP 2 602 602 A1 discloses a vehicle test rig for the dynamic loading of a vehicle, wherein at least one actuator is provided which simulates test loads acting on at least one test wheel of the vehicle during driving operation. A loading unit for the test wheel comprises a shaft section and a drum section. The test wheel is held in the drum section by friction. For this purpose, a tire mounted on a rim of the test wheel is radially clamped to a cylindrical inner surface of the drum section by inflation.

[0005] The applicant is also aware of so-called multi-link powertrain test rigs, which can be connected to the wheel flanges of a motor vehicle in a rotationally fixed manner and which guarantee the wheel flanges all degrees of freedom of movement that are also possible for the vehicle wheels during regular operation of the motor vehicle. The known multi-link powertrain test rigs consist of several levers and rotary joints arranged in series, each of which is movable relative to the others. The powertrain of the motor vehicle is driven directly by a vehicle-integrated drive unit. The drive shafts of the powertrain are the wheel shafts, which can be subjected to predetermined braking torques via the wheel flanges by the multi-link motor vehicle transmission test rigs.

[0006] DE 43 28 537 C2 discloses a transmission test bench comprising a first servomotor serving as a drive motor and a second servomotor serving as a brake motor. The first drive motor is connected via a coupling to the drive shaft of a vehicle transmission under test and its speed is controlled by a PC, allowing for the simulation of any desired speed profile. The brake motor is connected via another coupling to a driveshaft of the vehicle transmission under test. The speed of the second motor is also controlled by the PC. The speed profiles simulated by the PC are based on speed profiles measured in actual driving tests. Thus, according to DE 43 28 537 C2, the vehicle transmission can also be tested before installation in a vehicle.

[0007] Fig. 1 Figure 1 shows a wheel carrier module 10 known in the prior art, which detachably couples a drive axle 11 to a cardan shaft 12. The drive axle 11 is driven by a drive motor (not shown) and transmits rotational speed and torque via the wheel carrier module to the cardan shaft 12, which can be acted upon by a brake motor with a counterforce. The wheel carrier module is made of steel and, analogous to a conventional wheel rim, is connected to the drive axle via the wheel rim's bolt circle.

[0008] However, existing powertrain test benches have drawbacks in that they are either completely unsuitable for testing a motor vehicle powertrain before installation in a vehicle, or at least incapable of reliably testing an electrically driven powertrain before installation, because the behavior of the electric powertrain measured on the test bench does not correspond to its behavior when installed in the vehicle. The reason for this discrepancy between the behavior measured on the test bench and the behavior in the vehicle lies in the fact that the electric drive motor, compared to an internal combustion engine, has a comparatively rigid and inelastic rotational behavior.Furthermore, an electric drive motor is often located directly on the axle it drives, resulting in comparatively short drive paths and thus further stiffening of the drivetrain. This low elasticity of the electric drivetrain can, however, be largely compensated for by the vehicle's rubber tires when installed in the vehicle, but not on a drivetrain test bench.

[0009] It is an object of the present invention to propose an improved coupling module for a powertrain test bench for connecting a driveshaft to a propeller shaft.

[0010] This problem is solved according to the invention by the coupling module for a powertrain test bench for connecting a driveshaft to a propeller shaft according to claim 1. Advantageous embodiments are described in the dependent claims.

[0011] The invention relates to a coupling module for a powertrain test bench for connecting a driveshaft to a input shaft, wherein the coupling module comprises a wheel rim and a wheel hub with a base and a side wall, wherein the wheel rim can be arranged on the input shaft in a rotationally fixed manner and wherein the wheel hub can be arranged on the driveshaft in a rotationally fixed manner. The coupling module according to the invention is characterized in that an annular damping element is arranged on the wheel rim, which is in frictional contact with an inner surface of the side wall of the wheel hub.

[0012] According to the invention, a coupling module is provided which is suitable for connecting a drive shaft of a powertrain test bench to a driveshaft of a powertrain test bench. The drive shaft is a shaft that can be driven by a drive motor of the powertrain or the powertrain test bench. The drive motor of the powertrain or the powertrain test bench is preferably an electric drive motor. In particular, the drive shaft is not driven directly by the drive motor, but indirectly via a transmission stage or a switchable gearbox. Technically speaking, the drive shaft within the meaning of the invention can therefore also be the driveshaft of the transmission stage or the gearbox.

[0013] The drive shaft, together with the drive motor that drives it, can advantageously be designed as a drive train intended for installation in a vehicle; that is, the drive shaft could be, for example, a driven rigid axle, a driven steering axle, or even an individual wheel drive, which is installed in a suitable vehicle after the testing process. The vehicle could be, for example, a passenger car, a truck, a commercial vehicle, or even construction or industrial machinery.

[0014] The coupling module comprises a wheel rim, which may be designed as a conventional wheel rim for use on a motor vehicle. The coupling module further comprises a wheel hub, the wheel hub having a base and a side wall. The wheel hub is advantageously designed as a hollow cylinder, with the base forming the bottom surface of the hollow cylinder and the side surface forming the outer surface of the hollow cylinder. The wheel hub is preferably made of steel.

[0015] The coupling module can be connected to the drive shaft in a rotationally fixed manner via the wheel rim, in particular via a bolted ring on the wheel rim. Thus, the coupling module can be connected to the drive shaft of the drive train just like a conventional wheel rim.

[0016] The coupling module can also be connected to the driveshaft via the wheel hub in a rotationally fixed manner, particularly via a flange connection. The driveshaft is advantageously driven by an electric load motor, which can introduce braking torques into the drivetrain that oppose the drive torques of the drive motor. This allows a dynamic load on the drivetrain to be simulated.

[0017] The coupling module according to the invention is characterized in that an annular damping element is arranged on the wheel rim, the radial outer circumference of which, in particular, is in frictional contact with an inner surface of the side wall of the wheel hub. Thus, torque can be transmitted from the drive shaft via the wheel rim and the damping element to the side wall of the wheel hub and therefore to the drive shaft.

[0018] The ring-shaped damping element replicates the torsional vibration damping properties of an actual vehicle tire and is mounted on the wheel rim in the same way as a vehicle tire.

[0019] Advantageously, the damping element has a profiled tread surface on its radial outer circumference, similar to an actual vehicle tire.

[0020] The damping element can be made, for example, from a damping elastomer or from tire rubber. Furthermore, the damping element can be designed as an inflatable hollow body or as a solid form.

[0021] This results in the advantage that the coupling module according to the invention ensures an elasticity of the drivetrain in the drivetrain test bench that corresponds to the actual elasticity of the drivetrain in its installed state in the vehicle. By transmitting the torque of the drive motor via a wheel rim and the damping element, the invention utilizes the fact that the actual behavior of the drivetrain in its installed state is significantly influenced by the elasticity of the rubber vehicle tire. Thus, the coupling module according to the invention enables a considerably more realistic test of the drivetrain than is currently possible in the prior art.The invention therefore does not merely attempt to simulate a specific behavior of the drive train, as is often the case in the prior art, but adapts the characteristics that significantly shape the behavior of the drive train in its actual installed state in the vehicle.

[0022] Preferably, the inner surface of the wheel hub's side wall has a coating that increases the coefficient of friction of the damping element on the inside. This prevents the damping element from spinning freely in the wheel hub, even at high torques.

[0023] An asphalt coating is particularly preferred. This allows for a largely realistic behavior of the damping element in the wheel hub.

[0024] According to a further preferred embodiment of the invention, the damping element is designed as a vehicle tire, the tread of which is in frictional contact with an inner surface of the sidewall of the wheel hub. By designing the damping element as a vehicle tire, a completely realistic behavior of the drivetrain can be achieved during the testing process.

[0025] It is advantageous that the tire is only inflated with compressed air after it has been positioned in the wheel hub. If the tire is only inflated after being placed in the hub, it expands radially and thus comes into contact with the sidewall. This also facilitates easier placement of the tire in the wheel hub.

[0026] According to a further preferred embodiment of the invention, the wheel hub has a support ring arranged at one end of the wheel hub's side wall opposite the base surface. Thus, the damping element or the vehicle tire is not only radially enclosed by the inside of the wheel hub's side wall and axially enclosed by the base surface on a first side, but also axially enclosed by the support ring on a second side. This offers the advantage that the side wall is also stabilized at the axial end opposite the base surface, and both axial ends are secured, in particular, against radial bending, for example, due to the vehicle tire being inflated with compressed air and the resulting expansion.The support ring thus secures the sidewall against unwanted deformation and therefore also ensures a greater possible contact pressure of the damping element or the tread of the vehicle tire against the sidewall, since the sidewall cannot elastically yield to the contact pressure of the vehicle tire.

[0027] The support ring can either partially or completely enclose the second axial side of the damping element or the vehicle tire. In the case of partial enclosure, the support ring is preferably arranged in the radially outer region of the damping element or the vehicle tire and attached to the side wall of the coupling module.

[0028] According to a particularly preferred embodiment of the invention, the support ring is detachably arranged on the wheel hub. This has the advantage that the mounting or dismounting of the vehicle tire is not made more difficult by the support ring.

[0029] According to a further particularly preferred embodiment of the invention, the support ring is connected to the wheel rim at its inner circumference via a support bearing. This offers the advantage that the stability of the coupling module can be increased, particularly at high speeds or during highly dynamic testing procedures, via the support bearing.

[0030] If the coupling module has the additional support bearing, preferably a special rim is not used, but instead a special rim which has a corresponding bearing surface to support the support bearing.

[0031] According to a further preferred embodiment of the invention, a centering bearing is arranged in the base surface for centering the wheel hub on the wheel rim. The wheel rim can, for example, have a radially central projection on which the centering bearing can be supported. The centering bearing improves the centering accuracy of the driveshaft relative to the input shaft and thus reduces imbalance of the clutch module, particularly at high speeds and during highly dynamic testing procedures.

[0032] To support the centering bearing on the drive-side part of the clutch module, an adapter piece can preferably be used, which is particularly cylindrical and has an open and a closed axial end. A ring of holes is preferably provided at the open axial end, which allows the adapter piece to be fixed to the wheel rim's mounting ring by means of screws. For example, the adapter piece can be arranged on the drive shaft together with the wheel rim, so that the mounting ring of the wheel rim and the mounting ring of the adapter piece are aligned with the mounting ring of the drive shaft, and both the wheel rim and the adapter piece are held by the same screws, which pass through the wheel rim and the adapter piece and engage in the drive shaft. A projection is preferably provided at the closed axial end, which facilitates the arrangement of the centering bearing.

[0033] According to a further preferred embodiment of the invention, the base surface is designed as a grid surface or as a segmented surface with bracket arms. This means that the base surface is not designed as a solid "plate," but rather can be formed with gaps or intermediate surfaces that are free of material. The number of bracket arms can be selected as needed, depending on the material thickness or torque transmission capacity; the grid thickness can also be selected accordingly. The bracket arms represent connecting struts that link the side wall of the wheel hub to a connection point for the driveshaft, thus transmitting the torque transmitted from the tire to the side wall to the driveshaft. Similarly, the grid surface transmits the torque transmitted from the tire to the side wall to the driveshaft.By forming the coupling module as a grid surface or as a segmented surface with bracket arms, the advantage arises that material can be saved, making it lighter and more cost-effective, and in particular resulting in a lower moment of inertia. Furthermore, the vehicle tire is also accessible from the side of the ground surface.

[0034] According to a further preferred embodiment of the invention, the sidewall is designed as a clampable sidewall. A clampable sidewall is understood to be a sidewall whose circumference can be mechanically adjusted so that it can be clamped around the tread of the vehicle tire. This allows, on the one hand, a comparatively simple assembly of the damping element or the vehicle tire in the coupling module and, on the other hand, reliable clamping of the vehicle tire in the coupling module for testing. In particular, the vehicle tire does not need to be brought into contact with the sidewall by inflating it, meaning that even a fully inflated tire can be mounted. Furthermore, the frictional contact between the inner surface of the sidewall and the tread of the vehicle tire can be increased in this way, since the contact pressure can be greater.This means that larger torques can also be transmitted.

[0035] According to the invention, the inner sidewall has at least one contact patch segment. A contact patch segment is defined as a deviation from a circular shape in the form of a segmented circular chord upon which the damping element or the vehicle tire rests with its tread, forming a contact patch. Since, in actual operation of the vehicle tire on a motor vehicle, the force transmission from the tire to the road occurs exclusively via the contact patch, the contact patch segment enables the generation of particularly realistic test behavior and force transmission behavior by the clutch module. Optionally, several contact patch segments can be provided, which, for example, increases the stiffness with regard to the torque transmission behavior of the clutch module. Generally, the stiffness increases with the number of contact patch segments.

[0036] According to a further preferred embodiment of the invention, the damping element or the tread of the vehicle tire is in contact exclusively with the at least one contact segment. This allows for a completely realistic torque transmission behavior of the clutch module.

[0037] The invention further relates to an output module for a powertrain test bench, comprising an electric load motor and a coupling module according to the invention. This leads to the advantages already described in connection with the coupling module according to the invention also for the output module according to the invention.

[0038] Finally, the invention also relates to a powertrain test bench for testing a vehicle powertrain, comprising at least one output module according to the invention. This leads to the advantages already mentioned.

[0039] The invention is explained below by way of example with reference to embodiments shown in the figures.

[0040] They show: Fig. 1 a wheel carrier module known in the prior art, Fig. 2 an exemplary and schematic representation of a possible structure of a coupling module according to the invention for connecting a cardan shaft to a drive shaft, Fig. 3 a cross-section through the coupling module of the Fig. 2 ., Fig. 4 the cross-section through the coupling module of the Fig. 2 with a sliding segment and Fig. 5 by way of example and schematically another possible construction of a coupling module according to the invention for connecting a cardan shaft to a drive shaft.

[0041] 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.

[0042] Fig. 1 Figure 1 shows a wheel basket module 10 known in the prior art, which detachably connects a drive axle 11 with a cardan shaft 12.

[0043] Fig. 2 Figure 1 shows, by way of example and schematically, a possible construction of a coupling module 20 according to the invention for connecting a cardan shaft 22 to a drive shaft 21. The drive shaft 21 is connected, for example, by a (in Fig. 2 The coupling module 20 is driven by an electric motor (not shown) which is arranged directly on the drive shaft 21 and is rigidly associated with the drive shaft 21, i.e., which actually drives the drive shaft 21 during real-world driving operation in the motor vehicle. The coupling module 20 comprises a wheel rim 23, which is a conventional wheel rim 23 such as can be mounted on motor vehicles in road traffic. The coupling module 20 further comprises a wheel hub 24, with a base surface 24' and a side wall 24". Enclosed by the wheel hub 24 is a damping element 25 designed as a vehicle tire 25, which is arranged on the wheel rim 23 and whose running surface 25' is in frictional contact with an inner surface 24‴ of the side wall 24" of the wheel hub 24. This results in very realistic properties with regard to the torque transmission behavior of the clutch module 20, since the elasticity of the vehicle tire 25 is utilized as in real driving operation.The torque is first transmitted from the drive shaft 21 to the wheel rim 23 and then from the wheel rim 23 to the vehicle tire 24. The vehicle tire 24 transmits the torque, according to its elastic properties, via its tread 25' to the inner surface 24‴ of the sidewall 24" of the wheel hub 24. The wheel hub 24, in turn, transmits the torque via its base surface 24' to the driveshaft 22.

[0044] The exemplary coupling module 20 of the Fig. 2 The assembly further comprises a support ring 30, which is detachably arranged by means of a screw connection at one end of the side wall 24" of the wheel pot 24 opposite the bottom surface 24' of the wheel pot 24. The support ring 30 prevents elastic yielding in the sense of radial bending of the side wall 24" at the axial end of the side wall 24" facing the support ring 30.

[0045] Finally, the coupling module comprises 20 of the Fig. 2 The coupling module 20 also includes a centering bearing 26 for centering the wheel hub 24 on the wheel rim 23. The coupling module 20 is supported via its base surface 24' on a projection 27 of an adapter piece 31, which is connected to the wheel rim 23 by means of a screw connection via the bolted ring. The centering bearing 26 improves the uniformity of the coupling module 20, particularly at high speeds and during highly dynamic testing procedures.

[0046] Fig. 3 shows a cross-section through the coupling module 20 of the Fig. 2 The diagram shows the side wall 24" with the inner surface 24' of the wheel hub 24. The vehicle tire 25 is arranged in the wheel hub 24 with its tread 25', the tread 25' being in frictional contact with the inner surface 24" so that torque transmission is possible. The vehicle tire 25 is mounted on the wheel rim 23.

[0047] Fig. 4 shows the cross-section of Fig. 3 However, the inner side 24" of the side wall 24' has, for example, a contact segment 28. The contact segment 28 causes the vehicle tire 25, when clamped in the wheel hub 24, to form a contact point, just as in actual driving operation on the motor vehicle, through which the full torque is transmitted. For example, in Fig. 4 Aside from the contact segment 28, there is an air gap between the tread 25' of the vehicle tire 25 and the inside 24" of the sidewall 24'.

[0048] Fig. 5 Figure 1 shows, by way of example and schematically, another possible construction of a coupling module 20 according to the invention for connecting a cardan shaft 22 to a drive shaft 21. The coupling module 20 of the Fig. 5 differs from the clutch module 20 of the Fig. 2 This is achieved solely by using a specially manufactured wheel rim 23 instead of a conventional wheel rim 23, which allows for the provision of a support bearing 29. This offers the advantage that the stability of the clutch module 20 can be increased, particularly at high speeds or during highly dynamic testing procedures, via the support bearing 29. The support ring 30 is extended radially inwards accordingly to engage the support bearing 29. Bezugszeichen

[0049] 10 Wheel carrier module 11 Drive axle 12 Cardan shaft 20 Clutch module 21 Drive shaft 22 Cardan shaft 23 Wheel rim 24 Wheel hub 24' Bottom surface 24" Sidewall 24' Inner side 25 Damping element, vehicle tire 25' Tread 26 Centering bearing 27 Projection 28 Footplate 29 Support bearing 30 Support ring 31 Adapter piece

Claims

1. Coupling module (20) for a drive train test stand for connecting an articulated shaft (22) to a drive shaft (21), wherein the coupling module (20) comprises a wheel rim (23) and a wheel cap (24) having a base face (24') and a side wall (24‴), wherein the wheel rim (23) can be arranged in a rotationally secure manner on the drive shaft (21), wherein the wheel cap (24) can be arranged in a rotationally secure manner on the articulated shaft (22), and wherein there is arranged on the wheel rim (23) an annular damping element (25) which is in frictionally engaging abutment with an inner side (24‴) of the side wall (24") of the wheel cap (24), characterized in that the inner side (24‴) of the side wall (24") has at least one latch segment (28).

2. Coupling module (20) according to Claim 1, characterized in that the damping element (25) is in the form of a vehicle tyre (25) which is in frictionally engaging abutment with the running face (25') thereof with an inner side (24‴) of the side wall (24") of the wheel cap (24).

3. Coupling module (20) according to at least one of Claims 1 and 2, characterized in that the wheel cap (24) has a support ring (30) which is arranged at an end, opposite the base face (24') of the wheel cap (24), of the side wall (24") of the wheel cap (24).

4. Coupling module (20) according to Claim 3, characterized in that the support ring (30) is releasably arranged on the wheel cap (24).

5. Coupling module (20) according to at least one of Claims 3 and 4, characterized in that the support ring (30) is connected to the wheel rim (23) at the inner circumference thereof by means of a support bearing (29).

6. Coupling module (20) according to at least one of Claims 1 to 5, characterized in that a centring bearing (26) for centring the wheel cap (24) on the wheel rim (23) is arranged in the base face (24').

7. Coupling module (20) according to at least one of Claims 1 to 6, characterized in that the base face (24') is in the form of a grid face or a segment face having bracket arms.

8. Coupling module (20) according to at least one of Claims 1 to 7, characterized in that the side wall (24") is in the form of a clampable side wall (24").

9. Coupling module (20) according to Claim 1, characterized in that the damping element (25) or the running face (25') of the vehicle tyre (25) is exclusively in abutment with the at least one latch segment (28).

10. Output module for a drive train test stand, comprising an electric loading motor and a coupling module (20) according to at least one of Claims 1 to 9.

11. Drive train test stand for testing a vehicle drive train, comprising at least one output module according to Claim 10.