Apparatus and method for aligning a test specimen axis relative to the axis of a test stand
Patent Information
- Application Number
- EP2023782798
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-28
- Filing Date
- 2023-09-26
- Publication Date
- 2025-08-06
AI Technical Summary
The precise alignment of an electric motor's axis with the test stand axis is challenging, leading to vibrations and measurement errors due to potential parallel or angular offsets, requiring extensive effort and recurring measurements during assembly.
A device comprising two plates with a fastening system allowing for alignment and fixing states, enabling precise parallel and rotational displacement to align the test object axis with the test stand axis, which can be pre-assembled and attached as a unit to the test stand, eliminating the need for subsequent realignment.
This solution ensures accurate alignment of the electric motor's axis with the test stand axis, minimizing offsets and preventing vibrations, thus reducing measurement errors and assembly time, while allowing for efficient use of the test stand for other tasks.
Smart Images
Figure 1.1
Abstract
Description
[0001] Device and method for aligning a test object axis relative to the axis of a test bench
[0002] The invention relates to a device and a method for aligning a test object axis relative to the axis of a test bench.
[0003] With the increasing use of electric motors as drives, e.g., for motor vehicles, it is necessary to test and evaluate the drive behavior of electric motors on a test bench, as has long been the case for internal combustion engines. To minimize interference, the electric motor (test specimen) under test must be precisely aligned with its motor axis to the test bench axis. The motor axis forms the geometric center axis or rotational axis of the motor shaft. Accordingly, the test bench axis represents the geometric center axis or rotational axis of a test bench shaft. The term "axis" is therefore to be understood as a geometric element that defines the respective position and orientation of a corresponding shaft.
[0004] Incorrect alignment of the two axes, e.g. due to a parallel offset or angular offset of the test object axis relative to the test bench axis, can lead to vibrations in the subsequent test process, which can cause measurement errors or damage to the test object or the test bench.
[0005] Accordingly, the electric motor to be tested must be mounted on the test bench with very high precision. This requires considerable effort during assembly of the electric motor, coupled with recurring measurements and alignment corrections.
[0006] During assembly and alignment of the test specimen, the test bench is also blocked and cannot be used for other testing tasks.
[0007] The invention is therefore based on the object of providing a possibility to easily and conveniently align the axis of an electric motor serving as a test object relative to the axis of a test bench.
[0008] The object is achieved according to the invention by a device having the features of claim 1 and by a method according to the independent claim. Furthermore, a test bench arrangement is specified in which the device can be advantageously used. Advantageous embodiments are specified in the dependent claims.
[0009] A device for aligning the axis of a test specimen relative to the axis of a test bench is specified, comprising a first plate which is designed to be fastened to a mounting plate of the test bench; comprising a second plate which is designed to fasten the test specimen; wherein the first plate and the second plate are arranged flat on one another and are fastened to one another by a fastening device; wherein the fastening device allows at least two fastening states, namely an alignment state and a fixing state, such that the two plates are displaceable relative to one another in parallel in the alignment state and that the two plates are fixed relative to one another in the fixing state; and wherein an adjustment device is provided for the parallel displacement of one of the two plates relative to the other plate in the alignment state.
[0010] The device is thus suitable for aligning a test specimen axis with a test bench axis. This can particularly involve the (geometric) axes of the respective shafts if the test specimen is an electric motor with a motor shaft and a dynamometer with a corresponding dynamometer shaft is provided on the test bench side. The two axes, and thus the shafts, must be aligned as precisely as possible to minimize axial or parallel misalignment on the one hand and angular misalignment on the other.
[0011] The described device comprises neither the test bench nor the test piece itself. Rather, it serves as a link between the test piece and the test bench, allowing the test piece to be easily attached to the test bench and functions as a type of adapter. In particular, the device allows the test piece to be aligned before it is mounted on the test bench. This allows—as explained later—the test piece to be first attached to the device and subsequently aligned with respect to the device. The aligned test piece is then attached to the test bench together with the device. Subsequent re-alignment is not required.
[0012] In particular, the test specimen can be attached to the second plate of the fixture and subsequently aligned with the second plate relative to the first plate. The first plate is then attached (mounted) to the test bench together with the second plate and the test specimen it supports. Once alignment is complete, the entire fixture, with the already mounted and aligned test specimen, can be attached as a single unit to the test bench's mounting plate. Subsequent realignment is no longer necessary, as the test specimen is already in the optimal position, with the test specimen axis aligned with the test bench axis.
[0013] The first plate and the second plate are in planar contact with each other, meaning they touch each other across a respective flat contact surface. The plates do not necessarily have to be completely flat. They could also have a different contour and, in particular, a different depth.
[0014] Moving the two plates relative to each other, especially the parallel or rotational movement required in the alignment state, using the adjustment device is only possible if the fastening device allows the alignment state. Otherwise, the fastening device fixes the two plates together, making it impossible to move the plates relative to each other.
[0015] The displacement of the two plates relative to each other occurs in the contact area, i.e., the area where the two plates touch each other. This displacement includes both a linear or parallel displacement as well as a rotational rotation in the plane of the two plates relative to each other.
[0016] The test specimen is first mounted on the second plate. If the test specimen is an electric motor, it is possible to attach the electric motor to the second plate via its front flange, specifically by screwing it. The second plate is then connected to the first plate, and the two plates can be secured together using the fastening device. The first plate can be attached to the test bench's mounting plate after the test specimen has been mounted and aligned.
[0017] The fastening device can have at least one screw connection that acts between the first plate and the second plate, wherein the screw connection is firmly tightened in the fixing state and loosened in the alignment state such that the two plates can be moved relative to one another. This allows the plates to always be held flat against one another, wherein in the fixing state the plates are pressed together so tightly by the screw connection that they can no longer be moved relative to one another. In the alignment state, however, the screw connection is loosened enough that the two plates can be moved relative to one another. Of course, a certain degree of friction should still exist between the two plates so that the plates do not lose contact with one another.For precise alignment, it is necessary that the plates always remain in flat contact with each other, creating a certain amount of friction between the two plates. Loosening or lifting the plates from each other should be avoided, as this could cause the plates to tilt relative to each other, thus compromising parallel movement.
[0018] The adjustment device can be configured to generate a force between the first plate and the second plate for the relative displacement of the two plates. In particular, this can generate a force that extends parallel to the contact surface between the two plates. The adjustment device can be supported on one of the plates and exert a force on the other plate. This makes it possible to displace one plate relative to the other plate. The displacement can, for example, comprise a parallel displacement and / or a rotation of the two plates relative to one another.
[0019] The adjustment device can have multiple screw devices, wherein at least one of the screw devices has a threaded holder attached to one of the plates, wherein a screw bolt can be screwed into the threaded holder, and wherein one end face of the screw bolt acts on that of the two plates to which the threaded holder is not attached, whereby a force can be applied to the respective plate. The screw bolt runs in the thread of the threaded holder and, in particular, can be rotated in this thread like a screw. By turning the screw bolt, the screw bolt is displaced axially.
[0020] When the bolt is in contact with the plate it is pushing against, a force acts on the end face of the bolt on the plate in question, causing it to move relative to the other plate.
[0021] The threaded holder and / or the screw bolt that can be screwed into the threaded holder can be arranged on a side surface of the respective plate, wherein the side surface is perpendicular to a contact surface where the two plates are in surface contact. The force exerted by the screw bolt therefore acts laterally on the plate and thus parallel to the contact surfaces of the two plates. The geometry of the first plate and the second plate can each correspond to a plate-shaped cuboid, each with two plate surfaces parallel to one another and four side surfaces connecting the two plate surfaces, wherein the adjustment device can have eight screw devices, two of which are arranged on each side surface of a plate at a distance from one another. In this case, one of the plate surfaces is a contact surface to the respective contact surface of the other adjacent plate.
[0022] The geometry of the plates does not have to be strictly limited to an exact cuboid. Approximate cuboids, e.g., with recesses or serrations, are also possible. The crucial factor is that the plates have four mutually perpendicular or parallel side surfaces, so that the screw devices arranged there allow any desired movement of one plate relative to the other in the plane. Thus, using a coordinate system, the plates can be linearly translated or rotated in the x- and y-directions, but not in the z-direction (which would mean the two plates would separate from each other).
[0023] Typically, the test object can be an electric motor. The electric motor may have a flange or a flange surface on its end face that can be used to attach the electric motor to the second plate.
[0024] A support frame can be provided, which is attached to the second plate. The support frame can serve to stiffen the entire assembly of the first and second plates. In particular, the support frame can be used to transport the device together with the test specimen mounted on the device. Furthermore, the support frame can be designed to support the test specimen in order to prevent bending and transverse moments on the housing of the test specimen or even the test specimen shaft.
[0025] Support elements can be provided on the support frame to support a test specimen attached to the second plate. These support elements can be formed, for example, by support bolts or support columns and support the test specimen, particularly on its underside, to reliably hold and secure it to the support frame.
[0026] The described device can be used particularly advantageously as an alignment device for aligning and securing a test specimen in a known test bench arrangement. A test bench arrangement is specified comprising an electric motor serving as the test specimen, a test bench for testing the electric motor, a test bench shaft to which a shaft of the electric motor can be secured, for transmitting a movement of the electric motor on the test bench, a mounting plate provided on the test bench, and a device of the type described above as an alignment device for securing and aligning the electric motor on the mounting plate.
[0027] Such a test bench, without the aforementioned (alignment) device, is known per se. As a rule, it has a drive or load device, such as a dynamometer, the shaft of which forms the test bench shaft. The test bench shaft is a component of the test bench and can be coupled to the shaft of the test object (here: the electric motor), e.g. by means of a suitable coupling. In this way, the movements of the test object and the load or drive device are precisely coupled to one another. In particular, the dynamometer can be operated as a load device and thus exert a load torque on the electric motor. In this way, a typical drive situation with the electric motor can be simulated.
[0028] Additionally or alternatively, the dynamometer can also be operated as a drive device, exerting a drive torque on the non-driven electric motor. This allows for overrun operation. Of course, the electric motor serving as the test object can also be operated as a generator to counteract a braking load on the driving dynamometer. This allows the braking behavior of the test object to be investigated during overrun operation.
[0029] In particular, a so-called 4-quadrant operation can be realized, in which the electric motor and the dynamometer can each be operated as a motor or generator in different combinations (motor-motor, motor-generator, generator-motor, generator-generator).
[0030] The test bench features a mounting plate to which the electric motor can be coupled. For this purpose, the alignment fixture described above can be used to optimally align the electric motor before mounting it on the mounting plate. The electric motor is then attached to the mounting plate together with the alignment fixture, without the need for any further adjustment or alignment measures.
[0031] The mounting plate can be plate-shaped, but can also be designed as a block or frame. Ideally, the mounting plate has a mounting surface to which the alignment device with the electric motor can be attached.
[0032] In the alignment device, the first plate, the second plate, the electric motor attached to the second plate, and the support frame can form a preassembled unit that can be attached to the mounting plate as a single unit. Accordingly, as already explained above, the electric motor can first be attached to the second plate. The relative position of the second plate to the first plate is then adjusted such that the motor shaft of the electric motor, and thus the axis of the electric motor, is in the exact position (parallel position, angular position) in which it must be relative to the first plate in order to later achieve the smallest possible offset from the test bench. The relative position of the two plates can be adjusted using a high-precision 3D measuring device.
[0033] The first plate and the second plate containing the electric motor are attached to the support frame, forming a pre-assembled, compact unit. This unit can then be attached to the mounting plate after the alignment, adjustment, and fastening work has been completed.
[0034] In particular, the first plate of the unit can be fastened to the mounting plate. For this purpose, a centering device can be provided for centering the first plate relative to the mounting plate. The centering device can, for example, have centering pins to enable the first plate to be precisely fastened to the mounting plate of the test bench.
[0035] Since the axis of the electric motor has already been precisely aligned to the first plate, the axis of the electric motor is also located exactly where it needs to be relative to the test bench shaft in order to achieve the smallest possible offset or error.
[0036] A method for aligning the axis of a test specimen relative to the axis of a test bench is specified, comprising the steps:
[0037] Providing a first plate and a second plate; arranging the first plate and second plate with their respective flat sides superimposed;
[0038] Attaching the test specimen to the second plate;
[0039] Measuring the axis of the test specimen and comparing the position of the axis with a given reference position (position, angle) in relation to the first plate;
[0040] Aligning the axis of the test specimen relative to the first plate by moving the second plate supporting the test specimen relative to the first plate to minimize a deviation of the position of the axis from the reference position;
[0041] Attaching the first plate to the second plate;
[0042] Attaching a support frame to the second plate such that the first plate, the second plate, the test piece and the support frame form a unit;
[0043] Attaching the unit to a mounting plate of the test bench.
[0044] These advantages and features of the invention are explained in more detail below using examples with the aid of the accompanying figures. They show:
[0045] Fig. 1 is a schematic side view of a test bench arrangement, with a test bench only schematically indicated and an alignment device carrying a test specimen in a sectional view;
[0046] Fig. 2 shows the alignment device of Fig. 1 with the test specimen in perspective view from above;
[0047] Fig. 3 shows the alignment device of Fig. 2 with the test specimen in perspective view from below; and
[0048] Fig. 4 the alignment device of Fig. 2 without test specimen.
[0049] Fig. 1 shows a side view of the schematic structure of a test bench arrangement with a test bench 1, which is only schematically indicated, and an alignment device 2 according to the invention, on which an electric motor 3 serving as the test object is mounted. The alignment device 2 serves not only to align the electric motor 3 relative to the test bench 1, but also to pre-assemble and subsequently attach the electric motor 3 to the test bench 1.
[0050] Test bench 1 includes a dynamometer 4, shown only symbolically in Fig. 1, as a load and drive device. Dynamometer 4 is, for example, an electric motor capable of both motor and generator operation with a motor shaft forming a test bench shaft 5. Dynamometer 4 and test bench shaft 5 are not drawn to scale in Fig. 1 and serve only to illustrate the test bench arrangement.
[0051] The position of the dynamometer 4 with the test bench shaft 5 also defines a test bench axis 6, which corresponds to the central or rotational axis of the test bench shaft 5.
[0052] Part of the test bench 1 is also a mounting plate 7 to which the electric motor 3 is to be attached for the test procedure.
[0053] The electric motor 3 in turn has a motor shaft 8 which defines a geometric test object axis 9.
[0054] For the test procedure, the motor shaft 8 of the test specimen (electric motor 3) is connected to the test stand shaft 5 of the dynamometer 4, e.g., via a suitable coupling. It is particularly important that the test specimen axis 9 and the test stand axis 6 are precisely aligned. Any misalignment, whether parallel or angular, will result in irregular running during testing and impair the measurement results. In the worst case, the test specimen or the test stand may even be damaged if the alignment error is too large.
[0055] In order to facilitate alignment and simplify the work processes on the test bench, the alignment device 2 is provided.
[0056] The alignment device 2 has a support frame 10, a first plate 11 and a second plate 12.
[0057] The alignment device 2 is also shown in Figures 2 and 3 from different perspectives, together with the electric motor 3. In Figure 4, the alignment device 2 is shown without the electric motor 3. Since Figures 1 to 4 each show the same alignment device 2, the following description applies to all figures.
[0058] The support frame 10 is designed as a stable, angular body, with a base plate 13, a support wall 14 that stands vertically when installed on the test stand 1, and stiffening ribs 15. The elements of the support frame 10 can, for example, be formed as a welded construction or milled from solid material. In particular, the underside of the base plate 13 must be machined with high precision, since the support frame 10 can be pushed onto this underside onto a corresponding holder on the test stand 1, e.g., onto a support table provided on the test stand 1. For precise guidance of the support frame, spring elements 16 are provided, which can be inserted into corresponding groove recesses in the support table of the test stand 1 (not shown).
[0059] The second plate 12 is attached, e.g., by a screw connection, to the end face of the supporting frame 10, in particular to the end face of the supporting wall 14. The first plate 11 is placed flat on the second plate 12. The first plate 11 and the second plate 12 are connected to each other by screws forming a fastening device and can be firmly screwed together.
[0060] The electric motor 3 is attached to the second plate 12, e.g., via a front flange located on the front side of the housing of the electric motor 3. Furthermore, the rear part of the electric motor 3, facing away from the second plate 12, is supported by support elements 17 on the base plate 13. This ensures that the electric motor 3 is reliably attached to the support frame 10 and the second plate 12 during test bench operation, where corresponding vibrations and force loads can occur at high speeds.
[0061] The support frame 10, the first plate 11 and the second plate 12 together with the electric motor 3 mounted thereon form a compact unit.
[0062] To align the test specimen axis 9 of the electric motor 3, the second plate 12 can be displaced in the plane relative to the first plate 11. To do this, the fastening device 18 must first be loosened. To do this, the screws securing the first plate 11 and the second plate 12 together can be loosened, but only to the extent that the first plate 11 and the second plate 12 can be displaced relative to each other in their contact plane. Lifting of the first plate 11 and the second plate 12 should be avoided. The only thing that matters is their mutual displaceability.
[0063] On the end faces of the first plate 11 and the second plate 12, respective screw devices 19 are provided, each with a threaded holder 20 and a threaded bolt 21 that can be screwed into it, which together form part of an adjustment device 22. A total of eight such screw devices 19 are arranged around the circumference of the first plate 11 and the second plate 12, two on each side surface, which together form the adjustment device 22.
[0064] The threaded mounts 20 can each be attached to the first plate 11 and support the threaded bolts 21. By rotating the threaded bolts 21, a force can be exerted via the end face of the threaded bolts 21 onto the side surfaces of the second plate 12 acted upon by the force, so that the second plate 12 is displaced relative to the first plate 11 with high precision, namely in accordance with the rotation of the threaded bolts 21. The electric motor 3 attached to the second plate 12 is displaced accordingly.
[0065] During this displacement, the position of the motor shaft 8 and thus of the test object axis 9 in relation to a reference position of the first plate 11 can be repeatedly measured using a high-precision measuring device. When a state is reached in which the test object axis 9 is exactly in the relative position to the first plate 11, in which no further deviation from the reference position (position, angle) defined by the first plate 11 can be detected, the fastening device 18 can be closed by tightening the connecting screws between the first plate 11 and the second plate 12, so that mutual displacement of the first plate 11 and the second plate 12 is no longer possible.
[0066] In this case, the first plate 11, the second plate 12, together with the support frame 10 and the electric motor 3, form a compact, stable unit, with the test specimen axis 9 located exactly at the specified location in the specified position (reference position). When this compact unit is subsequently attached to the mounting plate 7 of the test bench 1 via the first plate 11, the test specimen axis 9 and the test bench axis 6 are precisely aligned with each other. Parallel or angular misalignment can thus be virtually eliminated.
[0067] The pre-assembly and alignment of the electric motor 3 can be carried out, for example, with the following steps:
[0068] Arranging the second plate 12 over the first plate 11 horizontally one above the other at a pre-assembly workstation not shown.
[0069] Place the test specimen (electric motor 3) on the second plate 12. In this case, the motor shaft 8 extends vertically downwards. Measure the position (position, direction) of the motor shaft 8 and thus the test bench axis 9 using a high-precision 3D measuring device.
[0070] Alignment of the motor shaft 8 and thus of the test specimen axis 9 by horizontally or planarly moving the second plate 12 on the first plate 11.
[0071] Fixing the first plate 11 to the second plate 12 using the fastening device 18.
[0072] Rotating the entire device by 90° (including the support frame 10 attached to the second plate 12).
[0073] Positioning the spring elements 16 present on the support frame 10 on a corresponding support table of the test stand 1 and sliding the support frame 10 over the support table, wherein the spring elements 16 are guided in corresponding grooves of the support table.
[0074] Move the support frame 10 together with the first plate 11 and the second plate 12 until the first plate 11 comes into contact with the mounting plate 7 of the test bench 1. Then connect the plates 11, 12 to the mounting plate 7 using screw connections.
[0075] For the exact positioning of the first plate 1 1 on the mounting plate 7, appropriate centering elements must be provided, e.g. at least two centering bolts.
[0076] In the example shown, the centering is realized by a ring centering with a cylindrical shoulder 23 on the first plate 1 1. A corresponding hollow cylindrical recess (not shown) is provided in the mounting plate 7, associated with the shoulder 23.
Claims
Patent claims 1. A device (2) for aligning the axis (9) of a test specimen (3) relative to the axis (6) of a test bench (1), comprising a first plate (11) designed to be fastened to a mounting plate (7) of the test bench (1); and comprising a second plate (12) designed to fasten the test specimen (3); wherein the first plate (11) and the second plate (12) are arranged flat on one another and are fastened by a fastening device (18); the fastening device (18) allows at least two fastening states, namely an alignment state and a fixing state, such that the two plates (11, 12) are displaceable parallel to one another in the alignment state and that the two plates (11, 12) are fixed relative to one another in the fixing state; and wherein an adjusting device (22) is provided for the parallel displacement of one of the two plates (11, 12) relative to the other plate (11, 12) in the alignment state.
2. Device according to claim 1, wherein the fastening device (18) comprises at least one screw connection acting between the first plate (11) and the second plate (12); and wherein the screw connection is firmly tightened in the fixing state and loosened in the alignment state such that the two plates (11, 12) are displaceable relative to one another.
3. Device according to one of the preceding claims, wherein the adjusting device (22) is designed to generate a force between the first plate (11) and the second plate (12) for the relative displacement of the two plates (11, 12).
4. Device according to one of the preceding claims, wherein the adjusting device (22) has a plurality of screw devices (19); at least one of the screw devices (19) has a threaded holder (20) which is fastened to one of the two plates (11, 12); a screw bolt (21) can be screwed into the threaded holder (20); and wherein one end face of the screw bolt (21) acts on that of the two plates (11, 12) to which the threaded holder (20) is not fastened, whereby a force can be applied to the plate in question (11, 12).
5. Device according to one of the preceding claims, wherein the threaded holder (20) and / or the screw bolt (21) that can be screwed into the threaded holder (20) are arranged on a side surface of the respective plate (11, 12); and wherein the side surface is perpendicular to a contact surface at which the two plates (11, 12) are in planar contact.
6. Device according to one of the preceding claims, wherein the geometry of the first plate (11) and the second plate (12) each corresponds to a plate-shaped cuboid, each with two parallel plate surfaces and four side surfaces connecting the two plate surfaces; and wherein the adjusting device (22) has eight screw devices (19), two of which are arranged at a distance from one another on each side surface of a plate.
7. Device according to one of the preceding claims, wherein the test object is an electric motor (3).
8. Device according to one of the preceding claims, wherein a support frame (10) is provided which is fastened to the second plate (12).
9. Device according to one of the preceding claims, wherein support elements (17) are provided on the support frame (10) for supporting a test specimen (3) fastened to the second plate (12).
10. Test bench arrangement, with an electric motor (3) serving as a test object; a test bench (1) for testing the electric motor (3); a test bench shaft (5) to which a shaft (8) of the electric motor (3) can be fastened, for transmitting a movement of the electric motor (3) to the test bench (1); a mounting plate (7) provided on the test bench (1); and with a device (2) according to one of the preceding claims as an alignment device for fastening and aligning the electric motor (3) on the mounting plate (7).
11. Test bench arrangement according to claim 10, wherein the first plate (11), the second plate (12), the electric motor (3) fastened to the second plate (12) and the support frame (10) form a preassembled unit which can be fastened as a unit to the mounting plate (7).
12. Test bench arrangement according to claim 10 or 11, wherein the first plate (11) of the unit is attachable to the mounting plate (7).
13. Test bench arrangement according to one of claims 10 to 12, wherein a centering device (23) is provided for centering the first plate (11) relative to the mounting plate (7).
14. Method for aligning the axis (9) of a test specimen (3) relative to the axis (6) of a test bench (1), comprising the steps: Providing a first plate (11) and a second plate (12); Arranging the first plate (11) and second plate (12) with their respective flat sides one above the other; Attaching the test specimen (3) to the second plate (12); Measuring the axis (9) of the test specimen (3) and comparing the position of the axis (9) with a predetermined reference position in relation to the first plate (11); Aligning the axis (9) of the test specimen (3) relative to the first plate (11) by displacing the second plate (12) supporting the test specimen (3) relative to the first plate (11) in order to minimize a deviation of the position of the axis (9) from the reference position; Fastening the first plate (11) to the second plate (12); Attaching a support frame (10) to the second plate (12) such that the first plate (11), the second plate (12), the test piece (3) and the support frame (10) form a unit; Attach the unit to a mounting plate (7) of the test bench (1).