Modular, power-split test bench gearbox with shifting and integrated cooling and damping

Abstract

Test bench with a test bench gearbox (1) comprising a torque input shaft (2) and a torque output shaft (3), wherein the torque output shaft (3) is prepared to be coupled to a test specimen, such as a high-speed electric motor, and wherein a power-split gearbox section (4) is provided between the torque input shaft (2) and the torque output shaft (3), which makes it possible to transmit torque from the torque input shaft (2) to the torque output shaft (3) via different, separate power flow paths, characterized in that at least one switching element is provided between the power-split gearbox section (4) and the torque input shaft (2) and / or the torque output shaft (3), which is configured to enable or prevent torque transmission depending on the switching position.

Description

Technical FieldThe present disclosure relates to a test stand having a test stand transmission with a torque input shaft and a torque output shaft, wherein the torque output shaft is prepared to couple to a test object, such as an electric motor, and wherein a power-split transmission section is present between the torque input shaft and the torque output shaft, which transmission section makes it possible to transfer torque from the torque input shaft to the torque output shaft on different, separate, for example parallel, power flow paths.Prior ArtHybrid drive trains with a power-distributing transmission for electric machines and corresponding shifting methods are already known from the prior art. For example, DE 10 2016 108 552 A1 discloses a hybrid drive which has a power-distributing, power-shiftable transmission which has a spur gear shaft transmission with a coaxial central shaft and a power-distributing transmission, such as a differential transmission of planetary gear design, which is arranged upstream of the shiftable transmission in terms of drive. At least two drive machines, such as a drive motor and / or electric machines usable as a generator, are each connected or can be connected rotatably and / or rotationally fixedly to the shaft of the coaxial central shaft. A pawl shift element having multiple shift positions is disposed as a power flow connector between a rotational body of the power split transmission and one of the shafts of the central shaft. The transmissions can be mechanically coupled and decoupled by shift sequences, wherein a claw sleeve has at least two shift positions, between which it is possible to shift alternately during operation of the hybrid drive.However, the prior art has the disadvantage that there have been less flexible / conformable solutions to date specific to high performance test stands, such as for testing electric motors or entire vehicle E-axles, i.e. that the prior test stand solutions cannot often cover varying customer requirements, especially with respect to relatively large speed operating ranges, with a test stand design. This has the result that customer requirements for different rotational speed operating ranges of test specimens often either have to be carried out on different test stands or the respective test stands have to be re-fitted in a time-consuming and thus cost-intensive manner.Furthermore, the prior art has the disadvantage that especially test stands for the high speed range generally have a high space requirement and this is additionally increased by additional cooling measures which are required due to the high speeds. In particular in the case of very precise test stands, damping measures are also necessary, which can additionally contribute to the space requirement of the test stand.Further prior art with respect to the aforementioned technical field is known from AT 512 104 A2.It is therefore an object of the invention to avoid or at least alleviate the disadvantages from the prior art. In particular, this is to be achieved by a modular, power-split and switchable test stand transmission with integratable cooling and damping.This object is achieved in principle in a device of the generic type according to the invention in that at least one shift element is present between a power-split transmission section and a torque input shaft and / or the torque output shaft, which shift element is configured to enable or disable torque transmission depending on the shift position.This has the advantage that the test stand can set the torque transmission in a targeted manner by means of the flexible shifting of the at least one shift element in order to bring about one or more transmission ratios or reductions in the transmission and a drive through without a change in rotational speed, or else an idling state by making the torque transmission impossible. As a result, a greater rotational speed operating range can be achieved with one design and different test specimens can be examined, for example, with one design.Advantageous embodiments are claimed in the dependent claims and are explained in more detail below.It is thus advantageous if the at least one shift element of the test stand transmission is a coupling element which is configured to directly couple the torque input shaft and torque output shaft at the respectively opposite shaft ends.As a result, it is possible to allow a through-drive without a change in rotational speed and with as few friction losses as possible in the transmission, since the force transmission, without additional branches, can be passed on directly via the coupling in the axial direction of the torque input shaft and torque output shaft.In addition, it is expedient if the torque input shaft and / or the torque output shaft have at least one shift element in the test stand transmission, which shift element is a through-shift element which is arranged between the torque input shaft and a torque input pinion located thereon or between the torque output shaft and a torque output pinion located thereon and is configured to enable or disable torque transmission.This allows a driven shaft to be transmitted torque between the driven shaft and the pinion when the torque transmission through-element is set by fixing the corresponding pinion to the driven shaft in a rotationally fixed manner, and the driven shaft rotates relative to the corresponding pinion without fixing the pinion to the driven shaft in a rotationally fixed manner and not moving.Through-shift elements thus allow, when a plurality of pinions are located on a driven shaft, selectively to fix one pinion for the torque transmission, while the torque transmission is prevented from occurring at the remaining pinions located on the driven shaft. Individual pinions can thus be selectively switched through, whereby different overdrives or gear reductions can be implemented in the transmission in a space-saving manner.An advantageous exemplary embodiment of the test stand transmission is characterized in that the through-shifting element and at least one component of the coupling element are arranged on the torque input shaft.By means of such an exemplary embodiment of the test stand transmission, it is possible, when the shift element is activated and the coupling element is decoupled, that is to say specifically the shift element allows the torque to be transmitted and the coupling element does not couple directly between the torque input shaft and the torque output shaft, to introduce the torque into the power-split transmission section via a pinion located on the torque input shaft.Furthermore, with this configuration it is also possible to make it possible to make it possible to transmit the torque to the through-shifting element and thus to transmit the torque to the power-split transmission section and instead to transmit the torque directly to the torque output shaft via the coupled coupling torque. It can thus be switched between an optionally increased or decreased or unchanged speed transmission.A further advantageous exemplary embodiment of the test stand transmission is characterized in that only through-shift elements are arranged as shift elements on the torque output shaft.This advantageous embodiment allows an over- or reduction gear to be implemented on the torque output shaft, depending on which shifting element on the torque output shaft is activated and thus carries out the torque transmission via a corresponding pinion.It is furthermore advantageous if the test stand transmission has an additional supply for liquids / fluids, such as coolant / heat medium, for example in the torque output shaft, for example for cooling the test object, which either has a fixed line which runs along the central axis of the hollow torque output shaft and does not rotate with respect to the torque output shaft, or which has a rotary bushing which has a static shaft sleeve in which a rotor part of the rotary bushing rotates, which is arranged at the end of the torque output shaft facing the torque input shaft and which has inlet openings for the additional liquid at the circumferential sections surrounded by the shaft sleeve and rotates with the hollow torque output shaft.In both of the above-mentioned embodiment possibilities of supplying liquid, the liquid advantageously runs along the central axis of the torque output shaft, as a result of which, on the one hand, a space-saving feeding of the test stand gear is made possible, and, on the other hand, a simultaneous, efficient feeding of the test object coupled to the torque output shaft is also made possible. By integrating the liquid supply, it is possible, for example, to reliably ensure tests that last for a longer time in the high-speed range by liquid cooling.Furthermore, it is preferred if the liquid supply of the test stand transmission reaches the fixed line and the torque output shaft via the coupling element.This embodiment makes it possible to combine the advantages of a coupling element and the liquid supply and to combine them in a component in a space-saving and functionally saving manner.According to an advantageous development of the test stand transmission, the liquid supply can take place via the fixed line as long as the coupling element does not couple the torque input shaft and the torque output shaft, and an interruption of the liquid supply can take place as soon as the torque input shaft and the torque output shaft are coupled directly via the coupling element.By the above-described liquid supply operating mechanism, it is possible to automatically stop liquid feed when the torque output shaft is directly coupled to the torque input shaft and has a relatively low rotational speed, and thus liquid feed is not required.At the same time, it is possible to ensure automatic fluid feeding of the torque output shaft, the test stand transmission itself and the test object as soon as the rotational speed of the torque output shaft increases relatively with respect to the torque input shaft if the latter is not directly coupled to the torque input shaft, but rather is rotated more quickly via a transmission ratio of the power-split transmission section relative to the torque input shaft.It is furthermore advantageous if the test stand transmission has torsion damping elements which are arranged at connection interfaces between the torque input shaft and a shift element and / or at connection interfaces between the torque output shaft and a shift element. In addition, the torsion damping elements can be arranged not only between a torque input shaft or torque output shaft and a shifting element, but also in the connection interfaces from one shifting element to another shifting element or on intermediate shafts embodied in two parts.The torsion damping elements can advantageously be arranged between toothing elements of the shift elements and the torque input shaft and / or the torque output shaft.The aforementioned embodiment has the advantage that the torsion damping elements can be accommodated in a particularly space-saving manner and directly on sensitive regions (due to the small material thickness of the toothing elements) with relatively high applied torsion forces. By inserting the torsion damping elements, torque irregularities, which arise, for example, due to the tooth meshing in the transmission, can be advantageously reduced, whereby the measurement of the torque measurement can be improved.In other words, the invention relates in its basic structure to a power-split spur gear transmission which is preferably constructed without a ring gear and is used predominantly in test stand construction as a high-drive gear. It is also intended in particular as a retrofitting solution for already existing test stands, the rotational speed field of which is to be extended upwards. In the reverse direction, the transmission is used when an existing engine with the transmission is reduced to lower speed with greater torque. The options listed below are integrated into the basic design of the power-split transmission in order to offer the user a compact and powerful unit, in particular for test bench applications.A transmission, preferably a test stand transmission, equipped with the following additional features leads to advantages because the field of application is thereby extended overall and / or operation is facilitated.A shift mechanism allows operation of the transmission with one or more overdrive / reduction ratios in one or more shift positions and, if necessary, a through-drive without a change in rotational speed in another shift position. As a result, a larger operating range can be achieved with one design, i.e. different test specimens can be examined with one design, for example.Recently, recently, electric motors are sometimes equipped with an internal rotor cooling system in order to further increase the power density. If such motors are inspected on test stands, the coolant supply must also be ensured there. The transmission system presented also offers a solution for this purpose in that the sun shaft is designed hollow and can be supplied via a fixed line, a so-called lance, or by means of a rotary feedthrough via the hollow shaft itself in the center, coolant or even another medium in the direction of the test object.A particular importance arises in connection with the fluid passage in conjunction with a possible shift in the power-split transmission. In this case, the medium is guided via the switching element into the center of the output shaft. In the non-switched state, the switching element is sealed with respect to the housing and the medium is transported into the center of the output shaft and is available there, for example, for cooling the test object. In the other switching position, i.e. during the drive, the switching element connects the input shaft and the output shaft. As a result, no liquid supply is possible. The feed is interrupted in the feed.Furthermore, especially for research and development tasks, the measurement of the operating data on the test object is in demand. In this case, the torque measurement is disturbed by the torque non-uniformity due to the tooth meshings in the transmission. The resulting desire of users for torsional damping between the transmission and the test object is met by the integration of damping elements, for example on the sun shaft.The damping elements are positioned in a space-saving manner between a shaft part and a hub part as a coupling. Typically, such clutches are used as a separate unit to connect different assemblies (e.g., between the engine and the transmission). Interfaces (fitting diameter for clamping, hole circle for screw connection or the like) are provided for this purpose.However, the connection via these interfaces requires its own installation space and adds additional mass to the structure. This can be very disadvantageous, especially for high-speed use. Damping elements are therefore introduced directly between the shaft and the hub part, for example a toothed element.Brief Description of the FiguresThe invention is explained in more detail below with the aid of drawings. The following are shown: FIG. 1 shows a schematic basic structure of a first embodiment of a test stand transmission, FIG. 2 shows a schematic basic structure of a second embodiment of a test stand transmission, FIG. 3 shows a perspective illustration of the second embodiment of the test stand transmission, FIG. 4 shows a sectional illustration of the test stand transmission along the longitudinal axes of the torque input shaft and of the torque output shaft for illustrating a first embodiment of the liquid feed, FIG. 5 shows a sectional illustration of the test stand transmission along the longitudinal axes of the torque input shaft and of the torque output shaft for illustrating a second embodiment of the liquid feed, FIG. 6 is an exploded view of a shift element and the torque output shaft and the interposed torsion damping elements, FIG. 7 is a perspective view of the torque output shaft assembled with a shift element and the torsion damping elements interposed in the connecting portions.The figures are merely schematic in nature and serve only to understand the invention. The same elements are provided with the same reference numerals. The features of the individual exemplary embodiments can be interchanged.DESCRIPTION OF THE EMBODIMENTSFIG. 1 shows a first embodiment of the test stand transmission 1 of a test stand according to the invention. The test stand transmission 1 has a torque input shaft 2 and a torque output shaft 3, wherein the torque output shaft 3 is prepared to couple to a test object, such as a high-speed electric motor. A power-split transmission section 4 is present between the torque input shaft 2 and the torque output shaft 3, which makes it possible to transfer torque from the torque input shaft 2 to the torque output shaft 3 on different power flow paths that are separate from one another. Furthermore, a shift element is arranged between the power-split transmission section 4 and the torque input shaft 2 as a through-shift element 5, and a second shift element is arranged as a clutch element 6 between the torque input shaft 2 and the torque output shaft 3.The first embodiment of the test stand transmission 1 is configured such that for a step-up or step-down from the torque input shaft 2 to the torque output shaft 3 the through-shifting element 5 is activated and at the same time the coupling element 6 is deactivated. That is to say, the torque of the torque input shaft 2 is transmitted to the power-split transmission 4 via a torque input toothing 7 arranged on the through-shifting element 5, since, in the activated state of the through-force element 5, the torque input toothing 7 is fixed to the torque input shaft 2 and the torque input toothing 7 thus rotates at the rotational speed of the torque input shaft 2.At the same time, in this shifting configuration, the coupling element 6, which can be a claw clutch, a clutch sleeve or any other clutch type, is deactivated, i.e. the coupling element 6 between the mutually opposite shaft ends of the torque input shaft 2 and the torque output shaft 3 is decoupled and does not transmit any torque between the torque input shaft 2 and the torque output shaft 3.The torque transmitted from the torque input shaft 2 to the torque input toothing 7 is further transmitted via the power-split transmission 4 to a torque output toothing 8 arranged on the torque output shaft 3 and is thus relayed to the torque output shaft 3. As shown in FIG. 3, the power-split transmission 4 is realized here by three intermediate shafts 9, which are arranged in planetary fashion around the torque input shaft 2 and torque output shaft 3. It should be noted that neither equal distances nor parallelism is required, but has advantages. Depending on the step-up or step-down settings of the test stand transmission 1, different intermediate shaft toothings 10 with different diameters and numbers of teeth are arranged on the intermediate shafts 9.The above shifting configuration of the first exemplary embodiment of the test stand transmission 1 can, however, also be reversed, i.e. the through-shifting element 5 is deactivated and the coupling element 6 is activated. In this state, the torque of the torque input shaft 2 is not transmitted to the torque input toothing 7 and therefore does not pass the path via the power-split transmission 4, but is transmitted directly and without transmission or reduction via the coupling element 6 to the torque output shaft 3.FIG. 2 shows a second exemplary embodiment of the test stand transmission 1, which enables three different steps-up or steps-downs, but is designed without a gear shift. In this embodiment of the test stand transmission 1, there is no shift element at all on the torque input shaft 2, so that the torque input toothing 7 transmits the torque alternatively to the power-split transmission 4. Three of the four intermediate shaft toothings 10 are in each case located on the intermediate shafts 9 of the power-split transmission 4 in engagement with torque output toothings 8 of the torque output shaft 3.Depending on the desired transmission ratio, one of the three available through-shift elements can be activated, while the other two through-shift elements 5 are inactive, so that their torque output gear teeth 8 do not transmit torque to the torque output shaft 3. In other words, precisely one through-shifting element 5 with an associated torque output toothing 8 can always be selectively activated on the torque output shaft 3, so that a total of three different transmission ratios can be realized.As already mentioned above, FIG. 3 shows a test stand transmission 1 with a power-split transmission 4 which has three intermediate shafts 9. The test stand transmission 1 shown in FIG. 3 is the second embodiment.FIG. 4 shows a first embodiment of a liquid feed integrated into the test stand transmission 1. In this case, the torque output shaft 3 is designed as a hollow shaft 3 and a fixed line / lance 11 is inserted into the torque output shaft 3 along the central axis of the torque output shaft 3. The fixed line 11 does not itself rotate during operation of the test stand transmission 1. Thus, only the torque output shaft 3 or hollow shaft 3 and the sleeve 13 which partially surround the fixed line 11 rotate.With the above embodiment, it is possible to efficiently supply a test object of the test stand transmission 1 with liquid via the torque output shaft 3 in a space-saving manner and with comparatively little constructive complexity.A second embodiment of a liquid feed integrated into the test stand transmission 1 is shown in FIG. 5. In this case, the torque output shaft 3 is supplied with liquid via a rotary feedthrough 14, which has a static shaft sleeve 15 with a stator line 16 and a rotor part 17 of the rotary feedthrough 14 rotating in the shaft sleeve 15 (also referred to as a liquid rotor).The coolant flow flows via the stator line 16 into a stator part 18 of the rotary feedthrough 14, from where the coolant flows into the rotor part 17 via coolant inlet openings 19 which are located on the outer side of the rotor part of the rotary feedthrough 17 surrounded by the shaft sleeve 15. The rotor part of the rotary feedthrough 17 is in turn connected in a rotationally fixed manner to the torque output shaft 3, which is designed as a hollow shaft 3, and rotates therewith.The liquid introduced into the rotor part of the Derh leadthrough 17 via the coolant inlet openings 19 is introduced via a longitudinal bore 20 of the rotor part of the rotary leadthrough 17 which is open toward the torque output shaft 3 into a hollow shaft longitudinal bore 21 which adjoins the torque output shaft 3 in the longitudinal direction, from where the liquid is conducted further to the test object and the supply of the latter with the medium is ensured.It can be envisaged that the coolant supply is integrated into the coupling element 6. The coolant is in this case conducted via a closable coolant inflow channel into a connection channel of the coupling element 6. From there, the coolant flows further into a lance for liquid supply / cooling lance, which projects from the coupling element 6 perpendicularly and centrally centered with respect to the longitudinal axis thereof and projects via the sleeve 13 for closing the hollow shaft into the torque input shaft 3, so that the liquid / the coolant is transported via the torque input shaft 3 to the test object.A particular embodiment of the liquid supply / coolant supply could be configured such that the cooling of the test object takes place only as long as the coupling element 6 is decoupled and thus no direct torque transfer takes place between the torque input shaft 2 and the torque output shaft 3, but instead the torque transfer takes place from the torque input shaft 2 via the power-split transmission 4 to the torque output shaft 3 and due to the resulting transmission ratio a significantly increased speed increase is achieved at the torque output shaft 3, which requires an additional liquid supply / cooling.In order that the coupling element 6 with integrated liquid supply / coolant supply can be coupled to the torque output shaft 3, the coupling element 6 is displaced axially in the direction of the torque output shaft 3 via an adjustment mechanism (not shown) and pushed over an outer circumferential section of the hollow shaft end sleeve 13. In this switching position of the coupling element 6, a first internal toothing of a first inner radius of the coupling element 6, the central axis of which is coaxial to the longitudinal axes of the torque input shaft 2 and torque output shaft 3, engages in an external toothing of the end piece of the torque input shaft 2 facing the torque output shaft 3.At the same time, in this switching position, a second internal toothing of a second inner radius on the opposite side of the coupling element 6 engages in a toothing of the outer circumferential section of the sleeve 13 for closing the hollow shaft, so that the coupling element 6 is coupled to both the torque input shaft 2 and the torque output shaft 3 and a direct torque transmission takes place between the two shafts without transmission or reduction.Due to the above-described axial displacement of the coupling element 6 for the coupled switching position, the access of the connection channel of the coupling element 6 located on the outer circumference of the coupling element 6 is likewise displaced, so that the coolant supply between the inflow channel and the connection channel is interrupted in a targeted manner. This coolant supply interruption is expedient since the relatively lower rotational speeds occurring during the drive-through operation do not require any additional cooling.Furthermore, clamp-shaped torsion damping elements 22 are shown in FIG. 6, which are arranged between the toothing elements 23 of the torque output toothing 5 and the torque output shaft 3 in order to reduce torque irregularities due to tooth interventions in the test stand transmission 1, which could interfere with the measurement of the operating data on the test object.Finally, FIG. 7 shows the assembled state of the integrated torsion damping elements 22 between the torque output toothing 8 and the torque output shaft 3.List of reference characters1 Test stand transmission 2 Torque input shaft 3 Torque output shaft or hollow shaft 4 Power-split transmission section 5 Through-shifting element 6 Coupling element 7 Torque input toothing 8 Torque output toothing 9 Intermediate shafts 10 Intermediate shaft toothing 11 Fixed line 12 Intermediate space 13 Hollow shaft end sleeve 14 Rotary bushing 15 Static shaft sleeve 16 Stator line 17 Rotor part of the rotary bushing 18 Stator part 19 Coolant inlet openings 20 Longitudinal bore of the rotor part 21 Hollow shaft longitudinal bore 22 Torsion damping elements 23 Toothing elements for receiving damping elements

Claims

Test stand having a test stand transmission (1) having a torque input shaft (2) and a torque output shaft (3), wherein the torque output shaft (3) is prepared in order to couple to a test object, such as a high-speed electric motor, and wherein a power-split transmission section (4) is present between the torque input shaft (2) and the torque output shaft (3), which makes it possible to transfer torque from the torque input shaft (2) to the torque output shaft (3) on different force flow paths which are separate from one another, characterized in that at least one shift element is present between the power-split transmission section (4) and the torque input shaft (2) and / or the torque output shaft (3), which shift element is configured to make possible or make impossible a torque transfer depending on the shift position.Test stand with a test stand transmission (1) according to Claim 1, characterized in that the at least one shift element is a coupling element (6) which is configured to directly couple the torque input shaft (2) and torque output shaft (3) at the respectively mutually opposite shaft ends.Test stand with a test stand transmission (1) according to Claim 1 or 2, characterized in that the torque input shaft (2) and / or the torque output shaft (3) have at least one shift element which is a through-shift element (5) which is arranged between the torque input shaft (2) and a torque input pinion (7) located thereon or between the torque output shaft (3) and a torque output toothing (8) located thereon and is designed to enable or disable torque transmission.Test stand with a test stand transmission according to Claim 3, characterized in that the through-switching element (5) and at least one component of the coupling element (6) are arranged on the torque input shaft (2).Test stand with a test stand transmission according to Claim 3, characterized in that only through-switching elements (5) are arranged on the torque output shaft (3) as switching elements.Test stand with a test stand transmission according to one of the preceding claims, characterized bya liquid supply in the torque output shaft (3) for feeding the test object, which either has a fixed line (11), which runs along the central axis of the hollow torque output shaft (3) and does not rotate with respect to the torque output shaft (3), or which has a rotary bushing (14), which has a static shaft sleeve (15) in which a rotor part (17) rotates, which is arranged at the end of the torque output shaft (3) facing the torque input shaft (2) and which has coolant inlet openings (19) at the circumferential sections embraced by the shaft sleeve (15) and rotates with the hollow torque output shaft (3).Test stand with a test stand transmission according to Claim 6, characterized in that the liquid feed reaches the fixed line (11) and the torque output shaft (3) via the coupling element (6).Test stand with a test stand transmission according to Claim 7, characterized in that the liquid supply takes place via the fixed line (11) as long as the coupling element (6) does not couple the torque input shaft (2) and the torque output shaft (3), and an interruption of the liquid supply takes place as soon as the torque input shaft (2) and the torque output shaft (3) are coupled directly via the coupling element (6).Test stand with a test stand transmission according to Claim 1, characterized by damping elements (22) which are arranged at connection interfaces between the torque input shaft (2) and a torque input toothing (7) and / or at connection interfaces between the torque output shaft (3) and a torque output toothing (8).Test stand with a test stand transmission according to Claim 9, characterized in that the torsion damping elements (22) are arranged between toothed elements of the coupling element (6) and the torque input shaft (2) and / or the torque output shaft (3).

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