Planetary transmission stage and electric drive system

Abstract

The invention relates to a planetary gear stage (13) comprising a sun gear (11), a planet carrier (8) and a corresponding planet gear (10), the planet carrier (8) having a web (32) and a planet pin (9) connected to the web (32) in a rotationally fixed manner, and a ring gear (12), each of the planetary gears (10) is rotatably mounted on a respective one of the planetary pins (9). The planetary gear stage according to the invention is characterized in that the planet carrier (8) is designed as a one-piece forged part.

Description

Technical Field

[0001] The invention relates to a planetary gear stage of the type defined in detail in the preamble to claim 1. The invention also relates to an electric drive system for a motor vehicle having such a planetary gear stage. Background Art

[0002] For example, planetary gear stages that can be used in electric drive systems for motor vehicles are known from the prior art. For this, for example, reference can be made to DE 10 2019 114 139 B3, which shows a motor vehicle transmission for connecting an electric machine to a drive train.

[0003] With regard to the planetary gear stage itself, reference can also be made to DE 10 2018 211 491 A1. This describes an arrangement for supporting an output shaft designed as a web shaft of a planetary gear set. This arrangement shows a very complex planetary gear carrier, which consists of multiple components and support elements for axial support and needle bearings for radial support that are separately formed therefrom. This arrangement is extremely complex to manufacture and is therefore expensive and difficult to install.

[0004] DE 10 2009 037 005 A1 and DE 195 36 177 C2 each show a planetary gear stage in which the planet carrier with the web and the planet gear pins is formed in one piece and as a forged part.

[0005] JP S61-17 562U, DE 10 2019 218 440 A1, DE 10 2019 109 616 A1, DE 10 2019 123 264 A1, DE 10 2017 114 480 A1 and DE 10 2016 208 827 A1 respectively show other related prior arts for forming a planetary gear carrier. Summary of the invention

[0006] The object of the present invention is to provide an improved planetary gear stage and an improved electric drive system having such a planetary gear stage.

[0007] According to the invention, this object is achieved by a planetary gear stage having the features of claim 1, in particular the features specified in the characterizing part of claim 1. Furthermore, this object is achieved by an electric drive system for a motor vehicle having the features of claim 10.

[0008] Advantageous embodiments and developments of the planetary gear stage according to the invention emerge from the dependent claims which refer back to the independent claim.

[0009] The planetary gear stage comprises a sun gear, a planet carrier with associated planetary gears, and a ring gear, wherein the sun gear, the planet carrier, and the ring gear are arranged rotatably about a main axis of rotation and are therefore all coaxial with the main axis of rotation. The planet carrier itself has a web and planetary gear pins connected to the web in a rotationally fixed manner, wherein the individual planetary gears are rotatably supported on these planetary gear pins. A feature known from the prior art is the region of the planet carrier. It is designed as a one-piece forging, which comprises not only the web but also the planetary gear pins. Such a forging allows high mechanical strength with good manufacturability and is preferably a one-piece component.

[0010] According to the invention, a web carrier is provided which is welded to each planet gear pin on the side facing away from the web. In this particularly advantageous design, the web carrier at the opposite end of the planet gear pin is a component of the one-piece construction of the forged part. The web carrier is welded to the planet gear pin in order to thereby simply and efficiently complete the structure of the planet gear carrier.

[0011] The invention further provides that a plurality of planetary gear bearings are provided, each of which is arranged coaxially with one of the planetary gear pins, wherein the web carrier has a first web carrier ring, wherein each of the first web carrier rings is arranged coaxially with one of the planetary gear pins. Each of the first web carrier rings is arranged radially inside the respective planetary gear bearing with respect to the planetary gear axis of rotation of the planetary gear of the respective planetary gear pin and overlaps axially with the respective planetary gear bearing. The planetary gear bearing or the planetary gear and its planetary gear bearing are thus located between the web on one side of the planetary gear pin and the web carrier on the other side of the planetary gear pin, the web carrier having a first web carrier ring in the region of the planetary gear pin. Within the scope of this text, the terms "coaxial", "radial" and "axial" are defined with reference to the planetary gear axis of rotation of the planetary gear.

[0012] Furthermore, according to the invention, a second planet carrier bearing is provided which is arranged coaxially with the main axis of rotation and which supports the web carrier directly in radial direction relative to the second housing ring, ie without any other elements in between.

[0013] The invention further provides that the second planet carrier bearing is arranged radially inside the second web carrier ring and radially outside the second housing ring. The web carrier is thus supported on the second housing ring from the outside as viewed in the radial direction via the bearing.

[0014] The invention further provides that a first web carrier ring designed to cooperate with a planet gear pin and a second web carrier ring designed to cooperate with a planet gear carrier bearing are formed in different axial directions with respect to the axial center of the web carrier. The first web carrier ring thus protrudes beyond the center plane of the web carrier, for example, in one axial direction, in particular in the direction toward the planet gear pin, while the second web carrier ring protrudes beyond the center plane of the web carrier in the axial direction in the opposite axial direction, i.e. in the direction away from the web of the planet gear carrier.

[0015] According to a very advantageous development, it can be provided that the weld seams for welding the web carrier and the planet gear pin are arranged between the first web carrier ring and the planet gear pin. A web carrier ring with a sufficiently thick material can thus be welded to the planet gear pin in a simple and efficient manner.

[0016] The planetary gear carriers here each have a first axial abutment surface It is designed to fix one of the planetary gear bearings in the first axial direction. In this advantageous design, it can also be provided that the first web carrier rings each have a second axial abutment surface, which is designed to fix one of the planetary gear bearings in the second axial direction. The planetary gear bearings are thus fixed, for example, between a planetary gear carrier abutment surface in the region of the web and / or the corresponding planetary gear pin on the one hand and a second axial abutment surface in the region of the web carrier on the other hand. Preferably, the planetary gear bearings can now be pushed onto the planetary gear pins together with the planetary gears and fixed together with the web carrier. If the web carrier is pressed onto the planetary gear carrier or the web with a certain pressure, the required preload force of the planetary gear bearing can be obtained here. The web carrier is welded to the planetary gear pin in a state where the planetary gear bearing is prestressed with an appropriate bearing preload force. This is extremely simple and efficient and allows the planetary gear carrier to be manufactured at low cost with a small number of components and to be easy to install.

[0017] Another very advantageous embodiment of the planetary gear stage according to the invention also provides that the first planet carrier bearing is arranged radially inside a support ring of the planet carrier and radially outside a first housing ring, which is arranged coaxially with respect to the main axis of rotation. The terms "coaxial", "axial" and "radial" refer here to the axis of rotation of the planet carrier, which is also the main axis of rotation of the planetary gear stage.

[0018] The planetary gear bearings can be realized in principle in different ways. They can be designed, for example, as sliding bearings or rolling bearings. Here, for example, a separate roller bearing for each planetary gear on the corresponding planetary gear pin is a suitable solution with optimized friction characteristics. But now, according to a very advantageous improvement of the planetary gear stage of the present invention, it can also be provided that each of the planetary gear bearings has two bearings between the corresponding planetary gear pin and the corresponding planetary gear. This design with two bearings enables the support of the planetary gears to be spaced apart in the axial direction. Here, the two bearings can preferably be constructed in the form of angular contact ball bearings, which are arranged at intervals in the axial direction between the corresponding planetary gear pin and the corresponding planetary gear. Through two such angular contact ball bearings, an ideal support structure with axial and radial support can be realized in the corresponding support.

[0019] According to the above-mentioned variant of the planetary gear carrier bearing and an extremely advantageous improvement of the variant described in the present invention, it can also be provided that the two pairs of angular contact ball bearings are arranged in an O-shaped arrangement with respect to their rotational axis. Here, each pair of bearings is installed so that the pressure lines of the two angular contact ball bearings running around the same rotational axis extend outwards so that their intersection points with the corresponding rotational axis are farther away in the axial direction than the bearings themselves. This structure is generally referred to as an O-shaped arrangement and a bearing structure with ideal support is achieved here.

[0020] The electric drive system for a motor vehicle according to the invention comprises: an electric motor with a rotor and an output shaft, which is connected to, for example, a direct drive wheel or a shaft reducer, such as a differential. In addition, a planetary transmission stage described in accordance with one of the above-mentioned design variants is provided in the electric drive system for a motor vehicle. Here, the motor rotor is connected or connectable to the sun gear in a torque-transmitting manner. The ring gear is connected or connectable to the housing in a rotationally fixed manner. Within the scope of the present invention, "rotationally fixed connection" means that two coaxial elements are connected so that they rotate at the same angular speed. The planetary gear carrier itself now forms an output device and is connected to the output shaft in a rotationally fixed manner. Therefore, in summary, by using a planetary transmission stage with a particularly efficient planetary gear carrier, this electric drive system for a motor vehicle has a compact, easy to manufacture and install and therefore highly cost-effective structure.

[0021] The electric drive system is preferably designed to drive exactly one wheel of the motor vehicle, so that the electric drive axle of the motor vehicle preferably has two electric drive systems according to the invention which are arranged in mirror symmetry with respect to one another. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Further advantageous embodiments of the planetary gear stage and of the electric drive system for a motor vehicle also result from the exemplary embodiments described in more detail below with reference to the accompanying drawings, in which:

[0023] Figure 1 A schematic diagram showing an embodiment of an electric drive system for a motor vehicle according to the present invention;

[0024] Figure 2 A partial cross-sectional view showing an electric drive system using a planetary gear stage according to the present invention;

[0025] Figure 3 A three-dimensional schematic view of a planetary gear stage according to the invention is shown, viewed from the web carrier of the planetary gear carrier. DETAILED DESCRIPTION

[0026] exist Figure 1 An electric drive system 1 is schematically shown in the figure. It has an electric machine 2, which is preferably designed as an axial flux machine. It comprises a stator 30 arranged in a rotationally fixed manner relative to a housing 5 and a two-part rotor 3 connected in a rotationally fixed manner to a rotor shaft 4. The rotor shaft 4 forms the input shaft to the planetary gear stage 13 and is connected in a rotationally fixed manner to the sun gear 11. The planetary gear stage 13 also includes a ring gear 12 connected in a rotationally fixed manner to the housing 5. The planetary gear carrier 8 is connected in a rotationally fixed manner to an output shaft 18, which outputs power from the electric drive system 1, such an output device is designated by 7 and is indicated by Figure 1 The arrows shown indicate.

[0027] exist Figure 2 A partial cross-section of an electric drive system 1 is shown in the figure. Here, only the half of the rotor 3 located on the right side in the motor 2 or on the right side of the stator 30 is shown, and the rotor is supported relative to the housing 5 via a rolling bearing 6. It is connected to the multi-piece rotor shaft 4 in a rotationally fixed manner. The rotor shaft 4 is supported indirectly by the rolling bearing 6 of the rotor 3, which is designed as an angular contact ball bearing, and is also supported on the housing via a needle bearing 28. An output device 7 leading to a motor vehicle wheel or an axle reducer (such as a differential) is schematically shown on the side of the planetary gear stage 13 facing away from the motor 2 in the axial direction a. The output device 7 is here connected to the planetary gear carrier 8 as the driven part of the planetary gear stage 13 in a rotationally fixed manner via an output shaft 18 by means of a spline shaft tooth portion marked with 19.

[0028] The planetary carrier 8 has a planetary gear pin 9 pointing in the axial direction a toward the electric motor 2. Only two of the planetary gears 10 can be seen here, which are supported on the planetary gear pins 9 via planetary gear bearings 33, which are designed here in the form of two angular contact ball bearings 33.1 and 33.2. The sun gear 11 meshes with the planetary gears 10 radially on the inside, and the sun gear is formed by the tooth row of the rotor shaft 4. The ring gear 12 supplements this structure to form a planetary gear stage 13 for converting torque between the rotor 3 and the output device 7. The ring gear 12 is connected to the housing 5 in a rotationally fixed manner.

[0029] The planet carrier 8 thus comprises a planet pin 9 and a web 32, wherein the planet pin 9 is connected to the web 32 in a rotationally fixed and axially fixed manner. In the embodiment shown here, the planet gears 10 are plugged onto the planet pin 9 together with two angular contact ball bearings 33.1, 33.2 which together form a planet gear bearing 33. Alternatively, for example, a separate rolling bearing can also be provided.

[0030] The planet carrier 8, which is formed by the web 32 and the planet pin 9, is preferably designed as a one-piece forging. After the planet gears 10 and the planet gear bearing 33, here in the form of two angular contact ball bearings 33.1, 33.2, have been installed, the web carrier 34 is now installed on the side of the planet gear pin 9 facing away from the web 32. The web carrier 34 has a first web carrier ring 35 in the region of the respective planet gear pin 9, which rests in the radial direction r with respect to the planet gear rotation axis PA of the planet gear 10 between the planet gear pin 9 and the inner ring of the angular contact ball bearing 33.2 facing the web carrier 34. The other angular contact ball bearing 33.1 rests in the axial direction a against a first axial abutment surface 36, which is formed on the planet gear pin 9 or by the web 32 of the planet gear carrier 8. In the region of the web carrier 34, a second axial abutment surface 29 for the inner ring of the second angular contact ball bearing 33.2 is formed accordingly. After the planetary gears 10 and the two corresponding angular contact ball bearings 33.1, 33.2 have been inserted, the planetary gear bearing 33 can now be preloaded by pressing the web carrier 34 onto the planetary gear carrier 8. The angular contact ball bearings 33.1, 33.2 can thus be placed at the required bearing preload. When this state is reached, a weld seam 37 is provided between the web carriers 34 and in particular between the first web carrier ring 35 and the planetary gear pin 9, which extends continuously or discontinuously around the circumference of the planetary gear pin 9 or the first web carrier ring 35. The weld seam 37 now ensures that the planetary gear carrier 8 is completely assembled with the planetary gears 10 and their planetary gear bearings 33 via the web carriers 34. The structure is very simple and can be installed ideally according to the required bearing preload by pressing the web carrier 34 accordingly before welding, so that the complete assembly of the central structure of the planetary gear stage 13 can be achieved very efficiently.

[0031] The two angular contact ball bearings 33.1, 33.2 of the planetary gear bearing 33 are designed in such a way that the angular contact ball bearings 33.1 are located at the bottom of the planetary gear bearing 33. Figure 2 The pressure line d1 shown in the lower half intersects the pressure line d2 of the other angular contact ball bearing 33.2 at a distance x from the planetary gear rotation axis PA of the planetary gear 10 shown below, which is greater than the spacing between the two angular contact ball bearings 33.1 and 33.2 in the axial direction a. This structure is generally also called an O-arrangement.

[0032] The planet carrier 8 itself now has, for its own support, a first bearing ring 39 arranged coaxially to the main rotation axis HA, which is arranged in the radial direction r on the outside of a first housing ring 40 also arranged coaxially to the main rotation axis HA. An angular contact ball bearing 14.1 is arranged as a first planet carrier bearing 41 between the first bearing ring 39 of the planet carrier 8 and the first housing ring 40 of the housing 5. The angular contact ball bearing 14.1 is supported by both axial and radial forces, for which purpose a first axial surface 42 is provided on the web side and an adjustment plate 43 is provided on the housing side, wherein the adjustment plate 43 itself is supported on an axial surface (not shown in detail) of the housing cover 5.1 of the housing 5. As a second planet carrier bearing 44, an angular contact ball bearing 14.2 is also provided, which is arranged radially between a second housing ring 45 and a second web carrier ring 38, which is designed here at the same time as a second bearing ring for supporting the planet carrier 8. The planet carrier bearing 44 is supported on the web carrier side on a second axial surface 46. The support takes place on the housing side on an axial surface of the second housing ring 45 which is not indicated in detail here.

[0033] The two angular contact ball bearings 14.1 and 14.2 as the first and second planetary gear carrier bearings 41, 44 are now also arranged in an O-shaped manner similar to the two angular contact ball bearings 33.1, 33.2 of the planetary gear bearing 33, but are arranged with respect to the main rotation axis HA. This also means that the pressure line D1 of the first angular contact ball bearing 14.1 and the pressure line D2 of the second angular contact ball bearing 14.2 intersect the main rotation axis HA at a distance, which is indicated here by y, which is greater than the spacing of the bearings themselves in the common axial direction a. The main rotation axis HA is the common rotation axis of the sun gear 11, the planetary gear carrier 8 and the ring gear 12.

[0034] exist Figure 3 In the illustration of FIG. 1 , the planetary gear stage 13 is again shown in a three-dimensional schematic diagram. For the sake of simplicity, the tooth arrangement is omitted here. Figure 3 The outermost part is shown in the form of a ring 12, in which three planetary gears 10 run in the embodiment shown here. The planetary gear carrier 8 or its web 32 is shown to be substantially enclosed by the planetary gears 10. Planetary gear pins 9 are arranged on the planetary gear carrier, on which the planetary gears 10 are respectively supported. It can be seen that the structure is largely enclosed here by the web carrier 34, which is welded to the planetary gear pins 9 via weld seams 37 in the region of a first web carrier ring 35, which cannot be seen here because it protrudes inwards. In the center of the web carrier 34 region, a second web carrier ring 38 is shown, by which the planetary gear carrier 8 is supported on one side axially. Figure 3 The center of the structure shown is also related to Figure 2 The illustration of shows the sun gear 11 and the rotor shaft 4 in a similar manner.

[0035] The overall support of the planetary gear stage 13 is now designed such that the planetary gear bearing 33 is arranged axially between the two planetary carrier bearings 41, 44. As described above, the sun gear 11 is supported accordingly via the rotor shaft 4 and thus via the bearing 6 and the needle bearing 28 shown in the region of the second housing ring 45. Another bearing can be formed in the region of the second half of the rotor 3 on the other side of the electric machine 2 in the axial direction a (not shown here again).

[0036] As shown above, the housing 5 consists of a housing cover 5.1 and a section 5.2 designed as a housing base, which is therefore designed in one piece. From the housing cover 5.1 side, the entire structure is now assembled so that the electric motor 2 is first installed and its stator 30 is correspondingly fixed, for example, by the screw connection 31 shown. Then, the individual components of the planetary gear stage 13 and the planetary gear carrier 8 composed of the web 32, the planetary gears 10 and the web carrier 34, which have been completely assembled before, are inserted. The bearing preload in the planetary gear bearing 33 is already generated here by pressing and welding the web carrier 34. The bearing preload for the two planetary gear carrier bearings 41, 44 can be adjusted accordingly during assembly by means of the adjustment plate 43, because the second housing ring 45 is formed in the housing base 5.2, and the first housing ring 40 is formed in the housing cover 5.1. Therefore, when the housing cover 5.1 is fixed to the housing base 5.2 of the housing 5 by means of the screw connection 47 shown, the bearing preload can be adjusted by means of a suitable adjustment plate 43.

[0037] As described above, the output shaft 18 can then be coupled to the planetary carrier 8 in a rotationally fixed manner via the splined shaft toothing 19 so that, for example, individual wheels or a shaft reduction device, such as, in particular, a motor vehicle differential, can be electrically driven via the output 7 .

[0038] Reference numerals list

[0039] 1 Electric drive system

[0040] 2 Motor

[0041] 3 Rotor

[0042] 4 Rotor shaft

[0043] 5 Housing

[0044] 5.1 Housing cover

[0045] 5.2 Shell base

[0046] 6 (Rotor) bearing

[0047] 7 Output Devices

[0048] 8 Planetary gear carrier

[0049] 9 Planetary gear pin

[0050] 10 Planetary gear

[0051] 11 Sun gear

[0052] 12 Ring gear

[0053] 13 planetary gear stages

[0054] 14.1 Angular contact ball bearing for first planetary gear carrier bearing

[0055] 14.2 Angular contact ball bearing for the second planetary gear carrier bearing

[0056] 18 Output shaft

[0057] 19 Spline shaft teeth

[0058] 28 Needle roller bearing

[0059] 29 Second axial abutment surface abutting against the web frame

[0060] 30 Stator

[0061] 31 Threaded connection of stator

[0062] 32 belly plate

[0063] 33 Planetary gear support device

[0064] 33.1 Angular contact ball bearings

[0065] 33.2 Angular contact ball bearings

[0066] 34 belly plate frame

[0067] 35 First web frame ring

[0068] 36 A first axial abutment surface abutting against the planetary gear pin

[0069] 37 Weld

[0070] 38 Second web frame ring

[0071] 39 First support ring

[0072] 40 First casing ring

[0073] 41 First planetary gear carrier bearing

[0074] 42 First axial surface on web

[0075] 43 Adjustment ring

[0076] 44 Second planetary gear carrier bearing

[0077] 45 Second shell ring

[0078] 46 Second axial surface of the web frame

[0079] 47 Threaded connection of housing cover

[0080] a Axial direction

[0081] D1, D2 pressure line

[0082] d1, d2 pressure lines

[0083] HA Main axis of rotation

[0084] PA Planetary gear rotation axis

[0085] r Radial direction

[0086] X distance

[0087] y distance.

Claims

1. A planetary gear stage (13) comprising: a sun gear (11); a planetary gear carrier (8) and corresponding planetary gears (10), the planetary gear carrier being arranged to be rotatable about a main axis of rotation (HA); and a ring gear (12), wherein: The planetary gear carrier (8) has a web (32) and a planetary gear pin (9) connected to the web (32) in a rotationally fixed manner, wherein each of the planetary gears (10) is rotatably mounted on one of the planetary gear pins (9). The planetary gear carrier (8) is designed as a one-piece forging. It is characterized in that A web frame (34) is provided, which is welded to the planetary gear pins (9) on the side facing away from the web (32). A planetary gear support device (33) is provided, wherein each of the planetary gear support devices (33) is arranged coaxially with one of the planetary gear pins (9), wherein the web frame (34) has a first web frame ring (35), wherein each of the first web frame rings (35) is arranged coaxially with one of the planetary gear pins (9), wherein each of the first web frame rings (35) is arranged radially inside the corresponding planetary gear support device (33) with respect to the planetary gear rotation axis (PA) of the planetary gear (10) of the corresponding planetary gear pin (9) and axially overlaps with the corresponding planetary gear support device, A second planetary gear carrier bearing (44) is provided, which is arranged coaxially with the main rotation axis (HA) and directly supports the web carrier (34) radially relative to the second housing ring (45). The second planetary gear carrier bearing (44) is arranged radially inside the second web carrier ring (38) and radially outside the second housing ring (45). The first web frame ring (35) and the second web frame ring (38) are formed on the web frame (34) in opposite axial directions.

2. The planetary gear stage (13) according to claim 1, It is characterized in that The welds (37) used for welding the web frame (34) and the planetary gear pin (9) are arranged between the first web frame ring (35) and the planetary gear pin (9).

3. The planetary gear stage (13) according to claim 1 or 2, It is characterized in that The planetary gear carriers (8) each have a first axial abutment surface (36), and the first axial abutment surface is designed to fix one of the planetary gear support devices (33) in the axial direction along a first direction.

4. The planetary gear stage (13) according to claim 3, It is characterized in that The first web frame rings (35) each have a second axial abutment surface (29), and the second axial abutment surface is designed to fix one of the planetary gear support devices (33) in the axial direction along the second direction.

5. A planetary gear stage (13) according to any one of the preceding claims, It is characterized in that A first planet carrier bearing (41) is arranged radially inside a first support ring (39) of the planet carrier (8) and radially outside a first housing ring (40) which is arranged coaxially with the main axis of rotation (HA).

6. The planetary gear stage (13) according to claim 5, It is characterized in that The first planetary gear carrier bearing (41) has a first angular contact ball bearing (14.1), and the second planetary gear carrier bearing (44) has a second angular contact ball bearing (14.2).

7. A planetary gear stage (13) according to any one of the preceding claims, It is characterized in that Each of the planet gear bearings (33) comprises two bearings (33.1, 33.2) between a corresponding planet gear pin (9) and a corresponding planet gear (10).

8. The planetary gear stage (13) according to claim 7, It is characterized in that The two bearings are designed in the form of two angular contact ball bearings (33.1, 33.2), which are arranged in a spaced-apart manner in the axial direction (a) between the corresponding planetary gear pin (9) and the corresponding planetary gear (10).

9. A planetary gear stage (13) according to claim 6 and / or claim 8, It is characterized in that At least one pair of angular contact ball bearings of the two pairs of angular contact ball bearings (33.1, 33.2; 14.1, 14.2) of the planetary gear (10) and / or the planetary gear carrier (8) is arranged in an O-shaped arrangement about its corresponding rotation axis (PA; HA).

10. An electric drive system (1) for a motor vehicle, comprising: an electric machine (2) with a rotor (3), an output shaft (18) and a planetary gear stage (13) according to any one of the preceding claims, It is characterized in that The rotor (3) is connected or can be connected to the sun gear (11) in a torque-transmitting manner, the ring gear (12) is connected or can be connected to the housing (5) in a rotationally fixed manner, and the planet carrier (8) is connected to the output shaft (18) in a rotationally fixed manner.

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