CN112460224A

CN112460224A - Method for producing a differential gear and differential gear

Info

Publication number: CN112460224A
Application number: CN202010920986.XA
Authority: CN
Inventors: D·蔡泽; M·道梅
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2019-09-06
Filing date: 2020-09-04
Publication date: 2021-03-09
Also published as: DE102019123969A1

Abstract

The invention relates to a method for producing a differential drive, comprising the following steps: providing a first and a second housing shell, which each carry a hollow cylindrical, axially outwardly extending bearing sleeve at their shell bottom with a central bore; providing a drive gear blank with a central recess and introducing a gear ring into the outer circumference of the drive gear blank for obtaining the drive gear, and; the housing cover is assembled with the drive gear in order to obtain a transmission housing which is rigidly surrounded by the ring gear of the drive gear. The invention is characterized in that the drive gear blank is first pressed against the first housing shell and then the ring gear is introduced into the outer circumference of the drive gear blank, wherein the introduction of the ring gear is effected by means of a processing machine, in a clamping device of which a processing reference axis is predefined, the bearing sleeve of the first housing shell being clamped coaxially to the processing reference axis. The invention also relates to a corresponding differential drive.

Description

Method for producing a differential gear and differential gear

Technical Field

The invention relates to a method for producing a differential gear (Diffentialgetriebe), comprising the following steps:

-providing a first and a second housing shell, which respectively carry at their shell bottom at the central bore a hollow cylindrical, axially outwardly extending bearing socket (Lagerstutzen);

-providing a drive gear blank with a central recess and introducing a ring gear (Zahnkranz) into the outer circumference of the drive gear blank for obtaining a drive gear; and is

Assembling the housing cover with the driving gear for obtaining the transmission housing rigidly surrounded by the ring gear of the driving gear.

The invention further relates to a differential drive comprising:

first and second housing shells which are rigidly connected to one another in a coaxial orientation with their shell edges facing one another in order to form the transmission housing and which each carry a hollow cylindrical, coaxially outwardly extending bearing socket on the outside at their shell base with a bore in the middle;

a drive gear coaxially fixed at the transmission housing, the drive gear having a central recess and a ring gear engaging the transmission housing radially outwardly; and

one side gear (Achswellenrad) is mounted coaxially inside at the housing bottom of each housing shell and two differential gears (ausgleichschrad) arranged on mutually opposite sides of the central axis and respectively meshing with the two side gears, which are mounted on radially oriented pins (Bolzen) fixed at the housing shells.

Background

A differential drive of this type is known from EP 1803972 a 1.

The basic structure of a differential transmission is known to the person skilled in the art. These differential transmissions serve to distribute the torque introduced via the drive gear to two shafts extending opposite one another, wherein the shafts can have different rotational speeds depending on the output load.

In the aforementioned document, a differential gear is known, the gear housing of which, often also referred to as differential carrier (differential), is formed from two substantially structurally identical bell-shaped housing shells which are rigidly connected to one another with their facing shell edges. Between these cover edges, a drive gear is clamped, the gear body of which has an outer toothed ring and an inner central recess. These cover edges are each supported at an axially outer abutment edge (angelekonte) of the central recess of the drive gear. At two points diametrically opposite one another, the central recess is expanded into in each case one axially open pocket (Tasche) in which end regions of pins that extend radially through the transmission housing are mounted in a corresponding form-fitting manner. In this way, a direct transmission of torque from the drive gear to the bolt is ensured. Two differential gears in the form of bevel gears are rotatably mounted on the pin. These differential gears are in each case in mesh with both side gears, likewise in the form of bevel gears, which are supported at the housing bottoms in the interior of the two housing shells. When installed in the drive train of a motor vehicle, the side gears are connected in a rotationally fixed manner to flanged half shafts (achsfflanschwelle) which are introduced into the transmission housing via bearing sleeves. Within such a drive train, the torque of the drive gear can thus be distributed to the two flange half shafts, wherein a difference in the rotational speed of these flange half shafts is possible. The gear housing rotates about its central axis which is perpendicular to the pin and is coaxial with two bearing sleeves, at which the differential gear is mounted by means of radial bearings.

It has been shown that already minimal deviations in the perfect coaxiality of the drive gear to the bearing (lagering) of the transmission housing, which are attributable to manufacturing tolerances, lead to disturbing noises during operation, which reduce the acoustic comfort of a motor vehicle equipped with such a differential transmission.

Disclosure of Invention

The object of the present invention is to provide a method for producing a differential gear with improved acoustic properties and a correspondingly improved differential gear.

This object is achieved by the features of the preamble of claim 1 by first crimping the drive gear blank to the first housing shell (pressure fuegen) and then introducing the toothed ring into the outer circumference of the drive gear blank, wherein the introduction of the toothed ring is effected by means of a processing machine in the clamping device of which a processing-reference axis is predefined, in which the bearing sleeve of the first housing shell is clamped coaxially to the processing-reference axis.

In addition, in connection with the features of the preamble of claim 9, this object is achieved in that the first housing shell is pressed against the drive gear.

Preferred embodiments of the invention are the subject matter of the dependent claims.

The basic idea of the invention is to manufacture the drive gear in situ. For this purpose, the drive gear blank is first pressed against the first housing shell. The combined component is then clamped into a processing machine for forming the toothed rim on the outer circumference of the drive gear blank. In this case, the pressing takes place in the region of the bearing sleeve of the first housing shell, so that the reference axis for introducing the ring gear, for example by milling and/or grinding, corresponds precisely to the following axis: the differential produced rotates in its final bearing state about this axis in the drive train. The last-mentioned axis of rotation is defined by a bearing block (Lagersitz) provided by one of the bearing sleeves. In accordance with the invention, the compression of the combination component therefore takes place precisely at this bearing sleeve. Thus, deviations from perfect coaxiality of the drive gear and the housing support in the end-of-installation state are largely excluded, since the toothing of the drive gear is produced with reference to the axis of symmetry of the bearing sleeve. Therefore, the disturbing noise caused by the lack of coaxiality in the prior art does not occur in the differential transmission device manufactured according to the present invention. The acoustic comfort of the respective motor vehicle is therefore higher.

The problem in implementing this basic concept is that for reasons of cost and for reasons of functionally adapted component design, the housing and the drive gear are usually made of different materials and manufactured in different ways. Before the introduction of the ring gear, it is therefore necessary for the machining to fix the drive gear blank sufficiently firmly to the first housing shell. The strength of this connection is certainly not sufficient for later operation in the drive train. The strength required for this purpose is achieved by a subsequent joining step, for example by screwing. In contrast, the pressing of the drive gear blank against the first housing shell provided according to the invention has proven to be a form of (temporary) engagement which is sufficiently robust for the introduction of the ring gear and which can be achieved quickly and cost-effectively. However, this temporary engagement is not released again during the further manufacturing method of the differential transmission according to the invention and is therefore also verified at the differential transmission produced.

Although the drive gear is only configured in the partial assembly phase as explained, it is advantageous if the drive gear blank is already engaged with the first housing shell with a high degree of precision. In a preferred embodiment of the method according to the invention, it is therefore provided that the first housing shell has, at its shell edge, an outer flange projecting radially outward with a stop edge directed axially toward the shell bottom side, and that the central recess of the drive gear blank has, on one axial side, an inner flange projecting radially inward with a stop edge directed axially inward, wherein the crimping is carried out in the following manner: the stop edge of the outer flange of the first housing shell, which is thus fixed in the central recess by means of a radial force fit, abuts against the stop edge of the inner flange of the central recess of the drive gear blank. The respective flanges of the crimped components rest against one another in the assembled state at respective stop edges which serve as axial position references (positionrefrenz) which can be produced with high precision, for example, by post-machining of a first housing shell designed as a cast part or a drive gear blank designed as a turned or stamped part or also designed as a cast part. Instead, the fastening of the two components to one another in the radial direction is effected in a force-fitting manner between the wall surface of the central recess of the drive gear blank and the outer flange of the first housing shell. Those skilled in the art are familiar with the relative dimensions of these components to be selected as required to construct the desired press fit (Presssitz).

A differential drive correspondingly produced is characterized in that,

the central recess of the drive gear has, on one axial side, an inner flange projecting radially inwards, with a stop edge directed axially inwards;

the first housing shell has, at its shell edge, a radially outwardly projecting outer flange with an axially outwardly directed stop edge,

the stop edge of the outer flange of the first housing shell, which is fixed in the central recess by means of a radial force fit, rests against the stop edge of the inner flange of the drive gear.

Within the scope of a preferred embodiment of the method according to the invention, after the introduction of the ring gear and before the assembly of the transmission housing, the first countershaft gear wheel is coaxially mounted on the housing base in the interior of the first housing. The time point preferably selected after the introduction of the ring gear onto the gear body of the drive gear blank is associated with the usual machining method for introducing the ring gear. This is usually done by cutting, in particular by milling and/or grinding. In this case, the components mounted inside the housing cover have previously become soiled. The sequence preferably selected allows cleaning of the assembly of the first housing shell and the drive gear just provided, before the installation of further components, in particular the support of the first half-shaft gear.

Similarly, it is also necessary to carry out the coaxial support of the second side gear at the cover bottom portion of the interior of the second case cover. The method steps can however be carried out independently of the mounting of the first half-shaft gear, at any time after the provision of the second housing shell and before the further assembly of the transmission housing.

As explained above and known to the person skilled in the art, in the end-of-installation state the shaft gears are coupled to one another by means of a so-called differential gear. In a preferred embodiment of the method according to the invention, it is provided that after the first axle gear is mounted on the housing bottom in the interior of the first housing shell and before the transmission housing is assembled, the pin with the differential gear rotatably mounted thereon is inserted, preferably with a positive fit, into the recesses of the housing edge of the first housing shell situated radially opposite one another, so that the differential gear meshes with the first axle gear on the sides of the central axis situated opposite one another. In this way, an assembly is produced which comprises the first housing shell, the drive gear pressed against it, the first differential gear and the differential gear meshing with it, which is supported on the pin which is already firmly supported in place.

In this case, it is particularly preferably provided that the central recess of the drive gear has pockets which are radially connected to the recess of the jacket edge of the first housing jacket and open axially toward the jacket edge side, into which pockets the end regions of the inserted bolt extend tangentially with a form fit. In this way, a form-fitting torque coupling is achieved between the drive gear and the bolt, unlike in some embodiments in which the bolt is connected only in the tangential direction and not directly to the drive gear, in which preferred embodiment the torque flow is not guided on the housing, which is accordingly less loaded and can therefore be produced correspondingly more lightweight and more cost-effectively. The differential drive produced accordingly is characterized in that the ring gear of the drive gear engages radially outside around the housing edges of the two housing shells, and the end regions of the pins project tangentially with a positive fit through bearing bores (Lagerdurchbruch) into pockets in the wall of the central recess of the drive gear, which pockets are connected radially outside to the bearing bores and open axially on at least one side.

As a next step of the method according to the invention, it is preferably provided that after the second side gear is supported at the cover bottom in the interior of the second housing cover and the pin is inserted into the first housing cover, the second housing cover with its cover edge directed toward the cover edge of the first housing cover is fixed at the drive gear in such a way that two recesses at the cover edge of the second housing cover, which recesses are situated diametrically opposite one another, form two bearing bores, which preferably enclose the engaging pin in a form-fitting manner, with the recess in the cover edge of the first housing cover, which recess carries the pin, and the second side gear meshes with the differential gear. In other words, the transmission housing is thus closed by the second housing shell. The differential drive produced accordingly is characterized in that the housing rim of the housing shell has corresponding recesses which together form two bearing bores which are diametrically opposite one another and in which the pin is supported.

However, it should be noted here that the housing shells are not directly fixed to one another, for example by screwing or welding. But the second housing cover is fixed at the drive gear. The preferred design by means of a press fit between the first housing shell and the drive gear (that is to say unlike the prior art) does not cause the drive gear to jam between the two housing shells. Instead, the first housing shell is carried by the drive gear on the inner flange of the drive gear. The drive gear itself is carried by its fastening at the second housing shell. Such fixing may be achieved, for example and preferably, by screwing. In this case, it is advantageous if the second housing shell has, axially spaced apart from its shell rim, an outer collar projecting radially outward and having a stop edge directed axially toward the shell rim side, and the second housing shell is fastened in such a way that, after fastening, the stop edge comes to bear against the stop edge surrounding the central recess of the drive gear. In this way, the drive gear is fixed in the axial direction by the abutment on the one hand at the outer flange of the second housing shell and on the other hand by its engagement (by means of its inner flange) at the rear with the outer flange of the first housing shell. The differential gear unit thus produced is characterized in that the second housing shell has, axially spaced apart from its shell rim, an outer flange projecting radially outward, with a stop edge directed axially toward the shell rim side, which rests against a stop edge surrounding the central recess of the drive gear.

The cover edge of the second housing cover is configured substantially identically to the cover edge of the first housing cover with regard to the latching support. The bearing bores for the bolts, which are produced by the cooperation of the recesses of the first and second housing shells, may preferably be non-circular, so that an anti-rotational fixing of the bolts is produced when the bolt-end regions are designed accordingly. Alternatively or additionally, such an anti-rotation fixing can also be achieved in the region of the pocket of the drive gear, if present, which is coupled radially outside to the bearing perforation.

Preferably, the two housing shells are placed directly on one another with their shell edges. However, it is of course also possible within the scope of the invention to provide spacing elements or sealing elements between the cover edges, although this is not preferred.

Further details and advantages of the invention result from the following detailed description and the accompanying drawings.

Drawings

Wherein:

fig. 1 shows a perspective view of a differential drive according to the invention in a front view;

FIG. 2 is a perspective view of the differential drive according to the present invention shown in a rear view;

FIG. 3 shows a cross-sectional view of the differential drive of FIGS. 1 and 2;

fig. 4 shows a sectional view perpendicular to fig. 3 of the differential drive of fig. 1 and 2;

fig. 5 shows an exploded view of the differential drive of fig. 1 to 4; and

fig. 6 shows a partially cut-away perspective view of an intermediate stage in the production of the differential drive of fig. 1 to 5.

Detailed Description

The same reference numbers in the drawings identify the same or similar elements.

Fig. 1 and 2 show a perspective view of a differential drive 10 according to the invention in the end-of-installation state, from different viewing directions. Fig. 3 and 4 show two sectional views of the differential drive 10 from fig. 1 and 2, which are perpendicular to one another. Fig. 5 shows an exploded view of the differential drive 10. Fig. 1 to 5 are collectively discussed below.

The differential transmission 10 includes a transmission housing 20 and a drive gear 30. The transmission housing 20 is composed of two housing shells, namely a first housing shell 21 and a second housing shell 22. As can be seen in particular from fig. 4, the cover edges 211, 221 of the housing covers 21, 22 abut against one another for forming the transmission housing 20. The drive gear 30 essentially comprises a gear body 31 with a central recess 32, on the outer circumference of which a gear ring 33 is machined. The drive gear 30 is fixed to the transmission housing 20 in such a way that the inner wall surfaces of the central recess 32 overlap axially and surround the cover edges lying against one another radially in a form-fitting manner.

The

housing shells

21, 22 are of substantially bell-shaped design and carry hollow cylindrical bearing

sleeves

212, 222 at their shell bottoms in each case, their coaxial guides serving to accommodate the flange half shafts. The flanged axle shaft which extends into the differential drive 10 integrated into the drive train of the motor vehicle is not shown in the drawing. In the final mounted state in the drive train, the differential transmission is driven in rotation about its central axis via the drive gear 30. The differential gear is in this case correspondingly radially supported, wherein the outer faces of the bearing

sleeves

212, 222 serve as bearing blocks 213, 223. The torque acting on the drive gearwheel 30 is transmitted in this case to a pin 40 fixed inside the transmission housing 20, on which pin two differential gears 43 are mounted, which mesh with a first and a

second side gear

41, 42 mounted inside at the bottom of the

housing shells

21, 22.

In the differential transmission according to the present invention, the transmission case 20 and the drive gear 30 are connected to each other in a double manner. Thus, the first housing shell 21 has, at its shell edge 211, an outer flange 214, the front face of which is intended to rest in front of the shell edge 221 of the second housing shell 22, while the rear face of the outer flange, i.e. the face directed toward the bottom, forms a stop edge for the corresponding stop edge of the inner flange 34 of the drive gear 30. By the abutment of the two stop edges against one another, a defined axial relative position of the drive gear 30 and the first housing shell 21 is ensured. The fixing in this relative position is achieved by a press fit between the outer flange 214 and the corresponding axial section of the inner wall surface of the central recess 32.

In addition to the first fixing member, the housing 20 and the driving gear 30 are connected to each other by screwing. In particular, the second housing cover 22 is screwed to the gear body 21 by means of screws 45. In order to ensure a defined axial position of the second housing shell 22 relative to the drive gear 30, the second housing shell 22 has an outer flange 224, which with its shell-edge-side stop edge rests against the circumferential edge 35 of the central recess 32 of the drive gear 30.

Basically, the fixing between the transmission housing 20 and the drive gear 30 just described is sufficient to obtain the assembly stability required during operation. However, a press connection between the first housing shell 21 and the drive gear 30 is required in order to be able to produce the combined component shown in fig. 6, which is composed of the first housing shell 21 and the drive gear 30. Within the scope of the production method according to the invention, only a drive gear blank is therefore provided first, the gear body of which-the outer circumference of which has not yet been introduced with a toothed ring-at least a finally finely structured toothed ring has not yet been introduced. The blank is connected to the first housing shell 21 in a force-fitting manner by means of the described press fit. The combined components at bearing cartridge 212 may then be clamped into the processing machine. For this purpose, the clamping device of the processing machine acts on the bearing block 213. The clamping axis (which is the reference axis for machining the drive gear blank) is therefore perfectly coaxial with the axis of rotation about which the transmission housing 20 with the drive gear 30 fixed thereto rotates during operation in the end-of-installation state in the drive train. This reliably avoids disturbing noises due to an insufficient coaxiality of the teeth of the drive gearwheel 30 with respect to the actually realized rotation of the transmission housing 20.

After machining the drive gear blank, i.e. after the formation of the toothed ring 33, the resulting composite component shown in fig. 6 can be cleaned. Only then is the first half-shaft gear 31 supported at the bottom of the first housing shell 21 via a bearing washer (lagerstheibe) 44. Similarly, a second side gear 42 is supported at the bottom of the second case cover 22 via a bearing sleeve 44. As can be seen particularly well in fig. 5, the

first housing shell

21, 22 has two

edge recesses

215, 225 at its shell edge, respectively, which lie diametrically opposite one another. These edge recesses are used to accommodate the latch 40. In the embodiment shown, the bolt 40 is provided in its end region with a flat (ableachung) 401 and the edge recesses 215, 225 have a correspondingly non-circular shape, so that the bolt is positively and rotationally fixedly located in the bearing bores, which are formed by the edge recesses 215, 225 interacting in each case in pairs in the assembled state of the transmission housing 20.

In the illustrated embodiment, the pin 40 projects radially beyond the transmission housing 20 and extends into the pocket 36 in the gear body 31 of the drive gear 30. These pockets are open on one side, i.e. toward the side facing the second housing shell 22, so that the bolts 40 can be inserted together with the differential gear 43 and the associated bearing washers 44 rotatably supported thereon by a purely axial movement. The second housing shell 22 is then placed and fixed to the gear body 31 by means of screws 45.

Of course, the embodiments discussed in the detailed description and illustrated in the drawings are merely illustrative embodiments of the invention. Given the disclosure herein, a wide range of variation possibilities will be afforded to those skilled in the art. For example, the side gears, and the differential gears, as preferably provided, may be configured as corresponding bevel gears. Other configurations, such as crown and spur gear configurations, may also be implemented. Furthermore, the person skilled in the art understands that with the introduction of a ring gear, this ring gear does not necessarily have to be provided completely here; instead, the drive gear blank may already have the basic structure of the ring gear, which is then finally fine-structured in the introduction step according to the invention.

List of reference numerals:

10 differential transmission device

20 Transmission device casing

21 first housing cover

21121 cover edge

21221 bearing sleeve

21321 bearing seat

21421 outer flange

21521 edge recess

22 second housing cover

22122 cover edge

22222 bearing sleeve

22322 bearing seat

22422 outer flange

22522 edge notch

30 drive gear

31 gear body

32 central recess

33 Ring gear

34 inner flange

35 circumferential stop edge

36 pocket groove

40 bolt

401 flat part

41 first half shaft gear

42 second side gear

43 differential gear

44 bearing washer

45 screws.

Claims

1. Method for producing a differential drive (10), comprising the following steps:

-providing a first and a second housing shell (21; 22) which each carry at their shell bottom with a central through-hole a hollow cylindrical, axially outwardly extending bearing socket (212; 222);

-providing a drive gear blank with a central recess (32) and introducing a gear ring (33) into the outer circumference of the drive gear blank for obtaining a drive gear (30); and is

-assembling the housing cover (21; 22) with the drive gear (30) in order to obtain a transmission housing (20) rigidly surrounded by a ring gear (33) of the drive gear (30),

it is characterized in that the preparation method is characterized in that,

first of all, the drive gear blank is pressed against the first housing shell (21) and then the toothed ring (33) is introduced into the outer circumference of the drive gear blank,

the ring gear (33) is introduced by means of a processing machine, in a clamping device of which a processing-reference axis is predefined, the bearing sleeve (212) of the first housing shell (21) is clamped coaxially to the processing-reference axis.

2. Method according to claim 1, characterized in that the first housing shell (21) has, at its shell edge (211), a radially outwardly projecting outer flange (214) with a stop edge directed axially towards the shell bottom side, and the central recess (32) of the drive gear blank has, on one axial side, a radially inwardly projecting inner flange (34) with a stop edge directed axially inwardly,

wherein the crimping is performed in the following manner: the stop edge of the outer flange (214) of the first housing shell (21), which is thus fixed in the central recess (32) by means of a radial force fit, abuts against the stop edge of the inner flange (34) of the central recess (32) of the drive gear blank.

3. Method according to any one of the preceding claims, characterized in that after the introduction of the ring gear (33) and before the assembly of the transmission housing (20), a first half shaft gear (41) is coaxially supported at the housing bottom inside the first housing shell (21).

4. The method of any of the preceding claims, characterized in that after providing the second case cover (22) and before assembling the transmission case (20), a second side gear (42) is coaxially supported at a cover bottom inside the second case cover (22).

5. Method according to claim 3 or, with reference back to claim 3, according to claim 4, characterized in that after supporting the first axle gear (41) at the housing bottom inside the first housing shell (21) and before assembling the transmission housing (20), a bolt (40) with a differential gear (43) rotatably supported there is placed into a recess (215) of the housing edge (211) of the first housing shell (21) situated diametrically opposite one another, so that the differential gear (41, 42) meshes with the first axle gear (41) on the sides of the central axis situated diametrically opposite one another.

6. Method according to claim 5, characterized in that the central recess (32) of the drive gear (30) has a pocket (36) which is coupled radially outside to the recess (215) of the cover edge (211) of the first housing cover (21) and which is open axially towards the cover edge side, into which pocket an end region of the inserted bolt (40) extends tangentially with a form fit.

7. The method according to any one of claims 5 to 6 with reference back to claim 3, characterized in that, after the second side gear (42) is supported at the cover bottom inside the second case cover (22) and the latch (40) is put into the first case cover (21), the second housing shell (22) is fastened to the drive gear (30) with its shell edge (221) pointing toward the shell edge (211) of the first housing shell (21), so that two recesses (225) in the cover edge (221) of the second housing cover (22) lying diametrically opposite one another and a recess (215) in the cover edge (211) of the first housing cover (21) carrying the bolt (40) form two bearing bores which embrace the bolt (40), and the second side gear (42) is meshed with the differential gear (43).

8. Method according to claim 7, characterized in that the second housing shell (22) has, axially spaced apart from its shell edge (221), a radially outwardly projecting outer flange (224) with a stop edge directed axially toward the shell edge side, and in that the second housing shell (22) is fixed in such a way that the stop edge, after fixing, rests against a stop edge (35) surrounding the central recess (32) of the drive gear (30).

9. Differential transmission (10) comprising:

-a first and a second housing shell (21, 22) which are rigidly connected to one another in a coaxial orientation with shell edges (211; 221) facing one another in order to form the transmission housing (20) and which each carry a hollow-cylindrical, coaxially outwardly extending bearing socket (212, 222) on the outside at their shell bottom with a central through-opening;

-a driving gear (30) coaxially fixed at the transmission housing (20) having a central recess (32) and a ring gear (33) engaging the transmission housing (20) peripherally and radially; and

-one side gear (41; 42) each supported coaxially inside at the case bottom of each case cover (21; 22) and two differential gears (43) arranged on mutually opposite sides of the central axis and respectively meshing with the two side gears (41; 42), said differential gears being supported at radially oriented pins (40) fixed at the case covers (21, 22),

it is characterized in that the preparation method is characterized in that,

the first housing cover (21) is in pressure contact with the drive gear (30).

10. Differential transmission (10) according to claim 9,

the central recess (32) of the drive gear (30) has, on one axial side, an inner collar (34) projecting radially inwards, with a stop edge pointing axially inwards,

the first housing shell (21) has, at its shell edge (211), a radially outwardly projecting outer flange (214) with an axially outwardly directed stop edge,

wherein the stop edge of the outer flange (214) of the first housing shell (21), which is fixed in the central recess (32) by means of a radial force fit, rests against the stop edge of the inner flange (34) of the drive gear (30).

11. Differential drive (10) according to one of claims 9 to 10, characterized in that the housing edge (211, 221) of the housing (21, 22) has a corresponding recess (215, 225) which jointly forms two bearing bores lying diametrically opposite one another, in which the bolt (40) is supported.

12. A differential drive (10) as claimed in claim 10 wherein the bearing bore has a non-circular cross-section.

13. Differential drive (10) according to one of claims 11 to 12, characterized in that the ring gear (33) of the drive gearwheel (30) engages radially outwardly around a housing edge (211, 221) of both housing housings (21, 22) and the end region of the bolt (40) projects tangentially with a form fit through the bearing perforation into a pocket (36) in the wall face of the central recess (32) of the drive gearwheel (30), which pocket is coupled radially outwardly to the bearing perforation and is open axially at least on one side.

14. Differential drive (10) according to one of claims 9 to 13, wherein the second housing shell (22) has, axially spaced apart from its shell edge (221), a radially outwardly projecting outer flange (224) with a stop edge directed axially toward the shell edge side, which abuts against a stop edge (35) surrounding the central recess of the drive gear.