PLANET CARRIER ASSEMBLY, SHAFT-HUB CONNECTION, AND METHOD FOR PRODUCING THE SHAFT-HUB CONNECTION BETWEEN A CARRIER FLANGE AND A CARRIER FROM THE PLANET CARRIER ASSEMBLY

A planet carrier assembly includes a rotational axis, a carrier and a carrier flange. The carrier has circumferentially spaced first driver elements formed thereon and the carrier flange has circumferentially spaced second driver elements formed thereon. The second driver elements are interconnected with the first driver elements at common contact areas in an interlocking manner. The carrier flange is axially secured to the carrier in an axial direction by plastically deformed material at the common contact areas. In an example embodiment, the plastically deformed material is displaced from the first driver elements or the second driver elements.

TECHNICAL FIELD

The present disclosure relates to a planet carrier assembly having at least a carrier flange and a carrier. The carrier flange is arranged to be concentric to a rotational axis of the planet carrier assembly and the first driver elements of the carrier formed on the carrier and second driver elements of the carrier flange formed on the carrier flange are connected in a form-fit manner to one another in circumferential directions around the rotational axis. The carrier flange and the carrier are axially secured to one another by means of at least one axial fixing means in the same direction as the rotational axis by means of at least one axial fixing means. The present disclosure also relates to a shaft-hub connection between the carrier and the carrier flange and a method for producing the shaft-hub connection.

BACKGROUND

A planet gear system of a planet carrier assembly is disclosed in DE 11 2012 000 461 B4. The planet gear system is formed by planet gears, planet pins, and the planet carrier assembly. The planet carrier assembly is made up of various components. One component is a planet carrier made up of two carrier flanges and the other component is a shaft with a radial flange. The planet carrier has two carrier flanges made of sheet metal, which are connected to one another axially by webs and planet pins. The planet carrier and the shaft are non-detachably materially bonded to one another. According to the embodiment shown in FIG. 1 of DE 11 2012 000 461 B4, one of the carrier flanges has a through-hole with an internal cylindrical guide surface. The inside diameter of the guide surface corresponds in nominal size to the outside diameter of an external cylindrical guide surface on the flange. The carrier flange is placed and supported on the flange in such a way that the internal cylindrical guide surface and the external cylindrical guide surface lie concentrically and radially on one another and the planet carrier is thus guided concentrically to the shaft. An annular shoulder of the carrier flange, the inner diameter of which is smaller than the outer diameter of the external cylindrical guide surface on the flange, axially adjoins the through-hole. This annular shoulder forms an axial stop. The axial stop ensures that the two joining surfaces are axially aligned with one another and are not axially offset from one another. The axial stop is also part of an axial fixing means in one axial direction. The other part of the axial fixing means is a weld seam, at which the planet carrier and the shaft are non-detachably connected to each other with a material bond.

A combination of connection techniques using positive locking and welding is described using a planet carrier assembly published with DE 10 2012 223 226 A1. The planet carrier assembly is rotatably supported on a shaft by means of a hub. The connection between one of the carrier flanges of the planet carrier and the hub is made by a form-fit driver element toothing connection in the form of serrations. In addition, the carrier flange is axially secured to the hub by means of weld seams.

A generic connection between the carrier flange and the shaft of a planet carrier assembly is disclosed in DE 10 2007 003 676 A1. The connection is made in the classic way via the mutual form-fit of driver element teeth. The carrier flange is provided with form-fit elements on the inside, in which suitably outer form-fit elements of an intermediate piece engage. The intermediate piece is designed like a hub and has the outer driver elements on the outside and the inner driver elements on the inside. The internal driver elements are implemented as serrations and are provided for a shaft-hub connection between the planet carrier assembly and a shaft. This connection is supported by a parallel sliding or press fit with which the carrier flange sits on the hub. As an additional safeguard for this form-fit connection, a caulking of the form-fit connection is provided in DE 10 2007 003 676 A1, through which material is displaced from the hub and/or the carrier flange into the sliding fit and which blocks it in axial directions.

Also generally known are shaft-hub connections, e.g., from DE69424245T2, which are formed from a combination of a form-fit via serrations and axial securing by means of plastically displaced material.

SUMMARY

The present disclosure provides a planet carrier assembly in which a connection between the carrier and the carrier flange can be produced easily and inexpensively.

The disclosure provides that the carrier flange and the carrier aligned in the circumferential directions about the rotational axis at common contact areas in the circumferential directions interlock in a form-fit or optionally also mutually engage in an interlocking and force-locking manner, and are non-detachably connected to one another. According to the disclosure, the axial fixing means is integrated into the form-fit or interlocking and force-locking engagements. The driver elements, which engage in one another in a form-fit manner, are pressed against one another in the circumferential direction around the rotational axis or in the tangential direction to the rotational axis, and are also held together axially by undercuts lying in the axial directions.

The disclosure provides that both the production of the components of the planet carrier assembly and the connections of these components can be produced exclusively by cold forming such as stamping, embossing, and extrusion, and machining steps and welding can be avoided.

The present disclosure also provides a shaft-hub connection between a carrier flange and a carrier of a planet carrier assembly and a method for producing this shaft-hub connection.

The manufacturer's existing machines for manufacturing the components, such as stamping or pressing, can be used without needing to invest in cost-intensive welding systems. The carrier or the shaft is largely produced by cold extrusion, and the flank geometry of the radial projections is formed at the same time. The carrier flange, including the inner contour with the form-fitting elements, is optionally produced using individual methods or shaping methods combined in a specific sequence, for example by punching, drawing, and bending. The plug-in connection between the hub or shaft and the carrier flange is produced by means of embossing or rolling, or with other suitable plastic shaping processes. Alternatively, the spline toothings are extruded or, for example, stamped on the sheet metal hub. From this point of view, the only necessary investment costs are for the punching, bending, or extrusion tools. The energy consumption in producing the component connections is lower. Negative consequences of welding such as distortion or weld spatter are avoided. The preparation and post-processing of the connection points required for welding are no longer necessary.

Carriers are components that are suitable for receiving one or more carrier elements of the planet carrier of the planet carrier assembly. These are, for example, shafts, shaft ends, axles, bolts, housing parts, etc.

Carrier flanges are all components that have at least one bearing point for a journal of a planetary bearing or for a planetary bolt. The carrier flange may be a component made of steel, which is mainly produced by non-material-removing methods. An example embodiment of the carrier flange is a sheet metal part, which is optionally produced by methods such as stamping, bending, drawing, or embossing, or by combinations thereof.

Axial is always aligned with or parallel to the rotational axis, regardless of the orientation of the rotational axis in space. Accordingly, radial is directed to be transverse to the direction of the rotational axis and towards the rotational axis.

A non-detachable or undetachable connection can only be released again by destroying structures or material of the components connected to one another or axially secured to one another, such as the carrier and carrier flange.

Non-detachable connections within the meaning of the disclosure are form-fit/force-fit connections which, according to one embodiment, are formed by material which is plastically displaced from at least one of the driver elements. Known processes for the formation of plastic deformations are caulking, squeezing and embossing, possibly extrusion and rolling. The deformation may be produced by stamps acting in the axial direction. For example, material is plastically displaced from the end faces facing in the axial directions, on one side or on both sides, towards the flanks of the driver elements that lie against one another. These are pressed against one another in a force-fit manner and thereby wedged together and secured axially against one another by protruding plastically displaced material.

Material is the material or materials from which either the beam or the beam flange or both the beam and the beam flange are made, and which is monolithically formed with the beam or the beam flange.

First of all, the welded connection known from the prior art offers itself as a reliable connection between the flange and the beam flange. Due to the shape of the carrier flanges and the relatively large dimensions, the investment costs for the assembly and welding devices of such assemblies are relatively high. Laser welding is a common process in use. Welding has disadvantages due to the process. The energy consumption during production is high with the corresponding negative CO2 emissions. The thermal energy introduced during welding can lead to warping due to the shape and dimensional accuracy of the components. Welding spatter occurs during welding, which can have a negative effect on the machining process or on the subsequent function of the planetary gear. As a rule, the components must be prepared for welding before they are manufactured, just as the welds must be reworked afterwards.

An embodiment provides that the first driver element and the second driver element lie against one another in the circumferential directions. A convex contour on one of the driver elements engages in a form-fit manner in a tangential direction or in the circumferential direction in a concave contour on the other driver element. The convex contour is axially engaged from the rear at two positions pointing away from each other axially by two axially opposite projections on the concave contour, each of which forms an axial fixing means in one of the axial directions. The projections are formed from plastically displaced material of the driver element from one of the driver elements or from both driver elements. Such flank-side contact is advantageous through the flanks of mutually engaging connections typical of shaft-hub connections via splines or serrations, in which the driver elements/teeth are aligned in the axial direction and the flanks are aligned in the circumferential direction or tangentially, and in which the teeth of the hub and the teeth of the shaft are mutually engaging.

Tangent is tangent to the circumferential direction about the rotational axis. The circumferential direction always runs on a circle or a circular area, the center of which is penetrated perpendicularly by the rotational axis.

A contour is an area or at least a contour line running between two points.

Concave and convex contours are defined in any parallel longitudinal sections through the driver element and through the form-fit engagement based on their position to an engagement path. The respective imaginary path of contact runs in the respective longitudinal section plane considered between points that lie on the respective contour line. The first point is on a first of the protrusions on the concave contour line and the second point is on the same contour line on the axially opposite second protrusion. Both projections protrude in the direction of the driver element with the convex contour and form undercuts which engage behind the convex contour at specific positions in the axial direction.

The concave contour is defined by the fact that its contour line is behind the imaginary engagement path. This means that the gap running in the considered longitudinal section plane between the concave contour line and the engagement path is not filled with the material of the driver element with the concave contour. In the same longitudinal section, the convex contour protrudes beyond the line of contact. That is, the gap formed in this longitudinal sectional plane between the convex contour line and the path of engagement is at least partially filled with the material of the driver element having the convex contour (see also the description ofFIGS.5and12).

The respective contour line runs in any spherically curved and/or straight line between the points, changing direction or linearly rising or falling, and can change direction as desired within the limits specified by the gap. In this case, straight means running in the axial direction or inclined in a straight line to the axial direction.

DETAILED DESCRIPTION

FIGS.1,2,3—The planet carrier assembly1is formed from a carrier3and a carrier flange2. The carrier3is a shaft20, for example a transmission shaft of an automatic transmission, not shown, of a motor vehicle, not shown, which is designed in one piece with a flange16. The carrier flange2is a sheet metal plate on which receptacles17are perforated for planet bolts, not shown, of a planetary drive, not shown. The carrier flange2is arranged to be concentric to the rotational axis4on the carrier3or with a hub18on the flange16of the shaft20.

FIGS.1and6—On the inside, the carrier flange2is provided with an internally toothed through-hole (seeFIG.6), which is the basis of a hub18of a shaft-hub connection10between the carrier flange2and the shaft20shown inFIG.1.

FIG.4—A detail of the shaft-hub connection10is shown. First driver elements5formed on the flange16of the carrier3and second driver elements6formed on the hub18of the carrier flange2are connected to one another in opposite circumferential directions about the rotational axis4in a form-fit or an interlocking and force-locking manner. The driver elements5are teeth of a driver element shaft profile11designed as a spline or serration. The teeth are distributed in the circumferential direction around the rotational axis4on the circumference of the flange16, and each protrude radially out of the flange16into one of the tooth spaces of the driving hub profile12. The driver element hub profile12is formed on the hub18and is formed from the second driver elements6, which each engage in a form-fit manner radially in the direction of the shaft20at a form-fit engagement7and engage in a form-fit manner in a tooth gap formed between the first driver elements5and completely fill this tooth gap.

FIGS.6and7—The driver element shaft profile11consists of a number of first driver elements5distributed around the rotational axis4, which are each separated from one another by tooth gaps21. The carrier hub profile12is formed by a number of second driver elements6distributed around the rotational axis4, which are separated from one another in the circumferential direction by a tooth gap19in each case. Before assembly, the carrier3and the carrier flange2are aligned with one another on the rotational axis4such that a first driver element5is axially opposite a tooth gap19of the driver element hub profile12and a second driver element6is axially opposite a tooth gap21of the driver element shaft profile11.

FIG.7—The flanks24of the first driver element5have a convex profile, which is arched out of the driver element5into the respective tooth gap21. There are two flanks24of adjacent first driver elements tangentially or in the circumferential direction opposite each other at the respective tooth gap21. The flanks25of the second driver element6face each other at the respective tooth gaps19as parallel and mutually inclined surfaces.

FIGS.8,9, and10—In a further method step, the carrier3and the carrier flange2are pushed axially into one another. The carrier flange2with the hub18is slid onto the flange16in such a way that the first driver element5and the second driver element6form a form fit due to the mutual engagement.

FIG.10—Via the form fit, torques can be transmitted in the circumferential direction about the rotational axis4between the carrier3and the carrier flange2via the flanks24of the first driver element6rest against the flanks25of the second driver element6in the circumferential direction. For this, the first driver elements engage in tooth gaps19which are formed between the second driver elements6. When the driver element shaft profile11and the driver element hub profile12are plugged into one another axially and in the circumferential direction in a form-fit manner according to one method step, the respective second driver element6is aligned in a tooth gap21in such a way that each convex flank24of the respective first driver element5corresponds to an axially aligned flank25parallel to one of the second driver elements6in the circumferential direction about the rotational axis4or tangentially opposite thereto.

FIGS.7and10—The flanks of the teeth or the first driver element5are provided with bevels22, which are inclined towards the axially facing end faces of the teeth at the angle bt (cf.FIG.10) and slope downward. The bevels22of adjacent driver elements5face each other in the tangential direction, are flat in this case but can also be spherical, and determine the contour of the convex profile. The flanks25of the second driver element6are flat and run axially and parallel to one another at each of the tooth gaps19, and are radially inclined with respect to one another.

FIG.11a—In the section running in a radial plane through a tooth gap21, the view falls on a flank24of a first driver element5having the bevels22. The base27of the tooth gaps21, where the driver element merges into the flange16, drops down at the bevels23inclined with the angles Bx towards the axial end sides of the flange16, so that in each tooth gap21a profile of the tooth gap21protruding radially outwards into the tooth gap21is formed at the base27.

FIG.11—The figure shows a longitudinal section of a second driver element6engaging in the tooth gap21. The broken lines indicate a first driver element5. Deviating from previous illustrations, the carrier flange2with the width W is shown wider than the flange16with the width T on the form-fit contact areas7. The following ratios of dimensions W and T are possible: T≥W (not shown) or W≥T. Possibly, material accumulations are created by the width differences, which provide sufficient material which is plastically displaced to form the axial fixing means. When the driver element shaft profile11and the driver element hub profile12are inserted axially into one another in a method step, and thus engage in a form-fit manner in one another in the circumferential direction, the respective second driver element6is aligned in a tooth gap21in such a way that the, for example, flat or straight contour37on the head of the respective second driver element6is radially opposite the convex profile at the base27of the tooth gap21.

FIGS.1,2,3,4,5, and12—In the pre-assembly assembly described withFIGS.8,9,10, and11, torques can already be transmitted in the circumferential direction around the rotational axis via the form-fit engagement of the driver element teeth. However, this pre-assembly assembly lacks the axial securing of the carrier and carrier flange against one another or against one another. On the other hand,FIGS.1,2,3,4,5, and12describe the finished planet carrier assembly1, in which form-fit or interlocking and force-locking connections between the driver element profiles are formed according to the disclosure. The interlocking and force-locking connections unfold their effect both in the axial direction as an axial fixing means and as an additional effect the tangential or circumferential clearance of the connection.

FIGS.4and8or9—Starting from the pre-assembly9shown inFIG.8or9, in the next step in the process, e.g., by embossing (not shown) from the driver elements6of hub18, material is plastically displaced in such a way that the depressions15shown inFIG.4are created. One of the depressions15extends axially into one of the second driver elements6in each case.

FIGS.10and5—WhileFIG.10shows the form-fit engagement7of the driver element shaft profile11in the driver element shaft profile12on the pre-assembly assembly,FIG.5shows both the form-fit and the force-fit engagement in a non-detachable connection including an axial fixing means8of both driver element profiles11and12after embossing the depressions15.

FIGS.11and12—FIG.11also shows the form-fit engagement of the two driver element profiles11and12before embossing.FIG.12, on the other hand, shows an interlocking and force-locking connection between the flange16and the hub18, which was produced by the plastic displacement of material, for example steel of the second driver element6, to create the depressions15.

FIGS.5and12—As shown in an example in each case, a first driver element5and a second driver element6rest against one another in the circumferential directions. During the embossing of the depressions15, these were pressed against one another in the circumferential direction or tangentially in such a way that they are clamped against one another in a force-fit and form-fit manner.

FIG.5—The embossing of the depressions15caused material from the second driver elements6to be plastically displaced and pressed against the convex flanks24of the first driver elements. This material nestles against the convex contour28, as a result of which the concave contour29on the flanks25of the second driver element6was formed. This means that a convex contour28on the driver element5in a tangential direction to the rotational axis4, or in a circumferential direction around the rotational axis4, engages in a form-fit manner in a concave contour29in a form-fit manner on the other driver element6. When the depressions15were embossed, material was also displaced into the areas in positions30and31that were furthest away from the respective driver element6. As a result, the convex contour28is axially engaged behind by two projections13and14at these two positions30and31pointing away from one another axially. The projections13and14protrude from the second driver element6at the ends of the concave contour29and are axially opposite one another. These projections13and14are formed by two sections of the plastically displaced material which protrude from the second driver element6and protrude furthest in the direction of the respective first driver element5. Such a form fit means that the axial fixing means8is formed by material that is plastically displaced from the second driver elements6and which forms axial stops at positions30and31. The flanks25shown in this exemplary embodiment are shown in an idealized manner after embossing and are inclined towards one another at an angle 2×Bt, which corresponds to twice the angle bt (FIG.10), i.e., the concave contour of the flanks25is adapted to the angle bt of the flanks24(seeFIG.10). Alternatively, the flanks25are also plastically deformed in all conceivable contours after the embossing (not shown).

FIG.12—The embossing of the depressions15caused material from the second driver elements6to be plastically displaced and pressed against the convex contour32which is formed on the base27of the tooth gap19. This material nestles against the convex contour32, as a result of which the concave contour37at the head of the second driver element6was formed. This means that for each tooth gap21, a convex contour32on the flange16engages in a form-fit manner in a concave contour37on the head of the respective second driver element6in the radial direction away from the rotational axis4, not shown inFIG.12. The rotational axis lies outside and below the viewed image plane. During the embossing of the recesses15, material was also displaced into the areas furthest behind the respective carrier6in the direction of the axis of rotation4in positions33and34so that the convex contour32at these two axially distancing positions33and34is axially engaged by two protrusions35and36axially opposite each other at the concave contour37. These projections35and36are formed by two sections of the plastically displaced material which protrude furthest in the direction of the flange16. Such a form fit means that the axial fixing means8is formed by plastically displaced material from the end faces of the second driver element, which material is designed as axial stops at positions33and34.

FIGS.5and12—The respective concave contour37,29is defined in that its contour line is behind the imaginary engagement path S. The engagement path S lies in the illustration on the straight line shown in dashed lines, and extends between the points of intersection S1 and S2. At the intersection points S1 and S2, the respective contour line of the respective concave contour37alternatively convex contour32intersects the contour line of the end face38. That is, the gap SS running in the considered longitudinal section plane between the concave contour37or29and the engagement path S is not filled by the material of the second driver element6with the concave contour37or29, but by a section of the first driver element5or of the flange16. In the same longitudinal section, the convex contour28or32protrudes beyond the engagement path S. In other words, the gap SS formed in this longitudinal section plane between the convex contour line28or32and the engagement path S is at least partially filled with the material of the first driver element5or the flange16.

In the exemplary embodiment described above, it was exclusively assumed that the axial fixing means8is formed exclusively from material plastically displaced from the second driver elements6. Alternatively, the axial fixing means can be formed both from plastically displaced material of the first driver element and from plastically displaced material of the second driver element or only from plastically displaced material from the first driver element (not shown).

REFERENCE NUMERALS

1Planet carrier assembly2Carrier flange3Carrier4Rotational axis5Driver element of the carrier6Driver element of the carrier flange7Form-fit engagement8Axial fixing means9Pre-assembly assembly10Shaft-hub connection11Driver element shaft profile12Driver element hub profile13Projection14Projection15Depression16Flange17Receptacle18Hub19Tooth gap of the driver element hub profile20Shaft21Tooth gap of the driver element shaft profile22Bevel23Bevel24Flank of the first driver element25Flank of the second driver element26Contour on the head of the second driver element27Base for the tooth gap28Convex contour of the first driver elements29Concave contour of the second driver elements30Location/Region31Location/Region32Convex contour at the base of the tooth gap33Location/Region34Location/Region35Projection36Projection37Concave contour on the head of the second driver element38End face