Patent Application
20250003483
The present disclosure relates to a planetary gearbox having a housing, with planet gears and with planet bearings. The planet gears are mounted on the housing by means of the planet bearings so as to be rotatable about an axially aligned planetary axis and at least one of the planet bearings is formed from at least one axially aligned planet pin and a thrust washer. The thrust washer is seated axially between the planet gear and the housing on the planet pin and is held in a form-fitting manner with the aid of an anti-rotation means so as to prevent rotation about the planetary axis and relative to the housing.
Such a planetary gearbox is disclosed in DE 40 09 968 A1. The thrust washers are axial sliding bearings of the planet bearings for the respective planet gear. The planet gear is mounted radially on a planet bolt by means of the planet bearing. The thrust washers are seated axially between the planet bearing, the planet gear and the planet carrier. A bearing surface is defined via the surface of the respective thrust washer, which is usually designed as a sliding bearing surface. The sliding bearing surfaces are designed differently from case to case. The thrust washers are equipped with tongue-like anti-rotation means. This prevents the respective thrust washer from rotating in relation to the planet carrier and avoids frictional wear in the contact zone between the hard thrust washer and the usually non-hardened planet carrier. On the other hand, undefined friction or sliding conditions between the thrust washer and the planet gear are avoided.
The present disclosure provides a planetary gearbox which can be produced easily and inexpensively.
According to the disclosure, the thrust washer has first thrust surfaces on a first side facing the housing and second thrust surfaces offset circumferentially relative to the first thrust surfaces on a second side facing a planet gear. Furthermore, a trough-like lubrication channel is formed on the thrust washer axially on the rear side of the thrust surfaces in each case. The lubrication channel extends radially outwards from the direction of the planet pin as far as an edge which delimits the thrust washer radially on the outside.
In one embodiment, the lubrication channel extends in each case between two of the first thrust surfaces of the thrust washer which are circumferentially adjacent to one another.
In a further embodiment, the lubrication channel ends at at least one of the anti-rotation means of a thrust washer.
In one embodiment, a design of the planetary gearbox is assumed in which at least one housing section of the housing is formed as a planet carrier and the housing sections are support cheeks of the planet carrier connected axially by means of connecting pieces. In such a planetary gearbox, the stop is a connecting piece projecting axially from one support cheek of the planet carrier in the direction of a further support cheek.
In a further development of the aforementioned embodiment, each of the connecting pieces has at least one stop for one anti-rotation means formed on one and the same thrust washer of two anti-rotation means formed on the thrust washer.
In addition, in a further development, two flanks of the planet carrier facing away from one another are the stops for the anti-rotation means of a thrust washer. The stops are formed circumferentially between two adjacent connecting pieces and adjoining the planet pin.
In a further embodiment, the thrust washer has two anti-rotation means which extend radially from a washer body and are formed circumferentially about a planetary axis of a planet gear adjacent to one another on the washer body and are made of a material of the thrust washer. The anti-rotation means may be integrally formed with a washer body of the thrust washer. The material may be sheet steel. A first anti-rotation means rests against a first stop. A second anti-rotation means formed on the same thrust washer rests against a second stop opposite the first stop. The respective stop may be formed on a connecting piece of a planet carrier of the planetary gearbox. Two support cheeks of the planet carrier are connected to one another via the respective connecting piece.
In a further embodiment, at least one of the anti-rotation means projects radially away from the planet pin beyond a contour of the planet gear, which contour delimits the planet gear on the outside.
In one embodiment, at least one of the anti-rotation means projects radially away from the planet pin beyond a contour of the planet gear, which contour delimits the at least one planet gear on the outside. In this regard, the lubrication channel, which is delimited on at least one side by the thrust washer, extends radially outwards as far as an edge of the anti-rotation means, which delimits the thrust washer radially on the outside.
The disclosure also provides for a thrust washer for the planetary gearbox. The thrust washer has first bulges and second bulges circumferentially adjacent to the first bulges. The first thrust surfaces are separated from one another by first bulges of the thrust washer. The second thrust surfaces are formed on the first bulges on the second side and rear side and are separated from one another by second bulges of the thrust washer. The first thrust surfaces are formed on the second bulges on the first side and rear side. A first bulge and a second bulge are, in each case, connected to one another by an elbowed section, which ensures the axial offset of the thrust surfaces. The bulges extend radially outwards in a trough-like manner from the direction of the planet pins as far as an edge of the thrust washer which delimits the thrust washer radially on the outside. The bulges may continue radially beyond an outer circumference of the washer body of the thrust washer and further at least partially into the anti-rotation means or, for example, up to the outer contour of the thrust washer on the anti-rotation means.
Two anti-rotation means are formed on the thrust washer instead of just one. This results in more possibilities for securing the thrust washer so as to prevent rotation. A targeted mounting of the thrust washer can be dispensed with in most cases. The thrust washer is supported against rotation by means of the respective anti-rotation means, either on one or two stops. Due to the aforementioned design of the axial washer, it is identical on both axially directed end faces and also mirror-symmetrical with respect to the anti-rotation means so that it can be mounted in the planet carrier without the need for a directionally oriented mounting.
It is also provided that the stop is a connecting piece that connects the housing sections, e.g., the support cheeks of a planet carrier, with one another, which alternatively also forms more than one stop. As these connecting pieces are already present in any case, the complex production of additional form-fit recesses for the engagement of the anti-rotation means of the thrust washers can advantageously be dispensed with.
Housings are housings of vehicle transmissions, of electric motors or of drive units operated by electric motors—but are alternatively also planet carriers and differential cases, e.g., differential cases of spur gear differentials. Accordingly, housing sections are, for example, end shields, partition walls, solid housings, halves of differential cases or support cheeks of planet carriers.
In one embodiment, the stop protrudes at least partially axially into a gap between planet gears distributed circumferentially around the central axis and adjacent to one another. This means that no additional effort is required for the positional orientation of the anti-rotation means. The connecting pieces, which are already circumferentially adjacent to one another, can be used as stops.
The thrust washer according to the disclosure is designed such that the stop radially adjoins the planet pin and projects radially beyond a contour of the housing. The position of the stop is therefore not essentially linked to the circumference of the planet gear, as is the case with known planet bearings, but is independent of it. Accordingly, there are a variety of design options for the anti-rotation means and the stop. For example, in one embodiment, the stop can have two stop sides pointing away from one another and in opposite circumferential directions, each serving to abut, in each case, a different anti-rotation means of one and the same thrust washer.
The bulges on the thrust washers interact with a further component to create lubrication channels, which can optionally form channels delimited by further thrust washers, housing sections, sections of the planet carrier or flanks of planet gears. Through these channels, lubricating oil reaching the thrust washer can be conveyed from the thrust washers on the inside radially to the outside without any additional effort.
In planetary gearboxes of the prior art, the thrust washers are provided with anti-rotation means for the reasons already mentioned in the “BACKGROUND” section. As such, the anti-rotation means engages in a form-fitting manner in a form-fit recess prepared on the respective housing, for example in a hole, an indentation or a recess. Accordingly, the thrust washers must be aligned, held and positioned with respect to the form-fit recesses when mounting the planet bearings with the anti-rotation means. This is often associated with increased effort-on the one hand, because the respective form-fit recess must be introduced into the housing and, on the other hand, because the directional positioning requires specific devices and operations for assembly.
When assembling planetary gearboxes, the aim is to handle planet gears together with the planet bearing (needle or roller bearing), with the planet pin/planet bolt and with the thrust washer as an assembly. This is possible by implementing the disclosed device with the planetary gearboxes according to the disclosure.
The present disclosure is described in more detail below with reference to the drawings.
The term “axial” is understood as aligned with the central axis 9 of the planetary gearbox 1 or 21. The term “radial” is understood as transverse to the axial direction.
Pocket-like windows 27 are formed between the connecting pieces 13. The toothing 29 of a planet gear 3 protrudes from each of the windows 27. The planet gears 3 are arranged in the support cheek 12 axially between the support cheek 12 and the support cheek 14 and at equal distances from one another around the central axis 9, each distributed with a radial distance between its planetary axis 24 and the central axis 9. On the respective planet bearing 4, the planet gears 3 are mounted with planet pins 5 on one side in the support cheek 12 and on the other side in the support cheek 14. In each case, one thrust washer 6 is arranged between the respective planet gear 3 and the support cheek 12 or 14, which is largely concealed in the illustration, the anti-rotation means 8 of which project radially beyond the contour 18 of the toothing 29 and are opposite a stop 10. Each of the connecting pieces 13 is a stop 10 or forms a stop 10 for, in each case, four of the anti-rotation means 8 and thus for four thrust washers 6. Of the four thrust washers 6, two of the thrust washers 6 are, in each case, assigned to one window 27 and two of the thrust washers 6 are assigned to an adjacent window 27.
The second side 46 of the thrust washer 6, which faces the planet gear 3 and is concealed in the illustration, is provided with second thrust surfaces 38, which are concealed in the illustration and which are formed on the front side of the bulges 41. The front side lies in the direction in which the bulge 41 is axially curved and closes it off axially. In the view shown, the bulges 41 form lubrication channels 43 open to the top and, in the installed state (see
The two thrust washers 6 are provided with the anti-rotation means 8, which protrude radially as tongues from the sheet metal of the thrust washer 6. In this context, the tongues form an angle of 120° between them in a circumferential direction, which can alternatively also be greater or less than 120°.
A gap 11 is formed between two opposing planet gears 3. One of the connecting pieces 13, which forms one or more of the stops 10, extends between the support cheeks 12 and 14 in every gap 11. In this case, the stop 10 is formed on a flank of the connecting piece 13 facing the planet gear 3. It is also conceivable that two of the connecting pieces extend in a gap. A pivoting clearance is formed between the anti-rotation means 8 and 30) the connecting pieces 13, by which the thrust washer 6 can pivot on the planet bolt about the planetary axis 24 up to the respective stop 10 so that one of the anti-rotation means 8 of the respective thrust washer can abut against the stop 10 opposite to it or none of the anti-rotation means 10 can come into contact. Lubrication channels 43 formed in the thrust washer 6 are visible here.
Pocket-like windows 27 are formed between the connecting pieces 13. The toothing 29 of a planet gear 3 protrudes from each of the windows 27. The planet gears 3 are arranged axially between the support cheek 12 and the support cheek 14 and are distributed at equal distances from one another in the case of the support cheek 12. The planet gears 3 are mounted with planet pins 5 on one side in the support cheek 12 and on the other side in the support cheek 14. The planet gears 3 are rotatably mounted on the housing 2 by means of the planet bearings 4a. The respective planet bearing 4a is formed from the axially aligned planet pin/planet bolt 5 and a thrust washer 6a. The thrust washer 6a sits axially between the planet gear 3 and the housing 2 on the planet pin 5, is provided with two anti-rotation means 8a, and is held by these anti-rotation means 8a against rotation relative to the housing 2 in a form-fitting manner against a stop 10a.
The stop 10a is formed circumferentially between two adjacent connecting pieces 13 and projects radially beyond a contour of the base body 33 of the support cheek 12, adjoining the planet pin 5 radially on the outside, when viewed in the radial direction from the center of the planetary gearbox 21. More precisely, the stops 10a for, in each case, one of the thrust washers 6a are circumferentially formed on the flanks of the planet carrier 7 facing away from one another between two adjacent connecting pieces 13 and adjoining the respective planet pin 5. The flanks are body edges or surfaces, directed in the circumferential direction, of a radially projecting support section of the support cheek 12, at which the planet pins 5 are partly accommodated in the support cheek 12.
The thrust washers 48 are provided with lubrication channels 51 formed by lubrication grooves 52, each of which ends at an anti-rotation means 49 and, where the anti-rotation means 49 are no longer axially opposite the housing 2, continues in a lubrication groove 52 to the end of the anti-rotation means 49.
The contour of the anti-rotation means 49 projects radially beyond an outer circumferential line U of the washer body 55 of the thrust washer 48. In this case, the washer body 55 is annularly delimited on the inside by the contours of the through-hole with the indentations 30 and on the outside by the outer circumferential line U and has an outer diameter DU of the outer circumferential line U. In addition, the washer body 55 is designed to be symmetrical with respect to the axes of symmetry S1 and S2. The axis of symmetry S1 is aligned horizontally and the axis of symmetry S2 is aligned vertically. The axes of symmetry S1 and S2 lie in a radial plane which is pierced perpendicularly by the planetary axis 24. The axes of symmetry S1 and S2 extend perpendicular to one another and intersect at a common point on the planetary axis 24.
The contour of the anti-rotation means 49 is defined, in each case, by two flank lines F1 and F2. Each contour of one of the anti-rotation means 49 is therefore outlined in the image plane by a flank line F1 and a flank line F2 as well as an arc. The arc connects the flank lines F1 and F2 of an anti-rotation means 49. The anti-rotation means 49 are designed to be symmetrical to one another and are mirrored on the axis of symmetry S2. In this regard, the extensions of the flank lines F1 of the two anti-rotation means 49 intersect at a common intersection point C1, which lies on the extension of the axis of symmetry S2 and which lies, at a radial distance from the outer contour of the thrust washer 48, outside of the outer contour. In this regard, the flank lines F1 and F1 of the adjacent anti-rotation means 49 form an obtuse angle W1 between them and the flank lines F1 and F2 form an acute angle W2 between them and the axis of symmetry S2 on one of the anti-rotation means 49 in each case. The two flank lines F1 of both anti-rotation means 49 optionally merge at a straight line describing the outer contour of the thrust washer at this point and extending radially below the intersection point C1 or alternatively at an arcuate line (not shown) of the outer contour of the thrust washer 48.
The respective extension of the flank line F1 of the one anti-rotation means 49 intersects the extension of its flank line F2 at an intersection point C2, which lies on the axis of symmetry S1 and radially outside of the outer contour of the thrust washer 48. The contour lines F1 and F2 of the respective anti-rotation means 49 form an acute angle W2 between them.
The thrust washer 48 is geometrically divided into quarter sections 48a-48d. The quarter sections 48a-48d adjoin one another at the axes of symmetry S1 and S2 and are designed to be symmetrical to one another on the washer body 55 described by the circumferential line U. Outside of the circumferential line U, the outer contours of the quarter 30) sections 48a and 48b lying above the axis of symmetry S1 are each delimited radially outwards by a complete flank line F1 and a part of a flank line F2. Below the axis of symmetry S1, the outer contours of the quarter sections 48c and 48d are each delimited by a part of a flank line F2 and a part of an arc line. The arc line lies on the circumferential line U. The respective flank line F2 merges into the arc line in the respective quarter section 48c and 48d, so that the contours of the anti-rotation means also extend, in each case, into the quarter section 48c or 48d lying below the axis of symmetry S1. The radius of the arc line starting from the planetary axis 24 corresponds to half the diameter DU of the outer circumferential line.
In each of the quarter sections 48a-48d, one of the bulges 54 is fully formed once. Each of the quarter sections 48a-48d also has, twice in each case, a part of one of the bulges 53. In this regard, the bulges 54 of the quarter sections 48a and 48b continue in the anti-rotation means 49 up to the outer contour of the thrust washer 48 and thus the anti-rotation means 49 at that point. In addition, a bulge 53, which extends along the axis of symmetry S1 and is formed partially in a quarter section 48a and 48d or 48b and 48d, continues radially outwards as far as the outer contour of the respective anti-rotation means 49 and thus the outer contour of the thrust washer 48. This means that in the planetary gearbox shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2021 131 137.3 | Nov 2021 | DE | national |
This application is the United States National Phase of PCT Appln. No. PCT/DE2022/100868 filed Nov. 21, 2022, which claims priority to German Application No. DE102021131137.3 filed Nov. 26, 2021, the entire disclosures of which are incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/DE2022/100868 | 11/21/2022 | WO |
