Weight-reduced spacer for ring gear

Abstract

The invention relates to a ring gear (2) having a spacer (3), wherein: the ring gear (2) comprises an internal toothing (7) for transmitting torque in a transmission; the spacer (3) spaces the ring gear (2) apart from an abutment face (4) of another component (5); the spacer (3), as a component which is separate from the ring gear (2), is interlockingly connected to the ring gear (2) and abuts an end-side abutment face (6) of the ring gear (2); and the end-side abutment face (6) is located radially outside the internal toothing (7) of the ring gear (2).

Description

[0001] - P240690 DE 1 Application Title: Weight-Reduced Spacer for Ring Gear Description: The invention relates to a ring gear of a transmission with a spacer to the housing, in order to maintain the ring gear at a distance in the axial direction from a contact surface of the housing. The spacer contacts both the ring gear or an end face of the ring gear and the contact surface of the housing, which is designed as an end face. The spacer is connected to the ring gear as a separate component via a captive connection. US 2022 / 0275857 A1 discloses a ring gear for torque transmission with a one-piece integrally formed flange, via which the ring gear can be attached to another component. The objective is to improve the known ring gear.The problem is solved according to the invention by a ring gear with a spacer, wherein the ring gear is designed with its internal teeth for torque transmission in a gearbox and the spacer separates the ring gear from a contact surface of another component, in that the spacer, as a component separate from the ring gear, is positively connected to the ring gear and rests against an end-face contact surface of the ring gear, the end-face contact surface being arranged radially outside the internal teeth of the ring gear. The component "spacer" is positively connected to the component "ring gear" and preferably in a captive manner. The positive connection is preferably a releasable snap connection. Thus, the spacer can be clipped onto the ring gear and is firmly connected to the ring gear during assembly of the ring gear in its future position - P240690 DE 2.After installation, the spacer positions the ring gear away from a stop surface, thus ensuring the correct positioning of the ring gear within the transmission. The positive-locking connection preferably creates a rotationally fixed connection between the ring gear and the spacer. Alternatively, rotation between the ring gear and the spacer can be provided, while maintaining the positive locking in the axial direction. It is advantageous if the spacer is designed as a single, ring-shaped component. This allows for a circumferential spacing of the ring gear from a contact surface with another component. Ideally, with ring-shaped bodies, three contact surfaces evenly distributed around the circumference result in a wobble-free and thus clearly defined overall contact. These three contact surfaces can be offset from the individual spacer in the axial direction.Alternatively, three spacers can be positively connected to the ring gear, with these being evenly distributed around the ring gear's circumference – however, this method requires more assembly and component preparation. The end face of the ring gear, where the spacer comes into contact after the positive connection is complete, is located radially outside the ring gear's internal teeth. As part of a transmission, the ring gear has internal teeth that can mesh with other gears. Thus, the ring gear is a ring-shaped component. Radially outside the internal teeth, the ring gear has a circumferential annular collar, which has at least one end face contact surface on an axial side of the ring gear. The annular collar, set back from the internal teeth, allows the contact surface to be positioned within the axial extent of the internal teeth.In other words, the extension of the internal teeth exceeds the placement of the contact surface for the spacer. Advantageous embodiments of the invention are the subject of the dependent claims and are explained in more detail below. In one embodiment of the invention, the further component is a housing surrounding the gearbox. Once the ring gear and the spacer have been joined together, the ring gear is ready for insertion into the gearbox. The gearbox is located within a housing (P240690 DE 3) and uses a ring gear, stationary relative to the housing, with its internal teeth for meshing with other gearbox components (gears). Thus, it is advantageous if the contact surface of the further component is provided by the housing, against which the spacer comes into contact, thereby reliably positioning the ring gear in the gearbox relative to the other gears. Advantageously, the spacer is made of plastic.This plastic is suitable for use in a gearbox and for the surrounding environment and contact with gear oil. At the same time, the plastic must possess the necessary dimensional stability so that the spacing provided by the spacer is not altered by gear oil and / or temperature during gearbox operation, thus ensuring reliable spacing. Only then is the correct positioning of the internal teeth relative to the meshing gears guaranteed with high precision. As a result, the axial engagement lengths of the teeth can exhibit less excess length, which ensures a constant contact length during operation. This means that the overall length of the components containing the teeth can be reduced due to the lower variance in engagement lengths during operation. Excess lengths required to ensure engagement lengths can be significantly reduced.In another embodiment, the spacer has at least one locking lug for a positive-locking connection with the ring gear. This locking lug secures the positive-locking connection in at least one axial direction, meaning it restricts at least one degree of freedom in the axial direction between the components. In the case of an annular spacer, several locking lugs, distributed regularly or irregularly around the circumference, can be formed as a single unit. The locking lug can engage in a groove formed by the ring gear that is complementary to the engagement contour of the locking lug, thus securing both components to each other. Thus, several locking lugs can engage in a common groove, several locking lugs can engage in their own separate grooves, or only one locking lug can engage in only one groove. Furthermore, the ring gear has at least one groove for a positive-locking connection with the spacer.The groove can be provided as a preferably arc-shaped groove in cross-section in the ring gear (P240690 DE 4), with the opening of the groove oriented radially inwards or outwards. Alternatively, for engagement with the locking lug, instead of a typical groove shape, it is also possible to form a radially inwardly or outwardly directed shoulder in the form of a radial step, the formation of such a step resembling an undercut. In one embodiment of the invention, the radial positioning of the positive locking connection is arranged in the axial direction within the axial extent of the internal teeth of the ring gear. Advantageously, this achieves a wide tooth profile and simultaneously saves weight. Another embodiment provides that the ring gear has external teeth which are located within the axial extent of the internal teeth.With this external toothing, the ring gear is joined, for example, to a complementary internal toothing of a housing, whereby the ring gear is considered fixed to the frame within the transmission. Alternatively, a parking pawl to block the rotation of the ring gear or another gear that drives or is driven by the ring gear can engage in such external toothing. In an advantageous embodiment, the end-face contact surface is positioned radially between the external toothing and the internal toothing. This advantageously allows for a wide tooth profile, reduces weight, and isolates the spacer from the influence of the internal toothing. The internal toothing does not need to have the engagement contour for a positive-locking connection with the spacer.In a preferred embodiment, the end-face contact surface is arranged axially within the axial extent of the internal teeth of the ring gear. Thus, the end-face contact surface does not project beyond the length of the teeth. This distance can therefore be accommodated by the axial extent of the spacer. - P240690 DE 5 Another embodiment provides that the contact surface of the additional component is arranged axially within the axial extent of the internal teeth of the ring gear. As an alternative to the previously mentioned embodiment, the material of the additional component can be designed to extend axially to such an extent that the spacer requires as little installation space as possible in its axial extent.

[0002] - P240690 DE 6 Description of Figures Further embodiments of the invention are explained in more detail with reference to the figures. Figure 1 shows a ring gear according to the invention with a spacer, Figure 2 shows the spacer according to the invention from Figure 1, and Figure 3 shows the installation situation of the ring gear according to the invention according to Figure 1. Figure 1 shows a ring gear 2 according to the invention with a spacer 3. The two components 2 and 3 thus form an assembly 1 as a device after being joined together, which can be inserted into a housing 13 (not shown here). This is explained further in Figure 3. The ring gear 2 has an external toothing 10 on an outer cylindrical surface, which engages with a complementary internal toothing 15 of a housing 13. The ring gear 2 has a "double-T" shape in cross-section.Furthermore, the ring gear 2 has an internal toothing 7 as a running tooth for engaging a planet gear, so that the planet gear can roll in the internal toothing 7. The internal toothing 7 has an axial extension 12, which extends from one end face of the internal toothing 7 to the axially opposite end face of the internal toothing 7. The external toothing 10 also has an axial extension 11, which extends from one end face of the external toothing 10 to the axially opposite end face of the external toothing 10. Offset from these two end faces of the external toothing 10, the end-face contact surface 6 of the ring gear 2 is formed on one axial side, against which the spacer 3 bears. The end-face contact surface 6 is ideally perfectly flat and has no further shoulders.Alternatively, this end-face contact surface 6 can be recessed in the circumferential direction; however, at least three partial end-face contact surfaces should be provided for contact with the spacer 3 so that the spacer 3 cannot tilt relative to the ring gear 2. In this embodiment, the positive locking connection 14 is achieved by a fully circumferential groove 9 formed by the ring gear 2, into which at least one lug 8 of the spacer 3 engages. The at least one lug 8 engages in the groove 9 and secures the spacer 3 to the ring gear 2 in the radial and axial directions. No positive locking element is provided in the circumferential direction. The end-face contact surface 6 is provided to determine the axial position between the ring gear 2 and the spacer 3. If the at least one lug 8 has a specific arc length in the circumferential direction, the locking in the radial direction is ensured.Figure 2 shows the spacer 3 according to the invention from Figure 1. A more detailed view of the at least one lug 8 reveals that there are multiple lugs 8, which are arranged regularly distributed around the circumference. In this embodiment, 18 lugs 8 are evenly spaced from one another around the circumference and are formed integrally with the spacer 3. All lugs 8 have the same geometric shape. It is thus clear that this arrangement of the lugs 8 enables the spacer 3 to be centered on the ring gear 2. Figure 3 shows the installation of the ring gear 2 according to the invention as shown in Figure 1. The two interlocking teeth 10 and 15 prevent the ring gear 2 from rotating, but rather fix it in place within the housing 13. The housing 13 has a contact surface 4 designed for the spacer 3.The positioning of the contact surfaces 4 and 6 within the axial extension 12 of the internal gear 7 is clearly visible. This allows the engagement length between the internal gear 7 and a planet gear to be designed independently of the shape of the spacer 3 and its contact surfaces 4 and 6. This nesting saves installation space and arranges components 2 and 3 very compactly within the housing 13. The axial extension of the spacer 3 allows identical ring gears 2 to be installed in different housings 13. The radial positioning of the contact surface 6, shown here, radially inside and thus away from the external gear 10, as well as radially outside and thus away from the internal gear 7, allows the spacer 3 to be "hidden" radially between the gear teeth, resulting in a very compact assembly 1.- P240690 DE 8 Reference numeral list 1 Assembly 2 Ring gear 3 Spacer 4 Contact surface (other component) 5 Other component 6 Face contact surface (ring gear) 7 Internal toothing 8 Detent lug 9 Groove 10 External toothing 11 Axial extension (external toothing) 12 Axial extension (internal toothing) 13 Housing 14 Positive locking connection 15 Internal toothing.

Claims

- P240690 DE 9 Claims 1. Ring gear (2) with a spacer (3), wherein the ring gear (2) is designed with internal teeth (7) for torque transmission in a gearbox and the spacer (3) spaces the ring gear (2) apart from a contact surface (4) of a further component (5), characterized in that the spacer (3) is positively connected to the ring gear (2) as a component separate from the ring gear (2) and bears against an end-face contact surface (6) of the ring gear (2), the end-face contact surface (6) being arranged radially outside the internal teeth (7) of the ring gear (2).

2. Ring gear (2) according to claim 1, characterized in that the further component (5) is a housing (13) surrounding the gearbox.

3. Ring gear (2) according to any one of the preceding claims, characterized in that the spacer (3) is made of plastic. 4.

5. Ring gear (2) according to one of the preceding claims, characterized in that the spacer (3) has at least one locking lug (8) for positive locking connection with the ring gear (2).

6. Ring gear (2) according to one of the preceding claims, characterized in that the ring gear (2) has at least one groove (9) for positive locking connection with the spacer (3). - P240690 DE 10 the radial positioning of the positive-locking connection (14) is arranged in the axial direction within the axial extension (12) of the internal teeth (7) of the ring gear (2).

7. Ring gear (2) according to one of the preceding claims, characterized in that the ring gear (2) has an external toothing (10) which is located in its axial extension (11) within the axial extension (12) of the internal teeth (7).

8. Ring gear (2) according to one of the preceding claims, characterized in that the end-face contact surface (6) is positioned radially between the external toothing (10) and the internal toothing (7).

9. Ring gear (2) according to one of the preceding claims, characterized in that the end-face contact surface (6) is arranged in the axial direction within the axial extension (12) of the internal teeth (7) of the ring gear (2). 10.Ring gear (2) according to one of the preceding claims, characterized in that the contact surface (4) of the further component (5) is arranged in the axial direction within the axial extension (12) of the internal toothing (7) of the ring gear (2).

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