Planetary gear for a motor vehicle

Abstract

Planetary gear (1) for a motor vehicle, comprising a sun gear (2) and a ring gear (3), and a planet gear set (4) with several planet gears (6) rotatably mounted on a planet carrier (5), wherein the planet gears (6) are in tooth mesh with the sun gear (2) and with the ring gear (3), wherein the planetary gear (1) is arranged within a motor-side first housing part (7) and a gearbox-side second housing part (8), wherein the second housing part (8) comes into axial contact with a second contact surface (11) against a first contact surface (10) of the first housing part (7) and forms a joining gap (9), wherein the ring gear (3) is used for axial fixing with a first end face (14) axially abuts the first contact surface (10) of the first housing part (7) and with a second end face (15) axially abuts a housing shoulder (17) of the second housing part (8), characterized in that a retaining ring (12) is partially received and axially secured in a groove (13) radially formed at the joining gap (9), wherein the ring gear (3) for axial fixing with the first end face (14) indirectly axially comes into contact with the first contact surface (10) in such a way that the ring gear with the first end face (14) comes into direct axial contact with the retaining ring (12), the retaining ring (12) comes into contact with the first contact surface (10) of the first housing part (7) and the groove (13) is formed partly on the inner circumferential surface of the first housing part (7) and partly on the inner circumferential surface of the second housing part (8).

Description

[0001] The invention relates to a planetary gear for a motor vehicle, comprising a sun gear and a ring gear, as well as a planet gear set with several planet gears rotatably mounted on a planet carrier, wherein the planet gears mesh with the sun gear and the ring gear. The invention further relates to a motor vehicle with such a planetary gear.

[0002] German patent DE 42 16 397 A1 discloses a planetary gear system. This system comprises a sun gear that can be non-rotatably connected to a drive shaft, several planet gears mounted in a planet carrier, and a ring gear that surrounds the planet gears. The ring gear is connected to a ring gear carrier. For axial force absorption, thrust rings are provided between the sun gear and the planet gears, and between the planet gears and the ring gear. The thrust rings are located on the end faces of the respective gears.

[0003] DE 691 00 828 T2 describes a starting device for an internal combustion engine with a ring gear of a planetary gearbox supported in a two-part housing.

[0004] US 2003 / 0109354A1 also describes a ring gear supported in a two-part housing, wherein a sealing element and a retaining ring form the axial closure against one housing part.

[0005] The object of the present invention is to further develop a planetary gear for a motor vehicle and in particular to improve the support of the axial forces that occur.

[0006] This problem is solved by a planetary gear unit with the features of claim 1. Preferred or advantageous embodiments of the invention are described in the dependent claims of the following description and in the accompanying figures.

[0007] A planetary gear system according to the invention for a motor vehicle comprises a sun gear and a ring gear, as well as a planet gear set with several planet gears rotatably mounted on a planet carrier, wherein the planet gears are in tooth mesh with the sun gear and with the ring gear, wherein the planetary gear system is arranged within a motor-side first housing part and a gearbox-side second housing part, wherein the second housing part comes into axial contact with a first contact surface of the first housing part with a second contact surface and forms a joining gap, wherein the ring gear comes into axial contact with the first contact surface of the first housing part at least indirectly with a first end face for axial fixing and comes into axial contact with a housing shoulder of the second housing part with a second end face.

[0008] The planetary gear set is preferably designed with helical teeth. Accordingly, the ring gear, the planet gears of the planetary gear set, and the sun gear each have helical teeth. In addition to circumferential forces, axial forces occur in the planetary gear set, which are introduced into the housing of the planetary gear set, for example, through the ring gear. The torque acting on the ring gear is transmitted primarily via the toothing.

[0009] The housing is formed in at least two parts: the first housing part on the engine side and the second housing part on the transmission side. The first housing part on the engine side is permanently attached to the vehicle. The second housing part on the transmission side is designed to be removable. The second housing part is preferably bolted to the first housing part. For this purpose, the first and second housing parts have, for example, corresponding threaded holes to be bolted together. In the assembled state, a gap or parting line is formed between the two contact surfaces of the housing parts.

[0010] Furthermore, the term "indirect" means that the ring gear may not be directly connected to the first housing part, but rather via another component or element, in particular a retaining ring. This positive connection between the ring gear and the first or second housing part is essentially intended to transmit axial forces from the ring gear to the planetary gear housing. Thus, a positive axial locking mechanism is established. The connection between the ring gear and the housing is at least partially deformable, allowing for load equalization between the planets.

[0011] For direct connection between the ring gear and the first housing part, the inner diameter of the first housing part is preferably smaller than the inner diameter of the second housing part. This causes the first contact surface to protrude radially inwards relative to the second contact surface, with the ring gear bearing axially against the first contact surface with its first end face.

[0012] According to the invention, a retaining ring is partially received and axially secured in a groove radially formed at the joining gap, wherein the ring gear comes into axial contact with the retaining ring with its first end face for axial fixation, and wherein the retaining ring comes into contact with the first contact surface of the first housing part.

[0013] In a preferred embodiment, both the first and second housing parts preferably have approximately the same inner diameter. According to the invention, the retaining ring is axially held in the groove formed in the parting line between the two contact surfaces of the housing parts. Thus, the retaining ring has axial clearance, preventing it from rotating during operation of the planetary gear when the ring gear rotates. Preferably, the retaining ring is a closed ring. With this design, the retaining ring cannot be radially compressed compared to conventional retaining rings, thereby preventing it from unintentionally popping out of the circumferential groove. Consequently, the retaining ring can only be installed or removed when the second housing part is detached from the first.Therefore, the groove for receiving the retaining ring is formed at the joining gap. According to the invention, the retaining ring is made of a metal. This results in increased wear resistance of the retaining ring during operation of the planetary gear according to the invention.

[0014] According to the invention, the groove is formed partially on the inner circumferential surface of the first housing part and partially on the inner circumferential surface of the second housing part. Furthermore, according to the invention, the groove is formed directly at the joining gap between the two contact surfaces. The axial position of the circumferential groove on the inner circumferential surface of the housing parts depends on the axial dimensions of the ring gear within the planetary gear set and the axial position of the joining gap.

[0015] In particular, the planetary gear system according to the invention is used in a motor vehicle. A motor vehicle is understood to be a vehicle which, according to its design and its special equipment permanently attached to the vehicle, serves for the transport of persons or goods. For example, a motor vehicle can be a passenger car or a truck.

[0016] Further measures improving the invention are described in more detail below, together with a description of four preferred embodiments of the invention, with reference to the five figures. These show... Fig. 1 a simplified schematic representation of a section of a planetary gear according to the invention, Fig. 2 a schematic sectional view of the partially depicted planetary gear according to Fig. 1 according to a first embodiment, Fig. 3 a schematic sectional view of the planetary gear according to a second embodiment, Fig. 4 a schematic sectional view of the planetary gear according to a third embodiment, and Fig. 5 a schematic sectional view of the planetary gear according to a fourth embodiment.

[0017] According to Fig. 1 comprises a planetary gear set 1 according to the invention – only partially shown here – for a motor vehicle – not shown here – a sun gear 2, a ring gear 3, and a planet gear set 4 with several planet gears 6 rotatably mounted on a planet carrier 5. The planetary gear set 1 is designed with helical gears, whereby circumferential forces and axial forces arising in the planetary gear set 1 are transferred via the ring gear 3 into a planet carrier 5. Fig. The housing 18 shown in sections 2 to 5 is guided. Due to the sectional view, only one planet gear 6 of the planet gear set 4 is shown here. The planet gears 6 are in mesh with the sun gear 2 and the ring gear 3.

[0018] After the Fig. Figures 2 to 5 show a longitudinal section of the planetary gear unit 1. The planetary gear unit 1 is arranged within a housing 18, which consists of a first housing part 7 on the motor side and a second housing part 8 on the gearbox side. The second housing part 8 comes into axial contact with a first housing part 10 of the first housing part 7 via a second contact surface 11, thus forming a gap 9 between the two contact surfaces 10 and 11. The second housing part 8 is screwed to the first housing part 7 by means of several screws 16, although only one screw 16 is shown here due to the partial sectional view.

[0019] In Fig. In the first housing part 7, the inner diameter is smaller than that of the second housing part 8. Therefore, according to a first embodiment, the ring gear 3 is axially fixed by bearing against the first contact surface 10 of the first housing part 7 with a first end face 14. With a second end face 15, the ring gear 3 also bears axially against a shoulder 17 of the second housing part 8. This axially fixes the ring gear 3 between the first and second housing parts 7, 8, and the axial forces can be supported against the housing 18.

[0020] According to the Fig. A retaining ring 12 is partially received and axially secured in a groove 13 radially formed at the joining gap 9, as shown in sections 3 to 5. The retaining ring 12 projects radially towards the interior of the transmission or the ring gear 3. The outer diameter of the ring gear 3 is larger than the inner diameter of the retaining ring 12, so that the first end face 14 of the ring gear 3 abuts axially against the retaining ring 12. The retaining ring 12 thus abuts the first contact surface 10 of the first housing part 7. The retaining ring 12 is axially held in the groove 13 between the two contact surfaces 10, 11 of the two housing parts 7, 8. Furthermore, the retaining ring 12 is formed as a closed ring and made of metal. This prevents the retaining ring 12 from being compressed and unintentionally popping out of the groove 13.Furthermore, the retaining ring 12 cannot rotate with the possibly rotating ring gear 3 during operation of the planetary gear 1. In addition, the groove 13 is designed such that the retaining ring is installed with a clearance.

[0021] After Fig. According to a second embodiment of the planetary gear 1 according to the invention, the groove 13 is formed partially on an inner circumferential surface of the first housing part 7 and partially on an inner circumferential surface of the second housing part 8. Both housing parts 7, 8 have a circumferential recess in the area of ​​the contact surfaces 10, 11, with the two recesses forming the groove 13, the groove 13 corresponding to the dimensions of the retaining ring 12.

[0022] Fig. Figure 4 shows that the groove 13 is formed on the inner circumferential surface of the second housing part 8. Here, only the second housing part 8 has a circumferential recess on the second contact surface 11 to accommodate the retaining ring 12.

[0023] In Fig. 5 the groove 13 is formed on the inner circumferential surface of the first housing part 7. Thus, when assembling the planetary gear 1 or when assembling the second housing part, the retaining ring 12 can first be inserted into the groove 13 formed at the joining gap 9 and then at least the ring gear 3 and the second housing part 8 can be mounted, thereby simplifying the assembly of the planetary gear 1. Reference symbol list 1 planetary gear 2 sun wheel 3. Ring gear 4 planetary gear set 5 planetary carriers 6 planetary gear 7 Housing part 8 Housing part 9 Joining gap 10 Plant area 11 Plant area 12 retaining ring 13 Nut 14 Front surface 15 Front surface 16 screw 17 Housing shoulder 18 cases

Claims

[1] Planetary gear (1) for a motor vehicle, comprising a sun gear (2) and a ring gear (3), and a planet gear set (4) with several planet gears (6) rotatably mounted on a planet carrier (5), wherein the planet gears (6) are in tooth mesh with the sun gear (2) and with the ring gear (3), wherein the planetary gear (1) is arranged within a motor-side first housing part (7) and a gearbox-side second housing part (8), wherein the second housing part (8) comes into axial contact with a second contact surface (11) against a first contact surface (10) of the first housing part (7) and forms a joining gap (9), wherein the ring gear (3) is used for axial fixing with a first end face (14) axially comes into contact with the first contact surface (10) of the first housing part (7) and with a second end face (15) axially comes into contact with a housing shoulder (17) of the second housing part (8), characterized by, that a retaining ring (12) is partially received and axially secured in a groove (13) radially formed at the joining gap (9), wherein the ring gear (3) for axial fixing with the first end face (14) indirectly axially comes into contact with the first contact surface (10) in such a way that the ring gear with the first end face (14) comes into direct axial contact with the retaining ring (12), the retaining ring (12) comes into contact with the first contact surface (10) of the first housing part (7) and the groove (13) is formed partly on the inner circumferential surface of the first housing part (7) and partly on the inner circumferential surface of the second housing part (8). [2] Planetary gear (1) according to any one of the preceding claims, characterized by , that the retaining ring (12) is made of a metal. [3] Planetary gear (1) according to claim 1 or 2, characterized by , that the retaining ring (12) is a closed ring. [4] Planetary gear (1) according to any one of the preceding claims, characterized by , that the two housing parts (7, 8) are screwed together. [5] Motor vehicle with a planetary gear (1) according to any one of claims 1 to 4.

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