Method for producing a ring gear for a planetary gear train, and a modular system having such a ring gear

Abstract

A method for producing a ring gear for a planetary gear train, wherein a continuous profile is produced by an extrusion process and the continuous profile is subsequently cut to a predetermined cutting length in order to form a ring gear body.

Claims

1. A method for producing a ring gear for a planetary gear train, the ring gear having a ring gear body with internal toothing on the inside of the ring gear body, the method comprising the steps of: producing a continuous profile of the ring gear by an extrusion process involving extruding plastic, wherein the internal toothing is formed on the inside of the plastic ring gear body; rotating the continuous profile; and subsequently cutting the continuous profile of the plastic ring gear body without burrs by laser cutting on the rotating continuous profile to a predetermined cutting length in order to form the plastic ring gear body.

2. The method according to claim 1, wherein the continuous profile is cut several times at different cutting lengths.

3. The method according to claim 1, further comprising the steps of: providing an end plate and mounting the end plate on the ring gear body.

4. The method according to claim 3, wherein the end plate is joined to the ring gear body.

5. The method according to claim 3, further comprising the steps of producing the end plate from a plastic.

6. A modular system with planet gears and different ring gears which can be combined to form planetary gear trains with different stages, wherein the ring gears are each produced by a method according to claim 1.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) The invention is described below using a plurality of exemplary embodiments which are explained in more detail with reference to Figures. They show:

(2) FIG. 1 is an exploded schematic view of a planetary gear train;

(3) FIG. 2 is a schematic view of a continuous profile;

(4) FIG. 3 is a schematic view of several different ring gear bodies;

(5) FIG. 4 is a plan view of a ring gear;

(6) FIG. 5 is a flowchart for producing a ring gear 10; and

(7) FIG. 6 is an exploded schematic view of a ring gear body with an end plate.

DETAILED DESCRIPTION OF THE INVENTION

(8) In describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner to accomplish a similar purpose.

(9) FIG. 1 schematically shows a planetary gear train 1 which is formed from a ring gear 10 and planet gears 22 which engage in a sun gear mounted on a shaft 21. The ring gear 10 comprises a ring gear body 12 and is designed with an internal toothing 11 on the inside of the ring gear body 12. The ring gear body 12 is cut to a cutting length C. In the assembled state, the planetary gear train 1 can be operated in different configurations. In one exemplary embodiment, the ring gear 10 is fixed, i.e., it does not rotate during operation. The output is then received by the planet gears 22 rotating about a sun gear. The shaft 21 connected to the sun gear serves as a drive.

(10) In another exemplary embodiment, the ring gear 10 is designed to be rotating. In this instance, the output can be taken from the ring gear 10 and the shaft 21 serves as a drive. Of course, in further exemplary embodiments a reversed configuration is conceivable, in which the ring gear 10 acts as a drive and the output is taken from the shaft 21.

(11) FIG. 2 shows the ring gear 10 of FIG. 1 before it was cut from a continuous profile 16. In the illustrated exemplary embodiment, the continuous profile 16 is produced by an extrusion process and can have any length. In order to produce a ring gear 10 from the continuous profile 16, the continuous profile 16 is cut off along a cutting line L in such a way that a ring gear body 12 with a cutting length C is formed. In the illustrated exemplary embodiment, the continuous profile 16 is cut using laser cutting.

(12) The internal toothing 11 has already been formed during the extrusion process by the shape of the die used. After cutting off the ring gear body 12 from the continuous profile 16 along the cutting line L, a functional ring gear 10 is thus immediately present.

(13) FIG. 3 shows three ring gear bodies 12, 12, 12 which are cut from the same continuous profile 16 with different cutting lengths C1, C2, C3. In the illustrated exemplary embodiment, a thermoplastic, namely reinforced PBT, is used as material for the ring gear bodies 12, 12, 12. The various ring gear bodies 12, 12, 12 are combined to form planetary gear trains with different stages.

(14) FIG. 4 shows a ring gear 10 in a plan view. FIG. 4 clearly shows that internal teeth 11 which can engage in the teeth of a planet gear are provided on the inside 13 of the ring gear 10. In the exemplary embodiment shown, the ring gear 10 is designed as a rotating ring gear 10 so that the achieved gear ratio of the planetary gear train 1 can be taken from the ring gear 10.

(15) FIG. 5 shows a flowchart for a method for producing a ring gear 10. In step S1, a continuous profile is produced by an extrusion process. In the exemplary embodiment shown, a plastic is thereby used. In step S1, a plastic granulate can in particular be guided onto a screw and heated. In the molten state, the plastic granulates used are viscous. The screw conveys the granulate in the direction of the die and is therein pressurized. Under pressure, the molten plastic granulate is pressed through the die and thus forms the continuous profile 16. Cut from In step 2, a ring gear body 12 with a cutting length C, C1, C2, C3 is cut from the continuous profile 16. In the illustrated exemplary embodiment, a laser cutting method is used for cutting. In other exemplary embodiments, however, it is also possible to use water jet cutting or electric discharge wire cutting. After completion of step S3, a fully functional ring gear 10 is present.

(16) FIG. 6 shows a ring gear 10 with an end plate 15, which together form a housing 2. The end plate 15 is connected to the ring gear 10 by a joining method. In the illustrated exemplary embodiment, the end plate 15 is bonded to the ring gear 10. The end plate 15 forms a customer-specific interface and is therefore only connected to the ring gear 10 after the production of said ring gear 10.

(17) The person skilled in the art concedes that the above-described exemplary embodiments and embodiments merely have exemplary character, and that the individual aspects of the exemplary embodiments may be combined with one another without departing from the inventive concept.

(18) Modifications and variations of the above-described embodiments of the present invention are possible, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described.

LIST OF REFERENCE NUMBERS

(19) 1 Planetary gear train 2 Housing 10 Ring gear 11 Internal toothing 12, 12, 12, 12 Ring gear body 13 Inside 14 Outside 15 End plate 16 Continuous profile 21 Shaft on the sun gear 22 Planet gear C, C1, C2, C3 Cutting length L Cutting line S1, S2, S3 Step