DE102013106686A1 - gear - Google Patents

Abstract

The invention relates to a toothed wheel with a coating (21) and crowns (22) having teeth (20) which is produced by a sintering process, the coating (21) being applied before the production of the crowns (22) and the crowns (22 ) are made by a rolling process.

Description

The invention relates to a gear with a coating and crowning teeth, which is made by a sintering process.

In vehicles electric drives are used to realize different adjustment functions. In electric steering, a torque is transmitted to the rack by an engine via a transmission to facilitate steering. Modern vehicles offer the driver several comfort functions, such as electric windows and seat adjusters. In the above functions and also in wiper drives and in an electromechanical brake booster worm gears are mostly used.

Other fields of application for which the invention is suitable are electrical tools (screwdrivers, hammers, angle grinders, jigsaws) and drives for electric bicycles, electric scooters and electric vehicles. In these applications mostly planetary, helical and bevel gears are used.

The gears contained in the gears and the gears of other gear stages are made either of metal or of a polymer material. The worm / Schraubradgetriebe often used for noise reasons can be constructed very limited compact, since, for example, the output and drive shaft are deflected by 90 °.

The teeth often have straight tooth flanks. However, these gears are subject to a high tolerance and high wear. In addition, the noise emission during operation is undesirably high and the production by a cutting process is relatively expensive. In addition, the gears of a mostly inexpensive plastic over metal gears due to their lower strength the disadvantage of a larger space.

The invention has the object to produce the gear mentioned in the future cheaper and to avoid the disadvantages.

The invention solves this problem with a generic gear in which according to the invention, the coating is applied prior to the production of the crowns, wherein the crowns are made by a rolling process. Crowns are convexes that extend on tooth flanks in the axial direction of the gear. A high material waste generating cutting operation can thus be omitted in the future. In particular, by the rolling process, the gear can be produced inexpensively, since the unwanted material waste is avoided and the rolling process requires only a relatively short processing time. In addition, the rolling process allows the coating to be applied prior to the manufacture of the crowns. The coating reduces wear and noise. In principle, of course, other than the rolling process other known in the art forming operations for the production of the crowns possible. The gear may be in a preferred embodiment, a helical gear, whose teeth are arranged obliquely to the axial direction of the gear. The gear then has a helical toothing. It can therefore be used together with a worm shaft.

• • Herstellen des Zahnrades durch einen Sintervorgang,
• • Beschichten des Zahnrades,
• • Bombieren der Zähne durch einen Walzvorgang.

The invention also relates to a method for producing the gear which is characterized by the following steps:

• Producing the gear by a sintering process,
• Coating the gear,
• • Crowning the teeth through a rolling process.

Due to the cost-effective production of low-noise sintered metal gears according to the invention, the use of these gears instead of plastic gears is made possible. In addition, for example, spur gear stages can be installed in a close-to-motor arrangement with a fast-rotating motor shaft instead of inherently low-noise worm helical gear stages. This allows a comparison with the known very compact design in particular a control and wiper gear. For example, a two-stage gearbox of a Sitzverstellers consisting of a worm-Schraubradstufe and a spur gear or Evoloidstufe be represented by the use of metal gears considerably flatter. The replacement of a worm helical gear stage by a spur gear stage has the further advantage of a significantly improved gear efficiency.

The invention will be explained in more detail with reference to the accompanying drawings.

In detail show:

1 a perspective view of a tooth of a gear according to the prior art;

2 a perspective view of a tooth of a gear according to the invention.

1 shows a tooth 10 a gear not shown here from the prior art. The tooth 10 has a straight tooth flank extending in the axial direction 11 on. The disadvantage with the teeth 10 However, equipped gear are its high tolerances and high wear. It is also usually produced by a relatively expensive machining process.

In contrast, an inventive tooth 20 of the gear by a sintering process, so without cutting produced. This is a cheaper production of the gear 20 possible.

Besides, the tooth is 20 with a coating 21 provided, whereby its wear and noise emission can be reduced.

The tooth 20 has crowns 22 on, whereby the wear and the noise emission are also significantly reduced. The crowns 22 are convex curvatures that are located on tooth flanks 23 extend in the axial direction of the gear.

To additionally reduce the manufacturing costs, the crowns 22 manufactured after the coating.

The production of the crowns 22 is preferably carried out by a rolling process. The costly cutting process can also be avoided in this way.

The tooth 20 can be arranged obliquely to the axial direction of the gear and thus form a helical toothing. Thus, the gear can be operated together with a worm shaft.

LIST OF REFERENCE NUMBERS

10

tooth

11

tooth flank

20

tooth

21

coating

22

pressings

23

tooth flank

Claims (8)

Process for producing the gear, characterized by the following steps: - producing the gear by a sintering process, - coating the gear, - crowning the teeth ( 20 ) by a rolling process. A gear produced by the method according to claim 1, characterized in that the gear produced by a sintering process has teeth ( 20 ) comprising a coating ( 21 ) and crowns ( 22 ) exhibit. Gear according to claim 2, characterized in that the gear is designed with a straight toothing. Gear according to claim 2, characterized in that the gear is designed with a helical toothing. Steering gear for an electric power steering system, characterized in that it comprises a gear according to one of claims 2 to 4. Stell or wiper gear for vehicles, characterized in that it comprises a gear according to one of claims 2 to 4. Gear for electric tools, characterized in that it comprises a gear according to one of claims 2 to 4. Transmission for electric vehicles, characterized in that it comprises a gear according to one of claims 2 to 4.

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