WO2011117055A2

WO2011117055A2 - Noise-optimized toothing system

Info

Publication number: WO2011117055A2
Application number: PCT/EP2011/053304
Authority: WO
Inventors: Samuel Billot; Stefan Tumback; Uwe Ehrenwall
Original assignee: Robert Bosch Gmbh
Priority date: 2010-03-26
Filing date: 2011-03-04
Publication date: 2011-09-29
Also published as: CN102918257B; JP5787975B2; WO2011117055A3; CN102918257A; DE102010003361A1; EP2553258A2; JP2013527892A

Abstract

The invention relates to an electric machine, in particular a starter device (10) for an internal combustion engine. It comprises a noise-optimized toothing system (232, 234) of two gearwheels (22, 25) which can be brought into engagement with one another. The noise-optimized toothing system (232, 234) is configured as an extra-deep toothing system on at least one of the gearwheels (22, 25), which extra-deep toothing system has an asymmetrical toothing profile (214).

Description

description

title

Noise-optimized gearing state of the art

DE 10 2008 042 434.5 relates to a reduction gear and a starter device for an internal combustion engine. By means of the reduction gear is a speed-reducing coupling between a drive shaft and a

Output shaft by means of at least two gears which are engaged with each other. The gears are formed straight toothed, the toothing between them is designed as a high toothing. The formation of the toothing as a high toothing makes it possible to significantly increase the overlap of the mutually engaged toothed component. A high toothing is a toothing in which the overlap of the toothing

> 2.0 is by reducing a normal engagement angle and preferably keeping it less than 20 °. In the design of the teeth as a high toothing steeper flanks, a larger profile coverage and lower occurring radial forces, which act on the storage of intermeshing gears. The high toothing is compared to the conventional one

Gearing geometry less sensitive to axial distance deviations and concentricity errors, also the smoothness is improved. Compared to a double helical gearing, which is also referred to as a helical gearing, a high gearing has the advantage that the used

straight toothed gears can be produced by means of conventional manufacturing processes and thus existing assembly processes can be maintained.

Frequently are for the speed-reducing teeth of pinion and

Sprocket used gears that have a conventional toothing. This has the disadvantage that vibrations are excited during operation, which worsen the acoustic properties of the teeth of starter pinion and ring gear. The resulting noise can sometimes be relatively loud and thus annoying.

To avoid the occurrence of such vibrations, for example, a spur gear is provided with a lower gear ratio. This measure improves the engagement conditions and reduces the

Generation of vibrations and the associated noise level. This improves the acoustic properties. The reduction of the

However, gear ratio also means that the dynamics of the starting device is changed, so that starting operations at extremely low temperatures can be affected. This in turn has the consequence that requirements of the customer's liability booklet can no longer be met or an adaptation of the requirements must be taken into account.

Further, in order to reduce the generation of these vibrations, helical toothing is provided between the intermeshing tooth partners, starting pinion and ring gear. This measure improves the engagement conditions and prevents the occurrence of vibrations and the associated noise level. This will cause the acoustic

Improved properties. The formation of a helical toothing, however, means that axial thrust forces act on the gears that the

Have helical teeth. This in turn means that in

Depending on the resulting thrust forces a corresponding bearing of the gears or the gears receiving waves must be provided. Also, the stiffness of the housing must be designed accordingly taking into account the thrust forces occurring. This leads to a complex design of the housing, which is now in the

Use of helical gears must intercept occurring axial forces.

This is accompanied by a significant increase in costs. Furthermore, there is a higher friction on the gears, which have a helical toothing, so that the efficiency of the teeth of the starter pinion and ring gear is deteriorated and thus the performance of the starter is reduced. This means that the starting ability of the starter device or of its Electric drive is reduced. To compensate for this, the power of the electric motor would have to be increased to ensure the necessary starting capability under all operating conditions. This has the consequence that the wear of the electric motor increases, in particular the wear of the commutation, so that the life of the electric motor is reduced. The advantageous vibration behavior of the helical gearing is offset by a deterioration of the efficiency and the more complex construction. Disclosure of the invention

According to the invention a toothing between two meshing gears, in particular a Andrehritzels, a starter device and a ring gear of an internal combustion engine is proposed, characterized by the noise level and the vibration behavior of the toothing

Andrehritzel and ring gear is significantly improved. By the proposed solution according to the invention, the high efficiency of a conventional spur toothing is substantially maintained. Following the solution proposed by the invention, the toothing between the

meshing gears designed as a high toothing, the

Traces of the gears are facilitated. At least one of the intermeshing wheels is an asymmetric geometry of

Gear profiles provided, which extends at least over part of the axial length of the toothing.

The proposed solution according to the invention, on the one hand, a compact design and on the other hand, a significantly increased life in a cost-effective design of the teeth of starter pinion and

Sprocket can be achieved. The mating pairing off

Starter pinion and ring gear is provided with an optimized toothing, which has a special profile to reduce the noise level during a starting operation of the internal combustion engine with meshing sprocket of the internal combustion engine and Andrehritzel the starting device. The optimized design of the pairing starter pinion and ring gear has the advantage that the optimized toothing significantly improves the operation in acoustic Way is optimized, ie overall, the noise level drops significantly. In addition, a compact and cost-saving design is possible. The cost savings are achieved in particular by the fact that a spur toothing is still used. As a result, axial forces can be avoided, which would otherwise have to be absorbed by structural measures of the bearing and the housing of the starting device. The storage of the drive and the crankshaft or the gears can be designed following the solution proposed according to the invention such that no or only small axial forces are to be absorbed. The improvement of the acoustic properties is achieved in that the toothing is designed as a high toothing. This allows an increase in

Profile coverage of the intermeshing gears, resulting in improved noise and vibration behavior. That reduced

Vibration level also has a positive effect on the service life of the optimized toothing between starter pinion and ring gear.

In the present case, noise-optimized high-toothing is understood as meaning a toothing in which the overlapping of the toothing is increased by reducing the normal-engagement angle and reducing the geometry of a tooth

Tooth head has a withdrawal of the tooth head profile. Furthermore, the high-toothing is designed such that in the region of the tooth root, a reinforcement of the Zahnfußprofils is shown. This results in steeper flanks, a larger profile coverage and lower radial forces acting on the bearing of the gears. Furthermore, by the withdrawal of the tooth head profile causing a reduction of a noise

Ideally, entry collisions at the start of engagement of the intermeshing gears prevented or significantly reduced. The reinforcement of the Zahnfußprofils increases the stiffness of the teeth, which also contributes to a significant reduction in the noise level occurring. The special profile performing high-gearing is significantly less sensitive to axial spacing deviations compared to a conventional tooth geometry

Runout; Furthermore, the smoothness of the meshing gears is significantly improved. In an advantageous embodiment of the high toothing, this has an effective minimum profile coverage of about 1 or greater than 1 between the

Andrehritzel and the sprocket on. The tooth height should be designed so that the uncorrected involute area achieves an effective minimum profile coverage of> 1 between the starter gear and the ring gear. This condition is fulfilled when the circle diameter d _Fa is chosen such that the engagement line g _a obeys the relationship g _a = 1 ^* p _et , where p _e t denotes the (front) engagement pitch. The profile coverage e _a represents the ratio of the engagement distance g _a to the preoperative pitch p _et . The prone engagement pitch p _et = m _t ^* π ^* cosa _t is the distance between two right or left edges on the engagement line. With these

Interference on the teeth can also be realized a load capacity optimization of the toothing.

By the measures described above, the requirements are met on the one hand optimal noise and vibration behavior, on the other hand to a sufficient strength of the meshing gears. The increase of the profile overlap occurs, among other things, through the use of a reduced module for a specific gear ratio on the gear pair, which is to be determined by the following design:

The module used must be selected according to strength, so that the load capacity is given in the area of the teeth of the toothing. The minimum usable module is according to experience at 1, 0 mm. However, this value is to be understood only as an indicative value since, if necessary, a lower modulus can also be possible by using improved materials.

In a further development of the solution proposed according to the invention, the high-toothing has a normal engagement angle of 10 ° to 35 °, preferably about 15 ° or about 25 °. The reduction of the normal engagement angle of the high gear results in steeper flanks, greater profile coverage and lower radial forces. Thus, the high-toothing compared to a conventional geometry is less sensitive to axial spacing deviations and concentricity errors, even the smoothness is improved. In the case of non-cutting toothings, the pressure angle can be reduced to approximately 10 °, in particular if the profile coverage is> 1, 0 is. If the toothing is hobbed off, the pressure angle can change

For example, be reduced to 15 °. By appropriate measures, for example, to increase the strength by selecting a different material, and normal pressure angle of <10 ° can be achieved.

An advantageous embodiment of the proposed solution according to the invention is given by the fact that the toothed feet of the high-toothing have a shape deviating from a Trochoidenform. The tooth root radius of the toothing is reduced by the use of a smaller module. The Zahnfußform is advantageously replaced by a corrected Zahnfußverrundung to improve the Zahnfußfestigkeit instead of a conventional rounding of the tooth root. The optimized Zahnfußform deviates from the previously formed Trochoidenform.

In a further development of the solution proposed according to the invention, it is provided that the tooth heads of the high toothing have a modified head region. In the region of the tooth tip, the flank can be formed, for example, by means of a slight head rounding adapted to the module used.

Alternatively, a head cancellation may be provided. The

Head return is represented by three mutually tangential radii, which are different, connecting each tooth flank and tooth head together. This last measure allows a shock-free inlet of force-transmitting tooth flanks, so that the wear

is lowered and the noise level is reduced.

Furthermore, advantageously, the inventively proposed high-toothing can be produced by means of a conventional manufacturing process. There are no additional manufacturing steps to make so that the teeth can be made relatively inexpensive.

In an advantageous embodiment of the invention proposed solution, the output shaft of the starter device is associated with a freewheel. About the freewheel can be prevented that the already started internal combustion engine applied to the drive shaft of the reducer with a high speed and thus, for example, a connected via this electric motor damaged. By the freewheel unilateral torque transmission is realized, so that the torque can be transmitted only from the drive shaft to the output shaft and not in the reverse direction.

Following the solution proposed according to the invention, the following acts

High toothing with an asymmetric geometry on the tooth profile, which runs at least over a limited length of the toothing together. The asymmetric geometry of the tooth profile can both in the frontal region of the ring gear of the internal combustion engine as well as in the frontal region of the sprocket of the

Internal combustion engine to be inserted in the axial direction Andrehritzels the starter device be executed. As part of the asymmetric geometry of the tooth profile, the toothing is designed such that the tooth thickness of either the Andrehritzels or the ring gear of

Internal combustion engine over a certain tooth width, starting from the front end side of the respective gear, only one-sided, i.

is asymmetrically reduced, and on this reduced tooth thickness region, a desired backlash assumes a value of, for example, 0.3 mm. Consequently, this design allows the usual tooth width, in which the tooth thickness is not reduced, can be designed with a much lower backlash. By combining these two measures, on the one hand, the meshing of the starting pinion in the sprocket is secured and, on the other hand, the noise level of the meshing teeth is noticeably lowered. The reduction of the tooth thickness to represent an asymmetrical geometry of the tooth profile can be done regardless of the direction of rotation of the starter device on the right or the left respective tooth flanks of the intermeshing teeth of the toothing. When designing the asymmetrical gearing, it must be taken into account that the safety for flank compression and for

Tooth root stress can be maintained both in the range of reduced tooth thickness and on the configured in normal tooth thickness range. As regards the design of asymmetric gearing, the procedure should be as follows: When designing a noise-optimized spur gear, a reduction of the backlash is sought. At the same time, a minimum backlash of 0.3 mm should be maintained to secure the meshing of the Andrehritzels in the outer teeth of the ring gear of the internal combustion engine. When designing the gearing, proceed as follows:

1 . In a first design step, an optimized

Gear geometry designed to ensure that a specified minimum foot and a minimum edge safety is maintained. The backlash present in the optimized gearing geometry may be less than 0.3 mm.

2. In a second design step, one of the optimized

Gear geometry derived according to the first step

Gearing geometry with reduced tooth width derived to achieve the required backlash of 0.3 mm. It is

Make sure the same tooth root radius as the one in the first

Process step optimized gearing geometry is used. The reduction of the tooth width can be achieved by setting a smaller one

Profile displacement factor, for example, be made at the starter pinion, the tip diameter is to be maintained.

3. In a third design step, it is assessed whether the specified minimum foot safety is complied with after the second design step.

If the minimum foot safety of the tooth geometry corresponds to the second safety step of a reference toothing according to the second design step, then the optimized tooth geometry is permitted according to the first design step. If this is not the case, in the optimized gearing according to the first design step, a module increase should be made and the process according to the second design step and the third

Designing step, i. the evaluation, be repeated.

Short description of the drawing The invention will be explained in more detail below with reference to the examples shown in the drawings.

a starter device of an internal combustion engine with a pair of intermeshing toothings of starter pinion and ring gear, a side view of a toothing pair of starter pinion and ring gear with noise-optimized high-gearing,

Figure 3 is a side view of the noise-optimized high gear and

Figure 4 is a view of an asymmetrical design

Gearing geometry on an end face of a starter pinion of a starter device or a ring gear of a

Internal combustion engine.

variants

FIG. 1 shows a starter device 10 in a longitudinal section. The

Starter device 10 includes, for example, a starter motor 13 and a

Vorspuraktuator 16 (for example, relay, starter relay) on. The starter motor 13 and the electric Vorspuraktuator 16 are connected to a common

Drive end plate 19 attached. The starter motor 13 functions to drive a starting pinion 22 when it is meshed with a ring gear 25 of an internal combustion engine not shown in FIG. The starter motor 13 has as

Housing a pole tube 28 which carries on its inner circumference pole pieces 31, which are each wrapped by a field winding 34. For starters smaller

Power classes are here, instead of the pole piece 31 and field winding 34 and permanent magnets conceivable. The pole shoes 31 in turn bypass an armature 37, which has a built-up of lamellae 40 anchor packet 43 and in grooves 46 arranged armature winding 49 has. The armature package 43 is pressed onto a drive shaft 44. At the end of the drive shaft 13 facing away from the starting pinion 22, a commutator 52 is mounted, which among other things is made up of individual commutator bars 55. The commutator bars 55 are so electrically connected in a known manner with the armature winding 49, that upon energization of the commutator fins 55 by carbon brushes 58, a rotational movement of the armature 37 in the pole tube 28 results. A arranged between the electric drive 16 and the starter motor 13 power supply 61 supplies in the on state, both the carbon brushes 58 and the

Excitation winding 34 with power. The drive shaft 44 is commutator side supported with a shaft journal 64 in a sliding bearing 67, which in turn is held stationary in a Kommutatorlagerdeckel 70. Of the

Commutator bearing cap 70 in turn is fastened by means of tie rods 73, which are distributed over the circumference of the pole tube 28, so for example screws, for example two, three or four pieces, in the drive end plate 19. It supports the pole tube 28 on the drive end plate 19 and the

Commutator bearing cap 70 on the pole tube 28.

In the drive direction, a sun gear 80 connects to the armature 37 of the starter device 10, the part of a planetary gear, such as a

Planetary gear 83, is. The sun gear 80 is surrounded by a plurality of planetary gears 86, usually three planet wheels 86, which are supported by means of rolling bearings 89 or plain bearings on journals 92. The planet gears 86 roll in a ring gear 95, which is radially mounted in the pole tube 28 of the starter 10. Towards the output side closes to the planetary gears

86, a planet carrier 98, in which the stub axles 92 are received. The planet carrier 98 is in turn stored in an intermediate storage 101 and a slide bearing 104 arranged therein. The intermediate bearing 101 is designed cup-shaped, that in this both the planetary carrier 98 and the planet gears 76 are added. Furthermore, in cup-shaped

Intermediate bearing 101, the ring gear 95 is arranged, which is ultimately closed by a lid 107 relative to the armature 37. Also, the intermediate bearing 101 is supported with its outer circumference on the inside of the pole tube 28. The armature 37 has on the end remote from the commutator 52 of the

Drive shaft 44 a further shaft journal 1 10, which also in a Slide bearing 1 13 is included. The slide bearing 1 13 in turn is received in a central bore of the planet carrier 98. The planet carrier 98 is integrally connected to the output shaft 1 16. The output shaft 1 16 is supported with its end facing away from the intermediate bearing 101 1 19 in a further bearing 122 which is fixed in the drive bearing plate 19, supported.

The output shaft 1 16 is divided into several sections: the section located in the sliding bearing 104 of the intermediate bearing 101 is followed by a section with a straight toothing 125 (internal toothing), which is part of a shaft-hub connection 128. The shaft-hub connection 128 in this case allows the axially straight sliding of a driver 131st The driver

131 is a sleeve-like extension, which is integrally connected to a cup-shaped outer ring 132 of the freewheel 137. The freewheel 137 (Richtgesperre) further consists of the inner ring 140, which is radially within the

Outer ring 132 is arranged. Between the inner ring 140 and the

Outer ring 132 clamping body 138 are arranged. The clamp bodies 138, in cooperation with the inner ring 140 and the outer ring 132, prevent relative rotation between the outer ring 132 and the inner ring 140 in a second direction. In other words, the freewheel 137 allows a circumferential relative movement between the inner ring 140 and the outer ring

132 in one direction only. In this embodiment, the inner ring 140 is integral with the starter pinion 22 and its helical teeth 143

(External helical teeth) executed. The starter pinion 22 may alternatively be designed as a straight toothed pinion. Instead of electromagnetically excited pole pieces 31 with exciter winding 34, permanently magnetically excited poles could also be used.

The electric Vorspuraktuator 16 and the armature 168 also has the task of moving a tension member 187 in the drive bearing plate 19 rotatably mounted lever. This lever 190 is usually designed as a fork lever and engages with two "tines", not shown here, two disks 193, 194 on its outer circumference, thereby moving a pinched driving ring 197 between them against the resistance of the spring 200 and thus the starting pinion 22 in the sprocket 25 of the internal combustion engine, not shown in Figure 1 eingespurt.

Below is discussed in more detail on the Einspurmechanismus. The electric Vorspuraktuator 16 has a bolt 150, a

represents electrical contact and in the case of being installed in the vehicle at the positive pole of an electric starter battery, which is not shown here, is connected. The bolt 150 is passed through a lid 153. A second bolt 152 is a connection for the electric starter motor 13, which is supplied via the power supply 61 (thick wire). The lid 153 includes a housing 156 made of steel, which is fastened by means of a plurality of fastening elements 159 (screws) on the drive end plate 19. In the electric Vorspuraktor 16, a pusher 160 for exerting a tensile force on the fork lever 190 and a switching device 161 is arranged. The

Pusher 160 has a winding 162, the switching device 161 has a winding 165 on. The winding 161 of the pusher 160 and the winding 165 of the switching device 161 each cause in the on state an electromagnetic field which flows through various components. The shaft-hub connection 128 may take place with a

Spur gearing 125 may also be provided with a steep thread toothing. The combinations are possible, according to which a) the starting pinion 22 is helically toothed and the shaft-hub connection 128 has a straight toothing 125, b) the starting pinion 22 is helically toothed and the shaft-hub connection 128 has a helical toothing or c) the Andrehritzel 22 is spur-toothed and the shaft-hub connection 128 has a helical toothing.

FIG. 2 shows, on the basis of a single tooth, the design according to the invention of an asymmetric toothing with a high toothing with a partially reduced tooth width in the front region of the toothing. Following the solution proposed according to the invention, an asymmetric toothing 214 will be described below with reference to a single tooth 202. In the single tooth 202 may be a tooth of a toothing, which is preferably formed as a straight toothing. The single tooth 202 shown in FIG. 2 with an asymmetrical toothing 214 can be formed either on the outer toothing of a starting pinion 22 as shown in FIG. 1 or on an outer circumference of a toothed ring 25 which serves to turn on an internal combustion engine. In the single tooth 202 shown in FIG. 2, a tooth flank 204 is formed in a tooth width 206. Following the solution according to the invention, it is proposed that on the tooth flank 204, as shown in FIG. 2, within a front region 228 extending from an end face 32 of FIG

Single tooth 202 extends along a reduced tooth width 208, a reduced tooth thickness 212 is formed. The reduced tooth thickness 212 extends from the end face 230 of the single tooth 202 along the reduced tooth width 208 up to a transition flank region 226. Within this transition flank region 226 on the tooth flank 204, the reduced tooth thickness 212 gradually transitions to an original tooth thickness 210. This means that the asymmetric toothing 214 is formed on the tooth flank 204.

By the asymmetric toothing 214, the combing of the

Individual teeth 202 of Andrehritzel 22 and ring gear 25 of the

Internal combustion engine can be significantly improved without the

Securing of a safe tracking of the twisting pin 222 in the

External teeth of the ring gear 25 of the internal combustion engine would be at risk. The inventively proposed asymmetric

Gearing 214 is designed so that the tooth thickness 210 within the front portion 228 of the single tooth 202 - seen from the end face 230 of the Andrehritzels 22 or the ring gear 25 - on the reduced

Tooth width 208 is performed only on one side of the tooth flank 204 of the single tooth 202, so that within this front portion 228 a tooth flank 204 of the single tooth 202 has a reduced tooth thickness 212. Along this front region 228, characterized by the reduced tooth thickness 212 along the reduced tooth width 208, is a desired backlash for example, 0.3 mm. This causes the gearing over the

remaining part of the tooth width 206 minus the reduced tooth width 208, can be designed with a significantly lower backlash, which is less than 0.3 mm. By combining both measures, i. the formation of the asymmetric toothing 214 in the front region 228 of

Single tooth 202, based on the end face 230, and the reduction of the backlash along the tooth width 206 minus the reduced tooth width 208, on the one hand, a secure meshing of the Andrehritzels 22 in the

Toothed ring 25 ensured and on the other hand, the noise level

Combing the gearing significantly reduced.

For completeness, it should be mentioned that the single tooth 202 of the

asymmetric toothing 214 is a top circle of the single tooth 202 with the reference numeral 216, a partial circle of the single tooth 202 with the reference numeral 218 and the root circle with the reference numeral 220 is designated. Critical is one

Area within a tooth root 222 of the single tooth 202, whose

mechanical load when combing the individual teeth 202 of the asymmetrically designed toothing 214 may not be exceeded. Reference numeral 226 designates the transition flank region within which the reduced tooth thickness 212 changes to the original tooth thickness 210.

When designing the described asymmetrical toothing 214, it should be taken into account that the edge-pressing security against the stress occurring in the region of the tooth root 220 is maintained both in the region of reduced tooth thickness 212 and in the region which is not reduced, i.e. in the region of reduced tooth thickness 212. the original tooth thickness 210 is formed. The following procedure is used to design the asymmetric toothing 214 proposed according to the invention: In the design of the noise-optimized, e.g. formed as a straight toothing asymmetrical teeth 214, the reduction of the backlash of the tooth flanks 204 of the individual teeth 202 is sought. At the same time it is used to secure the safe tracking of the

Andrehritzels 22 in the teeth of the ring gear 25 at least one

Torsional backlash of 0.3 mm complied with. To counter these opposing effects The following procedure is proposed when interpreting the gearing:

As a first step, the design of an optimized gear geometry for maintaining a foot tension safety at the tooth root 222 of the single tooth

202 and according to the interpretation of a Fußrundung 224 and a

Compliance with maximum allowable edge voltages that occur on the tooth flanks 204 of the individual teeth 202. For the optimized gear geometry to be designed in the first step, the backlash may be below 0.3 mm.

In a further second design step, a tooth geometry with a reduced tooth width 208 is derived from the optimized tooth geometry derived in the first step when the required backlash of 0.3 mm is reached. In this case, the same radius is to be used on the tooth root 222 as in the case of the optimized tooth geometry obtained according to the first method step. The reduced tooth width 208 can, starting from the original tooth width 206, by setting a smaller profile displacement factor, for example in the manufacture of

Andhrhritzels 22 are obtained. The tip diameter of the tip circle

216 of the single tooth 202 of the asymmetric toothing 214 is not to change.

If, in a third evaluation step, the safety on the tooth root 222 of the tooth geometry is at least equal to that derived from a proven one

Gearing geometry specified minimum footing, then the determined in the first step optimized gearing geometry is allowed. If, in the third method step representing an assessment, it is ensured that the safety in the tooth root 222 of the tooth geometry is at least equal to that of the reference toothing according to the present design step, then the optimized tooth thickness determined in the first method step

Gear geometry are allowed. If, on the other hand, this is not fulfilled, then in the optimized method determined and designed in the first method step Gearing a module increase the interpretation of the gearing are made and the subsequent two process steps, ie the second and the third process step, be run through again.

The tip diameter 216 is highlighted in Figure 2 with d _a , the pitch diameter 218 d and the root diameter d _f .

FIG. 3 shows a side view of a toothed pairing of starting pinion and ring gear with noise-optimized high-toothing.

The illustration according to FIG. 3 shows that individual teeth 202 of the toothed rim 25 of the internal combustion engine and of the starting pinion 22 of the starter device 10 mesh with one another. Both the ring gear 25 of the internal combustion engine and the starting pinion 22 of the starter device 10 are shown only partially in the illustration according to FIG. A

External teeth of the ring gear 25 of the internal combustion engine is designed as a noise-optimized high gear 232, which meshes with individual teeth 202 and also designed as a noise-optimized high gear teeth 234 external teeth of the starter device. In the illustration according to FIG. 2, the starting pinion 22, which is mounted on the output shaft 16, is meshed with the ring gear 25 of the internal combustion engine.

The illustration according to Figure 4 is a side view of the noise-optimized high toothing can be seen, both on the sprocket of the

Internal combustion engine can be designed as well as to be einzupurenden Andrehritzel the starter device.

FIG. 4 shows that a single tooth 202 of the noise-optimized high-toothing has tooth flanks 204, which in contrast to conventional ones

Gearing profiles 238 have modified areas. The modified regions of the tooth flanks 204 of the noise-optimized toothing proposed according to the invention, ie the high toothing 232, 234, on the one hand have a reinforced tooth root 236 formed in comparison to the conventional tooth root profile 238 and one by reference numeral 240 in FIG Contrary to the conventional tooth profile trained tip retraction 240 below the tip diameter d _a 216.

The embodiment of the noise-optimized toothing illustrated in FIG. the high-toothing 232, 234, which can be formed both on a trained as spur external teeth of Andrehritzels 22 of the starter device 10 and on the formed as a spur external teeth of the ring gear 25 of the internal combustion engine, characterized by an effective minimum profile coverage of about 1 or> 1 between the Andrehritzeln and the ring gear 25 off. An essential goal of the design of the high-toothing is to design the toothed sleeve such that the uncorrected involute region is an effective one

Minimum profile coverage of> 1 between the starter pinion 22 and the ring gear 25 achieved. This condition is fulfilled when the

Form circle diameter d _Fa is chosen so that the engagement distance g _{a of} the relationship g _a = 1 ^* p _et obeys, where p _e t denotes the (front) engagement division. The profile overlap εα is defined as the ratio of the engagement distance to the (front) engagement pitch p _et . The (front) engagement pitch p _et = m _t ^* π ^* cosa _t is the distance between two right or left flanks along the engagement line. If the high-toothing is designed in this way, the requirement on the one hand for the optimum noise and vibration behavior and on the other hand for a sufficient strength of the meshing gears 22, 25 are met. The increase of the profile coverage occurs among other things by the

Use of a reduced modulus for a given gear ratio on the intermeshing gear pair, to be determined by the following considerations:

The modulus used should be selected such that load-bearing tooth bases 222 are obtained. The minimum usable module is according to experience at 1, 0 mm. However, this value is to be understood only as an indicative value, since the use of improved materials also means a

Reduction of the module can be achieved.

The inventively proposed noise-optimized teeth 232, 234, in particular formed as a high toothing, is provided with a Normal engagement angle of 10 ° to 35 °, preferably a little 15 ° or slightly 25 ° provided. By reducing the normal engagement angle for the

High gearing results in steeper flanks 204, a larger one

Profile coverage and lower occurring radial forces. This is the high toothing compared to a conventional geometry

insensitive to axial spacing deviations and concentricity errors, furthermore, the smoothness is not significantly improved. In non-cutting produced teeth 232, 234, the normal engagement angle can be reduced to about 10 °, especially if a profile coverage of> 1, 0 is given. If the toothing is hobbed off, the normal engagement angle can be reduced, for example, to 15 °. By increasing the strength, usually given by a different choice of material, the normal engagement angle can also assume values smaller than 10 °. The toothed feet 222 of the noise-optimized toothings 232, 234 have, in particular, a shape deviating from the trochoidal shape. Tooth root rounding 224 is significantly reduced by the use of the smaller module. For example, to improve tooth root strength, the tooth root mold can advantageously replace the conventional fillet 224 of the tooth root 222 with a corrected version. This is done while maintaining the engagement of the intermeshing

Individual teeth 202 of the noise-optimized toothing 232, 234. Advantageously, as shown in FIG. 4, the tooth heads of the noise-optimized toothing 232, 234 are provided with a modified head region. in the

Tooth region, the tooth edge 204, for example, by a module adapted to the module used each slightly rounded or

Head return 240 may be modified. Both measures allow a shock-free inlet of the force-transmitting tooth flanks 204. This, on the one hand, reduces wear and, on the other hand, reduces the generation of noise.

When designing the inventively proposed noise-optimized teeth 232, 234 with an asymmetric tooth profile 214, as shown in Figure 2, it should be noted that the security

Flank compression and for tooth prestressing both in the area of reduced tooth thickness 212 and on the area formed in the normal tooth thickness 210, is maintained. The following will be for that A procedure for obtaining an asymmetrical tooth profile 214

proposed:

In the design of the noise-optimized toothing 232, 234, in particular as a straight toothed high toothing is a reduction of

Tilting game aimed for. At the same time to secure the secure Einspurens the Andrehritzels 22 in the ring gear 25 a

Minimum backlash of about 0.3 mm. When designing the noise-optimized toothing 232, the following procedure is shown:

As a first step, the design of an optimized gear geometry to comply with a minimum foot and minimum flank safety. The

Torsional backlash may be less than 0.3 mm in this design.

Based on the optimized gearing geometry according to the first step, a gearing geometry is derived, which is a reduced

Tooth width 208 to achieve the required backlash of 0.3 mm. The same Zahnfußradius as in the optimized

To use gearing geometry according to the first step. The

Reduction of the tooth width can be achieved by setting a smaller one

Profile displacement factor at the starter pinion 22 are made for example, the tip diameter 216 should not be changed.

In a third design step, if the foot safety of the

Gearing geometry according to the second method step is at least equal to the foot safety at a reference gearing, the optimized

Gear geometry approved according to the first method step. If the comparison is negative, the first method step for obtaining an optimized tooth geometry should be carried out by a module increase and the subsequent method steps 2) and 3) should be repeated.

Claims

claims

Electric machine, in particular starter device (10) for a

Internal combustion engine, with a noise-optimized toothing (232, 234) of two intermeshable gears (22, 25), characterized

in that the noise-optimized toothing (232, 234) is embodied on at least one of the toothed wheels (22, 25) as high toothing, which has an asymmetrical toothed profile (214).

Electric machine according to the preceding claim, characterized

characterized in that tooth heads of the noise-optimized toothing (232, 234) have a modified head region, in particular a tip retraction (240).

Electric machine according to one of the preceding claims, characterized in that toothed feet (222) of the noise-optimized toothing (232, 234) have a shape deviating from the trochoidal shape.

Electrical machine according to claim 1, characterized in that the high toothing has an effective minimum profile coverage of about 1 or> 1 between a starter pinion (22) and a ring gear (25) of

Internal combustion engine has.

Electrical machine according to one of the preceding claims, characterized in that the high-toothing (232, 234) a

Normal engagement angle of 10 ° to 35 °, preferably about 15 ° or about 25 °.

6. Electrical machine according to one of the preceding claims, characterized in that the noise-optimized toothing (232, 234) as

Straight toothing is formed.

7. Electrical machine according to one of the preceding claims, characterized in that the noise-optimized toothing (232, 234)

Single teeth (202) whose tooth thickness (210) in a front region (228), starting from an end face (230), in a reduced tooth thickness (212) is executed.

8. Electrical machine according to the preceding claim, characterized

characterized in that the reduced tooth thickness (212) extends along a reduced tooth width (208), starting from the end face (230) of the

Andhrhritzels (22) or the sprocket (25) extends.

9. Electrical machine according to one of the preceding claims, characterized in that a backlash (228) in the reduced tooth thickness (212) along the reduced tooth width 208, between 0.2 mm and 0.8 mm, preferably at 0.3 mm.

10. Electrical machine according to the preceding claim, characterized

characterized in that the backlash outside the front region (228) is less than 0.3 mm.

1 1. Electrical machine according to one of the preceding claims, characterized in that tooth flanks (204) on which the reduced tooth thickness (212) along the reduced tooth width (208) is executed, a

Transition flank region (226), within which the reduced tooth thickness (212) merges into the tooth thickness (210).

12, starter device (10) of an internal combustion engine with a starter pinion (22) which is einspurbar in a ring gear (25) of the internal combustion engine, characterized in that at least one of the teeth of the Andrehritzels (22) and / or the ring gear (25) as noise-optimized Gearing (232, 234) is formed.