DE102014213138A1 - Gear and gear arrangement with the gear - Google Patents

Abstract

Gear pairs are used for transmission and / or implementation, in particular translation and reduction, of torques in gears. The invention has for its object to provide a gear and a gear arrangement which runs quiet and at the same time reliable. For this purpose, a gear 1, proposed, wherein the gear 1 has a rotation axis 4, with a plurality of teeth 2, wherein the teeth 2 each have a tooth tip region 5, a Zahnfußbereich 6, wherein the teeth 2 each have a recess 8, wherein the Recess 8 in a sectional plane, which is arranged perpendicular to the rotation axis 4, an outlet region 10, wherein the outlet region 10 forms an outlet gap 12 and is opened in the tooth tip region 5 in the radial direction with respect to the axis of rotation, and wherein the recess 8 is a central region 9, wherein the central region 9 is formed wider in the sectional plane than the outlet region 10.

Description

The invention relates to a toothed wheel, wherein the toothed wheel has an axis of rotation, with a plurality of teeth, wherein the teeth each have a tooth tip region, a tooth root region, wherein the teeth each have a recess, wherein the recess in a sectional plane which is perpendicular to the axis of rotation is arranged, has an outlet region, and wherein the outlet region forms an outlet gap and is open in the tooth tip region in the radial direction with respect to the axis of rotation. The invention also relates to a gear arrangement with this gear.

Gear pairs are used for transmission and / or implementation, in particular translation and reduction, of torques in gears. A common form of toothing for gears is the so-called spur toothing, wherein the profile of the tooth in the axial extent with respect to the axis of rotation of the gear is constant. Conventional Gerverzverzahnungen are characterized in operation often by a change of single and double engagement, wherein in single engagement, only one tooth of a gear with a tooth of the other gear contacted. In a double engagement, two teeth of the one gear contact two teeth of the other gear. Such a double engagement results on the one hand from the structural design of the gear pair and on the other hand by dynamic load and resulting elastic deformation of the gears during operation. The dynamic loads and resulting deformations lead to a Drehwegfehler the gear, which corresponds to an apparent or actual rotation of the toothing of the gear relative to the angular position of the gear. Due to the Drehwegfehler a geometrically based on a single engagement gear pair can come to a double engagement.

The transition from the single engagement to the double engagement leads to clearly audible noise excitations in the gear pairing. For this reason, e.g. used in vehicle transmission mainly helical gears for the gears. Other measures to reduce the noise excitations are corrections in the profile of the gears, e.g. in the case of height crowning or a tooth head take-back.

The publication DE 101 02 294 A1 proposes a tooth for a toothed wheel, wherein the tooth head is shockproof than the tooth flanks, whereby noises are reduced in the entrance shock. For impact-like design of the tooth head is encouraged to provide a running in the axial direction and opened in the radial direction groove. The groove walls of the groove are open convexly to the outside, the groove base is formed in a circular arc.

Also the publication JP 9004697 A1 relates to a gear with teeth, which have a recess. In this document, it is proposed to design the recess slit-shaped in order to reduce the generation of noise.

The publication GB 1251941 A , which is probably the closest prior art, also discloses a gear with teeth, wherein in the teeth comparatively long slots are formed, the alignment of which extend radially in a section perpendicular to the axis of rotation and in the axial direction with respect to the axis of rotation a gap form.

The invention has for its object to provide a gear and a gear arrangement which runs quiet and at the same time reliable. This object is achieved by a gear with the features of claim 1 and by a gear arrangement with the features of claim 7. Preferred or advantageous embodiments of the invention will become apparent from the dependent claims, the following description and the accompanying drawings.

In the context of the invention, a gear is proposed. The gear defined with its axis of rotation a rotation axis. The gear is particularly preferably formed of a metal, in particular steel. The gear has a plurality of teeth, wherein the teeth are arranged in the direction of rotation about the axis of rotation, in particular equidistant to each other. The teeth may point radially inward with respect to the axis of rotation so that the gear is formed as an internal gear; Preferably, however, the teeth are radially outward with respect to the axis of rotation so that the gear is formed as an external gear. In particular, the gear is formed as a spur gear, wherein the teeth are arranged circumferentially and directed radially outward.

If the teeth are considered closer, they each have a tooth tip region and a tooth root region. The Zahnfußbereich forms the transition of the tooth to a main body of the gear, the Zahnkopfbereich sitting on the Zahnfußbereich. The flanks of the teeth may be straight, convex or concave. In particular, the plurality of teeth forms an involute toothing for the gear.

At least one of the teeth, some teeth and most preferably all the teeth have a recess. The recess is designed in particular as a void volume in the tooth. Considering the tooth with the recess in a sectional plane, wherein the cutting plane is arranged perpendicular to the axis of rotation of the gear and in particular forms a radial plane to this, the recess comprises an outlet region. The outlet region forms an outlet gap and is opened via an outlet opening in the tooth tip region in the radial direction with respect to the axis of rotation. Thus, considering a radial vector emanating from the axis of rotation, for an internal gear, the outlet opening of the outlet gap is inwardly open towards the origin of the radial vector. In the case of an external gear, the outlet opening of the outlet area is opened in the direction of the radial vector away from the axis of rotation. The outlet opening is in particular introduced on a tip or on a flattened tip of the toothed wheel.

In the context of the invention, it is proposed that the recess has a central region, wherein the central region forms a common recess with the outlet region and wherein the middle region in the described sectional plane is wider than the outlet region in a direction perpendicular to the radial direction in the sectional plane. This results in a profile of the recess in the unloaded state, wherein the recess, starting from the outlet opening via the outlet region initially has a narrow free diameter, which widened in the central region.

The advantage of the invention is that a more complex geometry of the recess, the functional properties of the tooth with the recess and thus the gear can be positively influenced. By narrower compared to the central area outlet area can be achieved that it is usable as a target stop or as an emergency stop. In the case of a setpoint stop, it is provided that the outlet gap is closed in the case of a desired load on the toothed wheel, so that a loadable or rigid tooth tip region is formed. In an emergency stop it is provided that in the desired load range of the gear wheel, the outlet gap and / or the outlet area is always open, but can be closed when the tooth is overloaded. In the event that the outlet gap is closed, the rigidity of the tooth, in particular of the tooth tip region, is greatly increased, so that due to the increased stiffness an irreversible deformation of the tooth tip region is avoided and the operational reliability is increased.

In a preferred structural embodiment, the outlet region, in particular the outlet gap, is formed by two contact flanks, wherein the contact flanks are spaced apart so far from each other via the outlet gap in the unloaded state that they are at a load, in particular at a desired stop and / or at an emergency stop, to each other, in particular flat against each other. In this state, the abutment flanks can support each other and thus increase the rigidity of the tooth tip region.

It is particularly preferably provided that the contact edges are rectified in the unloaded state in the cutting plane, in particular arranged parallel to each other. It is thus also possible that the abutment edges in the cutting plane are inclined relative to one another in such a way that, when the outlet gap is closed, they lie exactly flat against one another in order to be able to distribute existing loads over a large area. Figuratively speaking, the contact edges work like the jaws of a pair of pliers, with the jaws also lying flat against each other when the pliers are closed.

In a preferred structural embodiment of the invention, the central region in the described sectional plane is formed as a circle, as an oval and in particular as an ellipse. In particular, in the training as an ellipse, the recess is elongated, so that wide areas in the radial direction of the tooth tip region can be formed by the recess elastic. An advantage of the design as a circle, oval or ellipse lies in the fact that at the bottom of the central region, ie on the side facing away from the outlet, a rounding is formed so that no damaging notch forces can be introduced into the tooth from the inside.

In a preferred embodiment of the invention, the teeth have a straight toothing, wherein the profile of the recess in the course of the tooth is constant in the axial direction at least over 50% of the axial width, preferably over at least 70% and in particular over the entire axial width. This embodiment ensures that the load on the tooth is uniform over the axial width.

Another object of the invention relates to a gear arrangement with a gear according to one of the preceding claims and with a counter gear, wherein gear and counter gear are engaged with each other. Particularly preferably, the gear arrangement forms a part in a vehicle transmission, wherein via the gear arrangement, a drive torque of the vehicle is passed.

In a preferred embodiment of the invention, the gear arrangement is designed so that gear and counter gear are either temporarily or even constantly in double engagement. For example, the profiles of the teeth are formed as high gears.

In a preferred embodiment of the gear arrangement is provided that is closed at at least one angular position between the gear and counter gear of the outlet gap, wherein the outlet portion forms a desired stop. By reducing the gap width of the outlet gap, the region of the tooth tip is switched to "stiff" and further yielding of portions of the region of the tooth tip is prevented.

In another possible design of the gear arrangement is provided that the outlet gap is always open and in particular in each angular position of the gear between the gear and counter gear, the outlet, in particular the outlet form an emergency stop. In this design, the recess is thus designed so that it always has a minimum width in the outlet area as an open gap width, but at peak load or overload of the gear assembly goes into attack and prevents irreversible damage to the tooth in this way.

Due to the inventive design of the recess in the teeth of the gear is achieved that the stiffness profile of the flanks, in particular in a transition from the Zahnfußbereich is changed in the tooth tip region. By the recess is implemented that the tooth tip area compared to the Zahnfußbereich less stiff and thus softer, especially shockproof, is.

By this adapted stiffness curve is also achieved that the so-called Drehwegfehler the gear is reduced. The rotational path error of the gear is in principle formed by an apparent or actual displacement of teeth relative to the gear in the circumferential direction due to a load of the teeth. Figuratively speaking, the tooth is loaded in the direction of rotation, wherein the tooth then evades in the direction of rotation and is displaced. Especially in the case of the double engagement results in a discontinuous course of the rotary path error on the engagement division, being alternated between a negative Drehwegfehler and a positive Drehwegfehler depending on whether a single engagement or a double engagement is present. The inventive adaptation of the teeth through the recess can be achieved that the Drehwegfehler based on the amount of the maximum rotational path error with identical teeth without recess can be reduced to half or less.

Further features, advantages and effects of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. Showing:

1 a schematic sectional view or side plan view of a tooth of a gear as an embodiment of the invention;

2 a schematic sectional view or side plan view of a gear assembly with the gear of the 1 ;

3 a graph showing simulation results for the rotational path error of the gear arrangement in the 2 and to comparative gear arrangements.

The 1 shows a highly schematic top view or sectional view of a gear 1 in indicated form as well as a tooth 2 of the gear 1 which is representative of a plurality of teeth 2 is. The gear 1 is designed as a spur gear and has a center 3 on, through which a rotation axis 4 goes, being the center 3 or the axis of rotation 4 through the rotation of the gear 1 are defined. The gear 1 is as a spur gear with radial with respect to the axis of rotation 4 outward facing teeth 2 educated. The teeth 2 extend in the axial direction with respect to the axis of rotation 4 into the picture plane. In particular, the teeth 2 formed with a spur, so that the profile of the teeth 2 does not change in the axial direction.

The tooth 2 can in a tooth tip area 5 as well as in a tooth root area 6 be divided. Over the toothfoot area 6 is the tooth 2 to the gear 1 tethered. The tooth tip area 5 closes radially outward with respect to the axis of rotation 4 to the tooth root area 6 at. The tooth 2 has tooth flanks 7a and 7b on, which are convexly curved in the example shown outward. For example, it can be at the tooth flanks 7a , b is an involute gearing. The gear 1 is formed of a metal, in particular of steel. Particularly preferred is the gear 1 manufactured in one piece and / or one-material. For example, the gear is 1 made by a separating machining of a semi-finished product.

In the tooth 2 , especially in the area of the tooth tip 5 is a recess 8th arranged, which are in a middle area 9 and in an outlet area 10 divides. The recess 8th can on the two areas 9 . 10 be limited, but there may be more areas. The recess 8th extends with a constant profile over at least 50% of the axial extent of the tooth 2 , In particularly advantageous embodiments, the recess extends 8th in the profile shown, constant over the entire axial width of the tooth 2 , The outlet area 10 has an outlet opening 11 which acts as a slot on the radial outside of the gear 1 , in particular the tooth tip area 5 is formed and extends over the entire axial width of the tooth 2 extends. The outlet opening 11 is through an outlet gap 12 formed, which in the sectional plane shown in the radial direction with respect to the axis of rotation 4 extends. The outlet gap 12 is by two contact edges 13a , b, which are formed in the embodiment shown as baking a pair of pliers. The outsides of the plant flanks 13a , b in the circumferential direction are through the tooth flanks 7a , b formed. The mutually facing inner sides are supported by contact surfaces 14a , b, which are rectified or even parallel to each other.

The outlet area 10 goes to the middle area 9 over, which is formed in the sectional plane shown as an ellipse. The radial vector starting from the axis of rotation 4 which passes through the receiving gap 12 runs, also goes through the main axes of the ellipse. This is the middle range 9 arranged symmetrically to this radial vector. The radial extent of the central region 9 is at least twice as long as the radial extent of the outlet area 10 , The entire recess 8th takes about 1/3 of the tooth height of the tooth 2 to complete.

The contact edges 13a , b, in particular their contact surfaces 14a , b are in an unloaded state of the tooth 2 separated from each other by one nip width. The gap width is dimensioned so that the contact edges 13a , b elastic and not yet plastically deformed to form a mutual stop and / or physically, in particular contact flat.

Through the recess 8th becomes the stiffness course of the tooth 2 Changed, with targeted the tooth tip area 5 compared to the tooth root area 6 is formed softer. In particular, a stiffness curve of the tooth flanks results 7a , b being the stiffness starting from the tooth root area 6 to the tooth tip area 5 constantly decreasing.

The 2 shows in the same sectional plane or top view of the gear 1 and a counter gear 15 which are engaged with each other and a gear arrangement 18 form. In this particular case are gear 1 and counter gear 15 with the same teeth 2 executed. However, it can also be provided that only one of the gears 1 . 15 recesses 8th wears and the other gear 15 . 1 conventionally made of a solid material. In the 2 is the gear 1 the driving gear and rotates counterclockwise.

In the 2 the transitional state is shown, wherein from a single engagement at the position 16 to a double engagement at the position 16 and the position 17 is passed. A similar result is obtained when the gear arrangement shown 18 always in double engagement, wherein in the state shown the main load at the position 16 and a partial load at the position 17 he follows. The teeth 2 of the gear 1 be in order as 2.1.1 and 2.1.2 , the teeth 2 of the counter gear 15 With 2.15.1 and 2.15.2 designated. In the illustrated state, the gear presses 2.1.1 against the gear 2.15.1 , Due to the load, the outlet gap becomes 12 of the tooth 2.1.1 closed so that it has a gap width of near 0 or even closed so that the contact surfaces 14a , b contact each other flat and form a stop. Due to the elastic behavior of the abutment 15a There is no or only a small Drehwegfehler for the gear 1 or for the gear 15 , The leading tooth 2.15.1 of the counter gear 15 has an outlet gap 12 with unchanged gap width compared to the unloaded state. The lagging tooth 2.15.2 On the other hand, we are in his tooth-head area 5 already from the lagging tooth 2.1.2 pushed so that the outlet gap 12 of the tooth 2.15.2 already closed something.

In the 2 In addition, the comparison voltage according to von Mises is shown as surfaces, whereby it can be seen that at the point of contact between the teeth 2.1.1 and 2.15.1 the greatest load prevails, but this in the main body of the tooth 2 is derived.

The 3 shows in a graph different curves to illustrate the technical effect of the recess 8th in the tooth 2 , In the graph are on the X-axis, the relative engagement distance and on the Y-axis of the Drehwegfehler in mrad of the driving gear 2 plotted. A vertical line indicates the end of a period of engagement.

The curve I relates to a single engagement of teeth, the teeth are straight teeth and no recess 8th or have adapted edge correction.

The curve II shows the Drehwegfehler on the relative engagement distance in a double engagement in a straight toothing without recess 8th and without edge correction. It can be seen that the Drehwegfehler of the driving gear 1 initially negative, as long as the gear 1 with the counter gear 15 in a Single intervention is available. With transition to double engagement the Drehwegfehler is suddenly positive. This condition remains the same throughout the entire double intervention. Towards the end of the engagement division, the relative rotational path error again becomes negative via a jump. In the curve III the same tooth geometry is used, but this has a recess 8th on how these in the 1 and 2 is shown. It can be seen from the plot that the absolute value, in particular the absolute maximum value of the rotary path error, is only half or less compared to the absolute value of the original rotary path error. In the curve IV an identical tooth contour is shown in the same mating, but the flank has been corrected. It can be seen here that the edge correction forms similar but slightly weaker potential as the stiffness correction.

In the curve V For comparison, the rotational path error is plotted over the relative engagement path of a helical gearing. Helical gearing is the best technological alternative according to this plot. However, it must be noted that helical gears produce axial forces and tilting moments which increase the load on all the connection components, so that shafts, bearings, housings etc. must be made stronger. Thus, a major advantage of the gearing according to the invention is to be seen in avoiding the resulting secondary forces. There are no axial forces and tilting moments generated, which wheel body, shafts, bearings, housings, etc. can be made smaller. Furthermore, a quieter performance is achieved compared to the same tooth geometry of solid material.

LIST OF REFERENCE NUMBERS

1

 gear

2

 tooth

3

 Focus

4

 axis of rotation

5

 Tooth head area

6

 tooth base

7

 tooth flank

8th

 recess

9

 the central region

10

 outlet

11

 outlet

12

 outlet gap

13

 bearing flank

14

 contact surface

15

 counter gear

16

 Position with individual intervention

17

 Position with double engagement

18

 gearing

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10102294 A1 [0004]
• JP 9004697 A1 [0005]
• GB 1251941 A [0006]

Claims (10)

Gear ( 1 ), wherein the gear ( 1 ) a rotation axis ( 4 ), with a plurality of teeth ( 2 ), whereby the teeth ( 2 ) each have a tooth tip region ( 5 ), a tooth root area ( 6 ), wherein the teeth ( 2 ) each have a recess ( 8th ), wherein the recess ( 8th ) in a sectional plane which is perpendicular to the axis of rotation ( 4 ), an outlet area ( 10 ), wherein the outlet region ( 10 ) an outlet gap ( 12 ) and in the tooth tip region ( 5 ) is opened in the radial direction with respect to the axis of rotation, characterized in that the recess ( 8th ) a middle area ( 9 ), the middle region ( 9 ) in the sectional plane wider than the outlet area ( 10 ) is trained. Gear ( 2 ) according to claim 1, characterized in that the outlet area ( 10 ) by two contact edges ( 13a , b), wherein the abutment flanks ( 13a , b) when the tooth is loaded ( 2 ) in the region of the tooth tip ( 59 abut each other. Gear ( 2 ) according to claim 2, characterized in that the abutment edges ( 13a , b) lie flat against each other in the loaded state. Gear ( 2 ) according to one of the preceding claims 2 or 3, characterized in that the abutment edges ( 13a , b) are arranged in the unloaded state parallel to each other. Gear ( 2 ) according to one of the preceding claims, characterized in that the middle region ( 9 ) is formed in the sectional plane as a circle, an oval or an ellipse. Gear ( 2 ) according to one of the preceding claims, characterized in that the teeth ( 2 ) form a spur toothing, wherein the profile of the recess ( 8th ) in the course of the tooth ( 2 ) in the axial direction over at least 50%, preferably over at least 70% and in particular over the entire axial width of the tooth ( 2 ) is constant. Gear arrangement ( 18 ) with a gear ( 2 ) according to one of the preceding claims and a counter gear ( 15 ), whereby gear ( 2 ) and the counter gear ( 15 ) are engaged with each other. Gear arrangement ( 18 ) according to claim 7, characterized in that the gear ( 2 ) and the counter gear ( 15 ) are in a double engagement. Gear arrangement ( 2 ) according to claim 7 or 8, characterized in that in at least one angular position of the gear ( 2 ) the outlet gap ( 12 ) of the gear ( 2 ) is closed, the outlet area ( 10 ) forms a nominal stop. Gear arrangement ( 2 ) according to claim 7 or 8, characterized in that the outlet gap ( 12 ) is always open, the outlet area ( 10 ) forms an emergency stop.

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