WO2006061104A1

WO2006061104A1 - Toothed belt pulley

Info

Publication number: WO2006061104A1
Application number: PCT/EP2005/012605
Authority: WO
Inventors: Jürgen OSTERLÄNGER; Dieter Adler; Manfred Kraus; Ralf Mayer
Original assignee: Schaeffler Kg
Priority date: 2004-12-08
Filing date: 2005-11-25
Publication date: 2006-06-15
Also published as: DE102004058963A1

Abstract

The invention relates to a toothed belt pulley comprising a plastic gear rim (9, 33) which is sprayed onto a reinforcing ring (10, 29) that reinforces the gear rim (9, 33) and can be fixed to a shaft (24). Said reinforcing ring (10, 29) is formed from sheet metal in a non-cutting manner, and comprises a sleeve-type hub section (11, 31) that can be placed on the shaft (24), a sleeve-type jacket section (12, 30) that reinforces the gear rim (9, 33) and is radially interspaced from the hub section (11, 31), and a connecting section (13, 32) which connects the hub section (11, 31) to the jacket section (12, 30) in such a way that they form a single component.

Description

Name of the invention

Timing pulley

description

Field of the invention

The present invention relates to toothed belt pulleys and Kugelgewinde- gear, the spindle nut are connected to such pulleys.

From DE 31 51 447 A1, for example, pulleys are known, with a ring gear formed of plastic, which is connected to a sprocket reinforcing and fixable on a shaft reinforcing ring. The reinforcing rings listed there are made of several parts, but can be made in one piece according to the cited to the prior art DE 19 50 374 A and provided with a sprocket sprocket.

Object of the present invention is to provide a toothed belt pulley according to the features of the preamble of claim 1, which has a simple structure and is economical to produce. According to the invention this object is achieved in that the non-cutting formed from sheet metal reinforcing ring has a sleeve-shaped hub portion reinforcing a deni gear rim and radially spaced from the hub portion sleeve-shaped shell portion and a hub portion with the shell portion integrally connecting connecting portion. First, it is ensured by the one-piece design of the reinforcing ring with the hub portion formed thereon that proper centering of the hub portion is ensured to the sleeve-shaped shell portion. Furthermore, in a simple manner, a toothed belt pulley, which has a cavity for 4597-16-WO 2

Including additional components. This cavity is then bounded radially on the outside of the sleeve-shaped Manteiabschnitt and radially inwardly of the sleeve-shaped hub portion. In the axial direction of this cavity is then limited by the approximately disc-shaped connecting portion.

The reinforcing ring is preferably designed edge-free on its outer periphery in the region of the bending sections. A particularly rigid embodiment of a toothed belt pulley according to the invention provides a connecting portion which, viewed in longitudinal section, may be formed approximately step-wise from two disc-shaped sections arranged axially spaced from one another and from a sleeve-shaped section, the sleeve-shaped section integrally connecting two ends of the two disc-shaped sections , The end of the one disk-shaped portion may be formed by the inner circumference thereof, and the end of the other disk-shaped portion may be formed by the outer circumference thereof.

Preferably, the plastic is injection-molded only on the outer circumference of the sleeve-shaped jacket section for forming the ring gear, with the inner circumference of the jacket section defining a cavity of the toothed belt pulley. An encapsulation of the inner circumference of the sleeve-shaped shell portion is unnecessary if a sufficient rotationally fixed connection between the sprayed sprocket and the sleeve-shaped shell section is ensured. This rotationally fixed connection can be assisted, for example, by the fact that the shell section is provided on its outer periphery with a knurl which is enclosed by the plastic. Alternatively or additionally, the jacket section can be provided with passage openings from the outer to the inner circumference. The passage openings can be well penetrated by the molded plastic.

The hub portion may be provided at its inner circumference with a first 4597-16-WO 3

The recess and the shaft may be provided on its outer circumference with a second recess, wherein a radially resilient positive locking element engages in both recesses for the positive connection of the toothed belt pulley with the shaft. This compound has the advantage that the hub can be pushed axially onto the shaft without effort and is fixed in both the axial and in the circumferential directions on the shaft when the two recesses are perfectly opposite each other, so that the radially resilient positive locking element in both recesses spring into it.

Alternatively, the hub portion may be provided with a bead formed on its inner circumference and annularly disposed about the longitudinal axis, at least one filler opening being provided for filling a liquid curable substance into the bead. The hub portion of the reinforcing ring may, for example, have two seats arranged axially spaced apart from each other for proper alignment on the shaft, wherein the annular bead is arranged between these two seats. Now, if the liquid curable substance is filled into the bead, prevent the adjacent - and only with little or no distance from the shaft arranged - seating surfaces leakage of the liquid curable material from the bead. After curing of this substance a perfect positive connection is ensured both in the axial and possibly in the circumferential directions. As already explained above, the shaft in the region of the bead can also be provided with a knurling in this case, so that after hardening of the substance there is a positive connection in the circumferential directions.

Alternatively, the hub portion of the reinforcing ring may be provided with a slot penetrating the hub wall defining a radially inwardly deflectable tongue for engaging the tongue in a recess provided on the shaft. Also in this case, the pulley can be listed axially on the shaft without much effort. 4597-16-WO 4

When the tongue is properly located over the recess, by applying a radial force, this tongue can be formed into this recess. Also in this alternative embodiment, a proper connection of the toothed belt pulley with the shaft is ensured both in the axial and in the circumferential directions.

Ball screws have a rotatably mounted on a ball screw spindle nut, which are often connected to pulleys. The toothed belt pulley according to the invention is particularly suitable for use in a ball screw drive. The toothed belt pulley according to the invention can be pushed onto the spindle nut with little effort in the variations described and can be connected in a rotationally fixed manner to the spindle nut. Undesired deformations on the spindle nut during connection of the toothed belt pulley to the spindle nut are excluded. These spindle nuts have on their inner circumference on a helical ball groove. These spindle nuts must be ensured that no undesirable deformations of this ball groove occur. In a particular embodiment, a ball screw with a toothed pulley is provided which has a hub portion which is disposed at one axial end of the spindle nut, wherein the connecting portion of the reinforcing ring adjoins the axial end of the hub portion, which is located one end of the spindle nut initially. Since the hub portion in the region of the connection of the connecting portion has its greatest rigidity, - if the reinforcing ring is shrunk onto the spindle nut - deformation of the spindle nut at this end is not excluded. In order to avoid an adverse effect on the running of the balls rolling on the ball groove, this connecting portion is arranged directly at the end of the spindle nut. Regularly no balls are arranged in the ball circulation at the end of the spindle nut so that deformations remain without affecting the function of the ball screw. 4597-16-WO 5

The spindle nut may be provided on its outer circumference with one of the first recess opposite arranged second recess, wherein the resilient positive locking element engages in both recesses to secure the toothed belt pulley in the axial and / or circumferential direction against displacement.

This resilient positive locking element may initially be arranged completely in one of the two recesses and, after the toothed belt pulley has been placed on the spindle nut, and the two recesses are positioned in relation to each other, spring into the respective other recess. This procedure is easy to install and allows easy retrofitting of the timing belt pulley on the spindle nut. These two recesses can each be formed by an annular groove and the resilient positive locking element by a slotted spring ring. In this case, a perfect axial securing is formed with the intervention of the positive locking element in the annular grooves.

The hub portion of the toothed belt pulley may have a plurality of circumferentially spaced through bores and the spindle nut has a plurality of circumferentially spaced, and aligned with the through holes radial blind bores whose diameter is equal to or preferably greater than the diameter of the through holes, being passed through the through holes Rivet sleeves of rivets are nestled on the bore walls of the blind holes. This design of the rivet connection avoids the formation of rivet heads on the inner circumference of the spindle nut. The preferred gradation of the diameter of the through holes and the blind holes also ensures that the rivet is properly anchored in the subject hole. The rivet sleeve may additionally be nestled against the bore wall of the passage openings.

Such ball screws can be used as power steering in an electromechanically actuated rack and pinion steering of a motor vehicle 4597-16-WO 6

come. In such applications, it may happen that not the complete provided with the toothed belt ball screw can be installed in the steering. Rather, it may be necessary that first the ball screw is mounted without a toothed belt pulley, wherein the assembly of the toothed belt pulley takes place later. In this case, connection techniques must be provided which allow a perfect connection of the toothed belt pulley with the spindle nut. The toothed belt pulley according to the invention enables retrofitting, wherein high pressing forces are avoided.

The invention will be explained in more detail below with reference to five exemplary embodiments depicted in eleven figures. Show it:

FIG. 1 is a longitudinal sectional view of a ball screw drive with a toothed belt pulley according to the invention;

FIG. 2 shows the mounting of the toothed belt pulley on the spindle nut,

FIG. 3 shows an individual part of the ball screw drive from FIG. 1,

FIG. 4 shows a section and on an enlarged scale the item from FIG. 3,

5 shows a longitudinal section through the ball screw with a modified toothed belt pulley according to the invention,

FIG. 6 shows a riveted connection of the toothed belt disc with the spindle nut,

FIG. 7 shows a method step for producing the riveted connection in FIG. 6, 4597-16-WO 7

FIG. 8 shows a modified connection of the toothed belt pulley with the spindle nut,

FIG. 9 shows the connection from FIG. 8 along the longitudinal axis and

10 shows a further modified connection of the toothed belt and disc 11 with the spindle nut.

Detailed description of the drawing

FIGS. 1 to 4 show a toothed belt pulley according to the invention, which is fastened on a spindle nut 1. The ball screw drive comprises a radial ball bearing, on which the spindle nut 2 is mounted rotatably. On its inner circumference, the spindle nut 1 is provided with a helically arranged ball groove 3. Balls 4 roll in endless ball tracks 5 on the ball groove 3 of the spindle nut 1 and a ball groove 6 of a ball screw 7 from. In the present case, the ball screw is provided with a so-called outer deflection: arranged on the outer circumference of the spindle nut 1, here only dashed lines deflection 8 connect one end to a beginning of an endless ball track. 5

The toothed belt pulley comprises a ring gear 9 formed from plastic by injection molding, which is sprayed onto a reinforcing ring 10. The reinforcing ring 10 is made of sheet metal by deep-drawing and executed at its outer periphery in the region of bending sections without edges. The reinforcing ring 10 has the following sections: a sleeve-shaped hub section 11 placed on the spindle nut 1, a sleeve-shaped jacket section 12 radially spaced from the hub section, which reinforces the ring gear 9, and a connecting section integrally connecting the hub section 11 with the jacket section 12 13th 4597-16-WO 8

The toothed ring 9 forming plastic is presently sprayed exclusively on the outer circumference of the shell portion 12. For a perfect rotationally fixed connection of the ring gear 9 with the shell portion 12 of the sheath portion 12 is provided with a knurling 14, said radel- tion 14 is completely encapsulated by the plastic.

The toothed belt pulley is heated for mounting on the spindle nut 1. The inner diameter of the hub portion 11 is selected so that after cooling of the reinforcing ring 10 of the hub portion 11 is shrunk onto the outer circumference of the spindle nut.

To ensure additional axial securing of the toothed belt pulley on the spindle nut 1, the hub portion 11 is provided on its inner circumference and the spindle nut 1 on its outer circumference each with an annular groove 15, 16, wherein a slotted spring ring 17 engages in both annular grooves 15, 16 , FIG. 3 shows a view of the spring ring 17. It can be seen from this figure that the spring ring 17 is provided in a wave-like manner in the circumferential direction with radially outer wave crests 18 and radially inner wave valleys 19. The wave crests 18 engage in the annular groove 15 of the reinforcing ring 10 and the wave troughs 19 engage in the annular groove 16 of the spindle nut 1.

For mounting a dashed line in Figure 2 mated mounting cone 20 can be used. The slotted spring ring 17 is first inserted into the annular groove 15 of the reinforcing ring 10. The mounting cone 20 is frontally attached to the end of the spindle nut 1 and coaxial with the spindle nut 1. The reinforcing ring 10 with inserted spring ring 17 is initially listed axially on the mounting cone 20. The diameter of the extended end of the mounting cone 20 corresponds to the outer diameter of the spindle nut 1. If the pulley with the reinforcing ring 10 is listed on the spindle nut 1 so far that the spring ring 17 has reached the extended end of the mounting cone 20, this is completely 4597-16-WO 9

With further axial sliding of the toothed belt pulley, the reinforcing ring 10 now slides along the mantle surface of the spindle nut 1. If the two annular grooves 15, 16 are perfectly opposite, the prestressed slotted spring ring 17 additionally snaps into the annular groove 16 of the spindle nut 1 a.

The two annular grooves 15, 16 can also generally be referred to as the first and second recesses 21, 22, wherein the spring ring 17 can be referred to in general terms as a radially resilient positive locking element 23. In general terms, the spindle nut 1 may also be referred to as a shaft 24 and the hub portion as a hub 24a.

It can be seen from FIG. 1 that the connecting section 13, viewed in longitudinal section, is approximately step-shaped, consisting of two disk-shaped sections 25, 26 arranged axially spaced from one another and a sleeve-shaped section 27, wherein the sleeve-shaped section 27 has two ends of the two disk-shaped sections Sections 25, 26 integrally connected to each other. Between the disc-shaped sections 25, 26 and the sleeve-shaped sections 27, 12, 11, an angle of 90 ° is formed in each case. It can be seen from FIG. 1 that the toothed ring 9 is arranged axially spaced from the hub portion 11. The stepfömige training of the connecting portion 13 allows a rigid design of this connecting portion 13 over its axial extent.

It can also be seen from FIG. 1 that the jacket section 12 of the reinforcing ring 10 delimits an annular cavity 28. In this cavity 28, the deflecting pieces 8 of the outer deflection are housed protected.

FIG. 5 shows the ball screw drive as in FIG. 1, but with a modified toothed belt pulley. In this toothed belt pulley, the reinforcing ring 29 is provided with a sleeve-shaped jacket section 30, a sleeve-shaped jacket section 30. 4597-16-WO 10

hub portion 31 and provided with a disc-shaped connecting portion 32, wherein the connecting portion 32, the two sleeve-shaped sections 30, 31 integrally connected to each other. The jacket portion 30 of the reinforcing ring 29 is molded with plastic to form the ring gear 33. In this sprocket 34 located on the right side shelf 34 is listed after the injection molding of the ring gear 33 subsequently. Although an additional component is provided here. However, the finished molded sprocket with the reinforcing ring 29 can be led out axially from the injection mold without complex slide tools are required.

The hub portion 31 is warmly joined as well as in the above-described embodiment, and perfectly maintained on the spindle nut 1 in both the axial and circumferential directions.

In the figures ^' 6 and 7, the embodiment of Figure 5 is modified only in the region of the hub portion 31. The hub portion 31 is provided with through-holes 34 at a plurality of circumferentially spaced locations. The spindle nut 1 is provided with a plurality of distributed over the circumference arranged blind holes 34. The blind holes 35 are slightly larger in diameter than the through holes 34. The hub portion 31 is positively connected by means of rivets 36 with the spindle nut 1. The rivet 36 has a rivet mandrel 37 which is inserted into a rivet sleeve 38. The rivet sleeve 38 has a rivet head 39 for abutment with the lateral surface of the hub portion 31.

FIG. 7 shows the situation that the rivet mandrel 37 is pulled out of the rivet sleeve 38 while applying a tensile force. Under this extraction, the rivet sleeve 38 is first pressed against the bore wall of the blind hole 35 and then against the bore wall of the through holes 34. Finally, the rivet mandrel 37 ruptures at its predetermined breaking point and the rivet connection is made. Thereby, 4597-16-WO 11

that the diameter of the blind hole 35 is slightly larger than the diameter of the through holes 34 is reliably prevents the rivet 38 can be pulled out of the blind hole 35 when pulling out of the rivet mandrel 37: because the hub portion 31 partially covers the clear diameter of the blind hole 35th ,

In Figures 8 and 9, a further positive connection between the hub portion 31 and the spindle nut 1 is provided. The hub portion 31 is provided on its inner periphery with a molded annular bead 40. Axially on both sides of the bead 40 of the hub portion 31 is close to the outer periphery of the spindle nut 1 at. The hub portion 31 is provided in the region of the bead 40 with a filling opening 41 for filling a liquid, curable substance 42 in the bead 40. The spindle nut 1 is provided at its outer periphery in the region of the bead 40 with a knurling 43. In this way it is ensured that after curing of the liquid material a perfect positive connection is made.

FIGS. 10 and 11 show a further variant for the positive connection of the hub section 31 with the spindle nut 1. The hub portion 31 is provided with a hub wall penetrating slot 44 defining a radially inwardly deflectable tongue 45 for engagement with a recess 46 provided on the spindle nut 1. After sliding the timing pulley onto the spindle nut 1, the tongue 45 is radially inwardly into the Recess 46 bent into it, so that a perfect axial positive locking is guaranteed. LIST OF REFERENCE NUMBERS

1 spindle nut 31 sleeve-shaped hub

2 radial deep groove ball bearings cut

3 ball groove 32 disk-shaped Ver¬

4 ball binding section

5 ball track 33 sprocket

6 Ball groove 34 Through hole

7 Ball screw 35 blind hole

8 deflector 36 rivets

9 sprocket 37 rivet mandrel

10 Reinforcement ring 38 Rivet sleeve

11 Hub section 39 Riveting head

12 jacket section 40 bead

13 connecting portion 41 filling opening

14 knurling 42 hardenable fabric

15 ring groove 43 knurling

16 annular groove 44 slot

17 spring washer 45 tongue

18 wave crest 46 recess

19 wave valley

20 mounting cone

21 recess

22 recess

23 positive locking element

24 wave

25 disc-shaped section

26 sleeve-shaped section

27 sleeve-shaped section

28 cavity

29 reinforcing ring

30 sleeve-shaped Matelabschnitt

Claims

4597-16-WO 13

claims

1. pulley, with a ring gear formed from plastic (9, 33), the (9, 33) reinforcing and on a shaft (24) reinforcing reinforcing ring (10, 29) is injection-molded, characterized in that the Sheet metal formed without reinforcing ring (10, 29) on the shaft (24) attachable sleeve-shaped hub portion (11, 31), a sprocket (9, 33) and reinforcing the hub portion (11, 31) radially spaced sleeve-shaped shell portion ( 12, 30), and a hub portion (11, 31) with the sheath portion (12, 30) integrally connecting connecting portion (13, 32).

2. A toothed belt pulley according to claim 1, wherein the reinforcing ring (10, 29) is designed free of edges on its outer periphery in the region of the bending sections.

3. A toothed belt pulley according to claim 1, wherein the connecting portion (13) seen in longitudinal section approximately step-shaped from two axially spaced disc-shaped sections (25, 26) and a sleeve-shaped portion (27) is formed, wherein the sleeve-shaped portion (27). two ends of the two disc-shaped sections (25, 26) integrally connected to each other.

4. Toothed belt pulley according to claim 1, wherein only the sheath portion (12) of the reinforcing ring (10) at its outer periphery to form the ring gear (9) is provided with plastic, wherein the inner periphery of the shell portion defines a cavity (28) of the toothed belt pulley. 4597-16-WO 14

5. A toothed pulley according to claim 1, wherein the skirt portion (12) is provided on its outer periphery with a knurling (14) which is enclosed by the plastic.

6. Toothed belt pulley according to claim 4, wherein the hub portion (11) at its inner circumference with a first recess (22) and the shaft (24) are provided at its outer periphery with a second recess, wherein a radially resilient positive locking element (23) in both Recesses (21, 22) for positive connection of the toothed belt pulley with the shaft (24) engages.

7. A toothed pulley according to claim 1, wherein the hub portion (31) is provided with a molded on its inner circumference and annularly around the longitudinal axis bead (40), wherein at least one filling opening (41) for filling a liquid curable material

(42) is provided in the bead (40).

8. A toothed pulley according to claim 1, wherein the hub portion (31) is provided with a hub wall penetrating slot (44) defining a radially inwardly deflectable tongue (45) for engaging in a shaft provided on the recess (46).

9. ball screw for converting a rotary into a longitudinal movement, with a on a ball screw (7) rotatably mounted and as a shaft (24) formed spindle nut (1) on which the toothed belt pulley is arranged according to one or more of the preceding claims.

lO. A ball screw according to claim 9, wherein the boss portion (11, 31) is disposed at an axial end of the spindle nut (1) and the

Connecting portion (13, 32) to the axial end of the hub portion (31, 11) connects, which is located one end of the spindle nut (1) initially. 4597-16-WO 15

11. Ball screw drive according to claims 6 and 9, wherein the spindle nut is provided on its outer circumference with one of the first recess (21) arranged opposite second recess (22), wherein the resilient positive locking element (23) in both recesses (21, 22). engages to secure the pulley in the axial and / or circumferential direction against displacement.

12. Ball screw drive according to claim 11, wherein the resilient Formschlu- ßelement (23) initially completely in one of the two recesses

(21, 22) is arranged and after fitting the toothed belt pulley on the spindle nut (1) and positioning the two recesses (21, 22) to each other in the other recess (21, 22) springs.

13. Ball screw according to claim 11, wherein the two recesses (21, 22) in each case by an annular groove (15, 16) and the resilient positive locking element by a slotted spring ring (17) are formed.

14. Ball screw according to claim 14, wherein the hub portion (11, 31) fits tightly against the spindle nut (1), preferably by warm joining of the toothed belt wheel with the spindle nut (1).

15. Ball screw according to claim 9, wherein the hub portion (31) of the toothed belt pulley arranged a plurality of circumferentially distributed

Through holes (34) and the spindle nut (1) has a plurality of circumferentially distributed, and with the through holes (34) aligned radial blind holes (35) whose diameter is greater than the diameter of the through holes (34), wherein by Through holes (34) performed rivet sleeves (38) of rivets (36) to the bore walls of the blind holes (35) are nestled. 4597-16-WO 16

16. A ball screw according to claim 15, wherein the rivet sleeves (38) to the bore walls of the through holes (34) are nestled.

17. Ball screw according to claims 8 and 9, wherein the spindle nut (1) is provided on its outer circumference with the recess (46) for engagement of the tongue (45).

18. Use of the ball screw according to one or more of the preceding claims as power steering in an electromechanically actuated power steering rack gear of a motor vehicle for longitudinal displacement of the ball screw (7) having rack of the rack and pinion steering, wherein the toothed belt pulley is driven by an electric motor.