GEARWHEEL WITH AN INSERT PORTION MADE OF METAL AND AN OUTER PORTION MADE OF PLASTIC, STEERING MECHANISM WITH SUCH A GEARWHEEL AND METHOD FOR PRODUCING SUCH A GEARWHEEL

Abstract

A gearwheel has an insert portion made of metal and an outer portion made of plastic, where the outer portion has a toothed rim and the outer portion is injection-molded onto the insert portion. The outer portion has a plurality of injection-molded sections formed on a side surface of the insert portion which surface is directed transversely or perpendicularly to the central longitudinal axis. To produce the gearwheel inexpensively and with sufficiently good physical properties as regards its load-bearing capacity and its useful life. The gearwheel is characterized in having injection-molded sections spaced apart from one another on the side surface of the insert portion and side surface areas of the insert portion are left free between directly adjacent injection-molded sections.

Claims

1. A gearwheel (1, 27, 29, 35) comprising: an insert portion (2) made of metal; and an outer portion (3) made of plastic, wherein the outer portion (3) comprises a toothed rim (4) with a plurality of teeth (6) directed outward relative to a central longitudinal axis (5) of the gearwheel (1, 27, 29) and the outer portion (3) is injection-molded onto the insert portion (2), wherein the outer portion (3) has a plurality of injection-molded sections (7) on a side surface (8) of the insert portion (2) which is directed transversely to the central longitudinal axis (5), and wherein the plurality of injection-molded sections (7) on the side surface (8) of the insert portion (2) are positioned a distance apart from one another and side surface areas (9) of the insert portion (2) between directly adjacent injection-molded sections (7) are left free.

2. The gearwheel according to claim 1, wherein a side (34) or further side surface (19) of the insert portion (2) is completely uncovered by the plastic of the outer portion (3), and the insert portion (2) has a form selected from (i) a cylindrical hub or disk-shaped hub or a hub with an inner cylinder (30), (ii) an outer cylinder (31), and (iii) an annular disk (32) connecting the inner cylinder (30) to the outer cylinder (31).

3. The gearwheel according to wherein each of the injection-molded sections (7) has a three-sided shape, wherein one corner (10) of each injection-molded section (7) extends radially inward toward the central longitudinal axis (5), wherein each injection-molded section (7) has two side edges (13, 14) arranged such that between the two side edges (13, 14) an obtuse angle opening radially outward relative to the central longitudinal axis (5) is formed, and wherein the plurality of injection-molded sections (7) are distributed uniformly around the central longitudinal axis (5).

4. The gearwheel according to claim 1, wherein the insert portion (2) defines a central through-going opening (16) and/or an axle wherein, a corner (10) of each injection-molded section (7) is spaced from the through-going opening (16) and/or the axle, and an annular side surface area (17) of the side surface (8) between the injection-molded sections (7) and the through-going opening (16) and/or axis is left free.

5. The gearwheel according to claim 3, wherein the radially inward-directed corner (10) of each injection-molded section (7) is curved and defines a radius, such that a notional full circle (26) with that radius lies completely on the side surface (8) of the insert portion (2) and coincides flush with an outer circumference of the insert portion (2).

6. The gearwheel according to claim 1, wherein the toothed rim (4) has an annular rim section (18), wherein an inner circumference of the rim section (18) is arranged on an outer circumference of the insert portion (2) and an outer circumference of the rim section (18) corresponds to a root circle diameter for the teeth (6) of the toothed rim (4), and an edge section (15) of each injection-molded section (7) directed radially outward relative to the central longitudinal axis (5) is arranged at least partially or completely between the inner circumference of the rim section (18) and the root circle diameter, and the edge section (15) projects radially, relative to the central longitudinal axis (5), outward into the root circle diameter in an area of the teeth (6)).

7. The gearwheel according to claim 6, wherein the edge section (15) of each injection-molded section (7) has a shape of a section of a circle, wherein the edge sections (15) of all the injection-molded sections (7) lie on a common circle and are arranged concentrically with the central longitudinal axis (5), and wherein a thickness of each injection-molded section (7) decreases at least in part in the direction toward the edge section (15).

8. The gearwheel according to claim 6, wherein the edge section (15) of each injection-molded section (7) has a flow contour (20) with at least one chamfer and/or with at least one rounded edge (21 22), the flow contour (20) having a first rounded edge (21) with a first radius being curved convexly outward, and a second rounded edge (22) with a second radius being curved concavely inward, and wherein the second rounded edge (22) is formed between the rim section (18) and the first rounded edge (21).

9. The gearwheel according to claim 1, wherein the outer portion (3) has three injection-molded sections (7) distributed around the central longitudinal axis (5) with 120 spacing.

10. (canceled)

11. (canceled)

12. The gearwheel according to claim 1, wherein the outer portion (3) has four injection-molded sections distributed around the central longitudinal axis (5) with 90 spacing.

13. A steering mechanism for a vehicle, comprising the gearwheel (1, 27, 29, 35) according to claim 1, wherein the teeth (6) of the toothed rim (4) form a helical tooth array configured to cooperate with at least one worm gear or at least one worm shaft.

14. A method for producing a gearwheel (1, 27, 29, 35) according to claim 1, the method comprising: placing the insert portion (2) in an injection-molding die; and injection-molding the outer portion (3) by way of a hot runner manifold (23), wherein the hot runner manifold (23) has a plurality of outlet points (24) arranged for forming the outer portion (3), the plurality of outlet points (24) corresponding in number to a number of injection-molded sections (7) to be formed, wherein the outlet points (24) are directed toward the side surface (8) of the insert portion (2).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Below, the invention is explained in greater detail with reference to the figures. In the figures, the same indexes denote the same, similar or functionally equivalent components or elements. The figures show:

[0027] FIG. 1: A first perspective side view of a first gearwheel according to the invention,

[0028] FIG. 2: A second perspective side view of the first gearwheel according to the invention shown in FIG. 1,

[0029] FIG. 3: A sectioned side view of the first gearwheel according to the invention shown in FIGS. 1 and 2,

[0030] FIG. 4: A further perspective side view of the first gearwheel according to the invention shown in FIGS. 1 to 3, with a schematically indicated hot runner manifold,

[0031] FIG. 5: A first perspective side view of a second gearwheel according to the invention,

[0032] FIG. 6: A second perspective side view of the second gearwheel according to the invention shown in FIG. 5,

[0033] FIG. 7: A perspective side view of a third gearwheel according to the invention,

[0034] FIG. 8: A sectioned side view of the third gearwheel according to the invention shown in FIG. 7, and

[0035] FIG. 9: A sectioned side view of a further gearwheel according to the invention.

DETAILED DESCRIPTION

[0036] FIG. 1 shows a first perspective side view of a first gearwheel 1 according to the invention. The gearwheel 1 is designed for a steering mechanism (not shown here), for example a steer-by-wire steering mechanism. In this example embodiment, the gearwheel 1 is made as a two-component gearwheel. Accordingly, the gearwheel 1 comprises an insert portion 2 and an outer portion 3.

[0037] The insert portion 2 is made of metal and the outer portion 3 is made of plastic. The outer portion comprises a toothed rim 4, wherein the toothed rim 4 comprises a plurality of teeth 6 directed radially outward relative to a central longitudinal axis 5 of the gearwheel 1. In this example embodiment, the teeth 6 of the outer portion 3 form a helical tooth array. For the sake of greater clarity not all the teeth 6 are indexed.

[0038] The outer portion 3 is injection-molded around the outer circumference of the insert portion 2. In addition, the outer portion 3 comprises a plurality of injection-molded sections 7. In this example embodiment the outer portion 3 has a total of three injection-molded sections. The injection-molded sections 7 are formed integrally or in one piece with the toothed rim 4. The insert portion 2 has a side surface 8 that extends at a right-angle to the central longitudinal axis 5. All the injection-molded sections 7 are arranged on the side surface 8 or in contact with the side surface 8. In this case the injection-molded sections 7 are distributed uniformly around the central longitudinal axis, namely here at an angle of 120 apart from one another. By means of the injection-molded sections 7 the insert portion 2 is fixed at least in an axial direction relative to the central longitudinal axis 5.

[0039] The injection-molded sections 7 are a distance apart from one another on the side surface 8. In this example embodiment the injection-molded sections 7 do not merge directly with one another. Instead, side surface areas 9 of the side surface 8 between injection-molded sections 7 immediately adjacent to one another in the circumferential direction relative to the central longitudinal axis 5 are left completely free. Since in this case there are three injection-molded sections 7, in this example embodiment, there are three corresponding free side surface areas 9.

[0040] The injection-molded sections 7 each have a three-sided and/or triangular basic shape. Correspondingly, the injection-molded sections 7 have a first corner 10, a second corner 11, and a third corner 12. The first corner 10 of each injection-molded section 7 is directed radially inward in the direction toward the central longitudinal axis 5. In this example embodiment, the first corner 10 is rounded. On the other hand, in this example embodiment, the second corner 11 and the third corner 12 are each define an acute angle.

[0041] The injection-molded sections 7 have in each case two side edges 13 and 14. Between the two side edges 13, 14, starting from the first corner 10, an obtuse angle is formed which opens radially outward relative to the central longitudinal axis 5. In other words, as viewed radially inward, the two side edges 13 and 14 converge toward the first corner 10.

[0042] The two radially outward-directed ends of the two side edges 13, 14, or the two corners 11 and 12, are connected to one another by means of an edge section 15 of the injection-molded section 7 concerned. Thus, the edge section 15 and the first side edge 13 converge to form the second corner 11 and the edge section 15 and the second side edge 14 converge to form the third corner 12.

[0043] In this example embodiment, the edge section 15 of each injection-molded section 7 is in the shape of a circular segment. In contrast, in this example embodiment the side edges 13 and 14 are each straight. The circular segment shaped edge sections 15 of each injection-molded section 7 are located on a circle (not shown here and thus notional) and are concentric with the central longitudinal axis 5.

[0044] In this example embodiment, the insert portion 2 is in the form of a hub with an annular disk shape. Correspondingly, the insert portion 2 has a central through-going opening 16. For example, the gearwheel 1 can be pushed or pressed onto an axle (not shown here) in such manner that the axle passes through, or partially through the through-going opening 16.

[0045] In this example embodiment, the injection-molded sections 7, or the first corner 10 of each injection-molded section 7, is a distance away from the through-going opening 16. Consequently, an annular side surface area 17 of the side surface 8 of the insert portion 2 between the injection-molded sections 7 and the through-going opening 16 is left free. Thus, the annular side surface area 17 radially inside relative to the central longitudinal axis 5, and likewise the side surface areas 9 of the insert portion 2, are not covered by the plastic forming the outer portion 3.

[0046] The toothed rim 4 of the outer portion 3 has an annular rim section 18. Thus, the toothed rim 4 is formed by the rim section 18, and the teeth 6 that extend from the rim section 18 extend radially outward relative to the central longitudinal axis 5. An inside circumference of the rim section 18 coincides with an outer circumference of the insert portion 2. Between the inside circumference of the rim section 18 and the outer circumference of the insert portion 2 an interlock (not shown in greater detail here) is formed for fixing the inside circumference of the rim section 18 onto the outer circumference of the insert portion 2. At the same time an outer circumference of the rim section 18 forms a root circle diameter of the teeth 6 of the toothed rim 4.

[0047] According to this example embodiment, the outward-directed edge section 15 of the injection-molded section 7 concerned is arranged at least partially between the inside circumference of the rim section 18 and the root circle diameter of the teeth 6 of the toothed rim 4. Thus, the injection-molded section concerned projects radially relative to the central longitudinal axis 5 beyond the outer circumference of the insert portion 2. In this example the edge section 15 projects radially outward relative to the central longitudinal axis 5 beyond the root circle diameter in the area of the teeth 6 or in the area of the tooth roots of the teeth 6.

[0048] FIG. 2 shows a second perspective side view of the first gearwheel according to the invention as shown in FIG. 1. The figure shows a side surface 19 of the insert portion 2 other than the side surface 8 that has the injection-molded sections 7 (which are not visible here). In this example embodiment, the further side surface 19 is not covered by the plastic of the outer portion 3. Thus, the plastic of the outer portion 3 is arranged exclusively on the side surface 8 shown in FIG. 1 to form the injection-molded sections 7 and around the outer circumference of the insert portion 2 to form the toothed rim 4. Alternatively, a design is possible in which the plastic of the outer portion 3 surrounds or embraces the outer circumference of the insert portion 2 so that the plastic of the outer portion 3 is also arranged on the further side surface 19. In that way the interlock between the outer portion 3 and the insert portion 2 can be improved.

[0049] FIG. 3 shows a sectioned side view of the first gearwheel 1 according to FIGS. 1 and 2. The transition of an injection-molded section 7 into the toothed rim 4 can be seen clearly. In this example embodiment, the edge section 15 of the injection-molded section 7 concerned has a flow contour 20. By virtue of the flow contour 20 the flow of the plastic is improved during injection-molding to form the outer portion 3.

[0050] In this example embodiment, the flow contour 20 has a first rounded edge 21 with a first radius, this first radius being curved convexly outward. In addition, in this example the flow contour 20 has a second rounded edge 22 with a second radius, this second radius being curved concavely inward. Thus, the second rounded edge 22 is between the rim section 18 and the first rounded edge 21. The first radius of the first rounded edge 21 merges into the second radius of the second rounded edge 22, and in this example the first rounded edge 21 and the second rounded edge 22 each extend over a quarter of a circle.

[0051] In this example embodiment, the thickness of each injection-molded section 7 is constant. Alternatively, the thickness of each injection-molded section 7 can decrease, at least in part, in the direction toward the edge section 15 and/or in the area of the edge section 15.

[0052] FIG. 4 shows a further perspective side view of the gearwheel 1 according to the invention according to FIGS. 1 to 3, with a schematically indicated hot runner manifold 23.

[0053] To produce the gearwheel 1, the insert portion 2 is placed in an injection-molding die (not shown here). The outer portion 3 is then injection-molded by way of the hot runner manifold 23. For that purpose, the hot runner manifold has a plurality of outlet points 24 for the plastic, the number thereof corresponding to the number of injection-molded sections 7 of the outer portion 3 to be formed, in order to produce the outer portion 3.

[0054] In this example embodiment, the hot runner manifold 23 has a total of three nozzles 25 (only schematically illustrated), each nozzle constituting an outlet point 24. The outlet points 24 or nozzles are directed toward the side surface 8 of the insert portion 2 in order to form the injection-molded sections 7 and the toothed rim 4 of the outer portion 3. For that purpose, the outlet points 24 or nozzles 25 are each arranged opposite an injection-molding point.

[0055] According to this example, such an injection-molding point corresponds to a mid-point of a notional full circle 26 on the side surface 8 or in this case indicated on a top side of the injection-molded section 7. After the production of the injection-molded section 7 concerned, this full circle 26 is located within the injection-molded section 7. In this example embodiment the full circle 26 is bounded flush by an outer circumference of the insert portion 2 and flush by the radially inward-directed first corner 20 of the injection-molded section 7 concerned. The radially inward-directed first corner 20 of the injection-molded section 7 concerned is correspondingly rounded in the shape of a section of a circle. Thus, in this example embodiment the first corner 20 has a radius that is the same as the radius of the full circle 20. The full circle 20 corresponds to an impingement area on the side surface 8 of the insert portion 2 for injection-molding the injection-molded section 7 and forming the outer portion 3.

[0056] FIG. 5 shows a first perspective side view of a gearwheel 27 according to the invention. The structure and functional mode of the second gearwheel 27 corresponds largely to those of the first gearwheel 1 shown in FIGS. 1 to 4. The same features are denoted by the same indexes as before. Consequently, to avoid repetition reference should be made to the earlier description.

[0057] Other than in the gearwheel 1, the gearwheel 27 shown in this case has an insert portion 2 with an out-of-round outer circumference. In correspondence thereto, the inner circumference of the outer portion 3, or toothed rim 4 with the rim section 18, is also out-of-round. This improves the interlock between the insert portion 2 and the outer portion 3.

[0058] In this example embodiment, a number of projections 28 are arranged or formed on the side surface 8. Each projection 28 is arranged in the area of the side surface section 9 and mid-way between two adjacent injection-molded sections 7. The projections 28 extend parallel to the central longitudinal axis 5. In this example, the projections 28 have a height that corresponds to the thickness, or to a maximum thickness of the injection-molded sections 7. Furthermore, in this case the projections 28 have the shape of a truncated cone.

[0059] By virtue of the projections 28, to produce the gearwheel 27 the insert portion 2 can be placed in an injection-molding die (not shown here) in a predetermined and correctly orientated position. For that purpose, the injection-molding die has recesses corresponding to the projections 28, into which the projections fit with interlock. Positioning of such an insert portion 2 in the injection-molding die in this way is particularly advantageous when the insert portion 2 is out-of-round, as in this case, in order to ensure reproducible orientation of the insert portion 2 relative to the injection-molded outer portion 3, in particular with improved after-pressure feeding during the injection-molding of the outer portion 3.

[0060] FIG. 6 shows a second perspective side view of the second gearwheel 27 according to the invention shown in FIG. 5. In this case the out-of-round contour of the outer circumference of the insert portion 2 and of the inner circumference of the toothed rim 4 and the rim section 18 corresponding to it can be seen clearly.

[0061] In this example embodiment as well, the further surface 19 is not covered by the plastic of the outer portion 3.

[0062] FIG. 7 shows a perspective side view of a third gearwheel 29 according to the invention. The structure and functional mode of this further gearwheel 29 correspond largely to those of the first gearwheel 1 shown in FIGS. 1 to 4 and the second gearwheel 27 shown in FIGS. 5 and 6. The same features are denoted by the same indexes as before, so to avoid repetitions, reference should again be made to the earlier description.

[0063] Other than in the gearwheels 1 and 27, the gearwheel 29 shown here has an insert portion 2 wherein the insert portion 2 in this example embodiment comprises an inner cylinder 30, an outer cylinder 31 and an annular disk 32. In this case the insert portion 2 is made integrally or in one piece. Furthermore, the inner cylinder 30 is connected to the outer cylinder 31 by means of the annular disk 32. Thus, the annular disk 32 is arranged between the inner cylinder 30 and the outer cylinder 31.

[0064] In detail, in this example embodiment, the annular disk 32 connects an end of the inner cylinder 30, axial relative to the central longitudinal axis 5, to an axial end of the outer cylinder 31. The annular disk 32 extends perpendicularly to the central longitudinal axis 5. Accordingly, the insert portion 2 in this example embodiment has an annular recess 33 extending in the direction of the central longitudinal axis 5. In this case the side surface 8, not visible here, is arranged on a side of the insert portion 2 facing away from a side 34 with the recess 33.

[0065] FIG. 8 shows a sectioned side view of the third gearwheel 29 according to the invention shown in FIG. 7. It can be seen clearly that in the area of the transition from the inner cylinder 30 via the annular disk 32 to the outer cylinder 31 a U-shaped cross-section is formed.

[0066] FIG. 9 shows a sectioned side view of a further gearwheel 35 according to the invention. The structure and functional mode of this further gearwheel 35 correspond largely to those of the third gearwheel 29 according to FIGS. 7 and 8, so in order to avoid repetitions reference should again be made to the earlier description.

[0067] Other than in the third gearwheel 29, the further gearwheel 35 shown here has a web-like or strip-like connecting section 36 between directly adjacent injection-molded sections 7. In this example embodiment the connecting sections 36 are curved or shaped as ring segments. The connecting sections 36 are made from the plastic of the outer portion 3 and form part of the outer portion 3. Thus, the directly adjacent injection-molded sections 7 merge partially into one another on the side surface 8 by virtue of the respective connecting sections 36 between them. Furthermore, the connecting sections 36 merge into the toothed rim 4 of the outer portion 3. The connecting sections 36 are integral or one-piece constituents of the outer portion 3. At the same time however, in this further gearwheel 35 a side surface area 9 between the directly adjacent injection-molded sections 7 is also left free.

[0068] In the example embodiment according to the gearwheel 35 pictured here, the plastic of the outer portion 3 surrounds the outer circumference of the insert portion 2. Since the outer circumference of the insert portion 2 is surrounded, in this example the plastic of the outer portion 3 is also in contact with the inner circumferential side of the outer cylinder 31. Furthermore, in this example embodiment the plastic of the outer portion 3 extends into the recess 33 until it comes into contact with the annular disk 32. In this embodiment the interlock between the outer portion 3 and the insert portion 2 is improved.

INDEXES

[0069] 1 Gearwheel [0070] 2 Insert portion [0071] 3 Outer portion [0072] 4 Toothed rim [0073] 5 Central longitudinal axis [0074] 6 Tooth [0075] 7 Injection-molded section [0076] 8 Side surface [0077] 9 Side surface area [0078] 10 First corner [0079] 11 Second corner [0080] 12 Third corner [0081] 13 Side edge [0082] 14 Side edge [0083] 15 Edge section [0084] 16 Through-going opening [0085] 17 Annular side-surface area [0086] 18 Rim section [0087] 19 Further side surface [0088] 20 Flow contour [0089] 21 First rounded edge [0090] 22 Second rounded edge [0091] 23 Hot runner manifold [0092] 24 Outlet point [0093] 25 Nozzle [0094] 26 Full circle [0095] 27 Gearwheel [0096] 28 Projection [0097] 29 Gearwheel [0098] 30 Inner cylinder [0099] 31 Outer cylinder [0100] 32 Annular disk [0101] 33 Recess [0102] 34 Side [0103] 35 Gearwheel [0104] 36 Connecting section