SLEEVE-TYPE FREEWHEEL WITH TORQUE LIMITATION FOR TWO-WHEELED VEHICLE STARTER APPLICATIONS

Abstract

A clamping freewheel has a ring element, being either an inner ring or an outer ring. The ring element has a plurality of clamping ramps (or ramped surfaces) for clamping a clamping element (or roller). One clamping element is disposed between one of the clamping ramps and the ring element. At least one of the clamping ramps includes a first region and a second region, wherein the second region is configured as a power transmission region and the first region is configured as an overload region. Slipping between the ring element and another ring element is allowed while the clamping element is located and rolling along the first region. No slipping is allowed between the ring element and the other ring element while the clamping element is located and rolling along the second region.

Claims

1. A clamping freewheel comprising: a ring element being either an inner ring or an outer ring, the ring element having at least one clamping ramp; at least one clamping element, each clamping element bears on and rolls along a respective one of the at least one clamping ramps; wherein each of the at least one clamping ramps has at least one first subsection and one second subsection, wherein the second subsection is a force transfer region, such that a relative movement between the at least one clamping element and the ring element can be prevented, wherein the first subsection is an overload region, such that relative movement between clamping elements and the ring element is allowed via which a transfer of force from the ring element to the at least one clamping element can be prevented.

2. The clamping freewheel according to claim 1, wherein the first subsection allows for relative movement between clamping elements and the ring element in that a tangent of an angle () at a bearing point (A) between the at least one clamping element and the at least one clamping ramp, formed between a force (F) that is to be transferred perpendicular (N1) to the first subsection at the bearing point (A), is greater than or equal to a frictional coefficient () for materials force by the ring element and the clamping element, and wherein the second subsection prevents relative movement between the clamping elements and the ring element in that the tangent of a second angle () at the bearing point (A) between a clamping element and the clamping ramp, formed between a second force (F) that is to be transferred perpendicular (N2) to the second subsection at the bearing point (A), is less than the frictional coefficient () for the materials of the frictional pair formed by the ring element and the clamping element.

3. The clamping freewheel according to claim 2, wherein the first angle () for the first subsection is greater than 15, wherein the second angle () in the second subsection is between 3 to 4.5.

4. The clamping freewheel according to claim 1, wherein the ring element is made of sheet metal, and wherein the ring element is thin walled such that the ring element has a wall thickness outside the at least one clamping ramp that is less than half of the thickness of the at least one clamping element.

5.-9. (canceled)

10. A clamping freewheel assembly for selectively transferring torque therethrough, the clamping freewheel assembly comprising: an inner ring; an outer ring disposed about the inner ring and having an inner surface that defines a plurality of ramped surfaces; and a plurality of rollers, each roller configured to roll along a respective one of the ramped surfaces; wherein each of the plurality of ramped surfaces includes a first section ramped at a first pitch, and an adjacent second section ramped at a second pitch different than the first pitch; wherein a first torque of a first magnitude urges the rollers to clamp between the second section of the ramped surfaces and the inner ring, and a second torque of a second magnitude larger than the first magnitude urges the rollers to clamp between the first section of the ramped surface and the inner ring.

11. The clamping freewheel assembly of claim 10, wherein relative rotation between the inner ring and the outer ring is enabled while the rollers are contacting the first section of the ramped surfaces.

12. The clamping freewheel assembly of claim 11, wherein a tangent of an angle () at a bearing point (A) between the rollers and the ramped surfaces, formed between a force (F) that is to be transferred perpendicular (N1) to a first subsection at the bearing point (A), is greater than or equal to a frictional coefficient () for materials of the inner ring and the rollers.

13. The clamping freewheel assembly of claim 12, wherein the angle is greater than 15 degrees.

14. The clamping freewheel assembly of claim 12, wherein relative rotation between the inner ring and the outer ring is prevented when the second torque forces the rollers to contact the second section of the ramped surfaces.

15. The clamping freewheel assembly of claim 14, wherein a tangent of an angle () at the bearing point (A) between the rollers and the ramped surfaces, formed between a force (F) that is to be transferred perpendicular (N2) to the second subsection at the bearing point (A), is less than a frictional coefficient () for the materials of the frictional pair formed by the inner ring and the rollers.

16. The clamping freewheel assembly of claim 15, wherein the angle is between 3 and 4.5 degrees.

17. The clamping freewheel assembly of claim 10, wherein the first sections of the ramped surfaces includes a linear sections.

18. The clamping freewheel assembly of claim 10, wherein the second sections of the ramped surfaces includes linear sections.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The disclosure shall be explained in greater detail below based on exemplary embodiments in conjunction with associated drawings. Therein:

[0056] FIG. 1 shows, schematically, a sectional view of a clamping freewheel according to an embodiment, or a freewheel assembly according to an embodiment, respectively;

[0057] FIG. 2 shows, schematically, an enlarged sectional view of a clamping element of the clamping freewheel shown in FIG. 1, in a first state;

[0058] FIG. 3 shows, schematically, an enlarged sectional view of a clamping element of the clamping freewheel shown in FIG. 1, in a second state;

[0059] FIG. 4 shows, schematically, another enlarged sectional view of a clamping element of the clamping freewheel shown in FIG. 1, in a first state; and

[0060] FIG. 5 shows, schematically, an enlarged sectional view of the clamping freewheel shown in FIG. 1, without a clamping element.

DETAILED DESCRIPTION OF THE DRAWINGS

[0061] The same reference symbols are used for identical objects in the following description.

[0062] FIG. 1 shows a sectional view of a clamping freewheel 1 according to an embodiment, or a freewheel assembly 10 according to an embodiment.

[0063] The freewheel assembly 10 has a clamping freewheel 1 with a first ring element 2 that comprises numerous clamping ramps 3 and numerous clamping elements 4, wherein each clamping ramp 3 clamps a clamping element 4. The first ring element 2 is an outer ring therein.

[0064] The first ring element 2 is pressed into an outer ring element 22 for a form fitting and force fitting connection. In this manner, the first ring element 2 can be thin walled and used in various configurations inside an outer ring element 22.

[0065] The first ring element 2 is made of sheet metal in order to obtain the thin walled construction.

[0066] In the present case, the ring element 2 is thin walled such that the hollow cylindrical ring element 2 has a wall thickness H outside the clamping ramp 3, or at the thickest point of the first ring element 2 along the circumference U, that comprises a fraction of the thickness of a clamping element 4.

[0067] According to the exemplary embodiment in FIG. 1, the wall thickness H is less than 0.3 times the thickness of a clamping element 4.

[0068] Furthermore, the freewheel assembly 10 comprises a second ring element 11, which in the present exemplary embodiment is an inner ring.

[0069] The first ring element 2, or the outer ring, has one clamping element 4 for each clamping rampas indicated abovewherein the clamping element 4 bears on the respective clamping ramp 3, or the clamping element 4 is in contact with the clamping ramp 3, respectively.

[0070] Moreover, each of the clamping elements 4 shown therein bears on the associated clamping ramp 3 of the first ring element 2 and on a surface O of the second ring element 11. In this manner, a force can be transferred from the first ring element 2 to the second ring element 11 via the clamping element, or vice versa.

[0071] Each clamping ramp 3 has at least a first subsection 5 and a second subsection 6.

[0072] When the clamping freewheel 1 or the freewheel assembly 10 is in operation, the first ring element, rotating in the direction of rotation D, transfers a force to the second ring element 11 via the clamping elements 4.

[0073] The clamping elements 4 move along the tapered ramp geometry of the clamping ramps 3 when the first ring element 2 moves in the rotational direction D.

[0074] The clamping elements are clamped between the clamping ramp 3, or the first ring element 2, and the second ring element 11 inside the second clamping region 6 of the clamping ramp 3.

[0075] If, however, a large force or torque is applied to the clamping freewheel 1 in a short time interval, the clamping elements 4 move from the second subsection 6 of the clamping ramp 3 to the first subsection 5.

[0076] This second subsection prevents the overall clamping freewheel 1, or the overall clamping freewheel assembly 10, from becoming damaged. This is because if excessive forces are applied to a freewheel, the clamping elements 4 are pressed back quickly into the clamping profile, or against the clamping ramp 3, such that it becomes damaged, which in turn can lead to a total breakdown of the freewheel.

[0077] Consequently, the first subsection 5 in the exemplary embodiment in FIG. 1 forms an overload region, such that each clamping element 4 moves in relation to the respective clamping ramp 3, via which a transfer of force from the first ring element 2 to the second ring element 11 via the clamping element 4 can be prevented.

[0078] In other words, the first subsection 5 forms an overload region, such that a clamping element 4 slips on the respective clamping ramp 3.

[0079] Specifically, the first subsections 5 of each clamping ramp 3 and an associated clamping element 4 fulfill the slippage condition tan , via which a transfer of force from the first ring element 2 to the second ring element 11 via the clamping element 4 can be suppressed, or is prevented.

[0080] In contrast, the second subsection 6 is a force transfer region, designed such that a clamping element 4 clamps to the respective clamping ramp 3. The second subsection 6 of each clamping ramp 3 and an associated clamping element 4 fulfill the clamping condition tan < thereby, via which a transfer of force from the first ring element 2 to the second ring element 11 via the clamping element 4 can be ensured, or can take place.

[0081] Moreover, FIG. 1 shows that the first ring element 2 and the second ring element 11 are concentric to one another and to the center/rotational center M of the freewheel assembly 10.

[0082] The outer ring element in the present exemplary embodiment shown in FIG. 1 serves together with the first ring element 2 as a drive, and the second ring element 11 functions as a drive output.

[0083] As specified above, the drive direction, or the rotational direction D for transferring forces from the first ring element 2, or the outer ring element 22, to the second ring element 11, is indicated in FIG. 1.

[0084] The freewheel assembly 10 according to FIG. 1 can only transfer forces from the drive, or the first ring element 2, to the drive output, or the second ring element 11, when the first ring element 2 is rotating at a rate that is greater than or equal to the rotational rate of the second ring element 11. Both ring elements 2, 11 must be rotating in the same direction D for this.

[0085] In addition to the clamping elements 4, one spring element 20 for each clamping element 4 is shown between the first ring element 2 and the second ring element. The spring elements 20 are compression springs that press against the associated clamping element 4 counter to the direction of rotation D.

[0086] While a clamping element 4 bears on one end of a spring element 20, the spring element 20 bears on a web 21 at the other end. This web 21 is connected to the first ring element 2.

[0087] Each clamping ramp 3 is oriented spatially in the first ring element 2 such that it enlarges the spacing X between the clamping ramp 3 of the first ring element 2 and the surface O of the second ring element 11 along its course in the rotational direction D of the first ring element 2. The enlargement is continuous, at least in the second subsection 6 of the clamping ramp 3.

[0088] It should be noted with regard to FIG. 1 that in addition to the rotational direction D, the circumferential direction U is also indicated therein.

[0089] FIG. 2 shows an enlarged sectional view of a clamping element 4 of the clamping freewheel 1 according to the embodiment shown in FIG. 1 in a first state.

[0090] Therein, the ring element 2 is an outer ring in the clamping freewheel 1, or the clamping roller freewheel 1, that has various clamping ramps 3, each of which clamps the clamping elements 4.

[0091] The clamping freewheel 1 also comprisesas explained aboveone clamping element 4 for each clamping ramp 3, bearing on the respective clamping ramp 3.

[0092] Each clamping ramp 3 has at least one first subsection 5 and one second subsection 6, and extends in the circumferential direction U.

[0093] The first subsection 6 forms a force transferring region, such that a relative movement between the clamping element 4 and the ring element 2 can be prevented.

[0094] The first subsection 5 forms an overload region that allows for relative movement between the clamping element and ring element 2, by means of which a transfer of force from the first ring element 2 to the at least one clamping element 4 can be prevented.

[0095] When the ring element 2 is rotated for transferring force, or when the ring element 2 rotates in the rotational direction D, the first subsection 5 follows the second subsection 6. As a result, if there is an overload, the clamping element 4 moves from the second subsection 6 to the first subsection 5 in order to interrupt the transfer of force between the first subsection 5, each clamping ramp 3, and the respective associated clamping elements 4.

[0096] In the state shown in FIG. 2, the clamping elements 4 are located in the second subsection 6 of the clamping ramp 3.

[0097] In this state, the second subsection 6 prevents relative movement between each clamping element 4 and ring element 2.

[0098] This is obtained in that the tangent of the angle at the bearing point between the clamping element 4 and the clamping ramp 3, which is formed between a force F that is to be transferred and a perpendicular N2 to the second subsection 6 at the bearing point A, is less than the frictional coefficient for the material of the frictional pair formed by the ring element 2 and the clamping element 4.

[0099] The angle is between 3 and 4.5 in the second subsection 6. The perpendicular N2 is perpendicular to the plane of the second subsection 6 of the clamping ramp 3.

[0100] Simply put, this means that each clamping ramp 3 and each associated clamping element 4 are clamped, or clamped to one another, such that the clamping condition tan < is satisfied. As a result, forces can be transferred from the first ring element 2 to the second ring element 11 via the clamping element 4.

[0101] FIG. 3 shows that the clamping elements 4 are located, or placed, in the first subsection 5 of the clamping ramp.

[0102] In the state shown in FIG. 3, the first subsection 5 allows relative movement between the clamping elements 4 and the ring element 2.

[0103] This is obtained in that the tangent of the angle at the bearing point A between each clamping element 4 and each clamping ramp 3, which is formed between a force F that is to be transferred and a perpendicular N1 to the first subsection 5 at the bearing point A, is greater than or equal to the frictional coefficient for the materials of the frictional pair formed by the ring element 2 and the clamping element 4.

[0104] The angle is greater than 15 for the first subsection 5. The perpendicular N1 is perpendicular to the plane of the first subsection 5 of the clamping ramp 3.

[0105] Simply put, in reference to FIG. 3 this means that the first subsection 5 forms an overload region, such that each clamping ramp 3 and each associated clamping element 4 slip, or slip in relation to one another, or do not clamp, respectively. In this manner, the slippage condition tan is satisfied. As a result, transfer of forces from the first ring element 2 to the second ring element 11 via the clamping element 4 can be prevented.

[0106] It should also be noted that in a comparison of FIGS. 2 and 3, the spring elements 2 for each clamping element 4 push counter to the direction of rotation D. Each spring element 20 bears on a clamping element 4, or each clamping element 4, in FIG. 2, while in FIG. 3, the clamping elements 4 and spring elements 20 are not in contact with one another.

[0107] FIG. 4 is substantially identical to FIG. 2, but with additional reference symbols. FIG. 4 also shows the freewheel assembly 10, or clamping freewheel 1, at a standstill, or in a state in which no forces are transferred.

[0108] When stationary, the surface of the first subsection 5 forms an angle 1 with each clamping ramp 3 of the first ring element 2 with a tangent at the bearing point B between the clamping element 4 and the surface O of the second ring element. This angle 1 is greater than 30.

[0109] Furthermore, when the freewheel assembly 10 is at a standstill, the surface of the second subsection 6 in each clamping ramp 3 of the first ring element 2 forms an angle 2 with a tangent at the bearing point B between the clamping element 4 and the surface O of the second ring element 11. This angle is between 6 and 9.

[0110] FIG. 5 shows an enlarged sectional view of the clamping freewheel 1 according to the embodiment in FIG. 1, without the clamping elements 4.

[0111] Firstly, angles 1 and 2 are again indicated therein, as described above in reference to FIG. 4.

[0112] Moreover, it can be clearly seen in FIG. 5 that each clamping ramp 3 is oriented spatially in the first ring element 2 such that it enlarges the spacing X between each clamping ramp 3 of the first ring element 2 and the surface O of the second ring element along its course in the rotational direction D of the first ring element 2, in which a force can be transferred from the first ring element 2 to the second ring element 11.

[0113] Thus, spacing X2 is greater than spacing X1, as shown in FIG. 5.

[0114] These spacings X1 and X2 are distances that extend through the rotational center, or center M, of the ring element 2. In this manner, the spacings indicate the shortest distance between the first ring element 2 and the second ring element 11, or between the clamping ramp 3 and the surface O of the ring element 11.

[0115] In the present example according to FIG. 5, the spacing between the first ring element 2 and the surface O of the second ring element 11 increases in the rotational direction D and in the region of a clamping ramp 3 in a continuous manner.

LIST OF REFERENCE SYMBOLS

[0116] 1 clamping freewheel [0117] 2 first ring element [0118] 3 clamping ramp [0119] 4 clamping element [0120] 5 first subsection [0121] 6 second subsection [0122] 10 freewheel assembly [0123] 11 second ring element [0124] 20 spring element [0125] 21 web [0126] 22 outer ring element [0127] A rotational axis [0128] D rotational direction [0129] F force [0130] M center [0131] N1 perpendicular [0132] N2 perpendicular [0133] O surface [0134] U circumferential direction