Freewheel and freewheel arrangement comprising such a freewheel

Abstract

The present invention relates to a freewheel comprising an outer ring, an inner ring, and at least one clamping element which is between the outer ring and the inner ring, which is moveable from a clamping position into a release position along a race on the outer ring in a first circumferential direction relative to the outer ring, wherein the race has a clamping section, and a release section following the clamping section in the first circumferential direction on which the clamping element is supportable. A first tangent through at least one support point on the clamping section defines a first inner angle, which is greater than 180, with a second tangent through at least one support point on the release section. In addition, the present invention relates to a freewheel arrangement for a motor vehicle comprising such a freewheel.

Claims

1. A freewheel comprising an outer ring, an inner ring having a circular counter-race, and at least one clamping element which is between the outer ring and the inner ring, which is moveable from a clamping position into a release position along a race on the outer ring in a first circumferential direction relative to the outer ring, wherein the race has a clamping section, and a release section following the clamping section in the first circumferential direction on which the clamping element is supportable, characterized in that a first tangent through at least one support point on the clamping section defines a first inner angle, which is greater than 180, with a second tangent through at least one support point on the release section; wherein: the inner ring comprises the circular counter-race; the clamping element engages the circular counter-race when the clamping element is positioned within the clamping section; and the release section has a radius greater than a radius of the at least one clamping element.

2. The freewheel as recited in claim 1, wherein the race has a transition section at the transition between the clamping section and the release section, wherein the transition section has a continuous or discontinuous course.

3. The freewheel according to claim 2, wherein the transition section has a course curved outward in a circular are in the radial direction with respect to the first circumferential direction.

4. The freewheel according to claim 1, wherein the clamping section is designed at least partially straight and/or has a course curved inward in an arch in the radial direction with respect to the first circumferential direction.

5. The freewheel according to claim 1, wherein the release section is designed at least partially straight and/or has a course curved inward in a spiral in the radial direction with respect to the first circumferential direction.

6. The freewheel according to claim 1, wherein the first inner angle is greater than 185.

7. The freewheel according to claim 1, wherein the second tangent defines a release angle on a circumference with a tangent through an intersection, at which a radial extending to a center of the clamping element crosses the circumference, said release angle being greater than twice the clamping angle of the freewheel when the clamping element is supported on the support point, through which the second tangent-extends.

8. The freewheel according to claim 1, wherein the race additionally has a retaining section following the release section in the first circumferential direction, on which retaining section the clamping element is supportable, wherein a third tangent defines a second or a third inner angle, which is 180 or less, with the second tangent or with the first tangent.

9. The freewheel according to claim 1, wherein the clamping element is designed as a clamping roller, wherein the ratio between a width and an outer diameter of the clamping roller is equal to 1:5, and the clamping roller is pretensioned in the clamping position by means of a spring element which is supportable on the outer ring.

10. A freewheel arrangement for a motor vehicle comprising a freewheel according to claim 1, wherein an output side of a starter motor is in permanent rotary driving connection with the inner ring, whereas an output side of an internal combustion engine of the motor vehicle is in or can be brought into rotary driving connection with the outer ring.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The invention will be subsequently described in greater detail by means of exemplary embodiments with reference to the attached figures.

(2) FIG. 1 shows a partial side view of a freewheel arrangement inside of a motor vehicle in a cutaway view;

(3) FIG. 2 shows a view along line A-A in FIG. 1 with the freewheel in a first embodiment and the clamping element in the clamping position;

(4) FIG. 3 shows the freewheel from FIG. 2 with the clamping element in a first release position;

(5) FIG. 4 shows the freewheel from FIG. 3 with the clamping element in a second release position;

(6) FIG. 5 shows the freewheel from FIG. 4 with the clamping element in a third release position;

(7) FIG. 6 shows a view along line A-A of FIG. 1 in a second embodiment variant of the freewheel;

(8) FIG. 7 shows a view along line A-A of FIG. 1 in a third embodiment of the freewheel; and

(9) FIG. 8 shows a view along line A-A of FIG. 1 in a fourth embodiment of the freewheel.

DETAILED DESCRIPTION OF THE DISCLOSURE

(10) FIG. 1 shows a freewheel arrangement 2 inside of a motor vehicle. Freewheel arrangement 2 essentially has a freewheel 4, a starter 6, and an internal combustion engine 8. Starter 6 has a starter motor 10 with an output side 12 which is essentially formed by a starter pinion 14 drivable by starter motor 10. Of internal combustion engine 8, an output side 16 is represented in the form of a driveshaft or crankshaft 18 which is connected rotationally fixed to a flywheel 20 in the embodiment shown. In FIG. 1, the opposing axial directions 22, 24, the opposing radial directions 26, 28, and the opposing circumferential directions 30, 32 of freewheel arrangement 2 and of freewheel 4 are indicated by means of corresponding arrows, wherein circumferential direction 30 is subsequently designated as first circumferential direction 30 and circumferential direction 32 is subsequently designated as second circumferential direction 32. The axis of rotation 34 of output side 16 and of freewheel 4 extends in axial directions 22, 24. First and second circumferential directions 30, 32 may also be designated as first and second directions of rotation.

(11) Output side 12 in the form of starter pinion 14 is arranged in radial direction 26 outside of freewheel 4 such that an output side 12 of starter 6 lying radially exterior may be stated with respect to freewheel 4. Output side 12 of starter motor 10 is permanently in rotary driving connection with a starter gear 36, wherein starter gear 36 has a rotary driving contour 38 for this purpose which is permanently in rotary driving connection with starter pinion 14. Starter gear 36 is connected rotationally fixed to an inner ring 42 of freewheel 4 via a starter wheel 40 which extends, starting from starter gear 36, inward in radial direction 28. An outer ring 44 of freewheel 4 surrounding inner ring 42 of freewheel 4 outwardly in radial direction 26 is, in contrast, connected rotationally fixed to output side 16 of internal combustion engine 8, wherein outer ring 44 in the embodiment shown is connected rotationally fixed to driveshaft 18 forming output side 16 of internal combustion engine 8 via flywheel 20.

(12) Inner ring 42 is supported directly or indirectly in radial directions 26, 28 on output side 16, in this case, on driveshaft 18, to be rotatable in circumferential direction 30, 32. Alternatively, inner ring 42 may also be supported directly or indirectly in radial directions 26, 28 to be rotatable on a stationary housing, for example, on the housing 46 of internal combustion engine 8 indicated in FIG. 1. In order to affect the rotatable support, this is carried out preferably via a radial bearing, particularly preferably via a rolling bearing or plain bearing 48, as this is indicated in FIG. 1. In the embodiment shown, freewheel 4 is designed as a dry-running freewheel. Alternatively, however, freewheel 4 may also be designed as a wet-running freewheel, the supply of coolant and/or lubricant in this case is preferably carried out via the coolant and/or lubricant supply of the internal combustion engine 8.

(13) Inner ring 42 and outer ring 44 are arranged nested in radial directions 26, 28 such that a circumferential clamping gap 50 is formed between the same in circumferential directions 30, 32. Multiple clamping elements 52 are arranged within clamping gap 50 spaced uniformly apart from one another in circumferential directions 30, 32, wherein clamping elements 52 are designed as clamping rollers in the embodiment shown which therefore have a circular circumference or a circular outer contour 54. Outer ring 44 has a race 56 facing inward in radial direction 28 toward clamping elements 52, wherein a race 56 of this type, which has a course deviating from a pure circular arc, is respectively assigned to each of clamping elements 52. Inner ring 42 has, in contrast, a counter-race 58 facing toward clamping elements 52 and outward in radial direction 26. Counter-race 58 designed circumferentially in circumferential directions 30, 32 is designed with a circular shape. Due to race 56 deviating from a circular path on the one side and the circular shape of counter-race 58 on the other side, a clamping gap 50 is created which tapers in second circumferential direction 32 in the region of respective clamping element 52, which will be introduced again in more detail with reference to FIGS. 2 to 8.

(14) Clamping elements 52 designed as clamping rollers have a width b and an outer diameter a with respect to axial directions 22, 24. The ratio between width b and outer diameter a of the respective clamping elements 52 designed as clamping rollers is equal to or less than 1:3, preferably equal to or less than 1:4, particularly preferably equal to or less than 1:5. In other words, coin shaped clamping elements 52 or clamping rollers may also be discussed which enable a particularly short axial structure of freewheel 4. Clamping gap 50 is delimited in axial direction 22 by a first side wall 60 and in axial direction 24 by a second side wall 62, wherein first side wall 60 is formed in the embodiment shown by a section of flywheel 20, whereas second side wall 62 is formed separately from flywheel 20 and as an annular disk. First side wall 60 and second side wall 62 are fixed rotationally fixed to outer ring 44 of freewheel 4, which may be carried out, by way of example, by means of the screw connection (no reference numeral) shown in FIG. 1.

(15) The further structure of freewheel arrangement 2 and freewheel 4 in FIG. 1 will be subsequently described with reference to FIGS. 1 to 5, wherein FIGS. 2 to 5 show a first embodiment of freewheel 4.

(16) Each clamping element 52 may be moved along race 56 on outer ring 44 in first circumferential direction 30 relative to outer ring 44 from a clamping position, which is shown in FIG. 2, into a release position, which is shown in FIGS. 3 to 5. Clamping element 52 is thereby moved from the clamping position into the release position counter to the reset force of a spring element 64, which is supported or is supportable on the one side in first circumferential direction 30 on outer ring 44 and on the other side in second circumferential direction 32 on clamping element 52. In other words, clamping element 52 designed as a clamping roller is pretensioned by spring element 64 in the clamping position shown in FIG. 2.

(17) In the clamping position shown in FIG. 2, outer contour 54 of clamping element 52 is supported both on race 56 and on counter-race 58, wherein a rotation of outer ring 44 in first circumferential direction 30 relative to inner ring 42 is prevented. In the clamping position, outer ring 44 and thus also output side 16 of internal combustion engine 8 in the form of driveshaft 18 may be driven with the aid of flywheel 20 by starter 6, which rotates inner ring 42 of freewheel 4 in second circumferential direction 32 by means of starter gear 36 and starter wheel 40. If internal combustion engine 8 starts as a result of this starting process, such that outer ring 44 driven by output side 16 of internal combustion engine 8 overtakes inner ring 42 of freewheel 4 in second circumferential direction 32, then clamping element 52 moves along race 56 as a result of centrifugal and inertial forces into the release position shown in FIGS. 3 to 5. Therefore, freewheel 4 in the basic structure is a so-called one-way coupling.

(18) Race 56 on outer ring 44 has essentially a clamping section 66, a transition section 68 following clamping section 66 in first circumferential direction 30, a release section 70 following transition section 68 in first circumferential direction 30, and a retaining section 72 following release section 70 in first circumferential direction, wherein transition section 68 is provided at the transition between clamping section 66 and release section 70. Transition section 68 may thereby be assigned partially or completely to clamping section 66 and/or partially or completely to release section 70. Clamping element 52 is supportable via its outer contour 54 at support points on clamping section 66, transition section 68, release section 70, and retaining section 72 respectively. Support points are thereby preferably understood as those points on the respective section, at which the clamping element is actually supportable for structural reasons.

(19) In the first embodiment according to FIGS. 2 to 5, clamping section 66 is designed to be at least partially or completely straight. Alternatively or supplementally, however, clamping section 66 may also have a curved course, as is indicated in FIG. 7. Thus, clamping section 66 in the embodiment according to FIG. 7 has a course curved inward in radial direction 28 in an arch, in a circular arc, or in a spiral with respect to first circumferential direction 30. It may also be stated here that clamping section is designed, according to the embodiment according to FIG. 7, curved outward in radial direction 26, preferably in an arch, in a circular arc, or in a spiral.

(20) Transition section 68 may basically have a continuous course, as this is shown in the embodiments according to FIGS. 2 to 5, 7 and 8, or a discontinuous course, as this is indicated in FIG. 6 in the context of a second embodiment of freewheel 4. In this second embodiment, transition section 68 analogously has a bent course. Regardless of whether transition section 68 has a continuous or discontinuous course, transition sections 68 in all of the embodiments shown according to FIGS. 2 to 8 have a course curved outward in radial direction 26 relative to first circumferential direction 30, wherein it may also be stated that transition section 68continuous or discontinuousis curved inward in radial direction 28. It is hereby preferred if transition section 68, as is shown in FIGS. 2 to 5 and 7 to 8, has a course curved outward in radial direction 26 in an arch, in a circular arc, or in a spiral, wherein it may also be stated that transition section 68 is curved inward in radial direction 28 in an arch, in a circular arc, or in a spiral in these embodiments.

(21) Release section 70 may be designed to be at least partially or completely straight. Alternatively or supplementally, however, release section 70 may also have a course curved inward in radial direction 28, preferably in an arch, in a circular arc, or in a spiral with respect to first circumferential direction 30. In other words, release section 70 may be designed curved outward in radial direction 26, preferably in an arch, in a circular arc, or in a spiral. In the embodiments shown, release section 70 has a first subsection 74 and a second subsection 76 following first subsection 74 in first circumferential direction 30, wherein first subsection 74 is designed to be straight, whereas second subsection 76 has a course curved inward in radial direction 28, preferably in an arch, in a circular arc, or in a spiral with respect to first circumferential direction 30.

(22) Retaining section 72 following release section 70 has, in turn a course curved inward in radial direction 28, preferably in an arch, in a circular arc, or in a spiral with respect to first circumferential direction 30, wherein it may be stated in turn that retaining section 72 has a course a course curved outward in radial direction 26, preferably in an arch, in a circular arc, or in a spiral. In the embodiments shown according to FIGS. 2 to 8, both second subsection 76 of release section 70 and retaining section 72 are curved in a circular arc, wherein this has a circular arc radius r.sub.1 or r.sub.2. Circular arc radius r.sub.1 preferably corresponds to circular arc radius r.sub.2. Alternatively, however, circular arc radius r.sub.2 may be designed to be greater than circular arc radius r.sub.1. It is also preferred if circular arc radius r.sub.2 of the circular arc formed by retaining section 72, regardless of whether this corresponds to circular arc radius r.sub.1 of second subsection 76 or whether second subsection 76 is even designed as a circular arc, is greater than the radius of clamping element 52 designed as a clamping roller, such that preferably a/2<r.sub.2 applies. It should also be noted at this point that release section 70 may be formed completely from straight first subsection 74 or from curved second subsection 76, even though the division into first and second subsections 74, 76 shown in FIGS. 2 to 8 is preferred.

(23) In order to effectively suppress noise development during the starting process and/or in the range or the idle speed, a first tangent 78 through at least one support point 80 on clamping section 66 of race 56 defines a first inner angle 1, which is greater than 180, with a second tangent 82 through at least one support point 84 on release section 70. It has hereby proven advantageous, if the cited first inner angle 1 is greater than 185, particularly preferably 190 or more. It is also preferred if the cited first inner angle 1 exists proportionally between all possible support points of clamping element 52 on clamping section 66 and all possible support points on release section 70.

(24) In addition, retaining section 72 is designed in such a way that a third tangent 86 through at least one support point 88 on retaining section 72 defines a second inner angle 2 and/or a third inner angle 3, which is 180 or less, with second tangent 82 and/or with first tangent 78.

(25) On the basis of the preceding description, it is apparent that race 56 has a course, on the basis of correspondingly formed first inner angle 1, which deviates from the conventional course 90, indicated in the figures with dashed lines, in order to effectively suppress noise development during the starting process and/or in the range of idle speed, wherein, in contrast to conventional course 90, a depression 92 is analogously created in the region of release section 70 and retaining section 72. The functionality of freewheel arrangement 2 and freewheel 4 shall be subsequently introduced in greater detail with reference to FIGS. 2 to 5.

(26) In FIG. 2, clamping element 52 is in the clamping position thereof. In the clamping position of clamping element 52, outer contour 52 [sic: should read 54] thereof is supported both in radial direction 26 outward on clamping section 66 and in radial direction 28 inward on counter-race 58, wherein clamping element is retained in the clamping position via spring element 64. For structural reasons, freewheel 4 has a predetermined clamping angle , which is indicated twice in FIG. 2. During the starting process, inner ring 42 is initially driven in second circumferential direction 32 via starter 6, wherein, due to the clamping position of clamping element 52, a rotary driving connection exists between inner ring 42 and outer ring 44 by means of clamping element 52. Therefore, outer ring 44 and, via outer ring 44, flywheel 20 and output side 16 of internal combustion engine 8, and internal combustion engine 8 or driveshaft 18 thereof, are also driven.

(27) In the combustion cycles of internal combustion engine 8, outer ring 44 is additionally drivensomewhat intermittentlyin second circumferential direction 32, such that clamping element 52 moves along race 56, more exactly stated, along clamping section 66, transition section 68 (FIG. 3), release section 70 (FIG. 4), and retaining section 72 (FIG. 5), wherein this occurs as a result of centrifugal and inertial forces counter to the reset force of spring element 64.

(28) In the compression cycles of internal combustion engine 8, however, the speed of outer ring 44 rotating in second circumferential direction 32 is reduced such that clamping element 52 is moved back in second circumferential direction 32 relative to outer ring 44 due to the reset force of spring element 64 and due to the decrease in the centrifugal force affecting clamping element 52. However, in the course of this movement of clamping element 52 in second circumferential direction 32 relative to outer ring 44, clamping element 52 supports itself on release section 70 of race 56, as this is shown in FIG. 4, wherein the previously mentioned first inner angle 1, which is designed to be greater than 180, prevents a further movement of clamping element 52 in second circumferential direction 32 relative to outer ring 44, such that it may be avoided that clamping element 52 is moved further along race 56 in second circumferential direction 32 relative to outer ring 44 and ultimately strikes counter-race 58 of inner ring 42 inward in radial direction 28. Thus, both noise development and also oscillation development may be prevented by this means.

(29) In this context, it has proven particularly advantageous if previously mentioned second tangent 82 (see also FIG. 4) through support point 84 defines a release angle on a circumference with a tangent 94 through an intersection point 96, at which a radial 100 extending to a center point 98 of clamping element 98 intersects the circumferencehere the circular counter-race 58, which angle is greater than twice clamping angle of freewheel 4 when clamping element 52 is supported on support point 84, through which second tangent 82 extends. It has additionally proven hereby advantageous, if release angle is at least 1.1 times or 1.5 times clamping angle , particularly preferably at least 2 times or 2.5 times clamping angle . As an upper limit for release angle , however, it has proven advantageous if release angle is not more than 3 times clamping angle .

(30) The preceding description of the first embodiment according to FIGS. 1 to 5 applies analogously to the additional embodiments according to FIGS. 6, 7, and 8, such that reference is made with respect to the preceding description. Whereas reference has already been made to the second embodiment according to FIG. 6 and to the third embodiment according to FIG. 7, fourth embodiment according to FIG. 8 shall subsequently be supplementally introduced. In contrast to the preceding embodiments, retaining section 72 in the fourth embodiment according to FIG. 8 is designed to be essentially straight. Thus, retaining section 72 has two straight subsections, connected to each other, however, at a bend. In general, the preceding description of embodiments 1 to 3 applies accordingly.