Friction ring for a synchronization unit

Abstract

Friction ring for a synchronization unit of a gear changing transmission. The friction ring, when in an uninstalled state, is circumferentially pre-loaded and includes an annular front side, an annular rear side, a conical inner friction surface, a conical outer installation surface, and a first separation surface facing and in contact with a second separation surface and defining a circumferential separation area in the friction ring. The friction ring is prevented from contracting radially and circumferentially by said contact and is capable of expanding radially and circumferentially while being circumferentially pre-loaded.

Claims

1. A friction ring for a synchronization unit of a gear changing transmission, said friction ring, when in an uninstalled state, being circumferentially pre-loaded and comprising: an annular front side; an annular rear side; a conical inner friction surface; a conical outer installation surface; the conical inner friction surface being defined by a friction angle (1) relative to a friction ring axis; the outer installation surface being defined by a installation angle (2) relative to the friction ring axis; a first separation surface facing and in contact with a second separation surface and defining a circumferential separation area in the friction ring, wherein the friction ring is prevented from contracting radially and circumferentially by said contact and is capable of expanding radially and circumferentially while being circumferentially pre-loaded.

2. The friction ring of claim 1, wherein a gap is created between the first separation surface and the second separation surface when the friction ring expands radially and circumferentially.

3. The friction ring of claim 1, wherein said contact between the first separation surface and the second separation surface is maintained while in the uninstalled state.

4. The friction ring of claim 1, wherein the first separation surface and the second separation surface move away from each other when the friction ring expands radially and circumferentially.

5. The friction ring of claim 1, wherein the first separation surface and the second separation surface move away from each other when the friction ring is subject to elastic circumferential deformation.

6. The friction ring of claim 1, wherein the circumferential separation area extends at a separation angle ().

7. The friction ring of claim 1, wherein the circumferential separation area extends at an angle that is orthogonal to a circumferential direction.

8. The friction ring of claim 1, wherein the first separation surface comprises a first profile and the second separation surface comprises a second profile.

9. The friction ring of claim 8, wherein the first profile engages with the second profile.

10. The friction ring of claim 8, wherein the first profile is different from the second profile.

11. The friction ring of claim 8, wherein the first profile engages with the second profile so as to prevent axial displacement between the first and second separation surfaces.

12. The friction ring of claim 8, wherein the first profile locks with the second profile so as to prevent axial displacement between the first and second separation surfaces.

13. The friction ring of claim 8, wherein the first profile locks with the second profile so as to limit radial expansion of the friction ring to a maximum amount.

14. The friction ring of claim 8, wherein the first profile comprises one of: a projection; or a rectangular projection.

15. The friction ring of claim 8, wherein the second profile comprises one of: a recess; or a rectangular recess.

16. The friction ring of claim 8, wherein one of: the first profile comprises a dovetail projection and the second profile comprises a dovetail recess; the first profile comprises a V-shaped recess and the second profile comprises a V-shaped projection; or the first profile comprises a convex shaped projection and the second profile comprises a concave shaped recess.

17. The friction ring of claim 8, wherein the first profile comprises a C-shaped projection and the second profile comprises a C-shaped recess.

18. The friction ring of claim 1, wherein the friction ring is one of: a stamped steel part; or a shaped sheet-metal part.

19. A synchronization unit for a gear changing transmission of a vehicle comprising: a synchronizer ring; and a friction ring in accordance with claim 1.

20. A gear changing transmission of a vehicle comprising: a synchronizer unit in accordance with claim 19.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following the invention will be explained in more detail on the basis of the schematic drawings.

(2) FIG. 1a shows a first embodiment of a known segmented friction ring consisting of several segments in an expanded configuration,

(3) FIG. 1b shows the friction ring in accordance with FIG. 1a in a compressed configuration,

(4) FIG. 1c shows a second embodiment of a known segmented friction ring consisting of a single segment,

(5) FIG. 1d shows a section along the line I-I in accordance with FIG. 1a and FIG. 1c,

(6) FIG. 1e shows a section of the friction ring in accordance with FIG. 1a and FIG. 1c in a perspective view,

(7) FIG. 2 shows a synchronization unit known from the prior art,

(8) FIG. 3a shows a first embodiment of a friction ring according to the invention,

(9) FIG. 3b shows a section along the line I-I in accordance with FIG. 2 having a friction ring in accordance with FIG. 3a,

(10) FIG. 4a shows a detailed view X in accordance with FIG. 3a,

(11) FIG. 4b shows a detailed view X in accordance with FIG. 3a of a second embodiment of a friction ring according to the invention,

(12) FIG. 4c shows a detailed view X in accordance with FIG. 3a of a third embodiment of a friction ring according to the invention,

(13) FIG. 4d shows a detailed view X in accordance with FIG. 3a of a forth embodiment of a friction ring according to the invention,

(14) FIG. 4e shows a detailed view X in accordance with FIG. 3a of a fifth embodiment of a friction ring according to the invention, and

(15) FIG. 4f shows a detailed view X in accordance with FIG. 3a of a sixth embodiment of a friction ring according to the invention.

DETAILED DESCRIPTION OF THE INVENTION

(16) As already mentioned, FIG. 1a to FIG. 2 show the prior art and have already been explained in detail at the beginning so that any further discussion may not be considered necessary.

(17) FIG. 3a shows a first embodiment of a friction ring according to the invention which is designated in the following as a whole by the reference numeral 1. The reference numerals used in the FIG. 3a to FIG. 4f have no apostrophe because these figures refer to embodiments of the present invention. As already mentioned above, only the reference numerals used in the FIG. 1a to FIG. 2 have an apostrophe, because they refer to embodiments known from the prior art.

(18) The friction ring 1 comprises a conical friction ring body 4 having an inner friction surface 401 and an outer installation surface 402 which each bound the friction ring body 4 in a radial direction extending perpendicular to an axial friction ring axis 6. As in the case of the known friction ring shown in FIG. 1d the inner friction surface 401 extends at a predefinable friction angle .sub.1 and the outer installation surface extends at a predefinable installation angle .sub.2 conically along the friction ring axis 6, wherein the predefinable friction angle .sub.1 differs from the predefinable installation angle .sub.2. The friction ring body 4 is interrupted in a circumferential direction U extending around the friction ring axis 6 by a separation area 5 in such a way that a first separation surface 7 and a second separation surface 8 are formed at the separation area 5, wherein the separation area 5 extends orthogonally to the circumferential direction U. In contrast to the known friction ring which is shown in FIG. 1c, the first separation surface 7 and the second separation surface 8 touch each other in such a way that the friction ring body 4 is shaped in the form of a closed ring in the circumferential direction U with a smallest circumference 13 or a smallest diameter. As a result, the friction ring 1 can only deform elastically by the application of forces towards a bigger circumference or a bigger diameter so that the self-locking effect at the inner friction surface 401 of the friction ring 1 can be avoided.

(19) As can be seen from FIG. 3b, due to this form the friction ring 1 can be clearly positioned within the synchronization unit 3 relative to the synchronizer ring 2 in the axial direction. As the first separation surface 7 and the second separation surface 8 touch each other, the circumference of the friction ring 1 can no longer deform elastically towards a smaller circumference or a smaller diameter. For this reason the friction ring 1 takes a controlled axial position relative to the synchronizer ring 2 during the synchronization.

(20) It is also possible that the first separation surface 7 and the second separation surface 8 of the friction ring 1 shown in FIG. 3a touch each other, when a circumferential preload 14 is applied, that is, the friction ring body 4 is loaded or prestressed in the circumferential direction U, wherein the force applied on both separation surfaces 7, 8 is preferably between 2 and 20N. This ensures, even if unavoidable forces such as centrifugal forces are applied on the friction ring 1, that the first separation surface 7 and the second separation 8 touch each other reliably.

(21) FIG. 4a to FIG. 4f show in each case a detailed view X in accordance with FIG. 3a, wherein FIG. 4b to FIG. 4f show further embodiments of a friction ring 1 according to the invention.

(22) As to the embodiments of the friction ring 1 according to FIG. 4b to FIG. 4f, the first separation surface 7 is shaped in the form of a first profile 15 and the second separation surface is shaped in the form of a corresponding second profile 16, i.e. in contrast to the embodiment shown in FIG. 3a the separation area 5 is not formed as a straight line. The first profile 15 and the second profile 16 engage with one another in such a way that the first separation surface 7 and the second separation surface 8 cannot essentially be displaced against each other in the direction of the friction ring axis 6, i.e. in the axial direction.

(23) As to the embodiment from FIG. 4b, the first profile 15 is shaped as a rectangular projection and the second profile 16 is shaped as a rectangular recess. FIG. 4c shows an embodiment where the first profile 15 is shaped as a projection having the form of an arrowhead and the second profile 16 is shaped as a recess having the form of an arrowhead, whereas FIG. 4d shows an embodiment where the first profile 15 constitutes a convex projection and the second profile 16 constitutes a concave recess.

(24) FIG. 4e and FIG. 4f show embodiments where the first profile 15 and the corresponding second profile 16 are shaped in the form of a separating lock 17 in such a way that the circumference of the friction ring 1 in relation to the smallest circumference 13 is limited by the separating lock 17 to a predefinable maximum circumference. I.e. due to the separating lock 17 the friction ring 1 can deform elastically in the circumferential direction U only up to a certain circumference. FIG. 4e shows an embodiment where the first profile 15 is shaped as a projection having the form of a dovetail and the second profile 16 is shaped as a recess having the form of a dovetail. FIG. 4f shows an embodiment where the first profile 15 is executed as a circular projection and the second profile 16 as a circular recess.

(25) It can be clearly recognized from FIG. 4a to FIG. 4f that the first separation surface 7 and the second separation surface 8 touch each other in an area. In all embodiments the circumference of the friction ring 1 can thereby no longer deform elastically towards a smaller circumference or a smaller diameter so that the friction ring 1 takes a controlled axial position relative to the synchronizer ring 2 during the synchronization.