[0001]ARRANGEMENT OF A SHIFT ROCKER IN A TRANSMISSION
[0002]
[0003]
[0004] The invention concerns an arrangement of a shift rocker in a transmission
housing, according to the preamble of Claim 1.
[0005]
[0006] Shift rockers are known shift elements for carrying out gearshifts in a manual
transmission. The shift rocket is curved or fork-shaped and is mounted to pivot relative to the transmission housing. It engages with sliding blocks in an annular groove of a shifting or sliding sleeve, which shifts the desired gear. The shift rocker is actuated by a shift rail or shift rod arranged to move longitudinally in the transmission housing and connected to the shift rocker by a coupling joint. This causes the shift rocker to pivot in one direction or the other.
[0007] From DE 43 42 957 A1 oy the present applicant a shifting mechanism with
a shift rocker of this type has tiecoune known. The pivoting mounting of the shift rocker is effected by means cf two pins fixed on the housing, which engage In corresponding blind-hole bores in the shift rocker and thus on the one hand enable a pivoting movement about a pivot axis defined by the pins, and on the other hand allow some axial play so that the sliding blocks can slide within the annular groove of the sliding sleeve without cfitching. In this known shifting mechanism the shift rocker's pivot axis defined by the pins is arranged horizontally.
[0008] Problems can arise if the pivot axis is arranged not horizontally but vertically
- because in relation to the engagement of the sliding blocks in the annular groove of the sliding sleeve various situations can exist. The shift rocker then rests with its full weight, via the upper sliding block, on the bottom of the annular grove in the sliding sleeve, whereas there is some play between the lower sliding block and the annular groove. This has the disadvantage that the upper sliding block is continually subjected to wear and the lower sliding block slips out of the annular groove
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(downward), so that the overlap is no longer optimal. In the prior art the engagement of the shift rocker in the shift rod is so designed that a corresponding projection or finger of the shift: rocker engages, from below, in a groove of the shift rod, so that no gravitational force is transmitted from the shift rocker to the shift rod. Accordingly, as the upper sliding block becomes progressively more worn the play in the vertical direction between the shift rocker and the shift rod also increases, which reduces the overlap and results in increased loading of the shift rod and the shift rocker.
[0009]
[0010] The purpose of the present invention is to design an arrangement of a shift
rocker of the type described a the start, in such manner that wear of the sliding blocks is reduced and engagement of the sliding blocks in the sliding sleeve and the engagement of the shift rocker in the shift rod are improved.
[0011] The invention's objectives are achieved by the characteristics specified in
Claim 1. According to the invention it is provided that the shift rocker rests Its weight on the shift rod and no longer- as in the prior art- on the sliding sleeve. By virtue of its pivot bearing on pivot pms the shift rocker can move freely in the vertical direction, so that the weight of 'he shift rocker can be supported on the shift rod by a supporting element arranged on the shift rocker. This has the advantage that the upper sliding block is relieved from the weight of the shift rocker, so that the friction force between the upper slidir;g block and the base of the groove in the sliding sleeve is reduced. This improves the efficiency of the transmission. The upper sliding block rests on the groove bottom of the sliding sleeve only under its own weight. Moreover, another advantage is that the supporting element rests at all times against the shift rod on a corresponding contact surface, so that optimum engagement is achieved during transfer of the shifting movement from the shift rod to the shift rocker. In addition, the overlap between the lower sliding block and the annular groove of the sliding sleeve is improved.
[0012] In a preferred design, th« shift rod has a groove opening downward, in which
a coupling element of the shift rocker engages, The supporting element also arranged on the shift rocker rests on a contact surface against the upper

circumference of the shift rod, and so supports the shift rocker on the shift rod. This division of functions has the advantage that the shifting force transmission takes place with less friction.
[0013]
[0014] An example embodiment of the invention is illustrated in the drawings and will
be described in more detail below. The drawings show:
[0015] Fig. 1: Perspective representation of a shift rocker according to the invention,
with its sliding sleeve and shift rod;
[0016] Fig. 2: View of the shift rocker with its sliding sleeve and shift rod in the axial
direction; and
[0017] Fig. 3: Another example embodiment of the invention, with a shift rocker and
shift rod,
[0018]
[0019] Fig, 1 shows a perspective representation of a shift rocker 1, a sliding sleeve
2 and a shift rod 3, arranged in a housing of a manual transmission (not shown). The shifting means 1, 2, 3 shown serve to carry out gearshifts, during which the sliding sleeve is pushed axially over a shaft (not shown) to engage in an adjacent geanwheel (not shown). The shift rocker 1 is mounted to pivot on two pins 4,5 fixed on the housing, the pivot axis defined by the longitudinal axes of the said pins being orientated vertically. The shift -ocker 1 engages with two sliding blocks, an upper sliding block 6 and a lower sliding block 7, in an annular groove (not indexed) of the sliding sleeve 2. The shift rod 3 is mounted fixed on the housing - this is not shown - and in the area of the shift 'ocker 1 has a groove 8 open upward, in which a supporting element 9 arrangec on the shift rocker 1 engages. Together with the shift rod 3 the supporting eleme nt 9 forms a coupling joint so that when the shift rod
3 moves axially, the shift rocker 1 undergoes a rotation or pivoting movement about the pins 4, 5. On the other hend, the shift rocker 1 rests with its weight, via the supporting element 9, on the ^^hift rod 3 - with the supporting element 9 resting against the bottom 8a of the grooveiS.

[0020] Fig. 2 shows the arrangement in Fig. 1 viewed in the axial direction, showing
the sliding sleeve 2, the shift rocker 1 and the shift rod 3, which is also called the shift rail. In this representation thei pivot axis defined by the upper pin 4 and the lower pin 5 is arranged vertically and indexed a. The shift rocker 1 can move upward and downward in the cirection of the pivot axis a, i.e. the pins 4, 5, which engage in blind-hole bores of the shift rocker 1 in a manner not shown, are formed as axial loose bearings. The siding blocks 6, 7 are guided in the shift rocker 1 by sliding pins (not shown) and ca i move in the pin direction, i.e. in the direction of the vertical diameter m. In the area of the groove 8 the shift rod 3 forms the upward-facing contact surface 8a, against which the supporting element 9 of the shift rocker 1 rests. Thus - disregarding triction forces at the bearing points of the pins and sliding blocks - the weight of tihe shift rocker 1 is supported completely on the shift rod 3. Consequently, the shif: rocker 1 no longer presses, via the upper sliding block 6 against the sliding slee /e 2, but rather, the upper sliding block 6 rests only under its own weight against the groove bottom 2a of the annular groove 2b. Between the upper side of the upper sliding block 6 and the lower side of the shift rocker there is some play s^. Analogously, between the upper side of the lower sliding block 7 and the groove bottom 2a there is some play Sa. By virtue of the support, according to the invention, of the shift rocker 1 on the shift rod 3 there is a constant overlap of the sliding blocks 6, 7 relative to the annular groove 2b and, on the other hand, constant contact between the supporting element 9 and the contact surface Ba, so that there too there is an optimum overlap.
[0021] Fig. 3 shows a further example embodiment of the invention, the same
components as in Figs. 1 and 2 being indexed in Fig. 3 with a number increased by 10. Thus, Fig. 3 shows a shift rocker 11 mounted to pivot about a vertically orientated pivot axis a on pin;; 14, 15 fixed to the housing. Analogously to the previous example embodiment, an upper sliding block 16 and a lower sliding block 17 are fitted in the shift rocker 1. A shift rod 13 is shown in cross-section and has a groove 18 open downward with a downward-facing groove bottom 18a. In contrast to the example embodiment of Figs, 1 and 2, where the groove 8 is open upward, the groove 18 is oper downward. A supporting element 19 formed as a projection extending from the Jhift rocker 11 rests on the upper edge 13a (contact

surface) of the shift rod 13 and io supports the shift rocker 11 with its weight on the shift rod 13. The shift rocker 11 also has a coupling element 20 formed as a finger, which engages in the groove 13 of the shift rod 13. The coupling element 20 can for example also be made intec rally with the shift rocker 11. The coupling element 20 does not transmit any gravitational forces to the shift rod 13, so there are no weight-related friction forces as there are in the previous example embodiment. The supporting element 19 and the coupling element 20 are approximately U-shaped and surround the shift rod 13 i i th© area of the groove 18. Thus, in this example embodiment there is a division of functions in the sense that the weight of the shift rocker 11 is transferred via the projecting supporting element 19 onto the shift rod 13 and the shifting movement of the shift rod 13 is transmitted by the coupling element 20 to the shift rocker" 1. As a result, minimal friction losses occur during a shift process so that the shifting comfort is increased.
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Indexes

1. Shift rocker
2. Sliding sleeve
3. Slnift rod
4. Pin
5. Pin
6. Sliding block
7. Sliding block
8. Groove
8a. Groove bottom
9. Supporting element
11. Shift rocker
12, Sliding sleeve
13. Shift rod
13a. Contact surface
14. Pin
15. Pin
16. Sliding block
17. Sliding block
18. Groove
18a. Groove bottom
19. Supporting element
20. Coupling element

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Claims
1. Arrangement of a shift roclcer (1, 11) in a transmission housing, which comprises a sliding sleeve (2)end a shift rod (3,13), such that the shift rocker (1, 11) is mounted to pivot relative to the housing about a pivot axis (a), can be actuated by means of the shifi: od (3,13), and engages via sliding blocks (6, 7; 16, 17) In an annular groove (26) of the sliding sleeve (2), characterized in that the pivot axis (a) is orientated substantially vertically and the shift rocker (1,11) has at least one supporting element (f), 19) arranged outside the said vertically orientated pivot axis (a), which rests on ttie shift rod (3).
2. Arrangement according to Claim 1, characterized in that the shift rocker (1,11) is mounted radially relative to the pivot axis (a) by means of pins (4, 5; 14, 15) fixed on the housing.
3. Arrangement according toiClaims 1 or 2, characterized In that the sliding blocks (6, 7; 16,17) are held end able to slide in the shift rocker (1,11).
4. ArrangementaccordingtOiClaims 1,2or3, characterized in that the shift rod (3) has a groove (8) open uoward, with a groove bottom (8a), and the supporting element (9) engages in the grcove (8) and rests on the groove bottom (8a).
5. Arrangement according to any of Claims 1 to 4, characterized in that the supporting element Is formed &s a projection (9) extending from the shift rocker (1).
6. Arrangement accordi ng to Claims 1,2 or 3, characterized in that the shift rod (13) has a groove (18) open downward, and the supporting element (19) rests on the upper side (13a) of the shift rod (13).

7. Arrangement accordiig toiClaim 6, characterized In that the shift rocker
(11) has a coupling element (20), winich engages in the downward-opening groove
(18).
8. Arrangement according to Claims 6 and 7, characterized in that the
supporting element (19) and the coupling element (20) enclose the shift rod (13) in
a U shape.
9. Arrangement according to any of the preceding Claims, characterized in
that the sliding blocks (6,7; 16 17) can move freely in the vertical direction (m), the
upper sliding block (6;16) has c^n upper clearance {s^) relative to the shift rocker (1,
11) and the lower sliding bloc'< (7, 17) has a lower clearance (Sj) relative to the
groove bottom (2a).

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