WO2012152469A1

WO2012152469A1 - Shift fork

Info

Publication number: WO2012152469A1
Application number: PCT/EP2012/054220
Authority: WO
Inventors: Uwe Schwarz; Jochen LÖFFELMANN
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2011-05-09
Filing date: 2012-03-12
Publication date: 2012-11-15
Also published as: DE102011075491A1

Abstract

What is proposed is a shift fork (3) which comprises a fork-shaped basic body (4) having mutually opposite fork legs (6, 7) which form a shift mouth (25) for guiding a shift sleeve, and a one-part, separately produced sliding element (5) for contact with the shift sleeve. In a first embodiment of the invention, the sliding element (5) at least partially engages around the fork legs (6, 7) and is snap-fastened thereon by means of a snap element (30). In a second embodiment, the sliding element (5) has two walls (42, 43) which are directed axially parallel and are connected to one another on the sliding sleeve side.

Description

Name of the invention

Shift fork description

Field of the invention

The invention relates to a shift fork which has a fork-shaped basic body with opposite fork legs, which form a shift jaw for guiding a shift sleeve, and a one-piece, separately manufactured sliding element for the contact with the shift sleeve.

Background of the invention

Shifter forks are known from the prior art, which have a switching jaw for external engagement in a shift sleeve between two fork legs. The shift sleeve is non-rotatably connected to a synchronizer body arranged on a transmission shaft so that it rotates relative to the gearshift housing stationary shift fork. To avoid overloading the shift fork during the switching process, the shift forks are usually end provided on their fork legs with separately manufactured sliding shoes. The sliding shoes can be molded or attached. For this they must be directed and permanently connected to the shift fork - often by complex welding.

To solve this problem, DE 71 05 1 1 1 U1 discloses a shift fork with a U-shaped plastic profile, which is defined by beads on the metallic body of the shift fork. The plastic profile in the form of a one-piece half-ring reduces installation costs compared to two separate sliding shoes. A further type of attachment of such a sliding shoe ring is shown in EP 1 686 294 B1, according to which the sliding shoe ring pushes against the inside of the shift fork due to its bending stiffness. To detach the sliding To prevent schuhrings is alternatively provided in US 4,630,719 B1 screw by bolt.

The aforementioned Gleitschuhringe require special material properties as sliding elements in order to secure them at the same time safe. In operation, some areas are heavily loaded, so that the Gleitschuhring can deform and is no longer safe.

Summary of the invention

The invention has for its object to provide a shift fork, which is particularly easy to manufacture and the sliding layer is securely held on the body. This object is achieved by a shift fork according to claim 1. For this purpose, the slider engages around the fork legs radially at least partially and is snapped at this by means of a snap element. The sliding element preferably fits against the sliding sleeve-side inner contour of the base body and is thus designed as a sliding shoe ring. In order to ensure effective support, the sliding element can also partially grip the basic body radially on the outside. The snap element is initially biased in the connection of the sliding element with the base body and locked in the course of the connection, so that it is held captive on the base body. Under load, the sliding member is supported on the base body, whereby a part of the snap element may be charged. Due to the fact that the sliding element partially surrounds the fork legs, deformation of the sliding element under load is reduced, so that it can not detach from the base body even under unfavorable operating conditions, but is always reliably supported on it.

In principle, a snap element to secure the components sliding element and body is sufficient. Preferably, however, several, in particular two snap elements are provided. The snap elements can be be arranged body and / or on the sliding element. For a particularly secure connection, it is advisable to arrange the snap elements towards the open ends of the sliding element or the base body. The snap element can snap in the axial direction, but preferably snaps it radially. After snapping the sliding element and the base body to each other can already be positioned as desired. Alternatively, the components are mutually still limited movement, then preferably stops or means are provided which position the components to each other definitively, for example, form-fitting.

In a variant of the invention, the snap element is designed as a snap hook. The snap hook has two legs connected via a connection base, which preferably form a U-shape or a V-shape. The snap hook can be arranged both on the main body and on the sliding element. If the snap hook is arranged on the sliding element, the connecting base points towards the base body when the sliding element is pushed onto the base body, so that the legs are first compressed and then spring open again. For this purpose, both legs are directed substantially parallel to the fork end of the body. Preferably, only one of the legs is connected to the sliding element, and the other leg snaps or locks on the base body.

The snap hook snaps preferably radially on the outside of the main body. If the snap hook remains slightly biased even after snapping, the sliding element is not only held captive, but is also safe on the body, without larger parts of the surface of the sliding element would have to be frictionally connected to the body.

The stability of the main body-sliding element composite is further increased if the sliding element has a closed end cross-section at the fork end. For this purpose it completely surrounds the main body so that it has gear recess or a blind hole for the fork end. Under load then bending of the sliding element is difficult - especially in the event that the sliding element consists of a plastic. In one embodiment of this variant, the sliding element at the fork end, but also in the middle region of the base body can be positively connected to the base body.

In a next embodiment of the invention, the sliding element is split endwise into two prongs. The thickness of the tines is not necessarily the same size. For example, it is provided that the first prong, the main prong, has the same thickness as the rest of the sliding element. The other tines are designed as snap tines preferably parallel to the main tines and forms the snap element. During assembly, the tines are first spread apart from each other by a projection on the base body, and in the course of the second tine can wear behind the projection. For this purpose, the projection is, for example, an arrow-shaped, so that the tines can lock on an undercut.

The sliding element with the prongs preferably has a passage recess on the tine bottom, so that the fork end of the main body can extend into the tine gap. Thus, the main tine is arranged radially on the inside, and the snap teeth snapped radially on the outside.

The invention is also achieved by a shift fork according to claim 9. For this purpose, the sliding element on two substantially parallel, axially directed walls, the sliding sleeve side are at least partially connected by a radial arc. Seen in longitudinal section to the transmission axis, the sliding element thus has a U-shaped profile. Due to this profiling, it is particularly stable and can absorb high forces and at the same time support itself securely on the basic body. The sliding element is preferably formed in cross-section complementary to the base body. Stability is maximized when the slider has the U-shaped profile over its entire length. All embodiments listed above to claim 1 can be transferred to a shift fork according to claim 9. The parallel walls can be combined particularly well with a closed cross-section.

In a development, the longitudinal section profile of the sliding element itself is used for snapping. Then no separate snap element must be formed, but the walls of the sliding element elastically spring during assembly on the base body and snapping back into their original shape in the end position.

In a further variant, the sliding element has a radial stop. The radial stop prevents expansion of the sliding element in operation, if the shift fork is locally exposed to high loads due to the friction during shifting and temperature-induced loosening due to different thermal expansion coefficients of the materials occur.

Furthermore, end stops can be provided for fixing the sliding element in its final position.

Brief description of the drawings

The invention will be explained below with reference to exemplary embodiments. Show it:

1 is a perspective view of a first fork according to the invention with two fork legs, Figure 2 is an enlarged view of a fork leg of Figure 1 in a perspective oblique view, FIG. 3 shows a perspective illustration of a second shift fork according to the invention with a sliding element,

FIG. 4 shows an enlarged view of the sliding element from FIG. 3 in a perspective oblique view,

Figure 5 is a perspective view of a third shift fork according to the invention with a sliding element, Figure 6 shows a cross section of the main body of the shift fork according to

FIG. 5,

FIG. 7 shows an enlarged view of the sliding element from FIG. 5 in a perspective oblique view,

Figure 8 is an enlarged view of the fork leg ends of

Main body of FIG. 5,

9 is an enlarged view of the one fork leg according to FIG. 5 in a perspective oblique view;

10 shows a cross section of a basic body of a fourth shift fork according to the invention according to FIG. 11 and FIG. 11 shows a cross section of the fourth shift fork according to the invention with the sliding element.

Detailed description of the drawings

Figure 12 shows a switching unit 1 with a at least axially movable to a transmission shaft, not shown, shift rod 2 and a shift fork 3. The shift fork 3 is fixedly connected to the shift rod 2, so that triggered by an operator or an actuator movements of the shift rod 2 the Shift shift fork 3 axially to a gear by means of a shift sleeve, not shown or interpret. The shift fork 3 has a base body 4 and a sliding element 5. The main body 4 is semicircular and has two fork legs 6, 7, the fork leg ends 9, 10 with respect to the transmission axis 8, not shown are opposite, so are arranged approximately 180 ° to each other. The fork legs 6, 7 are seen in cross section to the transmission axis to their fork leg ends 9, 10 relatively narrow and widen in the base 1 1, in which they merge into one another. The connection of the shift rod 2 also takes place in the base 1 1. For this purpose, the main body 4 has a radial bead 12 with a shift rod feedthrough 13.

The base body 4 is connected radially inwardly with the sliding element 5. The sliding element 5 is a plastic molded part whose radially outwardly directed contour is complementary to the inner contour of the base body 4. Thus, it is on the inside over the entire range of the shift fork on the base body 4. End side, the slider 5 sliding shoes 14, 15, the front side with respect to the base body 4 protrude axially slightly. The two differently shaped sliding shoes 14, 15 are connected to one another via a substantially flat, band-shaped bent half-ring 16 having in its center two radially outwardly directed tabs 17, 18 for connection to the base 1 1 of the base body 4. The second sliding shoe 15 differs from the first sliding shoe 14 in that it comprises a holding element 21 in the form of a cylinder with a semicircular cross section, which connects the two axially directed Gleitschuhwandungen 22, 23 with each other. Furthermore, it has no to the Gleitschuhwandungen 22, 23 vertically directed bottom 24 for supporting on the base body 4.

The thickness of the fork legs 6, 7 is reduced at the leg ends 8, 9. As a result, the required axial space for the shift fork 3 is not the sum of the sheet thickness of the main body 4 and the thickness of the sliding element 5, but is reduced compared to this sum. Furthermore, the base body 4 at the base 1 1 has a reduced in the sheet thickness region 19th on, which hardly reduces the transferable forces by the shift fork 3 forces at this point. It is configured in the shape of a crescent and represents a transport safety, since in cooperation with the lugs 17, 18 it prevents the sliding element 5 from swinging out.

The base body 4 made of sheet metal is produced without cutting from steel or aluminum sheet by stamping, deep drawing or other cold forming techniques. The sliding element 5 is manufactured separately from the main body 4. Figures 1 and 2 show a shift fork 3 with a guide tube 45 for a shift rod, not shown, and with a switching arm 46. The shift fork 3 has a fork-shaped base body 4, on the inside of the sliding sleeve, not shown, a slider 5 is arranged in the form of a half ring , The main body 4 has an axially directed board 47 for its stiffening. The sliding element 5 has a rectangular profile in longitudinal section with two axially directed walls 42, 43, which are interconnected by a radial arc 48. For positioning of the radial arc 48 on the base body 4, it has a window 49 as a positioning aid. The window 49 may be in positive or non-positive connection with the base body 4 in connection, for example, on this snub.

The sliding element 5 has at its end in each case a passage recess 44, which is penetrated by the leg ends 9, 10 of the base body 4. To improve the rigidity of the sliding element 5, this end is provided in each case with a closed profile 50, which surrounds the leg end 9 or 1 0 in a rectangular manner. Under load of the shift fork 3 thus bending of the sliding element 5 is prevented.

At the radially outer edge of the closed profile 50, a snap element 30 is arranged in the form of a snap-action hook. The snap element 30 has two legs 32, 33, which are connected to one another via a connection base 31. While one leg 32 is fixedly connected to the closed profile 50, the other leg 33 is at its the connection base 31 opposite end unconnected, so that he can deflect. The main body 4 has a recess 38, in which the leg 33 can snap or lock. The shift fork 3 according to the figure 3 differs from the shift fork 3 of Figure 1 by the connection of a differently shaped sliding element 5. As can be seen from Figure 4, the sliding member 5 is semicircular in cross section. Its outer contour corresponds to the inner contour of the switching jaw 25 of the base body 4. Seen in longitudinal section, the sliding element 5 is formed like a trough with a groove 51 directed towards the base body 4. The groove 51 is encircling and continues into the slide elements 34, 35 formed as secondary teeth 37. The radial arc 48 forms the bottom of the groove from which perpendicular walls 42, 43 extend, which surround the base body 4 axially in the mounted state. The Gleitelementenden 34, 35 split fork-shaped in two prongs 36, 37 with a zinc gap 52 on. The inside first prong 36, on which the sliding sleeve rubs, is made thicker than the second prong 37 as the main prong. The sliding element 5 snaps on the base body 4 with the secondary prong 37. For this purpose, the leg ends 9, 10 of the main body 4 are arrow-shaped. During assembly, the prongs 36, 37 of the sliding element 5 are initially spread by the dovetails 54 of the arrow contour, and the second prong 37 subsequently latches against the undercut 53 of the arrow contour. The groove 51 is connected via a passage recess 44 to the tine gap 52, so that in the assembled state the leg ends 9, 10 extend into the tine space 52. By locking the sliding element 5 and the base 4 are fixed to each other. On the back engages a guide member 40 of the fork leg 6 in a radial recess 39 which is part of the groove 51 here to ensure a backlash-free fixation. Figures 5 to 9 show an embodiment of the shift fork 3 with a sliding member 5, which differs from the Gleitschuhelement 5 of Figure 4 in that instead of tines 36, 37 at the Gleitelementenden 34, 35 thickenings in the form of Gleitschuhwandungen 22, 23 has , The circulating Groove 51 also extends between the Gleitschuhwandungen 22, 23. During assembly, the Gleitschuhwandungen in the direction of arrow 55 are axially expanded and verschnappen in their final position in corresponding Schnappausneh- ments 56 of the base body 4. The leg ends 9, 10 also Rast- clog 57 on , which engage positively in counter-contours 58 of the sliding element 5 in the installed state.

The radial arc 48 does not connect the walls 42, 43 on the entire semicircular circumference of the sliding element 5. Rather, it eliminates the end, so that the Gleitschuhwandungen 22, 23 can axially auffedern during assembly. The groove 51 is still continued over the end of the base body 4 and runs in the rounded Gleitelementenden 34, 35 from.

Furthermore, the sliding element 5 radial stops 41, which prevent expansion of the sliding element 5 with mating surfaces on the base body 4. The main body 4 also has a contact surface 60 for the sliding element 5, which may also be identical to the radial stop in a variant, not shown. In addition, the sliding element 5 has a snap hook as a separate snap element 30, which can latch in a complementary recess of the base body 4.

Under load by the shift sleeve all snap elements 30 and the locking pads 57 or all other stops of the sliding member 5 are pressed into the corresponding recesses on the base body 4, so that the main body 4 and the sliding member 5 form a secure bond.

The embodiment according to FIGS. 10 and 11 differs from that according to FIGS. 5 to 9 in that the snap-action recesses 56 are not arranged radially on the outside of the main body 4 but radially inwardly. The sliding element 5 designed as a sliding-shoe ring is adapted accordingly. reference numerals

1 switching unit

2 shift rod

3 shift fork

4 main body

5 sliding element

6 first fork leg

7 second fork leg

8 (not occupied)

9 first leg end

10 second leg end

1 1 base

12 bead

13 shift rod feedthrough

14 first sliding shoe

15 second shoe

16 half ring

17 tab

18 tab

19 reduced range

20 groove

21 retaining element

22 Gleitschuhwandung

23 sliding shoe wall

24 floor

25 shift mouth

26 first sliding leg

27 second sliding leg

28 (not occupied)

29 (not occupied)

30 snap element

31 connection base 32 thighs

33 thighs

34 first sliding element end

35 second sliding element end

36 first tines

37 second tines

38 recess

39 Radial recess

40 guide part

41 radial stop

42 first wall

43 second wall

44 through-hole

45 guide tube

46 switching arm

47 board

48 radial arc

49 windows

50 closed profile

51 groove

52 tine gap

53 undercut

54 arrow slope

55 arrow direction

56 snap recess

57 latching block

58 counter contour

59 (not occupied)

60 contact surface

Claims

claims

Gearshift fork (3), which a fork-shaped base body (4) with opposite fork legs (6, 7) forming a switching mouth (25) for guiding a shift sleeve, and a one-piece, separately manufactured sliding member (5) for contact with the shift sleeve characterized in that the sliding element (5) engages around the fork legs (6, 7) radially at least partially and is snapped against them by means of a snap element (30).

Shift fork (3) according to claim 1, characterized in that the snap element (30) is designed as a snap hook.

Shifting fork (3) according to claim 2, characterized in that the snap element (30) is snapped radially on the outside of the fork-shaped base body (4).

A shift fork (3) according to claim 3, characterized in that the snap element (30) has two legs (32, 33) connected to each other via a connection base (31), the legs (32, 33) being tangential to the fork legs (6, 7) ) are directed and the connection base (31) in the circumferential direction as seen to the fork-shaped base body (4) facing out oriented.

Gearshift fork (3) according to claim 2 or 3, characterized in that the sliding element ends (34, 35) fork-shaped two prongs (36, 37), wherein one of the prongs (36, 37) forms the snap element (30).

Gearshift fork (3) according to claim 5, characterized in that the snap element (30) on a recess (38) of one of the fork legs (6, 7) is snapped and that the snap element (30) has a radial recess (39) into which a guide part (40) of the fork leg (6, 7) engages.

7. shift fork (3) according to claim 3, characterized in that the sliding element (5) is snapped axially on the base body (4).

8. shift fork (3) according to claim 3, characterized in that the sliding element (5) has a radial stop (41).

9. shift fork (3) according to the preamble of claim 1, characterized in that the sliding element (5) has two axially parallel walls (42, 43), which are sliding sleeve side connected to each other.

Gearshift fork (3) according to one of the preceding claims, characterized in that the sliding element (5) has a closed cross section with a through-passage (44), into which one of the fork legs (6, 7) extends, so that the fork leg (6 , 7) is enclosed radially and axially by the sliding element (5).