WO2012041541A1

WO2012041541A1 - Shift fork having sliding shoes

Info

Publication number: WO2012041541A1
Application number: PCT/EP2011/058882
Authority: WO
Inventors: Uwe Schwarz; Matthias Feuerbach
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2010-09-30
Filing date: 2011-05-31
Publication date: 2012-04-05
Also published as: DE102010047140A1

Abstract

The invention relates to a shift fork (1), which has two fork arms (3). Sliding shoes (2) are arranged on the fork arms (3). The sliding shoes (2) have a through-opening (4) along the longitudinal axis thereof, wherein said through-opening is used to fasten on the fork arm (3).

Description

Name of the invention

Shift fork with sliding shoes Description

Field of the Invention The invention relates to a shift fork with two fork arms having sliding shoes.

Background of the Invention Such a shift fork is known from DE 10 2007 009 120 A1. The shift fork has two fork arms with sliding shoes arranged thereon. The sliding blocks are arranged on the mutually facing side of the fork arms and can be brought into engagement with a groove of a sliding sleeve. In this case, fastening possibilities are disclosed from the facing sides of the fork arm in the direction of the remote side of the fork arms. For this purpose, the sliding blocks have positive snap-in connections. This has the disadvantage in the preferred use of plastic, that these Einschnappmittel can bend or break, resulting in an indeterminable durability of the attachment. Furthermore, this arrangement of shift fork and shoe has the disadvantage that the mounting direction of the shoe on the shift fork is not identical. As a result, assembly time is lost.

In DE 196 45 522 it is disclosed that the free ends of the fork arms are encapsulated with plastic to form a sliding shoe. In this case, plastic can escape from the gaps between the workpiece and the tool. These gaps are caused by the tolerance-related geometry of tool and workpiece. Additional methods of removing excess and unused material are therefore required. DE 100 45 506 A1 discloses a shift fork with two fork arms, wherein at the free ends sliding shoes made of plastic are arranged. These plastic shoes are attached by gluing, shrinking or spraying. The escort shoes are in the form of plastic caps. After pressing the plastic caps disadvantages caused by the effect of temperature on the different materials in operation. Due to the different expansion coefficients, the oversize connection can be solved. When gluing the plastic caps with the fork ends, a free space for the adhesive must be provided between the plastic cap and the fork arm. A resulting positioning error adversely affects the accuracy of the arrangement in contact with the sliding sleeve.

Summary of the Invention It is therefore an object of the invention to provide a shift fork with sliding shoes mounted thereon, which are reliably connected.

According to the invention, this object is achieved in that the shift fork has a shoe according to the preamble of claim 1, wherein the shoe is integrally formed and has a passage opening for arrangement on the fork arms of a shift fork. In this case, the sliding block is completely penetrated by a fork arm along its passage opening. The fork arm is enveloped by the through hole. Shift forks are used in transmissions as a link between a switching element in the form of a switching shaft or shift rod and a shift sleeve of a synchronizer body. Switching movements are transmitted from the switching element by the shift fork on the shift sleeve. The shift fork is arranged on the switching element. The shift forks also include the shift rockers. The shift fork has two fork arms, at the free ends of the sliding shoes are arranged. These shoes are engaged with the sliding sleeve. The sliding shoes have sliding surfaces, which are in engagement with a radial web of the sliding sleeve. The sliding surfaces, and also the sliding shoes, are arranged facing each other on the shift fork.

According to the invention, each sliding block has a passage opening in the direction of its longitudinal axis. The shoe is integrally formed and is mounted as a whole on the fork arm. Elaborate divisions of the shoe, which form an attachment to the fork arm by joining, are not present. Furthermore, no complex training of fasteners, such as snap-in lugs, arranged on the shoe. The passage opening forms a simple receptacle for a fork arm. Advantageously, a defined game between shoe and fork arm is provided. This game is carried out low so that sliding on the fork arm is possible, however, a position error in the radial direction during or after assembly fails very low.

According to the invention, the passage opening of the sliding shoe is completely closed in the circumferential direction. If the sliding block is arranged on the fork arm, then the lateral surface of the fork arm is encircled. Forces are transmitted from the fork arm to the sliding shoe with little deformation due to this closed through opening, and a high stability of the connection of the sliding shoe to the fork arm is ensured. This high stability ensures a torsion and torsion-free function.

Alternatively it can be provided that the closed cross-section of the passage opening does not extend completely over the entire longitudinal axis of the slide shoe. When using a long sliding shoe along its longitudinal axis, can be dispensed with in part on the complete enclosure of the fork arm through the through hole. Thus, a complete enclosure at the ends of the longitudinal axis of the shoe take place, which has a positive effect during assembly. Long through openings, which are closed on the circumference, place increased demands on the manufacturing accuracy of the geometric shape along the longitudinal axis. In the case of a local, isolated arrangement of circumferentially closed passage openings ments along the longitudinal axis of the sliding block, the effort is reduced to the actually usable areas for the connection. This facilitates assembly and reduces the weight of the shoe. The required stability is given due to the relatively wide spacing of the circumferentially closed passage openings.

In one embodiment of the invention, the passage opening with the profile of the fork arm on a rotation of the shoe around its longitudinal axis. In this case, the passage opening may be formed in cross-section as a polygon. The profile of the fork arm must in this case have complementary surfaces which ensure an anti-rotation. Such a shoe can no longer rotate about its longitudinal axis. This is necessary to ensure alignment of facing shoes. Profiles of the passage opening can be, for example, square, rectangular or oval. Circular profiles are suitable conditionally to use an anti-rotation, since additional components are required to lock the degree of freedom of rotation of the shoe around its longitudinal axis.

In an advantageous embodiment of the invention, the shift fork is formed of sheet metal. It can be formed on the fork arms different profiles. Depending on the sheet metal design of the shift fork such profiles of the fork arms may be L-shaped, U-shaped, C-shaped, with and without fold, with or without doubling. Advantageously, the profiles of the passage opening of the sliding block can be combined with each other such that the variety of parts of the sliding shoes is minimized. For example, both an L-shaped profile and a U-shaped profile of the fork arm can be combined with a rectangular profile of the passage opening of the sliding shoe. In the advantageously designed dimensions of the profiles, both complementary anti-rotation locking surfaces are formed and the radial position of the sliding shoe is fixed to the fork arm.

According to the invention, the sliding shoes are made of wear-resistant material. These materials can be copper alloys, plastics or others Be materials with advantageous sliding properties. It is advantageous for the shoes to choose a different material from the shift fork material to reduce costs of the shift fork. In one embodiment of the invention, the passage opening has a rectangular-shaped profile. Advantageously, the fork arm is also formed in a rectangular shape in its profile. When using sheet metal as a fork arm, a rectangular cross-section is easy to produce. The preparation of the cross section can be done by reshaping the base material in view of the available space. To avoid elaborate Entgratprozessen at the outer edges of the fork arms in the connecting region with the sliding shoes, material recesses are provided in the inner corners of the passage opening. Thus, a trouble-free installation of the shoe is guaranteed on the fork arm and a complex deburring process on the fork arms is avoided.

These material recesses advantageously have the form of curves. These curves extend into the material of the shoe. This results in a clearance for the untreated outer edges of the fork arms and a trouble-free installation is given.

Alternatively, the fork arms may have edge conditions that provide sufficient clearance for installation. These edge states can be radii or chamfers. An arrangement of radii or chamfers on the edges is given in manufacturing processes such as casting.

In an embodiment according to the invention, the passage opening has a constant cross section along the longitudinal direction of the sliding block. Here are materials that are brought by casting, sintering or extrusion in the desired shape. Such materials can be plastics or metals. Through the use of original and forming processes almost every profile can be produced for the passage opening. When using metals is advantageously the space of the shoe in contrast not increased for training with plastic. When using plastic, a metal core can be used to reinforce the structure of the shoe. Optionally, alternatively or additionally, methods such as milling, broaching or grinding are used to achieve the desired quality of the surfaces.

Another possibility of the invention is not to completely close the cross section of the passage opening partially or continuously along the longitudinal axis. Advantageously, the sliding shoes can be slotted along their longitudinal axis on the mutually applied sides. In this case, a frictional connection can be formed, which minimizes the radial clearance after mounting on the fork arm.

In one embodiment of the invention, the fork arm has an assembly stop. This mounting stop serves to fix the sliding block along its longitudinal axis. A limitation of the game along the longitudinal axis of the sliding block is advantageous in changes of direction of the sliding sleeve. Constant contact on the mounting stop so noise is avoided by changing the direction of rotation of the shift sleeve and the service life is increased.

Advantageously, a contact between the shoe and the mounting stop is made during assembly. The shoe is fixed by securing means at the free ends of the fork arms. In an embodiment of the shift fork made of metal, the free end of the fork arm for axial securing of the shoe can be reshaped. In this case, the circumference of the profile of the fork arm relative to the profile of the passage opening, for example by caulking, increased and such material displacements cause attachment of the sliding shoe on the shift fork. A radial displacement of the profile of the fork arm relative to the profile of the passage opening, for example by bending, may be an alternative to the axial securing. Other securing means may be indirect elements such as split pins, rivets, pins or screws. Alternatively, the Securing means, directly and indirectly, be placed in each area of the connection, without being limited to the free end of the fork arm. Alternatively, a game between the mounting stop and the shoe may be formed. The shoe can move axially on the fork arm and is limited by the mounting stop and the captive. This may be advantageous to allow for rough tolerances in the axial direction of the passage opening with respect to the overall length of the sliding shoe.

In an advantageous embodiment, the shift fork is made of sheet metal. It is advantageous to form the assembly stop as a step by forming processes. Such forming processes can be pressing, stamping, bending or deep-drawing. The shift fork may also be formed from other base profiles than from sheet metal.

Optionally, the shift fork is formed from a casting process. In this case, the assembly stop can advantageously be cast in the process. Alternatively, the mounting stop may be formed from a cross-sectional widening of the fork arm. This can be done by the formation of curves in the direction of the connection of both fork arms. Furthermore, the free end of a fork arm can also be tapered towards the free end, for example by the use of conical surfaces. A corresponding formation of the passage opening is required here. The integrative training of anti-rotation of the shoe with the mounting stop saves space.

In one embodiment according to the invention, the sliding shoe has parallel elevations along its longitudinal axis. These surveys are done in pairs. The mutually facing sides of the elevations of a sliding block form sliding surfaces for contact with an annular web on the sliding sleeve. The overall width of the shoe is determined by the elevations not significantly increased. The elevations encompass the radial web of the sliding sleeve. The radial web is flanked by the sliding surfaces. An advantage of this arrangement is the simpler structure of the shift sleeve, in which a web needs to be attached or manufactured. As a result, depending on the method welds can be omitted, the service life is increased and the stresses of the material used decreases.

The inventive arrangement of the parallel elevations, the shoe on a high torsional stiffness. The elevations can extend completely along the longitudinal axis of the sliding shoe. Advantageously, these elevations are formed with the sliding surfaces only partially in the contact area with the shift sleeve. The high torsional rigidity and the targeted arrangement of the sliding surfaces form a low weight sliding shoe and increased service life.

As an alternative to the sliding surfaces formed integrally with the sliding shoe, an additional reinforcement can be provided. This reinforcement has the sliding surfaces and is arranged on the shoe. The reinforcement reinforces the sliding surfaces on the shoe and advantageously increases the life. This reinforcement may be formed as a coating.

In a further embodiment, the reinforcement may be formed as a separate component and is fixed in the longitudinal direction via radially aligned rear gripping at the ends of the sliding block. The fixation in the radial direction of the shoe is made by material connections such as gluing, soldering or the like. Advantageously, a different material for use at the contact to the shift sleeve can be selected here, as for the sliding block. The materials used are provided with advantageous sliding properties. Furthermore, application-specific sliding elements can be arranged on the same sliding shoes. Alternatively, identical sliding elements can be arranged on different application-specific sliding shoes. In both cases, the numbers are increased, which reduces the manufacturing costs and the variety of parts. Another aspect of the invention is a method for mounting the sliding shoes on the fork arms. The alignment of the passage opening of the sliding shoes with the free ends of the fork arms is such that the sliding surfaces of the sliding shoes face each other. Thereafter, the shoes are attached to the fork arms. This process can be done in parallel for both fork arms. The advantage here is the reduction of assembly costs due to the parallel processes and the simple assembly direction. Alternatively, the shift fork can be rotated until the next fork arm assumes the position of the previous one. Then the next shoe is attached. It is advantageous to hold the shift fork so that the shoes are pressed by the gravitational force against the mounting stop.

This is followed by the production of the axial securing of the sliding shoe. In this case, a tool is advantageously placed on the free end and under predetermined force introduction line and feed the material displaced or caulked at the free end. Optionally, middle securing elements can be provided, aligned, fed and joined in corresponding openings.

Thus, a shoe is arranged on a fork arm of a shift fork, which has a reliable connection and is easy to assemble.

Brief description of the drawings

An embodiment of the invention is shown in the figures. Show it:

1 is a shift fork with two fork arms and sliding shoes arranged thereon, 2 is a plan view of a free end of a fork arm of the shift fork of FIG.

3 is a shift fork, which is in engagement with a shift sleeve, Fig. 4 is a plan view of a free end of a fork arm of the shift fork according to Fig. 3,

Fig. 5 is a shift fork with two fork arms and arranged thereon

Sliding shoes, which have additional reinforcements, Fig. 6 is a detail view of a sliding shoe according to Fig. 5,

Fig. 7 shows a cross section through the shoe according to Fig. 5 and

8 shows a longitudinal section through the sliding block according to FIG. 5.

Detailed description of the drawings

In Fig. 1, a shift fork 1 is shown. The shift fork 1 has two fork arms 3. The fork arms 3 are punched from a sheet and form a crescent. In the middle of the half-moon, a cylindrical bushing 14 is arranged for receiving a switching shaft. The cylindrical sleeve 14 has a hole transverse to its longitudinal axis to be axially fixed to a selector shaft. On the middle inside of the crescent a middle slide shoe 5 is arranged. At the free ends 9, the shift fork 1 forms a square profile. At each fork arm 3, a sliding shoe 2 is disposed at the free ends 9, respectively. The free end 9 of each fork arm 3 extends completely through the shoe 2. The shoes 2 are aligned facing each other. The shift fork 1 has an assembly stop 10 on each fork arm 3. The mounting stop 10 is formed by a broadening of the sheet of the shift fork 1.

In Fig. 2 is a plan view of one of the two free ends 9 is shown. The sliding block 2 encloses the fork arm 3 completely with its passage opening 4. In this case, the passage opening 4 and the fork arm 3 have a square profile 5. Both sliding blocks 2 have sliding surfaces 13 which can be brought into contact with a shift sleeve, not shown. The sliding surfaces 13 are within the material thickness of the shift fork 1 and are arranged symmetrically to its center plane. Over the lateral surfaces of the square see profile 5, the shoe 2 is secured against rotation on the fork arm 3. The square profile 5 of the free end 9 of the fork arm 3 is picked up by the passage opening 4. The passage opening 4 of the sliding shoe 2 has rounded corners 6. The rounded corners 6 have the formation of undercuts. Of the undercuts two extend in the same direction and the other two in the opposite direction. The wall thickness of the shoe 2 is circumferentially largely the same. In the extension direction of the through hole 4, the square profile 5 remains constant.

Fig. 3 shows an arrangement of the shift fork 1 with the shift sleeve 8. The shift sleeve 8 has a guide ring 12 which is formed circumferentially. The sliding shoes 2 are arranged on the shift fork 1 and are in contact with the guide ring 12 of the shift sleeve 8. The guide ring 12 has a constant height and width.

Fig. 4 shows a view perpendicular to the longitudinal axis of the shoe 2 with a view of the free end 9 of a fork arm 3 of the shift fork 1. Here, the shoe 2 engages on both sides an annular web 12 of the shift sleeve 8. The sliding surfaces 13 on the shoes 2 form the contact to the annular web 12th

Fig. 5 shows a shift fork 1 with two fork arms 3 and arranged thereon shoes 2. The free end 9 of each fork arm 3 extends completely through the respective shoe 2 therethrough. On the sliding shoes 2 each additional reinforcements 7 are attached. The two reinforcements 7 of a sliding block face each other. These reinforcements 7 form a reinforcement of the sliding surfaces 13. As a result, the sliding surfaces 13 on the sliding block 2 are made more solid and can be subjected to higher loads.

FIG. 6 shows a detailed view of FIG. 5 on a sliding shoe 2. The sliding surfaces 13 are reinforced by the reinforcement 7. The additional reinforcement 7 has transverse grips 11 transversely to its longitudinal axis. This Hintergreifungen 1 1 form a contact to the shoe 2 and fix the reinforcement 7 in both directions with respect to its longitudinal axis. In this case, the reinforcement 7 is penetrated by the shoe 2 in the region of the center of the longitudinal axis. The reinforcement 7 is formed here from plastic. 7 shows a sliding shoe 2 with a reinforcement 7 and the sliding surfaces 13 arranged thereon. In this case, the passage opening 4 of the sliding shoe 2 has a square profile 5 with rounded corners 6. The profile of the free end 9 follows that of the through hole 4. The shoe 2 is made of metal by extrusion. The reinforcement 7 is made of plastic. The reinforcement 7 is supported by the shoe 2 in the loading direction, wherein the reinforcement 7 takes over the sliding function on the sliding surfaces 13 with the plastic. The reinforcement 7 is located within the outer contour of the shoe 2.

8 shows a section along the longitudinal axis of the sliding block 2. In this case, the passage opening 4 is completely penetrated by the free end 9. The additional reinforcement 7 has at both ends of its extension in the longitudinal direction of the rear engagements 1 1, which serve for fixing on the sliding block 2. The shoe 2 and the reinforcement 7 may additionally be cohesively connected by gluing or soldering and non-positively by an oversized connection. The reinforcement 7 protrudes in the longitudinal direction beyond the contours of the shoe 2 addition.

List of reference numbers) shift fork

) Shoe

) Fork arm

) Passage opening

) Polygon profile

) rounded edges

) Reinforcement

) Shift sleeve

) free end

0) Mounting stop

1) Hintergreifungen

2) guide ring

3) sliding surface

4) cylindrical bush

5) middle shoe

Claims

claims

1. shift fork (1) for a shift shaft, wherein the shift fork (1) has two fork arms (3) and on a fork arm (3) a sliding shoe (2) is arranged, characterized in that the sliding shoe (2) a

Through opening (4) which envelops the fork arm (3) in one piece.

2. shift fork (1) according to claim 1, characterized in that the sliding shoe (2) relative to the fork arm (3) by the formation of the passage opening (4) is secured against rotation.

3. shift fork (1) according to claim 2, characterized in that the passage opening (4) has a polygonal profile (5) with rounded corners (6).

4. shift fork (1) according to claim 1, characterized in that the sliding shoe (2) with an additional, engageable for frictional engagement with the shift sleeve, reinforcement (7) is provided.

5. shift fork (1) according to claim 1, characterized in that the sliding block (2) engages around a guide ring (12) of a shift sleeve (8) on both sides.

6. shift fork (1) according to claim 1, characterized in that the fork arm (3) at its free end (9) holding means for captive securing of the sliding block (2).

7. shift fork (1) according to claim 1, characterized in that the fork arm (3) at its free end (9) material displacements as a retaining means for captive securing of the sliding block (2).

8. shift fork (1) according to claim 1, characterized in that the fork arm (3) has a mounting stop (10) for the sliding block (2).

9. shoe (2) a shift fork (1) according to one of the preceding claims.

10. A method for producing a shift fork (1), wherein the shift fork (1) according to any one of the preceding claims, characterized marked characterized in that the sliding shoe (2) is pushed onto the fork arm (3) until it is the mounting stop (10). is contacted and then fixed in position so that on the fork arm (3) at its free, through the passage opening (4) projecting end (9) material is displaced to increase the circumference.