GB2286436A

GB2286436A - Device for shifting a transmission using a synchronizing device

Info

Publication number: GB2286436A
Application number: GB9502415A
Authority: GB
Inventors: Klaus Herberg
Original assignee: Dr Ing HCF Porsche AG
Current assignee: Dr Ing HCF Porsche AG
Priority date: 1994-02-09
Filing date: 1995-02-08
Publication date: 1995-08-16
Anticipated expiration: 2015-02-08
Also published as: FR2715979A1; DE4404093C1; GB2286436B; GB9502415D0; FR2715979B1; DE4404093C2

Abstract

The synchronisation device uses sprung balls that hold a sleeve in a neutral or engaged position. The gear shift sleeve's (1) inner peripheral surface (60 contains a second, hollow conical (11) cavity (3) directly adjacent to the first cavity (2) for achieving power peaks in the gearshift sleeve's overthrust force (U) with intermediate release of synchronisation. Transfer edges (4, 5) for the balls (7) are positioned between the two cavities and the inner peripheral surface of the gearshift sleeve. An axial section of the gearshift sleeve's inner peripheral surface follows the second transfer edge (5). The balls are connected to the gearshift sleeve's transfer edges.

Description

2286436 1 Device for Shifting a Transmission by way of a Synchronizing

Device The invention relates to a device for shifting a transmission by way of a synchronizing device comprising a gear-shift sleeve held in a neutral and shifting position by means of thrust members comprising spring-loaded balls, wherein the balls engage in a retaining manner on the inner peripheral face of first recesses in the gear-shift sleeve, and when an overthrust force is produced on the gear-shift sleeve an axial force is exerted on a locking block guiding the ball and on a synchronizing ring.

In conventional designs, devices for synchronizing gear shifts, for example from a first gear into a second gear, comprise a synchronizing ring which is operatively connected to a gear-shift sleeve and which can be brought into engagement with a coupling member of a loose gear by axial displacement. A so-called overthrust force is produced on the gear- shift sleeve by way of a spring-loaded ball acting upon the gear-shift sleeve, and exerts an axial thrust on a locking block and the synchronizing ring. This axial thrust acts upon the synchronizing ring and displaces it axially. In 2 this way., a connection is made between the synchronizing ring and the friction ring at the rotational speed of the driving shaft on the one hand and the cone ring at the driven rotational speed on the other hand.

In this conventional synchronizing system the synchronizing device is completely unlocked in this position and the gear-shift sleeve can be displaced further axially, a pre-condition for the ideal creation of positive locking being that the rotational speeds should be momentarily equal, i.e. there should be no difference in the rotational speeds. In practice it happens that the synchronized rotational speeds deviate and when a through connexion is made there is a so-called gear-shift scraping.

An object of the invention is to provide an improved device for gear shifting, by which the above-mentioned disadvantages are avoided and socalled gear-shift scraping is prevented.

The invention provides a device as claimed in Claim 1. Further preferred embodiments are claimed in the Sub-Claims.

With a device according to the invention it becomes possible for a subsequent synchronization to be achieved il 3 by means of two recesses formed in succession in the inner peripheral face of the gear-shift sleeve and separated from one another by overpass edges and by means of a spring-loaded ball held in the locking block.

The recesses each produce a peak in the overthrust force of the gearshift sleeve, and a drop in the overthrust force is produced between the two peaks, so that the loaded synchronizing device can be briefly released and the gear-shift sleeve can then be displaced axially to a slight extent.

This second peak of force, resulting from the second recess, has the effect that a further axial thrust is exerted upon the synchronizing ring. The synchronizing ring is thus thrust a second time, as a result of which a so-called subsequent synchronization is achieved. The originally synchronized parts, the rotational speeds of which deviate again, however, are thereby coupled by non-positive locking, so that a scrape-free through connection becomes possible.

Claims

The features of Claims
2 to 4 are used to achieve the different peaks of

force and the drops in the overthrust force.

The further features as claimed in Claims 5 to 7 4 con-ai'n varous i569gitlg gfflbodimgnts of the 5econd recess.

Embodiments of the invention will now be described by way of example only in the accompanying drawings, wherein:

Figs. 1 to 4 show diagrammatically in section possible positions of a gear-shift sleeve of a synchronizing device with a locking block and spring-loaded balls positioned accordingly, Figs. 5 to 8 are force-path graphs corresponding to the Figs. 1 to 4, and Figs. 9 to 13 are enlarged sectional views of the gear-shift sleeve with the locking block and the spring-loaded ball from the neutral position as far as the through-connexion position.

In the drawings, a gear-shift sleeve 1 is provided on the inner peripheral face 6 thereof with two recesses 2 and
3 which are arranged in succession and which are separated from each other by an overpass edge
4. A further overpass edge
5 is provided between the second recess 3 and the inner peripheral face
6. A ball
7 is arranged in a locking block 8 opposite the recesses 2 and 3, and is urged against the gear-shift sleeve 1 by means of a spring 9.

The recesses 2 and 3 are arranged one immediately behind the other as viewed in the displacement direction 10 of the gear-shift sleeve 1, for example for shifting from a first gear into a second gear of a transmission. The overpass edge 4 between the two recesses 2 and 3 has a larger internal diameter D than the further following overpass edge 5, which has a smaller internal diameter d.

As the gear-shift sleeve 1 is displaced, the overpass edges 4, 5 produce two peaks of force 14 and 16 and a drop in force 15 between the peaks via the ball 7. The force pattern is illustrated over a path S and the overthrust force F in the graphs of Figs. 5 to 8. The corresponding position of the gear-shift sleeve 1 is shown respectively in Figs. 1 to 4 and 10 to 13.

The recess 3 may be formed as a channel 11, a groove, a flat face 12 or an oblique face; it is essential that only two overpass edges 4 and 5 are formed.

Figs. 1 to 4 show recesses 3 in the form of 6 channels 11, and Figs. 9 to 13 show recesses, for example, in the form of flat faces 12.

Fig. 9 shows the gear-shift sleeve 1 in a neutral position I, in which the ball 7 is situated in the first recess 2.

In the following position II shown in Fig. 10 the gear-shift sleeve 1 is displaced in the direction of the arrow 10 for synchronization and the ball 7 is urged against the spring 9, as a result of which the locking block 8 is displaced slightly in the direction 13 towards the synchronizing ring (not shown). By passing over the overpass edge 4 provided between the two recesses 2 and 3 the ball 7 produces a first peak 14 in the overthrust force F of the gear-shift sleeve 1.

As the gear-shift sleeve 1 is displaced further, the ball 7 adopts a position in the recess 3 such as for example in the channel 11 or on the flat recess 12. In this position III (see Fig. II) the synchronization is unlocked and the overthrust force F drops to a point 15 (Fig. 6). The loaded synchronizing is released and the gear-shift sleeve 1 can be displaced axially.

As the gear-shift sleeve 1 is displaced further into position IV (Fig. 12), the ball 7 produces the 7 second force peak 16 by means of the further overpass edge 5 at the end of the second recess 3. This force peak 16 is higher than the first force peak 14. This higher force peak 16 causes a further pressing upon the synchronizing ring by way of the locking block 8, as a result of which a second pressing and thereby a subsequent synchronization can take place.

As shown in greater detail in Figs. 4 to 13, positive locking is achieved by pushing the gear-shift sleeve 1 into the through-connection position V, in which case the ball 7 slides along the inner peripheral face 6 of the gear-shift sleeve 1.
8. A device substantially as herein described with reference to any of the embodiments shown in the accompanying drawings.

8 Claims:

A device for shifting a transmission by way of a synchronizing device comprising a gear-shift sleeve held in a neutral and shifting position by means of thrust members comprising spring-loaded balls, wherein the balls engage in a retaining manner on the inner peripheral face of f-j:st recesses in the gear-shift sleeve, and when an -jverthrust force is produced on the gear-shift sleeve an axial force is exerted on a locking block guiGing the ball and on a synchronizing ring, characteri:ted in that a second recess immediately adjacent to the first recess is provided in the inner peripheral face of the gear-shift sleeve in order to achieve increasing peaks in the overthrust force of the gearshift sleeve with the intermediate unlocking of the synchronization, and first and second overpass edges are provided between the two recesses and between one of the recesses and the inner peripheral face of the gear-shift sleeve, respectively.

2. A device according to Claim 1 wherein the ball for synchronization is in contact with the overpass edges of the gear-shift sleeve in such a way that peaks in the overthrust force are produced having different 9 magnitudes, and a drop in the overthrust force is introduced between the two peaks of force by means of the position of the ball in the second recess of the gearshift sleeve.

A device according to Claim 1 or 2, wherein the first overpass edge is provided in the transition region from the first recess to the second recess, the overpass edge having a larger internal diameter than the second overpass edge frora the second recess to the inner peripheral face of the gear-shift sleeve.

4.

A device according to Claim 3, wherein a first low peak in the overthrust force of the gear-shift sleeve is achieved on the first overpass edge with the larger internal diameter and the second following higher peak force on the overpass edg with the smaller internal diameter.

A device according to any one of the preceding Claims, characterized in that the second recess comprises a channel.

A device according to Claim 3 or 4, wherein the second recess comprises a flat face and has an internal diameter corresponding to the larger internal diameter of the first overpass edge.

7. A device according to Claims 1 to 4, wherein the second recess comprises an oblique plane which terminates with an offset at the second overpass edge.