GB2085984A

GB2085984A - Synchronizing gear systems

Info

Publication number: GB2085984A
Application number: GB8131282A
Authority: GB
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 1980-10-17
Filing date: 1981-10-16
Publication date: 1982-05-06
Also published as: IT1142815B; DE3039231C2; IT8149285A0; BR8106679A; FR2492486A2; ZA816344B; DE3039231A1

Abstract

Two coaxially arranged elements, e.g. a toothed synchronizing body (2) and a gearwheel (5), rotating at different speeds are coupled together via an axially displaceable annular sleeve 1 which has internal clutch teeth (11) engageable with matching external teeth (21, 53) of the two elements. Spring-loaded pivotable locking members (3) cooperate with projections (41) of synchronizing ring (4) to transmit initial axial movement of sleeve (1) to ring (4), the projections then retaining the locking members in position to baulk further movement of the sleeve until the elements (2, 5) are synchronized - when the sleeve can depress the locking members and complete its travel. Alternate locking members simply engage the back of ring (4) in an alternative embodiment, and a synchronizing plate clutch may be employed instead of the cone clutch shown. <IMAGE>

Description

SPECIFICATION Synchronizing systems This invention relates to a locking synchronizing system such as is used, for example, in motor vehicle transmissions for synchronous engagement of the gears.

When a gear shift is made from one gear to another in a transmission, two constructional elements rotating at different speeds must be coupled together via an axially displaceable third element. These two rotating elements -- called hereafter a synchronizing body and gearwheel - each have in the case of known synchronizing systems external clutch teeth in which internal clutch teeth of the third element to be connected -- called hereafter the sliding clutch sleeve -- engage. If this sliding sleeve, which is for example in engagement with the non-rotating synchronizing body, is caused to slide over the external teeth of the gearwheel, the end-face impingement of the two toothed rims causes the teeth to knock over one another, which results in both a very loud unpleasant noise and damage to the teeth.

In order to prevent such clutch noises and corresponding damage, it is known to use a synchronizing system which first synchronizes the two elements to be coupled, i.e. brings them to the same speed, whereafter the sliding sleeve may be readily caused to slide into the corresponding gearwheel clutch teeth.

In accordance with the prior art - ZF - B- Synchronizing System/Publication 42290/R 2964-367 of March 1967, this is done by means of a so-called synchronizing ring which is disposed between the synchronizing body and the gearwheel in which, on one hand, it is rotated at the same speed as the synchronizing body and, on the other hand, forms a friction clutch with the gearwheel. The known synchronizing ring also has external clutch teeth which are of substantially identical configuration as the external clutch teeth of the two other elements, i.e. synchronizing body and gearwheel. In addition a plurality of so-called ball-head pins and thrust elements are provided and are axially displaceable on the periphery in the synchronizing body, wherein the ball-head pin is spring-mounted in a radial direction.The ball-head pins engage in an annular recess in the internal bore of the sliding sleeve, as a result of which the sliding sleeve is in practice centered in a predetermined position.

When the sliding sleeve is axially displaced in a gear-changing operation, the ball-head pin and the thrust element are constrained to move with it in an axial direction, so that the thrust element presses axially against the synchronizing ring. The synchronizing ring is consequently displaced towards the gearwheel as a result of which the common frictional clutch is engaged. In this respect the synchronizing ring is deflected in the direction of the relative speed in a tangential manner up to an abutment in the synchronizing body, as a result of which the teeth of the synchronizing ring prevent the sliding sleeve from sliding through in the direction of the second clutch teeth. Only when both members are synchronized can the sleeve be further displaced through the teeth of the synchronizing ring, the ball-head pins being forced radially inwardly at the same time.

The synchronizing system using this known synchronizing ring is comparatively costly as a result of the teeth of this ring which includes locking skews and rear slides. Moreover, the sliding sleeve must be subjected to a relatively high actuating force in order to provide a corresponding force for the synchronous clutch.

In order to obtain an increased coupling force it is known to provide the synchronizing system with a double-cone friction clutch on the synchronizing ring. However, using this it would not even be possible to double the force by using more components and using considerably more space.

It is an object of the invention to provide a locking synchronizing system in which the sliding sleeve can be locked until synchronous running of the two components to be coupled as well as a simultaneous increase of the axially operating coupling force is achieved in a very simple and inexpensive manner, without any increase in the space requirement with respect to existing synchronizing systems. Furthermore, it should be possible to exchange simply and rapidly synchronizing systems which have already been installed with the synchronizing system of the invention, in which the application to all synchronized transmissions is taken into account.

Accordingly, the present invention consists in a locking synchronizing system for gear-shift transmission, in which two components disposed coaxially and rotating at different speeds, for example a synchronizing body and a gearwheel, are positively coupled together upon synchronous running by means of an axially displaceable, annular sliding sleeve, and in which internal clutch teeth of the sliding sleeve engage corresponding external clutch teeth of each of the two rotating components, with locking members which are radially guided and spring-loaded in the synchronizing body, the locking members engaging in an annular recess on the interior of the sliding sleeve and being axially displaceable, and with a synchronizing ring which is arranged axially between the two components and effects substantially the same movement of rotation with the synchronizing body, parts of the gearwheel forming a friction clutch together with parts of the synchronizing ring, characterised in that on the locking member disposed in the synchronizing body and on the synchronizing ring there is only one working surface for the transmission of an axial thrust force and a radial-tangential locking force in the case of non-synchronization.

The invention of our Patent Application No.

2 048 399 is further developed in an advantageous manner by the present invention.

In the above publication, oblique or bevelled surfaces which extends outwardly in the peripheral direction on the synchronizing ring and inwardly on the locking member are disposed so as to cooperate with each other, these surfaces preventing coupling of the sliding sleeve with the gearwheel if the synchronizing body and the gearwheel to be coupled have different speeds and releasing the sliding sleeve when the same speed has been reached. Moreover, a further contact location is disposed on the above parts (locking member and synchronous ring) which locations cooperate and via which the force conveyed from the actuating sleeve to the locking member is increased for synchronization and transmitted to the synchronizing ring.

Although a very good reinforcement effect is achieved for the synchronization using this arrangement and in addition a more reliable locking effect is obtained in the case in which the gearwheel and the synchronizing body have different speeds, the friction losses are still relatively high although improved with respect to the prior art.

The arrangement in accordance with our copending Application is therefore particularly designed to improve the sliding over force of the sliding sleeve after the achievement of synchronous running.

As a result of the reduction to a single location of contact between the locking member and the synchronizing ring, via which both the axially operating thrust force and the radially-tangentially operating locking force are transmitted, it is possible to reduce friction particularly during unlocking and sliding over. If there is only a single location of contact present, the normal force extends spatially in a twisted manner to the axial direction, there is a further reduction of friction so that a smaller actuating force is required and therefore actuation is possible in an easier and more uniform manner with complete safety in operation during the locking process.

The reinforcement effect, locking effect and sliding over effect of the synchronization may be optimised independently of one another if the contact geometry and the angle of pitch on the locking member and possibly on the thrust element are appropriately designed. This is of particular importance in the case of disk synchronizations, as there is very little space available for their housing and in addition approximately nine friction pairs are required to achieve the friction effect of a cone synchronization of approximately the same size.

A further reduction of friction may be obtained if the working surfaces on the locking member and the synchronizing ring are curved, as in this way the unlocking process is facilitated.

If the working surfaces are formed as surfaces of rotation, economic and relatively simple production is possible in particular if in the case of the synchronizing ring these surfaces of rotation are disposed on projections which project in the axial direction towards the locking member.

If these surfaces of rotation are conical, as is the case if the projections on the synchronizing ring are conical or frusto-conical, the geometry is very simple and particularly easy to produce, although a relatively small contact surface theoretically a point contact -- must be taken into account.

If a lower pressing is to be achieved, it is convenient to form the projections oh the synchronizing ring as well as the working surfaces on the locking member as unparted hyperboloids which provide, in the case of reciprocal pressing, a line contact theoretically and a greater surface contact in practice, in comparison with a conical formation.

If radially spring-mounted thrust elements are disposed in a suitable manner in addition to the locking members distributed on the periphery of the synchronizing body, it is possible to accelerate the synchronization and to reduce the path of sliding over of the sliding sleeve. Moreover, the locking effect is more secure as long as synchronous running is not achieved between the synchronizing body and the gearwheel.

This simple embodiment having a single working surface respectively on the locking member and synchronizing ring may be used both for the cone and for the disk synchronization and furthermore may be used in a space of the same size.

By suitable formation of the geometry of the contact surfaces of the synchronization the wear adjustment may, as already disclosed in the Patent Application No. 2 048 399, be obtained in the same way and the power reinforcement is effective not only during the synchronization process by also during the unlocking process.

In addition to satisfying the particular object, the invention according to the main claim and the advantageous further embodiments satisfies in an optimum manner the main requirements of a locking synchronization system: - maintaining the locked condition during the speed equalization phase, and - unlocking which is as easy as possible when synchronous running has been achieved.

In order that the invention may be more readily understood, reference is made to the accompanying drawings which illustrate diagrammatically and by way of example embodiments thereof, and in which: Figure 1 is a fragmentary axial section through a first embodiment of a locking synchronization system in accordance with the invention, Figure 2 is a cross-section on the line Il-Il of Fig. 1, Figure 3 is a simplified axial section through a further embodiment of a locking synchronization system in accordance with the invention, Figure 4 is a simplified section from Fig. 2 in accordance with Fig. 3, Figure 5 is an axial section through a locking synchronization system with a thrust element, Figure 6 is a diagrammatic view of a synchronizing ring with the locking members and thrust elements distributed on the periphery, and Figure 7 is an axial section of a synchronizing ring showing the friction clutches.

As can be seen from Figs. 1 and 2, the locking synchronization system comprises a sliding sleeve 1 which is continuously connected rotationaily fast to a synchronizing body 2 via teeth 11,21.

The synchronizing body 2 is connected rotationally and axially fast to a shaft (not shown), preferably the output shaft, and carries locking members 3 in appropriate recesses. At least one gearwheel 5 is disposed on the synchronizing body 2 in an axially fixed but rotatable manner. A synchronizing ring 4 is disposed in recesses 22 of the synchronizing body 2 between the gearwheel 5 and the locking member 3 in such a manner that the working surfaces 42 of the frusto-conical projections 41 which project from the annular surface 43 of the synchronizing ring 4 in the direction of the locking member 3 can come into contact with the working surface 32 on the cone surface 33 of the member 3.The locking member 3 is spring-mounted at 37 in the radial direction and formed to have an inverted V-shape 38 externally with an angle of pitch a and projects into a correspondingly shaped milled groove 12 on the sliding sleeve 1. The two projections 41 of the synchronizing ring 4 which are associated with each locking member 3 enable a tangential relative movement of the synchronizing ring 4, which is arranged in such a manner with respect to the synchronizing body 2 and spaced such that actuation is locked in both end positions and released in the central position.

Figs. 3 and 4 are simplified representations and correspond in principle to Figs. 1 and 2, with the difference that the working surfaces 45 on the projections 41' of the synchronizing ring 4' and also the acting surfaces 35 facing the projections 41' of the locking member 3' are formed as an unparted hyperboloid.

Fig. 5 is an axial section, similar to Fig. 1, through a locking synchronization system, having a thrust element 6 and a synchronizing ring 4" which widens in the radial direction.

Fig. 6 shows how the locking members 3, 3' and the thrust elements 6 may be arranged on the periphery, for example three in each case, of the synchronization and also how the projections 41, 41' associated with the locking members 3, 3' may be arranged on the synchronizing ring 4, 4'.

Fig. 7 is an axial section through a synchronizing ring 4, 4' having a cone 46 as the surface of synchronization and a cone 42 as the working surface on the projection 41 - upper half -- and a disk synchronization -- disk carrier 47 - and an unparted hyperboloid 45 as the working surface on the projection 41' - lower half.

When the sliding sleeve 1 is moved axially, for example in the direction of the gearwheel 5, the locking member 3, 3' is pivoted in the same direction and becomes synchronized, cone 46 on the synchronizing ring 4 and cone 51 on the gearwheel contact each other readily. The path to synchronization may be substantially shortened and the time may also be reduced if the synchronization is effected via thrust elements 6 (Fig. 5), as in this case the axial path transfers the sliding sleeve almost completely to the synchronizing ring 4" as a result of the lower radial and axial spacing with respect to the synchronizing ring 4".

In the case of a different speed between the synchronizing body 2 - also the sliding sleeve 1, the locking member 3, the thrust element 6 and in principle also the synchronizing ring 4, 4', 4" - and the gearwheel 5, the synchronizing ring immediately carries out a relative movement in the peripheral direction to the position of the locking member 3, 3' and the working surfaces 32, 42 and 35, 45 come to bear against one another.

In this position the clutch actuating operation may not proceed further and is locked. As a result of further actuating pressure -- actuating power - on the sliding sleeve 1 in the axial direction, this actuating power is increased in accordance with the lever ratio sliding sleeve/point of rotation of the locking member and point of rotation of the locking member/contact surface of the acting surfaces, for example 32, 42 to synchronization. This is of particular advantage when the synchronization surfaces are formed as disks, as shown in Fig. 7. If thrust elements 6 are used, these may be inwardly deflected during this process and also later -- during continuation of the actuation -- in the radial direction.If synchronous running is achieved by this process, the actuating pressure becomes predominant the actuating force - and the locking member 3, 3' is forced radially inwardly, and the synchronous ring 4, 4' is simultaneously rotated in a tangential manner via the working surfaces, so that the locking members 3, 3' come to rest approximately in the middle of the projections 41,41'.

The sliding sleeve 1 may then produce with its teeth 11 the positive connection between the clutch teeth 21 of the synchronizing body 2 and the clutch teeth 53 of the gearwheel 5.

As may be readily seen, this actuating force is not only increased for the purposes of synchronization but also for the sliding over operation.

Whilst as a result of the angle of pitch (a) of the locking member 3, 3' and the contact geometry -- formation of the working surfaces on the locking member and the synchronizing ring a considerable effect may be exerted on the reinforcement, locking and sliding over effects, the springs 37, 67 are only required in principle for the radial return of the locking member 3, 3' and the pressure element 6 into the neutral position of the sliding sleeve 1.

The invention is not limited solely to the examples described and illustrated in Figs. 1 to 7.

For example, the shaping of the working surfaces, bearing in mind requirements, may be such that, for example, the central axis point of the projections 41 does not come to rest on the synchronizing ring 4, or the entire maximum diameter of the projections is substantially greater than the width of the synchronizing ring. This may arise particularly if the conditions of the wear adjustment must also be taken into account in the shaping of the working surfaces.

Claims

1. A locking synchronizing system for gear-shift transmission, in which two components disposed coaxially and rotating at different speeds, for example a synchronizing body and a gearwheel, are positively coupled together upon synchronous running by means of an axially displaceable, annular sliding sleeve, and in which internal clutch teeth of the sliding sleeve engage corresponding external clutch teeth of each of the two rotating components, with locking members which are radially guided and spring-loaded in the synchronizing body, these locking members engaging in an annular recess on the interior of the sliding sleeve and being axially displaceable, and with a synchronizing ring which is arranged axially between the two components and effects substantially the same movement of rotation with the synchronizing body, parts of the gearwheel forming a friction clutch together with parts of the synchronizing ring, characterised in that on the locking member disposed in the synchronizing body and on the synchronizing ring there is only one working surface for the transmission of an axial thrust force and a radial-tangential locking force in the case of non-synchronization.

2. A locking synchronizing system as claimed in claim 1, wherein the working surfaces on the locking member and on the synchronizing ring are curved.

3. A locking synchronizing system as claimed in claim 2, wherein the curved working surfaces are surfaces of rotation.

4. A locking synchronizing system as claimed in any of the preceding claims, wherein the working surfaces on the synchronizing ring are disposed to project on projections which are arranged on the annular surface which bears on the locking member and wherein two projections are associated with each locking member.

5. A locking synchronizing system as claimed in claim 4, wherein the projections on the synchronizing ring have the shape of a cone or the frustum of a cone.

6. A locking synchronizing system as claimed in claim 4, wherein the projections on the synchronizing ring have the shape of an unparted hyperboloid.

7. A locking synchronizing system as claimed in any of the preceding claims, wherein the outer surface of the locking member has the shape of the surface of a cone or an unparted hyperboloid in the direction of the projections of the synchronizing ring.

8. A locking synchronizing system as claimed in any of the preceding claims, wherein in addition to the locking members arranged in the synchronizing body and distributed about its periphery there are also provided thrust elements.

9. A locking synchronizing system as claimed in any of the preceding claims, wherein the synchronizing frictional clutch is a cone clutch.

10. A locking synchronizing system as claimed in any of claims 1 to 8, wherein the synchronizing friction clutch is a disk clutch.

11. A locking synchronizing system for gearshift transmission, substantially as herein described with reference to and as shown in the accompanying drawings.