GB2357815A

GB2357815A - A synchronising ring made by superimposed moulding

Info

Publication number: GB2357815A
Application number: GB0031584A
Authority: GB
Inventors: Erick Duno; George Skotnicki; Kenneth Birch
Original assignee: Valeo SE
Current assignee: Valeo SE
Priority date: 1999-12-27
Filing date: 2000-12-22
Publication date: 2001-07-04
Anticipated expiration: 2020-12-22
Also published as: GB0031584D0; GB2357815B; DE10063053A1; FR2802996B1; FR2802996A1

Abstract

A synchronising ring 10 comprises an annular body 12 having a frusto-conical internal friction surface 14. The body 12 consists of an annular driving crown 16 with coaxial second crown 18 attached to it on one side by superimposed moulding of a non-metallic material on a metal disc 20 that constitutes the driving crown 16. The non-metallic material may be plastics, ceramic, an reinforced organic resin, or an organic material. Friction surface 14 may be coated with a plastics material 32 having a set of axial grooves. In manufacturing the second crown 18 and friction surface 14 are moulded at the same time. The second crown 18 is an engagement and positioning crown which has external engagement and axial positioning bosses 26 and the driving crown 16 has external drive teeth which cooperate with teeth on, for example, a roving sleeve.

Description

2357815 A SYNCHRONISING RING FOR A GEARBOX SYNCHRONISER This invention

relates to synchronising rings for gearbox synchronisers, and more particularly to a synchronising ring for a gearbox synchroniser comprising a generally annular body defining a frusto- conical internal working surface, which is adapted to cooperate by friction with a complementary working surface of another component, the said frusto-conical annular body comprising a first portion and a second portion disposed side by side axially, the said first portion defining a driving crown of the synchronisation ring, and the said io second portion being a crown for engagement and positioning of the synchronising ring.

Such a synchronising ring is described for example in European patent publication No. EP 0 821 175, to which reference is invited for more detail.

In a multiple ratio gearbox, during gear changes, the synchronism necessary between the roving sleeve, which rotates at the velocity of the output shaft, and the corresponding gear wheel is obtained by means of a synchronisation system operating by friction.

In one known example of a design of synchronising device, the latter is equipped with a hub or sleeve which is splined to the secondary shaft. The roving sleeve is arranged to slide axially on this hub. The hub is provided on each side with a synchronising sleeve which, for example, comprises an internal friction cone. The cone of the sleeve and the complementary external cone of the gear wheel together constitute a conical coupling which gives, by friction, the required synchronism, that is to say the driving of the idle gear wheel for the purpose of engaging the corresponding gear speed.

2 The teeth and friction surfaces of the meshing components are mad of treated steel, and they are for example coated with molybdenu In one known design of synchronising rings, they are made in the for of solid metal elements which are machined, the internal cones an the annular rings being for example of bronze, aluminium alloy or sintered steel.

This design of a solid, one-piece, synchronising ring has a number o disadvantages. First, each ring is relatively heavy and has a relativel high inertia. Second, manufacture of the synchronising rings b io machining calls for numerous steps of repeated machining, and i particularly long and costly. Finally, the rigidity necessary for eac synchronisation ring gives no scope for reduction in its dimensions an weight.

The invention aims to overcome the above mentioned drawbacks.

According to the invention, in a synchronising ring for a gearbo synchroniser, comprising a generally annular body defining a frusto. conical internal working surface which is adapted to cooperate by friction with a complementary working surface of another component the said frusto conical annular body comprising a first portion and second portion disposed side by side axially, the said first portio defining a driving crown of the synchronisation ring, and the sai second portion being a crown for engagement and positioning of th synchronising ring, the driving crown consists of a metallic disc, th engagement and positioning crown being formed by superimpose moulding of a non-metallic compound on the driving crown.

With this arrangement, there is no need to provide seaming or "reldin operations to join the engagement and positioning crown to the drivinj 3 crown, so that the solution is both simple and inexpensive, and reduces the weight of the ring. Moreover, the driving crown has good mechanical strength against the stresses imposed on it in operation.

As compared with what is disclosed in European published patent specification No. EP 0 821 175A, the operations for forming a sheet metal component are avoided.

Preferably, the said non-metallic compound is a plastics material.

Preferably, the said working surface is at least partly coated with a layer of material.

io Preferably, the said working surface has a set of substantially axial grooves formed by moulding within the thickness of the said layer of material.

Preferably, the said layer of material on the working surface is of plastics material.

Preferably, a layer of plastics material on the working surface is moulded at the same time as the formation of the engagement and positioning crown.

Preferably, the said non-metallic compound is a plastics material, the engagement and positioning crown and the layer of plastics material on the working surface being moulded in the same plastics material.

Preferably, the non-metallic compound is a plastics material, the plastics layer on the working surface being co-moulded with the engagement and positioning crown.

Preferably, the material covering the working surface is a friction material.

4 Preferably, the layer of friction material is applied on the working surface by superimposed moulding.

Preferably, the driving crown has external drive teeth adapted t cooperate with complementary teeth, for example a roving sleeve.

Preferably, the engagement and positioning crown includes externol engagement and axial positioning bosses formed by moulding.

The invention enables the thickness of the driving crown to b controlled.

Further features and advantages of the invention will appear on a io reading of the following detailed description of a preferred embodiment of the invention, which is given by way of non-limiting example onh( and with reference to the accompanying drawings, in which:

- Figure 1 is a three-quarter front perspective view showing synchronising ring incorporating features of the invention; and - Figure 2 is a scrap view on a larger scale showing part of the sam4 synchronising ring in axial cross section.

In this description, those elements and components which are identica or similar or analogous to each other will be designated by the sam reference signs.

The synchronising ring is indicated at 10, and it consists essentially ol a generally annular body 12, having a central axis X-X and defining E frusto-conical internal working surface 14.

The annular body 12 consists of a first portion in the form of a crowr 16 for driving the synchronising ring 10, and a second portion def ininQ a crown 18 for engagement and axial positioning of the ring 10. Th driving crown 16 in this example is in the form of an annular disc 20, the circular outer edge 22 of which includes drive teeth 24. The annular disc 20 is made of metal and is of the same type as is conventionally used in synchronising rings. It is for example made of bronze, aluminium alloy or sintered steel, and is manufactured by a conventional manufacturing technique, for example hot forging, sintering or press-forming and stamping.

The crown 16 therefore has a good strength against the stresses imposed on it, in particular in the region of its teeth.

io The engagement and positioning crown 18 extends axially from an axial end face of the annular disc 20. This crown 20 includes, on its outer peripheral edge 28, bosses 26 for engagement and axial positioning of the ring 10. In this example there are three of these bosses, which are spaced apart circumferentially at regular intervals.

The engagement and positioning bosses 26 are, in particular, formed integrally with the engagement and positioning crown 18. The latter also includes, again on its outer peripheral edge 28, positioning notches 30 between the bosses 26. The notches 30 are formed by moulding, and in this example there are three of these notches, spaced apart circumferentially at regular intervals.

The engagement and positioning crown 18 is made by superimposed moulding of a non-metallic compound on the driving crown 16.

This non-metallic compound is preferably a plastics material, or a ceramic, or a reinforced organic resin, or an organic material. The 2s bosses 26 and notches 30 are easily formed, and the material of the crown 18 is well adapted to its function.

6 Figure 2 shows that the engagement and positioning crown 18 can b formed by superimposed moulding in the extension of the intern 1 t peripheral edge 27 of the driving crown 16, so that the internal frus conical working surface 14 is bounded at the same time by the inner peripheral edge 29 of the engagement and positioning crown 18, an by the inner peripheral edge 27 of the driving crown 16.

In another version, not shown, of a synchronising ring incorporatinil features of the invention, the engagement and positioning crown 18 i formed by superimposed moulding on the inner peripheral edge 27 of lo the driving crown 16 in such a way that the frusto-conical internal working surface 14 is defined only by the inner peripheral edge 29 of the engagement and positioning crown 18.

It will be noted that axial retention and rotational retention of th crown 18 on the crown 16 may be achieved in any known way used in superimposed moulding methods. For example, the driving crown 16 may include lugs of any suitable form, extending axially towards the engagement and positioning crown 18. When the crown 18 i moulded over the driving crown 16, the moulding material envelop these lugs so that the latter can then retain the moulded part bot axially and against rotation.

In another example, the driving crown 16 includes notches of suitabl 1 i form for receiving the moulding material, thereby retaining the crow 18 axially and against rotation with respect to the driving crown 16.

In yet another example, the axial end face of the driving crown 16 that receives the engagement and positioning crown 18 may be so treated as to give adhesive bonding of the crown 18 on it, so as to secure the crown 18 axially and against rotation relative to the crown 16.

7 The frusto-conical internal working surface 14 is preferably coated with a layer 32 of a suitable material such as a friction material. This friction coating 32 may for example be formed by superimposed moulding on the inner peripheral surface 29 of the engagement and positioning crown 18.

The precise geometry of the frusto-conical surface 14 is obtained in the moulding process, that is to say it does not depend on the accuracy with which the annular body 12, which constitutes an insert in the mould, is made. On the contrary, the geometry of the surface io 14 depends only on the precision of the mould itself.

The material of the layer 13 must be capable of working in oil. An example of a friction material and its method of manufacture is disclosed in published international patent specification W095/26473.

In order to improve the bonding of the friction layer moulded on the annular body 12, a preliminary coating of a resin may be deposited, on the body 12 or on the friction material, before the superimposed moulding operation takes place. The deposit can be carried out by immersing the annular body 12 in a resin bath, or by projecting the resin on the frustoconical working surface 14, or by any other suitable coating method, for example by rolling.

As is known for friction cones, the frusto-conical working surface 14 may be formed with a set of substantially axial grooves 34. In this example, the grooves are, with advantage, formed integrally by moulding with the friction layer 32.

In another modification, not shown, the internal frusto-conical working surface 14 is coated with a layer of plastics material. This plastics layer may be moulded in position at the same time as the engagement and positioning crown 18, and may for example be in the sa plastics material. Alternatively, it may be formed by co-moulding wit the crown 18, in a different plastics material.

Holes or openings or notches may be formed in the driving crown 1 5 to improve the anchorage of the crown 18.

The synchronisation ring 10 can be made very inexpensively. Its mas and its inertia are greatly reduced as compared with synchronisatio rings of known solid, one-piece types, and it can be made without th, need for any machining operation.

io The crown 18 is of a material well suited to its function, while th driving crown 16 may be made with the desired thickness, especiall when the material of the frusto-conical working surface 14 is coate with a material 32 which is different from that of the crowns 16 an 18.

9

Claims

1. A synchronising ring for a gearbox synchroniser, comprising a generally annular body defining a frusto-conical internal working surface which is adapted to cooperate by friction with a 5 complementary working surface of another component, the said frusto-conical annular body comprising a first portion and a second portion disposed side by side axially, the said first portion defining a driving crown of the synchronisation ring, and the said second portion being a crown for engagement and positioning of the synchronising io ring, wherein the driving crown consists of a metallic disc, the engagement and positioning crown being formed by superimposed moulding of a non-metallic compound on the driving crown.

2. A synchronising ring according to Claim 1, wherein the said nonmetallic compound is a plastics material.

3. A synchronising ring according to Claim 1 or Claim 2, wherein the said working surface is at least partly coated with a layer of material.

4. A synchronising ring according to Claim 3, wherein the said working surface has a set of substantially axial grooves formed by moulding within the thickness of the said layer of material.

5. A synchronising ring according to Claim 3 or Claim 4, wherein the said layer of material on the working surface is of plastics material.

6. A synchronising ring according to Claim 5, wherein a layer of plastics material on the working surface is moulded at the same time as the formation of the engagement and positioning crown.

7. A synchronising ring according to Claim 6, wherein the said normetallic compound is a plastics material, the engagement and positioning crown and the layer of plastics material on the workini 3 surface being moulded in the same plastics material.

8. A synchronising ring according to Claim 6, wherein the nonmetallic compound is a plastics material, the plastics layer on the working surface being co-moulded with the engagement ano positioning crown.

9. A synchronising ring according to Claim 3 or Claim 4, wherein th io material covering the working surface is a friction material.

10. A synchronising ring according to Claim 9, wherein the layer o friction material is applied on the working surface by superimposeo moulding.

11. A synchronising ring according to any one of the precedin Claims, wherein the driving crown has external drive teeth adapted t cooperate with complementary teeth, for example a roving sleeve

12. A synchronising ring according to any one of the precedin( Claims, wherein the engagement and positioning crown include., external engagement and axial positioning bosses formed by moulding, 13 A synchronising ring substantially as herein described wit reference to and as shown in the accompanying drawings