GB2113781A

GB2113781A - Synchronizer ring for transmission

Info

Publication number: GB2113781A
Application number: GB08201775A
Authority: GB
Inventors: Peter Powell
Original assignee: Ewarts Ltd
Current assignee: Ewarts Ltd
Priority date: 1982-01-22
Filing date: 1982-01-22
Publication date: 1983-08-10

Abstract

The ring comprises a single unitary and integral body of thermoplastic or thermosetting plastics material. Also disclosed is an all-plastics ring comprising inner and outer parts made of different plastics materials, wherein one part may be moulded onto the other, or the parts may be moulded separately and bonded, and a ring comprising an inner metal part and an outer plastics part.

Description

SPECIFICATION A synchroniser ring for a transmission synchromesh device This invention relates to a synchroniser ring, otherwise known as a baulk ring for a synchromesh device of the kind used in vehicle gear boxes, for example.

Known synchromesh devices or synchroniser rings have frusto conical slide surfaces adapted to be in slidable contact with complementary frusto conical slide surfaces of the (steel) gears. The synchroniser rings are therefore made of brass or bronze so as to minimise wear. Sometimes they are castings and sometimes they are hot pressings. They are inevitably expensive.

Various attempts have been made to reduce the costs for example by making them thinner, which tends to lead to problems in operation.

It has also been suggested to make the synchroniser ring of a very thin metal component with a synthetic resin moulded integrally and externally of the metal ring. This proposal is contained in British Patent Application No. 2030660.

The objects of the invention are to provide improvements and in particular to provide alternatives to the arrangements suggested in said patent application but which possess like, similar or even further advantages.

In accordance with a first aspect of the present invention, a synchroniser ring is made from a single unitary and integral plastics body.

Such a ring may be made by a heat-forming process of thermoplastic or thermo-setting material, in one example using injection moulding, in matching mould components.

According to a second aspect of the invention, an all plastics synchroniser ring comprises radially inner and outer parts made of different plastics materials.

According to a feature of this second aspect of the invention, the two plastics materials are joined together by a bonding or like process including the possibility of moulding a second of the components to a preformed moulding of the first of the components. This enables plastics materials having different characteristics to be used for the inner and outer parts, so that the required specification of material for different purposes can be selected without compromise.

According to an alternative feature of this second aspect, two plastics components may be formed separately and joined together by a mechanical keying process, made as a push-fit one with the other, joined together by an adhesive, by high frequency welding or by other techniques.

According to another (and third) aspect of the invention, the inner part of a synchroniser ring is made of metal and the outer part of plastics, and the two are rendered angularly fast with one another and preferably additionally axially fast with one another by any convenient means other than integrally moulding the plastics to the metal.

One possibility for this last mentioned aspect is to key the parts together by providing radially extending lugs and recesses on the two parts.

Another alternative is to use an adhesive or bonding method.

According to any of the alternatives, where two components are required, instead of using adhesives or high frequency welding, alternative welding methods may be provided and the parts may instead or additionally be made as an interference fit with one another and possibly additionally arranged so that they snap together.

Yet another possibility in this direction allows for hot mouldings direct from their forming process to be assembled to cold (or possibly into chilled) components possibly as a push fit, and so that when the two have reached a common temperature they will be interference fitted together as a result of the normal contraction and expansion of the parts.

Where metal is used, almost any particular metal may be found satisfactory. The resin may be a nylon or a thermoplastic polyester, and the resin may be reinforced for example by glass fibre, aramid, carbon fibre or any other reinforcing agent or any combination of reinforcing agents.

1. A synchroniser ring for a synchromesh device of the kind used in vehicle gear boxes characterised in that it consists of a single unitary and integral plastics body.

2. A ring as claimed in Claim 1 made by a heat forming process and from a thermoplastic material.

3. A ring as claimed in Claim 1 made by a heat forming process and from a thermo-setting material.

4. A synchroniser ring for a synchromesh device of the kind used in vehicle gear boxes characterised in that it consists of an all plastics ring comprising radially inner and outer parts made of different plastics materials.

5. A ring as claimed in Claim 4 wherein the two materials are joined together by a bonding or like process.

6. A ring as claimed in Claim 4 wherein the two plastics materials are joined together by moulding the second of the components to a preformed first moulded component.

7. A ring as claimed in Claim 4 comprising two different plastics components formed separately and joined together.

8. A synchroniser ring for a synchromesh device of the kind used in vehicle gear boxes comprising radially inner and outer parts, the inner part being of metal and the outer part of plastics,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION A synchroniser ring for a transmission synchromesh device This invention relates to a synchroniser ring, otherwise known as a baulk ring for a synchromesh device of the kind used in vehicle gear boxes, for example. Known synchromesh devices or synchroniser rings have frusto conical slide surfaces adapted to be in slidable contact with complementary frusto conical slide surfaces of the (steel) gears. The synchroniser rings are therefore made of brass or bronze so as to minimise wear. Sometimes they are castings and sometimes they are hot pressings. They are inevitably expensive. Various attempts have been made to reduce the costs for example by making them thinner, which tends to lead to problems in operation. It has also been suggested to make the synchroniser ring of a very thin metal component with a synthetic resin moulded integrally and externally of the metal ring. This proposal is contained in British Patent Application No. 2030660. The objects of the invention are to provide improvements and in particular to provide alternatives to the arrangements suggested in said patent application but which possess like, similar or even further advantages. In accordance with a first aspect of the present invention, a synchroniser ring is made from a single unitary and integral plastics body. Such a ring may be made by a heat-forming process of thermoplastic or thermo-setting material, in one example using injection moulding, in matching mould components. According to a second aspect of the invention, an all plastics synchroniser ring comprises radially inner and outer parts made of different plastics materials. According to a feature of this second aspect of the invention, the two plastics materials are joined together by a bonding or like process including the possibility of moulding a second of the components to a preformed moulding of the first of the components. This enables plastics materials having different characteristics to be used for the inner and outer parts, so that the required specification of material for different purposes can be selected without compromise. According to an alternative feature of this second aspect, two plastics components may be formed separately and joined together by a mechanical keying process, made as a push-fit one with the other, joined together by an adhesive, by high frequency welding or by other techniques. According to another (and third) aspect of the invention, the inner part of a synchroniser ring is made of metal and the outer part of plastics, and the two are rendered angularly fast with one another and preferably additionally axially fast with one another by any convenient means other than integrally moulding the plastics to the metal. One possibility for this last mentioned aspect is to key the parts together by providing radially extending lugs and recesses on the two parts. Another alternative is to use an adhesive or bonding method. According to any of the alternatives, where two components are required, instead of using adhesives or high frequency welding, alternative welding methods may be provided and the parts may instead or additionally be made as an interference fit with one another and possibly additionally arranged so that they snap together. Yet another possibility in this direction allows for hot mouldings direct from their forming process to be assembled to cold (or possibly into chilled) components possibly as a push fit, and so that when the two have reached a common temperature they will be interference fitted together as a result of the normal contraction and expansion of the parts. Where metal is used, almost any particular metal may be found satisfactory. The resin may be a nylon or a thermoplastic polyester, and the resin may be reinforced for example by glass fibre, aramid, carbon fibre or any other reinforcing agent or any combination of reinforcing agents. CLAIMS

8. A synchroniser ring for a synchromesh device of the kind used in vehicle gear boxes comprising radially inner and outer parts, the inner part being of metal and the outer part of plastics, characterised in that the two parts are made separately and subsequently joined together and rendered angularly fast with one another.

9. A ring as claimed in Claim 8 in which the parts are additionally rendered axially fast with one another.