Synchronizing ring

A synchronizing ring for a synchronizer of a transmission. The synchronizing ring is provided with a plurality of axially extending cams for engagement with a further synchronizing ring. An axial surface of each axial cam is provided with at least one groove for transportation of oil.

TECHNICAL FIELD

The invention relates to a synchronizing ring for a synchronizer of a transmission, which synchronizing ring is provided with a plurality of axially extending cams for engagement with a further synchronizing ring. In addition, the invention relates to a synchronizer for a vehicle transmission which synchronizer comprises such a synchronizing ring.

BACKGROUND

Transmissions usually have synchronizers for shifting gears. For example, an idle gear wheel that is journaled on an output shaft and engaged with a gear wheel arranged on an input shaft, can be connected to the output shaft by a synchronizer. The synchronizer has a sleeve that is brought into engagement with a dog ring of the idle gear wheel by means of teeth. The sleeve is connected to a hub by means of a spline joint. The hub is in turn rotationally locked relative to the output shaft. Thus, when the sleeve and the dog ring are engaged, the idle gear wheel and the output shaft are rotationally locked relative to each other via the synchronizer and torque can be transferred.

When shifting gears, before displacement of the sleeve for engaging the dog ring, the rotation speeds of the idle gear wheel and the sleeve have however to be synchronized.

For this reason, friction rings can be used, and particularly an inner ring can be arranged inside of a blocking ring used for pre-synchronization in a synchronizer. Such an inner ring for a multi-cone synchronizer, has axially extending cams for engagement with the blocking ring. The cams are received by corresponding recesses of the blocking ring.

SUMMARY

An objective of the invention is to provide a synchronizing ring for improving lubrication of the synchronizer.

The objective is achieved by a synchronizing ring for a synchronizer of a transmission, wherein the synchronizing ring is provided with a plurality of axially extending cams for engagement with a further synchronizing ring, and wherein an axial surface of each axial cam is provided with at least one groove for transportation of oil.

The invention is based on the insight that a small gap formed between the axial surfaces of the axial cams of the synchronizing ring and a component such as a hub of the synchronizer, may under unfavourable conditions lead to oil being stuck in the gap and dried oil is sticking on the component. Said at least one groove arranged in the axial cams will eliminate or at least reduce such a problem by providing an improved circulation of oil in the synchronizer.

The axial surface of each axial cam is preferably provided with a plurality of grooves for transportation of oil.

According to one embodiment, each groove has an extension direction in the radial extension direction of the synchronizing ring, and preferably the length of each groove is equal to the extension of the corresponding axial cam in the radial extension direction of the synchronizing ring. Hereby, oil can be transported from the axial surface in an area between an outer radial surface and an inner radial surface of the axial cam, thereby increasing the circulation of oil in the synchronizer.

Each axial cam can have 2-20 grooves, preferably 3-10 grooves and more preferably 4-8 grooves, for drainage of oil from the gap. The cross section area of each groove can be in the interval 0.5-20 mm2, preferably 1-15 mm2and more preferably 2-10 mm2. For example, the cross-section of each groove can be semi-circular with a diameter in the interval 2-8 mm, preferably 3-6 mm.

The synchronizing ring can be an inner ring to be arranged inside the further synchronizing ring being an external ring. The synchronizing ring can have a conical shape with an outer radial surface for interacting with an intermediate friction ring of the synchronizer.

For example, the synchronizing ring can be an inner ring for a synchronizer which inner ring interacts with an intermediate ring and an external blocking ring of the synchronizer for pre-synchronization when a sleeve is displaced for shifting gears.

The synchronizer can be a multi-cone synchronizer, such as double or triple cone synchronizer.

The features of the invention can be advantageously used when the synchronizing ring has two or more axial cams. The synchronizing ring can have a number of axial cams being a multiple of 3 for instance. The number of axial cams is often in the interval 3-9.

Each axial cam can have two main extension directions; one first main extension direction in the circumferential direction of the synchronizing ring and a second main extension direction in the axial direction of the synchronizing ring. In addition, a third extension direction of the axial cam, i.e. the thickness, is in the radial direction of the synchronizing ring. The axial surface defined by the extension in the circumferential direction and the extension in the radial direction is often arranged with a small gap relative to an axial surface of a synchronizer hub, since the packing space is limited.

Due to the relatively large total area of the axial surfaces of the axial cams, it has been found out that the grooves can improve the lubrication to a significant extent.

According to another aspect of the invention, a further objective is to provide a synchronizer for a vehicle transmission enabling improved lubrication.

This objective is achieved by a synchronizer comprising a synchronizing ring, a component and a further synchronizing ring, wherein the synchronizing ring is provided with a plurality of axially extending cams received by a plurality of recesses of the further synchronizing ring, and wherein an axial surface of each axial cam is provided with at least one groove for transportation of oil from a gap formed between the axial surface of each axial cam and the component.

The advantages of the synchronizer are similar to the advantages already discussed hereinabove with reference to the different embodiments of the synchronizing ring.

DETAILED DESCRIPTION

FIG.1is a cut view of a transmission1having a synchronizer2. The synchronizer2can be used to rotationally lock a first gear wheel3and a second gear wheel4to a shaft5of the transmission1. For this purpose the synchronizer2has a displaceable sleeve6arranged on a hub7. InFIG.1the sleeve6is positioned in a neutral position. If the sleeve6is moved from the neutral position in an axial direction8of the synchronizer2towards the first gear wheel3, the sleeve6will engage a dog ring9of the first gear wheel3and thereby lock the first gear wheel3to the shaft5. If instead the sleeve6is moved in the axial direction8towards the second gear wheel4, the sleeve6will engage a clutch cone ring10and thereby lock the second gear wheel4to the shaft5.

The synchronizer2comprises a synchronizing ring11, a component7and a further synchronizing ring12. The synchronizing ring11is provided with a plurality of axially extending cams13. The further synchronizing ring12is provided with radially extending cams15and corresponding recesses14between the cams15for receiving the axial cams13of the synchronizing ring11. The synchronizing ring11can have a conical shape and be provided with an outer surface16for interaction with an intermediate friction ring17.

An axial surface18of each axial cam13is provided with at least one, preferably a plurality of grooves19for transportation of oil from a gap20formed between the axial surface18of each cam13and the component7. By axial surface is meant a surface faced in the axial direction8or the longitudinal direction of the synchronizing ring11. Each groove19forms a channel for transportation of oil. The component is here the hub7on which the sleeve6is arranged. The gap20is formed between the axial surface18of the axial cam13and an opposing axial surface21of the hub7. The grooves19of the synchronizing ring11will be further described hereinafter with reference to further figures. The synchronizing ring11is an inner ring arranged inside of the further synchronizing ring12being an external blocking ring and inside of the intermediate friction ring17.

FIGS.2A and2Bare enlarged views of parts of the synchronizer2inFIG.1. In addition to the dog ring9and the hub7, friction or synchronizing rings are shown. In the example embodiment illustrated inFIG.1, the synchronizer2is a double-cone synchronizer. The synchronizer2has the external synchronizing ring12, the intermediate synchronizing ring17and the inner synchronizing ring11. The external synchronizing ring will also be referred to as the further synchronizing ring12or blocking ring. The inner synchronizing ring will also be referred to as the synchronizing ring11or inner ring. When the sleeve6is initially moved towards the first gear wheel3, the blocking ring12will be contacted by one or more struts (not shown) of the synchronizer2for pre-synchronization. Each strut is arranged on the hub7and can be displaced in the axial direction8relative to the hub7together with the sleeve6for engagement with the blocking ring12.

InFIG.2A, one said axial cam13of the inner ring11received in one said recess14of the blocking ring12is illustrated, whereas inFIG.2Bone said radial cam15of the blocking ring12is illustrated. The axial cam13inFIG.2Ais illustrated with one of said plurality of grooves19for enabling transportation of oil from the gap20formed between the axial surface18of the axial cam13and the axial surface21of the hub7.

In the cut perspective view of the synchronizer2shown inFIG.2C, the synchronizing ring11provided with the axial cam13with the axial surface18having the grooves19is illustrated. One axial cam13of the inner ring11received by a recess14of the further synchronizing ring12is illustrated on each side of the radial cam15of the further synchronizing ring12. Further, a recess23of the dog ring9receiving an axial protrusion24of the intermediate ring17is shown. The hub7with splines25for connection to the shaft5and the sleeve6arranged on the hub7are also illustrated.

InFIGS.3A,3B and3Cthe synchronizing ring11is illustrated more in detail.FIG.3Ais a perspective view of the synchronizing ring11,FIG.3Bis a front view andFIG.3Cis a side view of the synchronizing ring11.

FIG.3Ais a perspective view showing the axially extending cams13of the synchronizing ring11. The synchronizing ring11has a ring portion31which is provided with the plurality of axial cams13for engagement with the further synchronizing ring12(seeFIG.1). The axial cams13are to be received by the corresponding recesses of the further synchronizing ring12. The axial surface18of each axial cam13is provided with the plurality of grooves19for transportation of oil. The grooves19can be used for transportation of oil from the gap20formed between the axial surface18of each axial cam13and a component7of the synchronizer2, such as the hub7, when the synchronizing ring11is installed in the synchronizer2.

Each axial cam13has suitably two main extension directions, one first main extension direction in a circumferential direction27of the synchronizing ring11and a second main extension direction in an axial direction28or longitudinal direction of the synchronizing ring11. This direction is in parallel with the axial direction8of the synchronizer2when the synchronizing ring11is installed in the synchronizer2. In addition, each axial cam13has a third extension direction or thickness in a radial direction29of the synchronizing ring11. This direction is in parallel with a radial direction of the synchronizer2when the synchronizing ring11is installed in the synchronizer2.

Each groove19can have a longitudinal extension direction in parallel with the radial extension direction29of the synchronizing ring11. The length of each groove19is preferably equal to the extension of the axial cam13in the radial extension direction29of the synchronizing ring11. Hereby, each groove forms a channel extending from one side of the cam to another side of the cam or in other words; from an outer radial surface22of the axial cam13to an inner radial surface26of the axial cam13.

Although the example embodiment of the synchronizing ring11illustrated inFIG.3Ahas three axial extending cams13, the number of axial cams13(and corresponding recesses30therebetween) can of course be different for other synchronizing rings. The synchronizing ring11has preferably a number of axial cams13being a multiple of 3, and often the synchronizing ring11has a number of cams in the interval 3-9.

For an increased circumferential length and/or radial extension of the axial cams13, the need of the grooves19will increase. Often the total circumferential length of the axial cams13and the thickness of the axial cams13have dimensions resulting in a not negligible area (defined by the axial surfaces18of the axial cams13) where the axial cams13and the hub7overlap and thereby form the gap20(seeFIG.2A). For example, the total circumferential length of the axial cams13is often at least equal to the total circumferential length of the recesses30between the axial cams13, and it has been found out that the grooves19can improve the lubrication to a significant extent.

Each axial cam13can have 2-20 grooves, preferably 3-10 grooves and more preferably 4-8 grooves. Of course, in addition to the number of grooves19also the size of the grooves, i.e. the cross-section dimensions, and the shape of the grooves, can be varied and adapted to the current application.

As illustrated in the example embodiment shown inFIGS.3A,3B and3C, each axial cam13can have six grooves19arranged on the axial surface18where each groove19has a length corresponding to the radial extension or thickness of the axial cam13, and each groove19has a semi-circular cross section.

The outside of the synchronizing ring11is suitably provided with a surface16for interacting with an intermediate ring17(seeFIG.1). This outer surface16of the ring portion31of the synchronizing ring11can be conical relative to the longitudinal extension direction28or axial direction of the synchronizing ring11.