GB2149864A

GB2149864A - Friction coupling

Info

Publication number: GB2149864A
Application number: GB08429227A
Authority: GB
Inventors: Paul Cornelis
Original assignee: OUDEN W H DEN NV; W H den Ouden NV
Current assignee: OUDEN W H DEN NV; W H den Ouden NV
Priority date: 1983-11-17
Filing date: 1984-11-19
Publication date: 1985-06-19
Also published as: NL8303950A; GB8429227D0; DE3441557A1; GB2149864B; FR2555267A1

Abstract

Friction coupling, in particular for application between a combustion engine and a reversing gear, said coupling comprising at least one axially shiftably friction ring 19, 20 and an annular disc 18 and sealing ring 27, 28 cooperating with this for engaging and disengaging the ingoing and outgoing shifts 5, 11 of the coupling, sealed areas 21, 31, 22, 32 being formed between the friction ring, sealing ring and annular disc to which area a pressure medium can be supplied for engaging and disengaging the coupling, the coupling being maintained in engaged position by roller elements being positioned between inclined slanting faces in opposed end faces of the friction ring and the annular disc. A control valve 55 and further valve means in the disc 18 control the pressure medium and prevent excessively fast changes between forward and reverse. <IMAGE>

Description

SPECIFICATION Friction coupling The invention relates to a friction coupling, in particular for application between a combustion engine and a reversing gear, said coupling comprising at least one axially shiftable friction ring on a shaft to be coupled, which is rotatably resting against an annular disc, fitted on the shaft to be coupled, by means of roller elements, said roller elements being positioned between inclined faces, slanting with respect to opposing end faces of the friction ring and the annular disc, means being provided for axial shifting of the friction ring for engaging and disengaging the coupling.

Such a friction coupling is described in Dutch patent specification Nr. 157,970. In this known coupling the means for axial shifting of the friction ring is formed by a coupling sleeve which extends annularly around the annular disc mounted on the shaft to be driven. The coupling sleeve is provided with a groove over its circumference into which fits a coupling fork, which is shiftably guided in an axial direction and maybe operated by a levertransmission.

Since the coupling fork is only shiftable in an axial direction, considerable friction forces will be generated in particular while operating the coupling. Accordingly the operation of the coupling demands a considerable effort.

It has been attempted to obviate this disadvantage by a hydraulic construction of the coupling. With such a coupling, however, it is required that during the total time of activation of the coupling the used medium is being maintained under pressure. This requires considerable energy, thus the efficiency of such a coupling being low especially when less energy has to be transmitted.

The invention provides a friction coupling, wherein the friction ring, shiftable over the shaft on the one side, is sealed off at the inner circumference with respect to the shaft and on the other side is sealed off at an axial face, located at a distance from the inner circumference, with respect to the annular disc for forming a sealed first area between the opposed end faces of the friction ring and the annular disc, to which area a pressure medium can be supplied for activating the coupling, while opposite the other end face of the friction ring a sealing ring is mounted on the shaft, which is supported in such a manner with respect to the shaft that it can not move away from the friction ring, said sealing ring being sealed at the inner circumference with respect to the shaft and at the outer circumference with respect to the friction ring or a press ring connected therewith, in such a manner that between the sealing ring and the friction ring a second sealed area is formed to which a pressure medium can be supplied for disengaging the coupling, channels being present in the shaft for the supply and discharge of the pressure medium to the areas formed by means of a stationary positioned control valve, valve means being positioned in the annular disc allowing to make a connection between the supply and discharge channels for the pressure medium after an activating of the coupling has taken place.

Thus in essence a friction ring forms a piston of a double acting pressure medium cylinder, thus allowing to exert a considerable force on the piston without causing problems for the operator.

The pump delivering the pressure medium can be driven by the ingoing shaft of the coupling, as this is also done in the known hydraulically operated couplings, described above. In the immediate vicinity of the pump the control valve may also be incorporated into the stationary part of the coupling, allowing optional supply of pressure medium to a specific area.

By incorporating the valve means as described above into the annular disc it is warranted that the medium provided by the pump will have to be under full pump pressure only when the coupling is operated. Immediately after the coupling has been brought to the desired position the medium does not need to be under full pump pressure any more and the pump will only make the medium to circulate. Though this does require some power, this power is only small with respect to the hydraulically functioning coupling described above.

According to a preferred embodiment of the invention the valve means are formed by bores provided in the annular disc, which are mainly radially extending, in each bore a pistion being present which is pressed outwardly by a spring and/or by the pressure medium used against the inner circumference of a control ring rotating together with the friction ring, said control ring being provided with a number of recesses corresponding with the number of pistons and positioned such that, making use of the limited angular rotation occurring between the friction ring and the shaft to be coupled while bringing the coupling in a desired specific position, always one of the pistons is shoved outwardly into the corresponding recess by which a connection is achieved between the supply line used for pressure medium and the suction side of the pump.

According to a further elaboration of the invention it is provided, that from the inner end of each piston an axially extending channel is made therein, continuing in a radially extending channel ending in the piston wall at such a location, that this channel is set free from the bore, in which the piston is present, when the piston is pressed into the corresponding recess.

The embodiment may be such, that when supplying medium to an area in order to bring the coupling into the neutral position, pressure medium is simultaneously supplied to the axial channel of that piston, which is pressed into the corresponding recess when the coupling has reached its neutral position, whereas with supply of pressure medium to said area whereby the coupling is brought into an engaged position, medium is simultaneously supplied to a channel provided in an axial direction in the annular disc and emerging against the piston which is shoved into the corresponding recess after bringing the coupling in the engaged position, during which movement the channel is set free for achieving a connection between this channel and the initially axially and subsequently radially extending channel through the piston.

This means that during bringing the coupling into an engaged position, which may require a high pressure of the medium, a double sealing of the discharge channel is present because the channel, in which the medium stands under pressure, is not directly connected with the channel made in the piston but is closed by the wall of the piston and is only set free when the piston is moving outwardly.

In order to prevent that the coupling is moved from an operating position to the neutral position and subsequently again to the same of another operating position, it can be provided, that when moving the control valve of the coupling to the neutral position, the control valve is blocked by the pressure builtup of the operating medium, until the relevant valve means, present in the annular disc, has ensured that a connection between the relevant supply channel for the pressure medium and the suction side of the pump is achieved such that the pump pressure has decreased to the circulation pressure.

In this way it is achieved, that a subsequent activation of the coupling can take place only after the coupling positively has acquired the neutral position. Thus damage to the coupling by a too sudden switching will be prevented, whereas the operational pressure of the oil pump can be restricted as well.

In that context special thought is given of course to switching of the coupling from forward to backwards, thus to a reversal of the direction of rotation of the shaft to be coupled.

According to a preferred embodiment of the invention blocking of the control valve will occur by a pin, which has been incorporated as a piston in a cylinder and which, by the pressure of the medium, may be pressed into a recess in the control valve so firmly that the control valve can not be operated.

As will be evident, the coupling described above will be applicable in particular for driving of a shaft to be coupled in opposed directions, having on either side of the annular disc a friction ring functioning as a piston.

and three valve means in total being present in the annular disc.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, wherein: Fig. 1 shows a longitudinal section of a double acting coupling according to the invention, wherein for the sake of clearness certain parts are presented in another position; Fig. 2 shows a cross-section of a part of the coupling along the line ll-ll in fig. 1: and Fig. 3 shows a detail section of the two friction rings and the annular disc between them, approximately along the broken line 111- 111 of fig. 2, and on a slightly enlarged scale.

The coupling shown in the drawings comprises a fixedly mounted flange 1, against which is connected the house 2 in a manner not shown. The driven shaft 5 is supported by the flange 1 and the house 2 by means of bearings 3 and 4, toothed wheels 6 and 7 being mounted on said shaft. At the bearing 4 the house is closed by a lid 8. The shaft 11 to be coupled is supported by the flange 1 and the house 2 by means of the bearing 9 and 10, said shaft being connected with the part to be driven by means of the flange plate 1 2.

The house is sealed by means of the ring 1 3 all around the projecting part of the flange plate 12.

The toothed wheels 1 6 and 1 7 are rotatably mounted on the shaft 11 to be coupled by means of the bearings 14 and 1 5. The toothed wheel 1 6 is directly coupled with the toothed wheel 6 of the driven shaft, whereas the toothed wheel 1 7 is coupled with the toothed wheel 7 of the driven shaft by means of a rotatable toothed wheel (not shown), supported by the house.

When the driven shaft 5 is rotating in the direction of the arrow P, the shaft 11 to be driven will rotate in the same direction, when the shaft is connected with the toothed wheel 17, and in the opposite direction if the shaft 11 is connected with the toothed wheel 1 6.

For coupling of the shaft 11 with one of the toothed wheels 1 6 and 17, an annular disc 1 8 has been mounted on the shaft 11, with at either side thereof friction rings 1 9 and 20, which are shiftable with respect to the shaft 11 and the annular disc 1 8 and are sealingly engaging the shaft and the annular disc 1 8 by means of O-rings. Thus the areas 21 and 22 respectively for pressure medium are obtained between the annular disc 1 8 and the friction rings 19 and 20.

Press-rings 23 and 24 respectively are located against the side of the annular ring 18 facing away from the friction rings 1 9 and 20, said press-rings on the other side contacting the lamellae packages 25 and 1 6 respectively. The lamellae package 25 comprises a number of lamellae, which are successively in connection with the press-ring 24 and with the toothed wheel 16, so that on pressing the lamellae against each other a connection can be achieved between the toothed wheel 1 6 and the shaft 11 to be coupled. The same can be said about the lamellae package 26.

Sealing rings 27 and 28 respectively are present at the press-rings 23 and 24, said sealing rings being sealed by means of Orings with respect to the corresponding pressrings and with respect to shaft 11. In order to prevent displacement of the sealing rings 27 and 28 in one direction, they engage collars 29 and 30 respectively, mounted on the shaft 11. Because of the mounting these collars will, however, not form an integral part of the shaft, but my be obtained for example by bushings shoved on the shaft. The annular disc 1 8 need not form an integral part with the shaft either.

In the manner indicated areas 31 and 32 for pressure medium are formed respectively between the friction rings 1 9 and 20 and the sealing rings 27 and 28 respectively.

Between the annular disc 1 8 and the friction rings 1 9 and 20 the balls 33 and 34 respectively are present which cooperate with inclined faces (not shown) oppositely provided in the annular ring 1 8 and the friction rings 1 9 and 20 respectively, in a manner as described in the above-said Dutch patent specification, in order to maintain the coupled connection when the shaft 11 has been coupled.

In the annular ring 1 8 are in addition three bores 35, 36, and 37, in which are located the pistons 38, 39 and 40, respectively, each of which is pressed outwardly by means of a spring 41, which is mainly incorporated into an axial channel 42 in the relevant piston, which channel emerges at the end of the piston into a radial channel 43, which in the interior location of the piston, is closed off by the wall of the bore in the annular disc 1 8.

The somewhat rounded off ends of the pistons 38-40 cooperate with a control ring 44, which is held in position with respect to the annular ring 1 8 by pins 45, applied in the friction rings 1 9 and 20, but in such a manner that the friction rings 1 9 and 20 may be axially displaced with respect to each other.

As appears from fig. 2 the piston 38 will be shoved outwardly into a recess 46 of the control ring 44 in the neutral position of the coupling. Moreover the piston 39 will end up in the recess 47 in the one engaged position and in the other engaged position the piston 40 will end up in the recess 48 of the control ring 44.

A channel 49 has been made in the shaft 11 for the supply of pressure medium to the area 21. A channel 50 is present for the supply of pressure medium to the area 22, and for the supply of pressure medium to the two areas 31 and 32 the shaft is provided with a channel 51. The channel 51 is in direct connection with the bore 35 by means of a branch 52, in which bore the piston 38 is located. Channels 53 and 54 extend through the annular disc 1 8 in an axial direction towards the bores 36 and 37 respectively.

The channel 53 extends itself to the area 21 and the channel 54 to the area 22, so that actually the channel 54 in fig. 2 is in front of the plane of the drawing. In the position of the pistons 39 and 40 as shown in fig. 2, there is no open connection between the channels 53, 54 and the corresponding bores 36 and 37 respectively, but such a connection is created when on rotation of the annular disc 1 8 either the piston 39 or the piston 40 will end up in the relevant recesses either 47 or 48.

The supply of pressure medium to the channels 49, 50 and 51 is controlled by means of a control valve 55, which is provided with a channel 56, which is continuously in connection with the press connection 57 of the pump 58, which is incorporated in a recess 59 in the flange 1 and is closed on the other hand by means of the plate 60 and is directly driven by means of the driven shaft 5.

In a bore 61 in the flange 1 and the plate 60 pin 62 is present, which may engage recesses 63, made in the operating valve 55, when oil under pressure is supplied to the bore 61 in a manner not further shown.

When the pressure provided by pump 58 is low, pin 62 is pressed into a recess 63 of the operating valve 55 with only a slight force by means of a spring 64, so that the operation of the valve is possible by pushing away the pin 62 against the force of the spring 64.

It will be obvious that between the channels running from the operating valve and the channels provided in the rotating shaft a continuously connection has to be present to which end annular spaces 65 have been provided in the flange 1 around the shaft 11, as shown in fig. 1.

The functioning of the friction coupling is as follows: In the neutral position as presented in the drawing from the pump 58 medium is supplied to the channel 56 in the operating valve 55 via de connection 57. The medium then flows via the channel 51 towards the areas 31 and 32 and via the branch 52 towards the bore 35 and via the channels 42 and 43 in the piston 36 along the control ring 44 into the house of the coupling, from where it may be sucked back again by the pump 58.

The pressure of the medium will be only small but the friction rings 1 9 and 20 will be closest to the annular disc 1 8.

Now the coupling will be engaged for example by rotation of the control valve 55 from the position indicated with N to the position V. The channel 56 of the valve 55, being connected to the discharge line 57 of the pump 58, will then get into connection with the channel 49 in the shaft 11, which channel runs towards the area 21 between the annular disc 1 8 and the friction ring 1 9.

There is no longer a connection then between the discharge connection 57 of the pump and the suction side thereof, so that the pump pressure will increase whereby the friction ring 1 9 will be pushed away from the annular disc 18, so that the lamellae package 25 will be compressed via the press-ring 23, causing the rotating toothed wheel 1 6 to engage shaft 11. The balls 33 will then start to cooperate with the inclined faces of the parts 1 8 and 1 9. The annular disc 18 will perform a certain angular rotation with respect to the friction ring 19, so that the piston 38 will be positioned outside the recess 46, whereas the piston 39 will be received into the recess 47 in the completely engaged condition.When this happens, the piston 39 will release the channel 53, connected with the area 21, so that the pressure medium can flow away via de axial channel 42 and the radial channel 43 in the pistion 39 towards the area in the house 2 of the coupling which is filled with oil. The pump 58 then will have to supply hardly any pressure.

If it is intended to disengage the coupling the control valve 55 is turned back again to the position first described, no free connection being present any longer between the press and suction sides of the pump 58, but medium will be supplied to the line 51 thus bringing the areas 31 and 32 under pressure and pushing the friction ring 1 9 to its neutral position. Once the ring 1 9 has reached this neutral position, the annular disc 1 8 will reoccupy the position as shown in fig. 2 with respect to the control ring 44.

If the control valve 55 is now turned to the position indicated with A in fig. 1, the pressure medium will be supplied to the line 50, thus friction ring 20 being pushed away from the annular disc 1 8 to compress the lamellae package 26. The outgoing shaft 11 will then start to rotate in a direction opposite to that in the first case.

As has been described already above, a pin 62 is present at the control valve 55, which pin will be pushed towards the operating valve 55 with a considerable force when the pump is providing medium under pressure. If the operating valve is for example in position A, thus the shaft 11 being driven in a given direction, the mcdium displaced by the pump 11 will be able to circulate freely, thus nin 62 being pushed into a recess 63 of the control valve 55 by the spring 64 with only a minor force. If now, with pushing away of the pin 62, the control valve is moved to the position N, the free circulation of the medium will be interrupted, thus the pump pressure will start to increase and the medium supplied to the area 23 will be put under pressure. The friction ring 20 will then be pushed toward the annular disc 18. while the pin 62 will be pushed into a recess 63 of the control valve 55 with a considerable force, thus counteracting further turning of the control valve to the position V. Only when the coupling has acquired its free position, in which the piston 35 is received into the recess 46, as shown in fig. 2, the pressure of the medium, provided by the pump 58 will decrease, thus allowing pin 62 to be pushed out of the recess 63 of the control valve 55 when bringing the control valve to the position V. It is now impossible to move the control valve 55 directly from the position A to the position V or vice versa.

It will be obvious that the drawings present only one possible embodiment of the invention which has been described in the above, and that many modifications may be made without leaving the inventive concept.

Claims

1. Friction coupling, in particular for application between a combustion engine and a reversing gear, said coupling comprising at least one axially shiftable friction ring on a shaft to be coupled, which is rotatably resting against an annular disc, fitted on the shaft to be coupled, by means of roller elements, said roller elements being positioned between inclined faces, slanting with respect to opposing end faces of the friction ring and the annular disc, means being provided for axial shifting of the friction ring for engaging and disengaging the coupling, wherein the friction ring, shiftable over the shaft, on the one side is sealed off at the inner circumference with respect to the shaft and on the other side is sealed off at an axial face, located at a distance from the inner circumference with respect to the annular disc for forming a sealed first area between the opposed end faces of the friction ring and the annular disc, to which area a pressure medium can be supplied for activating the coupling, while opposite the other end face of the friction ring a sealing ring is mounted on the shaft, which is suported in such a manner with respect to the shaft that it can not move away from the friction ring, said sealing ring being sealed at the inner circumference with respect to the shaft and at the outer circumference with respect to the friction ring or a press-ring connected therewith, in such a manner that, between the sealing ring and the friction ring, a second sealed area is formed, to which a pressure medium can be supplied for disengaging the coupling, channels being present in the shaft for the supply and discharge of the pressure medium to the areas formed by means of a stationary position control valve, valve means being positioned in the annular disc allowing to make a connection between the supply and discharge channels for the pressure medium after an activating of the coupling has taken place.

2. Friction coupling according to claim 1, wherein the valve means are formed by bores provided in the annular disc which are mainly radially extending, in each bore a piston being present which is pressed outwardly by a spring and/or by the pressure medium used against the inner circumference of a control ring rotating together with the friction ring, said control ring being provided with a number of recesses corresponding with the number of pistons and positioned such that by making use of the limited angular rotation occuring between the friction ring and the shaft to be coupled when bringing the coupling into a desired specific position always one of the pistons is shoved outwarding into the corresponding recess by which a connection is achieved between the supply line used for the pressure medium and the suction side of the pump.

3. Friction coupling according to claim 2, wherein from the inner end of each piston an axially extending channel is made therein, continuing in a radially extending channel ending in the piston wall at such a location, that this channel is set free from the bore in which the piston is present when the piston is pressed into the corresponding recess.

4. Friction coupling according to claim 3, wherein when supplying medium to an area in order to bring the coupling into the neutral position, pressure medium is simultaneously supplied to the axial channel of that piston, which is pressed into the recess when the coupling has reached its neutral position, whereas with supply of pressure medium to that area whereby the coupling is brought into an engaged position, medium is simultaneously supplied to a channel provided in an axial direction in the annular disc, and emerging against the piston, which is shoved into the corresponding recess after bringing the coupling in the engaged position, during which movement the channel is set free for achieving a connection between this channel and the initially axially and subsequently radially extending channel through the piston.

5. Friction coupling according to one of the preceding claims, wherein the control valve is blocked by the pressure built-up of the operating medium when the operating valve of the transmission is brought into the neutral position, until the relevant valve means, present in the annular disc has ensured that a connection between the relvant supply channel for the pressure medium and the suction side of the pump is achieved such that the pump pressure has decreased to the dirculation pressure.

6. Friction coupling according to claim 5, wherein blocking of the control valve occurs by a pin which has been incorporated as a piston in a cylinder and which, by the pressure of the medium may be pressed into a recess in the control valve so firmly, that the control valve can not be operated.

7. Friction coupling substantially as herein described with reference to and as shown in the accompanying drawings.