FR2626638A1 - Hydraulically controlled clutch of the sort including a drag brake - Google Patents

Abstract

The present invention relates to hydraulically controlled multi-disc clutches including a drag brake 60. According to the invention, the brake disc 62 of the said drag brake 60 is subjected to the action of an annular elastic member 63 of the Belleville washer type.

Description

 The present invention relates in general to clutches, and in particular multi-plate rifles, the control of which is hydraulic.

 A multi-plate clutch comprises, overall, two coaxial parts, a first, or driving part equipped annularly with one or more friction discs staggered axially and a second, or driven part, equipped with intermediate discs also staggered axially, and arranged alternately with friction discs.

 When such a multi-plate clutch must be hydraulically controlled one of the two parts, for example the driven part comprises two parts in relation to cylinder-piston, located on a first axial side of the intermediate and friction discs, forming between they have a variable voluiae pressure chamber.

 When pressurized fluid is sent into this pressure chamber, the piston-forming part moves axially to act on the intermediate and friction discs and to clamp them axially between it and a fixed flange located on the axial side opposite these discs. .

your two coaxial parts, driving and driven, are then secured in rotation with each other
In order to separate the two coaxial parts, the pressure in the pressure chamber is released, which allows elastic means, provided for this purpose, to loosen the discs.

 In a manner known per se, there is provided in such devices a circuit for lubricating and / or cooling the discs. Also using a pressurized fluid.

 One of the problems to be solved in the re-setting of such a hydraulically controlled multi-plate clutch results from the fact that the f-luide presents in their lubrication and cooling circuit can induce, by drag effect, an untimely rotation of the part. carried out while the latter is in the disengagement position with respect to the driving part.

 Since this type of clutch finds its application in particular in the control of a power take-off on vehicles such as tractors, this problem is important because it can make it difficult and even dangerous to engage a power tool on such a power take-off. causing it to rotate inappropriately.

 To overcome this difficulty, it is known to associate with the driven part of the clutch a brake, commonly known as drag brake, capable of acting on it when it is in the disengagement position.

 Such a treated brake may include a piston capable of applying a brake shoe against a bearing surface, generally cylindrical of the part led to control, or else be, as proposed in French patent n 77 27970 filed on September 16, 1977, a band brake.

 These solutions, although often satisfactory, have certain drawbacks; first of all they are counting and moreover they notably increase the radial size of the clutch because the action of the drag brake is then exerted outside the cylinder-forming part.

In order to reduce the size of such a device, it has already been proposed to apply the brake inside the fixed casing, but the solutions proposed to date are either complex or incapable of absorbing the necessary friction torque.
A general object of the present invention is to provide a hydraulically controlled clutch device comprising a drag brake which is compact, simple to build and efficient in operation.

In a more precise manner, it relates to a clutch with hydraulic control of the kind comprising in a fixed casing, a first part carrying at least one disc linked in rotation but moveaxially, a second part comprising a piston and a cylinder carrying the at least one disc linked in rotation and axially movable, a brake disc capable of acting on the internal face of the fixed casing for immobilization of that of said first and second part which is the driven part characterized in that said brake disc is subjected to the action of an annular elastic member of the Belleville washer type
The use of an annular elastic member of the Belleville washer type makes it possible to exert a large braking force by using a member of small bulk.
According to another characteristic of the invention, this annular elastic member is linked in rotation to the cylinder of the driven part so as to absorb the braking torque.
This annular elastic member can, moreover, be subjected to control means piloted by the axial displacement of an element of the driven part.
These control means are such that they reduce the tightening action exerted by the BÉelleville washer on the friction disc as a function of the clutch tightening, they can be either mechanical and then be formed by at least one linked caliper for example the piston, or hydraulic if an intermediate piston is provided which, due to a pressure difference, can move at the same time as the piston of the driving part.

In a preferred embodiment of the invention, the annular elastic member is controlled by stirrups linked to the first intermediate disc. It is then possible to use said annular elastic member to separate the friction discs and the intermediate discs during clutch release
According to this arrangement, it is then possible not to use the spring usually provided for pushing the piston when the clutch is released, the annular elastic member being able to advantageously replace it.
The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the accompanying drawings in which *
FIG. 1 is a half-section view of a hydraulically controlled clutch device according to the invention,
FIG. 2 is a section along line II-II in FIG. 1,
FIG. 3 is a view along arrow III in FIG. I,
FIG. 4 is a section along the line IV-IV of FIG. 1,
- Figure 5 is a partial sectional view of an alternative embodiment of the device.

- Figure 6 is a half sectional view of another alternative embodiment of the device
Overall, and as shown in these figures, the clutch with 'hydraulic control according to the invention comprises a driving part 10 and a driven part 20 mounted in a fixed casing 30 partially shown.

 The driving part 10 comprises a hub 11 linked in rotation, for example by a spline mounting, to a driving shaft, not shown, which can be an output shaft of the motor vehicle engine on which said hydraulically controlled clutch is artwork.

Said hub li has, at a distance from the axis, an axial annular extension 12 with a grooved external profile for mounting annular friction discs 13 of which only two are shown here. These friction discs 13 are, in a manner known per se, engaged by a toothing 14, which they have for this purpose at their internal periphery, on the grooves 15 of the axial extension 12. They are thus linked in rotation to said axial extension 12 while being left free in translation
The clutch has, alternating axially with the friction discs 13, intermediate discs 22 of the driven part 20 These intermediate discs 22 are fixed in rotation on a skirt 21, which comprises said driven part, while being engaged, by a toothing 23 provided for this purpose on their outer periphery, with grooves-res 24 axially perforated, from place to place, up to its end this skirt 21.

 Like the friction discs 13, these intermediate discs 22 are free in translation with respect to the element which carries them, that is to say the skirt 21.

 In order to tighten the clutch, the friction discs 13 and the intermediate discs 22 are moved by a control means, which will be described later, in the direction of a flange forming the reaction plate 25 shims axially and in rotation on the skirt 21 .

 In the embodiment shown, this reaction plate 25 is fixed axially on the skirt 21 by a washer 27, of the radially split washer type, which is engaged with a groove 28 in the skirt 21 and with a groove 29 in the plate reaction 25.

Near its end, the skirt 21 is, on its outer face hooped by a ring 35 which is made integral by welding for example
The device according to the invention is a clutch with hydraulic control, the control means 40 of said clutch are therefore hydraulic means.

 These control means 40 are part of the driven part 20, the latter comprising for this purpose two elements in relation to cylinder-piston. The cylinder 41 is formed by the skirt 21 and a radial return 42 which the latter presents at its end affixed to the reaction plate 25.

 The piston 43 is located inside this cylinder 41, and has an axial extension 44 directed towards the friction discs 13 and spacers 22 mounted alternately, in order to act on thrust thereon.

 The cylinder 41 and the piston 43 are arranged annularly around a hydraulic distributor means 45.

 The cylinder 41 is linked to the internal periphery of the.

radial flange 42, to a flange 46 of said hydraulic distributor 45 by rivets 47,
The piston 43 is slidably mounted in the annular space located between the skirt 21 and the hydraulic distributor 45, for its sealing assembly the piston 43 carries a seal in contact with the internal surface of the skirt and a seal in contact with the surface external of the hydraulic distributor.

The piston 43, the cylinder 41 and the hydraulic distributor 45 delimit between them a variable volume chamber 48 capable of being supplied with fluid under pressure by a conduit 49 of the hydraulic distributor 45,
Under the action of the pressurized fluid, the piston 43 passes from its position shown in the figures for which the discs are separated from each other to a position, not shown, for which it ensures the axial clamping of the discs against the plate of reaction 25.

 This piston 43 is permanently biased towards its position for disengaging the clutch by a spring 50., positioned in the free annular space 51 which remains, in a manner known per se, between the axial extension 12 of the hub it the driving part 10, the axial extension 44 of the piston 43 and the hydraulic distributor 45 The spring 50 is in abutment at one of its ends, against the piston 43 and, at the other of its ends, against a flange 52 integral axially with the hydraulic distributor.

 To provide lubrication and / or cooling of the clutch discs, pressurized fluid is supplied via channel 53 of the hydraulic distributor 45. The fluid then used may be different from that ensuring the hydraulic control, but in practice, for simplicity, the same fluid.

 The lubrication and / or cooling fluid enters through the channel 53 in the annular space 51, circulates between the axial extensions 12 and 44 of the hub II and of the piston 43, towards the friction discs 13 and the intermediate discs 22, then after having swept these discs, escapes through the grooves 24 of the skirt 21 in the casing 30.

 It is the circulation of this lubrication and / or cooling fluid which, when the clutch is loose. can induce an untimely rotation of the driven part by drag effect.

 The present invention therefore provides for the use of a drag brake 60. In a manner designed per se, a fixed part is used to immobilize the driven part 20 of the casing 30 of the hydraulically controlled clutch. A generally annular pressure plate 61 clamps, against the internal face of the casing 30, a brake disc 62 which can be carried either by the pressure plate 61, or by the fixed casing 30.

According to the invention, the pressure plate 61 is subjected to the action of an annular elastic member such as a Belleville washer 63 to apply said drag brake 60. Means are then provided in the clutch control device hydraulic to release said drag brake when applying the clutch
These control means can be mechanical, as shown in FIGS. 1 to 5, or hydraulic, as shown as a variant in FIG. 6.

if one refers to figures 1-s 5, the washer
Belleville 63 is, by its internal periphery, integral in rotation with the radial flange 42 of the cylinder element 41 of the driven part 20 For this purpose, the rivets 47, ensuring the joining of said flange 42 on the flange 46 of the hydraulic distributor 45 , have an axially elongated head 64 which is housed in notches 65 of the internal periphery of the washer
Belleville 63. for its positioning rais, the washer
Belleville 63 is mounted by its internal periphery on a bearing surface 66 ending in a shoulder 67 of the hydraulic distributor 45 against which it is axially supported
The pressure plate 61 conforms, at at least two points on its external periphery, so as to have tabs 68. These tabs 68 have an axial part 69, in the direction of the driven part 20, then a radial part 701 is directing opposite the axis of the device and ending in an enlarged part 71. As visible in FIG. 4, the Belleville washer 63 is secured in rotation to the pressure plate 61 by being engaged by notches 72 of its periphery external on these legs 68
The Belleville round 63 lying in support by its internal periphery against the shoulder 67 of the hydraulic distributor 45, and in support by its external periphery against the pressure plate 61 of the drag brake 60, it exerts an axial force on said pressure plate 61 in the direction of the fixed casing 30 so as to apply the brake disc 62.In addition, the mounting of the washer
Belleville 63 by notches 65 of its internal periphery on the elongated heads 64 of the rivets 47 and by notches 72 of its external periphery on the lugs 68 of said pressure plate 61 allows it to be said Belleville washer 63 which drives the drag brake in rotation and ensures the passage of all the friction torque, this would not have been possible if an elastic element other than annular had been provided.

 In a hydraulically operated clutch device comprising a drag brake, said drag must be applied when the clutch is released but in order not to interfere with the use of said clutch, said drag brake must be released when the clutch is tight.

The use for tightening the drag brake 60 of an annular elastic member such as the washer
Belleville 63 -allows, as will be seen below, to have means for controlling the application of the drag brake 60 very simple.

The control means 80 for applying the drag brake 60 can advantageously, as shown in FIGS. 1 to 5, be reduced to a. a part which will be called the stirrup 81. This stirrup 81 is intended to act, by one of its ends, on the annular elastic member 63; this action is done in this example embodiment, by means of the plate; 61. In order to make the stirrup 81 integral in translation with the pressure plate 61, - it has an opening 82 in the shape of a T, the wide part of said opening 82 allows the passage of the widened part 71 of the tab 68 of the pressure plate 61, while the narrow part of said opening 82 allows passage only of the radial part 70. By this simple and rapid assembly, the stirrup is linked to the pressure plate 61 and can move the latter axially
At its other end, the stirrup-81 is controlled in translation by an axially movable element of the driven part 20. This movable element can be either the piston 43 or one of the intermediate discs 22-. In figure l. a preferred arrangement of the invention is shown according to which said stirrup 81 is controlled in translation by the intermediate disc 22 closest to the piston 43. For this purpose, as visible in the figures, - the end of the stirrup 81 is folded in the direction of the axis and then forms a tab 83 qfli crosses the skirt 21 by one of the grooves 24 thereof upstream of the intermediate disc 22 closest to the piston 43 Said tab 83 has an enlarged end 84 for its radial retention relative to the skirt 21.

Preferably, in order to avoid the risk of jamming during the maneuvers of the clutch, several stirrups 81 are provided, for example two years diametrically opposite positions or three regularly distributed circumferentially.
The device is now described, we will explain how it works.

 In Figure I, the hydraulically operated clutch is shown in the loose state, the discs 13 and 22 are spaced from each other, the drag brake 60 is applied. When it is desired to engage, the pressurized fluid is admitted through the channel 49, of the hydraulic distributor 45, into the chamber 48 and then pushes the piston 43, to the left of FIG. 1, to its extreme position for which it clamps the friction discs 13 and the intermediate discs 22 between its axial extension 44 and the reaction plate 25 It is easily understood that, when it is tightened, the first intermediate disc 22 pushes by its external periphery on the tab 83 of the caliper 81.

 The caliper 81 being, thus controlled in translation to the left, drives the pressure plate 61 by its lugs 68. The brake disc 62 is then released and the tralnee brake 60 has no more action.

When the pressure is released in the chamber 48, the Belleville washer 63 recalls the pressure plate 61 to the right in the position of FIG. 1 to re-apply the drag brake 60
The return spring 50 pushes the piston 43 back into its position in FIG. 1, aided by the action of the Belleville washer 63 on the caliper 81 and on the intermediate disc 22 *
Due to the positioning of the tab 83 so as to be controlled, to be clamped, and to control, on release, the intermediate disc 22, the spacing of the friction discs 13 and of the intermediate dinguas 22 is obtained more reliably during the declutching only if one acted by the tab 83 on the piston 43.

 As a variant, in FIG. 5, it is provided that the stirrup 81 acts directly on the Belleville washer 63, for this purpose the Belleville washer 63 is hooked to the stirrup by teeth.

In this embodiment, the shape of the pressure plate 6l has also been changed so that it bears on a central region of the Belleville washer 63, in order to increase the load exerted by said washer.
Belleville 63
This can be useful if the drag torque to be fought is very high, but it can also make it possible not to use the return spring 50 by ensuring the return of the piston by the Belleville washer 63 alone.

 If necessary, it is also possible to attach two Belleville washers to provide a higher load.

We see here another advantage of the use of an annular elastic member: one can, without being penalized by problems of volume, modify the load available in from simple baleen. drag brake 60
In Figure 6, there is shown a variant of the hydraulically controlled clutch device in which the control means 80 of the drag brake 60 are hydraulic. in this figure the same elements as in the previous figures bear the same references
In this exemplary embodiment, the cylinder part 41 of the driven part is linked in rotation to the hydraulic distributor 45 by grooves 90 located at the internal periphery of the radial return 42 which eng-renent on corresponding grooves 92 of the hydraulic distributor
This mounting by splines allows the cylinder 41 to be able to move axially with respect to the hydraulic distributor 45 for the reasons which will emerge from the description which follows.
In this embodiment, it is the radial return 42 of the cylinder 41 which serves as a pressure plate in order to tighten the brake disc 62 against the fixed casing 30 * This radial return 42 is pushed towards the position for applying the drag brake 60 by the axial action of an annular elastic member 63 according to the invention L) has washer
Belleville 62 rests axially on its internal periphery on a washer 92 linked to the hydraulic distributor 45 and on its external periphery on a circumferential bead of an intermediate piston 93
The hydraulic chamber 48 for controlling the multi-plate clutch is delimited by the piston 43, the cylinder 41, the intermediate piston 93 and the hydraulic distributor 45. When, for the clutch tightening control, fluid under pressure sion is admitted, through the channel 49, into the chamber 48, the piston 43 is pushed to the left of the figure- 6 Because of the difference between the surfaces of the piston 43 and the intermediate piston 93, and therefore of the difference of pressure occurring, the piston 93 is also moved to the left of FIG. 6, as well as the cylinder 41, against the force exerted by the Belleville washer 63.

The brake disc 62 is thus released
The intermediate piston 93 moves from the stroke C left during assembly between the internal periphery of the Bellaville washer 63 and the intermediate piston 93 Z this stroke C sufficient for releasing the brake disc 62.

 When disengaging, the pressurized fluid is no longer admitted into the hydraulic control chamber 48 and the force exerted by the Belleville washer 63 pushes the intermediate piston 93 and the radial flange 42 to the right of the figure so as to tighten the drag disc 62 of drag brake 60.

 Of course, the present invention is not limited to the examples described but encompasses any variant embodiment of said clutch with hydraulic control.

Claims (11)

 1 - Clutch with hydraulic control of the kind comprising in a fixed casing (30), a first part (10) carrying at least one disc (13) linked in rotation but axially movable, a second part (comprising a piston <43) and a cylinder (41) carrying at least one disc <22> eft, rotation and axially movable, a brake disc (62) capable of acting on the internal face of the fixed casing (30) for immobilization of that of said first and second parts which is the driven part (20) characterized in that said brake disc (62) is subjected to the action of an annular elastic member (63) of the washer type Beautiful city.  2 - Hydraulically controlled clutch according to claim 1 characterized in that said annular elastic member (63) is subjected to control means (80) controlled by the axial movement of an element of the driven part.  3 - Hydraulically controlled clutch according to claim 2, characterized in that the control means (80) reduce the clamping action exerted by the annular elastic member (63) on the brake disc (62) as a function of the clamping discs (13, 22) of the clutch.  4 - Hydraulically controlled clutch according to claim 3, characterized in that said control means (80) are mechanical and formed by at least one stirrup (81) capable of acting by the first of its ends on the external periphery of the annular elastic member (63) directly or indirectly.  9 - clutch with hydraulic control according to claim 4, characterized in that by the second of its ends, the caliper (81) is capable of being controlled in translation by an axially movable element of the driven part (20)  6 - Hydraulically controlled clutch according to claim 5, characterized in that said cylinder (41) being partly shaped as a skirt (21) having grooves (24) for mounting the discs (22), the caliper (81) comprises at the second of its ends a tab (83) in the direction of the axis of the device which passes through the cylinder (41) 'through one of these grooves (24) and has an enlarged end (64) for its radial retention.  7 - Hydraulically controlled clutch according to claim 6, characterized in that said tab (83) of the caliper (81) passes through said cylinder (41) upstream of the disc (22) closest to the piston (43).  8 - clutch hydraulically controlled a aes the preceding claims characterized in that said annular elastic member (63) is -solidaire in rotation at its inner periphery of a radial flange (42), that has said cylinder (41), by cooperation with notches (65) which for this purpose has the axially elongated head (64) of rivets (47) ensuring the joining of said radial flange (42) on a hydraulic distributor (45) and that it exerts its action of tightening the friction disc by its outer periphery 20  9 - Hydraulically controlled clutch according to one of claims 4 to 88 characterized in that the stirrup (81) is made integral by the first of its ends with a generally annular pressure plate (61) subjected to the action of the outer periphery of the annular elastic member (63).  10 - Hydraulically controlled clutch according to one of claims 4 to 8, characterized in that the stirrup (81) is made integral by the first of its ends with the outer periphery of the annular elastic member (63) r le pressure plate (61) bearing on a central region thereof.  11 - Clutch with hydraulic control according to claim 1t 3, characterized in that said control means (80) are hydraulic and include an intermediate piston (93) on a circumferential bead from which supports the external periphery of the annular elastic member (63) .  12 - clutch with hydraulic control according to claim II, - characterized in that said intermediate piston (93) is located inside the cylinder (41) and controls in translation the -radial flange (42) of said cylinder (41), said radial flange (4Z) of the cylinder (41) serving as a pressure plate for the brake disc (62)