FR2780465A1 - Hydraulic slave actuator for clutch mechanism - Google Patents

Abstract

The concentric hydraulic slave actuator (8) consists of one part, a fixed part (9), made up of an exterior body (21) and a guide tube (22) cylindrically coaxial. The other part is a piston (11), mounted to slide coaxially in the fixed part (9) and by so doing defining a variable volume chamber (13) designed to be joined up to the hydraulic operating actuator. The piston head (11) consists of at least two segments assembled in an arc of a circle by the aid of a positioning washer (57). These segments in the form of a circle have on their nose ends (67), a seal (68) designed to ensure the sealing of the variable volume chamber (13).

Description

i "Hydraulic receiver, in particular of clutch, with piston head

  The invention relates to a hydraulic circuit, in particular to a clutch. More particularly, it relates to a receiving device capable of receiving information for controlling a hydraulic circuit in the form of pressure variations, more precisely a

concentric type receptor.

  Receiving devices of this kind are for example described in the

  French Patent No. 82 03485 published under No. FR-A-2 522 757.

  Such receivers generally comprise, on the one hand, a fixed part composed of an external body and a coaxial cylindrical guide tube and, on the other hand, a piston mounted sliding coaxially with the fixed part and defining a chamber therein. variable volume intended to be connected to the transmitter

  hydraulics of the hydraulic control.

  The object of the present invention is to propose a hydraulic receiver which is simple to manufacture, and of low cost price, which, in order to do this, requires in particular less machining than in the technique.

  traditional, and is partially made of light material.

  To this end, the invention proposes a receiver of the concentric type for hydraulic control comprising, on the one hand, a fixed part composed of an external body and a coaxial cylindrical guide tube and, on the other hand, a piston mounted sliding coaxially with the fixed part and defining therein a variable volume chamber intended to be connected to the hydraulic transmitter of the hydraulic control, characterized in that the piston head comprises at least two segments in an arc of a ring assembled, thanks to a positioning means, in a ring carrying a seal intended to

  sealing the variable volume chamber.

  This arrangement makes it possible to produce by molding a piston head of complex section, then to assemble it by suitable means, without being limited by the release constraints. The joint is a joint for joining the segments. Preferably, these arcuate segments are three in number. The segments in an arc of a ring each advantageously carry a sculpture in the shape of an identical lug oriented towards the variable volume chamber. This arrangement facilitates the attachment of a seal which

  also ensures a complementary joining of the segments.

  The seal is advantageously a seal in the form of

toric cupola.

  The means of positioning the segments in an arc of a ring is

  preferably a metal support washer.

  Preferably, the support washer comprises positioning pins cooperating with bores formed in the segments in

  ring arch to ensure their precise positioning.

  The support washer advantageously includes a recess on i 5 its internal periphery intended to receive radial edges of guide shoes. In order to allow the assembly of the piston head with the other parts constituting the concentric receiver, the ring arc segments

  have a staircase ledge on their rear face.

  Advantageously, the piston carrying tube has a transverse flange

  arranged inside the staircase rim of the piston head.

  The staircase rim is preferably of width greater than the thickness of the transverse flange of the piston carrier tube, thus defining an axial clearance of the piston carrier tube in its housing inside the rim in

piston head staircase.

  Of course the number of guide shoes depends on the applications.

  The number of segments also depends on the applications.

  Description and drawings of a preferred embodiment of

  the invention, given below, will allow a better understanding of the aims and

  advantages of the invention. It is clear that this description is given as

  example, and is not limiting. In the drawings: - Figure 1 is a sectional view of a clutch assembly comprising a concentric hydraulic receiver according to the invention; - Figure 2 is a half sectional view of the receiver alone, on a larger scale; - Figures 3 and 4 are partial detail views of the guide tube before assembly with the outer body alone on a larger scale; - Figure 5 is a partial sectional view showing the elements forming the piston head and the seal; - Figure 6 is a view similar to Figure 5, the cutting plane being different; - Figure 7 is a half-sectional view along VII-VII of Figure 5 - Figure 8 is a view along VIII-VIII of Figure 2; - Figure 9 is a partial sectional view showing the establishment of the piston stop washer; - Figure 10 is a partial sectional view of the piston stopper; - Figure 11 is a partial sectional view showing the stopper

  piston in operational position.

  Figure 1 shows a sectional view of a clutch. We recognize in this view the main elements of the conventional clutch 1 here of the pushed type, with in particular the cover 7, the reaction plate 2, the pressure plate 3 on which the diaphragm 4 comes to bear, here in the position clutch disengaged, these two plates 2 and 3 being intended to tighten the friction linings 5 of a friction disc 6 equipped with a hub with internal grooves. Such clutches are well known per se and such by

  example as that described in detail in document FR-A-

2,730,532.

  The receiver 8, forming part of the clutch control, for disengaging the clutch, is here of the concentric type, and is visible in FIG. 1 in the position for which the clutch is disengaged, or disengaged, and on the Figure 2 in the rest position for which the clutch

is engaged.

  Generally in the following description, the term "before"

  corresponds to the left part of the parts in Figures 1 to 6, and the term "rear" corresponds to the right part of the same parts in these same figures. In known manner, the receiver 8 comprises two annular parts in relation to the cylinder-piston, namely a fixed part 9 by which the receiver 8 is mounted on a fixed structure such as the casing 10 of the gearbox, and a mobile part consisting of a piston 11l of generally annular shape sliding axially partially inside a

  cavity 1 2 also annular defined in the fixed part 9 of hollow form.

  This cavity 12 is blind and suitable for being pressurized and

  depressurized. The control fluid here is oil.

  It is thus defined by the piston 11, in the cavity 12, a chamber

variable volume 1 3.

  To vary the internal volume of this variable-volume chamber 13, the fixed part 9 has a supply inlet 14 connected to the cavity 12. This supply inlet 14 is extended by an internal channel 15 opening through an opening 16 in the bottom of the cavity 12 o is defined

the variable volume chamber 13.

  The power input 14 is connected by a conduit 17 to the transmitter (not shown) of the clutch control. This transmitter is actuated in a known manner by an actuator of any type (not shown), such as a clutch pedal or an actuator with a motor, for example electric, connected to a computer to act, according to programs.

  predetermined, on the piston of the transmitter.

  When the control fluid of the variable-volume chamber 13 is pressurized from the transmitter, the piston 11 is allowed to move to the left in FIG. 2, so that the volume of the variable-volume chamber 1 3 increases . In the position visible in Figure 1, the piston 1 1 is out of the cavity 12, the variable volume chamber 13

  then having maximum volume.

  The piston 1 1 actuates in its stroke a clutch release bearing 18 which pushes the internal end of the fingers of the diaphragm 4 to allow the clutch to disengage, as visible in FIG. 1. By depressurizing the variable volume chamber 13 , its volume decreases, the fluid returning through the conduit 17 to the transmitter; the piston 1 1 then moves to the right of FIG. 1, under the return effect of the diaphragm 4 which returns to its rest position in which, bearing on the cover 7 axially integral with the reaction plate 2, it urges elastically the pressure plate 3 in the direction of the reaction plate 2 for tightening, between the two plates, the linings 5. The piston reaches

  finally its rest position as shown in FIG. 2.

  The declutching stopper 18 forms the attack element acting by pushing on the fingers of the diaphragm 4, and consists, here, of a ball bearing, the rotating outer ring 19 of which is in permanent contact with the fingers of the diaphragm 4 by virtue of by the action of a preload spring 20 acting between the fixed part 9 and the piston 11 which cooperates with the ring

  internal 27 not rotating of the stop 28, under the conditions described above

below.

  The fixed part 9 of the receiver 8 is secured in a known manner to the gearbox casing 10, for example by means of non-removable ears.

visible in the drawings.

  Conventionally, and for example as described in document FR-A-96 02571, the fixed part 9 is composed of two main coaxial elements which are on the one hand an external body 21 made of a material

  moldable such as aluminum, and a concentric guide tube 22.

  The outer body 21 has a front tubular part 23 and a thicker rear part in the form of a flange 24; The fluid opening 16, connected by the internal channel 15 to the supply conduit 17,

  opens into the internal face of the collar 24.

  The guide tube 22 is preferably made of metallic material and forms a support and guide member for the piston 11. As can be seen in FIG. 2, the guide tube 22, mainly composed of a cylindrical section 39, is longer in its axial direction as the outer body 21. It is thin, which reduces the radial size of the receiver 8. This tube 22 is crossed by the input shaft of the box

speeds not shown.

  At its rear part, the guide tube 22 has, at the end of its cylindrical section 39, a flare formed by a conical section 30 terminated by a transverse annular edge 31. This annular edge 31 is secured to the outer body 21, to close the cavity 12 and form the bottom thereof; to do this, the outer body 21 has on its internal face 35 a groove 32, FIG. 3, and is internally stepped in diameter, so as to create a shoulder 33 internally extending one of the sides of the groove 32, here the

1 5 front flank.

  An O-ring 34 of known type is disposed in the bottom of the groove 32 so as to seal the connection, therefore that of the

variable volume 13.

  The annular edge 31 of the guide tube 22, of almost identical diameter, before its assembly, FIG. 3, to that of the internal face 35 of the external body 21, set back with respect to the shoulder 33, is inserted into the groove 32

  until the O-ring 34 is compressed, as described below.

  When it is placed in the groove 32, after placing the guide tube 22 in the axis of the external body 21, as can be seen in FIG. 3, the guide tube 22 has such a shape before mounting that its edge

  annular 31 is in line with the internal face 35 of the external body 21.

  The annular edge 31 is then brought into contact with the shoulder 33 of the outer body 21, FIG. 4, and is held in this position by a

counter tool 70.

  The conicity of the conical section 30 is then varied by the action of a tool 36 of cylindrical shape having a face having a frustoconical segment 37 and an annular segment 38 to bring the annular edge 31 into the groove 32 by a variation d angle and therefore a

  increase in the outside diameter of the annular edge 31.

  As can be seen in FIG. 2, the opening 16 for supplying the variable volume chamber 13 is arranged axially substantially in line with the conical section 30 of the guide tube 22 which defines the minimum volume of said chamber; this arrangement limits the axial size of the receiver 8 and allows good flow of the control fluid

  in the chamber 1 3 thanks in particular to the section 30.

  The front face of the flange 25 (on the left in FIG. 2) of the external body 21 serves as a support for the preload spring 20, the other end of which is supported on a transverse flange 26 which the piston 11 has at its

front end.

  A scraper seal 45, which contributes to preventing the penetration of dust within the variable-volume chamber 13, surrounds the guide tube 22. It carries a set of legs extending axially and forming guide pads 28; the scraper seal 45 and its guide pads 28 are axially integral with the piston 11 and caused to slide on the outer surface of the tube

  guide 22 and allow the piston 11 to be guided.

  The guide shoes 28, which here are six in number, each cover an angle of about 50 and are separated by sectors of an angle 10 along the guide tube 22 (see Figure 7); the scraper seal 45 and the guide shoes 28 are in one piece and made of plastic material having good sliding properties. The number of pads 28 depends on the applications. The guide shoes 28 are terminated at their end remote from the scraper seal 45 by radial flanges 55 each entering a recess 56 (FIGS. 5 and 6) formed at the internal periphery of a support washer 57 made of steel secured to the piston i 1 and whose role will appear below. The splitting into several guide shoes 28 makes it possible to better

  withstand thermal deformations.

  Between the piston 11 and the scraper seal 45, is inserted a steel piston support tube 46, FIG. 2, of substantially cylindrical shape, terminated at its rear part by an annular flange 47 which is arranged, in the assembled configuration of the receiver 8 such that can be seen in FIG. 2, between the rear face of the piston 11 and the support washer 57. The piston support tube 46 is produced in the example described here, without limitation, in steel, which allows it to withstand mechanical stresses without excessive deformation. In particular, the piston carrying tube 46 is adapted to

  resume the forces transmitted by a self-centering washer 49, described below

below.

  Therefore, the piston 11 is made of plastic, which reduces costs, avoiding for example the need for machining of a metal piston, the piston 11 can here be molded. The piston 11 and the scraper seal 49 with these pads 28 thermally insulate the piston support tube 46, which deforms very little. The risks of jamming of the piston 11 are reduced for the presence of the tube 46 and of the pads 28. The main function of the piston 11 is then to transmit the mechanical forces created in the

  variable volume chamber 13, along the axis AA, at the stop 18.

  To this end, in the embodiment presented here by way of example, the piston 11 comprises ribs 58 of structural reinforcement, oriented axially in a direction substantially parallel to the axis AA, extending towards the rear of the piston 11 from its front face 54, and of dimension adapted to allow the passage of the piston 11 and the ribs 58 in the cylindrical space formed

  between the piston-carrying tube 46 and the tubular part 23 of the external body 21.

  The front face 54 of the piston 11, of substantially annular shape, is

  therefore intended to receive the clutch release bearing 18.

  To provide protection against entry of impurities into the variable-volume chamber 13, the piston 11 includes a protective skirt 59, which has the shape of an annular cylindrical wall of small thickness of axis AA, the end of which free is shaped as an external scraper seal 60. The protective skirt 59 takes place during mounting around the tubular part 23 of the outer body 21 and inside the preload spring 20,

  the external scraper seal 60 being adapted to rub against the external body 21.

  The preload spring 20 is supported on the transverse flange 26 carried by the piston 11 and which extends radially at the birth of the protective skirt 59. Such a protective skirt 59 advantageously replaces the bellows

  usually used in conventional concentric receivers.

  As can be clearly seen in Figure 2, and as can be seen from

  the description above, the piston 11 therefore has a section in the form of

  "U" surrounding the piston carrying tube 46, and a first branch of greater structural resistance, forming the piston proper, is disposed between the piston carrying tube 46 and the tubular part 23 of the outer body 21, and a second external branch thin forming the protective skirt 59, the end 60 of which scrapes the external face of the tubular part 23 of the external body i15 to protect the internal part of the receiver 8 against impurities. The receiver 8 has, in a known manner, an axial clearance 62 and a radial clearance, FIG. 5, between the piston head 63, described below, and the piston 11 proper, to take into account possible variations in

  position, fingers of diaphragm 4 for example.

  In the present invention, the piston head 63 is made up, figures and 6, of the support washer 57 of steel, already cited, placed in the rear part (on the right in the figures) of the annular flange 47 which the carrying tube comprises. piston 46, as well as several segments 64, 65, 66, here three in number, of annular shape each carrying an also annular sculpture in the shape of a pin 67 oriented axially towards the variable-volume chamber 13. These segments 64, 65 , 66 have on their rear face a staircase edge 61 carried by an axial tab 71. The shape of the piston head 63 in several annular segments 64, 65, 66 is justified by the fact that a molding in an annular piece comprising both shaped sculpture

  lug 67 and the staircase edge 61 is not easily achievable.

  When mounting the segments 64, 65, 66 around the support washer 57, the staircase flanges 61 of the segments 64, 65, 66 overlap and trap the annular flange 47 of the piston carrier tube 46, limiting the possible displacement of the tube piston holder 46, and therefore of piston 11, to an axial clearance 62 defined by the staircase rim 61, relative to the piston head 63. A cup seal 68 of generally toric shape is placed on the lug-shaped sculptures 67 of the three segments 64, 65, 66, and seals the variable-volume chamber 13. The seal 68

  constitutes an assembly part for the segments 64, 65, 66.

  The steel support washer 57 comprises positioning pins 69 in number equal to that of the segments, here three, and intended to facilitate the respective positioning of said segments. These positioning pins 69 cooperate with bores 72, Figure 6, formed in the segments 64,, 66 to ensure their precise positioning. Once angularly positioned, these two by two present a circumferential clearance of

around 0.1 mm.

  The piston-carrying tube 46 is of axial length slightly greater than that of the piston 11, so as to protrude a little at the front thereof, to allow the mounting of a so-called self-centering washer 49. For this purpose, the piston-carrying tube 46 has at its front end, FIG. 2, a shallow groove 48, better visible in FIG. 9, the function of which is to serve as a support for the self-centering washer 49. This shallow groove 48 comprises preferably a non-vertical front flank 52, and for example

tilted at 45.

  The self-centering washer 49, of the "Belleville" type, is of slightly frustoconical shape before mounting, as shown in solid lines in FIG. 9. Its thickness is for example from 0.5 to 0.6 mm. It has a series of elastically deformable nozzles 50 on its inner periphery distributed angularly in a regular manner, for example every 45, and forming, with the annular part of the self-centering washer 49, a dihedral

  curved identical for all the spouts.

  When mounting the clutch release bearing 18 on the receiver 8, the self-centering washer 49 is placed in the axis of the piston holder tube 46, then is pushed using a punch 51, as is seen in FIG. 9, in the groove 48, in which, by deformation, the ends of the spouts 50 take place. The Belleville washer is chosen so as to have a deflection curve as a function of the applied force having a flat range, corresponding to a significant deformation possible while maintaining a constant specific force applied to the washer. It is this characteristic

  which is used to deform the spouts 50 in this range during assembly.

  The non-rotating ring 27 of the stop 18, bearing on the front face of the piston 54, serves as a counter tool during this operation. After mounting, the spouts 50 bear by their end edges 53 on the front flank 52 of the groove 48 of the piston holder tube 46. The self-centering washer 49 then produces a force on the non-rotating ring 27 of the stopper declutching, thus causing the desired axial locking of the stopper 18 which retains a freedom of radial movements for its centering, as

known per se.

  It is understood that the assembly of the piston 11 and the piston support tube 46 is completed by the self-centering washer 49 which serves not only to axially block the stop 18 against the piston, but also to block the piston 11 against the annular flange 47 of the piston holder tube 46. This washer 49 remains generally in transverse orientation after assembly, only the spouts 50 are deformed. Here we amplified the deformation of the washer

49.

  Referring to Figures 1 and 2, it can be seen that the guide tube 22 carries at its front part, on the left in the figures, a stopper 29 intended to axially limit the stroke of the piston 11. The stopper 29 consists, Figure 10, of a washer of the "Belleville" type comprising a frustoconical ring 40 whose internal part is extended along lugs 41 directed on the convex side relative to the ring 40 at an angle with it, here of 90 degrees; the legs 41 each end with a flange

  hook terminal 42 directed towards the side of the ring 40.

  The guide tube 22 has at the front end of its cylindrical section 39 a groove 43 formed on its internal face 44 and adapted to receive the flanges 42 of the tabs 41 of the stopper 29. When mounting the stopper stop 29, the frusto-conical ring 40 is tilted using a tool to its flat configuration and the legs 41 are introduced into the guide tube 22 until the flanges 42 of the legs

  41 take their place in the groove 43 of the guide tube 22.

  In this position, visible in FIG. 11, the frustoconical ring 40 takes the form of a substantially plane ring perpendicular to the axis of the tube

guide 22.

  It will be appreciated that the outer periphery of the guide tube 22 is smooth at its front end. Thanks to the stopper 29 the length can be reduced

  axial of the tube 22 or increase the guide length thereof.

  The operation of the receiver 8 according to the invention is identical to

  that of a conventional concentric receiver and will not be detailed here.

  Many variations can be considered depending on the

circumstances of use.

  In a variant relating to the method of mounting the guide tube 22 in the groove 32 of the outer body 21, the guide tube 22 has an initial diameter, before mounting, slightly greater than that of the internal face 35 of the outer body 21, and the size chips during installation in the groove 32. The scope of the present invention is not limited to the details of the above embodiments considered by way of example, but extends

  on the contrary to modifications within the reach of the skilled person.

Claims (10)

  1. Receiver (8) of the concentric type for hydraulic control comprising, on the one hand, a fixed part (9) composed of an outer body (21) and a coaxial cylindrical guide tube (22) and, on the other part, a piston (11) slidably mounted coaxially with the fixed part (9) and defining there a variable volume chamber (13) intended to be connected to the hydraulic transmitter of the hydraulic control, characterized in that the head (63 ) of the piston (11) comprises at least two segments (64,65,66) in an arc of a ring assembled, by means of a positioning means (57), into a ring carrying a seal (68) intended to ensure sealing variable volume chamber (13) 2. Receiver according to claim 1, characterized in that the head of   piston (63) has three segments (64, 65, 66) in a ring arc.   3. Receiver according to any one of claims 1 or 2,   characterized in that the segments (64, 65, 66) in an arc of a ring each carry a lug-shaped sculpture (67) oriented towards the chamber variable volume (13).   4. Receiver according to any one of claims 1 to 3,   characterized in that the means for positioning the segments (64,65,66)   in a ring arc is a metal support washer (57).   5. Receiver according to claim 4, characterized in that the support washer (57) comprises positioning lugs (69) cooperating with bores formed in the segments (64,65,66) in ring arc for   ensure their precise positioning.   6. Receiver according to any one of claims 4 or 5,   characterized in that the support washer (57) has a recess (55) on its internal periphery intended to receive radial edges (55) of guide pads (28).   7. Receiver according to any one of claims 1 to 6,   characterized in that the ring arc segments (64, 65, 66) have   on their rear face a staircase ledge (61).   8. Receiver according to claim 7, characterized in that the piston carrying tube (46) has a transverse flange (47) disposed inside the staircase ledge (61).   9. Receiver according to claim 8, characterized in that the staircase rim (61) is of width greater than the thickness of the transverse flange (47) of the piston-carrying tube (46), thus defining an axial clearance (62) of the piston holder tube (46) in its housing inside the staircase rim (61) of the piston head (63).   10. Receiver according to any one of claims 1 to 9   characterized in that the seal (68) is in the form of an O-cup.