FR2626337A1 - Torsion damper with viscous damping and double damping flywheel including such a damper - Google Patents

Abstract

The present invention relates to a damper with viscous damping 33 provided with radial fins 31, 32. According to the invention, the damper is characterised in that the cavity is partially filled with a fluid so that, after a defined angular deflection between the two parts, it passes from an air throttling mode to a fluid throttling mode by passing through the calibrated passages 36, 38, etc. Application: double damping flywheel.

Description

 The present invention relates to a torsion rtisseur, in particular for a motor vehicle, of the kind comprising at least two coaxial parts mounted to rotate relative to each other, elastic tens with circumferential action functionally interposed between these two masses and a mechanically viscous damping arrangement interposed between said two parts and confined within a sealed cavity. It also relates to a double damping flywheel comprising such a damper.

 Such a shock absorber is described in document FF-86 08835 filed on 19.06.1986.

 This teaches filling the cavity fully with a viscous fluid, preferably not Newtonian, to mount in it groups of fins respectively integral in rotation with said masses, and to create calibrated passages between consecutive fins.

 The fluid is laminated inside the cavity by the relative movements of the two groups of fins, this rolling producing a damping and therefore phenomena of hy-steresis.

Due to the filling of the chamber, the hysteresis cannot be as low as desired, in particular for good filtration of neutral noise when in a motor vehicle the engine is running at idle speed.
In addition, the rotating joints provided to seal the chamber are in constant contact with. the fluid, which is not good for the life of these.

 To reduce hysteresis while having, for example when starting and stopping the engine for example a strong hysteresis, one can consider adopting a provision with friction washers, one of which only adds its effects after a certain angular movement between said parts, as described in application FR-86 18152 filed on 24.12.1986.

Such an arrangement only involves dry friction, so that the damping torque is constant and can vary over time, in particular as a function of wear,
The object of the present invention is to overcome these drawbacks and therefore to create a viscous damping arrangement which makes it possible to decrease the hvstresresis for the small relative deflections between the two parts while increasing the lifetime of the seals, by involving hysteresis stronger after some movement between the two sides and providing other benefits
A torsion damper of the aforementioned kind, in which the viscous damping arrangement with calibrated passages comprises inside the cavity two groups of eaglets respectively integral in rotation with said masses, each group of fins generally extending in radial planes by being coupled to a carrier element one, d5t internal carrier element being disposed inside the other, called external carrier element, any fin of one group being inserted circumferentially between two fins of the other group and in which the cavity is sealed at its internal periphery by at least one rotating joint is characterized in that the cavity is partially filled with a fluid, so as to pass, after an angular displacement determined between the parts, of a mode of air rolling in a fluid rolling mode by passage through the calibrated passages.

 Thanks to this arrangement for small relative angular deflections between the two parts, the chambers delimited by two adjacent fins vary and air is transferred from one chamber to the other, one decreasing in volume while the other increases in volume. It is only from a determined angular deflection that one of the pressurized chambers fills completely with fluid, then that this is transferred into the other chamber through the calibrated passages, producing a damping by rolling of fluid.

 The hysteresis can therefore be low for small deflections and then high for larger deflections, and it is only from this deflection that the rotary joint is subjected to the action of the fluid. This is particularly advantageous in the context of a double damping flywheel in which a high hysteresis is sought when the vehicle is started and stopped, while having a low hysteresis for filtering neutral noise.

it will be appreciated that the damping can therefore be easily known and controlled, for example by playing on the calibrated passages and possibly on the viscosity of the fluid. The device can therefore be economical and operate with any type of fluid
Newtonian or not Newtonian. In addition, the shock absorber has advantageously faithful and reproducible operating characteristics.
It is even possible, in certain cases, to dispense with the presence of a torque limiter.

 Circumferentially, the fins have a generally trapezoidal shape and are mounted head to tail from one group to another. A good distribution of the material favorable to good resistance as well as an optimization of the volume of fluid are thus obtained. It is arranged so that in position of mutual contact, the flanks of the fins match.

 According to another characteristic, for a good connection of characteristics between the two hysteresis, provision is made for the creation of at least one air reserve thanks to a recess provided in the internal carrier element.

 n trapping air we introduce elasticity which improves the connection. It can also be improved by varying the volume of certain chambers delimited by neighboring fins.

 Special shapes can be provided on one of the load-bearing elements and on the fins.

 Anyway, we are sure that the jump of hysteresis will not cause annoying shocks. All these provisions constitute various solutions of anti-shock means housed in viscous damping.

 According to another characteristic, the rotary joint is disposed at the end of a protective passage with a high pressure drop greater than that of the calibrated passage.

 This arrangement further improves the longevity of the seal since the fluid will preferably pass through the calibrated passage.

The description which follows illustrates the invention, in the context of a double steering wheel for a motor vehicle, with reference to the appended drawings in which
- Figure 1 is an axial sectional view of a double damping flywheel according to the invention
- Figure 2 is a sectional view along the line II-II of Figure I;
- Figure 8 is an enlarged view identified by the insert 3 of Figure 1;
- Figure 4 is a partial view in the direction along the arrow f of Figure 1 t
FIG. 5 is a partial view similar to FIG. 1 for another alternative embodiment,
- Figure 6 is a half view similar to Figure 2 for this alternative embodiment ;;
- Figure 7 is a half view similar to Figures 2 and 6 for another alternative embodiment;
- Figure a is a partial view in axial section showing the recess for another alternative embodiment.

 In Figure 1 we see in 1 a first part, here a mass of inertia, integral with the nose A of the crankshaft of the motor vehicle by means of screws 2. This mass comprises a flange 3 which carries the starter ring 3 ' and is connected, at its outer periphery, to another flange 4 by means of a spacer crown 5. This crown 5 is linked to the flange 4 by countersunk head screws 7 and to the flange 3 by screws 8, which also fix a washer 9 on which the crown 3 'is forcibly mounted.

 In the flanges 3 and 4 are made windows 10 for housing elastic elements 11, here coil springs, which bear on the contours of said windows 1a by means of bases 12. A web 13 is disposed centrally between the flanges 3 and 4 and carries radial arms 14 with circumferential fingers 15 adapted to attack the bases 12 after taking up a clearance.

All these provisions are described in the request
FR-A-2 571 461.

 The web 13 is secured by screws 16 to a connecting plate 17 linked by screws 18 to a removable reaction plate 19. It is on this reaction plate that the clutch friction disc is able to act.

This reaction plate 19 therefore belongs to a second part 20, coaxial with the first, and the elastic elements 11 are therefore functionally interposed between the two coaxial parts 1.20. A bearing 21 is mounted between the connecting plate 17 and a hub 22 connected to the nose of the crankshaft A by the screws 2. The web 13 has a tortuous shape and is present at the base of its arms 14 FIG. 2> a crown 23, of which comes from a transversely open wall 24 centrally. a crown 23 axially forms a skirt and it is in this that the screws 16 are fixed. The wall 24 is parallel to the face 25 of the connection plate 17 turned opposite to the reaction plate 19. wall 24, crown 23, connection plate 17, forming walls and belonging to the second part or mass 20, therefore delimits an annular cavity 26 with parallel walls partially sealed by contact of the ring 23 with the connection plate 17, which has a centering range for this purpose. This cavity 26 is further delimited by a carrier element 27 engaging in the central opening of the wall 24.

 As shown in FIG. 1, this carrier element 27, integral with the mass 1 and arranged inside the skirt 23, is preassembled to the hub 22 and to the flange 3 respectively by screws 28, 29 while being traversed by the screws 2.

 Between the internal periphery of the wall 24 and the support element 27 is interposed a rotating seal 30.

 Inside the cavity 26 are arranged two groups of fins 31, 32, respectively integral in rotation with the coaxial masses 1.20. More specifically, the annular skirt 23, said here for convenience of external support element, carries the first group of fins 31, which protrudes radially internally in the cavity 26, while the support element 27, said here for convenience of internal support element , also annular, disposed inside the skirt 23, carries the fins 32 which project radially, in the cavity 26 externally relative to the element 27.

 The fins 31, 32 extend generally in radial planes passing through the common axis (X, X ') of the double flywheel and any fin of a group is inserted circumferentially between two fins of the other group.

 A viscous arrangement 33 with fins 31, 32 is thus created and the latter is mechanically interposed between the two masses ltZO while being confined within the sealed cavity 26 disposed closer to the axis than the springs 11. It will be noted that the bearing 21 is sealed and that it contributes to the sealing of said cavity 26.

As can be seen in FIG. 2, it will also be noted that the fins of constant thickness generally have a trapezoidal shape, being head to tail, and that the hub 22 has, for the internal element 27, a centering surface 221 of small diameter. connecting to a transverse support shoulder 22 '' generally in alignment with the face 25 after mounting.

 According to the invention the cavity 26 is partially filled with a fluid t so as to pass, after a determined angular movement between the parts, from an air rolling mode to a fluid rolling mode through the calibrated passages .

lei the free edges 34 of the fins 31 are judiciously spaces from the external surface 35 of the carrier element 27 by defining a calibrated passage 36,
The free edges 37 of the fins 32 are also spaces of the internal face 50 of the skirt 23 by a calibrated passage 38. Narrow passages exist, on the one hand, between the fins 31 and the walls 24-17 (25) and, on the other hand, between the fins 32 and said walls 24-17 (25) All of these narrow and calibrated passages 36,38 defines a calibrated passage (36, 38 ...) between two consecutive fins 31,32.

Several chambers are thus defined between two consecutive fins.

 To explain Iefonctionn-ement, for simplicity we will consider three successive chambers D, 13 and C Figure 2) assuming that the veil 13 moves relative to the carrier member 27 in the direction of arrow f.

 When the engine is running, the fluid is centrifuged towards the skirt 23 and air is present in the lower part of the chambers D, B and C.

During a first phase, the volume of chamber 13 decreases while that of chambers C and D increases and air is transferred from chamber B to chambers C and D through the calibrated passage (26, 38 ...) defined above between two successive 1.32 fins. Chamber B pressurizes while chambers C and D depressurize, the free surface of the fluid in the chamber
B approaching radially the outer periphery 35 of the element 27, while the free surface of the fluid in the chambers C and D moves away from this periphery.

 From a certain relative angular movement between the two masses 1 and 20, the chamber B is completely filled with fluid, the free surface of the latter coming into contact with the periphery 35, then during the continuation of the movement, during a second phase, fluid is transferred from chamber 13 to chambers C c and D through the calibrated passage (36, 28 ...). This results in a rolling of the fluid and, by the pressure drop that must be overcome for this transfer of room, by a stronger damping torque than during the first phase, on which the damping torque depends for the essential of the friction of the joints. The hysteresis is thus variable, from one phase to another, like the damping torque.

The return to the rest position is effected by transfer of liquid from chambers C and D to chamber B.

To avoid a hysteresis jump that is too large and therefore giant shocks, provision is made for the creation of anti-shock means within the viscous damping arrangement.
In FIGS. 5 and 6, it is formed from an air reserve 40 formed locally by means of a recess 41 formed in the internal bearing element '27, at the foot of the fins ~ 32 and on either side of these * This recess 41 is formed centrally at the outer periphery 35 of the element 27 and is delimited by two edges 42,43.

Thus the free surface of the fluid of the chamber B coming into contact with the periphery 35, air is trapped in said recess 41 thus creating an elastic buffer
It will be noted that the penetration of the free surface of the fluid into the recess 41 is a function of the pressure drops for transferring the liquid and therefore of the pressure of the fluid in the chamber E. The higher the pressure, the more the fluid descends into the recess , All this is a function of the displacement of the toothing 31,
This elastic buffer improves the connection between the hysteresis of the first phase and of the second phase, so that the jump is less abrupt and the shocks less annoying.

 According to another characteristic and as best seen in FIG. 3, for all the embodiments according to the invention, provision is made for the creation of a protective passage 44 with a high pressure drop, greater than that of the calibrated passage (36, 38 ...).

 More precisely, the fins 32 are narrower than the carrier element 27 which penetrates radially into the cavity.

 We identified by J the game mistletoe separates the carrier element 27 from one of the walls 24,17, the same game or a different game that may exist between the carrier element 27 and the other wall 24,17.

 The narrow passage 44 is therefore a function of this play. As a variant, the support element 27 can have the same thickness as the fins 32 and the narrow passage 44 is then cleaned thanks to at least one axial projection present at the internal periphery. of the cavity. It is therefore less wide in this case at its internal periphery.

 Thanks to this arrangement, a sir operation is obtained and the seal 30 is well cleaned because the 'fluid will preferably pass through said calibrated passage (36, 38 ...) and the passage 44 can be defined as a protective passage.

 Alternatively, Figure 8 ,. instead of digging the support element 27, said recess 41 can be produced using two side plates 45,46 higher than the support element. The sheet 46 has an axial return 46 for cooperation with the seal 30 housed, as in FIG. 3, in a groove 49 formed at the internal periphery of the wall 24. It will be appreciated that the support element 27 is simplified because its central part 27 '' massive is reduced to a ring, so that the machining of said element is simplified.

 As a variant, it is possible to make suitable shapes at the internal periphery 50 of the skirt 23. As can be seen in FIG. 7, the internal face 50 of the skirt 23 is stepped and has a central portion 51 opposite the free edge 37 then a second portion 52 arranged on either side of the portion 51, and finally a portion 53 extending the portion 52 to the feet of the fins 31.

 These various portions are connected to each other by inclined portions 54.

 As will be understood, the radial jet between the free edge 37 and various portions is maximum at the level of the portions 51 and then decreases to the portion 53, which makes it possible to vary the level of hysteresis according to the relative angular movement between the two parts 1.20.

 As a variant, as shown in the lower part of FIG. 7, the free edge 37 can be rounded.

 Finally, it is possible, for example, to dig the free edge 37, as visible in dotted lines, in order to have an expansion of the fluid during its flow through the calibrated passage 38.

 As is evident from the drawings, the flanks of the fins 31, 32 conform to conform to each other when the fins come into contact with one another and the clearance between the fins 31 and the walls 24, 17 is negligible so that the calibrated passage (36, 38 ...) depends on the fins 32 and the walls 24, 17 as well as the passages 36, 38.

 Of course, the present invention is not limited to the embodiments described, but encompasses any variant and / or combination of their various elements, in particular the double damping flywheel can be fitted with a torque limiter as described in the addiction certificate FR-87 04954. The external load-bearing element can be added by being force-fitted in the skirt 23 or in the skirt defined in the connection plate as explained above. The fins can also be attached. Similarly, a second seal can be provided between the plate of ison-17 and the hub 22, and the external periphery 35 of the support element 27 can be stepped like the face 50 or like, for example , shown in Figure 7.

 That is to say that the height of the carrier element can vary, which causes an asymmetry in the chambers and makes the jump of hysteresis less brutal. As a variant, the variation of the chambers can be obtained using fins of different width. It is of course possible to combine the two forms. Anyway the jump of hysteresis will be less brutal and by these modifications of form of certain rooms, one obtains an anti-shock means.

 Finally, the invention applies to clutch friction discs.

Claims (5)

 1) Torsional damper, in particular for a motor vehicle, of the type comprising at least two coaxial parts (1,20) mounted to rotate relative to one another, elastic means (11) with circumferential action, functionally interposed between these two parts <1.20) and a viscous damping arrangement (33) with calibrated passages (3d, 38 ...) interposed between said parts (1.20) and confined within a sealed cavity (26) , in which the viscous damping arrangement (33) comprises, inside the cavity (26), two groups of fins (31,32), respectively rotationally integral with said masses, s1 extending generally in radial planes being coupled each to a carrier element (27, 23), one, said internal carrier element, has inside the other, said external carrier element, any fin (31,32) of a group being interposed circumferentially between two fins (32,31) of the other group and in which the cavity is sealed at its internal periphery by at least one rotary joint (30), characterized in that the cavity (26) is partially filled with a fluid so as to pass, after an angular movement determines between the two parts (1,20) , from an air rolling mode to a fluid rolling mode by passage through the calibrated passages (36, 38 ...).  2) Shock absorber according to claim 1, characterized in that the viscous damping arrangement (33) is provided with anti-shock means (40, 51, 52, 53, ...).  3) Shock absorber according to claim 2, characterized in that the anti-shock means consists in at least one recess (41) formed at the periphery (35) of the internal support element (27) at the foot of a fin (32 ).  4) Shock absorber according to claim 3, characterized in that the recess (41) is made using tolets (45, 46) higher que.l'élément internal carrier (27).  5r damper according to claim 1 or 2, characterized in that the periphery (35, 50) of the carrier element is stepped.  6> Damper according to claim l or 2, characterized in that the volume of the chambers (D, B, C. *.) Delimited by two consecutive fins (31,32) is variable.  7) Shock absorber according to any one of the preceding claims, characterized in that the rotary joint (30) is disposed at the end of a protective passage (44) so as to create a pressure drop greater than that of the existing calibrated passage between two successive fins (31,32).  8) Shock absorber according to claim 7, characterized in that the narrow passage t44) is produced by an additional thickness of the internal support element (27) relative to the fins (32) integral with the latter.  9> Double flywheel, characterized in that it comprises a torsion damper according to any one of claims 1 to 8.