ITRM20000315A1 - DOUBLE SHOCK ABSORBER FOR VEHICLE. - Google Patents

Description

DESCRIPTION OF THE INDUSTRIAL INVENTION entitled: "DOUBLE FLYWHEEL SHOCK ABSORBER FOR MOTOR VEHICLES"

The invention refers to a double shock absorber flywheel for motor vehicles, with a simple and economical structure, and more precisely to a double shock absorber flywheel intended to couple in rotation around a general axis a crankshaft of the engine of this vehicle to a mechanism of clutch filtering the torsional vibrations emitted by the engine, comprising two flywheel elements, a primary element to be made integral in rotation with the end of the crankshaft and a secondary element to be made integral in rotation with the transmission input member , and coupling means connecting these flywheel elements with an angular oscillation and consisting of elastic means which act circumferentially against a transmitted torque, and shock-absorbing means consisting of a stack of friction rings centered on the general axis of the flywheel and tightened each other against the others by means of an axial action spring means, these crowns being dragged inate in relative angular oscillation in response to angular oscillation between the flywheel elements, the spring means being constituted by two sets of springs arranged in succession in a toric housing centered on the central axis of the flywheel, thrust elements being arranged to press against the opposite ends of the spring assemblies to compress them when the transmitted torque angularly displaces the elements.

It is known that such an arrangement allows excellent filtering of the torsional oscillations emitted by the engine, particularly at low speeds, with consequently a considerable reduction in noise, in particular in the gearbox.

In order to fully benefit from the filtering effect, the coupling means are of large angular oscillation. Currently, the resilient means are long coil springs which are frequently pre-curved to be disposed in the toric housing. Due to the speed of rotation of the motor and their almost semicircular shape, these springs, subjected to a centrifugal force that can reach considerable values, are applied against the periphery of their toric housing, which blocks the oscillation. It is therefore necessary to provide a low-wear gasket between the springs and the periphery of the O-ring housing, and to fill the O-Ring, at least partially, with grease, so that the angular oscillation between the flywheel elements is not impeded by the effects of force. centrifuge, as described in document FR-A-2 601 104; this solution is burdensome, especially as it is not desirable for the fat to enter a graft mechanism.

It is proposed in document US-A-4 484 898 to make a group of springs arranged circumferentially working in series, by means of said timing washers; it is a relatively complicated device, the secondary element being provided with retaining parts to lock the springs and prevent centrifugal force from squeezing them against the periphery of the toroidal housing although the individual springs are short; the flywheel described comprises three groups of three springs which work in series.

Document FR-A-2741 928 discloses such a double shock absorber flywheel comprising a primary flywheel intended to be connected to the crankshaft of the vehicle engine, a secondary flywheel intended to receive an engagement mechanism, torsion-action shock absorber means circumferential being kinematically arranged between the primary and secondary flywheels, the shock-absorbing means comprising elastic means associated with friction means, said elastic means being constituted by at least one group of springs which act in series by means of timing washers, support seats and locking seats being provided for said springs, which are distinguished by the fact that said support seats and locking seats are integral with timing washers.

This arrangement leads, due to the angular dimensions of the support and locking elements inserted between the individual springs and the multiplication of these springs, to a reduction of the total angle of possible oscillation, while the seat of the timing washers on the hub of the primary flywheel, which ensures that they are kept centered, is subjected to the centrifugal force exerted on the support and locking elements, which requires that this seat be treated to have a reduced friction coefficient in order to contribute only in a reduced way to the '' damping of the oscillation between the primary and secondary flywheels in such a way that this is not too variable with the rotation speed.

It will be observed that these double flywheels do not have in themselves privileged directions of rotation, and therefore remain effective when the transmitted torque is reversed, the transmission dragging the motor (motor brake).

To remedy the shortcomings of the double shock absorber flywheels of the state of the art cited above, the invention proposes a double shock absorber flywheel for motor vehicles, designed to couple in rotation around a general axis a crankshaft of the engine of this vehicle to a mechanism of clutch filtering the torsional vibrations emitted by the engine, comprising two flywheel elements, a primary element to be made integral in rotation with the end of the crankshaft and a secondary element to be made integral in rotation with the transmission input member , and coupling means' which connect these flywheel elements with an angular oscillation and consist of elastic means which act circumferentially against a transmitted torque and shock-absorbing means constituted by a stack of friction crowns centered on the general axis of the flywheel and tightened each other against the others by means of an axial action spring means, these crowns eg being driven into relative angular oscillation in response to angular oscillation between the flywheel elements, the elastic means being constituted by two sets of springs arranged in succession in a toroidal housing centered on the general axis of the flywheel, thrust elements being arranged to press against the opposite ends of the groups of springs to compress them when the transmitted torque angularly moves the elements, double flywheel characterized by the fact that each group of springs is made up of a continuous structure with multiple coils which occupy, in the absence of the transmitted torque, a reduced semicircle of an interval in which two thrust elements are housed, offset radially and in respective projection from each element of the flywheel parallel to the general axis, these structures crossing each of a plurality of retaining collars arranged at a substantially regular angular spacing, and each crossed collar from one structure being connected diametrically by means of a ring spacer to a collar crossed by the other structure.

It is understood that, on the one hand, the structures of springs used are particularly simple and that the amplitude of the allowed oscillation is practically limited only by the compression capacity of the springs which occupy almost a semi-circumference at rest, and that, on the other hand On the other hand, the attachment of the retaining collars by two to diametrical points of a ring spacer cancels the resultant of the centrifugal forces exerted on the retaining collars and the spring structures in the areas of crossing of the collars by these structures. In this way practically all the frictions which are a function of the rotation speed of the flywheel are eliminated.

Preferably, the multiple-turn structures comprise two common circular-axis helices, one right-handed and the other left-handed, with one housed concentrically in the other.

This classic arrangement makes it possible to use two springs of different stiffness in parallel without the coils of one helix inserting between the coils of the other.

A convenient number of rings in each multiplicity is three, which is a good compromise between keeping the springs in shape and the amplitude of swing allowed.

It is convenient for the ring spacers to have two fins protruding diametrically from the external periphery, comprising at their ends an area for fixing a retaining collar.

It is therefore preferred that the fins of at least some of the ring spacers comprise, between the spacer and the fixing area, a double curvature which creates an offset, with respect to the general median plane of the spacer, of a parallel median plane in common of areas of fixing, this offset being at least equal to the thickness of a spacer. The spacers can thus be stacked, the median plane of the assembly of the fastening areas being in common and coinciding with the plane of the circular axis of the spring groups.

Preferably, the collars comprise pads adapted to slide on surfaces of revolution around the general axis of the flywheel, surfaces belonging to one and the other of the elements of the flywheel and laterally delimiting the annular housing of the groups of springs.

The combination of the shoes and the surfaces of revolution on which they slide ensures the centering of the annular spacers around the general axis of the flywheel, and consequently the balancing of the centrifugal forces exerted on these spacers.

It is preferred that one of these surfaces is cylindrical, belongs to the primary element and constitutes the outer periphery of the annular housing.

According to a preferred arrangement, the retaining collars comprise a fin in internal radial protrusion which engages between two turns of the crossed structure. This arrangement ensures that the collars constantly rest on the same coils, and maintain their relative angular distributions as the springs see their compression rate change.

However, this makes it possible to use the annular spacers as cushioning friction rings, which avoids the use of separate friction rings.

In a classical way, the two ends of each group of springs are provided with heads arranged to rest on thrust elements protruding from the two elements of the flywheel. Preferably then, at zero transmitted torque, the heads rest on the thrust element protruding from one of the elements of the flywheel, while the thrust element protruding from the other element is susceptible to oscillation between the heads. It is understood that for weak oscillations, the heads of the springs rest, in each interval, on the thrust element protruding from a first element and that the second element can move angularly with respect to the first without compressing the springs, until the thrust element protruding from this second element it does not rest on a head.

It is preferred that the thrust elements which, at zero transmitted torque, rest on the heads are those which protrude from the primary flywheel element, in particular for ease of assembly. According to an arrangement of the invention, the heads have a face, turned towards said intervals, in a convex protuberance in a plane perpendicular to the general axis of the flywheel, and in this face a mouth parallel to this axis into which a temple formed in the element protruding from the flywheel element, here called first, which rests on the heads, with zero transmitted torque, while the thrust elements protruding from the second element include, towards one and the other of the heads, complementary housings of these protuberances, and a opening according to the circular axis of the annular housing which allows the thrust element protruding from the first element to pass.

This arrangement ensures a radial seal of the heads against centrifugal forces, both by engaging a rod of the thrust element protruding from the first element in the opening facing it, and by engaging the protuberance in the complementary housing obtained in the thrust element. protruding from the second element when, by means of angular offset of the second element, this thrust element, by letting the thrust element protruding from the first element pass through the opening, makes contact with the head, which disengages the temple from the opening.

According to another arrangement of the invention, the heads are contained in retaining bracelets connected two by two by means of ring spacers. The retaining bracelets play, for the ends of the springs, the same role as the retaining collars for the areas crossed by the springs.

The retaining bracelets may have gaskets, which rest on at least one face of the toric housing.

It is preferred that the ends of at least one spring of each structure be curved outwardly of the coil, and that the heads include passages made for these curved ends, so that the latter are oscillatingly connected to these heads.

The characteristics and advantages of the invention will moreover result from the following description, with reference to the attached drawings in which:

Figure 1 is a cross-sectional view along the plane I-I of Figure 2, of a double shock absorber flywheel according to the invention;

Figure 2 is a section according to II-II of Figure 1;

Figure 3 is a plan view of a ring spacer of the double shock absorber flywheel of Figures 1 and 2;

Figure 4 is a partial view of the representation of Figure 1 when the angular oscillation between the elements of the flywheel is maximum;

Figures 5A and 5B show, in two directions and partially sectioned, a ring spacer centering pad;

Figures 6A, 6B and 6C show, in longitudinal section and in front and rear views, a spring head;

Figures 7A and 7B show, in plan and in section according to VIIB-VIIB, a stacking of ring spacers;

Figure 8 is a section, according to the plane VIII-VIII of Figure 9, of a variant of the flywheel of Figure 1;

figure 9 is a section according to IX-IX of figure 8;

Figures 10A and 10B are similar to Figures 5A and 5B of a flywheel shoe of Figures 8 and 9;

Figure 11 is a detail of a second arrangement of a double shock absorber flywheel according to the invention;

figure 12 is a section, similar to those of figures 2 and 9, of the flywheel of figure 11;

Figure 13 is a section, similar to that of Figure 12 but angularly offset, of a variant of the flywheel of Figure 11;

Figures 14A, 14B, 14C, 14D show different arrangements of the fastening of a retaining collar on a centering pad.

According to the embodiment selected and represented in Figures 1 and 2, a double shock absorber flywheel according to the invention comprises a primary flywheel element 1 as a whole, to be mounted on the end flange of a crankshaft of the engine of a motor vehicle ( from the left of Figure 2) and comprising a plate 10 in drawn sheet of revolution around a general axis x-x 'which ends at its outer periphery with an edge 12 extending parallel to the axis, x-x'; in the center of this plate 10 there is a hole 10a for centering on the flange of the crankshaft; a sleeve 14 following the hole 10a is riveted to the plate 10 and includes holes for fixing bolts on the crankshaft flange. A crown 11 is mounted and welded around the edge 12, with an external toothing for starting the engine; this crown, in addition to its starting role, brings, through its relatively large mass and diameter, a considerable moment of inertia.

On the sleeve 14 of the primary flywheel element a secondary flywheel element 2 is rotatably mounted as a whole, by means of an L-section bearing seal 15, made of low friction material. A flat annular plate 16, tightened at the end on the sleeve 14 of the primary flywheel element 1, ensures the axial retention of the secondary element on the primary element. The annular face 20 of the secondary element 2, unlike the primary element 1, is flat and perpendicular to the general axis x-x 'of the flywheel; it is arranged, in a classical manner, to serve as the reaction plate of a clutch mechanism at the entrance to the vehicle transmission. The elements of the primary 1 and secondary 2 flywheel are connected, with a limited angular oscillation, by coupling means constituted by elastic means 3, 3 'and by shock-absorbing means 5, in their assemblies. The elastic means 3, 3 'act circumferentially against a torque transmitted from the engine to the transmission. They are circular and arranged in a toric housing 6, centered on the general axis x-x ', and consisting of the plate 10 and the edge 12 of the primary element 1, and a thinning of the secondary element 2 in the face opposite to the face 20 , and around a hub 24. As can be seen in Figures 1 and 2, the elastic means comprise two continuous structures 3, 3 'with multiple coils each consisting of two helical springs 30, 31 and 30', 31 ', one right-handed and the other left-handed, one housed concentrically in the other. It should be remembered that this arrangement, which allows to play on the rigidity of the spring structure, also prevents the coils of the internal spring from being lodged between the coils of the external spring.

The structures 3, 3 'are hooded, at their ends by heads 32 and 32' 'for the structure 3 and 32' and 32 '' 'for the structure 3'; in the position shown in Figure 1, in which the transmitted torque is zero, the heads 32 and 32 '' 'rest on a thrust element 13 protruding from the primary flywheel element 1 in the toric housing 6, and the heads 32 'and 32' 'on a thrust element 13' also protruding from the primary element 1. These thrust elements 13 and 13 'are cylinder arc blades located on the circular axis of the springs 30, 31, 30', 31 ' . On the other hand, when there is a transmitted torque, such as the maximum torque as shown in Figure 4, the angular oscillation of the secondary flywheel element 2 with respect to the primary element 1 carries the thrust elements 21 and 21 ', protruding from the element secondary 2, in contact with respective heads 32, 32 'to compress the spring structures 3 and 3'. The thrust elements 21 and 21 'are in two parts between which the rounded heads 32, 32' 'engage, parts offset radially with respect to the thrust elements 13, 13' protruding from the primary element, which can thus pass through them. It will be observed that there is a small arc at the start of the swing in which the pushers 21, 21 'do not rest on the heads 32, 32' so that there is no spring torque to recall, which is conducive to filtering. torsional vibrations of the engine at idle and with the transmission disconnected.

The total oscillation between the elements of the flywheel is established at ± 70 ° of which ± 14 ° of oscillation without elastic return.

It is evident that the shape of the spring structures, substantially in a semicircle (≡ 72 °) gives them almost no resistance to the centrifugal force when the flywheel rotates around its axis, given that with the rotation speeds of modern engines this centrifugal force is considerable. To prevent, under the effect of this centrifugal force, the structures of the springs 3, 3 'from applying against the edge 12 and locking therein, around each structure 3 and 3', and at an angular spacing substantially regular, three retaining collars 41b, 42b, 43b for the structure 3 and 41'b, 42'b, 43'b for the structure 3 '. As can be seen more clearly for the collars 42b, 42'b in Figure 3 these are fixed to fins 42a, 42'a projecting from the periphery of a ring spacer 42, so that the centrifugal forces suffered by the structures 3 and 3 ' and transmitted to the retaining collars 42b and 42'b and to the ring spacer 42 are balanced. This is the same for complexes 41, 41b, 41'b and 43, 43b, 43'b.

Since the balance of forces implies that the ring spacers are exactly centered on the general x-x 'axis of the flywheel, the collars 41b, 42b, 43b, 41'b, 42'b, 43'b are equipped with shoes 41c, 42c , 43c, 41'c, 42'c, 43'c respectively, which straddle the structures of the springs 3, 3 'and are capable of sliding on the inner face of the edge 12 of the primary flywheel element 1. Figures 5A and 4B better show the shape of these shoes 41c-43'c, here 42c with a depression 42d for the passage of the corresponding collar 42b; It goes without saying that these pads are made from low friction printable material.

The restraint of the structures 3, 3 'against centrifugal forces is also obtained, for the ends of these structures, by means of the complementary shapes of heads 32, 32', 32 '', 32 '' 'and of thrust elements 13, 13' projecting from the primary flywheel element 1, and 21, 21 'projecting from the secondary element. Figures 6A, 6B, 6C show in detail the shape of the head 32, the other heads being identical. This head 32 has a convex front face 32a capable of getting stuck in the thrust element 21 which then holds it against the centrifugal force. Furthermore, in this face there is a nozzle 32b parallel to the general axis x-x ', radially on the circular axis of the spring structures 3, 3', in which the temple end of the thrust element 13 engages projecting from the primary flywheel element 1, to block the head radially. The rear face of the head 32 has a housing 32c in which the ends of the springs 30 and 31 engage. This rear face extends with a lip 32d which functions as a shoe resting on the edge 12 of the primary flywheel element 1.

Referring to Figures 7A, 7B, which schematically represent the stacking of the ring spacers 41, 42, 43, it can be seen that the spacer 42, in a median position in the stacking, with its fins 42a, 42'a for fixing the retaining collars, is flat, while the fins 41a, 41'a of the spacer 41 and 43a, 43'a of the spacer 43 are offset by two successive inverse bends so that the riveting areas of the collars are in the plane of the median spacer 42, which is the plane in which the centrifugal forces are exerted on the structures of springs 3 and 3 '.

In parallel with the elastic means 3, 3 ', and between the primary 1 and secondary flywheel elements 2, friction shock-absorbing means 5 are arranged. These means comprise a stacking of crowns including two crowns 50 made of friction material taken between the plate 10 and a rigid crown 51 made integral in rotation, with play, with the secondary flywheel element by means of projections 25 of the hub 24 of this secondary element. A Belleville 52 washer ensures the desired tightening of the chainring stack.

The characteristics of the torsion vibration filter consisting of the double flywheel are determined by the combination of the rotational inertia of the elements of the primary 1 and secondary flywheel 2, the rigidity of the elastic means 3, 3 ', and the damping torque due to the means 5.

The variant of the double shock absorber flywheel shown in Figures 8 to 10B differs from the previous one only in the arrangement of the centering pads, of the ring spacers and of the shock absorber means; consequently, the description will be limited to the differences, which lead to references increased by 100 of the elements described above.

The stacked ring spacers 141, 142, 143 constitute the friction crowns of the cushioning means 105 and are caught between two crowns of friction material 150, 150 'which rest, the first 150 on the plate 110 of the primary flywheel element 1 , and the second 150 'on a crown 153 on which a Belleville washer 152 rests in clamping, the assembly of the shock absorber means 105 being housed in an annular groove 154 welded onto the plate 112.

On the other hand, the centering pads such as 142c comprise a lug 142e projecting inwardly and centrally as a segment of a circle, so as to fit between two adjacent coils of the external spring 130. This arrangement ensures that the pad 142c has an unchangeable relative angular position on the spring structure.

Thus, assuming a sense of angular oscillation corresponding to what is shown in Figure 4, and taking the primary flywheel element as the origin of the oscillations, if the angular oscillation of the secondary element is a, the ring spacer 141 will exhibit an oscillation of 3/4 a, the spacer 142 an oscillation of 1/2 a, and the spacer 143 an oscillation of 1/4 α, - the factors of the oscillations of the spacers 141 and 143 are reversed with the direction of oscillation of the secondary flywheel, becoming 1/4 a and 3/4 a respectively; since the crown 154 is practically made integral in rotation with the primary flywheel element 1, the friction effect in the shock absorber 105, and therefore the damping coefficient of the flywheel, are unchanged whatever the direction of the oscillation. Moreover, in the interval of the oscillation of the thrust elements 121, 121 'between the heads 132, 132' '' and 132 ', 132' 'respectively, in which the compression of the spring structures does not intervene, there is no torque of elastic return, nor friction damping.

The double shock absorber flywheel shown in Figures 11 to 13, the references of which add 200 to the references of the corresponding elements of the flywheel which has been described with reference to Figures 1 to 4, differs from this in the arrangement of the heads from 232 to 232 ' '' and of the thrust elements 221 to 221 '' 'projecting from the secondary flywheel element 202, as will now be specified.

Figure 11 is limited to the ends of the spring structures 203 and 203 ', opposite on either side of the thrust elements 213 protruding from the primary element 201, and 221a, 221b protruding from the secondary element 202. The element thrust 213 is similar to the element 13 of Figures 2 and 3, and also rests, at zero transmitted torque, on the heads 232 of the structure 203 and 232''1 of the structure 203 '. The thrust elements 221a, 221b, protruding from the secondary flywheel element 202 are of a shape similar to that of the element 213 and arranged radially symmetrical with respect to this thrust element, but shorter peripherally to obtain a clearance without return torque for very weak oscillations as in previous devices. Heads such as 232, 232 '' 'have a flat bearing face for the thrust elements. They engage via a groove in a retaining bracelet 244b for head 232 and 245''b for head 232 '' '(heads 232', 232 '' and bracelets 244'b and 245'b are not shown here ); these retaining bracelets are attached two by two (244b, 244'b and 245b, 245'b) in diametrically opposite positions on respective ring spacers 244 and 245 similar to ring spacers 241 to 243 in which the collars of restraint. However, the ring spacers from 241 to 245 are made of thin sheet metal so as to be flexible enough to lend themselves to deformations such that the collars and retaining bracelets are held in the same plane perpendicular to the general axis and passing through the circular axis of spring structures. The assembly of ring spacers 241 to 245 is centered on the hub 224 of the secondary flywheel element 202 by means of a raised flange ring 246 of low friction coefficient material. This ring is for example in several parts to facilitate assembly.

The extreme coils of the external springs 230, 230 'of the structures 203, 203' are curved arc 230a, 230''a (and 230'a, 230 '' 'a not shown, towards the outside, and pass through passages such as 232a in the heads from 232 to 232 '' ', in such a way that these heads are made integral with the ends of the springs 230, 230'.

The balancing of the heads and retaining bracelets with the ring spacers that join them can be made more precise by attaching centering seals made of low friction material to the bracelets in a similar manner to the centering pads of the retaining collars described above.

Figures 14A to 14D show, in a sufficiently explicit way not to require comments, different ways of mounting retaining collars, in one piece (Figures 14A, 14B) or in two pieces (Figures 14C, 14D) on centering pads, with rivets or spot welds for fixing these collars on ring spacers.

Of course, the invention is not limited to the examples described but embraces any variant of execution thereof, within the scope of the claims.

Claims (16)

CLAIMS 1. Double shock absorber flywheel for motor vehicles, designed to couple in rotation around a general axis (x-x1) a crankshaft of the engine of this vehicle to a clutch mechanism, filtering the torsional vibrations emitted by the engine, comprising two elements of flywheel, a primary element (1) to be made integral in rotation with the end of the crankshaft and a secondary element (2) to be made integral in rotation with the input member of the transmission, and coupling means which connect these flywheel elements with an angular oscillation and consisting of elastic means (3, 3 ') which act circumferentially against a transmitted torque, and shock-absorbing means (5) consisting of a stack of friction crowns centered on the general axis of the flywheel and tightened the against each other by means of an axial-acting spring means (52), these crowns being driven into relative angular oscillation in response to the angular oscillation between the and elements of the flywheel (1, 2), the elastic means being constituted by two groups of springs (3, 3 ') arranged in succession in a toric housing (6) centered on the general axis of the flywheel, thrust elements (13, 13 '; 21, 21 ') being arranged to rest against the opposite ends of the groups of springs (3, 3') to compress them when the transmitted torque angularly offsets the elements (1, 2), double flywheel characterized in that each group of springs ( 3, 3 ') consists of a continuous structure with multiple turns which occupies, in the absence of the transmitted torque, a semicircle reduced by an interval in which two thrust elements (13, 13'; 21, 21 ') are housed, radially staggered and in relative projection from each flywheel element (1, 2) parallel to the general axis (χ-χ '), these structures each passing through a multiplicity of retaining collars (41b-43b, 41'b-43'b) arranged with substantially regular angular spacing, and each collar (41b-43b) crossed by a structure (3) being connected diametrically by means of a ring spacer (41-43) to a collar (41'b-43'b) crossed by the other structure (3 '). 2. Double shock absorber flywheel according to claim 1, characterized by the fact that the structures with multiple coils comprise two propellers (30, 31; 30 ', 31') with a common circular axis, one first right-hand and the other left-hand, with a (31, 31 ') housed concentrically in the other (30, 30'). Double shock absorber flywheel according to one of claims 1 and 2, characterized in that the multiplicity of retaining collars (41b-43b, 41'b-43'b) is 3. 4. Double shock absorber flywheel according to any one of claims 1 to 3, characterized in that the ring spacers (41-43) have two fins (41a, 41'a-43a, 43'a) protruding diametrically from the external periphery, comprising at their ends an area for fixing a retaining collar. 5. Double shock absorber flywheel according to claim 4, characterized in that the fins (41a, 41'a; 43a, 43'a) of at least some of the ring spacers (41, 43) comprise between the spacer and the fixing area a double curvature which creates an offset, with respect to the general plane of the spacer, of a parallel plane in common with the fixing areas, this offset being at least equal to the thickness of a spacer. 6. Double shock absorber flywheel according to any one of claims 1 to 5, characterized in that the collars (41b-43b, 41'b-43'b) comprise shoes (41c-43c, 41'c-43'c) adapted to to slide on surfaces of revolution (11, 25) around the general axis (χ-χ ') of the flywheel, surfaces belonging to one and the other of the elements of the flywheel (1, 2) and laterally delimiting the annular housing of the spring groups (3, 3 '}. Double shock absorber flywheel according to claim 6, characterized in that one of these surfaces of revolution (12) is cylindrical, belongs to the element of the primary flywheel (1) and constitutes the outer periphery of the annular housing (6). 8. Double shock absorber flywheel according to one of claims 6 and 7, characterized in that the shoes (141c-143c, 141'c-143'c) comprise a fin (141e-143e, 141'e-143'e) in internal radial projection that engages between two turns of the crossed structure (3, 3 '). Double shock absorber flywheel according to claim 8, characterized in that the spacer rings (141-143) constitute friction rings of shock absorber means (105). 10. Double shock absorber flywheel according to one of claims 1 to 9, characterized in that the two ends of each group of springs (3, 3 ') are provided with heads (30-30,' ') arranged to rest on elements of thrust (13, 21; 13 ', 21') protruding from the two flywheel elements. 11. Double shock absorber flywheel according to claim 10, characterized in that, with transmitted torque 0, in each interval between groups of springs (3, 3 '), the heads (32-3211') rest on the thrust element (13 , 13 ') protruding from one of the elements (1) of the flywheel while the thrust element (21, 21') protruding from the other element (2) is susceptible to oscillation between the heads (30-30 '' '). 12. Double shock absorber flywheel according to claim 11, characterized in that the thrust elements (13, 13 ') which, at zero transmitted torque, rest on the heads (32-32' '') are those which protrude from the primary flywheel (1). 13. Double shock absorber flywheel according to claim 12, characterized in that the heads (32-32 '' ') have a face (32a) facing said intervals, in a convex protuberance in a plane perpendicular to the general axis (χ-χ ') of the flywheel and, in this face, a nozzle (32b-32' '' b) parallel to this axis into which a temple formed in the thrust element (13, 13 ') protruding from the primary element (1) penetrates along the circular axis of the housing, while the thrust elements (21'21 ') protruding from the secondary flywheel element comprise, towards one and the other of the heads (32-32' ''), complementary housings (32c, 32 '' 'c) of these protuberances (32a-32,', a) and an opening along the circular axis of the annular housing which allows the thrust element (13, 13 ') protruding from the primary element (1). Double shock absorber flywheel according to any one of claims 10 to 12, characterized in that the heads (232-232 '' ') are contained in diametrically connected retaining bracelets (244a, 244' a; 245a, 245'a) two by two by means of ring spacers (244, 245). Double shock absorber flywheel according to claim 14, characterized in that the retaining bracelets (244a, 244'a; 245a, 245'a) have centering seals which rest on at least one face of the toric housing (212). 16. Double shock absorber flywheel according to one of claims 14 and 15, characterized in that the ends of at least one of the springs (230, 230 ') of each structure are arched (230a-230' '' a) outwards of the spiral, and the heads (232-232 '') comprise passages (232a-232 '' 'a) made for these curved ends, so that the latter are connected by oscillation to these heads.