WO2016203325A1

WO2016203325A1 - Filtering unit for torque transmission devices

Info

Publication number: WO2016203325A1
Application number: PCT/IB2016/052605
Authority: WO
Inventors: Sabrina BERTAGGIA; Roberto Ronchetto; Giacomo GIANSETTO; Andrea Montani; Walter Huber
Original assignee: Dayco Europe S.R.L.
Priority date: 2015-06-16
Filing date: 2016-05-06
Publication date: 2016-12-22

Abstract

A filtering unit (F) for a torque transmission device (1; 100; 200) of a propulsion system for a vehicle (E), said device (1; 100; 200) comprising a first rotating mass (M ₁; M ₁₀₁; M ₂₀₁) and a second rotating mass (M ₂; M ₁₀₂; M ₂₀₂), said filtering unit (F) being interposed between said first and second rotating mass (M ₁; M ₁₀₁; M ₂₀₁), (M ₂; Μ ₁₀₂; M ₂₀₂) and comprising at least one spiral spring (4; 104; 204); the filtering unit (F) further comprises a plurality of containing elements (17; 117; 217) configured so as to limit the deformation of said at least one spiral spring (4; 104; 204) in a radial direction due to the centrifugal force.

Description

"FILTERING UNIT FOR TORQUE TRANSMISSION DEVICES"

TECHNICAL FIELD

The present invention concerns a filtering unit for a torque transmission device of a vehicle propulsion system. In particular the invention concerns a spiral spring filtering unit for said device.

Below, by the term "torque transmission device" we mean any device interposed between a propulsion system and a gearbox of a vehicle, for example a double mass flywheel, a torque converter or a decoupling flywheel for hybrid propulsion systems . BACKGROUND ART

A problem common to the known torque transmission devices is the need to transmit the torque from the propulsion system to the gearbox filtering the torsional vibrations that could generate noise or damage the gearbox.

For this purpose a filtering unit is commonly used configured to filter predetermined torsional frequencies and comprising a spiral spring. Examples of said filtering units are described in EP2828554 or EP2783130.

According to a known solution, the filtering unit comprises two or more spiral springs having a first end connected to a first rotating mass and a second end connected to a second rotating mass which has the possibility of relative rotation with respect to the first rotating mass.

As the torque transmission device rotation speed increases, for example from 1500-2000 rpm, the spiral springs tend to be expanded due to centrifugal force towards the outside. As the spiral springs have their respective ends fixed to said masses, their expansion causes undesired rotation of the second rotating mass with respect to the first. This expansion of the spiral springs furthermore generates undesired tensions in the area of the outer ends of the spiral springs and the relative rotating mass. Said contact tensions can cause early breakage of the spiral springs. DISCLOSURE OF INVENTION

The object of the present invention is to produce a filtering unit for torque transmission devices which solves the problems described above. The above-mentioned object is achieved by a filtering unit according to claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, a preferred embodiment is described below, by way of non- limiting example and with reference to the accompanying drawings in which:

figure 1 is a functional diagram of a double mass flywheel comprising a filtering unit according to the invention;

figure 2 is an exploded perspective view of the flywheel of figure 1 ;

figure 3 is a first axial partially sectional view of the flywheel of figure 2 ;

figure 4 is a second axial partially sectional view of the flywheel of figure 2 ;

figure 5 is a section according to line V-V of the flywheel of figure 4 ;

figure 6 is an axial partially sectional view according to line VI-VI in figure 5; figure 7 is a schematic cross section according to line VII- VII in figure 5;

figure 8 is a cross section analogous to that of figure 7 showing an embodiment of the filtering unit subject of the invention;

figure 9 is a functional diagram of a torque converter comprising a filtering unit according to the invention;

figure 10 is an exploded perspective view of a module of the converter of figure 9;

figure 11 is a sectional view of the module of figure 10;

figure 12 is a functional diagram of a decoupling flywheel for hybrid propulsion systems comprising a filtering unit according to the invention;

figure 13 is an exploded perspective view of the decoupler of figure 12;

figure 14 is a sectional view of the decoupler of figure 12; and

figure 15 is a partially sectional view of an alternative embodiment of the decoupler of figure 12.

BEST MODE FOR CARRYING OUT THE INVENTION

Figures 2 and 4 show a double mass flywheel 1 with axis A and comprising a primary mass adapted to be connected to a drive shaft of an internal combustion engine (not illustrated) , a secondary mass ^i¾½ adapted to be connected to an inlet shaft of a transmission (not illustrated) , for example a clutch, and a filtering stage 3 which reciprocally connects the masses and . The flywheel 1 has an axis A coinciding with the axis of the drive shaft and the transmission shaft.

The filtering stage 3 is axially interposed between the primary mass and the secondary mass -¹ 2 and comprises essentially a first intermediate mass ¾ , a second intermediate mass ^J¾. and elastic and damping means which connect the two intermediate masses to each other and to the masses ¾ and respectively as described in detail below . The primary mass comprises a hub 10, adapted to be connected to the drive shaft (not shown) and a disc 11 connected integrally to the hub 10. An annular crown 9 is fixed to the radially outer edge of the disc 11, extending parallel to the axis A in an overhanging manner towards the secondary mass and internally delimited by an inner annular surface 9a.

The primary mass is connected to the first intermediate mass -^ 3 by means of a filtering unit F comprising a pair of metal spiral springs 4 with quadrangular section, having respective inner ends 4a fixed in diametrically opposite positions to the first intermediate mass ^;¾ and respective outer ends 4b secured to respective spring holder elements 14 fixed in positions diametrically opposite the surface 9a and therefore integral with the disc 11. Said spring holder elements 14 are arch-shaped and each have a slit 14a in which the end of a respective spring 4 integrally engages. The springs 4, having an equivalent rigidity ¾s , have the same winding direction and a number of coils between 0.5 and 2.

The filtering unit F further comprises, fixed on the surface 9a of the crown 9, a plurality of containing elements 17 for the coils of the spiral springs 4 which, in addition to the deformations connected with transmission of the torque, are also subject to a radial expansion deformation due to the centrifugal effect which begins to become effective at speeds of approximately 1500-2000 rpm and becomes important at high rotation speeds of the flywheel 1, for example 4000-6000 rpm. Figures 7 and 8 show two of the possible variations for the containing elements 17. Figure 7 shows a first embodiment in which four containing elements 17 are present with arched shape and having an outer profile 17a configured to couple with the surface 9a and an inner profile 17b configured so as to reproduce the deformed profile of the spiral spring 4 at a combination of design speed and torque, for example 4000 rpm and 220 Nm. The containing elements 17 in this case are in diametrically opposite pairs fixed to the surface 9a in the angular spaces between the two spring holders 14, in each of which two containing elements are housed.

The embodiment of figure 8 comprises, in addition to the containing elements of figure 7, two further containing elements 17 positioned internally between the coils of the spiral spring 4 and fixed to the disc 11 for example by means of threaded connections or pins. In this case the stop 17 has two profiles 17c, 17d, outer and inner respectively, configured so as to reproduce the deformed profile of the coils with which they cooperate respectively, at a combination of design speed and torque, for example 4000 rpm and 220 Nm.

With reference to figure 5, a friction damper, preferably a friction disc 7, is further axially interposed between the spiral spring 4 and the primary mass , integral with the primary mass ¾ . Said friction disc is positioned in axial contact with the coils of the spiral springs 4 in order to provide a damping ^ss between the primary mass and the first intermediate mass ¾ , due to the reciprocal sliding between them.

The first intermediate mass comprises essentially a spring holder element 12 having a substantially cylindrical shape provided with substantially tangential seats (not shown) for interlocking of the inner ends 4a of the spiral springs 4. Said spring holder element 12 is radially supported in a rotationally free manner by rolling bearings 61 on the primary mass . Between the primary mass and the first intermediate mass ^3 one or more safety stops 63 are conveniently provided to limit the maximum torsional deformation of the spiral spring 4. Conveniently (figures 5, 7 and 8) said safety stops 63 consist of radial ridges 64 of the hub 10 and respective inner teeth 65 of the spring holder element 12. From the spring holder element 12 a tubular portion 12a extends towards the secondary mass ¾ . On the tubular portion 12a a plurality of outer radial ridges 16 are provided each defining a circular seat 13 with radial axis; on the bottom of each seat a hole 15 is provided, also with radial axis and having smaller diameter than the respective seat 13. Each seat 13 houses a radially movable shoe 19 loaded towards the outside by a cylindrical spring 20 housed in the respective hole . From the tubular portion 12a an annular axial ridge 12b extends, recessed with respect to the tubular portion 12a, on which a damper 25 is mounted. The damper 25 substantially comprises a C-shaped bushing 30 cooperating by sliding with the outer surface of the axial ridge 12b and an open metal ring 31 fitted by radial forcing on the bushing 30 and rotationally coupled to the same by means of a pair of radial ridges (not shown) which engage in corresponding holes in the ring 31. The ring 31 comprises, at its ends, respective outer radial ridges 33 adapted to cooperate with stop elements 34 integral with the second intermediate mass as described below .

The second intermediate mass comprises an annular actuator disc 40 on the inner edge 41 of which evenly spaced recesses 22 are obtained in which the respective shoes 19 of the first intermediate mass are free to move circumferentially . The recesses 22 are delimited by oblique sides 22a diverging towards the inside of the actuator disc 40 and have a bottom surface 22b having an intermediate portion 22c with circular profile and axis A, and respective lateral portions 22d adjacent to the sides 22a in relief with respect to the intermediate portion 22c and joined to it.

The shoes 19 are pushed by the respective springs 20 against the bottom surface 22b of the respective recesses; each spring 20 exerts different forces, smaller and greater respectively, according to whether the shoes 19 cooperate with the intermediate portion 22c or with the lateral portion 22d.

Assuming that a shoe 19 is arranged angularly evenly spaced with respect to the sides 22a, the angle between each shoe 19 and each of the sides 22a will be equal to 2 , where ^£ϊ: represents the total angular stroke of the shoes 19 within the openings 22. Said stroke has a value of less than 30°, preferably less than 24°, and conveniently 16° and is formed by a central section σ for example 8° defined by the stroke of the shoe 19 against the central portion 22c and by respective end sections ^ε equal for example to 4° defined by the stroke of the shoe 19 against each of the lateral portions 22d. According to a variation, not shown, the openings 22 can be coated in a layer of polymer material.

The disc 40 further comprises a plurality of spokes 42 extending radially from the disc 40 and arranged angularly evenly spaced from one another, preferably four, in diametrically opposite pairs. The disc 40 is free to rotate within a volume 43 enclosed by two shells 44,45 integral with the secondary mass . Between the disc 40 and the secondary mass s friction rings 47 are axially interposed, adapted to define a damping between the second intermediate mass and the secondary mass. The above-mentioned stop elements 34 extend axially in an overhanging manner from the disc 40 towards the damper 25. In the position of the damper 25 in which the ridges 33 are evenly spaced from the respective stop elements 34, an angle ' 2 is present between each of the ridges 33 and the respective stop element 34, β being the total free rotation angle between the damper 25 and the actuator disc 40. The angle β is conveniently equal to the angle σ to allow activation of the damper 25 when the shoes 19 interact with the lateral portions 22d so that the respective dampings add up to form a damping TGI .

The shells 44,45 enclose, in seats 51 obtained therein, a plurality of elastic assemblies 50, preferably four, arranged circumferentially and angularly evenly spaced from one another. The seats 51 conveniently consist of windows of the shells 44,45 facing each other (figure 2) . The elastic assemblies 50 comprise (figure 6) a cylindrical helical spring 52 with tangential axis and a pair of shoes 53 which house respective end portions of the spring 52 and are adapted to cooperate under the thrust of the spring 52 with respective ends 51a of the seats 51. The springs 51 have an equivalent rigidity i much greater than the equivalent rigidity &ss of the spiral springs 4. The angular clearance δ between the shoes 53 of each elastic assembly 50, arranged in contact with the ends 51 of the respective seat 50, is conveniently equal to 4°. The shoes 53 are also adapted to cooperate with the spokes 42 of the disc 40.

Assuming that the actuator disc 40 is arranged so that each of the spokes 42 is angularly evenly spaced from the elastic assemblies 50, the angle between each of the spokes 42 and

¥ί

each of the elastic assemblies 50 will be equal to il , where Y represents the total angular play between the spokes 42 and the elastic assemblies 50.

The spokes 42 are adapted to cooperate with the elastic assemblies 50 determining the compression of the springs 52 and if necessary the relative contact between the shoes 53 once the clearance δ between them has been taken up.

The secondary mass comprises a disc 59 provided with a hub

58 supported in a rotationally free manner on the hub 10 of the mass ^J¾'½ by the rolling bearings 62. Also the shells 44,45 integrally secured to the disc 59 form part of the secondary mass -^ - The disc 59 is adapted to be connected in a conventional manner to a clutch of the vehicle. With reference to figure 1, the filtering unit 3 can be considered to be composed of three stages in series:

a filtering stage F comprising:

o an elasticity between the primary mass and the first intermediate mass ¾ due to the overall rigidity of the spiral springs 4 and

o a damping ¾,? generated by sliding of the spiral springs

4 on the friction disc 7;

an idling stage comprising:

o a damping -¹ acting between the intermediate masses s and ¾, due to the interaction between the shoe 19 and the surfaces 22b, 22d and also to the effect of the damper 25 and o a clearance defined by the angle a between the shoes

19 and the openings 22

a starter stage comprising:

o a damping between the second intermediate mass ^;!¾ and the secondary mass s due to the interaction between the shells 44,45 and the friction rings 47, and

o a clearance G3, defined by the angle γ,

o an elasticity &i in series with the clearance G3, due to the springs 42 and

o a damping ^Ί. in series with the clearance G3 and parallel to the elasticity ·¾ due to the friction of the movement of the shoes 53 in the respective seats 51 during compression of the springs 52.

Two rigidities &e , ¾ representing the equivalent rigidities of the drive shaft and the gearbox respectively.

Operation of the flywheel 1 is as follows.

With the engine in a steady state (fixed or variable speed but without sudden accelerations or decelerations) the inlet torque acting on the primary mass is transmitted from the spiral springs 4 (rigidity &ss ) to the first intermediate mass

The angular clearance Gl is taken up by the torque, with value higher, for example, than 70Nm, thus making the damping ineffective and the spokes 42 of the actuator disc 40 come into contact with respective shoes 53 of the elastic assemblies 50. Since the rigidity is much greater than the rigidity &ss · , the deformations of the springs 52 are much less than those of the spiral springs 4.

Therefore the torsional oscillations of the drive shaft are substantially absorbed by the filtering stage F.

With the engine in idling conditions (torque absent but relatively high torsional oscillations), the filtering assembly F and the starter assembly S, provided with respective rigidities ¾s and , behave like rigid systems with respect to the idling assembly I, which therefore absorbs the oscillations thus making the spiral springs 4 inactive.

For oscillations with amplitude smaller than the angle σ, the shoes 19 cooperate with the central portions 22c of the openings 22 thus generating a first damping level conveniently lower than 3 Nm, and preferably equal to 1-2 Nm. In the example illustrated in which the angle β is equal to the angle σ, the damper 25 is inactive since the ridges 32 do not interact with the stop elements 34. For oscillations with amplitude greater than the angle σ, the shoes 19 cooperate with the lateral portions 22d of the openings 22 thus generating a second damping level conveniently greater than 2 Nm, and preferably equal to 4-7 Nm. In the example illustrated in which the angle β is equal to the angle σ, parallel to the interaction of the shoes 19 with the lateral portions 22d, one of the two ridges 33 (according to the rotation direction) cooperates with the respective stop element 34 and tends to close the ring 31 on the bushing 30, increasing the forcing thereof on the surface 12b. An additional damping is therefore generated between the first and the second intermediate mass ¾ , ¾* , conveniently greater than 2 Nm, and preferably equal to 4Nm. Said damping is added to the second damping level defining a total damping value ^J¾ equal for example to 6-10 Nm.

At starting and in particular operating conditions, for example gear change errors or sudden torque inversions or variations, the torsional oscillations can reach even higher values and in particular greater than the angle a. In these situations the torsional oscillations are transmitted to the actuator disc 40 due to the contact between the shoes 19 and the sides 22b.

Once the clearance G3 between the spokes 42 of the actuator disc 40 and the elastic assemblies 50 has been taken up, the spokes 42 come into contact with respective shoes 53 of the elastic assemblies 50 and compress the springs 52, the purpose of which is to avoid rigid impact between the actuator disc 40 and the secondary mass M2. The shoes 53 of each elastic assembly 50 come into contact only in the event of extreme stress, which rarely occurs in the normal operating conditions of the engine.

When the flywheel rotates at a very high speed, for example 4000-5000 r.p.m., the centrifugal force acting on the spiral springs 4 causes an abnormal deformation thereof which could produce a spurious rotation of the first intermediate mass and possible intervention of the safety stops 63 in the absence of torque or at low torque, and with consequent noise. The containing elements 17 of the spiral springs 4, containing the radial expansion of the spring coils, prevent occurrence of the above-mentioned drawback.

The containing elements 17 also ensure that the radial expansion of the springs does not cause abnormal stress in the areas of the spring adjacent to the outer end areas 4b due to contact with the spring holder 14.

Figures 10 and 11 show a torque converter module 100 with axis B comprising a primary mass ^iei adapted to be connected to a drive shaft of an internal combustion engine (not illustrated) and a secondary mass ^¾o2 adapted to be connected to an inlet shaft of a transmission (not illustrated) , and a filtering unit F which reciprocally connects the masses ^ien and ^ioz-

The primary mass ^ici comprises an annular element 102 configured to be connected to a clutch C configured to selectively connect the torque converter module 100 to the outlet of the internal combustion engine E and a disc 120 integral with the annular element 102. The secondary mass ^ios comprises a hub 101 configured to connect to an outlet shaft (not shown) at the inlet to the gearbox G.

The annular element 102 essentially comprises a cylindrical portion 103 coaxial with the axis B and an annular flange 108 perpendicular to the cylindrical portion 103 and joined to the latter. The cylindrical portion 103 comprises a plurality of longitudinal ridges 105 extending radially from an inner annular surface thereof towards the axis B. The ridges 105 are configured to connect the annular element 102 to the clutch C.

The flange 108 comprises a plurality of holes 106 with axis parallel to the axis B and preferably arranged on diametrically opposite sides. The holes 106 are configured to cooperate with fastening means 107, such as bolts or rivets, to reciprocally connect the annular element 102 and the disc 120, as described below, to define a casing inside which the filtering unit F is housed.

The filtering unit F comprises a pair of metal spiral springs 104 with quadrangular section, having respective inner ends 104a fixed in diametrically opposite positions to the hub 101 and respective outer ends 104b secured to respective spring holder elements 114. Said spring holder elements 114 have an arched shape and each comprise a plurality of holes 121 configured to cooperate with the fastening means 107 to be fixed integral and axially interposed between the annular element 102 and the disc 120. The spring holder elements 114 further comprise a slit 114a in which the end 104b of a respective spring 104 engages in an integral manner.

The springs 104 have the same winding direction and a number of coils between 0.5 and 2.

The annular element 102 carries a plurality of containing elements 117 for the coils of the spiral springs 104 which, in addition to the deformations connected with transmission of the torque, are also subject to a radial expansion deformation due to the centrifugal effect which begins to become effective at speeds of approximately 1500-2000 rpm and becomes important at high rotation speeds of the module 100, for example 4000-6000 rpm.

The containing elements 117 can comprise the same characteristics and variations as those described for the flywheel 1 and shown in fig. 7 and 8.

Figure 10 shows an alternative embodiment of the containing elements 117 in which the containing elements 117 are made in one single piece in polymer material and comprise a plurality of holes 118 configured to cooperate with fastening elements 107. Inside the holes 118 a bushing 123 is conveniently housed intended to prevent direct contact between the fastening element 107 and the containing elements 117.

The containing elements 117 further comprise a plurality of through openings 124 configured to reduce the weight of the containing element 117 while at the same time maintaining an adequate structural rigidity; the openings 124 are further necessary to obtain the containing elements 117 by means of a simple inexpensive manufacturing process. The shape and number of said openings 124 is a function of the design conditions of the containing element 117. The disc 120 comprises a hole 130 in which part of the hub 101 is mounted in a through manner. The disc 120 is directly supported in a radial direction on the hub 101; since the module 100 works in an oil bath, support bushings are not necessary and the disc 120 can freely rotate on the hub 101.

The disc 120 comprises an inner ring 135, radially delimited by the hole 130 and an outer ring 136 connected by means of a plurality of spokes 137. Preferably there are five spokes 137 angularly evenly spaced from one another.

The outer ring 136 of the disc 120 comprises a plurality of holes coaxial with the holes 121 of the annular element 102 and configured to cooperate with the fastening elements 107. In this way the containing elements 117 are comprised and integral between the annular element 102 on the one side and the disc 120 on the other.

The inner ring 135 comprises a plurality of holes 140 arranged circumferentially with respect to the axis B via which, by means of fastening means 141, a module 150 of a turbine T is mounted. The turbine T comprises the module 150 and a module 151 configured to reciprocally cooperate in a known manner; essentially the modules 150, 151 cooperate with a fluid interposed between them to amplify the inlet torque module to the torque converter module 100.

The hub 101 comprises a radial flange 162 on which a pair of slots 161 are obtained extending in a circumferential direction by a predetermined angle. Between the two slots 161 respective portions 165 are provided diametrically opposite to each other and extending axially with respect to the flange 162. The portions 165 are configured to receive the inner ends 104a of the spiral springs 104. Said configuration of the hub 101 comprising the slots 161 gives particular rigidity to the hub 101.

The module 100 further comprises safety stops configured to prevent excessive relative rotation of the primary mass ^iei with respect to the secondary mass ^io2 , thus avoiding overloading the spiral springs 104. The safety stops essentially comprise a ridge 163 extending from the inner ring 135 of the disc 120 towards the hub 101 and a lateral wall 160 of the portions 165 with shape complementary to that of the ridge 163. The ridges 163 are free to move over a predetermined angular range until they hit the wall 160, thus defining a maximum relative rotation between the primary and secondary masses ^ΙΌΙ· ^i02- The filtering unit F further comprises a plurality of shoes 138, preferably carried by the spokes 137 by means of appropriate joints, configured to damp vibrations of the spiral springs 104 in an axial direction. Preferably said shoes 138 are made of polymer material.

Preferably the damping value provided by the shoes 138 is lower than 3 Nm.

With reference to the diagram of figure 9, the operation of the torque converter is as follows.

In one operating stage the clutch C is open so that the torque delivered by the engine E is transmitted to the turbine T. The modules 150 and 151 of the turbine T operate, in a known way, by amplifying the movement of the torque which is transmitted to the disc 120 to which the module is integrally connected. The spring holders 114, being integral with the disc 120, rotate the spiral springs 104 which, in turn, rotate the hub 101. In this way, the torque is transferred from the engine to the gearbox G, in an inverted direction and filtered from the torsional vibrations due both to the turbine T and to the spiral springs 104.

In another operating stage the clutch F is closed so that the torque of the engine E is transmitted simultaneously both to the turbine T and to the primary mass ^loi . In this way the torque bypasses the turbine T (since the modules 150, 151 reciprocally rotate with no sliding at all) and is exclusively filtered by the filtering unit F by means of the spiral springs 104 and transferred to the gearbox G.

In both the operating stages the containing elements 117 prevent the spiral springs 114 from expanding in an uncontrolled manner at an excessive rotation speed, exactly as described for the flywheel 1.

Analogously, the safety stops 160 prevent any excessive relative rotations between the primary mass ^ici and the secondary mass ^i&i and the shoes 138 damp the axial vibrations of the spiral springs 104.

Obviously the filtering unit F of the module 100 can be used also in other types of torque converters in which, according to the operating status of the clutch, the torque can follow different paths. For example, in a known configuration, when the clutch C is open, the torque to the module 150 could go directly to the gearbox G without passing through the filtering unit F.

Figures 13 and 14 illustrate a decoupler flywheel for hybrid propulsion systems 200, below called "hybrid decoupler" 200 for the sake of brevity. The hybrid decoupler 200, with axis D, comprises a primary mass ^20i adapted to be connected to a drive shaft of a hybrid combustion engine (not illustrated) and a secondary mass -^20s adapted to be connected to an inlet shaft of a transmission (not illustrated) , and a filtering unit F which reciprocally connects the masses ^J¾½0i and ^Ζϋι-

The primary mass ^201 comprises essentially a flywheel 208 comprising a hub 210, adapted to be connected to the drive shaft (not shown) and a disc 211 connected integrally to the hub 210. On the outer edge of the disc 211 an annular crown 209 is fixed extending parallel to the axis D overhanging towards the secondary mass ^20s and internally delimited by an annular surface 209a. The filtering unit F comprises a pair of metal spiral springs 204 with quadrangular section, having respective inner ends 204a fixed in diametrically opposite positions to the secondary mass ^ZQi and respective outer ends 204b secured to respective spring holders 214 fixed in diametrically opposite positions to the annular surface 209a, integral with the disc 211. Said spring holder elements 214 have an arched shape and each have a slit 214a in which the end 204b of a respective spring 204 integrally engages. The springs 204, having an equivalent rigidity &ss , have the same winding direction and a number of coils between 0.5 and 2.

The secondary mass ^20s comprises essentially a spring holder element 212 having a substantially cylindrical shape provided with seats (not shown) which are substantially tangential for interlocking the inner ends 204a of the spiral springs 204.

The spring holder element 212 is free to rotate with respect to the primary mass ^2&i since respective radial and axial clearances are provided between the hub 210 of the flywheel 208 and the spring holder 212. For example these radial clearances are approximately 0.5 mm. On the spring holder 212 an annular element 240 with L-shaped section is preferably fitted configured to withstand any impact due to undesired contact with the hub 211. Between the primary mass ^20ii and the secondary mass ^;^ "0i one or more safety stops 260 are conveniently provided configured to limit the maximum torsional deformation of the spiral spring 204. Conveniently the safety stops 260 are of the type described for the flywheel 1 or the torque converter module 100.

The hybrid decoupler 200 further comprises a cover 230 comprising a disc 231 and a flange 232 extending axially from the outer edge of the disc 231 towards the primary mass ^ 2Si . The flange 232 is configured to cooperate with the flange 209 to enclose the filtering unit F between the disc 231 and the disc 211. Preferably the cover 230 is made in one single piece, in a metallic material.

On at least one between the discs, disc 211 and the disc 231, a plurality of shoes 225 are carried configured to damp the vibrations of the spiral springs 204 in an axial direction.

Preferably the shoes 225 have a substantially elliptical shape and are arranged circumferentially around the axis D, angularly evenly spaced from one another, preferably the ones carried by the disc 211 facing the others carried by the disc 231.

Preferably the damping value T_ss provided by the shoes 225 is lower than 12 Nm, even more preferably lower than approximately 3 Nm.

The filtering unit F comprises a plurality of containing elements 217 for the coils of the spiral springs 204 fixed on the surface 209a of the crown 209. The containing elements 217 have purposes identical to those of the filtering unit F described for the flywheel 1 or for the torque converter module 100 and can be produced in one of the forms previously described .

Figure 13 shows an alternative embodiment for the containing elements 217 in which each containing element 217 comprises a metal core 218 and a plurality of inserts 219 made of polymer material housed in seats 220 obtained on the inner profile 217b of the containing element 217. The inserts 219 project in a radial direction towards the spiral springs 204 and each comprise an inner profile 219a configured so as to reproduce the corresponding portion of spring 204 deformed at a given combination of design torque and speed.

Figure 15 shows a further alternative embodiment for the containing elements 217 in which the latter are obtained integrally with the shoes 225. For example, each shoe 225 of the disc 102 comprises an axial ridge 226 extending from an outer radial edge of the shoe 225 towards the respective axial ridge 226 carried by the disc 211 and the corresponding shoe 225 carried by the cover 230.

The axial ridges 226 comprise, in turn, an inner profile 226a configured to reproduce the corresponding portion of spring 204 deformed at a given combination of design torque and speed .

In this way while the shoes 225 damp the axial vibrations of the spiral springs 204 the axial ridges 226 act containing the radial expansion of the spiral springs 204 analogously to what is described for the other embodiments of the containing elements 217.

With reference to figure 12, the operation of the hybrid decoupler 200 is as follows.

The inlet torque to the primary mass ^2&i is transmitted to the secondary mass by means of the spiral springs 204, caused to rotate by means of the spring holders 214, integral with the primary mass ^½0i . The secondary mass ^2Qs in turn causes rotation of the shaft connected to it, providing a torque previously filtered by the filtering unit F to the gearbox G. The containing elements 217 operate analogously to what is described for the flywheel 1 and the torque converter module 100. The only difference is that the spiral springs 204 rest on the surfaces 219a of the inserts 219. Furthermore, in the case of excessive torque transmitted from the primary mass -¾23-t to the secondary mass ^2Q¾ the safety stops 260 act as already illustrated to contain the relative rotation between the masses ^ ©i , ^20s . Analogously the shoes 225 damp the axial vibrations of the spiral springs 204 and avoid undesired metal/metal contacts.

From the above, the advantages of a filtering unit F for a torque transmission unit 1, 100, 200 according to the invention are obvious. The use of containing elements 17; 117; 217 reduces deformations of the spiral springs 4; 104; 204 and consequent undesired rotations of one of the two rotating masses.

Furthermore containment of the expansion of the spiral springs 4; 104; 204 avoids undesired contacts between the spring holders 14, 114, 214 and the coils of the spiral springs 4; 104; 204 in the end fixing area.

The use of containing elements 17; 117; 217 comprising a contact profile 17b, 117b, 219a to accommodate the coils of the spiral springs 204 deformed at a given speed and torque transmitted by the torque transmission device 1, 100, 200, allows complementary coupling between the deformed coils and the containing elements 17; 117; 217 avoiding undesired localized contacts.

The use of containing elements 17; 117; 217 made of plastic and comprising openings 124 allows reduction of the weight of the containing elements 17; 117; 217, and therefore of the torque transmission device 1, 100, 200.

The use of containing elements 17; 117; 217 comprising plastic inserts 219 allows sole replacement of the same when worn and not of the whole containing element 17; 117; 217.

Lastly it is clear that modifications and variations can be made to the filtering unit F which do not depart from the protective scope defined by the claims.

For example, the embodiments of the containing elements 17; 117; 217 described in the double mass flywheel 1 can be used indifferently in the torque converter module 100 or in the hybrid decoupler 200; their number and the shape of their profiles can be varied without modifying their function. The embodiments of the axial damping elements 7; 138; 225 described in the double mass flywheel 1 can be used indifferently in the torque converter module 100 or in the hybrid decoupler 200; their number can be varied without modifying their function.

Claims

1.- A filtering unit (F) for a torque transmission device (1; 100; 200) of a propulsion system for a vehicle (E) , said device (1; 100; 200) comprising a first rotating mass ( Mj : M Qit M-2Q1 ) and a second rotating mass (

) , said filtering unit (F) being interposed between said first and second rotating mass {^ι' ^ίΰί' ^2ΰ±) , (^a? ιο₂: 203 ) and comprising at least one spiral spring (4; 104; 204), characterized in that it comprises a plurality of containing elements (17; 117; 217) configured so as to limit the deformation of said at least one spiral spring (4; 104; 204) in a radial direction due to the centrifugal force.

2.- A unit according to claim 1, characterized in that said containing elements (17; 117; 217) are carried by either said first rotating mass ^iOaJ ^ 01 ) or said second rotating mass (¾" M ; M^Cn ) .

3.- A unit according to claim 1 or 2, characterized in that said containing elements (17; 117; 217) comprise at least one profile (17a; 17c; 17d) configured to couple with an outer surface of a coil of said at least one spiral spring (4, 104, 204) .

4.- A unit according to claim 3, characterized in that at least one profile (17a; 17c; 17d) is configured so as to correspond to the profile of a coil of said at least one spiral spring (4; 104; 204) at a combination of predetermined rotation speed and torque transmitted of said torque transmission device (1; 100; 200) .

5.- A unit according to one of the claims from 1 to 4 characterized in that said containing elements (17; 117; 217) are made in one single piece in polymer material.

6.- A unit according to one of the claims from 1 to 4 characterized in that said containing elements (17; 117; 217) are made in one single piece in metal material.

7.- A unit according to one of the claims 3 or 4 characterized in that said containing elements (17; 117; 217) comprise a metal core (218) and plastic inserts (219), said inserts (219) comprising a profile (219a) adapted to couple with said outer surface.

8. - A unit according to one of the claims from 1 to 7 characterized in that said filtering unit (F) comprises at least one friction element (7; 138; 225) cooperating axially with said spiral springs (4; 104; 204) to generate a damping ( _ss ) .

9. - A unit according to claim 8, characterized in that said at least one friction element (7; 138; 225) is carried by at least one of either said first or second rotating mass ( _j .; M_{10l5 20l} ) , ( _¾; M_ito? M_{mi )} .

10. - A unit according to claim 8 or 9, characterized in that said containing elements (17; 117; 217) are produced integrally with said friction elements (7; 138; 225) .

11. A double mass flywheel comprising a filtering unit (F) according to any one of the claims from 1 to 10.

12. A torque converter comprising a filtering unit (F) according to any one of the claims from 1 to 10.

13. A torque converter according to claim 12, wherein said primary mass ^lQi comprises an annular element (102) connectable to a clutch of the vehicle and a supporting disc (120) for supporting a turbine (T), said secondary mass ^ios comprising a hub (101) connectable to an inlet shaft of a gearbox of the vehicle, said at least one spiral spring (104) having an inner end secured to said hub (101) and an outer end secured to a spring holder (114) fixed between said annular element (102) and said disc (120) .

14. A decoupling flywheel for hybrid propulsion systems comprising a filtering unit (F) according to any one of the claims from 1 to 10.

15. A decoupling flywheel for hybrid propulsion systems wherein said primary mass &¾0i comprises a flywheel (208), said secondary mass ^2Qi comprising a hub (212) connectable to an inlet shaft of a gearbox of the vehicle, said at least one spiral spring (204) having an inner end secured to said hub (212) and an outer end secured to a spring holder (214) fixed on said flywheel (208) .