FR2817601A1 - Double damping flywheel has temporary immobilizer for use on assembly of primary and secondary flywheels, made in form of movable tool with ring and tubes engaging with cavities in two and equipped with extractor - Google Patents

Abstract

The double damping flywheel (10) consists of a primary flywheel (11), a secondary flywheel (12) able to rotate freely relative to the primary one about a main axis, and a vibration damping mechanism (13) between the two. The flywheel has a temporary immobilizer (30) for use on assembly of the primary and secondary flywheels, made in the form of a movable tool with a ring and tubes engaging with cavities (14, 22) in the two and equipped with an extractor.

Description

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The invention relates to a double damping flywheel for a motor vehicle clutch mechanism.

 Generally, a clutch mechanism comprises a friction disc fitted with friction linings suitable for being clamped between a pressure plate and a reaction plate (also called flywheel) by a diaphragm. The diaphragm is pivotally mounted on a cover which is fixed to the reaction plate (itself fixed to the engine crankshaft), and the pressure plate is linked in rotation with the cover, but movable in axial translation relative to said cover. The radially external part of the diaphragm (in the form of a Belleville washer) bears on the pressure plate, while the radially internal part (of the radial fingers) cooperates with a control member such as a clutch release bearing which is movable in translation axial.

 In the context of a clutch associated with a double damping flywheel, the linings of the friction disc bear against a secondary flywheel connected in rotation to a primary flywheel around the axis of the clutch mechanism. The two flywheels are therefore coupled so as to be able to rotate with respect to each other, a mechanism for absorbing rotational vibrations comprising elastic members makes the connection in rotation between these two flywheels.

 This type of assembly makes it possible to absorb the vibrations of the crankshaft which does not rotate with a constant speed of rotation because it is subjected to jolts due in particular to the movements of the pistons in the engine cylinders. To simplify, we can say that the crankshaft has a cyclic rotational movement whose frequency is a function of the number of cylinders.

 The double damping flywheel therefore compensates for small acceleration or deceleration of the crankshaft, especially when the gearbox is in neutral and the engine is idling, which avoids transmitting vibrations to the gearbox.

 In this type of double damping flywheel, in particular with radial springs, the vibration absorption mechanism generally acts only from a certain angular amplitude in the offset between the two flywheels around the rest position, that is to say that the restoring force of

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 springs may be very weak, see substantially zero for small angles of travel. It follows that the secondary flywheel can rotate relative to the primary flywheel without the springs catching up with the angular offset thus created.

 Thus, during assembly on the crankshaft of the module constituted by the two flywheels and the vibration absorption mechanism, the operator may be faced with the problem of poor alignment between the orifices provided in the secondary flywheel for the passage of screws. or a tightening tool, and the holes in the primary flywheel receiving the fixing screws on the crankshaft. This misalignment can occur during handling of the module or during transport.

 An object of the present invention is therefore to remedy these problems.

 For this, the invention relates to a double damping flywheel for filtering vibrations between an engine and a motor vehicle transmission system, this double flywheel comprising a primary flywheel, a secondary flywheel which is free to rotate relative to the primary flywheel around a main axis, and a vibration damping mechanism interposed between the primary flywheel and the secondary flywheel, characterized in that it further comprises at least one means for temporarily immobilizing the secondary flywheel in a determined angular position relative to the primary flywheel.

 According to another characteristic of the invention, the temporary immobilization means will be provided to break under the effect of a low torque exerted between the secondary flywheel and the primary flywheel, so as to be able to release the rotation lock of the flywheel secondary to the primary flywheel. This torque may in particular be due to the inertia of the secondary flywheel when starting the engine or to the torque transmitted during the starting of the vehicle.

 Advantageously, the temporary immobilization means will remain integral with the primary flywheel and / or the secondary flywheel after it has broken.

 By way of example, the temporary immobilization means may consist of an adhesive material connecting the primary flywheel to the secondary flywheel, for example a hot-melt adhesive.

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 As a variant, the temporary immobilization means may have a zone of least resistance and include a pin, a first part of which will be housed in an orifice of the primary flywheel and a second part of which will be housed in an orifice of the secondary flywheel, the two parts then being connected to each other by means of the zone of least resistance, constituted for example by a local reduction in material thickness, which can be achieved by a local reduction in diameter.

 According to another variant, the temporary immobilization means may consist of a metal wire welded to the primary and secondary flywheels.

 Advantageously, the temporary immobilization means will be designed so that after its rupture, it does not release any debris after its rupture.

 Generally, the temporary immobilization means will preferably be mounted in an area close to the external periphery of the double flywheel.

 Several means of temporary immobilization may be distributed around the perimeter of the double steering wheel.

 According to yet another exemplary embodiment, part of the immobilization means will be mounted on an additional part fixed to the primary or secondary flywheel, which may for example belong to a device for determining the speed of rotation of the double flywheel.

 Alternatively, the temporary immobilization means may take the form of a removable tool adaptable in the orifices of the secondary flywheel before mounting the double flywheel on the crankshaft. This tool may take the form of a crown provided with several tubes mounted in the orifices for the passage through them of a tightening tool and possibly of fixing screws. The tool can be fitted with prominent extraction tabs for its removal once the double flywheel is mounted. The tubes may be fitted with stops for the axial retention of the fixing screws before mounting the double flywheel on the crankshaft.

 Any other type of tool using a housing in one or the other of the handwheels to secure them can be used.

 Other characteristics, details and advantages of the invention will emerge on reading the description which follows, given by way of example with reference to the appended drawings in which:

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- la figure 1 est une vue en coupe d'un double volant amortisseur selon la présente invention, - la figure 2 est une vue de face, - la figure 3 est une vue de détail d'un moyen de blocage du double volant amortisseur, - la figure 4 est une variante de réalisation de la figure 3, - la figure 5 est une vue en perspective d'un outil amovible d'immobilisation, et - la figure 6 est une vue partielle en coupe de l'outil présenté figure 5.

- Figure 1 is a sectional view of a double damping flywheel according to the present invention, - Figure 2 is a front view, - Figure 3 is a detail view of a blocking means of the double damping flywheel, - Figure 4 is an alternative embodiment of Figure 3, - Figure 5 is a perspective view of a removable immobilization tool, and - Figure 6 is a partial sectional view of the tool presented in Figure 5 .

 In FIG. 1, the reference 10 designates a double damping flywheel for an internal combustion engine of a motor vehicle.

 The double damping flywheel 10 is fixed to a crankshaft 20 using screws 25. This double damping flywheel 10 forms a module which comprises a primary flywheel 11, a secondary flywheel 12 and a device for damping the vibrations in rotation comprising springs 13 with radial orientation, this device being interposed between the primary flywheel 11 and the secondary flywheel 12. The secondary flywheel 12 serves as a reaction plate for linings of a friction disc (not shown) of known type.

 The secondary flywheel 12 also has (see lower half-section of FIG. 1) orifices 14 for passages for a tool so as to be able to fix the module to the crankshaft 20 using the screws 25. These orifices 14 can also be used when passing the screws if they have not been previously mounted on the primary flywheel.

 To be able to pass this tool and possibly the fixing screws 25, in order to fix the module on the crankshaft, it is therefore necessary that the holes 14 of the secondary flywheel are perfectly aligned with the holes 22 provided in the primary flywheel. at least one means 30 is provided for temporarily immobilizing the secondary flywheel 12 on the primary flywheel 11 to facilitate this mounting. The operator then simply aligns the screws 25 with the corresponding holes provided in the crankshaft.

 The sectional view of Figure 2 shows the radial springs 13 of the vibration damping device of the double flywheel 10, as well as the screws 25 for fixing the double flywheel on the crankshaft. We also see on the

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 right half-section the movement of the springs 13 during an angular offset between the primary flywheel 11 and the secondary flywheel 12.

 As can be seen in the detail view of FIG. 3, the immobilization means 30 takes the form of a point of adhesive glue 31, for example hot-melt, connecting the two parts 11 and 12 of the double flywheel 10 at the level of their periphery.

 More specifically, the point of glue 31 connects the secondary flywheel 12 to an annular intermediate piece 15 belonging to a device for determining the speed of the primary flywheel 11. Of course, this piece 15 can be eliminated in which case the glue point 31 connects directly the primary flywheel 11 to the secondary flywheel 12.

 In this perspective, we can also provide small recesses (not shown) in the two steering wheels so that the operator better locates the precise place where he must put the point of glue 31. This also makes it possible to dose more easily the amount of glue and prevent it from tearing off before mounting.

 According to an alternative embodiment illustrated by the detail view of Figure 4, one can make holes 16 and 18 respectively inside the primary flywheel 11 and secondary 12, and accommodate in each of these holes part of a pin breakable plastic 32. The two parts 32a and 32b of the pins 32 are connected by a reduced cross-section area 32c producing a fracture initiator facilitating the separation of the two parts, such as a reduction in the diameter of the pin.

 According to another variant, not shown, the immobilization means 30 can be a thin metal (or plastic) wire which is welded between the primary flywheel and the secondary flywheel.

 Of course, it is possible to have several immobilization means 30 around the periphery of the steering wheel, and in particular to place them at regular intervals.

 In the various embodiments presented, the immobilization means 30 must be temporary, that is to say that once the double damping flywheel 10 mounted on the crankshaft 20, it must allow the rotation of the two flywheels and stop to be active.

 Typically, it must break when a sufficiently large torque is applied between the primary flywheel 11 and the secondary flywheel 12, but it must hold during the entire mounting operation. This couple will be able to

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 example be greater than about 10 Nm. Thus, the rupture may take place at the first start of the engine, or a little later, when the vehicle will be driven for the first time, with a gear engaged. This torque could just as easily be applied directly by the operator who carried out the assembly if this is desired.

 In the case where the temporary immobilization means 30 is a point of glue 31, the rupture of this means consists in tearing off the glue at the level of its fixing to one or the other of the two flywheels, or possibly to internal tearing of the glue.

 In the case where the temporary immobilization means 30 is a pin 32, the rupture will take place at the location of the zone of least resistance 32c provided for this purpose.

 Finally, in the case where the temporary immobilization means 30 is a wire, the latter can be cut or torn off at its attachment to one or the other of the two flywheels.

 Preferably, the immobilizing means 30 must not allow debris to escape when it breaks so as not to interfere with the normal operation of the clutch. Thus, taking for example the case of the pin, one will choose a plastic material making it possible to obtain a frank break.

 In FIGS. 5 and 6, an alternative embodiment can be seen in which a tool 40 for holding the secondary flywheel 12 is inserted inside the different orifices 14 thereof, as well as in the corresponding orifices 22 of the primary flywheel 11 This tool 40 is put in place during assembly of the module.

 This tool 40 takes the form of a crown 42 or a washer provided with several cylindrical tubes 44. Each tube 44 engages in the orifices 14 and 22 of the two flywheels while maintaining these orifices perfectly aligned during transport and assembly. of the module by the operator on the crankshaft 20. The operator can therefore pass through the tubes 44 a tightening tool (not shown) and possibly the screws 25 if these are not previously mounted on the primary flywheel 11 .

 After screwing the module onto the crankshaft 20, the operator removes the removable tool 40 using protruding tabs 46 provided for this purpose.

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 In the case where the screws 25 are previously mounted in the module, provision can be made to hold them in position in the tubes 44 either by radial tightening in the evening using elastic stops 48 as can be seen in FIG. 6 where the module is ready to be fixed on the crankshaft.

 This maintenance in position can be achieved so that the ends of the screws do not protrude from the primary flywheel, or that the screws are on the contrary completely driven into their housing.

 Any other holding tool using other housings on each of the steering wheels can be used.

 It should be understood, however, that these examples are given solely by way of illustration of the object of the invention of which they do not in any way constitute a limitation for their realization.

 Thus, the number and location of the immobilization means can vary, as can the material used.

 Likewise, the damper between the two flywheels can be constituted by curved or radially oriented springs, mounted with prestressing or with play.

Claims (19)

1. Double damping flywheel (10) for filtering vibrations between an engine and a motor vehicle transmission system, this double flywheel (10) comprising a primary flywheel (11), a secondary flywheel (12) free to rotate relative to a primary flywheel around a main axis, and a vibration damping mechanism (13) interposed between the primary flywheel (11) and the secondary flywheel (12), characterized in that it further comprises at least means (30) for temporarily immobilizing in a determined angular position the secondary flywheel (12) relative to the primary flywheel (11).  2. Double damping flywheel (10) according to claim 1, characterized in that the immobilization means (30) breaks under the effect of a low torque exerted between the secondary flywheel and the primary flywheel so as to be able to release the rotation lock of the secondary flywheel (12) relative to the primary flywheel (11).  3. Double damping flywheel (10) according to any one of the preceding claims, characterized in that the temporary immobilization means (30) remains integral with the primary flywheel (11) and / or the secondary flywheel (12) after it breaks .  4. Double damping flywheel (10) according to any one of the preceding claims, characterized in that the temporary immobilization means (30) consists of an adhesive material connecting the primary flywheel (11) to the secondary flywheel (12).  5. Double damping flywheel (10) according to claim 4, characterized in that the adhesive material is an adhesive (31) hot melt.  6. Double damping flywheel (10) according to any one of the preceding claims, characterized in that the temporary immobilization means (30) has a zone of least resistance (32c).  7. Double damping flywheel (10) according to any one of claims 1 to 3 and 6, characterized in that the temporary immobilization means (30) comprises a pin (32) of which a first part (32a) is housed in an orifice (16) of the primary flywheel (11), a second part (32b) is housed in an orifice (18) of the secondary flywheel (12).  8. Double damping flywheel (10) according to claim 7, characterized in that the pin (32) is made of plastic material. <Desc / Clms Page number 9>  9. Double damping flywheel (10) according to any one of claims 1 to 3, characterized in that the temporary immobilization means (30) consists of a metal wire welded to the primary (11) and secondary (12) flywheels. .  10. Double damping flywheel (10) according to any one of the preceding claims, characterized in that the temporary immobilization means (30) does not release any debris after it breaks.  11. Double damping flywheel (10) according to any one of the preceding claims, characterized in that the temporary immobilization means (30) is mounted in an area close to the external periphery of the double flywheel (10).  12. Double damping flywheel (10) according to any one of the preceding claims, characterized in that several temporary immobilization means (30) are distributed around the periphery of the double flywheel (10).  13. Double damping flywheel (10) according to any one of the preceding claims, characterized in that a part of the temporary immobilization means (30) is mounted on an intermediate piece (15) fixed to the primary flywheel (11) or secondary (12).  14. Double damping flywheel (10) according to claim 13, characterized in that this intermediate part (15) belongs to a device for determining the speed of rotation of the double flywheel.  15. Double damping flywheel (10) according to claim 1, characterized in that the temporary immobilization means (30) is constituted by a removable tool (40) adaptable in housings (14) and (22) respectively of the flywheels primary (11) and secondary (12).  16. Double damping flywheel (10) according to claim 15, characterized in that the tool (40) takes the form of a crown (42) provided with several tubes (44) mounted in the orifices (14) and (22) for the passage of a clamping tool and possibly fixing screws (25).  17. Double damping flywheel (10) according to claim 16, characterized in that the tool (40) is equipped with prominent extraction means (46) for its removal once the double flywheel is mounted.  18. Double damping flywheel (10) according to claim 16 or 17, characterized in that the tubes (44) are equipped with stops (48) for <Desc / Clms Page number 10>  axially hold the fixing screws (25) before mounting the double flywheel (10) on the crankshaft (20).  19. Double damping flywheel according to claim 18, characterized in that the tubes (44) are fitted with directional action stops (48) acting on the screws, to allow passage in one direction.