EP1966510A2

EP1966510A2 - Torque transmission device comprising a flywheel and means for damping the oscillations of the flywheel

Info

Publication number: EP1966510A2
Application number: EP06842108A
Authority: EP
Inventors: Romain Cassu; Robert Kunsch; Shanjin Wang
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 2005-12-27
Filing date: 2006-12-06
Publication date: 2008-09-10
Also published as: FR2895471B1; FR2895471A1; WO2007074253A2; WO2007074253A3

Abstract

The invention relates to a device for the transmission of the torque of an engine comprising a drive shaft and a flywheel (20) provided with a hub (22) which is adapted in such a way as to be fixed to the drive shaft, an annular inertial mass (21) which has a larger diameter than the hub, is fixed thereto, and has a rear radial face (19) facing the crankshaft, and means for damping oscillations of the annular inertial mass in relation to said hub, said means comprising at least one damping element (30) which connects the hub to the annular inertial mass and can elastically deform itself following the direction of the axle (A1) of the drive shaft. According to the invention, the damping element comprises a central part (33) which is supported on the drive shaft, and an external part (312, 322) which is arranged in such a way as to be supported against the rear radial face of the annular inertial mass of the flywheel and to co-operate by friction with the same.

Description

TORQUE TRANSMISSION DEVICE COMPRISING A MOTOR FLYWHEEL AND DAMPING MEANS FOR DAMPING THE OSCILLATIONS

ENGINE STEERING WHEEL TECHNICAL FIELD TO WHICH THE INVENTION RELATES

The present invention generally relates to internal combustion engines.

It relates more particularly to a torque transmission device of an engine which comprises a driving shaft, a flywheel having a hub adapted to be fixed on the driving shaft and an annular inertial mass which, larger in diameter than the hub, is integral with this hub and has a rear radial face oriented on the crankshaft side, means for damping the oscillations of the annular inertial mass with respect to this hub, comprising at least one damping member connecting the hub to the inertial mass annular and able to deform elastically in the direction of the axis of the driving shaft.

The invention finds a particularly advantageous application for torque transmission devices comprising a flexible type flywheel.

TECHNOLOGICAL BACKGROUND

To reduce the motor vibrations in the medium frequency range (200-1000 Hz), a so-called softened flywheel is generally used.

To soften the flywheel it is known to make diametrically opposite through windows on the disk which allows to have flexibility around one or more preferred axes belonging to the middle plane of the flywheel, that is to say in the plane transverse to the axis of the driving shaft.

However, when the engine is running, the flexibility of the flywheel can cause, by bending of the inertial mass, deflections of the flywheel in the axial direction of the drive shaft which exceed the tolerable limit. This results in mechanical strength problems of the flywheel and the clutch friction device.

It is therefore necessary for this type of flywheel to find a damping system that reduces the axial deflections of the flywheel without having a significant impact on its flexural flexibility.

WO 2004/065807 describes, in its embodiment illustrated in Figure 13, a torque transmission device of an engine which comprises a flywheel. The flywheel comprises a hub adapted to be fixed on a driving shaft and an annular inertial mass fixed to the hub. It is also provided a damping member oscillations of the inertial mass annular with respect to this hub, able to deform elastically in the direction of the axis of the driving shaft, and which comprises an outer portion arranged to bear against and cooperate by friction with the rear radial face of the annular inertial mass. flywheel. However, in this device, the damping member is attached to the hub of the flywheel on the side of the clutch, that is to say against the face of the hub opposite the crankshaft. The damping member is mounted during assembly of the flywheel. The document WO 2004/065807 does not provide any possibility of adjusting the support force of the damping member against the annular flywheel mass of the flywheel. Such a setting would be particularly inconvenient, if not impossible, insofar as, to achieve such an adjustment, it would indeed be necessary to disassemble the flywheel to replace the damping member or insert the spacers.

OBJECT OF THE INVENTION The present invention proposes a novel torque transmission device adapted to reduce the axial deflections of the flywheel.

For this purpose, it is proposed according to the invention a torque transmission device of an engine which comprises a driving shaft, a flywheel having a hub adapted to be fixed on the driving shaft and an annular inertial mass which, moreover large diameter that the hub, is integral with the hub and has a rear radial face oriented on the side of the crankshaft, means for damping the oscillations of the annular inertial mass with respect to this hub, comprising at least one damping member connecting the hub to the annular inertial mass and able to deform elastically in the direction of the axis of the driving shaft, wherein the damping member comprises a central portion which bears on the driving shaft and a part external arranged to bear against and cooperate by friction with the rear radial face of the annular inertial mass of the flywheel.

When the flywheel bends, the damping member rubs on the portion of the annular inertial mass of the flywheel with which it is supported, which reduces the axial movements of the flywheel annular mass of the flywheel.

Thanks to the damping member adapted to deform elastically, the flywheel retains the flexibility that gives it its bending capacity. So the large amplitudes of the axial deflections of the inertial mass are reduced by friction of the damping member on the inertial mass, without significantly affecting the bending capacity of the entire flywheel. This damping member is a part independent of the flywheel and the crankshaft and becomes integral with the hub of the flywheel and crankshaft when assembling the transmission device Thus, the mounting of the damping device is simplified which reduces the production costs of the transmission device In addition, such a damping member uses for its fixation that the fixing screws of the flywheel hub and can be used regardless of the type of flywheel without having to add an additional fastening system

Finally, the fact that the central part of the damping member is located between the hub of the flywheel and the drive shaft, offers, when mounting the flywheel on the drive shaft, the possibility of adjusting the axial elastic return force exerted by the outer portion of the damping member on the annular flywheel flywheel mass

According to a first advantageous characteristic of the invention, the device comprises means for enabling, during the assembly of the flywheel with the drive shaft and the damping member, an adjustment of the axial elastic return force of friction exerted by the outer portion of the damping member The damping member can thus receive an adjustable preload so as to ensure a permanent contact of the damping means with the annular flywheel flywheel mass.

The prestressing level is the support force of the damping member against the annular flywheel mass of the flywheel Thanks to the arrangement of the damping member between the flywheel and the driving shaft, it is possible to adjust by means of the fixing screws of the hub of the flywheel on the driving shaft, the level of prestressing imposed on the damping member Thus, one can adjust the level of friction that one wishes to generate between the body of damping and the annular inertial mass during oscillations of the inertial mass Other advantageous and non-limiting characteristics of the torque transmission device according to the invention are as follows:

- The driving shaft having a fixing plate, the central portion of the damping member is located between the hub of the flywheel and the attachment plate of the driving shaft,

- The damping member has holes for the passage of fixing screws for passing through the flywheel hub and to be housed in the crankshaft,

the damping member comprises tabs which extend radially from the central part and whose end portion constitutes the outer part of the damping member,

the central part of the damping member is of annular shape and the damping member comprises two tabs which extend radially from the central part and whose end portion constitutes the outer part of the damping member , the flywheel having at least one preferred axis of flexion, each tongue is disposed along a preferred axis of flexion of the flywheel,

the outer part of the tongues is enlarged,

the damping member is a plate, the plate is a washer,

it comprises a plurality of damping members stacked on top of each other

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description with reference to the accompanying drawings of several embodiments given by way of non-limiting example, will make it clear what the invention consists of and how it can be achieved. appended

- Figure 1 is a side view of a flywheel and a crankshaft,

FIG. 2A is a rear view of the flywheel according to a first embodiment,

FIG. 2B is a view according to section A-A of the flywheel of FIG. 2A,

FIG. 3 is a sectional view in the median plane of the flywheel according to a second embodiment, FIG. 4A is a sectional view in the median plane of the flywheel according to a third embodiment,

FIG. 4B is a view according to section B-B of the flywheel of FIG. 4A,

FIG. 5A is a sectional view in the median plane of the flywheel according to a fourth embodiment,

FIG. 5B is a view along section C-C of the flywheel of FIG. 5A.

As a preliminary, it will be noted that the identical or similar elements of the different embodiments represented in the different figures will, as far as possible, be referenced by the same reference signs and will not be described each time.

FIG. 1 shows part of a torque transmission device of an internal combustion engine of a motor vehicle

This torque transmission device comprises a driving shaft, HERE a crankshaft 10 provided with a plate 11 for attachment, and a flywheel 20 intended to cooperate with a clutch disc (not shown)

As represented in FIGS. 2A and 2B, the flywheel 20 comprises, on the one hand, a hub 22 adapted to be fixed to the plate 11 of the crankshaft 10 and, on the other hand, an annular inertial mass 21 which, on a larger scale, Diameter that the hub 22, is integral with the hub 22 As the hub, the inertial mass 21 has a rear radial face 19 oriented on the side of the crankshaft 10 and a front radial face 18 opposite intended to cooperate by friction with the disc of clutch (not shown)

The hub 22 constitutes the central part of the flywheel 20 Here the flywheel 20 has openings, or through windows 23, 24, 25, 26 formed in the hub or central portion, of the flywheel

Here, the two through windows 26 are diametrically opposed and symmetrical to each other with respect to the axis X perpendicular to the plane of symmetry of the crankshaft 10 which allows to have flexibility around this axis X Similarly, the two through windows 23, 24 are diametrically opposed and symmetrical to one another with respect to the Y axis, that is to say the axis defined by the intersection of the average plane of the flywheel 20 and the plane of symmetry of the crankshaft 10 which allows to have flexibility around this axis

The levels of flexibility around the two preferred axes X and Y can be adjusted by acting on the size and shape of the through windows The positions of these preferred axes with respect to each other and with respect to the plane of the crankshaft can be adjusted in order to decouple the bending modes around each of these two axes, that is to say in order to position , in the frequency range, the bending mode of the wheel around the X axis far enough from the bending mode around the Y axis not to increase the vibration of the crankshaft.

This torque transmission device also comprises means for damping the oscillations of the annular inertial mass 21 with respect to the hub 22. These damping means comprise a damping member 30 connecting the hub 22 to the annular inertial mass 21 and able to deform elastically in the direction of the axis A1 of the crankshaft 10.

Advantageously, the damping member 30 comprises a central portion 33 which bears on the driving shaft 10 and an outer portion 312, 322 arranged to bear against and cooperate by friction with the rear radial face 19 of the inertial mass 21 annular flywheel 20.

Preferably, the central portion 33 of the damping member 30 is located between the hub 22 of the flywheel 20 and the plate 11 for fixing the crankshaft 10. Alternatively, it is possible to fix the central portion 33 of the member damping on another part of the crankshaft. Here, the damping member 30 is a flexible plate 30 made of a material, for example steel, sufficiently elastic to be able to deform under the effect of the deflections of the inertial mass and sufficiently strong mechanically to be able to hold under the effect of the alternating stresses imposed by the inertial mass in flexion. The plate is in one piece and is obtained by stamping and cutting. The plate has a small thickness, for example between 1 mm and 3 mm.

According to a first embodiment of the invention shown in Figures 2A and 2B, the flexible plate 30 comprises tongues 31, 32 which extend radially from the central portion 33 and whose end portion constitutes the outer portion 312, 322 of the damping device. The central portion 33 is here in the form of a ring and interconnects the two tabs. These tongues 31, 32 also comprise an intermediate portion 311, 321 inclined with respect to the end portion of the corresponding tongue and with respect to the central portion 33 of the plate 30. The hub 22 of the flywheel 20 has holes for the passage of the fixing screws 12. The fixing ring is provided with through holes 34 intended to be positioned vis-à-vis the fixing holes of the hub 22 of the flywheel 20 , in order to pass through elements 12 for centering and fixing the flywheel 20 on the crankshaft, for its attachment between the hub 22 of the flywheel 20 and the plate 11 of the crankshaft 10.

As shown in FIG. 2A, each tongue is disposed along a preferred bending axis of the flywheel 20, here the Y axis. As a variant, it would also be possible to arrange tabs along the X axis. of the transmission device is carried out as follows.

The crown-shaped central part of the flexible plate is first attached to the crankshaft plate. Then the hub of the flywheel is positioned on the crankshaft plate vis-à-vis the ring so that the fixing holes of the hub are in front of the passage holes of the crown of the flexible plate to allow attachment flywheel and plate on the crankshaft plate. When tightening the flywheel fixing screws on the crankshaft, the inclined intermediate portion of the tongue is flattened which generates a prestressing force of the tongue on the annular mass. The tightening of the screw makes it possible to adjust the planarization and thus the level of prestressing. By against it may be useful to provide washers to compensate for any play between the hub of the flywheel and the central portion of the plate, depending on the desired level of clamping.

Thus, thanks to the prestressing force generated, it ensures a permanent contact of the damping means with the annular inertial mass of the flywheel.

In operation, when the flywheel 20 vibrates in bending about the axis perpendicular to the plane of symmetry of the crankshaft 10, the annular mass 21 moves axially relative to its hub 22 and tries to pull the tongues 31, 32 also in the direction axial. As a result, a shear force is created between the tongues 31, 32 and the annular mass 21. Beyond a certain limit, the tongues 31, 32 slide relative to the annular mass 21 and thus create a friction on the ring mass. These alternative friction makes it possible to attenuate the movements of the annular mass 21 in the axial direction and therefore to reduce the axial deflections of the flywheel 20 in flexion. According to a second embodiment shown in FIG. 3, which is a variant of the first embodiment (FIGS. 2A and 2B), provision may be made to use a plate 60 provided with tongues 61, 62 whose external parts 63, 64 are widened at their end intended to bear against the rear radial face 19 of the inertial mass 21. Thus the contact surfaces between the tongues and the annular inertial mass are increased.

It is also possible according to a third embodiment shown in FIGS. 4A and 4B to produce a stack of flexible plates. Here a second flexible plate 40 is stacked on the first flexible plate 30. The tongues 31, 41 and 32, 42 of each of these plates 30, 40 are superimposed with each other, which makes it possible to increase the friction during the oscillation of the flywheel around its axis of bending Y.

The surfaces of the portions of the tongues and portions of the annular inertial mass intended to be in contact can be adapted to promote contact between these two parts by means of a suitable machining process and / or by depositing a specific coating .

It can also be provided that the annular inertial mass is provided with specific arrangements (not shown) for receiving the ends of the tongues in order to improve the endurance resistance of the interfaces between the steel tongues and the cast ring mass.

According to a fourth embodiment shown in FIGS. 5A and

5B, the flexible plate is a washer 50, that is to say a hollow disc at the passage of the crankshaft and fastening screws. This washer 50 is in contact with the entire rear radial face of the hub 22 and the annular mass 21 of the flywheel 20.

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any variant within his mind.

Here the flywheel is perforated. Alternatively, it can be provided to use the damping member as described above with a solid flywheel.

In addition, the flywheel is here monobloc, but, alternatively, it can be provided that the annular inertial mass and the hub flywheel form separate parts. Similarly the damping member is monobloc, but, alternatively, it could consist of several parts. Finally, the damping member as described above can be used with a flexible flywheel comprising an annular mass and a flexible annular flange.

Claims

A torque transmission device of an engine comprising:

a driving shaft (10),

- a flywheel (20) having a hub (22) adapted to be fixed on the driving shaft (10) and an annular mass (21) which, larger in diameter than the hub (22), is integral with this hub (22) and has a rear radial face (19) oriented towards the crankshaft side,

means for damping oscillations of the annular inertial mass (21) with respect to this hub (22), comprising at least one damping member (30; 40; 50; 60) connecting the hub (22) to the inertial mass (21) annular and able to deform elastically in the direction of the axis (A1) of the driving shaft (10), characterized in that the damping member (30; 40; 50; 60) comprises a central part (33) which bears on the driving shaft (10) and an outer part (312, 322; 63, 64) arranged to bear against and frictionally engage with the rear radial face (19) of the an inertial flywheel mass (21) of the flywheel (20) and in that the damping member (30; 40; 60) comprises radially extending tongues (31,32; 41; 42; 61,62). from the central portion (33) and whose end portion constitutes the outer portion (312, 322, 63, 64) of the damping member (30; 40; 60).

2. Torque transmission device according to the preceding claim, characterized in that, the driving shaft (10) having a plate (11) for fixing, the central portion (33) of the damping member (30; 50) is located between the hub (22) of the flywheel (20) and the plate (11) for fixing the driving shaft (10).

3. Torque transmission device according to one of the preceding claims, characterized in that it comprises means (12) for allowing, during the assembly of the flywheel (20) with the driving shaft (11) and the damping member (30; 40; 50; 60), an adjustment of the axial elastic frictional return force exerted by the outer portion (312, 322; 63, 64) of the damping member.

Torque transmission device according to one of the preceding claims, characterized in that the damping member (30; 40; 50; 60) has holes (34) for the passage of fixing screws for passing through the hub (22) of the flywheel (20) and to be housed in the crankshaft.

Torque transmission device according to one of the preceding claims, characterized in that the central portion (33) of the damping member (30; 40; 60) is of annular shape and the damping member (30; 40; 60) comprises two tabs (31,32; 41; 42; 61,62).

6. Torque transmission device according to one of the preceding claims, characterized in that, the flywheel (20) having at least one preferred axis (X, Y) bending, each tab is disposed along an axis (Y) preferred bending flywheel (20).

Torque transmission device according to one of the preceding claims, characterized in that the outer portion (63, 64) of the tongues (61; 62) is widened.

8. torque transmission device according to one of the preceding claims characterized in that the damping member (30; 40; 50; 60) is a plate (30; 40; 50; 60).

9. Torque transmission device according to the preceding claim, characterized in that the plate is a washer (50).

Torque transmission device comprising a plurality of damping members (30; 40; 50; 60) according to one of the preceding claims stacked on top of one another.