FR2661721A1 - SELF-CONTAINING FRICTION CLUTCH WITH DISC WITH LOW INERTIA. - Google Patents

Abstract

The invention relates to an assembly of a clutch. According to the invention, it comprises a cover (11), a friction plate (20), a flywheel (22), a pressure plate (26), friction pads (25, 28) and an assembly of a driven disc (40). The invention applies in particular to the automotive industry.

Description

The present invention generally relates to friction clutches

and in particular to clutches

  autonomous devices with a low inertia driven disk.

  Clutches are well known devices that are used to selectively connect a source of rotational power, such as the crankshaft of a

  motor, to a driven mechanism, such as a transmission.

  Typically, a clutch cover is connected to a flywheel carried at the end of the crankshaft of the engine for rotation with it. Between the flywheel and the clutch cover is arranged a pressure plate. The pressure plate is connected for rotation to the flywheel and the cover but it can move axially relative to them An assembly of a shift lever is provided to selectively move the pressure plate to

  forward and backward in the axial direction.

  An assembly of a driven disk is arranged in

  the clutch between the pressure plate and the steering wheel.

  The assembly of the driven disk is carried on a clutch output shaft which is also the input shaft of the transmission. When the pressure plate is moved towards the steering wheel, the assembly of the driven disk is in engagement. friction between them, forcing the output shaft of the clutch to rotate with the flywheel, the cover and the pressure plate In this manner, the clutch is engaged to transmit the power of the engine to the transmission to drive the vehicle When the pressure plate is moved away from the steering wheel, the assembly of the driven disk is released from this frictional engagement, to disconnect this drive connection A clutch is typically released to allow a

  shifting operation in the transmission.

  The transmission is often provided with a conventional synchronizing device The synchronizing device is typically mounted on the input shaft of the transmission for rotation with it and it has one or more friction surfaces when the clutch is disengaged and When a change operation is about to occur, the friction surface of the synchronizing device engages with a corresponding surface formed on a selected gear of the transmission to synchronize the rotational speeds of the drive shaft. input and selected gear This gear synchronization is necessary to prevent an undesirable shock of the gear teeth during the change operation Given the relatively large inertia of the various pinions in rotation in the transmission, the synchronization device modifies mainly the rotational speed of the input shaft of the transmission so that it matches with the rotational speed of the transmission gear selected when a change operation is about to occur. However, as mentioned above, the assembly of the driven disk is usually mounted on the input shaft of the transmission for rotation with it. As a result, the inertial load applied to the synchronization device during the Friction engagement with the selected gear of the transmission is determined by the sum of the input shaft weight and the weight of the driven disc assembly. The additional weight of the driven disc assembly increases wear on the drive. synchronization device and can also affect the overall quality of the change operation Thus, it is desirable to keep the weight of the driven disc assembly to a minimum while still offering a

satisfactory performance.

  The present invention relates to an autonomous friction clutch having an assembly of a low inertia driven disk. The clutch comprises a cover having a

  friction plate attached to it in spaced relation.

  The cover and the friction plate are fixed to a flywheel in one unit, the friction plate being disposed adjacent to the flywheel Radial and circular grooves are formed in the face of the flywheel, close to the friction plate to allow the flow of the cooling air A pressure plate is arranged between the cover and the friction plate for rotation with it and axial movement relative thereto. Friction pads are attached to the adjacent faces of the friction plate and the pressure plate A assembly of a driven disk is arranged between

  the friction plate and the pressure plate.

  The driven disc assembly includes a support plate that extends between the pads attached to the friction plate and the pressure plate. When the clutch is engaged, the friction pads on the friction plate and the pressure plate come in frictional engagement with the support plate for rotation The support plate may have a curved outer peripheral edge

to increase its stiffness.

  The object of the present invention is to provide an autonomous friction clutch having an assembly of a

drive with low inertia.

  Another object of the present invention is to provide such a frictional self-contained clutch having a friction plate for covering a engaging surface.

of the steering wheel by protecting it.

  Another object of the present invention is to provide such an autonomous friction clutch having

  better cooling capabilities.

  The invention will be better understood, and other purposes, features, details and advantages thereof

  will become clearer during the description

  explanatory text which follows with reference to the accompanying schematic drawings given solely by way of example illustrating an embodiment of the invention, and in which: FIG. 1 is an extreme elevational view of a portion of an autonomous clutch; friction according to the invention; Figure 2 is a sectional and elevational view taken along line 2-2 of Figure 1 of the entire clutch; and FIG. 3 is an extreme elevational view of the

  flying, made along the line 3-3 of Figure 2.

  Referring now to the drawings, FIG. 1 shows the portion of the cover assembly of a friction clutch, generally indicated at 10, according to the present invention. The clutch 10 has a generally annular cover, generally indicated at 11, which is adapted to rotate about a central axis The cover 11 is formed with a flange portion 12 extending radially outwardly, an axially extending flange portion 13 and a radially extending end wall portion. The end wall portion 14 is provided with a number of ramp portions 15 extending radially inward. A central opening 16 through the

  lid 11 is defined by the ramp portions 15.

  The opening 16 is coaxially aligned with the axis of

rotation of the clutch 10.

  An annular friction plate 20 is connected to the flange portion 12 of the cover 11 by a number of rivets 21. The flange portion 12 of the cover 11 and the friction plate 20 are attached to a flywheel 22 by a number of bolts. Threaded 23 (see Figure 2) As is well known, the flywheel 22 is connected to a crankshaft 24 or similar means of rotation drive Thus, the flywheel 22, the friction plate 20 and the cover 11 all rotate together during One or more conventional friction pads 25 are connected to the side of the friction plate which faces the lid 11, by rivets or similar means. These friction pads 25 have a function which

  will be explained in more detail below.

  A pressure plate 26 is disposed between the cover 11 and the friction plate 20, near the end wall portion 14. A number of raised protuberances 27 are formed on the side of the pressure plate 26 which faces the cover 11 One or more conventional friction pads 28 are connected to the side of the pressure plate 26 which is remote from the lid 11, by rivets or similar means The protuberance portions 27 and the friction pads 28 have functions which will be explained in detail below The pressure plate 26 is connected to the cover 11 by conventional tongues 29 or other means for rotation, while permitting limited axial movement relative thereto. The tongues 29 also serve for the elastic biasing of the

  pressure plate 26 towards the lid 11.

  A lever control mechanism is provided for selectively moving the pressure plate 26 away from the cover 11 and toward the friction plate 20. The mechanism comprises a number of radially extending levers 30 which are pivotally connected to the portion of end wall 14 of cover 11 by respective pivots 31 The outer ends of the levers 30 engage protuberances 27 which are formed on the pressure plate 26 The inner ends of the levers 30 engage a conventional trigger bearing 32 The bearing 32 is arranged around An output shaft 33 of the clutch 10 As best seen in FIG. 2, the movement of the bearing 32 to the right forces the levers 30 to pivot about the pivots 31, thereby displacing the outer ends of the levers and the pressure plate 26 to the left When the bearing 32 is moved to the left, the pressure plate 26 is pulled to the right under the sollicita tion

  tabs 29 as previously described.

  An assembly of a driven disk, indicated generally at 40, is keyed on the output shaft 33 of the clutch 10 The assembly 40 comprises a central hub 41 which is wedged on the output shaft 33 and a plate of support 42 which is mounted around the hub 41 for a limited rotation relative thereto. A conventional spring damping mechanism, generally indicated at 43, allows the rotational drive connection between the support plate 42 and the hub 41. 42 extends radially outward between the friction pads 25 and 28 carried on the friction plate 20 and the pressure plate 26, respectively the outer peripheral edge of the support plate 42 is slightly curved towards the plate of friction 20, as shown in 42a, for reasons that

will be explained below.

  Thus, when the pressure plate 26 is moved to the left as described above, the support plate 42 is locked between the friction pads 25 and 28. As a result, the assembly 40 of the driven disk is friction engagement with the steering wheel 22, the plateau of

  friction 20 and the cover 11 for rotation with them.

  When the bearing 32 is moved to the left, the support plate 42 is disengaged, allowing relative rotation of the assembly 40. A Belleville spring 44 or similar resilient means is provided to normally bias the pressure plate 26 to the left. internal device of the spring 44 is carried on the ramp portions 15 of the lid while the edge 7, external device engages the levers 30 by a conventional slip ring 45 As is well known, the spring 44 reacts against the cover 11 to solicit the internal ends of the levers 30 to the right, thereby soliciting the pressure plate 26 to the left. Referring now to FIG. 3, the side of the flywheel 22 which faces the friction plate 20 is illustrated. As can be seen, the surface of the flywheel 22 has a number of radially extending grooves 22a which The radial grooves 22a extend completely to the outer peripheral edge of the flywheel 22. In addition, one or more circular grooves 22b are formed in the surface of the flywheel 22. Two concentric circular grooves 22b are shown in the illustrated embodiment The grooves 22a and 22b allow air to flow between the friction plate 20 and the

  This airflow promotes cooling.

  friction plate 20 which is heated during use due to a frictional engagement

with the support plate 42.

  As described above, the support plate 42 is generally flat and annular in shape, having no friction pads attached thereto. The friction pads 25 and 28 are attached to the tray.

  friction 20 and the pressure plate 26, respectively.

  This structure is desirable because it removes a large amount of weight from the support plate 42. As a result, the inertia of the support plate 42 is considerably reduced and its frictional engagement causes much less wear than if a certain number of skids The friction pad 25 and 28 provided on the friction plate 20 and the pressure plate 26, respectively, provide a further advantage in that the number of these friction pads 25 and 28 (as well as the material that is used) can be changed as desired without affecting the weight or inertia of the support plate 42 and therefore the assembly of the driven disk 40 This is important because the platter carrier 42 is connected by hub 41 and output shaft 33 to a transmission (not shown) or similar device As the assembly 40 of the driven disk is keyed to the output shaft 33 in. When rotated with it, the transmission must be designed to take into account the rotational characteristics of the driven disk assembly. As the friction pads 25 and 28 are not mounted on the support plate 42, they can be changed without affect the weight or inertia of the assembly 40 of

led record.

  For the reasons described above, it is desirable that no friction pad be attached to the support plate 42. However, in the prior art driven disk assemblies, the attachment of the friction pads to the support plate provided an advantage, that is, they tended to stiffen the support plate and prevent its warping during use. Such warping tends to occur because the support plate is subjected to relatively high temperatures. and large forces when in friction engagement In order to prevent this from occurring with the friction plate 42, its outer peripheral edge is bent, as shown at 42. The curved edge 42 has a tendency to stiffen all the support plate 42 and to prevent it from buckling. The curved edge 42a of the support plate 42 can

  also serve as a wear indicator for the clutch 10.

  As shown in FIG. 2, a predetermined axial distance is defined between the friction plate 20 and the curved edge 42a when the clutch 10 is engaged and the friction pads 25 and 28 are not worn while the wear occurs, the axial thickness of the friction pads 25 and 28 decreases, and the support plate 42 and the pressure plate 26 are placed closer and closer to the friction plate 20 when the clutch 10 is engaged. Accordingly, the predetermined axial distance between the friction plate 20 and the curved edge 42a also decreases. When the thicknesses of the friction pads 25 and 28 have decreased in a sufficient amount, the curved edge 42a of the support plate 42 surface of the friction plate 20 when the clutch 10 is in engagement The noise produced by this scraping action produces a signal clearly audible to the operator, indicating that the friction pads 25 and 28 must be

soon replaced.

Claims (3)

R E V E N D I C A T IO N S   1 assembly of a clutch characterized in that it comprises: a cover (11) a friction plate (20) a flywheel (22) having a surface, said cover and said friction plate being connected to said steering wheel so that said friction plate is disposed adjacent the surface of said flywheel; a pressure plate (26) disposed between said lid and said friction plate and connected thereto for rotation therewith and for axial movement relative thereto between engaged and disengaged positions; first and second friction pads (25 and 28) which are attached to said friction plate and said pressure plate, respectively; and an assembly (40) of a driven disk which is disposed between the friction plate and the pressure plate, said assembly of the driven disk having a support plate which extends between said first and second friction pads so that said friction pads are in frictional engagement with said support plate for rotation with it when said   pressure plate is moved to its engaged position.   Assembly according to claim 1, characterized in that it further comprises a number of aligned openings which are formed through the cover and the friction plate and a corresponding number of threaded fastening means (23) which traverse said aligned openings to come in threaded engagement with the steering wheel.   Assembly according to Claim 1, characterized in that the support plate (42) comprises