FR2882579A1 - Internal combustion engine`s torque transmission system for motor vehicle, has flywheel including face that comprises fin, where fin uniformly covers total surface of face and extends along radius of flywheel - Google Patents

Abstract

The system has a flywheel (10) and a clutch disc (59), where the flywheel includes a face (13) opposite to the clutch disc. The flywheel has another face (16) that is opposite to the former face and is oriented to a side of the flywheel. The latter face includes a fin (30), where the fin uniformly covers the total surface of the latter face and extends along a radius of the flywheel. An independent claim is also included for a power-unit of a motor vehicle comprising a torque transmission system.

Description

TECHNICAL FIELD TO WHICH THE INVENTION REFERS

  The present invention generally relates to internal combustion engine torque transmission systems.

  It relates more particularly to a torque transmission system comprising a flywheel and a clutch disc, the flywheel comprising a first face facing the clutch disk and a second face, opposite to the first face, oriented on the motor side.

  It also relates to a powertrain motor vehicle comprising such a torque transmission system.

BACKGROUND

  Currently, it is already known a torque transmission system of the aforementioned type which comprises a flywheel connected to a crankshaft and a clutch device connected to an input shaft of a gearbox.

  The flywheel is made of a circular plate, called canvas, bordered by a rim.

  This rim carries a ring gear, on which comes to engage a starter to launch the engine.

  The flywheel is rotated by the crankshaft linked to the engine. In particular, the flywheel, thanks to its large mass, stores the kinetic energy produced during an explosion and expansion phase in the engine, and it restores this kinetic energy during a dead time of the engine (phases intake, exhaust, compression), thus regulating the rotation of the crankshaft.

  The flywheel is responsible for rotating the clutch device. The engine torque is transmitted from the flywheel to the clutch disk and then to the input shaft of the gearbox.

  Nowadays, motor vehicle engines achieve mechanical performance increasingly important. The mechanical elements of the torque transmission system of the engine are then very physically and therefore thermally stressed.

  Now, the flywheel transmits the engine torque to the friction clutch disc. This transmission of friction torque is effected by a side of the flywheel which cooperates with friction linings disposed on the clutch disc. This face of the flywheel is then very thermally stressed, especially when the driver is looking for the skidding point in the plugs or in a rib.

  The mechanical stress is such that sliding occurs between the friction linings of the clutch plate and the corresponding flywheel face. These slips are responsible for significant heating that degrade the mechanical characteristics of the clutch disc friction linings.

  When the degradation of the mechanical characteristics of the friction linings is too great the clutch disk no longer transmits the power of the engine to the input shaft of the gearbox.

  OBJECT OF THE INVENTION In order to overcome the aforementioned drawbacks of the state of the art, the present invention proposes a torque transmission system of an internal combustion engine in which the temperature rises between the clutch plate and the flywheel. are dissipated.

  For this purpose, there is provided according to the invention a torque transmission system of an internal combustion engine as defined in the introduction in which it is expected that the second face of the flywheel comprises fins.

  Thus, thanks to the fins on the second face of the flywheel according to the invention, the heat exchange surface with air is very significantly increased. Thermal exchanges are then favored. This results in a dissipation of the heating of the parts of the flywheel and the clutch device and in particular the friction linings of the clutch disc. The mechanical characteristics of the friction linings of the clutch disk are thus preserved.

  According to another advantageous characteristic of the invention, the fins cover, uniformly, the entire surface of the second face of the flywheel.

  Thus, the distribution of the mass of the flywheel is homogeneous, this homogenization of the mass of the flywheel being necessary for a good regularization of the operation of the engine.

  According to another advantageous characteristic of the invention, the flywheel comprising a rim, the fins have ridges which all extend in a plane defined by the lateral contour of the rim oriented towards the engine.

  The size of the flywheel is then unchanged. The size of the flywheel is an important factor because the flywheel is located near the engine.

  According to another advantageous characteristic of the invention, the fins follow helical portions which extend between the center and the edge of the flywheel.

  This geometrical configuration of the fins makes it possible to generate a circulation of air around the fins in order to promote the dissipation of heat by convection around the fins.

  According to another advantageous characteristic of the invention, the fins extend along spokes of the flywheel.

  Thus, this geometrical configuration of the fins makes it possible to generate an air flow in order to promote the dissipation of heat by convection around the fins, while offering a simple method of obtaining the fins.

  According to another advantageous characteristic of the invention, the fins extend in concentric circles centered on the flywheel.

  Thus the cooling of the flywheel is essentially by conduction.

  According to another advantageous characteristic of the invention, the fins 20 rise perpendicularly to the second face of the flywheel.

  Thus, the structure of these fins is simple which facilitates the process of obtaining these fins.

  According to another advantageous characteristic of the invention, the fins form with the second face of the flywheel an acute angle.

  The acute angle introduced makes it possible to control the circulation of the air around the flywheel while using fins of simple structure.

  According to another advantageous characteristic of the invention, the fins and the flywheel form a single piece obtained by casting without mass variation of the flywheel.

  Thus, compared to the flywheel according to the state of the art, the flywheel according to the invention is of the same mass. There is then no rebalancing of the flywheel to perform.

  The invention also relates to a motor vehicle power unit comprising a torque transmission system as mentioned above.

  DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

  The following description with reference to the accompanying drawings given as non-limiting examples, will make it clear what the invention is and how it can be achieved.

  In the accompanying drawings: - Figure 1 is a schematic view of a portion of a torque transmission system according to the invention; FIG. 2 is a perspective view of the first face of the flywheel of the torque transmission system of FIG. 1; and FIG. 3 is a perspective view of the second face of the flywheel of the torque transmission system of FIG. 1.

  In Figure 1 there is shown a portion of a torque transmission system of an internal combustion engine.

  This system comprises a flywheel 10 and a clutch device 50.

  The flywheel 10 forms a base to which is fixed all the clutch device 50.

  The clutch device 50 comprises the following elements: - a clutch disc 59, - a pressure plate 52 intended to exert a strong pressure on the clutch disc 59, - a diaphragm spring 53 intended to drive the plate pressure device 52 against the clutch disc 59, a series of pins 54 located on the periphery of the diaphragm spring 53 and intended to guide the diaphragm spring 53, a thrust bearing 55 intended to cooperate with the diaphragm spring 53, a clutch fork 57 which controls the thrust bearing 55, and a clutch cover 58.

  The clutch disk 59 is a thin sheet disk. This disc is provided with friction linings 51 on both sides. The clutch disc 59 slides through splines (not shown) of an input shaft 56 of a gearbox (not shown).

  The clutch disc 59, clamped between the flywheel 10 and the pressure plate 52, is rotated by adhesion. By means of the splines, the input shaft 56 of the gearbox is in turn rotated.

  The flywheel 10 is formed of a circular plate called web 14 having two faces 13,16 and a rim 43 which borders the web 14. The rim 43 is formed with the web 14.

  The flywheel 10 comprises a first face 13 vis-à-vis the clutch disc 59, and a second face 16, opposite the first face 13, oriented on the motor side.

  The rim 43 serves as a base for a ring gear 80, called a starter ring, cooperating with a starter (not shown).

  The flywheel 10 is attached to a crankshaft 24 itself connected to the engine.

  More particularly, the crankshaft 24 is equipped with a fixing plate 23 which is screwed by means of tapped holes 11 around the hub 12 of the flywheel 10. The hub 12 can also accommodate one end of the crankshaft 24.

  As shown in Figure 2, the fabric 14 is corrugated so that the central portion of the first face 13 of the flywheel 10 is adapted to the size of the clutch device 50, while the peripheral portion of the first face 13 provides a friction surface friction lining 51 of the clutch disc 59. Of course, the second face 16 of the flywheel is also corrugated.

  The periphery of this first front face of the flywheel 10 comprises a ring gear called target PMH (Top Dead Center) 40 coming from formation with the flywheel 10. This target PMH 40 has a tooth of greater width than the other teeth of the target PMH, called acquisition tooth PMH 41. This acquisition tooth PMH 41 serves as a marker, for the adjustment of the combustion in the engine, a sensor, called PMH sensor (not shown) positioned at the height of the target PMH 40 in a housing (not shown) in which is mounted the torque transmission system of the engine.

  As shown in FIG. 2, below the PMH target 40, there are provided studs 70 arranged in a ring and having tapped holes 71 which make it possible to fix the clutch device 50 to the flywheel 10.

  To solve problems of alignment in operation of the crankshaft 24 with respect to the input shaft 56, it is also possible to use a ball bearing (not shown), called a guide bearing, housed in the hub 12 of the flywheel 10. This guide bearing then serves to support the end of the input shaft 56 of the gearbox so that the flywheel 10 and the input shaft 56 of the gearbox are properly aligned on the same rotation axis.

  Advantageously, as shown in FIG. 3, the second face 16 of the flywheel 10 comprises fins 30. Here, the fins 30 cover the entire surface of the second face 16 of the flywheel 10. Moreover, these fins 30 are distributed uniformly on said surface of the second face 16 of the flywheel 10.

  The fins 30 have ridges 31 which all extend in a plane defined by the lateral contour of the rim 43 facing the engine. The height of each fin 30 varies as a function of the corrugations of the second face 16 of the flywheel 10.

  FIG. 3 shows an embodiment according to the invention in which the fins 30 follow helical portions which extend between the hub 12 and the rim 43 of the flywheel 10.

  According to a first variant of the invention not shown, it can be provided that the second face of the flywheel is provided with fins which extend along radii of the flywheel.

  To simplify the principle of obtaining these fins, it is possible to raise them perpendicular to the second face of the flywheel.

  Finally, if one wishes to control the orientation of the air circulation around the flywheel can be used fins forming with the second face of the flywheel an acute angle.

  A second variant of the invention not shown may consist of providing fins which extend in concentric circles centered on the center of the flywheel. As for the first variant, the fins can rise perpendicularly to the second face of the flywheel or form an acute angle with the second face.

  The fins 30 are formed with the flywheel 10 by casting. In addition, advantageously, the implantation of fins 30 does not vary the mass of the flywheel 10 since they are arranged in the thickness of the web 14 of the flywheel 10.

  It should be noted that the use of cooling fins 30 on the second face 16 of a flywheel 10 applies to both a flexible flywheel and a rigid flywheel.

  The flywheel 10 cooperates with the clutch device 50 in the following manner: the clutch fork 57 is controlled by a clutch pedal (not shown). This clutch fork 57 controls engagement or disengagement of the clutch disk 59 on the flywheel 10. In order to engage the clutch disk 59 on the flywheel 10, the fork loosens the thrust bearing 55 of the As the middle of the diaphragm spring 53 is released, the set of pins 54 guides the diaphragm spring 53 which presses the pressure plate 52 against the clutch disc 59. The clutch is then secured to the flywheel 10.

  The force that the clutch disc 59 can receive from the flywheel 10 depends on the friction between the clutch disk 59 and the flywheel 10, and with what force the diaphragm spring 53 presses on the pressure plate 52.

  When the engine is running and the flywheel 10 is secured to the clutch disk 59, the fins 30 of the second face 16 of the flywheel 10 generate dissipation by conduction and / or convection of the heat released by the interaction between the first face 13 of the flywheel 10 and the friction lining 51 of the clutch disc 59.

  Indeed, the flywheel 10 is rotated about its axis of rotation by the crankshaft 24. This drive rotation of the flywheel 10 generates, according to the arrangement of the fins 30, a relative displacement of the air relative to the fins 30 or a circulation of air between the fins 30.

  Thus, a provision of the concentric circles in fins, rising perpendicularly to the second face of the flywheel or having with it an acute angle, causes a relative movement of air relative to the fins, but does not participate in the circulation air around the flywheel. In this geometric configuration, the dissipation of the heat released between the flywheel and the clutch disk is therefore essentially by conduction along the fins.

  Preferably, a singular orientation of the fins makes it possible to generate an air flow around the flywheel and thus promotes the dissipation of heat by convection around the fins. Thus a radial arrangement of the fins rising perpendicularly to the second face of the flywheel creates a flow of air around the second face of the flywheel. This air flow can be controlled by introducing an acute angle between the fins and the second face of the flywheel.

  In the embodiment of the invention shown, the convective heat dissipation is optimized by using fins 30 which follow helical portions.

  Finally, in one embodiment where the fins 30 extend from the hub 12 to the rim 43 of the flywheel 10, these fins 30 act as rib between the hub 12 and the rim 43. The starter ring 80 resting on the rim 43 and the target PMH 40 materialize the outer diameter of the flywheel 10.

  However, under the effect of the centrifugal force during the driving rotation of the flywheel 10, the diameter of the flywheel 10 expands radially. It follows that the starter ring 80 and the PMH target 40 move away from the shaft line comprising the crankshaft 24 and the input shaft of the gearbox 56. The starter ring 80 is then incorrectly positioned relative to the starter. In addition, the teeth of the PMH target 40 are no longer aligned relative to the PMH sensor.

  The fins 30 then play their role of ribs by preventing the expansion of the outer diameter of the flywheel 10 under the effect of centrifugal force.

  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.

Claims (1)

9 CLAIMS   1. Torque transmission system of an internal combustion engine comprising a flywheel (10) and a clutch disc (59), the flywheel (10) comprising a first face (13) vis-à-vis of the clutch disc (59) and a second face (16), opposite the first face (13), facing towards the engine, characterized in that the second face (16) of the flywheel (10) comprises fins (30).   2. torque transmission system according to claim 1, characterized in that the fins (30) cover, uniformly, the entire surface of the second face (16) of the flywheel (10).   3. torque transmission system according to claim 1, characterized in that the flywheel (10) comprising a rim (43), the fins (30) have ridges (31) which all extend in a plane defined by the lateral contour of the rim (43) facing the engine.   4. Torque transmission system according to one of claims 1 to 3, characterized in that the fins (30) follow helical portions extending between the center and the edge of the flywheel (10).   5. Torque transmission system according to one of claims 1 to 3, characterized in that the fins (30) extend along radii of the flywheel (10).   6. Torque transmission system according to one of claims 1 to 3, characterized in that the fins (30) extend in concentric circles centered on the flywheel (10).   7. Transmission system according to one of claims 5 or 6, characterized in that the fins (30) rise perpendicularly to the second face (16) of the flywheel (10).   8. Torque transmission system according to one of claims 5 or 6, characterized in that the fins (30) form with the second face (16) an acute angle.   9. Transmission system according to one of claims 1 to 8, characterized in that the fins (30) and the flywheel (10) form a single piece obtained by casting.   Motor vehicle power unit comprising such a transmission system according to any one of the preceding claims.