FR3046822A1 - ASSEMBLING A CRANKSHAFT END PORTION WITH A GUIDE BEARING - Google Patents

Abstract

An end portion (18) of a crankshaft (19) is housed in an interior volume (12) of a motor housing (10). A bearing (53) for guiding rotation of the end portion (18) of the crankshaft (19), supported at least partially by a bearing seat (14) defining an opening (15) of the housing, comprises at least one track rotary guide (46) and a fixed guide track (50). A tip (22) passes through the opening (15). The tip (22) has a contact and attachment interface with the end portion (18) of the crankshaft (19) and a bearing surface (46, 147) facing radially outwardly, the rotating guide track (46). ) being formed by the radially outwardly facing bearing (46, 147) or an inner bearing ring (146) engaged on the radially outwardly facing bearing (46, 147).

Description

ASSEMBLY OF A CRANKSHAFT END PORTION WITH A BEARING BEARING

GUIDANCE

TECHNICAL FIELD OF THE INVENTION

The invention relates to the rotational guidance of an end portion of a crankshaft housed in a crankcase.

STATE OF THE PRIOR ART

According to the state of the art illustrated in Figure 1, a crankshaft 1019 of an internal combustion engine has an end portion 1018 guided in rotation about an axis of revolution 1000 relative to a motor housing 1010 thanks to a plain bearing 1053, this end 1018 comprising a flange 1054 projecting outside the crankcase 1010. The flange 1054 forms a positioning surface 1058 rotated radially outwardly and a shoulder on which threaded holes 1056 , and thus constitutes a fixing interface for a flywheel 1024, which is positioned on the positioning surface 1058 in direct support against the shoulder. The flywheel 1024 is provided with bores 1057 aligned with the threaded holes 1056, the attachment of the flywheel 1024 to the crankshaft 1019 being provided by fixing screws 1059 passing through the bores screwed into the threaded holes 1056. With a In this type of assembly, the plain bearing 1053 consists of a bearing 1153 in at least two parts, positioned on a journal 1046 of the crankshaft confined between the flange 1054 and the first crank of the crankshaft 1019.

The recent evolution of low-consumption internal combustion engines to engine speeds at low rotational speed and high engine torque, with intermittent operations in stop / start mode, inducing a significant tension on the drive belt of the engines. accessories and interruptions of the oil pump, strongly urges the plain bearings, especially at startup and during cold transient periods. It may thus be advantageous to replace some of the smooth bearings of the crankshaft, including the two-part bearing bearing at the end of the crankshaft carrying the flywheel, with rolling bearings, more efficient cold. One then comes up against a mounting problem, because of the confinement of the pin between the flange and the first crank of the crankshaft. This requires either a two-part inner race ring, a poorly performing solution, as suggested in document FR 2 906 167, ie a directly formed raceway on the crankshaft. This last solution is particularly expensive and does not optimize the choice of material constituting the raceway. Another solution would be to eliminate the flange, but with the disadvantage of considerably reducing the available area for fixing the flywheel to the crankshaft, thus reducing the number of fastening screws, but also to reduce the fastening diameter. screws therefore, for a given nominal torque, to increase the shear forces experienced by each screw.

The confinement of the trunnion 1046 between the flange 1054 and the first crank of the crankshaft 1019 also poses a problem if it is desired to increase the performance of the sliding bearing 1053 by replacing the bearing in two parts 1153 by a one-piece annular bearing.

To assemble a crank end portion and an flywheel located axially on either side of an opening formed in a crankcase, it has been proposed in French Patent Application No. 1556894, no still published on the day of filing of the present application, to use a guide bearing, preferably bearing, comprising a rotating inner race ring having bores, which are aligned with threaded holes of the crankshaft and with axial bores of the steering wheel. inertia. Screws are inserted into the bores of the flywheel and the guide ring and screwed into the threaded holes of the crankshaft to ensure consistency of the assembly. This solution, however, imposes a rotating inner ring of large outside diameter, and can lead to oversizing of the bearing with respect to the forces encountered, resulting in an additional cost and possibly a problem of size.

STATEMENT OF THE INVENTION

The invention aims to overcome the disadvantages of the state of the art and to propose a compact assembly for fixing between them a flywheel to the crankshaft of the engine, and which is compatible with a one-piece ring bearing.

To do this is proposed, according to the invention, an assembly comprising: - a motor housing defining an interior volume and having a bearing seat defining at least partially a passage opening between the internal volume and an external volume at motor housing; - An end portion of a crankshaft, housed in the interior of the engine housing, and defining an axis of revolution; a bearing for rotating the end portion of the crankshaft, at least partially supported by the bearing seat [14] and comprising at least one rotating guide track fixed in rotation relative to the end portion of the crankshaft and a fixed guide track, fixed in rotation relative to the motor housing; and a ferrule passing through the opening of the motor housing, the ferrule having a contact and attachment interface with the end portion of the crankshaft and a radially outwardly facing bearing, the rotating guide track being formed by the bearing turned radially outward or on a bearing inner ring on the radially outward facing bearing.

Because the tip is a separate part of the end portion of the crankshaft, it becomes possible to thread all or part of the guide bearing parts on the tip. Preferably, the guide bearing comprises an outer bearing ring in contact with the bearing seat and in which is formed the fixed guide track. The outer ring is preferably one-piece, the contact and fixing interface with the end portion of the crankshaft and the radially outwardly facing bearing having an outer casing located radially inside the outer ring, and if the bearing is a rolling bearing provided with a cage, inside said cage. It is thus possible, before mounting the tip at the end of the crankshaft, to thread the outer ring axially from the end of the tip including the contact interface to the level of the range turned radially outwardly. Advantageously, a seal is provided between the outer ring and the endpiece.

According to one embodiment, the nozzle comprises a fixing flange located outside the motor housing and provided with fixing holes of a flywheel extending outside the motor housing. This solution will be preferred especially when the endpiece is intended to integrate certain functions that require a steel with more noble characteristics than those required for the steering wheel, for example when the endpiece integrates one or more tracks of guide, rolling or sliding, for the guide bearing or for a pilot bearing for guiding one end of a gearbox primary shaft.

According to one embodiment, the assembly further comprises a flywheel extending outside the motor housing and secured to the endpiece. The flywheel may optionally be fixed to the fixing flange mentioned above. Alternatively, the tip is with the flywheel a single piece. This solution will be preferred when the end piece has no function requiring a noble steel, for example when the bearing has an inner ring shrunk on the radially outwardly facing bearing and, where appropriate, a pilot bearing attached to the tip.

According to one embodiment, the nozzle comprises an axial cavity open towards the outside of the motor housing, in which is housed a pilot bearing or smooth bearing to guide a gearbox primary shaft. As mentioned above, it can be envisaged that the pilot bearing comprises an outer ring hooped in the axial cavity open towards the outside, or alternatively that the pilot bearing comprises a guide track formed by a wall of the axial cavity open towards the outside. .

According to one embodiment, the assembly comprises at least one fixing screw of the end piece to the end portion of the crankshaft, the endpiece comprising an axial bore housing the fixing screw and a shoulder of support of a head of the fixing screw, the end portion of the crankshaft having an axial screw threaded hole of the fastening screw. Preferably, a single fastening screw is aligned on the axis of revolution.

Preferably, the tip and the end portion of the crankshaft comprise conjugate shapes engaged in each other to lock in rotation the nozzle relative to the end portion of the crankshaft. According to one embodiment, the conjugate shapes are oriented to allow radial engagement of the tip with the end portion of the crankshaft. Alternatively, and preferably, the conjugate shapes are oriented to allow axial engagement of the tip with the end portion of the crankshaft. These conjugate forms may include including splines of the nozzle, extending axially, fretted in corresponding grooves of the end portion of the crankshaft, or teeth of the tip extending radially, engaged in corresponding teeth of the end portion of the crankshaft.

To secure the connection between the tip and the end portion of the crankshaft, there may be a retention washer between the end portion of the crankshaft and the tip. The securing is then obtained by friction or by obstacle. It is also possible to provide a positive locking piece in rotation, preferably a pin inserted radially, solidarisant the tip to the end portion of the crankshaft at least in rotation about the axis of revolution.

Such means may in particular be implemented in the event that the tip has a thread engaged with a conjugate thread of the end portion of the crankshaft.

It can advantageously provide an axial overlap between the tip and the end portion of the crankshaft, at the contact interface and fixing. This can be achieved in particular by providing that the endpiece comprises an axial cavity open towards the end portion of the crankshaft and in which is housed an axial end of the end portion of the crankshaft, and / or that the end portion the crankshaft comprises an axial cavity open towards the endpiece and in which is housed an axial end of the endpiece.

According to one embodiment, a seal is arranged between the motor housing and the tip, outside the motor housing.

The assembly is particularly suitable for the situation in which the guide bearing is a rolling bearing, preferably a roller bearing, preferably a cylindrical roller bearing.

In various embodiments, it is advantageously provided that the tip has a collar located between the rotating guide track and the end portion of the crankshaft, and projecting radially relative to the rotating guide track. Such a collar may constitute a cylindrical roller guide collar in the event that the radially outwardly facing bearing surface of the nozzle constitutes a rolling track for such rollers. Assuming that the radially outward bearing surface of the end piece constitutes a hooping bearing surface of a rolling or plain bearing ring, such a collar can be formed by deformation of material after having fitted the ring on the frettage range, to axially ensure the connection between the tip and the ring.

BRIEF DESCRIPTION OF THE FIGURES

Other features and advantages of the invention will become apparent on reading the description which follows, with reference to the appended figures, which illustrate: FIG. 1, a sectional view of an assembly according to the state of the technical; Figure 2 is a sectional view of an assembly according to a first embodiment of the invention; Figure 3, a half-sectional view of an assembly according to a second embodiment of the invention; Figure 4 is a half-sectional view of an assembly according to a third embodiment of the invention; Figure 5 is a half-sectional view of an assembly according to a fourth embodiment of the invention; Figure 6, a half-sectional view of an assembly according to a fifth embodiment of the invention; Figure 7, a half-sectional view of an assembly according to a sixth embodiment of the invention; Figure 8 is a half-sectional view of an assembly according to a seventh embodiment of the invention; Figure 9, a half-sectional view of an assembly according to an eighth embodiment of the invention; Figure 10 is a sectional view of an assembly according to a ninth embodiment of the invention; Figure 11 is a half-sectional view of an assembly according to a tenth embodiment of the invention; Figure 12, a half-sectional view of an assembly according to an eleventh embodiment of the invention; - Figure 13, an exploded isometric view of the assembly according to a twelfth embodiment of the invention; - Figure 14, a half-sectional view of an assembly according to a thirteenth embodiment of the invention; Figure 15, a half-sectional view of an assembly according to a fourteenth embodiment of the invention.

For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

DETAILED DESCRIPTION OF EMBODIMENTS

In Figure 2 is illustrated a portion of a motor housing 10 defining an interior volume 12 closed by an oil sump 13, and having a bearing seat 14 located in an opening 15 passage between the interior volume 12 and the outside 16 of the housing 10. An end portion 18 of a crankshaft 19 is housed in the inner volume 12 of the motor housing 10 and defines an axis of revolution 100. A one-piece nozzle 22 passes through the opening 15 of the housing 10 and forms a connecting piece between the end portion of the crankshaft 18 and a flywheel 24, which may be a simple flywheel or a primary flywheel of a double damping flywheel.

The end portion 18 of the crankshaft has a cylindrical bearing surface 26 rotated radially outwards, a bearing wall 28 turned axially towards the nozzle 22, and a threaded hole 30.

The tip 22 comprises a recess 32 for housing the end portion 18 of the crankshaft, having a cylindrical bearing surface 34 rotated radially inwardly and a bottom wall 36 forming a shoulder facing the wall. 28. The bottom wall 36 is traversed by an axial bore 38 and separates the recess 32 from a cavity 40 with two shoulders open opposite the crankshaft 19, for housing a head 42 of a fixing screw 44 screwed into the threaded holes 30 of the end portion of the crankshaft. The end portion 18 of the crankshaft is shrunk in the recess 32 and bears axially against the shoulder of the bottom wall 36, the mechanical connection being secured by the screw.

Furthermore, the tip 22 has a radially outwardly facing bearing, forming an inner guide track 46 for rolling bodies 48, here cylindrical rollers, arranged between the inner guide track 46 and a track of external guide 50 formed on an outer ring 52 integral with the motor housing 10, in contact with the bearing seat 14, housed at least partially in the opening 15 of the motor housing 10. A collar 47 located axially between the inner guide track 46 and the crankshaft 19 protrudes radially outwardly relative to the inner guide track 46. The tip 22 thus constitutes an inner ring of a rolling bearing 53 for rotating the end portion 18 of the crankshaft 19 through the opening 15 of the crankcase 10. The outer race 52 is integral and has an inside diameter larger than the outside diameter of the portion of the spigot extending xialement from the guide track 46 inward 12 of the motor housing 10. A flange 55 attached to the motor housing 10, delimiting therewith the opening 15 and ensures the fixing of the outer ring 52.

The tip 22 comprises a fixing flange 54 located outside 16 of the motor housing 10 and provided with threaded fixing holes 56 of the flywheel 24. The tip 22 further comprises a centering skirt 58 which is slightly protruding axially relative to the fixing flange 54 to facilitate the mounting of the flywheel 24, which is fixed to the flange 54 by screws [not shown] screwed into the threaded mounting holes 56. The tip 22 thus constitutes a hub for the flywheel 24. A seal 60 is fixed to the crankcase 10 and bears elastically against a cylindrical seat 62 formed at the periphery of the flange 54 to ensure a seal between the inside 12 and the outside 16 of the motor housing 10.

In the illustrated embodiment, the cavity 40 with two shoulders also serves as a housing for a pilot bearing bearing 64 for guiding an end of a gearbox input shaft [not shown]. The pilot bearing 64 comprises an outer raceway 66 directly formed in cavity 40, an inner raceway 68 formed on an inner ring 70 to be shrunk on the input shaft of the gearbox and the rolling bodies 72 between them. tracks 66, 68.

Alternatively, the bearing surfaces 26, 34 may have a shape which, in cross section, is non-circular. They may in particular be provided with complementary grooves, which extend axially and protrude radially or, more generally, have conjugate shapes engaged one inside the other to lock the endpiece 22 in rotation relative to the end portion 18 of the crankshaft. . If necessary, the manufacturing method can provide that before assembly, grooves are formed on one of the two bearing surfaces 26, 34, and that the grooves on the other bearing are machined by the splines already formed when the portion of 18 end of the crankshaft is inserted into the recess 32.

The assembly illustrated in Figure 3 differs from the assembly of Figure 2 essentially by the location of the seal 60, which is fixed to the outer ring 52 and in sliding contact against a seat 162 formed on the tip 22.

The assembly illustrated in Figure 4 differs from that of Figure 2 in that the inner guide track 46 of the guide bearing 53 is formed on an inner ring 146 fretted on an outer cylindrical surface 147 of the 22. Furthermore, the outer race 66 of the pilot bearing is formed on an outer race ring 166, hooped in the cavity 40 of the nozzle.

The assembly illustrated in Figure 5 differs from the assembly of Figure 2 by the structure of the pilot bearing 64, which is a sliding bearing having a sliding ring 164 shrunk inside the cavity 40.

The assembly illustrated in Figure 6 differs from the assembly of Figure 2 in that the endpiece 22 comprises an outer hooping surface 134, fretted within a scope 126 provided for this purpose in the end portion 18 of the crankshaft. This hooping comes instead of the hooping between the bearing 26 and the recess 34 of the embodiment of FIG. 2. The increase of the hooping diameter with respect to the embodiment of FIG. 2 allows the transmission of a torque superior.

The bearings 134, 126 may be cylindrical with a circular base or not. They may in particular be splined or more generally have conjugate shapes engaged one inside the other to lock in rotation the endpiece 22 relative to the end portion 18 of the crankshaft.

The assembly illustrated in Figure 7 provides for it a facial contact between a ring gear 234 formed at the axial end of the nozzle 22 and a ring gear 226 formed on the end portion 18 of the crankshaft. . The toothed crowns 234, 226 comprise complementary notches in crenellations or in triangles, called Hirth notches, which are inserted and interlock axially in each other to ensure the transmission of the torque.

The assembly illustrated in Figure 8 differs from the assembly of Figure 2 by the absence of clamping screw 44 and bore 38, the fretted assembly being secured by a retaining washer 344 having tabs elastics 345 hooked into an annular recess 330 of the end portion 18 of the crankshaft.

The assembly illustrated in Figure 9 differs from the assembly of Figure 2 by the absence of clamping screws and bore, the fretted assembly being secured by complementary threads 430, 444 formed on the portion end 18 of the crankshaft and the end piece 22.

The variant illustrated in Figure 10 adds to the assembly of Figure 9 a pin (not shown) passing through a radial bore 480 of the end portion 18 of the crankshaft and the tip 22, to secure the screw connection. between the threads 430,444.

The assembly illustrated in Figure 11 differs from the assembly of Figure 2 by the absence of clamping screw and bore, the fretted assembly between the hooping surfaces 26, 34 being secured by a rod annular elastic 544 which is housed in two complementary grooves formed in the end portion of the crankshaft and on the tip.

In FIG. 12 is illustrated an assembly in which the connection between the end piece 22 and the end portion 18 of the crankshaft is made by welding, in particular by friction welding, between annular faces 526, 534 facing each other. two parts, these surfaces 626, 634 may especially be flat or frustoconical.

FIG. 13 is an assembly in which the end piece 22 has a non-cylindrical fixing portion 782 which is inserted radially into a complementary non-cylindrical housing 784 formed for this purpose in the end portion 18 of the crankshaft, the shape connection thus produced being secured by a screw similar to that of the assembly of FIG. 2.

In Figure 14 is illustrated an assembly which differs from that of Figure 2 in that the end piece 22 and the flywheel 24 are in one piece. This variant can naturally be declined for all embodiments.

In Figure 15 is illustrated an assembly which differs from that of Figure 6 by the protruding frustoconical shape of the support wall 28 formed by the end portion 18 of the crankshaft, and the complementary concave frustoconical shape of the bottom wall 36 of the nozzle 22. This configuration provides extra material to the end portion 18 of the crankshaft, which improves its resistance to fatigue.

Naturally, the examples shown in the figures and discussed above are given for illustrative and not limiting. It is explicitly provided that the various illustrated embodiments can be combined with one another to propose others. All the features as they are apparent to a person skilled in the art from the disclosure of the invention, even if in concrete terms they have only been described in relation to other specific characteristics, both individually and in any combinations may be combined with other characteristics or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims (24)

An assembly comprising: - an engine casing [10) delimiting an interior volume [12] and having a bearing seat (14) at least partially delimiting an opening (15) for passage between the interior volume (12) and a volume outside (16) to the motor housing (10); - An end portion (18) of a crankshaft (19), housed in the inner volume (12) of the motor housing (10), and defining an axis of revolution (100); and - a bearing (53) for rotating the end portion (18) of the crankshaft (19), at least partially supported by the bearing seat (14) and comprising at least one rotating guide track (46) fixed in rotation relative to the end portion (18) of the crankshaft (19) and a fixed guide track (50) fixed in rotation relative to the motor housing (10); characterized in that it further comprises a tip (22) passing through the opening (15) of the motor casing (10), the end piece (22) having a contact and fixing interface with the end portion ( 18) of the crankshaft (19) and a bearing surface (46, 147) rotated radially outwardly, the rotating guide track (46) being formed by the radially outwardly facing bearing (46, 147) or on a ring inner bearing (146) shrunk on the radially outward facing bearing (46, 147). 2. An assembly according to claim 1, characterized in that the guide bearing (53) comprises an outer bearing ring (52) in contact with the bearing seat (14) and in which the fixed guide track (50) is formed. . 3. Assembly according to claim 2, characterized in that the outer ring (52) is in one piece, and in that the interface contact and attachment with the end portion of the crankshaft and the bearing rotated radially outwardly (46, 147) have an outer shell located radially inside the outer ring (52). 4. Assembly according to any one of claims 2 to 3, characterized in that it comprises a seal (60) between the outer ring (52) and the tip (22). 5. Assembly according to any one of the preceding claims, characterized in that the tip (22) has a fixing flange (54) located outside (16) of the motor housing (10) and provided with holes of fixing (56) a flywheel (24) extending outside (16) of the motor housing (10). 6. Assembly according to any one of the preceding claims, characterized in that it further comprises a flywheel (24) extending to the outside (16) of the motor housing (10) and secured to the endpiece. (22). 7. An assembly according to claim 6, characterized in that the tip (22) constitutes with the flywheel (24) a single piece. 8. Assembly according to any one of the preceding claims, characterized in that the tip (22) comprises an axial cavity (40) open towards the outside (16) of the motor housing (10), in which is housed a pilot bearing (64) smooth or rolling to guide a gearbox primary shaft. 9. An assembly according to claim 8, characterized in that the pilot bearing (64) comprises an outer ring (168) hooped in the axial cavity (40) open towards the outside (16). 10. Assembly according to claim 8, characterized in that the pilot bearing (64) comprises a guide track (66) formed by a wall of the axial cavity (40) open towards the outside (16). 11. Assembly according to any one of the preceding claims, characterized in that it comprises at least one fixing screw (44) of the nozzle (22) to the end portion (18) of the crankshaft (19), the end piece (22) having an axial bore (38) for housing the fixing screw and a bearing shoulder for a head (42) of the fixing screw (44), the end portion (18). crankshaft (19) having a threaded axial hole (30) for screwing the fastening screw (44). 12. An assembly according to any one of the preceding claims, characterized in that the tip (22) and the end portion (18) of the crankshaft (19) comprise conjugate shapes engaged one inside the other to lock in rotation. the tip relative to the end portion of the crankshaft. 13. An assembly according to claim 12, characterized in that the conjugate shapes (782, 784) are oriented to allow a radial engagement of the tip with the end portion of the crankshaft. 14. An assembly according to claim 12, characterized in that the conjugate shapes (26, 34, 126, 134, 226, 234) are oriented to allow axial engagement of the tip with the end portion of the crankshaft. 15. An assembly according to any one of the preceding claims, characterized in that the tip (22) has axially extending grooves, hooped in corresponding grooves of the end portion (18) of the crankshaft (19). 16. Assembly according to any one of the preceding claims, characterized in that the tip (22) has radially extending toothing engaged in corresponding teeth of the end portion (18) of the crankshaft (19). 17. Assembly according to any one of the preceding claims, characterized in that it comprises a retaining washer (344) between the end portion (18) of the crankshaft (19) and the end piece (22). 18. Assembly according to any one of the preceding claims, characterized in that it comprises a locking piece positive rotation, preferably a pin inserted radially, solidarisant the tip (22) to the end portion (18). crankshaft (19) at least in rotation about the axis of revolution (100). 19. An assembly according to any one of the preceding claims, characterized in that the tip (22) has a thread (430) engaged with a conjugate thread (444) of the end portion (18) of the crankshaft (19). ). 20. Assembly according to any one of the preceding claims, characterized in that the tip (22) comprises an axial cavity (32) open towards the end portion (18) of the crankshaft (19) and in which is housed a axial end of the end portion (18) of the crankshaft (19). 21. Assembly according to any one of the preceding claims, characterized in that the end portion (18) of the crankshaft (19) comprises an axial cavity open towards the endpiece and in which is housed an axial end of the endpiece. (22). 22. Assembly according to any one of the preceding claims, characterized in that it comprises a seal (60) between the motor housing (10) and the end piece (22), outside (16). of the motor housing (10). 23. An assembly according to any one of the preceding claims, characterized in that the guide bearing (53) is a rolling bearing, preferably a roller bearing (48), preferably a cylindrical roller bearing (48). 24. Assembly according to any one of the preceding claims, characterized in that the tip (22) has a collar (47) located between the rotating guide track (46) and the end portion (18) of the crankshaft ( 19), and protruding radially from the rotating guide track (46).