AUTOMOTIVE POWERTRAIN EQUIPPED WITH A REINFORCED RETAINING LINKAGE

Abstract

A motor vehicle powertrain comprising an elongated connecting rod (2) for retaining this unit (4), having at one end an elastic link (6) comprising a tube (20) passing through an elastic element (26), receiving a clamping screw (8) engaged in a bore (22) of the powertrain (4) disposed along an axis (A) perpendicular to the connecting rod (2), the bore of the unit (22) having a conical inlet recess (36), and the tube (20) having a conical front end (30) which is complementary to the conical inlet recess (36) of the bore (22) of the powertrain (4). Figure 3

Description

Title of the invention: AUTOMOBILE POWERTRAIN EQUIPPED WITH A REINFORCED RETAINING LINK

[0001] The present invention relates to a motor vehicle powertrain equipped with a retaining link for this powertrain comprising a reinforced fixing, as well as a method for assembling this powertrain and a motor vehicle comprising such a powertrain.

[0002] A known type of connecting rod for linking the powertrain to the body, presented in particular by document WO-A1-2018198413, includes a torque-recovery rod arranged in a plane perpendicular to the axis of the engine, fixed on one side to the powertrain and on the other to the body in order to oppose the torque coming in reaction to that which it applies on the drive wheels of the vehicle.

[0003] The connecting rod has on one side an elastic connection with the body which is complex, comprising a large elastic element performing the filtering of a wide range of frequencies.

[0004] On the other side, the connection with the powertrain comprises an annular elastic element including a central tube that receives a screw threaded into a hole in the housing of this powertrain. The screw, bearing against one end of the tube and clamping its other end, which is flat against a flat face of the housing, forms the intermediary between this housing and the connecting rod, absorbing all the stresses transmitted by this connecting rod, particularly in the plane perpendicular to its axis, with work in shear.

[0005] The tube's support on the flat face of the housing transmits forces in the directions of this plane, provided that a high tightening force is maintained by the screw, which must be maintained throughout its service life. This type of assembly, comprising few components, subjects the screw to high stresses and requires a high axial tightening force, which must be maintained to limit shear forces on the screw that could cause problems with its strength.

[0006] Alternatively, it is known to add a tab above the elastic linkage, through which the screw passes to tighten it onto the top of the tube. After bends, this tab is tightened onto a powertrain housing by a second screw to create a clevis-type mounting for the end of the connecting rod. This reduces the stress on the main clamping screw, but adds extra components that increase complexity, assembly labor time, and purchasing and management costs.

[0007] The present invention is specifically designed to avoid these problems of the prior art.

[0008] For this purpose, it proposes a motor vehicle powertrain comprising an elongated connecting rod for retaining this group, having at one end an elastic link comprising a tube passing through an elastic element, receiving a clamping screw engaged in a bore of the powertrain arranged along an axis perpendicular to the connecting rod, this powertrain being remarkable in that its bore has a conical inlet recess, and in that the tube has a front end of conical shape which is complementary to the conical inlet recess of the bore of the powertrain.

[0009] An advantage of this powertrain is that thanks to the complementary conical shapes, the end of the tube is locked in the bore of the housing, held by the axial tightening of the screw which can be moderate, giving a robust connection between the tube and the element of the group receiving it, which can withstand high forces in all directions, in particular in the plane perpendicular to the axis.

[0010] The screw, requiring moderate axial tightening to lock the complementary conical shapes together, does not experience the forces in the plane perpendicular to the axis that are transmitted by these conical shapes without passing through the screw. The screw is subjected to limited stresses in all directions, resulting in a robust assembly.

[0011] Moreover, with only one screw and without additional force-bearing parts, a minimum number of components and reduced assembly time are obtained, which gives this connection a cost that remains limited.

[0012] The vehicle according to the invention may further comprise one or more of the following characteristics, which may be combined with each other.

[0013] Advantageously, the tube comprises, after the conical front end, a cylindrical rear part receiving the elastic element.

[0014] In this case, advantageously an intermediate axial clearance is arranged between the conical front end and the elastic element.

[0015] Advantageously, the largest diameter of the conical front end is less than or equal to that of a ring surrounding the elastic element.

[0016] Advantageously, the half-angle of opening of the conical front shape is between 20 and 40 degrees.

[0017] According to one embodiment, the clamping screw is engaged in a thread formed directly in the drilling of the powertrain.

[0018] The invention also relates to a method of assembling a powertrain comprising any one of the preceding characteristics, remarkable in that it includes a step of preparing a sub-assembly comprising the tube and the elastic element assembled on the connecting rod, then a step of introducing the conical front end into the conical inlet hollow of the powertrain bore, and finally a step of tightening the clamping screw.

[0019] The invention further relates to a motor vehicle equipped with a powertrain comprising any one of the preceding characteristics, remarkable in that the connecting rod arranged in a transverse plane of the engine axis constitutes a torque-recovery connecting rod which is applied to this powertrain.

[0020] The invention will be better understood and other features and advantages will become more apparent upon reading the following description given by way of example, with reference to the accompanying drawings in which:

[0021] [Fig-1] is a side view of a connecting rod of a powertrain according to the invention;

[0022] [Fig.2] is a view of the elastic bond alone of this group; and

[0023] [Fig.3] is an axial cross-sectional view of the assembly with this connection.

[0024] The [Fig. 1] presents an elongated torque-recovery link 2, having at one end an elastic link 6 through which passes a clamping screw 8 arranged along an axis A perpendicular to the length of the link, which is screwed towards a front direction AV in the surface plane 10 of a housing 4 of a powertrain.

[0025] The connecting rod 2, arranged in a plane perpendicular to the axis of rotation of the engine, has at its other end 12 a connection with the body of the vehicle to oppose the reaction torque applied by the drive wheels on the powertrain.

[0026] Figures 2 and 3 show the elastic link 6 comprising a central tube 20 receiving the clamping screw 8, which is engaged in a threaded hole 22 in the housing 4.

[0027] The rear part 24 of the central tube 20 has a cylindrical shape receiving an annular elastic element 26, then an outer ring 28 covering the thickness of the connecting rod 2, which is fitted into a bore of this connecting rod to form an elastic connection.

[0028] The front end of the central tube 30 has a conical shape narrowing towards the front, having a flat transverse front face 32 and a cylindrical rear chamfer 34. The threaded hole 22 of the housing 4 has at its entrance a conical hollow 36 complementary to the conical shape of the front end 30, which receives this shape in a tight fit with axial tightening by the screw 8.

[0029] Alternatively, a nut can be placed in front of the hole in the housing 4 which is smooth to tighten the screw 8, in particular in the case where the remaining thickness of this housing after the conical entry hollow 36 is insufficient to form the thread receiving the screw.

[0030] The elastic link 6 has an intermediate axial clearance 38 between the conical front end 30 and the elastic element 26, so as to allow small displacements of this elastic element.

[0031] Advantageously the largest diameter of the conical front end 30 is less than or equal to that of the outer ring 28, which allows, when assembling the elastic link 6 in the connecting rod 2, for this conical front end to be introduced first into the bore of the connecting rod receiving the outer ring.

[0032] After tightening the screw 8 bearing on the rear transverse face of the central tube 20, an anchoring of the conical front end 30 of this tube is obtained in the conical inlet hollow 36 of the housing 4, having precise guidance and robust retention in all three directions.

[0033] In particular, by taking a fairly narrow opening angle of the cone, with a half-angle between 20 and 40 degrees, we obtain a locking of this cone and a resistant anchoring of the tube 20 in the housing 4.

[0034] The connecting rod 2 transmits forces along its longitudinal axis, the central tube 20 is subjected to shear forces applied along this axis, and to tilting around its anchorage in the housing 4 formed by the adjustment of the complementary cones locked by the axial tightening of the screw 8.

[0035] Since the screw 8 only provides axial clamping of the conical shapes together, it is no longer subjected to shear stress or tilting torque. Moderate tightening of the screw 8, which is easy to maintain over time, ensures the robustness of the connection. This avoids high tightening torques that would require specialized materials, particularly for the screw, resulting in higher costs.

[0036] Advantageously the connecting rod 2 is supplied directly equipped with the complete elastic link 6, including the conical front end 30 protruding on the side, to form a sub-assembly which is then fixed on the powertrain in a simple and quick manner during its preparation prior to assembly on the vehicle.

[0037] In addition, the conical front end 30 provides a guide facilitating the insertion of the central tube 20 into the conical hollow 36 of the entry into the threaded hole 22 of the housing 4, before the insertion and tightening of a single screw 8.

[0038] The number of components of the linkage of the connecting rod 2 with the powertrain is reduced and the assembly time is fast, which optimizes the costs of this assembly.

[0039] Generally, the connecting rod 2 can be fixed directly onto a housing 4 of the powertrain, in particular an engine housing which can be an internal combustion engine or an electric traction machine, or onto another element such as a support for this powertrain.

Claims

Demands

1. Motor vehicle powertrain comprising an elongated connecting rod (2) for retaining this powertrain (4), having at one end an elastic link (6) comprising a tube (20) passing through an elastic element (26), receiving a clamping screw (8) engaged in a bore (22) of the powertrain (4) disposed along an axis (A) perpendicular to the connecting rod (2), characterized in that the bore of the powertrain (22) has a conical inlet recess (36), and in that the tube (20) has a front end of conical shape (30) which is complementary to the conical inlet recess (36) of the bore (22) of the powertrain (4).

2. Powertrain according to claim 1, characterized in that the tube (20) has after the conical front end (30) a cylindrical rear part (24) receiving the elastic element (26).

3. Powertrain according to claim 2, characterized in that an intermediate axial clearance (38) is disposed between the conical front end (30) and the elastic element (26).

4. Powertrain according to any one of the preceding claims, characterized in that the largest diameter of the conical front end (30) is less than or equal to that of a ring (28) surrounding the elastic element (26).

5. Powertrain according to any one of the preceding claims, characterized in that the half-angle of opening of the conical front shape is between 20 and 40 degrees.

6. Powertrain according to any one of the preceding claims, characterized in that the clamping screw (8) is engaged in a thread formed directly in the bore (22) of the powertrain (4).

7. Method of assembling a powertrain according to any one of the preceding claims, characterized in that it comprises a step of preparing a subassembly comprising the tube (20) and the elastic element (26) assembled on the connecting rod (2), then a step of introducing the conical front end (30) into the conical inlet hollow (36) of the bore (22) of the powertrain (4), and finally a step of tightening the clamping screw (8).

8. Motor vehicle equipped with a powertrain according to any one of claims 1 to 6, characterized in that the connecting rod (2) disposed in a transverse plane of the engine axis, constitutes a torque-recovery connecting rod which applies to this powertrain (4).

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