FR3078749A1 - CRANKSHAFT BEARING CUSHION AND ASSOCIATED LUBRICATION SYSTEM - Google Patents

Abstract

The invention provides a crank bearing bearing having a semi-cylindrical ring (30) whose concave wall (34) has a first circular groove section (42-1) extending from a first end (38-1). ) of the semi-cylindrical ring, only along a portion of the concave wall (34), and a first associated radial bore (46-1), and a second section (42-2) of circular groove which s' extends from a second end (38-2) of the semi-cylindrical ring, only along an angular portion of the concave wall (34), which does not communicate with the first section (42-1), and a second associated radial drilling (46-2) which communicates with this second section (42-2).

Description

Crankshaft bearing bearing and associated lubrication system

TECHNICAL FIELD OF THE INVENTION

The invention relates to a crankshaft bearing bearing, in particular belonging to a lubrication system of a crankshaft of a combustion engine.

TECHNICAL BACKGROUND OF THE INVENTION

Internal combustion engines, in particular internal combustion engines, generally comprise an upper cylinder head and a cylinder block, also called cylinder block, comprising at least one cylinder in which a piston slides in a reciprocating movement.

The piston is connected by a connecting rod to a crankshaft at the level of a crankpin.

The crankshaft comprises at least one journal and at least one crankpin whose axes are parallel to the longitudinal axis of the crankshaft.

The crankshaft is mounted rotating in a connecting rod chamber into which the cylinder opens. The axis of the crankshaft is held in position in the connecting rod chamber by fixed bearings and bearing caps, each bearing and its associated bearing cap surrounding and guiding in rotation an associated journal of the crankshaft.

As the crankshaft rotates at high speeds (from 800 revolutions / min to 5000 revolutions / min), the contact zones between a crankshaft journal and a bearing-bearing cap assembly must be lubricated accordingly in order to reduce friction which can lead to overheating. different organs and overconsumption of fuel.

Lubricating fluid, here lubricating oil is therefore brought to these contact zones, here from a main oil manifold arranged in the cylinder block, by a conduit which is pierced in the body of the crankshaft the bearing and which opens into the convex cylindrical wall of the bearing opposite the crankshaft journal.

An intermediate conduit is also drilled in the body of the crankshaft to connect the wall of the journal in contact with the bearing, and the wall of an adjacent crank pin on which a connecting rod head is mounted for rotation.

The oil brought to the bearing wall in contact with the journal lubricates the contact areas between the journal and the bearing.

Part of the oil is then directed from the wall of the journal to the wall of the crankpin in order to lubricate the contact area of the crankpin with the connecting rod head.

A bearing is interposed radially between on the one hand the pin and, on the other hand, the bearing-associated bearing cap assembly.

Each bearing consists of two complementary semi-cylindrical hollow rings, upper and lower, to surround the convex cylindrical wall of the journal.

Each ring is also commonly called a pad itself.

The upper bearing is placed against the bearing, and the additional lower bearing is arranged against the bearing cap. The upper bearing has an external cylindrical wall in contact with the wall of the bearing and an internal cylindrical wall in contact with the wall of the journal, and at least one bore or radial hole which is connected to the oil supply duct.

In known manner, in its internal cylindrical wall, the upper bearing comprises a circular groove into which the radial bore opens, this groove being intended to direct the circulation of oil over a surface portion of the journal.

According to this known design which is for example illustrated in document FR-2,979,666, the groove extends angularly over the entire length separating the two end edges of the upper pad.

This design has the drawback in particular of reducing the hydrodynamic lift, a phenomenon which is particularly important in the case of high loads oriented towards said bearing comprising a reduction in its useful width as illustrated in the document FR.2.979.666, which is in particular the case under the effect of the inertial forces linked in particular to the alternative masses of the pistons.

The invention aims in particular to remedy this drawback.

BRIEF SUMMARY OF THE INVENTION

The invention provides a crankshaft bearing bearing comprising a first and a second complementary hollow semi-cylindrical ring, at least the first of which comprises, in its concave wall:

- at least one circular groove section which extends from one end of the semi-cylindrical ring and only along an angular portion of the concave wall; and

- at least one associated radial bore which communicates with the circular groove.

According to other characteristics of the bearing:

the concave wall has a first section of circular groove which extends angularly from a first end of the semi-cylindrical ring, only along an angular portion of the concave wall, and a first associated radial bore which communicates with this first section; and a second section of circular groove which extends angularly from a second end of the semi-cylindrical ring, only along an angular portion of the concave wall, which does not communicate with the first section, and a second radial bore partner who communicates with this second section;

each angular groove section extends angularly between one end of the semi-cylindrical ring and the associated bore;

- The first semi-cylindrical ring has a symmetry of design with respect to a median axial plane.

The invention also provides a lubrication system for a motor vehicle engine crankshaft which comprises:

- a crankshaft comprising at least one rotary guide pin;

- a bearing which is interposed radially between the journal and a fixed bearing of the motor comprising an oil inlet duct, characterized in that the bearing is produced according to the invention.

The invention finally provides a heat engine of a motor vehicle characterized in that it is equipped with a lubrication system according to the invention.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the invention will appear during the reading of the detailed description which will follow for the understanding of which reference will be made to the appended drawings in which:

- Figure 1 is a view which schematically shows in axial longitudinal section of a crankshaft and its lubrication system; and

FIG. 2 is a large-scale perspective view of the upper semi-cylindrical ring of a bearing according to the invention capable of fitting to the line bearings of the crankshaft of FIG. 1.

DETAILED DESCRIPTION OF THE FIGURES

In the following description, elements having an identical structure or analogous functions will be designated by the same references.

In the following description, we will adopt non-limiting longitudinal or axial orientations with reference to the axis of the bearing, and radial with reference to the axial orientation of the bearing.

There is shown schematically in Figure 1 a crankshaft 10 of an internal combustion engine of a four-cylinder motor vehicle.

The crankshaft 10 comprises at least one cylindrical journal 12 which is surrounded by a bearing 14 and a bearing cap 16, and comprises at least one crankpin 18 which is surrounded by a connecting rod head (not shown).

The crankshaft lubrication system comprises a main oil manifold 20 which is arranged in an unrepresented part of the engine and which is supplied by an oil pump 22.

The ramp 20 is connected to a pipe 24 for supplying oil which opens out through the bearing 14 in a concave cylindrical wall opposite the cylindrical journal 12.

An intermediate oil duct 28 is pierced in the body of the crankshaft and it extends between the peripheral wall, concave cylindrical, of the bearing 14 and a wall, convex cylindrical, of the crankpin 18 to bring the captured oil to the wall from pin 12 to pin 18 and lubricate the contact area between the pin and an associated connecting rod (not shown).

In a known manner, a bearing is interposed radially between the convex cylindrical peripheral wall of the pin 12 and the concave internal cylindrical wall formed for half in the "lower" bearing 14 and the "upper" bearing cap 16.

Each bearing for this purpose consists of a first part and a second part, each of which is in the form of a semi-cylindrical ring which is associated with the bearing cap 16 and the bearing 14 respectively.

Each of the two parts in the shape of a semicylindrical ring is commonly called upper bearing (line or crankshaft) and lower bearing (line or crankshaft).

The invention here relates at least to the design of the first semi-cylindrical ring constituting the upper bushing, a preferred embodiment of which is illustrated in FIG. 2.

The upper semi-cylindrical ring 30 illustrated in FIG. 2 is delimited by a convex cylindrical external wall 32 and by a concave cylindrical internal wall 34.

The ring 30 is delimited axially by two opposite lateral edges 36 and angularly by a first end edge 38-1 and by a second end edge 38-2.

These two end edges 38-1 and 38-2 are the connection edges forming a connection joint plane with the other lower semi-cylindrical ring not shown.

This connection or junction area is also known as the "skinning area".

According to the invention, the concave cylindrical inner wall 34 has a circular groove, here produced without limitation in two sections 42-1 and 42-2, which does not extend angularly over the entire length separating the first edge d end 38-1 of the second end edge 38-2.

In other words, there is an angular portion or section - here an intermediate central portion 44 - of the concave cylindrical inner wall 34 which has no groove.

The circular groove is of rectangular section and, without limitation, it is here rectilinear, extending in a radial plane centered with respect to the two opposite lateral edges 36.

The first section 42-1 of circular groove extends angularly from the first end edge 38-1 of the semi-cylindrical ring 30, to its opposite angular end which is defined by a first associated radial through hole 46- 1 which communicates with this first section 42-1 of circular groove.

Here symmetrically with respect to a median axial plane of symmetry of the semi-cylindrical ring 30, the groove comprises a second section 42-2 of circular groove which extends angularly from the second end edge 38-2 of the semi-cylindrical ring 30, to its opposite angular end which is defined by a second associated radial bore passing through 46-2 which communicates with this second section 42-2 of circular groove.

Thus, each section 42-1, 42-2 of the angular groove extends angularly between one end 38-1, 38-2 of the semi-cylindrical ring 30 and the associated bore 46-1, 46-2.

Each bore 46-1, 46-2 thus puts the associated groove section 42-1, 42-2 into communication with an external cylindrical wall 32 convex.

Thus, the loss of negative hydrodynamic lift due to the presence of the groove is reduced, compared to the prior art in which the groove extends angularly over the entire length separating the first end edge 38-1 from the second end edge 38-2.

This is particularly important in operating cases in which the main direction of the load at the line bearing is directed “upwards” in the direction of the upper bearing, which is in particular the case under the effect of inertial forces. related in particular to the alternative masses of the pistons.

This problem is advantageously solved while satisfying the requirements for supplying oil to the connecting rod crankpin (s) and for removing pollution such as particles present in the lubricating oil, this removal taking place in the so-called "zone". skinning >> mentioned previously.

The zone or intermediate central portion 44 without groove is advantageously the most stressed zone at high speeds of rotation of the crankshaft.

The preferred embodiment which has just been described having a general symmetry of design is advantageous in that it does not require any keying for the mounting of the upper bearing in one or the other of its two possible mounting positions.

According to variants not shown of the invention:

- the concave inner wall has only one section of circular groove which extends from one end of the semi-cylindrical ring and only along an angular portion of the concave wall;

- For each groove section, the radial bore is not necessarily arranged at one end of the section.

Claims (6)

1. Crankshaft bearing bearing (12) (10) comprising first and second complementary hollow semi-cylindrical rings, at least the first ring (30) of which, in its concave wall (34): - at least one section (42-1, 42-2) of circular groove which extends from one end (38-1, 38-2) of the semi-cylindrical ring (30) and only along an angular portion of the concave wall (34); and - at least one associated radial bore (46-1, 46-2) which communicates with the circular groove. 2. Pad according to claim 1, characterized in that the concave wall (34) comprises: a first section (42-1) of circular groove which extends angularly from a first end (38-1) of the semi-cylindrical ring (30), only along an angular portion of the concave wall, and a first associated radial bore (46-1) which communicates with this first section (42-1); and - A second section (42-2) of circular groove which extends angularly from a second end (38-2) of the semi-cylindrical ring (30), only along an angular portion of the concave wall (34 ), which does not communicate with the first section (42-1), and a second associated radial bore (46-2) which communicates with this second section (42-2). 3. A bearing according to any one of the preceding claims, characterized in that each section (42-1, 42-2) of angular groove extends angularly between one end (38-1, 38-2) of the semi ring -cylindrical (30) and the associated drilling (46-1, 46-2). 4. A bearing according to any one of the preceding claims, characterized in that said first semi-cylindrical ring has a symmetry of design with respect to a median axial plane. 5. Lubrication system of a crankshaft (10) of a motor vehicle engine which comprises: 5 - a crankshaft (10) comprising at least one rotary guide pin; - a bearing which is interposed radially between the journal and a fixed bearing (12) of the motor comprising an oil inlet duct, characterized in that the bearing is produced according to any one of the preceding claims. 6. Motor vehicle engine characterized in that it is equipped with a lubrication system according to claim 5.