Crankshaft with reduced oil shocks

Abstract

The present invention relates to a crankshaft (1) of a heat engine extending along a rotation axis (X) and comprising at least one journal (12) and two crank arms (16), each equipped with a counterweight (24) intended to be at least partially immersed in the heat engine oil. This counterweight (24) extends over an angular sector (α) between an entry edge (32) in the oil and an exit edge (34) of the oil. According to the invention, the counterweight (24) comprises at least one shape (40) configured to reduce impacts at the entry of the entry edge (32) into the oil. This shape (40) extends over at least one face (36, 38) of the counterweight (24) secant to the rotation axis (X) from the entry edge (32) and over an angle (β) greater than 20% of the angular sector (α).

Description

[0001] The present invention relates to the field of crankshafts for internal combustion engines, and more particularly to such crankshafts which are configured to reduce friction with an oil reservoir of the internal combustion engine.

[0002] Internal combustion engines in motor vehicles typically consist of a housing or casing containing the crankshaft. This crankshaft drives the connecting rods, pistons, or other components of the internal combustion engine. The crankshaft includes bearings and crankpins connected to the bearings by crank arms. These crank arms are usually fitted at one end with counterweights, which act as balancing masses to ensure the stability of the engine's moving parts.

[0003] A portion of the crankcase also serves as a storage reservoir for engine lubricating oil. During acceleration and braking, or when the vehicle is cornering, the volume of oil in this reservoir shifts. This causes certain crankshaft components, particularly the counterweights, to impact the oil in the crankcase.

[0004] Such an impact between the counterweights and the oil causes emulsification phenomena that can disrupt the internal pressure of the internal combustion engine and the settling of oil vapors, potentially diminishing the lubrication and cooling effects otherwise provided by the oil. Furthermore, these impacts generate hydrodynamic losses, which vary depending on the oil's viscosity.

[0005] Prior art exists solutions designed to reduce friction between the crankshaft and the oil in the storage tank. For example, it is known to coat certain parts with a material or coating that has friction-reducing properties.

[0006] However, these solutions do not allow for the absorption of shocks caused by the collision of counterweights with the oil.

[0007] WO 2021 / 201740 A1 discloses a crankshaft according to the preamble of claim 1. JP 2004 197897 A and JP 4 865774 B2 each disclose a crankshaft having a shape on only one face.

[0008] The present invention aims to overcome this drawback by proposing a crankshaft whose counterweights are configured to reduce these shocks with the oil contained in the storage tank.

[0009] The main object of the present invention is a crankshaft of a heat engine according to claim 1.

[0010] The crankshaft according to the invention thus reduces the shocks to its counterweight upon entering the engine oil, thanks to the counterweight's specific shape. This counterweight acts as a balancing mass, its purpose being to dynamically balance the crankshaft as it rotates around its axis of rotation. Indeed, the movement of the crankshaft's components during its rotation generates forces, which the counterweight reduces or even eliminates.

[0011] The crankshaft rotation axis and the crankpin axis are distinct axes from each other and parallel to each other.

[0012] The counterweight has a first end corresponding to the inlet edge and a second end corresponding to the outlet edge. The shape, configured to reduce shocks, gives the counterweight a hydrodynamic form. This shape is obtained, for example, by die forging. It extends from the inlet edge towards the outlet edge. It spans an angle greater than 20% of the angular sector, that is, at least 20% of the distance measured from the inlet edge to the outlet edge.

[0013] According to an unclaimed feature of the invention, the shape is a bevel that extends from the entry edge towards the exit edge.

[0014] It is understood here that the shape configured to reduce shocks has at least one sloping wall, which allows the entry edge to enter the shock-limiting oil. According to another unclaimed feature of the invention, the face on which the shape extends is located on one side of the crank arm that carries the crankpin.

[0015] According to an unclaimed feature of the invention, the face on which the shape extends is located on one side of the crank arm that carries the rotating bearing. This face extends predominantly perpendicularly to the axis of rotation of the crankshaft.

[0016] According to another feature of the invention, the face arranged on the side of the crank arm which carries the crankpin is a first face and the face arranged on the side of the crank arm which carries the rotation bearing is a second face, the counterweight comprising a first shape arranged on the first face and a second shape arranged on the second face.

[0017] The crank arm thus has two faces, one facing the crankpin and the other facing the rotating bearing. These two faces are therefore opposite each other and substantially parallel. The shock-absorbing shape can be located on either the first face, the second face, or both. In the embodiment where both the first and second faces have a shock-absorbing shape, there is a first shape on the first face and a second shape on the second face.

[0018] According to an unclaimed feature, the first face and the second face define a thickness of the counterweight, the bevel extending from the entry edge and towards the exit edge increasing its thickness.

[0019] This thickness can be measured parallel to the crankshaft's axis of rotation. The bevel corresponds to a reduction in this thickness from the inlet edge; thus, the counterweight thickness is less when measured near the inlet edge compared to a measurement near the outlet edge.

[0020] According to one feature of the invention, the first shape and the second shape delimit a cone whose apex corresponds to the entrance edge.

[0021] In other words, when both the first face and the second face have the shape configured to reduce shocks, a section of the bevel viewed from a plane from the entry edge to the exit edge is substantially triangular in shape, the apex of this triangle being the entry edge.

[0022] According to another feature of the invention, the shape extends from the entry edge over an angle between 20% and 50% of the angular sector.

[0023] It is understood here that the shape configured to reduce shocks constitutes at most half of an angular sector of the counterweight, measured from its entry edge to its exit edge.

[0024] According to one feature of the invention, the entry edge and the exit edge are joined by a rounded edge, the shape extending from this rounded edge in the direction of the axis of rotation.

[0025] The entry edge is therefore connected to the exit edge by this rounded edge. This edge extends substantially along the angular sector. The shape configured to reduce shocks thus extends here along the angular sector.

[0026] According to one characteristic, the rounded edge fits within a circle whose center is the axis of rotation of the crankshaft, the shape having a dimension measured along the radius of said circle from the rounded edge between 0 and 70% of the radius of said circle.

[0027] The invention further relates to a heat engine comprising a crankshaft as previously mentioned and a crankcase intended to contain an oil reservoir, the crankshaft being configured to be at least partially immersed in the oil reservoir.

[0028] The internal combustion engine according to the invention is, for example, an internal combustion engine of a motor vehicle. More precisely, it is the counterweight of the crankshaft that is immersed in oil, particularly when the motor vehicle accelerates, brakes, or when it is moving around a corner.

[0029] According to one feature of the invention, the crankshaft rotates in a direction of rotation, the inlet edge being the edge that first enters the oil reservoir in this direction of rotation.

[0030] Other features, details and advantages of the invention will become clearer upon reading the following description on the one hand, and the illustrative and non-limiting examples of embodiments given with reference to the accompanying drawings on the other hand, in which: [ Fig. 1 ] illustrates, schematically, a crankshaft according to the invention, in a cross-sectional view; [ Fig. 2 ] illustrates, schematically, a portion of the crankshaft of the figure 1 .

[0031] The features, variations, and different embodiments of the invention can be combined in various ways, provided they are not incompatible or mutually exclusive. In particular, variations of the invention may include only a selection of features, described hereafter in isolation from the other features described, if this selection of features is sufficient to confer a technical advantage and / or to differentiate the invention from prior art.

[0032] In the figures, elements common to several figures retain the same reference.

[0033] There figure 1 This schematically illustrates elements of a motor vehicle's internal combustion engine, including at least one crankcase 4 and a crankshaft 1 according to the invention, which extends along an axis of rotation X around which it rotates during operation, in a direction of rotation X1. The crankshaft 1 is located, at least partially, within an internal housing 2 of the engine's crankcase 4. This crankcase 4 constitutes an oil reservoir 6, which is used to lubricate the internal combustion engine.

[0034] The internal combustion engine comprises, opposite the oil reservoir 6, a cylinder block 8 within which at least one piston 10 moves. This piston 10 slides back and forth within a cylinder. The piston 10 is connected to a crankpin 12 of the crankshaft 1 via a connecting rod 14, this connecting rod 14 being connected to the piston 10 at one end and to the crankpin 12 at the other. The crankpin 12 extends around an axis Y distinct from the axis of rotation X of the crankshaft 1. The Y axis of the crankpin 12 and the axis of rotation X of the crankshaft 1 are parallel.

[0035] In addition to the crankpin 12, the crankshaft 1 has at least two crank arms 16, 18, including a first crank arm 16 and a second crank arm 18.

[0036] Only the first crank arm 16 is shown in the figure 1 , while the two crank arms 16, 18 are visible in figure 2 .

[0037] As seen on this figure 2 Each of the crank arms 16, 18 has a first end 20 and a second end 22, these ends 20, 22 being on either side of the axis of rotation X of the crankshaft 10. The crankpin 12 extends axially between the first end 20 of the first crank arm 16 and the second end 20 of the second crank arm 18. It is thus understood that the axis Y of the crankpin passes through both the first end 20 of the first crank arm 16 and the first end 20 of the second crank arm 18.

[0038] The second ends 22 of the crank arms 16, 18 are equipped with balancing masses or counterweights 24, which have the role of dynamically balancing the crankshaft 1 and / or the moving assembly of the internal combustion engine, when the latter is driven in rotation around the axis of rotation X. A counterweight 24 is disposed on the crank arm 16, 18 opposite the crankpin 12.

[0039] A crank arm 16, 18 is axially delimited by a first side 26 and a second side 28. The crankpin 12 is located between the first side 26 of the first crank arm 16 and the first side 26 of the second crank arm 18. A crankshaft bearing 30 projects from the second side 28 of one of the crank arms 16, 18. In other words, the first side 26 of the crank arms corresponds to a side that carries the crankpin 12, while their second side 28 is the one that carries the bearing 30.

[0040] As shown here, the crankshaft 1 can include several rotating bearings 30, each of these rotating bearings 1 being then separated from a crankpin 12 by a crank arm 16, 18. The rotating bearing 30 is centered on the axis of rotation X of the crankshaft 1. The crankshaft 1 also includes several crankpins 12, each eccentric with respect to the axis of rotation X of the rotating bearing 30. The first ends 20 and the second ends 22 of the crank arms 16, 18 are arranged substantially equidistant from the axis of rotation X of the crankshaft 1 according to the invention.

[0041] As can be seen in figure 1 The crankshaft 1 is configured to be immersed, at least partially, in the oil reservoir 6 contained in the crankcase 4. More specifically, the crankshaft 1 is immersed in the oil reservoir 6, particularly when the motor vehicle it powers accelerates, brakes, or turns. Within the crankshaft 1, it is specifically the counterweight 24 that is designed to come into contact with the oil.

[0042] The counterweight 24 will now be described in more detail in relation to the first crank arm 16, but it is understood that there is one counterweight 24 for this first crank arm 16 and another counterweight 24 for the second crank arm 18, each counterweight 24 being as described below.

[0043] The counterweight 24 is divided into a first portion 46 and a second portion 48 by a molding line J which corresponds substantially to its median plane, the axis of rotation X of the crankshaft 1 lying in this plane. One end of the first portion 46 of the counterweight 24, or first end, corresponds to an inlet edge 32 in the oil reservoir 6, while one end of the second portion 48 of this counterweight, or second end, corresponds to an outlet edge 34. The inlet edge 32 and the outlet edge 34 are therefore each located on one side of the molding line J. The inlet edge 32 in the oil reservoir 6 is the edge of the counterweight 24 that enters this oil reservoir 6 first when the crankshaft rotates around the axis of rotation X, in its direction of rotation X1.

[0044] The counterweight 24 extends over an angular sector α, this angular sector α being defined by a circle C whose center corresponds to the axis of rotation X. This angular sector α is delimited by the entrance edge 32 on one side and by the exit edge 34 on the other.

[0045] The inlet edge 32 is connected to the outlet edge 34 by a rounded edge 35 which follows the portion of the circle C that forms the angular sector α. This rounded edge 35 extends between the inlet edge 32 and the outlet edge 34 along the angular sector α. It is understood that the rounded edge 35 lies within the circle C whose center corresponds to the axis of rotation X of the crankshaft 1.

[0046] As seen on the figure 2 The counterweight 24 has a first face 36 and a second face 38 connecting the inlet edge 32 to the outlet edge 34. These first and second faces 36 and 38 are substantially parallel to each other. They intersect the axis of rotation X of the crankshaft 1, notably by lying in planes perpendicular, or substantially perpendicular, to this axis. The first face 36 is located on the counterweight 24 on the first side 26 of the first crank arm 16, and the second face 38 is located on the second side 28. It is thus understood that the first face 36 of the counterweight 24 is on the side of the crankpin 12, while its second face 38 is on the side of the rotating bearing 30. The first face 36 and the second face 38 are joined, at the second end 22 of the first crank arm 16, by the rounded edge 35.

[0047] According to the invention, the counterweight 24 comprises at least one shape 40 configured to reduce shocks at the entry of the inlet edge 32 into the oil reservoir 6, such a shape 40 resulting, for example, from a forging of the counterweight 4 of the crankshaft 1. This shock-reducing shape 40 extends from the inlet edge 32 towards the outlet edge 34. More precisely, and as can be seen in the figure 1 , the shape 40 configured to reduce shocks extends from the inlet edge 32 and over an angle β greater than 20% of the angular sector α; it is understood here that the shape 40 configured to reduce shocks extends over a distance measured from the inlet edge 32 along the angular sector α, such a distance corresponding to at least 20% of this angular sector α.

[0048] According to the embodiments, the shock-reducing shape 40 extends from the entry edge 32 over an angle β corresponding to between 20% and 50% of the angular sector α. It is understood here that this shock-reducing shape 40 extends at most over half of the counterweight 24, this half being measured between the entry edge 32 and the exit edge 34 along the rounded edge 35. In other words, the shock-reducing shape 40 then extends from the entry edge 32 to the demolding line J.

[0049] In addition, the shape 40 configured to reduce shocks can, according to different embodiments, be arranged either on the first face 36 of the counterweight 24, or on the second face 38 of the counterweight 24, or both on the first face 36 and the second face 38 of this counterweight 24.

[0050] In other words, the shape 40 configured to reduce shocks can be arranged either on the first side 26 of the first crank arm 16, i.e. the one which carries the crankpin 12, or on its second side 28, i.e. the one which carries the rotation bearing 30, or both on this first side 26 and this second side 28.

[0051] The shape 40 formed on the first side 26 of the first crank arm 16 extends in a plane secant to the plane in which the first face 36 of the counterweight 24 is inscribed, forming an angle between ZZ° and WW°.

[0052] The shape 40 formed on the second side 28 of the first crank arm 16 extends in a plane intersecting the plane in which the second face 38 of the counterweight 24 is inscribed, forming an angle included in a non-limiting way for example between 10° and 30°.

[0053] For embodiments in which the shock-reducing shape 40 is present on both the first face 36 and the second face 38, there is therefore a first shock-reducing shape 40A on the first face 36 and a second shock-reducing shape 40B on the second face 38 of the counterweight 24. First shape 40A and second shape 40B combine with each other to reduce shocks in contact with the oil.

[0054] The plane in which the first shape 40A is inscribed and the plane in which the second shape 40B is inscribed intersect at an angle of, for example, between 20 and 60°.

[0055] The first face 36 and the second face 38 of the counterweight 24 define a thickness E of this counterweight 24, this thickness E being measured along a direction parallel to the axis of rotation X of the crankshaft. The shape 40 configured to reduce shocks is, for example, a bevel. This bevel includes an oblique wall 42 extending from the inlet edge 32 towards the outlet edge 34. Thus, the shape 40 configured to reduce shocks is such that a thickness E of the counterweight 24 measured near the inlet edge 32 is less than a thickness E of this counterweight 24 measured near the outlet edge 34, or near the demolding line J.

[0056] When the counterweight 24 has both a first shape 40A and a second shape 40B configured to reduce shocks, these two shapes 40A, 40B delimit a cone whose apex 44 corresponds to a line of the inlet edge 32. It follows that a section of these shapes 40A, 40B configured to reduce shocks made along the rounded edge 35 of the counterweight 24 is in the shape of an isosceles triangle, a principal vertex of this isosceles triangle corresponding to the apex 44 of the cone.

[0057] The shape 40 configured to reduce the shocks of the counterweight 24 can further be likened to a third shape 40C which extends from the rounded edge 35 and in the direction of the axis of rotation X of the crankshaft 1.

[0058] Thus, and as particularly visible in figure 2The third shape 40C forms a flare that starts at the rounded edge 35 and opens towards the axis of rotation X of the crankshaft 1. The third shape 40C, configured to reduce shocks, has a smaller counterweight thickness E 24 when measured at the rounded edge 35 than when measured at another point closer to the axis of rotation X of the crankshaft 1. In other words, this third shape 40C, configured to reduce shocks, constitutes a reduction in the thickness E of the crankshaft in the vicinity of the rounded edge 35.

[0059] As mentioned previously, this rounded edge 35 is inscribed within the circle C whose center is the axis of rotation X of the crankshaft 1,whose radius depends on the dimensions of the engine itself, in particular the piston stroke. The third shape 40C configured to reduce shocks then has a dimension, measured along this radius and from the rounded edge 35, which is between 0 and 70% of this radius, from the center of the circle C.

[0060] The present invention thus proposes a crankshaft whose impact with the oil of a thermal engine is reduced due to the particular shape of its counterweight, which is configured to facilitate the entry of the counterweight into the oil reservoir, for example by cutting the oil film by means of the shape 40, 40A, 40B, 40C configured to reduce the impacts.

[0061] The present invention is not limited to the means and configurations described and illustrated herein, and also extends to any equivalent means and configuration as well as any technically operative combination of such means.

[0062] It includes in particular an improved embodiment, not shown in the figures, in which an additional shape is configured to limit the drag at the exit of the oil outlet edge, this shape extending over at least one face of the counterweight, secant to the axis of rotation of the crankshaft, from the outlet edge, and over an angle also greater than 20% of the angular sector over which the counterweight extends.

Claims

1. Crankshaft (1) of a heat engine extending along a rotation axis (X) and comprising at least one rotation bearing (30), at least one crank pin (12) and at least two crank arms (16, 18), the crank pin (12) extending around an axis (Y) distinct from the rotation axis (X), the crank arms (16, 18) each having a first end (20) and a second end (22), the crank pin (12) being arranged axially between the first ends (20) of the crank arms (16, 18), the second ends (22) of the crank arms (16, 18) being each equipped with a counterweight (24), at least one counterweight (24) being intended to be at least partially immersed in the oil of the heat engine, this counterweight (24) extending over an angular sector (α) between an inlet edge (32) in the oil and an outlet edge (34) of oil, the counterweight (24) comprising at least one shape (40) configured to reduce shocks at the inlet of the inlet edge (32) in the oil, said shape (40, 40A, 40B, 40C) extending on at least one face (36, 38) of the counterweight (24) secant to the rotation axis (X), from the inlet edge (32) and over an angle (β) greater than 20% of the angular sector (α), " crankshaft wherein the face (36, 38) arranged on the side (26) of the crank arm (16, 18) that carries the crank pin (12) is a first face (36) and the face (36, 38) arranged on the side of the crank arm (16, 18) that carries the rotation bearing (30) is a second face (38), the counterweight (24) comprising a first shape (40A) arranged on the first face (36) and a second shape (40B) arranged on the second face (38), characterised in that the first shape (40A) and the second shape (40B) delineate a cone, an apex (44) of which corresponds to the inlet edge (32).

2. Crankshaft (1) according to claim 1, wherein the shape (40, 40A, 40B, 40C) extends from the input edge (32) over an angle (β) comprised between 20% and 50% of the angular sector (α).

3. Crankshaft (1) according to any one of the preceding claims, wherein the input edge (32) and the output edge (34) are joined by a rounded edge (35), the shape (40) extending from this rounded edge (35) in the direction of the rotation axis (X).

4. Crankshaft (1) according to the preceding claim, wherein the rounded edge (35) fits into a circle (C) whose centre is the rotation axis (X) of the crankshaft (1), the shape (40, 40A, 40B, 40C) having a dimension measured along the radius of said circle from the rounded edge (35) of between 0 and 70% of the radius of said circle (C).

5. Heat engine comprising a crankshaft (1) according to any one of the preceding claims and a crankcase (4) for containing an oil reserve (6), the crankshaft (1) being configured to at least partially bathe in the oil reserve (6).

6. Heat engine according to the preceding claim, wherein the crankshaft (1) rotates in a rotation direction (X1), the inlet edge (32) being the edge that first enters the oil reserve (6) in this rotation direction (X1).

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