FR3040745A1 - INTERNAL COMBUSTION ENGINE ASSEMBLY COMPRISING A PISTON AND A CLOSING PLATE OF A PISTON COOLING GALLERY - Google Patents

Abstract

The invention relates to an assembly for an internal combustion engine comprising: - a piston (10) comprising a cylindrical body (11) extending along a longitudinal axis (12) and comprising a lower part (14) in which an annular groove ( 16) is formed around the longitudinal axis, the groove (16) comprising a radially outer wall (17) provided with a first recess (20) and a radially inner wall (18) provided with a second recess (23). arranged opposite the first recess, the first recess comprising an upper wall (21) and a lower wall (22) and the second recess comprising an upper wall (24), a closure plate (50) in the form of a portion of ring, configured to seat in the first and second recesses (20, 23) and cover the groove (16) so as to form with the groove a cooling gallery of the piston, said plate comprising a radially outer edge (51) configured to train with the pa upper king (21) and the lower wall (22) of the first recess (20) of the upper and lower contact points (P1s, P1i) respectively, said plate further comprising a radially inner edge (52) configured to form with the wall upper (24) of the second recess (23) an upper contact point (P2s).

Description

GENERAL TECHNICAL FIELD The invention relates generally to the field of internal combustion engines, in particular for an aircraft. More specifically, the invention relates to an assembly for an internal combustion engine comprising a piston and a closure plate of a cooling gallery of the piston.

STATE OF THE ART

An internal combustion engine typically comprises a plurality of cylinders and pistons sliding in each of the cylinders. The pistons separate an upper chamber called combustion chamber and a lower chamber. The pistons each comprise a body provided with an upper part facing the combustion chamber and a lower part facing the lower chamber through which the piston is driven in translation in the associated cylinder. For this, a rod is connected by pivot connection to the lower part of the piston at a first end and a crankshaft pivoting about a shaft at a second end thereof.

However, when such a motor reaches a certain power level, it is necessary to be able to cool the pistons using an oil jet.

For this, it is known to produce in the body of the pistons an annular chamber extending around the axis of the piston so as to form a cooling gallery in which circulates the oil for cooling the piston. The annular chamber generally has an inlet port and an outlet for the circulation of the oil.

It is for example known to make the foundry cooling gallery at the same time as the raw piston. Such a solution is for example described in document US 2012/325166 which proposes using an annular soluble molding core comprising an inlet and an outlet, so as to form the cooling gallery. This inexpensive solution is however more suitable for aluminum pistons than steel pistons.

It is also known, especially when the pistons are made of steel, to make the cooling tunnel by mechanical deformation of the piston. Such a solution is for example described in documents US 2013/0133610, US 2004/168319, WO 2013/117575 and US 2006/000087. These documents propose making pistons provided with an annular flange extending radially from the upper part of the piston. This flange is subsequently mechanically deformed so as to fold the free end of the collar against the side wall of the piston body and form the cooling gallery.

The mechanical deformation of the piston may also be associated with the welding of the free end of the deformed portion to the side wall of the piston body, as proposed in particular in documents US 2006/000087 and US 2009/241769.

These solutions are however complex to implement.

Another known solution, particularly common when the pistons are steel, is to provide on their lower part an annular groove extending around the axis of the piston, intended to be opposite the lower chamber, and to close the throat via two spring plates in the form of a half-ring. Housings are provided in the radially outer and inner walls of the groove respectively to accommodate the radially outer and inner edges of the closure plates.

Such a solution is for example proposed in DE 42 08 037. In this document, the inner edge of the spring plates is in lower contact with a lower wall of the inner housing of the piston groove, while the outer edge of the plates. spring is in radial and upper contact with a radial wall and with an upper wall of the outer housing of the piston groove.

However, such a definition of the contacts between the spring plates and the recesses of the piston groove causes the deformation of the spring plates and housings due to the forces applied by the spring plates. Furthermore, the definition of the contacts between the spring plates and the outer housing of the piston groove causes wear of the spring plates and the outer housing due to the relative movements of the spring plates relative to the piston, during operation of the engine and thus the sliding of the piston.

To overcome these drawbacks, it has for example been proposed in US 2007/0209614 to give the spring plates a funnel shape. In this configuration, the radial contact between the outer edge of the spring plates and the outer housing of the piston groove is eliminated, and the respectively lower and upper contact points with the inner and outer edges of the spring plates apply a force of torsion to said spring plates, thus ensuring their holding in position on the piston.

However, the funnel shape of the spring plates proposed in this document complicates their design and production because it allows lower manufacturing tolerances and less dispersion of mounting force on the pistons.

PRESENTATION OF THE INVENTION

The present invention aims to overcome the disadvantages mentioned above.

More specifically, the subject of the present invention is an assembly for an internal combustion engine comprising: a piston for an internal combustion engine comprising a cylindrical body extending along a longitudinal axis and comprising an upper part and a lower part, the lower part comprising an annular groove formed around the longitudinal axis forming a cooling gallery of the piston, the groove comprising a radially outer wall provided with a first recess and a radially inner wall provided with a second recess arranged opposite the first recess, the first recess comprising an upper wall and a lower wall and the second recess comprising an upper wall, - at least one closing plate of the cooling tunnel in the form of a ring portion, said closure plate being configured to be housed in the first and second recesses of the piston and cover the groove so as to close the cooling tunnel of the piston, said plate comprising a radially outer edge configured to form with the upper wall and the lower wall of the first recess of the upper and lower contact points respectively, said plate further comprising a radially edge internal configured to form with the upper wall of the second recess an upper contact point.

Preferably, the upper wall of the first recess of the piston is shifted towards the lower part of the piston relative to the upper wall of the second recess of the piston. The offset between the upper wall of the first recess of the piston and the upper wall of the second recess of the piston is for example of the order of 0.1 to 1mm, preferably 0.2mm.

Preferably, the bottom wall of the first recess of the piston comprises one or a plurality of access housings to the first recess, and the radially outer edge of the closure plate comprises one or a plurality of protrusions extending radially from said edge and complementary shape with the access housing to the first recess of the piston.

More preferably, the plurality of piston access housings are arranged to form an alternation of housings and projections of complementary shape and of different dimensions, the plurality of projections of the closure plate being arranged so as to form an alternation protrusions and housing of complementary shape and substantially the same dimensions as the housing and corresponding projections of the piston.

Preferably, the radial dimensions of the closure plate are defined so as to ensure a minimum clearance between the radially outer edge of the closure plate and the radially outer wall of the piston groove, when the closure plate is mounted in the piston.

Preferably, the upper wall of the second recess of the piston and the radially inner edge of the closure plate are provided with rotational locking means about the longitudinal axis of the closure plate relative to the piston. The rotational locking means of the piston is for example a notch, and the locking means in rotation of the closure plate is for example a finger configured to be folded in the notch of the piston, when the closure plate is mounted in the piston.

Preferably, the closure plate comprises setting means configured to assist in sliding pivoting of the closure plate about the longitudinal axis, when the closure plate is mounted in the piston.

Preferably, the closure plate is flat.

Preferably, the closure plate is in the form of a half-ring.

The present invention also relates to an internal combustion engine comprising: a piston for an internal combustion engine comprising a cylindrical body extending along a longitudinal axis and comprising an upper part and a lower part, the lower part comprising an annular groove; arranged around the longitudinal axis forming a cooling gallery of the piston, when the closure plate is mounted in the piston, the groove comprising a radially outer wall provided with a first recess and a radially inner wall provided with a second recess arranged opposite the first recess, the first recess comprising an upper wall and a lower wall and the second recess comprising an upper wall, - at least one closing plate of the cooling tunnel in the form of a ring portion, the said recess plate; closure being accommodated in the first and second recesses of the piston and covering the groove so as to close the cooling gallery of the piston, said plate comprising a radially outer edge forming with the upper wall and the lower wall of the first recess the upper and lower contact points respectively, said plate further comprising an edge radially internal forming with the upper wall of the second recess an upper contact point.

PRESENTATION OF THE FIGURES Other features, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and which should be read with reference to the accompanying drawings, in which: FIGS. 1b are bottom views respectively of a piston and a closure plate according to one embodiment of the invention, - Figures 2a and 2b are partial sectional views of a piston and a a closure plate according to one embodiment of the invention, when the closure plate is mounted in the piston, - Figure 3 is a detailed view, in perspective, of the piston shown in Figure 1a, - Figure 4 is a bottom view of the piston of FIG. 1a and a closure plate as illustrated in FIG. 1b, at a first step of mounting the closure plate in the piston; FIG. 5 is a view of FIG. below the piston of Figure 1a in which two p Closing lacquers as illustrated in Figure 1b were mounted.

DETAILED DESCRIPTION

Figures 1a and 1b respectively show a piston 10 for an internal combustion engine (not shown) and a closure plate 50 according to one embodiment of the invention. FIGS. 2a and 2b show the piston 10 and the closing plate 50, when the closing plate 50 is mounted in the piston 10.

The piston 10 comprises a cylindrical body 11 extending along a longitudinal axis 12. The piston 10 is intended to slide in a cylinder (not shown) of the internal combustion engine along the longitudinal axis 12. The cylindrical body 11 of the piston 10 comprises an upper portion 13 and a lower portion 14. The upper portion 13 is intended to be facing an upper chamber (not shown) said combustion chamber of the internal combustion engine. The upper portion 13 comprises a recess extending in the longitudinal axis 12 and forming the bowl of the piston 10 (Figures 2a and 2b). The lower portion 14 is provided with connecting means at one end of a connecting rod (not shown) which is intended to drive the piston 10 in translation in the cylinder. For this, the opposite end of the connecting rod is connected to a crankshaft (not shown) pivoting about a shaft (not shown). In the example illustrated in Figure 1a, the connecting means comprise two coaxial orifices 15a, 15b disposed along an axis perpendicular to the longitudinal axis 12, for receiving an axis about which the end of the connecting rod is mounted.

The lower portion 14 of the piston 10 comprises an annular groove 16 formed around the longitudinal axis 12 comprising a radially outer wall 17, a radially inner wall 18 and a bottom 19. The annular groove 16 forms a cooling gallery of the piston 10.

The outer wall 17 of the groove 16 is provided with a first recess 20 comprising an upper wall 21 and a lower wall 22. The first recess 20 extends over the entire circumference of the groove 16.

The inner wall 18 of the groove 16 is provided with a second recess 23 comprising an upper wall 24. The second recess 23 is arranged facing the first recess 20. The second recess 23 extends over the entire circumference of the groove 16 The second recess 23 forms a shoulder.

The closure plate 50 has a ring-shaped portion. The closure plate 50 is configured to be housed in the first and second recesses 20, 23 and to cover the groove 16 so as to close the cooling gallery of the piston 10.

In the example illustrated in Figure 1b, the closure plate 50 has the shape of a half-ring. In this case, two closure plates 50 are mounted in the piston 10 to close the cooling gallery, as shown in FIG. 5. It will be understood that the closure plate 50 can also have the shape of a third, a quarter, etc. in this case, three, four, etc. plates are mounted in the piston 10 to close the cooling gallery. Advantageously, the closure plates 50 are identical.

The closure plate 50 comprises a radially outer edge 51 and a radially inner edge 52. The outer edge 51 is configured to form with the upper wall 21 and the lower wall 22 of the first recess 20 of the upper and lower contact points Pis, Pu respectively. The inner edge 52 is configured to form with the upper wall 24 of the second recess 53 an upper contact point P2s.

In this way, the centering of the closure plate 50 is formed on the second recess 23 and therefore the inner wall 18 of the groove 16 of the piston 10 which is more stable in terms of thermomechanical deformation than the outer wall 17 of the groove 16 of said piston 10. Indeed, the temperature being maximum in the piston 10 at the longitudinal axis 12, the centering of the closure plate 50 on the inner wall 18 of the piston 10 allows the closure plate 50 of adapt to the radial expansions of the piston 10.

Furthermore, the second recess 23 forming a shoulder is easily achievable. The second recess 23 also allows more space to be made, either to make a cooling gallery of the larger piston 10, or to make a piston bowl 10 whose shape extends more closely to the inner wall 18 and the second recess 23 of the cooling gallery of the piston 10.

As illustrated in FIGS. 2a and 2b, the upper wall 21 of the first recess 20 of the piston 10 is preferably shifted towards the lower part 14 of the piston 10 with respect to the upper wall 24 of the second recess 23 of the piston 10. This offset is by example of the order of 0.1 to 1mm, preferably 0.2mm.

In this way, the closing plate 50 works slightly in flexion, when it is mounted in the piston 10, thus ensuring a permanent contact between the closure plate 50 and the walls 21, 22, 24 of the first and second recesses 20, 23 of the groove 16 of the piston 10, without generating a mounting force or significant stresses between the closure plate 50 and the recesses 20, 23 of the groove 16.

As illustrated in FIGS. 1a and 1b, the lower wall 22 of the first recess 20 of the piston 10 preferably comprises one or a plurality of access housings 25 to the first recess 20 and the outer edge 51 of the closure plate 50 preferably comprises one or a plurality of protrusion 53 extending radially and of complementary shape with the access housing 25 of the piston 10. The plurality of access housings 25 of the piston 10 is for example arranged so as to form an alternation of housing and complementary projections, and the plurality of projections 53 of the closure plate 50 is for example arranged so as to form an alternation of projections and housing of complementary shape and substantially of the same dimensions as the housings 25 and corresponding projections of the piston 10. "Substantially the same size" means that the projections and housings are of the same size with close play, ie re to plus or minus 0.1mm.

In this way, to mount the closure plate 50 in the piston 10, the closure plate 50 is inserted into the first and second recesses 20, 23 by placing the projections 53 of the closure plate 50 facing each other and the access housing 25 of the piston 10, as illustrated in FIG. 4. Then, the closing plate 50 is pivoted about the longitudinal axis 12, sliding in the first and second recesses 20, 23, so that that the projections 53 of the closure plate 50 and the access housing 25 of the piston 10 are no longer facing each other, the closure plate 50 then being locked in translation along the longitudinal axis 12 by the upper wall 21 of the first recess 20 of the groove 16 of the piston 10. The closure plate 50 can also be pivoted to allow the access housings 25 to be released from the piston 10 for mounting a second closure plate 50 according to the procedure described above. (Figure 5).

In the example illustrated in Figures 1a and 1b, the access housing 25 and the projections of the piston 10 are of complementary shape and the same dimensions, the projections 53 and the housing of the closing plate 50 is de facto also shaped complementary and substantially the same dimensions. In a variant, the access housings 25 and the projections of the piston 10 are of complementary shape and of different dimensions, the projections 53 and the housings of the closing plate 50 being in fact also of complementary shape and of different dimensions. This variant has the advantage of preventing any error in the mounting direction of the closure plate 50 in the piston 10.

In the example illustrated in FIG. 1a, the plurality of access housings 25 of the piston 10 extend generally over a half-circumference of the groove 16. This has the advantage of limiting oil leaks from the gallery of cooling the piston 10, in particular between the first recess 20 and the closure plate 50.

As illustrated in FIG. 2b, the radial dimensions of the closure plate 50 are defined so as to ensure a minimum clearance between the outer edge 51 of the closure plate 50 and the external wall 17 of the groove 16, so that limit oil leakage from the cooling gallery to the outside of the piston 10.

In the example illustrated in Figures 1a and 1b, the upper wall 24 of the second recess 23 of the piston 10 and the inner edge 52 of the closure plate 50 are provided with locking means 26, 54 in rotation around the longitudinal axis 12 of the closure plate 50 relative to the piston 10. The rotational locking means 26 of the piston 10 is for example a notch as is more specifically illustrated in FIG. 3 and the rotational locking means 54 of the closure plate. 50 is for example a finger configured to be folded in the notch 26 of the piston 10. A notch 26 is preferably associated with each closure plate 50.

Alternatively, to lock in rotation the closure plate 50 about the longitudinal axis 12, the closure plate 50 can be welded to the piston 10. An additional component such as a ring spacer welded to the piston 10 can also be added between two adjacent closure plates 50. The ring spacer may further be configured to form the oil inlet and outlet ports.

Optionally, as illustrated in FIG. 1b, the closing plate 50 comprises gripping means 55 for assisting the sliding pivoting of the closure plate 50 around the longitudinal axis 12, in particular via a adapted tool. In the example illustrated in FIG. 1b, the closure plate 50 comprises for this purpose one or more stamped zones 55.

In the example illustrated in FIG. 5, the closing plates 50 are configured so as to form between them free spaces 56, 57 acting as inlet or outlet orifices respectively, when they are mounted. in the piston 10. Alternatively, the closure plates 50 may each be provided with one or more orifices for the entry and / or the oil outlet of the cooling gallery.

The closure plate 50 is preferably flat. The closure plate 50 is thus easy to design and produce allowing better manufacturing tolerances and less dispersion of mounting force on the piston 10.

The closure plate 50 comprises for example steel, aluminum or magnesium. Indeed, it is not necessary that the closure plate 50 has a specific elasticity that would allow its mounting by elastic deformation.

Claims (10)

An assembly for an internal combustion engine characterized in that it comprises: a piston (10) for an internal combustion engine comprising a cylindrical body (11) extending along a longitudinal axis (12) and comprising an upper part ( 13) and a lower part (14), the lower part (14) comprising an annular groove (16) formed around the longitudinal axis (12) forming a cooling gallery of the piston (10), the groove (16) comprising a radially outer wall (17) provided with a first recess (20) and a radially inner wall (18) provided with a second recess (23) arranged facing the first recess (20), the first recess (20) comprising an upper wall (21) and a lower wall (22) and the second recess (23) comprising an upper wall (24), - at least one closure plate (50) of the ring portion cooling tunnel , said closure plate (50) being configured in ur housing in the first and second recesses (20, 23) of the piston (10) and cover the groove (16) so as to close the cooling gallery of the piston (10), said closure plate (50) comprising an edge radially outer member (51) configured to form with the upper wall (21) and the lower wall (22) of the first recess (20) the upper and lower contact points (Pis, Pu) respectively, said closure plate (50) comprising in addition a radially inner edge (52) configured to form with the upper wall (24) of the second recess (23) an upper contact point (P2s). 2. The assembly of claim 1, wherein the upper wall (21) of the first recess (20) of the piston (10) is shifted towards the lower portion (14) of the piston (10) relative to the upper wall (24). the second recess (23) of the piston (10). 3. An assembly according to one of claims 1 to 2, wherein: - the bottom wall (22) of the first recess (20) of the piston (10) comprises one or a plurality of access slots (25) to the first recess (20) - the radially outer edge (51) of the closure plate (50) comprises one or a plurality of projections (53) extending radially from said edge and of complementary shape with the access housings (25) at the first recess (20) of the piston (10). 4. The assembly of claim 3, wherein the plurality of access housings (25) of the piston (10) is arranged to form an alternation of housing and complementary shaped projections of different dimensions, the plurality of projection (53) of the closure plate (50) being arranged to form an alternation of projections and housing of complementary shape and substantially the same dimensions as the corresponding housing and projections of the piston (10). 5. An assembly according to one of claims 1 to 4, wherein the radial dimensions of the closure plate (50) are defined so as to ensure a minimum clearance between the radially outer edge (51) of the closure plate (50). and the radially outer wall (17) of the groove (16) of the piston (10), when the closure plate (50) is mounted in the piston (10). 6. Assembly according to one of claims 1 to 5, wherein the upper wall (24) of the second recess (23) of the piston (10) and the radially inner edge (52) of the closure plate (50) are provided. locking means (26, 54) rotating about the longitudinal axis (12) of the closure plate (50) relative to the piston (10). An assembly according to one of claims 1 to 6, wherein the closure plate (50) comprises engagement means (55) configured to assist sliding pivoting of the closure plate (50) about the axis. longitudinal (12), when the closing plate (50) is mounted in the piston (10). 8. Assembly according to one of claims 1 to 7, wherein the closure plate (50) is flat. 9. Assembly according to one of claims 1 to 8, wherein the closure plate (50) is in the form of a half-ring. An internal combustion engine comprising: - a piston (10) for an internal combustion engine comprising a cylindrical body (11) extending along a longitudinal axis (12) and comprising an upper part (13) and a lower part (14). ), the lower portion (14) comprising an annular groove (16) formed around the longitudinal axis (12) forming a cooling gallery of the piston (10), the groove (16) comprising a radially outer wall (17) provided with a first recess (20) and a radially inner wall (18) provided with a second recess (23) arranged opposite the first recess (20), the first recess (20) comprising an upper wall (21) and a lower wall (22) and the second recess (23) comprising an upper wall (24), - at least one closure plate (50) of the ring-shaped cooling tunnel, said closure plate (50) being housed in the first and second recesses (20, 23) of the piston (10) so as to cover the groove (16) and close the cooling gallery of the piston (10), said closure plate (50) comprising a radially outer edge (51) forming with the upper wall (21). ) and the lower wall (22) of the first recess (20) of the upper and lower contact points (Pis, Pu) respectively, said closure plate (50) further comprising a radially inner edge (52) forming with the top wall (24) of the second recess (23) an upper contact point (P2s).