FI94281B - Piston for internal combustion engines and other similar machines - Google Patents

Description

94281 5 Piston for internal combustion engines and similar machines Kolv för förbränningsmotorer och andra liknande Maskiner

The invention relates to pistons intended to slide in cylinders of reciprocating internal combustion engines and compressors, i.e. cylinders of machines in which the operating gas contained in the cylinder or each cylinder is both high pressure and high temperature due to the cross-section of the piston 10, preferably two , the pistons comprising an externally cylindrical bearing surface on the outside of the cylindrical shell, which forms a connecting rod for receiving a partially spherical end of the seat 15. The piston seat and / or the end of the connecting rod may be embodied in a shape which is not partially spherical for the reasons set out below, but the term "spherical" as used herein to simplify the description means a shape which is completely or substantially spherical, the difference between these shapes to be done.

Such pistons are described, for example, in French patent publications no. 965 449 and no. 1,547,151 and in British Patent Publication no. 293 506. In the case of these known pistons, these two partially spherical elements of the piston and the connecting rod, which. are metal, move to contact each other, especially if a thin film of lubricating oil is maintained between them by supplying pressurized oil, for example from a longitudinal channel inside the connecting rod (see related French Patent No. 965,449 and British Patent No. 299).

The object of the invention is to enable the articulation between the piston and the connecting rod to withstand the considerable stresses applied to the piston as a result of high pressures, which pressures develop periodically in a variable-volume chamber limited by the piston inside its cylinder.

When the terms "upper", "lower", "above-2 94281 la" or "below" are used hereinafter, it is assumed that the piston is oriented so that its axis is vertical and that the connecting rod is located below this piston. This assumption is only intended to simplify the description, and thus does not mean that the piston is actually oriented in this way when it is installed in an internal combustion engine or compressor.

According to a first aspect of the invention, a piston of the type defined above is essentially characterized in that the piston comprises an open inner cavity at its end opposite to said cross-section, which is at least partially bounded laterally by a rotating-cylindrical support surface; that the space bounded by the partially spherical end of the connecting rod in the piston inside this cavity is filled with a viscous flowing or pasty or mouldable substance which is practically incompressible at the operating temperatures and pressures of the piston; and that the diameter of said cylindrical support surface is very slightly larger than the diameter of the partially spherical end of the connecting rod so that the operating clearance between said cylindrical support surface and the partially spherical end is small enough to completely prevent said substance from moving out of this space at piston operating temperatures, and under pressure.

The jacket line of said cylindrical surface is preferably parallel to the jacket line of the cylindrical jacket of the piston, this cylindrical support surface being generally coaxial with this jacket.

In order to completely prevent the loss of said substance in the long run, a thin metal shell is preferably placed between the partially spherical end of the connecting rod and said substance, which is made in place by pressing it against said cylindrical support surface, this assembly being such that against the cylindrical support surface the part is able to move 35 parallel to the axis of this cylindrical bearing surface under the effect of stresses exceeding a certain limit.

3,94281

According to another aspect of the invention, a piston for sliding in cylinders of reciprocating internal combustion engines and compressors, i.e. cylinders of machines in which the operating gas contained in the cylinder or each cylinder is preferably at high pressure or high temperature due to the piston cross-section, for four-stroke piston engines, which piston receives a partially spherical end of the connecting rod like a ball joint, it is essentially characterized in that the piston comprises an outer cavity, coaxial support surface; that a thin, liquid-tight metal shell is placed in said cavity, the lower part of which, pressed tightly against the support surface in the form of a rotary cylinder of the piston, has a cylindrical shape, and the upper part against which the end of the connecting rod rests is substantially hemispherical; that the outer surface of the substantially hemispherical portion of the metal shell delimits a space within the inner cavity of the piston filled with a viscous, pasty or moldable material that is substantially uncompressible at the operating temperatures and pressures of the piston; and that the outer diameter of the partially spherical end of the connecting rod is slightly smaller than the diameter of the cylindrical support surface of the piston so that the cylindrical part of the shell is compressed as described above and said substance is completely prevented from escaping said space at piston operating temperatures and pressures.

The above-mentioned substance is preferably a fluorinated polymer, in particular polytetrafluoroethylene (PTFE) or "TEFLON", although other materials which are chemically and physically stable at the operating temperatures and pressures of the piston and when compressed can also be used successfully for the same purpose. so malleable that they fill said space 35 as completely as possible (taking into account the possible presence of said mold) but are viscous enough to completely prevent said material from escaping into the clearance between the partially spherical head or shell and said cylindrical support surface during operation. In particular, a highly viscous oil can be used, which is used, for example, in viscosity-based vibration dampers. In particular, it is noted that the above definition of said substance does not cover in particular oils of low or medium viscosity.

In this way, whatever the position of the connecting rod with respect to the piston, a mattress formed of said deformable material, the passage of which is prevented from the space belonging to the piston, uniformly transmits the stresses on the piston to the partially spherical end of the connecting rod. Due to the ability of the shell (preferably in the presence of it) to move parallel to the axis of the cylindrical surface, this shell moves practically only in the case of perpendicular compression against its support surface 15, where there is no risk of breaking or puncturing, allowing axial movement of the mold. automatic exit.

20 It should be noted that the aforementioned French patent publication no. 1,547,151 proposes to place a plastic layer, such as a PTFE layer, directly between the partially spherical seat of the piston and the partially spherical end of the connecting rod, but on the opposite side from the side according to the present invention and for a completely different purpose. It should also be noted that it is known in the art to provide both counterparts of a vehicle ball joint, for example, with a synthetic resin, such as PTFE (see U.S. Patent No. 3,342,513), so that the two elements moving in contact with each other are synthetic resin.

30

The metal mold according to the invention is preferably made of bronze, in particular beryllium bronze, or of another metal or alloy which has a good lubrication friction coefficient and a high limit value for workability. Its thickness is generally 1-3% of the diameter of the partially spherical end of the helical 35.

In the case of the second aspect of the invention as defined above, the metal shell 5 94281 is preferably positioned so that its substantially hemispherical portion abuts against the partially spherical end of the connecting rod along a closed annular contact line or zone, the line or zone being preferably above the center of the connecting rod head 5 against a perpendicular plane, or the top of a line or zone of which is bounded by that plane; that the unidirectional means for supplying pressurized lubricating oil, which are connected upstream of the oil passage through the non-return valve to the circulating rod, terminate in a space bounded above said contact line or zone by a partially spherical head, a partially spherical head and a metal shell the pressure of the lubricating oil being greater than said pressure in said intermediate space 15 during at least part of the operating cycle of the engine before said non-return valve; and that the space below said contact line or zone, between the partially spherical head and the metal shell, communicates with a low pressure zone where the prevailing pressure is lower than the maximum pressure prevailing in said intermediate space.

In this way, the metal shell is incorporated into a means for supplying pressurized lubricating oil to the surface of the partially spherical end of the connecting rod, the connecting rod of which must be able to rotate freely with respect to the inner surface of said housing. Numerous embodiments of said space and lubricating oil supply means are described in detail below.

Furthermore, in the preferred case where a metal shell is present, the partially spherical end of the connecting rod or the side of the metal shell facing the end of the connecting rod is provided with grooves or lubrication channels for distributing the supplied lubricating oil to this housing and the connecting rod in a known or described manner. between the head. It should be emphasized that there is no risk of clogging the ointment channels with PTFE or other similar material or fluid, as they are made on surfaces that are not in contact with this material or fluid.

6,94281

However, in the absence of said shell, pressurized lubricating oil may be fed into an annular chamber, partially limited by the end of the connecting rod, as described below, so that use promotes the formation of a lubricating oil film at this end.

5

The invention will now be described in more detail with reference to the accompanying drawings.

Fig. 1 of the drawings is a partial axial section of a piston assembly and a corresponding connecting rod assembly according to a first embodiment of the invention.

Figure 2 shows a partly spherical rod head as seen in Figure 1 in the direction of the arrow shown.

15

Figure 3 shows details of the parts forming the ball joint of the piston and connecting rod before they are assembled.

Figures 4-7 are comparative schematic representations illustrating certain advantages of the invention.

Fig. 8 is a half-axial section of a piston assembly and a corresponding connecting rod assembly according to a second embodiment of the invention.

25

Fig. 9 is a partial axial section of a piston assembly and a corresponding pivot rod assembly according to a third embodiment of the invention.

Fig. 10 is a partial axial section of a piston assembly and a corresponding rotary rod assembly according to a fourth embodiment of the invention.

Figures 11 and 12 show lubrication means implemented in accordance with two different solutions, respectively.

Figures 13 and 14 show a first modification of the embodiment of Figure 1 of the UIN 1 7 94281, in axial section and from above, seen from the end of the connecting rod.

Fig. 15 shows another modification of the embodiment of Fig. 12.

The piston (Figures 1 and 2) according to the first embodiment of the invention, which is indicated in its entirety by the number 1, is intended to slide in the cylinder 2. This cylinder 2 contains the operating gas by means of the cross-section 10 of the piston 1 10.

The piston 1 comprises an externally cylindrical (the term "cylindrical" does not prevent the presence of recesses for the rings or the like) inside the jacket 3 a partially spherical seat 4, the function 15 of which is to receive a partially spherical end 5 of the connecting rod 6 like a ball joint.

According to the invention, the piston comprises an inner cavity 7 (see Fig. 3) delimited at least in part by a rotationally cylindrical support surface 20, which is preferably (but not necessarily) coaxial with said housing 3 (the common shaft is denoted XX), and which the diameter D is very slightly larger than the diameter d of the head 5. The cavity 7 in Fig. 1 is open downwards, i.e. in the opposite direction with respect to the cross-section 10. One of the approximately hemispherical surfaces 9a of the upper part of the seat 4 (according to Figures 1 and 3) consists of a single thin metal shell 9 concave in the opposite direction to said cross-sectional surface 10 of the piston 1, i.e. downwards in Figures 1 and 3. against the bladed support surface 8. Finally, the space 12 bounded inside the on-30 diaphragm 7 by the second surface 9b of the metal shell 9 is filled with a viscous or pasty or moldable material 13 which is practically incompressible at the operating temperatures and pressures of the piston 1.

As mentioned above, this substance or fluid 13 is preferably polytetrafluoroethylene or a similar paste.

t 8 94281

The advantage of the rotationally cylindrical shape of the support surface 8 in terms of co-operation with the partially spherical shape of the end of the connecting rod 5 and the value determined for its diameter D can be seen in comparative figures 4-7, of which the metal shell 9 is omitted 5 either to clarify the drawing in case this shell is present. to account for the embodiment (Fig. 9) in which this shell is missing.

If the diameter D of the cylindrical support surface 8 is too small (Fig. 10), it results in contact between the two metal surfaces between the head 5 and the edge of the cylindrical support surface 8, and no hydrostatic pressure is present in the fluid or substance 13.

If the diameter of the cylindrical support surface 8 is too large (Fig. 15 5), it will result in the material 13 leaking out from the sides, as shown by the arrows in Fig. 5.

If the diameter of the inlet of the cavity 7 is of the correct size, but if its side wall 8 is not cylindrical 20 (Fig. 6), then the clearance does not disappear by itself, which clearance can be due to either wear or uneven deformation (elastic or non-elastic), or uneven expansion, causing lateral leakage over time, as in the case of Figure 5.

If the cavity 7 is made according to the invention (Fig. 7), the clearance is caused to disappear automatically.

According to a preferred embodiment, the metal shell 9 is made of bronze, in particular beryllium bronze, or of another metal or alloy 30 which has a good limit value of the lubrication friction coefficient and high ductility. It will be appreciated that the piston assembly comprises conventional means, shown as passages 14 and 15 passing through the connecting rod 6 and its end 5, respectively, for guiding pressurized lubricating oil between the outer surface of the head 5 and the surface 9a of the blade 9.

Further, the partially spherical end 5 (Fig. 2) or the surface 9a of the shell 9 (Fig. 9 94281 3) is provided with grooves or lubrication channels 16.

In this way a piston is obtained, the manufacturing method of which is obvious from the above, and in the seat 4 the end 5 of the connecting rod 5 6 is placed, which head is then held in place in the case of a piston for at least a four-stroke internal combustion engine, for example with a rigid ring 17 flexibly tensioned. with the upwardly flexible ring 18, resting on the outside of the piston 1. The piston 10 for the two-stroke internal combustion engine may omit holding means, such as rings 17 and 18, since the stresses are always applied parallel to the piston during the engine operating cycle.

During operation, the force exerted on the upper surface of the piston 1 by the pressure of the operating gas is evenly distributed on the head 5 due to the mattress formed of the material 13.

As schematically shown in Figures 1 and 8, the metal shell 9 can be made to remain in place by pressing it against the cylindrical support surface 8 of the piston 1, provided, however, that this shell can move parallel to the axis X-X of this cylinder surface when the stress exceeds a certain limit.

According to the embodiment shown in Fig. 1, a shell 9, the half-25 spherical part of which is extended by a cylindrical sheath 11 in contact with the cylindrical support surface 8 of the piston 1, is placed on the piston 1 without securing it other than by pressing it between the head 5 and the piston cylindrical support surface 8. . This compression is achieved by selecting the thickness 30 (at rest) of the shell 9 and / or its outer diameter and the difference between said diameters D and d in the correct manner. This thickness is usually 1-3% of the diameter of the head 5.

According to the embodiment shown in Fig. 8, the hemispherical portion 35 of the shell 9 continues as a strongly expanded sheath 20 tightly seated between the lower end of the piston 1 sheath 3 and a ring 22 attached to this lower end of the sheath by suitable means such as wool. In order for the shell 9 to move parallel to the axis XX, the lower end of the housing 3 of the piston 1 comprises a rounded surface 21, and the dimensions of the housing 9 and in particular its housing 20 are determined by the volume of fluid or substance 13 so that the rounded surface 21 and the housing , there is a clearance 23 at rest between the part 9c opposite this surface 21, which allows the shape of the part 9c to change without being subjected to tensile stresses as the shell 9 moves axially with respect to the cylindrical support surface 8 of the piston 1.

10

The embodiment according to Fig. 9 differs from the embodiments shown in Figs. 1, 2 and 8 in that it lacks a shell between the partially spherical end 5 of the connecting rod 6 and the cylindrical support surface 8 of the piston 1. That is, the deformable material 13 is in direct contact with the head 5 and its escape from the cavity 7 is prevented simply by selecting the clearance between this end 5 and the cylindrical support surface 8 (or, resulting in the same result, the difference between said diameters D and d). taking into account the viscosity of substance 13.

20

The ratio between the cross-sectional area obtained along the diameter of the partially spherical head 5 and the transverse cross-sectional area of the piston 1 (measured perpendicular to the axis X-X) is greater than or equal to 0.5, which preferably limits the compressive stresses on the material 13 and the head 5 during operation. This characteristic also preferably applies in the presence of the shell 9, although it is not shown in the schematic representations of Figures 1 and 8.

According to the embodiment shown in Fig. 9, lubrication grooves such as those shown at 16 in Figs. In this case, a pressurized lubricating oil supply passage 14 made in the rotary rod communicates with passages 15a passing through the end 5 of the connecting rod, which passes continuously below the "equator plane" P perpendicular to the axis XX, passing through the center C of the partially spherical surface. chamber 25,

Illustrated below said plane P by a ring 17a analogous to the ring 17 shown in Fig. 1, which chamber 25 is, however, provided with outlets 26 for lubricating oil entering the chamber 25 via the channels 14 and 15a.

5

In any case, the height of the cylindrical support surface 8 must be large enough to accommodate the axial movement of the end 5 of the connecting rod 6 relative to the piston 1, corresponding to: 10 different thermal expansion (due to different coefficients of thermal expansion) and / or - compressibility and / or - manufacturing anomalies and / or 15 - wear phenomena.

It is assumed above that the fluid 13 is made of PTFE. Despite the obvious advantages of this substance, it has certain disadvantages. Particularly in the case of small or very small false sea buckthorns in the shell 9 (when present) there is a risk that the PTFE mat will not conform to them. In addition, the transverse trigger time of the distortion is relatively large.

In certain cases, in order to avoid the disadvantages associated with PTFE, it is preferable to replace it with a highly viscous liquid, for example silicone oils used in viscosity-based vibration trainers, preferably combined with the use of a shell 9 which is periodically distorted during use. This is illustrated in Figure 10, where the space 12 is filled from below (in the filling position) 30 to avoid possible air bubbles with highly viscous oil 13 through an opening 27 which is then closed with a cap or plug 28. During filling, air escapes (in the filling position) from the top 12 through an outlet 31 the opening is then closed with a cap or plug screw 32. The space 12 terminates a short distance 35 below the equatorial plane P in a rounding 29 (rather than obliquely). Indeed, the hydrostatic pressure of the mattress consisting of the viscous liquid 13 must be achieved up to this equatorial level P 12 94281 by thickening this mattress up to this level P. The annular seal 30 is placed in a groove made in the piston in such a way that it terminates on the cylindrical support surface 8 below said rounding 29, but as close as possible to the equatorial plane P to avoid the hydrostatic pressure removing the shell 9 from the cylindrical support surface 8. 13 leakage. However, it is necessary that the thickness of the space 12 be relatively small, for example about 2 mm, so that the effect of the compressibility of the very high viscosity oil 13 does not have to be taken into account, so that this oil can be considered practically uncompressed at operating temperatures and pressures. according to the general definition.

Hereinafter, means for utilizing the presence of the shell 9 to maintain a lubricating oil film between this shell 9 and the end 5 of the connecting rod will be described.

According to the invention and as shown in Fig. 11, in order to implement such means 20, the shell 9 is positioned so that its substantially hemispherical part 9a, 9b rests on the partially spherical end 5 of the connecting rod 6 along a closed circular contact line 33 located at the end of the connecting rod end. 5 in the plane Q passing above the center C (according to the above agreement), it being preferably perpendicular to the axis XX of the piston 1

regarding. According to a variant, the shell 9 can rest on the head 5 along a circular zone 34, the upper part of which zone is delimited by a line 33 and / or a plane Q. The unidirectional means for supplying pressurized lubricating oil on the upstream side communicate with the rotary rod 6 via a non-return valve 35 an intermediate space 36 bounded by parts located above said contact line 33 (or contact zone 34) of the end 5 of the connecting rod and the housing 9. This assembly is implemented in such a way that the pressure of the lubricating oil with respect to the non-return valve 35 on the upstream side is higher than the pressure prevailing in the intermediate space 36 during at least part of the operating gas compression-firing cycle. Finally, the space 37 between the end 5 of the connecting rod and the shell 9, below the contact line 13 94281 or zone 33 or 34, communicates with a low pressure outlet zone 38 where the pressure prevailing is lower than the maximum pressure prevailing in the intermediate space 36. In the presence of a ring 17a analogous to the ring shown in Figure 9 to hold the end 5 within the piston 1, at least one opening or channel 26 must pass through or rotate through this ring 17a to provide unobstructed contact with the outlet zone 38. If space 37 were tight, the lubricating oil would stand in space 36.

10

Preferably, and as shown in Figures 13 and 14, said intermediate space 36 consists essentially of a space between the shell 9 and the crank arm 5, located above their line of contact or zone 33,34, and a plurality of grooves 39 made in the housing 9 and the crank end 5. on at least one facing surface and in communication with the orifice of the one-way lubricating oil supply means, i.e., downstream of the non-return valve 35. To simplify the drawing, Fig. 11 shows only said space 20 between the shell 9 and the end of the connecting rod 5 and the contact line 33 and the contact zone 34, the latter being further shown in Fig. 14. The width of the grooves 39 and the like is approximately equal to the thickness of the shell 9. These grooves 39 are generally meridian-like grooves passing through this point of intersection and terminating in said line of contact or zone 33, 34. As in the case of the "equatorial plane" P, the term "meridian" or "meridian" is used in this connection. then comparing the end 5 of the connecting rod to the ground, the line through the poles of which forms the axis of the connecting rod and coincides with the axis XX of the piston 1 when the connecting rod 6 is placed on the axis 1 of the piston 1, as shown in Fig. 13, for example.

As shown in Figs. 14 and 15, the orifice of the unidirectional pressurized lubricating oil supply means is located at the intersection of the partially spherical surface of the connecting rod head 5 and the piston axis X-X, whatever the relative angular position of the connecting rod 6 and the piston 1 passes through and passes 39. terminating in said contact line 33 or the upper limit of the contact zone 34 14 94281.

In addition to the grooves 39 such as the meridians 39, at least one other groove 40 is made in the end 5 against the axis X-X of the piston 1 perpendicular to the meridian plane 5 above the contact line or zone 33,34 or at the upper limit of this contact zone 34. At least one further groove 41 is made in the end 5 against the axis X-X of the piston 1 in a plane perpendicular to the contact line or zone 33,34 or to the lower limit of this contact zone 34. Further, below this contact zone 10 34, in the meridian planes, other grooves 42 may be made. Alternatively, these grooves 39, 40 and 41 may be made on the inner surface 9b of the shell 9, their position being the same as the grooves preferably made on the crank end 5, at least when the crank 6 is located in the same line as the piston 1.

15

According to the solution shown in Fig. 11, the values of the thickness 9 of the shell 9 and the stiffness of its material are so small that the almost hemispherical upper part 9a, 9b of the shell 9 reaches the spherical appearance of the crank head 5 as a result of maximum forces , so that the oil retained in the intermediate space 36 passes through said line of contact or zone 33,34 to form a hydrostatic membrane towards said outlet zone 38, and these values are so large that the shell 9 returns to its original shape when the resultant of forces on the piston 1 is as small as possible , so that the pressure in the intermediate space 36 drops to a value lower than the pressure of the oil supplied by the non-return oil supply means 35 via the non-return valve 35.

As the piston reciprocates, the nearly hemispherical portion of the shell 9 acts as a diaphragm for the diaphragm pump, the suction phase of this pump due to the expansion of the space 36 and its ejection phase due to the contraction of this space due to the resilient deformation of the shell 9.

In this case, the shell 9 can be formed as follows:

Il IM l · I.III I I I Hl! I

15 94281 a) In the case of a shell, the upper part of which is almost hemispherical at rest, the shell 9 can be formed by pressing into a mold giving the required shape, whereby the end 5 of the connecting rod can be completely spherical (except naturally the lower part 5 is connected to the connecting rod 6) .

The disadvantage of this solution is that the intermediate space 36 is fixed with respect to the piston 1 and that grooves are required in it to supply oil to this intermediate space from an oil opening which is fixed with respect to the connecting rod 6.

B) In the case of a shell, the upper part of which has a hemispherical shape at rest, the end 5 of the connecting rod can be machined to free the space 36 around the oil hole. This machining can be carried out, for example, by turning a rotating part using a numerically controlled machine. In this case, the grooves described in the previous paragraph can be omitted.

According to the second solution shown in Figures 12-15, the unidirectional means for supplying pressurized oil comprise a rotary rod 6 and a piston pump integrated in the assembly of the rotary rod end 5, which sucks oil through the suction valve 43 and pushes it through said non-return valve 35.

According to a preferred construction, said pump consists of a cavity 44 of variable volume located between the suction valve 43 and the non-return valve 35 and bounded by a body of a connecting rod 6, the upper part 45 of which is made axially sliding in a bore 46 machined at the end of the connecting rod. A spring is placed between the body of the connecting rod 6 and the end 5 of the connecting rod.

The compression of this spring is so great that the pressure of the oil trapped in said cavity 44 between the two valves 35,43 may exceed the pressure in said intermediate during at least part of the working gas compression-firing cycle, the length of this spring 35 being so large that its relative compression exceed the limits of elastic deformation and not of the fatigue of the spring material, the stiffness of the spring being so low that the spring 16 94281 is capable of compressing so that the bearing surfaces of the crankshaft head 5 and the crankshaft body 6 come into contact with each other when the piston 1 is high , and the stiffness being so great that the spring 5 is able to release when the resultant of the forces acting on the piston is at least at its smallest.

According to the simplest embodiment schematically shown in Fig. 14, said spring is a simple coil spring 47. Mechanical means 10, not shown, restrict the movement of the end 5 of the connecting rod in the direction away from the connecting rod 6.

According to the most advanced embodiments shown in Figures 13-15, said spring is a metal rod, which is preferably titanium.

According to the embodiment shown in Fig. 13, the metal rod shown at 48 is tubular in shape and surrounds the end portion 45 of the connecting rod body 6. This portion 45 is in the form of a cylinder tapered to the adjacent portion of the connecting rod body 6 to form an annular rim 49 against one of the axial ends of the tubular rod 48 rests.

According to the modification shown in Fig. 15, the metal bar 25 shown at 50 is massive except for the elongate channel 51 passing through it as an extension of the channel 14 of the connecting rod 6.

Whatever embodiment is applied, the relative contraction of the rod 48 or 50 is about 0.25%, and its cross section is preferably about 3% of the cross section of the piston 1.

A metal bar, such as 48 or 50, which can generally be considered rigid, can act as a spring if its cross section is small enough compared to the compressive stresses acting on it, but still 35 large enough to remain in the resilient compression range of the metal from which the bar is made. The advantage of the metal bar compared to the spring shown in Fig. 12 is its lower space requirement and the shark. mu i 17 94281 reduction in the number of dead holdings. Titanium is preferred over steel because its modulus of elasticity (Young's modulus; 11.3.105 bar) is about half that of steel (22.105). In the case of equal compression, the compression ‘5 of the bar 48 or 50’ is twice that of the steel bar, or in the case of a given compression, the length of the titanium bar is half the length of the steel bar.

Claims (25)

1. A piston designed to slide in cylinders of piston engines and compressors based on internal or external combustion, or in 5 cylinders of such machines where the propellant gas in the cylinder or each cylinder thanks to the transverse surface (10) of the coil (1) is bed at high pressure and at high temperature, advantageous for two-stroke or four-stroke piston engines, which piston (1) within the outer cylindrical male end (3) comprises a partially spherical bearing surface (4) which an approach for receiving the partially spherical end (5) of a drawbar (6), characterized in that the cowling comprises an open inner hollow (7) at the opposite end relative to said cross-surface (10), side health is at least partially limited by a support surface (8) in the form of a rotary cylinder; that a space (12) which limits the partially spherical end (5) of the drawbar (6) within this cavity (7) is filled with viscous flowing or forging or reshaping substance (13), which substance is practically non-compressive only at the operating temperatures and pressures of the piston (1); and that the diameter (D) of said cylindrical support surface (8) is slightly larger than the diameter (d) of the partially spherical end (5) of the drawbar (6) in such a manner that the operating space between said cylindrical support surface (8) ) and the partially spherical end (5) is small enough to completely prevent said blank (13) from escaping from this space at the operating temperatures and pressures of the piston. Piston according to claim 1, characterized in that the casing line of said cylindrical surface is parallel to the casing line of the cylindrical casing (3) of the coif (1), said cylindrical supporting surface (8) being generally coaxial with this casing. (3). Piston according to either of claims 1 or 2, characterized in that a thin metal sheath (9) is placed between the partially spherical end (5) of the drawbar (6) and said blank (13). in place by pressing it against said cylindrical support surface (8), this whole being such that the part of the manifold (9) pressed against the cylindrical supporting surface (8) is moved to move parallel to the axis of this cylindrical supporting surface (8). the impact of crowding that exceeds a certain limit. 5 4. Pistons intended to slide in cylinders of piston engines and compressors based on internal or external combustion, ie in cylinders of such machines where the propellant gas in the cylinder or each cylinder thanks to the transverse surface (10) of the cow (1) ) is located at high pressure bed and at high temperature, advantageous for two-stroke or four-stroke piston motors, which piston (1), like a ball joint, receives the partially spherical end (5) of a drawbar (6), known as - characterized in that the cowl comprises an open internal hollow (7) inside the outer cylindrical male end (3) at its opposite end in relation to said cross-section (10), which at least in part is limited by a supporting surface ( 8) in the form of a rotary cylinder which is advantageously coaxial with the coif (1); a thin, liquid-tight metal sheath (9) has been placed in said hollow (7), the lower part of which is tightly pressed against the rotating cylindrical support surface (8) of the piston (1), is in the shape of a cylinder (11), and the upper part of which is supported by the end (5) of the drawbar is essentially the shape of a hemisphere; that the substantially hemispherical outer surface (9b) of the portion of the metal sheath (9) limits a space (12) within the inner sanctum (7) of the piston (1) filled with a viscous smudged or reshapable substance which is practically not compressible at the operating temperatures and pressures of the piston (1); and that the outer diameter (d) of the partially spherical end (5) of the drawbar (6) is slightly smaller than the diameter of the cylindrical support surface (8) of the piston (1) in such a manner that the cylindrical portion of the sheath (9) (11) is pressed above as seen above, and that the output of said substance from said space (12) is completely prevented at the operating temperatures and pressures of the piston (1). 5. A piston as claimed in any one of claims 3 or 4, characterized in that the metal sheath (9) is made of bronze, especially of beryllium bronze, or any other such metal or alloy, where the limit value of the lubrication coefficient is good and 27 94281 whose malleability is high. Piston according to any one of claims 3-5, characterized in that the partially spherical end (5) of the drawbar (6) or the surface (9a) of the metal jacket (9) facing the end (5) of the drawbar is provided with rafters or lubrication channels (16), the purpose of which is to spread the lubricating oil passed between the manifold (9) and the end (5) of the drawbar. Piston according to any of claims 3-6, characterized in that the manifold (9) is mounted in the cowl (1) without attaching it in any other way than by pressing against the cylindrical support surface (8) of the cowl (1). Piston according to any one of claims 3-6, characterized in that the male end (9) comprises a hemispherical part, which is followed by a strongly expanded sheath (20), which is densely implanted towards the lower end of the male end (3). of the cow (1), this whole being such that there is a gap (23) between the lower end of the jacket (1) of the piston (1) and the portion (9c) of the male (9) in a resting state. Piston according to any one of claims 3-8, characterized in that the thickness of the male insert (9) is 1-3% of the diameter (d) of the partially spherical end (5) of the drawbar (6). 10. A piston according to any one of claims 1-9, characterized in that said blank (13) is a fluorinated polymer, in particular polytetrafluoroethylene. 30 Piston according to any one of claims 1-9, characterized in that said blank (13) is of very viscous oil, for example, such an oil used in vibration dampers based on viscosity. 35 Piston according to any one of claims 1-11, characterized in that the ratio between the surface of the cut obtained along the diameter of the partially spherical end (5) and the transverse cutting of the cow (1) is greater than or equal to with 0.5. 13. A piston according to either of claims 3 or 4, either separately or in combination with any of claims 5-12, characterized in that the manifold (9) is positioned in such a way that its substantially hemispherical part is supported against the partially spherical end (5) of the drawbar (6) along the closed circular contact line or zone (33 or 34), said line or zone being located in a plane (Q) extending above the center (C) of the end ( 5) of the drawbar, or this plane (Q) limits the upper part of this line or zone, this tab being advantageously perpendicular to the axis (XX) of the cow (1); that the parallel feed means of the pressurized lubricating oil, which on the overcurrent side by means of a check valve (35) is in communication with the oil channel (14) made in the drawbar (6), terminates in an intermediate space (36) which is limited by portions located above said contact line or zone (33,34) and belongs to the end (5) of the drawbar and mannequin 20 (9), the pressure of the lubricating oil being greater relative to the non-return valve (35) on the overcurrent side than the pressure which rises in said intermediate space (35) for at least part of the compression-release period of the propellant gas; and that the space (35) located between the end (5) of the drawbar and manifold (9) below the contact line or zone 25 (33,34) is in communication with a low pressure exit zone (38) where lower than the highest pressure which raises in said intermediate space (36). Piston according to claim 13, characterized in that said intermediate space (36) consists of a space which substantially remains between the manifold (9) and the end (5) of the drawbar, while being located above their contact line or zone. (33,34), and of a plurality of rafters (39,40,41,42) made on at least one facing surface of the male thread (9) and the end (5) of the drawbar, the width of which is 35 advantageously lies the thickness of the male threads (9), which latches (39,40,41,42) are in communication with the mouth opening of the parallel feeding means of the lubricating oil. 29 94281 Piston according to claim 14, characterized in that the mouth opening of the parallel feeding tools for the pressurized lubricating oil is located at the intersection of the partially spherical surface of the end (5) of the drawbar and the piston (1) shaft (XX). a portion of the aforementioned spar (39) is spar which runs in the form of longitudinal circuits which run through this intersection and terminate at said contact line or zone (33, 34). 16. A plunger according to either of claims 14 or 15, characterized in that at least one (40) of said lock is advantageously located at the plane of the partially spherical surface of the end (5) of the drawbar which is perpendicular to the axis (XX) of the piston (1) axial tone where the pull rod (6) is located coaxially with the coiffure, this bar being located above or below said contact line or zone (33, 34). Piston according to any of claims 14-16, characterized in that at least a part (41, 42) of said lock is advantageously made below said contact line or zone (33, 34) on the partially spherical the surface of the end (5) of the drawbar, advantageously at the plane of the longitudinal circuits. Piston according to any one of claims 13-17, characterized in that the thickness of the male insert (9) and the stiffness of its manufacturing material are so small that the proximal half-circular upper part (9a, 9b) of the male integral (9) is completely achieves the appearance of the partially spherical surface of the end (5) of the drawbar as a result of the resilient shape change, where the resultant force directed towards the cow (1) is greatest, in such a way that the oil poured into said intermediate space ( 36) protrudes over said contact line or zone (33,34) thereby forming a hydrostatic film against said exit zone, and said thickness and stiffness is so Great that men (9) return to their original shape where the resultant of the forces is acting on the coil (1) is at least in such a way that the pressure traveling in the intermediate space (36) drops to a value lower than the pressure on the oil supplied by the parallel ·· feeding tools. one of the oil. 94281 30 19. A piston as claimed in any of claims 13-17, characterized in that the parallel feeding tools for the pressurized oil comprise a piston pump which sucks through a suction valve (43) and pushes it through said non-return valve (35). 5 Piston according to claim 19, characterized in that said pump comprises a variable volume (44) located between said suction valve (43) and said non-return valve (35), which is limited by the actual body of the drawbar, the the upper part (45) is made in said partially spherical end (5) of the drawbar to a piston sliding in the borehole (46) in the direction of the shaft, and a spring (47) is placed between said body of the drawbar and said partially spherical end (5) of the drawbar. Piston according to claim 20, characterized in that the compression of said spring (47) is so great that the pressure on the oil which is kept in the hollow (44) between these two valves (35, 43) can exceed the pressure which rises in said intermediate space (36) for at least a portion of the compression release period of the propellant gas, the length of this spring (47) being so large that its relative compression does not exceed the elastic shape change or fatigue limit values of the spring material being small, the stiffness of the spring being small , that the spring is adversely compressed in such a way that the supporting surfaces of the end (5) of the drawbar 25 and the body (6) of the drawbar come into mutual contact, where the results of the forces directed towards the cowling (1) are maximally at most , whereby this stiffness is large, that the spring's forearms are triggered, where the resultant of the forces directed towards the cow (1) is minimal as a minimum. 30 Piston according to claim 21, characterized in that said spring consists of a metal rod (48.50). Piston according to claim 22, characterized in that the material on this rod (48.50) is made of titanium. Piston according to claim 23, characterized in that the relative compression of the stitch (48.50) is 0.25%. 25. A piston according to any of claims 23 or 24, characterized in that the cross-section of this stitch (48.50) is about 5% of the cross-section of the piston (1). •