WO2017046480A1

WO2017046480A1 - Double-acting piston

Info

Publication number: WO2017046480A1
Application number: PCT/FR2016/052234
Authority: WO
Inventors: Vianney Rabhi
Original assignee: Vianney Rabhi
Priority date: 2015-09-14
Filing date: 2016-09-07
Publication date: 2017-03-23
Also published as: FR3041041A1; FR3041041B1

Abstract

The invention relates to a double-acting piston (1) which comprises a lower half-piston (13) and an upper half-piston (14), the periphery of each so-called half-piston (13, 14) abutting radially with a radial traction disc (30) which is held clamped by a clamping screw (29) between the two so-called half-pistons (13, 14) at the centre thereof, between a lower central clamping surface (19) and an upper central clamping surface (20) as well as, at the periphery thereof, between a lower peripheral clamping surface (21) and an upper peripheral clamping surface (22), the clamping by said screw (29) of said disc (30) having the effect of pre-stressing the lower piston crown (15) and the upper piston crown (16) which are provided on the lower half-piston (13) and the upper half-piston (14), respectively.

Description

DOUBLE EFFECT PISTON

The present invention relates to a double-acting piston operable at high temperature, consisting of a prestressed assembly.

It would be of great energy interest to make volumetric regenerative engines inspired by turbocharged Brayton cycle engines, power turbine, burner and regenerator. These latter engines are the main source of power for certain gas-fired power plants or certain vessels such as those powered by the "Rolls-Royce WR-21" engine.

It should be noted that the applicant holds two French patent applications relating to a heat transfer-expansion and regeneration engine. The first of these requests was registered on January 30, 2015 under the number 1550762, and the second is dated February 25, 2015 and bears the number 1551593.

This engine differs from conventional regenerative Brayton cycle engines in that the normally used driving turbine is replaced by a regulator cylinder whose energy performance is maximized by intake and exhaust metering valves operating in a special mode described in the "operation" section of those applications.

In particular, the phasing of the intake metering valve maximizes the output of the expansion of the gases by extending the latter to the exhaust pressure. In addition, the phasing of the exhaust metering valve is provided to re-compress the residual exhaust gas trapped in the dead volume found at the top dead center of the piston so that before the metering valve opens admission, the pressure and the temperature of said gases become equivalent to those of the gases leaving the burner. This last phasage avoids any irreversibility due to the discharge of gas under high pressure in a dead volume remained under low pressure.

According to said applications, the replacement of said power turbine by said expansion cylinder is in particular made possible by innovative piston sealing means which prevent the pressurized gases from escaping between said cylinder and the expansion piston with which it cooperates. These last two bodies being brought to very high temperature, they exclude any recourse to some lubrication by oil whether a segment or a ring and any contact between the hot expansion cylinder on the one hand, and a segment or a seal on the other hand.

This is why the innovative sealing means proposed in patent applications No. 1550762 and No. 1551593 make it possible to overcome any need for lubrication and contact by maintaining an air film interposed between a ring. perforated continuous and the expander cylinder, the flow of said air further ensuring the cooling of said ring. By the same token, the said requests propose a layout and novel technical solutions that solve a technical problem hitherto unresolved, thus answering the identified and unmet need to make possible the production of regenerative engines of a much higher efficiency. to that of Brayton cycle engines with turbine regeneration, and far superior to that of Otto or Diesel internal combustion internal combustion engines of any type.

It is noted that in the applications No. 1550762 and No. 1551593, the sealing means are in secondary claim not to exclude the possibility of other sealing means that would provide the same benefits.

This being exposed, whether the piston expander as presented in applications Nos. 1550762 and 1551593, or any other piston expander or not, since said piston operates at high temperature, it must be constituted a material with sufficiently high mechanical strength at high temperature such as alumina, silicon carbide or zirconium oxide.

Said expander piston must also remain light to limit the inertial forces it generates at high speeds, while being able to withstand the high pressure forces to which it can be subjected.

In addition, the fastening means which connect said piston to the transmission means which make it possible to collect the work produced by said piston must preferably be made of steel with a high mechanical resistance which is not very compatible with the high temperatures to which the piston piston is subjected. even.

This is why the double-acting piston according to the invention is provided for the positive displacement cylindrical and piston positive thermal machines operating at high temperature, and to meet the triple need for said piston to remain lightweight, resistant, and compatible with steel fastening means to be maintained at low temperature. In the field of application of reciprocating thermal machines with piston (s) in general and heat engines in particular, it follows from the invention a double-acting piston, light, resistant, and compatible with high-grade steel fastening means. mechanical resistance. It is understood that the double-acting piston according to the invention is adaptable to any machine or apparatus with (e) at least one cylinder operating at high temperature. By way of non-limiting example, among the examples of application of said invention is the transfer-expansion and regeneration thermal engine which is the subject of French patent applications Nos. 1550762 and 1551593, said applications belonging to the applicant.

The other features of the present invention have been described in the description and in the dependent claims directly or indirectly dependent on the main claim.

The double-acting piston can operate at high temperature and cooperating with transmission means to move in a cylinder whose end which opens on the side of said means is closed by a lower yoke to define with said piston a lower hot gas chamber , and whose other end is closed by an upper yoke to define with said piston a higher hot gas chamber, the transmission means being housed in a transmission housing on which is fixed directly or indirectly the cylinder, comprises according to the invention: · A lower half-piston which has a piston lower cap oriented towards the lower hot gas chamber, said cap being extended by a lower piston rod which passes through the lower cylinder via a lower stem orifice arranged in said cylinder head, said rod being directly or indirectly secured to the transmitting means ission, while the face of said half-piston opposite said cap is hollow and constitutes a lower relief obviously; • A lower central pillar, coaxial with the lower half-piston, which is housed in the lower relief lightening to end with a lower central clamping surface; · At least one lower peripheral clamping surface arranged on the lower half-piston and which borders the lower relief of relief at the periphery of said half-piston;

• At least one lower radial stopper arranged in the lower half-piston near the lower peripheral clamping surface;

• A lower clamping screw shaft formed in the lower half-piston at its center, and which passes through said half-piston from one side in the axial direction; · An upper half-piston which has an upper piston crown facing the upper hot gas chamber, said crown being extended or not an upper piston rod which penetrates or passes through the upper cylinder head via an upper stem orifice arranged in said cylinder head, while the face of said half-piston opposite said cap is hollow and constitutes an upper relief of relief;

• An upper central pillar, coaxial with the upper half-piston, which is housed in the upper relief of lightening and ends with an upper central clamping surface;

• At least one upper peripheral clamping surface arranged on the upper half-piston and which borders the upper relief of relief at the periphery of said half-piston; · At least one upper radial stopper arranged in the upper half-piston near the upper peripheral clamping surface;

• An upper clamping screw well arranged in the upper half-piston at its center, and which passes through said half-piston from one side in the axial direction; • At least one perforated radial disc with or without perforation, pierced at its center with a screw hole, whose outer diameter is close to that of the double-acting piston, whose central zone is tightly mounted between the surface of lower central clamping and the upper central clamping surface, the peripheral zone of which is mounted tight between the lower peripheral clamping surface and the upper peripheral clamping surface, and the periphery of which has at least one radial traction stop which can cooperate with the lower radial stop stop and / or upper radial stop;

A clamping screw housed partly in the lower clamping screw well and partly in the upper clamping screw well, the first end of said screw being secured to the transmission means while the second end of said screw is secured to the upper piston rod or the upper piston crown.

The double-acting piston according to the present invention comprises a thickness and a geometry of the radial traction disk as well as an axial position of the lower central clamping surface, the upper central clamping surface, the lower peripheral clamping surface, and of the upper peripheral clamping surface which are provided so that when the tightening screw is tightened when the double-acting piston is mounted, said disk is first compressed between the lower peripheral clamping surface and the upper front peripheral clamping surface to be compressed between the lower central clamping surface and the upper central clamping surface.

The double-acting piston according to the present invention comprises a radial position of the radial tensile stop relative to that of the lower radial stop and / or the upper radial stop which is provided for when mounting of the double-acting piston the tightening screw is tightened, said lower and / or upper radial stop stop comes into contact with the radial tensile stop and limits the diameter of the lower half-piston and / or the upper half-piston . The double-acting piston according to the present invention comprises a radial traction disc which has at its periphery a segment groove which can accommodate sealing means. The double-acting piston according to the present invention comprises a segment groove which is housed in a throat groove which commonly constitutes a lower overhang which comprises at its periphery the lower half-piston, and an upper overhang which comprises in its periphery the half - upper piston.

The double-acting piston according to the present invention comprises at least one radial air supply duct which is arranged in the thickness of the radial traction disc, said duct connecting the screw orifice to the periphery of said disc.

The double-acting piston according to the present invention comprises a radial traction disc which consists of two radial traction half-discs on the surface of at least one of which is arranged at least one radial channel groove which constitutes the radial duct. supplying air when the two said half-discs are pressed against each other following the tightening of the clamping screw.

The double-acting piston according to the present invention comprises an end of the upper piston rod which is furthest from the upper piston crown which always remains immersed in a pressure chamber filled with compressed air irrespective of the position of the piston. double-acting piston in the cylinder, said chamber being secured or not to the upper yoke and being connected to a source of pressurized air from which the compressed air originates, whereas said end has at least one feed channel; air that connects the upper clamp screw well to the pressure chamber.

The double-acting piston according to the present invention comprises an air supply channel which consists of a radial groove arranged either at the flat end of the upper piston rod which is farthest from the upper piston crown. or on at least one of the faces of a screw bearing washer on which the clamping screw bears.

The double-acting piston according to the present invention comprises a screw cooling tube which wraps the clamping screw over all or part of its length, compressed air from the pressurized air source being able to circulate in a space left between the inner wall of said tube and the surface external of the clamping screw while the largest possible part of the outer surface of said tube does not touch the inner wall of the upper clamping screw well so as to define with the latter wall a void space. The double-acting piston according to the present invention comprises a screw cooling tube which has a tube flange held tight by the clamping screw against the end of the upper piston rod.

The double-acting piston according to the present invention comprises a screw cooling tube which comprises at least one tube bulge consisting of an axial portion of said tube whose diameter is substantially equivalent or even slightly greater than that of the upper clamping screw well. or the lower clamping screw well in which it is housed. The double-acting piston according to the present invention comprises a screw cooling tube which comprises at least one tube diameter restriction consisting of an axial portion of said tube whose diameter is substantially equivalent or even slightly less than that of the body of the screw. Clamping. The double-acting piston according to the present invention comprises a screw cooling tube which has at least one radial communication hole which allows the compressed air to enter or escape from said tube.

The double-acting piston according to the present invention comprises a lower stem orifice and / or an upper stem orifice which cooperates with or comprises rod sealing means which provide a seal between the lower piston rod and the lower yoke and / or between the upper piston rod and the upper yoke. The double-acting piston according to the present invention comprises rod sealing means which comprise an upper stem seal and a lower stem seal sufficiently far apart to form - between the two said seals - a chamber an oil-circulating circuit in which a cooling-lubricating oil supply duct opens and from which a cooling-lubricating oil outlet duct is released. The double acting piston according to the present invention comprises rod sealing means which cooperate with a rod guide ring housed inside or outside the oil circulation chamber. The description which follows with reference to the appended drawings and given by way of non-limiting examples will make it possible to better understand the invention, the characteristics that it presents, and the advantages that it is likely to provide: FIG. three-dimensional three-quarters of a cylinder assembly, lower yoke and upper yoke fixed on a transmission housing which receives the double-acting piston according to the invention.

FIG. 2 is a three-dimensional front view and cut away of the double-acting piston according to the invention, the latter being housed in the cylinder with which it co-operates, said sight also representing the transmission casing which houses the transmission means provided for collecting the work produced by said piston, said means being according to this embodiment consisting of a rod articulated on a crank connected to a crankshaft, and a stick.

Figure 3 is an exploded three-dimensional view of the double-acting piston according to the invention, and the various members with which it cooperates.

Figure 4 is a schematic longitudinal section of the double-acting piston according to the invention with a medallion close-up view showing the detail of the throat groove which - according to a particular embodiment - accommodates the segment groove in which is housed a ring continuous perforated.

Figure 5 is a schematic sectional view including rod sealing means which cooperate with the lower piston rod of the double-acting piston according to the invention.

FIG. 6 is a diagrammatic sectional view in particular of shaft sealing means which cooperate with the upper piston rod of the double-acting piston according to the invention, said upper stem opening - according to this particular embodiment - in a chamber of pressure. DESCRIPTION OF THE INVENTION

FIGS. 1 to 6 show the double-acting piston 1, various details of its components, its variants, and its accessories.

As shown in FIG. 2, the double-acting piston 1 according to the invention that can operate at high temperature cooperates with transmission means 8 to move in a cylinder 2 whose end which opens on the side of said means 8 is closed by a lower yoke 4 for defining with said piston 1 a lower hot gas chamber 6, and whose other end is closed by an upper yoke 5 to define with said piston 1 a higher hot gas chamber 7, the transmission means 8 being housed in a transmission casing 3 on which the cylinder 2 is directly or indirectly fixed. In this same FIG. 2, it will be noted that the transmission means 8 may in particular be constituted by a connecting rod 9 articulated around a crank 10 arranged. on a crankshaft 11, said connecting rod 9 being connected to the double-acting piston 1 by means of a stick 12. As a variant not shown, the means of tra Transmission 8 may consist of a cam, a hydraulic transmitting pump, an electricity generator or any other means of transmission known to those skilled in the art.

Note also that - as shown in particular in Figures 1 to 3 - the lower yoke 4 and the upper yoke 5 may comprise at least one valve 70 controlled by a valve actuator 71.

FIG. 4 in particular illustrates that the double-acting piston 1 according to the invention comprises a lower half-piston 13 which has a piston lower cap 15 facing the lower hot gas chamber 6, said cap 15 being extended by a lower piston rod 17 which passes through the lower yoke 4 via a lower stem orifice 37 provided in said yoke 4, said rod 17 being directly or indirectly secured to the transmission means 8, while the face of said opposite half-piston 13 said cap 15 is hollow and constitutes a lower relief of relief 25. It will be appreciated that the lower lightening recess 25 may be compartmentalized and / or reinforced with ribs. In addition, the lower piston crown 15 and the lower piston rod 17 can be made in one and the same piece of a material that retains a high mechanical strength at high temperature such as alumina, silicon carbide or silicon. zirconium oxide.

FIGS. 3 and 4 show that the double-acting piston 1 according to the invention comprises a lower central pillar 23, coaxial with the lower half-piston 13, which is housed in the lower lightening recess 25 and ends with a surface bottom central clamping 19.

It will be noted that advantageously, the lower central pillar 23 can be made in the same piece of material as the lower half-piston 13, or be attached to it.

Figures 3 and 4 illustrate that the double-acting piston 1 according to the invention comprises at least one lower peripheral clamping surface 21 arranged on the lower half-piston 13 and which borders the lower relief of relief 25 at the periphery said half-piston 13, said surface 21 may be provided minimum to provide the least possible passage to heat.

The double-acting piston 1 according to the invention also comprises at least one lower radial stop 35 arranged in the lower half-piston 13 near the lower peripheral clamping surface 21.

In addition, as shown in FIGS. 3 and 4, the double-acting piston 1 according to the invention comprises a lower clamping screw well 27 arranged in the lower half-piston 13 at its center, and which passes through said half-piston. 13 from one side to the other in the axial direction.

In FIGS. 3 and 4, it can be seen that the double-acting piston 1 according to the invention comprises an upper half-piston 14 which has an upper piston crown 16 oriented facing the upper hot gas chamber 7, said cap 16 being extended or not an upper piston rod 18 which penetrates or passes through the upper yoke 5 via an upper rod hole 38 provided in said cylinder head 5, while - as particularly illustrated in FIG. 4 - the face of said half-piston 14 opposed to said cap 16 is hollow and constitutes an obvious upper lightening 26 compartmentalized or not and / or reinforced ribs or not, the upper piston cap 16 and the upper piston rod 18 may be preferably made in one and the same piece of a material that retains a high mechanical strength at high temperature such as alumina, silicon carbide or zirconium oxide.

In FIG. 4, there is an upper central pillar 24 that comprises the double-acting piston 1 according to the invention, said pillar 24 being coaxial with the upper half-piston 14, while said pillar 24 is housed in the upper recess of FIG. lightening 26 to end with an upper central clamping surface 20, said pillar 24 can be made in the same piece of material as the lower half piston 14, or be reported on it.

Figures 3 and 4 illustrate that the double-acting piston 1 according to the invention has at least one upper peripheral clamping surface 22 provided on the upper half-piston 14 and which borders the upper relief of relief 26 at the level around said half-piston 14, said surface 21 may be provided minimum to offer the least possible passage to heat. FIGS. 3 and 4 show that the double-acting piston 1 according to the invention has at least one upper radial stopper 36 arranged in the upper half-piston 14 near the upper peripheral clamping surface 22.

Moreover, the double-acting piston 1 according to the invention also comprises an upper clamping screw well 28 arranged in the upper half-piston 14 at its center, and which passes through said half-piston 14 from one end to the other in the axial direction. Said well 28 is particularly visible in FIGS. 3 and 4.

Still in FIGS. 3 and 4, it can be seen that the double-acting piston 1 according to the invention comprises at least one radial traction disk 30 that may or may not be perforated, pierced at its center by a screw-passing orifice 31, whose diameter the outer zone is close to that of the double-acting piston 1, whose central zone 32 is tightly mounted between the lower central clamping surface 19 and the upper central clamping surface 20, the peripheral zone 33 of which is mounted tightly between the clamping surface lower peripheral 21 and the upper peripheral clamping surface 22, and whose periphery comprises at least one radial radial abutment 34 which can cooperate with the lower radial stop 35 and / or the upper radial stopper 36 so as to limit the outside diameter of the lower half-piston 13 and / or the upper half-piston 14.

Finally, FIGS. 3 and 4 show that the double-acting piston 1 according to the invention comprises a clamping screw 29 housed partly in the lower clamping screw well 27 and partly in the upper clamping screw well 28, the first end of said screw 29 being secured to the transmission means 8 while the second end of said screw 29 is secured to the upper piston rod 18 or the upper piston cap 16 in the case where the latter is not not extended by an upper piston rod 18.

Note that said ends can be made integral with the transmission means 8 and the other with the upper piston rod 18 or the upper piston cap 16 by means of a screw head clamping 67, or a screw thread 68 which comprises the clamping screw 29, said threading 68 screwing into a nut or a tapping.

Note further that the tightening of the clamping screw 29 has the effect of clamping the radial traction disc 30 between the lower central clamping surface 19 and the upper central clamping surface 20 of a first part, and between the surface lower peripheral clamping device 21 and the upper peripheral clamping surface 22 of the second part.

Note that if the upper piston cap 16 is not extended by an upper piston rod 18, the head or the nut which terminates the clamping screw 29 and which holds tightly said cap 16 can be housed in a fitted cavity in the latter, said cavity can be closed by a plug.

In any case, the clamping screw 29 does not exclude the possibility of providing one or more other screws which interconnect the lower piston crown 15 and the upper piston crown 16.

Nor can it be ruled out that the shape and / or the curvature of the lower piston crown 15 is different from that of the upper piston crown 16, the said crowns 15, 16 may furthermore comprise recesses or protuberances. facing valves or valves that may respectively comprise the lower yoke 4 and / or the upper yoke 5 .. It will be noted that according to a particular embodiment of the double-acting piston 1 according to the invention, the thickness and the geometry of the radial traction disc 30 as well as the axial position of the lower central clamping surface 19, of the surface of the upper central clamping 20, the lower peripheral clamping surface 21 and the upper peripheral clamping surface 22 may be provided so that when the mounting of the double-acting piston 1 is tightened the clamping screw 29, said disc 30 is first compressed between the lower peripheral clamping surface 21 and the upper peripheral clamping surface 22 before being compressed between the lower central clamping surface 19 and the upper central clamping surface 20.

As a result of this arrangement, the lower piston crown 15 and the upper piston crown 16 are prestressed, which guarantees the tightening of the radial traction disc 30 when the double-acting piston 1 deforms under the effect of the pressure. prevailing in the lower hot gas chamber 6 or in the upper hot gas chamber 7.

Still according to a particular embodiment of the double-acting piston 1 according to the invention, the radial position of the radial tensile stop 34 relative to that of the lower radial stop 35 and / or the stop stop radial upper 36 may be provided so that when the assembly of the double-acting piston 1 is tightened the clamping screw 29, said lower radial stop stop 35 and / or upper 36 comes into contact with the radial tensile stop 34 and limits the diameter of the lower half-piston 13 and / or the upper half-piston 14.

As a result of this arrangement, the lower piston crown 15 and the upper piston crown 16 each constitute two arches which oppose a high mechanical resistance to the forces produced by the pressure prevailing in the lower hot gas chamber 6 and / or in the chamber The first base of the vaults that constitutes the lower piston cap 15 is stowed at the lower central pillar 23 while the second base of said vaults is stowed at the lower radial stop 35. it is the same for the upper piston cap 16 which forms two arches whose bases are respectively stowed at the upper central pillar 24 and at the upper radial stop stop 36. FIGS. 3 and 4 show that according to the double-acting piston 1 according to the invention, the radial traction disk 30 may have at its periphery a segment groove 39 which can accommodate sealing means 40 such as a continuous ring perforated 41 air cushion similar or identical to that described in French patent applications No. 1550762 and No. 1551593 belonging to the applicant and allowing the realization of a heat transfer engine-relaxation and regeneration.

FIG. 4 makes it possible to specify visually that the segment groove 39 can be housed in a throat groove 42 that is commonly a lower overhang 43 that has at its periphery the lower half-piston 13, and an upper overhang 44 that comprises in its periphery the upper half-piston 14.

According to this particular configuration, a thermal insulation space may advantageously be left between the radial traction disk 30 at the segment groove 39, and the groove 42, said space constituting a thermal barrier.

It is noted in FIG. 4 that the double-acting piston 1 according to the invention may comprise at least one radial air supply duct 45 arranged in the thickness of the radial traction disc 30, said duct 45 connecting the passage opening screw 31 at the periphery of said disk 30 so for example to supply compressed air 54 a perforated continuous ring 41 air cushion similar or identical to that described in the French patent applications No. 1550762 and No. 1551593 belonging to applicant and allowing the realization of a thermal engine transfer-relaxation and regeneration.

It should also be noted that the cavities constituted by the lower lightening recess 25 and the upper lightening recess 26 can be pressurized by the compressed air 54 which supplies the perforated continuous ring 41 or which supplies all other means sealing member 40 requiring said compressed air 54.

FIGS. 3 and 4 show that according to the double-acting piston 1 according to the invention, the radial traction disc 30 may consist of two radial traction half-discs 46 on the surface of at least one of which is arranged at least one radial duct groove 47 which constitutes the radial duct for supplying air 45 when said two half-discs 46 are pressed against each other following the tightening of the clamping screw 29.

Figures 2, 3 and 6 illustrate that according to an alternative embodiment of the double-acting piston 1 according to the invention, the end of the upper piston rod 18 which is furthest from the upper piston cap 16 may still remain dipped in a pressure chamber 49 filled with compressed air 54 regardless of the position of the double-acting piston 1 in the cylinder 2. Note that said chamber 49 may or may not be integral with the upper yoke 5 and be connected to a source of pressurized air 50 from which the compressed air 54 comes, while the end of the upper piston rod 18 has at least one air supply channel 48 which connects the upper clamping screw well 28 with the pressure chamber 49 so for example to cooperate with the supply of compressed air 54 of a perforated continuous ring 41 air cushion similar or identical to that described in French Patent Application No. 1550762 and n 1551593 belonging to the applicant and allowing the realization of a thermal engine transfer-relaxation and regeneration. Alternatively, the pressure chamber 49 may be connected to the lower clamping screw well 27, an air supply channel connecting said well 27 to said chamber 49. In this case, said chamber 49 may for example be formed by the volume swept by a butt 12 sealed to be connected to the pressurized air source 50.

It should be noted that - whatever the configuration adopted - the pressurized air source 50 may comprise an air compressor which forces the compressed air 54 to circulate in the upper clamping screw well 28 or the screw well. lower clamping 27, said compressor being able to continue to operate a certain time after stopping the thermal machine to which the double-acting piston 1 according to the invention applies. This last arrangement allows for example to evacuate the heat that said piston 1 is likely to continue to transmit during its cooling to the clamping screw 29. It can be specified here that the air supply channel 48 may be optionally constituted of at least one radial groove arranged at the flat end of the upper piston rod 18 which is furthest from the upper cap of piston 16, that is on at least one of the faces of a screw support washer on which the clamping screw 29 bears.

As shown in FIGS. 3 and 4, the double-acting piston 1 according to the invention may comprise a screw cooling tube 53 which envelops the clamping screw 29 over all or part of its length, a compressed air 54 coming from the source of pressurized air 50 able to circulate in a space left between the inner wall of said tube 53 and the outer surface of the clamping screw 29, while the largest possible part of the external surface of said tube 23 does not touch the inner wall of the upper clamping screw well 28 so as to define with the latter wall an empty space.

Note that according to the chosen embodiment of the double-acting piston 1 according to the invention, the screw cooling tube 53 can descend at the level of the lower clamping screw well 27.

As can be seen in FIGS. 3 and 4, the screw cooling tube 53 may comprise a tube flange 55 held tight by the clamping screw 29 against the end of the upper piston rod 18.

In addition, the screw cooling tube 53 may also comprise at least one tube bulge 56 consisting of an axial portion of said tube 53 whose diameter is substantially equivalent or even slightly greater than that of the upper clamping screw well 28 or lower clamping screw well 27 in which it is housed, this ensuring that said tube 53 remains locally centered in said well 28 or 27, and realizing if necessary a seal between said tube 53 and said well 28 or 27.

Note also in Figures 3 and 4 that the screw cooling tube 53 may possibly include at least one tube diameter restriction 57 consisting of an axial portion of said tube 53 whose diameter is substantially equivalent to or slightly less than that of the body of the clamping screw 29 in order to locally seal between said tube 53 and said screw 29. In FIG. 58, it can be seen that the screw cooling tube 53 may comprise at least one radial communication hole 58 which allows the compressed air 54 to enter said tube 53, or to escape. It will be noted in FIGS. 2, 3, 5 and 6 that according to a particular embodiment of the double-acting piston 1 according to the invention, the lower stem orifice 37 and / or the upper stem orifice 38 can cooperate with - or may comprise - rod sealing means 59 which provide a seal between the lower piston rod 17 and the lower yoke 4 and / or between the upper piston rod 18 and the upper yoke 5.

More specifically, FIGS. 5 and 6 show that the shaft sealing means 59 may comprise an upper shaft seal 60 and a lower shaft seal 61 sufficiently spaced apart from each other to form between the two said seals. 60, 61 - an oil circulating chamber 62 into which a cooling lubricating oil supply duct 63 opens and from which a cooling lubricating oil outlet duct 64 leaves.

It should be noted that the oil circulation chamber 62 has the dual function of lubricating and cooling the lower piston rod 17 and / or the upper piston rod 18. It should also be noted that the upper rod 60 and / or or the lower seam seal 61 may consist in particular of a segment with a section or two segments with superimposed section and whose sections are angularly offset while the external surface of the lower piston rod 17 and / or the rod upper piston 18 may be provided with shallow double-helix stripes which form a succession of oil tanks and hydrodynamic lift surfaces.

In FIG. 5, it can be seen that the segment (s) constituting the upper rod seal 60 can be kept at a distance from those constituting the lower rod seal 61 by a segment spacer spring 65 also designed - in particular because it includes orifices or passages - to pass the cooling and lubricating oil flow established between the cooling oil-lubricating supply line 63 and the cooling-lubricating oil outlet duct 64.

Also, according to a particular embodiment of the double-acting piston 1 according to the invention, all or part of the space left between the clamping screw 29 and the inner wall of the lower clamping screw well 27 and / or the well clamping screw 28 may be filled with sodium, lithium salts or potassium to indirectly promote cooling of the lower piston rod 17 and / or the upper piston rod 18 by the oil flow chamber 62. As shown in FIG. 6, the rod sealing means 59 can cooperate with a rod guide ring 66 housed inside or outside the oil circulation chamber 62, said ring 66 being made of bronze or any other material usually used to manufacture bearings or rings antifriction and / or hydrodynamic.

Said ring 66 can ensure the radial guide of the lower piston rod 17 in the lower yoke 4 and / or the upper piston rod 18 in the upper yoke 5. It should also be noted that if - as shown in FIGS. 2, 4 and 5 - the transmission means 8 comprise a stick 12, the rod sealing means 59 are preferably provided with a rod guiding ring 66 when they apply to the upper piston rod 18 while that the radial guide of the lower piston rod 17 is provided by said butt 12 only.

OPERATION OF THE INVENTION:

The operation of the double-acting piston 1 according to the invention is easily understood from the view of FIGS. 1 to 6.

To detail said operation, it will be assumed here that said double-acting piston 1 applies to the heat transfer-expansion and regeneration engine of which the French patent applications No. 1550762 and No. 1551593 belong to the applicant. This application has an exemplary value and does not exclude any other use of the double-acting piston 1 according to the invention.

As is particularly noted in Figures 2 and 3, the double-acting piston 1 can move in the cylinder 2 which is closed by its lower yoke 4 and its upper yoke 5. Thus, said piston 1 and said cylinder 2 constitute with the lower yoke 4 a lower hot gas chamber 6, and with the upper yoke 5 a higher hot gas chamber 7. Note that the cylinder 2 is fixed on the transmission housing 3 which houses the transmission means 8 which is connected to the double-acting piston 1. Said means 8 are provided to transform the back and forth movements that takes place in the cylinder 2 the double-acting piston 1, in continuous rotational movement of a crankshaft 11. For these purposes and still according to this non-limiting example, said means 8 consist of a connecting rod 9 connected to the double-acting piston 1 by means of a butt 12, said connecting rod 9 being articulated around a crank 10 arranged on the crankshaft 11. It is noted that in the transfer-expansion and regeneration heat engine taken here as an example of application, it is it is necessary to provide sealing means 40 similar to those described in French Patent Application Nos. 1550762 and 1551593 and which belong to the applicant. As such and as illustrated in Figures 2 to 4, one can for example provide a perforated continuous ring 41 housed in a segment groove 39, mounting said ring 41 requiring that said groove 39 is assembled in two parts. For this first reason and because otherwise it is extremely difficult to lighten the double-acting piston 1, Figures 2 to 4 show that the latter is assembled and consists of a lower half-piston 13 and a half-piston. upper piston 14.

This configuration effectively makes it possible to provide a segment groove 39 itself assembled which allows the mounting of the perforated continuous ring 41. In addition, said configuration makes it possible to achieve a lower recess of relief 25 in the lower half-piston 13 and an upper relief of relief 26 in the upper half-piston 14.

Note that for the double-acting piston 1 according to the invention is as light as possible, it is imperative to solicit the constituent material in the most rational way possible. It is for this reason that said piston consists of a prestressed assembly which - according to the non-limiting embodiment taken here to illustrate the operation - provides that the lower piston crown 15 and the upper piston crown 16 each constitute two arches of small thickness respectively with the lower recess of relief 25 and with the upper recess of relief 26. For a vault to be rigid, it is necessary that its two bases are securely stowed. This is a prerequisite for said vault to retransmit the load to which it is subjected to said bases. Thus, as can be seen clearly in FIG. 4, the stowage of the first base of the two arches formed by the lower piston crown 15 consists of the junction between said cap 15 and the lower central pillar 23 while the stowage of the second base of the two so-called vaults consists of the lower radial stop stop 35 which is supported on the radial tensile stop 34 that includes the peripheral zone 33 of the radial traction disc 30. The same principle is retained for the upper cap piston 16.

Recall here that the thickness and the geometry of the radial traction disc 30 as well as the axial position of the lower central clamping surface 19, the upper central clamping surface 20, the lower peripheral clamping surface 21 and the surface upper peripheral clamping means 22 are provided so that when the mounting of the double-acting piston 1 is tightened the clamping screw 29, said disc 30 is first compressed between the lower peripheral clamping surface 21 and the upper peripheral clamping surface 22 before being compressed between the lower central clamping surface 19 and the upper central clamping surface 20.

It follows clearly from this arrangement that the lower piston crown 15 and the upper piston crown 16 are deformed and are prestressed, which guarantees, on the one hand, the clamping of the radial traction disc 30 at its peripheral zone 33 when the double-acting piston 1 deforms under the effect of the pressure prevailing in the lower hot gas chamber 6 or in the upper hot gas chamber 7, and which also guarantees the support of the stop lower radial stop 35 and the upper radial stopper 36 each against the radial traction stop 34 with which they cooperate.

As can be seen in FIGS. 3 and 4, advantageously, the radial traction disc 30 consists of two radial traction half-discs 46 on the surface of which are formed radial duct grooves 47 which constitute as many radial supply ducts. 45 when the two said half-disks 46 are pressed against each other following the tightening of the clamping screw 29. This configuration allows to convey compressed air from the pressure chamber 49 until to the perforated continuous ring 41 which constitutes according to this example non-limiting sealing means 40 between the double-acting piston 1 and the cylinder 2.

FIGS. 3 and 4 show the clamping screw 29 which makes it possible to clamp together the lower half-piston 13, the radial traction disc 30, and the upper half-piston 14. Advantageously, this screw is made of high-grade steel mechanical resistance which must remain at a relatively low temperature not exceeding - for example - one hundred and fifty or two hundred degrees Celsius. For this, it is noted that the clamping screw 29 is in direct contact only with parts held at low temperature. For example, said screw 29 comprises a clamping screw head 67 which remains in contact with the end of the upper piston rod 18 which still remains immersed in the pressure chamber 49 maintained at low temperature whatever the position of the piston In addition, said screw 29 has a screw thread 68 screwed into the butt 12 which is also maintained at low temperature.

Note that the body of the clamping screw 29 is not in contact with the inner wall of the lower clamping screw well 27, nor with that of the upper clamping screw well 28, nor with the Since the air is a powerful thermal insulator, this arrangement drastically limits any transfer of heat from the lower half-piston 13 and the upper half-piston 14 to the body of the clamping screw 29. Moreover, note the role of cooler of the body of the clamping screw 29 that plays air from the pressure chamber 49 and to the perforated continuous ring 41, said air passing through the screw cooling tube 53. Indeed, this air maintained at a moderate temperature of the order of a hundred degrees or less penetrates into said tube 53 via the air supply ducts 48 which comprises - according to the embodiment shown in FIGS. 2 to 4 - a perforated support washer 69 that encloses the screw head Age 67. Particularly in FIG. 4, it is noted that after passing through said channels 48, said air enters via the tube flange 55 into the space left between the screw cooling tube 53 and the external surface of the screw. tightening 29.

It will be noted - particularly in FIG. 4 - that the screw cooling tube 53 has in the vicinity of the tube flange 55 a bulge of tube 56 which ensures that said tube 53 remains locally centered in the upper clamping screw well 28. It is further seen that on either side of the screwthread port 31, two further tube bulges 56 each constitute both centering and sealing respectively between the screw cooling tube 53 and the upper clamping screw well 28, and between said tube 53 and the lower clamping screw well 27. These said two further bulges 56 cooperate with a restriction of tube diameter 57 arranged in the vicinity of the lower end of the screw cooling tube 53, said restriction 57 locally providing a seal between said tube 53 and the body of the clamping screw 29.

The medallion of FIG. 4 also shows the particular arrangements provided by the double-acting piston 1 according to the invention for protecting the perforated continuous ring 41 from any excessive rise in temperature. As such, it is noted in this medallion the segment groove 39 formed by the two radial traction half-discs 46 when the latter are pressed against one another following the tightening of the clamping screw 29.

It can be seen in particular that the lower overhang 43 and the upper overhang 44 together form a throat groove 42 which leaves an air gap between themselves and the radial traction disc 30 at the segment groove 39. Said blade constitutes a thermal barrier which limits the heat transfer from the lower half-piston 13 and the upper half-piston 14 towards the perforated continuous ring 41. In FIG. 5, it can be seen that the rod sealing means 59 which seal between the lower hot gas chamber 6 and the lower piston rod 17 while ensuring the lubrication of the upper shaft seal 60 and the lower shaft seal 61 which are constituted by said means 59. It is noted that said means 59 also provide cooling of the lower piston rod 17 by means of an oil circulation chamber 62 into which a cooling-lubricating oil feed pipe 63 opens and from which a coolant-lubrication oil outlet duct 64 returns. It is easy to notice that the oil flow circulating between said ducts 63, 64 being in permanent contact with the lower piston rod 17, said flow rate allows to maintain said rod 17 at a temperature for example slightly above one hundred degrees Celsius, but not higher. Still in FIG. 5, it can be seen that, advantageously, the upper shaft seal 60 consists of two superimposed section segments whose sections are angularly offset while the lower shaft seal 61 consists of a single segment with a section. both said seals 60, 61 being spaced from each other by a segment spacer spring 65 which includes orifices allowing the flow of coolant and lubricating oil to pass between the supply line of the cooling-lubricating oil 63 and the cooling-lubricating oil outlet duct 64 via the oil circulation chamber 62.

FIG. 6 illustrates the same arrangement, with the main difference that the segment spacer spring 65 gives way to a rod guide ring 66 which provides radial guidance of the upper piston rod 18 which, according to the non-limiting example, A limiting example taken here to illustrate the operation of the double-acting piston 1 according to the invention opens into the pressure chamber 49 which supplies the perforated continuous ring 41 with compressed air.

When the heat transfer engine-relaxation and regeneration taken here as an example of application stops, it is noted that the oil pump that feeds the oil flow chambers 62 continues to supply them with oil to cool the lower piston rod 17 and the upper piston rod 18 and this, as long as the lower yoke 4 and the upper yoke 5 continue to transmit heat to said chambers 62 and may carry the oil contained in said chambers 62 at temperature of coking.

The possibilities of the double-acting piston 1 according to the invention are not limited to the applications which have just been described and it must also be understood that the foregoing description has been given only as a example and it does not limit the field of said invention which one would not go out by replacing the execution details described by any other equivalent.

Claims

1. Double-acting piston (1) capable of operating at high temperature and cooperating with transmission means (8) to move in a cylinder

(2) whose end which opens onto the side of said means (8) is closed by a lower yoke (4) to define with said piston (1) a lower hot gas chamber (6), and the other end of which is closed by an upper cylinder head (5) to define with said piston (1) an upper hot gas chamber (7), the transmission means (8) being housed in a transmission casing

(3) on which the cylinder (2) is fixed directly or indirectly, characterized in that it comprises:

A lower half-piston (13) which has a lower piston cap (15) oriented facing the lower hot gas chamber (6), said cap (15) being extended by a lower piston rod (17) which passes through the lower cylinder head (4) via a lower rod hole (37) provided in said cylinder head

(4), said rod (17) being directly or indirectly made integral with the transmission means (8), while the face of said half-piston (13) opposite said cap (15) is hollow and constitutes a lower recess of relief (25);

A lower central pillar (23), coaxial with the lower half-piston (13), which is housed in the lower relief recess (25) to end in a lower central clamping surface (19);

At least one lower peripheral clamping surface (21) arranged on the lower half-piston (13) and which borders the lower relief recess (25) at the level of the periphery of said half-piston (13);

At least one lower radial stop (35) arranged in the lower half-piston (13) near the lower peripheral clamping surface (21);

A lower clamping screw well (27) arranged in the lower half-piston (13) in its center, and which passes through said half-piston (13) right through in the axial direction; An upper half-piston (14) which has an upper piston cap (16) oriented facing the upper hot gas chamber (7), said cap (16) being extended or not by an upper piston rod (18) which enters or passes through the upper cylinder head (5) via an upper rod hole (38) provided in said cylinder head

(5), while the face of said half-piston (14) opposite said cap (16) is hollow and constitutes an upper relief recess (26);

An upper central pillar (24), coaxial with the upper half-piston (14), which is housed in the upper relief recess (26) to terminate in an upper central clamping surface (20);

At least one upper peripheral clamping surface (22) arranged on the upper half-piston (14) and which borders the upper relief recess (26) at the level of the periphery of said half-piston (14);

At least one upper radial stopper (36) arranged in the upper half-piston (14) near the upper peripheral clamping surface (22);

An upper clamping screw well (28) arranged in the upper half-piston (14) in its center, and which passes through said half-piston (14) right through in the axial direction;

At least one radial traction disc (30), perforated or not, pierced in its center with a screw passage orifice (31), the external diameter of which is close to that of the double-acting piston (1), the area of which central clamping surface (32) is mounted tight between the lower central clamping surface (19) and the upper central clamping surface (20), the peripheral zone (33) of which is mounted tight between the lower peripheral clamping surface (21) and the upper peripheral clamping surface (22), and the periphery of which comprises at least one radial traction stop (34) which can cooperate with the lower radial stop stop (35) and/or the upper radial stop stop (36 ) ; • A tightening screw (29) housed partly in the lower tightening screw well (27) and partly in the upper tightening screw well (28), the first end of said screw (29) being made integral with the transmission means (8) while the second end of said screw (29) is made integral with the upper piston rod (18) or the upper piston cap (16).

Double-acting piston according to Claim 1, characterized in that the thickness and geometry of the radial traction disc (30) as well as the axial position of the lower central clamping surface (19), of the upper central clamping surface (20), the lower peripheral clamping surface (21) and the upper peripheral clamping surface (22) are provided so that when mounting the double-acting piston (1) the clamping screw (29) is tightened. , said disc (30) is first compressed between the lower peripheral clamping surface (21) and the upper peripheral clamping surface (22) before being compressed between the lower central clamping surface (19) and the surface of upper central tightening (20).

Double-acting piston according to claim 2, characterized in that the radial position of the radial traction stop (34) relative to that of the lower radial stop stop (35) and/or the radial stop stop upper (36) is provided so that when mounting the double-acting piston (1) the tightening screw (29) is tightened, said lower (35) and/or upper (36) radial stop stop comes into contact with the radial traction stop (34) and limits the diameter of the lower half-piston (13) and/or the upper half-piston (14).

Double-acting piston according to claim 1, characterized in that the radial traction disk (30) has at its periphery a segment groove (39) which can accommodate sealing means (40).

Double-acting piston according to claim 4, characterized in that the segment groove (39) is housed in a groove groove (42) which commonly constitutes a lower overhang (43) which has on its periphery the lower half-piston ( 13), and an upper overhang (44) which has on its periphery the upper half-piston (14).

6. Double-acting piston according to claim 1, characterized in that at least one radial air supply conduit (45) is arranged in the thickness of the radial traction disk (30), said conduit (45) connecting the screw passage hole (31) at the periphery of said disc (30).

7. Double-acting piston according to claim 6, characterized in that the radial traction disk (30) consists of two half-radial traction disks (46) on the surface of at least one of which is arranged at least a radial duct groove (47) which constitutes the radial air supply duct (45) when the two said half-discs (46) are pressed against each other following tightening of the tightening screw ( 29).

8. Double-acting piston according to claim 1, characterized in that the end of the upper piston rod (18) which is farthest from the upper piston cap (16) always remains immersed in a pressure chamber ( 49) filled with compressed air (54) whatever the position of the double-acting piston (1) in the cylinder (2), said chamber (49) being integral or not with the upper cylinder head (5) and being connected to a source of pressurized air (50) from which the compressed air (54) comes while said end has at least one air supply channel (48) which connects the upper clamping screw well ( 28) with the pressure chamber (49).

9. Double-acting piston according to claim 8, characterized in that the air supply channel (48) consists of a radial groove arranged either at the flat end of the upper piston rod (18) which is furthest from the upper piston cap (16), i.e. on at least one of the faces of a screw support washer on which the clamping screw (29) rests.

10. Double-acting piston according to claim 8, characterized in that a screw cooling tube (53) surrounds the clamping screw (29) over all or part of its length, compressed air (54) coming from the source of pressurized air (50) capable of circulating in a space left between the internal wall of said tube (53) and the external surface of the clamping screw (29) while as much as possible of the external surface of said tube ( 23) does not touch the internal wall of the upper clamping screw well (28) so as to define an empty space with this last wall.

11. Double-acting piston according to claim 10, characterized in that the screw cooling tube (53) comprises a tube collar (55) held tight by the clamping screw (29) against the end of the upper rod piston (18).

12. Double-acting piston according to claim 10, characterized in that the screw cooling tube (53) comprises at least one tube bulge (56) consisting of an axial portion of said tube (53) whose diameter is substantially equivalent or even slightly greater than that of the upper clamping screw well (28) or the lower clamping screw well (27) in which it is housed.

13. Double-acting piston according to claim 10, characterized in that the screw cooling tube (53) comprises at least one tube diameter restriction (57) consisting of an axial portion of said tube (53) whose diameter is substantially equivalent or even slightly lower than that of the body of the tightening screw (29).

14. Double-acting piston according to claim 10, characterized in that the screw cooling tube (53) comprises at least one radial communication hole (58) which allows compressed air (54) to enter said tube (53), or to escape from it.

15. Double-acting piston according to claim 1, characterized in that the lower rod orifice (37) and/or the upper rod orifice (38) cooperates with - or comprises - rod sealing means ( 59) which provide a seal between the lower piston rod (17) and the lower cylinder head (4) and/or between the upper piston rod (18) and the upper cylinder head (5).

16. Double-acting piston according to claim 15, characterized in that the rod sealing means (59) comprise an upper rod seal (60) and a lower rod seal (61) sufficiently distant from each other. another to form - between the two said seals (60, 61) - an oil circulation chamber (62) into which a cooling-lubricating oil supply conduit (63) opens and from which a conduit leaves cooling-lubrication oil outlet (64).

17. Double-acting piston according to claim 16, characterized in that the rod sealing means (59) cooperate with a rod guide ring (66) housed inside or outside the circulation chamber of oil (62).