The present invention relates to a double-acting piston operable at high temperature, consisting of a prestressed assembly.
It would be very interesting, in terms of energy, to manufacture volumetric regenerative engines inspired by Brayton's cycle engines with turbocharger, power turbine, burner and regenerator. The latter engines are the main power source of some gas-fired electricity generating plants or some vessels such as those powered by the “Rolls-Royce WR 21” engine.
We note that the applicant holds two French patent applications relating to a transfer-expansion and regenerative heat engine. The first of these applications was recorded on Jan. 30, 2015 under No. 1,550,762, and the second is dated Feb. 25, 2015 and bears the No. 1,551,593.
Said engine differs from the conventional Brayton regenerative cycle engines in that the commonly used power turbine is replaced by an expander cylinder whose energy efficiency is maximized by intake and exhaust metering valves operating according to a special mode described in the “operation” section of the said applications.
In particular, the phasing of the intake metering valve maximizes the efficiency of the gas expansion by extending the latter to the exhaust pressure. Furthermore, the phasing of the exhaust metering valve is arranged to re-compress the residual exhaust gases trapped in the void volume found at the top dead center of the piston so that before the intake metering valve opens, the pressure and temperature of said gases become equivalent to those of the gases exiting the burner. This latter phasing avoids any irreversibility due to discharge of high pressure gas in a dead volume that remained under low pressure.
According to said applications, the replacement of said power turbine by said expander cylinder is especially enabled by innovative piston sealing means which prevent pressurized gas from leaking between said cylinder and the regulator piston with which it cooperates. The latter two bodies being brought to very high temperature, they exclude any recourse to oil lubrication of either a segment or a ring and any contact between the hot expander cylinder, on the one hand, and a segment or a sealing gasket, on the other hand.
That is why the innovative sealing means proposed in patent applications No. 1,550,762 and No. 1,551,593 allow overcoming any need for lubrication and contact by maintaining an air film sandwiched between a perforated continuous ring and the expander cylinder, the flow of said air further providing cooling of said ring.
Thus, said applications propose an arrangement and novel technical solutions that solve a technical problem so far unresolved, thus meeting the need identified and unmet to enable the production of regenerative engines with a performance substantially higher than that of Brayton turbine regenerative cycle engines, and substantially higher than that of Otto or Diesel internal combustion alternative heat engines of any type.
It should be noted that in applications No. 1,550,762 and No. 1,551,593, the sealing means are included in a secondary claim so as not to exclude the possibility of other sealing means which would provide the same benefits.
This being exposed, whether it is the regulator piston as described in Applications No. 1,550,762 and No. 1,551,593, or any other piston, regulator or not, once said piston operates at high temperatures, it must be made of a material having a sufficiently high mechanical strength at high temperature such as alumina, silicon carbide or zirconium oxide.
Said regulator piston must also remain light to minimize the inertial forces that it generates at high speeds, while being able to withstand high pressure loads to which it may be subjected.
In addition, the fastening means connecting said piston to the transmission means that collect the work produced by said piston are preferably made of high strength steel hardly compatible with the high temperatures to which the regulator piston itself is subjected.
That is why the double-acting piston according to the invention is provided for reciprocating displacement heat engines with cylinder and piston operating at high temperature, and for meeting the triple need for said piston to remain lightweight, resistant, and compatible with steel fastening means that must be kept at low temperature.
In the scope of application of the reciprocating heat machines equipped with piston(s) in general, and heat engines in particular, the invention provides a light, resistant and compatible double-acting piston with fastening means made of high strength steel.
It should be understood that the double-acting piston according to the invention is adaptable to any machine or device equipped with at least one cylinder operating at high temperature. As a non-limiting example, among the examples of application of said invention is the transfer-expansion and regenerative heat engine object of French patent applications No. 1,550,762 and No. 1,551,593, said applications belonging to the applicant.
Other features of the present invention have been described in the specification and in the secondary claims directly or indirectly dependent on the main claim.
The double-acting piston, operable 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 cylinder head to define with said piston a lower hot gas chamber, and whose other end is closed by an upper cylinder head to define with said piston an upper hot gas chamber, the transmission means being housed within a transmission housing to which the cylinder is fixed directly or indirectly, comprises according to the invention:
The double-acting piston according to the present invention comprises a thickness and a geometry of the radial traction disc as well as an axial position of the lower central clamping surface, of the upper central clamping surface, of the lower peripheral clamping surface, and of the upper peripheral clamping surface which are designed so that, when the clamping screw is tightened while mounting the double-acting piston, said disc is first compressed between the lower peripheral clamping surface and the upper peripheral clamping surface before being 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 traction radial stop relative to the lower radial limit stop and/or the upper radial limit stop which is provided so that, when the clamping screw is tightened at mounting the double-acting piston, said lower and/or upper radial limit stop comes into contact with the traction radial 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 having in its periphery a ring groove which can accommodate sealing means.
The double-acting piston according to the present invention comprises a ring groove which is housed in a groove of groove that is commonly constituted by a lower overhang included at the periphery of the lower half-piston, and an upper overhang included at the periphery of the upper half-piston.
The double-acting piston according to the present invention comprises at least one air supply radial duct which is arranged in the thickness of the radial traction disc, said duct connecting the screw through-hole 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 duct groove which constitutes the air supply radial duct when said two half-discs are pressed against each other as a result of 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 cap which is always immersed in a pressure chamber filled with compressed air regardless of the position of the double-acting piston in the cylinder, said chamber being integral or not to the upper cylinder head and being connected to a pressurized air source from which the compressed air originates, while said end has at least one air supply channel that connects the upper clamp screw shaft with 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 on the flat end of the upper piston rod which is furthest from the piston upper cap, or on at least one of the faces of a screw thrust washer on which the clamping screw rests.
The double-acting piston according to the present invention comprises a screw cooling tube which surrounds the clamping screw on all or part of its length, compressed air coming from the pressurized air source being able to flow into a space left between the inner wall of said tube and the outer surface of the clamping screw, while the greatest possible portion of the outer surface of said tube does not touch the internal wall of the upper clamping screw bore so as to define a vacuum space with the latter wall.
The double-acting piston according to the present invention comprises a screw cooling tube having a tube flange held clamped 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 to, or slightly greater than that of the upper clamping screw bore or the lower clamping screw bore in which it is housed.
The double-acting piston according to the present invention comprises a screw cooling tube which includes at least one tube diameter restriction consisting of an axial portion of said tube whose diameter is substantially equivalent to, or slightly smaller than that of the body of the clamping screw.
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 penetrate into said tube, or to escape from it.
The double-acting piston according to the present invention comprises a lower rod orifice and/or upper rod orifice which cooperate with—or which comprise—rod sealing means which create a seal between the lower piston rod and the lower cylinder head and/or between the upper piston rod and the upper cylinder head.
The double-acting piston according to the present invention includes rod sealing means which comprise an upper rod seal and a lower rod seal sufficiently distant from each other to form—between said two seals—a chamber for circulating oil into which leads a duct for supplying cooling-lubrication oil, and out of which leads an outlet duct of cooling-lubricating oil.
The double-acting piston according to the present invention includes rod sealing means rod which cooperate with a rod guiding ring housed inside or outside the oil flow chamber.
The description that follows in addition to the drawings, annexed and given by way of non-limiting examples, will allow a better understanding of the invention, its characteristics, and the advantages that it can likely provide:
As shown in
In this same
By way of non-represented variant, the transmission means 8 may consist of a cam, a transmitting hydraulic pump, a power generator or any other known transmission means to those skilled in the art.
It should also be noted—as shown in particular in
It should be noted that the lower relief recess 25 may be compartmentalized and/or reinforced with ribs. Furthermore, the lower piston cap 15 and the lower piston rod 17 may be made in a single piece of a material which maintains high mechanical strength at high temperature such as alumina, silicon carbide or zirconium oxide.
It should be noted that, advantageously, the lower central pillar 23 may be made from the same piece of material as the lower half-piston 13, or be attached to it.
The double-acting piston 1 according to the invention also comprises at least one lower radial limit stop 35 fitted in the lower half-piston 13 near the lower peripheral clamping surface 21.
In addition, as shown in
It can be seen in
It can be seen in
Moreover, the double-acting piston 1 according to the invention also comprises an upper clamping screw bore 28 arranged in the upper half-piston 14 at its center, and which passes through said half-piston 14 from one side to the other in an axial direction. Said shaft 28 is particularly visible in
Still in
Finally,
It should be noted that said ends may be made integral one with the transmission means 8 and the other with the upper piston rod 18 or the upper piston cap 16 by means of a clamping screw head 67, or a screw thread 68 that is included in the clamping screw 29, said thread 68 being screwed into a nut or a bore.
It should be further noted that the clamping of the clamping screw 29 results in tightening the radial traction disc 30 between the lower central clamping surface 19 and the upper central clamping surface 20, on the one hand, and between the lower peripheral clamping surface 21 and the upper peripheral clamping surface 22, on the other hand.
It should be noted that if the upper piston cap 16 is not prolonged by an upper piston rod 18, the head or the nut which terminates the clamping screw 29 and which holds said cap 16 tight may be housed in a cavity formed therein, said cavity being optionally closed by a plug.
In any case, the clamping screw 29 does not exclude the possibility of providing one or more other screws that together connect the lower piston cap 15 and the upper piston cap 16.
It should be ruled out either that the shape and/or curvature of the lower piston cap 15 be different from that of the upper piston cap 16, said caps 15, 16 also optionally comprising recesses or protuberances facing valves or dampers that the lower cylinder head 4 and/or the upper cylinder head 5 may respectively comprise.
It should be noted that according to a particular embodiment of the double-acting piston 1 according to the invention, 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, of the lower peripheral clamping surface 21, and the upper peripheral clamping surface 22 may be provided so that, when the clamping screw 29 is tightened while mounting the double-acting piston 1, 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 from this arrangement that the lower piston cap 15 and the upper piston cap 16 are placed under prestress which ensures the clamping of the radial traction disc 30 when the double-acting piston 1 is deformed 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 traction stop 34 relative to that of the lower radial limit stop 35 and/or the upper radial limit stop 36 may be provided so that when the clamping screw 29 is tightened while mounting the double-acting piston 1, said lower radial limit stop 35 and/or upper 36 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.
It follows from this arrangement that the lower piston cap 15 and the upper piston cap 16 each creates two arches which oppose a high mechanical resistance to the forces produced by the pressure in the lower hot gas chamber 6 and/or in the upper hot gas chamber 7. The first baseplate of the arches that is constituted by the lower piston cap 15 is secured at the lower central pillar 23 while the second baseplate of said arches is secured at the lower radial lower limit stop 35. The same is true for the upper piston cap 16 which forms two arches whose baseplates are respectively secured at the upper central pillar 24 and at the upper radial limit stop 36.
According to this particular configuration, a heat insulating space may advantageously be left between the radial traction disc 30 at the ring groove 39 and the groove of groove 42, said space constituting a thermal barrier.
It is noted in
It should also be noted that the cavities formed by the lower relief recess 25 and the upper relief recess 26 may be pressurized by the compressed air 54 that feeds the perforated continuous ring 41 or that feeds any other sealing means 40 requiring said compressed air 54.
It should be noted in
It should be noted that said chamber 49 may be integral or not with the upper cylinder head 5 and be connected to a pressurized air source 50 from which compressed air 54 is supplied, while the end of the upper piston rod 18 has at least one air supply channel 48 which connects the upper clamping screw bore 28 to the pressure chamber 49 so as, for example, to cooperate in the supply of compressed air 54 to a perforated continuous ring 41 with air cushion, similar or identical to that described in the French patent applications No. 1,550,762 and No. 1,551,593 belonging to the applicant, and allowing the production of a transfer-expansion and regenerative heat engine.
Alternatively, the pressure chamber 49 may be connected to the lower clamping screw bore 27, an air supply channel connecting said well 27 to said chamber 49. In this case, the chamber 49 may be formed, for example, by the volume swept by a butt 12, which is sealed so as to be connected to the pressurized air source 50.
It should be noted that—irrespective of the selected configuration—the pressurized air source 50 may include an air compressor which forces the compressed air 54 to flow into the upper clamping screw bore 28 or the lower clamping screw bore 27, said compressor being able to continue running for some time after stopping the heat machine to which is applied the double-acting piston 1 according to the invention. This last configuration all, for example, removing the heat that said piston 1 is likely to continue transmitting during cooling to the clamping screw 29.
It may be specified here that the air supply channel 48 may optionally be composed of at least one radial groove arranged either on the flat end of the upper piston rod 18 which is furthest from the upper piston cap 16, or on at least one of the faces of a screw thrust washer on which rests the clamping screw 29.
As shown in
It should be noted that according to the chosen embodiment of the double-acting piston 1 according to the invention, the screw cooling tube 53 may descend to the level of the lower clamping screw bore 27.
As can be seen in
In addition, the screw cooling tube 53 may also include at least one tube bulge 56 consisting of an axial portion of said tube 53 whose diameter is substantially equivalent to or slightly larger than that of the upper clamping screw bore 28 or the lower clamping screw bore 27 in which it is housed, this ensuring that said tube 53 remains locally centered in said shaft 28 or 27, and, if necessary, forming a seal between said tube 53 and said shaft 28 or 27.
It should also be noted in
In
It should be noted in
Specifically,
It should be noted that the oil flow chamber 62 performs the double function of lubricating and cooling the lower piston rod 17 and/or the upper piston rod 18. It is further noted that the upper rod seal 60 and/or the lower rod seal 61 may be composed in particular of a cutting segment or two superposed cutting segments and whose sections are angularly offset while the outer surface of the lower piston rod 17 and/or upper piston rod 18 may be provided with double helix shallow cuts which form a succession of oil reservoirs and hydrodynamic lift surfaces.
It is noted in
Also, according to a particular embodiment of the double-acting piston 1 of the invention, all or part of the space left between the clamping screw 29 and the inner wall of the lower clamping screw bore 27 and/or the upper clamping screw bore 28 may be filled with sodium, lithium salts or potassium salts to indirectly promote cooling of the lower piston rod 17 and/or the upper piston rod 18 by the oil flow chamber 62.
As illustrated in
Said ring 66 can provide radial guidance of the lower piston rod 17 in the lower cylinder head 4 and/or the upper piston rod 18 in the upper cylinder head 5.
It should be noted, moreover, that if—as illustrated in
The operation of the double-acting piston 1 according to the invention is easily understood when observing
To detail the said operation, we will assume here that said double-acting piston 1 is applied to the transfer-expansion and regenerative heat engine for which the French patent applications No. 1,550,762 and No. 1,551,593 are owned by the applicant. This application only serves as an example and does not exclude any other use of the double-acting piston 1 of the invention.
As particularly apparent in
It is noted that cylinder 2 is attached to the transmission case 3 that houses the transmission means 8 to which the double-acting piston 1 is connected. Said means 8 are provided for transforming the back and forth movements carried out by the double-acting piston 1 in the cylinder 2, into the continuous rotary motion of a crankshaft 11. To this end, and still according to this non-limiting example, said means 8 consist of a rod 9 connected to the double-acting piston 1 by a butt 12, said rod 9 being hinged around a crank 10 fitted on the crankshaft 11.
It is noted that in the transfer-expansion and regenerative heat engine chosen here as an example of application, it is necessary to provide sealing means 40 similar to those described in the French patent application No. 1,550,762 and No. 1,551,593 and belonging to the applicant.
As such, and as shown in
This configuration effectively allows providing a ring groove 39, itself assembled, which enables mounting the perforated continuous ring 41. In addition, said configuration allows providing a lower relief recess 25 in the lower half-piston 13 and an upper relief recess 26 in the upper half-piston 14.
It is noted that in order for the double-acting piston 1 of the invention to be as light as possible, it is imperative to seek its 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 exemplary non-limiting embodiment chosen here to illustrate the operation—provides that the lower piston cap 15 and the upper piston cap 16 each constitute two low thickness arches, respectively with the lower relief recess 25 and with the upper relief recess 26.
In order for an arch to be rigid, it is necessary that its two baseplates be securely anchored. This is a prerequisite so that said arch can retransmit the load to which it is subjected to said baseplates. Thus, as is clearly seen in
Let us 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, of the upper central clamping surface 20, of the lower peripheral clamping surface 21, and the upper peripheral clamping surface 22 are provided so that when the clamping screw 29 is tightened while mounting the double-acting piston 1, 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 does result from this arrangement that the lower piston cap 15 and the upper piston cap 16 are deformed and are placed under prestress which ensures, on the one hand, the clamping of the radial traction disc 30 at its peripheral zone 33 when the double-acting piston 1 is deformed under the effect of the pressure in the lower hot gas chamber 6 or in the upper hot gas chamber 7, and which ensures, on the other hand, that the lower radial limit stop 35 and the upper radial limit stop 36 each bear against the radial traction stop 34 with which they cooperate.
As seen in
The clamping screw 29, seen in
To do this, we note that the clamping screw 29 is only in direct contact with parts kept at low temperature. For example, said screw 29 has a clamping screw head 67 which remains in contact with the end of the upper piston rod 18 which is always immersed in the pressure chamber 49 maintained at low temperature regardless of the position of the piston double-acting 1. Further, said screw 29 has a screw thread 68 screwed into the butt 12 which is also maintained at low temperature.
It is noted that the body of the clamping screw 29 is in contact neither with the inner wall of the lower clamping screw bore 27, nor with that of the upper clamping screw bore 28, nor with the screw through-hole 31. The air being a powerful thermal insulation, this arrangement limits drastically any heat transfer from the lower half-piston 13 and the upper half-piston 14 towards the body of the clamping screw 29.
In addition, cooling of the body of the clamping screw 29 by the air coming from the pressure chamber 49 and going to the perforated continuous ring 41 should be noted, said air passing through the screw cooling tube 53. Indeed, this air, maintained at a moderate temperature of the order of one hundred degrees or even less, enters said tube 53 through the air supply channels 48 that are included—according to the embodiment shown in
It should be noted—particularly in
The inset of
It can be seen therein that the lower overhang 43 and the upper overhang 44 form together a groove of groove 42 which leaves an air gap between them and the radial traction disc 30 at the ring 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.
Still in reference to
When the transfer-expansion and regenerative heat engine, chosen here as an example of application, stops, it is noted that the oil pump that supplies the oil flow chambers 62 continues to supply oil to the latter to cool the lower piston rod 17 and the upper piston rod 18 and this, as long as the lower cylinder head 4 and the upper cylinder head 5 continue to transmit heat to said chambers 62 and risk bringing the oil contained in said chambers 62 to coking temperature.
The possibilities of the double-acting piston 1 according to the invention are not limited to the applications that have just been described and it must also be understood that the above description has been given only as an example and that it does not limit the scope of said invention, and that replacing the details of execution described by any other equivalent would not be considered as being outside said scope.
Number | Date | Country | |
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62218311 | Sep 2015 | US |