FR3067386B1 - RELAXATION MACHINE - Google Patents

Abstract

The present invention relates to a Rankine cycle piston expansion machine, comprising an outer body having an exhaust port and inside which are housed: a cylinder head (800) defining with said external body an admission zone high pressure of a working fluid under pressure, - an expansion zone comprising at least one cavity, in which a piston is movable to drive a driving shaft (1), characterized in that said outer body is formed of two hollow parts (100, 200) only, - a casing (100) on the one hand having a passage for said drive shaft (1) and - a cylinder head cover (200) on the other hand, forming a complementary sealed hollow envelope, having an inlet (20) - said yoke (800) being housed at least partially within said cylinder head cover (200) - the housing (100) and the cylinder head cover (200) being joined by surfaces join (101, 2 01) located outside said high-pressure inlet zone.

Description

RELAXATION MACHINE

Field of the invention

The present invention relates to the field of piston expansion machines performing a conversion of the lost heat of the internal combustion engine in an organic Rankine cycle into mechanical energy that can be transferred to a shaft driving the internal combustion engine.

State of the art

The general principle of such relaxation machines is known in the prior art.

For example, the French patent application FR3031135 of the applicant is known.

This document describes an example of a piston axial expansion machine comprising: a pressurized steam inlet yoke comprising a steam inlet, an expansion zone comprising a plurality of cylinders, in which a piston sliding in each respective cylinder is connected to a shaft by an inclined plate, each piston being parallel to said shaft, - a plurality of stem valves disposed in the intake yoke allowing the admission of steam alternately in said cylinders, each valve being controlled by a cam arranged on the shaft, - a lifting mechanism of each valve cooperating with the cam, - a return mechanism of each valve.

Also known is German Patent Application DE 102010036917 describing an axial piston machine comprising a shaft and a set of closed cylinders and pistons for driving the shaft.

US patent application US2016245225 discloses another example of an external heat engine device operating on a Rankine cycle, and preferably an organic Rankine cycle. It comprises a cylinder block, an upper lid and a lower tray provided with sealing surfaces arranged to be joined together and to bear against complementary fitting covers, each sealing surface being supported by sealed against a single opposite sealing surface.

Disadvantages of prior art

The solutions of the prior art have a plurality of sealing surfaces between the different parts of the machine. Some of these sealing surfaces insulate interior parts subjected to high temperatures, of the order of 200 to 250 ° C, with aggressive fluids such as gas phase ethanol, at high pressures, order of 20 to 40 bars.

These contexts require very elaborate and expensive joints, making it possible to withstand these operating conditions in the long term without degrading.

In case of leakage, the risks are very high because of the flammable nature of the working fluid.

In the solutions of the prior art, the outer casing has at least two connection areas to be sealed, some of which communicate with areas where the working fluid circulates at high temperatures and pressures.

Solution provided by the invention

The present invention aims to overcome the drawbacks of the prior art by proposing a solution drastically reducing the number of joints, by a particular design of the body of the relaxation machine limited to two pieces only, with a connection zone located in an area where the working fluid circulates at an already cooled temperature and a limited pressure.

The present invention relates, in its most general sense, to a Rankine cycle piston-type expansion machine, comprising an outer body having an exhaust orifice and inside which are housed: a cylinder head defining with said outer body a zone of admittance of a pressurized working fluid, called "high-pressure admission zone", - an expansion zone comprising at least one cavity, in which a piston is movable to drive a motor shaft, characterized in that said outer body is formed of two hollow portions only, - a casing on the one hand, the bottom having a passage for said motor shaft and - a cylinder head cover on the other, forming a complementary sealed hollow envelope, having a hole d intake - said cylinder head being housed at least partially within said cylinder head cover - the crankcase and the cylinder head cover being assembled by complementary joining surfaces located outside of said high pressure inlet zone.

Advantageously, it comprises an elastomeric O-ring seal disposed between said complementary joining surfaces.

According to a preferred variant, said joining surfaces are placed at the exhaust of the expansion zone, to be cooled by the flow of exhaust fluid.

According to another variant, the machine comprises a flat seal sealing between a peripheral shoulder of the cylinder head, and a complementary peripheral surface provided on the cylinder head cover.

In a particular example, said flat gasket is made of expanded polytetrafluoroethylene.

Advantageously, said cylinder head comprises at least one intake valve having a radially movable part.

According to a variant, said cylinder head comprises at least one exhaust valve having a radially movable part.

According to another variant, said exhaust valves are arranged angularly between two adjacent cylinders, at the level of the expansion chamber

Preferably, said valves are actuated by lifting means placed on said motor shaft.

According to a preferred embodiment, at least one exhaust duct of the expansion zone has an outlet oriented so as to direct the flow of fluid towards said lifting means.

According to an advantageous variant, each piston body has a longitudinal groove each cooperating with a corresponding anti-rotation pin housed in a radial lateral bore formed in the inner side wall of the housing.

According to another variant, the head of each piston is surrounded by an annular skirt providing guiding relative to the liner of the cylinder head, the other end of the piston also having an annular guiding guide skirt for guiding with respect to the cavity formed in the housing, the piston guide being provided on both sides of the plate.

Advantageously, the piston body is perforated to prevent compression.

According to a variant, a hollow volume formed between the front surface of the piston head (400) and the front surface of the piston body constitutes a thermal insulation zone.

According to another variant, the machine has a hollow space between the front surface of the piston head and the front surface of the piston body constitutes a thermal insulation zone.

Advantageously, said hollow volume has a bore opening in the exhaust zone to allow the evacuation of the liquid phase of the working fluid.

Advantageously, said hollow volume has a bore opening in the exhaust zone to allow the evacuation of the liquid phase of the working fluid.

According to another variant, at least part of the fixed parts of said machine is made of cast iron or steel, with application of a treatment of internal and external surfaces by nitriding in a salt bath followed by an oxidation phase.

According to an advantageous embodiment, the inner part of the housing has a plurality of longitudinally oriented bosses placed in the oil-laden vapor circulation circuit coming from the cylinder head via the lights, said bosses being arranged to partially stop the circular trajectory of the particles. oil arriving at the surface of the housing, and guide them towards the bottom of the housing.

Preferably, the bottom of the housing has conduits for lubricating the seal, the bearing and the stop with the oil recovered on the bottom and by the body of the pistons.

According to another variant, said conduits open on one side into cavities guiding the bodies of the pistons, and on the other side in a lubrication zone surrounding the shaft.

Detailed Description of a Non-Limiting Example of the Invention

The present invention will be better understood on reading the detailed description of a nonlimiting example of the invention which follows, with reference to the appended drawings in which: FIG. 1 represents an exploded view of an expansion machine according to FIG. invention. FIG. 2 represents an internal perspective view of the casing; FIG. 3 represents a longitudinal sectional view of the machine; FIGS. 4 and 5 show perspective views of the cylinder head respectively from outside and inside; FIG. is an inside perspective view of the cylinder head cover - FIGS. 7 and 8 show respectively a perspective view of the distribution, without the cylinder head and a partial sectional view; FIG. 9 is a cross-sectional view of a valve of FIG. Fig. 10 shows a cross-sectional view of an intake valve - Fig. 11 shows the valve lift laws.

General principle of a relaxation machine

An expansion machine, within the meaning of the present invention, produces a rotary mechanical movement by transforming the energy from a working fluid under pressure.

The transformation is carried out in an expansion chamber or several expansion chambers forming an expansion zone, supplied with working fluid in lubricant-laden vapor form, coming from the high-pressure admission zone and discharged through a zone. exhaust. The pressurized fluid comprises a main component such as ethanol, providing the thermodynamic cycle, charged with a liquid lubricant sprayed into the vapor phase of the main component. The lubricant is of the polyalkylene glycol (PAG) type miscible in the liquid phase with the other components. The proportion of lubricant is typically between 1 and 20% by weight.

This working fluid may further comprise components such as water, in a proportion of between 0 and 20% by weight and optionally additives for denaturing ethanol, for example of the-denaturant (trade name). , or an alkane, or a ketone in proportions of between 1 and 10% by weight.

In nominal operation, the expansion machine operates according to the general principle of the relaxation step of a Rankine or Hirn cycle.

The problem addressed by this patent relates to the sealing of the expansion machine inside which circulates a flammable working fluid, in the gas phase, at high pressure, high temperature (about 200 to 250 ° C).

Such machines are installed on motor vehicles involving drastic safety requirements.

General architecture of the machine according to the invention

Figure 1 shows an exploded view of an expansion machine according to an example of the invention.

It has an outer body formed of two complementary hollow parts: - a housing (100) - a cylinder head cover (200).

These two complementary parts (100, 200) each have a peripheral flange (101, 201) complementary, to allow a tight connection by bolting. The movable hitch (300) is integrally enclosed in the volume defined by the housing (100) and the cylinder head cover (200).

The housing (100) surrounds the area of the expansion machine that extends from the bottom dead end to the outlet of the shaft (1). This zone includes in particular the inclined plate (2) which transforms the reciprocating movement of the three pistons (400, 500) into rotary movement of the shaft (1).

The cylinder head cover (200) surrounds the zone of the expansion machine which extends from the steam inlet in the cylinder head to the exhaust ports (38) provided at the bottom dead center. This is the hottest part of the expansion machine. The movable hitch (300) comprises the shaft (1) and the members that are attached thereto: - the inclined plate (2) - the three pistons, two of which are shown in FIG. 1 (400, 500) - the three pairs of semi-spherical shoes (412, 413) ensuring the transmission of forces between the pistons (400, 500) and the inclined plate (2) - the cams (5, 6) activating the steam distribution - the bearings, for example needle or roller bearings, and optionally an oil pump (34).

In operation, the steam enters the cylinder head (800) at a temperature below 250 ° C generally between 180 ° C and 235 ° C. This steam is loaded with lubricant.

The lubricant travels in a known manner the entire Rankine circuit, driven by the working fluid.

This working fluid is for example composed of an ethanol / water mixture. The percentage of water is between 0 to 20% by weight, preferably 4.5% of the mass (azeotrope). To this mixture is added a denaturant, for example an alkane or a ketone or ofeurodenaturant (standardized mixture) between 1% by mass and more (euro-denaturing 7% by volume) to which polyalkylene lubricant is added. glycol (PAG) miscible between 1 and 20% by weight, usually about 10%.

The steam arrives through an inlet fitting (20) provided on the cylinder head cover (200) and, in the example described, exits on the opposite side by an exhaust flange (33) provided on the housing (100).

The steam circulates in the cylinder head (800) to actuate the pistons (400, 500) as will be presented in more detail in the following description.

Detailed description of the housing

Figures 2 and 3 show an internal perspective view of the housing and a longitudinal sectional view of the machine.

In the example described, the casing (100) is made of cast iron, in particular a cast iron of lamellar graphite type resistant to ethanol.

The part is made by casting in a mold and machining of the various orifices and cavities, then is subjected to a nitriding surface treatment in a salt bath followed by an oxidation phase.

The bottom (102) has three cylindrical cavities (103 to 105) closed on one side only for guiding the three bodies (401, 501) of the three pistons (400, 500). These cylindrical cavities (103 to 105) have an inner section complementary to the outer section of the three piston bodies (401, 501).

The depth of these cavities (103 to 105) is slightly greater than the stroke of the pistons (400, 500), the difference between the depth and the stroke being less than 5 millimeters, to avoid the compression of oil or vapor and of take into account the molding tolerances.

These three cavities (103 to 105) each have, on their side wall, a first radial lateral piercing (106) in which is inserted a pin (109) of antirotation of the piston bodies (401, 501). These piston bodies (401, 501) have for this purpose a complementary groove (402, 502) visible in FIG.

These first lateral holes (106) are inclined relative to the axis of the shaft (1) by an angle of between 35 and 55 °, preferably 45 °, towards the cylinder head.

These three cavities (103 to 105) each have, on their lateral wall, a second radial lateral bore (112 to 114) inclined relative to the axis of the shaft (1) in the direction opposite to the cylinder head of a angle between 0 ° and 60 °, and opening into the central cavity (118).

These second bores (112 to 114) constitute oil supply conduits for the shaft end seal (115) as well as the bearing (116) and the axial abutment (117).

The bottom (102) further has a central shaft outlet (118) whose inner tubular surface is machined to receive the bearing (116) and the axial stop (117), the shaft end seal (115) and optionally a second shaft end seal (119). The annular space (120) between the seals (115, 119) constitutes a vent chamber to prevent contamination by the working fluid contained in the machine from inside the combustion engine on which is mounted the relaxation machine.

This chamber (120) is pierced by a vent (32) opening on the outside, in the lower part of the annular chamber, when the machine is mounted on a motor, to allow the evacuation of any leaks of working fluid. , or engine oil.

The seals (115, 119) are annular lip seals, the lips being oriented in opposite directions to the chamber (120) to promote the sealing of the machine with respect to the working fluid on the one hand and the tightness of the motor compared to the engine oil on the other hand. Thus, the chamber (120) forms a volume for recovering fluids coming from the machine or the motor, to evacuate them to the outside, and to prevent the penetration of a fluid coming from the machine into the engine, and vice versa .

The seal (115) is made of polytetrafluoroethylene (PTFE), for example a lip seal sold under the reference BEKA 804 or BEKA 806 by the company FranceJoint (trade names).

The housing (100) has on an side wall an exhaust port (33) surrounded by a flange (121) forming an annular receiving surface for receiving a seal.

Two threads (122, 123) allow to receive screws for fixing a flange of an exhaust duct. This flange (121) is located in the lower lower half of the expansion machine when it is mounted on the internal combustion engine. Its exact position is determined by the engine, to facilitate connection to the Rankine cycle condenser.

The inner portion of the casing (100) also has a plurality of semi-cylindrical bosses (124, 125, 126) oriented longitudinally, receiving a tapping for fixing the cylinder head (800).

These bosses (124, 125, 126) are placed in the oil-laden vapor circulation circuit from the cylinder head via the slots (38, 39). This vapor circulates with a rotating component, printed by the rotation of the inclined plate (2). This movement leads to a centrifugal force tending to drive the oil particles to the inner wall of the housing. The bosses (124, 125, 126) partially stop the circular path of the oil particles arriving at the surface of the housing, and guide them towards the bottom (102) of the housing (100). The oil recovered on the bottom (102) thus feeds the cavities (103 to 105), and flows through the conduits (112 to 114) to lubricate in particular the piston guides (401) and the grooves (402, 502,) the seal (115), the bearing (116) and the stop (117).

It should be noted that the body of the pistons (401, 501) plays a similar role of collecting oil, being interposed on the circular path of the oil particles, and guiding a portion of the collected oil towards the cavities (103). at 105).

The flange (101) surrounds the housing (100) to form a transverse surface for receiving a seal (130).

This surface has threads distributed over the periphery to receive the screws for fixing with the cylinder head cover (200), having a flange (201) complementary.

The seal (130) is a fluoroelastomer O-ring, for example VITON (trade name) or EPDM (ethylene-propylene-diene monomer).

The joint area between the housing (100) and the cylinder head cover (200) lies in the area of the machine where the plate (2) is located, and in which the vapor is escaped by the exhaust ports (38). ). This is a low-pressure zone at low temperatures relative to the rest of the machine, allowing the use of inexpensive elastomeric seals rather than high temperature resistant seals.

Alternatively, the seal may be deposited not on the transverse surface of the flange (101), but surround a tubular surface (assembly called "piston").

The outer surface of the bottom (102) has fastening means on the internal combustion engine, for example at a power take-off and in particular the rear power take-off, provided on the internal combustion engine. The shaft (1) has means for coupling to the motor, for example a combination of the following elements: freewheel, clutch, vibration damper, gear, pulley.

The inner surface of the peripheral skirt of the casing has housings (131, 132, 133) for positioning sensors, for example temperature, pressure or plateau position sensors.

Detailed description of the piston guide

Figure 3 illustrates the guidance of the pistons. The shape of the piston illustrated in Figure 3 differs from that illustrated in Figure 1, corresponding to an alternative embodiment with respect to this detail. The description will relate to a single piston (400), it being understood that the other pistons (500) are identical.

The piston (400) consists of two parts, namely the piston body (401) and the piston head (403), connected by a screw (404) or by any other known means, for example by hooping.

The head (403) is surrounded by a sealing segment (405), for example cast iron.

The body (401) is surmounted, on the side of the head (403), an annular ring (406).

This annular ring (406) provides guiding of the head and resumes the guide forces of the entire piston (400). It also defines a hollow space (407) between the front surface of the head (403) and the front surface of the body (401), constituting a zone of thermal insulation. This hollow volume (407) has a bore (420) opening into the exhaust zone to allow the evacuation of the liquid phase of the working fluid.

The head (403) is surrounded by an annular skirt (408) providing guiding relative to the liner (409) of the yoke (800). The other end of the piston (400) also has an annular guide skirt (410) defining an open cavity (411) for preventing vapor compression between the piston body (401) and the bottom of the cavity (103). ) of the housing (100). The open section represents about 60% of the cross section of the body (401).

The guide of the piston is thus ensured on both sides of the plate (2) allowing a reduction of the guiding forces but also making it possible to place the exhaust (33) as close as possible to the side of the intake (20). which facilitates the integration of the relaxation machine in a vehicle.

As already explained, the body (401) has a longitudinal groove (402) in which is slid the anti-rotation pin (109) integral with the housing (100).

The cooperation between the piston (400) and the plate (2) is provided in known manner by pads having a spherical cap shape (412, 413) disposed on either side of the plate.

The pads (412, 413) are made of 100Cr6 type steel (according to the designation proposed by the AFNOR EN 10027 standard).

The pad (412) located on the side of the piston head (403) is optionally subjected to an amorphous carbon type surface treatment called DLC ("diamond like carbon" in English).

The piston body (401) is made of forged steel or spheroidal graphite cast iron, then subjected to nitriding surface treatment in a salt bath followed by an oxidation phase. It can also be made of forged aluminum, followed by a surface treatment by anodic oxidation.

The piston head (403) is made of spheroidal graphite cast iron or steel, with the application of a nitriding surface treatment in a salt bath followed by an oxidation phase.

The plate (2) is made of spheroidal graphite iron, which is then surface-treated by nitriding in a bath of salts followed by an oxidation phase.

Alternatively, the plate is made of forged steel subjected to a treatment of the DLC type on at least its plane face on the side of the cylinders.

Detailed description of the cylinder head

Figures 4 and 5 show perspective views of the yoke respectively outside and inside.

The cylinder head (800) is made by molding a spheroidal graphite cast iron, machining and nitriding surface treatment in a salt bath with an additional oxidation step.

The yoke (800) has three cavities (414, 514, 614) in which are inserted the tubular sleeves (409, 509, 609) open at both ends. The cavities (414, 514, 614) are blind, each having two orifices, namely an oblong exhaust port (415, 515, 615) and an inlet port (416, 516, 616).

A flat seal (417) visible in FIG. 3 seals between the front surface of the liner (409) and the bottom of the cavity (414).

The jacket (409) has an annular groove (418) for defining, with the inner wall of the cavity (414) an annular space forming a thermal insulation. Optionally, this space can be traversed by a hot steam flow. For this purpose, the cavities (414, 514, 614) have a first series of lateral bores (419, 519, 619) and a second series of lateral bores not visible in the figures, arranged on both sides of the bores. a median longitudinal plane. Other holes (824, 825, 826) may be provided to allow gravity discharge of the oil which accumulates in the annular zone (418, 518, 618) of the cylinder head (800). For this purpose, the holes (824, 825, 826) are provided in the lower parts when the machine is mounted on the internal combustion engine.

The central bore (801) is for the passage of the shaft (1).

This passage (1) has a bearing area of a conical bearing (617) visible in FIG. 3.

The bottom (802) of the cylinder head (800) also has holes (803 to 805) for fixing the cylinder head (800) on the housing by screws penetrating into the threads provided in the bosses (124 to 126). . The orifice (806) constitutes the output of an internal bypass duct ensuring the purging of the stagnant liquid in the machine at standstill.

The bottom (802) also has three lights (807 to 809) for the passage of steam escaped by the exhaust ducts (415, 515 and 615). Near the orifice (806), the yoke (800) has a wall (810) extending radially in a longitudinal plane between the transverse end face (802) and the intermediate transverse plate (811). This wall (810) partitions the flow of steam in the bypass circuit which will be described in more detail in the following. It has a bore (822) for preventing the accumulation of oil in a part of the machine.

The intermediate transverse plate (811) is surrounded by a peripheral seal (812). This seal (812) is a flat gasket, expanded polytetrafluoroethylene whose thickness is between 1 and 4 millimeters.

This plate (811) is surmounted by an annular ring (813) having at its end a peripheral edge (814) surrounded by a seal (815). This seal (815) is also a flat gasket, expanded polytetrafluoroethylene whose thickness is between 1 and 4 millimeters. The annular space between the seals (812) and (815) constitutes the high-pressure zone connected to the inlet (20) and opening, via the inlet valves (11), into the expansion chambers delimited by the jackets (409, 509, 609), the bottom of the cavities (414, 514, 614) and the head of the pistons (403).

This annular space is sealed by the two flat seals (812 and 815) when the cylinder head cover (200) is brought axially and is positioned on the housing (100). The connection between the cylinder head cover (200) and the housing (100) is also sealed by the O-ring (130).

These simultaneous seals on different pitch planes are allowed due to the compressibility properties of expanded polytetrafluoroethylene and the judicious choice of the thickness of the flat seals (812, 815).

The annular ring (813) delimits, with a complementary inner wall (817), a thermal insulation chamber (816) of annular shape.

The inner wall (817) is pierced by three exhaust ducts (818 to 820) which are connected on one side to the exhaust port (415, 515, 615) and on the other side to lights ( 821) which are closable by the exhaust valves (12).

These exhaust ducts (818 to 82 0) are closed by the cylinder head cover (200) to form an exhaust duct between the expansion zones and the exhaust ports (821).

The intake valves (11) and the exhaust valves (12) are stem valves movable in substantially radial directions under the action of the cams (5, 6) on the shaft (1).

The exhaust valves (12) are arranged angularly between the pistons (400, 500) so as to optimize the axial space in particular by using the space available between two adjacent jackets.

The intake valve duct (11) connects the high pressure zone to the expansion zone via the orifice (416, 516, 616).

The wall (817) is pierced by at least one bore (823) having a diameter of less than 4 mm, which opens into the insulating zone (816) to prevent the accumulation of oil and to maintain the insulating zone (816) at low pressure.

The cylinder head has a bypass circuit from the high pressure zone via a bypass passage formed in the cylinder head cover (200) controlled by a valve (9).

This conduit opens into an area defined between the cylinder head cover (200), the intermediate plate (811) and the front plate (802). In operation in bypass mode, valve (9) open, the vapor flowing in this zone passes successively through the annular spaces (418), into which they enter through one of the orifices (419, 519, 619) and exit through the other opposite orifice.

The vapor then opens, after this circuit, into the orifice (806).

Detailed description of the cylinder head cover

Figure 6 shows an interior perspective view of the cylinder head cover.

In the example described, the cylinder head cover (200) is a hollow piece made of cast iron, in particular an ethanol resistant spheroidal graphite cast iron.

The part is made by casting in a mold and machining of the various orifices and cavities, then is subjected to a nitriding surface treatment in a salt bath followed by an oxidation phase.

The bottom (202) has a guide bearing (203) of the shaft (1), not traversing. The bottom (202) is surrounded by a peripheral skirt (204) having a flange (201) as previously mentioned.

The bottom (202) is extended by blades (205 to 207) erected perpendicularly to the bottom (202), in planes perpendicular to radial directions. The ends of these blades (205 to 207) have a curved surface (208 to 210) closing the exhaust ducts (818, 819, 820). The shape of this surface (208 to 210) is configured to reduce the volume of the exhaust duct (818, 819, 82 0) while limiting the pressure drops. The radius of curvature of this concave shape is adaptive to define a substantially constant exhaust section.

Ribs (212) provide stiffness of the bottom (202) to prevent deformations resulting from the vapor pressure.

The bottom (202) has two grooves (213, 214) in which are housed seals, to define the high pressure zone and the thermal insulation zone (816).

The lower surface of the cylinder head cover (200) further has a shoulder (215) peripheral forming a transverse bearing surface against which rests the transverse surface (811) of the cylinder head.

A seal (812) is disposed between these two surfaces.

The plate (215) is traversed by a hole (828) opening into a housing receiving the bypass valve (9). This valve (9) controls the opening or closing of an orifice (829) opening into the high-pressure zone. One and / or the other of these orifices (828, 829) has a restricted section having a section 4 to 12 times smaller than the inlet (20) to intentionally produce in operation in bypass mode ( for example for purging the liquid contained in the machine at a stop) adequate pressure drop.

The cylinder head cover (200) also includes the intake fitting (20).

In FIG. 1, the cylinder head cover (200) also comprises an optional oil pump (818), for example a trochoidal oil pump.

According to this option, the oil pump (34) is used for the circulation of oil, to lubricate the bearings, the abutment, the joints, the inclined plate and the cams, via radial bores on the shaft opening on a canal running longitudinally through the shaft (1). In this case, an external oil supply to the pump is provided.

Optionally, the inner surface of the cylinder head cover may also have housings for receiving one or more sensors such as instantaneous pressure sensors in the cylinders, pressure sensors of the high pressure zone, sensors for the oil pressure when There is an oil pump or temperature sensors.

Optionally the cylinder head cover (200) comprises a safety valve between the high-pressure zone and the bypass duct, this valve opening when the pressure difference of the steam between the high-pressure zone and the bypass duct exceeds a threshold value, for example 40 or 45 bar.

Detailed description of the distribution

Figures 7 and 8 respectively show a perspective view of the distribution, without the cylinder head and a partial sectional view. The shaft (1) has cams (5, 6) actuating the intake valves (11) and the exhaust valves (12).

The exhaust valves (12) are stem valves, of which Figure 9 is a cross-sectional view.

The movable portion of the valve (12) is constituted by a head (50) extended by a rod (51), itself extended by a cylindrical body (52) having a conical annular support zone (53) against the seat (827) itself having a mating bearing surface.

The head (50) comprises an adjusting pad (54) whose thickness is chosen to make up the manufacturing tolerances of the cams and the valve, and to guarantee a play of about 75 microns between the base radius of the cam and the valve in the closed position, where the annular surface (53) bears against the seat (827).

The cam (5), rotating with the shaft (1), sweeps a rectangular surface on the wafer (54). The diameter of said wafer (54) is therefore adapted so that this rectangular surface is inscribed in the surface of the wafer in order to avoid, in operation, the interruption of the film of oil between the cam (5) and the wafer (54) and thus control the wear of these parts.

The fixed portion of the valve (12) is constituted by a base (55) whose outer section is complementary to the inner section of the cylindrical body (53) to allow axial movement of said movable portion of the valve (12). A spring (56) is inserted in the cylindrical body (53), and abuts against the transverse bottom (57) of the cylindrical body (53) and against a shoulder (58) of the base (55). on the other hand. The base (55) has a duct (59) for exhausting gases accumulated inside the cylindrical body (53).

The exhaust valves (12) are radially introduced into the cylinder head (800) from an opening provided at the outer peripheral surface of the cylinder head. When in place, they are immobilized by a stop segment (60).

To adjust the valve, the movable portion of the valve (12) is first introduced until it abuts the seat (827).

The distance between the pellet (54) and the surface of the cam in the closed position is then determined. For this, is introduced between the surface of the cam and the wafer (54) a series of calibrated shims of different thicknesses.

The original chip is then replaced by a chip of suitable thickness to obtain a nominal clearance, for example 75 microns.

Alternatively, the movable portion may have a disc portion whose peripheral zone opposite the head constitutes the bearing surface on the seat, this disc portion being extended by a rod. In this case, the base has a tubular extension for guiding this rod. The spring surrounds this tubular extension and abuts on the one hand against the rear surface of the disc portion and on the other hand on a shoulder or on the base of the base.

The intake valves (11) are stem valves, of which Figure 10 is a cross-sectional view.

The valve guide (61) is shrunk into a radial through housing provided in the cylinder head. This valve guide (61) has a through bore for guiding the stem (62) of the valve.

This rod (62) has at its end a head (63) extended by a lug (64). The opposite end has a cup (65) encased on the valve stem (66). This cup (65) forms a bearing surface of a spring (67) whose other end abuts against the bottom (68) of the valve guide (61).

The valve (11) further comprises a pusher (69) of cylindrical shape, with flats (72) diametrically opposed. These flats (72) are perforated for the passage of a setting pad (70) positioned between the tail of the valve (66) and the pusher (69).

The pusher (69) is guided by the valve guide (61) within which it moves axially.

It is stopped in rotation by a key (71) disposed between the valve guide (61) and the pusher (69), or by the flat (72) coming into contact with the cylinder head (800) or the cylinder head cover (200). ) having for this purpose housings of complementary non-circular section.

The clearance adjustment is achieved with the valve in the closed position. The distance between the pusher (69) and the cam is measured with calibrated spacers, and the original pellet (70) is replaced by a pellet whose thickness makes it possible to reach the nominal clearance, for example 75 microns. The lug (64) is a gripping means for forcing the opening of the valve to allow the replacement of the adjustment pad (70). Alternatively the head (63) can be equipped with an axial tapping facilitating its grip and reducing its mass.

Detailed description of lubrication

The lubrication of the cams (5, 6) and the intake and exhaust valves (11, 12) and the tapered bearing (617) is provided by the oil-laden vapor from the exhaust duct (821), opening out near the cams (5, 6).

The oil-laden vapor from the exhaust ports (38) opens into the area where the inclined plate (2) is located, which ensures the lubrication of the plate and the semi-spherical pads (412, 413).

The lubrication of the inclined plate and semi-spherical pads is improved by a relative adjustment of the inner side wall of the housing (100) around the inclined plate and the pistons on the one hand, and by a favorable axial position of the orifice of exhaust (33) on the other hand. The exhaust port (33), preferably positioned beyond the median radial plane of the inclined plate with respect to the exhaust ports (38), thereby ensures that the oil-laden vapor continuously lubricates the platen. bypassing it in its path to the exhaust port, including during operating phases where the bypass circuit is activated.

As previously described, the lubrication of the bearing (116), abutment (117) and shaft end seal (115) is provided by the oil-laden vapor passing through the conduits (112, 113, 114).

The segments (405) and the skirt (408) of the piston head are lubricated by the oil-laden vapor from the expansion chamber.

The lubrication of the piston body guide (410) and the groove (402, 502) is provided by the oil-laden vapor from the exhaust ports (38) opening into the area where the inclined plate (2) is located. ), the oil then being conveyed along the bosses (124, 125, 126). The lubrication of the seat of the intake valve is ensured by the steam charged with oil coming from the inlet of the machine.

Laws of lift of the valves

Figure 11 shows the valve lift laws. The opening of the intake valve (theta7) starts a few degrees (between 25 ° and 5 °, and preferably 15 ° to 20 °) before the top dead point (theta) and ends (theta) between 55 ° and 100 °, and preferably 65 ° to 70 ° after the top dead center.

The exhaust ports are discovered by the piston (theta2) a few degrees (between 40 ° and 20 °, and preferably between 30 ° and 35 °) before the bottom dead center (theta4), symmetrically with respect to the neutral position low (theta4). The exhaust valve opens substantially concomitantly (theta3) with the release of the exhaust ports and close substantially concomitantly (theta6) with the opening of the intake valve (theta7).

Claims (17)

claims 1 - Rankine cycle piston relaxation machine, comprising an outer body having an exhaust port and inside which are housed: - a cylinder head (800) defining with said outer body a high-pressure inlet zone a working fluid under pressure, - an expansion zone comprising at least one cavity (414, 514, 614), in which a piston (400, 500, 600) is movable to drive a motor shaft (1), characterized in that said outer body is formed of two hollow portions (100, 200) only, - a casing (100) on the one hand having a passage for said motor shaft (1) and - a cylinder head cover (200) d on the other hand, forming a complementary sealed hollow envelope, having an inlet (20) - said cylinder head (800) being housed at least partially inside said cylinder head cover (200) - the housing (100) and the cylinder head cover (200) being joined by joining surfaces (101, 201) complementing located outside of said high-pressure inlet zone. 2 - piston reclining machine according to claim 1 characterized in that it comprises an O-ring seal (130) of elastomer disposed between said complementary joining surfaces (101, 201). 3 - piston reclining machine according to claim 1 characterized in that said joining surfaces (101, 201) are placed at the exhaust of the expansion zone, to be cooled by the flow of exhaust fluid . 4 - piston reclining machine according to claim 1 characterized in that it comprises a flat seal (812) sealing between a peripheral shoulder of the cylinder head, and a complementary peripheral surface provided on the cylinder head cover. 5 - piston reclining machine according to claim 4 characterized in that said flat gasket (812) is made of expanded polytetrafluoroethylene. 6 - piston reclining machine according to claim 1 characterized in that said yoke comprises at least one inlet valve (11) having a radially movable portion. 7 - piston reclining machine according to claim 1 characterized in that said cylinder head comprises at least one exhaust valve (12) having a radially movable portion. 8 - piston reclining machine according to claim 7 characterized in that said exhaust valves (12) are arranged angularly between two adjacent cylinders at the expansion chamber 9 - piston reclining machine according to any one of claims 6 to 8 characterized in that said valves (11, 12) are actuated by lifting means (5, 6) placed on said motor shaft (1). 10 - piston reclining machine according to the preceding claim characterized in that at least one exhaust duct (818, 819, 820) of the expansion zone has an outlet (821) oriented to direct the flow of fluid to said lifting means (5, 6). 11 - piston reclining machine according to claim 1 characterized in that each piston body (401, 501) has a longitudinal groove (402, 502) each cooperating with a pin (109) corresponding anti-rotation housed in a radial side piercing (106) formed in the inner sidewall of the housing (100). 12 - piston reclining machine according to claim 1 characterized in that the head (403) of each piston is surrounded by an annular skirt (408) providing guiding relative to the sleeve (409) of the cylinder head (800), the other end of the piston (400) also having an annular skirt (410) providing guiding relative to the cavity (104) formed in the housing (100), the guiding of the piston being provided on both sides of the plate (2). 13 - Piston relaxation machine according to the preceding claim characterized in that the body (401) has an open cavity (411). 14 - piston reclining machine according to claim 1 characterized in that at least a portion of the parts of said machine is made of cast iron or steel, with application of a treatment of internal and external surfaces by nitriding in a bath of salts followed by an oxidation phase. 15 - piston reclining machine according to claim 1 characterized in that the inner portion of the housing (100) has a plurality of bosses (124, 125, 126) oriented longitudinally, placed in the vapor circulation circuit loaded with oil from the cylinder head via lümières (38, 39) arranged to partially stop the circular path of the oil particles arriving at the surface of the housing, and guide them towards the bottom (102) of the housing (100). 16 - piston reciprocating machine according to the preceding claim characterized in that the bottom (102) of the housing (100) has ducts (112 to 114) for lubricating a seal (115), a bearing (116), a stop ( 117) and annular skirts (410) with the oil recovered on the bottom (102). 17 - Piston relaxation machine according to the preceding claim characterized in that said conduits (112 to 114) open on one side in cavities (103 to 105) ensuring the guiding bodies (401, 501) of the pistons (400, 500), and on the other side in a lubrication area surrounding the shaft (1).