EP3638887A1

EP3638887A1 - Expansion machine and methods for using such a machine

Info

Publication number: EP3638887A1
Application number: EP18726521.0A
Authority: EP
Inventors: Rémi DACCORD; Antoine Debaise; St phane WATTS; Xavier Durand
Original assignee: Exoes SAS
Current assignee: Exoes SAS
Priority date: 2017-06-13
Filing date: 2018-04-27
Publication date: 2020-04-22
Also published as: FR3067385B1; FR3067439A1; WO2018229404A1; FR3067385A1; WO2018229368A1; EP3638888A1

Abstract

The present invention relates to an expansion machine (0) comprising an inlet region (22) having an intake port for a pressurised working fluid, the fluid being made up of a main component in the gaseous phase under nominal operating conditions, filled with a lubricant component in the liquid phase. The high pressure area is made up of the inlet region (22) fed directly by the pressurised working fluid. The bypass circuit is in contact with the expansion area for transferring heat between the working fluid flowing in the bypass circuit and the working fluid contained in the expansion area, to form a pre-heating means (15). The inlet region (22) has: o at least a first internal opening emerging into an expansion area and o a second internal opening emerging into the bypass circuit, controlled by the valve (9).

Description

MACHINE FOR RELAXATION AND

METHODS OF USING SUCH A MACHINE

Field of the invention

The present invention relates to the field of expansion machines for the recovery of thermal energy from hot fluid for the transformation into mechanical or electrical energy.

According to a preferred field of invention, the invention relates to a system for recovering thermal energy from an engine such as an internal combustion engine, and finds a particular application in the field of transport.

State of the art

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

In particular, the European patent application

EP3128137 discloses an assembly for controlling a flow of working fluid in the gas phase between its source and the admission of a flashing machine.

The purpose of this solution of the prior art is to prevent the penetration of the working fluid in liquid form into the machine, by reducing the pressure when the temperature of the fluid supplying the machine is too low. Another goal is to limit the pressure when it is excessive. For this, this solution provides a slide valve comprising several passages feeding on one side the cylinder head, on the other side the exhaust zone.

Also known in the prior art the international patent application WO 2015176142 vapor expansion device, said device comprising an expansion valve having an inlet which is connected to an intake pipe and a discharge which is connected to a discharge pipe, the intake pipe being provided with an intake valve and the discharge pipe being provided with an evacuation valve for isolating the space between the valves by closing these valves when the expander is not in operation, the device being provided with a steam supply which conditions the space between the valves when the expander is not in operation, so that the air can not penetrate the space.

In this document of the prior art, a referenced supply valve (18) is connected to a controller which controls the opening when the expander is taken out of service and reclosing when the expander is put back into operation. This supply valve is disposed on the steam supply circuit and not in the device

Disadvantages of prior art

The solution of the prior art does not ensure adequate heating of the branch downstream of the valve, between the valve and the cylinder head. This part of the expansion machine is heated only by thermal conduction. Solution provided by the invention

The present invention aims to overcome the disadvantages of the prior art to ensure optimum temperature setting of all parts of the heat machine, especially during the startup phase.

The invention also makes it possible to simplify the heating circuit, which makes it possible to reduce its bulk.

The object of the invention is to improve the operation of the machine in atypical operation modes of the expansion machine by a single and same means constituted by this valve actuating a shutter disposed in the machine. The atypical functions presented in the invention are the following:

a) machine temperature too low,

(b) overpressure at admission,

c) request to stop the machine,

d) overheating too low on admission and

e) Overheating too low in the exhaust.

To this end, the invention relates, in its most general sense, to an expansion machine according to claim 1, taken alone or in combination with one or more dependent claims.

The invention also relates to a thermal energy recovery system according to claim 1, taken alone or in combination with one or more dependent claims.

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 a schematic view of the solutions of the prior art

FIG. 2 represents a schematic view of the solution according to the invention

FIG. 3 represents a longitudinal sectional view of a first exemplary embodiment of a single piston expansion machine.

FIG. 4 represents an exploded view of an alternative embodiment of a three-piston expansion machine.

- Figure 5 shows a partial sectional view of a second embodiment of a three-piston expansion machine FIG. 6 represents a cross-sectional view of the second exemplary embodiment of a three-piston expansion machine.

Figures 7 and 8 show an exterior and interior isometric view of the cylinder head

Figure 9 shows a longitudinal sectional view of the expansion machine.

- Figure 10 shows a schematic view of a third embodiment of a spiral expansion machine.

Schematic presentation of the state of the art

FIG. 1 represents a schematic view of an expansion machine solution according to the prior art.

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 one or more expansion chambers forming an expansion zone, supplied with working fluid in vapor form filled with lubricant, coming from the high-pressure admission zone and discharged through an exhaust zone.

By convention, the term "zone of expansion" will be used to designate the zone comprising one or more expansion chambers with pistons, or a screw, or a spiral, ensuring the transformation of thermodynamic energy of thermal fluid into mechanical work.

The terms "expansion zone", "expansion chamber" or "expansion chambers" will subsequently be used interchangeably, the invention not specifically relating to the nature of the expansion zone but to its control thermal.

The terms "admission zone" or "admission chamber" will also be used interchangeably. 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, by mass, 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 Euro-denaturant (trade name). , or an alkane, or a ketone in proportions of between 1 and 10% by weight. The mixture of these liquids is monophasic, the different constituents mixing perfectly.

The composition of this working fluid is variable, but always contains a lubricant, whose degradation temperature is high and higher than the evaporation temperature of the other components.

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

When stopped, the working fluid fills the cavities of the expansion machine in the form of a liquid phase, without vapor phase, in order to avoid vacuum conditions with respect to atmospheric pressure which would lead in the long term to the penetration of air and therefore of oxygen in the circuit.

The transition from this last situation to a nominal mode of operation constitutes a critical transitional phase, since the nominal operation is incompatible with a situation where:

a) the expansion zone is filled with an exclusively liquid phase, b) the liquid phase present in the expansion machine is poor in lubricant. Indeed, in "hot" phase, the lubricant is the only component remaining in the liquid phase and thus ensures its lubricating function. On the other hand, in the "cold" phase, the other constituents are also in the liquid phase and thus dilute the lubricant, and very significantly reduce its lubricating capacity. Dilution is typically a factor of 5 to 100.

In the remainder of this description, "nominal operation" will be understood to mean the situation in which the machine is rotating, under the action of the working fluid in the gaseous phase under pressure injected into the expansion zone to cause the displacement of the pistons or the rotation of a screw or spiral.

Atypical functioning will be understood to mean special and transient situations:

a) the step of starting the machine from stopping to moving

b) the step of stopping the machine running contrary to the nominal operation at standstill

(c) improper operating fluid temperature and pressure conditions with nominal operation.

The invention relates to controlling these three atypical operating modes of the expansion machine by one and the same means:

a) the start-up phase of such an expansion machine, requiring a purge of the working fluid in the liquid phase contained in the cavities of the machine, in particular in the expansion zone, and a lubrication of the internal movable members. When stopped, the chambers of the expansion machine are filled with liquid, namely the working fluid in the liquid phase consisting of a mixture of water (optionally) ethanol, a denaturant and a lubricant. The composition of this working fluid is variable, but always contains a lubricant, whose degradation temperature is high and higher than the evaporation temperature of the other components.

This liquid is incompressible, and prevents the normal movement of the pistons. Furthermore, this liquid is low in lubricant, the lubricant is highly diluted, and the machine start would be in conditions of friction and wear unfavorable.

The liquid mixture is monophasic, the different constituents mixing perfectly. In order to concentrate the "lubricant" component, it is necessary to evaporate the other components (water, ethanol and denaturant) by heating to a temperature above the evaporation temperature of these other three components, and below decomposition temperature of the lubricant.

This heating should preferably occur in the areas closest to the expansion zone in order to promote the evacuation of the water, ethanol and denaturant components, and to promote the deposition of the lubricant on the surface of the expansion zone, after separation due to heating.

It would be very detrimental to start the expansion machine before having purged the liquid and deposited a film of oil on the moving parts. The first function of the solution proposed by the invention is therefore to improve the heating as close as possible to the zone of expansion of the liquid y stagnant before starting. stop of the expansion machine: when it is desired to stop the expansion machine before the natural shutdown resulting from the ratio of the inlet pressure to the exhaust pressure below a threshold value, the means allows to lower the intake pressure and thereby lower this ratio. This threshold value is for example a ratio of 5.

Alternatively it may be desirable to cancel the production of mechanical work of the expansion machine (especially in case of stopping the vehicle) without necessarily causing the stop of the rotation thereof, the means can reduce the ratio to a suitable value, especially if the 2-way valve is proportional or pulse-regulated

c) filtering the conditions of admission or exhaust of the working fluid outside their nominal range, for example in the event of pressure exceeding a threshold value or insufficient overheating. Insufficient superheating may correspond, for example, to a difference between the temperature of the working fluid and the saturation temperature at the pressure of the working fluid lower than a threshold value for a duration greater than a threshold duration. An insufficient superheat threshold value is for example 5 ° K for 30 seconds.)

In the prior art, it has been proposed to meet these three objectives by solutions illustrated schematically in Figure 1, with a three-way valve (90) external to the expansion machine (0). This three-way valve (90) is placed between the inlet (21) of the working fluid and the inlet (20) of the expansion machine (0).

This valve (90) controls, according to its position:

a) the direct transmission of the working fluid from the inlet (21) to the inlet (20) opening into the inlet zone (22) of the expansion machine (0). b) the transmission of all or part of the working fluid from the inlet (21) to a heating means (15).

This configuration does not allow to properly and quickly empty the branch (23) between the valve (90) and the high-pressure inlet zone (22) of the expansion machine (0).

This branch (23) is a "dead" zone that generates a significant warm-up time.

Schematic presentation of the invention

The invention is described schematically with reference to FIG.

One of the important differences is that the valve (9) has two particular characteristics:

(a) it is a two-way valve and not a three-way valve

b) this valve is positioned inside the expansion machine on an internal outlet of the high-pressure inlet zone.

It can be positioned in the cylinder head cover or at the interface between the high-pressure inlet chamber (22) and the preheating means (15) connected to the exhaust zone.

Advantageously, the two-way valve (9) is a valve manufactured by Schrader.

This configuration ensures in all circumstances a sweeping of the high-pressure inlet zone by the working fluid, both when the valve is in the open position and when in the closed position, unlike the solutions of the prior art where this high pressure inlet zone is swept by the fluid of only when the valve is in the nominal operating position.

The valve (9) has two positions:

a) a closed position, corresponding to the nominal operation of the expansion machine, where the working fluid circulates inside the expansion machine from the intake zone (22) to the exhaust (32) passing through the expansion zone (25)

b) an open position, corresponding to the three atypical situations referred to above, where the working fluid first passes through the inlet chamber (22), then to open:

in a bypass circuit comprising the preheating means (15) and which connects the intake zone (22) and the exhaust zone (32) without passing through the expansion zone (25), in phase starting when the machine is stopped and does not rotate in the expansion zone opening into the exhaust zone (32) and in the branch circuit, in the other two situations, where the machine is in operation.

General architecture of a single piston solution

Figure 3 shows a view of a first example of implementation of a single piston expansion machine.

It has an intake zone (22) opening in the outer casing (10) through an inlet (20).

Inside the expansion machine, the inlet chamber (22) has two outputs:

a) a first outlet (24) opening into the variable volume expansion zone (25) defined by a moving means, for example a piston (13) in the example described. The invention is not limited to a mobile means formed by A piston. The moving means can also be constituted by a screw or a spiral,

b) a second internal outlet (14) opening into the preheating means described below. The shutter of the valve (9) ensures the opening or closing of this second internal outlet (14).

The first output (24) is always open in the case where the moving means is a screw or a spiral. In the case of a piston machine, the first outlet (24) is controlled by the intake system, which alternately opens and closes the outlet (24) depending on the position of the piston. When the expansion machine is stopped, the first outlet (24) is in any situation, depending on the position of the piston at the time of its stop. The first output (24) can therefore be in the open position, in the closed position or in the intermediate position. In any case, the state of the first internal outlet (24), at the stop of the expansion machine, is not controlled and is only defined by the last position of the piston.

The second internal outlet (14) is associated with a valve (9) controlled by an external signal depending on the state of the expansion machine, the state of the Rankine cycle, in particular the conditions of admission of the steam, and an external stop control of the expansion machine.

The term "internal outlet" in the sense of this patent a passage providing communication between two internal zones of the expansion machine, and not opening out of the expansion machine.

In nominal operation, the second internal output (14) is closed by the shutter of the valve (9).

In the three cases of atypical operation mentioned above, the valve (9) is passing to open the second internal outlet (14) and allow the passage of the working fluid from the inlet chamber (22) to the preheating means (15). ). In the remainder of the description, the term "preheating means", "preheating means", "heating means", "bypass and preheating circuit" or "branch circuit" will be used indifferently; it is in all cases a circulation circuit of the working fluid, when the valve is open, between the intake zone and the exhaust zone with a heat exchange with the expansion zone.

These preheating means (15) consist of passages of the working fluid around the expansion chamber (25), to allow the heating of the piston liner, if necessary, and especially the working fluid stagnant or contained in the expansion chamber (25). They open into the exhaust zone (32). They may be constituted by bores or annular machining formed in the cylinder head or in the liner, and holes connecting these bores and machining.

These preheating means (15) are particularly efficient when the machine is atypical starting phase to heat the expansion zone.

When the machine is in operation, heat exchange is not a desired effect, and the function of this circuit is then mainly to derive a portion of the working fluid to lower the pressure in the intake chamber.

Moreover, the preheating means (15) form a zone of thermal insulation of the expansion zone (25) with respect to the exhaust zone (32), and possibly with respect to the outside, when the valve (9) is in the closed position. This thermal insulation is obtained by the static gas blade inside the preheating means, when they are not traversed by the working fluid. General Architecture of a Three-Piston Solution Figure 4 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 mobile hitch (300) is integrally enclosed in the volume defined by the housing (100) and the cylinder head cover

(200).

The casing (100) surrounds the zone of the expansion machine which extends from the low-piston end point to the outlet of the shaft (1) · This zone comprises in particular the inclined plate (2) which ensures the transformation of the movement of the three pistons (400, 500) back and forth in rotary motion 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 mobile hitch (300) comprises the shaft (1) and the members attached thereto:

- the inclined plate (2)

the three pistons, two of which are shown in FIG. 4 (400, 500) the three pairs of semi-spherical shoes (412, 413) ensuring the transmission of the 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 a Euro-denaturant (standardized mixture) between 1% by weight 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 preheating zone

Figures 5 to 8 show views of an example of a three-piston expansion machine. Figure 5 shows the expansion machine with a partial cutout for visualizing the bypass circuit of the working fluid.

In this example, the cylinder head cover (200) has an inlet (20) opening into a connector (26) on which is connected the inlet pipe of pressurized working fluid. On the other side, the inlet (20) opens into the high pressure inlet zone (22) formed by an annular chamber surrounding the zone containing the valve lifting means, not described in the present application.

The cylindrical inner wall of this annular chamber forming the inlet zone (22) is pierced by a first series of three outlets (24) each opening into a curved conduit opening axially in the expansion zone (25). Each of these first outlets (24) is controlled by a valve (11) having a radially movable portion.

These valves (11) are controlled in known manner by a cam (5) mounted on the motor shaft (1) to ensure the distribution of the working fluid in the expansion chambers.

The cylindrical outer wall of this annular chamber forming the intake zone (22) is pierced by a second outlet (14) opening into a housing receiving the bypass valve (9). This valve (9) controls the opening or closing of an orifice (14) opening into the high-pressure zone of restricted section, 4 to 12 times smaller than the inlet orifice (20), in order to produce intentionally operating in bypass mode (for example for purging the liquid contained in the machine at standstill) an adequate pressure drop.

The passage between the annular chamber forming the intake zone (22) and the preheating means is illustrated in FIG. 5 by the two arrows (46, 47), the fluid passing through the orifice (14) and then through the orifice (828).

The valve (9) is a pneumatic valve powered by the compressed air of the vehicle's pneumatic system.

In the absence of pneumatic supply, the valve

(9) automatically switches to the open position, which controls switching to stop mode in case of failure.

In summary, the annular inlet chamber (22) receives the working fluid and transmits it:

a) when the valve (9) is closed, exclusively to the expansion zone

b) when the valve (9) is open, both at the expansion zone and the preheating means.

This intake chamber (22) is in any case swept by the working fluid under pressure, which ensures both in nominal operation and in one of the three atypical operating cases the purge of the liquid phase working fluid, avoiding any dead zone.

Figures 6 to 8 illustrate in more detail the preheating zone (15).

This zone (15) is formed by an annular space defined on the outside by the cylinder head cover (200) and on the inside by the cylinder head (800). Within this annular zone (15) of preheating is a wall (810) extending in a radial and longitudinal plane intersecting the circulation of the working fluid.

The working fluid enters this annular preheating chamber (15) at one side of the wall (810) through an inlet (828) passing through the transverse shoulder of the cylinder head cover (200), and the other side of this wall (810), through a hole (806) through the transverse bottom (802) exhaust side. The working fluid is forced to traverse a circuit between this inlet port (828) and this outlet port (806), successively bypassing the three expansion chambers (25a, 25b, 25c), which leads to an exchange thermal with these three expansion chambers (25a, 25b, 25c).

For this purpose, each expansion chamber (25a, 25b, 25c) comprises a jacket (409, 509, 609) within which a piston moves. These jackets (409, 509, 609) are inserted into the yoke (800), with a positioning delimiting a peripheral tubular space (418, 518, 618) closed frontally at each end.

Optionally, these tubular spaces (418, 518, 618) have bores (824, 825, 826) radial relative to the axis of the cylinders, and inclined downwardly of the expansion machine when mounted on the motor internal combustion. These inclined bores (824, 825, 826) allow gravity evacuation of liquid residues in nominal operation and maintain a thermal insulation function by means of a static gas blade filling the tubular spaces (418, 518, 618).

These tubular spaces (418, 518, 618) form part of the annular preheating chamber (15). The working fluid enters the first tubular space (418) through a radial lumen (419a) oriented toward the inlet port (828), and exits through a diametrically opposed radial lumen (419b).

The working fluid then continues its path to enter the second tubular space (518) by a radial lumen (519a) oriented towards the radial lumen (419b) of the preceding annular space (418), and emerges by a light diametrically opposite radial (519b).

The working fluid then continues along its path to enter the third tubular space (618) by a radial lumen (619a) oriented towards the radial lumen (519b) of the preceding annular space (518), and is pulled out by a diametrically opposed radial lumen (619b) directed toward the outlet (806).

Thus, the working fluid successively traverses, in bypass operation mode, the three annular spaces (418, 518, 618) surrounding the expansion chambers, and ensures the heating of the working fluid stagnant in the liquid phase in these chambers. Expansion until evaporation of the ethanol, water and denaturant components, which allows their evacuation and allows the lubricant component to find a sufficient concentration to ensure the lubrication of the moving parts.

At the outlet of this annular preheating chamber (15), the working fluid enters the exhaust zone (32) which is filled with working fluid in the liquid phase during startup. The working fluid from the annular preheating chamber (15) is thus injected into the exhaust zone (32) and expels the liquid phase from the working fluid. The lubricating component provided by the working fluid provides the lubricating function of the inclined plate (2) and the moving parts which have been leached by the liquid phase which previously filled the exhaust zone (32).

Finally, the working fluid completes its circuit by evacuation via an orifice (33).

Detailed description of the cylinder head.

The detailed description of the cylinder head is illustrated in Figure 7 and Figure 8.

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 breech (800) has three cavities (414, 514, 614) in which to insert the shirts tubulars (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 FIGS. 3 and 9 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 intended for the passage of the shaft (1).

This passage (1) has a bearing zone of a conical bearing (617) visible in FIGS. 3 and 9.

The bottom (802) of the cylinder head (800) further has holes (803 to 805) for fixing the cylinder head (800) on the housing by screws penetrating into the threads provided in the bosses.

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, and its compressibility is between 10 and 70%.

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, and its compressibility is between 10 and 70%.

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 permitted 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 820) 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 starting from the high-pressure zone, via a passage of bypass 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 EXPANSION AREA FIG. 9 represents a longitudinal sectional view of the expansion machine according to the invention.

The shape of the piston illustrated in Figure 9 differs from that illustrated in Figure 4, 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 hole (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 guidance of the piston is thus ensured on both sides of the inclined 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 inlet side (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 inclined plate (2) is provided in known manner by pads having a spherical cap shape (412, 413) arranged 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 realized made of forged aluminum, followed by 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 inclined 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 thermal insulation

The expansion machine has several zones contributing to thermal insulation. This thermal insulation reduces internal heat transfer to the machine, thus improving the efficiency.

The first thermal insulation zone is provided by the annular ring (406) guiding the head (403) of the piston and taking up the guiding forces of the entire piston (400). This annular ring (406) delimits 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.

A second thermal insulation zone is constituted by the three tubular spaces (418, 518, 618) surrounding the expansion chambers (25a, 25b and 25c). This zone is insulating when the valve (9) is in the closed position.

The third zone of insulation consists of disc spaces (425) located at the bottom of each of the expansion chambers (25a, 25b, 25c). For this purpose, each liner is closed frontally by a bottom (426) crossed by:

an exhaust opening opening into the curved duct opening the exhaust zone

- An inlet opening into a curved conduit opening in the intake zone.

The third isolation spaces (425) are formed between the bottoms (426) of the shirts and the cylinder head (800).

The fourth isolation space is constituted by the annular thermal insulation chamber (816) previously described.

In general, the insulating zones of the machine are arranged to be subjected to the pressure of the exhaust zone (32) by means of passages putting them in communication with said exhaust zone, said passages preferably being placed close to the low point of each of the isolation zones to ensure the drainage of liquids.

By this arrangement, the vapor present in the insulation zones is at a lower density and therefore less conducive to heat. Moreover, its superheating is thus maximum, which limits the condensation phenomena that would harm the thermal insulation. General Architecture of a Spiral Solution

The invention is not limited to a piston expansion machine. It can also relate to a relaxation machine using a screw or a spiral (respectively "screw expander" or "scroll expander" in English).

Figure 10 shows a schematic view of such a machine. The preheating circuit operates in a similar manner to the previously described embodiments.

It comprises a valve (9) controlling the passage of the working fluid, atypical operating mode, to a bypass circuit opening into the exhaust chamber containing the fixed and mobile spirals (16).

This valve (9) controls the opening or closing of the passage of the working fluid from the inlet chamber (22) in this branch circuit. In nominal operation, the valve (9) is in the closed position, all the working fluid from the inlet chamber (22) then supplying the expansion zone delimited by the screw or the spiral.

The previously described characteristics relating to the inlet chamber (22), the valve (9) and the control means of the working fluid in normal operation or atypical operation are directly adapted to such screw machines or spiral.

The spirals (16) may also be provided with thermal insulation means (17, 18) to limit heat transfer between the inlet chamber (22) and the expansion zone (25) and between the zone of expansion (25) and the exhaust zone (32).

Claims

claims

1 - Expansion machine (0) comprising an intake zone (22) having an inlet for a pressurized working fluid, said fluid consisting of a main component in the gaseous phase at nominal operating speed loaded with a lubricating component in the liquid phase,

Said inlet zone (22) being connected to an expansion zone (25),

Said machine further comprising a bypass circuit controlled by a valve (9) for connecting a high pressure zone and an exhaust zone (32).

characterized in that

Said high pressure zone is constituted by the intake zone (22) fed directly by the working fluid under pressure,

Said branch circuit being in contact with the expansion zone (25) to ensure a thermal transfer between the working fluid circulating in said branch circuit and the working fluid contained in said expansion zone (25), for forming a preheating means (15)

· Said intake zone having:

at least a first internal opening opening into an expansion zone (25) and

a second internal opening opening into said bypass circuit, controlled by said valve (9)

Said valve (9) being a two-way valve whose shutter is disposed between said second internal opening of said intake zone (22) and said bypass circuit, for controlling, when said valve (9) is open, a circulation of said working fluid between said internal outlet of said intake zone (22) and said bypass and preheat circuit (15).

2 - expansion machine (0) according to claim 1 characterized in that said valve (9) is a two-way valve proportional control.

3 - expansion machine (0) according to claim 1 characterized in that said valve (9) is a two-way valve controlled by pulses.

4 - expansion machine (0) according to claim 1 characterized in that said bypass circuit and preheating is, when said valve (9) is closed, a thermal insulation means of said expansion zone.

5 - relaxation machine (0) according to claim 1 characterized in that said machine is a piston machine and in that said expansion zone (25) comprises at least one cylinder.

6 - relaxation machine (0) according to the preceding claim characterized in that said cylinder contains a jacket (409) defining an annular space with the wall of said cylinder, said preheating means (15) comprising said annular space.

7 - relaxation machine (0) according to claim 5 characterized in that said piston contains a thermal insulation means.

8 - relaxation machine (0) according to claim 1 or 5 characterized in that it comprises an insulation means heat disposed between said intake zone (22) and said exhaust zone (32).

9 - relaxation machine (0) according to claim 1 or 5 characterized in that it comprises a thermal insulation means disposed between said intake zone (22) and said expansion zone (25).

10 - relaxation machine (0) according to claim 1 or 5 characterized in that it comprises a thermal insulation means disposed between said exhaust zone (32) and said expansion zone (25).

11 - relaxation machine (0) according to any one of claims 7 to 10 characterized in that at least one said thermal insulation means is constituted by an insulating material.

12 - relaxation machine (0) according to any one of claims 7 to 10 characterized in that at least one said insulation means is constituted by a hollow space communicating with said exhaust zone (32) through orifices .

13 - relaxation machine (0) according to claims 6 and 9 or 6 and 10 characterized in that said liner (409) is closed frontally, the frontal closing partition having at least one inlet and / or exhaust port said insulation means being defined between said front closure partition and the cylinder head.

14 - relaxation machine (0) piston according to claim 5 characterized in that a hollow volume between the front surface of the piston head and the front surface the piston body (400) constitutes a zone of thermal insulation.

15 - relaxation machine (0) piston according to the preceding claim characterized in that said hollow volume has a bore opening into the exhaust zone (32) to allow the evacuation of the liquid phase of the working fluid.

16 - Thermal energy recovery system comprising at least one evaporator, at least one condenser, at least one pump and an expansion machine comprising an intake zone (22) having an intake port for a working fluid under pressure, said fluid being constituted, at the inlet of the expansion machine (0) in nominal operating mode, by a main component in the gaseous phase charged with a lubricant component in liquid phase,

Said inlet zone (22) being connected to an expansion zone (25),

Said machine further comprising a bypass circuit controlled by a valve for connecting a high pressure zone and an exhaust zone (32)

characterized in that

Said branch circuit being in contact with the expansion zone (25) to ensure a thermal transfer between the working fluid circulating in said branch circuit and the working fluid contained in said expansion zone, to form a means preheating (15)

Said intake zone (22) presenting:

at least a first internal opening opening into an expansion zone (25) and a second internal opening opening into said bypass circuit, controlled by said valve (9)

Said valve (9) being a two-way valve disposed between said second internal opening of said intake zone and said bypass circuit, for controlling, when said valve (9) is open, a circulation of said working fluid between said internal outlet of said inlet zone (22) and said bypass and preheat circuit.

17 - Method for controlling the operation of an expansion machine comprising an intake zone (22) having an inlet for a working fluid in the gaseous state under pressure,

Said inlet zone (22) being connected to an expansion zone (25),

Said machine comprising a bypass and preheat duct between said intake zone (22) and an exhaust zone (32),

Characterized in that

When the temperature of the expansion machine is lower than a variable threshold value as a function of pressure, the opening of a two-way valve (9) disposed between an output of said zone inlet (22) and said bypass and preheat duct, for circulating said working fluid between an outlet of said inlet zone (22) and said bypass and preheat duct, in order to purge the zone of expanding (25) the working fluid in the liquid phase and depositing a film of lubricant on the moving parts.

18 - Method for controlling the operation of an expansion machine (0) comprising an intake zone (22) having an inlet for a working fluid in gaseous state under pressure,

Said inlet zone (22) being connected to an expansion zone (25),

Characterized in that

When the pressure of the working fluid at the inlet of the expansion machine is greater than a threshold value, the opening of a two-way valve (9) disposed between an outlet of said zone inlet (22) and said bypass and preheat duct for lowering the inlet pressure of the working fluid.

19 - Method for controlling the operation of an expansion machine (0) comprising an intake zone (22) having an inlet for a working fluid in the gaseous state under pressure,

Said inlet zone (22) being connected to an expansion zone (25),

Characterized in that

When switching to the "stop" mode of the system comprising the said expansion machine, the passage in open mode of a two-way valve (9), the shutter of which is arranged between an output of said zone d, is controlled inlet (22) and said bypass and preheat duct, for lowering the pressure ratio between the intake and the exhaust.

20 - Method for controlling the operation of an expansion machine (0) comprising an intake zone (22) having an intake port for a working fluid in the gaseous state under pressure,

Said intake zone (22) being connected to an expansion zone (25),

Characterized in that

When the difference between the temperature of the working fluid and the saturation temperature at the pressure of the working fluid, measured at the intake, is controlled, it is less than a threshold value for a duration greater than a reference period. , the open-mode passage of a two-way valve (9) disposed between an outlet of said intake zone (22) and said one bypass and preheat duct, to reduce the pressure of the working fluid in the zone admission (22).

21 - Method for controlling the operation of an expansion machine (0) comprising an intake zone (22) having an inlet for a working fluid in the gaseous state under pressure,

Said inlet zone (22) being connected to an expansion zone (25),

Characterized in that

When the difference between the temperature of the working fluid and the saturation temperature at the pressure of the working fluid, measured at the exhaust, is controlled, it is less than a threshold value for a duration greater than a reference time, the open-mode transition of a two-way valve (9) disposed between an outlet of said intake zone (22) and said one bypass and preheat duct, to reduce the pressure of the working fluid in the intake area

(22).