FR3067385A1 - RELAXATION MACHINE AND METHODS OF USING SUCH A MACHINE - Google Patents

Abstract

The present invention relates to an expansion machine (0) comprising an intake zone (22) having an intake port for a pressurized working fluid, said fluid being constituted by a main component in the gaseous phase under nominal operating conditions loaded with a lubricating component in the liquid phase. The high pressure zone is constituted by the intake zone (22) fed directly by the working fluid under pressure. The bypass circuit being in contact with the expansion zone (25) to provide heat transfer between the working fluid flowing in said bypass circuit and the working fluid contained in said expansion zone (25), to form a means for preheating (15). The intake zone (22) has: 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).

Description

RELAXATION MACHINE AND

METHODS OF USING SUCH A MACHINE

Field of the invention

The present invention relates to the field of expansion machines for recovering thermal energy from hot fluid, for 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 expansion machines is known in the prior art.

In particular, European patent application EP3128137 describes an assembly for controlling a flow of working fluid in the gaseous phase between its source and the intake of an expansion machine.

The purpose of this solution of the prior art is to avoid 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 aim is to limit the pressure when it is excessive. For this, this solution provides a slide valve comprising several passages supplying on one side the cylinder head, on the other side the exhaust zone.

Also known in the prior art is the international patent application WO 2016142144 describing an axial piston machine which comprises a rotor in a casing, cylinders arranged annularly around the rotor and in which pistons are arranged movable in translation, an orifice admission to a cylinder head and an exhaust port in the housing being associated with each cylinder. This solution of the prior art is characterized in that an intake channel leading to the intake port and an exhaust channel communicating with the exhaust port are provided in the cylinder head and in the casing respectively. . A bypass channel extends from the cylinder head to the exhaust channel to an area comprising a plate inclined through the housing. A bypass valve is connected to or integrated into the cylinder head and distributes a working fluid between the intake channel and the bypass channel according to its position.

The purpose of this solution is to reduce the size of the machine by better integration of the circuits, and to accelerate the heating of the axial piston engine by a bypass channel formed in the body of the machine, and controlled by a three-way valve. channels distributing the working fluid supplying the machine at the cylinder head inlet either towards the cylinder head or towards the bypass channel.

The international patent application WO 2014123572 is also known.

This document relates to a waste heat recovery device, for use with an internal combustion engine, comprising a working fluid circuit for circulating working fluid, an evaporator connected to the working fluid circuit and suitable for recovering waste heat from a source to heat the working fluid, an expansion machine connected to the working fluid circuit to receive working fluid from the evaporator, and a heating means associated with the expansion machine . The working fluid circuit downstream of the evaporator comprises a first connection connecting to an inlet of the expansion machine and a second connection connecting to the heating means. A valve is connected to the working fluid circuit to selectively regulate the flow of working fluid to the first connection for expansion and recovery work or to the second connection for heating

the machine job. of relaxation according to temperature of fluid of The goal this solution is improve the operation of the machine when the fluid of job East

at an insufficient temperature and close to saturation, in order to avoid degradation of the machine by injection of a liquid phase, and to reduce the heating time of the machine. The expansion machine of the prior art for this purpose comprises a heating means which is connected to receive a working fluid for the purpose of heating the expansion machine. A three-way bypass valve controls the bypass of the working fluid to the expansion machine or to the heating means.

Also known is the international patent application WO / 2017/008094 describing a method for controlling a waste heat recovery system for an internal combustion engine of a vehicle. This waste heat recovery system has at least one expander that transmits torque to the internal combustion engine and can be bypassed via a bypass flow path. The evaporator is arranged in the region of the exhaust system of the internal combustion engine. The expander can operate in different modes depending on at least one input variable.

The input variable is selected from the group comprising the following elements:

- speed of rotation of the expander,

- reporting information (IM),

- slowdown information (CI),

- pressure (pl, p2) and temperature (Tl, T2) of the service fluid upstream and downstream of the expander (22) via the control device (30).

A first operating mode is associated with a warm-up phase after starting the expander. A second operating corresponds to a normal operating phase of the expander.

In the first mode, the bypass flow path is open and the expander is not connected to an auxiliary drive shaft of the internal combustion engine.

In the second mode, the bypass flow path is closed and the expander is connected to the internal combustion engine. The second mode is selected when the pressure (p2) and / or the temperature (T2) of the service fluid downstream from the expander (22) exceeds a defined value.

This solution is not satisfactory because it proposes to implement a control device external to the machine, which does not make it possible to optimize the heat exchanges of the internal organs, in particular of the admission with the fluid.

Another patent EP2886806 describes another known turbomachine solution comprising a turbine disposed in a housing, which can be stressed with a hot working fluid, characterized in that at least one bypass channel extending entirely inside the housing and surrounding the turbine is provided to heat the housing via the working fluid.

Disadvantages of the prior art

The solutions of the prior art provide for the use of three-way valves, which are expensive for applications of circulation of fluids at high temperature and high pressure, and which are also corrosive (generally ethanol).

Furthermore, these solutions do not allow adequate heating of the branch downstream of the valve, between the valve and the cylinder head. This part of the expansion machine is only heated by thermal conduction.

Solution provided by the invention

The present invention aims to remedy the drawbacks of the prior art by allowing the use of a two-way valve only, and above all ensuring optimum temperature setting of all the parts of the thermal machine, especially during the phase of start-up.

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

To this end, the invention relates, in its most general sense, to an expansion machine comprising an intake zone having an intake orifice for a working fluid under pressure, said fluid being constituted by a main component in the gaseous phase. in nominal operating conditions loaded with a lubricant component in the liquid phase, • said intake zone being connected to an expansion zone, • said machine further comprising a bypass circuit controlled by a valve for connecting a high pressure zone and an exhaust zone characterized in that • said high pressure zone is constituted by the intake zone supplied directly by the working fluid under pressure, • said bypass circuit being in contact with the zone expansion to ensure thermal transfer between the working fluid circulating in said bypass circuit and the working fluid contained in said zone expansion, to form a preheating means • said intake zone having:

o at least a first internal opening opening into an expansion zone and o a second internal opening opening into said branch circuit, controlled by said valve

Said valve being a valve together way disposed Between said second opening internal of said zoned admission and said circuit of : derivation, for order, when said valve East opened, a traffic said fluid of job Between said exit internal of said admission area and said circuit of

bypass and preheat.

According to first variants:

said valve East a valve at of them way at ordered proportional. said valve East a valve at of them way at ordered by pulses. These variants present a effect technical

allowing regulation when the inlet pressure is maximum without loss of efficiency, and starting (at intermediate Padm inlet pressure), stopping (mini Padm) and overheating regulation more robustly.

Preferably, said bypass and preheating circuit constitutes, when said valve is closed, a means of thermal insulation of said expansion zone.

Advantageously, said machine is a piston machine and said expansion zone comprises at least one cylinder.

According to other variants which are not mutually exclusive,

- Said cylinder contains a jacket defining an annular space with the wall of said cylinder, said preheating means comprising said annular space.

said piston contains a means of thermal insulation.

the machine comprises a thermal insulation means disposed between said intake zone and said exhaust zone.

the machine comprises a thermal insulation means disposed between said intake zone and said expansion zone.

- Said thermal insulation means consists of an insulation material.

- Said isolation means is constituted by a hollow space communicating with said exhaust zone through orifices.

said jacket is closed frontally, the front closing partition having at least one inlet and / or exhaust orifice, said insulation means being defined between said front closing partition and the cylinder head.

The invention also relates to a system for recovering thermal energy comprising at least one evaporator, at least one condenser, at least one pump and an expansion machine comprising an intake zone having a fluid intake inlet. working under pressure, said fluid being constituted, at the intake of the expansion machine in nominal operating conditions, by a main component in the gas phase loaded with a lubricant component in the liquid phase, • said intake zone being connected to a expansion zone, • said machine further comprising a bypass circuit controlled by a valve for bringing together a high pressure zone and an exhaust zone characterized in that • said high pressure zone is constituted by the intake zone supplied directly by the working fluid under pressure, • said bypass circuit being in contact with the expansion zone to ensure transfer t thermal between the working fluid circulating in said bypass circuit and the working fluid contained in said expansion zone, to form a means of preheating • said intake zone having:

o at least one first internal opening opening into an expansion zone and o a second internal opening opening into said branch circuit, controlled by said valve • Said valve being a two-way valve disposed between said second internal opening of said zone intake and said bypass circuit, to control, when said valve is open, a circulation of said working fluid between said internal outlet of said intake zone and said bypass and preheating circuit.

The invention also relates to a method for controlling the operation of an expansion machine comprising an intake zone having an orifice for admitting a working fluid in the gaseous state under pressure, • said intake zone being connected to an expansion zone, • said machine comprising a bypass and preheating duct between said intake zone and an exhaust zone,

Characterized in that • when the temperature of the expansion machine is lower than a variable threshold value depending on the pressure, it is controlled to switch to open mode of a two-way valve arranged between an outlet from said zone inlet and said bypass and preheating duct, to ensure circulation of said working fluid between an outlet of said intake zone and said bypass and preheating duct, in order to purge the expansion zone of the working fluid in the liquid phase and deposit a film of lubricant on the moving parts.

According to variants of the method, it also has the following characteristics:

when the inlet working pressure in the expansion machine is higher than a threshold value, the passage in open mode of a two-way valve arranged between an outlet from said zone and said inlet bypass duct and to lower the inlet pressure of the working fluid.

when the system comprising said expansion machine goes into “stop” mode, the passage of an open two-way valve disposed between an outlet of said intake zone and said bypass and preheating duct is switched to open mode, to lower the pressure ratio between intake and exhaust.

when the difference between the temperature of the working fluid and the saturation temperature at the pressure of the working fluid, measured at the inlet, is controlled to be less than a threshold value for a duration greater than a reference duration, the passage in open mode of a two-way valve disposed between an outlet of said intake zone and said a bypass and preheating conduit, to reduce the pressure of the working fluid in the intake zone.

• 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 to be less than a threshold value for a duration greater than a reference duration, passage in open mode of a two-way valve disposed between an outlet of said intake zone and said a bypass and preheating conduit, to reduce the pressure of the working fluid in the intake zone.

Detailed description of a nonlimiting example of

1'invention

The present invention will be better understood on reading the detailed description of a nonlimiting example of the invention which follows, referring to the accompanying drawings in which:

- Figure 1 shows a schematic view of the solutions of the prior art

- Figure 2 shows a schematic view of the solution according to the invention Figure 3 shows a longitudinal sectional view of a first embodiment of a single piston expansion machine

- Figure 4 shows 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

- Figure 6 shows a cross-sectional view of the second 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 section view of the expansion machine.

- Figure 10 shows a schematic view of a third alternative 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 transformation of the energy coming 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 the form of vapor charged with lubricant, coming from the high-pressure intake zone and discharged through an exhaust zone.

By convention, the term “expansion zone” 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 the thermodynamic energy of thermal fluid into mechanical work.

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

The terms “admission zone” or “admission chamber” will also be used afterwards.

The pressurized fluid comprises a main component such as ethanol, ensuring the thermodynamic cycle, loaded with a liquid lubricant sprayed in 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 mass.

This working fluid can also comprise components such as water, in a proportion of between 0 and 20% by mass and possibly additives for denaturing ethanol, for example eurodenaturant (trade name). , or an alkane, or a ketone in proportions of between 1 and 10% by mass. 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 expansion 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 relative to atmospheric pressure which would lead in the long term to the penetration of air and therefore oxygen into the circuit.

The transition from this latter situation to a nominal operating mode constitutes a critical transient phase, since 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. In fact, in the “hot” phase, the lubricant is the only component remaining in the liquid phase and therefore performs its lubrication function. On the other hand, in the "cold" phase, the other constituents are also in the liquid phase and thereby dilute the lubricant, and very significantly reduce its lubrication capacity. The dilution is typically by a factor of 5 to 100.

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

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

a) the start-up stage of the machine passing from stopping to setting in motion

b) the step of stopping the machine passing in reverse from nominal operation to stopping

c) unsuitable working fluid temperature and pressure situations with nominal operation.

The invention relates to the control of these three atypical operating regimes 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 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 (possibly), 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 not very lubricating, the lubricant being highly diluted, and the machine would start up under unfavorable friction and wear conditions.

The liquid mixture is monophasic, the different constituents mixing perfectly. To allow the “lubricant” component to be concentrated, it is necessary to evaporate the other components (water, ethanol and denaturant), by heating to a temperature above the evaporation temperature of these three other components, and below the decomposition temperature of the lubricant.

This heating should preferably take place in the areas closest to the expansion area in order to promote the evacuation of the water, ethanol and denaturing components, and to promote the deposition of the lubricant on the surface of the expansion area, 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 stagnating there before starting.

b) the shutdown of the expansion machine: when it is desired to cause the shutdown of the expansion machine before the natural shutdown resulting from the ratio of the intake pressure to the exhaust pressure below a threshold value , the means makes it possible 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 (in particular in the event of the vehicle stopping) without necessarily causing the rotation of the latter to stop, the means making it possible to reduce the pressure ratio to an adequate value, in particular if the 2-way valve is of the proportional or pulse-controlled type

c) filtering the intake or exhaust conditions of the working fluid outside their nominal range, for example in the event of pressure exceeding a threshold value or insufficient overheating. Insufficient overheating 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 less than a threshold value for a duration greater than a threshold duration. An insufficient overheating threshold value is for example 5 ° K for 30 seconds.)

In the prior art, it has been proposed to meet these three objectives with solutions illustrated diagrammatically in FIG. 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, depending on its position: a) the direct transmission of the working fluid from the inlet (21) to the intake port (20) opening into the intake 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 the branch (23) between the valve (90) and the high-pressure intake zone (22) of the expansion machine (0) to be emptied correctly and quickly.

This branch (23) is therefore a "dead" zone which generates a significant preheating time.

Schematic presentation of the invention

The invention is described schematically with reference to FIG. 2.

One of the important differences is the fact 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 intake zone.

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

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

This configuration makes it possible in all circumstances to ensure a sweeping of the high-pressure intake zone by the working fluid, both when the valve is in the open position and when it is in the closed position, unlike the solutions of the prior art where this high-pressure inlet zone is scanned by the working fluid 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) in passing through the expansion zone (25)

b) an open position, corresponding to the three above-mentioned atypical situations, where the working fluid first passes through the intake chamber (22), to then 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 the phase of starting where the machine is stopped and does not rotate in the expansion zone opening into the exhaust zone (32) and in the bypass circuit, in the two other 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 area (22) opening into the outer casing (10) through an intake port (20).

Inside the expansion machine, the intake chamber (22) has two outlets:

a) a first outlet (24) opening into the variable-volume expansion zone (25) defined by a movable means, for example a piston (13) in the example described. The invention is not limited to a mobile means formed by a piston. The mobile 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 first outlet (24) is always open in the case where the mobile 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 when it stops. The first outlet (24) can therefore also be in the open position, in the closed position or in the intermediate position. In any event, the state of the first internal output (24), when the expansion machine stops, is not controlled and is only defined by the last position of the piston.

The second internal output (14) is associated with a valve (9) controlled by an external signal as a function of the state of the expansion machine, the state of the Rankine cycle, in particular the conditions for admission of steam, and an external control for stopping the expansion machine.

For the purposes of the present patent, the term “internal outlet” means a passage ensuring communication between two internal zones of the expansion machine, and not opening out to the exterior of the expansion machine.

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

In the three aforementioned atypical operating cases, the valve (9) is open to open the second internal outlet (14) and allow the passage of the working fluid from the intake chamber (22) to the preheating means (15 ).

In the following description, the term “preheating means”, “preheating means”, “heating means”, “bypass and preheating circuit” or “bypass circuit” will be used interchangeably; in all cases, this is a circulation circuit for 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 jacket, if necessary, and especially of the working fluid stagnant or contained in the expansion chamber (25). They open into the exhaust zone (32). They can be constituted by bores or annular machining operations formed in the cylinder head or in the jacket, and bores connecting these bores and machining operations.

These preheating means (15) are particularly efficient when the machine is in the atypical start-up 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 part of the working fluid to lower the pressure in the intake chamber.

Furthermore, the preheating means (15) form a thermal insulation zone 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 external body formed by two complementary hollow parts:

- a housing (100) - a cylinder head cover (200). These two parts Additional (100, 200) show each a bridle peripheral (101, 201) complementary, for waterproof by bolting. to permit an assembly so

The movable coupling (300) is fully enclosed in the volume defined by the casing (100) and the cylinder head cover (200).

The housing (100) surrounds the area of the expansion machine which extends from the bottom dead center piston end to the output 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 arrival of steam in the cylinder head to the exhaust ports (38) provided at the bottom dead center piston. It is the hottest part of the expansion machine.

The movable coupling (300) comprises the shaft (1) and the members attached to it:

- the inclined plate (2)

- the three pistons, two of which are shown in Figure 4 (400, 500)

- the three pairs of semi-spherical pads (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 vapor is charged with lubricant.

The lubricant travels in a known manner throughout the 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 mass, preferably 4.5% by mass (azeotrope).

To this mixture is added a denaturant, for example an alkane or a ketone or of the eurodenaturant (standardized mixture) between 1% by mass and more (Euro-denaturant 7% by volume) to which polyalkylene type lubricant is added. glycol (PAG) miscible between 1 and 20% by mass, generally around 10%.

Steam arrives via an inlet connection (20) provided on the cylinder head cover (200) and exits, in the example described, on the opposite side by an exhaust flange (33) provided on the casing (100).

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 to view the bypass circuit of the working fluid.

In this example, the cylinder head cover (200) has an inlet orifice (20) opening into a fitting (26) to which the working fluid inlet pipe under pressure is connected. On the other side, the intake orifice (20) opens into the high pressure intake 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 intake zone (22) is pierced with a first series of three outlets (24) each opening into a curved conduit opening axially in the expansion zone (25). Each of these first outputs (24) is controlled by a valve (11) having a radially movable part.

These valves (11) are controlled in a 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 with 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 intake orifice (20), in order to produce intentionally when operating in bypass mode (for example to drain the liquid contained in the stopped machine) 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) then through the orifice (828).

The valve (9) is a pneumatic valve supplied with compressed air from the vehicle's pneumatic system.

If there is no pneumatic supply, the valve (9) automatically switches to the open position, which switches to stop mode in the event of a failure.

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

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

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

This inlet chamber (22) is in all cases swept by the working fluid under pressure, which makes it possible to ensure both in nominal operation and in one of the three cases of atypical operation the purging of the liquid phase. working fluid, avoiding any dead zones.

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). Inside this annular preheating zone (15) there is a wall (810) extending in a radial and longitudinal plane cutting off the circulation of the working fluid.

The working fluid enters this annular preheating chamber (15), on one side of the wall (810) through an inlet orifice (828) passing through the transverse shoulder of the cylinder head cover (200), and comes out of the other side of this wall (810), through an orifice (806), crossing the transverse bottom (802) on the exhaust side.

The working fluid is forced to pass through a circuit between this inlet orifice (828) and this outlet orifice (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) inside which moves a piston. These shirts (409, 509, 609) are inserted into the cylinder head (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 holes (824, 825, 826) radial relative to the axis of the cylinders, and inclined towards the bottom of the expansion machine when it is mounted on the engine. internal combustion. These inclined bores (824, 825, 826) allow the gravitational evacuation of the liquid residues in nominal operation and maintain a thermal insulation function thanks to 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) by a radial lumen (419a) oriented towards the inlet orifice (828), and exits by a diametrically opposite radial lumen (419b).

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

The working fluid then continues its course to enter the third tubular space (618) by a radial lumen (619a) oriented in the direction of the radial lumen (519b) of the preceding annular space (518), and exits by a lumen diametrically opposite radial (619b) directed towards the outlet orifice (806).

Thus, the working fluid passes successively, in bypass operating mode, the three annular spaces (418, 518, 618) surrounding the expansion chambers, and ensures the heating of the working fluid stagnating in liquid phase in these chambers d expansion until the evaporation of the ethanol, water and denaturing components, which allows their evacuation and allows the lubricating component to regain 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 start-up. The working fluid from the annular preheating chamber (15) is thus injected into the exhaust zone (32) and drives out the liquid phase of the working fluid. The lubricant component provided by the working fluid performs the lubrication function of the plate (2) and of the moving parts which had been washed out by the liquid phase which previously filled the exhaust zone (32).

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

Detailed description of the cylinder head.

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

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

The cylinder head (800) has three cavities (414, 514, 614) into which are inserted the tubular liners (409, 509, 609) open at the two front ends. The cavities (414, 514, 614) are blind, each having two orifices, namely an oblong exhaust orifice (415, 515, 615) and an intake orifice (416, 516, 616).

A flat seal (417) visible in Figures 3 and 9 seals between the front surface of the jacket (409) and the bottom of the cavity (414).

The jacket (409) has an annular groove (418) making it possible to define, with the interior wall of the cavity (414), an annular space forming thermal insulation. Optionally, this space can be traversed by a flow of hot steam.

To this end, 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 either side. 'a median longitudinal plane.

Other holes (824, 825, 826) can be provided to allow the evacuation by gravity 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 hole (801) is intended for the passage of

The tree (1).

This passage (1) has a carrying area for a tapered bearing (617) visible in FIGS. 3 and 9.

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

The orifice (806) constitutes the outlet of an internal bypass duct (“bypass”) ensuring the purging of the stagnant liquid in the machine when stopped.

The bottom (802) also has three lights (807 to 809) intended for the passage of steam escaped through the exhaust ducts (415, 515 and 615).

Near the orifice (806), the cylinder head (800) has a wall (810) extending radially, in a longitudinal plane, between the transverse front face (802) and the intermediate transverse plate (811). This wall (810) partitions the circulation of vapor in the bypass circuit which will be described in more detail below. It has a hole (822) intended to prevent 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 seal, made of expanded polytetrafluoroethylene, the thickness of which is between 1 and 4 millimeters.

This plate (811) is surmounted by an annular crown (813) having at its end a peripheral edge (814) surrounded by a seal (815). This seal (815) is also a flat seal, made of expanded polytetrafluoroethylene, the thickness of which is between 1 and 4 millimeters.

The annular space between the seals (812) and (815) constitutes the high-pressure zone connected to the intake (20) and opening, via the intake valves (11), into the expansion chambers delimited by the liners (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 2 flat seals (812 and 815) when the cylinder head cover (200) is brought axially and is positioned on the casing (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 joints of different heights are allowed thanks to the compressibility properties of expanded polytetrafluoroethylene as well as the judicious choice of the thickness of the flat joints (812, 815).

The annular ring (813) defines, with an internal wall (817) complementary, a thermal insulation chamber (816) of annular shape.

The internal wall (817) is pierced by three exhaust ducts (818 to 820) which are connected on one side to the exhaust orifice (415, 515, 615) and on the other side to lights ( 821) which can be closed off 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 rod valves, movable in substantially radial directions, under the action of the cams (5, 6) located on the shaft (1).

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

The inlet 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) with a diameter 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 bypass passage formed in the cylinder head cover (200) controlled by a valve (9).

This conduit opens into a zone 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 circulating in this zone successively crosses the annular spaces (418), into which they enter through one of the orifices (419, 519, 619) and exits through the another opposite opening.

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

Detailed description of the expansion area

FIG. 9 represents a view in longitudinal section of the expansion machine according to the invention.

The shape of the piston illustrated in FIG. 9 differs from that illustrated in FIG. 4, corresponding to an alternative embodiment with regard 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 shrinking.

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

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

This annular ring (406) guides the head and takes up the guiding forces of the piston assembly (400). It also defines a hollow volume (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 from the working fluid.

The head (403) is surrounded by an annular skirt (408) providing guidance relative to the liner (409) of the cylinder head (800).

The other end of the piston (400) also has an annular guide skirt (410) delimiting an open cavity (411) making it possible to avoid vapor compression between the body of the piston (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).

Guiding of the piston is thus ensured on either side 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 intake side (20), this which facilitates the integration of the trigger machine in a vehicle.

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

The cooperation between the piston (400) and the plate (2) is ensured in a known manner by pads having a shape of a spherical cap (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 the subject of 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 a surface treatment by nitriding 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 surface treatment by nitriding in a salt bath followed by an oxidation phase.

The plate (2) is made of spheroidal graphite cast iron, then subjected to a surface treatment by nitriding in a salt bath followed by an oxidation phase.

Alternatively, the plate is made of forged steel which is the subject of a DLC type treatment on at least its flat 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 transfers to the machine, and therefore improves 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) defines a hollow volume (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 formed 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 isolation zone consists of disc spaces (425) located at the bottom of each of the expansion chambers (25a, 25b, 25c).

To this end, each shirt is closed frontally by a bottom (426) crossed by:

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

- an intake opening opening into a curved duct opening into the intake area.

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

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

In general, the isolation 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 being preferably placed. close to the low point of each of the insulation zones to ensure the drainage of liquids.

By this arrangement the vapor present in the insulation zones is of lower density and therefore less conductive of heat. In addition, its overheating is thus maximum, which limits the phenomena of condensation which would harm thermal insulation.

General architecture of a spiral solution

The invention is not limited to a piston expansion machine. It can also relate to an expansion 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 embodiments previously described.

It comprises a valve (9) controlling the passage of the working fluid, in atypical operating mode, towards 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 coming from the intake chamber (22), in this bypass circuit. In nominal operation, the valve (9) is in the closed position, all the working fluid coming from the intake chamber (22) then supplying the expansion zone delimited by the screw or the spiral.

The characteristics described above concerning the intake chamber (22), the valve (9) and the means for controlling the working fluid in normal operation or in atypical operation are directly adapted to such screw or spiral machines.

The spirals (16) can also be provided with thermal insulation means (17, 18) in order to limit the heat transfers between the intake chamber (22) and the expansion zone (25) as well as between the zone expansion (25) and the exhaust zone (32).

Claims (21)

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 in nominal operating conditions loaded with a lubricant component in the liquid phase, • said intake 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 consists of the intake zone (22) supplied directly by the working fluid under pressure, • said circuit bypass being in contact with the expansion zone (25) to ensure a thermal transfer between the working fluid circulating in said bypass circuit and the working fluid contained in said expansion zone (25), to form a preheating means (15) • said intake zone having: o at least a first internal opening opening into an expansion zone (25) and o a second internal opening opening into said branch circuit, controlled by said valve (9) • said valve (9) being a two-way valve arranged between said second internal opening of said intake zone (22) and said bypass circuit, to control, 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 preheating circuit (15). 2 - expansion machine (0) according to claim 1 5 characterized in that said valve (9) is a two-way valve with proportional control. 3 - expansion machine (0) according to claim 1 characterized in that said valve (9) is a two-way valve 10 channels with pulse control. 4 - Expansion machine (0) according to claim 1 characterized in that said bypass and preheating circuit constitutes, when said valve (9) is closed, a 15 means of thermal insulation of said expansion zone. 5 - expansion machine (0) according to claim 1 characterized in that said machine is a piston machine and in that said expansion zone (25) comprises at 20 minus one cylinder. 6 - Expansion machine (0) according to the preceding claim characterized in that said cylinder contains a jacket (409) defining an annular space with the wall 25 of said cylinder, said preheating means (15) comprising said annular space. 7 - expansion machine (0) according to claim 5 characterized in that said piston contains a means 30 thermal insulation. 8 - expansion 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 35 exhaust zone (32). 9 - expansion 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 - Expansion 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 - Expansion 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 insulation material. 12 - Expansion 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) by orifices . 13 - Expansion machine (0) according to claims 6 and 9 or 6 and 10 characterized in that said jacket (409) is closed frontally, the front closing partition having at least one inlet and / or exhaust port , said insulation means being defined between said front closing partition and the cylinder head. 14 - Expansion machine (0) with pistons according to claim 5 characterized in that a hollow volume between the front surface of the piston head and the front surface of the piston body (400) constitutes a thermal insulation zone. 15 - Expansion machine (0) with pistons according to the preceding claim characterized in that said hollow volume has a hole 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 inlet for admitting a working fluid under pressure, said fluid being constituted, on admission of the expansion machine (0) in nominal operating mode, by a main component in the gas phase loaded with a lubricant component in the liquid phase, • said intake 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 high pressure zone is constituted by the intake zone (22) supplied directly by the working fluid under pressure, • said bypass circuit being in contact with the expansion zone (25) to ensure a heat transfer between the working fluid circulating in said bypass circuit and the working fluid contained in said expansion zone, to form a preheating means (15) • said intake zone (22) having: o at least a first internal opening opening into an expansion zone (25) and o a second internal opening opening into said branch circuit, controlled by said valve (9) • said valve (9) being a two-way valve arranged between said second internal opening of said intake zone and said bypass circuit, to control, 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 preheating circuit. 17 - Method for controlling the operation of an expansion machine comprising an inlet zone (22) having an orifice for admitting 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 preheating 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 depending on the pressure, it is controlled to switch to open mode of a two-way valve (9) disposed between an outlet of said intake zone (22) and said bypass and preheating duct, to ensure circulation of said working fluid between an outlet of said intake zone (22) and said bypass and preheating duct, in order to purge the expansion zone (25) of the working fluid in the liquid phase and deposit a film of lubricant on the moving parts. 18 - Method for controlling the operation of an expansion machine (0) comprising an inlet zone (22) having an orifice for admitting a working fluid in the gaseous state under pressure, • said zone intake (22) being connected to an expansion zone (25), • said machine comprising a bypass and preheating duct between said intake zone (22) and an exhaust zone (32), Characterized in that • when the pressure of the working fluid on the inlet of the expansion machine is greater than a threshold value, it is controlled to switch to open mode of a two-way valve (9) disposed between an outlet from said intake zone (22) and said bypass and preheating duct, to lower the intake pressure of the working fluid. 19 - Method for controlling the operation of an expansion machine (0) comprising an inlet zone (22) having an inlet orifice for a working fluid in the gaseous state under pressure, • said zone intake (22) being connected to an expansion zone (25), • said machine comprising a bypass and preheating duct between said intake zone (22) and an exhaust zone (32), Characterized in that • when the system comprising said expansion machine is switched to “stop” mode, the passage into open mode of a two-way valve (9) disposed between an outlet from said zone intake (22) and said bypass and preheating duct, to lower 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 inlet orifice for a working fluid in the gaseous state under pressure, (22) being connected a zone said expansion intake zone (25), said machine comprising a bypass and preheating duct between said intake zone (22) and an exhaust zone (32), Characterized in that one controls, when the difference between the temperature of the working fluid and the saturation temperature at the pressure of the working fluid, measured at the inlet, is less than a threshold value for a duration greater than one reference time, the passage into open mode of a two-way valve (9) disposed between an outlet of said intake zone (22) and said a bypass and preheating duct, to reduce the pressure of the working fluid in the intake area (22). 21 - Method for controlling the operation of an expansion machine (0) comprising an inlet zone (22) having an inlet orifice for a working fluid in the gaseous state under pressure, • said zone intake (22) being connected to an expansion zone (25), • said machine comprising a bypass and preheating duct between said intake zone (22) and an exhaust zone (32), Characterized in that • we control, when the difference between the working fluid temperature and the saturation temperature at the working fluid pressure, measured at the exhaust, is less than a threshold value for a period greater than a reference duration, the transition to two-way mode disposed between an open intake of a valve (9) leaving said zone (22) and said a bypass and preheating conduit, to reduce the pressure of the work in the admission area