COAXIAL TWO-PIECE CONNECTOR AND EXTERNAL HOT SOURCE MOTOR WITH THIS

Description

Technical field

[0001] The present invention relates to a slide valve for an external heat source engine of the type comprising: at least one cylinder, at least one piston, a cylinder head, a working chamber for a working gas, a distribution comprising said slide valve and selectively communicating the working chamber with different resources. The slide valve comprises two coaxial parts: a working gas guide part, comprising internal passages opening radially through at least one mouth which communicates selectively with the working chamber through at least one light made in the cylinder head, and a working gas distribution part, movable and arranged on the periphery of the guide part, comprising at least one window which selectively communicates the working chamber with at least one of said internal passages so that the working gas flows selectively between the working chamber and the various resources. It also relates to an external hot source engine equipped with said slide. State of the prior art

[0002] External heat source engines, such as the Ericsson type, are experiencing renewed interest and development, with the aim of reducing pollutant emissions or reducing energy consumption by reusing heat discharges. This type of engine operates between two heat sources external to the engine via exchangers. It uses valves to control the flow of the working fluid (in the gas phase) between two chambers, one for compression and the other for expansion.

[0003] For volumetric machines such as internal combustion piston engines, distributions using cam-actuated valves are also known. This type of distribution has various limitations. In particular, the pressure on the face of the valve opposite the working chamber must be low. In addition, the maximum valve lift is low if the duration (measured in degrees of cam rotation angle) of valve opening is short. In addition, the cam drive consumes energy.

[0004] We also know volumetric machines, such as compressors, which use valve distribution. This solution requires that the pressure differential on each valve always has, at each stage of the machine's operating cycle, an appropriate value and direction so that the valve is in the state - open or closed - necessary at the stage in question in the cycle.

[0005] In certain volumetric machines with an external hot source, such as those described in the two patent applications FR 2 905 728 and FR 2 954 799, air taken from the atmosphere is admitted and compressed in a working chamber, then transferred into a hot source, and from there re-transferred into the same working chamber at the start of an expansion time of this chamber, producing mechanical energy collected by a piston, then evacuated to the atmosphere.

[0006] To be effective, the two transfers of working gas, from the working chamber to the hot source and then from said hot source to said working chamber, must be brief and take place through a passage section large enough to minimize pressure losses. These requirements are difficult to meet with cam-controlled valve distribution. Furthermore, this type of cycle is difficult to reconcile with valve distribution.

[0007] Patent application FR 3 069 884 discloses an external heat source engine comprising slide valves. Each slide valve is rotatably mounted in the cylinder head and has internal passages opening through its side wall by at least one mouthpiece which communicates selectively with the working chamber by at least one port made in the cylinder head. Each slide valve is made of a single piece. The slide valve offers a larger passage section for the working gas and makes it possible to reduce pressure losses between the working chamber and resources. Although satisfactory, this type of distributor has the following drawbacks: significant heat exchanges between the hot flow, coming from the hot end of an exchanger, entering the working chamber and the cold flow leaving the working chamber, reducing the capacity to extract heat from the hot resource, and a double valve effect in the path of the working gas with a discontinuity between a lumen of the cylinder head and a mouth of the valve on the one hand, and an orifice of the valve and a lumen of a connection of a resource on the other hand, not very conducive to the circulation of air between the working chamber and the hot resource.

[0008] He is keen to always improve the two gas transfers indicated above and / or to propose efficient technical solutions in order to achieve the two gas transfers in the engine and to increase its performance.

[0009] The present invention aims to provide an external heat source motor that can at least partially overcome the problems mentioned above. It also aims to provide a space-saving motor. Statement of the invention

[0010] According to a first aspect of the invention, at least one of the objectives is achieved with a slide valve for an external heat source engine of the type as defined by the claims. It comprises: at least one cylinder, a piston moving back and forth in the cylinder, a cylinder head defining, with the piston and the cylinder, a working chamber for a working gas, a distribution, comprising said valve, mounted in the cylinder head and selectively communicating the working chamber with different resources.

[0011] The valve is characterized in that it comprises two coaxial parts: a working gas guide part, comprising internal passages opening radially through at least one mouth which communicates selectively with the working chamber through at least one light made in the cylinder head, and a working gas distribution part, arranged on the periphery of the guide part and movable relative to the guide part, the distribution part comprising at least one window which selectively communicates the working chamber with at least one of said internal passages so that the working gas flows selectively between the working chamber and the different resources.

[0012] The slide valve according to the invention has the advantages of simultaneously limiting thermal losses and pressure losses, and of ensuring better continuity of flows between the working chamber and the hot resource, thus making it possible to improve the efficiency and / or performance of an external hot source engine equipped with said slide valve.

[0013] A plug is a cylindrical device comprising internal passages through which the working gas can circulate. An internal passage is, for example, a conduit. The plug is arranged such that its axis of rotation is perpendicular to the axis of the cylinder above which it is arranged. The plug is located between the working chamber and an exchanger along the path of the working gas. The plug presented here has the particularity of comprising two coaxial parts: a guide part and a distribution part surrounding the guide part. The rotary movement of one and / or the other of the guide part and the distribution part of the plug is / are synchronized with the reciprocating movement of the piston, so that the working gas can pass through the plug via the internal passages, and thus distribute the gas between the working chamber and the exchanger.Preferably, each internal passage communicates with at least two openings provided through the side wall of the guide portion of the slide, each opening being located at one of the two ends of the internal passage. At a certain stage of the cycle, the working gas flows between the working chamber and the cold inlet of the exchanger by passing through at least one port of the cylinder head, at least one internal passage of the guide portion of the slide and at least one opening of the distribution portion of the slide.

[0014] A mouthpiece is an opening located at one end of the guide portion of the slide. The mouthpiece selectively coincides with at least one port in the cylinder head. A window is an opening in the distribution portion of the slide. A window selectively coincides with at least one port and at least one mouthpiece. A window may coincide with at least one orifice. An opening located at another end of the guide portion of the slide is called an orifice. The orifice is located opposite the mouthpiece.

[0015] For the foregoing and for the remainder of the application, the terms mouth and orifice correspond to, or qualify, openings made through the side wall of the guide part of the slide. The term mouth is used to qualify each opening capable of communicating with the lumen of the cylinder head for the passage of the working gas from the working chamber to the slide or vice versa. A mouth is always made through the peripheral wall of the guide part, also called the circumferential wall. The term orifice is used to qualify each opening capable of communicating with a connector for the passage of the working gas from the slide to the connector or vice versa. An orifice may be made through the peripheral wall of the guide part, also called the circumferential wall, or through the transverse wall of the guide part. A mouth cannot serve as an orifice and vice versa.For this, in the case where the orifice is made on the peripheral wall of the guide part, the at least one mouthpiece is axially offset relative to the at least one orifice.

[0016] For the above and for the remainder of the application, the term window corresponds to, or qualifies, an opening made through the side wall of the distribution part of the slide. The term window is used to qualify each opening capable of communicating with the lumen of the cylinder head and a mouth, for the passage of the working gas from the working chamber to the slide or vice versa. In this case, the expression mouth window may be used. Furthermore, the term window is used to qualify each opening capable of communicating with an orifice and a connector, for the passage of the working gas from the slide to the connector or vice versa. In this case, the expression orifice window may be used. A window may be made through the peripheral wall of the distribution part, also called the circumferential wall, or through the transverse wall of the distribution part.

[0017] Finally, the adjectives "hot" and "cold" have a relative meaning, simply meaning that a hot element, for example a hot mouthpiece or a hot orifice, is generally hotter than a cold element, for example a cold mouthpiece or a cold orifice, during engine operation.

[0018] By side wall, when referring to the guide part or the distribution part, we mean on the one hand a peripheral wall, also called a circumferential wall, which extends along a cylindrical face of said part, or on the other hand a transverse wall, also called an axial face of said part, which extends along a flat face of said part.

[0019] The valve distribution system makes it possible to provide a large passage section for the working gas, in particular as soon as a mouthpiece begins to coincide with a window in the distribution part and with a port in the cylinder head. Since the rotation speed of the valve is substantially constant, the passage section increases rapidly, for example linearly, until the mouthpiece coincides perfectly with the port in the cylinder head.

[0020] The valve distribution allows the following four-stroke thermodynamic cycle to be carried out: a substantially cold working gas is admitted into the working chamber, said gas is compressed in said working chamber, then transferred into the exchanger in which a heat-transferring fluid (the hot source) circulates, so as to heat the working gas; the heated working gas is re-transferred into the working chamber at the start of an expansion time of the same working chamber; then the expansion continues and ends while the working chamber is isolated from the exchanger; and the working gas is escaped from the working chamber.

[0021] Thanks to the valve, the two aforementioned transfers of the working gas are brief and take place through a passage section large enough to minimize pressure losses.

[0022] Preferably, at least one lumen of the cylinder head is capable of communicating with two internal passages of the guide part of the slide which open through the peripheral wall of the guide part by two mouths aligned circumferentially, according to the angular position of the distribution part.

[0023] Said two internal passages are, one, a passage through which the working gas enters the working chamber, and the other, a passage through which the working gas leaves the working chamber.

[0024] For example, the bushel includes: an internal passage intended to circulate the cold and compressed working gas between the working chamber and the cold end of the exchanger, and an internal passage, separate from the previous one, intended to circulate the working gas, compressed and heated, between the hot end of the exchanger and the working chamber.

[0025] The working gas entering the exchanger is said to be "cold" in comparison with its higher temperature when it leaves the exchanger "hot". However, it must be understood that the "cold" working gas entering the exchanger is already heated by its compression in the working chamber. Similarly, the "cold" end of the exchanger is still at a temperature close to that of the working gas at the end of compression.

[0026] Preferably, the distribution is arranged so that, towards the end of compression, the working chamber begins to communicate with the cold end of the exchanger when the pressure in the working chamber is lower than the pressure in the exchanger. During operation of the engine and with reference to the cycle described above, the cold and compressed working gas and / or gas being compressed enters the guide part of the slide, which is fixed, as soon as at least one window of the rotating distribution part coincides simultaneously with a part of the mouth and with the light so as to circulate the cold and compressed working gas towards the cold end of the exchanger. The passage section between the working chamber and the mouth increases with the rotation of the distribution part of the slide. When the mouth of the slide coincides perfectly with the light of the cylinder head, the passage section is maximum.The majority, at least 50%, of the volume of cold and compressed working gas has then passed through said mouth. Then, due to the rotation of the guide part of the slide and the end of compression, only part of the mouth coincides with the port, so as to circulate the remaining part of the cold and compressed working gas towards the cold end of the exchanger. Simultaneously, the passage section between the working chamber and the second mouth, of the second internal passage, increases so that part of said mouth coincides with the same port. The working gas leaving the second mouth, and therefore entering the working chamber, comes from the hot end of the exchanger after having been heated. The working gas thus makes a loop passing through the same port of the cylinder head but through different internal passages of the slide.This results in the said lumen being larger, and thus further increasing the passage section offered to the gas to pass into and out of the exchanger. For a short time the cold working gas, leaving the working chamber, and the hot working gas, entering the working chamber, cross. This avoids an unfavorable phenomenon of relatively low pressure in the working chamber at the beginning of the expansion phase.

[0027] Preferably, the cross-section of the lumen is at least equal to the sum of the cross-sections of the hot and cold mouths. Preferably, the cross-section of the lumen is at least equal to the sum of the cross-sections of the hot and cold mouths and the cross-section of the wall separating the hot mouth from the cold mouth.

[0028] According to an exemplary embodiment, the two neighboring mouthpieces are circumferentially aligned and offset by an angle of between 5 and 15 degrees.

[0029] These values, as well as other angular values ​​provided subsequently, concerning the mouths, orifices and windows, are indicated for a rotation speed of the slide between 1000 and 3000 rpm (revolutions per minute), preferably between 2000 and 3000 rpm (revolutions per minute). Furthermore, the nominal pressure prevailing in the heat exchanger may be between 4 and 5 bar absolute and the heat-transfer fluid may have a temperature between 500°C and 900°C (degrees Celsius).

[0030] According to a preferred embodiment, the guide portion is fixed relative to the engine. Since the majority of the slide is static, the gases are on the one hand less disturbed when they flow in the slide. In addition, the heat of the hot gases is on the other hand less dissipated by convection and / or conduction of the internal and / or external surface of the internal passage(s) of the slide, or of the external surface of the slide facing the cylinder head. In particular, the heat of the hot gases is less dissipated by convection and / or conduction of the internal and / or external surface of the internal passage(s) of the slide facing the internal passage(s) in which cold gases flow. By hot gas relative to cold gas is meant a hot gas which has a higher temperature than that of a cold gas.This makes it possible to limit or avoid the reduction of the temperature difference between the hot part of the valve and the cold part of the valve; the principle of the motor lies in the temperature difference between the hot source and the cold source.

[0031] Finally, a synergistic effect is observed. As the gas flow is facilitated, heat dissipation is reduced. Compared to the prior art, the temperature difference between the hot gases and the cold gases within the engine is maximized, allowing for significantly improved efficiency, at least beyond the addition of the two effects taken separately.

[0032] Preferably, the guide portion comprises at least one orifice, arranged at the end of an internal passage opposite the at least one mouth, so that the internal passages open through a wall of the guide portion of the slide valve through the at least one orifice which allows the internal passage to communicate with a corresponding fixed connection. A fixed connection connects the engine with a resource, for example a cold or hot end of an exchanger.

[0033] According to a first embodiment, the at least one orifice is arranged on a peripheral wall of the guide part. This feature has the advantage of making the gases pass radially through the valve and thus makes it possible to limit the travel distance of the gases between the working chamber and the resources. According to one example, the guide part may comprise two orifices, a cold orifice and a hot orifice, arranged on the peripheral wall.

[0034] According to a second embodiment, the at least one orifice comprises two orifices: an orifice arranged on a peripheral wall of the guide part and an orifice arranged on a transverse wall of the guide part. Preferably, the at least one orifice comprises two orifices: an orifice, called a cold orifice, arranged on a peripheral wall of the guide part and an orifice, called a hot orifice, arranged on a transverse wall of the guide part. This characteristic has the advantage of limiting heat transfers between the internal passages, in which hot gases and cold gases flow respectively, from the internal passage containing a hot gas to an internal passage containing a cold gas or vice versa, due to the distance of the hot orifice from the cold orifice.

[0035] According to a third embodiment, the at least one orifice is arranged on a transverse wall of the guide part. This feature has the advantage of leaving the at least one orifice constantly open, and thus of limiting the pressure loss. The guide part may comprise two orifices, a cold orifice and a hot orifice, arranged on a transverse wall. According to a first example, the two orifices may be arranged on the same transverse wall, or the same axial face. According to a second example, each orifice is arranged on a separate opposite transverse wall.

[0036] Preferably, the dispensing portion is generally tubular in shape. The dispensing portion comprises at least one radially directed window arranged and configured to, during rotation of said portion, selectively align with at least one mouth of the guide portion of the valve.

[0037] According to one embodiment, the dispensing portion is generally tubular in shape, and the dispensing portion comprises at least one window arranged and configured to selectively align, during a rotation of said portion, with at least one orifice of the guide portion of the valve. According to an embodiment compatible with the first and second embodiments of the guide portion, the dispensing portion is generally tubular in shape, and the dispensing portion comprises at least one radially directed window arranged to selectively align with at least one mouthpiece, and at least one radially directed window arranged to align with at least one orifice.

[0038] The distribution part may further comprise, for a cylinder, a single radially directed window, selectively communicating one or other of two internal passages with the working chamber. In an embodiment in particular compatible with the third embodiment of the guide part, the distribution part comprises, for a cylinder, a single radially directed window.

[0039] According to one embodiment, the at least one mouthpiece comprises two mouthpieces for the same internal passage, capable of communicating simultaneously with the working chamber, via two ports. Each mouthpiece may coincide with a port. This characteristic is particularly advantageous in order to find a compromise between a large passage section for the flow of working gas, limiting the pressure drop of said flow and limiting leaks of working gas between the valve and the cylinder head.

[0040] For example, during the compression phase of the working gas and when it is conveyed to the cold end of the exchanger, the gas passes through the two openings of the high-pressure slide, crossing the two ports of the cylinder head so that the flow is divided into two to cross the two ports and the two openings, forming two flow lines. After the two openings, each flow line circulates in a conduit opening into a common conduit. The internal passage actually has the shape of a Y according to this particular embodiment.

[0041] Preferably, the lights and mouths have a rectangular shape to limit pressure losses.

[0042] Preferably, at least one of the mouths is subdivided by at least one mullion. This feature makes it possible to support sealing devices, placed on the cylinder head, when the at least one mouth passes in front of a port in the cylinder head. The mullions can be fitted to both the mouths of the low-pressure valve and those of the high-pressure valve.

[0043] For the above and for the remainder of the description, a mullion is understood to mean a bar intended to subdivide only the mouthpiece without projecting inside the plug (without subdividing the internal passage). It extends circumferentially to connect two longitudinal sides of a mouthpiece so as to extend the circumference of the plug.

[0044] According to one embodiment, at least one passage comprises two passages leading in parallel to the same resource, each capable of communicating simultaneously with a respective port of the cylinder head. This feature makes it possible to provide a large passage section for the working gas. For example, during the return of the working gas from the hot end of the exchanger, the flow of the working gas is divided into two flow lines, which circulate in two separate internal passages inside the valve. The two flow lines are divided before entering the two ports of the valve and join after leaving the two ports of the cylinder head.

[0045] According to one option, the guide portion comprises at least one cavity arranged between the internal passages of the guide portion, the cavity forming an axially directed pipe. This cavity may allow a gas to be introduced in order to heat the internal passages.

[0046] According to a second aspect of the invention, at least one of the objectives is achieved with an external heat source engine comprising: at least one cylinder, a piston moving back and forth in the cylinder, being connected to a drive shaft, a cylinder head defining, with the piston and the cylinder, a working chamber for a working gas, a distribution mounted in the cylinder head and selectively communicating the working chamber with the following resources: a working gas inlet, a cold end of a heat exchanger, a hot end of the heat exchanger, an exhaust, characterized in that it comprises at least a first slide valve arranged according to one or more of the characteristics of the first aspect.

[0047] According to optional improvements of the invention: the engine comprises a second valve, called low pressure, controlling the selective communication of the working chamber with the intake and the exhaust, the second valve comprising internal passages opening radially through at least one mouth which communicates selectively with the working chamber through at least one port made in the cylinder head, the second valve comprises a radially directed orifice and an axially directed orifice, each orifice being arranged at the end of the corresponding internal passage opposite its mouth, the second valve is a low pressure valve controlling the selective communication of the working chamber with the intake and the exhaust, and the first valve is a high pressure valve controlling the selective communication of the working chamber with the hot and cold ends of the exchanger;this characteristic makes it possible to simplify the construction of the engine by separating the so-called "high pressure" flows and the so-called "low pressure" flows and to reduce its size; the valves can have identical diameters, making it possible to simplify the construction of the engine; the valves can have different diameters, for example the first valve called high pressure can have a diameter greater than the diameter of the second valve called low pressure; this characteristic makes it possible to further enlarge the passage section of the internal passages, going to the exchanger and returning;the engine comprises means for driving one of the parts of the slide at a speed proportional to the speed of the engine shaft, the engine comprises means for driving the distribution part of the slide at a speed proportional to the speed of the engine shaft, the engine comprises, alternatively to the second slide, a valve distribution, of the type used for internal combustion engines, the engine comprises two fixed connections, a so-called "high pressure" connection and a so-called "low pressure" connection, the high pressure connection comprises a cold connection communicating with the cold end of the exchanger and a hot connection communicating with the hot end of the exchanger, the low pressure connection comprises an inlet connection, communicating with the inlet of the working gas, and an exhaust connection communicating with the exhaust of the working gas. ;

[0048] According to a preferred embodiment, the thermodynamic cycle is carried out in a single cylinder. The cylinder head, surmounting the working chamber, supports the high pressure valve and the low pressure valve, which are arranged parallel to each other when viewed parallel to the axis of the valve.

[0049] In other embodiments, the external heat source engine may include multiple cylinders such as an internal combustion engine. For example, the engine may include at least two cylinders. In this case, it may include some or all of the features described so far.

[0050] In the case of two or more cylinders, the valve is potentially the same for all cylinders which are arranged in line with each other. According to another embodiment, one valve is provided per cylinder.

[0051] Preferably, the engine includes sealing devices to limit gas leaks.

[0052] In one embodiment, the ports may be surrounded by sealing devices to close the gap between the peripheral wall of the valve and an adjacent surface of the cylinder head around each port. The sealing device may include strips of a dry friction material, e.g., graphite. For example, the strips are disposed around the ports of the cylinder head.

[0053] According to another embodiment, which may be compatible with the previous one, the mouthpieces may be surrounded by sealing devices to close the radial gap between the guide part and the distribution part of the valve.

[0054] According to another aspect of the invention, which may be compatible with the first aspect, there is provided a motor assembly comprising an engine according to one or more of the features set forth above and a heat exchanger having a heat-receiving path extending between a cold end and a hot end selectively connected to the working chamber towards the end of a compression phase and towards the beginning of an expansion phase, respectively. The working gas circulates in the heat-receiving path.

[0055] Preferably, the exchanger is of the counter-current type. The heat exchanger comprises a heat-transfer path through which a heat-transfer fluid flows in one direction, a direction which is opposite to the direction of travel of the working gas in the heat-receiving path. The heat-transfer path is separate from the heat-receiving path.

[0056] According to one embodiment, the heat exchanger comprises a heat-transfer path traveled by the exhaust gases of an internal combustion engine. According to another embodiment, the heat exchanger comprises a heat-transfer path traveled by a fluid heated by solar energy. Brief description of the drawings

[0057] Other advantages and particularities of the invention will appear on reading the detailed description of implementations and embodiments which are in no way limiting, and the following appended drawings: [ fig.1 ] there figure 1 includes two Figures 1a and 1b showing two schematic representations of an external heat source engine, comprising two slides, one low pressure slide, to the left of each of the Figures 1a and 1b , and a high pressure valve, to the right of each of the Figures 1a and 1b, comprising two coaxial parts according to the invention, a guide part and a distribution part, the high pressure slide being illustrated according to a first embodiment, in which the guide part comprises internal passages, each internal passage opening radially through a mouth and an orifice, the distribution part comprising a mouth window directed radially and arranged to selectively align with a mouth, and an orifice window directed radially and arranged to selectively align with an orifice, the engine being coupled with a heat exchanger, the engine and exchanger assembly being seen in section during two main phases of operation of the engine: the Figure 1a illustrating a phase of admission of a working gas into the engine cylinder, the Figure 1b illustrating a phase of gas escape from said cylinder; [ fig.2 ] there figure 2 includes three Figures 2a, 2b and 2cshowing three schematic representations of an engine conforming to the figure 1 , the engine and exchanger assembly also being seen in section during three main phases of engine operation: the Figure 2a illustrating an end phase of compression of the working gas and during which the gas is also directed towards a cold end of the heat exchanger, the Figure 2b illustrating a phase in which a slide valve has a so-called "sweeping" position which allows simultaneous fluid communication of the cold end and the hot end of the exchanger with the engine cylinder, the Figure 2c illustrating a phase of expansion of the working gas after its passage through the exchanger; [ fig.3 ] there figure 3is a sectional view of an engine comprising a low pressure slide, on the right of the figure, and a high pressure slide, on the left of the figure, comprising two coaxial parts, the sectional plane being perpendicular to the axes of the slides, the figure 3 illustrating an end phase of compression of the working gas and showing the position of the various moving parts including the angular position of the slides, in particular the angular position of the distribution part relative to the guide part of the high pressure slide, the position of the distribution part being such that a window is angularly offset by a few degrees relative to a cold mouth; [ fig.4 ] there figure 4 is a zoom of the high pressure valve of the figure 3 ; [ fig.5 ] there Figure 5 is a zoom of the high pressure valve in accordance with the Figures 3 and 4 , there Figure 5illustrating a position in which the window of the dispensing portion is centered relative to a cold mouthpiece; [ fig.6 ] there figure 6 is a zoom of the high pressure valve in accordance with the Figures 3 and 4 , there figure 6 illustrating a position in which the window of the dispensing part is angularly offset by a few degrees relative to a cold mouthpiece and also to a hot mouthpiece; [ fig.7 ] there figure 7 is a zoom of the high pressure valve in accordance with the Figures 3 and 4 , there figure 7 illustrating a position in which the window of the dispensing portion is centered relative to a hot mouthpiece; [ fig.8 ] there figure 8 is a zoom of the high pressure valve in accordance with the Figures 3 and 4 , there figure 8illustrating a position in which the window of the dispensing part is angularly offset by a few degrees relative to a hot mouth so that said window of the dispensing part no longer coincides with the hot mouth; [ fig.9 ] there figure 9 is an exploded perspective view of a high-pressure valve according to a second embodiment of the invention, the valve comprising a distribution part and a guide part, the guide part comprising two cold mouths and two hot mouths, the distribution part comprising only two windows, called mouth windows, the distribution part being provided to cover the guide part of the valve; [ fig.10 ] there figure 10 is an exploded perspective view of a bushel according to the same embodiment as the figure 9, the guide part comprising an orifice, called a cold orifice, arranged on the circumferential wall, the distribution part comprising a window, called an orifice window, arranged on the circumferential wall; [ fig.11 ] there figure 11 is a longitudinal sectional view of the engine having a high pressure slide valve according to the embodiment of the figures 9 and 10 , the cutting plane passing through the axis of said slide and through the axis of the piston, the figure 11 illustrating a phase during which the working gas is in communication with one of the cold ends of the heat exchanger; [ fig.12 ] there figure 12 is a zoom of the high pressure valve in accordance with the figures 9, 10 And 11, illustrating a phase in which the working gas is directed towards a cold end of the heat exchanger, or in which the working gas, coming from a hot end of the heat exchanger, is directed towards the working chamber; [ fig.13 ] there figure 13 is a zoom of the high pressure valve in accordance with the figures 9, 10 And 11 , illustrating a phase in which the working gas, coming from a hot end of the heat exchanger, is directed towards the working chamber, or, in which the working gas is directed towards a cold end of the heat exchanger; [ fig.14 ] there figure 14is an exploded perspective view of a high-pressure valve according to a third embodiment of the invention, the valve comprising a distribution part and a guide part, the guide part comprising two cold mouths and two hot mouths, the distribution part comprising two windows, called mouth windows, the distribution part being provided to cover the guide part of the valve; [ fig.15 ] there figure 15 includes two Figures 15a and 15b showing two perspective views of a guide part of a valve according to the embodiment of the figure 14 , in which two orifices are arranged on a transverse wall, the valve being provided for an engine comprising a cylinder, the Figure 15a showing the bushel in transparency so as to visualize the internal passages; [ fig.16 ] there figure 16is a longitudinal sectional view of an engine having a high pressure slide valve conforming to figures 14 And 15 , the cutting plane passing through the axis of said slide and through the axis of the piston, the figure 16 illustrating a phase in which the working gas is directed to a cold end of the heat exchanger. Description of the embodiments

[0058] Since these embodiments are in no way limiting, it will be possible in particular to consider variants of the invention comprising only a selection of characteristics described below isolated from the other characteristics described (even if this selection is isolated within a sentence comprising these other characteristics), if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art. This selection comprises at least one preferably functional characteristic without structural details, and / or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention compared to the state of the prior art.

[0059] THE Figures 1a, 1b, 2a, 2b and 2cillustrate the main operating phases of an external heat source engine 1, and will make it possible to describe the engine comprising slides according to one embodiment. The engine comprises: an engine block in which a cylindrical cavity called cylinder 2 is formed, a movable piston 3 arranged to move back and forth in the cylinder 2, a cylinder head 4 covering the engine block above the cylinder 2, a working chamber 5 being delimited for a working gas, typically air, in the cylinder 2 between the piston 3 and the cylinder head 4, a distribution mounted in the cylinder head 4, arranged and configured to selectively communicate the working chamber 5 with the following resources: an inlet A of working gas, a cold end B of a heat exchanger, a hot end C of the heat exchanger, an exhaust D.

[0060] The engine is connected to a heat exchanger 6 for heat exchange between the working gas, called the heat-receiving fluid, and a heat-discharging fluid. The heat exchanger 6 is of the counter-current type. It comprises a heat-discharging path 61 through which the heat-discharging fluid flows from left to right. It further comprises a heat-receiving path 62, shown below the heat-discharging path 61, with reference to Figures 1a to 2c , so that the working gas travels along the heat-receiving path from right to left. The heat-transferring path is distinct from the heat-receiving path. The heat-transferring fluid is, for example, the exhaust gases of an internal combustion engine.

[0061] The heat exchanger 6 is connected to the engine via fittings 60, see figures 11 And 16, and pipes so as to be able to circulate the working gas from the engine to the exchanger and vice versa. Similarly, one or more fittings or pipes are connected to the engine to carry out the intake and exhaust.

[0062] The distribution comprises two valves, a first valve 10, called the “high pressure” valve, and a second valve 30, called the “low pressure” valve, mounted in the cylinder head 4, above the working chamber 5. Each valve has the general shape of a cylinder. The axes of the two valves are parallel to each other and orthogonal to the axis of the cylinder 2. The low pressure valve 30 is arranged and configured to control the selective communication of the working chamber 5 with the intake A and the exhaust D. The high pressure valve 10 is arranged and configured to control the selective communication of the working chamber 5 with the hot C and cold B ends of the exchanger 6. Preferably, the high pressure valve 10 is used only to control the circulation of the working gas between the working chamber and the exchanger. Similarly, the low pressure slide 30 is used only to control the intake and exhaust.This feature makes it possible to simplify the construction of the engine by separating the so-called "high pressure" flows and the so-called "low pressure" flows and to reduce its size. The slides have, for example, but not necessarily, identical diameters, making it possible to simplify the construction of the engine. The low pressure slide 30 is made from a single block or from a single piece and is rotatably mounted in the cylinder head 4. The high pressure slide 10 is made in two coaxial parts: a so-called "guide" part 11 and a so-called "distribution" part 16. The guide part 11 has a generally cylindrical shape and is fixed relative to the cylinder head 4. The distribution part 16 has a generally tubular shape which surrounds the guide part 11 and which is rotatable relative to the guide part. The distribution part 16 of the high pressure slide is rotatably mounted in the cylinder head 4.Only the distribution part is rotating with regard to the high pressure slide.

[0063] Each valve 10, 30 comprises internal passages for conducting the working gas between the working chamber 5 and the resources. Each internal passage has two ends which open through the side wall of a valve, each through at least one opening. The distribution is arranged and configured so that the rotary movements of the valves are synchronized with the reciprocating movement of the piston, so that the working gas can pass through the valves via the internal passages. The openings are arranged and configured to selectively coincide with at least one port made in the cylinder head and at least one port made in a fixed connection. The mouth is called the opening opposite the port of the cylinder head when the working gas passes between the working chamber and the valve or vice versa. The orifice is called the opening opposite a connection when the working gas passes between the valve and said connection or vice versa.A mouthpiece cannot serve as an orifice and vice versa. For this, the orifices have an axial offset with the mouthpieces. The mouthpiece window is the opening opposite both a mouthpiece and a port when the working gas passes between the working chamber and the plug or vice versa. The orifice window is the opening opposite both an orifice and a connection when the working gas passes between the plug and said connection or vice versa.

[0064] According to one embodiment of an engine comprising a single cylinder, the low pressure slide comprises: for intake A, an internal passage comprising an intake mouth and an intake orifice, for exhaust D, an internal passage comprising an exhaust mouth and an exhaust orifice, the guide part of the high pressure slide comprises, according to any embodiment of the guide part: for the transfer of the working gas from the working chamber 5 to the cold end B of the exchanger 6, an internal passage comprising at least one cold mouth and at least one cold orifice, for the transfer of the working gas from the hot end C of the exchanger 6 to the working chamber 5, an internal passage comprising at least one hot mouth and at least one hot orifice, and the distribution part of the high pressure slide comprises, according to any embodiment of the distribution part, at least one window, called a mouth window, for the transfer of the working gas from the working chamber 5 to the cold end B of the exchanger 6, then for the transfer of the working gas from the hot end C of the exchanger 6 to the working chamber 5.

[0065] The valve distribution allows the thermodynamic cycle to be carried out, the main phases of which will now be described.

[0066] THE Figures 2a, 2b and 2c schematically illustrate an engine comprising a high pressure slide valve produced according to a particular embodiment; said Figures 2a, 2b and 2c showing a high pressure valve comprising two mouths and two orifices arranged on the peripheral wall of the guide part of the high pressure valve.

[0067] According to a first embodiment similar to that of the figure 9, the high pressure valve comprises two cold mouths 21 and two hot mouths 22 arranged on the peripheral wall of the guide part 11, and two mouth windows 17 arranged on the peripheral wall of the distribution part 16, each window 17 being provided to successively superimpose above a cold mouth 21 then a hot mouth 22, during operation. According to one embodiment, the guide part comprises a single cold mouth and a single hot mouth, and the distribution part comprises a single mouth window.

[0068] There figure 10 , shows a high pressure valve conforming to the figure 9, pivoted through an angle of approximately 180 degrees, comprising a cold orifice 23 arranged on the peripheral wall of the guide part 11, and an orifice window 19, called the cold orifice window, arranged on the peripheral wall of the distribution part 16, said window being provided to overlap said orifice during operation. According to the first embodiment not shown, but similar to that of the figure 10 , the high pressure valve comprises two ports, a cold port 23 and a hot port 24 (see Figure 2c ), arranged on the peripheral wall of the guide part 11, and two orifice windows 19, a cold orifice window 19c (see Figures 2a, 2b ) and a 19h hot orifice window (see Figures 2b and 2c), arranged on the distribution part. The cold orifice 23 is axially offset relative to the cold 21 and hot 22 mouths. The hot orifice is axially offset relative to the cold 21 and hot 22 mouths. This arrangement is not limiting. Other arrangements of the orifices on the guide part will be described in more detail below.

[0069] In addition, the figures 3, 4 , 5, 6 , 7 and 8 illustrate a first high pressure slide valve according to one embodiment and seen in section. These figures make it possible to show the rotation of the distribution part of the high pressure slide valve relative to the guide part of said slide valve and relative to the cylinder head of the engine, during operation of the engine in addition to the Figures 1a, 1b, 2a, 2b and 2c In particular, the angular displacement of a mouth window 17 is shown, relative to the cold 21 and hot 22 mouths and relative to the lumen of the breech.

[0070] In reference to the Figure 1a, the phase of admission of a working gas into the working chamber 5 is illustrated. The synchronization of the piston 3 and the slides 10, 30 is such that the movement of the piston 3 is downward while the rotation of the low pressure slide 30 allows an inlet mouth 32 of the low pressure slide to communicate with a port of the cylinder head and simultaneously allows an inlet orifice 34 to communicate with a port of an inlet connection. The working gas passes through the internal passage between the inlet orifice 34 and the inlet mouth 32 so as to be admitted into the working chamber 5. Simultaneously, no mouth of the high pressure slide communicates with a port of the cylinder head. The working gas is preferably air taken from the external environment.When the piston has reached bottom dead center, the low pressure slide 30 has pivoted so that the intake mouth 32 of the low pressure slide no longer communicates, even partially, with a port in the cylinder head (excluding any possible delay in intake closure).

[0071] Then the piston moves up so that the trapped working gas is compressed in the working chamber. With reference to the Figures 3 and 4 , the synchronization of the piston 3 and the distribution part 16 of the high pressure slide 10 is such that the movement of the piston 3 is upward while the rotation of the distribution part 16 is clockwise. The distribution part comprises a window, called the mouth window 17. With reference to the figure 4, the mouth window 17, the opening length of which is represented by a dotted arc of a circle, is located in an angular position offset by a few degrees relative to the cold mouth 21, the opening length of which is represented by an arrow with two opposite points, and relative to the light 41 of the breech, so that a part of said window begins to be inserted between the cold mouth 21 and said light 41.

[0072] In reference to the Figure 2a , a phase of end compression of the working gas is illustrated. The synchronization of the piston 3 and the slides 10, 30 is such that the movement of the piston 3 is upward while the rotation of the distribution part 16 of the high pressure slide 10 allows the mouth window 17 to be interposed radially between a light of the cylinder head and a cold mouth 21. With reference to the Figure 5, the mouth window 17 is centered relative to the opening of the cold mouth 21. This position has the effect of making the cold mouth 21 of the guide part communicate with the lumen of the cylinder head so that the working gas enters the associated internal passage. Simultaneously, the synchronization allows a window, called the cold orifice window 19c, to be inserted between the cold orifice 23 and a lumen of a connection of the cold end B of the exchanger 6. This position has the effect of making the cold orifice 23 communicate with the lumen of a connection of the cold end B of the exchanger 6 so that the working gas enters said connection. The working gas passes through the internal passage between the cold mouth 21 and the cold orifice 23 so as to be transferred to the exchanger 6 to be heated. At the same time, no mouth of the low pressure slide communicates with a port in the cylinder head.The synchronization of the distribution part 16 of the high pressure slide with respect to the rise of the piston during compression is adjusted so as to limit an unfavorable phenomenon of relatively high pressure in the working chamber.

[0073] In reference to the Figure 2b , the synchronization of the piston 3 and the slides 10, 30 is such that the piston 3 is located at top dead center, or a position close to top dead center, while the rotation of the distribution part of the high pressure slide 10 allows the mouth window 17 to position itself circumferentially simultaneously in partial face-to-face with the cold mouth 21 and in partial face-to-face with the hot mouth 22, so as to achieve a double circulation of working gas inside the high pressure slide. With reference to the figure 6, the mouth window 17 is located circumferentially between the cold mouth 21 and the hot mouth 22 so that said window 17 overlaps the wall separating the cold internal passage from the hot internal passage. The cold mouth 21 and the hot mouth 22 of the guide part 11 each coincide at least partially with the same light 41 of the cylinder head.

[0074] Simultaneously, the synchronization allows the cold port window 19c to be positioned partially opposite the cold port 23 and partially with the same lumen of a connection of the cold end B of the exchanger 6, as previously. An internal so-called cold passage of the guide part allows the working gas to be transferred from the working chamber to the exchanger 6, via the cold end B.

[0075] Furthermore, simultaneously the synchronization allows an orifice window, called hot orifice window 19h, to be positioned partially opposite a hot orifice 24 and a light of a connection of the hot end C of the exchanger 6, so as to make the hot orifice 24 coincide at least partially with a light of a connection of the hot end C of the exchanger 6. An internal passage called hot, distinct from the internal cold passage, allows the working gas to be transferred from the exchanger 6, via the hot end C, to the working chamber 5.

[0076] Communication between the cold end B and the hot end C of the exchanger is then established so that a portion of the incoming working gas and a portion of the outgoing working gas come into contact and cross. Working gas still passes through the internal passage between the cold mouth 21 and the cold orifice 23, and working gas passes through the internal passage between the hot orifice 24 and the hot mouth 22. The volume of gas previously compressed is in fact distributed in the path between the cold end B and the hot end C of the exchanger 6, the working gas being heated by the heat-transfer fluid present in the heat-transfer path 61 of the exchanger 6. The heated working gas leaving the hot mouth 22 begins to expand. Simultaneously, no mouth of the low-pressure valve communicates with a port in the cylinder head.

[0077] Then the heated working gas coming out of the high pressure valve expands in the working chamber. With reference to the Figure 2c , the synchronization of the piston 3 and the high pressure slide 10 is such that the movement of the piston 3 is downward while the rotation of the distribution part 16 of the high pressure slide 10 allows the mouth window 17 to be interposed radially between the light 41 of the cylinder head and the hot mouth 22 of the guide part. With reference to the figure 7 , the mouth window 17 is centered relative to the opening of the hot mouth 22. This position has the effect of making the hot mouth 22 of the guide part communicate with the light 41 of the cylinder head so that the working gas can exit the hot internal passage to enter the working chamber.

[0078] Simultaneously, the synchronization of the engine allows the hot orifice window 19h to be inserted between the hot orifice 24 and the port of a connection of the hot end C. This position has the effect of making the hot orifice 24 communicate with the same port of a connection of the hot end C of the exchanger 6. The working gas passes through the internal passage between the hot orifice 24 and the hot mouthpiece 22 so as to be transferred from the exchanger 6 to the working chamber to be expanded.

[0079] Simultaneously, no mouth of the low pressure slide communicates with a port of the cylinder head. Once the piston has reached bottom dead center, no mouth of the high pressure slide communicates with a port of the cylinder head. According to one embodiment, no mouth of the high pressure slide communicates with a port of the cylinder head before the piston reaches its bottom dead center.

[0080] In reference to the Figure 1b , a working gas exhaust phase is illustrated. The synchronization of the piston 3 and the slides 10, 30 is such that the movement of the piston 3 is upward while the rotation of the low pressure slide 30 allows an exhaust mouth 31 of the low pressure slide to communicate with a port of the cylinder head and simultaneously allows an exhaust port 33 to communicate with a port of an exhaust connection. The working gas passes through the internal passage between the exhaust mouth 31 and the exhaust port 33 so as to be expelled from the working chamber 5. Simultaneously, no mouth of the high pressure slide communicates with a port of the cylinder head. With reference to the figure 8 , the clockwise rotation of the distribution part is such that the mouth window 17 is angularly offset by a few degrees so that the latter is no longer and is not opposite, even partially, the hot mouth 22. The working gas is discharged into the external environment. When the piston has reached top dead center, the low pressure slide has pivoted so that the exhaust mouth 31 of the low pressure slide no longer communicates, even partially, with a port of the cylinder head (excluding any possible exhaust closure delay).

[0081] Thanks to the slide valve, the working gas transfers are brief and take place through a passage section large enough to minimize pressure losses. In addition, heat transfers between the working gas and the walls of the high-pressure slide valve are minimized, in particular concerning the gas coming from the hot end of the exchanger and heading towards the working chamber. Furthermore, since the thermodynamic cycle can be carried out in a single cylinder, the engine has a very small footprint compared to the external heat source engine of the prior art.

[0082] Furthermore, the hot mouthpieces 22 and the cold mouthpieces 21 are spaced apart along the circumference of the valve by a very small angular displacement, for example 5 to 15 degrees. The angular displacement is chosen so that a port 41 can communicate simultaneously with a cold mouthpiece and a hot mouthpiece.

[0083] For example, each hot mouthpiece has, along the circumference of the plug, an angular opening of between 20 and 50 degrees, preferably between 25 and 35 degrees. Given that the engine produces four main phases and that the internal passages are separated by walls of non-zero thickness, these values ​​are chosen according to a compromise between the need for a large passage section of the working gas flow, the reduction of pressure losses and the size (diameter and length of the plug). Each cold mouthpiece has, along the circumference of the plug, an angular opening of, for example, between 10 and 40 degrees, preferably between 20 and 30 degrees.

[0084] Furthermore, each light has, along the circumference of the receiving surface 40, an angular opening of, for example, between 15 and 30 degrees.

[0085] Preferably, each orifice has, along the circumference of the valve, an angular opening of between 100 and 350 degrees, preferably between 120 and 150 degrees.

[0086] Two other specific embodiments of the high pressure valve will now be described, which will be described in their differences with the above embodiment. The two high pressure valves described below are arranged to cooperate with a single cylinder, see figures 11 And 16 .

[0087] In reference to the figures 9, 10 , 11, 12 And 13 , a second embodiment of a high pressure valve of the type comprising a guide part having a radial cold orifice and an axial hot orifice is shown.

[0088] The high-pressure slide valve 10 comprises a guide portion 11 having the shape of a cylinder. The guide portion comprises a base arranged at one end, in order to fix it to the cylinder head. The guide portion 11 comprises on its peripheral surface two mouths, called cold mouths 21, adjacent and axially aligned. It further comprises two other mouths, called hot mouths 22, adjacent and axially aligned. The cold mouths 21 are circumferentially aligned with the hot mouths 22. The mouths have a rectangular shape. The cold and hot mouths each have a substantially rectangular shape whose longitudinal dimension extends in a direction which is parallel to the axis of the slide valve. The shape and the opening dimensions of the cold mouths are substantially identical to the shape and the opening dimensions of the hot mouths.

[0089] The high-pressure valve 10 comprises a distribution part having the shape of a tube. The distribution part comprises a pivot shaft 26 which is arranged at one end of said distribution part. The distribution part comprises on its peripheral surface two windows, called mouth windows 17, aligned axially. The mouth windows 17 have a shape and opening dimensions substantially identical to the shape and dimensions of the mouths. Furthermore, the axial spacing of the windows is identical to that of the mouths 21, 22.

[0090] There figure 10 represents the bushel of the figure 9 angularly rotated by approximately 180 degrees. The guide part 11 comprises on its peripheral surface a single orifice, called cold orifice 23. With regard to the figure 9 , the cold orifice 23 is axially offset relative to the cold 21 and hot 22 mouths. The cold orifice 23 has a rectangular shape whose longitudinal dimension extends in a direction which is orthogonal or circumferential to the axis of the plug. The distribution part 16 comprises on its peripheral surface, a window, called the orifice window 19. The orifice window 19 has a shape and opening dimensions substantially identical to the shape and opening dimensions of the hot orifice.

[0091] In reference to the figures 9, 10 , 11, 12 And 13 the distribution part is intended to cover and surround the guide part.

[0092] THE figures 11, 12 And 13 represent the path of the internal passages of the guide part of the high pressure valve in accordance with figures 9 et 10 . Furthermore, the guide portion comprises a hot orifice 24 opening onto a transverse end, or axial face, of the guide portion.

[0093] In the foreground of the figures 11 et 12 , the path of two conduits extending from two cold mouths 21 is shown. The two conduits join to form a single conduit up to the cold orifice 23, forming the internal cold passages. As the figures 11 et 12 each illustrate a phase of transfer of working gas to the cold end of an exchanger, such as the figure 2a , the mouth windows 17 coincide with the cold mouths 21, and the orifice window 19 coincides with the cold orifice 23. In the background, the hot internal passages are shown.

[0094] In reference to the figure 13 , it is shown, in the foreground, the path of two conduits extending from two hot mouths 22. The two conduits join to form a single conduit up to the hot orifice 24, forming the hot internal passages. In the background, the cold internal passages are shown.

[0095] This embodiment has the advantage of further separating the hot flows from the cold flows and thus minimizing heat transfers between these two flows.

[0096] According to an alternative embodiment not shown, the high pressure valve comprises a guide part having an axial cold orifice and a radial hot orifice.

[0097] In reference to the figures 14 , 15 et 16 , a third embodiment of a high pressure valve of the type comprising a guide part having an axial cold orifice and an axial hot orifice is shown. This embodiment will be described in its differences with the above embodiment.

[0098] The cold 23 and hot 24 orifices are each arranged on a transverse face or end of the guide part 11. The path of the cold and hot internal passages is respectively such that conduits extend from two mouths and join to form a single conduit which opens at an axial end of the guide part 11, see figure 16 . In reference to the figure 15 , the internal hot and cold passages are arranged in the guide part in a substantially symmetrical manner with respect to a plane passing through the axis of the guide part.

[0099] In reference to the figure 14 , the absence of a radially arranged orifice makes it possible to produce a high-pressure valve of a shorter length than other embodiments. In addition, the distribution part only comprises mouth windows.

[0100] According to a particular embodiment and with reference to the figure 14 , each mouthpiece comprises a mullion 25 dividing the mouthpiece opening in two. In this case, two conduits extend from one mouthpiece, see figures 15 et 16 .

[0101] According to one embodiment, compatible with the three embodiments of the high pressure valve, the distribution part 16 is driven in rotation by a pulley 28 which sets the distribution part 16 in motion by means of the pivot shaft 26, see figures 11, 12 , 13 And 16 .

[0102] According to a particular embodiment, compatible with the three embodiments of the high pressure valve, the guide part 11 comprises a cavity 27 arranged between the hot and cold internal passages, see the figures 11 And 16 . The cavity 27 is intended to receive and store a hot gas. This characteristic makes it possible to maintain the highest possible temperature for the working gases coming from the hot end of the exchanger and heading towards the working chamber.

[0103] Preferably, the high pressure valve comprises sealing devices arranged between the guide portion and the distribution portion. With reference to the figures 5 à 8 , the sealing devices have the shape of a plate curved in an arc of a circle so as to be inserted between the guide part and the distribution part. Each sealing device comprises a notch at each end so as to produce a central excess thickness which is intended to be arranged in a sealing device housing 13 arranged on the peripheral surface of the guide part, see figures 9 And 14 .

Claims

1. Slide valve (10) for an engine (1) with an external heat source of the type comprising: - at least one cylinder (2), - a piston (3) capable of reciprocating in the cylinder (2) - a cylinder head (4) defining, with the piston (3) and the cylinder (2), a working chamber (5) for a working gas, - a valve train, comprising said slide valve, mounted in the cylinder head (4) and selectively bringing the working chamber into communication with different resources, characterized in that the slide valve (10) comprises two coaxial portions: - a portion (11) for guiding the working gas, comprising at least two internal passages, each opening radially through at least one opening (21, 22) which communicates selectively with the working chamber (5) through at least one port (41) provided in the cylinder head (4), said at least two internal passages comprising a first internal passage comprising at least one cold opening (21) and at least one radial cold orifice (23) and a second internal passage comprising at least one hot opening (22) and at least one axial hot orifice (24), said radial cold orifice (23) being arranged on a peripheral wall of the guide portion (11) and said hot orifice (24) being arranged on a transverse wall of the guide portion (11), and - a portion (16) for distributing the working gas, arranged at the periphery of the guide portion (11) and movable relative to the guide portion (11), the distribution portion comprising at least one window (17) which selectively brings the working chamber (5) into communication with at least one of said internal passages so that the working gas flows selectively between the working chamber (5) and the different resources, said at least one window (17) being designed to be superposed successively above said at least one cold opening (21) and then said at least one hot opening (22), during operation.

2. Slide valve (10) according to claim 1, characterized in that the guide portion (11) is fixed relative to the engine (1).

3. Slide valve (10) according to one of claims 1 or 2, characterized in that the distribution portion (16) is generally tubular in shape, and in that the distribution portion (16) comprises at least one window (17) arranged and configured to selectively align, during a rotation of said portion, with at least one orifice (23, 24) of the guide portion (11) of the slide valve.

4. Slide valve (10) according to claim 1, characterized in that the distribution portion (16) is generally tubular in shape, and in that the distribution portion (16) comprises at least one radially directed window (17) arranged to selectively align with at least one opening (21, 22), and at least one radially directed window (17) arranged to align with at least one orifice (23, 24).

5. Slide valve (10) according to one of claims 1, characterized in that the distribution portion (16) is generally tubular in shape.

6. Slide valve (10) according to one of the preceding claims, characterized in that the distribution portion (16) comprises at least one radially directed window (17) arranged and configured to, during a rotation of said portion, selectively align with at least one opening (21, 22) of the guide portion (11) of the slide valve.

7. Slide valve (10) according to one of claims 1 to 5, characterized in that the distribution portion (16) comprises, for a cylinder (2), a single radially directed window (17), selectively bringing one or other of two internal passages into communication with the working chamber (5).

8. Slide valve (10) according to one of the preceding claims, characterized in that the guide portion (11) comprises at least one cavity (27) arranged between the internal passages of the guide portion (11), the cavity (27) forming an axially directed channel.

9. Engine (1) with an external heat source, comprising: - at least one cylinder (2), - a piston (3) capable of reciprocating in the cylinder (2), connected to a crankshaft, - a cylinder head (4) defining, with the piston (3) and the cylinder (2), a working chamber (5) for a working gas, - a valve train mounted in the cylinder head (4) and selectively bringing the working chamber (5) into communication with the following resources: - an intake (A) for working gas, - a cold end (B) of a heat exchanger (6), - a hot end (C) of the heat exchanger (6), - an exhaust (D), characterized in that it comprises at least one first slide valve (10) arranged according to one of the preceding claims.

10. Engine (1) according to the preceding claim, characterized in that it comprises a second slide valve (30), referred to as low-pressure slide valve, controlling the selective communication between the working chamber (5) and the intake (A) and exhaust (D), the second slide valve (30) comprising internal passages opening radially through at least one opening (31, 32) which communicates selectively with the working chamber (5) through at least one port (41) provided in the cylinder head (4).