EP3899236A1

EP3899236A1 - Beta-type stirling machine

Info

Publication number: EP3899236A1
Application number: EP19823912.1A
Authority: EP
Inventors: Sylvie BEGOT; Steve DJETEL-GOTHE; Hakeem KHIRZADA; François LANZETTA; Guillaume LAYES; Philippe NIKA
Original assignee: Universite de Franche-Comte
Current assignee: Universite de Franche-Comte
Priority date: 2018-12-20
Filing date: 2019-12-17
Publication date: 2021-10-27
Also published as: WO2020127295A1; US20220065193A1; BR112021011943A2; US11952960B2; WO2020127292A1; CA3124288A1; CN113454324A; EP3899235A1

Abstract

The invention relates to a beta-type Stirling machine (1) capable of operating in an engine mode or in a heat pump mode. The Stirling machine has a cold section (3) and a hot section (2), a displacement piston (6) comprising a friction zone (9), and an engine piston (7) comprising a friction zone (10). The Stirling machine has a single liner (8) arranged in the cold section of the Stirling machine operating in the engine mode or in the heat pump mode, wherein the friction zones of said displacement piston and engine piston slide within said single liner.

Description

Beta type Stirling machine

Technical area

The present invention relates to the field of machines providing external heat. In particular, these machines can be used in motor mode, or in receiver mode in operation in refrigeration mode or in operation in heat pump mode.

The invention relates in particular to Stirling beta type machines.

State of the art

Known in the prior art are motors, refrigeration machines and Stirling beta type heat pumps. There are known in the state of the art work aimed at improving the seal between the compression zone and the expansion zone of the Stirling machine. On the other hand, little conclusive work is known concerning the minimization of direct heat conduction between the cold source and the hot source of the Stirling machine. Indeed, most of the progress made in Stirling machines of the state of the art relates to sealing.

An object of the invention is in particular to:

- reduce heat exchange by conduction between the hot and cold parts of the Stirling machine, and / or

- reduce the dead volumes present in the Stirling machine, and / or

- reduce the pressure losses during the circulation of the working gas in the Stirling machine,

- improve the cooling in the friction zones of the Stirling machine.

Presentation of the invention

To this end, a beta type Stirling machine is proposed which can operate in engine mode or in heat pump mode or in refrigeration mode, said Stirling machine comprising:

- a cold part and a hot part,

- a displacement piston comprising a friction zone,

- an engine piston comprising a friction zone. The Stirling machine comprises a single jacket disposed in the cold part of the Stirling machine operating in engine mode or in heat pump mode, or respectively in the hot part of the Stirling machine operating in refrigeration mode, and in which the friction zones slide. of the displacing piston and the driving piston.

In the present application, the term “Stirling machine” designates a Stirling machine of the beta type that can operate both in engine mode and in receiver mode (that is to say in refrigeration machine or heat pump operation).

In the present application, when no operating mode of the Stirling machine is specified (engine mode or cooling mode or heat pump mode), the engine operating mode is considered to be the default operating mode. In this case, it is understood that the characteristic of the Stirling machine described corresponds to operation in engine mode. Consequently, a part, or an element, considered of the Stirling machine operating in engine mode which exerts a function different from a function exercised by the same part, or the same element, considered of the Stirling machine operating in another mode, can be transposed by the function of the part, or element, considered corresponding to the other operating mode of the Stirling machine by making the changes specified below.

Regarding the cold and hot parts of the Stirling machine. When the Stirling machine is operating in engine mode, the part located on the side of a housing of the Stirling machine is the cold part and the part situated on the side of the Stirling machine opposite the housing is the hot part. The cold part of the Stirling machine operating in engine mode corresponds to the cold part of the Stirling machine operating in heat pump mode and corresponds to the hot part of the Stirling machine operating in refrigeration mode. Similarly, the hot part of the Stirling machine operating in engine mode corresponds to the hot part of the Stirling machine operating in heat pump mode and corresponds to the cold part of the Stirling machine operating in refrigeration mode.

Concerning the compression and expansion zones of the Stirling machine. When the Stirling machine is operating in engine mode, the part located on the side of a Stirling machine housing is the compression zone and the part located on the side of the Stirling machine opposite the housing is the expansion zone. The compression zone of the Stirling machine operating in engine mode corresponds to the compression zone of the Stirling machine operating in refrigeration mode and corresponds to the expansion zone of the Stirling machine operating in heat pump mode. Similarly, the expansion zone of the Stirling machine operating in engine mode corresponds to the expansion zone of the Stirling machine operating in refrigeration mode and corresponds to the compression zone of the Stirling machine operating in heat pump mode.

When we consider the element of the Stirling machine defined as the heater, or respectively the cooler, of the Stirling machine. The element of the Stirling machine in which a gas traveling from the passageways of the single jacket passes to the compression volume of the Stirling machine operating in engine mode or in refrigeration mode, or vice versa, is a cooler. The element of the Stirling machine in which a gas traveling from the passageways of the single jacket passes to the expansion volume of the Stirling machine operating in heat pump mode, or vice versa, is a heater.

When we consider the part of the Stirling machine located on the side opposite the casing which can be defined as the exchanger of the Stirling machine. The part of the Stirling machine located on the side opposite the casing is the hot exchanger of the Stirling machine operating in engine mode or in heat pump mode, or respectively is the cold exchanger of the Stirling machine operating in refrigeration mode.

The only shirt can be a dry shirt.

The single shirt can be a single piece.

The single shirt can be made in one piece and / or in the same material.

The single shirt can be placed entirely in the cold part of the Stirling machine.

The single jacket can form part of a cylinder of the Stirling machine located in the cold part of the Stirling machine. The single jacket can extend along the races of the friction zones of the displacing piston and the driving piston.

By friction zones of the displacing piston and of the driving piston, it is understood the zone of friction of the displacing piston with the single jacket and the zone of friction of the piston with the single jacket.

A zone of the single jacket having no friction may be situated between the zone of friction of the displacing piston with the single jacket and the zone of friction of the piston with the single jacket.

The single jacket can extend only along the races of the friction zones of the displacing piston and the driving piston.

The jacket can extend beyond the races of the friction zones of the displacing piston and / or of the driving piston.

The single jacket can extend from a lower end of travel of the friction zone of the driving piston, said end of the casing of the single jacket, said lower end of travel of the friction zone of the driving piston being situated on the side of a crankshaft of the engine piston, up to an upper end of travel of the friction zone of the displacing piston, said separation end of the single jacket, said upper end of travel of the friction zone of the displacing piston being situated on the side d 'an exchanger.

The hot exchanger can be located on the side of an expansion zone of the Stirling machine operating in engine mode or in refrigeration mode, or respectively on the side of a compression zone of the Stirling machine operating in heat pump mode.

The exchanger can be a hot exchanger when the Stirling machine is operating in engine mode or in heat pump mode, or respectively a cold exchanger when the Stirling machine is operating in refrigeration mode.

The single jacket may extend from a lower end of travel of an end portion of the engine piston, said end of the housing of the single jacket, said lower end of travel of the end portion of the engine piston being located on the side of the crankshaft of the engine piston. The upper limit switch of a terminal part of the displacer piston located on the side of the hot exchanger is preferably located in the hot exchanger.

Preferably, the hot exchanger forms an end part of the hot part of the Stirling machine. Preferably, the hot exchanger forms an end part of the cylinder.

The single jacket may include conduits for the passage of a gas moving from a compression volume of the Stirling machine operating in engine mode or in refrigeration mode, or respectively an expansion volume of the Stirling machine operating in heat pump mode, towards a cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively a heater of the Stirling machine operating in heat pump mode, or vice versa, said passage conduits passing through the single jacket. The passage conduits can extend according to the thickness of the single jacket.

The compression volume is located between the displacing piston and the driving piston. When the engine piston is at the upper end of travel, the displacer piston is at mid-stroke. There is an angle of the cycle where the compression volume is minimal.

Preferably, the passage conduits can be located in a zone of the jacket, called compression zone, situated between the upper end of travel of the driving piston and the lower end of travel of the displacing piston.

Preferably, the passage conduits can be distributed annularly in the compression zone.

Preferably, said passage conduits passing through the single jacket are located at an area of the single jacket that does not have friction.

The cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the Stirling machine operating in heat pump mode may be, at least in part, preferably integrally, in direct contact with the single jacket and may surround, at least in part, preferably integrally, the single jacket, said one of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the Stirling machine operating in heat pump mode, being entirely included in the cold part of the Stirling machine operating in engine mode or in heat pump mode, or respectively in the hot part of the Stirling machine operating in refrigeration mode.

The cooler can be arranged to convey a gas from the passageways of the single jacket towards the hot part of the Stirling machine, or vice versa, and cool the gas in question during its passage through the cooler.

Gas can be understood as a mixture of gases.

The cooler can be arranged to convey a gas from the passageways of the single jacket to a regenerator of the Stirling machine, or vice versa, and cool the gas in question during its passage through the cooler.

An inner wall of the cooler may be, at least in part, preferably integrally, in direct contact with the single jacket and may surround, at least in part, preferably integrally, the single jacket, said cooler being entirely included in the cold part of the Stirling machine. The inner wall of the cooler is located on the side of the single jacket.

The cooler may include one or more gas flow paths. Preferably, the cooler comprises gas flow paths.

The cooler flow path (s) may be, in part, delimited by the inner wall of the cooler.

The cooler flow path (s) may be, at least in part, preferably integrally, in direct contact with the single jacket and may surround, at least in part, preferably integrally, the single jacket, said cooler being fully understood in the cold part of the Stirling machine. The flow path, or flow paths, of the cooler may be, in part, delimited by an outer wall, or parts of the outer wall, respectively, of the single jacket. The outer wall of the single jacket is located on the side of the cooler. The cooler can be in direct contact with the single jacket and can extend from the passage conduits towards the hot part.

The cooler can be in direct contact with the single jacket and can extend from the passage conduits to a separation end of the jacket with the hot part.

The cooler can surround the single jacket over an area extending from the separation end of the jacket with the hot part to the passageways of the single jacket.

The single jacket and the cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the machine of the Stirling machine operating in heat pump mode, may be inserted, at least in part, preferably integrally, in a housing until they are supported on the shoulders of the housing.

The casing may include, among other things, the connecting rods of the engine and displacer pistons, and the crankshaft.

The housing may include a single shoulder or shoulders for the single jacket and a single shoulder or shoulders for the cooler. The single shoulder or the shoulders for the cooler may be different from the single shoulder or the shoulders for the single jacket.

The Stirling machine may comprise a head forming, at least in part, preferably integrally, the hot part of the Stirling machine operating in engine mode or in heat pump mode, or respectively of the cold part of the Stirling machine operating in refrigeration mode , at least part of one end of said head, said end of separation of the head, preferably the entire end of separation of said head, is, in part, supported on the end of separation of the single jacket and, in part, pressing on a part of the cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively on a part of the heater of the Stirling machine operating in heat pump mode, said end of separation of the cooler from the Stirling machine operating in engine mode or in refrigeration machine mode, or respectively said end of separation of the heater from the Stirling machine operating in heat pump mode.

The term "in support" can mean direct contact.

The part of the head resting on the separation end of the single jacket and the part of the head resting on the separation end of the cooler can form the entire separation end of said head.

Preferably, no friction occurs between the displacer piston and the head.

The head can constitute part, preferably integrally, the hot part of the Stirling machine.

Preferably, the head forms a part of the cylinder arranged in the hot part of the Stirling machine.

Preferably, the head comprises a hot exchanger. The hot heat exchanger can form part of the head.

Preferably, an end portion of the head forms at least in part, preferably integrally, the hot exchanger.

The Stirling machine can comprise a regenerator extending from the separation end of the head to one or more end portions, called regenerator, of one or more gas passage channels moving from the expansion volume of the Stirling machine operating in engine mode or in refrigeration mode, or respectively from the compression volume of the Stirling machine operating in heat pump mode, up to the regenerator, or vice versa.

The passage channel (s) may be provided in a wall of the head separating the cylinder from the outside of the Stirling machine.

The regenerator can be sandwiched between two walls of the head, one of said walls, known as the interior wall of the regenerator, forming part of an interior wall of the of the hot part of the Stirling machine operating in engine mode or in heat pump mode. , or respectively of the cold part of the Stirling machine operating in refrigeration mode, the other of said walls, known as the outer wall of the regenerator, forming a part of an outer wall of the hot part of the Stirling machine operating in engine mode or in heat pump mode, or respectively of the cold part of the Stirling machine operating in refrigeration mode.

The passage channel (s) may be between a part of the interior wall of the hot part of the Stirling machine, called the interior wall of the passage channel (s), and another wall of the hot part of the Stirling machine, said wall exterior of the passage channel (s).

The inner wall of the regenerator can constitute an extension of the inner wall of the passage channel (s). The outer wall of the regenerator can constitute an extension of the outer wall of the passage channel (s).

An extension of the outer wall of the regenerator can form part of the inner wall of the hot part of the Stirling machine. An extension of the outer wall of the regenerator can form part of the inner wall of the hot exchanger.

An inner wall of the part of the cylinder formed by the head can constitute the inner wall of the hot part of the Stirling machine.

A part of the outer wall of the regenerator can be supported on the separation end of the cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the Stirling machine operating in heat pump mode, and a part of the inner wall of the regenerator is supported on the separation end of the single jacket. In this case, the part of the separation end of the head resting on the separation end of the single jacket constitutes the part of the inner wall of the regenerator resting on the separation end of the single jacket. In this case, too, the part of the separation end of the head resting on the separation end of the cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the Stirling machine operating in pump mode heat, constitutes the part of the outer wall of the regenerator resting on the separation end of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the Stirling machine operating in heat pump mode ,. In this case, too, the part of the external wall of the regenerator and the part of the internal wall of the regenerator constitute the separation end of the head.

The Stirling machine can include one or more recesses. The recess (s) can be made in:

- one or parts of the separation end of the single liner pressing on the separation end of the head and / or one or parts of the separation end of the cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the Stirling machine operating in heat pump mode, pressing on the separation end of the head, and / or

- one or parts of the separation end of the head resting on the separation end of the single jacket and / or resting on the separation end of the cooler of the Stirling machine operating in engine mode or in refrigerator, or respectively the heater of the Stirling machine operating in heat pump mode.

Preferably, the recess or recesses are arranged to minimize the contact surfaces between the hot part and the cold part of the Stirling machine so as to limit the thermal conduction between these parts.

Preferably, the contact zones between the hot part and the cold part of the Stirling machine, inter alia between the regenerator and the head and between the single jacket and the head, can be arranged to minimize the contact surfaces between the hot part and the cold part of the Stirling machine so as to limit the thermal conduction between these parts.

The Stirling machine may include an assembly system arranged to keep the head and the housing in contact, the assembly system is connected to the housing and is arranged to engage with a shoulder of the head, located at the separation end of the outer wall of the head resting on the separation end of the cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively the heater of the Stirling machine operating in heat pump mode.

The assembly system can be a flange type fixing system.

A part of the assembly system arranged to engage the shoulder of the head may be a shoulder of the flange.

Preferably, the assembly system is engaged only with the shoulder. The assembly system can be supported on an outer wall of the casing.

The shoulder may be part of the outer wall of the head and / or part of the cooler.

Preferably, the contact zones between the assembly system and the other elements of the Stirling machine, inter alia the casing and the head, can be arranged to minimize the contact surfaces between the hot part and the cold part of the machine. Stirling so as to limit the thermal conduction between these parts.

A maximum hydraulic diameter of each of the flow paths of the cooler of the Stirling machine operating in engine mode or in refrigeration mode, or respectively of the heater of the Stirling machine operating in heat pump mode, and of the passage channels of the head can be greater than or equal to a thickness of a thermal boundary layer.

Preferably, a maximum hydraulic diameter of each of the cooler flow paths and the head passage channels can be greater than or equal to twice the thickness of the thermal boundary layer. More preferably, a maximum hydraulic diameter of each of the flow paths of the cooler and of the passage channels of the head can be equal to three times a thickness of the thermal boundary layer.

This characteristic has the effect of constraining the flows according to a desired dynamic while limiting the dead volume that constitutes the cooler. Preferably, a length of each of the passage conduits in a direction of travel of the displacer and motor pistons, called the thickness of the passage conduits, is the shortest length of the passage conduits. The Stirling machine can comprise one or more means of friction of the displacing piston and / or one or more means of friction of the driving piston with the single jacket. The friction means or means of the displacing piston and / or one or more means of friction of the driving piston can comprise graphite and / or PolyTetraFluoroEthylene (PTFE).

The friction means can be a segment.

The friction zone of a piston can be defined as the zone in which extends one or more friction means of the piston in question.

A friction zone of the jacket can be defined as the zone of the jacket with which the friction means or means of a piston or pistons are in contact.

When a piston comprises several friction means, the lower end of the friction zone of the engine piston may correspond to the end of a friction means located on the side of the crankshaft of the engine piston and the upper limit of travel the friction zone of the displacing piston may correspond to the end of the friction means of the displacing piston situated on the side of the hot exchanger.

The unique shirt of the Stirling machine can be made of steel.

Description of the figures

Other advantages and particularities of the invention will appear on reading the detailed description of implementations and embodiments in no way limiting, and the following appended drawings:

[Fig. 1] FIGURE 1 is a schematic representation of a bias view of a beta type Stirling engine according to the invention,

[Fig. 2] FIGURE 2 is a schematic representation of a sectional view of the single jacket of the Stirling beta type engine according to the invention, [Fig. 3] FIGURE 3 is a schematic representation of a sectional view of a Stirling beta type engine according to the invention,

[Fig. 4] FIGURE 4 is a schematic representation of a sectional view of a Stirling beta type engine according to the invention,

[Fig. 5] FIGURE 5 is a schematic representation of a sectional view of the assembly system for the hot and cold parts of the Stirling beta type machine according to the invention,

[Fig. 6] FIGURE 6 is a schematic representation in bias view of a vertical section of an area of the Stirling engine of beta type according to the invention comprising the single jacket and the cooler of the Stirling engine.

Description of the embodiments

As the embodiments described below are in no way limiting, we can in particular consider variants of the invention comprising only a selection of described characteristics, isolated from the other described characteristics (even if this selection is isolated within a sentence including these other features), if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art. This selection comprises at least one characteristic, preferably functional without structural details, or with only a part of the structural details if this part only is sufficient to confer a technical advantage or to differentiate the invention from the state of the prior art .

For the sake of clarity and to make the description as intelligible as possible, it is described below of the described embodiments of a Stirling machine of beta 1 type operating in engine mode. However, the characteristic described for the operation of the Stirling 1 machine operating in engine mode can be transposed by the characteristic corresponding to another operating mode of the Stirling 1 machine by making the changes as described in the exposed part of the present application. . It is therefore worth remembering that the Stirling beta 1 type machine operating in engine mode as described below can as well to operate in receiver mode, that is to say in refrigeration machine or heat pump operation. Consequently, the part, or element, considered of the Stirling 1 machine operating in engine mode which performs a function different from the function exercised by the same part, or the same element, considered of the Stirling 1 machine operating in another mode, can be transposed by the function corresponding to the other operating mode of the Stirling 1 machine by making the changes specified below. To do this, it suffices to transpose the function of the part, or of the element, specific to the operation in motor mode by the function of the part, or of the element, corresponding specific to the intended mode of operation.

The main transpositions to be made concern the following characteristics:

- when the Stirling machine 1 is operating in engine mode, the part situated on the side of the casing 11 is the cold part 3 and the part situated on the side of the Stirling machine 1 opposite the casing is the hot part 2. The cold part 3 of the Stirling machine 1 operating in engine mode corresponds to the cold part 3 of the Stirling machine 1 operating in heat pump mode and corresponds to the hot part 3 of the Stirling machine 1 operating in refrigeration mode. Similarly, the hot part 2 of the Stirling machine 1 operating in engine mode corresponds to the hot part 2 of the Stirling machine 1 operating in heat pump mode and corresponds to the cold part 2 of the Stirling machine 1 operating in refrigeration mode,

- when the Stirling machine 1 is operating in engine mode, the part located on the side of the casing 11 of the Stirling machine 1 is the compression zone 3 and the part situated on the side of the Stirling machine 1 opposite the casing is the expansion zone 2 The compression zone 3 of the Stirling 1 machine operating in engine mode corresponds to the compression zone 3 of the Stirling 1 machine operating in refrigeration mode and corresponds to the expansion zone 3 of the Stirling 1 machine operating in heat pump mode. . Similarly, the expansion zone 2 of the Stirling machine 1 operating in engine mode corresponds to the expansion zone 2 of the Stirling machine 1 operating in refrigeration mode and corresponds to the compression zone 2 of the Stirling machine 1 operating in pump mode at heat,

the element of the Stirling machine 1 in which a gas moving from passage conduits 13 of the single jacket 8 passes to the compression volume 14 of the Stirling machine 1 operating in engine mode or in refrigeration mode, or vice versa, is a cooler 4. The element of the Stirling machine 1 in which passes a gas moving from passage ducts 13 of the single jacket 8 to the expansion volume 14 of the Stirling machine 1 operating in heat pump mode, or conversely, is a heater 4,

- when we consider the part of the Stirling machine 1 located on the side opposite to the casing 11 which can be defined as the exchanger 5 of the Stirling machine 1. The part of the Stirling machine located on the side opposite to the casing 11 is l heat exchanger 5 of the Stirling machine 1 operating in engine mode or in heat pump mode, or respectively is the cold exchanger 5 of the Stirling machine 1 operating in refrigeration mode.

With reference to FIGURES 1 to 6, there is described, in a first embodiment, a Stirling 1 engine of beta type. The Stirling engine 1 comprises a cold part 3 and a hot part 2. The Stirling engine 1 comprises a hot exchanger 5 and a cooler 4. The Stirling engine 1 comprises a displacing piston 6 and a driving piston 7. The displacing piston 6 comprises a assembly 131 formed by a sealing segment and a guide ring for the displacing piston 6. The driving piston 7 comprises an assembly 132 formed by a sealing segment and a guide ring for the driving piston 7. The Stirling engine 1 of beta type according to the invention comprises a single jacket 8 disposed integrally in the cold part 3 of the engine 1 and in which the friction zone 9 of the displacing piston 6 and the friction area 10 of the driving piston 7 slide.

In the remainder of this description, the term “engine” used alone designates a Stirling machine of beta 1 type operating in engine mode.

By way of nonlimiting example, the operating conditions for which the engine 1 has been designed are 900 ° C. for the temperature at the level of the hot exchanger 5, working gas pressures of the order of 100 bars and an operating frequency of 50 Hz for operation in motor mode. When use in refrigeration mode of the Stirling machine 1 is targeted, the temperature at the cold exchanger 5 is of the order of -50 ° C., the working gas pressures are of the order of 100 bars. and the operating frequency is around 50. Finally, for use in heat pump mode, the temperature at the hot exchanger 5 is 200 ° C., the working gas pressures are around 100 bars and the operating frequency is around 50 Hz. Machine 1 is designed to operate without lubrication.

First, proceed to the description of the cold part 3 of the engine 1.

The driving piston 7 and the displacing piston 6 are connected to the crankshaft 26 via respective connecting rods 16, 17. The rod 161 of the connecting rod 16 passes through the driving piston 7 at the level of a sliding pad 27 ensuring the sealing and the sliding of the rod in question through the driving piston 7. The displacing piston 6 comprises radiation shields 35.

The single jacket 8 constitutes the part of the cylinder of the engine 1 situated in the cold part 3 of the engine 1. The use of a single jacket 8 makes it possible not to introduce any junction zone present when two shirts are used. This facilitates maintenance and costs, and does not introduce a high thermal gradient which necessarily appears at the junction when using two shirts. It also does not create dead volume at the junction.

The single liner 8 comprises passage conduits 13 for the working gas through the liner 8. The passage conduits 13 pass through the liner 8 in a radial direction relative to the strokes of the pistons 6, 7. The passage conduits 13 are distributed annularly along the compression zone 14 of the gases.

The passage conduits 13 have an elongated shape. The length of the passage conduits 13 along the inner perimeter of the jacket 8 is greater than the thickness of the passage conduits 13 along the direction of travel of the pistons 6, 7. The thickness of the passage conduits 13 is minimized to reduce the volume located at the volume level of compression 14. The shape of the passage conduits 13 according to the invention thus makes it possible to improve the efficiency of the motor 1 by reducing the distance separating the limit switches of the displacer pistons 6 and motor 7 at the level of the compression volume 14 and consequently reduce the dead volume constituted by the distance separating the limit switches of the displacer 6 and motor 7 pistons at the level of the compression volume 14.

The size of the passage conduits 13 governs the pressure drops. A too small size constitutes a brake on the circulation of gases between the compression volume 14 and the expansion volume 15 and on a reduction in the efficiency of the engine 1. In practice, the thickness of the passage conduits 13 limited by the mechanical strength of the shirt.

The single liner 8 is inserted into the casing 11 and abuts against a shoulder 12 formed in the inner wall of the casing 11. After the single liner 8 has been inserted into the casing 11, the part of the outer wall of the liner 8 extending from the lower end of the passage conduits 13 to the end of travel of the friction zone 10 of the driving piston 7 on the side of the connecting rods 16, 17 is in direct contact with the inner wall of the casing 11. The portion of the cold part 3 of the engine 1 comprising the part of the outer wall of the jacket 8 in question is called the lower part 19. The end of the single jacket 8 located on the side of the connecting rods 16, 17 may extend to the beyond the end of the stroke of the driving piston 7 on the side of the connecting rods 16, 17.

After the single liner 8 has been inserted, the part of the outer wall of the liner 8 extending from the lower end of the passage conduits 13 to the end of travel of the friction zone 9 of the displacer piston 6 located on the side of the hot exchanger 5 is not in contact with the inner wall of the casing 11. The portion of the cold part 3 of the engine 1 comprising the part of the outer wall of the jacket 8 in question is called the upper part 20. At the lower end of the passage conduits 13, the casing 11 forms a shoulder 18 which, in the upper part 20 of the cold part 3, moves the inner wall of the casing 11 away from the outer wall of the jacket 8 .

After the single jacket 8 has been inserted, a housing is thus formed between the wall of the casing 11 and the wall of the single jacket 8 in the upper part 20 of the cold part 3 of the engine 1. This housing is arranged to receive the cooler 4. The cooler 4 can be inserted in the housing or formed in a block with the casing 11. An inlet 22 and an outlet 23 are provided through the casing 11 to allow the circulation of the heat transfer liquid, for example water, in the cooler

4.

In this configuration, the single jacket 8 is in direct contact with the cooler 4. This ensures better cooling of the jacket 8 and therefore of the compression zone 14. In addition, this arrangement ensures direct contact of the single jacket 8 with the entire wall of the cooler 4 over the entire length of the cooler 4. This aspect ensures better heat transfer between these parts. The use of a single jacket 8 entirely located in the compression zone 14 makes it possible to maintain the jacket 8 at low temperatures and therefore to significantly reduce the thickness of the wall of the single jacket 8. This configuration makes it possible to maintain a temperature of the single jacket 8 at a temperature below 60 ° C. The fact that the thickness of the jacket 8 is small considerably reduces the thermal conduction between the hot 2 and cold 3 parts which are at different temperatures. The fact that the temperature of the single jacket 8 is low decreases the thermal expansion of the jacket.

The fact that the friction zones 9, 10 are in contact only with the single jacket 8 and that the jacket 8 remains at such low temperatures, makes it possible to use unique segments / shirt pairs based on unusual materials. By way of nonlimiting example, the jacket can be made of steel, for example 42CD4T steel, and the segments are made of PTFE-graphite composite. The PTFE-graphite couple is used as a solid lubricant, which eliminates the heat treatment stages of steel

The cooler 4 comprises flow paths 21 for the working gas. These flow paths 21 extend along the cooler 4 in the direction of travel of the pistons 6, 7 and connect the passage conduits 13 to a regenerator 24 located in the hot part 2 of the engine 1.

The cooler 4 is inserted into the housing and abuts against the shoulders 25 and 18 of the casing 11. The shoulder 25 is provided in the wall of the casing 11. The wall of the cooler 4 in contact with the shoulder 18 comprises a recess 394 intended to receive a sealing element between the water and the working gas. The side wall of the cooler 4 in contact with the wall of the casing 11 of the upper part 20 of the engine 1 has a recess 395 also intended to receive a sealing element between the water and the outside. The cooler 4 is arranged so that after being inserted into the housing, its wall located on the side of the jacket 8 is traversed by flow paths 21. Thus, these flow paths 21 connect the passage conduits 13 to a regenerator 24 located in the hot part 2 of the engine 1.

Secondly, proceed to the description of the hot part 2 of the engine 1.

The hot part 2 is composed of a steel or inconel head 28. The head 28 constitutes the hot part 2 of the engine 1. According to the invention, the friction zones 9, 10 are in contact only with the single jacket 8, the head 28 is not subjected to any mechanical stress linked to friction . The thickness of the head 28 is therefore also reduced so as to minimize the contact zones between the head 28 and the cold part 3 and consequently further limit the thermal conduction between the hot 2 and cold 3 parts of the engine 1 which are not not at the same temperature. In the head 28 is formed the part of the cylinder of the engine 1 located in the hot part 2. The end part of the head 28 comprises the hot exchanger 5. The expansion volume 15 located in the end part of the cylinder is in contact with the hot exchanger 5. A so-called upper portion 29 of the head 28 extends from the hot exchanger 5 to the regenerator 24. A so-called lower portion 30 of the head 28 comprises the regenerator 24 and s' extends from the end of the upper portion 29 to the cooler 4. The outer wall of the upper portion 29 of the head 28 comprises fins 31 improving the heat exchanges in the vicinity of the hot exchanger 5.

Passage channels 32 connecting the expansion zone 15 to the regenerator 24 are formed in the upper portion 29 of the head 2. These passage channels 32 are between the inner wall 33 and the outer wall 34 of the head 28. The wall inner 33 of head 28 also constitutes the wall of the cylinder of the engine 1. The fins 31 extend from the external wall 34 of the head 28.

A shoulder 36 is formed in the inner surface of the outer wall 34 of the head 28. This shoulder 36 induces an increase in the distance separating the inner wall 33 from the outer wall 34 in the lower portion 30. This increase in the distance forms thus a housing between the walls 33, 34 of the head 28. The shape of the shoulder 36 reduces the pressure losses during the circulation of the gas between the regenerator 24 and the hot exchanger 5. The regenerator 24 can be inserted into the housing or formed of a block with the head 28.

The hot part 2 also includes a regenerator 24 intended to store and then restore the heat of the gas passing from the expansion volume 15 of the engine mode 1 to the compression volume 14 of the engine mode 1. The working gas, or working gas, is also cooled or heated during its passage through the regenerator 24. The regenerator 24 extends from the passage channels 32 of the head 28 to the flow paths 21 of the cooler 4 of the engine mode 1.

Preferably, the regenerator 24 can be designed separately so as to be perfectly suited to the conditions of use of the engine 1. The regenerator 24 can be inserted into the housing of the head 28 until it abuts against the shoulder 36. In order to reduce the heat exchanges between the cold part 3 and the hot part 2, the length of the regenerator 24 according to the direction of travel of the pistons 6, 7 will be increased. The optimal length will be established to optimize the compromise between minimizing conduction and reducing head losses and dead volumes. The regenerator 24 is arranged so that the heat is stored as far as possible from the cold part 3 on the side of the hot exchanger 5.

In order to limit the pressure drops, it is preferable to use a regenerator 24 comprising volumes of different porosities arranged successively along the direction of flow of the gas. For this purpose, it is more preferable that an alternation of portions with high and low porosity be formed, aiming to increase the overall hydraulic diameter of the regenerator 24 so as to reduce the overall pressure losses while retaining an equivalent exchange surface. Still with a view to limiting pressure drops, it is preferable to use a regenerator 24 whose porosity values at the ends of the regenerator 24, and in particular on the side of the hot exchanger 5, are lower than the porosity values at regenerator center 24.

The performance of the regenerator 24 is also improved when:

the porosities of the portions of the regenerator 24 increase from a central plane of the regenerator towards the ends of the regenerator 24, and / or

- The portion with the highest porosity of the regenerator has a porosity equal to 1, and / or

the porosity is between 0 and 1 per unit of volume and / or between 0 and 1 per unit of length, and / or

the regenerator 24 is made of a porous rigid material being composed of a set of contiguous cells arranged spatially with respect to each other, the or each of the contact surfaces of each of the cells with the gas form an angle of between 5 ° and 85 ° with respect to the direction of flow of the gases, and / or

each cell of the regenerator 24 comprises at least four oblong elements extending from the center of the cell, each of the elements forming an angle between 5 ° and 85 ° relative to the direction of flow of the gases, and / or

- two contiguous cells of the regenerator 24 are physically linked together:

• by at least one of their oblong elements, or

• by a layer of material to which is connected at least one of their oblong elements, and / or

- The oblong elements of the cells of the regenerator 24 are symmetrical two by two with respect to one or more planes of symmetry comprising the center of the cell.

Thirdly, a description is given of the assembly of the cold 3 and hot 2 parts and of the geometric characteristics of the engine 1. One of the points limiting the efficiency of Stirling beta type machines lies in the fact that the hot 2 and cold 3 parts are joined. Also, the heat exchange by conduction between the hot part 2 and the cold part 3 must be reduced as much as possible. Thermal conduction by machine parts remains the main factor reducing the efficiency of Stirling beta type machines. Some of the Stirling machines of the state of the art introduce insulation means placed between the cold part 3 and the hot part 2 to thermally insulate the hot part 2 from the cold part 3. This increases the weight and the cost of the Stirling 1 machine and introduced maintenance difficulties and increased dead volumes. According to the invention, no insulation means is inserted between the hot part 2 and the cold part 3 of the Stirling machine 1.

The head 28 is brought into contact with the cold part 3 of the motor 1. When the head 28 is in contact with the cold part 3 of the motor 1, the end of the interior wall 33 of the head 28 is in contact with a shoulder 38 located at the end of the single jacket 8. The side wall of the shoulder 38 has a recess 391 aimed at reducing the contact surface between the head 28 and the single jacket 8 and consequently the thermal conduction between the head 28 and the jacket 8. This recess 391 also makes it possible to accommodate a sealing element. When the head 28 is in contact with the cold part 3 of the engine 1, a shoulder 40 situated at the end of the external wall 34 of the head 28 is in contact with the face of the cooler 4 situated opposite the head 28. The face of the cooler 4 facing the head 28 comprises two recesses 392, 393 aimed at reducing the contact surface between the head 28 and the cooler 4 and consequently the thermal conduction between the head 28 and the cooler 4. The recess 392 is arranged to receive a sealing element between the working gas and the outside. When the head 28 is in contact with the cold part 3 of the engine 1, the end face of the regenerator 24 situated opposite the cold part 3 is partly supported on the end faces of the cooler 4 and of the jacket single 8 located opposite the end face of the regenerator 24 in question. The end of the flow paths 21 of the cooler 4 located on the side of the hot part 2 open onto the end face of the regenerator 24 located opposite. The cold part 3 is kept in contact with the hot part 2 by means of a system of assembly flanges 37. By way of nonlimiting example, the motor 1 comprises eight systems of assembly flanges 37. Each system 37 comprises a screw 41 intended to be inserted from an upper side of a flange 42 and into a passage through the flange 42. The thread of the screw 41 is intended to be carried projecting from the side opposite to the upper side of the flange 42. Each flange 42 is intended to keep in contact the head 28 and the casing 11 by carrying a part of the flange 42 bearing on the head 28 and another part of the flange 42 bearing on the casing 11. After the screw 41 has been inserted, the head 48 of the screw 41 is intended to be brought to bear on the flange 42. The thread of the screw 41 is designed to be screwed into a thread made in a bead 44 of the casing 11. The flange 42 comprises a shoulder 45 intended to come into engagement with the shoulder 40 of the head 28 so that, after screw screw 41, the head 28 is maintained in intimate contact with the cooler 4. Preferably, the shoulder 46 can be arranged so as to be in contact only with the cooler 4, not with the casing 11. The shoulder 45 has a recess 396 aimed at reducing the thermal conduction between the flange 42, and consequently the casing 11, and the head 28. Also, the shoulder 45 of the flange 42 can therefore be defined as consisting of an edge 46 extending in the direction connecting the expansion zone 15 to the compression zone 14 and forming the single part of the flange 42 intended to come into contact with the head 28, and in particular in contact with the shoulder 40 of the head 28. This edge 46 is located on the side of the flange 42 facing the motor 1. This stop 46 aims to minimize the contact area between the flange 42 and the head 28. In the same way, the face of the flange 42 located opposite the bead 44 of the casing 11, has an edge 47 intended to come into abutment s ur the bead 44. This edge 47 extending in the direction connecting the expansion zone 15 to the compression zone 14 and being brought into contact with the bead 44. This edge 47 is located on the outside of the flange 42 relative to the center of the machine 1. This edge 47 forms the single part of the flange 42 intended to come into contact with the casing 11. This stop 47 aims to reduce the contact zones between the flange 42 and the casing 11 while maintaining a space between the flange 42 and the casing 11. According to the invention, the reduction of the thermal conduction between the hot 2 and cold 3 parts which are at different temperatures has been achieved by the implementation of the characteristics, and / or by their combinations, that are:

the use of a single jacket 8 located entirely in the cold part 3 of the engine 1, and / or

the arrangement of the cooler 4 in direct contact with the single jacket 8, and / or

the maximization of the contact surfaces between the cooler 4 and the single jacket 8, and / or

the arrangement of the regenerator 24 entirely in the head 28 and therefore entirely in the hot part 2, and / or

the minimization of the contact surfaces between the head 28 and the cold part 3, and / or

the introduction of recesses in the contact zones between the head 28 and the cold part 3, and / or

the reduction in the size of the walls 33, 34 of the head 28, and / or

the reduction in the size of the wall of the jacket 8 which is made possible by the use of a single jacket 8 integrally included in the cold part 3 of the engine 1.

According to the invention, the reduction in dead volumes has been achieved by the implementation of the characteristics, and / or by their combinations, which are:

the use of a single jacket 8 located entirely in the cold part 3 of the engine 1, and

the arrangement of the passage conduits 13 at the level of the compression zone 14, and

the reduction in the thickness of the passage conduits 13, and / or

the reduction in the distance separating the end positions of the displacer 6 and motor 7 pistons at the level of the compression zone 14.

According to the invention, the reduction in pressure losses during the circulation of the gases has been achieved by the implementation of the characteristics, and / or by their combinations, that are: use a regenerator 4 comprising volumes of different successive porosities arranged along the gas flow direction, and / or

use a regenerator comprising alternating portions of high and low porosity so as to increase the overall hydraulic diameter of the regenerator 4 so as to reduce the overall pressure losses while retaining an equivalent exchange surface, and / or

use a regenerator 4 whose porosity values at the ends of the regenerator 4, and in particular on the side of the hot exchanger 5, are lower than the porosity values at the center of the regenerator 4, and / or

- two contiguous cells of the regenerator 24 are physically linked together:

• by at least one of their oblong elements, or

- The oblong elements of the cells of the regenerator 24 are symmetrical two by two with respect to one or more planes of symmetry comprising the center of the cell. Of course, the invention is not limited to the examples which have just been described and numerous modifications can be made to these examples without departing from the scope of the invention. In addition, the different characteristics, forms, variants and embodiments of the invention can be combined with one another in various combinations as long as they are not incompatible or mutually exclusive of each other.

Claims

1. Stirling machine (1) of beta type which can operate in engine mode or in heat pump mode, said Stirling machine comprising:

- a cold part (3) and a hot part (2),

- a displacement piston (6) comprising a friction zone (9),

- a driving piston (7) comprising a friction zone (10),

the Stirling machine being characterized in that it comprises a single jacket (8) disposed in the cold part of the Stirling machine operating in engine mode or in heat pump mode and in which single jacket slide the friction zones of the displacing piston and of the engine piston.

2. Stirling machine (1) according to claim 1, in which the single jacket (8) extends along the races of the friction zones of the displacing piston (6) and of the driving piston (7).

3. Stirling machine (1) according to claim 1 or 2, in which the single jacket (8) extends from a lower end of travel of the friction zone (10) of the driving piston (7), called the end of the casing. of the single liner, said lower limit switch of the friction zone of the driving piston being situated on the side of a crankshaft (26) of the driving piston, up to an upper limit switch of the friction zone (9) of the displacing piston (6), said end for separating the single jacket, said upper limit switch of the friction zone of the displacing piston being situated on the side of an exchanger (5).

4. Stirling machine (1) according to any one of the preceding claims, in which the single jacket (8) comprises passage conduits (13) of a gas moving from a compression volume (14) of the Stirling machine operating in engine mode, or respectively an expansion volume (14) of the Stirling machine operating in heat pump mode, to a cooler (4) of the Stirling machine operating in engine mode, or respectively a heater (4) of the machine Stirling operating in heat pump mode, or vice versa, said passage conduits passing through the single jacket.

5. Stirling machine (1) according to claim 4, in which the cooler (4) of the Stirling machine operating in engine mode, or respectively the heater (4) of the Stirling machine operating in heat pump mode, is, at least in part, in direct contact with the single jacket (8) and surrounds, at least in part, the single jacket, said cooler of the Stirling machine operating in engine mode, or respectively the heater the Stirling machine operating in heat pump mode, being entirely included in the cold part (3) of the Stirling machine operating in engine mode or in heat pump mode.

6. Stirling machine (1) according to claim 4 or 5, wherein the single jacket (8) and the cooler (4) of the Stirling machine operating in engine mode, or respectively the heater (4) of the machine of the machine Stirling, operating in heat pump mode, are inserted, at least in part, into a casing (11) until they are brought to bear on the shoulders (12) of the casing.

7. Stirling machine (1) according to any one of claims 4 to 6, comprising a head (28) forming, at least in part, the hot part

(2) of the Stirling machine operating in engine mode or in heat pump mode, at least part of one end of said head, called head separation end, is, in part, supported on the end of separation of the single jacket (8) and, in part, pressing on a part of the cooler (4) of the Stirling machine operating in engine mode, or respectively on a part of the heater (4) of the Stirling machine operating in pump mode heat, said separation end of the Stirling machine cooler operating in engine mode, or respectively said separation end of the Stirling machine heater operating in heat pump mode.

8. Stirling machine (1) according to claim 7, comprising a regenerator (24) extending from the separation end of the head (28) to one or more end portions, called regenerator, of one or more passage channels (32) for a gas moving from the expansion volume (15) of the Stirling machine operating in engine mode, or respectively from the compression volume (15) of the Stirling machine operating in heat pump mode , to the regenerator, or vice versa.

9. Stirling machine (1) according to claim 8, in which the regenerator (24) is sandwiched between two walls (33, 34) of the head (28), one of said walls of the head, called inner wall of the regenerator (33), forming a part of an inner wall of the hot part (2) of the Stirling machine operating in engine mode or in heat pump mode, or respectively of the cold part (2) of the Stirling machine operating in refrigeration mode, the other of said walls of the head, known as the external wall of the regenerator (34), forming part of an external wall of the hot part of the Stirling machine operating in motor mode or heat pump mode.

10. Stirling machine (1) according to claim 9, in which a part of the external wall of the regenerator (34) is in abutment on the separation end of the cooler (4) of the Stirling machine operating in engine mode, or respectively. the heater (4) of the Stirling machine operating in heat pump mode, and part of the inner wall of the regenerator (33) is supported on the separation end of the single jacket (8).

11. Stirling machine (1) according to one of claims 7 to 10, in which one or more recesses (391, 392, 393, 394, 395, 396) are produced in:

- one or parts of the separation end of the single jacket (8) bearing on the separation end of the head (28) and / or one or parts of the separation end of the cooler (4) of the Stirling machine operating in engine mode, or respectively of the heater (4) of the Stirling machine operating in heat pump mode, pressing on the separation end of the head, and / or

one or more parts of the separation end of the head resting on the separation end of the single jacket and / or resting on the separation end of the cooler of the Stirling machine operating in engine mode, or respectively the Stirling machine heater operating in heat pump mode.

12. Stirling machine (1) according to one of claims 9 to 11, comprising an assembly system (40, 41, 42, 44) arranged to maintain in contact the head (28) and the casing (11), the assembly system is connected to the housing and is arranged to engage with a shoulder (40) of the head located at the separation end of the outer wall of the head (34) resting on the end for separating the cooler (4) from the Stirling machine operating in engine, or respectively the heater (4) of the Stirling machine operating in heat pump mode.

13. Stirling machine (1) according to any one of claims 8 to 12, in which a maximum hydraulic diameter of each of the flow paths (21) of the cooler (4) of the Stirling machine operating in engine mode, or respectively the heater (4) of the Stirling machine operating in heat pump mode, and passage channels (32) of the head (28) are greater than or equal to a thickness of a thermal boundary layer.

14. Stirling machine (1) according to any one of the preceding claims, in which one or more means of friction of the displacing piston (6) and / or one or more means of friction of the driving piston (7) comprise graphite and / or PolyTetraFluoroEthylene.

15. Stirling machine (1) according to any one of the preceding claims, in which the single jacket (8) is made of steel.