FR3105303A1 - Double-turn Stirling engine - Google Patents

Abstract

The present invention relates to an engine working according to a Stirling cycle, the cycle of which takes place over two engine revolutions, of which each phase of the Stirling cycle takes place over 180 degrees and of which the working fluid contained in each chamber is completely transferred from chamber in chamber, characterized in that it comprises cylinders in which constantly moves a piston (11, 12, 13, 14) delimiting two working chambers, ((7, 1), (2, 8), (9, 3), (4, 10)), a heat transfer exchanger containing two chambers (5, 6) allowing the cold fluid to be partially heated by the hot fluid during the temperature rise and cooling phases

Description

Double-turn Stirling engine

The present invention relates to a twin-turn Stirling engine.

There are alpha, beta, gamma type Stirling engines.
There is the hot air engine working permanently according to a cycle derived from the Stirling cycle according to patent FR3079877.
There is the hot air engine working essentially according to a three-phase cycle according to patent FR2966520.
Today's Stirling engines perform the Stirling cycle on one revolution of the crankshaft, i.e. 360 degrees.
The Stirling engine according to the invention performs the Stirling cycle over two engine revolutions, ie 2 times 360 degrees.

The Stirling cycle comprises 4 phases which are an isothermal compression phase, an isochoric temperature rise phase, an isothermal expansion phase and an isochoric cooling phase.
The Stirling engine according to the invention carries out the phases over 180 degrees, the advantage is that the heat transfer times are longer, which improves the performance of the engine.
As each phase of the cycle takes place over 180 degrees, it is necessary to make two revolutions of the engine.

The volumes of gas according to the invention are transferred 100% from room to room.
The gas that was used to carry out the compression phase is 100% used for the temperature rise phase.
The gas that was used to carry out the temperature rise phase is 100% used for the expansion phase.
The gas that was used to carry out the expansion phase is 100% used for the cooling phase.
The gas that was used to carry out the expansion phase is 100% used for the cooling phase.
The gas that was used to carry out the cooling phase is 100% used for the compression phase.
The working volumes of the gas are perfectly distinct, those which improve the performance of the engine.

Some current Stirling engines use a regenerator or an exchanger.
The purpose of this regenerator or this exchanger is to improve the efficiency of the Stirlingen cycle by cooling the gas after its expansion and by heating it after its compression.
The drawback of this regenerator or of this exchanger is that the heat transfers do not take place simultaneously.
The exchanger according to the invention allows the transfer of heat simultaneously and for 180 degrees.

The characteristics of the double-turn Stirling engine which is the subject of the invention are described in detail with reference to the attached non-limiting drawings in which

Figure 1 is a diagram representing different phases of the Stirling cycle during the first revolution of the engine.

FIG. 2 is a diagram representing different phases of the Stirling cycle during the second revolution of the engine.

The Stirling engine according to the invention is composed of cylinders.
Each cylinder has two sealed chambers separated by a piston.

The pistons perform an alternating linear translation and are moved by a connecting rod-crank system.

The pistons are all in phase.

The connecting rod-crank system is not shown in figures 1 and 2.

The rooms are interconnected by pipes.
The configuration of the pipes changes every 180 degrees. This configuration is obtained for example by a set of drawers and cams.

The end of the cylinders with the chambers (7) and (2) is maintained at a hot temperature.
The end of the cylinders with the chambers (1) and (8) is maintained at a cold temperature
The cylinder with the chambers (3) and (9) is maintained at a cold temperature.
The cylinder with the chambers (4) and (10) is maintained at a hot temperature.

Figure 1, the piston (12) will move and will transfer the volume of gas contained in the chamber (8) in the chamber (3).
The volume of chamber (3) is significantly lower than the volume of chamber (8) and as chambers (3) and (8) are maintained at a cold temperature, the isothermal compression phase of the Stirling cycle will be operated. 180 degrees.

Figure 1, the piston (13) will move and will transfer the volume of gas contained in the chamber (9) in the chamber (4) through the chamber 6 of the exchanger.
As the volumes of chambers (9) and (4) are identical, as chamber (9) is maintained at cold temperature and as chamber (4) is maintained at hot temperature, the temperature rise phase will be carried out of the Stirling cycle.
The temperature rise phase of the Stirling cycle is not perfectly isochoric due to the small volume of the chamber (6) of the exchanger.

Figure 1, the piston (14) will move and will transfer the volume of gas contained in the chamber (10) in the chamber (2).
The volume of chamber (2) is significantly greater than the volume of chamber (10) and since chambers (2) and (10) are maintained at a hot temperature, the isothermal expansion phase of the Stirling cycle will be operated.

Figure 1, the piston (11) will move and will transfer the volume of gas contained in the chamber (7) in the chamber (1) passing the chamber (5) of the exchanger.
The volume of chamber (7) is maintained at hot temperature and as the volume of chamber (1) is maintained at cold temperature, the cooling phase of the Stirling cycle will be carried out.
The cooling phase of the Stirling cycle is not perfectly isochoric due to the small volume of the chamber (5) of the exchanger.

Figure 2, the piston (11) will move and will transfer the volume of gas contained in the chamber (1) in the chamber (9).
The volume of chamber (9) is much lower than the volume of chamber (1) and as chambers (1) and (9) are maintained at a cold temperature, the isothermal compression phase of the Stirling cycle will be operated. 180 degrees.

Figure 2, the piston (13) will move and will transfer the volume of gas contained in the chamber (3) in the chamber (10) through the chamber 6 of the exchanger.
As the volumes of chambers (3) and (10) are identical, as chamber (3) is maintained at cold temperature and as chamber (10) is maintained at hot temperature, the temperature rise phase will be carried out of the Stirling cycle.
The temperature rise phase of the Stirling cycle is not perfectly isochoric due to the small volume of the chamber (6) of the exchanger.

Figure 2, the piston (14) will move and will transfer the volume of gas contained in the chamber (4) in the chamber (7).
The volume of chamber (7) is significantly greater than the volume of chamber (4) and since chambers (7) and (4) are maintained at a hot temperature, the isothermal expansion phase of the Stirling cycle will be operated.

Figure 2, the piston (12) will move and will transfer the volume of gas contained in the chamber (2) in the chamber (8) passing the chamber (5) of the exchanger.
The volume of chamber (2) is maintained at cold temperature and as the volume of chamber (8) is maintained at cold temperature, the cooling phase of the Stirling cycle will be carried out.
The cooling phase of the Stirling cycle is not perfectly isochoric due to the small volume of the chamber (5) of the exchanger.

The cylinders with the pistons (11) and (12) are maintained at the end with different temperatures, it is necessary to make these cylinders with thermally insulating materials of the ceramic type for example.

Figure 3 is a diagram representing a variant of the cylinders.
Instead of using a single cylinder with different end temperatures, it is possible to use two identical cylinders which are physically connected by an insulating material.
The two identical pistons are connected to each other by an insulating material.

FIG. 4 is a diagram representing another variant of the cylinders with different end temperatures.
Instead of using a single cylinder, it is possible to use two independent cylinders each having a single chamber and each having their own connecting rod system. Each cylinder is maintained at temperature either by a cold source or a hot source.

A variant proposed for the displacement of the pistons (13) and (14), these pistons can be free instead of being moved by a connecting rod-crank system.
It is the difference in pressure that these pistons undergo which allows their movement.

Claims (1)

The present invention relates to an engine working according to a Stirling cycle, the cycle of which takes place over two engine revolutions, of which each phase of the Stirling cycle takes place over 180 degrees and of which the working fluid contained in each chamber is transferred completely from the in the room,
engine characterized in that it comprises
cylinders in which a piston (11, 12, 13, 14) constantly moves delimiting two working chambers, ((7, 1), (2, 8), (9, 3), (4, 10)),
a heat transfer exchanger containing two chambers (5, 6) allowing the cold fluid to be partially heated by the hot fluid during the temperature rise and cooling phases,
pipes connecting the different chambers (1, 9, 3, 6, 10, 4, 7, 12, 5, 2), equipped with organs of the type, for example a set of drawers, cams, making it possible to modify the connections between these chambers every half turn of the engine so:
that during the isothermal compression phase during the first half-turn of the engine (180 degrees), the working fluid contained in the chamber (1) maintained at a cold temperature by a cold source is transferred into the chamber (9) d a smaller volume and maintained at a cold temperature by the cold source,
that during the temperature rise phase during the second half-turn of the engine, the working fluid contained in the chamber (9) maintained at a cold temperature is transferred into the chamber (4) maintained at a hot temperature by a source hot and is preheated during transfer into the chamber (6) of the exchanger,
that during the isothermal expansion phase during the third half-turn of the engine, the working fluid contained in the chamber (4) maintained at a hot temperature is transferred into the chamber (7) maintained at a hot temperature by a hot source,
that during the cooling phase during the fourth half-turn of the engine, the working fluid contained in the chamber (7) is transferred to the chamber (1) maintained at a cold temperature by the cold source and gives off heat during the transfer in the chamber (5) of the exchanger.