FR2778695A1 - Flexible combustion chamber for an internal combustion engine - Google Patents

Abstract

The combustion chamber comprises an impermeable pouch (3) of a supple and deformable material enclosed within a tubular sheath (4) of braided, mesh or knitted synthetic filaments. The pouch is fed with a combustible mixture, for example LPG and air. The sheath is fixed at one end and connected at the other to a mechanism (10) such as a crankshaft which transfers the energy resulting from the deformation caused by the detonation of the combustible mixture inside the pouch.

Description

-1- The present invention consists of a new type of chamber

  combustion for an internal combustion engine characterized in that it mainly consists of a

  deformable pocket wrapped in a braid.

  Currently, conventional internal combustion engines have at least one combustion chamber formed and delimited by a jacket, a cylinder head and a piston. The variation in volume of said chamber is obtained by sliding the piston in the jacket, which assumes dynamic sealing. In addition, during engine operation, the pressures prevailing in the combustion chamber tend mainly to exert a compressive force on the piston, therefore on the connecting rod, itself linked to the

  crankshaft. This requires great rigidity of the latter.

  In addition, there is a pneumatic actuator called "McKibben muscle" which, starting from a gas under pressure makes it possible to generate a traction force. This "McKibben muscle" mainly consists of a tight flexible tube, playing the role of a deformable pocket, wrapped in a tubular braid whose ends are terminated by a

fixed tip and a movable tip.

  The present invention consists of the association of the mechanical principles of the "McKibben muscle" with the thermodynamic principles of the internal combustion engine. I1 is to create a new type of engine characterized by the fact that the combustion chamber (s)

  mainly consist of a deformable pocket wrapped in a braid.

  We designate by deformable pocket a flexible and waterproof envelope, similar to

  a tubular air chamber with a rectilinear axis.

  By braid we designate a tubular braid or tubular sheath or network of wires, forming similar pantographs, obtained for example thanks to the techniques of

  braiding, knitting, knitting.

  The assembly constituted by said deformable pocket and braid terminated by end pieces, is the equivalent for a conventional internal combustion engine, of the cylinder head, jacket, piston and connecting rod assembly. The other main components of the engine, in particular the crankshaft and the fuel system are not specific to the invention and will not be

therefore not detailed.

  Said tips can accommodate one or more valves for intake and exhaust, as well as a possible spark ignition system to initiate combustion. Said ends are attached to a mechanical system which recovers the tensile forces of said braid. We can have, for example, a fixed tip attached to the frame of the

  engine and a moving end attached to a crankshaft.

  An original construction of the explosion chamber is possible by introducing a core into said chamber, in order to reduce the dead volume not swept by the normal displacement of the deformable pocket. The term “core” designates one or more mechanical parts, generally cylindrical in shape, gas tight, which are located in the explosion chamber delimited by the deformable pocket. This core can be a protrusion of one or both ends, but it can also be linked elastically or telescopically to the two ends at the same time, or in any other way. Such a core is directly exposed to the flame, and by occupying at least part of said dead volume in the deformable pocket, it allows

  significantly increase the volumetric ratio of the combustion chamber.

  Several combustion chambers according to the invention can be associated, for example in a star shape, to be integrated in at least one wheel of a land vehicle, and thus

reduce the size of the motor.

  Detailed description of an embodiment of the combustion chamber of the invention:

see figure 1.

  The present combustion chamber (9) consists of a deformable pocket (3), produced from a flexible tube made of silicone elastomer which acts as an air chamber while resisting high temperatures. This deformable pocket is wrapped in a braid (4) of chemical textile fibers (aramid), terminated at each end by a fixed end piece (1) and a movable end piece (2) linked to the crankshaft (not shown) to supply the engine with torque. . In the fixed end piece (1) is housed an intake valve (6) which incorporates a spark plug (7) while in the movable end piece (2) is housed a valve

exhaust (8).

  The geometric properties of said braid associate with the swelling of said deformable pocket an increase in the diameter of said braid and a decrease in its length, and vice versa, up to a certain limit linked to the characteristics of said braid. In order to describe the different times of the engine, we will express ourselves in terms of increases or decreases in the volume of the deformable pocket, corresponding respectively to decreases or increases in the length of said braid, linked by its movable tip.

to the crankshaft it animates.

  At the intake, the intake valve (6) is open and the deformable pocket (3) increases in volume, allowing fresh gases and fuel to penetrate. In order for fresh gases to enter said deformable pocket (3), it may be necessary to send them under pressure or else to place said deformable pocket and said braid in an enclosure.

under low pressure.

  During compression, the volume of said deformable pocket (3) decreases, the valves (6)

  and (8) being closed, the pressure increases.

  When the volume of the deformable pocket is close to its minimum, the spark of the

  spark plug (7) triggers combustion of the air-fuel mixture.

  Upon expansion, the volume of the deformable pocket increases and the pressure of the burnt gases at high temperature generates a significant tensile force on the crankshaft via

  of the movable end piece (2) and of said braid (4).

  -3- At the exhaust, the exhaust valve (8) opens while the volume of the

  deformable pocket (3) decreases expelling the burnt gases.

  This engine thus describes a 4-stroke cycle, but it is possible to add "dead" times (engine revolutions without fuel intake or combustion) to improve sweeping and cooling, thanks to a valve control system not related to the crankshaft. It is also possible to envisage a simultaneous flue gas sweeping system

  the introduction of fresh gases to have a 2-stroke engine.

  Such a combustion chamber has several advantages compared to conventional combustion chambers: * The deformable pocket can be completely sealed, thus eliminating any dynamic sealing. * The constituent parts of such a chamber can be made of materials

  light such as polymers, which makes it possible to obtain a very low weight / displacement ratio.

  * All the effort is transmitted to the crankshaft by said braid which only works

  traction, which eliminates the problems of rigidity of the rods working in compression.

  * This combustion chamber can be produced without machining and almost without metals, by mass production processes such as injection or extrusion, from a

  particularly economical production.

  * The deformable pocket being made of flexible material, the "sound box" effect

  of conventional engines is greatly reduced.

  * During combustion and expansion, the hot gases are in contact almost only with the deformable pocket made of flexible material. However, its materials, especially elastomers, have a low thermal conductivity compared to that of metals. This allows, thermodynamically, a more "adiabatic" expansion, therefore a better engine efficiency. -4-

Claims (3)

  1) Combustion chamber of an internal combustion engine characterized in that   that it mainly consists of a deformable pocket wrapped in a braid.   2) Combustion chamber according to claim 1 characterized in that a core is integrated therein. 3) Combination of combustion chamber according to claim 1 or 2 characterized in that it allows the integration of the engine thus formed in at least one wheel of a land vehicle.