FR2609753A1 - Internal combustion engine with a rotary piston - Google Patents

Abstract

The present invention relates to an internal combustion engine. The engine is characterised in that it particularly comprises a first piston 11, a second piston 12 which can rotate variably about the axis of the cylinder 1, 2, the two pistons delimiting a working chamber, and a device 20 for varying the speed of the pistons 11, 12. The invention finds an application, for example, in the automotive field.

Description

 The present invention relates to an internal combustion engine with rotary piston, comprising at least one hollow cylinder in which said piston rotates in sealed contact with the internal surface of the cylinder by helping to define a chamber forming a working chamber of variable volume and angularly moving. during the rotation of the piston, varying in volume between a minimum volume giving rise to the ignition of an air-fuel mixture contained in the chamber and a maximum volume, during each revolution of the piston, of the burnt gas exhaust ports and of the air or mixture admission, situated in the internal face of the cylinder at angularly offset locations so as to be successively uncovered and closed by the piston with a view to the evacuation of the burnt gases and the admission of air or said mixture.

 Motors of this type are already known. For example, motors of the wankel type have a cylinder whose inner surface has a complex shape with several lobes and is crossed by an eccentric shaft carrying the piston of troncoldale shape adapted to the internal surface of the cylinder.

 These known engines have the major drawback that, due to the complicated shape of the cylinder and its rotor, the problem of sealing, for example, is practically not controllable in a satisfactory manner.

 The object of the present invention is to propose an internal combustion engine with a rotary piston which does not have the drawbacks of known engines.

 To achieve this object, the engine according to the invention is characterized in that the cylinder has an internal space of circular cross section, said piston is arranged to constitute a first piston uniformly rotatable around the axis of the cylinder, than a second piston is variably rotatably mounted around the axis of the cylinder, in sealed contact with the internal surface of the latter and angularly offset with respect to the first piston so as to delimit with said latter and the internal surface of the cylinder said working chamber, that the pistons have a cross section perpendicular to the axis of the cylinder advantageously in the form of a segment of a circle coaxial with the cylinder, and in that it comprises a variator of the rotary speed of the pistons, adapted so that the first piston rotates at a higher speed than the second in its circular travel part, located between said first angular location and a second predetermined angular location, in front l of the exhaust port, and the second piston rotates at a higher speed during the remaining part of the circular stroke of the first piston in the same direction as the latter so that the working chamber has its volume again minimal said first angular location.

 According to an advantageous characteristic of the invention, the variable speed drive is adapted to immobilize the second piston during the aforementioned first part of the stroke of the first piston.

 According to yet another advantageous characteristic, the variable speed drive comprises a pinion driven in rotation by the shaft of the first piston and meshing a toothing provided at the periphery of an oblong member comprising a rectilinear middle part and at its two ends a semi- circular, this member comprises a rectilinear central recess, which extends in the axis of the member and forms a guide path for the displacement in non-rotary relative translation of an element advantageously of rectangular cross section, integral in rotation with the shaft of the second piston, the latter being stationary as long as the piston meshes with the rectilinear parts of the toothing of said member and driven in rotation when the piston meshes with the semi-circular parts of the toothing of said member.

 According to yet another advantageous characteristic of the invention, two cylinders, each with two pistons, are combined by providing between them a chamber opening in the internal space of the two cylinders at the first angular location of the chamber in each cylinder , the first pistons as the second pistons of two cylinders are interconnected to rotate synchronously, by suitable means such as a gear.

 According to yet another advantageous characteristic of the invention, one of the pistons of a cylinder is made integral in rotation with a first shaft over a part such that half of its length and coaxially surrounds the other part while allowing it to remain an annular space, and in that the other piston is mounted for rotation with a second tubular shaft mounted coaxial with the first shaft in said annular space, the two shafts being taken out of the cylinder at least at one end of the latter for be kinetically linked to each other by the aforementioned variable speed drive.

The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly during the explanatory description which follows, made with reference to the appended schematic drawings given solely by way of example illustrating a embodiment of the invention, and in which
- Figure 1 is a view in axial median section of the cylinder block of an engine according to the present invention
- Figure 2 is a cross-sectional view along line II-II of Figure 1, the pinions of each cylinder occupying their angular position of formation of the minimum volume of the combustion chamber
- Figure 3 is a perspective view, with cutaway of the central part III of the cylinder block according to Figure 1, after removal of the semi-spherical end parts of the cylinder
- Figure 4 shows a sealing segment used in a cylinder according to the present invention
- Figure 5 is a schematic perspective view in partial section of a variable speed drive according to the present invention
FIGS. 6 and 7 are schematic views intended to illustrate the operation of the variable speed drive according to FIG. 5, and
- Figures 8 to 11 schematically illustrate the operation of an engine according to the present invention, by representing it at four different times of an engine cycle according to the present invention.

 The figures show an internal combustion engine according to the present invention, the cylinder block of which comprises two cylinders 1 and 2, the central part 3 connecting these two cylinders on at least part of their axial extension is shaped to delimit a chamber 4, advantageously of parallelepiped shape, which opens at its two ends in the internal spaces of the cylinders 1 and 2. In the illustrated embodiment of the engine according to the invention, the internal space of each cylinder has a circular cross section and comprises a cylindrical central part 6 closed at its ends by elements 7 and 8 of semi-spherical shape. As shown in Figure 1, the upper semi-spherical element 7 is produced separately and can be fixed to the central part 6 by any suitable means shown in 9. Two pistons 11 and 12 are mounted in the internal space of each cylinder , rotatable around the axis thereof.

The two pistons are angularly offset and have a cross section having the general shape of a segment of a circle having a radius slightly less than the radius of the cross section of the cylindrical internal surface of the corresponding cylinder. As shown in Figure 1, each piston is shaped so as to have an axial cross section such that its peripheral surface follows the internal surface of its cylinder over practically its entire extension to ensure tight contact between the internal surface of the cylinder and the pistons during their rotation in the latter.

 Regarding the mounting of the two pistons 11 and 12 in their cylinder, it can be seen that a shaft 14 passes through it axially. The piston 11 is secured in rotation to this shaft 14 over substantially half of its internal axial length 15, while on the remaining part 16 of its length, it is set back from the shaft 14 to leave a partially annular space 17 The piston 12 is integral in rotation with the hollow shaft 18 mounted coaxial with the shaft 14 in said space 17. The shafts 14 and 18 are both pulled out at the upper end of the cylinder and connected to the outside kinetically thereof by a variable speed drive 20 which will be described later, in detail.

The rotation shafts 12 of the pistons 11 of the two cylinders 1 and 2 are kinetically connected by a gear device 21. A gear device 22 of the same type kinetically connects the rotation shafts 18 of the pistons 12 of the two cylinders.

 The chamber 4 in the central part of the engine block is arranged to constitute the combustion chamber of the engine. To this end, it includes the ignition means such as spark plugs, shown diagrammatically at 50, and, where appropriate, an injector, not shown. As indicated in FIG. 2, the wall of each cylinder 1, 2 is traversed by channels constituting exhaust ports 24 for the burnt gases and for admission 25 of air or of an air-fuel mixture.

These lights are equipped with valves, such as single spring valves, not shown. It can be seen that the lights 24 and 25 are angularly offset in the internal wall of the cylinders, the exhaust light being closer to the combustion or explosion chamber 4 than the intake light.

These lights are closable by the pistons 11 and 12.

 To seal between the peripheral surface of the pistons and the internal surface of the cylinders, sealing segments 26, as shown in FIG. 4, are housed in grooves 27 formed in the peripheral surface of the pistons, along a generatrix. . So that the sealing segments 26 are constantly retained in their grooves 27 and applied against the bottom thereof, provision has been made, for example, at the mid-height of the chamber 4, in the opening of the internal space of the cylinder in the chamber, support bars 30, which ensure the retention of the sealing segments 26 in their grooves 27 during the interval of passage in front of said openings. To cool the cylinder, the wall thereof is provided with internal channels or spaces 31 of a cooling system by forced circulation of a fluid such as a liquid. In addition, the external surface of the cylinder can carry ribs or fins 32 for cooling by ambient air.

 Referring to FIGS. 5 to 7, the variator 20 of the rotary speed of the pistons 11 and 12 of a cylinder 1 or 2 will be described below. It can be seen that the rotation shaft 14 of the piston 11 transmits its rotation by sets of pinions 35 to a pinion 36 which meshes with the teeth provided around a member of oblong shape 38. The central part 39 of the latter is of rectangular shape, while the ends 37 are of semi-cylindrical shape. Thus the sides of the middle part 39 are shaped as rectilinear racks. The member 38 comprises a recess 40 of rectangular section shape, which extends in the longitudinal axis of the member 38 and forms a guide for an element 41 with a square cross section. This element is integral in rotation with the shaft 18 for rotation of the piston 12. The recess 40 and the element 41 are dimensioned in such a way that the latter can only carry out in the recess 40 a translational movement. Owing to this configuration and the relative arrangement of the various elements making up the variable speed drive, the member 38 performs a rectilinear movement as long as the pinion 36 meshes with one of the lateral sides 39 forming rectilinear racks and a rotational movement when the pinion 36 comes into engagement with one of the parts of semi-circular shape 37. To reduce the friction forces which the member 38 must overcome during its complex movement, the latter is supported on a ball bearing 42, these balls being distributed over the entire surface swept by the member 38 during its movement. It should be noted that the recess has a length such that the axis of rotation of the recess 41 merges with the center of the rounded parts 37, when the member 38 is in an extreme position of its rectilinear movement.

 To complete the description of the structure of an engine according to the present invention, it should also be noted that the variable speed drive 20 as well as the pinions of the transmission gear devices 21 and 22 are located inside waterproof boots. in an oil bath, such as the housing 43 surrounding the variable speed drive 20 or the shoemakers indicated at 44 mounted on the cylinder block at the top and / or at the bottom of the cylinders.

 With particular reference to FIGS. 6, 7 and 8 to 11, the operation of the engine according to the present invention, which has just been described, will be described below.

 At the start of an engine cycle, the positions of the pistons 11 and 12 are those shown in FIGS. 2 and 8. The pistons are in their closest angular position, at the level of the chamber 4 formed in the central part of the block -engine. The working chamber formed by the chamber 4 and the space 51 delimited between the substantially radial surfaces 46 and 47 of the pistons 11 and 12, which will hereinafter be called the variable-volume chamber, then has its minimum volume. In this relative starting position of the pistons 11 and 12, the member 38 with the toothed periphery, occupies the position indicated in FIG. 5 and that which is shown in solid lines in FIG. 6. When the air-fuel mixture being in the variable volume chamber is on, the piston 11, under the effect of the forces generated by the explosion, rotates in the direction of the arrow F1. This overlaps the rotation of the pinion 36 in the direction of the arrow F2 (FIG. 5). This pinion being engaged with one of the lateral parts with rectilinear racks 39 of the member 38, this member performs a rectilinear movement from its starting position a to its position b indicated in dashed lines in FIG. 6. This movement purely rectilinear of the member 38 ends when the pinion 36 begins to mesh with the toothed portion 37 of the member 38 which follows the rack portion 39. As long as the member 38 does not perform a rotary movement, the cam element 41 inside the guide recess 40 remains stationary, which has the consequence that the drive shaft 18 of the piston 12 does not rotate and the latter remains in its position according to FIGS. 2 and 8. L transmission gear 35, the pinion 36 and the member 38 are dimensioned such that at the end of the rectilinear movement of the member 38, the piston 11 occupies the position indicated in FIG. 10, in which it discovers the intake light 25, after passing through the position according to the figure e 9. In this position the piston 11 has just discovered the exhaust port 24, which allows the evacuation of the burnt gases for example by sweeping, provided of course that the exhaust valve is open. In the constellation of pistons, shown in Figure 10, the admission of air or an air-fuel mixture can take place.

 As soon as the pinion 36 begins to mesh with the semi-circular toothed part 37 of the body 38, that is to say as soon as the body 38 has reached position b (FIG. 6) it begins to rotate, causing the element 41, which is integral in rotation with the shaft 18 of the piston 12. The latter therefore begins to rotate in the same direction of rotation as the piston 11. The ratio of the transmission gears of the rotary movement of the piston 11 to the piston 12 is chosen so that the piston 12 rotates at a higher speed than that of the piston 11, such that it can catch up with the latter so that the constellation of the pistons 11 and 12 shown in FIGS. 2 and 8 is reproduced. During this phase the variable volume chamber 48 decreases, which causes the compression of the air or of the mixture contained in this chamber. In FIG. 8, the compression is maximum and a new engine cycle is triggered by the ignition of the compressed content in room 30. It should be repeated r that in the constellation of FIG. 8, the body 38 again occupies position a according to FIG. 6, after having made a rotation at an angle of 1800.

 It should be noted that numerous variants can be made to the engine which has just been described. For example, it is not necessary to use two cylinders arranged in pairs. A single cylinder could suffice and the explosion or ignition chamber 4 would then be shaped accordingly.

The shape of the pistons may be different from that shown in the figures. The catch-up movement of the piston 12 can begin before the piston 11 has reached the position shown in FIG. 10, for example from the moment when the piston 11 has discovered the exhaust port 24 (FIG. 9).

 It will be understood from the above, that in the engine according to the present invention the piston 11 in each cylinder rotates at a substantially constant speed. This movement is transmitted to the motor output shaft by the shaft represented at 48 in FIG. 1.

On the other hand, the piston 12 performs a rotational movement at variable speed, obtained from the movement of the piston 11 via the speed variator 20.

 The use of the principle of the piston or pistons with two rotors is by no means exclusive to the internal combustion engine and is therefore not exhaustive. This principle can be adapted to the construction of other mechanical devices, for example compressors, etc.

Claims (9)

 1. Internal combustion engine with rotary piston, comprising at least one hollow cylinder in which said piston rotates in sealed contact with the internal surface of said cylinder while helping to define a chamber forming combustion and working chamber and moving angularly during the rotation of the piston varying in volume between a minimum volume giving rise to the ignition of an air-fuel mixture contained in the chamber and a maximum volume, during each revolution of the piston, of the exhaust lights of the burnt gases and of admission of air or of said mixture, situated in the internal face of the cylinder at angularly offset locations so as to be successively uncovered and closed by the piston with a view to the evacuation of the burnt gases or the admission of air or of said mixture, and means for igniting said mixture located at a first angular location of the cylinder, to which the chamber of minimum volume is formed, characterized in that the cylinder (1, 2) pres ente an internal space of circular cross section, said piston (11) is arranged to constitute a first piston uniformly rotatable around the axis of the cylinder, that a second piston (12) is mounted variably rotatable around the axis of the cylinder (1,2) in sealed contact with the internal surface of the latter and angularly offset with respect to the first piston so as to delimit with the latter and the internal surface of the cylinder said working chamber, as the pistons (11, 12) have a cross section perpendicular to the axis of the cylinder advantageously in the form of a segment of circle coaxial with the cylinder, and in that it comprises a variator (20) of the rotary speed of the pistons (11, 12) adapted so that the first piston (11) rotates at a higher speed than the second (12) in its circular stroke part located between said first angular location and a second predetermined angular location, downstream of the exhaust port (24) and the second piston (12) rotates at a higher speed during the remaining part of the circular stroke of the first piston, in the same direction as the latter, so that the working chamber delimited by the two pistons (11 and 12) again has its minimum volume at said first angular location.  2. Motor according to claim 1, characterized in that the speed variator (20) is adapted to immobilize the second piston (12) during the aforementioned first part of the stroke of the first piston (11).  3. Motor according to claim 2, characterized in that the speed variator (20) comprises a pinion (36) rotated by the shaft (14) of the first piston and meshing a toothing provided at the periphery of a member ( 38) of oblong shape comprising a rectilinear middle part (37) and at its two ends a circular part (39), this member (38) comprises a central recess (40) advantageously parallelepipedic, which extends in the axis of l member (38) and forms a guide path for the displacement in non-rotary relative translation of an element (41) advantageously of rectangular cross section, integral in rotation with the shaft (18) of the second piston (12) , the latter being stationary as long as the piston (11) meshes with the straight parts (39) of the toothing of said member (38) and rotated when the pinion (36) meshes with the semicircular parts (37) of the toothing of said organ (38).  4. Motor according to one of the preceding claims, characterized in that each rotor (11, 12) comprises a peripheral surface shaped to match the internal surface of the cylinder (1,2) and in that said peripheral surface carries segments d 'sealing (26) each extending along a generator so as to ensure sealing between the cooperating surfaces of the pistons (11, 12) and the cylinder (1,2).  5. Engine according to one of the preceding claims, characterized in that the cylinder (1,2) has, axially aligned, a cylindrical central part (6) with circular cross section, closed at its ends by semi-spherical parts ( 7.8).  6. Engine according to one of the preceding claims, characterized in that two cylinders (1,2), each with two rotors (11, 12) are combined by providing between them a central chamber (4) opening in the internal space of the two cylinders at the aforementioned first angular location of the cylinders, that the chamber (4) is shaped as an explosion chamber and comprises the aforementioned ignition means (50) and in that the first pistons (11) as the second pistons (12) of the two cylinders (1,2) are interconnected to rotate synchronously, by suitable means such as gear devices (21, 22).  7. Engine according to one of the preceding claims, characterized in that the first piston (11) of a cylinder (1,2) is made integral in rotation with the shaft (14) axially passing through the cylinder, on a part such that advantageously half of its length and coaxially surrounds the remaining part, leaving an annular space (17), and in that the other piston (12) is mounted in rotation with a tubular shaft (18) mounted coaxial with the shaft (14) in said annular space (17), the two shafts (14, 18) being taken out of the cylinder at least at one end of it to be kinetically connected to each other by the variable speed drive (20 ).  8. Engine according to one of the preceding claims, characterized in that cooling channels (31) by preferably forced circulation of a fluid such as a liquid are provided in the walls of the cylinder (1,2).  9. Engine according to one of claims 4 to 8, characterized in that at least one support bar (30) is provided at the opening of the combustion chamber (4) in the internal space d 'a cylinder and adapted to be able to retain the sealing segment (26) in its working position when it passes in front of said opening.