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MAQUINA PARA PISTONES GIRATORIOS Y PALIZA CONTROLADA (PRBC)

Principios cyclo 4 veces Conversión del movimiento Sistema de variable calzand
de las válvulas
Sistema de regular del rate de compresión Rendimientos y aplicaciones


La traducción en español de esta página no está disponible, thank you for su conocimiento


The conversion of the motion is probably a domain as important as its generation...

If one looks at the history of the volumetric motors, which use pressurized gases rather than kinetic gases, the designers didn't take care about this aspect. For example, the engine with pistons, rods and crankshaft , possesses a kinematics, that in addition to be very unbalanced, immediately imposes a frozen law of conversion : even while making vary the radius of the crankshaft or the lentgh of the rods, the kinematics of the TDC/BDC is deplorable (too much long and stationary). One could mention other examples, as the Wankel where the evolution of the volume of the combustion rooms, according to the angle of rotation of the output shaft, is not controllable, because of an epitrochoïdal geometry that imposes all as soon as the triangular geometry of the rotor is chosen.


All engines currently known are incapable to arbitrary impose an evolution of the volume of every room
 according to the angle of rotation of continually rotating shaft of the motor.


And yet, to one time where one tries to pilot the auto-ignition of gases by the rise of temperature during the compression (with new field of research like the controlled auto-ignition (CAI), high charge compression ignition (HCCI), active thermo atmosphere (ATAC), and even piloted detonation...), very few concepts worry about that and bring breaktough about the subject. Only some inventors in Quebec noticed the advantage of a sudden and intense TDC to synchronize the auto-ignition of fresh gases very exactly with the TDC, so that, in a first time, the combustion is the most complete and clean, and in a second time, the relaxation of gases occurs as early as possible to push appropriately the mobile parts of their machine...


However it would be necessary to be capable to generate the volume that one WANTS in EVERY ROOM
 according to the angle of rotation of the rotating shaft of the engine.


In the case of the SYCOMOREEN's rotary pistons engines, it needs to CONTROL the BEATINGS of the pistons... more precisely :
- their angular amplitude
- their minimal and maximal angles of alternative rotation
- but also and especially the law of evolution of the beating during a cycle "mini angle - > maxi angle  - > mini angle"


1. Motion to convert


The typical PRBC engines are based on p pairs of pistons distributed linearly if  p = 1 and circularly as soon as p is superior or equal to 2. The set of the centers of rotation of every piston forms then :

-         if p = 1, a segment

-         if  p superior or equal to 2, a regular polygon with 2p sides


One defines then, with the help of an adequate cover, 2p rooms of variable volumes, which pass alternately from their minimal volume to their maximal volume, and it requires the intermittent contact between every piston and its 2 nearests neighbors. What implies :

angular amplitude of the motion of rotary pistons = Pi / p radian or 180 / p degrees

 

2. Proposed system

It is possible to use a generic system of conversion of the rotative alternated motion of every piston in a continuous rotation on a shaft of which the axis of rotation is in the center of the said segment (if p=1), or of the said regular polygon (if p>=2), and that, whatever is p superior or equal to 1, whose principle is the next one : 

From eccentric pebbles in relation to the axis of rotation of the pistons and bound of these pistons, one recovers 2p motions of alternate translation along the mediators associated to the rotation's centers of 2 consecutive pistons. This motion is transmitted to 2p grooves, equipped themselves with one or several pebbles, which push on a continuously rotative central cam, bound on the output rotative shaft of the motor, or the power entry shaft of the pump (or compressor).

Components of the generic system of conversion of motion for PRBC engines

Generic system of conversion in the case of only one pair of pistons.

glissière : groove        came centrale : central cam        galet excentré : eccentric pebble   

  galet de glissière: groove's pebble        axe des pistons rotatif : piston's rotative axis       


Every contact eccentric / groove pebble is systematically bilateral either while making displace the eccentric pebble in a groove whose width is worth the diameter of the pebble (what will be represented here), either while bringing up a slippery sliding part in the groove mounted rotative on the eccentric pebble.

2 options of cams are possible, and don't exclude themselves mutually :

-         exterior profiled cam when the pebble of groove is placed in exterior radial position

-         interior profiled cam when the pebble of groove is placed in interior radial position

-         this distinction becoming less clear for the particular case p=1 because the 2 symmetrical pebbles are in contact with the same profile of cam.

 

3. Advantages of the mechanism

 The present mechanism based on a central rotative cam offers very numerous assets :

mini angle = Pi - angle maxi

4. Examples of rotary central cam systems

The following pictures show the extreme adaptability of the rotary central cam design with all type of PRBC engines.



Bi lobed rotative central cam for a 2PRBC engine

p = 2, exterior cam and pebbles

Bi lobed rotative central cam for a 2PRBC engine

p = 2, cam and interior pebbles


Tri lobed rotative central cam for a 3PRBC engine

p = 3, cam and exterior pebbles

Tri lobed rotative central cam for a 3PRBC engine

p = 3, cam and interior pebbles


uadri lobed rotative central cam for a 4PRBC engine

p = 4, cam and exterior pebbles

uadri lobed rotative central cam for a 4PRBC engine

p = 4, cam and interior pebbles


Penta lobed rotative central cam for a 5PRBC engine

p = 5, cam and exterior pebbles

Penta lobed rotative central cam for a 5PRBC engine

p = 5, cam and interior pebbles.


5. Animations of mechanisms to rotary central cam 2Pi / cyclic p

Rotative central cam kinematics with one lobe for 1PRBC engines
 Piloted Motion 45°/135° and 90° of amplitude with symmetrical beating
Rotative central cam kinematics with one lobe for 1PRBC engines
Piloted Motion : 0°/180° and 180° of amplitude with symmetrical beating
Rotative central cam kinematics with two lobes for 2PRBC engines
Piloted Motion : 0°/90° and 90° of amplitude with asymmetric beating
Rotative central cam kinematics with three lobes for 3PRBC engines
Piloted Motion : 0°/60° and 180° of amplitude with symmetrical beating
Rotative central cam kinematics with five lobes for 5PRBC engines
Piloted Motion : 0°/36° and 36° of amplitude with asymmetric beating
Cinématique à came centrale rotative pour battement super asymétrique à 3lobes adaptés aux machines 3PRBC
Mouvement piloté : 0°/60° et 60° d'amplitude avec battement super asymétrique

6. Over multi-lobed rotary central (2Pi /kpcyclic cam

The minimal number of lobes of the rotary central cam to make the engine run  is worth the p number of pairs of pistons

However, the rotary central cam can be over multi-lobed, by machining  k . p lobes on the cam where k is positive integer superior or equal to 2.

Why to over multi-lobe the rotary central cam ?

it multiplies by k the numbers 
necessary cycles to 1 have one revolution of the cam...

therefore
it multiplies by k the nominal compactness of the motor !


1. The cam, in addition to convert the motion, plays a complementary role of reducing gearings by a k factor

2. The use of pebbles mounted on ball-bearings converts the power with an output rate of about  95%

(contrary to the successive trains of gearings whose output falls quickly unless 90% by rubbings / barbotages in oil)

3. All this functionalities are achieved by a single part with a thickness of some millimiters
 (laser cuttable or usinable... in a simple plate of steel)


Under the condition to respect transmission angles which lead to acceptable efforts wether the engine works as a motor or a pump, and to give sufficient size to the rotary central cam, k can easily pass 3 or 4, in particular for engines having few pairs of rotary pistons.

The following animation belows show the extreme variety of possible and arbitrary motions with over multi-lobed cams for all type of PRBC engines.
Rotary central cam kinematics with 6 lobes for 1PRBC engines
Piloted motion : 0°/180° and 180° of amplitude with asymmetric beating by a 1 x 6 over multi-lobed cam
Rotary central cam kinematics with 7 lobes for 1PRBC engines
Piloted motion :  0°/180° and 180° of amplitude with symmetrical beating by an 1 x 7 over multi-lobed cam
Double rotary central cam kinematics with 4 lobes for 2PRBC engines
Movement piloted 0°/90° and 90° of amplitude to symmetrical beating by two (2 x 2 over multi-lobed) cams 
Double rotary central cam kinematics with 6 lobes for 3PRBC engines
Piloted motion : 0°/60° and 60° of amplitude with symmetrical beating by two (3 x 2 over multi-lobed) cams
Rotary central cam kinematics with 12 lobes for 4PRBC engines
Piloted motion : 0°/45° and 45° of amplitude with asymmetric beating by a 4 x 3 over multi-lobed rotary central cam


7. Simplifed system of conversion for 2PRBC engines


One can also develop simplified systems of conversion, especially for 2PRBC engines, it is possible to convert the motion with only one rotary part bound on 2 manetons actuated by orthogonal grooves, they-even manipulated by a kinematics based on a deformable lozenge. The following system can be qualified as a double crossed sinus mechanism.
"double crossed sinus" mechanism of conversion for 2PRBC engines

Piloted motion : 0°/90° and 90° of amplitude with linear symmetrical beating



"double crossed sinus" mechanism of conversion for 2PRBC engines
Partial view of the mechanism "doubles sinus" for a 2PRBC engine


"double crossed sinus" mechanism of conversion for 2PRBC engines
Partial view of front side of the mechanism "doubles sinus" for a 2PRBC engine
in charcoal gray: orthogonal grooves,        
in yellow and foreground : rotary output shaft
in yellow to the second plan : eccentric bound of the rotary pistons
blank: rod of the deformable lozenge




Principios cyclo 4 veces Conversión del movimiento Sistema de variable calzand
de las válvulas
Sistema de regular del rate de compresión Rendimientos y aplicaciones
Sistemas para la conversión de los movimientos y las energías renovables
Motores
y Bombas
PRBC Concepto
POGDC Concepto

Máquinas especiales
de STIRLING


Regrese a la carta principal