FR2501288A1 - IMPROVEMENTS IN THE POWER SUPPLY OF TWO-STROKE ENGINES - Google Patents

Abstract

THE INVENTION CONCERNS A TWO STROKE ENGINE OF THE TYPE INCLUDING A SEPARATE TRANSFER OF RICH CARBIDE AIR. ACCORDING TO THE INVENTION, THE FUEL INJECTION IS CONTROLLED BY A REGULATION CHAMBER29, 32 DEPENDING ON VARIATIONS IN THE DYNAMIC PRESSURE REVENTING AT TWO DISTANT POINTS17, 22 OF AN AUXILIARY CHAMBER13 FOR STORING THE PRE-COMPRESSION ENGINE OPENING INTO THE COMBUSTION CHAMBER2 BY A LIGHT16, LOCATED LOWER THAN THE OUTLETS7 OF THE MAIN TRANSFERS. THE INVENTION ALLOWS AN IMPROVEMENT IN THE EFFICIENCY AND A DECREASE IN POLLUTION OF TWO STROKE ENGINES.

Description

The present invention relates to improvements to a motor

  two-stroke internal combustion for improved performance and operating performance by improving combustion and reducing the loss of fresh gas to the exhaust. It is well known that the two-stroke engine has compared to the four-stroke engine advantages of simplicity and

  higher mass power, especially for

  cubic meters. On the other hand, the very principle of feeding and sweeping the engine cylinder with the fresh carbureted gas, with the exhaust ports open, leads to losses of fresh gas at the exhaust. These losses are detrimental to

  performance of the engine in terms of efficiency (

  summation) than on that of pollution.

  Many and various attempts have been made to

improve these conditions.

  One solution is to pre-scan the cy-

  clean the engine with clean air and inject the fuel gas

  rich mixture only when the exhaust port is closed.

  This a priori satisfactory solution presents difficulties of execution, in particular at the level of the injection under pressure of the rich fueled mixture after the closing of the exhaust and at the level of the problems of distribution. In practice, the two-stroke engine loses its advantages of simplicity by

  compared to the four-stroke engine and is no longer competitive.

  A preferred intermediate solution is to provide separate transfers for the scavenging air and for the carburetted gas mixture and to draw the combustion chamber and the piston, so as to trap the rich carbureted mixture in the chamber behind a cushion. scavenging air, so as to limit exhaust losses to the lowest possible amount of carbureted air. In practice, we are limited in this way by the questions of injection pressure and homogeneous mixture in the combustion chamber of the fuel mixture, too much stratification of the fuel mixture in the chamber

  of combustion affecting the efficiency of operation of the engine.

  The object of the invention is to solve the problems

  mentioned, ie to limit pollution of two-stroke engines and to increase their operating efficiency by

  using the principle of separate transfers for primary air

  pal of sweeping and comrbustion, and for the fuel-rich mixture injected

  in the chamber of ccbustion, and that sanls use of device

  In addition, it is also possible to use this method to dispense with the fuel-injector chamber of the fuel-injected injector. by a slight increase in pressure due to the pressure variations in the crankcase; however, it is difficult

  of nmoedler -x te ie a! i'untatioa An function of the variable equation of the engine.

  At the same time, and resolving the difficulties mentioned

  In this case, the use of the load-bearing unit is used for its food.

  fuel mixture n injected into fuel by an imbrare type fuel pump, acting (directing or direct) by

  the pressure variations appearing in the crankcase during the fo-

  motor, said motor being characterized in that said injector

  opens a second chamber of storage of the pre-ompression

  ter connected to it by a non-return valve or any equivalent, and said injector is located in said room Auciliaixe

  the way it is created by different types of pressure.

  209st sw.e in'fjec + tion x d caro-rant when mnivy _, $ such as a light or O s quies yesnts, deo t an output of the ladit chadMbre

  USI DIARY in drecticn of said chateau mo'tur cb3'stion. he ap-

  para: t that the use of such a provision is an effective injection

  of the mCla-nge CruR in the car of C uston, at the most

  bAn and under pressure.Vdulable the most appropriate to the proper functioning

  of the photo. ib outra, this is the place where a system of

  As a result, the regulation is automatic thanks to the laws of fluid dynamics and allowing all the adjustments and adjustments to be made.

  possible. According to another characteristic of the invention, the auxiliary chamber

  liar emerges into the engine's acceleration chamber through an orifice of

  lower transfer (relative to the top dead center of the

  tor; PHM) that sweeping and filling transfers

  of said combustion chamber. This is extremely

  vorable because it reduces or even eliminates gas losses

  exhaust, and this is possible because of the pre-

  view of the aforementioned auxiliary chamber for storage of pres-

  configuration and / or positioning

  of the injector in this auxiliary chamber. According to an advantageous characteristic of construction,

  said injector is located substantially at a level of

  narrowed intermediate formation of the auxiliary chamber, forming Venturi. According to another characteristic of the invention,

  the injector is connected to a control chamber which

  carries a membrane actuating a closure member (such

  valve) of the fuel supply duct

  mented by said fuel pump, and said membrane is

  continuously at two opposing pressures taken in said auxiliary chamber at remote points, subjected to different dynamic pressures, particularly at the moment of

  the opening of said outlet of said chamber auxi-

  hlaire to said combustion chamber. Thus, automatically and in accordance with adjustable laws, the injection of the exactly desired quantity of fuel into the auxiliary chamber to be transferred into the combustion chamber is achieved at the effective transfer times of the fuel mixture to the fuel chamber.

  combustion chamber, the quantities of fuel injected

  to be automatically adjusted according to the instantaneous

engine operation.

  The invention will appear more clearly with the help of

  following description, made with reference to the

  given only as examples and schematically

some embodiments.

  In these drawings: FIG. 1 is a sectional view showing schematically

  a two-stroke engine equipped with the means of the invention.

  Figures 2 and 3 are views similar to that of the

  Figure 1, and relate to two variants.

  Figure 4 shows a modification of the variant of the

figure 3.

  Figure 5 is a distribution diagram facilitating the

understanding of the operation.

  Referring firstly to Figure 1, which shows a two-stroke engine 1, comprising a combustion chamber 2, formed between the cylinder 3 and the piston 4 of the engine. 5, schematically illustrates one of the two lateral transfers allowing the main air to scan

  and combustion, pre-compressed in the casing 6 during the movement

  downward movement of piston 4 towards its bottom dead center,

  in the combustion chamber when the

  blocked 7 destranferts5 are released by the piston. At 8, the exhaust pipe opening through the lumen 9 can be seen in the chamber 2. The air is pre-compressed in the casing 6, being fed by a conduit 10 controlled by the butterfly

  11 gases. In 12 has been shown schematically a check valve

  putting the pre-compression in the crankcase 6. All that has

  has been described so far is all that is more classic.

  According to the invention, there is provided for the engine an auxiliary chamber 13 for storing the pre-compression of air in the casing 6 during the descent towards the low-word point of the piston 4. In the example illustrated, the auxiliary chamber 13 was shown separated from the engine as an appendage that was

  added and which communicates with the housing by a hole 14 ob-

  flared by a non-return valve allowing the passage of

  air from the housing 6 to the auxiliary chamber 13 and the

  in the other. It is understood, however, that the auxiliary chamber 13 could be formed in the body of the engine, the illustrated example showing the auxiliary chamber 13 separated for clarity, and corresponding further to the

test prototype made.

  The auxiliary storage chamber 13 opens on the other hand

  in the combustion chamber 2 by a light 16. Avanta

  and, as will be explained more clearly later, the light 16 is located in the chamber 2 a little lower than the lights 7 of the outlets of the main transfers 5, and its section can be reduced compared to the section

  lights 7 of the main transfers. The report of the

  tions will advantageously be between 1/5 to 1/20.

  The injection of fuel is made at the appropriate moment, by an injector 17, in the auxiliary chamber 13. In the example shown, the injector 17 is placed in a narrowed section

  18 of the chamber 13 forming Venturi.

  The injector 17 is supplied with fuel by a fuel pump.

  membrane 19, connected by a conduit 20 for fuel supply.

  from a reservoir (not shown). The pump

  membrane 19 is actuated under the effect of pressure variations.

  sion prevailing in the auxiliary chamber 13 during the various operating times of the engine. Pressure taking is

  made by a conduit 21, opening at 22 in the chamber

  xilary 13, and acting on the diaphragm 23 of the pump 19 on one side of it in opposition to the action of a spring 24. The

  pressure pulsations appearing in room 13 provoked by

  pumping action of the pump 19, allowing through the provision of nonreturn valves 25, 26, to bring fuel under pressure at an orifice 27 controlled by a closure member such as a valve or needle 28

  27 leading to a balancing chamber 29. A small

  spell 30 normally maintains the closed orifice 27 by applying

  tion of the needle 28 against said orifice, and that as long as the pressures prevailing on either side of a membrane 31 closing the bottom of the balancing chamber 29 and separating it from an adjacent chamber 32 communicating with the conduit 21 are substantially equal. In these circumstances, it can not

there is fuel injection.

  On the other hand, when an imbalance of

  between Chambers 29 and 32, and more specifically a

  pressure in the chamber 29 relative to that prevailing in the chamber 32, the membrane 31 controls against the

  spring 30, the clearance of the needle 28 allowing the introduction

  fuel duct in chamber 29 towards the

  jector 17. Such imbalance occurs when the light 16 coming to be released by the piston 4 which approaches its

  low dead point, an effective dynamic injection of stagnant air

  cke under pressure in the auxiliary chamber 13 occurs

  to the combustion chamber 2, the pressure at

  calf injector 17 placed at the Venturi neck 18 of the chamber.

  helper 13 then falling sharply below this

  the reigning higher in the chamber 13, at the pressure tap 22. As it has been understood, this arrangement allows the automatic injection of fuel into the chamber

  13 at the precise moment when the third trans-

2501288 '

  when the light 16 is released by the piston

4.

  The operating cycle is understandable, furthermore

  reference to the distribution diagram of Figure 5.

  On this diagragm, PMH and PMB have been identified as the angular coordinates corresponding to the moment when the piston reaches the top dead center and then the bottom dead center. The arrow indicates the

direction of motor rotation.

  According to the example shown, the opening of the exhaust, o10 indicated by the letters O.E., occurs a little before the

: piston is halfway.

  Continuing its descent, the piston discovers a little more

  late at O.T, the main transfers 5

  first filling and sweeping of the chamber of com-

  bustion 2 by the main compressed air in the housing 6, under

  the piston which c-continues its descent. It should be noted that as long as this

  the opening did not occur, the pressure in the housing 6 was raised, and some of the compressed air was stored

  in the auxiliary chamber 13 whose light 16 is closed.

  When the transfers occur, the pressure drops in the casing and the check valve isolates the auxiliary chamber.

  13 of the casing, now in the auxiliary chamber

  necessary to ensure the injection of the mixture

carbureted, but not later.

  Indeed, the piston continuing its course, releases a

  little later, the 16th point indicates O.T ', a little bit

  before the bottom dead center. The injection of rich carburized mixture then occurs in the combustion chamber thanks to the pressure stored in the auxiliary chamber 13 and thanks to the pressure differential appearing between the points 17 and

  22 during the dynamic flow of the carburetted air of the chamber

  13 to room 2, as previously explained.

  The injection by the light 16 of the rich fuel mixture being substantially opposite to the exhaust port 9, it will be noted that between the rich fuel mixture and the exhaust is interposed a pre-scan air cushion. injected

  and which continues to be injected by the main transfers 5.

  The risk of loss to the

fresh gas.

  The piston then passes through the bottom dead center, and

  cons successively the closing of the light 16 stopping the injection at the marked point F.T ', the closing of the main transfers at the point marked F.T, then the closing of the escape at the point marked F.E. The ignition can then occur

  a little before the top dead center at the AI point.

  We will now describe the illustrated embodiment variant

in Figure 2.

  This variant differs from the embodiment described in

  FIG. 1 in that the fuel pump 19 receives directly

  the pressure fluctuations necessary for its func-

  motor housing by means of a conduit 40 which makes it possible to

  plicate the instantaneous pressure prevailing in the casing 6 to

the membrane 23 of the pump 19.

  In order to allow the injection of fuel into the chamber

  13, under the pressure that prevails at the time of the injection, which pressure will be greater than that prevailing at

  this moment in the case 6, because of the opening of the trans-

  5, there is further provided on the conduit 41 connecting the output of the pump 19 to the injector 17, a small

pressure accumulator 42.

  On the other hand, so as to allow, as in the embodiment of Figure 1, the clearance of the valve 28

  discovering the fuel supply port 27 towards the

  jector 17 at the moment when the light 16 is uncovered by the piston 4, the chamber 32 is subjected to the pressure prevailing in the auxiliary chamber 13, taken at a point 43, remote from the injector 17 and which can be positioned substantially as the point 22 of the outlet conduit 21 of the example shown in Figure 1. Note that in the example of Figure 2, there is no communication between the chamber 32 and the volume

  44 of the pump 19, located above the membrane 23 with respect to

  port to the spring 24, which of the remainder can be omitted in this embodiment.

  Obviously, the operation of the device illustrated in

  FIG. 2 is identical to that of the device illustrated in FIG.

gure 1.

  The embodiment variant illustrated in FIG. 3, which is very similar to that illustrated in FIG.

figure 1.

  It differs in that the chamber 44 of the pump 19, above the membrane 23, is in communication with the volume of the auxiliary chamber 13 by a conduit 45 which is different from the calibrated conduit 46 joining said chamber 13

  to the capacity 32 ensuring the regulation of the injection of car-

  when the injection light 16 of the rich carburized mixture is discovered. This arrangement allows adjustment

  simpler regulation, in particular by playing a role in

  Of course, in this example, it is the outlet 47 of the conduit 46 in the auxiliary chamber 13, which

  plays the role of the outlet 22 of the pipe 21 (FIG.

  capped 43 (FIG. 2) allowing the injection of rich fuel air

  at the moment of opening of the light 16, thanks to the birth

  a pressure differential between this point and the one where the injector 17 opens, in the Venturi 18 of the chamber

13, at the time of injection.

  The fuel flow adjustment can also be modulated

  1, as shown in FIG. 3, by providing a bypass 48 on the pipe 46, forming an air leak controlled by a

  needle 49 whose engagement is related to the position of the butterfly

  11, for example by a linkage, the conduit 48 can open upstream and downstream of the butterfly 11 on the

  main line 10 of air intake.

  Alternatively, and as illustrated in FIG. 4, the needle 49

can be omitted.

  It should be noted that, in accordance with the invention, it is very

  to regulate and modulate the flow and the richness of the

  rich carburized fuel injected into the combustion chamber

  shot from the auxiliary chamber. Indeed, the modulation can be done not only at the level of the calibration of the injectors and

  pressure lines, but especially at the level of the

  and / or the orientation of the different pressure

  in the auxiliary chamber 13, as indicated in 17 and 22 in Figure 1, 17 and 43 in Figure 2, 17 and 47 in Figure 3. According to the location and direction of these takes, can modulate the carburation and manage to optimize

2501288 1

  the operating efficiency of an engine.

  Of course, the invention is in no way limited to the embodiments illustrated and described which have been given only by way of examples, the invention comprising on the contrary all the

  technical equivalents of the means described and their

  combinations if they are carried out according to his spirit and

  implemented in the context of the following claims.

REV'ENDICATIONS

  1. Two-stroke engine of the type comprising for its food

  In a carburetted mixture an injector supplied with fuel by a gasoline pump of the membrane type, actuated (directly or indirectly) by the pressure variations occurring in the engine during operation of the engine, said engine being characterized in that that said injector 17 opens

  in an auxiliary chamber 13 for storing the pre-compres-

  sion in the housing 6 and connected to it by a

  non-return fart 15 or any equivalent means, and said injection

  is located and / or directed in the said auxiliary chamber of

  o10 how it creates at its outlet a differential of pres-

  fuel injection when means, such as light 16 or equivalent means, discover

  an outlet of said auxiliary chamber 13 in the direction of

  combustion chamber 2 of the engine.

  2. Motor according to claim 1, characterized in that

  the auxiliary chamber 13 opens into the combustion chamber

  2 of the engine by a transfer port 16 located lower (relative to the top dead center of the engine) than the outlets

  7 and sweeping and air-filling transfers 5 of the-

said combustion chamber.

  3. Motor according to claim 1 or claim 2,

  characterized in that said injector 17 is located

  at the level of a narrowed intermediate section 18 forming

  Venturi of the auxiliary chamber 13.

  4. Motor according to one of the preceding claims,

  characterized in that the injector 17 is connected to a chamber

  29, comprising a membrane 31 actuating a body

  shutter 28 (such as a valve) of the feed duct

  fuel supply 27, powered by said fuel pump

  19, and said membrane 31 is permanently transmitted to two pres-

  antagonistic measures taken in the said auxiliary chamber 13 in

  distant points (17,22; 17,43; 17,47) subject to

  different dynamic situations, especially at the time of

  said outlet port 16 of said auxiliary chamber

to said combustion chamber.

  5. Motor according to claims 3 and 4, characterized in

  that the two aforementioned antagonistic pressures are respectively taken at said narrowed section 18 and at a

other level.

  6. Engine according to one of the preceding claims,

  characterized in that the fuel pump 19 is actuated by the pressure variations occurring in said auxiliary chamber 13 as a result of the pressure variations occurring.

in the crankcase of the engine.

  7. Motor according to one of claims 1 to 5, characterized

  in that the fuel pump 19 is actuated by the varia-

  pressures appearing in the housing 6, and it is pre-

  seen a pressure accumulator 42 on the feed circuit

  fuel injection of the injector 17 after said pump.

  8. Motor according to one of claims 4 to 7, characterized

  in that one creates at the level of at least one of

  counteracting pressure 47 acting in the control chamber

  29,32 a controlled leak 48.

  9. Motor according to claim 8, characterized in that

* The size of the leak is controlled according to the posi-

  the throttle valve 11, for example by means of a trilo-

  glerie operating a needle needle 49.

  10. Motor according to claim 8, characterized in that

  the size of the leak is controlled according to the pressure

  prevailing in the escape channel 48, connected to the pipe 10

engine air intake.