FR2489888A1 - CARBURETOR FOR TWO-STAGE EXPLOSION ENGINES - Google Patents

Abstract

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

Description

The present invention relates to a carburettor of the Aype fuel pump

  2-cycle internal combustion engines, which makes it possible to simulate a wide variety of applications, of a very simple construction and

  remarkable economic benefits - and having

  especially limited overall

  The carburettor according to the invention, of a type allowing its operation in any inclination, is particularly suitable for two-stroke combustion engines used for tools and devices of dimensions, weight and limited space. It involves the minimum of complications and congestion, it can be easily adapted to a

  many different applications - through

  of simple and reduced modifications or

  and it's safe to operate in any

terms of use.

  In addition, in the carburetor according to the invention, it is extremely easy to ensure the

  replacement of parts most subject to wear.

  Essentially, the carburettor for two-stroke engines according to the invention, of the type consisting of several replaceable components which are associated with each other in the form of a unitary unit, is characterized in that it comprises four components, consisting of a main body containing the main duct dV carburetor (in which the mixture is formed), a lower body associated with the main body and containing the fuel chamber, and two lids, the first containing the fuel pump placed between the lid and the main body while the second contains the fuel pressure control devices in said chamber, said devices being disposed between the second lid and the body

  lower, what are the channels allowing the fuel

  to move from the chamber into the main duct of the carburettor are in the form of open grooves which are formed in the surface of the body:

  lower that is directed to the main body,.

  said grooves being covered by association of said bodies with the interposition of appropriate seals.

  Another important feature of the car-

  The burator according to the invention consists in that, in said carburettor, the. the full-rate fuel quantity adjustment screw and the idle fuel quantity adjustment screw are placed in the lower body and are arranged side by side and

same side of said body.

  According to another characteristic of the carburettor according to the invention, it is possible, by a simple inversion of the casting cores of the mixture forming duct during the casting of the main body, to connect the lower body with the main body so as to place the two setscrews on the opposite side of the carburettor, while keeping unchanged the other features of the carburetor elements

well said.

  Other advantages and features of the invention will be highlighted, in the following

  description, given by way of non-limiting example, in

  reference to the accompanying drawings, which show a preferred embodiment thereof and in which: Figure 1 is a view of the outside of the carburetor according to the invention, seen from the side of the motor connection flange; Figure 2 is a top plan view of the carburettor of Figure 1; 5. Figure 3 is a top view, in the direction of the arrow III of Figure 1, the lower body of the carburetor; Figure 4 is an enlarged sectional view taken along the line IV-IV of Figure 2; 10. Figure 5 is a longitudinal section of the main body of the carburettor of Figure 1, taken along the line V-V of Figure 1; Figure 6 is a partial sectional view of the idle mixing ducts on an enlarged scale; Figure 7 is a partial sectional view of the controls of the pressure admission, on an enlarged scale; the enlarged figure of the channels 20. the enlarged figure of the channels the carburettor-conforming figure with respect to that side of the flange of the reverse carburettor figure; FIG. 8 is a scale sectional view of the pump inlet; 9 is a sectional view with pump discharge scale; Fig. 1 is a view from the outside of an embodiment of the invention, of an inverted type shown in Fig. 1, seen from the connection of the inverted carburettor. It is a plan view from above of Fig. 10; 12 is a top view of the lower body of the inverted carburettor, in the direction of arrow XII of FIG. 10, FIG. 13 is a sectional view on an enlarged scale, taken along line XIII-XIII of FIG. 11 of the carburettor. reversed; and

  FIG. 14 is a longitudinal sectional view

  nale, made along the line XIV-XIV of Figure 10, the main body of the carburettor inverted figures

at 13.

  As indicated in the drawings and as explained above, the two-cycle diaphragm pump carburetor according to the present invention is formed of four elements which are associated in the form of a unitary assembly, these elements comprising a main body 1, a lower body 2, a cover

  3 for the pump and a cover 4 for the battery chamber.

  fuellines. The carburettor diaphragm pump (FIGS. 4, 7, 8, 9) is formed between the main body 1 and the lid 3 and is fed by a channel 5 (FIGS. 1, 7) connecting with the pressure inlet

  pulsation, arranged inside the motor (not shown

  felt) in the crankcase located below the piston. This pump comprises (FIG. 4) a first chamber 7 formed in the main body 1 and into which opens the end 6 of the channel 5 (FIG. 7), a diaphragm 8 made of elastic material (preferably a rubber material) mounted between the body main 1 and the lid 3, and a second chamber 9 formed inside the lid 3. This pump also comprises an intake valve 10 (Figure 8), which can establish and cut the communication between the first hand supply ducts 11, 12 and the tubular connection 13 connected to the fuel tank, and secondly the chamber 9 of the pump, as well as a discharge valve

  14 (FIG. 9), arranged to establish and cut off the

  nication between on the one hand the chamber 9 and the channels 15 and 16 connected thereto and on the other hand a small chamber 17 which communicates, via a filter 19, with the conduit 18 opening into the chamber

  fuel 24 (described in the following) of the carburetor.

  The valves 10 and 14 are of the automatic type - in the form of a tongue placed on the diaphragm 8 - as is well known in the art.

  to which the present invention is applicable.

  The fuel chamber 24 is formed (Figure 4) inside the lower body 2 of the carburetor, which also contains the needle valve 20 controlling the fuel supply. A spring 21 normally holds the needle valve 20 in the closed condition by acting on a curved intermediate portion 221 of a rocker lever 22 rotatably mounted

  on an articulated connecting element 22 ", one of the

  said other end is urged by a diaphragm device placed under the control of the depression produced, during rotation of the motor, in the main pipe 23 (FIGS. 4 and 4); 5) o the mixture is formed, said conduit being disposed in the body

main 1 of the carburetor.

  The diaphragm device, formed between the lower body 2 and the cover 4 of the fuel chamber, comprises (see in particular FIG. 4) an upper chamber 24 in which the

  needle valve 20, the spring 21 and the lever

  scorer 22. The upper chamber 24 communicates with the main conduit 23 of the body 1 through a full-speed nozzle 25, a capillary element 26

  housed in a seat 27 (Figure 4) of the groove 28

  (Figures 3 and 4) in the upper surface of the lower body 2, the hole 29, the small hole 30 of the full-speed mixing adjustment screw 31, and the hole 32 (Figures 3 and 4). The communication is also established via the progression holes 33 and 34, as well as the idle mixing hole 35 (FIG. 5), through the grooves 36 and 37 formed in the upper surface of the lower body 2 (FIG. Figure 3), and through the hole 38, the small hole 39 controlled by the idle mixture adjusting screw 40, and the hole 41 (Figures 3 and 6). The diaphragm device further comprises (FIG. 4) the diaphragm 42, mounted between the cover 4 and the lower body 2, and

  that a lower chamber 43, subjected to atmospheric pressure,

  because of the existence of hole 34 in the

cover 4.

  It should be noted that, in accordance with one of the essential features of the present invention, the channels for transferring fuel from the

  chamber in the main duct of the carburettor

  all feel in the form of open grooves (28, 36, 37) which are formed in the upper surface of the lower body 2, said grooves being covered by application of said lower body 2 to the body

  principal 1, with the interposition of an

  appropriate degree, as indicated in g in Figure 4.

  This solution involves a very simple and very economical machining, while at the same time being very precise and thus obtaining considerable advantages compared to conventional solutions for solving

the same problem.

  In FIG. 5, there is designated by 45 a small chamber for mixing, obtained in the lower part of the main body 1 of the carburettor. This chamber 45 is fed by the groove 36 (FIG. 3) of the lower body 2 and is in communication with the progression holes 33 and 34 as well as with the idle mixing hole 35. FIG. 5 also shows the main throttle 46 which serves for the power control as well as the front throttle valve 47 which serves to enrich the mixture in the cold start condition, and further the flange 48 for attachment to the engine and the flange

  49 air intake into the carburetor.

  In addition, 51 and 52 in FIG. 1 denote the two carburetor attachment holes according to the invention on the engine. These holes can be suitably arranged in different positions (as indicated for example at 51 ', 52') each time

  this is necessary for mounting reasons.

  When the carburetor described above is mounted on a two-stroke engine and when

  start this engine, the chamber 7 of the fuel pump

  The engine is subjected to the pulsating pressure transmitted to it via the channel 5, 6, from the crankcase of the engine located below the piston (said oscillating pressure, in a known manner, between a minimum corresponding to the top dead center position of the piston and a maximum corresponding to the bottom dead center position of this piston). As a result, the diaphragm 8 is driven forwards and backwards and produces respectively an increase

  and a reduction in the volume of the chamber 9 of the pump.

  In the first case, the depression generated in said chamber is transmitted, via the inlet valve 10 and the channels 11, 12, to the pipe 13

  connected to the fuel tank and it causes the aspi-

  fuel ration. In the second case, the compression generated in the chamber discharges the fuel, through the channels 15 and 16 and the discharge valve 14, to the small chamber 17 and to the channel 18 so that it reaches the chamber. intermediate of the filter 19, to the needle valve 20 which controls

  the fuel inlet in the chamber 24 of the carburetor.

  In said chamber 24, as seen, the spring 21 normally holds the needle valve in the closed condition. However, when the engine is started, the air sucked into the main duct 23 creates a vacuum which is transmitted to the chamber 24 via the communication means provided.

  in the bodies 1 and 2 and described above. As a result

  Accordingly, the diaphragm 42, subjected to the depression prevailing in the chamber 24 and at the atmospheric pressure prevailing in the chamber 43, begins to exert a thrust on the rocker lever 22, causing its rotation around the articulated connecting element 22 The rocker lever 22 then lifts the valve 20 from its seat and allows the fuel to enter the chamber 24 until the pressure in this chamber reaches a value in equilibrium with the force of the spring 21. In this way , a constant pressure is maintained in the fuel chamber 24, which allows a regular supply of fuel to the main intake duct 23 and therefore to the engine, through the jet of full speed 25, or by the intermediate of the progression holes 33 and 34 and the injection hole of

idling mixture 35.

  Channels supplying fuel,

  at full speed, from room 24 were represented

  4 and they consist of the hole 32, the small hole-30 set by the needle of the screw 31, the hole 29, the groove 28 (visible in FIG. 3), the capillary element 26 formed in the seat 27 and the

jet of full speed 25.

  The channels supplying the fuel supply under idling conditions have been indicated in FIG. 6 and consist of the hole 41, the small hole 39 set by the needle screw 40, the hole 38 and

  grooves 37 and 38 (visible in Figure 3).

  At the exit of the groove 36, the fuel reaches the small chamber 45, which can ensure

  feeding the holes 33, 34 and 35 (Figure 5).

  As shown in the above figures (in particular FIG. 3), the two full-speed adjustment screws 31 and the idle adjustment screws 40 are all

  two placed on one side of the carburetor.

  However, the particular conditions under which this carburetor is to be used - as stated above, the carburetor was designed to be mounted on medium-sized appliances, powered by small combustion engines - may require, mainly for reasons of 'clutter or positioning, an arrangement of the mixture adjustment screws full speed and idling mixture on

the other side of the carburetor.

  For this purpose, the possibility of reversing the carburettor by a simple change in the position of the main duct, which is oriented in the opposite direction to that previously described, has therefore been provided, so that this consequently results in an orientation towards the motor of the flange of

  connection 49 '(FIG. 14) which, in the pre-solution

  cente, was turned to the outside air intake (Figure 5). This result is obtained, from the point of view of the construction, in a very simple and very convenient way by inverting the position of the casting cores of the duct at the time of the casting of the main body 1

  (usually by die casting).

  For this other structure, other changes

  light cations must obviously be made to the main body (1 'in Figure 10), to the arrangement

  idle mixture hole and -progress holes

  35 'and 33' and 34 'respectively in Figure 14) and the arrangement of the engine pressure inlet (5' Figure) D) on the connecting flange (49 ') of the carburetor. The main body

  still has a double groove 50, 45 in order to

  put the position of the idle mixture hole and the progression holes as well in the direction of

  the flange 48 in the direction of the flange 49 '.

  With regard to the lower body (2 ', FIG. 12), it is sufficient to reverse the full-speed mixing groove 28' and the mixing grooves

of idling 36 'and 37'.

  It should be noted that the idling mixture groove 36 provided on the lower body 2 (or 36 'on the upper body 2') is positioned so as to allow the positioning of the idle mixture hole and

  progression holes both right and left.

  This therefore makes it possible to use the same casting process of the two bodies of the carburettor to obtain two solutions which differ as regards the position and consequently the access of the two adjustment screws.

  It should also be noted that the inferior body

  2 (or 2 ') contains all the wear parts of the carburettor (in particular the fuel inlet valve 20 in the fuel chamber as well as its seat, the adjusting screws 31 and 40 and their calibration holes respective, the diaphragm 42); this makes it possible to restore a carburettor, which has been used for a long time, under conditions that are practically identical to those of a

  new carburetor by simply replacing it

  the whole of his lower body.

Claims (2)

2-cycle internal combustion engine carburettor, of the type formed of several replaceable components which are associated with each other in the form of a unitary assembly, characterized in that it comprises four components consisting of a main body (1) containing the duct in which the mixture is formed, in a lower body (2) associated with the main body and containing the fuel chamber (24) and in two lids (3,4), the first of which ( 3) contains the fuel pump (7,8,9) placed between this cover and the main body while the second (4) contains the control devices (20,21,22) of the fuel pressure in said chamber, said devices being placed between the second cover (4) and the lower body (2), and in that the channels for transferring fuel from the chamber to the main conduit (23) where the mixture is formed are in the form of open grooves (28,36,   37) which are formed in the surface of the inferior body   which is turned towards the main body, said grooves being covered by assembly of said bodies   with the interposition of appropriate seals requested.   Carburettor according to claim 1, characterized   in that the adjusting screw (31) of the fuel quantity supplied at full speed and the adjusting screw   (40) the quantity of fuel supplied in the con-   idle conditions are placed in the lower body   and arranged side by side on the same side of said body.   30) Carburettor according to claim 2, characterized   in that the positioning of the conduit (23), in which the mixture is formed, in the main body (1) of the carburettor is reversed so as to allow the association of the lower body (2) with the body   (1) so as to place the two setscrews   the opposite side of the carburettor, while keeping the other characteristics unchanged   components forming said carburettor.   Carburettor according to claim 3, characterized   in that said inversion is obtained by inverting   the position of the casting cores of the duct at   moment of casting of the main body (1).