FR2482201A1 - IMPROVEMENTS ON CARBURETORS COMPRISING A MAIN CIRCUIT AND AN AUXILIARY CIRCUIT - Google Patents

Abstract

AN INTERNAL COMBUSTION ENGINE CARBURETOR INCLUDES AN EMULSIONED FUEL MAIN CIRCUIT FOR NORMAL OPERATION, OPENING INTO A VENTURE IN THE INTAKE DUCT, AND AT LEAST ONE AUXILIARY IDLE CIRCUIT, EQUIPPED WITH JETS. THESE NOZZLES 30, 32 ARE CARRIED BY A DISTRIBUTION BLOCK 20 PROVIDED TO BE INSERTED AND FIXED REMOVABLE IN THE PART OF THE INTAKE DUCT 1 LOCATED NEAR VENTURI 6.

Description

Carburetor upgrades with a.

  main circuit and an auxiliary circuit.

  The invention relates to carburetors for internal combustion engines of the type which include a main fuel spouting circuit for normal operation, opening into a venturiand at least one auxiliary circuit intended to supply the engine with a flow of air / fuel mixture. allowing operation at low speed and low load, said circuits being provided with metering devices. The auxiliary circuit opens into the intake duct, on the one hand through an idle orifice disposed downstream of a throttle member, on the other hand through at least one progression orifice situated so as to pass from upstream downstream of the throttle member when it is ajar from its minimum open position. In conventional carburetors, the devices

  dosing devices consist of calibrated orifices which determine

  fuel and / or air flow rates and are provided in nozzles. In recent carburetors, these calibrated orifices are supplemented or replaced by solenoid valves excited by electrical pulses

  width modulated by an advantageous control circuit-

  fully looped, using a diving probe as a detector

  in the engine exhaust.

  The nozzles and / or solenoid valves are usually carried by the carburetor body and generally screwed into threaded passages of the body. The main fuel nozzle is generally placed in the constant level tank of the carburetor; an air jet (or automatic nozzle), supplying air for emulsion of the fuel delivered by the main spouting circuit, is placed in the air inlet of the carburetor. The idle jet is often screwed on the external part of the carburas body

tor, come from foundry.

  This dispersion of calibrated metering organs in

  different points on the carburetor have drawbacks.

  During assembly in the workshop of carburetors intended to supply different types of engines, the calibrated members corresponding to these different engines are placed on a carburetor body; to meet demand, it is necessary to maintain as many stocks of carburetors as

  types of motors, resulting in excessive spending.

  In addition, we often find, in conventional carburetors whose spouting circuit includes an emulsion well, pulses of flow when the circuit is primed, as well as sudden changes in the fuel flow at full load, changes due to the transmission of pulsatiorn

pressure along the well.

  The present invention aims to provide a simple and compact carburetor of reduced, adaptable coat

  to different types of motor in a simple way.

  - For this purpose, the invention notably proposes a carbura-

  tor of the kind defined above in which the metering devices are carried by a distribution block constituting a whole intended to be fixed removably in the duct

  admission to the vicinity of Venturi.

  Thanks to this arrangement, the primary mixture of air and fuel delivered by the main spouting circuit is developed very close to the place where it

leads into the Venturi.

  When said devices are fixed calibrated orifices provided in sprinklers, the latter

  can easily be placed in two support arms.

  The invention will be better understood on reading

  the following description of a carburetor which constitutes it

  a particular embodiment, given by way of example

  not limiting. The description refers to the single figure

  which shows, in vertical section, the carburetor.

  The carburetor, of the inverted type, comprises a body in which is formed an intake duct 1 connected to the

  engine intake manifold with air inlet 2.

  In the duct 1 is placed a throttling member 3 or throttle actuated by the conductor, mounted on an axis 4 of

24822O I

so you can rotate.

  The fuel supplying the engine comes from a constant level tank N through a channel 5. The emulsified fuel used for normal operation borrows a main spouting circuit opening into the intake duct 1 at the neck of a Venturi 6 , while the emulsified fuel necessary for operating at idle or at low engine load is supplied by an auxiliary idling circuit. This circuit comprises, in its downstream part, a channel 7 which opens into the intake duct 1 by: -at least one transfer orifice 8 located so as to pass from upstream to downstream of the butterfly valve when the latter is opened ci from its minimum open position, - and an idle orifice 9 located downstream of the butterfly 3 and whose passage section is adjustable by displacement of the terminal portion 10a of a screw 10, braked by a

spring 11.

  The carburetor according to the invention comprises a single distributor block 20 which supplies: the main fuel spouting system,

-and the idle channel 7.

  This distributor block 20 includes a foundation piece

  hollow line 21 rigidly fixed in the air inlet 2 of the carburetor. Lapièce 21 has a central cylindrical part and radial arms, two in number in the mode

  of illustrated embodiment, we take aqpui on the body of the carbura-

  tor by inclined faces. One of the arms 21a is used

  for supplying fuel from the constant level tank.

  The other 21b is used to supply the auxiliary circuit.

  The part 21 is held in place by a hollow screw 22 penetrating into the arm 21b, the threaded part of which cooperates with a thread 23 of the carburetor body and the end part of which rests on the part 21 via

  an O-ring seal 24.

  the hollow part 21 provides the connection between the tank

  at constant level N and the main and idle circuits.

  It has for this purpose a common trunk, constituted by the channel 5 and a conduit 5a formed in the arm 21a and in

  which is fitted a main nozzle 30.

  From this nozzle 30, the auxiliary circuit comprises, formed in the part 21, a circumferential duct 31 and an idle nozzle 32 which opens into the passage

  formed inside the hollow screw 22.

  From this same main nozzle, the main circuit comprises an annular passage delimited, in a central cavity 40 of the part 21, by a ventilation nozzle 41. the nozzle 41 is screwed inside the cavity 40 in a tapped part 42 of the part 21. The ventilation nozzle 41 is itself pierced with a central passage in which is fitted an automaticity nozzle pierced with a calibrated hole 44. The passage 43 connects the inlet air 2 from the carburetor to the central cavity 40 via one or more radial holes 45. Finally, the cavity 40 opens into the intake duct through openings 46 located at the level

- the main Venturi 6.

  the operation is as follows: When the engine is idling the throttle 3 is

  closed (as shown in the figure) and a significant depression

  Aunt is exerted on the orifice 9. The corresponding vacuum in the idle circuit is adjustable by means of the screw 10. Under these conditions, fuel and air are sucked by the idle circuit. The fuel comes from the constant level tank N through the channel 5, the conduit 5a and the nozzle 30. The air arrives from the air inlet 2 through the calibrated orifice 44 and the openings 46. The mixture of air and fuel which is thus formed in the upstream part of the duct 31 is delivered by the duct 31, the nozzle 32, the hollow screw 22 and the channel 7 to open into the duct 1 through the orifice 9. The quantity of idle mixture is adjusted by adjusting screw 10 to allow proper

engine operation.

  If the engine is partially loaded by opening the throttle valve 3, the orifices 8 pass downstream of the upper edge of the throttle valve and deliver the additional quantity of air / fuel mixture necessary for proper operation

of the motor.

  If the engine is loaded more by opening the

  throttle 3, the vacuum transmitted to the spouting circuit-

  main fuel becomes sufficient to ignite it; from this instant, the vacuum in the openings 46 draws fuel from the constant level tank, through the channel 5, the conduit 5a calibrated by the nozzle 30, the annular space 40 and the openings 46 simultaneously from the emulsion air arrives in the annular space through the calibrated hole 44, the central passage 43 and the holes 45. This air mixes with the fuel to form a primary mixture delivered at the neck of the main Venturi by

the openings 46.

  The invention is obviously susceptible of numerous variants and in particular the main nozzle 30 can be replaced or supplemented by a solenoid valve, the control circuit of which is, for example, of the type described in patent application FR 78 06715 and supplies pulses at a frequency which is advantageously greater than 10 Hz to avoid

appreciable flow pulsations.

  It can be seen that the invention allows, thanks to a compact block carrying all of the metering devices 9 such as calibrated orifices, defining the characteristics of the air and fuel flow rate of the carburetor, a simple structure of the carburetor. In addition, the overall amount of fuel and air / fuel mixture contained in the main spouting system downstream of the main fuel metering device (main nozzle 30 in the figure) is much lower than that contained in the fueling systems. usual spurts. This results in a

  reduction of pulsatLQns of the flow rate of the spring system-

  ment during priming and a reduction in the distortion of the pressure signal during operation at full load,

  throttle body 3 wide open.

Claims (6)

  1. Carburetor for internal combustion engine   including a main fuel spouting circuit   ble emulsified for normal operation, opening into a Venturi from the intake pipe of the carburetor and at least one auxiliary circuit intended to provide the engine with a flow of air / fuel mixture allowing operation at low   speed and low engine load, said circuits compress   dispensing devices, characterized in that the dosing devices are carried by a distribution block intended to be inserted and fixed in a removable manner in the   part of the intake duct located near the Venturi.   2. Carburetor according to claim 1, character-   laughed in that said block comprises a part (21) provided with arms (21a, 21b) bearing on the body of the carburetor, one of which is pierced with a fuel supply passage and carries a main device for metering and the other of which is pierced with a supply passage of the auxiliary circuit. and wears an idle jet (32).   3. Carburetor according to claim 2, characterized in that the main metering device is a nozzle (30). 4. Carburetor according to claim 2, characterized in that the main device is a solenoid valve controlled by rectangular signals of variable duty cycle.   5. Carburetor according to any one of the claims   cations 2 to 4, characterized in that said part has a central cavity in which is placed an air outlet (41) pierced with a central air intake passage   emulsion through a calibrated hole <44).   6. Carburetor according to claim 5, characterized in that the main device opens into a passage   annular delimited by the part (21) and the end piece (41).