Fuel Feed Devices For Internal-combustion Engines

Abstract

The overall duration of opening of an injection valve in the fuel feed is regulated by an auxiliary throttle member opening automatically arranged upstream of a main throttle member. The pressure of the fuel passing through the injection valve is regulated by a system sensitive to the suction existing in the space between the two throttle members. Correction means act by feeding air into the system so as to reduce the suction and can include a diaphragm-controlled return valve and/or a capsule-driven piston obturating a calibrated orifice to the atmosphere.

Description

The invention relates to fuel feed devices for internal-combustion engines, of the type comprising in the induction pipe, upstream of a man throttling member operated by the driver, an auxiliary throttling member which opens automatically and progressively as the rate of airflow in the said pipe increases; means for injecting liquid fuel under pressure into that portion of the induction pipe downstream of the main throttling member; and a metering system adapted to respond to the position of the auxiliary throttling member and so to regulate the rate of flow of the fuel injected that the richness of the fuel-air mixture entering the induction pipe is substantially constant, at least for certain running conditions of the engine, the said injection means being in the form of a source of fuel under pressure of which the delivery circuit, leading into the said portion of the induction pipe, is controlled by at least one valve operated by an electromagnet.

The invention relates more particularly to those devices of this type in which the metering system comprises a member adapted to be rotated continuously, preferably by the internal-combustion engine, and capable, by affecting energization of the electromagnet, of causing opening of the valve during only a fraction of each of its revolutions, this system being so arranged that it increases this fraction the further the auxiliary throttling member opens, and vice versa.

The invention relates more particularly, but not exclusively, to devices of this type in which the member adapted to be continuously rotated has means for transmitting to a stationary receiver a flow of energy during a fraction of a revolution whose value varies according to the relative positions of the rotary member and receiver, the receiver being such that it controls the energizing circuit for the electromagnet according to whether or not it receives the flow of energy, and the auxiliary throttling member being such as to modify the relative positions of the rotary member and receiver; the means for emitting the flow of energy may be a light source, and the receiver may be a photoelectric cell, the source and cell being situated on each side of the said rotary member, which forms an opaque screen containing at least one port to permit illumination of the cell.

The rotary member is advantageously in the form of a flat, opaque disc perpendicular to its axis of rotation, the stationary receiver being such that it can be brought closer to or further from this axis.

Feed devices (of whatever type) for engines preferably, of course, have correction means for adapting the richness of the mixture supplied by them to certain operating parameters, such as the characteristics (pressure and/or temperature) of the ambient air and the loads applied to the engines.

The object of the invention is to combine correction means which are simple and economical in construction with feed devices of the type described.

According to the invention, the feed device of the type described, in which the fuel source is so arranged that its delivery pressure is regulated by a system adapted to respond to the suction prevailing in the induction pipe between the two main and auxiliary throttling members, is characterized in that the feed device is associated with correction means acting by introducing air into the said system in order to reduce the suction, with the result that these means can also vary the delivery pressure of the said source and consequently, for a given position of the auxiliary throttling member, the rate at which fuel is admitted to the induction pipe by the said valve.

The invention will in any case be clear from the following description and the accompanying drawings, relating to preferred embodiments given purely by way of illustrative examples.

FIG. 1 of the drawings shows, by means of a diagrammatic elevation with parts in section, a feed device embodying the invention; and

FIG. 2 shows a section along a line II-II in FIG. 1, on a larger scale.

A fuel feed device for a vehicle engine or the like is constructed as follows or in a similar fashion.

As regards the device as a whole, it is constituted in any appropriate manner, in such a way that it comprises (FIG. 1): In the induction pipe 1, upstream of a main throttling member 2 operated by the driver, an auxiliary throttling member 3 which opens automatically and progressively as the rate of airflow in the said pipe 1 increases; means for injecting liquid fuel under pressure into that portion of the induction pipe 1 downstream of the main throttling member 2; and a metering system adapted to respond to the position of the auxiliary throttling member 3 and so to regulate the rate of flow of the fuel injected that the richness of the fuel-air mixture entering the induction pipe 1 is substantially constant, at least for certain running conditions of the engine.

According to the embodiment illustrated, the auxiliary throttling member 3 is in the form of a butterfly valve keyed on a pivot 4. This butterfly valve is operated by a pneumatic device with a diaphragm 5 which separates two chambers 6,7 from one another. The chamber 6 is connected by a duct 8 to a chamber 9 formed by that portion of the pipe 1 between the main throttling member 2 and the butterfly valve 3. The pivot 4 is attached to a lever 10 whose free end bears a detent 11 cooperating with the end of a rod 12 connected to the diaphragm 5. A spring 13 tends to close the butterfly valve 3, counteracting the influence of the suction transmitted in the chamber 6. The chamber 7 is connected to the atmosphere by a duct 14, preferably running from the air intake 15 of the pipe 1.

The angular position of the butterfly valve 3 within the pipe 1 at any time corresponds, of course, to the rate of airflow in this pipe. The higher this rate of flow, the more the butterfly valve 3 opens, a substantially constant suction (or a suction varying according to the characteristics of the spring 13) establishing itself in the chamber 9 between the two throttling members 2,3. Equivalent throttling members might be substituted for the butterfly valve 3, for example members adapted to move in translation.

The injection means mentioned are in the form of a source of fuel under pressure (see below) of which the delivery duct 40, which joins the pipe 1 downstream of the main throttling member 2, is controlled by at least one valve 16 operated by an electromagnet 17.

The metering system comprises a flat, opaque disc 18 which is mounted on a shaft 19 connected to a motor, for example the internal-combustion engine (not shown) supplied by the device, in such a way that the disc is rotated continuously about an axis perpendicular to its plane. The disc 18 is placed between a light source 20 and a photoelectric cell 21 mounted on a common support 22 connected to the auxiliary throttling member 3, and it contains at least one port 23 adapted to admit the beam from the light source 20 to the photoelectric cell 21. The cell 21 is adapted to cause energization of the electromagnet 17, depending on whether or not it is illuminated, the assembly as a whole being such that the electromagnet is energized during a fraction of each revolution of the disc 18 which varies in the same sense as the degree of opening of the auxiliary throttling member 3.

The light source 20 may be in the form of a lamp which can be supplied by a battery 24 once the engine ignition switch 25 is on, and which is housed in a hollow boss 26 containing a hole. This hole is so arranged that it directs a light beam onto the cell 21, through a hole in a hollow boss 27 housing this cell.

In the embodiment illustrated, the bosses 26,27 are mounted on the ends of the U-shaped support 22, which is placed astride the disc 18 so that the source 20 and cell 21 are on opposite sides of this disc, and which is attached to the pivot 4, the latter being parallel to the shaft 19 and to the light beam received by the cell 21.

In order to make use of the currents produced in the cell 21, an amplifying relay 28 and possibly an intensity limiting device 29 may be inserted between this cell and the electromagnet 17.

When the internal-combustion engine has a plurality of cylinders, each supplied by a valve 16 operated by a separate electromagnet 17, a distributor 30 is provided, this distributor being synchronized with the disc 18 in order to supply the intermittent energizing current to the different electromagnets in succession, along leads such as 31, the disc having as many ports 23 as there are cylinders to be supplied. These ports are equispaced around the shaft 19, and each is shaped in such a way that the fraction of a revolution during which it normally permits illumination of the cell 21 increases as the throttling member 3 opens, that is to say (according to the embodiment illustrated), as the bosses 26,27 come nearer to the shaft 19.

The feed device just recalled operates, of course, as follows:

As the rate of airflow in the pipe 1 increases, the throttling member 3 opens, moving the support 22 in the direction which brings the bosses 26,27 nearer the shaft 19. Each of the positions of these bosses corresponds to a different radius of the disc 18. Since the shape of each port 23 has been selected so that the fraction of a revolution during which it admits the light ray from the source 20 to the cell 21 (a current being produced in the lead 31) increases, the nearer the latter elements come to the shaft 19, the rate at which fuel is supplied by each injection valve 16 will necessarily vary in the same sense as the rate of airflow in the pipe 1.

Under these conditions, the fuel source is arranged so that its delivery pressure is regulated by a system adapted to respond to the suction prevailing in the chamber 9, and the feed device is associated with correction means acting by introducing air into the said system in order to reduce the suction, with the result that these means can vary the pressure of the said source and consequently, for a given position of the auxiliary throttling member, the rate at which fuel is admitted to the induction pipe 1 by the valve 16.

The fuel source has a reservoir (not shown) connected by a duct 32 to a pump 33, operated either by the internal-combustion engine or by an electric motor; a float chamber 34 to which the delivery duct 35 from the pump 33 leads, the flow of fuel through the duct 35 being regulated by a needle 36 operated by a float 37; an injection pump 38 with a relatively high delivery pressure, operated either by the internal-combustion engine or, preferably, by an electric motor (not shown) controlled by the ignition switch 25, the suction duct 39 for this pump being connected to the bottom of the chamber 34 and the delivery duct 40 of the pump to the valve 16; and a return duct 41, which is connected to the delivery duct 40 of the pump 38 and whose connection to the reservoir, or rather the chamber 34, is regulated by the said system adapted to respond to the suction prevailing in the chamber 9.

As regards this latter system, it comprises a valve 42 cooperating with a seat 43 formed by the bottom of a chamber 44, which is immersed in the fuel in the float chamber 34 and to which the return duct 41 leads; and a movable or deformable element such as a diaphragm 45 connected to the valve 42, for example by a rod 46, this element forming one wall of a chamber 47 connected by a duct 48 to the chamber 9 either directly or, as shown in FIG. 1, by way of the duct 8. The duct 48 contains a calibrated orifice 49. That side of the diaphragm 45 remote from the suction chamber 47 is connected to the atmosphere. If, as shown in FIG. 1, this side of the diaphragm 45 defines a second chamber 50, the latter may be connected by an orifice 51 to the top of the float chamber 34, which is itself ventilated by an orifice 52, preferably connected to the air intake 15 downstream of an air filter. The assembly as a whole is such that the suction derived from the chamber 9, by acting on the diaphragm 45, tends to close the valve 42 when the pressure of the fuel which is delivered to the chamber 44, and which acts directly on this valve, tends to open it.

In accordance with the invention, the correction means are arranged so that they act by introducing air into the chamber 47 in order to reduce the suction inside it, this suction being transmitted to it by the duct 48.

In a first embodiment, the correction means comprise an enclosed actuator adapted to respond to the suction prevailing in the induction tube 53 of the induction piping, which continues the pipe 1 downstream of the main throttling member 2. As FIG. 1 shows, this enclosed actuator may be in the form of a movable or deformable member such as a diaphragm 54, biased by a spring 55 and closing a chamber 56 connected by a duct 57 to the tube 53. The central portion of the diaphragm 54 forms an obturator for a calibrated orifice 58, through which the suction chamber 47 can communicate with the atmosphere. The assembly as a whole is such that the suction prevailing in the chamber 56 of the actuator tends to open the orifice 58, counteracting the spring 55.

Preferably, the orifice 58 communicates, by way of a chamber 59 defined by the diaphragm 54 on the opposite side from the suction chamber 56, with the air intake 15 by way of a duct 60. As shown by solid lines in FIG. 1, this duct may run from a site 61 permanently upstream of the auxiliary throttling member 3. Often, however, as shown by chain lines, it may be better to run it from a site 61a, so that it moves from upstream to downstream of the auxiliary throttling member 3 when the latter passes from its minimally open position (shown by broken lines) to a partially open position (beyond that shown by chain lines).

In a second embodiment, which may be used either separately or in combination with the preceding embodiment, the correction means comprise a capsule 62 adapted to respond to the characteristics of any fluid capable of influencing operation of the device and entailing a correction of the richness of the mixture, this capsule 62 operating a needle 63 (or equivalent obturating means) adapted to establish or prevent communication between an orifice 64, similar to the orifice 58, and a ventilating orifice 65, possibly connected to a duct (not shown) similar to the duct 60. The fluid mentioned above may be the ambient air, of which the temperature and/or pressure may be determined by the capsule 62.

The resulting device operates as follows.

The pump 38 is preferably driven by an electric motor connected by the switch 25 to the engine ignition circuit so that, as soon as the engine starts, the pressure required to supply the or each injection valve 16 is produced in the duct 40. When the engine turns, a certain suction appears in the chamber 9 between the throttling members 2 and 3 and therefore in the duct 48, and this suction acts on the diaphragm 45 and closes the valve 42, by drawing it onto its seat 43. This suction regulates the pressure prevailing in the duct 40.

Subsequently, under all engine running conditions, the delivery pressure of the fuel in the duct 40 is regulated by the leakage through the valve 42, which always depends on the suction prevailing between the throttling members 2 and 3. In general, therefore, the suction in the chamber 47 is the same as that in the chamber 6 or 9.

In certain cases, however, it may be necessary to reduce this suction, If the shapes of the ports 23 have been designed for the full load curve, the shapes of these ports may be unsuitable for the "partial load" curves and may lead to excessive richness of the mixture. The fuel pressure under partial load must then be reduced at the or each valve 16 in order to correct the mixture.

Running under a reduced load increases the suction in the tube 53, and therefore in the duct 57 and chamber 56. The diaphragm 54 is therefore moved, counteracting the spring 55, and the orifice 58 is uncovered so that air drawn in along the duct 60 can enter the chamber 47. The existence of the calibrated orifice 49 makes it possible to produce in this chamber 47 a suction slightly less than that in the chambers 6 and 9.

The pressure of the fuel in the duct 40 is therefore reduced to extents depending on the respective sizes of the calibrated orifices 49 and 58, so that, whenever the engine is running under a reduced load, a lower fuel pressure, and therefore a lower rate of fuel flow, can be produced for the same rate of airflow as under full load conditions.

Similarly, if the atmospheric pressure drops or the air temperature is too high, the fuel pressure must be modified in order to prevent the mixture from becoming too rich. To this end, the capsule 62, which may be a barometric capsule if compensation of the barometric pressure is required, expands if the atmospheric pressure drops, moving the needle 63 beyond the orifice 64 so that air can enter the chamber 47, producing the same effect as the intake of air through the orifice 58. The fuel pressure therefore drops, and with it the total delivery from the injection valves 16. If the mixture is to be corrected on account of the temperature, it is merely necessary for the capsule 62 to be temperature responsive.

As already explained above, the two devices may be used simultaneously, as shown in FIG. 1.

Also, if, in the case of the arrangement having the enclosed actuator with the diaphragm 54, the air is drawn in through the orifice 61a as shown by chain lines, the fuel pressure can be corrected for certain rates of airflow, for example for low rates of airflow and under a reduced load. As long as the throttling member 3 is between the closed position shown by broken lines and the position shown by chain lines, the air is, of course, drawn in upstream of the throttling member 3, so that, if the diaphragm 54 uncovers the orifice 58, the air introduced through the duct 60 helps to reduce the fuel pressure in the duct 40. As soon as the throttling member 3 moves past the position shown by chain lines on the other hand, the duct 60 is opened downstream of the throttling member 3, and it is subjected to substantially the same suction as the duct 8. As a result the air arriving through the duct 60 and orifice 58 is at the same pressure as the air arriving through the duct 48, and the actuator with the diaphragm 54 becomes inoperative. This actuator, therefore, can be used not only to compensate for reduced loads as compared with full loads, but also to correct the mixture within a certain range of airflow rates, as compared with other ranges of airflow rates.

Lastly, when the engine stops, the pump 38 is stopped and the suction in the duct 48, and therefore in the chamber 47, disappears, so that the valve 42 opens and the pressure in the duct 40 returns to zero. This prevents any leakage from the injection valves 16 while the engine is off.

The present device therefore offers innumerable correction possibilities, which can be very simply realized, to adapt the metering device to all types of engines and any physical characteristics of the air fed to the engine.

Claims

I claim:

1. In a fuel feed device for internal-combustion engines, which comprise in the induction pipe, upstream of a main throttling member operated by the driver, an auxiliary throttling member which opens automatically and progressively as the rate of airflow in the said pipe increases; means for injecting liquid fuel under pressure into that portion of the induction pipe downstream of the main throttling member; and a metering system adapted to respond to the position of the auxiliary throttling member and so to regulate the rate of flow of the fuel injected that the richness of the fuel-air mixture entering the induction pipe is substantially constant, at least for certain running conditions of the engine, the said injection means being in the form of a source of fuel under pressure of which the delivery circuit, leading into the said portion of the induction pipe, is controlled by at least one valve operated by an electromagnet, the metering system comprising a member adapted to be rotated continuously and capable, by affecting energization of the electromagnet of causing opening of the valve during only a fraction of each of its rotation, this system being so arranged that it increases this fraction the further the auxiliary throttling member opens, and decreases this fraction the further the auxiliary throttling member closes, the said fuel source being arranged so that its delivery pressure is regulated by a system adapted to respond to the suction prevailing in the space defined in the induction pipe by the two main and auxiliary throttling members, the improvement that the device comprises correction means acting by introducing air into the said system in order to reduce the suction, with the result that these correction means can also vary said delivery pressure and consequently, for a given position of the auxiliary throttling member, correct the rate at which fuel is admitted to the induction pipe by the said valve.

2. The improvement of claim 1, wherein the fuel source has an injection pump delivering in parallel to the or each injection valve and to a return pipe controlled by a return valve, said return valve being operated by a movable or deformable element which forms one wall of a chamber connected to the space defined in the induction pipe by the two throttling members.

3. The improvement of claim 1, wherein the correction means comprise an enclosed actuator adapted to respond to the suction prevailing in the induction pipe downstream of the main throttling member, said actuator controlling a calibrated orifice through which said correction means communicate with the atmosphere.

4. The improvement of claim 3, wherein the calibrated orifice is connected to a zone in the induction pipe, said zone being situated at the air intake of this pipe.

5. The improvement of claim 4, wherein the zone is so situated that it passes from upstream to downstream of the auxiliary throttling member when the latter passes from its minimally open position to a partially open position.

6. The improvement of claim 1, wherein the correction means comprise a capsule adapted to respond to the characteristics of any fluid capable of influencing operation of the device and by an obturator operated by said capsule and adapted to establish or prevent communication between the said correction means and the atmosphere.

7. The improvement of claim 6, wherein said communication is via the air intake of the induction pipe.

8. The improvement of claim 1, wherein the fuel source comprises an injection pump, and said pump is driven by an electric motor connected to the engine ignition circuit in such a way that the pump operates only when the ignition circuit of the internal-combustion engine is closed.

9. The improvement of claim 1, wherein said continuously rotated member is driven by the internal-combustion engine.