FR2492891A1 - Charge intake for IC-engine - has housing with air flow passage controlled by obturator and fuel passage with sprung valve - Google Patents

Abstract

The air intake for an i.c. engine has a housing (1) containing an air flow passage (2). An orifice feeds fuel (8) under light pressure to the passage intake to mix with the air. A valve (9) can close the fuel orifice via a spring. A feed control valve (19) has a gate (26) in the air passage and over the fuel inlet. A spring (24) forces the gate closed and is mounted in the base of the housing. A second valve (35) can control the volume of the housing depending on external conditions.

Description

 The present invention relates to a fuel supply device for a combustion engine of the internal combustion and spark ignition type and it relates, more particularly, to supply devices for explosion engines.

 The object of the invention is to provide a particularly simple, precise, space-saving and feedable supply device, having only a minimum number of moving parts and making it possible to ensure a proportional metering of the combustible fluid with respect to the flow rate. oxidizing fluid.

 The object of the invention is, moreover, to propose a supply device whose constituent elements, responsible for the formation of the fuel mixture, do not have a hinge connection between them, so as to avoid disturbances or fluctuations in operation resulting from assembly or wear clearances.

According to the invention, the supply device for an internal combustion engine is characterized in that it comprises
- a body delimiting a circulation vein
air,
- a combustible fluid inlet orifice under
slight downward pressure relative to
in the sense of air circulation,
- a valve requested to close the orifice
arrival by a spring,
- and a pro dosing and adjustment device
portion including
. a obturator placed in the vein in
upstream of the inlet,
an elastic member pushing the shutter
in the closed position and acting in the
opening direction on the valve.

 Various other characteristics will emerge from the description below made with reference to the appended drawings which show, by way of examples, embodiments of the subject of the invention.

 Fig. 1 is a sectional elevation of the supply device according to the invention.

 Fig. 2 is a schematic elevation showing an example of application of the subject of the invention.

 Fig. 3 is a partial elevation view showing a development of the device.

 According to fig. 1, the supply device comprises a body 1, of the tubular type, delimiting a vein 2 of air circulation caused to circulate in the direction of the arrow 1. Depending on the type of application, the air circulation in the direction of the arrow f1 can result either from a pressurization of said fluid upstream of the device, or from a vacuum setting downstream of this device.

 Preferably, the body I is constituted by two half-bodies 1a and 1b which are assembled between them by any suitable means so as to establish a total seal between the surrounding medium and the vein 2 which they delimit together. This arrangement is chosen so as to facilitate the production of the half-bodies 1a and 1b as well as the mounting, the installation and / or the adjustment of the internal organs of the device.

 The body lb is provided with a throttling means 3, generally called a butterfly, operated at will by the user and making it possible to control the passage section offered by said body lb and which can range from a maximum opening available to a closing total. In particular, such a butterfly valve 3 is necessary in the case of vacuum operation downstream of the device.

 The half-body 1b forms below the butterfly 3 a sleeve or connector 4 for mounting on a pipe, not shown, for supplying combustible mixture to the combustion chamber or chambers of an internal combustion engine.

The half-body 1b supports a conduit 5 for supplying, within the stream 2, a fuel, for example, petrol, delivered under relative pressure by a discharge pump drawing from a tank not shown. The conduit 5 is formed in a support 6 in the form of a bar which is mounted on the half-body 1b by removable waterproof fixing means 7 so as to pass through the vein 2 diametrically traced
The support 6 has an outlet orifice 8 which is oriented downstream with respect to the circulation of the air stream in the direction of the arrow f1. The orifice 8 is oriented axially with respect to the body 1 and is controlled by a valve 9 which is formed in the form of a cylindrical needle guided in a bore 10 presented by a metering body 11 formed by the support 6.

The valve 9 has an extreme frustoconical bearing 12 intended to cooperate with a seat complementary to the orifice 8 towards which said bearing is always urged by an elastic member 13. Preferably, the elastic member 13 is constituted by a helical spring, working in compression, threaded concentrically with the valve 9, so as to bear on the bottom of a housing 14, of the cylindrical type, delimited by the metering body 11 to receive and guide a cylindrical extension 15 formed by a stirrup 16. The second end of the helical spring 13 bears on the extension 15 and urges the moving element, the 9-caliper valve 16, to bear against an adjustable stop 17 carried by the metering body 11. The stop 17 is, preferably, constituted by an eccentric, making it possible to adjust a stop position of the needle going from the interlocking to a tight closure of the orifice 8 by the frustoconical bearing 12.

 The drawing shows that, preferably, in the bottom of the housing 14 is provided a groove for receiving a seal 18, surrounding the valve 9. The seal 18 establishes a sealed separation between the housing 14 and the bore 10 which communicates with the conduit 5 and the orifice 8 for supplying the combustible fluid.

 The valve 9 is slaved in opening by a metering and adjustment device 19 of which the stirrup 16 is part. The stirrup 16 is mounted adjustable in axial position on the valve by a needle screw 20. The stirrup core is extended by two branches 21, diametrically opposite, which extend substantially parallel to the valve 9 while being oriented in the direction of the support 6. The branches 21 are permanently housed inside two slots 22 which are formed in the metering body 11. In this way, the stirrup 16 cannot be subjected to an angular displacement concomitantly the axial displacement which is imparted to it when the valve 9 slides in the bore 10.

 The ends of the branches 21 of the stirrup 16 are provided with two end portions 23 in the form of legs folded outwards relative to the longitudinal axis of the valve 9. The legs 23 are engaged in one of the turns of an elastic member 24, of the helical-type, working under compression, bearing on the support 6 and on a shutter 25 biased by said spring in the closed position of the stream 2 upstream of the outlet orifice 8 by relation to the direction of circulation according to arrow fl. The spring 24 and the shutter 25 form with the stirrup 16 the device 19 for metering and adjusting proportions. The shutter 25 is constituted by a cap 26 of frustoconical shape cooperating, by its large base, with a frustoconical diverging part 27 presented by the half-body 1a.

The action of the spring 24 tends to keep the frustoconical wall close to the large base of the cap 26 in closing support against an edge 27a defining the smallest section of the divergent 27. The cap 26 is oriented so that its small base is directed face in the direction of traffic in the direction of arrow f1. The cap 26 is extended by a tubular tail 28 which is threaded, with the possibility of axial sliding, on the metering body 11. The tubular tail 28 has> in its end portion, axial slots 29 which are intended to allow passage to the branches 21 of the stirrup 16, while allowing possible axial sliding of the shutter 25.

 The helical spring 24 thus represents a member assuming a first function of urging the cap 26 against the edge 27a and a second function of connection with the legs 23 of the stirrup 16. The spring 24 is made so as to be immobilized in rotation relative to the support 6 and, for this purpose, provision may be made to conform the terminal part of the last turn, lower according to the drawing, to make it include a lug 30 intended to be engaged in any one of several holes 31 made in the support 6 from the base of the metering body 11. Preferably, the holes 31 are equidistant and are inclined from the base of the metering body 11 towards the outlet orifice 8 at the level and at the periphery from which they emerge.

 The support 6 comprises> at the periphery of the base of the metering body 11 a clearance 32 more particularly consisting of flats hollowed out from above the bar. This clearance is provided for the installation of a flared cup 33 whose large open base is directed towards the cap 26. The small base has a rim 34 delimiting a central opening whose radius is greater than that of the geometric place occupied by the various holes 31 which are thus always cleared. The rim 34 also constitutes a support base for the last turn of the spring 24.

 The cup 33 can be made in any suitable way out of metal or plastic and its frustoconical shape is chosen so that the large open base has a circular cross section smaller than that of the useful half-body 1b and is also set back of the corresponding transverse edge of said body.

 The shutter 25 is completed by the existence of a pressure relief valve 35 with unidirectional efficiency whose opening direction is opposite to the direction of the arrow f1. The valve 35 is, for example, constituted by a shutter 36, in particular of the ball type, housed in a chamber 37 communicating, on the one hand with the internal medium of the body 1 by a hole 38 made in the tail 28 and, d on the other hand, with the medium external to the body 1 and located upstream of the cap 26 by conduits 39 formed in the latter. The conduits 39 open at the base of an axial cutout 40 made in an extension 41 of the cap 26. The cutout 40 serves as a guide for a control lever 42 mounted articulated by an axis 43 on the half-body la.A one end, the lever 42 is provided with a roller 44 cooperating with the cap 26 and at the other end, said lever is connected to a transmission member 45 such as a rigid linkage or a flexible control.

 The device described above operates in the following manner.

 In the case of application to an internal combustion engine, stopping such an engine places the device in the state of FIG. 1. The spring 24 pushes the shutter 25 in closing and the spring! 3 holds the needle 9 against the stop 17 which is adjusted to allow an annular passage sufficient to maintain an idle rotation regime. However, upon stopping, the arrival of the fuel under relative pressure is interrupted 3 so that the fuel is therefore not delivered into the stream 2.

If in these weights the engine is started, energizing the electrical circuit and / or driving in rotation, in particular by means of a starter, produces the supply of the discharge pump which supplies a fuel flow under relative pressure caused to circulate in the duct 5 and to pass through the annular section of the orifice 8 formed by the gap between the valve yawns. The launching of the engine produced by the aspiration of the combustion chamber or chambers, a vacuum in the body 1 causing the bonnet 26 to open. A flow of oxidizing fluid crosses the body 1 in the direction of the arrow f1 and takes
1 5 loads the fuel delivered by the orifice 8. This results in this spraying of the fuel and the formation with the oxidizing fluid of a combustible mixture passing through the chamber 2b to be directed towards the combustion chamber (s) .

 The device provides, under these conditions, a combustible mixture suitable for maintaining a stable idle speed as long as the operating conditions remain unchanged.

 If, for example) the user then cuts off the supply to the controlled ignition circuit, the discharge pump stops working and the fuel is no longer supplied to orifice 8. No combustible mixture is then formed from so that the engine stops working.

 If, on the other hand, the user acts to control a larger opening of the throttle valve 3, there is an increase in vacuum in the chamber 2a. The shutter 25 is thus urged into a larger opening against the action of the spring 24, in the direction of the arrow f This results in a progressive approximation of the different turns of the spring 24, so that the one in contact with the tabs 23 of the stirrup 16 acts on the latter in the same direction and therefore controls the sliding of the valve 9 in the direction for which the frustoconical bearing 12 moves away from the support seat of the orifice 8. The fuel supplied by the conduit 4 is thus delivered and distributed at a higher flow rate in the chamber 2b where it is sprayed by the circulation of air in the vein 2. it should be noted that a spraying of the fuel also occurs via of the air stream brought through the holes 31 whose orientation has the effect of establishing, at the periphery of the orifice 8, a kind of blowing nozzle which improves the primary spraying effect resulting from the arrival under relative fuel pressure and the effect of aspiration induced by air circulation. This spraying is further improved by the presence of the cup 33 which makes it possible to take a fraction of the mass of air circulating in the vein 2 and to accelerate the speed of this mass before it passes through the holes 31. Consequently, the opening of the shutter 25 makes it possible to control a proportional opening of the fuel inlet orifice under relative pressure and, consequently, to have a larger mixture in flow rate but respecting the same dosage to ensure correct operation of the motor.

 If the vacuum prevailing in the chamber 2a, or, at least, in the mixing chamber 2b, increases further as a result of the opening of the butterfly valve 3, a modification of the equilibrium conditions results. The shutter 25 is then urged into a larger opening relative to the diverging portion 27 against the action of the elastic member 24. this results in a proportionally larger opening of the fuel distribution orifice by a greater distance from the bearing 12 relative to the seat of the orifice 8.

 Consequently, the carburetor, in accordance with the invention, makes it possible to obtain an opening proportional to the circulation of air and, consequently, to ensure a proportional metering of the fuel according to the conditions of use.

Taking into account the mounting of the spring 24, it is understood that the crushing of the turns occurs in a differential manner when the shutter 25 is opened and that the turns progressively closer to the shutter are subjected to an axial displacement proportionally larger. This characteristic is used to allow a correction of proportion. In fact, by modifying the relative position of the legs 23 with the turns, the opening of the valve 9 is consequently modified for a given opening amplitude of the shutter 25. To this end, it suffices to release the lug 30 of the spring 24 of the hole 31> in which it is engaged, to rotate the spring 24 on itself and modify, consequently, the axial position of the stirrup 16 by movement of the turn in contact with the lugs 23
This feature is also taken advantage of to allow adjustment of the proportion of fuel. If, for example, it is desired to increase the richness, the screw 20 is loosened, so as to release the stirrup 16 relative to the valve 9. The stirrup 16 is then raised on the needle 9 so that the legs 23 and its branches 21 are brought to be able to be engaged in the turn immediately above that illustrated in the drawing.

The screw 20 is then again blocked so as to re-establish the connection between the clamp 16 and the valve 9. In such a case, since the active coil for the spring is located higher than the previous one, for a given opening of the shutter 25 and, consequently, for a determined compression of the spring 24, this will result in a greater opening of the valve 9 and a higher metering of fuel.

 A lower proportion adjustment is carried out in reverse. In the two cases above, it is obviously possible then to carry out an adjustment or a correction of the chosen mixing ratio by proceeding as described previously by means of the modification of the position of the pin 30 in any of the holes 31 surrounding the base of the metering body 11 in the support 6.

 The above operations can be carried out by separating the half-body la from the half-body 1b or by providing adjustment means accessible from the shutter 25.

 The sensitivity of the device and, in particular, its ability to authorize an opening of the shutter 25 for an engine idling speed, can be adapted by adjusting the relative spacing of the half-bodies 1a and 1b.

 In certain operating cases, we know that it may be necessary to have, temporarily, a different proportion adjustment and, in particular, a greater richness. This is, in particular, the case when the temperature conditions are not optimal to generate a homogeneous internal vaporization and the most complete combustion in the shortest time. These conditions are generally met, in particular, during a first start-up when the temperature of the oxidizing gaseous medium and / or that of the engine are relatively low.

 To allow such adjustment, according to the invention, the user actuates the enrichment control or or choke by the linkage 45 to cause the opening of the shutter 25, the stressing of the spring 24 and the interlocking of the butterfly 3 by a conjugation command as not shown.

The stirrup 16 is thus biased in the same direction and therefore causes a corresponding additional opening of the opening 8 to be added to that of the idle. The result is, for given functional conditions, a larger opening and a higher fuel flow rate than normal operating conditions.

 it should be noted that the vacuum prevailing in the chamber 2a is responsible only for the degree of opening of the shutter 25 and not for the call or the aspiration of the corresponding fraction of fuel. Indeed, the fuel is brought under constant relative pressure and its proportion is a function of the opening of the valve 9. It therefore becomes possible to produce a supply of pressurized air comparable to a principle of supercharging, so as to ensure, in somehow, rather than filling the cylinders by the effect of depression resulting from the variation in volume of their combustion chamber, overfilling said chambers with combustible mixture. Such a possibility makes it possible to deplete the mixture, to achieve better efficiency and lower consonance. , lation without intervention-: r a supply system by direct injection.

 The supercharging can then be obtained by producing a greater mass flow of air by a compressor or by placing, on the suction circuit, make a convergent 46 oriented facing the relative wind resulting from the movement of a vehicle whose engine is equipped with such a feeding device.

 FIG. 2 shows such an example according to which the convergent 46 is arranged upstream of a filter itself connected to a tube 47 formed by the body 1a in the extension of the diverging part 27.

 As is understandable, the choke control 45 can be controlled automatically by taking into account some of the operating parameters of the engine and, in particular, temperature.

 Fig. 3 shows that, to facilitate adjustment and obtain greater precision and fidelity of response, the supply device can be associated with an independent fuel supply circuit for a range of rotation corresponding to an idle speed. According to such a development, the half-body 1b comprises a control 48 comprising an inclined ramp 49 formed at the end of a rod 50 supported with the possibility of sliding by the support 6 and a seal ring 51 mounted on the half-body. The ramp 49 is placed under a tab 23 so that its lowest part is not, in the rest position 9 in contact with said tab 23 when the stirrup 16 occupies a position corresponding to the closing of the orifice 8 by the On the other hand, the ramp 49 is formed so that its highest part can, on the contrary, by displacement in the direction of the arrow f2, be brought under and at most just in contact with such a tab 23 occupying the above closing position.

 The rod 50 extends perpendicular to the support 6 and passes through the cup 33, if necessary. The free end of the rod 50 is integral with a deformable membrane 52 carried by a sealed housing 53 which is connected, by a pipe 54 with a vacuum outlet 54a opening under the butterfly 3. The boot 53 supports a member elastic return 55 acting on the rod in the opposite direction to that of arrow f2. The tension of the spring 55 can be adjusted by a screw 56. The case 53 also carries, coaxially with the spring 55, a needle 57 whose axial position can be adjusted by a screw 58. The needle 57 represents a stop limiting the stroke of the rod 50 in the direction of arrow f2.

 The half-body 1b also comprises a fuel supply circuit 59 independent of the main circuit controlled by the valve 9 and suitable for maintaining an idle rotation speed. This circuit 59 is, for example, constituted by an independent part 59e attached to the body lb.

 The part 59a comprises at least one air intake hole 60 normally located above the butterfly when the latter is in the closed position according to the drawing to be, in this state, completely free. The hole 60 opens into a mixing chamber 61 into which also arrives a calibrated inlet 62 of fuel delivered without pressure. The base of the mixing chamber 61 is crossed by an adjustable restrictor 63 controlling the section of at least one conduit 64 opening out below the butterfly valve 3 when the latter is in the closed position.

 At the start of engine operation, the vacuum prevailing under the butterfly 3 is transmitted to the housing 53. The membrane 52 attracts the rod 50 so that the ramp 49 comes to be placed under the corresponding tab of the stirrup 16 occupying the stable position rest in which, by adjusting the eccentric 17, the bearing 12 of the valve 9 closes the orifice 8. The normal circuit for supplying pressurized fuel into the stream 2 is thus closed although the shutter 25 is requested in opening.

 The air circulating in the vein 2 obligatorily borrows the hole (s) 60 then the chamber 61 where a premix is carried out with the fuel supplied by the hole 62. The fuel mixture is sucked through the conduit 64 to supply the engine and satisfy maintaining an idle speed whose adjustment is made by the restrictor 63.

 The idling circuit is maintained as long as the opening of the throttle valve 3 allows the establishment of a relative pressure difference between the hole 60 and the conduit 64. The connection between the tube 4 and the conduit 54 is provided so that, in the butterfly opening position, oti the pressure difference between the holes 60 and 64 is canceled, the orifice of 1o vacuum outlet 54e is released and put in relation with the vein 2, so that the depression prevailing in the bootmaker 53 is canceled. The spring 57 then returns the ramp 49 to a release position when the valve 9 opens, which again becomes directly subject to the operation of the shutter 25. The main fuel supply circuit then takes over from the idle circuit.

 Reverse operation occurs when the user closes the throttle valve 3. In fact, a vacuum is created under the butterfly valve so that the membrane 52 attracts the rod 50, the ramp 40 of which is placed or pushes the tab 23 in the closing direction of the orifice 8. At this time, the pressure difference between the hole 60 and the conduit 64 restores the supply circuit for the idle speed.

 It should be noted that the independent circuit 59 also assumes an economizer function. Indeed, first of all, the opening of the main circuit occurs only from a given degree of opening of the throttle 3 and, consequently, all risk of overdose disappears for rotation regimes. corresponding. In addition, if for example the engine powered by such a device is mounted on a motor vehicle which, in normal travel, is suddenly subjected to significant braking. The user, in such a phase releases the throttle valve 3 which closes while the engine is driven in rotation, sometimes still high, via the transmission. The closure of the throttle valve 3 gives rise to the depression which is responsible for the sliding of the rod 50 in the direction of the arrow f2. The ramp 49 then acts on the lug 23 and forces the stirrup 16 to slide in closing the orifice 8 by the valve 9. The fuel under relative pressure is therefore no longer delivered by the orifice 8 to the engine which has no need as soon as the throttle opening control is released 3.

 Identical operation occurs in the event that the vehicle follows a descending slope and that the user judges it preferable not to accelerate.

 Fig. 4 shows a development according to which the part 59e comprises a conduit 64 drilled as above and controlled by a restrictor 63 with an oblique arrangement. The conduit 64 opens into a chamber 65 into which also ends the inlet 62 which is controlled by a calibrated nozzle 66. The part 59e also includes a plurality of conduits 67 parallel and superimposed on the conduit 64.

The conduits 67 also open into the chamber 65 which contains a valve 68 biased by a spring 69 in an extreme high position according to the drawing, in which the various conduits are released.

The valve can also be brought, against the action of the spring 69, into another extreme position, low according to the drawing, in which the various conduits 64 and 67 as well as the inlet 62 are closed.

 The part 59a has in the upper part a hole 70 delimited to be separated from the conduits 64 and 67 and from the inlet 62 when the valve occupies the extreme high position. A hole 71, for example inclined, is made in the part 59e to make the chamber 2b communicate with the upper conduit 67 which has, in its part comprised between the chamber 65 and the intersection with the hole 71, a section greater than that of the other part. Fig.

4 also shows that the sum of the sections of the conduits 67 at the level of the chamber 65 is less than that of the hole 70.

 The setting of the spring 69 is chosen to be greater than the value of the vacuum prevailing under the butterfly 3 for a normal idle rotation speed. Thus, in this state, the valve occupies the high position under the action of the spring and isolates the hole 70. On the other hand, under the effect of the vacuum prevailing in the chamber 2b, a fraction of air borrows the conduits 57 and passes through the chamber 45 in which a premix is carried out with the fuel supplied by the inlet 62. The mixture obtained is directed through the conduit 64 towards the chamber 2b and ensures a supply of the engine for an idle speed regulated by the restrictor 63.

 As the butterfly valve 3S opens, the conduits 67 provide an additional authorized mixing flow since the adjustment 66 is chosen with a capacity greater than that of the restrictor 63. These conduits 67 then behave as leaks delivering an additional mixture allowing a revival without involving the main circuit. This operating phase is enabled by the presence of the inclined hole 71 which alone then supplies the pre-spray air fraction.

 When all of the conduits 67 are located under the butterfly valve being opened, the main supply circuit then takes over.

 Assuming that the butterfly is suddenly closed, the nascent depression, already responsible for the functioning of the device 48, exceeds the setting value of the spring 69. The valve 65 is thus brought to the low position and cuts the flow in mixture according to the flow idling allowed. This results in a simultaneous closure of the main and idling circuits and, as a result, a significant saving in fuel consumption.

 An operating phase can also take place with an engine, the air stream of which is at least partly produced by the rotation of a turbine, the rotary drive of which comes from the recovery of part of the energy of the gases d 'exhaust.

Indeed, in such a case, the overpressure arising during the closing of the butterfly at the level of the hole 70 pushes back the valve 65 which passes into the closed position.

 As is apparent from the above, the device according to the invention is of particularly simple design and can therefore be produced at a low cost price. In addition, the moving parts which are relatively sensitive to variations in the conditions of vacuum, pressure or speed, are reduced in number and do not have a relative articulation, so that the device is of precise and reliable operation.

Claims (10)

 1 - Supply device for an internal combustion type combustion engine with positive ignition, characterized in that it comprises  - a body (1) delimiting a vein (2) of circu  air lation,  - a fuel inlet orifice (8) under the  manages downstream pressure relative to the  air flow direction,  - a valve (9) urged to close the ori  arrival point (8) by a spring (13),  - And a device (19) for metering and adjusting  proportion including  a shutter (26) arranged in the vein  (2) upstream from the finish (8),  an elastic member (24) pushing the shutter  in the closed position and acting in the  opening direction on the valve (9).  2 - Device according to claim 1, characterized in that it comprises  - a shutter (26) mounted to slide axially  on a metering body (11) formed by the body  concentrically to the vein (2),  - a helical spring (24) bearing on the  body base (11) and pushing the shutter  in the closed position,  - a piece (16) in the shape of an adjustable mounting bracket  axially on the valve, angularly guided  by the metering body and comprising two branches  ches (21) whose ends are engaged between  two coils of the helical spring.  3 - Device according to claim 1 or 2, characterized in that it comprises a shutter (26) associated with a valve (35) overpressure relating the internal volume of the body with the surrounding environment.  4 - Device according to one of claims 1 to 3, characterized in that the shutter (26) is associated with a spring (24) assuming the additional function of a means of correcting the opening of the valve (9) and comprising for this purpose an extreme turn resting on the metering body (11) and forming a means of immobilization and angular adjustment on said base.  5 - Device according to claim 4, characterized in that the turn of the spring (24) bearing on the metering body (11) is extended by a lug (30) capable of being engaged in any one of several holes (31) formed in the base of the body (11) so as to open in the vein (2) upstream of the inlet (8) and to open at the periphery of the latter to form a blowing means and spraying of the gasoline delivered.  6 - Device according to claim 5, characterized in that the base of the body (11) is associated with a frustoconical cup whose large base opens in the direction of the shutter.  7 - Device according to one of claims 1 to 4, characterized in that the shutter is associated with a control (42) immobilization in adjustable pre-opening.  8 - Device according to one of claims 1 to 2, characterized in that, on the one hand, the valve (9) is associated with an automatic closing means of the inlet (8), this means comprising an inclined ramp (49) acting on the caliper (16) and controlled by a housing (53) sensitive to the vacuum prevailing downstream of the butterfly (3) and, on the other hand, the body (1) carries an auxiliary supply circuit in idle speed comprising at least one air inlet hole situated above the butterfly in the closed position at least one hole situated under the butterfly in the same position and a mixing chamber in which said holes end and a calibrated fuel supply.  9 - Device according to claim 8, characterized in that the hole located under the butterfly in the adjustable position is associated with an adjustable restrictor.  10 - Device according to claim 8, characterized in that the chamber of the auxiliary supply circuit comprises a closing valve maintained in the opening position by a spring whose calibration is just greater than the calling force resulting from the vacuum reigning under the throttle in normal idle rotation.