GB2050504A

GB2050504A - Electromagnetic Fuel Injector for an Internal Combustion Engine Carburation System

Info

Publication number: GB2050504A
Application number: GB8012979A
Authority: GB
Original assignee: Mikuni Corp; Mitsubishi Motors Corp
Current assignee: Mikuni Corp; Mitsubishi Motors Corp
Priority date: 1979-04-24
Filing date: 1980-04-21
Publication date: 1981-01-07
Also published as: FR2455187A1; DE3015403A1

Abstract

Swirl is imparted to the fuel flowing to the outlet 8m when the valve head 8d is raised from its seat 8j. The swirl may be imparted by tangential inlets 8k to the passage 8h around the valve head 8d or by a helical groove (8l), Fig. 6 (not shown) in the valve head. The injector 8 supplies fuel to an intake passage (3), Fig. 1 (not shown), under the control of a microcomputer 7 which processes air flow, exhaust oxygen concentration and engine operating condition signals. <IMAGE>

Description

SPECIFICATION Fuel Injection Valve Device for Internal Combustion Engine Carburation System Description of Invention The present invention relates to a carburation system for an internal combustion engine, the system including a fuel injection valve device for injecting fuel into an air intake passage.

A carburation system has already been proposed for an internal combustion engine in which the fuel feed rate is controlled electronically by controlling an electromagnetic fuel injection valve electronically by pulse signals generated according to electric signals derived from a sensor for sensing the rate of flow of air into the system. However, the known system has a disadvantage in that it is difficult to secure effective atomization of the fuel injected into the air intake passage, due to the valve construction, so that effective fuel feed and mixing of fuel and air, is prevented.

An object of the present invention is to provide a fuel injection valve device for an internal combustion engine carburation system whereby fuel atomization can be improved in comparison with known devices, to avoid the abovementioned problem.

According to one aspect of the invention, there is provided a fuel injection valve device for use in an internal combustion engine carburation system to inject fuel into an air intake passage of such a system, the device comprising a valve housing providing an internal space, a fuel inlet and a fuel outlet communicating with said internal space, and, disposed in said valve housing, a valve member reciprocable, by means including an associated electromagnetic coil fixed with respect to the valve housing, between a closed position in which the outlet is cut off from said inlet and an open position in which fluid can pass through the valve body from said fuel inlet to said fuel outlet via said internal space, the device including means for imparting a swirling or rotational movement to fluid issuing from the outlet after passage through the valve body when the valve member is in said open position.

According to another aspect of the invention, there is provided a carburation system for an internal combustion engine comprising an air intake passage, a fuel tank, a fuel injection valve device according to the first mentioned aspect of the invention operable to inject into said air intake passage a fluid fuel supplied to said fuel inlet from the fuel tank by a fuel pump, and means for energising and de-energising the said coil, to open and close the valve intermittently.

Embodiments of the invention are described below by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic diagram illustrating an internal combustion engine having a carburation system incorporating an injection valve device embodying the invention, Figure 2 is a schematic diagram illustrating the operation of an air flow rate detecting device forming part of the system of Figure 1, Figure 3 shows at (a), (b) and (c) three graphs illustrating the manner in which the injection valve device in the system of Figures 1 and 2 is controlled electronically, in accordance with electrical signals provided by the air flow rate detecting device, Figure 4 is a longitudinal sectional view of one form of fuel injection valve embodying the invention, Figure 5 is a view of the valve of Figure 4 in cross-section along the line V-V in Figure 4, Figure 6 presents longitudinal sectional view of another fuel injection valve embodying the invention, Figure 7 is a diagram showing yet another form of fuel injection valve embodying the invention in longitudinal section, and showing, diagrammatically, associated parts of a fuel supply and control system connected therewith, and Figure 8 is a view of the valve of Figure 7 in cross-section along the line VIll-VIll in Figure 7.

As shown in Figures 1 and 2, in a carburation system for an internal combustion engine 17, an airflow rate detecting device 4 is provided in an air intake passage 3 between an air cleaner 1 and a throttle valve 2.

The air flow rate detecting device 4 comprises a triangular prism 4a disposed with one face facing perpendicularly against the direction of flow of air along the passage 3, a speaker 4b functioning as an ultrasonic wave generator and a microphone 4c functioning as an ultrasonic wave receiver being disposed diametrically opposite one another on the wall of the intake air passage 3. The speaker 4b and microphone 4c are disposed downstream of the triangular prism 4a.

Reference numeral 5 designates an intake air flow rectifier provided for rectifying the intake air flow thus ensuring stabilized operation of the intake air flow rate detecting device 4.

When air is flowing along the intake passage 3 a periodically repeating pattern of turbulence (a Karman trail) is produced downstream of the prism 4a, the frequency of repetition being proportional to the velocity of air flow.

Accordingly, as shown in Figure 2, if an ultrasonic signal corresponding to an a.c. signal SIN is generated by the speaker 4b, the sound received by microphone 4c corresponds to the sound emitted by speaker 4b with amplitude modulation and frequency modulation caused by the turbulence, so that the electrical signal SOUT produced by microphone 4c has a mean frequency corresponding to SIN but has a periodic amplitude and frequency modulation the repetition rate of which is proportional to the air flow speed. This modulated signal SOUT is passed to harmonic component by a wave shaping circuit 6 including a low pass filter detector, etc.

whereby higher harmonic compounds are eliminated and only the modulation frequency as an envelope component is selected, so that circuit 6 provides an output signal in the form of an alternating sinusoidal voltage signal Eo having a frequency proportional to the air flow velocity, and thus to the air volume flow rate along the passage 3 and fluctuating periodically.

This alternating voltage signal Eo is used to derive a signal comprising a succession of pulses Pw (Figure 3-b) the pulse repetition frequency of which is equal to the frequency of signal Ew or to a predetermined multiple or fraction of that frequency.

An electromagnetically operated fuel injection valve 8, operable to inject liquid fuel into passage 3, is driven by a train of pulses Pa;' which are produced in synchronism with the pulses Pw but are, as will appear later, pulse-width modulated.

The derivation of the signal Pa;' from signal Eel) is effected by a micro-computer 7 employed as an electric control means.

The driving pulses Pco' are continuously applied to an electromagnetic coil 8a of the valve 8 causing the valve 8 to be intermittently operated in synchronism with the pulses Paw'. The width of each pulse in the train of driving pulses Pa;' is selectively determined according to, inter alia, the specific performance of the fuel injection valve 8.

As shown in Figures 1 and 4, the injection valve 8 includes a valve housing 8b providing an internal space 8b', which is substantially cylindrical and has, as its axis, a central longitudinal axis of the valve housing, an axial cylindrical bore extending from one end of the valve housing to space 8b' and affording an inlet 8n and a passage 8g' connecting the inlet 8n with space 8b', an axial cylindrical bore extending from the space 8h' to a position adjacent the other end of the valve housing, at which position the bore 8d connects with a co-axial cylindrical recess of enlarged diameter, connected in turn, via a coaxial valve seat 8jwith the co-axial outlet 8m of the valve at said other end of the valve housing.

Said other end of the housing is formed as an injection nozzle 8f.

The valve includes a valve member 8c which is of ferro-magnetic material and is of circular crosssection perpendicular to the valve axis, the valve member being in the form of a plunger having an enlarged cylindrical portion, accommodated with radial and axial clearance in the space 8b, a stem of reduced diameter extending axially from the enlarged cylindrical part, along the bore providing passage 8g, to a valve head 8d in th form of a needle valve, comprising a cylindrical body and a conical tip which, in the closed position of the valve, sealingly engages the valve seat 8j.The cylindrical body of valve head 8d is a close sliding fit in the bore providing passage 8g, and communication between the passage 8g and a chamber or passage 8p defined, when the valve is closed, between the valve head 8d and the recess at the end of the last-mentioned bore, is afforded by passages 8h, 8i and 8k described more fully below.

When the valve head 8d is in engagement with the valve seat, the valve is closed, and there is no communication between outlet 8m and passage 8p, and hence no communication between outlet 8m and inlet 8n. When the valve member 8c is moved axially away from valve seat 8j, the valve is open and fuel can pass from inlet 8n, through passage 8g', space 8b', passage 8g, and passages 8h, 8iand 8k, to the space within the recess adjoining valve seat 8j, and thence, via the gap between the valve seat 8jand the valve head 8d, to the outlet 8m. The enlarged cylindrical part of the plunger 8c is, in the closed position of the valve, disposed partly within one end of the coil 8a, which is coaxial with the rest of the valve and partly defines the space 8b', the arrangement being such that when the coil 8a is energised by an appropriate electrical current, the valve member 8c will be moved axially away from the valve seat 8j by the magnetic field of the coil 8a to open the valve.

A compression spring 8e, acting on the end face of the valve member 8c remote from the valve head 8d serves to return the valve member axially when the coil 8a is de-energised, into the closed position in which the valve head sod is in engagement with valve seat 8j.

As shown in Figures 4 and 5, means TU which operates to impart a swirling or rotational movement to the fuel injected from the fuel outlet 8m is provided in the fuel injecting nozzle 8f at the tip end of the fuel injection valve 8. The means TU comprises the passages 8i, 8k, 8p, referred to above, and these passages, and their effect will now be described in greater detail.

Referring to Figure 5, the chamber or passage 8p defined, at least when the valve is closed, between the valve head 8d is of circular annular form and is defined between the cylindrical periphery of valve head 8d and the opposing cylindrical surface of a circular annular wall, coaxial with valve head 8d, which wall separates passage 8p from a second, radially outer, circular annular passage 8i, coaxial with the valve, the passage 8i being connected with passage 8g' through by-pass passages 8h and being connected with passage 8p by three communication passages 8k each extending through said circular annular wall. Each of the communication passages 8k, as shown in Figure 5, is so arranged that at least over its portion which opens into passage 8d, and preferably over its whole length, its centre line extends in a direction having a substantial circumferential component relative to the valve axis, and preferably extends substantially tangentially of the first circular passage 8p. The passages 8k are, of course, so arranged that the circumferential components of the directions in which they extend from passage 8;to passage 8p are all in the same rotational sense.

Accordingly, when a driving pulse Po' is applied to the electromagnetic coil 8a of the fuel injection valve 8 by the micro-computer 7, the magnetic coil 8a is energised and the plunger 8c is shifted a fixed distance against the spring 8e opening the valve.When the valve is open, ful, supplied under pressure to fuel inlet 8n of the valve 8 passes, as indicated by the arrow in Figure 4, via the internal passage 8g', the internal space 8b', the internal passage 8g and the by-pass passage 8h, into the passages 8i and is forced through the three communicating passage 8k into the recess adjacent the valve seat 8j so that the injected fuel is swirled about the valve axis as shown by the arrows in Figure 5, as it passes to the outlet 8m to be injected into the passage 3 thereby improving the atomization of the fuel injected from the fuel outlet 8m of the fuel injection valve 8.

On the other hand, during an interval between pulses Pa;' the coil 8a is not energised and spring 8e depresses the plunger Sc to keep the needle valve closed.

The outlet of valve 8 is disposed in a portion 9 of the intake passage 3 which is downstream of the throttle valve 2. An electric fuel pump P, (Figure 1) has its outlet connected via a line 11 with fuel intake 8n of valve 8, and has its inlet connected via an inlet line with a fuel tank 13, the fuel pump P, in operation, supplying valve 8 with fuel under pressure. A fuel regulator 10 having a first chamber 1 Ob and a second chamber 1 Oc separated by a diaphragm 1 Oa has its chamber 1 Oc connected to the line 11, and hence to the fuel inlet 8n of the fuel injection valve 8 via a branch pipe 14 and has its chamber 1 Oc connected, via a vacuum pipe 12, to the portion 9 of intake passage 3 at a location near the fuel outlet of valve 8.A fuel return conduit 1 5 is provided between the first chamber 1 Ob and the fuel tank 13 and a valve member 1 Od connected with diaphragm 1 Oa cooperates with a valve seat around the outlet from chamber 1 Ob into conduit 1 5 to control the rate at which fuel is allowed to return from line 11 to the fuel tank and thereby control the pressure of fuel supplied to valve 8.

The reference numeral 10e in Figure 1 designates a spring urging the diaphragm 10a in the direction such as to close the valve 1 Od is closed through a diaphragm 1 Oa respectively.

When the pressure in the intake passage 9 decreases, the pressure in the second chamber 1 Oc also decreases so that the diaphragm 1 Oa is pulled against the spring 1 Oe opening the valve 1 Odto allow a part of the fuel to return into the fuel tank 1 3 through the fuel return tube 15, so that the fuel pressure feeding the fuel to the fuel injection valve 8 is reduced, thus maintaining a fixed pressure difference between the fuel supplied to the inlet of the fuel injection valve 8 and the portion 9 of the intake passage, (where the pressure is normally sub-atmospheric).

Operating condition detecting means is provided to detect the temperature of the engine cooling water, the load condition, the acceleration and deceleration rate and the engine operating condition of the internal combustion engine 1 7 and to produce electric signals corresponding to each condition. The operating condition detecting means includes a sensor 16a for detecting the engine cooling water temperature, a sensor 1 6b for detecting the load on the internal combustion engine 17, a sensor 1 6c for detecting the acceleration and deceleration rate of the internal combustion engine 1 7 and a sensor 1 6dfor detecting the oxygen concentration of the exhaust gas.A control circuit 1 6 is also provided to receive and synthesize the information signals from the sensors 1 6a to 1 6d to judge the operating condition and to produce electric signals by a pre-programmed calculating means.

The control circuit is incorporated in the microcomputer 7, and the signals from the sensors 1 6a through 1 6d are input to the control circuit 1 6 through terminals A through D, then transmitted to the main control circuit of the micro-computer 7.

As indicated previously the micro-computer 7 operates so that the driving pulses Pa;' applied to valve 8 are synchronised with the raw pulses Pco, but are pulse width modulated, in accordance with the electrical signals given by the control circuit 1 6 of the operating condition detecting means. The driving pulses Pa;' (Figure 3-c) of modulated pulse width are output from the terminal E of the micro-computer 7 and applied to the fuel injection valve 8.

In Figure 1, reference numeral 18 designates an exhaust pipe.

The carburation system and control system described above with reference to Figures 1 to 5 derives, from the flow velocity, and hence the volumetric flow rate of the air passing along intake passage 3 after being sucked through the air cleaner 1, an alternating voltage signal Ew of a frequency porportional to the air flow rate as detected by the air flow detecting device 4, then the alternative voltage signal Ew is converted into a train of pulses Po of a frequency proportional to that of signal Ew by the micro-computer 7 and driving pulses Po > ' synchronised with pulses Po but of a pulse width determined by computer 7 in accordance with sensed engine conditions etc.

are applied to the fuel injection valve 8 so that the said fuel injection valve 8 is intermittently operated in synchronism with or in dependence on the frequency of occurrence of the pulses Pc > .

During the resultant intermittent injection of fuel into the portion 9 of the intake passage, a rotational movement or swirling movement is imparted to the fuel as it passes through the outlet of valve 8, to improve atomisation thereby securing good fuel/air mixing and feeding the fuel effectively to the engine. Furthermore, the pressure of the fuel fed into the fuel injection valve 8 is regulated so that the pressure differential between the intake passage and the outlet of the valve is kept constant.As the length of time for which the fuel injection valve 8 is kept open each time that it is operated depends on the pulse width of the corresponding modulated driving pulse Pus', the amount of the fuel injected for each pulse will vary in accordance with the operating condition of the internal combustion engine 1 7, and the injection of the fuel will be electronically controlled so that its condition is maintained optimum according to the operation of the engine. The valve 8, having means TU to impart swirling to the fuel discharged from the outlet of the valve, as described with reference to Figures 4 and 5 may be replaced by the valve shown in Figure 6, which is identical with the valve of Figures 4 and 5 except that means TU is replaced by means TU'. (In Figure 6, parts corresponding to parts in Figures 4 and 5 have like references).

Thus, in the valve of Figure 6, the bore 8g extending from space 8b' towards valve seat 8, extends right to said valve seat without variation in its diameter, while the valve head Sdof the valve member, which again has a cylindrical periphery which is a close sliding fit in the bore 8g, has a helical groove 8/formed therein from the end of the valve head 8dwhich is connected to the elongate stem to the conical end which engages the valve seat so, the resultant notch on the conical end of the valve member, where the helical groove terminates, lying radially outwardly of the radially inner limit of the valve seat 8jwhen the valve is closed, so that when the valve is closed no fuel is discharged, whereas when the valve is open, fuel can pass along the spiral groove 8last the valve head 8d, to emerge with a swirling movement from the valve outlet 8m.

The valve shown in Figure 6 is of simple construction but can impart very effectively a swirling movement to the fuel intermittently injected into the intake passage and the atomization of the injected fuel can be thereby improved.

In the embodiments described with reference to Figures 1 to 6 the fuel injection valve 8 is provided in the portion 9 of the intake passage which is downstream of the throttle valve 2, however, if desired, the valve 8 (and the inlet of line 12) can be provided upstream of the throttle valve 2.

A variant of the carburation system of Figures 1 to 5, incorporating another form of injection valve, is described below with reference to Figures 7 and 8.

The carburation system incorporating the elements shown in Figures 7 and 8 may differ from that described with reference to Figures 1 and 2 only in the form of the injection valve and the system for controlling the supply of fuel to, and the return of fuel from the valve.

Referring to Figure 7, the variant injection valve shown also exhibits substantial rotational symmetry about a longitudinal axis thereof, except in the respects specifically noted below, and comprises a valve housing 100 which includes an upper housing part 101 and a lower housing part 103, which has an upper enlarged part thereof fitted in a cavity in the lower end of the part 101. An internal space 101' in the upper housing part 101 accommodates an electromagnetic coil 102.

The housing part 101 has an opening at its upper end, through which the coil 102 is inserted, in assembly of the valve, into space 101', and has an axial passage extending downwardly from space 101' to connect with the upper end of an axial passage extending through the lower housing part 103.

The opening at the upper end of housing part 101 is closed by a member comprising an axially extended central core 105 with a flange 106 extending radially therefrom, the flange 106 being fitted within the opening at the upper end of housing part 101, above coil 102, to hold the coil 102 firmly in position, while the core 105 projects within the coil. The core 105 has a fuel inlet passage 104 formed axially therethrough to communicate with the space 101'.

The coil 102 is encapsulated in a casing of a material impervious to, and unaffected by the fuel, and the space 101' is sealed off, except for its connections with passage 104 and the internal axial passage in part 103, by sealing rings 107 and 108, which are respectively disposed within coil 102 between the casing of the latter and core 105, and around the coil 102, between the coil casing and the wall of housing part 101.

The axial passage through part 103 includes an enlarged chamber 120, adjacent the lower, free end of the part 103 and an outlet passage 109 extending from chamber 120 to open on the lower free end of part 103. Mounted for free axial movement within the axial passage through part 103, and extending into the space 101', is a valve member comprising a plunger 111 surmounted by an iron armature member 112, the plunger 111 carrying at its lower end a valve head 110, in the form of a needle valve, which in the closed position of the valve engages a valve seat 109' formed around the outlet 109 where the latter leaves the chamber 120, to prevent fluid flow from chamber 120 to said outlet, and which valve head, in an open position of the valve, is out of engagement with seat 109' to allow such flow.

In the middle of plunger 111, i.e. below armature 112 and above the valve head 110, is a portion 114 which is of non-circular cross-section perpendicular to the valve axis, preferably of square cross section, said portion 114 being a sliding fit in a portion 11 6 of the axial passage through part 103, which portion 116 is of complementary non-circular cross-section (i.e.

square cross section in the preferred case). Thus the valve member is prevented from rotating about the vertical axis of the valve.

Above the portion 114, the plunger 111 is formed with a radially projecting flange 11 5, perpendicular to the valve axis, this flange being accommodated in a portion of enlarged diameter, of the axial passage through part 103, which portion immediately adjoins the upper end of the part 103, and the portion of the plunger 111 which extends axially upwardly from flange 11 5 to armature 112 extends through a central aperture, of smaller diameter than the flange, in an abutment plate 11 7 disposed between the upper end of part 103 and the end of the recess in part 101 in which part 103 is received.

Movement of the valve member away from the valve seat 109' is limited by abutment of flange 115 with plate 117.

The armature 112, which, in the closed position of the valve, closely adjoins the lower end of the coil, and, in the open position of the valve extends partly within the coil, is spaced longitudinally from the adjoining end of core 105 in either of these positions of the valve, and a compression spring 113 is interposed between the upper, free end of armature 11 2 and the adjoining, lower, end of core 105 to urge the valve member towards the closed position.

Extending axially from the upper end of armature 112, through the latter and into the plunger 111, as far as a point just above valve head 110, is a first part of a fuel passage 118 the second part of which comprises a diametral bore through plunger 111 intersecting said first part of passage 11 8. The passage 11 8 serves to conduct fuel supplied via passage 104 to the internal space 101' in the upper housing, from said space 101' into an internal space in the nozzle part 103, the latter internal space being partly constituted by said axial passage through part 103, and including said chamber 120.Thus, when the electromagnetic coil 102 is energised, the needle valve 110 is pulled up from its seat 109' by the electromagnetic coil 102 to open the outlet 109 to the passage of fuel from chamber 120, while when the electromagnetic coil 102 is de energized, the needle valve 110 is returned to the original position by the spring 113 to close the outlet 109 to cut off the injection of the fuel.

Repetition of the above operation can ensure intermittent supply of the fuel.

The fuel injection valve 8' is provided with the means TU" to impart a swirling movement about the valve axis to the fuel injected from the outlet 109. Thus, a bulk-head 119 is interposed between the part of said internal space in part 103 into which passage 118 opens directly, and the chamber 120, the portion of the axial passage extending through bulkhead 11 9 being in the form of a smooth cylindrical bore in which the cylindrical periphery of the valve head 110 is a sealing sliding fit.The fuel swirling chamber 120 is of circular annular form in cross-section (Figure 8) being bounded on its radially outer side by a peripheral wall surface afforded by a wall provided by bulkhead 11 9 and which wall is part circular in cross section, and being bounded by the valve head 110 on its radially inner side, at least when the valve is closed.

An outer chamber 123, constituting the part of said internal space in part 103 which is outside bulkhead 119, and which chamber 123, in crosssection at the axial position chamber 123 has the form of a broken annulus concentric with chamber 120, is connected with chamber 120 by a passage 1 21 extending through the peripheral wall of said bulkhead, while a passage 122 extends from chamber 120, through a solid portion extending from chamber 120 to a further outlet on the side of nozzle part 103.In operation, fuel is supplied to the inlet 104 of the fuel injection valve 8' as shown in Figure 7 via a fuel feed line 127 by a fuel pump 124, a damper 125 being interposed between pump 124 and valve 8' and a regulator 126, which will alleviate the pulsation in the fuel pressure at the time of ignition being also connected to the fuel inlet 104 of the fuel injection valve 8'. A return line 130 having a flow control valve 128 therein to regulate the fuel injection rate and electromagnetic valve 129 therein which is connected with an ignition switch (not shown) to prevent a fuel pressure drop in line 130 after the switch has been turned off, is connected to the further outlet of valve 8', and thus to said passage 122, and extends to a fuel tank 131 thereby connecting the return passage 130 with the fuel swirling chamber 120 and a fuel tank 131.Thus, the fuel which is pumped out from the fuel tank 1 31 by the fuel pump 124 is passed thereby through damper 125 and its fuel pressure is regulated by the regulator 126 and is fed into the fuel injection valve 8' through the fuel injection inlet 104 and then is conducted into the fuel chamber 1 23 of the nozzle 103 through passage 1 1 8 and then is fed into the fuel swirling chamber 20 through the passage 121.The centre line of passage 121 extends substantially tangentially to the annular centre line of the annular chamber 121, as does that of passage 122, so that fuel forced through passage 1 21 into chamber 120 is caused to swirl around the chamber 120 as indicated by the arrows in Figure 8, to pass, in part, tangentially from chamber 1 20 along passage 122, and to be discharged into the return passage 130 and returned to the fuel tank 131 after passing through the throttle valve 128 and the electromagnetic valve 129.

With this arrangement, the fuel is kept at the required pressure during operation and is circulated through the fuel injection valve 8', and as the fuel is circulated in the chamber 120 in the nozzle part 1 03, the fuel around the needle valve member 110 which closes the fuel outlet 109, is always swirling about the valve axis so that the fuel is injected, while still swirling, into the intake passage of an internal combustion engine due to the rotational inertia of the fuel, as soon as the needle valve 110 is opened. The atomization of the fuel is thereby greatly improved.

Instead of the flow control valve 128 which is provided as a flow rate controlling member in return passage 130, an orifice or throttling restriction can be provided. Moreover, the return passage 130 can be connected to the fuel feed passage 127 on the intake side of the fuel pump, in which case the return line 130 can normally be made shorter than if the line 130 is connected directly to the fuel tank.

Claims

1. A fuel injection valve device for use in an internal combustion engine carburation system to inject fuel into an air intake passage of such a system, the device comprising a valve housing providing an internal space, a fuel inlet and a fuel outlet communicating with said internal space, and, disposed in said valve housing, a valve member reciprocable, by means including an associated electromagnetic coil fixed with respect to the valve housing, between a closed position in which the outlet is cut off from said inlet and an open position in which fluid can pass through the valve body from said fuel inlet to said fuel outlet via said internal space, the device including means for imparting a swirling or rotational movement to fluid imparting from the outlet after passage through the valve body when the valve member is in a said open position.

2. A fuel injection device according to claim 1 wherein the valve member is disposed adjacent said outlet and is reciprocabie along the axis of said outlet into and out of sealing engagement with a valve seat formed around said outlet, and wherein said means for imparting a swirling or rotational movement to fluid issuing from the outlet includes a peripheral surface, facing outwardly from said axis and formed on the valve member adjacent said outlet and which is, in cross-section perpendicular to said axis, substantially circular and coaxial with said outlet, and a further surface formed in said valve housing, facing towards said axis and, substantially circular in cross-section perpendicular to said axis, said further surface being also susbtantially coaxial with said outlet and being so disposed that when the valve member is in its closed position there is defined between the valve member and said further surface a susbtantially circular annular passage and when the valve member is in its open position there is defined a space bounded on the radially outer side by said further surface and connected with said opening via the gap between the valve member and said valve seat, said means for imparting a swirling or rotational movement to fluid issuing from the outlet further comprising at least one duct opening onto said further surface and in communication with said inlet, said duct, in the region of said circular annular passage, extending in a direction having at least some tangential component.

3. A device according to claim 2 wherein said further surface is provided by an annular wall, susbtantially coaxial with said opening, separating an annular passage formed in said housing on the radially outer side of said wall from said passage defined between the valve member and said further surface, the or each said duct extending through said annular wall.

4. A device according to claim 2 or claim 3 wherein said duct has its centre line extending tangentially with respect to said circular annular passage.

5. A device according to claim 2, wherein there is provided a return passage which connects said circular annular passage with a further outlet provided for connection, in use of the device with a fuel tank or the suction passage of a fuel pump.

6. A fuel injection valve device according to claim 1 wherein the valve member is disposed adjacent said outlet and is reciprocable along the axis of said outlet, along a substantially cylindrical passage coaxial with said outlet, into and out of sealing engagement with a valve seat formed at one end of said passage adjacent said outlet, wherein the valve member has a body with a substantially cylindrical peripheral surface opposing the wall of said substantially cylindrical passage, and wherein said means for imparting a swirling or rotational movement to fluid issuing from the outlet includes a spiral groove formed on the periphery of the valve body.

7. A device according to any preceding claim, wherein said valve housing comprises an upper housing part in which said inlet is formed and in which an upper part of said internal space communicating with said inlet is formed and having said electromagnetic coil in said internal space, and a lower housing part in which said outlet is formed and in which is formed a lower part of said internal space which communicates with said fuel outlet when the valve member is in a said open position.

8. A device according to claim 7, wherein the internal space in said upper housing part and the internal space in the lower housing part are connected by a passage formed in said valve member plunger.

9. A device according to claim 1, wherein the valve member has a central portion which is elongate along the axis along which the valve member is reciprocable, and which central portion is provided with a flange extending radially outwardly therefrom substantially perpendicular to said axis of reciprocation, and wherein an abutment is provided for engagement with said flange to limit the stroke of the valve member away from its closed position to an open position.

10. A device according to claim 1, wherein the valve member has a part having a non-circular shape in cross section perpendicular to the axis along which the valve member is reciprocable, and which part is guided for such reciprocation in a passage of complementary cross-section in said housing so that the valve member is free to reciprocate along said axis but is prevented from rotating about said axis.

11. A device according to claim 1 , wherein said valve body member has a valve head in the form of a needle valve.

12. A carburation system for an internal combustion engine, comprising an air intake passage, a fuel tank, a fuel injection valve device according to any of claims 1 to 11 operable to inject into said air intake passage a fluid fuel supplied to said fuel inlet from the fuel tank by a fuel pump, and means for energising and deenergising said coil to open and close the valve intermittently.

1 3. A carburation system according to claim 12, wherein the fuel injection valve device is a device in accordance with claim 5, and wherein said further outlet is connected with a return conduit connected with said fuel tank or the suction passage of the fuel pump, and wherein an electromagnetic valve is provided to regulate the fuel flow in said return conduit.

14. A fuel injection valve device for use in an internal combustion engine carburation system, substantially as hereinbefore described with reference to, and as shown in, Figures 4 and 5 of the accompanying drawings.

1 5. A fuel injection valve device for use in an internal combustion engine carburation system, substantially as hereinbefore described with reference to, and as shown in, Figure 6 of the accompanying drawings.

1 6. A fuel injection valve device for use in an internal combustion engine carburation system, substantially as hereinbefore described with reference to, and as shown in, Figures 7 and 8 of the accompanying drawings.

1 7. A carburation system for an internal combustion engine, substantially as hereinbefore described with reference to, and as shown in, Figures 1, 2, 4 and 5 of the accompanying drawings.

1 8. A carburation system for an internal combustion engine, susbtantially as hereinbefore described with reference to, and as shown in Figures 1, 2 and 6 of the accompanying drawings.

1 9. A carburation system for an internal combustion engine, substantially as hereinbefore described with reference to, and as shown in Figures 1, 2, 7 and 8 of the accompanying drawings.

20. Any novel feature or combination of features described herein.