IL23019A - Fuel injector devices and systems - Google Patents

Description

•niun inn -ηιπΐ"Ί m PATENT ATTORNEYS · D'DID S 'ΠΙΙ) PATENTS AND DESIGNS ORDINANCE SPECIFICATION · FUEL. INJECTOR 0EVICE8 ANO SYSTEMS I/We PETROL INJECTION LIMITED ( FORMERLY, TEC ALEMI T (DEVELOPME TS ) LIMITEo), A BRITISH OOMPANV, OF VALLEY ROOD, PLVMPTON, PLYMOUTH, DEVON, ENGLAND, AND HAROLD ERNEST JACKSON, A BRITISH SUBJECT, OF "PANORAMA", VI OAR AGO ROAD, PLY. PTON ST, MARY, DEVON, ENGLAND. do hereby declare the nature of this invention- and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement :- This invention relates to low pressure continuous fuel injection systems for internal combustion engines.

The invention relates particularly to fuel injector devices suitable for use in low pressure continuous fuel injection systems in which metered fuel is fed to the devices and mixed therein with low-pressure air prior to discharge from the injector device at substantially the pressure of the air supply. Examples of such systems are disclosed in British Patent Specifications Nos. 1,045,150 and 1,098,825. Typically, fuel is supplied to the injector devices at pressures up to several tens of p.s.i. and air at pressures of a few p.s.i.

According to the present invention, an internal combustion engine having a low pressure continuous fuel injection system including a plurality of injector devices having outlet orifices disposed in the engine air intake manifold structure, each injector device including a body portion having liquid fuel and air inlets, an air chamber communicating with the air inlet and with an Injector nozzle defining the said outlet orifice, the fuel inlet communicating with a fuel tube so positioned that the fuel stream emerges from the fuel tube into air from the air chamber and is discharged through the outlet orifice, the fuel injection system further including means operable to supply liquid fuel to the fuel inlets of the Injector devices and air pump means for supplying air to the air inlets of the injector devices, and valve means operable to prevent sub-atmospheric conditions in the air intake manifold structure giving rise to sub-atmospheric conditions in the injector devices.

In one embodiment, the body portion of each injector devioe has superposed transverse fuel and air inlets and the The nozzle can be straight or bent as desired. The fuel tube can terminate in the air chamber, preferably being aligned with the inlet to the injector nozzle, although this is not essential. Air fed to the air chamber then impinges on the fuel emergent from the fuel tube, breaks it into globules which are swept into the injector nozzle. Alternatively, the fuel tube can extend through the air chamber into the injector nozzle terminating short of the outlet orifice so that the fuel stream emergent from the fuel tube enters air flow from the air chamber and is discharged through the outlet orlfioe. In this latter arrangement the fuel tube can incorporate a flow restrictor device, located adjacent the outlet of the fuel tube.

By way of example, the invention will be described in greater detail with reference to the accompanying drawings, in which:- Pig. 1 is a sectional elevation of a preferred form of injector device according to the invention, D Pig. LA is a view, similar to Pig. 1, of a modified construction thereof, Pig. 2 is an end view, partly sectional, of the device shown in Pig. 1, ? 5 Pig. 3 is a section on the line Ill-Ill in Pig. 1, Pig. 4 is a schematic section of an alternative construction of an injector device according to the invention, Pigs.5 and 6 are plan and elevational section views illustrating the disposition of injector devices according to the invention in an internal combustion engine, and Pigs.7 and 8 are schematic illustrations of fuel injection systems incorporating injector devices 15 according to the invention.

Pigs.l, 2 and 3 show a preferred construction of an injector device according to the invention. The injector device has a body portion 1 having superposed transverse fuel and atomising air inlets 2 and 3 respectively. The ai-r inlet 3 communicates with a' chamber 4' in the lower por portion of the body 1 which, in turn, communicates with an open injector nozzle tube 5 dependent from the base of the body portion. The outlet end of the nozzle tube 5 terminates in a nozzle cap 6 having a flared outlet orifice 25 7. The outlet end of the nozzle tube 5 is bent through 90° with respect to its inlet end. The fuel inlet 2 communicates Φ with a. fuel chamber 8jwhich extends a fuel tube 9 passing through the air chamber 4 into the nozzle tube 5, terminating short of the outlet orifice 7 to define a mixing chamber 10 in the nozzle cap 6. The fuel tube 9 is at its inlet end is secured in the "body portion 1 by a threaded coupling 12. The clips 11 are so shaped that they offer little resistance to air flow through the nozzle tube 5.

In use of the injector device described above, metered liquid fuel is fed to the inlet 2 at a. low pressure, typically several tens of p.s.i. and passes from the chamber 8 into the fuel tube 9 from which it emerges into the mixing chamber 10. Low pressure air is fed to the inlet 3, typically at a pressure of a few p.s.i., and passes from the air chamber 4 into the nozzle tube 5 and in the mixing chamber 10 impinges on and entrains fuel emergent from the fuel tube 9, breaking the fuel stream, into globules and discharging the atomised fuel through the outlet orifice 7 at a. pressure substantially that of the atomising air. Passage of the fuel through the outlet orifice increases the atomisation thereof. As mentioned above, the clips 11 offer little resistance to air flow and do not impair effective atomisation of the fuel.

T e injector device shown in Pigs. 1-3 can be modified as illustrated by Pig.LA. The modification consists in the extension of the fuel tube 9 to a point closely adjacent the outlet orifice and the inclusion in the extension of a flow restrictor ¥, The outlet end of the fuel tube 9 is located so closely adjacent the outlet orifice 7 that diffusion of the emergent fuel stream jet is precluded, the ^et being directed into the outlet orifice. Apart from this feature, the injector device is identical to that shown in Pigs.1-3. An alternative construction of a fuel injector device in accordance with the invention is shown, diagrammatically , in Pi . 4. The device has a body portion 2L having 23 respectively. The air inlet 23 leads to a chamber 24 which communicates with an open injector nozzle tube 25 dependent from the base of the body portion 21. The nozzle tube 25 has an outlet orifice 26 and its outlet end is bent through 90° with respect to its inlet end. The fuel inlet 2 leads to a chamber 27 which communicates with the air chamber 24 via a tube 28 which preferably, as shown, is aligned with the inlet end of the injector nozzle tube 25 so that fuel emergent from the tube 28 is directed into the nozzle tube.

In use of this injector device, metered liquid fuel and atomising air are fed to the inlets 22 and 23 at similar pressures to those disclosed in relation to Pigs. 1-3. The fuel passes from the inlet 1 into the chamber 27 and thence via the tube 28 to the chamber 24.

Air fed to the inlet 3 passes through the chamber 24 into the nozzle tube 25, the speed of entry of air into the nozzle tube being sufficient to break up the fuel stream emergent from the tube 28 into small globules. The entrained globules pass along the nozzle tube 25 and are discharged through the outlet orifice 26 which serves to increase the atomisation of the fuel. The atomised fuel is discharged substantially at the atomising air pressure.

The injector devices described above are suitable for incorporation in a low pressure, continuous fuel injection system for an internal combustion engine. The manner of disposition of the injector devices , together with details of part of the atomising air supply system are illustrated ■ in Pigs . 5 and 6.

Pigs. 5 and 6 show the air inlet manifold 30 of an internal combustion en ine havin a. c linder block 31 manifold 30 has an air intake conduit 32 in which is disposed the throttle butterfly valve 33I the manifold le connected to the inlet passages 34 of the respective engine cylinders 35» one of which is shown in Fig. 6, by branch conduits 36 best shown in ig. 5· The air intake conduit 32 also has a port 32A located on the engine side of the throttle valve 33 in all positions of the latter. The injeotor devices 37 are disposed one in each conduit 36» the injector nozzles extending through the wall3 of the conduits 36 with their outlet orifices directed towards the respective inlet passages 34· The injector devices 37 are indicated in block outline and can be constructed either as shown in Figs; 1-3 or as shown in Fig. 4.

The fuel inlets of the injector devices 37 are connected via flow equalising restrlctors 38 to a fuel supply line 39 supplied from a fuel source in a manner to be described hereinafter. If injector devices of the type shown in Fig. 1A are used, then the flow restrictors 38 are not used, their function being fulfilled by the restriotors 5 forming part of the injector devices.

The air inlets of the injector devices 37 are connected to a common air supply line 40 supplied from an air compressor, for example', a diaphragm pump. The air line 40 incorporates a vacuum relief valve 41 having a lover chamber 42, forming part of the air supply line 40, containing an annular seat 43 open at one end to atmospheric pressure and having its opposite tnd normally closed by a resilient diaphragm 44. The valve 41 has an upper chamber connected to the manifold 30 so that the upper side of the diaphragm 44 is exposed to the manifold pressure A. The vacuum relief The construction of the injector devices is simple yet results in efficient atomisation and injection of fuel without relyin on the use of mechanical devioes for atomisation.

Pigs. 7 and 8 illustrate fuel injection systems ncorporating injector devices according to the invention, which are located in the manner illustrated in Figs. 5 and 6.

The fuel circuit of the system shown in Fig, 7 comprises a ring main having a supply branch 101 and a return branch 102, flo to the latter being controlled by a metering valve 103 operatle in response to engine inlet manifold pressure. A prira.i¾ pump 104A driven by an electric motor 104 supplies fuel from a tank 105 to a fuel line via a check valve 106 which prevents drainage of the fuel supply ring main during engine shutdown. From the check valve 106, the fuel passes to a relief valve 107 whioh is set to maintain a standing fuel pressure in the supply line 101 at a convenient level, e.g. 3 p.s.i. Surplus fuel is returned to the tanK 105 via the relief valve 107· From the relief valve, fuel passes to an engine driven impeller 108 which raises the fuel pressure to a level dependent on engine speed and passes the fuel through a check valve 109» which removes some or all of the standing pressure, to a pair of flow restrictors 110 and 111 which determine fuel flow in the branch 101. The supply branch 101 contains a fuel manifold connected hy flow equalising restrictors 112 to the fuel inlets 2 of injectors 113 of the type shown in Figs. 1-3. Only one such injector is shown in Fig. 7 hut it will he understood that one injector device is provided for each engine cylinder, as indicated in Fig. 5.

The downstream end of the fuel manifold is connected via the metering valve 103 to the return branch 102 of the fuel ring main. Fuel from the metering valve is passed to a collection chamber 114 via an air balance valve 115 from which it is pumped back to the tank 105 by a scavenge ■ pump 104B , also driven by the electric motor 104» Of the flow restrictors, 110 and 111, the former has a. resilient bellows responsive to atmospheric pressure to adjust fuel flow in accordance with atmospheric pressure. The restrictor 111 is normally closed but can be opened, either manually or automatically, by a control 115 to supplement fuel supply to the injector devices for cold starting conditions and warming up.

The metering valve 103 has a ported sleeve 116 rotatable in either sense by a follower 117 movable by a cam 118. The cam 118 is coupled to a piston 119 movable against a spring in a cylinder 120 in response to engine inlet manifold vacuum. The vacuum pressure is connected to the cylinder 120 by a conduit 121 leading to a diaphragm divided chamber 122, one compartment 123 of which communicates with the cylinder via a passage 124. The compartment 123 contains an annular seating member 125, normall closed at one end b a resilient diaphragm 126, D The compartment ' 123 communicates with the other side of the diaphragm 126 via a restriction 127 such that under steady and slowly chan ing pressure conditions in the compartment 123, the diaphragm 126 remains seated. Variations in engine 5 inlet manifold pressure cause movement of the piston 119 and correspondin · rotation of the ported sleeve 116 to vary the quantity of fuel bled to the return branch 102 and hence to vary the fuel supply to the injector devices. The diaphragm chamber 122 acts as an acceleration response device, ensuring that there is minimum lag between rapid opening of the engine throttle and consequent increase in fuel supply to the injector devices. In the event of a rapid throttle opening, the engine inlet manifold pressure quickly rises but there is some delay in transmission of this change to the cylinder 120 and consequently lag in the • piston 119 taking up a new equilibrium position. This is counteracted by the restrictor 127 which results in a marked pressure difference across the diaphragm 126 so that it becomes unseated exposing the cylinder 120 directly to atmospheric pressure, causing closing movement of the metering valve 103 and supplementing the fuel supply to the injector devices until pressure balance again exists across the diaphragm 126 with the piston 119 in a new equilibrium position. This sequence of operation is very rapid, normally taking place in under half a second.

The atomising air supply to the injector devices 113 is obtained from an engine operated diaphragm pump 128.

The output from the pump 128 operates a diaphragm switch 129 yrtiich controls operation of the electric motor 104 via a contact set 130. The contact set has three contacts, the lower two being closed in the dead engine condition. Opera centre contact and energises the motor 104 via the lower contact i Operation of the air pump 128 raises the diaphragm of the switch 129 so that the centre contact of the set 130 makes with the Upper contact, through which the motor 104 continues to he energised, is the diaphragm of the switch 129 continues to lift, the disc valve 131 of the switch 129 is unseated allowing air to pass to the air supply line 132 and via an air manifold 133 and conduits 134 to the air inlets of the injector devices 113.

For the purpose described with reference to Pigs. 5 and 6, the air line 132 incorporates a vacuum relief valve 135, indicated diagrammatically in Pig. 7 and preferably constructed and arranged as shown in Pig. 5. Thus, the lowest pressure that can arise inthe air manifold 133 is atmospheric pressure, but this pressure can rise to the supply pressure of the air pump 128. This pressure is preset in the injector devices and the tendency of the pressure to oppose and reduce fuel supply to the injector devices is counteracted by the feeding of the air pump supply to the relief valve 107 and the air balance valve 115, so that fuel flow throughout the .ring main circuit is opposed by the atomising air pressure.

It will be appreciated that the injector devices 113 could, if desired, be of the type shown in Pig. 4.

Pig. 8 shows an alternative fuel injection system incorporating fuel injector devices according to the invention. In describing this system reference will be made to Pigs. 5 and 6, the former being incorporated in Pig. 8.

The system shown in Pig. 8 includes a ring main fuel supply circuit having a supply branch 201 and a return 2 erable to the manner described with reference to Fig. 7.

A priming pump 204 feeds fuel from a tank 205 to an engine driven impeller 206, the output pressure from the pump 204 "being maintained at a convenient standing pressure "by a relief valve 207 which returns excess fuel to the tank 205. The impeller 206 is engine driven such that it raises the fuel pressure to a level dependent on engine speed. From the impeller, fuel passes via an engine starting and overrun control valve 208, an equalising restrictor and a gas/air separator 209 to the fuel manifold 39 (see also Fig. ) .

. The engine starting and overrun valve 208 comprises a valve member 210 having two seated positions in which fuel flow through the valve is shut-off. The position of the valve member 210 is controlled by engine inlet manifold pressure, applied to an inlet 211 and by fuel pressure across the impeller 206.' The valve 208 is operated by these control parameters such that under engine starting conditions, the valve member 210 is lifted from the lower seat and allows adequate fuel supply to the engine even though the pressure difference across the impeller 206 is small. Under normal engine running conditions, the valve member 210 is maintained intermediate the seated positions, allowing free fuel flow, but under conditions in which the engine runs fast with the engine throttle closed, the valve member 210 seats on the upper seating and again cuts-off fuel supply.

A barometric compensation valve 212 is connected between the gas/air separator 209 and the fuel return branch 202 (points A-A) and adjusts fuel flow to the manifold 39 to compensate for atmospheric changes.

The fuel manifold 39 is connected by flow equalising positioned as previously described with reference to Pigs.5 and 6. The injector devices can be of the type shown in Pigs.1-3 or that shown in Pig. 4. As previously mentioned, if the injectors are of the type shown in Pig. 1A, the flow restrictors 38 are omitted, their function being 38a performed by the restrictors 13.

Downstream of the metering valve 203 the fuel return branch 202 includes an air balance valve 213 connected to a collection chamber 214 from which surplus fuel is returned to the tank 205 by a scavenge pump 215. A vacuum relief valve 216 connected to the collection tank 214 ensures that the scavenge pump 215 does not starve the injector devices 37 of fuel.

The injector devices 37 are supplied with atomising air from a compressor 217 (Pig. 8) connected to the air supply line 40 (Pig. 5) which incorporates a vacuum relief valve 41, shown diagrammatically in Pig. 8.

The metering valve 203 has a valve member 219 operable in response to engine inlet manifold vacuum, connected to the valve 203 by conduit 220, to vary the fuel bled to the return branch 202. Thus, fuel supply to the injector devices is depen'dent upon engine y eoci (impeller 206) and engine inlet manifold vacuum pressure (valve 203). The vacuum relief valve 41 ensures that air pressure in the supply line 40 and in the injector devices 37 is at least atmospheric pressure. Since the air pressure in the injector devices opposes fuel flow therein, which could affect correct fuel supply to the engine, atomising air pressure is fed to the relief valve 207 and the air balance valve 213 so that balanced fuel flow conditions are obtained throughout the ring circuit. engine speeds. Atomising air is fed to the open injector devices, typically at a pressure of about 3 p.s.i. in which the fuel is atoraised by the air flow and injected continuously into the engine inlet ports. The injector devices have open nozzles, are simple in construction but are so designed that the air stream produces effioiont atomisation of the fuel and injection of fuel substantially at the atomising air pressure, the latter being prevented from falling below atmospheric pressure by a vacuum relief valve and thereby preventing the manifold vacuum interfering with fuel flo through the injectors* $he systems described with reference to Pigs. 7 and Θ are described in greater detail in British Patent Specification NO. 1098823. The control valve 208 (Fig. 8) is desoribed in British Patent Specification lio. 1098822 and features of the metering valves 103 (Pig. 7) and 203 (Pig. 8) are disclosed in greater detail in British Patent Specification Ho. 1098821»

Claims (6)

1. , 1. An internal combustion engine, haying a low pressure continuous fuel injection system including a plurality of injector devices ,having outlet orifioes disposed in the engine ;air intake manifold structure, each injector device includin a body portion having liquid fuel and air inlets, an air chamber communicating with the air inlet and with an injector nozzle defining the said outlet orifice, the fuel inlet communicating with a fuel tube so positioned that the fuel stream emerges from the fuel tube into air from the air chamber and is discharged through the outlet orifice, the fuel injection system further including means operable to supply liquid fuel to the fuel inlets of the injector devloes and air pump means for supplying air to the air inlets of the injector devices, and valve means operable to prevent sub-atmosp erio oonditions in, the air intake manifold structure giving tfise to sub-atmospheric conditions in the injeotor devloes.

2. An internal combustion engine having an air intake manifold structure and a low-pressure continuous fuel Injection system including a plurality of fuel injector devices having open outlet orifices disposed in the air intake manifold structure, each injeotor device including a body portion having liquid fuel and air inlets, an air chamber communicating with the air inlet and with an injeotor nozzle in one end of which is defined the said outlet orifice, the fuel inlet communicating with a fuel tube extending within the injector nozzle and terminating short of the outlet orifice whereby fuel emergent from the fuel tube enters into air from the air chamber and is discharged through the outlet orifice, the injection system further including means operable to supply fuel to the injector devices and air pump means operable to supply air at low pressure to the air inlets of the Injector devices, the connection between the air pump means and the air. inlets of the injector devices inoluding vacuum relief valve means operable to prevent sub-atmospheric conditions arising in the injector devices as a result of sub-atmospheric conditions in the manifold structure.

3. 5· An engine according to claim 2, in which in each fuel injector device the fuel tube includes a flow restric-tor device looated adjacent the outlet end of the fuel tube, the flow restrictors of the injector devices forming fuel flow equalising restrictors.

4. An engine accordin to claim 2 or claim 3, in which each injector devloe includes a device within the injector nozzle and external of the fuel tube which locates the fuel tube in spaced relation with the nozzle device and offers low resistance to air flow.

5. An engine according to claim 4, in which the locating device of each injector device is a removable clip device.

6. An engine according to any one of the preceding claims, in which in each injector device the fuel and air inlets are superposed with the fuel inlet uppermost. For the Applicants DR. REiNHO D COHN ND PARTNERS'