CA1073292A

CA1073292A - Fuel injection apparatus

Info

Publication number: CA1073292A
Application number: CA269,621A
Authority: CA
Inventors: Barrie J. Martin; Samuel S. Hall
Original assignee: Plessey Handel und Investments AG
Current assignee: Plessey Handel und Investments AG
Priority date: 1976-01-14
Filing date: 1977-01-13
Publication date: 1980-03-11
Also published as: FR2338396B1; BR7700265A; ES455033A1; IT1077855B; SE7700312L; FR2338396A1; US4167158A; DE2701422A1; JPS5289726A

Abstract

ABSTRACT OF THE DISCLOSURE:

Fuel injection apparatus comprising a fuel injector and a surface which can be vibrated, the apparatus being such that in operation the injector is vibrated to inject atomized fuel towards the surface which is also vibrated so that any particles of insufficiently atomized fuel can hit the vibrating surface and be further atomized.

Description

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This invention relates to fuel injection appara-tus Acccrdingly, this invention provides fuel injection apparatus comprisi~ a ~uel inject~r, first vibrator means for vibrating the injector, a plate member, and second vibrator means ior ~ribrating the plate member, the plate member being sufficientl~ thin that when it is vib~ated a plurality of vibration anti~nodes are set up in the piate member with the vibration anti-nodes acting substantially at right angles to the plate member, and the apparatus being ~uch that in operation ~he injector is vibrated by the first vibrator means to inject atomised fuel towards the plate member which is vibrated by the se~or.d vibrator means so that any particles of insufficiently atomised fuel can .strike the vibrating plàte member and be ~urt'ner atomised.

Yarious types~of injector can be used in the present - i~ve~tion. P~eferably, the injector has a ball valve effective to shut of the fuel flow ~rhen the injector is not being vibrated.
Exa~ples of appropriate injectors that may be used are described in our ~ritish Patent Numbers 1420313, 141553~ and 1471916 ~d in OUL- ~anadian Patent Applications Numbers 246024, 24~23, 231486 and 259~42.

., ` rreferably, the first vibrator means is a piezoelectric device 2n~ e seconcl vibrator means is also preferably a piezoelectric device. ~he first and second vibrator means ma~ also be other devices s~lch f`or example as a magretostrictive device. If desired, the second vibrator means and the plate may be attac~ed -- .

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Z~2 to a device that can be used as a vi~rator~ fuel injector.
In this case, the vibrating device (herelna~ter sometimes referred to as a surface ~to~iser) ~11 be vibra~ted not to inject fuel ~ut to merely cause the plate member to vib~ate. ~he plate member can be arran~ed aro~und the neck of the surface àtomiser, i.e~ iD
the form cf a washer, with the piezoelectri.^ device belng attac~ed to a bcdy portion of the surface atomisèr.

As the thin plate member vibrates, a plural~t~ of the vi`oration anti-nodes.are formed on the plate memher between its centre and its ed~es. A single vibrati~g device car thus be used to provide a large ~ibrati.n~ surface havl~g a plurality o~ areas o~ maximum vibration. i.eO the anti-nodes, withou~ using too much power.

In cre e_bodiment of the invention, the ~ue injection appar~tus is modified to provide apparatus ~or mete~ing f~el and air for - an engine, the appar~tlls . then includ~ng air fiow measuring mearls which measur2s at least a part of the flowCof air for the engine and which generates an electr c&l output that is propo~tio~al to the measured . . .

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~ 3Z92 air flow, and control means which receives the output from the air flow measuring m~ans and which generates elec~rical output signals which vary in dependence upon the received signals, the apparatus being such that in use the ou~put signals ~rom the control means are used to control the period of vibration of at least the injector. Preferably, the output signals from the control means are used to control the period of vibration of the injector and the surface.

The apparatus of the invention ~an be effective for providing an optimum amount of fuel and air for an engine under varying conditions. Precise control is achieved by utilising the air flow for the engine.
More specifically, the use of the air flow measuring means enables a continuous check on the condition of ~he air ultimately destined for an engine. The data obtained by the air flow mRasuring means can then be fed to the control means and the control means can then appropriately control the injection of fuel into the 6e~
air. The presence of the F~rf~cc ~hich can be vibrated ensures that the injected fuel is in a finely atomized form so that ilt can be fully mixed with the air.

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The apparatus of the present invention may be used for various types of engines such for example as two and four stroke internal combustion engines.

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Usually the GUtpUt from the air flow measuring means will be a series of eLectrical pulses of a frequency determined by the air volume flow through the air flow measuring means. Preferably, the air flow measuring - 5 means is a vortex shedding flow meter having a pressure or a temperature transducer. Such a vortex shedding flow meter may have a bluff body which causes the air passing the bluff body to form vortices alternatively from either side of the bluff body~ The oscillation lo within the air flow can then be sensed by the pressure or temperature transducer. Other types of apparatus can be used if desired such for example as air flow measuring means which gives an output dependent upon temperature changes caused by varying air flow. Still further, the air flow measuring means may be a fluidic dev;ce, e.g. a fluidic switching device in which t~e air switches between two channels.

The air flow m~asuring means may be arranged in the main air duct leading to the engineO In this case, all the air for the engine is measured. Alternatively, the air flow measuring means can be arranged in a by-pass air duct so that only a proportion of the air for the engine is measured~ In this lat~er case, the fuel is pre~erably injected into the main air duct but, ir desired, it can be mixed with the air in the by-pass ' ` ' ;

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duct and then this mixture can be combined in the main air duct with the remaining flow of air destined for the engine prior to the intro-duction of the fuel/air mixture into the engine.
Advantageously, the injector and the plate member are both positioned in the vicinity of an inlet manifold for an engine. Since the fuel injector and the plate member are positioned in the vicinity of the inlet manifold, the fuel does not have to pass along an appre-ciable length of an air induction pipe leading to the inlet manifold.
It can sometimes be disadvantageous to inject the fuel in the air induction pipe an appreciable distance from the inlet manifold since the fuel will obviously wet the walls of the induction pipe. When the engine is being driven and power is no longer required, the operator will release the throttle to cause the engine revolutions to subside and a correspondingly smaller amount of fuel to be inject-ed from the injector. This may often cause a suction effect at the inlet manifold which can act to suck the petrol off the walls of the induction pipe and into the engine at a time when this additional fuel is not required. By appropriately positioning the injector and the plate member near the inlet manifold, this disadvantageous effect can be substantially prevented.

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The control means may be a digital computer device.
An analogue computer device may also be usedr Preferably, the control means actuates the injector on a predetermined pulse width per signal.

The control means may include a monostable device effective to receive the pulses from the air flow measuring means and to generate pulses of an appropriate predetermined pulse width. The monostable device may have a fixed multiplication or division factor so that it is able to generate output pulses which are in a fixed ratio to the input pulses. The width of the pulses can be altered to enable the air/fuel ratio either to be kept constant when the air temperature may be causing variations in the air mass flow, or to be varied (e.gO by using the engine throttle) to enable the engine to respond to transient demands made upon it. The air/fuel ratio can be enriched for engine accelerations and weakened for engine decelerations and on over-run. The air/fuel ratio can also be adjusted for other varying engine conditions such for Pxample as when the temperature of any coolant for the engine varies or when the output of any battery associated with the engine drops too low. If desired, the apparatus of the invention may also include an oxygen sensor which may be located in the exhaust duct from the engine. This oxygen sensor may provide a feedback signal from the engine exhaust ~- 7 -. , .
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-~a~3z~2 to the control means and may be effective to ensure that the fuel supplied to the engine is correct to maintain a desired optimum air/fuel ratio, e.g. 15 by mass.

The ~utput pulses from the monostable device may be fed to an oscillator which is effective to ac~uate the fuel injector and causP it to vibrate. Various types of oscillator and associated circuitry may be utilised and an example of one suitable oscillator and associated cicuitry is described in our co-pending Canadian patent application No,. 261479.
A solenoid operated valve may also be employedO
If desired, the surface atomizer may be similar to or the same as the fuel injector but provided with a surrounding surface which can be used for breaking up any particles of insufficiently atomized ~uelO This surface atomizer can also be caused to vibrate by the same type of oscillator and associated rircuitry used for vibrating the fuel injector.

It may be necessary due to practical problems such ~or example as slow injector valve closing or poor metering accuracy at low pulse widths, or the ratio o injector pulses to air flow meter pulses to be varied a~ predetermined flow meter rates and to have the ~ulse 25 width varied accordingly. For examp}e, 1 injector pulse . `

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per induction stroke of an engine at idle conditions may require a 1 millisecond pulse on the injector. At high loads, 1 induction stroke may requlre 5 of the 1 millisecond pulses. At this point, the control means could be set such that it changes the ratio from 1:1 to 1:5 with the pulse width increased to 5 milliseconds, provid-ing the flow from the injector is proportional. If the flow from the injector is not proportional, then the pulse width is ad~usted and not the ratio.
Embodiments of t~he invention will now be described solely by way of example and with reference to the accompanying drawings in which:
Figure 1 shows first apparatus in accordance with the invention;
Figure 2 shows second apparatus in accordance with the - invention;
Figure 3 shows third apparatus in accordance with the invention;
Figure 4 shows fourth apparatus in accordancP with the invention;

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~0~3Z~2 and Figure 5 is a top plan view of the apparatus shown in Figure 4.

Referring now to Figure 1, there is shown apparatus - 5 2 for metering fuel in accordance with air in an air duct 4 leading to an e~gine 6. The apparatus 2 romprises air flow measuring means 8 which is arranged directly in the duct 4 and which therefore measures all of the air flow for the engine 6. The measuring m~ans 8 causes lo an oscillation of the air to be set up with the frequency of oscillation being proportional to the air flow rate.
These oscillations are converted into electrical pulses by means of a pressure or flow sensitive element forming part of the measuring means 8. The measuring means 8 thus generates electricàl pulses of a frequency proportional to the measured air volume flow.
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- At cranking speed, the air being inspired into the enginQ may not be of sufficient velocity to enable the air flow measuring means to work adequatelyO At these conditions the injector may be commanded by the ~gnition pulses of the engine. When the output, e.g.
air pulses, from the air flow measuring means are of a sufficilent frequency, the electrical circui~ will _ 10 -:
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sense this and will change the command from the ignitionpulses to the air flow measuring means.

The output from the measuring means 8 passes along line 10 to control means 12~ The control means 12 is also fed with information such for example as acceleration of the engine via line 14, air temperature in the duct t~ 4 via line 16, battery ~utput voltage ~ i~c ~, and engine coolant temperature vi~ liLle 19. The air and engine co~lant tempera~ures can be measured by appropriately positioned thermistors. When the engine is cold, more fuel may be needed, thus providing a "choke" function.
When the vehicle is accelerating, more fuel may temporarily be needed to ensure freedom from engine flat spots.
This may be accomplished by a throttle movement rate sensor, which ensures that the fuel:air ratio is increased whenever the vehicle driver demands an acceleration by causin~ appropriate electrical signals to pass along the line 14.
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The control means 12 is thus fed with information - 20 which is relevant to the proportion of fuel to air needed by the engine. The control means 12 then generates an appropriate train of square pulses of predetermined width along line 18 which is effective to cause injection of exactly the right amoun~ of fuel into the duct 4 from an injector 20. The width o ~he pulses is primarily .

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determined by the air flow rate in the duct 4, but modified by the above mentioned control variables such for example as engine acceler-ation and air and engine coolant temperatures.
The width of the pulses may also be modified by the option-al presence of an oxygen sensor 11 arranged in the exhaust duct 13 of the engine 6. The oxygen sensor 11 monitors the oxygen content of the exhaust and is effective to provide a signal in line 15 indica-tive of the air/fuel ratio at which the engine is operating. This signal is fed via the line 15 to the control means 12 and may serve to specify the required air/fuel ratio. During acceleration and deceleration of the engine 6, the signal from the oxygen sensor 11 will normally be over-ridden by the throttle movement sensor so that temporary changes in the air/fuel ratio are permitted. This ensures that full driveability of the vehicle is maintained when acceleration is demanded and that minimum fuel is provided during deceleration demands.
The injector 20 is a vibratory type of injector and the line 18 is connected to second vibration means in the form of a piezoelectric crystal 22. The electric signals actuate the piezoelec-

2~ tric crystal 22 and the injector is caused to vibrate. Fuel injectedby the injector when it lS being vibrated is in the form of a spray.

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;tzgz The vibrations, which are prefera~ly ultrasonic, are magnified in the horn portion 24 of the injector 20. Usually the tip 26 of the horn portion 24 will have an orifice therein which is closed by means of a non-return valve. Preferably the non-return valve is a ball valve. When a ball valve is used, it is preferably positioned in a separate housing in the nozzle tip 26 and this housing may be provided with various apertures for causing the fuel to swirl in the housing and also for causing the ball valve to be pushed by the fuel in the housing towards the nozzle orifice.
10 - It will be seen from Figure 1 that positioned adjacent the nozzle 20 and arranged in the duct 4 is a surface atomizer 28. The surface atomizer 28 is provided with a thin flat collar or plate 30 which receives any insufficiently or non-atomized fuel from the injector nozzle 20. In other respects, the surface atomizer 28 may be substantially the same as the injector nozzle 20 although it will of course not be used for injecting fuel. The surface atomizer is caused to vibrate, usually in synchronisation with the nozzle 20, by the control means 12 which is connected by line 32 to a piezoelectric crystal 34 which constitutes a-first vibration means.
As the surface atomizer 28 is vibrated, any insufficiently or non-atomized fuel which strikes the plate 30 is broken up under the impact. By applying . . ' , "'.

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the vibrations to the centre of the plate 30 such that there is an impedance match between the llorn and the pla-te 30, the plate 30 will vibrate with a plurality of vibration anti-nodes and such that an appreciable area of the plate 30 will exceed the level of amplitude at which atomization of fuel on the plate 30 takes place. The vibrating anti-nodes will extend between the centre and the edges of the plate 30. The edge of the plate 30 will be at a vibration anti-node and this ensures that any fuel in the centre of the plate 30 that runs towards the edges of the plate and is not vibrated still has the chance of being vibrated right at the edge of the plate 30.
If desired, a plate member can also be provided on the nozzle 20 so that fuel particles can be thrown backwards and fon~ards between the plate members until sufficient atomization of the fuel has been achieved.
The fully vapourised and correctly mixed fuel/air mixture can then pass through a normal butterfly throttle 36 to the engine 6 for combustion.
Referring now to Figure 2, similar apparatus to that shown in Figure 1 has been illustrated and similar parts have been given the same reference numeral. In ~.

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the embodiment shown in Figure 2, it will be seen that the air flow measuring means ~ is not positioned in the main air flow duct 4 but is positioned in a by-pass duct 50. The air fl~ measuring means 8 thus measures a proportion of the air ultimately destined for the engine 6.

The injector 20 and the sùrface atomizer 28 are also positioned in the duct 50. The full amount of fuel needed for the engine 6 is injected by the injector o 20 into the air in the duct S0. The presence of the surface atomizer 28 ensures that the fuel is fully atomizedO
The mixture of fuel and air is then passed back into the main duct 4 at orifice 52 and the correct air/fuel mixture then passes past the butterfly throttle 3~ to the engine ~. A restrictor 33 may optionally be employed in the duct 4 for ensurin~ that there is a constant ratio of the air 10w through the main duct 4 and the by-pass duct 50~

: Referring now to Figure 3, similar apparatus to that sho~rn ~n Figures 1 and 2 has been illustrated and similar parts have been given the same reference numeral. In the embodiment shown in Figure 3, it will be seen that the air flow measuring m~ans ~ is positioned in the by-pass duct 50 ~ut the injector 20 and the surface . : . ...... , .... , ; ~ , : . ' '. . ' atomizer 28 are positioned in the main duct 4.
In the embodiment of Figure 3, it may be desired to obtain a ratio of 16:1 or 17:1 of air mass:fuel. Also, the pulses passing along line 18 for actuating the injector 20 may be 1 millisecond pulses at engine tick over speeds.
In Figure 3, it will be noted that the control means 12 has been formed as two separate units comprising a monostable device 12A and an oscillator 12B, e.g. of the type described in our co-pending patent application No. 261,479 filed September 17, 1976.
The monostable device 12A-is fed with electrical pulses from the air flow measuring means 8, the frequency of the pulses being determined by the mass of air in the bypass duct 50. The monostable device 12A
is also fed with information that can affect the fuel/air ratio of the combustion mixture for the engine 6. This information can be : information on throttle movement via line 14, air temperature in the duct 4 via line 16, battery output voltage via line 17 and engine coolant temperature via line 19. The monostable device 12A is effective to digest the information received and to generate a train of pulses of predetermined width and of a frequency which fires the oscillator 12B for the required periods of time. The injector 20 injects fuel for the required periods of time consequent ~ 16 -: . . . . . .
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upon being activated by the oscillator 12B.
When the systems illustrated in Figures 1 to 3 are operated without the oxygen sensor 11, electrical shaping circuits will preferably be included in -the control means to ensure that the desired fuel quantity is supplied :irrespective of non~linearities within any monitoring instruments or the engine 6.
Referring now to Figures 4 and 5, there is shown an inlet manifold 102 having inlet pipes 10~1, 106, 108, 110, leading to an engine 111. Arranged in the inlet manifold 102 is an air induction pipe 112. In the induction pipe 112 and also in the vicinity of the inlet manifold 102, is arranged a fuel injector 114 and surface atomizer means 116 having a surface 118 which can be vibrated.
The injector 114 comprises second vibration means in the form of a piezoelectric ceramic device 120 which can be activated by an eleetrical current passing along lead 122. Activation of the deviee 120 causes the injector 114 to vibrate and a ball valve (not ; shown) inside the injector 114 to be moved off its seat (not shown) to allow fuel to be injected as shown by thè dotted lines 124. Small ~inely divided partieles of fuel are carried away by the air passing along the inlet duct 112 to the engine 111 via the .
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inlet pipes 104, 106, 108, 110. Large particles of fuel which are not so carried away by the air strike the plate 118.
The plate 118 is caused to vibrate by virtue of the fact that the device 116 is being vibrated by first vibrator means in the form of a piezoelectric ceramic device 126 energised from a lead 128, the plate 118 being sufficiently thin to allow a plurality of vibration anti-nodes to be set up in the plate.
The large particles of fuel hitting the plate 118 are thus pro-jected back into the main air duct after being further broken up by the impact with the plate 118.
It will be noticed that the inlet pipe 112 is provided with an inward restriction 130 in effect forming a Venturi at ; 132 between the restriction 130 and the edges of the plate 118.
Air passing along the pipe 112 past the butterfly 134 is caused to increase in velocity at this point to enable it more efficiently to pick up fuel from the injector 114.
Since the fuel is not injected in the pipe 112 remote from the manifold 102, there will be no fuel in the pipe 112 and it will thus be substantially dry. The fuel will only wet the ~nlet manifold walls. Thus, ~ '- 18 --. : :, ~ : .:

~ Z~2 when the engines revolutions are s~ddenly cut back, any suction created in the inlet mkaniold 102 will not cause fuel to be sucked off the walls of the pipe 112, as would be the case if the fuel were inject~d in the pipe 112 remote from the manifold 102.

It is to be appreciated that the em~odiment of the invention described above has been given by way of example on]y and that modifications may be effec~ed.
Thus, for example, a different type of surface atomizer 28 or 116 could be employed. Also, the inlet manifold 102 in ~igures 4 and 5 could be heated, for example by means of water, to facilitate fuel atomization.
Further, a di~ferent type of injector 20 or 114 could be utilised. Thus, for example~ the injector could be electro-magnetically operated or could be one without a ball valve. Although only one injector has been shown, more ;njectors could be employed if desired. For example, in the case of a V-~ engine, two injectors could be employed, each feeding an intake manifold for four cylinders~ Still further a low fl~w rate injector could be employed for one part of an engine cycle and a high flow rate injector could ~e employed in the same system but for a different part of the engine cycle.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Fuel injection apparatus comprising a fuel injector, first vibrator means for vibrating the injector, a plate member, and second vibrator means for vibrating the plate member, the plate member being sufficiently thin that when it is vibrated a plurality of vibration anti-nodes are set up in the plate member with the vibration anti-nodes acting substantially at right angles to the plate member, and the apparatus being such that in operation the injector is vibrated by the first vibrator means to inject atomised fuel towards the plate member which is vibrated by the second vibrator means so,that any particles of insufficiently atomised fuel can strike the vibrating plate member and be further atomised.

2. Fuel injection apparatus according to claim 1 in which the first vibrator means is a piezoelectric device, and in which the second vibrator means is a piezoelectric device.

3. Fuel injection apparatus according to claim 2 in which the piezoelectric device constituting the second vibrator means forms part of a vibrating device having a body portion and a neck portion the piezoelectric device being attached to the body portion and the plate member being arranged around the neck portion.

4. Fuel injection apparatus according to claim 1 including air flow measuring means which measures at least a part of the flow of air for an engine and which generates an electrical output that is proportional to the measured air flow, and control means which receives the output from the air flow measuring means and which generates electrical output signals which vary in dependence upon the received signals, the apparatus being such that in use the output signals from the control means.

5. Fuel injection apparatus according to claim 4, in which the air flow measuring means is a vortex shedding flow meter.

6. Fuel injection apparatus according to claim 5 in which the flow meter includes a pressure transducer.

7. Fuel injection apparatus according to claim 5 in which the flow meter includes a temperature transducer.

8. Fuel injection apparatus according to claim 4 in which the control means includes a monostable device effective to receive the pulses from the air flow measuring means and to generate pulses of a predetermined width, and in which the control means also includes an oscillator for receiving pulses from the mono-stable device and for actuating the fuel injector.