Note: Descriptions are shown in the official language in which they were submitted.
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Ultrasonic Injecking M~thod
and Iniection Nozzle
Technical Field
This invention relates generally to the art of ultrasonic
injection for atomizing liquid material, and particularly to
an ultrasonic injecting method and nozzle suitable for use
on a fuel injecting val~e for intcrnnl combustion engincs
such as diesel engines, gasoline 0ngino~ and gas turbine
engines, and external combustion en~J 1108 such as l~urners for
boilers, heating furnaces, heatincl al)paratus and the lik~,
and also for a spray head for dryin~ L~n(l produc,ing powdered
medicines. While this invention is u~eful as an injecting
nozzle or apparatus for atomizing and injecting liquid
material in various applications as described above (the
term "liquid material" is intended to mean not only a liquid.
such as liquid fuel but also various solutions or suspensions
such as liquid for producing medicines as well as water or
other liquid fGr use with a humidi.Ey;lng or spraying apparatus),
the invention will be described heroJ~ ftor wlth re~pect to
a fuel injecting nozzle particularly Lor use with internal
combustion engines such as diesel ~ln(l qasoline engines.
Background-Art
Various attempts have hereto~ore been made to supply
liquid fuel in atomized form into ~ combustion or precombustion
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ehamber of an interllai c~mbustion engine such as diesel or
gasoline engine in order to reduce soot and enhance fuel
economy. One of the mo~t common methods is to inject liquid
fuel under pressure through the outlet port of an injection
nozzle. In such injeetion it is known that atomization of
liquid fuel is promoted by imparting ultrasonie vibrations
to the liquid fuel.
There have llore~o~ora beèn developed two mechanisms for
atomizing liquid by u~r.lsonic waves - (1) the cavitation
mechanism and (2) t]lo w;lvo mechanism. The cavitation
m~chanism is unsuiL;~ e rOr application to an injection
valve because of diEIic~llty in controlling the degree of
atomizing. The wave meehanism includes the eapillary system
and the liquid film system. In the eapillary system an
ultrasonic vibrating element has a capillary aperture formed
therethrough. Liquid fuel is introduced through the inlet
port of the capillary aperture while the ultrasonic vibrating
element is subjected to vibration, whereby the liquid fuel
is spread through the outlet of the capillary aperture in a
film form over tho ~o~tom surface of the vibrating element
and then injeeted in nn atomized state. In the liquid film
system, an ultrasollle v~l)rating element is ~ormed on its
forward erld with a p~ltloll flared as in the ~orm of a poppet
valve. Liquid fuel is clelivered to and spread over the face
portion in a film ~oral.llld then injected in an atomized state.
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As is understood from the foregoing, it has been
heretofore considered tha~ the mechanism by which l~quid
is atomized by means of an ultrasonic vibrating element is
based on either cavitation or wave motions caused after the
liquid is transformcd to Eilm, and particularly that wave
motions in film are indispensably required to efect atomiza-
tion of liquid in a Iilrllo quantity. Accordingly, the
arrangemcn~ as de~crlbecl above have been hitherto proposed.
However, in ac~ual1ty the injection nozzles hitherto
proposed have so smal:L capacity for spraying that they are
unsuitable for use as an injection nozzle for internal
combustion engines such as diesel or gasoline engines which
require a large amount of atomized fuel.
In an attempt to accomplish atomization of liquid fuel
in a larc~e quantity, 1l~-1 inventors of this application have
conducted extensivo ro~ rch and experiments on the mechanism
by which liquid is ul~r~lsonically atomized as well as on the
conEigur;ltion of tl~e ultr~sortic vibrating element and found
out that it is possil~lo ~o effect atomization of liquid fuel
by an atomization meclla~ism distinct from the atomization
mechanisms as described hereinabove. More specifically, the
inventors have discovered that liquid fuel may be atomized
in a large quantity from an edged portion ~ormed at an end
of an ultrasonic vibrating element by delivering liquid fuel
to and past said edgod portion in a film state. This
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invention l~;IS ~eell d~!Ve l~l>ed on the basis of such novel
discovcry.
Summary o~ the InvellLIo
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Accordin~ to llli~ Irlvcntion, an ultrasonic injection
nozzle i~ uLovid(~(l wlll~h comprises an ul~rasonic vibration
gcnerating mcans a~ vilJrating element connectcd to said
vibration generating means so as to be vibrated thereby,
said vibrating element being `formed at its forward end with
an edged portion to and along w~ich a liquid material is
delivered to be atomized.
In a preferred enlbodiment of this invention, the
ultrasonic vibration ~lenerating means is always in operation,
hence the vibratin~ olelllent is continuously vibrated while
liquid material is interll~ittently ~ed to the vibrating
element, thcreby cJil~ ting the time lag involved in
illltiatioll of vil)ra~ ll, the defect of the conventional
ultraso~ injec~iollllo;:zle in which the vibrating element
is vibrated only wl~ell injectlng liquid material.
Further, in a pLeferred embodiment of the invention,
the vibrating element having the edged portion is so arranged
as to be located ad~acent the outlet port of the lnjection
nozzle, whereby a vcry compa~t ultrasonic injection nozzle
m~y be providod.
In a~lditioll to lll~ illtermittent injection nozzle as
describc~ clbove, tlle l~r~l,cnt invention may be applicable to
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continuous burning such as a burner and also to a spraying
apparatus for spray drying to produce powdered medicine.
Accordingly, a primary object of this invention is to
provide an ultrasonic injecting method and injection nozzle
capable of atomizing a liquid material in a amount on an
elther intermittent or continuous basis.
Another object of the invention is to provide an
ultra~onic injecting mc~hod and injection nozzle for use on
internal combustion Ingines such as a diesel engine, gasoline
engine, gas turbine cngine and the like, or for use on
external combustion engines such as burners for boilers,
heating furnaces, heating apparatus and the like for atomizing
liquid fuel in a uniform manner and in a large quantity to
thereby provide for attaining complete combustion in a short
tlme, resulting in preventing emission of soot as well as
improving the ~ucl o~o~lomy.
Another obj~ct o~ the invention i5 to provide an
ultrasonic injecting m~thod and injection nozzle for use on
internal combustion orlgines which are capable of not only
atomizing li~uid in a large amount but also atomizing liquid
even at a low flow rat~ at which the prior art was unable to
effect atomizing, to thexeby enhance fuel efficiency.
Still another object of the invention is to provide an
ultra~onic injecting method and injection nozzle for use on
an internal combustion engine which provide for reducing
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soot and improving fuel economy and which is capable of
continuous operation and highly suitable for pxactical use.
Still anothcr objoct of the invention is to provide
an ultrasonic injectln(l method and injection nozzle which
are capable of fuel ln~cction with no time~lag,
Yet another objoct is to provide an ultrasonic injecting
method and injection nozzle which are useful not only for
spraying a medicine producing solution ox suspension to dry
the materials contained therein'as for producing powdere,d
medicine but also for humidifying a room or material.
Another object of the invention-is to provide an
ultrasonic injccti~ mQthod and injection nozzle which can
make the constructioll compact in size.
Brief Description of tllo Drawings
These and other ol)~octs and features of the present
invention are morc fulJ.y disclosed in the following specifica-
tion, reference beinc3 had to the accompanying drawlngs, in
which: '
Fig. 1 is a fractional cross-sectional view of the
ultrasonic injection nozzle a~cording to the present
invention;
Figs. 2 and 3 are fractional front views of alterna~e
forms of the edged`portion at the forward end o the
vibrating element;
Fig, 4 is a ~raa~lonal enlarged view illustrating the
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operation of the edged portion; and
Fig. 5 is a front: view of the hollow needle valve.
Preferred Forms of the lnvention
An ultrasonic illjcction nozzle according to this
invention will be cle~crlbed in details with reference to
the accompanying drawing~.
Referring to Fi~. 1, the ultrasonic injection nozzle
1 according to this invention includes a generally
cylindrical elongated housing 4'having a central bore 2
extending centrally therethrough. Threaded to the external
thread 6 on the upper portion of the housing 4 is the lower
mounting portion of a vibrator holder 8 which has a through
bore 12 ~xtendin(3 c~3lltrally therethrough coaxially wi.th
and in longitudinal ali~3lunent with the central bore of the
housing 9.
A vibrating elel~ or vibrator 14 is mounted in the
tl~rough bore 12 of ~h~l vl~rator holder 8 and the central
bore 2 of the housincl 4. The vibrating element 14 comprises
an upper body portion 16, an elongated cylindrical vibrator
shank 18 having a diameter,smaller than that of the body
portion, and a transition portion 20 connecting the body
portion 16 and shank 18. The body portion 16 has an enlarged
diameter collar 22 therearound which is clamped to the
vibrator holder 8 by an shoulder 24 formed on the inner
periphery of the vibrator holder 8 adjacent its upper end,
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~L28;~ 7
and an annular vlbrator retainer 30 fas~ened to the upper
cnd face of the vil~r.l~or holder 8.
The shank 18 of tho vibrating element 14 extends
downwardly or outwardly beyond the housing 4. The forward
end of the vibrating element 14, .that is, the forward end
of the shank portion 18 is formed with an edged portion 32
as will be described in.more details hereinafter. A hollow
needle valve 34 is mounted for slidable mounted in that
portion of the vibratlllg element 14 extending beyond the
housing 4.
The hollow n~edle valve 34 is generally of cylindrical
shape, and compriso~ all upper reduced-diameter portion 38
~djacent its upper erld, il central large-diameter portion 38,
a tapered portion 40 sloping from the large-diameter portion
38, a small-diameter portion 42 connected to the tapered
portion 40, and a tapered forward end portion 44 sloping
from the small-diameter portion 42~ The extreme end of the
tapered forward end portion 44 is disposed adjacent the edged
portion 32 of the vibrating element 14. On the other hand,
the upper reduced-diamcter portion 36 of ~he hollow needle
valve 34 extends upw~lrdly beyond an annular shoulder 46
extendillg radially inw.~rdly from the lower end portion of
the housing 4.
The hollow noocll~ valve 34 is housed in the needle
valve holder 50 which 1~ detachably secured to the housing
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w,L~ lt~`L .l~l,Lt~3t ~ U ~c~tlYlt'l.LI~c~ tJI~ wn,L'I ~e
lt)lllI,~ Jl, Wlllt~ . p~.t~I~Jln~O G~l 11 ;In tu~rl ~o~ 3cLt~
wL~ lr~ l llt.L~?~: lJt)lll. '~t) ~P ~ lOU!3.ttll,~ 4~
lc?~ lv~ l~t~ 0 .Ls~ r~ 3 ~ 3~ L'
k t~ ~ k l~ .r~ x l~o~ l 5 ~1 C3 .l~ I 'L~
v~lv~ l~t~ lt~ rlr~r~ L~ p 7~ r~ y
C~Stl1Y c~p~rl:L~ J Wl~ 3 aOI~ k~ L~Il n .L1~ O~'Lr1k po,r~,
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76 formed through tllc walls of the needle valve holder 50
and the housing 4, roflp~ctively.
A compression ~p~ tJ 80 is disposed in an annular
space defincd betwcell tllo peripheral wall of the central
bore 2 in the housing 4 and the outer periphery of the
vibrator shank 18. The lower end of the compression spring
80 abuts against the top.end face of the upper reduced-
diameter portion 36 of the hollow needle valve 34 by means
of an annular spring retainer 82 while the upper end of the
spring abuts against the bottom surface of an injection
pressure regula~ing mcmber 84 which is a cylindrical member
disposed in the spacc bo~ween the peripheral wall of the
central bore 2 in ~h~ housing 4 and the outer periphery of
the vibrator shank lU atlcl threaded to the inner periphery
of the housing 4. ~lul~, the pressure on the needle valve
34 may bc adjusted ~y rotating the injection pressure
regulating member 84 re.lative to the housing 4.
The operation oE th~ ultrasonic injection nozzle 1 will
now be described below.
In operation, liquid fuel is introduced through the
fuel inlet port 70 and suppl.ied through the fuel inlet
passage 68 and fu 1 ~upply passage 66 into the fuel reservoir
64 which is c1Osed-l~y tl~e tapered portion of the hollow
needle valvc 34 ur~e(l downwardly by the spring 80.
Consequontly, the pro~sLIre in the reservoir 64 is built up
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as it is continuously ~ Jlied with liquid fuel. When the
pressure in the fuel reservolr 64 reaches a certain level,
the hollow needle valve 34 is caused to move upward against
the biasing force of the spring 80.
The upward movement of the hollow needle valve 34 causes
the fuel reservoir 6q to be opened to the fuel supply passage
62, which is thus suE)~lled with the liquid fuel. From the
fuel supply passago ~2, tlle fùel is delivered to the edged
portion 32 formed ~ll th~ ~orward end of the vibrating element
14.
The cdged portln~ of the vibra~ing element 14 may be
in the Eorm of a s~a.lrca~e including three concentric steps
having progressively lechlced diameters as shown in Fig. 1,
or may comprise two ~ I.lve steps as shown in Figs. 2 and 3.
Whatever configuration it may be, it is important that the
edged portion be formed around its outer periphery with an
edga or edges. While tlle edged portion 32 as shown in Figs.
1 to 3 i~ oE a st:epped ~ol~figuration having progressively
reduced dlallloters, ll nlay be o~ a configuration having
progres4ively incre~8~d d~ametcrs or progressively reduced
and then increased ~ maters. Further, as shown in Fig. 4,
the geometry such aH tl~ width (W) and height (h) of the
s~ep are ~uch that ~ho ~dge may act to render the liquid
fuel filmy and to dam t~le liquid flow.
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According to the researches and experiments of the invent-
ors, in the case of atomlzing liquid in a large quantity it
has been found that the height (h) and ~idth (w) of each step
of the edged portion must be kept at a specific range, that
is, under the condition as follows:
0.2mm~ h ~A/4 (1)
0.2mm c w C A~4 (2)
Wherein A is the length of ultrasonic waves.
In a preferred embodiment of this invention the height
(h) and width (w) of each step are 15 h/wc 10. Particularly
in the vibrating element having the configuration as shown
in Fig. 3 the height (h) is preferably less than 4mm. The wave
length (~ of ultrasonic waves varies with the materials used
for the vibrating element such as Inconel, titanium, etc. and
is usually in the range of 5 to 50 cm.
Fur-ther, the output of the ultrasonic oscillator for vib-
rating the vibrating element is substantially lO W and the
amplitude and freguency of the vibrating element are 30 to
70mm and 20 to 50kHz, respectively. In addition the diameter
(D) of the vibrating element is preferably in the range of
A/lO to ~/4. The flow rate of the li~uid to be processed
increases as the amplitude and diameter (D) are larger.
The~vibrating element 14 id continuously vibrated by
ultrasonic vibration generating meas 100 operatively
connected to the body portion 16, so that the liquid fuel
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:Ls atomiz~(l and injec~d outwardly as it is delivered to
~:h~ edq~(l portioll 32. lt is important tllat uneven injection
~e eliminat~d so .~ o l.nsure uniform injection around an
:IIljcctioll valve~. tn ~hl~ regard, a~ sl~own in Fig. 5, the
llalall~ o~or l~ortloll.4~ of the hollow needle valve 34 may
bo a plurality oi, ~ay, two diametrically opposed angularly
~xtending groove~ ~3. i~ hclg been found that such arrangement
causes turbulence to.~o produced in the fuel supply passage
as well as imparting a swirl to the fuel ~eing injected to
reby ~liminate un~ven injection. In addition, such
~rran(3c~ m.ly al.~o ~rvo to promote separation of the spray
t~ uo I of ~ Lll~ ed~a~ a~ well as to enhance the atomization.
~Il ex.~ pl~ ol: varlo~ parameters and dimensions as to
the ultrasollic in~ectEan nozzle accordin~ to the invention
~!~ descr.l~d h~r~ abov~ Is as follows:
OUt l-Ut of ult~a~ontc vibration: :LO watts
~onnratiny means
Amplitude o~ vibration of : 34 ~m
vibrating element
Frequency of vibration of : 33 KHz
vibrating element
Geometry of vibrating element
Width(w) of edged portion : 0.5 mm
First step ................. : 7 mm in diameter(Do)
Second step : 6 mm in diameter
Third step ~ : 5 mm in diameter
Forth step : 4 mm in diameter
.
Fifth step : 3 mm in diameter (d)
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~2~7~6~7
Height(h) of each step : 2 mm
Type of fuel : Gas oil
Flow ratc of ~u~ ~0.06 cm3 per injection
Injcction pro~ of fuel 1~70 kg/cm2
Tem~eraturc ol fusl : Normal temperature
Materlal for vlbrattny element: Titanium lor iron)
Notcs:
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(L) It lt3 advantn~leo~s .to make the amE~litude of vibration
o~ ~he vil~r.ltin~ nt cls great as possible.
(2`l The vibratill(J olement should have a frequeJIcy of
vil~ratiol~ lligher ~han 20 l~llz.
(3~ The injection fuol of fuel should be made .to approach
tllC pressure in the en~inc chamber.
A pt~rtioll (~u~l)lulJ) of the fuel supplied to the fuel
r~3~rvt~ir 64 fl.owll tllrough th~ fine space (in the order of
~m) betw~ ll lllo h~llow n~0dle valve 34 and the needle valve
hol(ler 50 to ~e ~ollect~d into tlle rQturn fuel sump 72, and
i~ then lot.l~rned to ~h~ ~uol outlet 78 through the fuel
ro~urn l~a~9a~JQ~ 7~ an~ 16. rrl~ fuel outlet 78 is connected
v~a a ~ul ~al~.lQ c~ndu~t t not sllowll) with the fuel tank so
that the excess fucl is recirculated to the tank.
As the pressuro in the fuel reservoir 64 drops, the
hollow needle valve 34 is moved downward under the action
of the spring 80 to close the fuel reservoir 64, so that the
delivery oF fuel to l:llo odged portion 32 of the vibrating
eLcment 1~ is intc!rrupted, and the fuel injection from the
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nozzle 1 is (11~c~o~t]nll(tll,
~ cc~ (J t.o th~ rnvt3ntioll~ mi~lm;Lng in fuel injection
CIUO to a ~lnlo ]ag ~n lnltiation o vibration is avoided since
the vibratin(3 t3~ l4 Illay be kept in operation irrespective
o~ the fuel supp1y
As indicated abov~, the injection nozzle of this
invention is capable of providing a large amount of injection
at 0.06 cm3 per injcc~;on whLch,makes it possible to put the
nozzle ~o practi~al U~e a~ an injection nozzle for an internal
coll~ustlon englne. ~h~ 1B 500 to 1,000 times as high as the
flow ra~tJ a-; was rep~t~ to be possible with the prior art
ultrasolllt ln~ection no~zie. Furthermore, the present
illvontiol~ o ~pplla~ble to a burner for continuous
combustion tn whlcll l.h~ fiow rat~ may be in the order of
100 ~hr.. rrhi~ invt3ll~tol~ may also be u~ed as a spray drying
apparatus ~or producing powdered medicines.
In addition to the provision for atomization of liquid
in a large quantity as described above, this invcntion is
also characterized in that i~ is capable of providing generally
ul~iform distribution in a~omized particles with an average
purticl~ ra~ius in ~ r~ler of 10 to 30 llm.
Industri~ pli~al-lt~
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A~ clor~t~d fr-~lll the foregoing, the present
il~v~ntioll ~-rovid~ n ~lt~dsonic injecllllg method and
il~joctln~] nc)zzl~ cdl~bJ~ ~E not only atomizing a liquid
,
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mu~erial ill a unlL~ n~J~ r and in a large quantity but
aLso atomiæing a li(lul~ material even at a low flow rate,
on an eithcr intermitt~Jlt or continuous basis.
Accol-dill~31y tl~(J ul~rasonic injecting method and
injoctio~ lo ~ccord~n~l to this invention is suitable for
Urle on Il~ n~ll colllb~t~oll ~nglnes such ~s a diesel engine,
g~l~;oline ell(JLIle~ ~3a~ ~rblne enc3ine alld ~he like, for use
oll extelll~ onlbllt~ n engin~s such as burners for boilers,
h(~;ltin(3 fu~n~ces, ~attng appar~tus and t:he like, or for
Ut3e on a ~l~r.lyin~J or hum~difyinc3 apparatus.
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