Note: Descriptions are shown in the official language in which they were submitted.
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1 Background of the Invention:
The present invention relates to improvements in
windshield washer nozzles which, in conjunction with wiper blades,
function to clean vehicle windshields or similar window units.
Windshield washers presently used in motor vehicles
and the like employ two nozzles, one for each side of the
windshield. The nozzles are fed liquid under pressure from a
reservoir via some type of pumping arrangement which is operator-
initiated for a predetermined time period or until a pr~determined
volume of liquid is pumped.
Disadvantages of the aforementioned existing system
include: the need for two or more nozzles and the appropriate
liquid conduits in order to cover both sides of a windshield;
the localized area against which the issued jet strikes the wind-
shield, requiring many strokes of the wiper blade, and possibly
many actuations of the washer, before mud, salt spray, or similar
dirt can be cleared away sufficiently to afford the desired
visibility; wear and tear on wiper blades which, because of the
localized impact area of the washer spray, are forced to wipe large
sections of dry windshield until the wash liquid is sufficiently
distributed by the wiper; and the running of the wash liquid
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downward, for low vehicle speeds, and upward, for high ~ehicle
speeds, and out of the wiper blade range before it can be distributed
~ .
;by the wiper blade, thereby wasting considerable amounts of wash
liquid.
It is therefore an object of the present invention to
provide a method and apparatus for washing windshields in which
a common nozzle may be utilized to obtain full spray coverage
of the windshield.
It is another object of the present invention to provide
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1 a method and apparatus for washing windshields wherein the wash
liquid is so distributed that a single stroke of the blade will
provide full visibility for most windshield dirt conditions.
It is another object of the present invention to
minimize wear and tear of windshield wiper blades by issuing
wash liquid over the entire path of the blade rather than relying
on the blade to distribute the wash liquid.
It is still another object of the present invention
to distribute windshield wash liquid by means of a nozzle in
such a manner as to preclude run-off of the liquid before it
can be swept by the wiper blade.
Summary of the Invention:
In accordance with one aspect of the present invention
a windshield washer nozzle is arranged to define a liquid jet and
sweep that jet repetitively in a dimension transverse to jet flow.
The swept jet, upon being issued from the nozzle, breaks up into
droplets which impinge upon the windshield over an area defined
by the jet sweep path. One or more of such nozzles may be
used to cover the entire windshield. In a preferred embodiment the
jet is oscillatorily swept back and forth between two extreme
positions. More preferably, the nozzle is a fluidic oscillator,
although non-fluidic oscillators may be used.
~ In accordance with another aspect of the invention
; a single fluidic oscillator, having two discrete outlet
passages from which a liquid jet is alternately issued, replaces
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the two nozzle arrangement conventionally employed to wet both
sides of a windshield~
Brief Description of the Drawings:
The above and stiIl further objects, f~atures and
advantage8 of the present invention will become apparent upon
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1 consideration of the following detailed description of one
speciflc embodiment thereof, especially when taken in conjunction
with the accompanying drawings, wherein:
Figure 1 is a view in perspective of a motor vehicle
windshield and spray apparatus according to the present invention;
Figure 2 is a partially diagrammatic plan view of a
fluid oscillator suitable for use as a spray apparatus according
to the present invention;
Figure 3 is a schematic diagram of a conventional
windshield washer actuator and supply arrangement;
Figure 4 is a view in perspèctive of a motor vehicle
windshield and spray apparatus in which the spray is arranged
to emanate from different locations than in Figure l;
Figure 5 is a view in perspective of a motor vehicle
apparatus and a different type of spray apparatus from that
: used in Figure 1, also in accordance with the present invention;
Figure 6 is a plan view of one type of fluidic
oscillator suitable for use in the embodiment of Figure 5;
Figures 7 and 8 are views in perspective and plan,
respectively, of a spray apparatus suitable for use in the
embodiment of Figures 1 and 4;
: Figure 9 is a view in plan of another spray apparatus
suitable for use in the embodiments of Figures 1 and 4; and
Figure 10 is a view in plan of another spray apparatus
suitable for use in the embodiment of Figure 5.
Description of the Preferred Embodiments:
Referring specifically to Figure 1 of the accompanying
drawings, a motor vehicle 1 has a windshield 2 which is to be
selectively sprayed with liquid in accordance with;the present
invention. Spray emanates from a spray nozzle 3 disposed generally
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1 on the longitudinal center line of the vehicle so that the nozzle
is substantially centered with respect to the windshield. In
any of a number of ways to be subsequently described, nozzle 3
issues a jet of wash liquid which, within nozzle 3, is caused to
repetitively sweep across windshield 2. The spray pattern, which
is generally fan-shaped, is preferably wide enough to extend
across the wiping ranges of both windshield wipers 5 and 6. The
repetitive jet sweep may be of the oscillatory or back and forth
type wherein the jet sweeps first in one direction and then in
the opposite direction between two extreme angular positions.
Alternatively the jet sweep may be unidirectional, going from
left to right or right to left but not in both directions.
Supplying wash liquid to nozzle 3 is accomplished in
a conventional manner as described subsequently in relation to
Figure 3. It is important to note that the single nozzle 3 with
its repetitive sweeping characteristic is able to wet an area
extending substantially across the entire windshield 2; whereas
two conventional windshield washer nozzles are required to
achieve this feature. Moreover, by wetting substantially the
entire area to be wiped, rather than only the localized areas
wetted by conventional windshield washer nozzles, nozzle 3
; eliminates the need for the wiper to bear the burden af distributing
the liquid. The wiper, therefore, does not have to wipe across
dry areas of the windshield. In addition, the sweeping jet
breaks up into individual droplets which strike windshield 2
whereas conventional nozzles issue jets which form solid streams
or puddle-like regions that distort the driver's view. Further,
by quickly wetting the large area to be wiped, the swept jet nozzle
3 permits quick removal of mud, salt, and general road spray upon
a single wipe of the wiper blades whereas many more wipes are
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required to spread the liquid issued from conventional nozzles.
For some vehicles, particularly where the top-to-
bottom dimension of the windshield is quite long, it may be
desirable to use a second swept jet nozzle, such as nozzle 4 in
Pigure 1. Nozzle 4 is also disposed centrally relative to wind-
shield 2 and is arranged so that its issued jet strikes the
windshield at a higher location than the jet from nozzle 3. It
is to be stressed that the second nozzle 4 is optional and would not
be required for the vast majority of automobiles presently being
sold.
Referring specifically to Figure 2 of the accompanying
drawings, a fluidic oscillatGr 10, suitable for use as spray
nozzle 3 or 4, is illustrated in the form of various flow channels
and passages. Oscillator 10 is of the type described in
Fi~ures 1 - 3 of co-pending Patent Application Serial
No.235,845, filed September 19, 1975, (allowed April 10, 1979)and
entitled "CONTROLLED FLUID DISPERSAL TECHNIQUES". As is conventional
in fluidics technology the channels are preferably defined at one
surface of a base plate 11, which surface is then sealed by a cover
plate (not shown). Al~ernatively, plate 11 may be a center plate
sandwiched between top and bottom cover plates. A tapered or
convergent power nozzle 12 is adapted to receive pressurized wash
liquid and issue a liquid jet into the upstream end of an
interaction region 13. The interaction region is defined between
left and right sidewalls 15 and 16, respectively, which first
diverge from power nozzle 12 and then convergetoward an outlet
throat 14 located at the downstream end of the region. Nozzle 12
and throat 14 are disposed in substantial alignment with one
another along the longitudinal centerline of oscillator 10. An
outlet region 17 is located immediately downstream of throat 14 and
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1 is. defined between left and right outlet walls 18 and 19,
respectively, which diverge in a downstream direction from throat
14. A left control passage 21 extends between outlet region 17
and the upstream end of interaction region 13 through port 23
defined in left outlet wall 18 and port 24 defined in left
s.idewall 15. A similar right control passage 22 extends between
outlet region 17 and the upstream end of interaction region 13
through port 25 in right outlet wall 19 and port 26 defined in
right sidewall 16. The upstream sides of ports 24 and 26 terminate
at the outlet of power nozzle 12; the upstream sides of these
ports are set back from the oscillator centerline relative to
the upstream sides.
As is typical with fluidic oscillators, during
operation of oscillator 10 a power jet of fluid issued from
nozzle 12 is cyclically deflected between extreme positions
defined by sidewalls 15 and 16. The phenomena producing oscillation
is described subsequently; for the present, it should be noted
that, when flowing along left sidewall 15, the jet is guided back
to the right thereby and egresses through throat 14 in a direction
generally toward right outlet wall 19. When flowing along right
sidewall 16 the jet is guided back to the left thereby and
egresses through throat 14 in a direction generally toward outlet
wall 18. Intermediate the two extreme positions the jet sweeps
across outlet region 17. Operation of this particular oscillator,
in contradistinction to prior oscillators, is characterized by
the fact that neither working fluid from the power jet nor ambient
fluid is ingested back into interaction region 13 through control
passages 21 and 22. Instead, when the jet flows along left
sidewall 15 towards right outlet wall 19, it entrains and merges
with outflow through right control passage 22; meanwhile, left
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1 contxol passage remains filled with fluid derived from the up-
stream end of interaction region 13.
The absence of inflow or ingestion from outlet region
17 is achieved by creating a static pressure at the upstream end
of interaction region 13 which is higher than the static
pressure in outlet region 17. This pressure difference is
created by a combination of factors, including: the width T
of throat 14 which is only slightly wider than power nozzle 12
so that the egressing power jet fully seals interaction region
13 from outlet region 17; and the length D of interaction region
13 from power nozzle 12 to throat 14, which length is
significantly shorter than in prior art oscillators. It should
be noted that the width X of control passages 21, 22 is smaller
than the power nozzle. In referring to the widths T and X, it
is assumed that the depth H of the various channels in the
oscillator is constant throughout. If such is not the case, the
cross-sectional areas of throat 14 and passages 21, 22 are to be
considered. If all channels in oscillator 10 are of equal depth
(i.e. into the plane of the drawing), and if the width of
power nozzle 12 at its narrowest point is W, then the following
relationships are suitable, although not necessarily exclusive,
for operation in the manner described hereinbelow:
; T = l.OW to 1.7W
D = 4W to 9W
~ Considerable leeway in these dimensions exists, depending to
`~ some extent upon other dimensions such as the setback B between
the downstream ends of sidewalls 15 and 16, the transverse width
of interaction region 13, and the width of openings 24, 26.
The oscillator frequency depends upon the size of
the oscillator and other factors. Generally, the frequency f
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1 may be represented by: f = 54.4 ~ ; or f = 1700 Q where p is
the liquid pressure applied to the oscillator and Q is flow
through the unit.
The absence of inflow to interaction region 13 during
oscillator operation is particularly important. For one thing,
as the liquid jet approaches the outlet wall, for example left
outlet wall 18, it induces and merges with liquid outflow from
left control passage 21. This merger of power jet liquid with
control liquid prevents the power jet from impinging directly
against outlet wall 18; that i5, the outflow from the control
passages 21, 22 provides a sort of cushioning effect for the
deflecting jet. Consequently, the edges of the jet do not
experience the shearing effect which would result from its
impinging against the outlet wall. Minimization of the shearing
effect in turn minimizes the formation of extremely small or fine
droplets at the stream boundary, which droplet tends to ~e blown
away and not strike the windshield of a moving vehicle. In
addition, outflow through control passages 21, 22 ensures against
ingestion of jet liquid or ambient fluid into the interaction
reglon. In most prior art fluidic oscillators, the very operation
of the oscillator depends upon inflow of jet or ambient fluid
to the interaction region via such control or feedback passages.
Such inflow is undesirable since it may contain dirt which can
clog the oscillator. Oscillator 10, on the other hand, eliminates
this problem.
The operation of oscillator 10 may be described as
follows, with reference to Figure 2. Assume initially that
liquid under pressure is applied to power nozzle 12. The liquid
jet which is issued by power nozzle 12 is initially directed
straight through interaction region 13 and egresses through
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1 throat 14. The narrowness of throat 14 results in portions of
the jet periphery being scooped off and recirculated along side-
walls 15 and 16 to form vortices on the sides of the jet in
interaction region 13. Due to slight inherent perturbations in
the jet, the vortex on one side becomes stronger than that on
the other and therefore tends to deflect the jet to flow along
one of the sidewalls (e.g. right sidewall 16 as illustrated in
Figure 2). The remaining vortex further increases the pressure
in interaction region 13 which is effectively sealed from outlet
region 17 by the egressing power jet. The liquid fills the
interaction region and the static pressure therein builds up to
a higher level than that in outlet region 17, whereupon liquid
begins to flow from the interaction region into control passages
21, 22. Meanwhile, the power jet is directed by right sidewall
16 to flow generally toward left outlet wall 18. Liquid outflow
through left control passage 21 is aided by jet aspiration and merges
withthe jet at left outlet wall 18, preventing the jet from
impinging against the wall itself. The jet tends to increase the
flow rate of liquid through control passage 21 when in the position
shown in Figure 2 because of the aspiration effect the jet has
on the left control passage as it flows along left outlet wall 18.
This aspiration tends to reduce the pressure in left control
passage 21 relative to that in right control passage 22 which is
filled with liquid and in which no similar aspiration occurs at
~ this time. The pressure differential in the control passages
`~ is reflected at the upstream end of the interaction region and
causes the jet to be deflected across the interaction region so
as to flow along left sidewall 15 and toward right outlet wall 19.
During such deflection the jet sweeps from left to right across
3~ the outlet region 17. Upon approaching right o~tlet wall 13 the
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1 jet begins to aspirate liquid ~rom right control passage 22 and
ceases aspiration through left control passage 21. The pressure
on the right side of the power stream is therefore rendered
lower than on the left side and the jet is deflected once
again. This cyclic deflection of the ~et results in a cyclic
sweeping back and forth of the jet across outlet region 17.
I have found that the flow conditions in the
unaspirated control passage (e.g. - right control passage 22
when the jet is directed along left outlet wall 18; left control
passage 21 when the jet is directed along right outlet wall 19)
are dependent upon the pressure of the liquid applied to power
nozzle 12. Specifically, for low and intermediate pressures the
liquid in the unaspirated passage tends to form a convex
meniscus which bulges outwardly from opening 25 or 23 into the
outlet region as illustrated in Figure 2 for opening 25. At
high applied pressures the meniscus becomes concave, as illustrated
in Figure 3 for opening 25. In all cases, however, the unaspirated
passage remains full of liquid and prevents any flow back into
interaction region 13. Therefore, over an entire cycle, there
is a net flow outwardly (i.e. to the outlet region) from both
control passages-21, 22.
The relative shortness of interaction region 13 is
:
particularly interesting in view of the fact that in prior art
oscillators short interaction regions render the power jet
; incapable of oscillation or even significant deflection. The
power jet in the present invention not only oscillates within
a short interaction region, but does so at a frequency which
varies in direct proportion to the flow rate through the oscillator.
The build-up of a higher pressure at the upstream
end of interaction region 13 relative to outlet region 17 is
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1 likewise antithetical to the teachingsregarding prior art fluidic
oscillators. Specifically, most prior art oscillators require
feedback flow toward the interaction region to achieve
deflection of the power jet; such feedback flow requires a
low pressure at the upstream end of the interaction region.
Moreover, too high a pressure in the interaction region has
heretofore been thought to impede jet deflection. In the present
invention, however, high frequency oscillation readily occurs.
In addition, it is this pressure build-up which causes flow to
be directed outward through the control passages, a crucial
aspect of oscillator 10.
Depending upon the dimensions of the various parts
of the oscillator, it is capable of delivering a variety of
liquid spray patterns. Specifically, as the power jet sweeps
back and forth it breaks up into droplets of generally uniform
size, which size depends upon a number of factors including the
size of the oscillator, frequency of oscillation, etc. These
droplets are distributed in a spray pattern having a more or
less fan configuration, the sides of which are defined by the
;~ 20 angle between the outlet walls 18, 19 of the oscillator.
Distribution of the droplets within the spray pattern depends
upon the osclllator dimensions, primarily on the width of throat 14.
Referring to Figure 3 of the accompanying drawings,
there is illustrated a schematic diagram of the liquid supply
and actuator for the sprayer illustrated in Figures 1 and 2.
` It should be noted that the arrangement of Figure 3 is
conventional and typical of just one of numerous types of
ar~angements which serve the same function. A reservoir 31 of
wash liquid is arranged to have liquid pumped therefrom by means
of a pump 32 acting via flow tube 33. The pumped liquid is
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1 supplied via tube 36 to sprayer 3 or 4 of Figure 1, specifically
at nozzle 12 of Figure 2. The pump 32 is actuated by an operator-
controlled switch 35 which first initiates a time cycle at
timer 34. For the predetermined timer period, which may typically
be one to five seconds, the pump is rendered operative to draw
wash liquid from reservoir 31 and deliver it to the sprayer.
The arrangement of Figure 3 may be used in conjunction
with all of the sprayer embodiments described herein.
Referring to Figure 4, for some applications,
particularly for vehicles with extra-wide windshields, it may
be desirable to locate sprayers 3, 4 on either side of the
longitudinal center line of the vehicle, much like the locations
of conventional windshield sprayers. This arrangement, of course,
loses the economy of requiring only one sprayer but still is
advantageous in that it more quickly wets the wiped area with
less loss of wash liquid than do conventional sprayers.
In another aspect of the present invention, a single
fluid oscillator may be employed to deliver two alternating non-
sweeping jets to respective sides of a windshield. This
arrangement is illustrated in Figure 5 wherein a vehicle 1 with
a windshield 2 has a sprayer 7 mounted substantially centrally of
the windshield. Sprayer 7, examples of which are described in
detail below, characteristically delivers slugs of liquid from
two outlet passages in alternation. These passages are oriented
50 that one issues its slugs onto the left side of windshield 2
` and the other issues its slugs onto the right side of windshield
`:
2. Numerous types of fluid oscillators operate in this manner,
some of which are fluidic (i.e. no moving parts are required to
` oscillate the jet baok and forth between outlet passages). A
particularly advantageous fluidic oscillator is the one described
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1 in my U.S. Patent No. RE 27,938 which is illustrated in Figure 6
herein.
Referring specifically to Figure 6, the oscillator is
generally designated by the reference numeral 40 and includes a
power nozzle 41 which directs a liquid jet into an interaction
region 42 and thence through an initially diverging and then
converging region which terminates in a throat 43 that opens into
a diverging outlet region 44. The oscillator is provided with
a pair of control nozzles 46 and 47 connected via feedback
1~ passages 48 and 49 to outlet region 44. A flow divider 50 is
disposed in outlet region 44 to define left and right outlet
passages 51 and 52, respectively, between the divider and the
diverging walls of the outlet region.
In operation, the jet issued by the power nozzle 41 is
initially directed centrally of the interaction region 42 and
fills the region with a mixture of fluid, fluid spray, and
entrained air bubbles, whilst some fluid passes into outlet
region 44 and exists via outlet passages 51 and 52. The jet
quickly tends to become biase~ toward one side of region 43 due
to random jet perturbations. The biased fluid mixture flow tends
;~ to follow, for instance, the left wall of region 42, and is
injected into region 44 toward the right outlet passage 52. The
fluid flow passing by the control nozzles 46 and 47 in region 42
strongly aspirates fluid from these control nozzles and from the
I ~ connected feedback channels 48 and 49. The biased fluid mixture
!
;~ flow injected into right outlet passage 52 is aspirated into the
feedback channel 49 and flow~ back through this channel and
through control nozæle 47 into region 42, whilst only air is
aspirated through the feedback channel 48 and control nozzle 46
` 30 into region 42 on the left side of the jet. Since volumetric flow
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1 of air due to the aspiration thrGugh control nozzle 46 is much
greater than the volumetric flow of the air-water mixture
through control nozzle 47, the right side of the jet in region
42 experiences a lower pressure than the left side; this in
turn causes the jet to attach to the right wall of region 42
so that the jet is diverted to the left outlet passage 51.
The above operation is aided and enhanced by a
small portion of the jet in region 42 being peeled off and
returned into region 42 by the cusp at the exit throat 42.
The returned jet portion circulated within region 42 in
clockwise direction in the above example, thus providing a positive
feedback to hold the jet to the right wall. This feedback flow
; also effects a closure of the region 42 exit against external
air which might otherwise enter from the only partially fluid-
filled region 44 into region 42 and which might interfere with
the correct and desired oscillator operation.
The jet diversion to the left outlet passage 51
causes a portion of the air-water jet to enter feedback passage
48 because of aspiration of that passage by the jet. The fluid
flowing through feedback channel 48 and control nozzle 46 causes
a lower pressure on the left side of the jet in region 42 than
on the right side, which by now has aspirated all fluid out of
the feedback line 49 via control nozzle 47 and which aspirates
air from the right outlet passage 52. This condition of pressure
reversal on the two sides of the jet in region 42 again causes the
; jet to switch to the left wall of the region 42, aided by feed-
back in this region so that the jet is now diverted to the right
outlet passage S2.
In the above manner, the jet is caused to switch
back and forth between the left and right outlet passages 51 and 52
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at a rate determined by the time delay in the circuitry, which
is proportional to the fluid flow velocity in the channels,
whereby the power stream flow velocity provides the forward time
delay from nozzle 41 to region 44 and the feedback flow velocity
provides the feedback time delay from region 44 to control
nozzles 46, 47.
The major advantage over the prior art of using a
single, two-outlet fluid oscillator for the purpose described
is that only one sprayer unit, rather than two, is required.
This reduces the hosing requirement and the installation
difficulty.
It should be noted, too, that the fluidic oscillator
of Figure 6 is only one of the numerous types of fluidic
oscillators useful for application as two-outlet sprayer 7 in
Figure 5. Virtually any two-outlet oscillator can be so employed.
In addition to fluidic (i.e. no moving parts)
oscillators, other oscillator arrangements may be employed for
the embodiments of Figures 1, 4 and 5. For example, reference
is made to Figure 7 wherein there is illustrated a portion of
a rigid stem member 110 having a central fluid-conducting bore
111 defined therein. ~ne bore terminates at the outlet end
o~ the stem where it receives a flexible tube 112. One end of
the tube is bonded or otherwise secured in the bore 111; the
othex end of the tube is freely suspended. Water flow through
the bore 111 and tube 112 causes the outlet end of the tube to
react by whipping baGk and forth. If this whipping motion is
constrained to a single plane, the tube sweeps back and forth
at a frequency determined by the water pressure.
In Figure 8, the sweeping arrangement of Figure 7
is illustrated as part of a nozzle 120. Specifically flexible
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1 tube 121 is fixedly mounted at one end 122 where it receives
water under pressure. The other end of the tube is suspended.
A bottom wall 123 and top wall (not shown) constrain the tube
so that it moves only in a plane parallel to these two walls.
Water issued by tube 121 is in the form of a jet which
respectively sweeps back and forth as the tube shifts back and
forth within head 120. As illustrated, nozzle 120 is suitable
as a sprayer unit for the embodiment of Figures 1 and 4. To
modify nozzle 120 for use in the Figure 5 embodiment, one would
merely extend the downstream length of the unit and add a flow
divider so that two discrete, appropriately directed outlet
passages are formed.
Still another sweep arrangement is illustrated in
Figure 9 wherein a vibrating reed type oscillator is
incorporated in a nozzle 130. The oscillator includes a
generally heart-shaped interaction region 131 which is open
at its pointed or downstream end to provide an outlet 135
for a water jet. An outlet region 136 is located downstream
of outlet 135 and is bounded by diverting outlet walls,
137, 138. Inlets 132, 133 for pressurized water are located
in respective lobes of heart-shaped chamber 131 and are
arranged to receive pressurized water from a supply conduit
(not shown). Interaction region 131 is formed as a channel
in one plate of nozzle 130 and is covered and sealed by another
plate (not shown).
A vibratable reed 134 extends longitudinally through
chamber 131 and is fixed to the upstream end o the chamber.
The other end of reed 134 is freely suspended and extends into
outlet region 136. The width of the reed (i.e. - the dimension
perpendicular to the plane of the drawing) is just slightly smaller
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1 than the depth of the channel from which the interaction region
131 is formed. The reed thus divides interaction region 131
into two sub-chambers 139, 140.
In operation, the reed 134 is alternately driven from
side to side in the interaction by the alternating and oppositely-
phased build up and relaxation of pressure on both sides of the
reed. For example, in the position of the reed shown in solid
line of Figure 9, wherein the reed is against outlet wall 138,
sub-chamber 139 is sealed off from outlet 135 by the reed.
; 10 Consequently the pressure builds up within sub-chamber 139. Sub-
chamber 140 on the other hand has complete access to outlet 135
so that outflow from sub-chamber 140 avoids pressure build-up
therein. The differential pressure between the two sub-chambers
deflects the reed. Oscillation of the reed continues in this
manner.
Outflow from the lnteraction region is in the form of
a water jet directed in accordance with the position of the reed.
For example, when the reed is against outlet wall 138, outflow
from sub-chamber 140 is directed by the reed and by the sub-
chamber sidewall to flow along the reed. As the reed begins
; ~deflecting toward outlet wall 137, flow from sub-chamber 140
remains directed along the reed, the directivity being aided by
the boundary layer attachment or Coanda effect along the reed.
., ~
In addition, as the reed moves from outlet wall 138, outflow
begins and gradually increases from sub-chamber 139. This outflow
; is also guided by the reed and by the curvature of the sidewall in
sub-chamber 139. The individual jets from the two sub-chambers
merge just downstream of the termination of reed 134 due to the
low pressure region created at the reed tip by the aspiration
action of the flowing streams. The merging of the two streams
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1 forms a single jet which is thus swept by the reed as it
oscil:Lates back and forth. Depending upon the material and
dimensions of the reed and upon the pressure of the water,
high frequencies may be readily achieved.
The nozzle 130 of Figure 9 is appropriate for use
as the sweeping spray unit in the embodiments of Figures 1 and
4. This nozzle can be modified, as shown in Figure 10, by
merely adding a flow divider 141 in outlet region 136 to define
two discrete outlet passages 142 and 143. This oscillator may be
employed in the embodiment of Figure 5.
In its broadest contexts, the invention as described
contemplates a windshield washer employing a sweeping jet, no
matter how it is swept. In a narrower concept the invention
contemplates the use of a fluidic oscillator as a windshield
washer, whether the outflow from the oscillator is a sweeping
jet or alternately directed liquid slugs.
It should be noted that where two oscillators are
as in the Figure 1 embodiment, both oscillators may be constructed
as part of a single structure.
It should also be noted that, although the invention
has been described in terms of washing windshields, it is useful
for other windows on a vehicle where a wiper is employed. For
example, it is common on some vehicles, particularly station
wagons, to employ a washer-wiper arrangement on the rear window
of the vehicle. - -
It must once again be stressed that the washer of
the present invention is-employed in conjunction with a wiper
blade to efficiently wet the window to be wiped
While I have described and illustrated specific
embodiments of my invention, it will be clear that variations of
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1 the detail.s of construction which are specifically illustrated
and described may be resorted to without departing from the
true spirit and scope of the invention as defined in the appended
claims.
10
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