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Document Type and Number:
WIPO Patent Application WO/1987/006201
Kind Code:
A fluidic oscillator (20) is relatively short in length (under about 2.5 W where ''W'' is the width of the power nozzle) and has a leaky splitter (22) located proximate the center of the outlet flare (21) so as to divide the outlet into essentially two alternating slug flows. The floor (FW) and/or ceiling (CW) of the oscillator diverge between about six degrees and ten degrees to allow the jet steam to expand and thereby avoid creating a back pressure to control ports (CP1 and CP2). When used as a windshield defrost/defog nozzle, vanes (29L and 29R) forming part of the leaky splitter are laterally shifted so that the largest opening is on the drive side and the smaller opening is on the passenger side so as to direct more defrost energy towards the drivers's side.

STOUFFER, Ronald, Denton SHARKITT, Patrick, T.
Application Number:
Publication Date:
October 22, 1987
Filing Date:
April 07, 1987
Export Citation:
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International Classes:
B05B1/08; B60S1/54; F15C1/22; F15D1/04; (IPC1-7): B60S1/54
Domestic Patent References:
Foreign References:
Other References:
VAN NOSTRAND's Scientific Encyclopedia, Sixth Edition, published 1983, VAN NOSTRAND REINHOLD Company, see pages 1233-1236.
See also references of EP 0299977A4
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1. In a motor vehicle windshield defrost/defog apparatus having a source of def ost/defog air and a centrally located nozzle for issuing defrost/defog air upon the driver and passenger sides, respectively, of a windshield surface to be cleared, the improvement comprising means for causing said de rost/de og air to issue in two alternating slug flows of substantially the full intensity of said source, first one of said two slug flows upon the driver side for a predetermined period of time and then the other of said two slug flows upon the passenger side for essentially the same predetermined period of time.
2. The motor vehicle def ost/de og apparatus defined in claim 1 wherein said means for causing defrost/de og air to issue in two alternating slug flows of substantially the full intensity of said source include a fluidic oscillator for issuing a et from said source to ambient, said fluidic oscillator including a power nozzle having a predetermined crosssectional area coupled to a supply of air under pressure, Λn interaction region receiving a jet of air from said power nozzle, said interaction region being defined by a pair of diverging lateral sidewalls and ceiling and floor walls, leading to an outlet flare, a pair of control ports on opposite sides of said interaction region, a continuous inertance loop interconnecting said control ports and controlling the frequency of oscillation, and leaky splitter means located φ 0 ft a 3 Ω μ o £ TJ to TJ Ω o ft It < to rt O Φ to a c TJ ft μ* ύ Φ 0 3 Ό ft ft ft ri to 0 to ft tr 3 3 r μ Ω r r a ft.
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This application s related to Stouffer U.S. application Serial No. 522.884, entitled "Vehicle Windshield Defrost Apparatus With Reduced Dashboard SDace Requirements": Boone et al. U.S. application Serial No. 71fe.737. entitled "Air Sweep Defroster"; and Stouffer U.S. application Serial No. 748,065, entitled "Novel Inertance Loop Construction for Air Sweep Fluidic Oscillator" .


The use of a sweeping ιet fluidic oscillator for issuing a sweeping let of air to, for example, clear the windshield of an automobile, is known in the art. In the above-identi ied related application Serial No. 522,884 of Stouffer, one embodiment uses a continuous inertance loop fluidic oscillator in which a cross-over type fluidic oscillator has a pair of converging sidewalls leading to a common outlet with the air je issuing from the power nozzle being caused to shift from one side of the chamber to the other and issue in a sweeping fashion through the common outlet by virtue of the action of a continuous inertance loop connecting control ports at each side of ' the air _ιet as it

issues from the power nozzle. In the above-identified related application of Boone et al . , the oscillator portion is made relatively short and instead of a diverqinq-converging cross-over type chamber fluidic oscillator element, the sidewal of the interaction region diverge from each other to form an elonqated slot to accomodate the sweepinq angle of the oscillator. The pair of control ports imπ diately adjacent and downstream of the power nozzle are connected to a continuous inertance loop with several different techniques being utilized for accomodating the inertance loop, which is of a length and cross-sectional area so as to assure that the frequency of oscillation is below about 12 Hz for proper defrosting of the windshield. In the above-identified related application q.f Stouffer Serial No. 748,065, the inertance loop has a pair of matching sections for coupling to the control ports o£ the oscillator, a pair of loop sections connected to the respective ends of the matching sections, a pair of transition sections coupling the ends of the loop sections to a cross-over or commo section which is substantially flat and parallel to the plane o the fluidic element.

The present invention la an improvement on the fluidic oscillator disclosed in the above-identi ied related applications, and especially the fluidic oscillator disclosed i the above related application of Boone et al.

It is an object of the invention to provide an improved fluidic oscillator; more particularly, a further object of the

invention s to provide an improved fluidic oscillator element which alternately issues sluqs of concentrated air and is relatively short, easier and less expensive to fabricate, and h particularly unique applicability to defrost/defog function of vehicle windows.

According to this invention, the fluidic oscillator has a relatively short lenqth so that it can be incorporated under th dash/instrument panel of an automotive vehicle for distributing defrost/defoq air on both the driver and passenqer sides of the vehicle to thereby rapidly and efficiently clear the windshield of frost and/or foq. The oscillator includes a power nozzle havinq a predete irined cross-sectional area, an interaction region defined by ceilinq and floor walls and a pair of divergi sidewalls flaring to an outlet. A pair of control ports on the opposite sides of the interaction reqion and in advance of the diverging sidewalls, are interconnected by a continuous inertan loop or member. Accordinq to this invention a leaky splitter i located proximate the center of the outlet and modi ies the distribution pattern of the air so that for the defrost/defog operation of a vehicle windshield, for example, essentially two alternating jets or slugs of defrost/defog air are alternately directed at predetermined positions and anqular orientations on the windshield, each of the two ets being of full energy conte and not .diffused. The leaky splitter is comprised of a necking or pinching end of the floor and ceilinq walls proximate the center of the outlet and includes a pair of sweep angle enhanci

vanes spacedly located to each side of the neck end or pinched end ceilinq and/or floor walls.

Since it is desirable that the driver side be first cleared of frost or fog, the sweep anqle enhancing vanes are biased or offset toward the passenger side so that the largest opening is oriented and aimed towards the driver's side of the windshield and the smallest opening is oriented or aimed toward the passenqer side of the windshield. In a preferred embodimen the floor and ceilinq walls have angles of about six degrees to ten degrees to the axial center line of the interaction region provide an expanding outlet which is needed for interaction reqions which are under about 2.5W in length where W is the wid of the power nozzle. This space is needed to allow the et to expand in the interaction region so as to not create a back pressure at the control ports which would interfere with the oscillation. In a preferred embodiment, the power nozzle has a aspect ratio of about 1:1 which means that it is about as wide it is high, and that each of the two jets issuing through the sidewalls is approximately of the same cross-sectional shape an slightly larger in cross-sectional area. Thus, the invention i effect is switching the jet issuing through the power nozzle first through one side of the outlet and then the other due to the action of the leaky splitter. That is, as the et is switching from one of the diverging sidewalls towards the other of the diverging sidewalls, it impinges on the leaky splitter f a very short period of time. The splitter is relatively a larg

element but due to the leakiness of it, its impedance is significantly lower than a non-leaky split- er and hence does not adversely effect oscillation.

In addition, the distribution can be tailored by the addition of various thickness to the pinchinq end of a floor and ceilinq to achieve better tailoπnq or distribution of the ets impinging upon the windshield and thereby effect cleaning of other areas of glass (such as side windows) after clearing of th main or viewing areas or see areas.

It will be appreciated that while the invention finds particular applicability and uniqueness in its use for the clearing of frost and/or fog from windshields, the oscillator nevertheless has other uses besides clearing qlass areas on vehicles for better viewing purposes.


The above and other objects, advantages and features of the invention will become more apparent in light of the followin specification and accompanying drawings wherein:

Fig. 1 is an isometric view of a fluidic oscillator incorporating the invention.

Fig. 2 is a side elevational view of a fluidic oscillator incorporating the invention illustrating typical dimensional parameters,

Fig. 3 is απ end view illustrating he leaky splitter in

the outlet of the fluidic oscillator.

Fig. 4 is a side elevational view of a modification of the invention,

Fig. 5 is a side sectional view of the fluidic oscillator of this invention installed to issue defrost/defog air on the windshield of an automotive vehicle,

Figs. 6a-6g are illustrations showing the defrost efficacy of the fluidic oscillator according to the invention.


In general, fluidic oscillators accordinq to the invention have an interaction reqion IR having an upstream end and a downstream end with a power nozzle PN for projecting a jet of air (or other fluid) into the interaction reqion. First and second control ports CPl and CP2 at each side of the upstream en of the interaction region IR and at each side of the jet of air projected into the interaction region by the power nozzle, are interconnected together by a continuous inertance loop CL. The interaction region is defined by a pair of diverging sidewalls SW1 and SW2 and floor and ceiling walls FW and CW with the upstream ends of the diverging sidewalls SW1 and SW2 being connected directly to the upstream wall forming the control port CPl and CP2, respectively. In the operation, the air leaving power nozzle PN causes the et to oscillate back and forth between sidewalls SW1 and SW2 at at frequency determined by the

lenqth of continuous inertance loop CL and the oscillatinq frequency is essentially proportional to the flow of air through the power nozzle PN - the hiqher the flow rate, the higher the frequency of oscillation. In the preferred embodiment when used as a defrost/defog nozzle for vehicles, the frequency of oscillation is under about 12Hz. In the configuration disclosed herein with the parameters shown, the length of the inertance loop between control ports is 15 to 20 inches for a given cross-sectional area of the continuous inertance loop CL.

Fig. 5 shows the dashboard of instrument panel of an automobile which is adjacent to wind screen 11 and has an instrument cluster 12. An air distributing plenum 14 receives windshield clearing air (for either defrosting and/or defogging) (and it could be other areas besides the windshield, such aa the rear window) from a heat exchanger (not shown) and delivery to the windshield depending upon the position of a control (not shown ) in a position to be easily operable and accessable by the driver and/or passenger, all of which are conventional and form no part of the present invention other than being a control source of defroβt/defog air under pressure.

Referring to Fig. 1, fluidic oscillator 20 includes the following volumetric regions:

Interaction region IR, which is defined, as noted above, by a pair of diverging sidewalls SW1 and SW2 and ceiling and floor walls CW and FW, a pair of opposing control ports CPl and CP2, a power nozzle PN coupled to a supply of fluid under

pressure (not shown) , a continuous inertance loop CL interconnecting control ports CPl and CP2. Diverging sidewalls SWl and SW2 and floor wall FW and ceilinq wall CW form outlet 2


Leaky spli 4 - -. structure 22 is located proximate the center of out. 1 et 21. Leaky splitter 22 is comprised of a pair "pinched" or "necked' * in members FWP and CWP in the floor and ceiling walls, respectively. In this embodiment, pinched or necked members FWP and CWP are formed of a pair of triangular panels 23, 24 and 25, 26 respectively, which intrude into outle 21 from the floor FW and ceilinq CW walls and in effect divide the outlet into lobes 21L and 21R. It s noted that the crest 25CC and 25CF are spaced apart and do not contact each other to allow a small flow of fluid therebetween from which is derived the term "leaky splitter". A pair of flow deflection or sweep angle enhancing vanes 29L and 29R are positioned close to but spaced from the bases or points of joinder of triangular panels 23, 24 and 25, 26 to floor FW and CW wall panels so that there can also be flow between the flow enhancing vanes 2SL and 29R and the necked in members FWP and CWP so that the entire structure constitutes a leaky splitter forming two air outlet lobes 21L and 21R. Thus, when the main jet of air or fluid ia switched to the left, substantially all of the luid flows ' out " lobe 21L. A small portion of fluid is directed in a generally

parallel path between the panels 23 and 26 and flow sweep enhancing vane 29L but the main lobe is directed to the left. Likewise, when the fluidic oscillator is switched, and the main air flow through outlet 21 is through the right lobe 21R, there is a small flow between the pinched end portions or crests of th necked in members FWP and CWP as well as a small parallel flow between the panels 24 and 25 and sweep angle enhancing vane 29R. The sweep angle enhancing vanes 29L and 29R cause the angles of the jet issuing through their respective outlet lobes 21L and 21 respectively, to exit at greater angles relatively to the axial center of the device.

The power nozzle PN has an aspect ratio of about 1:1 and each of the individual side lobes 21L and 21R have substantially similar aspect ratios and are sliqhtly larger in cross-section.

In vehicle uses, the flow paths leadinq to the power- nozzle PN may be varied resulting in a velocity profile at the power nozzle which is not uniform and could interfere with the oscillatory operation. A long power nozzle throat could provide the time to correct the velocity profile but in the preferred embodiment, flow straightener means as disclosed in the above-identified application of Boone et al. are used to significantly shorten the power nozzle throat just in advance of the power nozzle to result in a fluidic oscillator whose overall length is relatively short. As shown in Fig. 1, a grid of vanes 35 is positioned just in advance of the power nozzle PN is improved.

As shown in Fig. 2, the floor and ceiling diverge from between about six degrees to about ten degrees to allow the et stream to expand thereby avoid creating a back pressure at the control ports CPl and CP2. This expansion in the outlet is needed for interaction regions which are under about 2.5W (where W is the width of the power nozzle PN) . In Figs. 1 and 2, the continuous inertance loop CL is shown as a loop which has a pair of control port coupling sections CL-CR and CL-CL and a substantially flat common section CL-C which is of a length and cross-sectional area so as to provide a predetermined oscillator frequency. The inertance loop CL can have the con iguration shown in Fig. 4 which includes a pair of matching sections CLΪ1R and CLML, a pair of uniform cross-section loop sections CLR and CLL which lead to transition sections CLTL and CLTR which conne to a common or cross-over section CL-CO which may pass through the interaction region or, preferrably is simply found on one o the other of floor or ceiling walls FW or CW or both, where the common sections CL-CO is split into two parallel paths.

The relative angular orientation of the fluidic oscillator relative to the windshield for defrost/defog purpose is illustrated in Fig. 5.

Figs. 6a-6g illustrate the cleaninq efficacy of a fluidic oscillator as incorporated in this invention for clearing a windshield of an automotive vehicle. The dotted lines "D-aee" indicate the driver's side see area which is the primary area t be initially cleared by the defrost system. Likewise, the

"P-see" area is the area on the passenqer side of the vehicle which it is desired to be cleared in the initial stages. The lines indicated as D-final and P-final indicate the areas which should be cleared within a predetermined period of time so a3 to satisfy FMVSS standards. The time of clearing of a Ford Tempo with an outlet accordinq to this invention is illustrated in eac of the figures.

It should be noted that in these figures, the area cleared on the driver's s de initially is larger and throughout the initial clearing phases is larqer than the area on the passenqer side. Th s is due to the desire to have the defroster clear the driver's side at a faster rate than the passenger's side. Accordingly, the sweep angle enhancing vanes 29L and 29R are shifted laterally in outlet openlnq -.1 so that the distance Dl on the passenqer side outlet lobe 21R is qreater than the distance D2 so that the driver's side lobe 21L receives more of the defrost energy - that is to say, the lobe 21L is larger than the lobe 21R. Moreover, in order to better reach the side windows after clearing of the "see" areas, the necked in portion may be provided with flow distributing enhancers such as a thickening of the panel 25, 26 by addition of an additional thickness on those interior portions of those panels. In effect the small flows through the leaky splitter are used to enhance t distribution effects of air upon the surfaces to be cleared of frost and fog.

Many modifications may be made without departing from the

basic spirit and scope of the present invention, some of which have been suggested hereinabove.