|1.||All weather fan spray apparatus for windshield of an automobile comprising: an oscillation chamber having left and right side walls a power nozzle for introducing a fluid power jet into said oscillation chamber; an outlet throat coaxially aligned with, said power nozzle and having a crosssectional area related to the crosssectional area of said power nozzle so as to provide a fan spray of a predetermined angle and directed towards said windshield, a pair of top and bottom walls diverging from each other in the direction of said outlet region so as to expand said power jet in all directions transverse to the direction of travel in advance of said outlet throat.|
|2.||The invention defined in Claim 1 wherein said apparatus is mounted on said automobile proximate the • center of said windshield, said fan spray is at a sel¬ ected angle related to the ratio of the crosssection¬ al area of said outlet throat to the crosssectional area of said power nozzle, with said outlet throat approximating a square.|
|3.||In a liquid spray apparatus for cyclically deflecting a liquid jet between the extreme positions defined by a pair of end walls to create a fan spray, said liquid jet issuing from a power nozzle toward an outlet through an oscillation inducing region and being subjected to cold temperatures such that oscillation is impaired, a method of assuring cold temperature oscilla¬ tion comprising expandint the crosssectional area of IjURE OMF " said liquid power jet in a pair or orthogonally oriented directions in the space between said power nozzle and said outlet.|
|4.||The invention defined in Claim 3 wherein the crosssectional area of said power nozzle is rectang¬ ular and the cross sectional area of said outlet is approximately square.|
|5.||In a fluidic oscillator device constituted by a body member having an oscillation chamber therein, said oscillation chamber having fluid inlet means for receiving fluid under pressure and admitting it into said chamber and a fluid outlet throat for issuing pressurized fluid from said chamber into an ambient environment in a fan shaped spray, said fluid inlet means and said outlet throat being coaxial and having crosssectional areas related to the angle of said fan spray rendering said oscillator relatively insensitive to low temperature, the improvements comprising, in¬ creasing the aspect ratio (H /W ) of said outlet throat, by increasing the height Hfc and decreasing the width W. while maintaining the ratio of the crosssectional area of said outlet throat to the crosssectional area of said fluid inlet means substantially constant for a predetermined fan angle for said fan shaped spray.|
|6.||In a fluidic oscillator including a body member having the following volumetric regions therein, an in¬ teraction region having an upstream end and a downstream end and a left and right side walls which first diverge from said upstream end and then converge towards said downstream end, a power nozzle region adapted to rec¬ eive fluid under pressure in a position to direct a jet of fluid through an entrance aperture into said inter "BU EACT OMPI action region through said upstream end, left and right outlet walls which diverge from said exit aperture, left and right control regions extending between the upstream end and a downstream end of fluid passing through said device to caise the right and left sweeping of said jet fluid and creat a fan spray, the improve¬ ments for assuring cold weather oscillation of said device comprising expanding said jet of fluid immediat¬ ely upon entrance into said interaction region so as to assure the filling up of said interaction region with fluid.|
|7.||In a fluidic oscillator including a body mem¬ ber having the following volumetric regions therein, an interaction region having an upstream end and a downstream end and a left and right side walls which first diverge from said upstream end and the converge towards said downstream end to define an exit aperture at said downstream end, a power nozzle region adapted to receive fluid under pressure in a position to direct a jet of fluid through an entrance aperture into said interaction region through said upstream end, left and right outlet walls which diverge from said exit aperture, left and right control regions extending between the upstream end and a downstream end of fluid passing through said device to cause the right and left sweep¬ ing of said jet fluid and create a fan spray, the im¬ provements for assuring cold fluid oscillation of said device which comprising increasing the aspect ratio (H/W) of the outlet throat without increasing the cross sectional area thereof relative to the crosssectional area of said power nozzle. "BU 1 ^.|
Cold Weather Fluidic Fan Spray Devices and Method
Background of the Invention
The invention is particularly applicable to wind- shield washer systems for automobiles but is not limited to that art area. In Bauer application, U.S. Serial No. 618,252, filed October 16, 1975 and assigned to the assignee hereof, various forms of liquid fan spray gen¬ eration systems are disclosed, including, ' one as dis- closed in U.S. Patent No. 4,052,002, assigned to the assignee hereof, of which the inventor hereof is a co- inventor, and incorporated herein by reference. In such fluidic oscillation systems, the distance between the power nozzle (e.g. , the entrance aperture for the power jet) and the outlet or throat area of the system (e.g., the exit aperture) and the ratio of the cross- sectional area of the power nozzle to the outlet throat area control the fan angle. The distance between the power nozzle and the throat is a function of the fan angle, the fan angle being inversely related to that distance. Thus, if the fan angle is selected, then the area ratio of the throat outlet to the power nozzle is established. For example, the cross-sectional area of the output throat should be approximately two and one- half times the area of the power nozzle. However, in the oscillator as shown in U.S. Patent No. 4,052,002 as well as conventional fluidic oscillators, the liquid jet from the power nozzle must fill up the cavity in order to set up alternate vortices in the interaction region. Initially, a coherent fluid jet travels from the power nozzle through the throat in a straight stream. The power jet must therefore expand sufficiently to fill the throat before the interaction region and the
oscillation feedback channels begin to fill. Vortices are formed on either side of the jet of the fluidic oscillator but two vortices cannot exist simultaneous¬ ly with equal intensity. Thus, as one vortex becomes dominant, the power stream will be diverted against the opposite wall and the oscillation begins. •
The power jet velocity at which the throat is fil¬ led is the threshold velocity level and is directly proportional to threshold pressure level. When the weather turns cold, the surface tension and.viscosity of the fluid increase so the cold fluid power jet does not expand readily so as to fill the cross-sectional area of the throat or outlet. In such case, no fan spray develops and the power jet stream passes through the outlet throat to impinge directly on the windshield. An increase in the velocity (an increase in the thres¬ hold pressure) by increasing pump pressure will provide the additional expansion and may be implemented to start the oscillation.* However, these same factors, i.e., increased surface tension and viscosity influence the fluid velocity as the pump will deliver a lower pre- sure fluid for the same energy input level.
Without the invention hereof, the same fluid (water plus an antifreeze, in a ratio of 50:50; at 3CP (centipoise)) at 0° F, the threshold pressure for oscillation is greater than 30 pounds per square inch. With the invention hereof, the same fluid at 0° require- es a threshold pressure of about equal to or somewhat greater than three pounds per square inch in a fluidic oscillator of the same character and size. Thus, accord¬ ing to the present invention, the same oscillator geome¬ try or silhouette has increased or improved cold start
* But it may not be successful in producing, for ex¬ ample, a full fan angle.
oscillation capabilities while at the same time main¬ taining the low pressure start capabilities, and avoids the use of a large pump.
According to the invention, the cross-sectional area of the outlet throat is maintained substantially constant but the height to width ratio of the throat (the aspect ratio (H/W)) is increased (by increasing H and diminishing W) while maintaining the cross-sec¬ tional area substantially constant. Whereas the cross- section of the throat outlet approaches a square while maintaining substantially the same area, the cross- section of the power nozzle remains essentially the same. The fan pattern angle is proportional to the ratio of the throat area to the power nozzle and by increasing the aspect ratio, there is a reduction in „ the outlet throat width so that the jet does not need to expand as much to fill the throat. All of this leads to a greatly improved cold weather starting capability for the oscillator. In the absence of the present in- vention, cold weather oscillation is substantially re¬ duced and/or eliminated so that only a single concen¬ trated jet stream impinges upon the windshield of an automobile, for example.
Brief Description of the Drawings The above and other objects, advantages and featur¬ es of the invention will become more apparent when con¬ sidered with the accompanying drawings wherein:
Figure 1 is a diagrammatic sketch of an automobile windshield washer system to which the invention has been applied;
Figure 2 is a diagrammatic sketch of a similar sys¬ tem wherein a dual fan spray is utilized;
Figure 3 is the silhouette of a fluidic oscillator incorporating the invention;
Figure 4 is a cross-sectional view taken on lines 4-4 of Figure 3 showing taper to the lower wall or boundary and the secondary stream exapnsion according to the invention; Figure 5 is a top view of a silhouette of an os¬ cillator as disclosed in U.S. Patent No. 4,052,002 and incorporating the invention;
Figure 6 is a cross-sectional view taken on lines 6-6 of Figure 5; and, Figure 7 illustrates a single fluidic device for providing a dual spray angle with an overall spray angle of 110° and a 30° splitter in the middle of the pattern so as to provide two individual streams of about 40° in width at the extreme ends of the pattern which reduce wind effects and directs the fluid to the area of the windshield where it is more needed.
Detailed Description of the Invention
Referring to Figure 1, an automobile windshield 10 is provided with a fan spray device 11 which issues a fan spray 11 of proper droplet size and sweep frequency. Washing fluid for this spray 12 is provided by pump 13 from reservior 14, which would conventionally be under the hood of the automobile. The fluid 16 in reservior 14 is subject to temperature variation and, usually is a mixture of water and an antifreeze with a cleansing compound included therein.
The fan angle illustrated in Figure 1 is about 95°, but it will be appreciated that a larger or smaller fan angle may be incorporated in the invention depending upon the parameters discussed later hereafter. How¬ ever, for a single device 11 to fully and adequately cover windshield of an automobile, the spray angle or fan angle should at least be approximately 95°.*
* It will be appreciated that the further the nozzle is away from the windshield, a smaller fan angle can cover a larger windshield area.
In Figure 2, fluid 16 from reservior 14 is supplied to pump 13 which delivers the fluid under pressure to a pair of devices 11R and 11L (for the right and left and sides of the windshield of the vehicle) . In this case, the fan angles are approximately 45° more or less. As shown in Figure 7 hereof, a single device 11 may be utilized to provide ' a dual spray on the windshield and incorporating the cold weather starting principles of the present invention.
Referring now to Figure 3, the washing fludi is lead to power nozzle supply 20 from the pump reservior and from supply 20 the fluid is directed through a pow¬ er nozzle 21 having a width D (exemplary preferred dimensions are illustrated on the drawings) . The fluid issuing through power nozzle 21 is directed in a power jet stream past a pair of control ports 22, 23 of feed¬ back passages 24, 25, respectively into an interaction region 26. Upper or cover plate 39 is secured to the upper confronting edges of the silhouette, the "voids" are to reduce the volume of material in the body member, but in a preferred embodiment, the device of Figure 3 is a planchette inserted into a housing indicated in dotted outline in Figure 4. Interaction region 26 is provided at each side with a pair of vortex sections 27, 28 in advance of the outlet throat 30. Throat 30 has a width W and a pair of flaring side walls 31, 32. The dotted lines 31' and 32' indicate the prior art position of the walls 31 and 32 with the non-tapered prior art floor shown in dotted outline in Figure 3, the "polarity notch" shown in Figure 4 assuring proper orientation in the housing in non cold weather fan spray
fluidic device prior to the present invention, walls 31, 32 constitute a pair of end walls which structurally define the outer limits of the fan spray. A pair of the feedback passages 24 and 25 are integrally formed in the body member and operate as a conventional fluid¬ ic oscillator feedbacks providing a sweeping or swept jet which is bounded by walls 31 and 32. As described above, the ratio of the area of throat 30 to the area of power nozzle .21 area defines the fan angle. In the present construction and with the given preferred ex¬ emplary dimensions, with a fan angle of about 95°, the outlet area is approximately two and one-half times the area of the power nozzle.
In the case of cold weather operation, the power jet from nozzle 21 initially travels from the power nozzle through throat 30 in a straight stream. As described earlier, the power jet must expand sufficient¬ ly to fill the throat 30 before the interaction region 26 and feedback channels 24 and 25 can begin to fill. Vortices are then formed on either side of the jet in the regions 27, 28 and as one vortex becomes dominant, the power stream will be diverted against the opposite wall, positive feedback occurs and oscillation begins. The power jet velocity at which the throat is filled is the threshold velocity and this is proportional to the threshold pressure level. Because of the increased surface tension and viscosity, a cold fluid power jet will not expand as readily. Increase in velocity by increasing the threshold pressure by increasing the size and/or energy delivered to the pump described in Figures 1 and 2 may be incorporated to start oscilla¬ tion. However, this means that a larger pump must be incorporated in the system.
The present invention, avoids the necessity of in- creasing the size of the pump changing the aspect ratio
(H /W ) of the throat and introducing a secondary flow pattern to expand the power jet before it reaches the throat. As shown in Figure 4, the bottom wall 40 (it could just as well be the upper wall of cover 39 or a combination of the two) has taper incorporated in it. At the same time, the width W of the throat is reduced to the area shown in the full lines of Figure 3. The range of taper angles found most suitable to accomp¬ lish the objective ranges from about 1° to about 10°. Five degrees (5°) has been found to be most acceptable since the taper angle is a function of the distance be¬ tween the power nozzle 21 and the throat or the outlet 30. In other words, the objective is to assure that the throat is narrowed (W) but that the cross-sectional area thereof remains essentially the same with a given width W and height H of a power nozzle 21. The taper angle is inversely related to. the distance between the power nozzle and the throat, the larger the distance, the smaller the angle and the smaller the angle the larger the distance- the objective being to maintain ' the ratio of the cross-sectional area outlet 30 to pow¬ er nozzle 21 constant since that parameter determines the width of the fan angle. As shown in Figure 4, low¬ er wall 40 is tapered at an angle of about 5° which, -for a 95° fan angle is found to provide barious sat¬ isfactory cold weather starting operation as well as, of course, operating quite satisfactorily in warm wea¬ ther. It will also be evident that the changes in the aspect ratio (the height H to width W of the throat) means that the jet need not expand as much to fill the throat. It is a combination of these factors which provides the enhanced cold weather operation.
In constructing the structure illustrated in Fig¬ ures 3 and 4, variour techniques and molding and/or casting of plastic of metal may be used to form the
silhouette illustrated. If formed in two (or more) parts as illustrated, as long as good sealing technique is incorporated between confronting halves, the device can be taken apart for cleaning. It is preferable that a filter be utilized so as to avoid the necessity of cleaning the device.
Referring now to Figure 5, a form of oscillator as shown in U.S. Patent No. 4,052,002, is depicted and incorporates the tapering wall of the present invention. In this case, it is significant to note that the entran¬ ce passages to the feedback channels is downstream of the throat and hence, a different oscillatory system as fully described in detail in the above-mentioned U.S. Patent No. 4,052,002 takes palce. It will,be ap- predated that the taper angle of 5° is essentially the same in this case since the length of the device, the fan angle and the ratio of the power nozzle cross-sec¬ tional area to the outlet throat cross-sectional area are essentially the same as illustrated in Figure 4. However, I wish it to be clearly understood that the invention is not restricted to these particular dimen¬ sions or ratios and that various other forms of the invention may be utilized. For example, instead of a smoothly tapering bottom wall, combinations of stepped bottom wall which permits an expansion of the power jet in advance of reaching the throat area is contem¬ plated. Alternatively, one or more steps could be in¬ corporated in both the upper and lower fluid bounding walls of the unit to achieve the desired effect. As discussed above, the increase in height H of the throat outlet is accompanied by a corresponding decrease in the width W. of the outlet throat so as to assure that the aspect ratio (H /W.) is increased but that the ratio of the cross-sectional area of the throat to the cross-sectional area of the power nozzle is maintained
substantially constant for a given oscillator.
Figure 7 shows the introduction of a splitter 50 sufficiently beyond the output throat region that it does not constitute an impedance and does not inter- fer with oscillatory action, and is incorporated to the purposes of splitting the output fan into two separate fan sections for directing washing fluid to desired areas of the windshiedl and avoiding wasting of clean¬ ing fluid, on areas where the mirror may be mounted for example. The positioning of the splitter 50 beyond or downstream of the outlet throat does not modify or in any way change the cold weather starting feature of this invention.
While I have described and illustrated one specific embodiment of the invention, it is clear that various modifications, obvious to those skilled, maybe incor¬ porated in the invention without departing from the true spirit and scope thereof as set forth in the appended claims.
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