Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
  • F15C—FLUID-CIRCUIT ELEMENTS PREDOMINANTLY USED FOR COMPUTING OR CONTROL PURPOSES
  • F15C1/00—Circuit elements having no moving parts
  • F15C1/22—Oscillators
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
  • B05B1/02—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to produce a jet, spray, or other discharge of particular shape or nature, e.g. in single drops, or having an outlet of particular shape
  • B05B1/08—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to produce a jet, spray, or other discharge of particular shape or nature, e.g. in single drops, or having an outlet of particular shape of pulsating nature, e.g. delivering liquid in successive separate quantities ; Fluidic oscillators

Definitions

• the liquid is a windshield washer fluid which is sprayed on an automobile windshield and the uniform droplets provide a better cleaning action.
• the oscillator in the present invention retains the desirable low pressure start features of the prior art as well as and cold weather start characteristics of the oscillator disclosed in the above mentioned Bray patent applicatio
• a further object of the invention is to provide an improved liquid oscillator for automobile windshield washer systems.
• the preferred embodiment of the invention is carried out with an oscillator constituted by a generally rectangular chamber having at the upstream end an inlet aperture for a power nozzle, an outlet aperture or throat coaxially aligned with the power nozzle or inlet aperture, the outlet aperture also having a pair of short boundary walls which have an angle between them of approximately the desired fan angle of liquid to be issued.
• the fan angle as disclosed in the prior art referred to above, is related to the distance between the power nozzle and the outlet throat.
• a pair of spaced walls extending downstream of the power nozzle and spaced therefrom terminate in a pair of bulbous protuberances or deflections which define the downstream ends of vortex forming spaces and the deflectors also define the vortex controlled entrance ways to the inlets of a pair of liquid passages, the exits for the passages being at opposite sides of the power nozzle. While it is not critical for the proper operation of the present invention, one of the upper and/or lower walls bounding the oscillation chamber is tapered to assure cold weather oscillation.
• Figure 1(a) is a silhouette of a preferred form of the oscillator
• Figure 1(b) is a sectional side elevational view of Figure 1 (a)
• Figure 2 is a view similar to Figure 1(a), but wherein legends have been applied and some of the numbering deleted for clarity and there is shown the positions of three of the vortices and the location of the power jet at a particular instance during operation thereof,
• FIGS 3a-3h diagrammatically illustrate a sequence of vortex formation and movement and resulting flow conditions in. an oscillator incorporating the invention
• Figure 4 illustrates the droplet formation due to the sweeping action of the power jet.
• the oscillator of the present invention is constituted by a molded plastic body member 10 which would typically be inserted into a housing or holder member 11 (shown in section Figure 2) which has a fitting 12 which receives tubing 13 connection to the outlet of the windshield washer pump (not shown).
• Liquid washing compound is thus introduced to the device via power nozzle inlet 14 which thus issues fluid through power nozzle 15.
• the liquid issues from the power nozzle 15 which at its exit EP has a width W, the liquid flowing initially past the exit ports 16 and 17 of liquid passages 18 and 19 respectively.
• Elements 20 and 21 basically form the boundaries of the interaction chamber and the liquid passages 18 and 19, respectively.
• This chamber structure is defined by a pair of walls 20-N and 21-N which are normal to the central axis through the power nozzle 15 and outlet throat 24, which connect with wall elements 20-P and 21-P which are parallel to the direction of fluid flow, the wall elements normal and parallel wall elements being joined by curved section 20-C and 21-C respectively so that the liquid passages from the inlets 18-I and 19-I respectively are of substantially uniform width and about equal to the width W of the power nozzle.
• An important feature of the invention are the bulbous protuberances or projections 20-B and 21-B at the downstream ends of parallel portions 20-P and 21-P which preferably have smoothly rounded surfaces.
• Protuberances 20-B and 21-B with outer wall portions 36 and 37 define the entranceways 38 and 39 to inlets 18-I and 19-I, respectively.
• the outlet throat 24 has a pair of very short diverging fan angle limiting walls 26-L and 26-R, which in this embodiment are set at an angle of about 110° and which thereby defines the maximum fan angle.
• Figure 1 shows that in the device the walls WP of the power nozzle, are not parallel to the power jet centerline, but converge increasingly all the way to the power nozzle exit EP, so that the power jet stream will continue to converge (and increase velocity) until the internal pressure in the jet overides and expansion begins.
• the main oscillator chamber MOC includes a pair of left and right vortex supporting or generating volumes which vortices avoid wall attachment and boundary layer effects and hence avoids dwell of the power jet at either extremity of its sweep; the chamber is more or less square.
• the terms "left” and “right” are solely with reference to the drawing and are not intended to be limiting.
• the feedback passage exits 16 and 17 are not reduced in flow area.
• a reduction in flow area is sometimes used in prior art oscillators to increase the velocity of feedback flow where it interacts with the power jet; to restrict entrainment flow out of the feedback passage; or as part of an RC feedback system to determine power jet dwell time at an attachment wall.
• the feedback passage exits 16 and 17 of the oscillator are the same size as the passages 19 and 20. No aid to wall attachment is necessary because there are no walls on which attachment might occur.
• Inlet (18-I and 19-I) The feedback inlets in many prior art oscillators are sharp edged dividers placed so that they intercept part of the power jet flow when the power jet is at either the right or left extreme of its motion.
• the dividers used in prior art oscillators at the feedback inlet direct a known percentage of the flow to the feedback exit (or feedback nozzle in some cases) in order to force the power jet to move or swicch to the other side of the device.
• the feedback passages sometimes contain "capacitors" to delay the build-up of feedback pressure in order to lengthen the time the power jet dwells at either extreme.
• the feedback inlets 18-I and 19-I on this invention are rotated 90° relative to the usual configuration, and thus do not intercept any power jet flow. In fact, as will be described later under the heading "Method of Oscillation", there is no power j et flow in the feedback passages 19 and 20.
• the partition that separates feedback passage from the main chamber MOC of the oscillator may also be seen in Figure 2, this partition is terminated at the feedback passage inlet by rounded protrusion or deflector members 20-B and 21-B.
• This part .of the partition has three functions; to deflect the power jet stream; to provide a downstream seal for the vortex generation chamber; and to form part of the feedback passage inlet.
• the power jet leaving via EP becomes turbulent. Liquid from the power nozzle EP issues therefrom toward the outlet throat and expands to fill the oscillation chamber MOC.
• the turbulence which begins on the free sides of the jet causes some entrainment of local fluid in the main chamber MOC, and eventually sufficient instability in the pressure surrounding the j t to cause it to begin to undulane. This movement increases with increased pressure until the jet impacts the deflectors and then the normal oscil lation pattern for this device begins.
• the vortex formation in left vortex generation chamber has just begun.
• the deflector 20B has formed a seal between the power jet and the rest of the chamber, so that the only place chamber MOC can get a supply of flow to relieve the low pressure generated there would be from the feedback passage FBI. With normal feedback this would occur because the feedback inlet would be receiving flow at a rate greater than the entrainment flow out of the feedback exit, and the power jet would move toward the opposite side.
• the inlet 18-I to the feedback passage is sealed by a strong vortex entranceway 38.
• This vortex at entranceway 38 was larger (like the one at entranceway 39) until it was confined in the feedback inlet by the power jet. Being suddenly reduced in size, its rotational speed increased, enhancing its ability to seal the feedback inlet 18-I and to deflect the power jet toward the outlet device to ambient. Meanwhile, since the vortex forming in the left vortex chamber has no flow to relieve the low pressure but the power jet, it builds in intensity. The increasing pressure unbalance across the power jet and the motion of the vortex cause. the power jet to move further left ( Figures 3 b , 3 c and 3 d ) and to begin to impact the deflector 20B more on the upstream side. As this condition increases the power jet deflects off the deflector at a more shallow angle permitting the vortex 32 at entranceway 33 to expand. Thus, the outlet stream begins to move before feedback begins.
• the effect of feedback flow is: 1. Permits the power jet to receive entrained flow (through 20), so it can begin to move away from the partition at 16. 2. The additional flow (power jet plus entrained flow) tends to push the vortex 30 in the left vortex chamber downstream.
• the outlet stream begins to move or sweep in an opposite direction by virtue of generation and movement of the vortices 30 and 31 and hence before fluid flow in the feedback passages. Therefore; the motion and position of the outlet stream is not entirely dependent on feedback, whereas the opposite is true, in astable multivibrators.
• the angular relationship (sweeping motion) of the output stream versus time is more closely related to sinusoidal oscillation than it is to astable oscillation. This is evidenced by the fact that the output stream does not "linger” at either extreme of its angular movement.
• the mechanism by which the droplets are formed begins in the power nozzle.
• the convergency of the power nozzle generates turbulence in the power jet.
• Vortex shedding on the free sides of the power jet combines with the internal turbulence of the jet to generate an "organized" instability within the power jet.
• This instability or undulation within the power jet continues to build uniformly as the power jet approaches and passes through the exit.
• the frequency of the undulation being much higher than the frequency at which the power jet sweeps from side to side, provides a pattern very similar to that shown in Figure 4.
• This figure shows a calculated displacement versus time plot of the motion of the power jet stream as it exits the oscillator.
• the power nozzle design purposely generates turbulence in the power jet stream prior t ⁇ the nozzle exit, rather than attempt to generate a "low” turbulence nozzle design with a controlled and stable velocity profile.
• the power nozzle allows the power jet flow within the power nozzle to "hug" one or the other of the power nozzle's sidewalls in order to cause a closer interaction between the power jet and the exits 16 and 17 of the feedback passages 19 and 20, thus, enhancing the generation of very low pressures in the feedback passages.
• the feedback passage exits 16 and 17 are unrestricted so there is no RC storage (e.g. capacitance or resistance effects) and permit maximum flow from the feedback passage.
• the large exits 16 and 17 also permit maximum aspiration to occur as a result of the power jet flowing across the exits.
• the feedback passages 19 and 20 are at a "low pressure-no flow" condition for most of the oscillator cycle.
• Feedback is controlled by low pressure and vortex movement rather than intercepting a portion of the power jet. In fact, there is no power jet flow in the feedback passage.
• the entranceways 38 and 39 to feedback passage inlets 18-1 and 19-1 are designed to provide containment of a vortex for sealing the inlet to the feedback passage against flow.
• the vortices produced in left and right vortex generation chambers dominate the process of oscillation and also provide a nex vortex that moves into the inlet of a feedback passage to terminate each feedback occurrence. It is the vortex, aided power jet control (as opposed to boundary layer or stream interaction) which is the dominant oscillatory mechanism controlling all major aspects.
• aided power jet control as opposed to boundary layer or stream interaction
• this vortex with help from a counter rotating vortex on the other side of the power jet, causes the power jet to bend sharply around the first vortex.
• the fan angle can be any value from 30° to 160°) needed for good watting , for example of a windshield, especially where separate driver and passenger nozzles are used.
• the fan is in the direct line of vision.
• the device retains the low threshold pressure for initiation of oscillation so in the case of a windshield washer assembly for automobiles, there is no need to increase pump sizes for cold weather operation when the viscosity and surface tension of the liquid has increased.
• the oscillation chamber can have the top (roof) and bottom (floor) walls thereof diverging from each other in the direction of the outlet throat so as to expand the power jet in cold weather but it is not necessary in regards to the present invention.
• the device illustrated is an actual operating device. Variations of the output characteristics can be achieved by varying the curvature of protuberances 20-B and 21-B.
• the fan angle can be decreased by shortening the distance between the power nozzle 15 and outlet throat 24.
• the distance between the power nozzle 15 and the outlet throat 24 is about 9W and the distance between side walls 20 and 21 is slightly more than 6W, the distance between protuberances 20-B and 21-B is slightly greater than 4W.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Theoretical Computer Science (AREA)
• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Mechanical Engineering (AREA)
• Nozzles (AREA)

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• 1981
  • 1981-01-13 BR BR8105864A patent/BR8105864A/pt unknown
  • 1981-01-13 EP EP81900400A patent/EP0044331B1/de not_active Expired
  • 1981-01-13 AU AU67780/81A patent/AU544839B2/en not_active Ceased
  • 1981-01-13 WO PCT/US1981/000047 patent/WO1981001966A1/en active IP Right Grant

Patent Citations (4)

Non-Patent Citations (1)

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