US3720218A

US3720218A - High speed decoupled fluidic switching device

Info

Publication number: US3720218A
Authority: US
Inventors: T Drzewiecki
Original assignee: United States Department of the Army
Current assignee: United States Department of the Army
Priority date: 1971-12-07
Filing date: 1971-12-07
Publication date: 1973-03-13
Anticipated expiration: 1990-03-13

Abstract

A novel construction of a fluidic switching device is disclosed, the construction effecting high speed decoupled operation. In the preferred inventive embodiment, the novel construction comprises a modification of a conventional fluidic switching device of the type including an input nozzle, a wall-attachment interaction chamber, and a plurality of output receiver lines, wherein a splitter of rounded convex shape is disposed downstream in the interaction chamber between the plurality of output receiver lines, wherein constrictions are provided to either side of the splitter between the interaction chamber and each respective output receiver line, wherein vent channel means are disposed behind and downstream of the splitter and the constrictions communicating with each output receiver line and coupling each output receiver line to a common vent, and wherein additional decoupling vents are disposed downstream of the constrictions in each output receiver line. This novel construction has the effect of eliminating the receiver line and downstream impedance to switching and specifically removes the vortex in the attachment region and the receiver line inductance.

Description

iluite States atent n91 Drzewiecki 1Mal'Ch 13, 1973 HIGH SPEED DECOUPLED FLUIDIC SWTTCHING DEVICE [75] inventor: Tadeusz M. Drzewiecki, Gaithersburg, Md.

[73] Assignee: The United States of America as represented by the Secretary of the Army [22] Filed: Dec. 7, 1971 [21] Appl. No.: 205,642

[52] US. Cl. ..137/839 [51] ..Fl5c l/04 [58] Field of Search ..137/81.5

[56] a References Cited UNlTED STATES PATENTS 3,181,546 5/1965 Boothe ..137/8l.5

3,326,227 6/1967 Mitchell ..137/81 5 3,428,065 2/1969 Cawley.... ..l37/8l 5 3,568,700 3/1971 Verhelst et a1. i ..137/81 5 3,621,859 11/1971 Scott ..l37/815 3,638,671 2/1972 Harvey et al. ..l37/81 5 3,643,693 2/1972 Auger ...137/8l.5 X 3,654,947 4/1972 Hatch, Jr. et a1. ..137/81.5

Primary Examiner--Samuel Scott Attorney-Harry M. Saragovitz et a1.

[57] ABSTRACT A novel construction of a fluidic switching device is disclosed, the construction effecting high speed decoupled operation. 1n the preferred inventive embodiment, the novel construction comprises a modification of a conventional fluidic switching device of the type including an input nozzle, a wall-attachment interaction chamber, and a plurality of output receiver lines, wherein a splitter of rounded convex shape is disposed downstream in the interaction chamber between the plurality of output receiver lines, wherein constrictions are provided to either side of the splitter between the interaction chamber and each respective output receiver line, wherein vent channel means are disposed behind and downstream of the splitter and the constrictions communicating with each output receiver line and coupling each output receiver line to a common vent, and wherein additional decoupling vents are disposed downstream of the constrictions in each output receiver line. This novel construction has the effect of eliminating the receiver line and downstream impedance to switching and specifically removes the vortex in the attachment region and the receiver line inductance.

5 Claims, 2 Drawing Figures HIGH SPEED DECOUPLED FLUIDIC SWITCIIIN DEVICE The invention described herein may be manufactured, used and licensed by or for the United States Government for governmental purposes without the payment to me of any royalty thereon.

This invention generally relates to the fluidic acts and particularly concerns a novel construction of a high speed decoupled fluidic switching device.

Fluidic switching devices such as bistable fluidic elements or flip-flops are typically constructed to include an input nozzle for issuing a fluidic power stream into an interaction chamber wherefrom the power stream exits into one or another of a plurality of output receiver lines. Such devices commonly utilize wall-at tachment interaction chambers such that the power stream initially attaches to one or the other of the two side walls of the interaction chamber to exit into a specific output receiver line. To effect the switching of the power stream from one receiver line to another, control ports are provided which communicate with the interaction chamber and react with the power stream therein in known fashion.

With such devices, a certain time delay or lag occurs between the application of a switching control signal at a control port and the time that the effects of such control signal are felt at a load attached to a particular output receiver line. The causes of this inherent time delay are varied and include, inter alia, the time that it takes the power jet to react to the presence of a control signal, the time that it takes the switching power jet to overcome any downstream impedance or flow field restrictions, and, finally, the time that it takes the switched power stream signal to propagate down the receiver line to the load.

Of course, it would be advantageous to provide a fluidic switching device which is not subject to these various inherent time delays and, to the extent that such is possible through improvements and modifications to the internal geometry of the device, the instant invention has as its primary objective the provision of such a high speed and decoupled fluidic switching element.

A more specific, though equally important objective of the instant invention concerns the provision of a fluidic switching device, of novel construction which effects high speed response by eliminating the receiver line and downstream impedance to switching.

These objects as well as others which will become apparent as the description proceeds, are implemented by the subject invention which, as aforestated, comprises an improvement or modification to a typically constructed fluidic switching device. In this respect, the basic fluidic switching device utilized includes an input nozzle for issuing a fluidic power stream, a plurality of output receiver lines for receiving at least a portion of the power stream flow, a wall-attachment interaction chamber disposed between and communicating with the input nozzle and the output receiver lines, and control ports which communicate with the interaction chamber for selectively switching the power stream in the interaction chamber from one to another of the output receiver lines.

The high speed switching characteristics of such a device is improved, in accordance with the preferred inventive construction, through the provision of a splitter of rounded convex shape which is disposed downstream in the interaction chamber between the plurality of output receiver lines. To either side of this splitter, constrictions are provided between the interaction chamber and each of the respective output receiver lines. A vent channel means or decoupling vent is disposed behind and downstream of the splitter and the constrictions and communicates with each output receiver line and serves to couple each output receiver line to a common vent. Additionally, the preferred inventive construction incorporates other decoupling vents disposed downstream of the constrictions in each output receiver line and at a preferable location immediately opposite or in alignment with the vent channel means behind the splitter.

With such a construction, the flow vortex which normally occurs in the attachment region of the interaction chamber in typical devices is effectively removed, as is the receiver line inductance. The various decoupler vents provided act as a low impedance in that the power stream flow can almost immediately be passed to it. Accordingly, the speed of switching is not retarded and will be the fastest possible since, when the fluidic device of the instant invention switches, the power stream is not affected by receiver line inductance and other impedance but is insulated therefrom by the various decoupling vents.

The invention itself will be better understood and further features and advantages thereof will become apparent from the following description of a preferred inventive embodiment, such description referring to the appended single sheet of drawings wherein:

FIG. 1 is a schematic illustration of a typical existing fluidic bistable element; and

FIG. 2 is a schematic illustration of a fluidic switching element incorporating the improved design features and construction in accordance with the principles of the instant invention.

Referring now to the drawings and particularly to FIG. 1 thereof, a typical fluidic bistable switching device is disclosed. This device will be seen to comprise, in the usual fashion, an input nozzle 10 for issuing a fluidic power stream generally designated by reference numeral 12 into an interaction chamber generally designated by reference numeral 14. The interaction chamber 14 has two opposite and'divergent side walls 16 and 18 and, in wellknown fashion due to pressure diferentials and the like, the power stream 12 will attach via the Coanda effect to one or the other of the side walls 18 or 16. In the disclosed embodiment, power stream 12 is seen to have attached to side wall 18 and is exiting into output receiver line 20, output receiver line 20 being one of two

output receiver lines

20 and 22 in the illustrated element with each of the output receiver lines selectively receiving at least a portion of the power stream flow.

Control ports 24 and 26 are provided to either side of the input nozzle 10 and communicate with the interaction chamber 14. These control ports, in known fashion, serve to selectively switch the power stream 12 in the interaction chamber 14 from one to another of the

output receiver lines

20 and 22 upon the application of a control signal thereto. Thus, in the illustrated embodiment, application of a control signal to control port 24 would serve to switch the power stream 12 from the output receiver line to output receiver line 22. Subsequently, to switch the power stream back to the original output receiver line 20, a control signal would be applied to control port 26, as is known.

So as to isolate the individual

output receiver lines

20 and 22 from the effects of load impedance such as provided by

respective loads

28 and 30, decoupling vents 32 and 34 are typically provided downstream in the respective

output receiver lines

20 and 22. Further, and so as to assist in the selective switching operation and in the creation of suitable pressure diferentials within the interaction chamber 14, other vents 36 and 38 are provided comm unicating with interaction chamber 14.

SUch a typical device has a certain inherent time response characteristic which can be defined as the time lag between application of a switching control signal to control port 24 or 26 and the time that the effects of the switching of power stream 12 are felt by the

loads

28 or 30. For one, there is always a certain time lag between application of a control signal to control port 24 or 26 and the time that the power stream 12 senses and reacts to such control signal.

Furthermore, there is an inherent delay in actual switching of power stream 12 since some time is necessary for power stream 12 to overcome the effects of any downstream impedance such. as would be created by

vortices

40 and 42, vortex 42 being disposed immediately upstream of the splitter 44 in the interaction chamber 14. Additionally, flow field restrictions such as that created by the entrance to each

output receiver line

20 and 22 must be overcome.

Once the power stream 12 has-been switched into one or the other of the

output receiver lines

20 and 22, a further time delay arises due to the time necessary for the signal flow and pressure to propagate down the

receiver lines

20 and 22 and then to the

load

28 or 30, respectively. In this respect, it should be appreciated that

receiver lines

20 and 22 have a certain characteristic inductive-resistive impedance which in and of itself effects a time delay. Thus, it should be recognized that to a large extent, the internal geometry of the fluidic device is responsible for many of the inherent time delay characteristics of the element and, to the extent that it is possible to eliminate such time delays due to geometry design, the instant invention proposes to do so. Specifically, the novel design of the instant invention is such as to eliminate the receiver line and the downstream impedance to switching as abovediscussed, the improved geometry of the instant invention further specifically eliminating the vortex in the attachment region such as vortex 42, and the receiver line inductance.

Attention is now directed to FIG. 2 of the appended sheet of drawings wherein the improved modified construction of a fluidic switching device operating in the advantageous fashion above-discussed is illustrated. The novel improved fluidic switching device will be seen to include, as does a typical fluidic device an input nozzle 46 for issuing a fluidic power stream generally designated 48 into an interaction chamber 50 of conventional construction. In the usual fashion,

control ports

52 and 54 are provided for selectively switching the power stream 48 to one or the other of

output receiver lines

56 and 58 coupled respectively to

loads

60 and 62.

In accordance with the novel principles of the instant invention a splitter 64 of rounded convex shape as shown is disposed downstream in the interaction chamber 50 between the plurality of

output receiver lines

56 and 58. Constrictions 66 and 68 are provided to either side of the splitter 64 between the interaction chamber 50 and each respective

output receiver line

56 and 58, these constrictions being in the form of nozzles and being defined by the passageway appearing between the sides of the splitter 64 and the opposing side walls 70 and 72 of the interaction chamber 50.

Vent channel means 74 are provided immediately behind and downstream of the splitter 64 and the

constrictions

66 and 68. Vent channel means 74 communicate with each

output receiver lines

56 and 58 and couple each output receiver line to a common vent 76. Additional decoupling vents 78 and .80 are disposed downstream of the

respective constrictions

66 and 68 in each of the

output receiver lines

56 and 58 and, in the preferred embodiment, the decoupling vents 78 and 80 are disposed at approximately the same downstream point in each output receiver line as is the vent channel means 74, the vent channel means 74 and each of the decoupling vents 78 and 80 thereby being in substantial alignment with one another.

In the preferred inventive construction as shown, the width of the

constrictions

66 and 68 in each

output receiver line

56 and 58, respectively, is designed to be one half the width of the respective output receiver line, per se. Additionally, and assuming that the width of the input power nozzle 46 is some value W, the width of each

constriction

66 and 68 is preferably designed to be approximately 1.3 W, the width of each

output receiver line

56 and 58 is preferably designed to be approximately 2.6 W, and the length of each

output receiver line

56 and 58 measured from the

respective constrictions

66 and 68 to the

respective loads

60 and 62 is preferably designed to be approximately 15 W. However this length may be reduced to as little as 3 W if the unit always operates with output flow. Thus there is a decrease in the response time of the unit as a whole.

The novel construction of the instant invention as discussed provides a fluidic switching device characterized by high speed, decoupled operation.

it should now be apparent that the objects initially set forth at the outset of this specification have been successfully achieved. lt should be understood that the invention is not limited to the exact details of construction shown and described herein for obvious modifications will occur to persons skilled in the art. Accordingly,

What is claimed is:

1. In a fluidic switching device including an input nozzle for issuing a fluidic power stream, a plurality of output receiver lines for receiving at least a portion of the power stream flow, a wall-attachment interaction chamber disposed between and communicating with the input nozzle and the output receiver lines, and control ports communicating with the interaction chamber for selectively switching the power stream in the interaction chamber from one to another of the output receiver lines, the improvement effecting high speed decoupled operation comprising:

a splitter of rounded convex shape disposed downstream in the interaction chamber between the plurality of output receiver lines;

and

2. The improvement defined in claim 1, wherein said i decoupling vents are disposed at approximately the same downstream point in each output receiver line as is said vent channel means, said vent channel means and said decoupling vents thereby being in substantial alignment with one another.

3. The improvement as defined in claim 2, wherein said vent channel means is disposed immediately downstream of and adjacent to said constrictions.

4. The improvement as defined in claim 3, wherein the width of the constriction in each output receiver line is one half the width of the respective output receiver line.

5. The improvement as defined in claim 4, wherein the width of the power nozzle is W, wherein the width of each constriction is approximately 1.3 W, wherein the width of each output receiver line is approximately 2.6 W, and wherein the length of each output receiver line is 3 W to 15 W.

Claims

1. In a fluidic switching device including an input nozzle for issuing a fluidic power stream, a plurality of output receiver lines for receiving at least a portion of the power stream flow, a wall-attachment interaction chamber disposed between and communicating with the input nozzle and the output receiver lines, and control ports communicating with the interaction chamber for selectively switching the power stream in the interaction chamber from one to another of the output receiver lines, the improvement effecting high speed decoupled operation comprising: a splitter of rounded convex shape disposed downstream in the interaction chamber between the plurality of output receiver lines; means providing a constriction to either side of said splitter between the interaction chamber and each respective output receiver line; vent channel means disposed behind and downstream of said splitter and said constrictions communicating with each output receiver line and coupling each output receiver line to a common vent; and decoupling vents disposed downstream of said constrictions in each output receiver line.

2. The improvement defined in claim 1, wherein said decoupling vents are disposed at approximately the same downstream point in each output receiver line as is said vent channel means, said vent channel means and said deCoupling vents thereby being in substantial alignment with one another.