US3731708A

US3731708A - Fluidic device

Info

Publication number: US3731708A
Authority: US
Inventors: Keefe R O; B Beeken
Original assignee: Automatic Switch Co
Current assignee: Automatic Switch Co
Priority date: 1970-11-05
Filing date: 1970-11-05
Publication date: 1973-05-08
Anticipated expiration: 1990-05-08

Abstract

A device for isolating contaminated control signal fluids from fluidic control logic comprises a first emitter channel for directing a first laminar fluid jet through a vented interaction chamber for impact with a second fluid jet issuing through an orifice between the chamber and a second emitter channel. Control signal fluid is introduced into the chamber to render the first fluid jet turbulent and shift the jet impact plane from the vicinity of the orifice toward the opposite end of the chamber. The resultant reduction in fluid pressure in the second emitter channel is manifested at an output port communicating therewith.

Description

0 United States Patent 11 1 1 1 3,731,708

OKeefe et a1. 1 1 May 8, 1973 [54] FLUIDIC DEVICE 3,446,228 5 1969 Stouffer et a1 ..137 s1.5 [75] Inventors: Robert F. OKeefe, Trumbell; Basil 342 IIIIIII ii Beekeni New Haven both of 3,574,309 4 1971 Kinner ..137/s1.5 Conn- 3,587,610 6/1971 Langley.. ....137 815 Assigneez Automatic Switch Florham 3,587,611 6/1971 Doherty ..l37/81,5

Park Primary Examiner-Samuel Scott [22] Filed: Nov. 5, 1970 AttorneyBreitenfeld & Levine [21] Appl. No.: 87,132 [57] ABSTRACT A device for isolating contaminated control signal [52] US. Cl ..l37/81.5 fluids from fluidic control logic comprises a firs1 [51] Ilrl. Cl. ..Fl5c 1/18 amine. channel for directing a first laminar fluid j [58] Fleld of Search ..l37/81.5 through a vented intcracion chamber for impact with a second fluid jet issuing through an orifice between [56] References C'ted the chamber and a second emitter channel. Control signal fluid is introduced into the chamber to render UNITED STATES PATENTS the first fluid jet turbulent and shift the jet impact 3,598,135 8/1971 Lederman et a1. ..137/s1.5 plane from the vicinity of the orifice toward the 0p- 3,603,335 9/197! Lederman et a1. ...l37/8l 5 posite end of the chamber. The resultant reduction in 3,626,962 12/1971 Atkinson 137/81 5 fluid pressure in the second emitter channel is 3,631,875 1/1972 DUCOUSSet etaL- 137/81 5 manifested at an output port communicating 3,520,316 7 1970 Colston 137/81 5 therewim 3,362,421 1/1968 Schafi'cr... 137/81 5 3,417,770 12/1968 Denison 137/81 5 8 Claims, 1 Drawing Figure COVER PLATE MAl N PLATE Patented May 8, '1973 3,731,708

COVER PLATE f ,v MAIN PLATE INV'ENTOR5'. Haber? O/(eefe 7 BY 505d 3. fieeifeiz FLUIDIC DEVICE BACKGROUND OF THE INVENTION The present invention relates to a fluidic isolator for isolating contaminated control signal fluids from fluids operating in a responsive fluidic control circuit wherein the isolator has no moving parts.

Fluidic components are presently being designated with the emphasis on miniaturization to take advantage of attendant high packing densities and-extremely low power consumption. For example, arrays have been successfully formed having 22 flow mode amplifiers in a plate 8 /2 inches by 2% inches. As a result of compacting the sizes of fluidic components, the fluid channels and orifices therein'become exceedingly small incrosssection some having effective width and/or height dimensionsin the order of 0.007 inchor less.

ln'view of the extremely smallfluid channel and orifice cross-sections found in currentfluidic components, it is extremely important that the-fluid, typically air, be exceptionally pure and uncontaminated. It will be appreciated that even relatively minute foreign particles entrained in the fluid can and have clogged or partially obstructed fluid channels and orifices, thus rendering an entire fluidic circuit, consisting of numerous fluidic components, inoperative.

In many applications, fluidic sensors arestationed in positions to detect the movement of a machine element or the passage of a part. These-sensors derive fluid pressure or flow input signals'to a fluidic control circuit which, in effect, acts on such input or controls signals to effect a desired .end result. Unfortunately, the atmosphere enveloping the fluidic sensors is typically contaminated with dust and dirt particles, etc. Consequently, to' allow the contaminated control signal fluids from the sensors to mix with the control logic fluids of the fluidic control circuit proper is to invite trouble. With the myriad of fluid passages and orifices in a typical fluidic circuit,it can be an extremely difficult and time consuming task to check the circuit and determine which one or ones are obstructed.

With this problem in mind, isolators have been designed to preserve the purity of the control logic fluid by maintaining possibly contaminated control input signal fluids separate therefrom. Heretofore, complete separation between the two fluids has been provided by an intervening movable diaphragm or "the like. The diaphragm acts in'the manner ofa relayto couple pressure or flow variations of the possibly contaminated signal input fluid (sensor output) on one side to an un contaminated fluid on the other side, which uncontaminated fluid then serves as the fluid signal input to the fluidic control circuit.

Such prior art isolators are relatively expensive, but more importantly have relatively low operating speeds as compared to typical fluidic components having no moving parts. This is a distinct disadvantage in many fluidic control system applications where rapid response is required. Moreover, when the operation of such prior art isolators is impaired due to the accumulation of contaminants, they are typically replaced in order to minimize down time. Due to thethigh cost of such isolators, this practice is expensive.

It is accordingly an object of the present invention to provide a fluidic isolator having high operating speeds comparable to other fluidic components.

A further object is to provide a fluidic isolator of the above character which has no moving mechanical parts.

Another object is to provide a fluidic isolator of the i above character which is simple in design, efficient in operation, and inexpensive to manufacture in quantity.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

SUMMARY OF THE INVENTION More specifically, the operating principles of flow mode amplifiers and impact modulators are combined in a novelmannerto provide a fluidic isolator which, by virtue of its structural similarity to an existing flow mode amplifier design, is inexpensive to manufacture. Thus, should it become clogged, it can be replaced and discarded at minimal expense. Moreover, the instant fluidic isolator requires no moving parts and thus has operating speeds comparable to that of present day fluidic'components.

The fluidic isolator of the invention is structurally similar to the flow mode amplifier disclosed in FIGS. 12 through 15 of the instant assignee's U. S. Pat. No. 3,469,593 issued to R. F. OKeefe. The disclosure of this patent is specifically incorporated herein by reference.

Generally, the instant fluidic isolator comprises an elongated first emitter channel from which issues a first laminar fluid jet. This first fluid jet is directed through an interaction chamber toward an orifice through which a second fluid jet issues from a second emitter channel. The relative flow characteristics of the two jets are adjusted such that they impact at an impact plane located in the interaction chamber in close proximity to the orifice of the'second emitter channel. The proximity of the impact plane to this orifice causes a relatively high impedance to fluid flow in the second emitter channel. The attendant high fluid pressure in the second emitter channel is manifested at a signal output port coupled thereto.

A control input signal fluid, which is considered to be contaminated, is introduced into the interaction chamber for lateral impingement with the first fluid jet; converting it from a laminar flow state to a turbulent flow state. The impact strength of the now turbulent first jet is significantly reduced with the result that the plane of impact with the second fluid jet is shifted from the vicinity of the orifice toward the end of the interaction chamber from which the first jet issues. The now, relatively remote location of the impact plane relative to the orifice causes a significant reduction in the fluid flow impedance in the second emitter channel, and thus a reduction in the fluid pressure at the output port.

At least one vent port is coupled into the interaction chamber at a location adjacent the orifice for the second fluid jet and is effective to completely exhaust the interaction chamber of fluid including the contaminated control input signal fluid. As a consequence, contaminated fluid never enters through the orifice into the second emitter. channel, thus assuring complete isolation of the output port coupled with the second emitter channel from the possibly contaminated control input signal fluid introduced into the interaction chamber. The output port serves as a source of uncontaminated control input signal fluid for fluidic control logic circuitry coupled thereto.

Further in accordance with the invention, the high and low fluid pressure differential at the output port is accentuated by making the second emitter channel in the form of a venturi section, with the output port coupled into the throat thereof.

The invention accordingly comprises the features of construction,combination of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing, in which the sole FIGURE is a schematic diagram of an illustrative embodiment of the invention.

DETAILED DESCRIPTION Referring to the drawing, the fluidic isolator of the illustrated embodiment of the invention comprises an elongated emitter channel 2 communicating at one end with a pressurized source 4 of an uncontaminated fluid such as air. The other end of the emitter channel 2 communicates with an interaction chamber 6 through an orifice 8 in the chamber end wall 10. A second emitter channel 12 communicates with the interaction chamber 6 through an orifice 14 in the chamber end wall 16 opposite chamber end wall 10.

Emitter channels

2 and 12 and their orifices 8 and 14 are in physical alignment such that a fluid stream orjet issuing through orifice 8 from emitter channel 2 is directed across interaction chamber 6 toward orifice 14. I

The fluid source 4 is also coupled by a fluid channel 18 to the opposite end of the second emitter channel 12 from orifice 14. It will be appreciated that the two emitter channels may be supplied from separate sources.

From the description thus far, it is seen that fluid flows through the emitter channels in opposite directions toward the interaction chamber 6 and, due to the alignment of the orifices 8 and 14, the respective fluid streams or jcts impact with each other. A con structor 20 is incorporated in fluid channel 18 to adjust the rate of fluid flow into the second emitter channel such that the impact plane of the two fluid jets is normally located in close proximity to the down stream side of orifice 14, Le, within interaction chamber 6 in contiguous relation to end'wall l6. Appropriate crosssectional dimensioning of channel 18 can be employed to provide the requisite fluid flow into emitter channel.

12, thus eliminating the need for constrictor 20.. If

separate sources are employed, they would be jointlyx' regulated such as to properly, normally locate the impact plane relative to orifice 14.

Completing the description of the disclosed fluidic isolator, the corners of the interaction chamber 6 adjacent its end wall 16 are recessed, as indicated at 22, to accommodate a pair of vent ports 24, which typically are open to the atmosphere. An input port 26 is coupled into the interaction chamber through a fluid channel 28 and an orifice 30 in chamber sidewall 32. Finally, an output port 34 is coupled into the second emitter channel 12 through a'fluid channel 36 and orifice 38. Emitter channel 12 is preferably given the geometrical configuration of a venturi section for reasons ascribed below. The orifice 38 at the junction of emitter channel 12 and fluid channel 36 is located at the throat of the venturi section.

The actual fabrication of the disclosed fluidic isolator embodiment may, and preferably is in accordance with the teaching in the above-noted U. S. Pat. No. 3,469,593. That is, the various channels and the interaction chamber are formed as grooves in the surface of main plate over which a superimposed cover plate is secured in sealing relation. The various ports are constituted by apertures in the main plate.

As is disclosed in the above-mentioned patent, the dimensions of the cross-section and length of the emitter channel 2 are such that the flow condition of the fluid jet issuing therefrom through orifice 8 into interaction chamber 6 is essentially laminar. This laminar fluid jet crosses the length of the interaction chamber and impacts with the oppositely directed fluid jet issu ing through orifice 14 from the second emitter channel 12, the impact plane being located adjacent the downstream side of the orifice 14. During this quiescent normal state, the impedance to fluid flow in the second emitter channel 12 is relatively high. This creates a high fluid pressure condition at the orifice 38 upstream from the orifice 14 and thus fluid flow through channel 38 to output port 34; this fluid flow serving as an input signal to circuitry coupled to the output port.

In the application of the present invention as a fluidic isolator, input or control port 26 is coupled to receive possibly contaminated control input signal fluid flow originating from a fluidic sensor, for example. During the presence of a control input, a fluid signal is introduced into the interaction chamber through orifice 30 to impinge against the side of the laminar fluidjet issuing from emitter channel 2. This causes the fluid jet to convert from a laminar flow condition to a turbulent flow condition. The attending dispersion of the fluid jet issuing fromemitter channel 2 materially degrades its strength of impact with the now more defined fluid jet issuing from orifice 14. The impact plane is consequently shifted away from orifice 14 and chamber end wall 16 toward chamber end wall 10. With the impact plane removed from the vicinity of orifice 14, the fluid flow impedance in the second emitter channel 12 is abruptly reduced and the rate of fluid flow therethrough abruptly increases. The fluid pressure at orifice 38 falls to a relatively low value. By providing the second emitter channel 12 in the form of a venturi section, the fluid pressure at orifice 38 in the throat thereof falls to near or less than zero. This venturi effect operates to magnify the differential between the high and 'low pressure conditions at orifice 38, and thus the signal at output port 34 is afforded a high signal to noise ratio. upon termination of the input signal at input port 26, the fluid jet issuing from emitter channel 2 reverts to its normal laminar flow condition. The impact plane shifts back to the vicinity of orifice 14, and the fluid pressure at orifice 38 in emitter channel 12 abruptly increases.

During the presence of a control input signal at input port 34, as well as during the quiescent state of the isolator, fluid is vented from the interaction chamber through vent ports 24. Consequently, any contaminants introduced into the reaction chamber with the control input signal fluid are also removed through the relatively large vent ports 24.

It is seen that the fluid jet issuing from the second emitter channel 12 prevents the entry therein through orifice 14 of any of the fluid originating with the control input signal, or for that matter the jet issuing from emitter channel 2. Thus,'fluid signals at output port 34 are effectively isolated from fluid signals at input port 26, and indeed isolated from fluid in interaction chamber 6. The signals at output port 34 are assured of purity, since they are entirely constituted by fluid from source 4.

it will be observed that the fluid signals at output port 34 are inverted in relation to the fluid signals at input port 26. That is, when a fluid signal flows into port 26, there is an absence of fluid signal flow out of port 34. If required, a fluidic inverter, of which numerous types are known, can be employed to invert the fluid signals coupled from output port 34. in fact, the instant isolator also functions as a fluidic signal inverter. Moreover, the device of the invention inherently performs a NOR logic function in that it normally provides an output signal in the absence of an input signal. In this context, the disclosed fluidic device can be provided with plural input ports and function as a multi-input NOR gate the presence of an input signal at any port being effective to terminate the output signal.

It is contemplated that during the isolators quiescent state the impact plane may be located along the emitter channel 12 at a point between the

orifices

14 and 38. The major consideration is that during the introduction into interaction chamber 6 of input signal fluid, the fluid flow through emitter channel 12 must then be effective to shift the impact plane into the interaction chamber and thus prevent entry of fluid from the chamber into the emitter channel 12.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be intcrpretcd as illustrative and not in a limiting sense.

Having described our invention, what we claim as new and desire to secure by Letters Patent is:

l. A fluidic device comprising, in combination:

A. a first emitter adapted to issue a laminar jet of B. a second emitter opposed and aligned with said first emitter and adapted to issue a second jet of fluid for impact with said laminarjet;

C an interaction chamber substantially enclosing the region between said first and second emitters;

D. the junction of said second emitter and said chamber defining an orifice, the flow characteristics of said laminar and second jets being established such that they impact to produce an impact plane normally located in closely spaced relation to said orifice;

E. an output port coupled into said second emitter upstream from said orifice for sensing the fluid pressure in said second emitter;

F. vent means for venting fluid from said chamber;

and

G. fluid jet control means communicating with said chamber and adapted when operative to convert the flow of said laminar jet through said chamber from a laminar condition to a turbulent condition whereby said jet impact plane shifts away from said orifice to thereby produce a fluid pressure change in said second emitter.

2. The fluidic device in claim 1, wherein the flow characteristics of said laminar and second jets are established to normally locate said impact plane in closely spaced relation to the downstream side of said orifice, said signal means being operative to shift said impact plane toward the first emitter end of said chamber away from said orifice, whereby to produce a fluid pressure drop in said second emitter.

3. The fluidic device of claim 1, which further in cludes a channel interconnecting one of said first and second emitters; and a constrictor in said channel for regulating the fluid flow therethrough. i 4. The fluidic device of claim 1, wherein said signal control means comprises an input port coupled into said chamber, to introduce a signal fluid for lateral impingement with said laminar jet and convert said laminar jet from a laminar flow condition to a turbulent flow condition.

5. The fluidic device of claim 4, wherein said vent means comprises two vent ports in said chamber flank ing the downstream side of said orifice, said vent ports being effective to exhaust said chamber.

6. A fluidic device comprising, in combination:

A. a first emitter issuing a first jet of fluid;

B. a second emitter opposed and aligned with said first emitter and issuing a second jet of fluid for impact with said first jet;

C. an interaction chamber substantially enclosing the region between said first and second emitters;

D. an orifice at the junction of said second emitter and said chamber;

1. the flow characteristics of said first and second jets being established such that they impact to produce an impact plane normally located in closely spaced relation to said orifice;

E. means sensing the fluid pressure in said second emitter, said sensing means including an output port coupled into said second emitter upstream from said orifice;

F. said second emitter including a channel having the geometrical configuration of a venturi section, said output port being coupled into the throat of said venturi section;

G. vent means for venting fluid from said chamber;

and

H. signal means communicating with said chamber for converting the flow of said first jet throughsaid chamber from a laminar condition to a turbulent condition whereby to shift said impact plane away from said orifice and thereby produce a fluid pressure change in said second emitter.

7. A fluidic device comprising, in combination:

A. a first emitter issuing a first jet of fluid;

C. an interaction chamber substantially enclosing the region between said first and second emitters; said first and second emitters being supplied from a common source;

D. an orifice at the junction of said second emitter and said chamber;

F. vent means for venting fluid from said chamber, said vent means including two vent ports in said chamber flanking the downstream side of said orifice, said vent ports being effective to exhaust said chamber; and

G. signal means communicating with said chamber for converting the flow of said first jet through said chamber from a laminar condition to a turbulent condition whereby to shift said impact plane away from said orifice and thereby produce a fluid pressure change in said second emitter, said signal means including an input port coupled into said chamber, to introduce a signal fluid for lateral impingement with said first jet and convert said first jet from a laminar flow condition to a turbulent flow condition.

8. A fluidic device comprising, in combination:

A. a first emitter issuing a first jet of fluid;

C i an interaction chamber substantially enclosing the region between said first and second emitter;

D. an orifice at the junction of said second emitter and said chamber;

G. signal means communicating with said chamber for converting the flow of said first jet through said chamber from a laminar condition to a turbulent condition, whereby to shift said impact plane away from said orifice and thereby produce a fluid pressure change in said second emitter, said signal means including an input port coupled into said chamber, to introduce a signal fluid for lateral impingement with said first jet and convert said first jet from a laminar flow condition to a turbulent flow condition, said second emitter including a channel having the geometrical configuration of a venturi section, said output port being coupled into the throat of said venturi section.

Claims

1. A fluidic device comprising, in combination: A. a first emitter adapted to issue a laminar jet of fluid; B. a second emitter opposed and aligned with said first emitter and adapted to issue a second jet of fluid for impact with said laminar jet; C an interaction chamber substantially enclosing the region between said first and second emitters; D. the junction of said second emitter and said chamber defining an orifice, the flow characteristics of said laminar and second jets being established such that they impact to produce an impact plane normally located in closely spaced relation to said orifice; E. an output port coupled into said second emitter upstream from said orifice for sensing the fluid pressure in said second emitter; F. vent means for venting fluid from said chamber; and G. fluid jet control means communicating with said chamber and adapted when operative to convert the flow of said laminar jet through said chamber from a laminar condition to a turbulent condition whereby said jet impact plane shifts away from said orifice to thereby produce a fluid pressure change in said second emitter.

3. The fluidic device of claim 1, which further includes a channel interconnecting one of said first and second emitters; and a constrictor in said channel for regulating the fluid flow therethrough.

4. The fluidic device of claim 1, wherein said signal control means comprises an input port coupled into said chamber, to introduce a signal fluid for lateral impingement with said laminar jet and convert said laminar jet from a laminar flow condition to a turbulent flow condition.

5. The fluidic device of claim 4, wherein said vent means comprIses two vent ports in said chamber flanking the downstream side of said orifice, said vent ports being effective to exhaust said chamber.

6. A fluidic device comprising, in combination: A. a first emitter issuing a first jet of fluid; B. a second emitter opposed and aligned with said first emitter and issuing a second jet of fluid for impact with said first jet; C. an interaction chamber substantially enclosing the region between said first and second emitters; D. an orifice at the junction of said second emitter and said chamber;

7. A fluidic device comprising, in combination: A. a first emitter issuing a first jet of fluid; B. a second emitter opposed and aligned with said first emitter and issuing a second jet of fluid for impact with said first jet; C. an interaction chamber substantially enclosing the region between said first and second emitters; said first and second emitters being supplied from a common source; D. an orifice at the junction of said second emitter and said chamber;

8. A fluidic device comprising, in combination: A. a first emitter issuing a first jet of fluid; B. a second emitter opposed and aligned with said first emitter and issuing a second jet of fluid for impact with said first jet; C. an interaction chamber substantially enclosing the region between said first and second emitter; D. an orifice at the junction of said second emitter and said chamber;