US3496955A - Electrically-actuated bistable fluid amplifier - Google Patents

Description

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ELECTRICALLY-ACTUATED BISTABLE FLUID AMPLIFIER Filed June 10, 1965 /A/VfNTo/es MA THEW EDEN/5 o/v P/c/fA/eo W Z/EMaQ 5y OQQQM E A To/efvfy United States Patent Ol U.S. Cl. 137-815 12 Claims ABSTRACT F THE DISCLOSURE A fluid amplifier system using an electrically-conducting uid such as a liquid metal where the fluid flow path is changed by magnetic means.

The present invention relates in general to the relatively new technology of uidics, the term fluidics as used herein referring to that field of technology that deals with the use of fluids, either gaseous or liquid, in motion to perform functions such as signal or power amplification, logic or computation, control, and the like. More specifically, the present invention relates to a fluid amplifier in which novel means are provided for electrically actuating the amplifier in addition to the normal fluid mean-s.

Fluid devices are known wherein a relatively lowenergy fluid input can impinge upon and effect switching of a relatively high-energy fiuid power stream to a selectable outlet. Since the output flow is thus of greater energy than that of the input, these devices have been referred to in the art as fluid amplifiers. These amplifiers are small, rugged, and may be constructed of almost any material, such as plastic, metal, or ceramic, and basically comprise a plurality of fluid ducts formed within substantially solid bodies of material. Moreover, these devices possess the advantages of being inexpensive and requiring no movable solid elements.

The fluid amplifier may be one whose operation is based on stream interaction or, on the other hand, it may be one that utilizes boundary layer control.

In a stream interaction system, a first nozzle is supplied with pressurized fluid and thereby issues a first jet that is commonly referred to as the power stream. A second jet, known as the control stream, supplied by a second nozzle, is directed against the side of the rst jet to impinge against and deflect the first jet away from the second jet. If there is no splash or bounce of the fluid streams, momentum is conserved and the first jet will flow at an angle with respect to its original direction, the tangent of this angle being a function of the momentum of the second jet and the original momentum of the first jet. Hence, the degree of the defiection of the power jet is proportional to the momentum of the control jet, so that, given just the right amount of nudge by the control stream, the main stream can be bent in the direction of any one of a plurality of outlet channels and will flow out through that output. It is thus seen that it is possible by means of such an apparatus to direct all or a portion of a high-power jet to a particular receivmg aperture using a lower power second jet and, since it gives a power gain, that this constitutes an amplifier in the conventional sense.

The other technique of fluid control does not produce proportional amplification, but involves instead a bistable r' ICC or fiip-fiop type of operation. More particularly, in this kind of system, the uid power stream, left to itself, locks onto one wall of a chamber through which it is fiowing and, as a result, the stream exists through the outlet channel on that side. An injection of fluid from the control jet on the same side causes the stream to swing over to the other side and lock onto the wall there, s0 that it then flows out of the other outlet channel. In either case, the stream maintains a stable position, flowing only to a particular outlet unless it is switched by a control jet. This kind of fluid amplifier is known as the boundary layer fiuid amplifier.

The reasons for this behavior on the part of the fluid are inherent in the mechanics of the situation. More particularly, as the power stream issues from its nozzle, it entrains duid in the jet interaction chamber, and as this entrained fluid is removed the pressure along one chamber wall is reduced. Generally speaking the particular wall along which the reduced pressure region occurs depends upon the position of one chamber wall relative to the orifice or nozzle of the first jet. More specifically, Iwhen one chamber wall is positioned slightly closer to the orifice than the other, the pressure on the side of the fluid stream closest to that one chamber wall will be lower than on the side of the stream toward the other chamber wall because of the fact that the process of removing entrained fluid is more effective on the first side. INow, as the pressure between the fluid stream and the one chamber Wall decreases, the rfluid stream moves closer towards that one chamber wall, and this movement produces a still further reduction in pressure therebetween -as a result of the increased entraining of fluid. Consequently, in the boundary layer type of amplifier, the fluid stream bends until it locks onto the one chamber wall and remains locked on until disturbed by a control ffuid entering between the one chamber wall and the main iiuid stream, as previously mentioned.

As indicated above, the fiuid amplifiers utilized in the prior art control the delivery of energy of a first stream of fluid to an outlet orifice or utilization device by means of a second fiuid flow issuing from a second nozzle generally at right angles to the first jet. Stated differently, fluid amplifiers in the prior art are responsive to fluid control signals for producing fluid output signals. However, it would be desirable in many instances to control fluid amplifiers with electrical signals rather than fluid signals and, to do so, it has been necessary in the past to apply the electrical signals to an electrically-actuated fluid valve. The fluid output signal from the valve is then aplied as a fluid control signal input to the fluid amplifier.

It is, therefore, an object of the present invention tov provide a yfiuid amplifier which does not require fluid control signals.

It is another object of the present invention to provide a fluid amplifier having only one fluid input stream called the power stream. v

It is a further object of the present invention to provide means responsive to small power electrical signals for producing larger power fluid signals.

It is an additional object of the present invention to provide electro-magnetic means for controlling a fiuid amplifier without the need for an intermediate transducer.

It is still another object of the present invention to enhance the flexibility and versatility of fluid amplifiers 3 by providing electrical actuation of the amplifier in addition to the normal fluid means.

The aforementioned objects are accomplished in the present invention by providing a normal bistable fluid amplifier in which the fluid medium is electrically conducting and electrically neutral and to which is added an electromagnetic coil near the diverging portion of the channel. To actuate the amplifier electrically, for example, when the conducting fluid is attached to the wall near the coil and is to be switched to the opposite wall, a current is pulsed through the coil. The resulting electromagnetic field exerts a force on the fluid in a direction away from the wall to which it had been attached and causes it to switch to the opposite wall and channel. Another coil opposite the first coil can then be used to electrically switch the fluid back to the original side. Hence, the fluid element can be moved or switched by means of electrical inputs to the coil, and this can be done without affecting its normal manner of switching by means of the fluid jets. Consequently, the electrical control means of the present invention may replace or be used in combination with the fluid control means heretofore employed. j

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawing in which an embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.

FIG. 1 is a diagrammatic showing of a boundary layer fluid amplifier constructed for electromagnetic as well as fluid control in accordance with the present invention; and

FIG. 2 presents a portion of the FIG. l embodiment, namely, the output channel portion, and shows a fluiddetection technique made possible by the present invention.

For a consideration of the invention in detail, reference is now made to the drawing wherein like or similar parts or elements are given like or similar designations in the figures. In FIG. 1, the fluid amplifier i-s shown to comprise a solid block of material in which relatively shallow channels have been cut to allow the passage of fluid, the term fluid in this specification and in the: appended claims being intended to cover any material having a flow power, such as a gas, a vapor, a liquid or, more generally, a system of molecules that are non-rigidly fast with one another or, again, of molecule portions such as flows of atom nuclei, or nucleus portions. For a clearer understanding of the appearance, configuration and general construction of fluid amplifier blocks and the channels cut therein, reference is made to the Feb. 8, 1965, issue of Missiles and Rockets, pages 18-48 therein, wherein a number of such devices, reduced to practice, are pictured.

Returning to FIG. l, the inlet channel is designated 11, and it is through this channel that the controlled fluid or power stream flows in the direction of the arrow 12. The forward end of channel 11 is the constricted'area 13 which couples or leads channel 11 into a cavity or juncture 14 to which the other channels in the block are also coupled. More specifically, connected to this cavity are two branch or outlet channels 15 and 16.which are made to receive the fluid flow in a manner such that the power stream will pass through the cavity and flow into either of the aforesaid branch passages with practically no loss of momentum. In this regard, the outlet channels are arranged to form what .may be termed a fork consisting of these two outgoing channels separated by a pointed or triangular structure 17 called the splitter. The splitter is positioned so that if the power stream is not disturbed when it enters cavity 14 and hits the splitter head on, the stream will be divided in two, half the fluid passing into one outlet channel and half into the other.

Turning now to means for deflecting the power stream to cause it to flow or pass through one or the other of the outlet channels, a pair of control conduits or channels 20 and 21 are respectively provided on opposite sides of the cavity through which the control fluids or jets will selectively flow into the cavity for impingement against the power stream. As may be seen from the figure, control channels 20 and 21 are preferably aligned coaxially with one another and they are also preferably oriented or disposed in a direction that is perpendicular to the direction of travel of the power stream in the cavity. In accordance with the present invention, the embodiment further includes a pair of coils 22 and 23 respectively wound around or, stated differently, mounted to encircle, control channels 20 and 21, the coils preferably being positioned as close to cavity 14 as is feasible. The leads of coil 22 are designated 22a, whereas the leads of coil 23 are designated 23a, the two sets of leads respectively beingconnected to current pulse sources (not shown).

As previously mentioned, block 10 may be made out of any one of a variety of materials, such as plastics, ceramics, metals, etc. However, if made out of metal, it is preferred that it be a non-magnetic type of metal so as not to adversely affect the magnetic fields produced by the flow of current through the coils. As for the several channels, they may be either of square or circular crosssection, or even rectangular-shaped, and their dimensions are relatively small.

Considering now the operation of the above-described device, a high-energy stream of fluid 24, the power stream, is pumped into inlet channel 11 at one end and flows through this channel in the direction of arrow 12, and it should be emphasized here that in accordance with the present invention the fluid is one that is electrically conducting. Mercury, sodium potassium and liquid metals are but a few examples of the kinds of electrically-conducting fluids that are available and may be used. As the fluid stream passes through the throat or noule of constricted area 13 and enters cavity 14, it entrains fluid from both sides and this pick-up of fluid along the streams sides causes the pressure to drop in the zones between the stream and the walls of the container. The resulting pressure difference creates an unstable situation in that the higher pressure of the surroundings (ambient pressure) pushes fluid back into the low-pressure zones on both sides of the stream to equalize the pressure.

However, some disturbance or asymmetry, such, as, for example, in the shape of the cavity, usually exists that causes the equalizing return flow to push the stream toward one wall, and as the zone between the stream and that wall narrows, there is less room for the admittance of counter-flow to replace the fluid being entrained by the stream on that side. Consequently, the comparative pressure in the zone drops further, and very quickly thereafter the stream moves over against the wall, with the result that the power stream is directed through the outlet channel nearest said one wall. Moreover, it stays locked onto that wall as long as the stream keeps flowing, because on the wall side a region of low pressure persists near the nozzle, whereas on the opposite side of the stream.

the ambient pressure pushes the stream toward that region. This is the situation or state of affairs presented in FIG. 1 wherein electrically conducting fluid 24 constituting the power stream is shown locked against cavity wall 14a by the aforesaid low-pressure region and thereby directed through outlet channel 16.

The stream can be moved away from this wall and out of channel 16 in a number of ways. In the prior art, this was done in either of two ways, namely, by increasing the pressure on the stream from the wall side or by reducing the pressure on the opposite side, and it Was for these reasons that control channels, such as control channels 20 and 21 in FIG. 1, wereprovided. Thus, by injection of a fluid jet (the control jet) into channel 21 and directingit with sufficient force against the power stream, the stream will swing away to opposite cavity wall 14b where it Will attach itself as it did earlier to wall 14a. At this point the control jet can then be shut oil, for the stream will stay locked onto the far side without any further help provided the control channel is closed such that the preS- sure imbalance cannot be equalized. 0f course, the locking of the stream onto the opposite cavity wall means that the entire stream now exits through outlet channel 15, and it will continue to do so until it is switched once again either by the application of a control jet to channel 20 or by means of suction in channel 21.

By means of the present invention magnetic means are made available and provided to switch the power stream from one outlet channel to the other, and these magnetic means may be used either in place of the control jets or in combination with them. In the latter case, both the magnetic as well as the fluid means may be utilized, either selectively or simultaneously, thereby giving the amplifier a degree of versatility and flexability it had not heretofore known. Accordingly, starting again with power stream 24 going through outlet channel 16, if it is desired to switch the power stream to outlet channel 15, then this can be done by sending a pulse of current of sufficient magnitude through coil 23. The current produces a strong magnetic field that intercepts fluid 24 which, it

will be remembered, is electrically conducting and, there-` fore, is equivalent to a wire moving through the magnetic field. As a result thereof, a strong enough force is exerted on the fluid in a direction away from the wall to which it had become attached to cause it to switch to the opposite wall and channel. In the same manner, that is to say, by sending a current pulse through coil 22, the fluid can be electrically switched back to the original side and channel.

It should be mentioned once again here by way of emphasis that controls channels 20 and 21 and their associated control jets may be entirely eliminated through the use of coils 22 and 23 and electrically conducting fluid 24 and if this is done, we have a fluid amplifier that does not require fluid control signals which, in turn, means that we have a fluid amplifier that has only one fluid input stream, namely, the power stream.

The use of an electrically conducting fluid for the power stream also facilitates the detection of the power stream in the outlet channels. Reference is now made to FIG. 2 wherein a pair of electro-magnetic devices, generally designated 25 and 26, are respectively mounted around or in close proximity to outlet channels 15 and 16. More specifically, device 25 includes a first coil 27 which is preferably mounted to encircle outlet channel 15 and a second coil 28 positioned adjacent coil 27 and likewise encircles the outlet channel, the input leads of coil 27, designated 27a, being connected to some source of direct current (not shown) and the output leads of coil 28, designated 28a, being connected to some sort of utilization device, such as, in the present instance, a voltmeter or galvanometer 30. In the same way, device 26 includes first and second coils 31 and 32, respectively, whose leads, designated 31a and 32a, are respectively connected to a direct-current source (not shown) and a utilization device 33.

In use, direct current, that is to say, current of substantially constant magnitude, is made to flow through coils 27 and 31, with the result that the magnetic lines of flux thereby produced or established respectively extend through outlet channels 15 and 16 and couple or link with the turns of coils 28 and 32. Consequently, when the power stream is switched from one outlet channel to the other, a change takes place in both D-C magnetic fields and this, in turn, gives rise to the generation of signals in the form of voltages by coils 28 and 32, a positive voltage being generated by the coil encircling the outlet channel into which the fluid has newly entered and a negative voltage being generated in the other coil due to the reverse direction of motion of the fluid. Thus, using the examples previously given, if the fluid 24 is switched from outlet channel 16 to outlet channel 15, then coil 28 would generate a positive voltage pulse, and coil 32 would, on the other hand, generate a negative voltage pulse.

While the outputs from coils 28 and 32 have herein been used to provide an indication of outlet channel flow, it will be recognized by those skilled in the art that these pulses may also be used as control signals for the purpose of switching or controlling the flow in other fluid amplifier devices or the like.

Having thus described the invention, what is claimed is:

1. The combination comprising: a fluid amplifier having an input channel through which an electrically neutral, electrically-conducting fluid flows in a power stream, a chamber connected to said input channel, a plurality of output channels connected to said chamber, means for flowing lsaid electrically neutral, electrically-conducting fluid under pressure through said input channel and through said chamber in laminar flow, and control means for controlling said fluid flow from said input channel to a selected output channel, said control means comprising means for producing in said fluid a magnetic field that has a gradient transverse to lthe direction of fluid flow for deflecting fluid flow to a selected output channel.

2. The device of claim 1 further including a `source of said electrically neutral, electrically-conducting fluid connected to said means for flowing said fluid through said input channel and said chamber.

3. The device of claim 1 wherein said magnetic control means comprises at least one coil positioned outside and adjacent said chamber.

4. The device of claim 1 wherein said magnetic control means comprises a first pair of coil means disposed outside said chamber and directly opposite a second pair of coil means.

5. The device of claim 1 wherein said control means includes means to energize said magnetic field producing means to establish a flow deflecting magnetic force.

6. The device of claim 1 further including output magnetic means disposed about each of said output channels for sensing the presence of fluid therein and generating an electrical signal in response thereto.

7. The device of claim 1 wherein said control means further includes oppositely directed fluid control channels connected to said chamber and substantially perpendicular to the flow of said electrically neutral, electrically-conducting fluid as said fluid enters said chamber.

8. The device of claim 7 wherein a pair of said m'agnetic field producing coils are disposed about each of said control channels.

9. The device of claim 7 further including means to direct a pulse of fluid to one of said control channels.

10. A method comprising providing a fluid amplifier having an input channel through which `an electrically neutral, electrically-conducting fluid flows in a power stream, a chamber connected to said input channel, and a plurality of output channels connected to said cham-ber, and .magnetic field generating means positioned outside lan adjacent said chamber; flowing an electrically neutral, electrically-conducting fluid under pressure through said input channel and through said chamber in laminar flow, deflecting said electrically neutral, electrically-conducting fluid stream into a selected output channel by generating a magnetic field having a gradient transverse to the direction of flow of said power stream by energizing at least one of said magnetic field generating means positioned adjacent Isaid chamber.

11. The method of claim 10 further including detecting the presence of said fluid in an output channel and generating an electrical signal in response thereto.

12. The method of claim 10 further including providingr 7 i 8 generating an electrical signal in response thereto, each of 3,071,154 1/ 1963 Cargill et al. 137-815 said output means comprising a magnetic field generating 3,122,062 2/ 1964 Spivak et al 137-81.5 X coil positioned adjacent said output channel and a Ipickup 3,142,796 7/ 1964 Goldberg et al. 324-34 X coil positioned adjacent said magnetic field generating coil, 3,182,686 5 1965 Zilberfarb 137-81.5 X and detecting the presence of fluid in Ian output channel 5 3,258,685 6/ 1966 Horton 137-815 X with said output magnetic means and generating an 3,266,514 8/ 1966 Brooks 137-815 electrical signal in response thereto. 3,362,421 1/ 1968 Schaier I137-1815 References Cited SAMUEL SCOTT, Primary Examiner UNITED STATES PATENTS 10 2,763,125 9/1956 Kadosch et al. 13H-81.5 X 2,964,985 12/ 1960 Webster 84-1.15

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