US3789883A

US3789883A - Push-pull fluidic logic element and drive unit

Info

Publication number: US3789883A
Authority: US
Inventors: Gregory D De
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1972-10-02
Filing date: 1972-10-02
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05

Abstract

A fluidic logic element and drive unit is disclosed which performs the half adder logic function of a passive AND gate but has a single output capable of giving two distinct output signals. The element has opposed aligned input nozzles and diverters arranged so that an output port is pressurized by the simultaneous presence of input signals at each nozzle and is evacuated by an atomizer effect when an input is present at either nozzle alone. The AND signal is indicated by a pressure at the output, while the OR signal is indicated by a vacuum at the output.

Description

D United States Patent 1 [111 3,789,883

De Gregory Feb. 5, 1974 [54] PUSH-PULL FLUIDIC LOGIC ELEMENT 3,277,915 10/1966 Dockery 137/823 X AND D VE UN 3,323,532 6/1967 Campagnuolo 137/824 X 3,366,130 l/l968 Reader 137/823 Inventor: Donald Lee De g y, Columbus, 3,493,004 2/1970 Hellbaum 137/823 Ohio [73] Assignee: Bell Telephone Laboratories, i ry Examiner-William R. Cline Incorporated, Murray Hill, NJ. Attorney, Agent, or Firm---Cv E. Graves [22] Filed: Oct. 2, 1972 [21] Appl. No.: 294,368 [57] ABSTRACT A fluidic logic element and drive unit is disclosed which performs the half adder logic function of a pas- ..hls3c7/l8/ig Sive AND gate but has a Single output capable of giw ing two distinct output Signals The element has [58] Field of Search 137/822 posed aligned input nozzles and diverters arranged so that an output port is pressurized by the simultaneous presence of input signals at each nozzle and is evacu- [56] References cued ated by an atomizer effect when an input is present at UNITED STATES PATENTS either nozzle alone. The AND signal is indicated by 21 3,128,040 4/1964 Norwood 137/818 pressure at the output, while the OR signal is indicated 3,334,640 8/1967 Phillips 137/824 by a vacuum at the output. 3,626,965 12/1971 Healey 137/823 3,537,465 Moore 137/824 1 Claim, 7 Drawing Figures PATENTED FEB 5 74 SHEET 1 OF 2 PAIENTED 5 74 SHEET 2 0? 2 FIG. 5

PUSH-PULL FLUIDIC LOGIC ELEMENT AND DRIVE UNIT FIELD OF THE INVENTION This invention relates to fluid logic devices and drive units and, more particularly, to such devices and units that perform the half adder logic function of a passive AND gate.

BACKGROUND OF THE INVENTION Passive AND gates are well known and have been used quite satisfactorily in many fluid logic systems. Typical of such gates is that disclosed by A. J. Healey in U. S. Pat. No. 3,626,965 issued Dec. 14, 1971. Two inputs to the gate are at substantially right angles to each other. An OR output is approximately in line with one output and an AND output is at a 45 angle to the inputs.

Such gates possess an inherent limitation based upon their geometric configuration. When a signal appears at either one of the inputs alone, the fluid flow is received by the OR output. If the active input is the one substantially in line with the OR output, the pressure recovered will be greater than under the circumstance where the other input is active alone. This occurs because the other output produces flow away from the OR output which must be redirected to the OR output. This generates perceptible fluid drive loss due to friction.

If the input pressures are adjusted to give approximately equal output signals in the OR condition, when both inputs appear simultaneously the AND signal will be disturbed. Since the AND output most effectively receives the combined flow from both simultaneous inputs at a 45 angle, the simultaneous inputs should be of approximately'equal pressure to produce a combined flow toward the AND output. Movement of the AND output to another position representing an inequality of input pressures would have an undesired effect on the OR condition. Such a geometric change could render the gate ineffective for many applications.

Since these gates are typically only a building block, or module, of a more complex logic system, substantial plumbing is required to connect the two outputs of the gate to other elements of the system. The AND and OR outputs cannot simply be connected together to simplify the interconnections because it would be impossible to distinguish between the two distinct signals.

It is therefore an object of my invention to provide a fluidic half adder logic device and drive unit in which the output signal strength will be uniform regardless of the input condition.

It is also an object of my invention to provide a device in which a single output channel will produce both the AND and OR signals.

SUMMARY OF THE INVENTION A bistable fluid logic element having a single output port is pressurized by the simultaneous presence of two input signals and evacuated by an atomizer effect when either input is present alone. Monitoring the pressure of the single output port will permit the AND and OR input conditions to be distinguished, and a bistable output signal to be produced.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 shows a plane view of a logic element embodying my invention;

FIG. 2 shows the element of FIG. 1 with the flow pattern indicated for one input;

FIG. 3 shows the element of FIG. 1 with the flow pattern indicated for the other input;

FIG. 4 shows the element of FIG. 1 with the flow pattern indicated for both inputs;

FIG. 5 indicates the element of FIG. 1 connected to a fluid switch with the flow pattern indicated for one active input;

FIG. 6 shows the element of FIG. 1 connected to a fluid switch with the flow indicated for the other active input; and

FIG. 7 shows the element of FIG. 1 connected to a fluid switch with the flow indicated for both inputs simultaneously present.

DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT For purposes of clarity, the device of FIG. 1 has been shown as having a transparent cover. This was done in the interests of clearly showing the configuration of the inside chamber without the confusing presence of cross-section lines and should not be taken as any limitation upon the material suitable for constructing such devices. Any material conventionally used for fluidic devices would be suitable for this device as well.

Device 11 consists of a first fluid input 12 and a second input 13. A first output 15 is positioned to receive flow from input 12. A second output 16 is positioned to receive the flow from input 13. Midway between

inputs

12 and 13 is a signal channel 20. As can be seen, device 11 is symmetrical about an imaginary central vertical axis. As a result, the output pressure of signals received in

outputs

15 and 16 will be equal for equal pressures at

inputs

12 and 13. This results from the similarity of the flow paths for each input-to-output combination.

When fluid flows from input 12 alone, the flow pattern of FIG. 2 is established. As can be seen, the flow issues from a nozzle 25 and flows toward signal channel 20. As the flow approaches channel. 20, it encounters curved wall or flow diverter 26. The flow is deflected by wall 26 from a. straight line path to be received at output 15. As the flow moves past the orifice 21 of signal channel 20, it produces an atomizer effect. That is, any fluid contained in channel 20 tends to be entrainedby the fluid moving past the orifice 21 and is carried with it. This produces a pressure which is stable, but below ambient, in channel 20.

A phenomenon similar to that just described occurs when fluid flows from input 13 alone. As seen in FIG. 3, the flow issues from a nozzle 29 and proceeds toward signal channel 20. The flows from

nozzles

25 and 29 are directed along a common path, although in opposite directions in accordance with the symmetry described above. Just prior to reaching orifice 21 at the input to channel 20, the flow is deflected from its straight line path by a curved wall or flow diverter 30 to be received by output 16. Once again the atomizer effect of the fluid flow moving past orifice 21 produces a pressure below ambient, or negative pressure, in signal channel 20.

If fluid flows simultaneously from

inputs

12 and 13, the flow pattern shown in FIG. 4 is produced. In this situation the flow from

nozzles

25 and 29 impact in the region of orifice 21. The impact of these two flows produces a turbulent condition in the vicinity of the input to channel 20. The effect of this turbulence is to produce a stable, but higher than ambient, pressure in signal channel 20. As can be seen, the fluid exits device 11 via the outputs and 16 although the well defined jets issuing from inputs l2 and 13 are disturbed.

The flow which exits via

outputs

15 and 16 is of no particular import and is returned to a fluid reservoir, or wasted to the ambient. However, monitoring output signal channel 20 will produce distinctive signal levels depending upon the input flow conditions. A pressure below ambient in channel 20 is indicative that one, but only one, input is active while a pressure above ambient is indicative that both inputs are active simultaneously.

A particular advantage of logic element 11 results from the ease of connection of signal channel 20 to other elements of a fluidic system. By way of illustration, FIGS. 5 through 7 show element 11 connected to a fluid switch 40. Switch 40 is a mercury drop switch such as was disclosed by P. J. Campbell in U. S. Pat. No. 3,583,420 issued June 8, 1971, and by H. Winter in U. S. Pat. No. 3,539,743 issued Nov. 10, 1970. Such switches include a chamber having a configuration similar to that of an hourglass in which a drop of mercury sufficient to fill one side is confined. Electrical contacts, closeable through the mercury, are positioned in one side of the chamber. By applying appropriate fluid signals, the mercury drop may be selectively moved from side to side within the chamber to make and break continuity through the contacts.

Switch 40 is illustratively shown as a double switch suitable for simultaneously switching two electrical connections, for example the tip and ring leads of a telephone connection. For purposes of illustration, let us assume that element 11 and switch 40 represent an element of a larger switching matrix in which input 12 is connected to a column or X element of the matrix and input 13 connects to a row or Y element of the matrix.

Chamber 41, the left half of switch 40, is used to move mercury droplet 45 to selectively switch the tip lead of the telephone station (not shown) associated with switch 40. The left half of chamber 41 includes two contacts 43 which are bridged by the conductive mercury droplet 45 when it is positioned in the left side of chamber 41. When droplet 45 is positioned on the right side of cavity 41, continuity between contacts 43 is interrupted.

Chamber 42, containing mercury droplet 46, is similar to chamber 41. Contacts 44, positioned on the right side of cavity 42, are bridged when the droplet 46 is in the right side of cavity 42, closing a path to the ring lead of the associated telephone station. When droplet 46 is moved to the left side of chamber 42, continuity is interrupted between contacts 44.

As can be seen in FIG. 5, when flow is present at input 12 alone the negative pressure produced in signal channel 20 causes drop 45 to be positioned in the right side of chamber 41 and drop 46 to be positioned in the left side of chamber 42. This positioning interrupts continuity between contact pairs 43 and 44. As can be seen in FIG. 6,

mercury droplets

45 and 46 are similarly po- Sitioned when flow is present only at input 13. (This is the OR condition for device 11.)

When flow is simultaneously present at inputs 12 and 13 (the AND condition for device 11), the flow pattern of FIG. 7 occurs. As described earlier, a positive pressure is produced in channel 20 due to this input condition. Drop 45 is moved to the left side of cavity 41 and drop 46 is moved to the right side of cavity 42. In this position the tip and ring leads are respectively connected through contact pairs 43 and 44. This would correspond to a signal condition in which the X and Y matrix elements corresponding to the associated telephone station are simultaneously energized. (

Inputs

12 and 13 both active). This would occur only under those conditions in which it was desired to establish contact with the associated station of switch 40. This happens when the unique X-Y combination representing the row and column address of the station has been activated.

It should be apparent that the size and shape of the flow diverters, illustratively shown by curved walls 26 and 30, may be varied. Any desired relationship between vacuum and pressure recovery, or the absolute magnitude of the output signals, can be produced by selection of a corresponding size and shape.

It should also be apparent that element 11 comprises both a device driving unit and a fluid logic buildingblock element. Any fluid logic designer with ordinary skill could devise a variety of systems in which this element could be effectively utilized without departing from the spirit and scope of this invention.

What is claimed is:

l. A fluidic half adder gate comprising a first input to selectively produce fluid flow;

a second input to selectively produce fluid flow;

a chamber;

a first nozzle connecting the first input to the chamber to generate a first fluid jet into the chamber when fluid flow is produced in the first input;

a second nozzle connecting the second input to the chamber to generate a second fluid jet into the chamber when fluid flow is produced in the second input, the second nozzle being located in spaced relationship to the first nozzle so that the second jet is generated opposite in direction, but substantially coaxial to the first jet;

an output connected to the chamber to receive the flow from the generator jets and permit fluid to leave the chamber;

a signal channel separate from said chamber output to produce two stable fluid output signals, the first signal being produced in response to the presence of a single generated jet and the second signal being produced in response to the simultaneous presence of both generated jets;

closed pressure utilization means connected to said signal channel for responding to changes in pressure in said signal channel;

an orifice to connect the signal channel to the chamber, the axis of the orifice being substantially perpendicular to the mutual axis of generation of the j a pair of diverters located on opposite sides of the orifice to divert the jets from their axis of generation to be received by the output;

generated jet past the orifice produces a stable pressure below ambient in the signal channel and the turbulence created by the impact of the simultaneously operated jets produces a stable presure above ambient in the signal channel.

Claims

1. A fluidic half adder gate comprising a first input to selectively produce fluid flow; a second input to selectively produce fluid flow; a chamber; a first nozzle connecting the first input to the chamber to generate a first fluid jet into the chamber when fluid flow is produced in the first input; a second nozzle connecting the second input to the chamber to generate a second fluid jet into the chamber when fluid flow is produced in the second input, the second nozzle being located in spaced relationship to the first nozzle so that the second jet is generated opposite in direction, but substantially coaxial to the first jet; an output connected to the chamber to receive the flow from the generator jets and permit fluid to leave the chamber; a signal channel separate from said chamber output to produce two stable fluid output signals, the first signal being produced in response to the presence of a single generated jet and the second signal being produced in response to the simultaneous presence of both generated jets; closed pressure utilization means connected to said signal channel for responding to changes in pressure in said signal channel; an orifice to connect the signal channel to the chamber, the axis of the orifice being substantially perpendicular to the mutual axis of generation of the jets; a pair of diverters located on opposite sides of the orifice to divert the jets from their axis of generation to be received by the output; a first wall to connect the first nozzle to one of the diverters so that the first jet attaches to the first wall and flows past the orifice; and a second wall to connect the second nozzle to the other diverter so that the second jet attaches to the second wall and flows past the orifice; whereby the atomizer action of the flow of a single generated jet past the orifice produces a stable pressure below ambient in the signal channel and the turbulence created by the impact of the simultaneously operated jets produces a stable presure above ambient in the signal channel.