US3703907A

US3703907A - Fluid amplifiers

Info

Publication number: US3703907A
Authority: US
Inventors: George B Richards
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-30
Filing date: 1970-10-30
Publication date: 1972-11-28
Anticipated expiration: 1989-11-28
Also published as: JPS57161308A; NL172982C; CA936806A; DE2153877B2; JPS6038563B2; FR2111973B1; NL7113764A; FR2111973A1; GB1344302A; JPS5749764B1; NL172982B; ZA716464B; AU3408771A; BE774095A; DE2153877C3; IT940975B; AU465009B2; CH527372A; DE2153877A1

Abstract

A fluid amplifier includes an inlet for directing a laminar fluid power stream along a predetermined axis. A control means downstream of the inlet includes a wall spaced laterally outward of the power stream and at least partially enclosing same with a guide surface portion of the wall curving outwardly away from the predetermined axis. An access opening to the power stream in the wall of the control means permits introduction of a perturbant signal to thereby alter the power stream from a laminar to a substantially turbulent flow pattern of a significantly greater cross-sectional dimension. This transition results in formation of a low pressure condition between the stream and the guide surface of the wall causing the stream to attach to the guide surface and divert away from the predetermined axis. Several embodiments and further features are disclosed.

Description

United States Patent Richards Nov. 28, 1972 [54] FLUID AMPLIFIERS 3,415,268 12/1968 Tweed 137/815 X 3 429 323 2/1969 Mott ..l37/81.5

72 I t George B. R! 1181113, 1212 Ran h I 1 Road, Lake "L 60045 c 3,517,686 6/1970 Lyman et al ..,.137/s1.s

[22] Filed: 30, 1970 Primary Examiner-William R. Cline I 21 AppL 5 37 Attomey-Jerry D. Hoiser Related us. Application Data 57 ABSTRACT [63] Continuation-impart of Ser. No. 840,119, June A fl id amplifier includes an inlet for directing a 19, 1969, which is a continuation-in-part of Ser. No. 724,385, April 26, 1968, abandoned.

laminar fluid power stream along a predetermined axis. A control means downstream of the inlet in- 1 eludes a wall spaced laterally outward of the power stream and at least partially enclosing same with a guide surface portion of the wall curving outwardly away from the predetermined axis. An access opening to the power stream in the wall of the control means permits introduction of a perturbant signal to thereby alter the power stream from a laminar to a substantially turbulent flow pattern of a significantly greater cross-sectional dimension. This transition results in formation of a low pressure condition between the stream and the guide surface of the wall causing the stream to attach to the guide surface and divert away from the predetermined axis. Several embodiments and further features are disclosed.

27 Clains, 17 DrawingFigures PAIENTEDnuvzwz I "3.703.907

SHEET 10F 3 Richorps PATENTEBuuv28 i912 3.703.907

SHEET 2UP 3 J v I Inventor Ricyds Inventor George B. Rlchordsv PATENTED um 28 I972 SHEET 3 BF 3 FLUID AMPLIFIERS CROSS REFERENCE TO RELATED APPLICATIONS The present application is a continuation-in-part of 5 INTRODUCTION The present invention is directed generally to fluid amplifiers and, more particularly, is directed to fluid amplifiers of a new class or kind, which have particular utility as liquid level sensing devices. Accordingly, the fluid amplifiers will be disclosed in the foregoing context although the broader principles of the invention will be recognized by those skilled in the art.

SUMMARY OF THE INVENTION The present invention is directed to a fluid amplifier having an inlet and an outlet zone and adapted for use in a liquid reservoir to sense a change of liquid level therein. More specifically, the amplifier comprises an inlet means including an inlet flow channel adapted to be positioned adjacent the desired liquid sensing level in the reservoir and adapted for directing a substantially laminar power stream of a predetermined crosssectional configuration substantially transversely to the surface of the liquid in the reservoir. The inlet means is constructed and arranged such that the fluid power jet is abruptly altered to a substantially turbulent flow pattern of a materially greater cross-sectional area than that of a predetermined area when the liquid level in the reservoir rises to the sensing level. There is also provided an outlet means spaced from the inlet means and including a first outlet aligned with the inlet flow channel. The liquid from the inlet flow channel develops a fluid pressure signal of a first predetermined value at the first outlet of the outlet means when the liquid level in the reservoir is below the sensing level and a signal of a second, lesser value when the liquid is at the sensing level. 1

In accordance with a further aspect of the invention, a fluid amplifier comprises an inlet means having a fluid passageway of a predetermined cross-sectional area for developing a substantially laminar power stream of a corresponding cross-sectional area and for directing the power stream along a predetermined axis. The amplifier further comprises control means including wall means spaced laterally outward of the fluid power stream by a predetermined distance and at least partially enclosing the fluid power stream. The wall means includes a guide surface portion curving outwardly away from the predetermined axis as well as an access opening to the fluid power stream which is positioned on the side of the stream opposite that of the guide surface portion. The access opening is provided for introducing a perturbant signal to alter the power stream from a substantially laminar flow to a substantially turbulent flow pattern of a cross-sectional area substantially greater than that of the predetermined area. The wall means is arranged such that a substantially enclosed spade if formed between the turbulent power stream and the wall means causing a low pressure condition to develop therebetween and the power stream to attach to the guide surface and divert away from the predetermined axis. Thus, anyoontrol or actuating mechanism positioned on the predetermined axis of the power stream receives a substantial fluid pressure signal in the absence of a perturbant signal and a zero fluid pressure signal in the presence of a perturbant signal. The perturbant signal may, for example, result from the liquid in a reservoir rising to a level so as to flow through the access opening and into intimate contact with the power stream.

Other aspects and features of the invention including a fluidic oscillator are disclosed in detail later herein.

BRIEF DESCRIPTION OF THE DRAWINGS The novel features of the present invention are set forth with particularity in the appended claims. The invention together with further objects and advantages thereof may best be understood, however, by reference to the following description taken in conjunction with the accompanying drawings in the several figures of which like reference numerals identify like elements and in which:

FIG. 1 is an elevational view, partly in section, of one embodiment of the present invention;

FIG. 2 is an perspective view of a prefered embodiment of a fluid amplifier according to the present invention;

FIG. 2a is a detail view illustrating an alternate form of the control means of the fluid amplifier of FIG. 2;

FIGS. 3a and 3b are cross-sectional views taken along liens 3a-3a of FIG. 2 and depicting the operational characteristics of the fluid amplifier of FIG. 2 in the environment of a liquid reservoir;

FIG. 4 is a partially schematic view of a fluid amplifier, similar to that of FIG. 2, but arranged to operate as a fluidic oscillator;

FIG. 5 is a perspective view, partly in section illustrating another perferred embodiment of the present invention;

FIGS. 5a 5c, inclusive, are cross-sectional views taken along lines Sa-Sa of FIG. 5 and illustrating the operational characteristics of the fluid amplifier in the sensing of a liquid level within a reservoir;

FIG. 6 is a perspective view, partly in section, of a further embodiment of the present invention;

FIGS. 6a-6c, inclusive, are cross-sectional views taken along lines 6a-6a of FIG. 6 and again illustrating the operational characteristics of the fluid amplifier as a liquid level sensing device;

FIG. 7 is an elevational view partly in section of yet another embodiment of the present invention and further including an actuating means selectively operated by the fluid amplifier;

7 FIG. 7a is a sectional view taken along lines 7a-7a of FIG. 7; and

FIG. 7b is an elevational view similar to that of FIG. 7, and is useful in explaining the operational characteristics of the fluid amplifier.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, the fluid amplifier 10 there illustrated is identical to that disclosed in the aforementioned application Ser. No. 840, l 19. As there described, the amplifier includes serially aligned inlet, interaction and outlet zones, respectively, comprising the inlet means 12, the free space 14 separating the inlet and outlet means, and the outlet means 16. As seen in the drawing, the outlet means 16 is formed from a pair of hollow conduit sections positioned in adjacent parallel relationship with hollow connector joining the two sections to provide a liquid flow path from a receiving orifice of the outlet to an outlet flow channel of a inlet-outlet header structure 18 of the amplifier. The inlet 12 is similarly formed from a hollow conduit section with one end suitably secured to the header structure 18. The opposite end of the inlet conduit 12 is restricted in cross-section by a plug which defines a nozzle-like orifice for directing the exit flow across the free space of the interaction region 14 toward and axially aligned and structurally similar orifice plug of the outlet flow conduit 16.

As explained in the above identified application, the header structure 18 provides a convenient means for effecting a sealed installation of the amplifier within a closed, pressurized tank, such as the chill tank of a carbonated beverage dispensing system. It will be understood, however, that the header 18 forms no part of the present invention and merely serves as a convenient means for utilizing the amplifier in the described, exemplary environment. In other applications, it may be desirable to provide entirely separate structures for the inlet and outlet flow conduits.

In the illustrated structure, the lower end of the header 18 is threaded so as to be received in threaded and sealed engagement with a correspondingly threaded opening of a closed tank (not shown). Suitable inlet and outlet fluid pressure lines (not shown) are connected to threaded inlet and

outlet bores

18a and 18b, respectively, of the header 18 to thereby provide a fluid flow path through the amplifier 10in the direction indicated by the arrows in the drawing. In this regard and as denoted in the drawing by the conically diverging solid lines extending between the inlet and outlet flow orifices, the fluid power jet exiting from the inlet flow conduit 12 normally diverges in a conical fashion to a limited extent before impingement on the orifice plug of the outlet conduit 16. The unit pressure in the outlet flow channel 16 is reduced relative to that at the orifice of the inlet conduit 12 in correspondence with the increase in cross-sectional area of the jet.

To the extent .above described, the amplifier 10 is conventional; however, it has been found that certain surprising and highly desirable results obtain on associating the amplifier 10 in a unique manner with a fluid reservoir. More particularly and in accordance with the present invention, the fluid amplifier 10 is positioned within a fluid reservoir or the like such that the axis of the fluid jet is transverse to the surface of the liquid herein. Additionally, the terminus of the inlet flow channel 12 is located at a point immediately above a desired liquid sensing level within the reservoir. The desired liquid sensing level for the amplifier 10 is schematically illustrated in the drawing by the horizontal dashed line immediately below the terminus of the inlet flow conduit 12.

With the above arrangement, it has been found that the liquid jet flowing between .the inlet and outlet orifices substantially maintains the illustrated solid line conical configuration for any fluid level in the reservoir lying below the predetermined sensing level, i.e., the horizontal dashed line. In other words, the fluid pressure in the outlet conduit 16 is reasonably constant as a liquid level within the reservoir moves upwardly from a point lying vertically below the orifice plug of the outlet conduit 16 through the free space of the interaction region 14 toward the sensing level.

It has been observed, however, that when the liquid level rises to the sensing level, the focus area of the jet, i.e., the cross-sectional area of the jet at the point of impingement on the orifice plug of the outlet conduit 16, increases markedly as denoted by the dotted lines in the drawing thereby causing a corresponding reduction in the pressure in the outlet flow conduit 16.

By way of example, in one constructed embodiment of the fluid amplifier 10 wherein the inlet and outlet orifice apertures were three thirty-seconds inch in diameter, the interaction region spacing 14 was oneinch and the liquid was water under a pressure of approximately 5 psi, it was observed that the liquid jet normally diverged to a focus area of three-sixteenths of an inch but that when the reservoir liquid attained the sensing level the focus area increased almost instantaneously to three-eighths inch in diameter. In terms of fluid signal pressure, the foregoing increase in the focus area resulted in a relative pressure change on the order of four to five times. It was further observed that the sensing level occurred at approximately 0.010 inch below the end of the plug in the inlet conduit 12.

It is currently believed that the above described operational characteristics are related to the differing character of the fluid entrained by the amplifier jet when the reservoir liquid level is respectively below and at the sensing level. Specifically, at all liquid levels below the sensing level, the jet emerging from the nozzle orifice of the amplifier inletl2 entrains only the surrounding gas or air within the system. On the other hand, when the liquid reaches the sensing level, the surrounding gas or air is substantially precluded access to the jet. Hence, the surrounding liquidis drawn toward entrainment with the jet. As a consequence of its greater mass, the liquid moves more slowly than the gas and thereby materially reduces the circumferential pressure around the jet, causing the jet to conically diverge from its normal configuration in a manner denoted schematically by the dashed lines in the drawing.

The abrupt change in fluid pressure at the outlet flow conduit 16 attendant the liquid rising to the sensing level provides a fluid pressure signal that may be used to operate a valve or the like to preform a predetermined control function, such as shutting off the inlet flow to the liquid reservoir. Thus, flow to chemical or fuel tanks may automatically be terminated with filling of the tank to a preselected level while refill may automatically be initiated with only a very slight reduction in the liquid in the tank.

Although the amplifier of FIG. 1 provides a marked change in fluid signal pressure attendant the liquid rising to or receding from the sensing level, a positive fluid pressure signal is always developed at the outlet conduit 16. In certain applications, it is highly desirable that no signal whatsoever be developed at the outlet upon occurrence of the sensed event. A fluid amplifier displaying such a mode of operation is disclosed in FIG. 2. This amplifier although bearing superficial structural similarity to the amplifier of FIG. 1 is materially different in certain vital respects, as presently will be seen.

The fluid amplifier 20 depicted in FIG. 2 is constructed for application to a like environment as that of the amplifier 10, namely, the sensing of liquid level within an enclosed, pressurized tank. Indeed, the amplifier 20 may directly be substituted for the amplifier in the system disclosed in the earlier mentioned patent application Ser. No. 840,1 19. As a result of such substitution, certain simplications may be made in the system as will be apparent to these skilled in the art on considering the aforesaid disclosure.

To the above end, the fluid amplifier includes a common inlet-outlet header structure 22 suitably coupled to inlet and outlet

fluid pressure lines

24 and 26, respectively. The lower end of the header 22 is threaded to permit sealed securement within a threaded opening of a pressurized tank. The amplifier 20 also includes an inlet means in the form of a hollow conduit 28 interconnected to the inlet pressure line 24 through the header structure 22. A lower end of the inlet conduit 28 is return bent to direct a fluid power stream toward an outlet means 30 which is spaced from and in axial alignment with the inlet flow channel. Herein, the outlet means is a conduit 30 interconnected to a flow line 26 through the header 22 and thence to a suitable actuating or control mechanism (not shown). Of course, the outlet means may include an actuating or control mechanism positioned in the vicinity of the fluid stream emanating from the inlet conduit 28, as opposed to the illustrated arrangement wherein the control or actuating mechanismis located at some remote position and receives the fluid pressure signal through

conduit

26 and 30.

The present embodiment of the invention is distinguished from that of FIG. 1 by the presence of a control means comprising a portion of a member 32 which is secured to the terminus of the inlet conduit 28. To the extent visible in FIG. 2, the member 32 is seen to have a bell-shaped mouth portion opening towards the outlet conduit 30 and an access opening 32a to the fluid power stream extending through the lateral side wall of the member 32. In the embodiment of FIG. 2, the access opening 32a is in the form of a horizontal cylindrical bore in the side wall of the member 32. However, it has been found that a suitable access opening may be provided in a variety of other forms and shapes. One of the most surprising of these alternatives is that illustrated in the detail view of FIG. 2a wherein a portion of the side wall of the member 32' has literally been cutaway exposing an entire circumferential segment of the fluid power stream. Except for the cut-away portion of the member 32 may be identical to that of member 32. Of course, in practice if the member 32 is molded or the like, the wall means would not be cut-away but merely omitted in the molding or other manufacturing process. Additionally, it has been found that the portion of the wall which is omitted should preferably not exceed to per cent of the circumferential dimension of the wall in order for proper operation to occur.

A more complete understanding of the structure of the control means as well as the operational characteristics of the amplifier 20 may be had by referring now to FIGS. 3a and 3b. As seen in FIG. 3a, the lower end of the member 32 is provided with a central bore for snugly receiving the terminal section of the inlet flow conduit 28. For convenience, a nozzle-like orifice for defining the power stream is formed by providing a reduced diameter central bore of circular cross-section within the member 32. This narrow diameter bore within the member 32 is equivalent to the orifice plug in the embodiment of FIG. 1 and serves to develop a substantially laminar fluid power stream of a cross-sectional configuration and area corresponding to that of the nozzle, the resultant power stream being directed along a predetermined axis toward the coaxially aligned outlet conduit 30.

The member 32 includes a wall portion 32b spaced laterally outward of the fluid power stream by a predetermined distance and at least partially enclosing the power stream. The wall 32b commences at the outward step adjacent the terminus of the orifice in the lower end of the member 32. From this point, the wall 32b is cylindrical for a portion of its upward extent and then gradually flares outwardly to form a bell-mouth opening. The geometry of the walls 32b may take other configurations depending upon the environment of use of the amplifier, the operational characteristics desired and the like. For example, the fluid jet may be of rectangular cross-sectional and the walls 32b similarly configured.

In operation, the nozzle-like orifice formed in the base of the member 32 projects a cylindrical, laminar power jet along an axis coincident with that of the reduced diameter central orifice in the outlet flow channel 30. The resultant fluid pressure signal developed in the outlet flow conduit 30 may be used to actuate a pressure responsive valve or other conventional control apparatus to perform a predetermined control function, as earlier explained. The power jet continues to flow in the manner described until and unless a perturbant signal is introduced through the access opening 32a to alter the character of the fluid power stream from its normally laminar flow condition to a substantially turbulent flow pattern having a crosssectional area substantially greater than that of the original power stream. In this regard, it has been found that the relative dimensions of the turbulent power stream and the wall substantially preclude air or other secondary fluid from flowing downwardly between the wall and power stream to replace that entrained by the stream adjacent the inlet. Accordingly, 32b a low pressure condition develops between the turbulent power stream and most particularly that portion of the wall 32b opposite the access opening 32a. The low pressure condition causes the power stream to divert away from its central axis and to attach to the guide surface of the wall 32b.

An exemplary form of perturbant signal is efiected by the liquid level within a reservoir or the like rising to a level to at least partially cover the access opening 32a. It has been found that the precise level at which the transition from a laminar to a turbulent flow occurs is very sharply defined for a particular amplifier and may be determined empirically for each amplifier construction.

In the present embodiment it has been found that the fluid power stream remains in a laminar flow condition for all liquid levels in the reservoir below that of the access opening and even up to a point as shown in FIG. 3a where a minor portion of the access opening is submerged. However, as shown in FIG. 3b when a liquid level rises to a point just below the upper surface of the access opening 32a, the fluid power stream abruptly changed to a turbulent flow pattern and the power stream attaches to the guide surface portion of the wall 32b in a manner analogous to that of the Coanda wallattachment efiect.

In one constructed embodiment of the present invention, the central bore in the member 32 for defining the laminar power stream was three thirty-seconds inch in diameter as was the orifice in the opposing outlet means 30. The wall portion 32b was of an initial diameter of one-eighth its terminal portion gradually flaring outwardly a one-fourth diameter in the manner shown. With the structural proportions indicated and a flow of one gallon per minute at the amplifier inlet, a signal of 10 psi was produced at the outlet under quiescent conditions. On the other hand, when the power jet is diverted away from the axis of the outlet conduit 30, the signal pressure within the outlet abruptly falls to zero value.

Thus, the present embodiment of the invention provides a truly digital operating characteristic while retaining the highly desirable feature of being responsive to a single, discrete liquid level within the reservoir. Also, rather surprisingly it has been found that a mere closing or covering of the access opening 32a has no effect on the character or direction of flow of the fluid power stream. In other words, opening and closing the access opening 32a has virtually no effect on the magnitude of the fluid pressure signal at the outlet 30. A further unique operating characteristic of the amplifier is that the power stream attaches to a portion of the wall 32b which is opposite that of the access opening 32a.

In terms of the theory of operation, it is presently believed that the transition of the power stream from a normally laminar to a turbulent flow pattern is caused by the same phenomenon as earlier explained in connection with the embodiment of the invention shown in FIG. 1. In the present embodiment, however, the transition has the further effect of materially retarding the flow of secondary fluid downwardly along the walls 32b to a point adjacent the base of the power stream to replace that fluid entrained by the power stream. As a consequence, a low pressure condition tends to develop adjacent the power stream base but this condition develops more rapidly on the side of the power stream opposite that of the access opening since liquid and a small portion of secondary fluid is able to at least partially satisfy the low pressure condition created on this side of the stream. As a consequence, the power stream is always diverted to a guide wall positioned approximately 180. from the access opening.

The orientation of the amplifier 20 relative to the surface of the liquid reservoir is not critical to its operation although if the amplifier is used to sense liquid level, it is preferable to have the amplifier oriented approximately perpendicular to the liquid surface. Additionally, the operating characteristics of the amplifier 20 are basically similar to that just described if the amplifier is inverted in the reservoir, i.e., the inlet-conduit 8 28 is positioned above the surface of the liquid and the outlet conduit below the liquid surface. A similar effect may also be achieved by coupling the member 32 to the terminus of conduit 30 and reversing the direction of fluid flow through the amplifier.

A perturbant signal may be introduced to the fluid power stream other than by the displacement of a liquid level in a'reservoir. An example of such an arrangement is disclosed by thefluid amplifier 40 of FIG. 4. The fluid amplifier here shown is basically similar to that of the embodiment of FIG. 2. Specifically, there is provided an inlet flow channel 42 which is seated in the receiving bore of an annular member 44. The member 44 is provided with a reduced diameter bore centrally disposed relative to the inlet flow channel 42 to define a cylindrical orifice or nozzle to fashion the fluid power stream to a preselected cross-sectional dimension. A bore 44a on the side wall of the member 44 provides the access opening through which a perturbant signal is introduced to the power stream. An interior wall portion 44b of the member 44 is stepped outwardly immediately above the inlet orifice for the fluid power jet extends for a moderate distance as a cylindrical passage and then gradually flares outwardly to a conical or bellmouth opening.

The means for introducing the perturbant signal to the amplifier 40 is arranged so as to cause the amplifier to operate as a fluidic oscillator. More specifically, a

lower end of a conduit 46 is seated within the bore of the access opening 44awhile the upper end of the conduit is connected to a liquid supply tank or the like 48 through a metering valve-50. By means of the valve 50, individual and separate units or droplets of fluid are advanced to the fluid power stream, as schematically indicated by the separate droplets in the conduit 46 extending from the metering valve to the power stream. As again schematically shown on the drawing, impingement of a unit of fluid on the power stream abruptly alters the stream from a laminar to a turbulent flow condition with the result that the stream attaches to the opposite side wall of the member 44 and diverts away from its normal straight line path. The dimensional spacing between the droplets advancing along the ho]- low conduit 46, denoted in the drawing by the dimensional unit, determines the rate or frequency of oscillation of the amplifier 40. It will be recognized by those skilled in the art that additional kinds of perturbant signals may be utilized to trigger the various amplifiers disclosed herein.

Referring now to FIG. 5, there is illustrated a fluid amplifier generally similar to that disclosed in FIG. 2 but wherein the fluid power stream is of a rectangular as opposed to a circular cross-section. The amplifier 50 comprises a pair of

laminar plates

52 and 54 forming the top and bottom walls'of the amplifier. Intermediate the

plates

52 and 54 there is sandwiched a member 56 which is contoured to define the flow passages as well as the control and guide surfaces for the fluid power stream. Specifically, a circular bore 56a in the member 56 connects to a fluid inlet line 58 which extends through the plate 52. A slotted passage in member 56 communicates with the inlet and cooperates with

plates

52 and 54 to provide a fluid flow orifice of rectangular cross-section. immediately about and to the right-hand side of the orifice, the member 56 is notched and then arcuately curved to define a guide surface 56c, as seen in the drawing. On the left-hand side of the orifice, the member 56 is formed to provide a horizontal plateau 56b. The member 56 and the

plates

52, 54 cooperate to enclose the power stream on three sides while the remaining side is open above the level of the plateau 56b to provide the required access opening to the power stream.

Looking now to FIG. a, the fluid amplifier 50 is illustrated in the environment of a liquid reservoir, the liquid within the reservoir being below the level of the plateau 56b of the amplifier. Under these conditions, the rectangular fluid power jet emitted from the inlet of the amplifier is directed vertically along a predetermined axis and is of a substantially laminar flow pattern. As shown, the curved guide surface portion 560 is laterally spaced from the fluid power jet so that air entrained by the fluid power jet in the region adjacent the notch underlying the curved guide surface 56c is replenished by air flowing into this region along the narrow space between the power stream and the curved guide surface. A suitable outlet means and control apparatus (not shown) are positioned to receive the power jet fluid.

When the liquid level within the reservoir rises above the plateau 56b to the predetermined sensing level as seen in F IG. 5b, the power stream is altered to a turbulent flow pattern of a sufficiently large cross-sectional dimension as to intercept the curved guide surface 560. Under these conditions, air or other secondary fluid within the system is precluded access to the notched space underlying the guide surface 56c causing a low pressure condition to develop within this region. The resultant pressure gradient across the power stream results in attachment of the fluid jet to the curved guide wall 56c and diversion of the power stream away from its vertical axis, as shown in FIG. 50. Again the liquid level at which the switching of the power stream occurs is very precise for a given amplifier construction. It will also be recognized by those skilled in the art that the switching time for the amplifier may be adjusted by adjusting the size of the enclosed space, the contour of the guide wall 56c as well as by adjusting other parameters such as the fluid viscosity.

A fluid amplifier basically similar to that just described is illustrated in FIG. 6. The fluid amplifier 60 there shown includes a pair of opposed

laminar plates

62 and 64 which define the upper and lower walls of the amplifier. The interior flow passageways of the amplifier are defined by a pair of spaced

members

66 and 68. The member 66 includes a cylindrical bore 660 coupled to a fluid inlet conduit 70 through a suitable aperture in the plate 62. A slotted passageway in the member 66 communicates with the cylindrical bore 66a to define in cooperation with the

plates

62 and 64, an inlet orifice of rectangular cross-section. Immediately downstream of the inlet orifice, the left-hand side of the member 66 is formed as a horizontal plateau 66b while the right-hand side of the member 66 is stepped in the same plane as the plateau of 66b and a vertical guide pillar 66c rises vertically from the step. The pillar 66c and the

plates

62 and 64 cooperate to partially enclose the power stream; an access opening to the power stream is provided by the open space between

plates

62 and 64 and above the plateau 66b.

The member 68 serves as an outlet flow divider and to this end is of a generally triangular construction with one vertex oriented to face the oncoming fluid power stream emitted from the rectangular inlet passageway. As shown most clearly in FIG. 6a, the vertex of the triangular member 68 is offset slightly to the right of the axis of the fluid power stream such that the stream normally intercepts the member 68 to the left-hand side of the vertex and the stream is diverted in its entirety toward a left-hand fluid outlet passageway. A righthand fluid passageway is formed between another side wall of the triangular member 68 and the vertical pillar 660.

In operation, a substantially laminar fluid power stream of a predetermined cross-sectional area is projected from the inlet passageway toward the triangular flow diverter 68. Since the member 68 is laterally offset relative to the fluid power stream, the power stream is diverted in its entirety into the left-hand fluid passageway of the amplifier, shown in FIG. 6a. However, when a perturbant signal is introduced to the fluid power stream through the access opening, the power stream is altered to a turbulent flow condition with a resultant increase in cross-sectional dimension so that the power stream is now split by the vertex of the member 68 with a portion of the fluid flow exiting from each of the outlet passageways. As illustrated in FIG. 6b, this perturbant signal may result from the liquid level within the reservoir rising above the plateau 66b and into intimate contact with the fluid power stream. The liquid flowing out of the right-hand passageway of the amplifier 60 in FIG. 6b substantially precludes a secondary fluid such as air from flowing down the channel passageway to replenish the air entrained by the stream in the region between the stream and the vertical pillar 66c. Accordingly, a low pressure condition develops within this region causing the fluid power stream to be diverted in its entirety to the right-hand outlet, as shown in FIG. 6c. The flow out of the righthand passageway continues until the liquid level recedes below the sensing level at which time the power stream reverts to the flow pattern illustrated in FIG. 6a.

A further embodiment of the invention is illustrated in FIG. 7. In this embodiment, the diversion of the fluid power stream occurs in a fashion substantially different from that of the earlier described embodiments. More specifically, the amplifier comprises a fluid inlet conduit 82 having a narrowed terminal portion 82a defining a nozzle-like orifice for projecting the fluid power stream across a free space toward a deflector plate 84.

As illustrated in the drawing, the deflector plate 84 is provided with an aperture positioned in alignment with the fluid power jet and of a cross-sectional dimension such that the jet normally flows in its entirety through the aperture. In this regard, it will be recognized that the power jet formed by the orifice 82a may be of a circular, rectangular or other cross-sectional configuration with the aperture in the deflector plate being only of a slightly larger cross-sectional area and preferrably of a like cross-sectional configuration.

The amplifier 80 further includes an actuator means 86 carried between a pair of parallel support plates 88 and 90, as seen in FIG. 7a. Specifically, the actuator means 86 includes a rotatable shaft 86a suitably journaled in the support plates 88 and 90. The shaft 86a is provided with a collar 86b which is angularly adjustable relative to the shaft 86a by means of a set screw. The collar 86b carries at spaced intervals a pair of radially extending

force transmitting members

86c and 86d. Theshaft 86a is coupled to a control member such as a valve 88 or the like which may be used to regulate a liquid flow in accordance with the angular position of the shaft 86a. In this regard, angular displacement of the shaft is confined to predetermined limits by a pair of angularly spaced

stop abutments

92 and 94 which are positioned to intercept a peg 86 radially extending from the collar 86b;

For convenience, the operation of the fluid amplifier 80 will again bedescribed in the context of a liquid level sensor although it will be recognized that the structure is suitable for other applications. As shown in FIG. 7, the liquid level within the reservoir is below that of the inlet orifice 82a. Accordingly, the fluid power stream retains its well defined cross-sectional configuration as it is projected across the free space toward the aperture in the deflector plate 84. The stream passes through the deflector plate 84 in its entirety and intercepts the force transmitting arm thereby 86c rotating the shaft 86a in a clockwise direction until the peg 86c intercepts the stop abutment 92.

' When the liquid level within the reservoir rises into intimate contact with the fluid power stream, as shown in FIGS. 7b, the power stream is altered to a turbulent flow pattern of a significantly greater cross-sectional dimension. Thus, a portion of the enlarged power stream now intercepts the curved deflector plate 84. It has been found that the fluid intercepting the deflector plate below the aperture therein is diverted upwardly with such a force that it directs all of the flow away from the aperture and along the curved contour of the deflector plate into engagement with the force transmitting member 86d. The shaft 86a is now rotated in a counter-clockwise direction until the peg 86c intercepts the stop abutment 94 thereby actuating the valve 88. The flow condition prevails until the liquid level within the reservoir recedes below the sensing level to restore the power stream to a laminar flow condition. At this time the amplifier reverts to the operating condition illustrated in FIG. 7.

While particular embodiments of the present invention have been shown and described, it is apparent that various changes and modifications may be made, and it is therefore intended in the following claims to cover all such modifications and changes as may fall within the true spirit and scope of this invention.

I claim:

1. A laminar-turbulent amplifier for sensing an interface between a liquid and a gas in a liquid containing reservoir and for developing a fluid pressure signal in response to the static presence of said interface at a preselected sensing level, comprising:

inlet means for developing a substantially laminar fluid power-stream having a predetermined crosssectional area and for rojecting said power stream from u n'nulelike orifice positioned immediately adjacent said sensing level and along a predetermined axis when said interface is spaced in one direction from said sensing level;

signal developing means co-acting at said preselected sensing level with said interface between said liquid and gas for abruptly altering said fluid power stream to a substantially turbulent flow condition of a cross-sectional area substantially greater than that of said predetermined area independently of any secondary control stream flow; and

outlet means spaced from said inlet means for receiving a fluid pressure signal of one magnitude when said power stream is laminar and of a second, substantially smaller magnitude when said power stream is altered to turbulent flow.

2. The fluid amplifier of claim 1 in which said outlet means comprises a deflector plate facing said power stream and having an aperture aligned with said power stream to define said first outlet and of a sufficiently large dimension for passing said substantially laminar power stream but of dimension less than that of said turbulent power stream so that said turbulent power stream impinges upon said deflector plate causing said power stream to be deflected in its entirety along said deflector plate and away from said first outlet.

3. The fluid amplifier of claim 1 in which said inlet means includes control means comprising a fluid passageway portion downstream of said passageway of said inlet means and of a greater cross-sectional area than said inlet means passageway and further having a guidewall portion curving outwardly away from the fluid power stream.

4. The fluid amplifier of claim 3 in which said control means includes an access opening to said fluid power stream on one side of said fluid passageway portion and in which said power stream is altered from said substantially laminar to said turbulent flow pattern attendant the liquid level in said reservoir rising to and flowing in said access opening.

5. The fluid amplifier of claim 4 in which said control means is constructed and arranged relative to said power stream such that the transition of said power stream from a laminar to a turbulent flow condition causes a low pressure condition to develop intermediate said guidewall portion and said power stream resulting in attachment of said power stream to said guidewall portion and diversion of said power stream along said guidewall portion and away from first outlet of said outlet means.

6. The fluid amplifier of claim 5 in which said passageways of said inlet means and said control means, respectively, are of circular cross-section.

7. The fluid amplifier of claim 6 in which said access opening comprises a port extending through a sidewall of said passageway of said control means.

8. The fluid amplifier of claim 6 in which a longitudinal section of said second passageway portion of said control means is cut-away to define said access opening.

9. The laminar-turbulent amplifier of claim 1 in which said inlet means includes a nozzle-like orifice for forming said power jet and said signal developing means comprises a wall portion surrounding said nozzle-like orifice and having a planar surface positioned substantially parallel to said interface between said dissimilar fluids.

10. The laminar-turbulent amplifier of claim 1 in which said signal developing means includes the static presence of the liquid being sensed.

11. The laminar-turbulent amplifier of claim in which said signal developing means includes an element positioned at the desired sensing level and in which said fluid stream is abruptly altered from laminar to turbulent flow exclusively through the interaction of said liquid and said element.

12. The laminar-turbulent amplifier of claim 1 in which said outlet means includes at least one outlet channel and further including control means responsive to the change of said fluid stream from laminar to turbulent flow for diverting said fluid stream away from said one outlet channel.

13. The laminar-turbulent amplifier of claim 12 in which said signal developing means is arranged for introducing a perturbant signal to said fluid stream at a position immediately downstream of said inlet means for altering said fluid form laminar to turbulent flow.

14. A fluid amplifier adapted for sensing the interface between a liquid and a gas in a liquid containing reservoir and for developing a fluid pressure signal in response to the static presence of the interface at a preselected sensing level, comprising:

inlet means for developing a substantially laminar fluid power stream having a predetermined crosssectional area;

outlet means spaced from said inlet means and including a first outlet for receiving said fluid power stream;

means defining an access region to said fluid power stream for permitting liquid at said preselected sensing level to physically contact said substantially laminar power stream to alter said laminar stream to a substantially turbulent flow pattern of a cross-sectional area substantially greater than that of said predetermined area;

and control means responsive to the change in said power stream from said substantially laminar to said substantially turbulent flow pattern for diverting said power stream away from said first outlet of said outlet means.

15. The fluid amplifier of claim 14 in which said control means comprises a deflector plate spaced from and facing said inlet means and including an aperture coaxially aligned with said laminar power stream and of a dimension for passing said laminar power stream but of dimension less than that of said turbulent power stream such that a portion of said turbulent power stream impinges on said deflector plate causing said power stream to be deflected in its entirety along said deflector plate.

16. The fluid amplifier of claim 15 in which said inlet means comprises a noule for developing a power jet of circular cross-section and said deflector plate is of a uniformly curved contour and the aperture therein is of circular cross-section.

17. The fluid amplifier of claim 16 and further including an actuating means having a first force transmitting member aligned with said fluid power stream and positioned on the side of said deflector plate opposite that of said inlet means and responsive to impingement of said laminar power stream for developing an actuating signal.

18. The fluid amplifier of claim 17 in which said actuating means includes a second force transmitting member responsive to impingement of said power stream for developing an actuating signal and positioned so as to intercept said power stream when it is deflected along said deflector plate.

19. The fluid amplifier of claim 14 in which said inlet means includes a fluid passageway for forming said substantially laminar power stream of predetermined cross-sectional area and in which said control means comprises a fluid passageway portion downstream of said passageway of said inlet means but of a substantially greater cross-sectional area and having a guidewall portion curving outwardly away from the fluid power stream and further in which said guidewall portion is positioned with respect to said power stream such that upon transition of said power stream from a laminar to a turbulent flow pattern a low pressure condition develops between said power stream and said guidewall portion causing said power stream to adhere to and follow the curvature of said guidewall.

20. The fluid amplifier of claim 19 in which said passageways of said inlet means and said control means, respectively, are of circular cross-section and in which said access defining means comprises a port ex tending through a sidewall of said passageway portion of said control means.

21. The fluid amplifier of claim 20 and further including oscillation control means for developing and applying a perturbant signal to said power stream at a predetermined frequency to effect an oscillating movement of said power stream at a corresponding frequency.

22. The fluid amplifier of claim 19 in which said passageways of said inlet means and said control means, respectively, are of a rectangular cross-section and in which said guidewall constitutes one of the sidewalls of said control means passageway and in which the sidewall opposite said one sidewall is provided with said access defining means.

23. A fluid amplifier for sensing the presence of liquid at a desired level in a liquid reservoir and for developing a pressure signal in response thereto, comprising:

inlet means having a fluid passageway of a predetermined cross-sectional area for developing a sub stantially laminar fluid power stream of a corresponding cross-sectional area and for directing said power stream along a predetermined axis;

and control means including wall means spaced laterally outward of said fluid power stream by a predetermined distance and only partially enclosing said fluid power stream, said wall means including a guide surface portion curving outwardly away from said predetermined axis and in which the non-enclosed portion of said power stream provides an access opening to said fluid power stream positioned on the side of said stream opposite that of said guide surface portion and at said desired level for permitting the reservoir liquid, upon ascending to said desired level, to flow through said access opening and into contact with said power stream for altering said power stream from said substantially laminar flow to a substantially turbulent flow pattern of a cross-sectional area substantially greater than that of said predetermined area, said wall means being positioned with respect to said turbulent fluid power stream so that a substantially enclosed space is formed between said turbulent power stream and said wall means causing a low pressure condition to develop therebetween resulting in said power stream attaching to said guide surface and diverting away from said predetermined axis.

24. The fluid amplifier of claim 23 and further including oscillator control means for developing and applying a perturbant signal to said power stream at a predetermined frequency to effect an oscillating movement of said power stream at a corresponding frequeny a resersaid reservoir at said desired level for causing said fluid stream to be abruptly altered to a substantially turbulent flow independently of any control stream flow when the fluid level in said reservoir 25. A laminar-turbulent fluid amplifier adapted for rises to the desired level; and outlet means spaced from said inlet means and positioned below said desired level for receiving a fluid pressure signal of one magnitude when the flow of said fluid stream is substantially laminar and for receiving a fluid pressure signal of a substantially altered magnitude when the flow of said fluid stream is substantially turbulent. 26. The laminar-turbulent amplifier of claim 24 in which said signal developing means includes the liquid being sensed and an element positioned adjacent to the desired sensing level and in which said fluid stream is abruptly altered from laminar to turbulent flow exclusively through the interaction of said liquid and said element.

27. The laminar-turbulent amplifier of claim 24 in which said outlet means includes at least one outlet channel and further including control means responsive to the change of said fluid stream from laminar to turbulent flow for diverting said fluid stream away from said one outlet channel.

Claims

1. A laminar-turbulent amplifier for sensing an interface between a liquid and a gas in a liquid containing reservoir and for developing a fluid pressure signal in response to the static presence of said interface at a preselected sensing level, comprising: inlet means for developing a substantially laminar fluid power stream having a predetermined cross-sectional area and for projecting said power stream from a nozzle-like orifice positioned immediately adjacent said sensing level and along a predetermined axis when said interface is spaced in one direction from said sensing level; signal developing means co-acting at said preselected sensing level with said interface between said liquid and gas for abruptly altering said fluid power stream to a substantially turbulent flow condition of a cross-sectional area substantially greater than that of said predetermined area independently of any secondary control stream flow; and outlet means spaced from said inlet means for receiving a fluid pressure signal of one magnitude when said power stream is laminar and of a second, substantially smaller magnitude when said power stream is altered to turBulent flow.

11. The laminar-turbulent amplifier of claim 10 in which said signal developing means includes an element positioned at the desired sensing level and in which said fluid stream is abruptly altered from laminar to turbulent flow exclusively through the interaction of said liquid and said element.

14. A fluid amplifier adapted for sensing the interface between a liquid and a gas in a liquid containing reservoir and for developing a fluid pressure signal in response to the static presence of the interface at a preselected sensing level, comprising: inlet means for developing a substantially laminar fluid power stream having a predetermined cross-sectional area; outlet means spaced from said inlet means and including a first outlet for receiving said fluiD power stream; means defining an access region to said fluid power stream for permitting liquid at said preselected sensing level to physically contact said substantially laminar power stream to alter said laminar stream to a substantially turbulent flow pattern of a cross-sectional area substantially greater than that of said predetermined area; and control means responsive to the change in said power stream from said substantially laminar to said substantially turbulent flow pattern for diverting said power stream away from said first outlet of said outlet means.

16. The fluid amplifier of claim 15 in which said inlet means comprises a nozzle for developing a power jet of circular cross-section and said deflector plate is of a uniformly curved contour and the aperture therein is of circular cross-section.

20. The fluid amplifier of claim 19 in which said passageways of said inlet means and said control means, respectively, are of circular cross-section and in which said access defining means comprises a port extending through a sidewall of said passageway portion of said control means.

23. A fluid amplifier for sensing the presence of liquid at a desired level in a liquid reservoir and for developing a pressure signal in response thereto, comprising: inlet means having a fluid passageway of a predetermined cross-sectional area for developing a substantially laminar fluid power stream of a corresponding cross-sectional area and for directing said power strEam along a predetermined axis; and control means including wall means spaced laterally outward of said fluid power stream by a predetermined distance and only partially enclosing said fluid power stream, said wall means including a guide surface portion curving outwardly away from said predetermined axis and in which the non-enclosed portion of said power stream provides an access opening to said fluid power stream positioned on the side of said stream opposite that of said guide surface portion and at said desired level for permitting the reservoir liquid, upon ascending to said desired level, to flow through said access opening and into contact with said power stream for altering said power stream from said substantially laminar flow to a substantially turbulent flow pattern of a cross-sectional area substantially greater than that of said predetermined area, said wall means being positioned with respect to said turbulent fluid power stream so that a substantially enclosed space is formed between said turbulent power stream and said wall means causing a low pressure condition to develop therebetween resulting in said power stream attaching to said guide surface and diverting away from said predetermined axis.

24. The fluid amplifier of claim 23 and further including oscillator control means for developing and applying a perturbant signal to said power stream at a predetermined frequency to effect an oscillating movement of said power stream at a corresponding frequency.

25. A laminar-turbulent fluid amplifier adapted for sensing a change from a desired liquid level in a reservoir, consisting essentially of: inlet means located at least partially above said desired level for directing a fluid stream of substantially laminar flow downwardly toward and substantially transversely to the surface of the liquid in said reservoir, when the liquid level in said reservoir is disposed below said desired level; signal developing means coacting with the liquid in said reservoir at said desired level for causing said fluid stream to be abruptly altered to a substantially turbulent flow independently of any control stream flow when the fluid level in said reservoir rises to the desired level; and outlet means spaced from said inlet means and positioned below said desired level for receiving a fluid pressure signal of one magnitude when the flow of said fluid stream is substantially laminar and for receiving a fluid pressure signal of a substantially altered magnitude when the flow of said fluid stream is substantially turbulent.

26. The laminar-turbulent amplifier of claim 24 in which said signal developing means includes the liquid being sensed and an element positioned adjacent to the desired sensing level and in which said fluid stream is abruptly altered from laminar to turbulent flow exclusively through the interaction of said liquid and said element.