US3853617A

US3853617A - Fluidic load regulator

Info

Publication number: US3853617A
Authority: US
Inventors: T Lechner
Original assignee: Johnson Service Co
Current assignee: Johnson Service Co; Johnson Controls International Inc
Priority date: 1971-09-29
Filing date: 1971-09-29
Publication date: 1974-12-10
Anticipated expiration: 1991-12-10
Also published as: AU4655972A; JPS4841180A; FR2155459A5; DE2247802A1; IT966062B; CA969094A

Abstract

A fluidic pressure regulator includes a pair of opposed nozzles connected respectively to a common source fluid supply through individual adjustable pressure dropping resistors. A variable flow load is connected to the junction of one resistor and the related nozzle. The nozzles establish opposing impacting flows with a stagnation or impact flow position adjacent the orifice of the load connected nozzle. The load connected resistor and nozzle define a pressure dividing network to establish a predetermined pressure output without load flow. Load flow tends to drop the load and load nozzle pressures. However, a decrease in the nozzle pressure causes movement of the impact flow toward the related orifice which increases the nozzle and therefore load pressure to maintain a regulated load pressure.

Description

Unit States Lechner, ,lr.

.ltet [191 FLUlllDIC LOAD REGULATOR [75] Inventor: Thomas J. Lechner, Jr., Menomonee Falls, Wis.

[73] Assignee: Johnson Service Company,

Milwaukee, Wis.

[22] Filed: Sept. 29, 1971 [21] Appl. No.: 184,686

[52] US. Cl. 137/824 [51] Int. Cl. FlSc 1/20 [58] lField of Search 137/815, 824; 73/37.7

[56] References Cited UNITED STATES PATENTS 3,272,215 9/1966 Bjornsen et a1 137/815 3,279,489 10/1966 Bjornsen et al 137/815 3,340,886 9/.1967 Jacobson 73/37.7 X 3,343,459 9/1967 Jacobson 73/37.7 X 3,388,713 6/1968 Bjornsen.... 137/815 3,472,255 10/1969 Fox et al l37/8l.5 3,616,809 11/1971 Laakaniemi et al. 137/824 X 3,623,497 12/1969 Kaske r l 137/815 3,710,421 l/l973 Tooka 73/37.7 X

Primary ExaminerWilliam R. Cline Assistant Examinerlra S. Lazarus Attorney, Agent, or FirmAndrus, Sceales, Starke & Sawall [5 7 ABSTRACT A fluidic pressure regulator includes a pair of opposed nozzles connected respectively to a common source fluid supply through individual adjustable pressure dropping resistors. A variable flow load is connected to the junction of one resistor and the related nozzle. The nozzles establish opposing impacting flows with a stagnation or impact flow position adjacent the orifice I 11 Claims, 4 Drawing Figures SOURCE PRESSURE l l l l l i l l PATENTELUEC 1 01914 SOURGE PRESSURE FIG.'.3

0 304m UJNNOZ INVENTOR. THOMAS J. LECHNER JR.

A I v Jug, Jaw/J Attorneys A G I F 2 3 PRESSURE (PSIG) FLUIDIC LOAD REGULATOR BACKGROUND OF THE INVENTION This invention relates to a fluidic load regulator and particularly to a pressure type regulator for incorporation in fluidic control or drive systems and the like.

Fluidic devices and interrelated industrial control systems have been developed to provide a pure fluid or essentially pure fluid system while maintaining many of the advantages and the versatility of electrical and electronic control systems. Thus, pure fluidic amplifiers and modulators can be constructed without moving mechanical parts through the use of interacting fluid streams. Such fluidic devices have certain advantages over electrical devices, particularly in environments where the electrical systems are adversely affected by spurious magnetic and electrical signals and must be especially constructed or operated. Further, pneumatic and similar operating systems can be readily connected to fluidic controls.

In many pneumatic and other fluid controls, a pressure signal delivered to a load or consuming device may require regulation such that the output pressure is essentially independent of the output or load flow. The output pressure variation with supply or source pressure variation is also preferably minimized. Although mechanical load flow regulators are well-known in the art there is a need for a fluidic regulator.

SUMMARY OF THE PRESENT INVENTION The present invention is particularly directed to a fluidic flow regulator which establishes an output pressure which is essentially independent of the load flow. The preferred construction of the invention also produces an equal percentage variation of the output pressure with a variation in source or supply pressure.

Generally, in accordance with the present invention, the pressure regulator includes a pair of stream forming means interconnected to a common pressure source means. The stream forming means are mounted in opposed and spaced relationship to establish a pair of opposed impacting streams with the impact position therebetween. The connection to the common pressure source means includes a flow resistance means between, at least, one of the stream forming means and the source means, with the output or load interconnected into the system between the resistance means and the corresponding stream forming means. Applicant has found that by proper selection of the supply connections and the stream forming means characteristics, the impacting balance or stagnation position is formed in a region wherein a very high rate of change in such position occurs with variation in the output or load pressure, such thatthe stream forming means effectively undergoes a significant impedance change for very small pressure changes. With this operation and characteristic, any increase or decrease in load flow results in a minute change in the output pressure with a corresponding inverse flow through the associated stream forming means to maintain an essentially constant output load pressure. Thus, the load pressure remains essentially constant and independent of normal fluctuations in load flow. Further, although the regulator will not maintain regulations with variations in supply pressure, it does provide equal percentage regulation such that the'load variation is a corresponding percentage and not directly equal to the supply pressure change.

In accordance with the particularly novel construction, the present invention employs a pair of opposed nozzles connected respectively to a common source fluid supply through individual pressure dropping resistors. The load is tapped or connected to the junction of one load resistor and the related load nozzle. The load resistor is preferably adjustable and is adjusted to establish the desired output pressure with a minimum load flow and with the opposed nozzle cut off. The nozzle diameters are so selected that they will pass the difference between the maximum and minimum load flow at the design pressure to be regulated. The second nozzle is then connected to the source through its resistor and adjusted to establish a stagnation or impact position just outwardly from or slightly spaced from the ori' fice of the load nozzle. The load resistor and the nozzle define a pressure dividing network (similar to a voltage divider in electrical circuits) to establish a predetermined pressure output without load flow. If load flow is increased, it would tend to drop the load pressure. This in turn would tend to decrease the load nozzle pressure. However, a decrease in the nozzle pressure causes movement of the impact flow toward the related load nozzle, thereby tending to block said nozzle and automatically provide a regulating effect.

Applicant has found that the present pressure regula tor provides exceptional regulation over a selected operating range which can be directly and practically applied in fluidic flow systems. The load flow is directly taken from the source through the load resistor and does not pass through a separate regulating or fluidic device and thereby permits recovery of output pressure equal to essentially one hundred percent of the supply pressure. The output pressure may therefore be selected at any value between reference and supply pressures. The load regulator of the present invention only requires twice the total desired flow change required by the load. Thus, the air consumed by the load regulator is not related to the total load flow but only to the desired or permitted change in load flow.

Further, a very significant advantage which Applicant has obtained with the present invention is the regulation of relatively low pressure stream flow or output stream flow. Thus with the present invention, regulation of pressures in the range of hundreths of pounds per square inch or centimeters of water have been reliably attained. To attain a similar results in the present diaphragm type units or the like would require impractically large diaphragms. Further the advantage of fluidic systems of course would also be lost with such sys tems.

The present invention thus provides a fluidic regulator for establishing of the output pressure essentially independent of load flow in a relatively simple and inexpensive construction and with a minimum load pressure variation with supply pressure variation.

BRIEF DESCRIPTION OF THE DRAWING The drawing furnished herewith illustrates the preferred construction of the present invention in which the above advantages and features are clearly disclosed as well as others which will be readily understood from the description of the preferred embodiment of the invention.

In the drawing:

FIG. 1 is a schematic illustration of a fluidic system including a flow regulator in accordance with the teaching of the present invention;

FIG. 2 is a diagrammatic illustration of a pair of opposed nozzles shown schematically in FIG. 1;

FIG. 3 is a graphical illustration of the flow characteristics with varying input nozzle pressures and flow and further showing one load line; and

FIG. 4 is a graphical illustration of pressure versus flow showing the impedance curve for a pressure regulator such as shown in FIG. 1.

DESCRIPTION OF THE ILLUSTRATED EMBODIMENT Refering to the drawing and particularly to FIG. 1, a pressure source or supply 1 of a suitable operating fluid such as gas, liquid or mixtures is shown interconnected to drive a fluid system load 2 through a pressure regulator 3 constructed and connected between the supply 1 and the load 2, in accordance with the teaching of the present invention. The load 2 is shown with an arrow thereto to indicate that the load flow demand may vary. The pressure regulator 3 is constructed to maintain an essentially constant pressure across the system load 2 with such normal variations in the output load flow. In accordance with the present invention the pressure regulator is a pure fluid device based on the impacting stream concept and employing an impact modulator 4, which is schematically shown in FIG. 1 and diagrammatically illustrated'in FIG. 2. The source 1 and load 2 may provide and consume any suitable fluid medium but advantageously employs air which is readily available and references to atmosphere. The system is hereinafter described as a pneumatic system.

The impact modulator 4 includes a pair of

opposed nozzles

5 and 6 which in the illustrated embodiment of the invention have similar opposed stream forming orifices 7 which are not necessarily of the same diameter. The nozzle 5 is connected to the supply 1 in series with a load connected resistor 8, which may be adjustable for setting of the regulated pressure. The nozzle 6 is similarly connected to the supply in series with a dropping resistor 9 which is also shown to be adjustable. The nozzles are mounted with the-orifices 7 in directly opposed aligned relationship as shown in FIG. 2 for maximum regulation, but could be skewed or canted if desired. The connection to the supply through the

resistors

8 and 9 establishes a pair of opposing streams l and 11 which impact, within the space between the two nozzles 12, is connected to atmosphere or some other convenient reference pressure to allow free exiting of the impacting streams. The reference pressure must be less than the desired regulated pressure.

Referring to FIG. 1, the load 2 is connected to the junction of the resistor 8 and the nozzle such that the output pressure is directly related to the division of the supply pressure established by the flow through these respective elements.

Thus, if the nozzle 5 is completely blocked to prevent any flow therethrough, all the flow through resistor 8 flows through load 2. This represents the maximum flow that the load can regulate to and the pressure is equal to the supply pressure less the drop across resistor 8, thus determining the value of resistor 8.

If the nozzle 5 is completely unrestricted, the flow through resistor 8 divides between load 2 and nozzle 5. This represents the minimum flow that the load can pass at the regulated pressure and thus determines the size of nozzle 5.

For example, referring particularly to FIG. 3, the flow characteristic for nozzle 5 is shown by trace 13. If the load flow is reduced, the nozzle flow increases and the pressure increases at the junction of the restrictor or resistor 8 and the nozzle 5 in accordance with trace 13. The load pressure equals the nozzle pressure and thus also increases in accordance with the curve 13. For any given supply, the load pressure intercepts the trace 13 and will vary with flow in accordance with a load line determined by the resistor 8, such as shown at 14 in FIG. 3.

In the presence of the opposing stream 10 from nozzle 6 the characteristic is further controlled by the relative strength of the two streams 10 and 11. In FIG. 3, traces 15 through 18 are illustrated for different preset pressures at nozzle 6, and are typically taken from a family of curves related to incremental pressure changes between pressures from 2 to 10 p.s.i.g. in nozzle 6. With the nozzle 6 at a pressure of 2 pounds per square inch, there is a negative flow through the nozzle 5 as shown by the lower portion of trace 15 until such time as the opposed nozzle pressure 5 equals the set pressure at nozzle 6. When the pressures are just equal there is a zero load flow through the nozzle 5 indicating that the impact position is adjacent the orifice 7 with all flow of nozzle 6 exiting to the reference. As the nozzle 5 pressure increases, the interaction with the nozzle orifice 7 at nozzle 5 is such that the system exhibits a characteristic of a very extreme impedance change for very minute pressure changes. Thus, a very slight increase in the pressure at nozzle 5 establishes a very rapid and substantial increase in the flow through nozzle 5 which is limited by the nozzle characteristics with zero pressure in nozzle 6. The device may be considered to be functioning in the manner of a zener diode in an electronic regulating circuit except that the impedance characteristic occurs at the point where the nozzle pressures are essentially equal rather than as a result of the inherent physical characteristic of the material of an element. Thus a very small change in the pressure at nozzle 5 is accompanied with substantial variations in flow, producing extremely high gain. Graphically, each of the traces 15 18 include an essentially straight line change in flow to the intersection of the flow characteristic line 13. The resistor 8 is selected or adjusted for nozzle 5 such that the nozzle pressure equals the desired load pressure with minimum or zero load flow and with the nozzle 6 cut off. Further, the orifice of nozzle 5 is selected to pass the difference between the maximum load flow and minimum or zero flow, as shown in FIG. 3 by the intersections of the traces l5 18 inclusive with the curve 13.

In the present invention, the dropping resistor 9 is selected to establish the necessary pressure in nozzle 6 which will create an impacting point just outwardly of the orifice 7 of the nozzle 5, for example, as illustrated in FIG. 2. The

resistors

8 and 9 thus establish the common intersection of the load line 14 with the nozzle characteristic curve 13 and the desired nozzle characteristic curves 15 18.

In operation, if there is an increase in load flow, a very minute and practical insignificant change in the pressure of nozzle 5 provides a corresponding decrease in the nozzle flow to keep the net flow through the regulator and the load constant with an essentially con stant load pressure.

The impact modulator 4 provides a continuous modulation similar to the function of a diaphragm pressure regulator with the stream from nozzle 6 functioning as the lid or diaphragm unit overlying the nozzle 5. However, the present invention allows operation and control regulation of pressures at relatively low values and in order of hundreths of pounds per square inch in a practical construction. Although it is possible to generally accomplish similar results with diaphragm units, the diaphragm must be extremely large and is therefore impractical. Further, the present invention provides a simple and inexpensive means of completely eliminating the mechanical features heretofore employed in pressure regulators and provides a load regulating flow wherein the load flow does not pass through a fluidic device before being applied to the load.

In FIG. 4-, typical regulated pressure curves 19 22 are shown. The embodiment of the invention for obtaining such curves was generally as shown in FIG. 1 with the opposing nozzles having orifices essentially 0.025 inches in diameter with a gap or spacing therebetween of 0.031 inches. Air was employed to form the stream from a supply pressure of 20 p.sig. (pounds per square inch gauge). The restrictors or

resistors

8 and 9 and the load 2 were made adjustable as diagrammatically shown in FIG. 1. The

fluid resistors

8 and 9 were set to establish regulated pressures of l, 2, 5 and 10 p.s.i.g. The load flow was then varied as shown in FIG.

' 4. Thus for 1 p.s.i.g. an essentially constant output pressure was maintained over the range of O to 100 cubic inches per minute, as shown by trace 19. When the regulated pressure was raised respectively to 5 and I p.s.i.g. by readjustment of the

resistors

8 and 9, a similar characteristic resulted. The regulation range at p.s.i.g. increased to a range ofO to just over 230 cubic inches per minute, and at p.s.i.g. increased to a range of 0 to 280 cubic inches per minute, as shown by

traces

21 and 22, respectively. The actual characteristics thus follow the expected results as shown from the illustration in FIG. 3, where the high gain and regulated pressure range increases with the increasing pressure levels. Further, the fluid consumption is minimal because the regulator requires only twice the value of the flow change which the load encounters and is not related to the total load flow. The maximum flow through nozzle Sand, consequently, also through nozzle 6, is the flow established with the minimum load flow. This in turn establishes the flow consumption for regulation independently of the total load flow.

In the present invention, the particular nozzle size and source pressure will not change the characteristics as long as pressures are maintained below those which might create shock waves and the like which would interfere with the stability of the impact position. The apparatus for optimum functioning will be restricted to regulated pressures below pressures at which shock waves are formed, such as, for example, .below 40 p.s.i.g. for air. The system can of course operate above such level if the instability associated with shock waves is acceptable.

Further, as previously noted, the resistor 8 and nozzle 5 function as a pressure divider. The normal variations and fluctuations in a practical pressure source will be correspondingly reflected at

nozzles

5 and 6. This results in a percentage change in the regulated load pressure equal to percentage change in the supply pressure. Thus, if the supply pressure in the illustrated embodiment were to increase from 20 to 22 p.s.i.g. for any reason, the load pressure would vary by a corresponding percentage, or 10 percent. Thus if the system were regulating at one pound the load pressure would change by one-tenth of a pound. If the load pressure were being regulated to 10 p.s.i.g., the load pressure, for the above supply variation, would vary by l p.s.i.g.

The operation of the illustrated embodiment of the invention can be summarized as follows. The

fluidic resistors

8 and 9 are adjusted to establish an impact position just outside of the nozzle 5, with a minimum load flow and the desired load pressure. Any increase in the load flow will result in a corresponding decrease in the flow through the nozzle 5 to maintain the output pressure constant. Thus, as the load flow increases, the output pressure would tend to drop as the result of the increased flow through the resistor 7. However, any decrease in output pressure results in movement of the impact or stagnation point with respect to the orifice of the nozzle 5 in a direction into the nozzle orifice, thereby tending to close off the nozzle and significantly increasing its impedance. This results in a reversal in the pressure characteristic to the upstream side of the nozzle 5 to return and hold the output pressure at the regulated level. Any increase in output pressure results in an opposite movement of the stagnation point to reduce the pressure. The system thus acts as an automatic leak port type control without the necessity for using the conventional mechanically positioned lid unit which is coupled to a sensing system for repositioning of the lid assembly to maintain a constant output pressure.

The present invention provides a highly acceptable regulation of a variable flow load, which would include varying flow through one load element, a plurality of selectively connected load elements or any other system coupled to a point between the flow resistance means and the outlet of the stream forming means which results in a change of flow from such point, over a wide range, with the selection and application of the system pressure over essentially the complete range of pressures below shock wave pressures. Further, although the system does not directly and completely regulate for changes in source pressure, such changes are minimized by establishing percentage regulation with respect to source pressure variations.

The present invention thus provides a simple, reliable and inexpensive fluidic pressure regulator which eliminates the necessity for the mechanical and the pneumatic type regulators heretofore employed in fluidic systems. I

Various modes of carrying out the invention are contemplated as being within the scope of the following claims, particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

1. A fluidic' regulated pressure supply system for supplying a regulated pressure to a variable flow load comprising, a first stream forming means including an outlet and a flow resistance means for calibrating a first stream pressure at said outlet for a minimal flow condition of said load, said load being connected to and supplied from a point between said flow resistance means and said first stream forming means outlet and upstream of said outlet, a second stream forming means mounted in opposed spaced relation to said first stream forming means for establishing a second stream, and

of said streams relative to said first stream forming means outlet to vary the impedance of said first stream forming means to maintain the desired regulated pressure to the load with said varying load flow with respect to said point.

2. The fluidic regulated pressure supply system of claim 1 wherein said resistance means is adjustable.

-3. The fluidic regulated pressure supply system of claim 1 wherein said load is operated at a regulated pressure of the order of hundreths of pounds per square inch.

4. The fluidic regulated pressure supply system of claim 1 wherein said regulated pressure is below a level creating shock waves in said first stream forming means.

5. The fluidic regulated pressure supply system of claim 1 wherein said stream forming means are connected to a source means and are each a nozzle means having orifice means establishing said pair of opposed impacting streams between said nozzle means.

6. The fluidic regulated pressure supply system of claim 5 wherein said nozzle means establish streams of a pressure below a level sufficient to create shock waves.

7. The fluidic regulated pressure supply system of claim 5 wherein said nozzle means having corresponding orifices are mounted in diametrically opposed relation.

8. The fluidic regulated pressure supply system of claim 5 wherein said resistance means includes a first resistor connected between said first nozzle means and said source means, said system includes a second resistor connected between said second nozzle means and said source means, said resistors being selected to establish the impact position of said streams adjacent the orifice of the first nozzle means with a minimum load flow and a selected output pressure.

9. The fluidic regulated pressure supply system of claim 8 wherein said resistors are adjustable.

10. The fluidic pressure regulator of claim 8 wherein said stream forming means establish streams below a pressure level sufficient to create shock waves.

11. A fluidic regulated pressure supply system for supplying a regulated pressure to a load comprising a pressure source means, a first nozzle having an orifice, a second opposed nozzle mounted in diametrically opposed spaced relation to said first nozzle and having an orifice corresponding to said orifice of the first nozzle, and establishing a pair of opposed impacting streams between said nozzle means, a first flow resistor connecting said first nozzle to said source means, a second flow resistor connecting said second nozzle to said source means, a variable flow load connected between said first resistor and said first nozzle, said orifice of said first nozzle being selected to carry the difference between the maximum and the minum load flow, and said pressure source means and resistors being selected to establish a maximum regulated pressure below the pressure at which shock waves will form.

l l l

Claims

1. A fluidic regulated pressure supply system for supplying a regulated pressure to a variable flow load comprising, a first stream forming means including an outlet and a flow resistance means for calibrating a first stream pressure at said outlet for a minimal flow condition of said load, said load being connected to and supplied from a point between said flow resistance means and said first stream forming means outlet and upstream of said outlet, a second stream forming means mounted in opposed spaced relation to said first stream forming means for establishing a second stream, and said first and second forming means providing streams of relative strength, one to the other, causing impacting of said streams between said stream forming means and defining an impacting flow in proximity to the outlet of said first stream forming means wherein varying load flow conditions causes movement of the impacting flow of said streams relative to said first stream forming means outlet to vary the impedance of said first stream forming means to maintain the desired regulated pressure to the load with said varying load flow with respect to said point.

3. The fluidic regulated pressure supply system of claim 1 wherein said load is operated at a regulated pressure of the order of hundreths of pounds per square inch.