US3845904A

US3845904A - Variable flow two stage nozzle

Info

Publication number: US3845904A
Application number: US00422880A
Authority: US
Inventors: Z Mocarski
Original assignee: SRC LAB
Current assignee: S R C LABOR INC US; SRC LAB
Priority date: 1973-12-07
Filing date: 1973-12-07
Publication date: 1974-11-05
Anticipated expiration: 1991-11-05

Abstract

A two stage nozzle in which pressurized fluid induces secondary fluid flow in both stages with the discharge of the first stage functioning as the pressurized fluid for the second stage and the latter discharge being the nozzle discharge. The quantity of secondary fluid flow in the second stage is varied by the difference in pressure existing between adjacent the nozzle discharge and the secondary fluid while the first stage may have a similar pressure differential variable opening to the secondary fluid or a fixed opening.

Description

United States Patent 1 1111 3,845,904

Mocarski Nov. 5, 1974 [54] VARIABLE FLOW TWO STAGE NOZZLE 3,693,656 9/1972 Sauer 239/410 Inventor: Zeno R. Mocarski, Easton Conn. 3.750.955 8/1973 Nakal et al. 239/420 [73] Assigneez S.R.C. Laboratories, Inc., Fairfield, Primary ExaminerLl0yd L. King Conn. Attorney, Agent, or Firm-Ernest Junkins 1 [22] Filed: Dec. 7, 1973 [57] ABSTRACT [2]] Appl 422380 A two stage nozzle in which pressurized fluid induces secondary fluid flow in both stages with the discharge 52 US. Cl. 239/410 of the first stage functioning as the Pressurized fluid [51] Int. Cl B05b 7/12 for the Second stage and the discharge being [58] Field of Search 239/420, 410, 411, 417.3, nozzle discharge The q y of Secondary fluid flew 239 533; 137 541 in the second stage is varied bythe difference in pressure existing between adjacent the nozzle discharge [5 References Cited and the secondary fluid while the first stage may have UNITED STATES PATENTS a similar pressure differential variable opening to the secondary fluid or a fixed opening. 3,527,056 9/1970 Hoffman 239/410 3,632,041 1/1972 Ghougasian r. 239/533 17 Claims, 2 Drawing Figures I l, /;b 246 2 r 'e ialf ii 451;"

! 24 1 2 e I II)IIIfVIIA 7 k9 /6 I 1 a3 1 1 V22. PRESSURIZED 20 I3 FLUID l0 1 SECONDARY FLUID Pmmmmw 5 1914 '31345904 PRESSURIZED FLUID l0 SECONDARY FLUID 5TAGE STAGE TRAVEL TRAVEL.

PRESSURIZED FLUID SECONDARY FLUID VARIABLE FLOW TWO STAGE NOZZLE In my U.S. patent application, Ser. No. 368,353, entitled Variable Flow Pressure Venturi Nozzle and assigned to the assignee of the present invention, there is disclosed a venturi type nozzle that induces flow of secondary fluid by movement of a pressurized fluid. The nozzle has a variable sized inlet or opening for the secondary fluid with the opening size varying inversely with a difference in pressure between that existing at the discharge and that existing at the secondary fluid input. Thus, as the pressure difference increases, the opening decreases in size until the opening can be made to be completely closed for a differential pressure that would cause reverse flow to the input or other malfunctioning of the nozzle. The discharge is then only that of the pressurized fluid.

By varying the size of the opening the quantity of flow of secondary fluid is made to be related to the pressure .difference with the large flow occurring at a small differential pressure and little or no flow oceurring at a high differential pressure. The nozzle thus becomes quite efficient over a much broader range of operating conditions than if the opening was fixed, the latter having in effect only one condition for efficient operation.

While such a nozzle has been found completely satisfactory for its intended purpose, its range of efficient operation, though greater than a fixed nozzle is still limited and has tended to prevent its usage in many applications. This especially applies to a situation where a large quantity of secondary fluid flow is desired to be efficiently induced to flow at a low differential pressure while still retaining the ability of the nozzle to efficiently function at much higher differential pressures. Onesuch application is a pressurized air operated vacuum cleaner.

It is accordingly'an object of the present invention to provide a variable flow nozzle that is efficient over a larger range of operating conditions than theretofore suggested nozzles.

Another object of the present invention is to provide a variable flow nozzle that is quite efficient in moving a large volume of secondary fluid at low differential pressures but is still effective at higher differential pressures to induce fluid flow.

A further object of the present invention is to achieve the above objects with a variable flow nozzle that is extremely simple in construction, economical to fabricate and durable and reliable in use.

ln carrying out the present invention there is provided a variable flow nozzle that consists of two separate nozzle means or stages, each capable of inducing secondary fluid flow. The first stage is connected to a source of pressurized fluid that powers the nozzle and also to a secondary fluid source and the flow of the former induces flow of the latter. The combined fluids exit together from the first state and are directed to the second stage with the first stage discharge constituting the pressurized fluid for powering the second stage. This second stage is also connected to a source of secondary fluid, which generally is the same as the secondary fluid for the first stage, and the flow of the first stage discharge induces in the second stage the flow of more secondary fluid. The discharge from the second stage is the total discharge from the nozzle and consists of the pressurized fluid and the secondary fluid induced to 2 flow by the first stage and also-the secondary fluidinduced to flow by the second stage.

The second stage is made to have a variable size opening through which the secondary fluid flows and the size of the opening is made to be pressure differential responsive to the differential pressure existing between that at the discharge and'ofthe secondary fluid. Preferably its response is such as -to have it completely closed at quite low pressures on the order of a few inches of mercury, thus assuring that reverse flow through the opening will not occur andthus enables-the second stage to utilize the relatively -large volume, low pressure discharge from the first stage as its powering fluid.

The first stage may be either a fixed nozzle having a constant opening to the secondary fluid :source or may bodiments, however, the first stage is capable of functioning with a higher differential pressure than that required to close the opening in the second stage. Preferably with a variable opening first stage, it is adjusted to maintain its opening fully open until theopening of the second stage closes thereby providing a continuous relationship between the differential pressure and the size of the opening or openings through which secondary fluid flows.

Other features and advantages will hereinafter appear.

In the drawing:

FIG. 1 is a diametric cross-sectionQof a variable flow two stage nozzle made in accordance with the present invention.

FIG. 2 is a section similar to FIG. 1 showing a further embodiment of a variable flow two stage nozzle.

Referring to the drawing, the nozzle of the present invention is generally indicated by the reference numeral l0 and includes a cylindrical housing 11 that is formed with a connection 12 for communication with a source of secondary fluid, so that the latter thus fills the housing.

A source of pressurized fluid is connected to a pipe 13 to flow through a port 14 formed between a conical valve stem 15 and an apertured tube 16. The port 14 is located adjacent an entrance 17a of a passageway l7 formed in an annular member 18 secured as by a screw 18a to the housing. The passageway 17 is shaped so that the flow of pressurized fluid from the port 14 and through it induces flow of secondary fluid into the entrance l7a as shown by the arrows 19 to be discharged from the exit 1712.

A ring 20 is secured as by a screw 21 to the interior of the housing and is connected to a cylindrical member 22 by means of a corrugated rubber hoop 23 having a somewhat U-shaped cross-section. The hoop 23 is resilient and tends to maintain the member 22 in the solid line position and permits but urges against, movement of the member 22 to the dotted line position shown. A passageway 24 is formed in the member and has an entrance 24a and an exit 24b. The housing end is open so that the exit 24b communicates exteriorly of the housing, it being understood that the hoop 23 blocks off the open end except for the exit 24b.

The passageway 24 is aligned with the passageway 17 so that fluid discharged from the exit 17b is directed into the passageway 24 which has an interior shape to cause this flow to induce the flow of secondary fluid through the opening that exists between the members 3 18 and 22 with the flow being indicated by arrows 25.

n the operation of the nozzle, the pressurized fluid flowing out of the port 14 induces flow of secondary fluid into the passageway 17 and both comingle and are discharged through the exit 17b. This discharge is directed at the entrance 24a of the passageway 24 into which it flows to induce flow of secondary fluid in the direction indicated by the arrows 25, also into the entrance 24a. The combined fluids are discharged through the exit 24b.

The ambient pressure adjacent the exit 24a exerts a force which tends to move the member 22 rightwardly and this is opposed by the pressure within the housing, which is essentially the pressure of the secondary fluid. Considering that the exit 24b is open to the atmosphere and the housing is basically a closed container having the same pressure as the secondary fluid, operation of the nozzle will cause the pressure of the secondary fluid to decrease as its absolute pressure decreases by reason of it being evacuated from the source. A suction is formed in the housing. This decreases the force acting on the interior of the member 22 and hoop 23 thereby increasing the difference in pressure on both sides of the member 22 and this pressure differential produces a force which causes the member 22 to be moved rightwardly against the urgings of the hoop 23. The rightward movement restricts the opening between the member 22 and the member 17 through which the secondary fluid can flow into the entrance 24a.

With a selected value of differential pressure, this opening can become completely closed and thus secondary fluid is blocked from flowing in the direction indicated by the arrows 25. This position of the parts is indicated by dotted lines and thus the only fluid being discharged is the pressurized fluid and the fluid induced to flow through the passageway 17. In between these two extremes, the member 22 will find a position which effects a balancing of the forces of the rubber hoop 23 and the pressure differential. One value of selected differential pressure to cause complete closure maybe on the order ofa few inches of mercury such as 4 or 5. The blocking of this opening, while preventing flow of secondary fluid also prevents fluid exiting from the passageway 17 from effectively recirculating back to the secondary source by flowing in a direction opposite to the arrows 25. However, for differential pressures below the selected value, substantial quantities of secondary fluid are induced to flow by the discharge from the passageway 17 even though it is a relatively large volume, low pressure flow.

Referring to the embodiment shown in FIG. 2 and indicated generally by the reference numeral 27, the nozzle in this embodiment varies from the previously disclosed embodiment in that the opening for the secondary fluid into the first stage is also made variable instead of being fixed as in the previous embodiment. The nozzle 27 has a housing 28 formed with communieating

tubes

29 and 30 that are connected together to the same source of secondary fluid, though if desired they could be connected to separate sources. A source of pressurized fluid is conducted through a pipe 31 to exit through a port 32 in the same manner as previously described. An annular member 33 having a passageway 34 has the diametric shape shown, is movably mounted in the housing and is normally urged by a spring 35 to abut against a ledge 36. The passageway 34 has an exit 34b aligned with the entrance 37a of a passageway 37 formed in a tubular member 38. A spring 39 urges the member 38 leftwardly against a stop 40 and thus tends to maintain the

members

33 and 38 apart.

The member 38 is capable of sliding movement within the housing 28 and an O-ring seal 41 may be provided to insure against leakage.

In the operation of this embodiment of a two stage nozzle, the pressurized fluid exiting from the port 32 into the passageway 34 induces flow (shown by arrows 42) of secondary fluid into the passageway and the combined fluids are discharged into the entrance 37a where the flow induces flow of secondary fluid into the entrance 37a as shown by the arrows 43. The combined fluids are then discharged from the exit 37b. As in the previous embodiment the position of the tubular member 38 depends upon the difference in pressure between that at the exit 37b and that of the secondary fluid within the housing and as this pressure difference increases, the member 38 moves rightwardly against the action of the spring 39. At a relatively low differential pressure, on the order of a few inches of mercury, the opening through which the secondary fluid flows (shown by arrows 43) becomes completely closed. As the differential pressure continues to increase, as for example, the absolute pressure of the secondary fluid decreasing while the exit ambient pressure remains constant at atmospheric, the member 38 will continue to move rightwardly and force the member 33 also rightwardly until the opening through which the secondary fluid flows (shown by arrows 42) for the first stage becomes closed. The lengthwise movement of the first stage member 33 is indicated by the arrows 44 while the movement of the member 38 is indicated by the arrow 45. It will thus be seen that with this embodiment of the invention there is a regulation of the size of the opening through which secondary fluid can flow throughout the entire operating range of the nozzle with the stages of the nozzle assuming the position at which they function more efficiently based on the differential pressure.

Accordingly. it will be understood that there has been disclosed a variable flow, two stage nozzle in which the first stage utilizes the flow of pressurized fluid to induce flow of secondary fluid while the discharge from the first stage constitutes the pressurized fluid for the second stage to induce more flow of secondary fluid. However, as the difference in pressure between that at the discharge and that of the secondary fluid increases, the opening through which secondary fluid may flow into the second stage is decreased and may be completely blocked to prevent reverse flow of fluid. However, the first stage will still function to induce flow of secondary fluid. Moreover, the first stage may have a fixed opening for the secondary fluid or if desired, it too may have a differential pressure responsive variable size opening for the secondary fluid.

Variations and modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. A variable flow two stage nozzle comprising a first nozzle means having a first passageway formed with an exit, means connectible to a source of pressurized fluid for directing a flow of pressurized fluid into the first passageway and means for communicating the passageway with a source of secondary fluid whereby flow of pressurized fluid in the first passageway induces flow of secondary fluid therein to have both fluids be ejected from the exit; a second nozzle means having a second passageway formed with an exit, means for directi ig the flow from the first nozzle means into the second passageway and means for communicating the second passageway to another source of secondary fluid whereby the flow of the fluid from the first passageway,

2. The invention as defined in claim 1 in which the source of secondary fluid is the same as the another source of secondary fluid.

3. The invention as defined in claim 1 in which the selected value is a value which is no greater than the value that would effect reverse flow of fluid through the second nozzle means communicating means.

4. The invention as defined in claim 1 in which the ambient pressure differential responsive means includes means urging the second nozzle communicating means open.

5. The invention as defined in claim 4 in which the pressure differential varying means varies the size of the opening for different values of differential pressure below the selected value.

6. The invention as defined in claim l in which the second nozzle communicating means includes at least a pair of surfaces, in which the surfaces are mounted for relative movement and in which for the selected value of differential pressure, the surfaces abut to prevent communication.

7. The invention as defined in claim 1 in which the second nozzle means passageway has an entrance and in which the exit of the first nozzle means is aligned therewith.

8. The invention as defined in claim 7 in which the first nozzle means includes one surface adjacent the exit, and the second surface is adjacent the entrance of the second nozzle means and in which the means for communicating to the second passageway is between these surfaces.

9. The invention as defined in claim 1 in which the first nozzle means communicating means has a constant size means for communicating.

10. The invention as defined in claim 1 in which the first nozzle means includes means responsive to the differential pressure between adjacent the exit of the second nozzle means and the source of secondary fluid for varying the communicating means'between the first passageway and the source of secondary fluid.

11. The invention as defined in claim 10 in which the first nozzle means for varying includes means for urging enlargement of the communicating means and in which said urging means is effective for values of differential pressure below a determined value.

12. The invention as defined in claim 11 in which the selected value of the second nozzle means essentially approximates the determined value of the first nozzle means.

13. A variable flow two stage nozzle comprising a housing having an open end, a first member formed to provide a through passageway having an entrance and an exit with the exit being at the open end, means sealing the open end except for the exit, means mounted the first member for relative movement in the housing, a second member mounted in the housing and having a through passageway with an exit and an entrance, said passageways being aligned with the exit of the second member being adjacent the entrance of the first member, means for communicating the housing with a source of secondary fluid, means connectible to a source of pressurized fluid for directing a jet therefrom into the entrance of the second member and means for urging the first member away from the second member against the force of the difference in pressure existing between the inside and the outside of the housing.

14. The invention as defined in claim 13 in which the first member is mounted for movement in the housing with respect to said second member, and in which there is a selected value of pressure difference required to overcome the urging means to cause the first member to abut the second member.

15. The invention as defined in claim 14 in which the second member is mounted for movement in the housing, means urging the second member towards the first member and in which there is a determined value of pressure difference required to overcome the second member urging means before movement of said second member occurs.

16. The invention as defined in claim 15 in which the selected value approximates the determined value.

17. The invention as defined in claim 16 in which the first member maintains abutment with the second member as the latter moves for values of pressure difference above the determined value.

Claims

1. A variable flow two stage nozzle comprising a first nozzle means having a first passageway formed with an exit, means connectible to a source of pressurized fluid for directing a flow of pressurized fluid into the first passageway and means for communicating the passageway with a source of secondary fluid whereby flow of pressurized fluid in the first passageway induces flow of secondary fluid therein to have both fluids be ejected from the exit; a second nozzle means having a second passagaway formed with an exit, means for directing the flow from the first nozzle means into the second passageway and means for communicating the second passageway to another source of secondary fluid whereby the flow of the fluid from the first passageway into the second passageway induces the flow of secondary fluid in the second passageway to have the fluids discharged from the second passageway exit and means responsive to a selected value of pressure differential existing between adjacent the exit of the second passageway and the another source of secondary fluid for closing the communicating means between the second passageway and the another source of secondary fluid.

6. The invention as defined in claim 1 in which the second nozzle communicating means includes at least a pair of surfaces, in which the surfaces are mounted for relative movement and in which for the selected value of differential pressure, the surfaces abut to prevent communication.

10. The invention as defined in claim 1 in which the first nozzle means includes means responsive to the differential pressure between adjacent the exit of the second nozzle means and the source of secondary fluid for varying the communicating means between the first passageway and the source of secondary fluid.