US3374799A

US3374799A - Fluid flow control system

Info

Publication number: US3374799A
Authority: US
Inventors: Lyman Brooks
Original assignee: Pitney Bowes Inc
Current assignee: Pitney Bowes Inc
Priority date: 1962-06-21
Filing date: 1964-11-25
Publication date: 1968-03-26
Anticipated expiration: 1985-03-26
Also published as: FR1454855A; GB1057512A; BE672756A; DE1475798A1

Abstract

1,057,512. Pure fluid amplifiers. PITNEYBOWES, Inc. Nov. 5, 1965 [Nov. 25, 1964], No.46977/65. Heading G3H. A pure fluid switch comprises a main flow passage 33 from which branch passages 37, 38 lead at an angle of between 15 and 45 degrees to the main passage, the passages being of uniform cross-section. Signal ports 45, 46 are provided at right angles to the branch passages 37, 28 and downstream of the point of intersection. When pressure fluid is supplied to the inlet 34 of the passage 33 the flow will divide between the passage 33 and one of the branch passages, say 37. To switch the flow from passage 37 to passage 38, pressure is applied at above a predetermined value to port 45 or suction is applied at 46. The flow may also be switched by interrupting the main flow and applying a pressure at 45 below the predetermined value and then re-establishing the main supply. The interruption of the main flow may be achieved by blocking the outlet of passage 33 or by applying a pressure signal through a port 54.

Description

March 26, 1968 B. L Y MAN 3,374,799

FLUID FLOW CONTROL SYSTEM Original Filed June 2l, 1962 ,X @l 7 INVENTOR. Brooks LymcL/z/ HTTO/QNEY United States Patent O l 3,374,799 FLUID FLOW CONTROL SYSTEM Brooks Lyman, Pound Ridge, N.Y., assigner to Pitney-Bowes, Inc., Stamford, Conn., a corporation of Delaware Original application June 21, 1962, Ser. No. 204,206,

now Patent No. 3,194,253. Divided and this application Nov. 25, 1964, Ser. No. 413,943 2 Claims. (Cl. 137-815) This application is a division of copending application Ser. No. 204,206, tiled June 21, 1962, for Fluid Flow Control Device, now Patent No. 3,194,253.

This invention relates to a novel fluid ow control arrangement which has no moving may be utilized to establish and maintain variable llow paths for a liuid stream. More particularly, the invention relates to a novel fluid ow control system for dividing a lluid supply stream into two constituent streams, one of the constituent streams always flowing through a principal exhaust conduit and the other constituent stream selectively owing through one of a plurality of branch exhaust conduits.

Various iiuidic devices having no moving parts have recently been developed. For example, U.S. Patents 3,024,- 805 and 3,030,979 respectively illustrate different arrangements which may be used in controlling a liuid ow. In the operation of such known devices the iluid supply stream passes through a nozzle and is then selectively directed along one of a plurality of different possible ow paths by appropriate control means so that for any given operating condition the iluid supply stream remains substantially undivided and extends principally along one predetermined path through the system. The instant invention on the other hand contemplates dividing the fluid supply stream into at least two separate streams which are selectively directed along two of at least three possible flow paths. Here for a given supply stream and a given operating condition of the system two predetermined separate and simultaneous exhaust flow streams are always produced. The operating condition of the system may be shifted by the application of relatively small fluid control signals at points in the two individual exhaust streams that are located respectively downstream from the point where the division of the main supply stream occurs. This operational shifting may be obtained by using two distinct levels of signal power, a lower power signal being eiective upon initiation of system operation while an effective higher power signal is required after the system is in operation.

The present type of system may be used where a smallsignal low-power fluidic control is desired.

One object of the invention is to lprovide an improved fluid ow control system having no moving parts.

Another object of the invention is to provide an improved fluid flow control system wherein a main fluid supply stream is divided into two separate streams, one of the separate streams always owing along a fixed path while the other separate stream selectively flows along different predetermined paths.

Another object of the invention is to provide a fluid ow control arrangement wherein a single fluid supply stream may be divided and directed along at least two of a plurality of separate individual tlow paths, and wherein selective direction of a divided portion of said stream may be controlled from points downstream from the respective initial portions of said individual ow paths.

A further object of the invention is to provide a novel uid flow control system wherein fluid control signals of different intensity levels are operable to shift the operating condition of the system depending respectively on whether 3,374,799 Patented Mar. 26, 1968 the system is or is not operating at the time of application of the control signals.

Another object of the invention is to provide a novel fluid control system wherein a control signal, having a power level below that normally required to shift the operating condition of the main uid ow, is applied before initiation of said main fluid flow whereby the said control signal will be capable of causing the said main iluid ow to assume a desired condition.

Further objects and advantages of the invention will become apparent as the description proceeds.

In the drawings:

FIG. 1 is a plan View showing the grooved construction of a main lower plate member utilized in one embodiment of the instant invention;

FIG. 2 is a side elevational view showing the sandwich type unit construction used in said one embodiment of the invention;

FIG. 3 is a transverse sectional view taken along section line 3-3 of FIG. 1.

In the illustrative embodiment of the invention shown in FIGS. 1-3 a sandwich type construction is utilized wherein a main body unit 30 comprises a lower grooved plate 31 and an upper cover plate 32 that is secured in superimposed sealed relation with respect to lower plate 31. The upper surface of grooved plate 31 is formed with an elongated and substantially straight cylindrically cross sectioned channel 33 one end of which communicates, by means of a suitable fitting 34 and llexible tubing 35, with a suitable fluid flow source indicated by arrow 36. Two straight symmetrically arranged

divergent branch channels

37 and 38 are formed in plate 31 so las to communicate with the main channel 33; the axes of

channels

37 and 38 intersecting at a common point 40 along the intermediate portion of the main channel axis 41. The angles B, FIG. 1, are substantially equal and may have a value of between 15 and 45 degrees. An exemplary value of 25 degrees has been found to be very satisfactory. There are no substantial restrictions in the

cylindrical channels

33, 37 and 38, and each channel has a substantially uniform cross sectional shape and size throughout its effective length particularly in the region of the junction 40.

In the operation of the trident fluid conduit arrangement thus far described a main i'luid supply stream in being introduced into the main channel 33 from source 36 is columnated as it flows along the elongated portion of said main channel 33 located upstream from junction 40. When arriving at junction 40 one part of the iluid stream will always exhaust through the downstream portion 33b of the main channel while the other part of said main stream will exhaust either through the branch channel 37 as indicated by arrow 43 or through the branch 38 as indicated by arrow 44. Whichever mode of operation exists at any given time i.e., whether air is exhausting as at 42, 43 or as at 42, 44 the flow conditions will persist and will be stable until the flow system is changed by the application of control signals as will be described below.

A pair of uid

signal control channels

45 and 46 are formed in plate 31; these control channels respectively communicating with said

branch channels

37 and 38 at points downstream from the region of the junction 40. The

control channels

45 and 46 are respectively connected by means of

suitable fittings

47 and 48 to suitable conduit means, such as

exible tubing

50 and 51, through which iiuid control signals may pass. With no control signals applied through

control channels

45 and 46 the instant device will have, upon initiating the ow on the main stream, an initial preferred operational mode wherein a portion of the main fluid stream will always flow or exhaust through a predetermined one of said

branch channels

37 and 38. Let it be assumed that the initial preferred operational mode is such that channel 33b and the branch channel 37 are conducting while lbranch channel 38 remains non-conducting. When it is desired to shift or change this operational mode of the system a control signal is initiated in the control channel 45 as indicated by arrow 52, the power level of this-control signal being equal to or greater than a predetermined minimum. In response to the application of this control signal, which may be momentary in duration, the operational mode of the system will be shifted so that branch channel 38 is now conducting while 37 is non-conducting. Instead of initiating a positive control signal, i.e. one above atmospheric pressure, in the control channel 45 the same mode shifting action may be obtained here by initiating a corresponding negative or sub-atmospheric control signal in the control channel 46 as indicated by the arrow 53, FIG. 3. With the channels 33b and 38 now conducting and channel 37 non-conducting it is possible to shift back to the original operational mode by introducing either `a positive control signal, having a fluid power level above said predetermined minimum level, into control channel 46 or a corresponding negative fluid control signal into the control channel 45 whereupon the device will assume its iirst mentioned operational mode wherein channels 37 and 33b are conducting. In either operational modev a slight sub-atmospheric pressure will normally exist in the non-conducting branch channel of the unit.

The system illustrated in FIGS. 1-3 may under certain conditions be controlled by the application of control signals that have less than the minimum power mentioned above. Normally when a positive control signal of predetermined reduced power, that is a signal below said predetermined minimum, is initiated in the appropriate control channel the operational mode of the system will not be shifted. If however such reduced power control signal is maintained and the ow of the main stream through the channel 33 is momentarily interrupted then upon the re-establishment of the main stream the maintained reduced signal will be sufficient to cause the shift in the operational mode. As will be apparent this type of control arrangement will be desirable where a control signal is to be maintained or stored until such time as it is to become eiective upon the initiation of another command signal. The said interruption of the flow of the main uid stream may be accomplished by cutting off the stream source or by blocking the downstream endA of the main channel 33; however a third procedure may under some conditions be preferable. Here the lower grooved plate 31 of the body unit 30 is provided with a control channel 54 which communicates with channel portion 33b and which by means of a suitable fitting 55 communicates with a suitable conduit means, such as the exible tubing 56, through which control signals may pass as indicated by arrow 57, FIG. 2. By introducing a positive signal into the control channel 54 the main uid stream may be momentarily disturbed to the extent necessary to produce the above described reduced signal mode shifting action.

While one embodiment of the invention has been shown and described, it will be apparent to those skilledv inthe art that numerous variations and modifications may be made in the particular construction without departing from the underlying principles of the invention. It is therefore desired, -by the following claims, to include within the scope of the invention all such variations and modications whereby substantially the results of the invention may be obtained by the use of substantially the same or equivalent means.

The invention claimed s:

1. A method of selectively controlling the flow of a fluid along at least two predetermined ow paths; comprising the steps of providing a iiuid ow source;

establishing a continuous main fluid stream from said source;

establishing two symmetrically disposed divergent ow paths which communicate at a substantially cornmon point with the main stream whereby at any given time at least a portion of said main stream is conducted along only one of said divergent ow paths, this fluid flow system normally remaining in a stable condition until caused by a predetermined uid control signal having atleast a predetermined minimum power to shift to another stable condition wherein at least a portion of the main stream is conducted `.along the other of said divergent paths;

applying a reduced fluid control signal having a power less than said predetermined minimum power to said [rst and second] one of said divergent flow paths downstream of said common point;

interrupting the luid ow along the main stream during the application of said reduced fiuid control signal; and

recstablishing said main fluid stream during the application lof said reduced fluid control signal so that at least a portion of the main Huid stream ows along only the said other of said divergent flow paths.

2. The method defined by claim 1 wherein said reduced control signal is applied before the initiation of the step of interrupting the said main uid stream from said source.

References Cited UNITED STATES PATENTS 3,024,805 3/ 1962 Horton 137-81.5 3,122,165 2/1964 Horton 137-815 3,148,691 9/ 1964 Greenblott 137-81.5 3,159,168 12/1964 Reader 137-8l.5 3,185,166 5/1965 Horton et al. 137-81.5 3,192,938 7/1965 Bauer 137-81.5 3,204,652 9/ 1965 Bauer 137-815 M. CARY NELSON, Primary Examiner.

S. SCOTT, Assistant Examiner.

Claims

1. A METHOD OF SELECTIVELY CONTROLLING THE FLOW OF A FLUID ALONG AT LEAST TWO PREDETERMINED FLOW PATHS; COMPRISING THE STEPS OF PROVIDING A FLUID FLOW SOURCE; ESTABLISHING A CONTINUOUS MAIN FLUID STREAM FROM SAID SOURCE; ESTABLISHING TWO SYMMETRICALLY DISPOSED DIVERGENT FLOW PATHS WHICH COMMUNICATE AT A SUBSTANTIALLY COMMON POINT WITH THE MAIN STREAM WHEREBY AT ANY GIVEN TIME AT LEAST A PORTION OF SAID MAIN STREAM IS CONDUCTED ALONG ONLY ONE OF SAID DIVERGENT FLOW PATHS, THIS FLUID FLOW SYSTEM NORMALLY REMAINING IN A STABLE CONDITION UNTIL CAUSED BY A PREDETERMINED FLUID CONTROL SIGNAL HAVING AT LEAST A PREDETERMINED MINIMUM POWER TO SHIFT TO ANOTHER STABLE CONDITION WHEREIN AT LEAST A PORTION OF THE MAIN STREAM IS CONDUCTED ALONG THE OTHER OF SAID DIVERGENT PATHS; APPLYING A REDUCED FLUID CONTROL SIGNAL HAVING A POWER LESS THAN SAID PREDETERMINED MINIMUM POWER TO SAID (FIRST AND SECOND) ONE OF SAID DIVERGENT FLOW PATHS DOWNSTREAM OF SAID COMMON POINT; INTERRUPTING THE FLUID FLOW ALONG THE MAIN STREAM DURING THE APPLICATION OF SAID REDUCED FLUID CONTROL SIGNAL; AND RE-ESTABLISHING SAID MAIN FLUID STREAM DURING THE APPLICATION OF SAID REDUCED FLUID CONTROL SIGNAL SO THAT AT LEAST A PORTION OF THE MAIN FLUID STREAM FLOWS ALONG ONLY THE SAID OTHER OF SAID DIVERGENT FLOW PATHS.