US 3598288 A
Description (OCR text may contain errors)
United States Patent Edward S. Pmglte 82 West Deane Park Drive, lslington, Ontario, Canada June 26, 1969 Aug. 10, 1971 inventor Appl. No. Filed Patented FLEXIBLE TUBDMETERING DEVICES 3 Claims, 5 Drawing Figs.
US. Cl 222/711. 251/4 Int. Cl. G04c 23/38 Field ol Search 222/70, 309, 333, 340; 103/148; 92/90; 251/4; 417/412, 478
Reierenees Cited UNITED STATES PATENTS 1,973,180 9/1934 Scott 103/148 2,393,838 1/1946 Tarbox 103/148 2,849,159 8/1958 Kaufmann 222/309 3,010,615 11/1961 Smith et 222/333 X 3,171,360 3/1965 103/148 3,182,602 5/1965 103/148 3,349,716 10/1967 103/148 Primary Examiner-Robert B. Reeves Assistant Examiner-T. E. Kocovsky Attorney-Fetherstonhaugh & Co.
ABSTRACT: A fluid-metering device for injecting measured quantities of additive liquids into hydraulic systems and characterized by a length of flexible tubing, with means for bending the tubing so that it acts as a shutoff valve or a variable flow rate valve.
PATENTED me I 0 I971 SHEET 1 0F 2 l/ l [111/ l/ FIG. 'I
INVEN'I 01 EDWARD s. POSGATE BY jj fiaw ATTORNEYS FIG. 2
FLEXIBLE TUBE-METERING DEVICES This invention relates to fluid-metering devices such as those that are used to inject measured quantities of liquids into hydraulic systems.
For example, in swimming pool operations it is necessary to inject into pool water precisely measured quantities of chlorine, soda ash and diatomaceous earth solutions and slurries. It is necessary to adjust the rate at which these chemicals are injected, according to any variation in the quality of pool water. The purpose of such chemical feed adjustment is to maintain water quality within specified limits well known in the art.
The conventional method of injecting measured quantities of chemicals is by means of piston or diaphragm-metering.
pumps which are fitted with manually adjustable cams for positioning the stroke of the piston or diaphragm. It has been found, however, that the adjustment range of these prior art devices is very small and relatively inaccurate. Further, the metering pumps of conventional design are driven by electric motors and have many moving parts so that extensive routine maintenance is required to keep them in good working order. Further, the conventional pumps are incapable of extremely low flow rates, and in the low flow rate range they are relatively unreliable.
In addition to the foregoing disadvantages, conventional metering pumps are expensive to manufacture, to install and to repair.
ltis, therefore, the primary object of this invention to provide fluid-metering devices and pumps which can be manufactured, installed and maintained at less cost than the conventional metering pumps known heretofore.
It is a more specific object of the invention to provide fluidmetering devices and pumps which are generally more reliable than conventional metering pumps. More specifically, the devices or pumps of the present invention are less subject to clogging, more reliable in the low flow rate range, and fully adjustable with respect to both feeding time intervals and quantity of feed.
The above and further objects of the invention are achieved by a metering device or pump characterized by the use of s flexible tube and means for bending the tube so that it acts as either a shutoff valve or as a variable flow rate valve. In one embodiment such a tube is used in conjunction with means for squeezing the tube downstream from the bent portion of the tube with the squeezing of the tube acting in conjunction with the bending of the tube to provide more accurate control on the flow rate through the tube and to carry out other functions as explained hereinafter.
The invention will be more thoroughly understood from the following description of several embodiments thereof as read in conjunction with the accompanying drawings.
in the Drawings:
FIG. I is a side elevation view, somewhat schematic, of a liquid-metering device in accordance with a first preferred embodiment ofthe invention;
FIG. 2 is a side elevation view of a part of the device of FIG. I;
FIG. 3 is a side elevation view, partially schematic, oi a second preferred embodiment of s metering device in uc= cordance with the invention, this embodiment also perforating a pumping action;
FIG. 4 is a side elevation view ofs part ofthe device acoord= ing to FIG. 3; and
FIG. 5 is a side elevation view of a modified form of the part ofthe FIG. 3 device that is shown in FIG. 4.
Referring to FIG. I, it should be understood that it is the basic function of the device to feed a liquid additive from container 12 into a primary fluid flowing through conduit Id.
In the FIG. 1 embodiment ofthe invention, the pressure dif ferential causing the additive fluid to flow from container 12. to conduit 14 is gained by an eductor 16 in conduit 1 but it should be understood that the device of the invention is adaptable to controlling the rate of additive feed when the pressure differential is created in another way, for example, by the provision of a positive pressure pump at container 12. As stated above, in the FIG. 1 embodiment the pressure differential is effected by the use of an eductor 16 and as the operating principle of an eductor is well known, it is not described in detail herein nor are the other possible alternative ways of creating a pressure differential between container 12 and conduit 14.
While it has been stated above that it is the primary object of device 10 to feed a fluid additive to conduit 14, the function of device 10 can be described more precisely as the controlling of the rate of introduction of a fluid additive into a primary fluid flow in conduit 14.
Referring still to FIG. 1, device 10 essentially consists of a flexible tube 18 and means 20 for bending the tube in a controlled manner. Tube bending means 20 consists of a solenoid 22 carrying a bar 24 carried at the free end of its rod 26. Tube 18 is attached to bar 24 by a clamp 28 and a spring 30 is fixed to clamp 28 by one end and anchored to the frame of the device at its other end.
In FIG. I, solenoid 22 is shown as it exists in its energized position, In this position, the tube takes up a form which permits free passage of additive fluid from container 12 to conduit 14. Upon deenergization of the solenoid, the weight of bar 24 and spring 30 cooperate to bend the tube so that it assumes the position shown in FIG. 2.
It can be seen, therefore, that by the operation of the solenoid, tube I8 can be bent and unbent at will so that the tube operates as a valve, the collapsing of the tube at its bend serving to seal the tube to interrupt the flow of fluid through it.
From the foregoing, it will be understood that the control of fluid flow through tube 18 is simply achieved by bending the tube as required employing a solenoid as a preferred means for doing so. It will also be understood that any number of possible arrangements could be employed for operating the solenoid or timer. Thus, for example, an arrangement based on a device for continuously analyzing the chemical composition of the primary fluid in conduit 14 could be used to feed and/or interrupt current to the solenoid as to open and close the tube valve.
By way of illustration, however, the embodiment oi FIG. it employs a timer 3d placed in series between solenoid 22 and power supply 36. The timer can be preset to govern the frequency at which the flexible tube opens and collapses and it also determines the amount of time during which the tube remains open. thereby the amount of fluid injected into conduit 14 is governed. As a preferred arrangement, timer 34 is used in conjunction with a valve 38 in an eductor bypass line 40. Thus. valve 38 can be adjusted to govern the amount of the primary fluid which passes through eductor 16 whereby a basic adjustment of the amount of additive fluid fed to conduit is is controlled by the variable pressure differential effected by eductor 16. depending upon the operation of valve 38. This control of the pressure differential working in conjunction with timer 34 provides an extremely sensitive adjustment to the rate and amount of additive fluid being fed to conduit 14. Tests have shown that the flow rate range possible is from less than 0.001 ml. to 2000 ml. a minute or more. Larger flow rates in the same degree can be achieved, depending upon the sizes of the components selected.
There are numerous advantages in the flow rate=adjusting device in accordance with the invention. These advantages stem from the use of a flexible tube as combined with means for bending the tube to seal it off and open it as desired. Firstly, replacement oftho flexible tube is very simple, and by selecting the proper type and size of tube material. long operating life can be expected. The simplicity of replacement of the tube is important in medical npparati, where danger of cross infection can occur. A new sterile tube can be used to replace the used tube at negligible cost. The flexible tube valve of the invention may also be used in recirculation machines such as artificial kidneys where it is desirable to stop blood flow when certain temperature and pressure limits are exceeded, and to immediately supply blood when temperature and pressure ranges are normalized. For this type of application, the flexible tube valve of the invention is ideal as it is extremely hygienic and provides a positive seal.
Another advantage of the flexible tube-metering device of the invention is that the interval between the feeding of an additive fluid to a main fluid stream is adjustable over practically any time range, being limited only by the range of timer selected. In conventional metering pumps, employing a piston or a diaphragm, the time interval is limited by a cam. Further, as time control in the present device is electronic, the period of injection can be as low as one fiftieth of a second. This extremely low time rate is difficult and costly to achieve by mechanical means. Further, the metering device of FIGS. 1 and 2 has a continuous flushing action through eductor l6 and the device is intended for the transfer of solids in a slurry. This continuous flushing action prevents solids of high specific gravity from settling in the conduit 14.
The embodiment of FIG. 3 combines the flexible tube valve with means for squeezing the tube, the combination producing a device capable of a positive pumping action while maintaining its prime.
Referring to FIG. 3, the illustrated device is quite similar to the device OF FIG. 1 except that the bar 24 is longer and there is included a stop 42 and a conventional check valve 44. The addition of the latter two elements permits the device of FIG. 3 to act as a positive displacement pump, i.e. a device that is capable of raising a liquid held in container 12 and dispensing the liquid from a nozzle 46, for example, rather than simply controlling the rate r f flow set up by a pressure differential originating outside the device as is the case with the FIG. I AND FIG. 2 embodiment.
The FIG. 3 embodiment ofthe invention is used in those applications requiring precise fluid measurement but wherein it is not convenient or economic to provide means for maintaining a constant head of liquid in container I2. As previously mentioned, the FIG. I and FIG. 2 embodiment of the invem tion is capable of extremely accurate flow control only if a constant pressure head is maintained on the liquid held in container 12.
The device of FIG. 3 operates in the following manner. Con trol of the device is gained by timer .34 which periodically feeds current to solenoid 20 as desired. When no current is flowing through the solenoid, the weight of plunger 26 and spring 30 causes bar 24 to squeeze the tube against stop 42. At the same time, the tube is bent so that it is closed off. In fact, sealing of the tube at the bend takes place before the tube is squeezed between bar 24 and 42, Thus, in this instance the bend in the tube acts as a check valve preventing flow of liquid past the bent portion of the tube so that the liquid held in the tube in the area of stop 42 is forced past check valve 34 and out nozzle 46. Thus. the status of the device following inter= ruption of current to the solenoid is that a precise quantity of liquid. depending upon the size of of the tube and the size of stop 42, has been ejected from nozzle 46. Further. the closure of the bend in the tube will serve to thereafter maintain prime with respect to the liquid held in container 12. in this regard, it will be noted that this is the no-eurrent status of the device so that the prime can he held indefinitely and is in condition for immediate operation when operation iii required llii determined by timer 34 or any other mechanism for feeding current to the solenoid or timer.
When current to the solenoid or timer is initiated. the bar 2d is drawn away from stop l2 and as the lube opens due to its own resiliency, the internal volume of the tube between check valve M and the bend in the tube is increased. This. ofcourse. creates a negative pressure within this length of the tube and with check valve 44 automatically operating to close that end of the tube and with the bend in the tube opening, a negative pressure within the tube causes liquid to be drawn up from container 12. Thus, with the bar being raised to its highest position, that portion of the tube between container 12 and check valve 44 is full of liquid and prime is held by check valve 44.
On interrruption of current to the solenoid, the bar 24, assisted by spring 30, drops downwardly as previously explained to squeeze the tube against stop 42, thereby forcing liquid contained in the tube in the area of stop 44 outwardly past check valve 44 to nozzle 46.
It will be appreciated from the foregoing that the quantity of liquid dispensed depends upon the dimensions of the tube and the dimensions of stop "U." FIG. 4 shows a modified form of the FIG. 3 device in which stop 42 is replaced by a movable stop 48 and an adjusting cam 50 so that the quantity of liquid dispensed can be varied, depending upon the position of the cam. It has been found that flow rates of from 0.1 ml. to 50 ml. per minute are possible. Larger flow rates than 50 ml. per minute would be possible by increasing the size of all of the components used including the tube itself.
FIG. 5 shows another modified form of the device OF FIG. 3. The FIG. 5 arrangement provides an alternative means for adjusting the flow rate. In this modification, stop 42 takes the form oftwo side-by-side elements 42a and 4212 but the modification might also be used with the type of stop illustrated in FIG. 3. The important difference is that means is provided for varying the tension in spring 30 so that adjustment in the flow rate is gained, not by varying the position of stop 42 but by varying the amount of pressure exerted against the tube by bar 24. The spring tension variation is gained by means of a fine threaded screw 52 held in a threaded block 54.
From the foregoing descriptions of FIGS. 3, d and 5, it will be appreciated that flow rate adjustment essentially is gained by providing means for varying the amount by which the tube is squeezed. It should be appreciated that the embodiments of FIGS. 3, d and 5 are intended for use in applications in which it is not possible or desirable to effect a pressure differential across the device as by the use of an eductor, for example. Another application of the FIGS. 3 to 5 embodiments is where very precise metering is required and it is not possible or desirable to employ means for maintaining a constant head of liquid in container 112.
The FIGS. 1 and 2 embodiments, on the other hand, are more suited to the feeding of heavier additives as there are no conventional check valves which might tend to become clogged. The embodiments of FIGS. 1 and It have a continuous flushing action which prevents solids of high specific gravity from settling in the conduit 14 and/or eductor 16.
Finally, it will be recognized from the foregoing that all of the illustrated embodiments ofthe invention are characterized by the principle of bending a flexible tube, whether the bend in the tube acts as a flow control valve or as a check valve. The advantage of bending the tube is that a minimum amount of power is required to effect a perfect seal.
The perfect seal in the bent tube functions as a nonleaking check valve and this positively prevents loss of prime in all of the devices described. In effect, this ensures that liquid in correctly metered quantities is discharged immediately the solenoid is energized. The bent tube maintains prime for indefinite periods and there is no delay in the discharge of liquid, even after long periods of nonuse. This is not possible with convcm tlonal metering pumps; check valves necessary with such pumps leaii due to atmospheric pressure and supply pipes lose prime. Thus. immediate delivery of a precisely metered quanlily of liquid. after long ptllititill=llliti even short periodsoi nonuac. is not possible with conventional metering pumps.
What i claim as my invention is:
l. A fluid metering device comprising.
a. a housing.
b. a length of flexible tubing in said housing, said tubing having an inlet end secured relative to said housing and connectable to a source of secondary fluid and an outlet end secured relative to said housing and conncctable to a receiver for metered fluid.
c. bending means for bending said tubing mounted in said housing and having a movable head portion engaging said tubing intermediate the ends thereof, said bending means being operable to move said head portion rapidly to and fro in a straight path between the first position spaced a substantial distance from one secured end of said tubing and a second position more closely disposed with respect to said one secured end,
. said tubing having a first portion of a sufficient length to extend between said secured inlet end and said head portion of said bending means in a deep curved configuration without restricting the flow of fluid therethrough when said head is in said first position, said first portion of said tubing being folded upon itself about a single-fold line located between said head and said secured inlet and to prevent the flow of fluid therethrough when said head is in said second position, said flexible tubing having a second portion extending from said head to the other end thereof in a configuration and of a sufficient length so as to provide unrestricted flow between said head and said second end in all positions of said head,
e. and timer means mounted in said housing for controlling the movement of said head in said first and second positions.
2. A fluid-metering device comprising,
a. a housing,
b. a fluid inductor mounted in said housing and having input passage means opening out of said housing connectable to a source of primary fluid, output passage means opening out of said housing connectable to a fluid receiver and inductor passage means intermediate said input and output passage means, said inductor being operable in response to the flow uf a primary fluid therethrough to create a negative pressure condition in said conductor passage,
c. a length of flexible tubing in said housing, said tubing having an inlet end secured relative to said housing and connectable to a source of secondary fluid and an outlet end secured to said inductor in fluid communication with said inductor passage,
d. bending means for bending said tubing mounted in said housing and having a movable head portion engaging said tubing intermediate the ends thereof, said bending means being operable to move said head portion rapidly to and for in a straight path between the first position spaced a substantial distance from one secured end of said tubing and a second position more closely disposed with respect to said one secured end,
e. said tubing having a first portion of a sufficient length to extend between said secured inlet end and said head portion of said bending means in a deep curved configuration without restricting the flow of fluid therethrough when said head is in said first position, said first portion of said tubing being folded upon itself about a single-fold line located between said head and said secured inlet end to prevent the flow of fluid therethrough when said head is in said second position, said flexible tubing having a second portion extending from said head to the other end thereof in a configuration and of a sufficient length so as to provide unrestricted flow between said head and said second end in all positions of said head,
. and timer means mounted in said housing for controlling the movement of said head in said first and second positions.
3. A device as claimed in claim 2, in which said bending means consists of a solenoid having its plunger fixed to said length of tubing and spring means, also fixed to said length of tubing and biased to bend said tube, said solenoid being opera-