US3425357A - Peristaltic pump with regular air bubble introduction - Google Patents

Description

Feb. 4, 1969 T. BILICHNIANSKY ET AL 3,425,357

PEHISTALTIC PUMP WITH REGULAR AIR BUBBLE INTRODUCTION Filed Aug. 25, 1967 Sheet of 15 INVENTORE) THEODORE B/L/CHN/ANSKY m JACK ISRELI WILL/AM J. 5MY77/5 ATTORNEY Feb. 4, 1969 T. BIILICHNIANSKY ET AL 3,425,357

PERISTALTIC PUMP ITH REGULAR AIR BUBBLE INTRODUCTION Filed Aug. 23, 1967 Sheet 2 of 5 IN VEN TORS 7715000125 B/L/CH/V/AMS/(Y J ICK ISREEL/ WILL/AM J. SMYTHE ATTORNEY 3,425,357 PERISTALTIC PUMP WITH REGULAR AIR BUBBLE INTRODUCTION Filed Aug. 23, 1967 1969 T. BILICHNIANSKY ET Sheet F a E JNVENTORS THEODORE B/L/CH/V/ANSKY JACK 15/?554/ WILLIAM J. 5MYTH WGL ATTORNEY United States Patent 5 Claims ABSTRACT OF THE DISCLOSURE A peristaltic type pump has a plurality of pump tubes in side by side relation and a plurality of rollers, each operable in sequence to concurrently engage against a platen, to progressively occlude the tubes along their lengths, and to release the tubes, to advance fluids therethrough; an additional assembly including a pressure pin and a pad for normally occluding therebetween at least one of the pump tubes; and adjustable means for causing the pin and pad to release the tube periodically, once between the occasions of successive rollers releasing the tubes. A linkage is provided coupling the platen to the additional assembly, so that release of the platen from the tubes causes a release of the pin and the pad from the tubes.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to fluid pumps, and particularly to flexible tube or peristaltic type proportioning pumps which are advantageously utilized in flowing stream analytical systems.

Description of the prior art In systems of this kind, a flowing stream of sample liquid, which stream may be a continuous monitoring stream, or a stream of sequential liquid samples, is continuously mixed in a predetermined proportion with one or more reagents, and otherwise processed to provide a color reaction, the optical density of which at a particular wavelength is responsive to the concentration of a constituent of interest in the original sample. Such a system was initially disclosed in U.S. Patent No. 2,797,149, issued to L. T. Skeggs on June 25, 1957. Customarily, the flowing stream. of sample plus reagent is divided into sequential segments, each succeeding segment of sample plus reagent being spaced from the preceding segment by a gas segment. Each segment of sample plus reagent is then mixed up as it flows along in the stream, as shown in U.S. Patent No. 2,933,293, granted to A. Ferrari, Jr. on April 19, 1960. The streams of sample and reagent are supplied in a predetermined proportion to a junction by a peristaltic proportioning pump, such as is shown in U.S. Patent No. 2,935,028, granted to A. Ferrari Jr. et al. on May 3, 1960, or U.S. Patent No. 3,227,091, granted to J. Isreeli et al. on J an. 4, 1966. In such a pump a plurality of resiliently compressible tubes are disposed in side by side relation, and are all concurrently, and each progressively, occluded by a series of rollers, to positively advance fluids through these tubes. The relative proportion of volumetric rate of flow of these fluids are substantially determined by the relative inner crosssectional areas of the respective tubes.

In U.S. Patent No. 3,306,229, granted to W. J. Smythe on Feb. 28, 1967, it is taught that the relative proportions of volumetric rate of flow through the tubes do not remain constant during the period of operation of the pump. When the leading roller fully occludes the tubes, the relative proportions are constant. However, as the 3,425,357 Patented Feb. 4, 1969 ICC leading roller rises away from the tubes, the porportions will change it the tubes are of different internal diameters. This transient change in proportions between the sample and the reagents may affect the accuracy of the analysis system, which accuracy is premised on constant prop0rtions. The solution to this problem taught by U.S. Patent No. 3,306,229 is the provision of a peristaltic pump having a plurality of rollers and a plurality of pump tubes, one tube for advancing the sample, one or more tubes for advancing one or more reagents respectively, and a tube for advancing a diiferent, immiscible therewith fluid, such as a gas, the outlets of said tubes being connected to a junction means, and means to admit a volume of the gas from its tube to said junction means in synchronism with the Withdrawal and disengagement of each roller from all of said tubes. The uniformly periodic gas segment serves to provide identical liquid segments of sample plus reagents. While such liquid segments initially may not be of uniform proportion throughout the length thereof, subsequent mixing is provided to homogenize each such liquid segment. This results in successive liquid segments, each having uniform proportions throughout their respective lengths, and each such segment being identical to the others in such proportions.

SUMMARY OF THE INVENTION It is an object of this invention to provide an improved peristaltic pump having an auxiliary means for occluding the gas tube and timing the release of gas therefrom, wherein provision is made for the release from compression of all of the tubes, including the release of compression of the gas-supply tube by said auxiliary means, when the pump is not in use, thereby precluding the development of a permanent set in any of these tubes. Another object is the provision of means for easily adjusting the phasing between the release of the tubes by the leading roller and the admission of the gas segment to the junction means to segmentize the flowing stream of sample plus reagent. I

In accordance with the present invention the gas supplying tube is normally occluded between an anvil and a cross-pin, the cross-pin being withdrawn from the tube periodically in phase with the withdrawal of the leading roller from the sample and reagent supplying tubes. When the pump is deactuated, means are provided to Withdraw the anvil from the gas supplying tube. Further, a cam is provided, which is adjustably coupled to the drive means for the rollers, to periodically actuate the release of the cross-pin from the gas-supply tube.

BRIEF DESCRIPTION OF THE DRAWING There and other objects, features and advantages of the present invention will be apparent from the following description considered in conjunction with the accompanying drawing, in which:

FIG. 1 is a top view in plan of a peristaltic proportioning pump embodying this invention;

FIG. 2 is a side view in elevation, taken along plane 2-2 of FIG. 1; and

FIG. 3 is a detail, broken away, in perspective, showing the gas supply tube valving assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENT As seen in the drawing, the embodiment of the invention is incorporated into a peristaltic type pump of the type shown in U.S. Patent No. 3,227,091.

Briefly, the pump includes an outer housing 10, within which there are fixed two support plates 12, and to which there is fixed a motor 14 with an output shaft 16. A fan blade 18 is fixed to one end of the shaft 16, and a drive gear 20 is fixed to the other end.

Two inner side walls are fixed within the housing and a cross shaft 32 is journaled between and through these inner side walls. External to one side wall, a driven gear 34 is fixed to the shaft 32 and is meshed with the drive gear 20. Within the side walls, two spaced apart sprocket wheels 36 are fixed to the shaft 3 2. .Each sprocket wheel 36 meshed with a respective endless sprocket chain 38. A plurality of rollers 40 are journaled to and between the two chains and, during the upper run of the chains, pass over two spaced apart guide plates 42. The guide plates are fixed to a cross-bar 44 which is fixed between the side walls 30.

A cover assembly has two side walls 52, each of which has a hook portion 54 adapted to fit under and pivot about a respective horizontal stud 56. Each stud 56 is fixed to a respective sidewall of the main housing 10. A multi-piece resilient platen 59 is mounted within the cover assembly, and includes an upper part 60 which is secured to and between the side walls 52, and a lower part 62. These two parts have a plurality of mutually opposed cavities 64 into which are disposed a respective of compression springs 66. The lower part is mutually captured to the upper part by a plurality of machine screws 68. An aperture is formed in the top of the main housing 10, and the platen extends therethrough. A pair of grooved, spaced apart, pump tube locating blocks 72 are releasably mounted to the top of the housing adjacent to the aperture and a plurality of pump tubes 74 may be disposed between the two blocks over the aperture in side by side relation. When the cover assembly is swung down, to the position shown in FIG. 2, and locked in place by a lock assembly 78, the pump tubes are pressed downwardly by the lower face of the lower part 62 of the platen assembly against those rollers 40 which are riding on the upper edges of the guide plates 42, and the tubes are occluded by these rollers. When these rollers are advanced by the sprocket chains, they progressively occlude these tubes along their respective adjacent lengths, advancing such fluids as are contained therein. It will be noted that at least two rollers are always in occluding engagement with the tubes.

When the pumping operation is discontinued, either to replace pump tubes or otherwise, the lock assembly 78 is released, and the cover assembly is pivoted upwardly about the studs 56, thereby removing the platen from the pump tubes and releasing them from compression by the rollers.

As shown in U.S. Patent No. 3,306,229, it is desirable to limit the flow of the segmentizing gas from one or more of the pump tubes into the sample conduit to intervals of uniform duration which occur regularly, periodically, between those occasions when the rollers 40 are leaving the pump tubes. This is accomplished by closing the downstream end of such gas advancing pump tubes, except when a volume of gas is to be introduced into the sample conduit. Specifically those gas advancing pump tubes are normally pinched closed, except when the gas volume is to be released. It is also desirable that this pinching be released when the pumping operation is discontinued.

As is most conveniently seen in the perspective view of FIG. 3, a cam ring 80 is adjustably secured to the gear 34, which gear is secured to the sprocket cross shaft 32. The cam is provided with a plurality of interrupted annular slots 82 through which the shanks of respective clamping screws 84 pass into threaded bores on the gear 34. The cam ring 80 has a plurality of rises 86 regularly disposed along its peripheral camming surface 88. Depending on the tooth ratios of the gears 20, 34, the sprocket wheels 36 and the chains 38, there is one rise 86 for each roller 40.

A gas tube block assembly is disposed on the top of the main housing 10. This assembly 100 includes a U-shaped block support 102 having two spaced apart, upstanding legs 104. The support 102 is fixed to the main housing 10 by a plurality of machine screws 106. A shaft 108 is journaled between and through these legs 104. A gas tube block support 110 is pivotally journaled on the shaft 108. This support includes a horizontal plate portion 112, having two spaced apart pluralities of upstanding spaced apart teeth 114, each plurality of which provide tube receiving grooves therebetween. Forwardly of these teeth, the plate has two spaced apart arms 116 which terminate in two upstanding ears 118, through which passes the shaft 108. A resilient pad 120 is adhered to the plate between the two pluralities of teeth. Rearwardly, the plate 112 has an inverted-L-shaped portion 122, whose toe 124, rests on and is raised by the end of the hook portion 54 of the cover assembly, when the pump is in the pumping posture. When the pump is in the nonpumping posture, the end of the hook is pivoted away from the toe of the portion 122 and the plate pivots downwardly, about the shaft 108, until it is halted by the main housing. A pressing pin unit 126 is fixed to the shaft 108. This unit includes a pressing pin portion 128 which has two spaced apart arms 130 whose distal ends are fixed to the shaft 108. A pressing pin actuator arm 134 is fixed at one end thereof to one end of the shaft 108. This arm has a stud 136 intermediate its length to which is secured one end of a tension spring 138. The other end of the spring is secured to a stud 140 fixed to a bracket 142 which is mounted by a plurality of machine screws 144 to the side wall 30.

A cam follower assembly 146 includes a cam link unit having a cylindrical body 148, an arm 150 extending from one end thereof and an arm 152 extending from the other end thereof. An adjustable cam link assembly 154 is adjustably fixed to the arm 152. This assembly includes an arm 156 having elongated bores therein, through which pass a plurality of machine screws 158 into threaded bores on the arm 152, and an arm 160 which has a cam follower roller 162 journaled to its distal end. A camming roller 164 is journaled to the distal end of the arm 150. A bearing, not shown, is disposed through the body portion 148 and the junction of the arm 156 and 150, and a machine screw 166 passes through this bearing to pivotally mount the assemblies 146 and 154 through a pad 168 and the sidewall 30 to a support plate 167. The plate 167 is fixed to the main housing by a plurality of machine screws 170 and 106.

The roller 162 rides on the peripheral surfaces 88 of the cam 80, while the roller 164 is spaced slightly from the lower edge of the arm 134. The angle included between these two rollers with respect to the axis of rotation through the machine screw 166 may be finely adjusted by means of the elongated slots and the machine screws 158, and will control the length of the interval that each cam rise 86 will cause the pin 128 to clear the pump tubes.

The tension spring 138 maintains the arm 134 downwardly with a corresponding downward bias of the pressure pin 128, occluding any pump tube, such as 74A, which may be disposed through the grooves between the teeth 114, and the resilient pressure pad 120. When the cover assembly 50 is raised, the hook 54 releases the portion 124, the plate 112 drops downwardly, with the resilient pressure pad 120, to release these tubes from contact with the pressure pin 128. Thus, the compression of these pump tubes 74A during an interval of non-pumping is avoided, and such permanent deformation of those tubes as might be caused by such compression is precluded.

It will be appreciated that, as previously mentioned, the fine adjustment of the arms 156 and 158 permits adjusting the length of the air bubble. The ramp on the cam rise 86 forces the roller 162 to work against the spring 138. The adjustment can be such that the roller 164 engages the arm 134 when the roller is at the bottom of the ramp for a long air bubble, or at the top of the ramp for a short air bubble.

While a preferred embodiment of this invention has been shown and described, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that changes in the form and arrangement of the parts and in the specific manner of practicing the invention may be made Without departing from the underlying principles of the invention within the scope of the appended claims.

What is claimed is:

1. A peristaltic type pump comprising:

a plurality of pump tubes; releasable means for causing said tubes to pump including a platen and a plurality of rollers, each roller operable in sequence to concurrently engage said tubes against said platen, to progressively occlude said tubes against said platen along their lengths, and to release said tubes; and

an additional assembly including occluding means for normally occluding at least one of said pump tubes downstream of said platen and said rollers, and adjustable means coupled to said means for causing said tubes to pump, for causing said occluding means to release said normally occluded pump tube periodically, once between the occasions of successive ones of said rollers releasing said pump tubes, and intermediate means coupled to said means for causing said tubes to pump and to said occluding means for causing said occluding means to release said normally occluded pump tube in response to said means for causing said tubes to pump being released from said tubes.

2. A pump according to claim 1 wherein said occluding means-includes a pressing pin and a pad for compressing said one tube therebetween, and said intermediate means serves to space said pin and said pad apart to release said tube in response to said platen being spaced from said rollers to release said tubes.

3. A pump according to claim 2 wherein said means for causing said tubes to pump includes:

a motor coupled to and driving a shaft on which are fixed two sprocket wheels, which engage and drive two spaced apart endless sprocket chains, which carry therebetween said rollers;

said adjustable means includes a cam coupled to said shaft and a linkage operated by said cam coupled to said occluding means for spacing said pin from said pad, said cam being adjustable in phase angle to said shaft.

References Cited UNITED STATES PATENTS 2,935,028 5/1960 Ferrari et a1 l03-149 3,227,091 1/1966 Isreeli et al. 103149 3,306,229 2/1967 Smythe 103-149 WILBUR I. GOODLIN, Prim'ary Examiner.

DONLEY J. STOCKING, Assistant Examiner.

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