US3464359A - Apparatus for moving fluid from one system to a second system - Google Patents

Description

Sept. 2, 1969 c. L. KING ETAL 3,464,359

APPARATUS FOR MOVING FLUID FROM ONE SYSTEM TO A SECOND SYSTEM Filed Nov. 13, 1967 3 Sheets-Sheet l Inventors Charles L King, John A.Joh.nson

Sept. 2, 1969 C. L. KING ETAL 3,464,359

APPARATUS FOR MOVING FLUID FROM ONE SYSTEM TO A SECOND SYSTEM Filed NOV. 13, 1967 5 Sheets-Sheet 2 r 1 Mi r |\\\\\\;r\\\\ 1 i M" 55% -44 4/lmlili 1 x-nl fiWI W Inventors harles L. Ki

l\\ \n \g John A.John.5on

Sept. 2, 1969 c KlNG ET AL 3,464,359

APPARATUS FOR MOVING FLUID FROM ONE SYSTEM TO A SECOND SYSTEM VII/II loo Inventor s Charles IHKm John A.Johnso United States Fatent APPARATUS FOR MOVING FLUID FROM ONE SYSTEM TO A SECOND SYSTEM Charles Lee King, Addison, and John A. Johnson, Evanston, Ill., assignors to The Medimeter Corporation, a corporation of Illinois Filed Nov. 13, 1967, Ser. No. 682,474

Int. Cl. F04b 49/00, 3/00 US. Cl. 10338 16 Claims ABSTRACT OF THE DISCLOSURE A fluid pump for moving fluid from one system to another under pressure having means to assert positive, precise control over the flow rate and to isolate the outlet of the pump from small quantities of air occurring therein, the pump including control means to shuttle the inlet and outlet pistons in regulated manner.

Disclosure The present invention is directed to the provision of an improved fluid pump and, more particularly, is directed to a pump adapted for transferring fluid from one system to another at a positively controlled flow rate while isolating the outlet from small quantities of air that may occur in the system.

Background of invention Fluid transfer devices, of course, are generally well known and exist in many different forms. It should be observed, however, that a satisfactory fluid pump has not been developed for control of the pumping and flow rate when transferring intravenous solutions, including blood from a reservoir, or bag, to the body. The system com monly used for this purpose is the gravity feed system where a bag is supported above the level of the body to which it is being introduced and where the flow rate is controlled by the gross pressure of a clamp upon the flexible tube extending between the bag and the body. It can readily be seen that the flow rate of fluid through the tube will be a function of the amount of constriction of the tube.

Control of flow rates in the manner defined above is diflicult at best and not amenable to precise regulation or quick, controlled change in flow rates.

It should be noted that a simple pump action would not be generally suitable for transferring blood, for example, since close control of flow rate may be desired and because of the critical requirement to avoid the transfer or introduction of air during the fluid transfer action. It can readily be seen that the introduction of air could result in an embolism.

The present invention is directed to the provision of a fluid pump suitable for the transfer of intravenous solutions, including blood, which will provide positive, controlled pumping and flow rate and which isolates the outlet from air which may occur in the system.

It is, accordingly, a general object of the present invention to provide an apparatus for the transfer under pressure of fluid from one system to another.

Another object of the present invention resides in the provision of an improved fluid transfer apparatus having positive, controlled pumping action.

A further object of the present invention resides in the provision of an improved fluid transfer apparatus having means to vary the flow rate in a controlled manner.

An additional object of the present invention resides in the provision of an improved fluid pump for transferring intravenous fluids from one system to another.

Another object of the present invention resides in the provision of an improved fluid pump for transferring intravenous fluids from one system to another with means to isolate the outlet from any quantity of air that may occur in the system.

A further object of the present invention resides in the provision of an improved fluid transfer apparatus that is comprised of relatively few elements, that is economical to manufacture, easy and economical to use, provides positive control of fluid transfer and has means to vary flow rates.

The invention itself is set forth with particularity in the appended claims. Further objects and advantages of the invention, however, will be understood from reading the following description of the invention in conjunction with the drawings, in which:

FIGURE 1 is a perspective view of the apparatus of the present invention illustrating the control means and pump, in combination, and schematically showing transfer of fluid from a bag to a body;

FIGURE 2 is a side elevation, partly in section, of the apparatus of the present invention showing the details of the control means, its functional elements and its relation to the pump of the apparatus;

FIGURE 3 is a top plan view of the control means of FIGURE 1 illustrating the control means in one extreme operative position;

FIGURE 4 is a top plan view of the control means, like FIGURE 3, with the control means shown in the other extreme operative position;

FIGURE 4A is a fragmentary sectional view of the apparatus of FIGURE I particularly illustrating the cam means utilized to control movement of the shuttle;

FIGURE 5 is a side view, partly in section, of the pump of the present invention illustrating the inlet piston in sealing relating to the inlet port and the outlet piston in fluid discharge relation to the outlet port;

FIGURE 6 is a side view of the pump, like FIGURE 5, showing the pump with the pistons in position to permit entry of fluid to the central chamber of the pump;

FIGURE 7 is a view of the pump, like FIGURE 5, showing the pump in the stage of operation sequentially following that illustrated in FIGURE 6 and showing the inlet and outlet ports both in sealed relation; and

FIGURE 8 is a view of the pump, like FIGURE 5, illustrating the fluid discharge position and the stage of operation sequentially following that illustrated in FIG- URE 7.

Referring more particularly now to the drawings, the apparatus is indicated generally at 10 and includes the control means 12 andpump 14. The apparatus of the present invention will specifically be described as an apparatus for transferring intravenous solutions, including blood (whole or plasma), from a reservoir to the body. It should benoted, however, that the fluid transfer apparatus of the present invention may be employed to transfer fluid from one system to another system generally without restriction to the character of the fluid. It has its more useful aspects in the transfer of intravenous solutions and blood, however, and is particularly suited for this purpose.

A blood reservoir, or bag, 16 is shown in FIGURE 1 and is supported by aconventional hanger stand 18. Asuitable fluid conduit 20 extends from thereservoir 16 to theinlet 22. Asecond conduit 24 extends from thepump outlet 26 to thebody 28 where it may intravenously be introduced by means well known in the art.

The control means 12 of the apparatus of the present invention is encased in a suitable housing. A powersupply control switch 30 may be provided on the housing to control the on-off condition of the apparatus. Theswitch 30 is disposed within the line (not shown) leading to the power supply ormotor 32 and is adapted for interruption of the continuous circuit otherwise defined between themotor 32 and a 60 cycle 115420 volt supply line (not shown).

Theoutput shaft 34 of themotor 32 moves at a relatively high angular velocity which may be about 1700 r.p.m.s. This is much to high to be within the useful range for the present apparatus. Accordingly, theoutput shaft 34 defines the input to a suitable speed reduction means 36. The output of the speed reduction means 36 is defined at theshaft 38 and will be a fraction of the input velocity.

Acam plate 40 is non-rotatably secured to theshaft 38. Acam follower 42 is secured to theplate 40 in a radially outboard position thereon to define a circular path of motion when driven in operation of the apparatus disclosed herein.

Support bars 44 and 46 are mounted in the housing of the control means 12. As shown in FIGURES 3 and 4, the ends of said bars are supported by the end Walls of the housing for the control means 12. These bars define guide and support members for the reciprocating elements of the control means, as defined hereinbclow.

Ashuttle member 48 is mounted on thebars 44 and 46 for sliding movement in either direction along said bars. Theshuttle 48 is defined by abase section 50 terminating at either end inupstanding leg sections 52 and 54, respectively.Suitable openings 56 are provided in thelegs 52 and 54, in axially aligned relation, to receive thebars 44 and 46.

Thebase section 50 of theshuttle 48 is provided with a block orprojection 58 on the upper surface thereof and near theleg 52 of the shuttle. Anopening 60 is defined in thebase 50 near theleg 54 of said shuttle. Aprojection 62, carried by the housing of the control means 12, extends through theopening 60, the function of said projection being set forth in detail hereinbclow.

The bottom surface of theshuttle 48 is provided with acam track 64 which extends in a generally straight path, normal to the longitudinal axis of the shuttle and in Which thecam follower 42 is guided. It should be observed that the cam assembly may assume any suitable configuration, other than disclosed, to satisfy the motion requirement of the apparatus. It can readily be seen that as thecam plate 40 rotates thecam follower 42 will move in a generally circular path with the plate. The path defined by thecam follower 42 will be translated into a linear reciprocatory motion of theshuttle 48 by reason of thefollower 42 riding in thecam track 64 during its movement. The path length of thecam track 64, of course, is necessary to accommodate the lateral vector movement of thefollower 42 as it moves in its circular path. The vector quantity of the follower movement which lies in direction parallel to the longitudinal axis of theshuttle 48 will cause theshuttle 48 to move in a reciprocatory motion along thebars 44 and 46.

A firstpiston engaging means 66 is mounted on thebars 44 and 46 for sliding action therealong in response to movement of the shuttle, as indicated hereinbclow. A secondpiston engaging means 68 is mounted on thebars 44 and 46 adjacent the other end of theshuttle 48 and is disposed on said bars for sliding motion therealong in response to movement to theshuttle 48.

Each of the piston engaging means (66 and 68) of the present apparatus is defined by spaced apartarms 70 having openings extending therethrough to receive thebars 44 and 46, respectively. Thearms 70 of themeans 66 are joined to an upstanding trunnion-like element 72 on the firstpiston engaging means 66. Thearms 70 of themeans 68 are joined to an upstanding trunnion-like element 74 of the secondpiston engaging means 68. The trunnion-like elements 72 and 74 of the apparatus each are open at the top and include spaced apart arms that may be sprung apart slightly to receive a mating portion of the piston associated therewith to grasp the pistons 4 and move them in conjunction with movement of themeans 66 and 68, respectively.

A control element, indicated generally at 76, is provided to define means for varying the flow rate of the apparatus and for control thereof during operation of the apparatus. Thecontrol element 76 includes afirst link 78 pivotally mounted at one end thereof to thebase 50 of theshuttle 48 by thepin 80. Thelink 78 is pivotally joined at the other end to asecond link 82 by thepin 84 to define a toggle-like linkage for thecontrol member 76.

Thelink 82 is in the general shape of a crank-arm having the first leg pivotally joined to thelink 78, a noted hereinabove, and having a second leg extending substantially at right angles to the first leg to define acontrol bar stop 86. Thesecond link 82 is pivotally mounted to the secondpiston engaging element 68 at the point where the first and second legs of the link are joined. Accordingly, thelink 76 then is pivoted at three positions:

(1) At the outboard end of thelink 78; (2) At the common ends of thelink 78 andlink 82; and (3) At the joint of the first and second legs of thelink 82.

Arate adjustment member 89 threadably extends through a wall of the housing for the control means 12. Themember 89 is defined by aprobe 90 and an adjustment knob 92' secured thereto. A threadedsection 94 is interposed between the knob 92' and theprobe 90 and threadably engages a mating threaded portion in the wall of the housing (FIGURES 3 and 4). The flow rate may be adjusted by moving theknob 92 clockwise or counterclockwise to move theprobe 90 into or out of the housing of the control means 12. The specific control function will-be set forth in detail hereinbclow.

Thecontrol element 76 is shown in one position in FIGURE 3 with thelinks 78 and 82 in aligned relation and in a second position (FIGURE 4) with an included angle between said links. It can readily be seen that the control element positions of FIGURES 3 and 4 represent the extreme operative positions of the apparatus. Theshuttle 48 is in the extreme left position in FIGURE 3 and in the extreme right position in FIGURE 4.

Thelink 76 is urged into the straightened position of FIGURE 3 by theprojection 62 which moves into contact with thebar stop 86 when theshuttle 48 moves to the left (FIGURE 3) bringing thestop 86 against theprojection 62. Thebar stop 86 includes aslight shoulder 88 at the free end thereof which moves against amating shoulder 91 on the piston engaging means 68 to prevent movement of thelink 76 to an over-center position and to assure pivoting in the direction shown in FIGURE 4. It is possible that without this stop thelink 76 might lock or freeze and inhibit movement of theshuttle 48 and related mechanism thereby giving rise to a condition which could result in damage to the apparatus.

As shown in FIGURE 2, the pump means 14 is provided with twopistons 92 and 94. Thefirst piston 92 is disposed in operative relation to theinlet 22 of the pump and is retained in thepiston engaging means 66 of the apparatus. Thesecond piston 94 is disposed in operative relation to theoutlet 26 of the pump and is operatively associated with thepiston engaging means 68 of the apparatus.

Thepump 14 of the present invention is shown in greater detail in FIGURES 5 to 8, inclusive, of the drawings. Thepump 14 includes apump body 96 having aninlet 22 and anoutlet 26 interconnected by apump chamber 98. Thepump chamber 98 is the central bore of thebody 96 and extends continuously along the body to define the fluid conveying chamber and means for insertion and operation of thepistons 92 and 94 of the apparatus.

Apositioning lug 100 is provided on thebody 96 to orient the body 'with respect to its associated apparatus. It should be noted that any suitable means of orientation may be employed. This particular use of the lug is only one means of many that would satisfy this requirement. Thelug 100 may be received in a mating opening in the housing of theapparatus 12 to position thepump 14 properly with respect to the apparatus for engagement of the pistons of the pump and for operation of the pump by the control means set forth herein. The positioning lug also may be adapted to assure proper orientation of the pump with respect to the control. It also should be noted that the pump of the present invention may be operated by other suitable control means, if desired. It may be desirable in some conditions of use to operate the pistons in simultaneous shuttle movement Within the body rather than in sequential movement as disclosed herein. Such operation would require the use of a modified pump operating and control means different from that specifically disclosed herein which would provide the required action. Still other desired programmed operation may be achieved with other devices in combination with this pump which would not detract in any way from the use of the pump but which suggest the flexibility of operation of the pump disclosed herein apart from the control means specifically set forth by way of illustration of the apparatus.

Thepiston 92 is disposed in thecentral chamber 98 of thepump body 96 adjacent to theinlet end 22 thereof, as indicated in FIGURE 5 of the drawings. The bore of thechamber 98 is such as to receive thehead 102 of thepiston 92 in fluid sealing relation therein without additional sealing means being employed. It should be observed, however, separate sealing means may be used. For example, one may elect to use O-rings along the head of the piston. Another, and perhaps more suitable sealing means in pumping fluids would reside in the use of formed disposable jacket elements (not shown) which would be telescopically received over the piston heads and would seal between the piston head and the inner wall of thechamber 98. This would provide the required sealing action between the piston head and thecentral chamber 98 of thepump body 96. Additionally, it would provide the attractive advantage of being able to form the pistons from a different material than the sealing element. This may result in sustantial economy in the forming operation and, of course, in the expense of the apparatus. The sleeve may be molded of an inert, elastomeric material which would not react in any -way to the fluid being pumped and which would, at the same time, provide the necessary sealing action for the apparatus.

The outboard ends of thepistons 92 and 94 are provided "with a recessed portion as illustrated at 104 of thepiston 92. The recessedportion 104 of thepiston 92 is received in thetrunnion 72 of thepiston engaging means 66 of the apparatus. The recessedportion 104 of thepiston 94 is received in thetrunnion 74 of the piston engaging means 68 (see FIGURE 2). In this manner thepistons 92 and 94 are engaged by themeans 66 and 68, respectively, and are caused to move in accordance wlth the movement of themeans 66 and 68, as noted below.

Thepiston 94 is received in thechamber 98 of thepump body 96 adjacent to theoutlet 26 of thepump 14. Thepiston 94 includes apiston head 106 having anopening 108 therein extending from theinboard end 110 of thepiston 94 continuously through the piston head and to the wall of the piston to define a continuous fluid passage from thechamber 98 between the ends of thepistons 92 and 94 to the outlet opening 27 of theoutlet 26 when theopening 108 is in registration with theopening 27. A flange 112 may be provided at the chamber terminal of theopening 108 as illustrated in FIGURE 5 for a reason to be noted below.

The outside diameter of thepiston 94 may be substantially the same as the inside diameter of thechamber 98 so that a sealing relation between the piston head and the chamber will be defined in use. It should be observed, however, that an auxiliary seal forpiston 94 may be provided when the differential pressure across the piston head is significant which seal will be the same as noted above forpiston 92. The molded sleeve or piston head, however, would carry the opening or provide access for theopening 108 to permit fluid flow through thepiston head 106.

The operation of the pump may be understood by reference to FIGURES 6, 7 and 8 in conjunction with the description set forth below. The intake cycle of the pumping operation is illustrated in FIGURE 6. At this stage of operation the second, oroutlet piston 94, is fully inserted into thechamber 98 and is at its maximum path of travel inwardly of the chamber. At this point it remains stationary for a brief interval while the first, orinlet piston 92, is withdrawn past theinlet opening 23. As thepiston head 102 uncovers theopening 23 fluid begins to enter the chamber and continues to enter the chamber during opening movement of thepiston 92. The fluid reservoir is disposed above the level of the pump in most instances in our specific example and in this position a fluid pressure head will be established which will cause the fluid to flow from the reservoir to the pump chamber any time that a chamber volume is presented to it and theinlet opening 23 is opened to permit the passage of fluid into thechamber 98. The fluid is fed to thechamber 98 by a combination of gravity feed and pressure differential between the reservoir and expanding chamber volume.

When the desired amount of fluid has been introduced into thechamber 98 thepiston head 102 will, in sequence, move to the left (FIGURE 6) to cover the inlet opening 23 to seal it and thereby isolate thechamber 98 from thereservoir 16. This position is shown in FIGURE 7 where the desired amount of fluid has entered thechamber 98 and is trapped therein between thepiston head 102 of thefirst piston 92 and thehead 106 of thesecond piston 94. It can readily be seen that fluid cannot flow through theopening 108 to the outlet opening 27 during the intake (FIGURE 6) or transport (FIGURE 7) stages since the wall terminal of theopening 108 is still isolated from theopening 27. Accordingly, the fluid is trapped between theend 103 of thepiston head 102 and the end of thehead 106 with, of course, a small amount of fluid also being trapped within the full extent of theopening 108.

The discharge portion of the cycle is illustrated in FIG- URE 8 where theopening 108 is brought into registration with theoutlet 27 to permit flow of fluid from thechamber 98 into theoutlet 27. The fluid is discharged from thechamber 98 into the outlet by bringing theend 103 of thepiston 92 into close spaced relation to theend 110 of thepiston head 106. If the flange 112 is present then, of course, theend 103 is stopped prior to engagement of said end with the flange.

The cycle then is repeated with thepistons 92 and 94 being moved to the right (FIGURES 6, 7 and 8) to the position substantially as shown in FIGURE 6 of the drawings.

It can be seen that if any air is in the system it will naturally rise to the top of thechamber 98 and will not pass into theoutlet 27 since the top of thechamber 98 is isolated at all times from connection with theoutlet 27. In this way air in the system is prevented from entering the outlet system for possible discharge to the body where it could cause an embolism or air blockage. The pump of the present invention is adapted for use in any position while still maintaining the characteristic of preventing air flow to the outlet. This feature is readily seen with the pump in the position shown in FIGURES 6, 7 and 8, for example. If the pump were oriented such that thepiston 92 is at the top, then the air would rise against thehead 102 of thepiston 92 and would not enter theoutlet 27 during pumping operation. It should be noted that not all of the fluid is pumped from the chamber during each cycle. A small amount is left each time to prevent discharge of air to the outlet and to provide a simpler mode of operation. If thechamber 98 is completely filled with air, the outlet piston will not be forced to a position where theopening 108 will register with the outlet opening. Air is compressible, of course, and the inlet piston will only compress the air inchamber 98 without forcing thepiston 94 to expose the outlet opening.

If thepump 14 is oriented such that thepiston 94 is at the top, the flange 112 will be necessary. It can readily be seen that any air in the system will rise to the top and move against theend 110 of thepiston head 106. However, the flange extension 112 on theconduit 108 will define a fluid path to thechamber 98 which will be slightly immersed and which will be below the air entrapped within the chamber. In this manner air again will be prevented from entering theoutlet 27, as in each of the other cases noted above.

The operation of the control means of the present invention may best be understood by reference to FIG- URES 2-4A, inclusive, in conjunction with the following description of its operation.

The fluid intake position of the control means 12 when used in conjunction with the pump disclosed herein is shown in FIGURES 2 and 3 of the drawings. As indicated, the first piston engaging means is moved fully to the left by thepushblock 58 on shuttle 48 (the shuttle movement having been described above). Movement of themeans 66 to the left will, of course, carry the associatedpiston 92 along with it. As thepiston 92 moves to the left (FIGURES 2 and 3) it will eventually expose theintake opening 23 of theintake opening 22 and permit fluid to enter thechamber 98 from thereservoir 16 which is connected thereto by theconduit 20.

It can be seen that theupstanding leg 52 moves to the left beyond the back face of themeans 66 for a slight distance. Theleg 52, of course, does not carry themeans 66 to the left (FIGURE 2)themeans 66 is moved to the left by the push block orprojection 58. As theshuttle 48 moves to the left it eventually will engage the front face of themeans 66 and will cause the piston engaging means 66 to slide along thebars 44 and 46 in unison with the continued leftward movement of the projection 58 (the projection, of course, being rigidly secured to thebase 50 of. the shuttle). However, a lost motion is provided between the projection '58 and theupstanding leg 52 to permit filling of thechamber 98 during the intake operation of pump cycle. This lost motion is achieved by permitting the shuttle to begin its leftward movement and to continue it for a short distance before theprojection 58 engages themeans 66 to start movement of thepiston 92 leftward (FIGURE 2). At this time theupstanding leg 52 has moved a short distance toward the left and is in spaced relation to the back face of the firstpiston engaging means 66. Theleg 52 and means 66 remain in the spaced relation during continued movement of theshuttle 48 toward the left. Accordingly, when the leftward movement of the shuttle has been completed the space between the front face of theleg 52 and the back face of themeans 66 defines the time interval during which thepiston 92 will remain stationary during continued movement of theshuttle 48 in a reverse, or rightward, direction.

As the cam assembly continues in its operation to move theshuttle 48 the direction of movement will change from left to right, as noted above. At the extreme left position of the shuttle, thelink 76 will be in its straight position, as shown in FIGURES 2 and 3. Thestop 62 will be resting fully against the face of thecontrol bar stop 86.

Continued movement of theshuttle 48 to the right will bring theleg 52 into engagement (after a predetermined interval) with thepiston engaging means 66 and start thepiston 92 moving toward the right. Thepiston 92 then will move over theopening 23 to seal it and isolate it from thereservoir 16. As theshuttle 48 continues to move to the right pumping action eventually will occur moving the fluid from thechamber 98 to theoutlet 26 of thepump 14.

When thepump 14 is in the fluid intake position, theoutlet piston 94 will be positioned such that theoutlet opening 27 will be sealed and theopening 108 will be out of registration therewith, as illustrated in FIGURES 2 and 6. During the fluid intake sequence of operation, thepiston 92 will temporarily be stationary. However, thepiston 94 will move toward the right (as shown in FIG- URE 2) with theshuttle 48 to define a pump chamber opening 98 which is continually enlarging to permit introduction of a predetermined, measured quantity of fluid to thechamber 98. The amount of fluid drawn into the chamber on each stroke is regulated by the position of themember 89. When the probe engages thebar 86 continued shuttle directed movement of thepiston 94 is terminated.Piston 94 may only be moved now by the force of the fluid trapped between thepistons 92 and 94. Since the fluid is not compressible thepiston 94 will move in direct response to movement of thepiston 92 until theopening 108 registers with the outlet of the pump. Thepiston 94 stops at this position since further movement ofpiston 92 will only push the fluid from thechamber 98 through theopening 108 to the pump outlet.

Prior to the time that theopening 108 begins to fall into registration with theoutlet opening 27, thepiston head 102 will pass over the inlet opening 23 to seal it and to prevent an open fluid circuit between the reservoir and the outlet system. This position is illustrated at FIGURE 7 of the drawings and will be between the positions of FIGURE 3 and FIGURE 4 of the control means.

Theshuttle 48 continues movement toward the right (FIGURE 2) under action of the cam assembly, as noted above. Thelink 76 will remain in the straight condition shown in FIGURE 3 until thebar stop 86 engages theprobe 90 of therate adjustment member 89. One end of thelink 76 is pivotally secured to thebase 50 of theshuttle 48 while the other end of thelink 76 is pivotally secured to the secondpiston engaging means 68. Accordingly, movement of theshuttle 48 will result in a corresponding movement of themeans 68 as long as thelink 76 remains in the straight position of FIGURE 3. The link assumes the function of a pusher arm in this position.

When thebar stop 86 strikes the positionallyadjustable probe 90 of therate control member 89, the second link '82 and thefirst link 78 pivot about thepin 84 in accordion fashion. This action of thelink arm 76 permits continued movement of theshuttle 48 rightward (FIGURE 2) while stopping continued movement of thepiston engaging means 70 and therelated piston 94. As noted above, when this occurs thechamber 98 is full.

Thepiston 94 is stopped when in registration with the outlet opening 27 but while thepiston 92 is still moving to the right with theshuttle 48. Accordingly, the continued movement of thepiston 92 will serve to move substantially all of the fluid within thepump chamber 98 through theopening 108 of thepiston head 106 and into the outlet opening of the pump.

Theshuttle 48 completes its rightward movement as shown in FIGURE 4. Theleg 54 of theshuttle 48 is slightly to the right of the back face of themeans 68 and is about the same distance from means 68 as theprojection 58 is to themeans 66. As theshuttle 48 begins to move toward the left again under the action of the cam assembly (noted above) the front face of theleg 54 will engage themeans 68 to move thepiston 94 to a position where theopening 108 is out of registration with theoutlet opening 27 and a fluid seal is defined at the outlet. Theprojection 58 engages themeans 66 at the same time to cause it andpiston 92 to move left to later expose theinlet 23 and permit introduction of another supply of fluid to thechamber 98. The cycle noted above is repeated during the pumping operation.

Thelink 76 is straightened during continued movement of the shuttle to the right. It will be noted that as the assembly moves toward the right theshuttle 48 will pull thelink 76 to a partially straight condition with a large included angle (but less than 180) between the first and second links of theassembly 76. The link is finally brought to a straight condition by movement of thebar stop 86 against theprojection 62. Theprojection 62 forces thebar stop 86 against theshoulder 91 to force theelements 78 and 82 into mutually aligned relation ready for the next pumping cycle.

It should be noted that therate adjustment member 89 may be moved toward or away from the center of the control means to vary pump chamber volume during the pumping operation. If theadjustment member 89 is moved inwardly the chamber volume will be smaller and the rate of transfer of fluid will be less per unit of time, or per stroke of the pump apparatus.

It also should be observed that when the pump apparatus of the present invention is used for introducing intravenous solutions a safety feature may be employed which will automatically interrupt flow of solution continuously through the outlet when the needle (or other device) is displaced from the vein. This is accomplished in the present apparataus by providing a slip fit between theoutlet tubing 24 and theoutlet projection 26 of the apparatus. If the needle of the outlet should become displaced from the vein, for example, and enter the muscular tissue, or other tissue surrounding the vein, it is important to stop the flow of solution to that area to avoid pumping of solution into the tissue thereby giving rise to a condition which may result in damage. The slip fit between thetubing 24 and theoutlet projection 26 is designed such that it will blow off upon a predetermined resistance to flow through thetubing 24. According- 1y, if the needle becomes displaced, the soltuion will very likely not flow freely and a pressure build up will occur in thetubing 24. When this pressure reaches a predetermined level (set at whatever safety level is necessary for the use) thetubing 24 will slip off of theprojection 26 and the solution thereafter will merely continue to flow over theprojection 26 onto the apparatus rather than into the tissue.

While we have shown and described a specific embodiment of the present invention it will, of course, be understood that other modifications and alternative constructions may be used without departing from the true spirit and scope of this invention.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. An apparatus for moving fluid from one system to a second system at a controlled regulatable flow rate, said apparatus comprising, in combination:

control means having a power supply associated therewith and regulating means thereon to define means to vary the output action of the control means; and

a pump operatively associated with said control means and responsive to the output action of said control means to provide for varying fluid flow rates, the pump including a central chamber having an inlet and outlet port and pistons associated with each said port, means associated with the outlet port piston to provide for independent interruption of outlet port piston movement while the outlet port is closed to said central chamber, said pistons each being moveable within the central chamber between its respective part open and part closed position to move fluid from one system through the inlet port and central pump chamber to the outlet port and the second system.

2. The apparatus of claim 1 wherein the control means includes first and second piston engaging members each of which reciprocates independently of the other, the first piston being operatively engaged to said first piston engaging member and the second piston being operatively engaged to said second piston engaging member.

3. The apparatus of claim 2 wherein said piston engaging members are moved by a common shuttle member connected to the power supply.

4. The apparatus of claim 3 wherein the shuttle is moved in shuttle-reciprocating action by a cam connected to the output of the power supply, said cam having a cam follower thereon operatively engaging a cam track in said shuttle.

5. The apparatus of claim 4 wherein means operatively associated with the second piston engaging member is provided to allow for varying the amount of fluid moved from inlet port to outlet port per piston cycle.

6. The apparatus of claim 1 wherein the regulating means is defined by stop means to define maximum piston movement of the piston associated with the inlet port of the pump.

7. The apparatus of claim 1 wherein the piston associated with the outlet port of the pump is provided with a continuous opening extending from the central axis of the piston on the end thereof internally of the piston to the outer wall thereof to define a fluid flow path from the central pump chamber through said continuous opening to the outlet port of the pump when the opening in the outer wall of the piston is in registration with the outlet port.

8. An apparatus for use in defining a shuttle action for moving a member in reciprocatory fashion, comprising:

a housing;

power supply means in said housing and having an outlet;

a shuttle member operatively associated with said power supply means and adapted to move in a predetermined reciprocatory motion in response to operation of the power supply means;

first member engaging means associated with said shuttle member and moveable in reciprocatory motion in response to movement of the shuttle;

second member engaging means associated with said shuttle member and moveable in reciprocatory motion in response to movement of the shuttle; and

a link joint secured at one end to the shuttle and at the other end to the second member engaging means, said link joint being collapsable to prevent movement of the second member engaging means in response to movement of the shuttle when it is desired to prevent such movement.

9. The apparatus of claim 8 wherein the power supply means is provided with a speed reducing means to provide the proper outlet motion for use by the shuttle of the apparatus.

10. The apparatus of claim 8' wherein the power supply means and shuttle, in combination, define cam means for reciprocatory movement of the shuttle in the path of movement thereof in the apparatus.

11. The apparatus of claim 8 wherein the shuttle is provided with spaced apart projections, one of said projections engaging the first member engaging means for movement thereof in one direction of shuttle movement and the other of said projections engaging the first member engaging means for movement thereof in the other shuttle direction.

12. A pump apparatus for use in transferring fluid from one system to another, comprising:

a pump body having a central chamber and inlet and outlet openings communicating therewith;

a first member disposed in said pump body for movement axially of the chamber and adapted in one position to seal the inlet of the pump to isolate the pump chamber from the inlet fluid system and in a second position to open the inlet of the pump to permit fluid to move from the inlet system to the pump chamber;

a second member disposed in said pump body for movement axially of the chamber and being in axially spaced relation to said first member in said chamber, said second member having an opening in the body thereof extending continuously from the chamber end to the wall thereof, said second member adapted in a first position to seal the outlet of the pump to isolate the pump chamber from the outlet fluid stream and in a second position to open the inlet of the pump to permit fluid to flow from the chamber to the outlet fluid system; means to move the first and second members between their first and second positions, respectively; and

means to prevent movement of said second member from first to second position when a compressible fluid is contained in said central chamber.

13. The pump ofclaim 12 wherein said means to prevent movement of said second member includes a collapsible hinged member associated with said second member which may be collapsed to allow compression of fiuid in the central chamber Without movement of the second member to its said second position.

14. The pump ofclaim 12 wherein the means is directly associated with the first member to engage it for movement to and between said first and second positions.

15. The pump ofclaim 12 wherein the second member is moved to said first position in direct response to movement of said means but is disengaged from said means prior to movement to said second position.

References Cited UNITED STATES PATENTS 722,431 3/1903 Packard 103-166 1,274,884 8/1918 Hudson 103166 2,833,226 5/1958 De Meux 103166 3,083,648 4/ 1963 Putrnan 103203 3,285,182 11/ 1966 Pinkerton 103203 3,302,528 2/1967 Anderson 103-166 WILLIAM L. FREEH, Primary Examiner US. Cl. X.R. 103-166

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