US3464359A

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

Info

Publication number: US3464359A
Application number: US682474A
Authority: US
Inventors: Charles Lee King; John A Johnson
Original assignee: Medimeter Corp
Current assignee: Medimeter Corp
Priority date: 1967-11-13
Filing date: 1967-11-13
Publication date: 1969-09-02
Anticipated expiration: 1986-09-02

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 and pump 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 a conventional hanger stand 18. A suitable fluid conduit 20 extends from the reservoir 16 to the inlet 22. A second conduit 24 extends from the pump outlet 26 to the body 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 power supply control switch 30 may be provided on the housing to control the on-off condition of the apparatus. The switch 30 is disposed within the line (not shown) leading to the power supply or motor 32 and is adapted for interruption of the continuous circuit otherwise defined between the motor 32 and a 60 cycle 115420 volt supply line (not shown).

The output shaft 34 of the motor 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, the output shaft 34 defines the input to a suitable speed reduction means 36. The output of the speed reduction means 36 is defined at the shaft 38 and will be a fraction of the input velocity.

A cam plate 40 is non-rotatably secured to the shaft 38. A cam follower 42 is secured to the plate 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.

A shuttle member 48 is mounted on the

bars

44 and 46 for sliding movement in either direction along said bars. The shuttle 48 is defined by a base section 50 terminating at either end in

upstanding leg sections

52 and 54, respectively. Suitable openings 56 are provided in the

legs

52 and 54, in axially aligned relation, to receive the

bars

44 and 46.

The base section 50 of the shuttle 48 is provided with a block or projection 58 on the upper surface thereof and near the leg 52 of the shuttle. An opening 60 is defined in the base 50 near the leg 54 of said shuttle. A projection 62, carried by the housing of the control means 12, extends through the opening 60, the function of said projection being set forth in detail hereinbclow.

The bottom surface of the shuttle 48 is provided with a cam track 64 which extends in a generally straight path, normal to the longitudinal axis of the shuttle and in Which the cam 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 the cam plate 40 rotates the cam follower 42 will move in a generally circular path with the plate. The path defined by the cam follower 42 will be translated into a linear reciprocatory motion of the shuttle 48 by reason of the follower 42 riding in the cam track 64 during its movement. The path length of the cam track 64, of course, is necessary to accommodate the lateral vector movement of the follower 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 the shuttle 48 will cause the shuttle 48 to move in a reciprocatory motion along the

bars

44 and 46.

A first piston engaging means 66 is mounted on the

bars

44 and 46 for sliding action therealong in response to movement of the shuttle, as indicated hereinbclow. A second piston engaging means 68 is mounted on the

bars

44 and 46 adjacent the other end of the shuttle 48 and is disposed on said bars for sliding motion therealong in response to movement to the shuttle 48.

Each of the piston engaging means (66 and 68) of the present apparatus is defined by spaced apart arms 70 having openings extending therethrough to receive the

bars

44 and 46, respectively. The arms 70 of the means 66 are joined to an upstanding trunnion-like element 72 on the first piston engaging means 66. The arms 70 of the means 68 are joined to an upstanding trunnion-like element 74 of the second piston 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 the

means

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. The control element 76 includes a first link 78 pivotally mounted at one end thereof to the base 50 of the shuttle 48 by the pin 80. The link 78 is pivotally joined at the other end to a second link 82 by the pin 84 to define a toggle-like linkage for the control member 76.

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

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

A rate adjustment member 89 threadably extends through a wall of the housing for the control means 12. The member 89 is defined by a probe 90 and an adjustment knob 92' secured thereto. A threaded section 94 is interposed between the knob 92' and the probe 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 the knob 92 clockwise or counterclockwise to move the probe 90 into or out of the housing of the control means 12. The specific control function will-be set forth in detail hereinbclow.

The control element 76 is shown in one position in FIGURE 3 with the

links

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. The shuttle 48 is in the extreme left position in FIGURE 3 and in the extreme right position in FIGURE 4.

The link 76 is urged into the straightened position of FIGURE 3 by the projection 62 which moves into contact with the bar stop 86 when the shuttle 48 moves to the left (FIGURE 3) bringing the stop 86 against the projection 62. The bar stop 86 includes a slight shoulder 88 at the free end thereof which moves against a mating shoulder 91 on the piston engaging means 68 to prevent movement of the link 76 to an over-center position and to assure pivoting in the direction shown in FIGURE 4. It is possible that without this stop the link 76 might lock or freeze and inhibit movement of the shuttle 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 two

pistons

92 and 94. The first piston 92 is disposed in operative relation to the inlet 22 of the pump and is retained in the piston engaging means 66 of the apparatus. The second piston 94 is disposed in operative relation to the outlet 26 of the pump and is operatively associated with the piston engaging means 68 of the apparatus.

The pump 14 of the present invention is shown in greater detail in FIGURES 5 to 8, inclusive, of the drawings. The pump 14 includes a pump body 96 having an inlet 22 and an outlet 26 interconnected by a pump chamber 98. The pump chamber 98 is the central bore of the body 96 and extends continuously along the body to define the fluid conveying chamber and means for insertion and operation of the

pistons

92 and 94 of the apparatus.

A positioning lug 100 is provided on the body 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. The lug 100 may be received in a mating opening in the housing of the apparatus 12 to position the pump 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.

The piston 92 is disposed in the central chamber 98 of the pump body 96 adjacent to the inlet end 22 thereof, as indicated in FIGURE 5 of the drawings. The bore of the chamber 98 is such as to receive the head 102 of the piston 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 the chamber 98. This would provide the required sealing action between the piston head and the central chamber 98 of the pump 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 the

pistons

92 and 94 are provided "with a recessed portion as illustrated at 104 of the piston 92. The recessed portion 104 of the piston 92 is received in the trunnion 72 of the piston engaging means 66 of the apparatus. The recessed portion 104 of the piston 94 is received in the trunnion 74 of the piston engaging means 68 (see FIGURE 2). In this manner the

pistons

92 and 94 are engaged by the

means

66 and 68, respectively, and are caused to move in accordance wlth the movement of the

means

66 and 68, as noted below.

The piston 94 is received in the chamber 98 of the pump body 96 adjacent to the outlet 26 of the pump 14. The piston 94 includes a piston head 106 having an opening 108 therein extending from the inboard end 110 of the piston 94 continuously through the piston head and to the wall of the piston to define a continuous fluid passage from the chamber 98 between the ends of the

pistons

92 and 94 to the outlet opening 27 of the outlet 26 when the opening 108 is in registration with the opening 27. A flange 112 may be provided at the chamber terminal of the opening 108 as illustrated in FIGURE 5 for a reason to be noted below.

The outside diameter of the piston 94 may be substantially the same as the inside diameter of the chamber 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 for piston 94 may be provided when the differential pressure across the piston head is significant which seal will be the same as noted above for piston 92. The molded sleeve or piston head, however, would carry the opening or provide access for the opening 108 to permit fluid flow through the piston 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, or outlet piston 94, is fully inserted into the chamber 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, or inlet piston 92, is withdrawn past the inlet opening 23. As the piston head 102 uncovers the opening 23 fluid begins to enter the chamber and continues to enter the chamber during opening movement of the piston 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 the inlet opening 23 is opened to permit the passage of fluid into the chamber 98. The fluid is fed to the chamber 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 the chamber 98 the piston head 102 will, in sequence, move to the left (FIGURE 6) to cover the inlet opening 23 to seal it and thereby isolate the chamber 98 from the reservoir 16. This position is shown in FIGURE 7 where the desired amount of fluid has entered the chamber 98 and is trapped therein between the piston head 102 of the first piston 92 and the head 106 of the second piston 94. It can readily be seen that fluid cannot flow through the opening 108 to the outlet opening 27 during the intake (FIGURE 6) or transport (FIGURE 7) stages since the wall terminal of the opening 108 is still isolated from the opening 27. Accordingly, the fluid is trapped between the end 103 of the piston head 102 and the end of the head 106 with, of course, a small amount of fluid also being trapped within the full extent of the opening 108.

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

The cycle then is repeated with the

pistons

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 the chamber 98 and will not pass into the outlet 27 since the top of the chamber 98 is isolated at all times from connection with the outlet 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 the piston 92 is at the top, then the air would rise against the head 102 of the piston 92 and would not enter the outlet 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 the chamber 98 is completely filled with air, the outlet piston will not be forced to a position where the opening 108 will register with the outlet opening. Air is compressible, of course, and the inlet piston will only compress the air in chamber 98 without forcing the piston 94 to expose the outlet opening.

If the pump 14 is oriented such that the piston 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 the end 110 of the piston head 106. However, the flange extension 112 on the conduit 108 will define a fluid path to the chamber 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 the outlet 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 the pushblock 58 on shuttle 48 (the shuttle movement having been described above). Movement of the means 66 to the left will, of course, carry the associated piston 92 along with it. As the piston 92 moves to the left (FIGURES 2 and 3) it will eventually expose the intake opening 23 of the intake opening 22 and permit fluid to enter the chamber 98 from the reservoir 16 which is connected thereto by the conduit 20.

It can be seen that the upstanding leg 52 moves to the left beyond the back face of the means 66 for a slight distance. The leg 52, of course, does not carry the means 66 to the left (FIGURE 2)the means 66 is moved to the left by the push block or projection 58. As the shuttle 48 moves to the left it eventually will engage the front face of the means 66 and will cause the piston engaging means 66 to slide along the

bars

44 and 46 in unison with the continued leftward movement of the projection 58 (the projection, of course, being rigidly secured to the base 50 of. the shuttle). However, a lost motion is provided between the projection '58 and the upstanding leg 52 to permit filling of the chamber 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 the projection 58 engages the means 66 to start movement of the piston 92 leftward (FIGURE 2). At this time the upstanding leg 52 has moved a short distance toward the left and is in spaced relation to the back face of the first piston engaging means 66. The leg 52 and means 66 remain in the spaced relation during continued movement of the shuttle 48 toward the left. Accordingly, when the leftward movement of the shuttle has been completed the space between the front face of the leg 52 and the back face of the means 66 defines the time interval during which the piston 92 will remain stationary during continued movement of the shuttle 48 in a reverse, or rightward, direction.

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

Continued movement of the shuttle 48 to the right will bring the leg 52 into engagement (after a predetermined interval) with the piston engaging means 66 and start the piston 92 moving toward the right. The piston 92 then will move over the opening 23 to seal it and isolate it from the reservoir 16. As the shuttle 48 continues to move to the right pumping action eventually will occur moving the fluid from the chamber 98 to the outlet 26 of the pump 14.

When the pump 14 is in the fluid intake position, the outlet piston 94 will be positioned such that the outlet opening 27 will be sealed and the opening 108 will be out of registration therewith, as illustrated in FIGURES 2 and 6. During the fluid intake sequence of operation, the piston 92 will temporarily be stationary. However, the piston 94 will move toward the right (as shown in FIG- URE 2) with the shuttle 48 to define a pump chamber opening 98 which is continually enlarging to permit introduction of a predetermined, measured quantity of fluid to the chamber 98. The amount of fluid drawn into the chamber on each stroke is regulated by the position of the member 89. When the probe engages the bar 86 continued shuttle directed movement of the piston 94 is terminated. Piston 94 may only be moved now by the force of the fluid trapped between the

pistons

92 and 94. Since the fluid is not compressible the piston 94 will move in direct response to movement of the piston 92 until the opening 108 registers with the outlet of the pump. The piston 94 stops at this position since further movement of piston 92 will only push the fluid from the chamber 98 through the opening 108 to the pump outlet.

Prior to the time that the opening 108 begins to fall into registration with the outlet opening 27, the piston 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.

The shuttle 48 continues movement toward the right (FIGURE 2) under action of the cam assembly, as noted above. The link 76 will remain in the straight condition shown in FIGURE 3 until the bar stop 86 engages the probe 90 of the rate adjustment member 89. One end of the link 76 is pivotally secured to the base 50 of the shuttle 48 while the other end of the link 76 is pivotally secured to the second piston engaging means 68. Accordingly, movement of the shuttle 48 will result in a corresponding movement of the means 68 as long as the link 76 remains in the straight position of FIGURE 3. The link assumes the function of a pusher arm in this position.

When the bar stop 86 strikes the positionally adjustable probe 90 of the rate control member 89, the second link '82 and the first link 78 pivot about the pin 84 in accordion fashion. This action of the link arm 76 permits continued movement of the shuttle 48 rightward (FIGURE 2) while stopping continued movement of the piston engaging means 70 and the related piston 94. As noted above, when this occurs the chamber 98 is full.

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

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

The link 76 is straightened during continued movement of the shuttle to the right. It will be noted that as the assembly moves toward the right the shuttle 48 will pull the link 76 to a partially straight condition with a large included angle (but less than 180) between the first and second links of the assembly 76. The link is finally brought to a straight condition by movement of the bar stop 86 against the projection 62. The projection 62 forces the bar stop 86 against the shoulder 91 to force the

elements

78 and 82 into mutually aligned relation ready for the next pumping cycle.

It should be noted that the rate 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 the adjustment 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 the outlet tubing 24 and the outlet 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 the tubing 24 and the outlet projection 26 is designed such that it will blow off upon a predetermined resistance to flow through the tubing 24. According- 1y, if the needle becomes displaced, the soltuion will very likely not flow freely and a pressure build up will occur in the tubing 24. When this pressure reaches a predetermined level (set at whatever safety level is necessary for the use) the tubing 24 will slip off of the projection 26 and the solution thereafter will merely continue to flow over the projection 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 of claim 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 of claim 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 of claim 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