Title of Invention

A PORTABLE INFUSION PUMP

Abstract

The invention relates to an improved portable infusion Dump for administering fluid into a subject comprising an electric motor (1) having an output shaft coupled to a toothed belt pulley means (5); and intermediate drive means (6); a plurality of bevel gears (20,21); and an idle gear (9) for reduction of the rotational output of said output shaft (22) and for supply of power to a bevel gear differential (19); a screw differential means (24.25.28,29) for causing differential liner movement of its constituent members (24,25); a pusher plate (30) transmitting the linear movement of one of the constituent members of said speed screw differential means (24,25,28,29) to a plunger (31) of a coupleable transfusible means (32) for pumping fluid, and a switching circuit (2) for regulating the average speed of said motor (1). The speed-reduction means comprises an epicyclic gear train and the said switching circuit (2) has a timer (4) for incrementing and decrementing an on-time and off-time of pulse-feeding of the motor in registration with higher and lower pumping requirement of the transfusible means (32).

Full Text

-1A- FIELD OF THE INVENTION This invention relates to an improved portable infusion pump. This invention further relates to an improved portable infusion pump for administering fluids into a subject, even when the subject is in moving state. BACKGROUND OF THE INVENTION Ambulatory drug infusion is finding increased use in the treatment of different diseases, such as Thalassaemia, Cancer, Kidney trouble and such others. It also finds application in case of pain-relieving injections, insulin injections etc. By providing mobility, it enables the patient to resume a more normal lifestyle while receiving needed medications oyer prolonged periods. The ambulatory infusion has also been adopted for total parental nutrition for patients whose systems cannot tolerate rapid carbohydrate infusions. Out of hospital infusions can also offer considerable financial savings for patients who are otherwise in good physical conditions. Among the most severe and common forms of Thalassaemia is B-thalassaemia which necessitates regular blood infusion (packed cells) to the patients to supplement their low haemoglobin level. However, the body has to get rid Contd..p/2. of extra iron which gets deposited to the vital organs and this is done by infusing an iron chelating agent called Desferrioxamine into the body. This infusion takes place over 8-20 hours and thus the pumping device has to be portable so that the patient can move around and attend to his/her regular activities. This requires expensive infusion pump equipment. The types of infusion pumps commercially available are the implant type, the ambulatory but fixed interval pulsated type or the micrometer driven type. All these type involve hi-technology and pulsatile intervals and infusion volumes are preset at manufacture. Besides the above, existing devices typically employ long spur gear trains to reduce the speed and therefore all these types are very costly and as a consequence beyond the reach of poor patients. OBJECTS OF THE INVENTION It is therefore an object of this invention to propose an improved infusion pump which is light, portable and suitable for administering fluids into a subject even when the subject is in moving state. It is a further object of this invention to propose an improved infusion pump which is inexpensive, simple to operate and consumes less power. V 3. Another object of this invention to propose an improved infusion pump which is reliable and durable-It is yet another abject of this invention to propose an infusion pump which can continuously operate for 10 - 12 hours and regulate the pumping speed. Thus according to this invention there is provided an improved portable infusion pump comprising an improved portable infusion pump for administering fluid into a subject comprising an electric motor having an output shaft coupled to a toothed belt puller means; an intermediate drive meams; a plurality of bevel gears, and an idle gear for reduction of the rotational output of said output shaft and for supply of power to a bevel gear differential, a screw differential means for causing differential linear movement of its constituent members; a pusher plate transmitting the linear movement of one of the constituent members of said screw differential means to the plunger of a coupleable transfusible means for pumping fluid, a switching circuit for regulating the average speed of said motor, characterized in that saids speed—reduction means comprises an epicyclic gear train, and in that said switching circuit has a timer for incrementing and decrementing an on line and off line of the pulse—feeding of said motor in registration with higher and lower pumping requirement of said transfusible means. 3A. The device comprises a motor connected to a speed reducing mechanism which ultimately supplies power to a screw differential. One of the screw member of said screw differential undergoes a differential linear movement. This slow linear movement is transferred to a pusher plate which ultimately pushes the plunger of a coupleable transfusible means which pumps in fluid drops in a living body continuously and/or intermittently at pre-determined rates and at pre-determined intervals. The device employs epicyclic gear train to drastically reduce the number of moving parts in the speed reducing means and also increases the efficiency of (power consumption) of the device. This advantage makes the developed device simple and easy to maintain. Due to lesser number of components-the price of the device is also expected to be less than the existing ones. The average speed to the set up is controlled by a simple electronic switching circuit. The motor is provided with pulses of voltage and pulse width modulation control is applied through a timer connected in an electronic circuit. When higher rate of pumping is required the motor is supplied with pulses having small off time and high on time. When low speed is required, on time is made low and off time made high. At the outset of the description which follows,it is to be understood that ensuing description only illustrates a particular form which is only an exemplary embodiment and without intending to implying any limitation on the scope of this invention. The nature of the invention, its objective and further advantages residing in the same will be apparent from the following description made with reference to the non-limiting exemplary embodiments of the invention represented in the accompanying drawings. BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS. Fig. 1 is a schematic view of the pump according to the present invention. Fig.2 is the electronic switching circuit for average speed control of the motor. 5- The portable infusion pump (refer Fig.l) comprises an electrical motor (1), preferably a 3 volt dry battery cell operated low-voltage motor whose r.p,m on no load condition is in the range of 2500 to 3000. The average speed control of the motor is regulated by an electronic switching circuit (refer Fig .2) which will be described herein below while defining Fig.2. The motor output shaft (22) is coupled to a multi-stage speed reduction means, advantageously an opicyclic gear train (19) via a toothed belt pulley means (5) , an intermediate drive means (6) , a plurality of bevel gear (20,21), a planetary bevel gear (8) and an idle gear (9)- The rotational output of the motor shaft (22), is reduced in the first stage by said toothed belt pulley means (5) comprising a small toothed pulley (10) mounted rigidly on the motor output shaft (22) , a large toothed pulley (11) mounted ridigly on a first shaft (13) disposed parallel to said motor shaft, the pulleys (10,11) being operably connected by means of an endless toothed belt (12) having teeth on its inner side. Pitch of the inner teeth of the belt (12) corresponds to the pitch of the toothed pulley (10,11) . In the second stage, the rotational output of said toothed pulley (11) is used to drive the first shaft (13) which is supported by a bush bearing (14). A first spur gear (16) is mounted rigidly on said first shaft (13) adapted to rotate a second spur gear (17) which is mounted 5 6. loosely on a second shaft (26) and coupled to a first bevel gear (21). A third spur gear (15) is mounted rigidly an the first shaft 6 7. in mesh with each other. The screws (24,25) are of equal diameter and pitch but opposite hand and mounted on said second and third shafts (26,27), wherein right-hand screw (24) is rotated by the planetary bevel gear (8) restricting its linear movement- The spur gear (28) is also rotated along with the right hand screw (24) both being mounted rigidly on the same shaft (26). The left hand screw (25) is splined to the third shaft (27) so that It can have independent linear motion while rotating with the third shaft (27) - The spur gear (29) , which is rigidly mounted on the third shaft (27), remains in mesh with the spur gear (28) and thus gets rotated by the coaxial spur gear 29. The spur gear (29) , on being rotated by gear (28) causes rotation of the third shaft (27) and of the left hand screw (25). The gear spur (28) has one tooth less than the spur gear (29). Thus, the screws (24,25) rotate with rotational speeds which are very close but opposite in sense. This advantageously causes a 1 inear differential movement of the left hand screw (25) along with the third shaft (27). A pusher plate (30) is loosely mounted on said left hand screw (25) so that it can be acted upon by the linear motion of the left hand screw. (25). This pusher plate (30) transmits the linear motion of the left hand scew (25) to a plunger (31) of a coupleable transfusible means (32), said plunger (31) generating 7 8. a pumping effect on said transfusible means (32). Advantageously, said coupleable means (32) is s syringe which administers fluid into a subject even in moving state. Referring to Figure 2, the linear motion generated at the left hand scriew (25) can be varied and/or, preset for example, by regulating the average speed of said motor (1) through applying pulse width modulation control of pulses of the input voltage provided to the motor (1). A switching circuit (2) is provided to change the average speed of the motor vis-a vis the speed of pumping which comprises a voltage source (3) generating pulses of voltage to said motor (1) through a plurality of variable resistances (Ra , Rb ) connected in series; a timer (4) operating in a stable multivibrator mode receives voltage pulses from said resistances (Ra , Rb )5 an intermediate transistor (T1) receives output pulses from said timer (4) which in turn drive a power transistor (T2) via a resistor (R1 ) which feeds pulses to the motor (1); a biasing resistance (R 2); a plurality of capacitors (C1, C2 ); and a diode (D) which are grounded and connected across the motor terminal, The off time and the on-time of said timer (4) is controlled by said resistances (Ra , Rb), wherein off-time is made smal1 and the on-time is made high corresponding to the requirements of higher zand lower pumping respectively- e 9. WE CLAIM; 1. An improved portable infusion pump for administering fluid into a subject comprising an electric motor (1) having an output shaft (22) coupled to a toothed belt pulley means (5); an intermediate drive means (6); a plurality of bevel gears (20,21); and an idle gear (9) for reduction of the rotational output of said output shaft (22) and for supply of power to a bevel gear differential (19); a screw differential means (24,25,28,29) for causing differential linear movement of its constituent members (24,25); a pusher plate (30) transmitting the linear movement of one of the constituent members of said speed screw differential means (24,25,28.29) to a plunger (31) of a coupleable transfusible means (32) for pumping fluid, and a switching circuit (2) for regulating the average speed of said motor (1), characterized in that said speed-reduction means comprises an epicyclic gear train and in that said switching circuit (2) has a timer (4) for incrementing and decrementing an on—time and off-tine of the pulse-feeding of said motor in registration with higher and lower pumping requirement of said transfusible means (32). 2. The pump as claimed in claim 1, wherein said motor is low-voltage dry battery driven motor. 3. The pump as claimed in claim 1 or 2, wherein said motor is preferably a 3 volt motor with r.p.m in the range of 2500 to 3000 in no load condition. 9 10. 4. The pump as claimed in claim 3 wherein said belt pully means (S) comprises two pulleys (10,11) rotatably mounted on the motor output shaft (22) connected by an endless belt (12) having teeth on its inner side. 5. The pump as claimed in claim 4, wherein said two pulleys (10,11) are of different size and pitch of the pulleys (10,11) are same as that of the teeth of said endless belt (12). 6. The pump as claimed in claim 1, wherein said intermediate drive means (6) comprises a first shaft (13) motor shaft (22) on which a first and a second spur gear (16,17) are adapted to rotate a third and fourth spur gears (15,18) mounted thereon, said third and fourth gears (15,18) providing the inputs to said bevel gear differential (19). 7. The pump as claimed in claim 6, wherein said first spur gear (16) has one tooth more than that of the third spur gear (15). 8. The pump as claimed in claim 6 wherein number of teeth of each one of said third and fourth gears (15,18) is identical. 9. The pump as claimed in claim 1, wherein said bevel gears (20 21) are in mesh with said third and fourth spur gear (15,18) of said intermediate drive means (6). 10. The pump as claimed in claim 1, wherein said idle gear (9) is interposed between the first spur gear (16) and the fourth spur gear (18). 10 12. 11- The pump as claimed in claim 1, wherein said planetary bevel gear (8) is mounted in mesh with said pair of bevel gears (20,21) and wherein the revolution of the planetary gear (8) intermeshed with said bevel gear pair (20,21) produces the output of said bevel gear differential (19) 12. The pump as claimed in claim 1, wherein said screw differential means (24,25,28,29) comprises a right hand threaded screw (24) and a left hand threaded screw (25), both having equal pitch circle diameter being mounted on shafts (26,27); and a third pair of spur gears (28,29) 13. The pump as claimed in claim 12, wherein linear motion of right handed screws (24) remains restricted being driven by said planetary gear (8) and wherein said left handed screw (25) is driven by one (29) of the gears of said third pair of spur gear (28,29). 14. The pump as claimed in claim 1, wherein said pusher plate (30) is 1oose1y maunted on said 1eft-hand screw shaft (27) and wherein said plunger of said coupleable transfusible means (32) being pushed at a speed commesurating with the slow linear motion of said left hand threaded screw member (25)- 15. The pump as claimed in claim 1, wherein said electronic switching circuit comprises a plurality of variable resistance (Ra ,Rb ); an intermediate transistor in which output pulses of 13. said timer (4) are fed through a resistor (T1 ); a power transistor (T2) receiving pulses from said intermediate transistor (T1) ) for amplifying and transmitting said pulses to said slow voltage motor (1); a biasing resistor(R2), a plurality of capacitors (C1, C2); and a free willing diode (D) which are grounded and connected across the motor terminal. 16. The pump as claimed in claim 6, in the preceding claims wherein said gears are made of synthetic materials, for example Nylon, Delrin, Teflon. 17. A pump as claimed in the preceding claims wherein said bevel gears are preferably made of Delrin. 18. A pump as claimed in the preceding claims wherein said screws are preferably made of Duralium. 19. A pump as claimed in the preceding claims wherein the connecting and fixing bolts and nuts and parts coming in direct contact with the fluid are surface-hardened steel. 20. An improved portable infusion pump substantially as hereinbefore described with reference to the accompanying drawings. The invention relates to an improved portable infusion Dump for administering fluid into a subject comprising an electric motor (1) having an output shaft coupled to a toothed belt pulley means (5); and intermediate drive means (6); a plurality of bevel gears (20,21); and an idle gear (9) for reduction of the rotational output of said output shaft (22) and for supply of power to a bevel gear differential (19); a screw differential means (24.25.28,29) for causing differential liner movement of its constituent members (24,25); a pusher plate (30) transmitting the linear movement of one of the constituent members of said speed screw differential means (24,25,28,29) to a plunger (31) of a coupleable transfusible means (32) for pumping fluid, and a switching circuit (2) for regulating the average speed of said motor (1). The speed-reduction means comprises an epicyclic gear train and the said switching circuit (2) has a timer (4) for incrementing and decrementing an on-time and off-time of pulse-feeding of the motor in registration with higher and lower pumping requirement of the transfusible means (32).

Documents:

00675-cal-2001-abstract.pdf

00675-cal-2001-claims.pdf

00675-cal-2001-correspondence.pdf

00675-cal-2001-description(complete).pdf

00675-cal-2001-description(provisional).pdf

00675-cal-2001-drawings.pdf

00675-cal-2001-form-1.pdf

00675-cal-2001-form-2.pdf

00675-cal-2001-form-3.pdf

00675-cal-2001-form-5.pdf

00675-cal-2001-g.p.a.pdf

00675-cal-2001-letters patent.pdf

675-CAL-2001-FORM 27.pdf