Automatic Injection System

Abstract

Apparatus for manipulating a hypodermic syringe to automatically administer an injection. The apparatus includes a hand held probe unit within which a loaded hypodermic syringe is placed. Operation of a control switch on the hand held unit will automatically drive the syringe in a cycle in which the syringe needle is seated in the patient's body, the syringe plunger is depressed to expel the charge from the syringe and the syringe needle is automatically withdrawn from the patient. The system may be operated to include an aspirating step between the needle seating and the plunger depressing steps, one embodiment of the invention providing for automatic timing of the aspiration step while another embodiment placing control of the duration of aspiration in the user. The system, in one form, may further provide for adjusting the rate at which the plunger is depressed, to thereby control the rate of injection.

Parent Case Text

This application is a continuation-in-part of my copending application Ser. No. 869,484, filed Oct. 27, 1969 and now abandoned.

Description

BACKGROUND OF THE INVENTION

The present invention is especially designed for use by persons, as for example, diabetics, who are required to follow an extensive program of self administered hypodermic injections. While the manual dexterity required is not overly great, many persons, especially small children, for either mental or physical reasons find it difficult to maintain the steadiness of hand and purpose necessary to administer the injections with the minimum amount of discomfort. Discomfort and damage to the flesh can occur upon movement of the needle while it is seated in the flesh and even after long experience, many people find it difficult to hold the syringe body perfectly stationary while at the same time depressing the syringe plunger at a slow and steady rate. Most persons through experience will find certain areas of the body which are less sensitive to the inevitable pain of the needle and will tend to prefer to make injections in these regions. This results in a toughening of the flesh in regions where numerous injections are made, increasing the difficulty of inserting the needle and of expelling fluid from the seated needle. Ideally, the fluid should be expelled from the needle at a relatively slow rate so that it can flow easily into the tissues and so that the temperature of the fluid during its passage through the needle can more nearly approach body temperature. A slow rate of injection requires that the needle be seated in the flesh a longer period of time with the consequent greater possibility for movement of the needle and resultant flesh damage.

A primary object of the present invention is to provide apparatus for efficiently administering hypodermic injections with a minimum amount of discomfort.

SUMMARY OF THE INVENTION

The present invention includes a hand held probe unit, within which a syringe body receiving carriage is mounted for reciprocation. A syringe plunger receiving element is mounted on the carriage for reciprocation relative to the carriage. An internally threaded sleeve is mounted on the carriage for free rotation relative to the carriage at an axially fixed position on the carriage, and the sleeve is fixedly attached to one end of a Bowden wire. The Bowden wire leads from the hand held unit to a control box and is coupled within the box to a reversible motor which is operable to drive the wire in rotation in either direction. Within the control box, the wire is also coupled to a drive unit which may take the form of a pair of alternatively actuated solenoid, which can be operated to reciprocate the wire between two established limits. Because the sleeve within the hand held unit is held against axial movement relative to the carriage, reciprocation of the wire reciprocates the carriage bodily within the hand held unit. The syringe plunger receiving element is threadably coupled to the sleeve so that rotation of the sleeve will reciprocate the plunger element upon the carriage. Reciprocation of the carriage is employed to seat or withdraw the syringe needle from the patient, while movement of the syringe plunger on the carriage, by rotation of the wire, is employed to operate the syringe plunger.

A control switch is mounted on the hand held unit and connected in an electric control circuit which controls operation of the motor and solenoids. In one form of the invention, a momentary actuation of the control switch will drive the apparatus in an automatic cycle in which the needle is seated, a timed aspiration step is performed by a slight withdrawal of the plunger after which the plunger is depressed at a controlled rate to expel the fluid from the syringe, and, when the fluid has been completely expelled, the needle is withdrawn from the patient.

The aspiration step is employed in connection with many types of injections, as for example, insulin, where it is necessary that the injection be made into fatty tissue and not into a blood vessel. By applying a slight withdrawal to the syringe plunger after the needle is seated, fluid is aspirated from the patient's body into the needle, and if blood appears in the needle during the aspiration step, the needle is withdrawn and relocated. The control circuit includes a provision by which the patient can initate a powered withdrawal of the needle by manipulation of the control switch. In one form of control circuit, a timing circuit is included which can be adjusted to establish a definite time duration of the aspirating step. In this form of circuit, depression of the plunger will occur automatically at the conclusion of the aspirating step unless the patient interrupts the cycle by manipulation of the control switch. In a second form of circuit, the aspirating step will continue as long as the patient holds the control switch in a forward position, depression of the plunger commencing as soon as the patient releases the control switch.

Other objects and features of the invention will become apparent by reference to the following specification and to the drawings.

IN THE DRAWINGS

FIG. 1 is a perspective view of an automatic injection system embodying the present invention;

FIG. 2 is an exploded perspective view of the probe assembly of FIG. 1;

FIG. 3 is a top plan view, partially in cross-section, of the probe assembly of FIG. 1;

FIG. 4 is a perspective view of a portion of the syringe plunger operating mechanism of the probe assembly;

FIG. 5 is a top plan view of the drive unit of the system of FIG. 1 with the cover removed;

FIG. 6 is an offset cross-sectional view of the drive unit taken approximately along the offset section line 6--6 of FIG. 5;

FIG. 7 is a schematic diagram of one form of electrical control circuit for the system of FIG. 1;

FIG. 8 is a perspective view, partially in section, of an alternative form of carriage and syringe plunger operating mechanism;

FIG. 9 is a cross-sectional view of the control box taken approximately on the same line as FIG. 6, but showing an alternative form of drive mechanism;

FIG. 10 is a detail cross-sectional view taken on line 10--10 of FIG. 9; and

FIG. 11 is a schematic diagram of an alternative form of electrical control circuit.

Referring first to FIG. 1, an automatic injection system embodying the present invention is shown as including a probe assembly designated generally 20, a separate or remote control and drive unit designated generally 22 and a flexible control and drive unit cable interconnecting various elements in the control box 22 to mechanism within probe 20. A conventional electric power cord 26 is connected within control box 22 to supply electric power to various control and drive elements to be described in greater detail below.

In FIG. 2, probe 20 is shown in an exploded view and is seen to include a main casing element designated generally 28 and a secondary casing element or cover 30 which is detachably mounted on main casing 28 as by half sleeve sections 32 and 34 on cover 30 and main casing 28 respectively which are conformed to be received slidably within complimentary portions on the mating casing member. Preferably, a suitable detent or mechanical latch (not shown) will be provided to releasably hold the two casing sections 28 and 30 in their assembled position shown in FIG. 1. The forward end of cover section 30 is formed with an internally threaded bore 36 which threadably receives the shank portion 38 of a hollow tube 40 whose forward end is beveled as at 42.

The internal diameter of tube section 40 is dimensioned to slidably receive the main body portion or cylinder 44 of a conventional hypodermic syringe designated generally 46 to locate the needle 48 of syringe 46 coaxially within tube 40. By threading tube 40 in threads 36, the depth of penetration of the syringe needle can be adjusted as desired. The body portion 44 of syringe 46 is conventionally formed with a projecting annular flange 50 through which the needle plunger 52 projects, plunger 52 being formed with a projecting flange 54 at its outer end.

Referring now to main casing assembly 28, a syringe body receiving carriage designated generally 56 is mounted within casing 28 and carries upon itself a syringe plunger receiving seat 58.

Referring now particularly to FIGS. 2 and 3, carriage 56 includes a syringe flange receiving block 60 located at the forward end of the carriage and formed with a recess 62 into which the flange 50 of syringe 46 may be inserted from above as viewed in FIG. 2. A U-shaped notch 64 at the rearward end of recess 62 loosely receives the plunger 52 of the syringe, while a somewhat larger U-shaped notch 66 at the forward side of recess 62 loosely receives body portion 44 of the syringe. As best seen in FIG. 2, when the syringe is located in seating block 60, flange 50 is received within recess 62 and the syringe body is thus restrained against axial movement relative to carriage 56.

A pair of tubular support rods 68 are fixedly secured to seating block 60 and extend rearwardly from the block in parallel relationship. A coupling block 70 is fixedly secured to and supported between the rearward ends of rods 68. Opposed pairs of guide blocks 72 and 74 are fixedly mounted on the interior wall of casing 28 and slidably receive rods 68 to support the entire carriage 56 for longitudinal reciprocatory movement within the casing.

Syringe plunger receiving block 58 is shown in detail most clearly in FIG. 4 and includes a block-like member 76 formed with a vertically extending T-shaped slot 78 in its forward end adapted to receive the flange 54 of the syringe in the manner best shown in FIG. 3 Block 76 is formed with concave notches 80 and 82 on its opposite side, notches 80 and 82 being dimensioned to slidably support block 76 upon the inner sides of rods 68 of carriage 56. A drive rod 84 having an external thread section 86 at its rearward end is mounted for free rotation at its forward end within a bore 88 in block 76 and is retained against axial movement in either direction relative to block 76 by a knurled knob 90 fixedly mounted upon rod 84 at the rearward side of the block and by a snap ring 92 engaged with rod 84 at the forward end of bore 88.

Knob 90 is provided with four or more radially extending notches 94 which cooperate with a sliding latch 96 frictionally retained on the top of block 76 by a retainer 98. Latch 96 may be disengaged from a notch 94 to permit rod 84 to be rotatively adjusted relative to block 76 and then held at the desired position of rotative adjustment by sliding latch 96 rearwardly into an aligned notch 94. The purpose of this adjustment will be explained below.

Referring now particularly to FIG. 3, it is seen that an elongate internally threaded sleeve 98 is supported within a bore 100 in member 70 for free rotation relative to member 70 as by bushings 102 and locked against axial movement relative to the bore as by snap rings 104. The internal thread section 106 within sleeve 98 is threadably engaged with the thread section 86 on drive rod 84 of plunger seating block 58 so that rotation of sleeve 98 acting through the threaded connection to rod 84 will drive the rotatively locked rod 84, and hence block 58 in longitudinal movement relative to the carriage along rods 68. It will be recalled that rod 84 is rotatively locked by latch 96. The initial rotative adjustment afforded by latch 96 and the plurality of notches 94 on knob 90 is for the purpose of establishing the initial longitudinal spacing between block 76 of seating block assembly 58 and block 60 of carriage 56.

Referring particularly to FIG. 3, it is seen that flexible cable 24 takes the form of a Bowden wire which includes an outer sheath 108 within which is freely mounted a flexible wire cable 110 whose right hand end as viewed in FIG. 3 is fixedly and rigidly secured to the end of sleeve 98 as at 112. Cable 98 functions in the disclosed apparatus as a Bowden wire, possessing sufficient longitudinal stiffness to reciprocate carriage 56 on rods 68 upon reciprocation of cable 110 and also having sufficient torsional rigidity to drive sleeve 98 in rotation upon rotation of cable 110. Reciprocation of cable 110 thus reciprocates carriage 56 and plunger seating block 58 as a unit, while rotation of cable 110 will drive plunger seating block 58 longitudinally relative to carriage 56.

Reciprocation and rotation of cable 110 is under the control of mechanism mounted in control box 22 and best seen in FIGS. 5 and 6. Referring first to FIG. 6, it is seen that outer sleeve 108 is fixedly secured to the casing of box 22 by a bushing 114 threadably clamped to the box wall as by a nut 116. Cable 110 projects through the interior of bushing 114 and is fixedly clamped or secured to one end of a rod 118 mounted for both axial and rotary movement relative to bushing 114. Rod 118 is formed with a centrally located reduced diameter section 120. Vertically spaced washers 124 are mounted on the end of a T-shaped drive lever 128 to provide a free pivotal coupling of rod 118 to the lever. Lever 128 is pivotably supported on a fixed frame portion of box 22 as at 130 and the opposite ends of lever 128 are pivotally connected as at 132 and 134 to the armatures 136 and 138 of a pair of solenoids 140 and 142. In FIG. 5, the apparatus is shown with solenoid 140 energized which has pulled in its armature 136 to swing lever 128 to its extreme limit in a clockwise direction about pivot 130. Energization of solenoids 140 and 142 is under the control of a control circuit to be described below. The circuit is so arranged that during operation of the device, one of the two solenoids is energized at all times while the other of the two solenoids is de-energized. Upon de-energization of solenoid 140 and energization of solenoid 142, armature 138 is retracted, while armature 136 is extended to thereby swing lever 128 in a counter clockwise direction about its pivot 130 to thereby drive rod 118 and cable 110 to the right as viewed in FIG. 5. This shifting movement of rod 118 is transmitted by cable 110 to carriage 56 to drive the carriage to the right from the position illustrated in FIG. 3. Carriage 56 can be restored to its original position by subsequently de-energizing solenoid 142 and re-energizing solenoid 140.

The left hand end of rod 118 as viewed in FIGS. 5 and 6 is connected to T-shaped drive crank as by a cross pin 146. Reduced diameter sections at the outer ends of the cross arms of crank 144 are slidably received within elongate U-shaped members 150 which are fixedly mounted within a block 152 to permit relative axial movement while maintaining a rotary drive coupling. Block 152 is rotatably supported upon a threaded stud 154 and locked against axial movement relative to the stud as by a snap ring 156 and the threaded section of stud 154. A spring loaded detent designated generally 158 releasably locks block 152 against rotation relative to the stud, but may be disengaged to permit the stud to rotate relative to block 152 under certain circumstances to be described below.

Stud 154 is supported upon the end of a grooved drive shaft 160 which is received for axial sliding movement within a complementary shaped bore 162 in stud 154. The grooved surfaces of drive shaft 160 and the complementary grooved surfaces of bore 162 lock stud 154 and drive shaft 160 against rotation relative to each other while at the same time accomodating axial movement of the stud and shaft relative to each other. Shaft 160 is driven in rotation by a reversible variable speed electric motor designated generally 164 operated under the control of an electrical control circuit to be described below.

The threaded section of stud 154 carries an external nut 166 which is locked against rotation relative to block 152 by a pin 168 fixedly mounted in block 152 and projecting through a bore 170 in a flange 172 integrally formed on nut 166.

Upon energization of motor 164, shaft 160 is driven in rotation in a direction determined by the direction of rotation of reversible motor 164. Rotation of shaft 160 is transmitted to stud 154, and with block 152 rotatively latched to stud 154 by detent 158, block 152 and its U-shaped drive elements 150 are likewise driven in rotation. Rotation of U-shaped elements 150 is transmitted via T-shaped drive crank 144 to shaft 118 and thence to cable 110. Rotation of cable 110 in turn, refering to FIG. 3, drives sleeve 98 in rotation. The threaded interconnection 106-86 between sleeve 98 and rod 94 transmits the rotation of sleeve 98 into axial movement of shaft 84 to thus drive the syringe plunger receiving seat 58 longitudinally on carriage 56 in a direction dependent upon the original direction of rotation of motor 164.

CONTROL SYSTEM

In FIG. 7 there is disclosed a control system for operation of the embodiment of FIGS. 1 through 6 described above. The system includes certain manually operable or adjustable external controls whose general location is best seen by reference to FIGS. 1 and 3.

The actuator of a three position mode switch 180 projects from the front panel of control box 22. When in its centered or neutral position, mode switch 180 is in an "OFF" position in which power is disconnected from the control circuit. When displaced in one direction from its centered position, the mode switch connects power to the control circuit and conditions the circuit for automatic operation, while when displaced from the "OFF" position in the opposite direction, mode switch 180 connects power to the circuit and conditions the circuit for a so called manual operation, the automatic and manual positions of the switch being indicated by A and M.

The control circuit also includes two adjustable potentiometers whose knobs 182 and 184 project from the front panel of control box 22. Potentiometer 182, as will be described below, is a variable resistance in a RC timing circuit and is employed to adjust the timing period of an aspiration step in the cycle of the system. Potentiometer 184 is a variable resistor connected in the power supply circuit to motor 164 and is employed to adjust the speed of motor 164.

A three position switch actuator 186 projects from a switch box 188 mounted on probe 20. Actuator 186 is employed to alternatively operate two switches 190 and 192 mounted within switch box 188.

Referring now to FIG. 7, the control circuit includes a pair of supply lines L1 and L2 which are connected via power cord 26 to a conventional 115 volt AC power supply. A transformer 200 is employed to cut the supply voltage and, in combination with a rectifier 202 to supply power to the control circuit in the form of 24 volts DC.

As shown in FIG. 7, the circuit finds mode switch 180 set for "automatic" operation. Among other elements, the circuit includes two relays designated generally 204 and 206, each of which controls four sets of contacts. In the stage which the circuit is shown in FIG. 7, both of the coils of relays 204 and 206 are de-energized.

For purposes of illustration, it will be assumed that at this time a filled syringe 46 has been loaded into probe 20 and that the plunger receiving block 78 has been withdrawn rearwardly from syringe receiving block 60 the proper distance to receive the flange 54 of the plunger, which at this time has been withdrawn from the syringe body by a distance determined by the volume of the charge of fluid within the syringe. The relative positioning of the various parts of the mechanism to accomplish this latter purpose will be described below.

With syringe 46 loaded within probe 20 and the circuit in the condition shown in FIG. 7, the system is ready to commence the performance of an automatic cycle. The carriage 56 within probe 20 is, at this time, fully retracted or at its leftward-most limit of movement as viewed in FIG. 3, because reverse solenoid 140 is energized at this time from the +12 volts DC side of rectifier 202 via switch leaf 208 of mode switch 180, contacts 1-1A of relay 204 and the 12 volt negative conductor 210 connected to the negative side of rectifier 202. Relay 140, when energized, positions lever 128 in the position shown in FIG. 5 which retracts cable 110 to its extreme left-hand limit of movement as viewed in FIG. 3.

With the various switches and mechanical elements in the position described, the user places probe 20 at the desired location for the injection by placing beveled end 42 of element 40 in position. Because the carriage 56 is retracted to its lefthand limit of movement at this time, the syringe needle 48 is withdrawn well within the interior of tube 40.

To initiate the automatic cycle, the user pushes the actuating lever 186 on probe 20 forwardly to thereby close the contacts of switch 192. Closing of the contacts of switch 192 connects the positive terminal of rectifier 202 to terminal 4 of relay 204 to thereby transmit a positive pulse from terminal 4 to terminal 4A of relay 204 and thence through a 1.5 K resistor 212 and conductor 214 to the gate of a silicon control rectifier 216. The positive pulse thus supplied to SCR 216 triggers this element to make it conductive to connect the junction 218 of relay 206 to the negative side of the line, i.e. conductor 210, the opposite end of relay 206 already being connected to the positive side of the line via conductor 220 by switch leaf 208 of mode switch 180.

To commence operation of the cycle, only a momentary depression of switch actuator 186 is required, this temporary displacement of actuator 186 serving to transmit the triggering pulse to SCR 216, and to energize the coil of relay 204. The coil of relay 204 becomes energized from the positive pulse supplied to contact 4 of relay 204 via the relay coil, clutch switch 196 and normally closed switch 190 to the negative side of the line at conductor 210. Energization of the coil of relay 204 shifts all of its contacts to complete a lock in circuit via contacts 4-4B and switch leaf 208 to the automatic position of mode switch 180 to supply positive voltage to terminal 4 upon the subsequent opening of switch 192.

The shifting of the contacts of relay 204 open the circuit between terminal 1 of relay 204 and terminal 1A and simultaneously connects terminal 1 to terminal 1B thereby energizing relay 142 to drive carriage 156 to its forward limit of movement to thus seat the needle of syringe 46 in the patient. At the same time, contacts 2 and 3 of relay 204 are connected to terminals 2B and 3B respectively which are in turn connected to terminals 3 and 2 of relay 206. Relay 206 is energized at this time, by the shifting of SCR 216 to its conductive state, and thus terminals 2 and 3 of relay 206 are now connected to terminals 3B and 2B of relay 206, thereby energizing motor 164 to drive in a reverse direction which rotates cable 110 in a direction tending to pull plunger 52 of the syringe outwardly to cause the syringe to aspirate fluid from the patient.

The purpose of the aspiration step in the cycle is to assure that the location chosen for the injection is such that the syringe needle is not seated in a vein or artery. Insulin injections, for example, are intended to be made into fatty tissue and not directly in the bloodstream, By withdrawing or pulling out of the syringe plunger after the needle is seated, the patient can observe the needle to see if the aspiration draws any blood into the syringe. In the event blood should appear, immediate withdrawal of the needle may be accomplished by moving switch actuator lever 186 to the rear, thereby opening switch 190 which de-energizes relay 204 to open the circuit via the number 1 contacts of this relay to the forward acting solenoid 142 and re-energize the reverse or withdrawal actuating solenoid 140.

In the circuit shown in FIG. 7, the aspiration step of the cycle is automatically programmed to continue for a predetermined length of time by adjustment of potentiometer 182 which is the resistance element of an RC timing circuit which includes condenser C1. If switch 190 is not opened within the preset time period, the cycle will automatically continue. If, however, during the aspiration period, switch 190 is opened, the needle is withdrawn and the cycle does not continue.

Timing of the aspiration cycle is commenced when the coil of relay 206 is energized to shift its contacts and thereby connect terminals 4 and 4B of relay 206 to energize the timing circuit. Energization of the timing circuit causes a charge to build up on condenser C1 and when the charge has built up to the desired value, discharge of the condenser switches a unijunction element 222 to activate an oscillator circuit 224 which, via a second SCR 226, transmits negative pulses from conduit 210 to the lower terminal 218 of relay 206 and thus to the anode of SCR 216 to reset SCR 216 in its nonconductive state. This action in turn de-energizes relay 206 to restore its contacts to the full line position shown in FIG. 7. When the timing circuit times out and the contacts of relay 206 return to their original position, the switch leafs associated with terminals 2 and 3 of relay 206 shift to reverse the polarity of the connections to motor 164, thereby reversing the direction of drive of motor 164 to its forward direction so that the motor now drives the syringe plunger in its forward or charge expelling direction.

As stated above, the speed of drive of motor 164 is controlled by potentiometer 184.

The motor continues to drive in the charge expelling direction until plunger carrying block 76 bottoms out against syringe receiving block 60. Bottoming of the two blocks in the afore described manner places a torsional load on cable 110 which backs up through the cable and unseats detent 158 (FIG. 6) so that the cable and block 152 remain stationary while motor 164 continues to drive. Block 152 is coupled, via pin 168 to nut 166 and, as nut 166 is held against rotation, the continued rotation of drive shaft 160 and stud 154 drives nut 166 to the right as viewed in FIG. 6. This causes flange 172 of nut 166 to shift the contacts of switch 196, this action referring now to FIG. 7, opening contacts 196 to thereby de-energize relay 204. De-energization of relay 204 returns its various switch leafs to their original position, thereby energizing reverse solenoid 140 which acts to withdraw the syringe from the patient's body.

At this particular time, the injection cycle has been completed, carriage 56 which carries the syringe being withdrawn to its extreme lefthand limit of movement as viewed in FIG. 3, with the syringe plunger carrying block being bottomed or in contact with block 60 of carriage 56. The casing is opened and the emptied syringe is removed.

At this time, plunger block 76 is approximately reset to its original position by again shifting actuator 186 forward to close contacts 192 which starts the mechanism in another "aspirating cycle" in which plunger block 76 is retracted rearwardly from carriage block 60. When block 76 arrives at the desired spacing, actuator 186 is shifted rearwardly by the user to stop the cycle by de-energizing relay 204 by the opening of switch 190. The closing of contacts 1-1B of relay 206 temporarily bypasses clutch contacts 196 to enable energization of relay 204 until contacts 196 close by the driving of nut 166 back to its original position.

A fine position adjustment of plunger block 76, if necessary, is made by manipulation of knob 90.

MODIFIED FORM OF CARRIAGE AND PLUNGER OPERATING MECHANISM

A modified form of carriage and plunger operating mechanism is shown in FIG. 8, parts of the FIG. 8 mechanism analogous to parts of the originally described mechanism employing the same reference numerals with a prime. The assembly of FIG. 8 is adapted for operation by a modified form of control circuit, shown in FIG. 11 and to be described below.

The embodiment of FIG. 8 includes a carriage receiving block 60' to which, as in the previously described embodiment, are fixedly secured a pair of rearwardly extending parallel rods 68' which are fixedly coupled to a modified form of coupling block which takes the form of a pair of annular discs 70' and 71'. An elongate sleeve 98' is fixedly secured at its rearward or left-hand end to cable 110' and is formed at its forward end with a relatively short internal thread section 106', threadably engaged with a relatively long threaded section 86' on rod 84'. As in the previous embodiment, rod 84' is rotatively received within the syringe plunger receiving block 76', but is locked against axial movement relative to block 76'. As in the previous case, block 76' is slidably supported upon rods 68'. The axial length of the smooth or unthreaded section 84' is less than the axial length of the threaded section 106' in sleeve 98'. A compression spring 250 is located within sleeve 98'.

In the structure shown in FIG. 8, the possibility of plunger carrying block 76' bottoming out against the forwardmost portion 71' of the coupling block assembly is forestalled. When cable 110' is driven in a direction which draws plunger carrying block 76' away from block 60', block 76' will move toward coupling element 71' until the unthreaded portion 84' of the drive rod passes into nut section 106', at which time further rotation of sleeve 98' rotatively uncouples nut 106' from threaded section 86'. Spring 250 resiliently biases the threaded section 86' to the right so that the threads promptly come back in to mesh with each other upon reversal of the direction of rotation of cable 110'.

MODIFIED CLUTCH ASSEMBLY

A modified form of clutch assembly is disclosed in FIGS. 9 and 10. Again parts of the mechanism corresponding to parts previously described in connection with the embodiment of FIGS. 1-5 employing the same reference numeral with a prime.

In the arrangement shown in FIGS. 9 and 10, an axially slidable spline type connection 252 is employed to rotatively couple the lefthand end of shaft 118' to a hollow shaft 254 rotatively supported in a bushing 256 mounted in control box 22'. A radially enlarged disc-shaped flange 258 is fixedly mounted on the lefthand end of shaft 254 and carries an axially projecting pin 260 to which is fixedly coupled to one end of a spiral torsion spring 262. The central portion of flange 258 is internally threaded at 264 and threadably receives a stud 266 which is fixedly mounted on the end of drive shaft 160'. A stop pin 268 is fixedly mounted in and projects radially from stud 266 to provide a positive rotary drive coupling, via pin 260, when engaged with the pin. A second pin 270 is mounted in stud 266 and projects axially from the stud and is coupled to the remaining end of torsion spring 262.

Referring now to FIG. 10, upon rotation of drive shaft 160' in a clockwise direction as viewed in FIG. 10, stop pin 268 will engage pin 260 to impart clockwise rotation to flange 258 and thence eventually to cable 110'. Should drive shaft 160' be driven in a counterclockwise direction as viewed in FIG. 10, rotation in this direction will tend to wind up or tighten torsion spring 262, and thus the counterclockwise rotation of drive shaft 162' is transmitted through a resilient coupling in the form of spring 262 to flange 268 and thence to cable 110'.

Rotation of drive shaft 160' in the counterclockwise direction is employed to drive, via cable 110', the syringe plunger receiving block in the forward or fluid expelling direction. As in the previously described embodiment, the syringe plunger block is driven in the fluid expelling direction until it bottoms out against the carriage. Bottoming of the plunger block increases the torsional resistance to movement of cable 110', and this action results in a further tightening of spring 262 by relative rotation of stud 266 and flange 258. This relative rotation is translated into axial movement of flange 258 by the threaded connection to stud 266, and the consequent axial movement of flange 258 is employed to actuate the contacts of the automatic clutch switch 196'.

MODIFIED CONTROL CIRCUIT

In FIG. 11, there is disclosed a modified form of control circuit which dispenses with the automatic timing of the aspiration step employed in the circuit of FIG. 7, while enabling the operator to perform an aspirating step under manual control. The circuit of FIG. 11 further enables a precise power driven positioning of the syringe plunger receiving block relative to the carriage under the control of the operator.

Because the control circuit shown in FIG. 11 operates to control two forward and reverse solenoids 140 and 142 and a reversible motor 164 by means of the two switches 190 and 192 actuated by actuator 186 on the probe, the control circuit of FIG. 11 may be used with any of the various mechanical embodiments previously described. The control circuit of FIG. 11 does not include controls for automatic timing of the aspirating step, nor does it include a variable speed adjustment for reversible motor 164.

In FIG. 11, the circuit is shown with mode switch 180 positioned for manual operation. When in the manual mode, the position of plunger carrying block 76 relative to syringe receiving block 60 may be accomplished by operating reversible motor 164 under the control of switch actuator 186. To drive plunger receiving block rearwardly away from the flange receiving block -- that is to withdraw the syringe plunger from the syringe body, switch actuator 186 is pushed forwardly to cause switch 192 to connect one side of the power supply line L1 to contact 192A, thereby energizing solenoid coil 280 whose other side is connected to line L2 of the power supply. Energization of solenoid 180 shifts its relay contacts from the illustrated position to connect terminal 1B to terminal 1C, thereby energizing motor 164 in the reverse direction.

To shift the syringe plunger receiving block in the opposite direction, motor 164 is energized to drive in the forward direction by shifting switch actuator 186 forwardly to close switch 190 with contacts 190A. This completes a circuit from supply line L1 via terminals 3N, 2M, 2N of mode switch 180, switch 190 to terminal 190A and thence to terminal 1N of the mode switch and thence via terminal 1M of the mode switch to the forward direction drive of motor 164 and thence via automatic clutch switch 196 to the L2 side of the power supply.

To operate the system in an automatic cycle, mode switch 180 is shifted to its automatic mode where its contacts are made respectively from terminals 1N, 2N and 3N to terminals 1A, 2A and 3A. This action immediately energizes the reverse solenoid 140 to withdraw the carriage to its extreme limit of movement away from the patient, thereby retracting the needle clear. The energizing circuit for solenoid 140 from the L1 side of the line is via terminals 3N, 3A, 4B, 4D, through solenoid 140 and closed clutch switch 196 to the L2 side of the line.

To commence an automatic cycle, actuator 186 is pushed forwardly to connect the L1 side of the line to contact 192A at switch 192, thereby energizing relay 280. Relay 280 shifts its contacts from the illustrated position and thus energizes the reverse drive motor via terminals 1B and 1C as described above. Relay 282 is simultaneously energized from the L1 side of the line via terminals 2B and 2C of relay 280, normal closed switch 190, terminals 2N, 2A of mode switch 180 and thence via clutch switch 196 to the L2 side of the line. Energization of relay 282 shifts its contacts, thus disconnecting the reverse solenoid 140 by opening the circuit at contact 4D and simultaneously closing a circuit to the forward relay 142 at contact 4B-4C.

It will be noted that at this instant, the needle is injected, by actuation of forward solenoid 142, and the plunger is being withdrawn by the operation of the reverse mode of motor 164. Aspiration can continue as long as actuator 186 is manually held in the forward position. Upon release of actuator 186 and the return of the actuator to its centered or neutral position, contact 192A is opened and solenoid 280 is de-energized, thereby returning its contacts to the illustrated position in FIG. 11. This opens the circuit to the reverse mode of motor 164 both at contacts 190a and also by virtue of the opening of the contact pair 1B 1C.

Solenoid 282, once energized, is locked in via contacts 3C, 3B, 3A, 3N which complete a circuit to the top of solenoid 282 as viewed in FIG. 11 from the L1 line, the lower end of solenoid 282 being connected to L2 via the closed switch 190, contacts 2N, 2A thence to clutch switch 196. The forward drive mode of motor 164 is energized when relay 280 is de-energized and relay 282 is energized, the circuit from the L1 side of the line passing through contacts 2B, 2D, 5C, 5B and thence to the forward side of motor 164.

At this time, the needle is now seated and the plunger is being driven forward to expell the charge from the syringe. The action continues until the plunger block bottoms on the carriage and consequently opens the clutch switch contacts 196, this action de-energizing solenoid 282. De-energization of solenoid 282 shifts its contacts back to the original position, thus energizing reverse solenoid 140 which thus withdraws the needle.

While various embodiments of the invention have been described, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting, and the true scope of the invention is that defined in the following claims.

Claims

I claim:

1. For use in operating a hypodermic syringe having a syringe body and a syringe plunger reciprocable within said syringe body; apparatus comprising a casing, a carriage mounted for reciprocating movement in said casing, syringe body receiving means on said carriage for releasibly coupling a syringe body to said carriage for movement therewith, syringe plunger receiving means mounted on said carriage for reciprocation relative to said carriage, rotary means on said carriage coupled to said plunger receiving means and operable when rotated to reciprocate said plunger receiving means on said carriage, a drive element mounted in said casing for both reciprocatory and rotary movement relative to said casing, means coupling said drive element to said rotary means, first reversible drive means for reciprocating said drive element relative to said casing to reciprocate said carriage, and second reversible drive means for rotating said drive element to drive said rotary means in rotation to reciprocate said plunger receiving means on said carriage.

2. Apparatus as defined in claim 1 further comprising means defining an end limit of movement of said plunger receiving means in one direction of movement, and control means responsive to the arrival of said plunger receiving means at said one end limit of movement for reversing said first drive means.

3. Apparatus as defined in claim 1 wherein said first drive means is operable in a first condition to locate said carriage in a withdrawn position within said casing and is operable in a second condition to locate said carriage in a forwardly projected position relative to said casing, control means operable in a first mode to set said first drive means in said first condition, and a manually actuated cycle initiation control coupled to said control means operable when actuated when said control means is in said first mode to set said first drive means in said second condition.

4. Apparatus as defined in claim 3 comprising means in said control means operable when said control means is in said first mode and said first drive means is in said second condition for actuating said second drive means to drive in a first direction moving said plunger receiving means toward said syringe body receiving means.

5. Apparatus as defined in claim 4 further comprising means in said control means operable when said control means is in said first mode for setting said first drive means in said first condition when said plunger receiving means is driven into abutment with said body receiving means.

6. Apparatus as defined in claim 3 comprising means in said control means operable when said control means is in said first mode and said cycle initiation control is actuated to drive said second drive means in a direction retracting said plunger receiving means from said body receivinG means for a Predetermined period of time and to then reverse the direction of drive of said second drive means.

7. Apparatus as defined in claim 3 wherein said cycle initiation control is movable between a first neutral position and second actuated position, means biasing said control to said neutral position, first means in said control means operable when said control means is in said first mode for setting said first drive means in said second condition upon movement of said control from said neutral to said actuated position and maintaining said first drive means in said second condition upon subsequent return of said control to said neutral position, and second means in said control means operable when said control means is in said first mode for operating said second drive means in a direction retracting said plunger receiving means from said body receiving means while said control is held in said actuated position and to operate said second drive means in the opposite direction when said control is restored to said neutral position.

8. For use in operating a hypodermic syringe having a syringe body and a syringe plunger reciprocable within said syringe body; apparatus comprising a casing, a carriage mounted in said casing for reciprocation between a front and a rear end limit of movement relative to said casing, syringe body receiving means fixedly mounted on the forward end of said carriage, syringe plunger receiving means slidably mounted on said carriage for movement between a forward and a rearward end limit of movement relative to said carriage, a threaded drive element mounted on the rearward end of said carriage for free rotation about an axis parallel to the direction of movement of said plunger receiving means relative to said carriage at a fixed axial location relative to said carriage, a drive member mounted on said plunger receiving means and threadably engaged with said drive element whereby rotation of said drive element is operable to drive said plunger receiving means in movement relative to said carriage, an elongate drive cable fixedly secured at one end to said drive element in coaxial relationship therewith, first reversible drive means coupled to said cable for driving said cable in longitudinal movement to shift said carriage between said front and rear end limits of movement relative to said casing, and second reversible drive means coupled to said cable for driving said cable in rotation about its longitudinal axis to shift said plunger receiving means between said forward and rearward end limits of movement relative to said carriage.

9. Apparatus as defined in claim 8 further comprising control means responsive to movement of said syringe plunger receiving means into abutment with said syringe body receiving means for disengaging said second drive means from said cable.

10. Apparatus as defined in claim 8 further comprising means for disengaging said threaded member from said drive element when said plunger receiving means is at said rearward end limit of movement on said carriage.

11. Apparatus as defined in claim 8 wherein said first drive means comprises a pair of solenoids, lever means pivotally coupled between said solenoids and said cable operable to locate said cable at one longitudinal end limit of movement when one of said solenoids is energized and to locate said cable at an opposite longitudinal end limit of movement when the other of said solenoids is energized, and control means for selectively energizing said solenoids.

12. Apparatus as defined in claim 8 wherein said second drive means comprises a reversible electric motor, and coupling means coupling said motor to said cable for maintaining a rotary drive coupling between said motor and cable while accommodating axial displacement of said cable relative to said motor.

13. Apparatus as defined in claim 8 further comprising control means responsive to the arrival of said plunger receiving means at said forward end limit of movement for actuating said first drive means to drive said carriage to said rear end limit of movement.

14. Apparatus as defined in claim 13 wherein said control means comprises a first member rotatable by said second drive means, a second member threadably supported on said first member and rotatively coupled to said cable, coupling means operable to normally maintain said first and second members against rotation relative to each other and to accommodate relative rotation of said first and second members upon an increased resistance to rotation of said cable by the driving of said plunger receiving means against said body receiving means, and switch means actuable by a predetermined axial movement of said first and second elements relative to each other.