DE2204900A1 - Portable infusion device - Google Patents

Description

BERLIN 33 8 MUNICH

Auguste-Viktoria-Strasse 65 rj_ ι ι_ι AMORIIC f ^ LI UC Pienzenauer Strasse

Pat. Dr. Ruschke W. mg. HANÖ KUÖLMIVt Pat, lawyer Agular

Telephone: 0311 4 ⁹ ™ 21 Dipl.-Ing. HEINZ AG U LA R Telephone: 0811 / «0 | §4

■ PATENT LAWYERS

Bank account: ..

Bank for trade and industry bank account:

Deposit kasse 32 ... Dresdner Bank

Berlin 33 Munich

Teplitzer Strasse 42 OO Π / Q Γ \ Π Dep.-Kassel Leopoldstrasse

Account 32 7608 ZtUHvJUU Account : B9 515

Telegram address: Telegram address;

Quadrature Berlin Quadrature Munich

Munich, February 2, 1972

Sherwood _x Medical Industries Inc., I83I Olive Street, St. Louis, Missouri 63103, USA

Portable infusion device

The invention relates to a portable infusion device with an exchangeable piston lifter and an exchangeable two-way valve as a liquid displacement pump ₀

During typical blood transfusions and intravenous injections, a solution bottle is usually hung over a patient to allow fluid delivery through a replaceable venoclysis tube to a catheter inserted into the patient's vein due to its weight. The transport of the patient is difficult because the solution bottle always be placed over the patient's needs, so that an operator is required which holds the solution bottle _e Even if the patient is in a hospital, periodic control operations are required, which require time and personnel. Despite periodic checks, certain errors can occur

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remain disregarded due to a lack of suitable error notification " During an injection, for example, it is possible for a needle to move in a vein and into a Muscle invades.

The invention is based on the object of creating an infusion device that has safety circuits for influencing of the operation of a control circuit according to external and internal states.

This object is achieved according to the invention by a Control device for controlling the pump and for generating a control signal depending on a selected one Flow rate of the liquid, a scanning device for generating a control signal as a function the flow velocity generated by the pump, and a circuit for generating an error signal when by comparing the control signal and the control signal it is indicated that the generated flow rate is a predetermined value from the selected Flow velocity deviated

The infusion device according to the invention has a safety circuit which eliminates faulty states that would otherwise arise as a result of a failure of the pump control circuit itself could result «, an electrical analog signal the pump is compared with the actual operation of the pump, which is recorded by an external scanning device, assigned to the pump drive is displayed. If the pump has a pumping speed above that of the analog Circuit generated, a speed control

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switches off the pump. The analog circuit produces a safety range of acceptable speeds for each of a plurality of pumping rates, which are selectable under control of the control circuit _0, the safety circuit and the external Pumpenabtasteinrichtung use many existing in the device parts, so that in addition the safety with only a slight increase in the cost or . the number of components is increased.

In connection with further embodiments of the invention, a portable infusion device can thus be created, which has an exchangeable piston lifter and an exchangeable two-way valve as a displacement pump. Of the The piston lifter is moved back and forth by a two-directional DC motor that is battery-powered is. Various selectable pump speeds are achieved by controlling the width of bidirectional pulses, which are fed to the motor and maintained by controlling the motor back EMF during the pulse-free time Safety circuits protect against faulty states such as the passage of an air bubble Overpressure or too high a pumping speed, how they can be caused by the failure of a component.

An embodiment of the invention is explained below with reference to Figures 1 to 5. It shows:

1 shows a perspective view of an infusion device according to the invention,

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Fig. 2 in an exploded arrangement, the pump device, the pump for the sake of clarity on the opposite side of the pump housing is shown in Fig. 1,

Fig «, 3 a circuit diagram of the control circuit of the pumping device,

4 is a circuit diagram of a speed control circuit, which can be connected to the control circuit of FIG. 3, and

Fig. 5A to 5B, the course of k in the circuit of Figo stresses arising ₀

Fig. 1 shows a portable infusion device by means of which liquids, such as blood, can be pumped from a solution bottle 20 to a catheter 21 which is inserted into a patient's vein. The liquid transport is performed by a pumping device 24 which is supported by a frame 26, a bed of a patient is attached to a rail 28 _o The frame supports removably the solution bottle 20, which are arranged in any expedient height with respect to the patient can _O

The solution bottle 20 is of conventional construction and has a cap 30 with an air valve 31 and an outlet 32 for liquid transport. An interchangeable one Venoclysis tube 3 ^ connects the outlet 32 with an inlet 36 of a replaceable two-way valve 4o, which forms part of the pumping device 24.

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The pumping device 24 has, as a pumping chamber, a conventional exchangeable lifter 42 with a displaceable piston 44 which can be moved back and forth in order to move the liquid into
pump a hollow siphon tube connected to the two-way valve 40 having an outlet 46 connected by a venoclysis tube 50 to a conventional Y-connector 52 for introduction of medicament
is.

The output of the Y-connector 52 is through an additional exchangeable Venoclysis tube 54 to the
Catheter 21 connected.

The control circuit of the pump device 24, which is shown in detail in FIGS. 3 and 4, is accommodated as a whole in the housing of the pump device and can be supplied with energy either externally or internally.
During a return stroke, in which the hub piston 44 of
When the valve 40 is withdrawn, liquid can flow from the solution bottle 20 through the inlet 36 into the siphon tube. The valve in outlet 46 is closed at this time. During a forward stroke in which the piston is pushed towards valve 40, the
Inlet 36 closed and outlet 46 opened, so
that the solution through the venoclysis tubes 52 and 54 to
the catheter is pumped.

In Fig. 2, the new pumping device 24 is shown in an exploded arrangement. A sterile positive displacement pump is economical by using a common interchangeable jack 42 along with a single one replaceable valve 40 is formed. The lifter 42 has

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a seal attached to the piston kk , slidable in a tube 72 and having a single fluid opening which ends in a needle port Jk. The lifter has protruding gripping arms J6 held by the base plate of the pumping device 2k

The lifter k2 and the valve kO be releasably held by the housing to take it off after use for each patient and to be able to replace it with a new jack and a new valve which are sterilized _o A lower molded housing 90 has two upstanding arms 92, each of which has a slot 9 ^ which slidably receives one of the arms 76 of the lifter. The lower housing 90 also has an upstanding support 100 with a concave surface 102 to hold the valve 40 when connected to the lifter k2 and to make electrical contact with electrodes embedded in the valve. Two electrical sockets 106 in the surface 102 receive air bubble detector electrodes and a socket 108 (not shown in FIG. 2), which can be arranged separately from the housing 90 or cast in the same way into a part thereof, receives an overpressure detector electrode. The sockets 106 and 108 are connected by wires to the circuit shown in FIG. 3, which is housed in the hollow housing 90.

The mechanical drive of the piston kk consists of a two-directional direct current motor 120 with an armature shaft 121 and a gear 122 arranged in one piece thereon. The gear 122 meshes with an idle gear 126 which is rotatable about an idle shaft 128,

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which is attached to a pinion 130. The pinion 13O meshes with a drive gear 132 which is attached to a shaft of a screw spindle 134 _o A jack cylinder holder 14O has a holding head 142 which has an opening to slidably receive the head 45 of the piston 44 !, the holder i4o has a central Internally threaded bore for receiving the screw spindle 134 to cause the holder to act on the screw spindle as a drive nut

When the DC motor 120 is energized by a voltage of a certain polarity, the two-stage rotates Gear reduction gear the screw spindle 134, so that the holder 140 and the attached cylinder 44 make a forward stroke. The holder 14O has a Projection 150 with a permanent magnet, which is extends downward magnetically to a sealed forward travel limit switch 154 and a sealed Operate reverse stroke limit switches 152 mounted on a circuit board 156 that includes the The circuit of FIG. 3 contains the holder 14O is shown in FIG in the forward stroke direction until the protrusion is directly over the limit switch 154, at which point in time the circuit of FIG. 3, the polarity of the voltage of the DC motor 120 is reversed to rotate the shaft 121 in the reverse direction. The holder 14O and the cylinder 44 are now displaced in the longitudinal direction in a backward stroke until the projection 150 is directly above the limit switch 152 is at what time the The circuit of Fig. 3 again reverses the polarity of the voltage of the DC motor. Although preferably magnetic

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table-operated limit switches are used, a mechanical switch arrangement could also be provided, which is mechanically operated by the protrusion 150.

The limit switches 152 and 15 ^ together with the projection 150 also serve as a sensor device for determining the actual operation of the pump. Parts of the circuit in FIG. 3, which respond to the limit switches, are with connected to the speed control circuit of Fig. 4 to produce an input signal (at terminals A and B), which reflects the actual operation of the siphon pump.

The energy for the direct current motor 120 and the control circuit including the speed control circuit of FIG. K is supplied by a self-contained energy source, for example two direct voltage batteries 160 connected in series. The batteries 160 are expediently rechargeable, sealed nickel-cadmium batteries which enable the pumping device to receive energy either from an external AC voltage source or internally so that the device is completely portable. If the device is designed for portable use only, the batteries can be standard 1.5V batteries. The batteries I60 are received in a cylinder 162 which is formed in the lower housing 90 _# The electrical connection is via a contact spring 164 and to, if necessary, replace a contact on a cap I65, which is screwed into the wall of the cylinder 162, the batteries to be able to «,

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An upper housing I70 mates with lower housing 90 to enclose the drive assembly and batteries I60. Housing 170 has a window 172 through which markings on dial 174 can be observed to allow an operator to set different fluid pumping speeds Select". The markings on the dial 174 to give directly the pumping speed, for example, one liter of liquid per one, two or three, etc. _o hours at ₀ Another range of pump speeds can be provided in that the lifter 42 is replaced by a different capacity "The adjustment knob 174 may then be provided with other markings. A siphon fill switch I76 allows an operator to override the setting selected by adjustment knob 174 to rapidly reciprocate plunger 44 the first time siphon 42 is filled to remove air bubbles the switch 176 is actuated, the air bubble protection circuit is out of operation.

Control circuit

The control circuit for the pump arrangement is shown in detail in FIG. DC voltage lies between a DC voltage line 248 and a reference voltage source 250 or earth. If an external 115 V AC voltage is available, a plug 256 can be plugged into the external AC voltage source in order to apply the AC voltage to a step-down transformer 2§8. The transformer can be connected to line 248 via a full-wave rectifier and a socket. ^x The rechargeable

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Batteries 16O form a filter capacitor for the rectified AC voltage, reducing the ripple of the voltage on DC voltage line 248 is decreased. If necessary, an additional filter capacitor 262 can be provided «The step-down transformer 258 and the full-wave rectifier can be housed in the connector 256 and replaced by a two-wire Line to be connected to the socket on the pumping device. If the pumping device is independent of the external alternating voltage source should, the cable plug is removed from the socket on the pumping device, so that the previously charged Batteries 16O can supply the control circuit with energy.

The DC motor 120 is a shunt wound permanent magnet motor that rotates forwards or backwards when current flows from a connection 26o to a connection 262 or vice versa. The motor is driven by pulses that have a duty cycle of less than 100 io . During the pulse-free time, the motor 120 works as a generator or tachometer and the back EMF at the connections is measured and stored in order to control the duty cycle of the drive pulses.

An electronic reverse holder, consisting of the transistors 265 to 270 form a two-pole switch «Die Transistors 265 and 268 are brought into conduction synchronously to carry current in the forward direction to let the motor 120 fHessen. Transistors 266 and 267 are brought into conduction synchronously to form a reverse current path for motor 120 and to turn the motor backwards When the transistors

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and 268 are switched on, current flows from a + line via transistor 265 to terminal 26O of the Motor 120, through the motor 120 and the connection 262 to the transistor 268 and then to earth 250 ', when the front limit position is reached by the permanent magnet is reproduced on the projection 150, which actuates the switch 15 ^, switches an actuator to be described of the reversing switch, transistors 268 and 268 off and transistors 266 and 267 on. It A current then flows from the positive line 275 through the transistor 266 to the terminal 262 and then through motor 120, terminal 260 to transistor 267, and then to ground 250.

The the reversing switch operating means is composed of transistors 280 to 283 that act as a bistable feedback switch which helps to maintain a strong driving performance, which is necessary when a low supply voltage of, for example ₀ 3 V is supplied by the two batteries I60. Transistors 14 and 283 saturate each other when magnetic projection 150 actuates switch 152 at the end of the return stroke, thereby grounding the base of transistor 282. Transistors 282 and 281 saturate each other when magnetic projection 150 actuates switch 15 ^ actuated, thereby grounding the bals of transistor 283 at the end of the forward stroke.

When transistor 281 is saturated, current flows from its emitter to the base and through a resistor 290 to the base of transistor 267 to the inverting holder to be actuated At the same time, the voltage increases on the

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Collector of transistor 261 to the voltage on line 275 ^a n, so that transistors 265 and 269 receive a reverse voltage »The transistor 282 is also saturated at this point in time, so that a resistor 292, _{through the emitter-base path of transistor 266 t,} a line 293, the collector of transistor 282, current flows to earth 250. This actuates the other half of the reversing switch. Since the collector voltage of transistor 282 is almost at ground potential, no current flows through resistor 295 to transistors 270, 268. When the other stable state of the bistable switch is set by magnetic projection 150, transistors 280 and 283 operate in the same way , as described above, like the transistors 281 and 282 and control the transistors 265, 269 and 268, 270, as will be explained with reference to the air bubble detector circuit

During the forward stroke, the transistor 27O is driven through by pulses with a duty cycle of almost 25 %.

ten controlled »With a 'built-up circuit, the Control pulses for a minimum motor speed in a 16 ms interval with a duration of 4 ms, so that a 60 Hz frequency was generated «The pulse duty factor during the forward stroke is adjustable and is controlled by controlled by a forward stroke control.

The return stroke always occurs at maximum speed, because the transistors 266 and 267 fully saturated during the backward movement of the motor ₀ Since the DC voltage of the batteries 16O with age and operating slowly decreases, reaches a lower voltage

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via return stroke transistors 266 and 267 to the DC motor 120; this leads to a reduced speed of movement ο a compensation circuit for a change in battery voltage responds to the decreased voltage in order to reduce the pulse-free time required by the Forward stroke control is controlled to decrease and thus increasing the speed on the forward stroke and maintaining the selected pumping speed ©

The forward stroke control comprises transistors 300 to 3O4, which as an asymmetrical, astable multivibra-

Around
Tor are switched _o different pumping speeds can be selected, the setting knob IJk is connected to the contact arm 310 of a multiple switch 312. The contact arm 310 is connected via individual contacts 1 to 9 with one of the resistors 315, each of which has a different resistance value ₀ A main switch connects when actuated, contact arm 310 through siphon fill switch 176 to DC line 248. When adjusting knob 174 is rotated to contact arm 310 of switch 312 to contact a particular resistor 315, a connection from DC line 248 is made actuated switch 316 and non-actuated switch 376, contact arm 310 and selected resistor 315 to the emitter of transistor 3OO. The collector of the transistor 3OO through a capacitor 317 and the collector-emitter path of transistor 301 connected to ground 250, the duty ratio of the given to the transistor 270 pulses is determined by the capacitance of the capacitor 317 »the selected value of the resistor 315 and the voltage at the Base of transistor 300

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(the speed feedback circuit, as later is explained) certain

The pulse duration of the duty cycle is determined by the time period in which the transistors 301 and 303 is saturated and transistors 302 and 304 are blocked sindo The transistor 3OO works as a controlled current source, which discharges capacitor 317 in time, in he would keep the transistor 3O4 blocked If the transistor 301 turns on, transistor 303 is through the one from its base through a resistor 320 and the conductive transistor 3OI to earth 250 current flowing switched on. The transistor 303 controls the transistor 27O of the device for actuating the reversing switch through a resistor 322. Thus, the pulse duration of the duty cycle, which the forward stroke of the Motor controls, determined by the saturation of transistor 303 *

The pulse-free time of the duty cycle is controlled by the saturation of the transistor JOk , at which time the transistors 301 and 303 are blocked. This pulse-free time is determined by the capacitance value of a capacitor 325 »the voltage to which the capacitor was able to charge during the previous pulse duration and the resistance values of two resistors 327 and 328 connected in series. The permissible voltage to which the capacitor 325 can be charged is set by the compensation circuit for the change in battery voltage.

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The forward stroke control circuit operates as follows: It is assumed that transistor 30I has just been turned on and capacitor 317 is fully charged and capacitor 325 is fully discharged. When transistor 301 is saturated, the negative terminal of capacitor 317 has one negative voltage equal to the supply voltage "For this example it is assumed that the supply voltage of the batteries I60 is maximum or _{c is} 3 V" A current now flows from the +3 V PoI via the switches 316, I76 and 310, the resistor 315 and the transistor 300 which discharges capacitor 317 ₀ If the negative terminal of the capacitor 317 Vt reaches 2 V (the base-emitter voltage drop of the transistors 302 and 3O4) * the transistors are turned on 302 and 3O4, turning off the transistor 301 and recharge the capacitor 317 to provide voltage through a resistor 330. Capacitor 325 discharges through series resistors 327 and 328 until the base-emitter voltage of transistor 301 is reached, at which point transistor 301 turns on and the cycle repeats.

During the forward stroke, the pulse delivered to the DC motor at the maximum infusion rate, selected by switch 310, one such a duration that there is a 25 $ pulse-free time. Due to the mechanical inertia, the motor continues to rotate and generates a back EMF proportional to the speed of rotation of the anchor. This voltage is supplied by a speed feedback circuit determined and stored to control the transistor 3OO and the duration

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of the pulses to compensate for changes in load. It can therefore be different liquids and Jacks can be used without significantly affecting the calibration of the adjusting knob 17 ^.

During the forward stroke, transistor 265 is switched on and connects terminal 260 to line 275 carrying the supply voltage. During the pulse-free part of the forward stroke, transistor 270 is switched off, blocks transistor 268 and separates earth 250 from motor terminal 262. The opposite -EMK at the motor connection is now coupled via a resistor 335 and two series-connected diodes 336 and 337 to a capacitor 3 ^ 0 connected to earth 250. The capacitor 3 ^ 0 discharges to a voltage that is the sum of the supply voltage and the voltage generated by the motor is _o

During the pulse duration of the forward stroke control is transistor 270 conducts and controls the transistor 268 into the conductive state and thus places the motor connection 262 almost at ground potential, whereby the Diodes 336 and 337 are blocked. The tension on that Capacitor 3 ^ 0 is now used to provide the base voltage of transistor 300 and generate a pulse duration proportional to the voltage of the capacitor. A resistor 3 ^ 2 allows the capacitor to turn 3 ^ 0 discharges slowly. Since the voltage at the emitter of transistor 300 in relation to the supply voltage stands, the current through the transistor depends only on the back EMF of the DC motor, whereby the effect of supply voltage changes is eliminated.

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The control circuit also includes a number of special safety circuits which are described below In addition, the control circuit has a compensation circuit for battery voltage changes with transistors 370 and 371 on.

Bubble detector

The bubble detector circuit includes electrodes 212 and transistors 350 and 351. If liquids with a conductivity corresponding to a salt content of 0.001 ia or more are present between the electrodes 212, which are spaced 6.35 mm apart, the resistance between them is approximately 200 kiloohms or less Emitter-base path of transistor 350, a resistor 352 of 10 kilo ohms, one electrode 212 and through the liquid to the other electrode 212 to charge a capacitor 353 with one microfarad «. The capacitor 353 is discharged by the forward stroke circuit through a diode 355. The time constants are chosen so that the capacitor 353 is not charged to more than 0.1 V if the forward stroke control circuit does not fail. When the forward stroke control circuit fails such that the forward stroke at full ^ fersorgungsspannung would be performed on the engine, the capacitor 353 is the supply voltage ^au f charged and turns transistor 350 off. This stops operation. The patient is thus protected against excessive infusion speeds that could be caused by the failure of critical parts of the circuit. Additional protection is provided by the speed control circuit to be described.

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The current that charges the capacitor 353 causes a current of at least two hundred times its size to flow from the supply line 275 through the emitter-collector path of the transistor 350 and a resistor 357 into the base of the transistor 351. As a result, the transistor 351 is forward-biased so that a connection to earth is established via the transistor 351 and a resistor 358 connected to the base of the transistor 269, so that a control current for the transistors 269 and 265 flows when the transistors 269 and 265 can be turned on by the circuit for operating the reversing switch. When an air bubble occurs between electrodes 212, the current is interrupted and transistor 351 is cut off. Thereby, the motor stops 120 at its forward at ₀ The Heberfüllschalter 176 in the Vorwärtshubsteuerkreis is used to this interruption to override during filling of the lifter.

The combination of the bubble detector circuit and the placement of electrodes 212 and 21 ^ in the two-way valve ko results in a safety device that detects air leaks caused by a defect in the pump assembly, the air detector control circuit acts as a safety device to prevent accidental passage of an air bubble and also for automatic shutdown of the pumping device when all of the liquid in the solution container has been used up. At the end of the liquid supply, air is introduced into the solution bottle and pumped to valve 4o.

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When the air reaches the point where the two sense electrodes are arranged 212, the current is interrupted and the engine operation is stopped, so that the pumping device is switched off ₀

Overpressure detector

This circuit is formed by gate circuits 400, 401 and a transistor 372 produced using integrated circuit technology. The gate circuits 400 and 401 form a bistable multivibrator ₀ During normal operation (no overpressure state), the gate circuit 401 is open and the transistor 372 is blocked. To ensure this state, a capacitor 405 is provided, which is five times as large as a capacitor 406. When the control circuit is energized, the capacitor 405 holds one input of the gate circuit 4OO at a low voltage long enough to bring the multivibrator into the state in which the gate circuit 401 is saturated and the gate circuit 4OO is blocked.

When liquid reaches electrodes 220, indicating an overpressure condition, a connection is established from one input of the gate circuit 400 to the supply voltage line 275 through the transistor 350 and the electrode 212, which are connected through a resistor 352 whose base is connected, produced, whereby the gate circuit 4OO is saturated and the gate circuit 401 is blocked will. This turns on transistor 372, which blocks transistor 351, which in turn opens the bias path of transistors 269 and 265. Through this the pumping device is stopped on the forward stroke »Die

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22Q4900

Overpressure detector circuit can be reset by turning the control circuit off and on becomes, whereby the capacitor 405 saturates the gate circuit again.

Bubble and overpressure indicator

This circuit consists of transistors 310 and 411 which _{control the energization of a visual indicator Z 0} B _{0 of} a light emitting diode 4i3. Because of the lower energy consumption, a light-emitting diode is expediently used instead of an incandescent lamp. When an air bubble or overpressure condition is detected by the circuitry previously described, transistor 351 is turned off. In turn off the transistor 410, whereby between a resistor 415 and a diode 4i6, the 413 and the base of the transistor are connected in series 411 between the anode of the diode compound prepared is made floating ₀ The transistor 411 is thus in the forward direction biased and creates a current path for diode 413 through resistor 420 and the collector-emitter path of the conductive transistor to ground 250 _o Diode 413 is positioned near a cover lens mounted in housing 17O to provide a visual indication of any detection an interruption of the circuit caused by an air bubble or an overpressure state »

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Speed control circuit

This circuit, shown in Figure 4, is connected to the circuit of Figure 3 by appropriately numbered and labeled connections which are indicated in circles "The Speed Control Circuit
generates an electrical analog signal that represents the lifter drive with which the scanned processes are carried out
the actual jack drive can be compared. The scanned processes are expediently determined by using the limit switches 152 and 154 which are actuated by the permanent magnet in the projection 150 (FIG. 2). If for any
Reason the actual jack drive its forward stroke in a predetermined shorter time than the analog one
Lifter drive performs the speed control circuit ends the forward stroke as _o by activating
part of the existing overpressure detector.

Failures can cause the actual lift drive has a too large pumping speed, for example _o
a speed that is much greater than that
is selected by the adjustment knob 174. For example, certain transistors can be used in the circuit
3 may fail or the speed switch 312 may cause an open circuit »

The circuit will now be considered in detail. The collectors of transistors 280 and 282 of the means for operating the reversing switch (Fig. 3) are
connected via a connection A to a 47 microfarad capacitor 500 (FIG. 4) and via a 3.3 kiloohm resistor 502 to the base of an NPN transistor 5θ4

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A 10 kiloohm resistor 506 connects the base and the emitter of transistor 5O4. The transistor serves to discharge a 470 microfarad capacitor 510 through a 10 ohm resistor 512 in series with the Collector and the emitter of transistor 5O4 is connected.

The capacitor 510 is part of a time constant selector, which is used to generate an analog voltage that can be used to determine whether the device is working properly. The capacitor is charged via a constant current source that consists of a PNP transistor 516 whose collector directly to the capacitor 510, its emitter with a common line 518 and its base with the connection point of a voltage divider between a 220 ohm resistor 520 and three series-connected semiconductor diodes 522 are connected. Of the Voltage divider is across line 248 between a source of positive voltage and ground 250 switched.

The charging speed of the capacitor 510 depends on the position of the speed switch 312 (Fig. 3) away. Each contact 1 to 9 of the speed switch is connected to the common line 518 via a corresponding diode 530 and a resistor 532 Each resistor 532 has a different resistance value, to generate a different time constant for the analog circuit with capacitor 510 that is so are chosen so that the analog voltage rise across the capacitor 510 reaches +1.2 V when the lifter drive

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has completed nearly $ 60 of its forward stroke. at In a practical infusion device, the values of the resistors 532 were 1, corresponding to the contacts up to 9 6.2 kilo ohms, 20 kilo ohms, 33 kilo ohms, 47 kilo ohms, 62 kiloohms, 75 kiloohms, 91 kiloohms, 100 kiloohms and 120 kiloohms

The analog voltage rise across capacitor 510 is over a diode 540 on the base of an NPN transistor 542 The emitter of transistor 542 is direct connected to earth 250 and the collector is over a 10 kiloohm resistor 544 to the + V line 248 and also connected to the base of an NPN transistor 550. The collector of transistor 550 is across the Connection E is connected to an input of the gate circuit 401 (FIG. 3). The emitter of transistor 550 is connected directly to the collector of a second NPN transistor 554, the emitter of which is connected directly to ground 250 is ο The base and emitter of this are connected by a 10 kiloohm resistor 556 to bias Control of transistor 554 is also via a 10 kiloohm resistor 56O and a base Connection B with the collectors connected in series of the transistors 281 and 283 of the device for actuating the reversing switch (Figo 3).

The operation of the speed control circuit of Fig. 4 will now be explained with reference to the waveforms shown in Figs. 5A to 5E. At the end of the return stroke of the actual lift drive the holder is 14O (Fig. 2) in its rear position in which the permanent magnet on the projection 150 actuates the limit switch 152 ₀

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This external sensing of the actual piston position is independent of the electric drive control and thus generates for the speed control circuit a signal of the actual position. If the switch 152 is operated at the end of the return stroke, the base of transistor 282 (Fig. 3) is grounded. As previously explained, this turns the transistors 280 and 283 saturated, so a positive Voltage at terminal A (Fig. 5A) and a negative (or earth) is generated at connection B (Fig. 5B).

This positive voltage, appearing at time 570 (FIG. 5A), drives transistor 504 into saturation, thereby discharging capacitor 510 to near 0V. (Fig. 5C) p Since the connection A is connected to the base of the transistor 504 via a capacitor 500, the capacitor 500 is temporarily charged to the positive voltage and removes the forward bias of the transistor 504. “The capacitor 510 now charges almost linearly at a rate determined by the time constant resistor 532 selected by the rate switch. The values of the resistors 532 are chosen so that the analog voltage rise (FIG is when the actual jack drive has completed nearly $ 60> of its forward stroke. The +1.2 V voltage biases the diode 54O and the base-emitter path of the transistor 542 in the forward direction, so that the voltage at the base of the transistor 550 is reduced to less than 0.1 V (FIG. 5D.

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To the end point 580 of the actual forward stroke, as it is scanned by the closing of the switch Λ $ Κ, the voltages return to the terminals A and B, the polarity at (Figo 5A and 5B) _O The positive voltage at the transistor 5 $ k biases these in the forward direction. However, the transistor 550 is still blocked by the output voltage (FIG. 5D) of the transistor 5 ^ 2, so that the connection between the connection E and the earth 250 is interrupted (FIG. 5E). At the end of the return stroke, the switch 152 is actuated again, so that the cycle described above is repeated.

If for some reason the jack drive is operating too fast such that the forward stroke is completed before the voltage rise on capacitor 510 reaches the +1.2 V level 572, then another operation results. Assuming that the actual return stroke begins at time 59O, that is to say well before the selected time, the voltage at connection B increases positively and biases transistor 55 ^ in the forward direction. At the same time, the voltage at the base of transistor 550 (FIG. 5D) is positive and brings transistor 550 into the conductive state. Since both transistors 550 and 55 ^ are forward-biased, the voltage at terminal E drops to ground potential (FIG. 5E ), so that an interruption or Error signal is generated. As Fig. 3 shows, the error signal, for example, the gate 401 switches _o mass, at the input to the bistable multivibrator, wherein said gate circuit UOI and the transistors 372 and 351 locked "As previously for the pressure detector

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220A900

has been explained, this opens the bias path for transistors 269 and 265 so that the lifter drive is stopped on the forward stroke. By different choices of the time constant values of the transistors 532 (Figo ^) and the value of the capacitor 510, the safety range that allows continuous normal operation, here 60 % of the selected speed, can be changed in the desired manner. This range also allows for changes in the consistency of the liquid being pumped and other factors including calibration errors.

In order to increase reliability, the terminals for connecting the components used in the circuits of Figs. 3 and k can be duplicated, ζ.Β »by being formed on both sides of a printed circuit board; other redundancy techniques can also be used. In certain applications, the number of individual circuits described can be smaller or different combinations of these can be used «

209834/0826

Claims (8)

I uj 'OB' -! SiP- avinov ζνϊβη -suKid '2, F * h «070 Claims Portable infusion device with a replaceable Piston lifter and a replaceable two-way valve as a liquid displacement pump, characterized by a control device for controlling the pump and for generating a control signal as a function of a selected flow rate of the liquid, a scanning device for generating a control signal depending on the flow rate generated by the pump, and a circuit for generating an error signal, if by comparing the control signal and the control signal it is indicated that the generated flow rate is a predetermined value from the selected Flow velocity deviates. 2. Infusion device according to claim 1, characterized in that that the pump (24) liquid lines (34,54) for connecting a liquid source (20) with an outlet, a pump chamber (42) and a drive with a piston (44) in the chamber in dependence is displaceable by the controller in order to pump liquid through the lines, and that the scanning device, the control signal as a function of a predetermined movement of the drive generated * 209834/0826 3. Infusion device according to claim 2, characterized in that that the drive has a cyclically moved connecting device (i4o) and that the scanning device has a device (152, 154) responsive to the position of the connecting device, to scan the cyclically repeating positions of the connecting device (i4o) and enter generate cyclically recurring control signal. 4. Infusion device according to claim 3 »characterized in that that the control device provides a fixed-value control signal for a specific selected flow rate generates the error signal circuit to generate a time constant circuit (510 * 532) for generating a time-changing signal with a value different from that of the fixed control signal and its duration depends, has, and by a device for comparing the signal changing over time with the cyclically recurring control signal to determine the predetermined speed deviation. 5 «infusion device according to claim 4, characterized in that that the time constant circuit has a capacitor (510) and one with the device for generating the Has fixed-value control signal connected charging path, and that the comparison device has a gate circuit (4O1) for discharging the capacitor (510) for each of the cyclically recurring control signals . 209834/0826 6. Infusion device according to claim 3 »characterized in that that the scanner switch (152.15 * 0 which are actuated with each recurring cycle of the connection device (i4o), 7. Infusion device according to claim 6, characterized in that that the switches (152,154) have a magnetically actuatable contact, which its state at Presence of a magnetic field changes, and that the connecting device (i4o) generates a magnetic field Means (150) for actuating the contact having. 8. Infusion device according to claim 1, characterized in that the control device has a selector switch (312) for the selection of different pumping speeds and a motor (120) responsive to the selector switch for controlling the cyclic drive speed of the pump, and that the error signal circuit is responsive to the selector switch (312) Device for generating a control signal with a different value for each selectable speed and means for comparing the control signals with different values with the control signal having" 9. Infusion device according to claim 8, characterized in that that the comparison device generates an error signal, when the flow rate generated by the motor (12O) exceeds the selected flow rate by a predetermined range, as well as has a safety device that responds to the error signal to switch off the engine 209834/0826