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United States Patent  [li] Patent Number: 4,840,620
Kobayashi et al.  Date of Patent: Jun. 20, 1989
U.S. Patent Jun. 20,1989 Sheet 2 of 2 4,840,620
 PORTABLE PUMP FOR INFUSING MEDICINE INTO A LIVING BODY
 Inventors: Susumu Kobayashi; Kazumasa Satoh, both of Fujinomiya, Japan
 Assignee: Terumo Corporation, Tokyo, Japan
 Appl. No.: 33,772
 Filed: Apr. 3,1987
 Foreign Application Priority Data
Apr. 7, 1986 [JP] Japan 61-78288
 Int.Cl.4 A61M5/00
 U.S. Q 604/246; 604/153;
 Field of Search 604/123, 153-155,
604/131, 246, 251, 253, 255
 References Cited
U.S. PATENT DOCUMENTS
4,217,993 8/1980 Jess et al 604/123
4,256,437 3/1981 Brown 604/123
4,261,360 4/1981 Perez 604/123
4,496,346 1/1985 Mosteller 604/123
4,642,098 2/1987 Lundquist 604/123
4,710,166 12/1987 Thompson et al 604/123
Primary Examiner—John D. Yasko
Assistant Examiner—Gene B. Kartchner
Attorney, Agent, or Firm—Staas & Halsey
A portable infusion pump for delivering medicine to a living body has a roller pump for infusing solutions by use of a motor, a driving circuit for driving the motor in response to a control signal, and a flow rate control for generating the control signal. The flow rate control includes a manual operating unit for manually setting a value of a speed of the motor, a speed setting unit for generating a digital signal associated with the value set by the manual operating unit, and a control signal output unit for generating the control signal associated with the digital signal delivered from the speed setting unit. Accordingly, the flow rate thus set clearly corresponds to an actual flow rate, thus facilitating the control of the liquid flow rate.
5 Claims, 2 Drawing Sheets
PORTABLE PUMP FOR INFUSING MEDICINE
INTO A LIVING BODY
BACKGROUND OF THE INVENTION 5
1. Field of the Invention
The present invention relates to a portable infusion pump, and in particular, to a portable infusion pump for supplying medicine such as a liquid having a high calo- 1Q ric value to a living body, for example.
2. Description of the Prior Art
A portable infusion pump which can be carried, for example, on a body of a patient and which transports medicine is required to be of a small size and of a light 15 weight. Consequently, control circuitry for controlling a motor of the pump is advantageously configured in a simple structure to the extent possible.
A direct current (DC) motor is suitable for a smallsized apparatus; furthermore, since a DC motor can be 20 easily controlled in motor speed, it is particularly advantageous for a portable infusion pump which needs to control the flow rate of a liquid to be supplied. In general, conventional control apparatus for controlling the flow rate of liquid uses a variable resistor to control the 25 motor speed. However, the adjusting precision of such a variable resistor is relatively coarse and there does not exist a clear one-to-one correspondence between the position of an adjusting slider and the motor speed, which leads to an insufficient reproducibility. Namely, 30 the correspondence cannot be fixedly determined between the flow rate, or a flowing volume per unit period of time, of the liquid transported by the pump and the position of the slider of the variable resistor, and hence a satisfactory reproducibility cannot be attained. 35
As a result, in the conventional apparatus for controlling the liquid flow rate, the scale marks of the control for adjusting the flow rate indicate only approximated targets, namely, it is difficult to indicate a digit representative of an appropriate setting value.
Moreover, when using a variable resistor, there may not exist a linear relationship between the positions of the adjusting slider and the speed of the motor. In order to design scale marks of the control for adjusting the 45 flow rate to represent directly the flow rate, the scale marks are not distributed with a uniform interval between adjacent ones, which leads to a disadvantage that the adjusting operation cannot be easily achieved.
As well known, as a compact infusion pump for medi- Jq cine to be used to supply medicine to an organism, there have been used a roller pump and a finger pump having a tube not exposed to the external environment thereof so as to prevent a chance of an infection. Since the pump is required to be of a" small size, it is difficult to 55 install in such an infusion pump an apparatus for actually measuring the flow rate.
As can be clear from this situation, in a case where such a compact infusion pump is used, it has been considerably difficult to measure the flow rate of nutritional go solutions and other intravenous solutions actually flowing through the liquid transporting tube and further to obtain a setting value of the flow rate.
SUMMARY OF THE INVENTION 65
It is therefore an object of the present invention to provide a liquid transporting pump for appropriately indicating a setting value of the flow rate of a liquid to
be transported, thereby solving the problem of the prior art technology.
An infusion pump of the present invention includes pump means having a pump for transporting a liquid, driving means for driving the motor in response to a control signal, and flow rate controlling means for generating the control signal. The flow rate controlling means comprises manual operating means for manually setting a value of the speed of the motor, speed setting means for generating a digital signal associated with the value set by the manual operating means, and control signal output means of generating a control signal corresponding to the digital signal delivered from the speed setting means to deliver the control signal to the driving means.
According to an aspect of the present invention, the manual operating means includes an indication for indicating a flow rate of liquid infusion associated with the speed of the motor.
According to another aspect of the present invention, the speed setting means includes DIP code switch means for generating a digital signal.
According to still another aspect of the present invention, the pump means comprises a roller pump, which is connected to the motor.
According to a further aspect of the present invention, the control signal output means includes an operational amplifier having an input adapted for receiving the digital signal generated by DIP code switch means and another input to which a reference voltage is supplied.
BRIEF DESCRIPTION OF THE DRAWINGS
The objects and features of the present invention will become more apparent from the consideration of the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic block diagram illustrating an embodiment in which an infusion pump of the present invention is applied to a portable infusion pump to be carried on a body of a patient, and
FIG. 2 is a schematic circuit diagram depicting a specific example of a circuit configuration of the embodiment shown in FIG. 1.
DESCRIPTION OF THE PREFERRED
Referring now to FIG. 1, in this embodiment, the present invention is applied to a portable liquid infusion pump which can be carried, for example, on a body of a patient and which delivers medicine such as hyperalimentation solutions to the living body. At an intermediate point of a flexible tube 10 for transporting the medicine from a source of the medicine to be transported, there is disposed a roller pump 12 in this embodiment. When a rotor 14 turns in the direction of an arrow A, the position pressing the tube 10 advances, which transports the medicine in the direction of an arrow B so as to be injected in the living body at a slow rate. In place of such a roller pump 12, a finger pump may be used.
In this emoodiment, a shaft 16 of the rotor 14 is mechanically coupled to a shaft 20 imparting torque of a DC motor 18 as conceptually indicated with a broken line and hence is rotated in the direction of an arrow C when the motor 18 is subjected to a driving control by a motor control circuit 30. A flow rate, and hence the speed of the motor 18 can be set to a desired value by the motor control circuit 30.