JPH09182789A - Estimation of flow rate and liquid transport pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the specified flow rate of a liquid to be transported when a liquid transport tube of any other type than specified is used on a liquid transport pump actuated to transport the liquid by the peristaltic action of a finger mechanism with high vibration resistance. SOLUTION: The outer diameter of a liquid transport tube is measured in such a state that the tube is mounted on a liquid transport pump (step S1), and the wall thickness of the liquid transport tube is measured by collapsing the inner diameter part of the liquid transport tube until the both sides of the inner diameter part come into contact with each other (step S2). In addition, the flow rate of the liquid to be transported by the peristaltic action of a finger mechanism when the tube is mounted on the pump is calculated by estimation by substituting the outer diameter and the wall thickness obtained by measurement respectively with the transfer function of the finger mechanism for the peristaltic action (steps S4, 5, 6). Further, the results of the calculation by estimation are output (step S7).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate predicting method and an infusion pump, and in particular, an infusion tube having an arbitrary outer diameter and an arbitrary wall thickness is used, and a peristaltic structure including a plurality of fingers arranged in parallel in the infusion pump ( Peristalsis) The present invention relates to flow rate prediction when a drug solution or the like is delivered by exercise.

[0002]

2. Description of the Related Art An infusion pump having a finger mechanism for delivering a liquid by a peristaltic movement acting in the longitudinal direction of the infusion tube is used to deliver the contents or the content liquid filled in the infusion tube.

For example, European Published Patent No. 0426273
According to the device disclosed in "Pumping device" of B1,
A state in which closing means for closing the infusion tube are respectively provided on the upstream side and the downstream side of the infusion tube, and a finger member having a plurality of fingers is provided between them, and the infusion tube is held by the finger member. There is disclosed a technique for performing infusion by reciprocally driving the infusion tube and pressing the infusion tube from the outer peripheral surface side to substantially completely crush it.

By the way, the flow rate of the liquid to be delivered by an infusion pump having a finger mechanism for delivering the liquid by this type of peristaltic movement varies greatly depending on the finger moving speed, the inner diameter of the infusion tube, and the wall thickness. A dedicated infusion set for open loop control was used by using this infusion tube. Here, the open loop control refers to a control method different from a feedback control method that automatically adjusts the drip amount of the infusion chamber based on the detection of the drip amount by the drip sensor.

On the other hand, when it is necessary to ensure the accuracy of the liquid delivery flow rate, the feedback control system using the drip cylinder sensor as described above is unavoidable.

[0006]

However, the feedback control system using the above-mentioned drip tube sensor has the drawback that the drip tube probe and others are weak against vibration, and it is necessary to set the drip tube in conformity with each drip tube. It has the drawback of being very troublesome.

On the other hand, a dedicated infusion set using a designated infusion tube is excellent in vibration resistance, but since it is necessary to use a part such as a drip tube probe that may cause a measurement error due to vibration, it is necessary to use other than the designated infusion tube. However, there is a problem in that the prescribed flow rate cannot be guaranteed if the liquid is used incorrectly, or if an infusion tube other than the one specified by force is used.

Therefore, the present invention has been made in view of the above problems, and in an infusion pump for delivering a medicinal solution, an infusate or the like by peristaltic movement of a finger mechanism having excellent vibration resistance, an infusion other than specified. It is an object of the present invention to provide a flow rate prediction method and an infusion pump that can guarantee a predetermined liquid delivery flow rate when a tube is used.

[0009]

In order to solve the above-mentioned problems and to achieve the object, according to the present invention, a peristaltic movement by a plurality of fingers juxtaposed to an infusion pump is used by using an infusion tube. A method of predicting a flow rate when sending a liquid, wherein the outer diameter is measured with the infusion tube attached to the infusion pump, and the inner diameter of the infusion tube is attached with the infusion tube attached to the infusion pump. Measure the thickness by crushing until the parts come into contact,
Substituting the outer diameter and the wall thickness obtained by the respective measurements into the transfer function of the finger mechanism for the peristaltic movement, the liquid delivery amount by the peristaltic movement with the infusion tube attached. Is calculated and the result of the prediction calculation is output.

Further, the infusion pump is an infusion pump for delivering liquid by a peristaltic motion by a plurality of fingers arranged in parallel using the infusion tube, and the outer diameter in the state where the infusion tube is attached. An outer diameter measuring means for measuring the wall thickness, a wall thickness measuring means for measuring the wall thickness by crushing until the inner diameter portion of the liquid transfusing tube comes into contact with the liquid transfusing tube attached, and for the peristaltic movement And a control means connected to the outer diameter measuring means and the wall thickness measuring means for storing the movement function of the finger mechanism in advance by the peristaltic movement with the infusion tube attached. It is characterized in that the liquid feed amount is calculated by the control means and the liquid is fed based on the result of the calculation.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 (a) is a plan view showing the main part of the infusion pump, and FIG. 1 (b) is (a).
2 is a cross-sectional view taken along line XX of FIG. 3C, and FIG. 6C is a cross-sectional view taken along line YY of FIG.

In the figure, the drive unit for the peristaltic movement of the infusion pump is fixed in the base 3 of the pump, and the rotational force of a drive motor (not shown) is transmitted to the cam shaft and fixed to the cam shaft. The cam that contacts the finger 2 converts the rotational movement of the cam into the linear movement of the finger 2.

Each finger 2 is connected to a receiving plate (not shown) which is fixed to an openable / closable door 5 via an elastic member such as a coil spring, a leaf spring, or a spring, and the infusion tube 1 shown in the figure.
While the fingers 2 are held in a sandwiched state, a plurality of fingers 2 are juxtaposed in a range L in the figure to perform a predetermined peristaltic movement, so that the flexible infusion tube 1 is pressed in order as described later. The liquid is sent by closing it.

In FIG. 1B, the door 5 is provided with an outer diameter measuring means 4. The device 4 is provided on the door 5, is rotatably provided at a fulcrum 7 of the door 5, and is provided on an arm 6 which is always biased in a closing direction when the door 5 is closed as shown in the drawing. On the other hand, the outer peripheral portion of the liquid transfusing tube 1 is brought into contact with the arm 6 to open the arm 6 in the arrow direction. The arm 6 is provided with an actuator of an operating transformer type linear gauge 8 fixed to the door 5, and outputs an output proportional to the moving amount to the control unit 10.
Outer diameter D (2R + 2)
d) can be measured.

Further, in FIG. 1 (c), the wall thickness measuring means 15 for measuring the wall thickness 2d by crushing the inner diameter portions of the liquid transfusing tube 1 until the inner diameter portions of the liquid transfusing tube 1 substantially abut each other as illustrated.
Can use the finger mechanism on the most downstream side of the finger mechanisms 2 arranged side by side, or can be provided independently, but it can be cheaper by using the finger mechanism on the most downstream side. Can be configured. For this,
By providing the elastic body 12 between the fingers 2, it is possible to move the finger mechanism above the bottom dead center by the cam mechanism. And this finger 2 has an operating transformer type linear gauge 8
Is provided so that an output proportional to the movement amount is sent to the control unit 10 so that the wall thickness d can be measured.

FIG. 1D is a block diagram of the infusion pump of the present application. In the figure, the moving function f (x) at an arbitrary position x of the finger mechanism 2 is stored in the control unit 10, and the function obtained from the cam offset amount of the mechanism and the range L is input and further displayed. The part 11 is connected. The function f (x) mentioned here represents the position of the tip 2a of the finger of the finger mechanism 2. (See FIG. 2A) Next, in the measurement principle diagram of FIG. 2, the finger mechanism is moved by one cycle (cycle) in the range L as shown in FIG. Each finger 2 sequentially presses the infusion tube 1 of FIG. At location A, backflow is prevented by almost completely crushing the infusion tube 1 as shown in the sectional view of (b). Further, at the position B, the finger 2 moves to a position almost completely away from the tube 1 and becomes a circular shape as shown in (c), and the cross-sectional area S of the inner diameter is obtained from πR2 (half-angle 2 indicates a power). .

On the other hand, at x, which is an arbitrary position,
In (d), assuming that the tube is crushed by the fingers 2 to have a shape formed by parallel sides and arcs as shown in the figure, the internal area of the parallel side portions is obtained from 2ra, and Since the internal area is obtained from πr2 (half-angle 2 indicates a power), the cross-sectional area S = πr2 + 2ra is obtained.

The above-mentioned a dimension is (2πR-2πr)
/ 2, so by substituting this, S = 2πRr-πr2
Get.

On the other hand, from 2r + 2d = f (x), r is f
(X) / 2-d, so substitute this

[0020]

(Equation 4)

The finger 2 which is one cycle of the finger mechanism 2 is obtained by using (x) as a parameter obtained from the equation 4.
Discharge amount (QL) for 1 to 2n (L)

[0022]

(Equation 5)

From the equation 5, L is vt (v is the moving speed of the finger, that is, each tip 2a of the fingers 21 to 2n.
Is the speed of moving in the l direction in order to reach the position of bottom dead center 2a1, and t is time), L = vt, so the flow rate per unit time (Q) is

[0024]

(Equation 6)

Prediction calculation can be performed from the equation (6).
Here, as stroke D0 (see FIG. 2 (e)) which is the width between the top dead center 2a1 and the bottom dead center 2a0, f (x) = 2 (R
+ D) -D0 + D0sinπx / L.
Here, x = 0 → D = 0; x = L / 2 → D = D0; x =
L → D = 0; D = D 0 dsinπx / L The result is displayed.

FIG. 3 is a flow chart summarizing the above processing. In this figure, when the power of the device is turned on and preparation is completed, an infusion tube having an arbitrary unknown outer diameter and wall thickness is loaded into the device. The door is set and the door is closed (step S1). After that, the outer diameter is measured and input to the control unit with the infusion tube attached in the outer diameter measuring device. After that, the process proceeds to step S3, and the finger mechanism is operated to crush it until the inner diameter portion of the infusion tube comes into contact, and the wall thickness is measured. Since f (vt) is an invariant function, if the finger bottom dead center described later is to be controlled, it is necessary to set f (x) by calculation, but no input step is required. By substituting the outer diameter and the wall thickness, the cross-sectional area S at an arbitrary position (x) by the peristaltic movement with the infusion tube attached is obtained from "Equation 4" (step S5).

Subsequent to this, in step S5, the discharge amount (QL) is obtained from "Equation 5". In addition, after obtaining the discharge amount (QL) from Equation 5 in this way, the process proceeds to step S7, the infusion rate of the flow rate (Q) per unit time is calculated from "Equation 6", displayed, and the processing ends. .

Since the flow rate can be predicted and displayed as described above, an arbitrary infusion tube can be used by appropriately setting the operation time (infusion rate control) based on the display result.

In the actual transfusion tube, even if the transfusion tube is manufactured by the same manufacturing method, a tolerance that varies in manufacturing is added to the wall thickness. Other than that, if each finger is driven so that the infusion tube is not completely crushed until the inner diameter of the tube becomes zero, the relationship between the crushed amount of the tube outer diameter and the discharge amount includes the error of the wall thickness tolerance. It will be possible to improve the accuracy. In this case, after the process of step 4 described above, even at the position of the top dead center where the finger 2 moves maximally, considering the tolerance of the wall thickness, the sandwiching width of the finger 2 is set below the finger 2 so as not to become zero. If the step of setting f (x) so as to control at the dead point is added, the change in the discharge amount depends only on the tolerance of the outer diameter, so that the manufacturing control of the tube becomes easy.

The finger mechanism may be automatically controlled on the basis of the prediction result so that a preset infusion amount can be obtained.

[0031]

As described above, according to the present invention,
It is possible to provide a flow rate predicting method and an infusion pump capable of guaranteeing a predetermined delivery flow rate when an infusion tube other than the designated one is used in an infusion pump that delivers liquid by peristaltic movement of a finger mechanism having excellent vibration resistance.

[0032]

[Brief description of the drawings]

FIG. 1 (a) is a plan view showing a main part of an infusion pump, and FIG. 1 (b) is a sectional view taken along line XX of FIG.
(C) is a sectional view taken along the line YY of (a), and (d) is a block diagram.

FIG. 2 is a measurement principle diagram.

FIG. 3 is a flowchart of flow rate prediction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Infusion tube 2 Finger 3 Base part (device) 4 Outer diameter measuring part 5 Door 6 Arm 8 Acting transformer type linear gauge 10 Control part 11 Display part

Claims (4)

[Claims] 1. A method for predicting a flow rate when a liquid is delivered by peristaltic movement by a plurality of fingers arranged in parallel in an infusion pump using the infusion tube, wherein the infusion tube is attached to the infusion pump. ,
Measuring the outer diameter, with the infusion tube attached to the infusion pump,
The wall thickness is measured by crushing until the inner diameter portion of the infusion tube comes into contact, and the outer diameter and the wall thickness obtained by each of the measurements are used as a movement function of a finger mechanism for the peristaltic movement. To predict the calculation of the amount of liquid to be delivered by the peristaltic movement with the infusion tube attached, and output the result of the prediction calculation. 2. The outer diameter is (2R + 2d, where R is the radius of the inner diameter, d is the wall thickness), the wall thickness is (d), and the outer tube is attached to the infusion pump. (2R + 2d) is measured, and with the infusion tube attached to the infusion pump,
The wall thickness (d) is measured so as to be crushed until the inner diameter portion of the infusion tube comes into contact, and the outer diameter and the wall thickness obtained by each measurement are finger mechanisms for the peristaltic movement. By substituting it into the transfer function f (x) of, the flow passage cross-sectional area (S) at an arbitrary position (x) of the finger mechanism is given by Using (x) as a parameter obtained from Equation 1, the discharge amount (QL) for one cycle (L) of the finger mechanism is calculated as follows. Obtained from the equation (2), the length (L) of the infusion tube crushed by the plurality of fingers is vt (v is the finger moving speed, t is time), and L = vt, so the flow rate per unit time (Q ) Is given by The flow rate predicting method according to claim 1, wherein the flow rate predicting method is calculated from the equation (3). 3. An infusion pump for delivering liquid by peristaltic movement by a plurality of fingers arranged in parallel using an infusion tube having an arbitrary outer diameter and wall thickness, in a state where the infusion tube is mounted. In the outer diameter measuring means for measuring the outer diameter, in a state where the infusion tube is attached, a wall thickness measuring means for measuring the wall thickness by crushing until the inner diameter portion of the infusion tube abuts, The movement function of the finger mechanism for the peristaltic movement is stored in advance, and the control means is connected to the outer diameter measuring means and the wall thickness measuring means. The amount of liquid sent by the peristaltic movement is calculated in the control means,
An infusion pump, which delivers liquid based on the result of the calculation. 4. The first outer diameter measuring means is provided on a detection member that abuts an outer peripheral portion of the infusion tube.
Of the plurality of fingers arranged side by side, and the second displacement electric conversion unit that is interlocked with the finger mechanism on the most downstream side of the plurality of fingers arranged side by side. 4. The method according to claim 3,
The infusion pump described in.