JPH03189520A - Metering pump - Google Patents

Abstract

PURPOSE:To attain transmission from a liquid transportation pump by detecting the amount of transported liquid from the detection signal of a detecting means. CONSTITUTION:A transmitting magnet 6 which is embedded in one end surface 32 of a drum 3 on the circumference in in-phase relation with a shaft 5 sends a flow rate pulse by sending a magnetic sensor 12 according to intervals of the depression of a pressure roller 4 to a liquid transportation tube 11. A rotation detection ring 15 detects the movement quantity of the tube 11 and a detector 25 which is fixed atop of a shaft 22 supported by a bearing 23 and responds to the magnet 24 detects the movement quantity. Namely, when the tube 11 is sealed by depression between the rollers 4 which are at an interval of an adjacence angle theta with a pressure cylinder surface 72, flow rate pulses weighted by volume corresponding to the liquid volume in the tube 11 are sent out. The flow rate pulses having constant weight under the condition that the tube 11 has no variation in elastic modulus, and is restored completely to maintain its sectional area in a period wherein the tube is pressed by one roller 4 and pressed again by the other roller 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a metering pump that transmits flow rate pulses from an infusion pump that presses an infusion tube to infuse fluid.

An infusion pump that presses a flexible, elastic infusion tube at multiple locations and infuses the fluid by sequentially moving the pressed locations is similar to a reciprocating pump, in which the fluid to be pumped is compressed by the sliding surface. Because it does not slide, it does not alter the quality of polymeric solutes or destroy biological cells.
It is used in medical applications such as population dialysis to transport colloids, high-molecular-weight solutes, blood, etc., and has also been used extensively in the field of biotechnology, especially in recent years with the progress of biotechnology.

A typical example of an infusion pump is a rotary peristaltic pump. This infusion pump consists of a movable pressing means in which a plurality of pressure rollers of equal size are rotatably supported on the outer periphery of a rotating body that rotates rapidly, and an arc-shaped pressing surface that faces the pressing rollers with a slight gap between them. An infusion tube is inserted between the two, and the infusion tube is rotated and pressed at at least two locations by a pressure roller, while infusing the infusion in the rotational direction of the rotating body.

The above infusion pump uses pressure rollers to press and seal at two points across a section of the infusion tube, and then presses and moves over the infusion tube, so it is housed within the infusion tube in this section. The volume of liquid to be delivered will be constant if the cross-sectional area of the tube is constant and the elastic modulus of the tube material is unchanged, and the volume of infusion, that is, the flow rate, is determined by the number of revolutions per unit time of the rotating body, the effective pressure angle per revolution, and the infusion tube. It is determined by the cross-sectional area. Conventionally, the flow rate has been determined on the assumption that the number of revolutions per unit time of the rotating body, the effective pressing angle per revolution, and the cross-sectional area of the infusion tube are constant, and transmission means such as transmitting a special flow rate pulse have not been arranged. It was not set up.

Furthermore, the cross-sectional area of the infusion tube becomes fatigued as the number of times of pressing increases, and the cross-sectional area in the section between the pressing rollers does not recover and decreases, so that the fluid volume in this period gradually decreases. As a result, there was a problem that the flow rate was not constant.

The present invention has been made to solve the above-mentioned problems, and includes transmitting a flow rate pulse according to the rotation of the pressure roller to infuse fluid, and also transmitting a constant flow rate pulse. The purpose of this pump is to provide a metering pump that also functions as a flow meter, and its gist is that the metering pump is rotatably supported on a coaxial circumference by a pincushion-shaped drum that rotates at a constant speed. A pressing drive unit having a plurality of pressing rollers of the same size,
a casing on which the pressing and sliding part is attached; and at least two casings removably interposed in the casing and coaxial with the drum shaft.
a cassette having a cylindrical surface facing one or more pressure rollers, an infusion pump that inserts an infusion tube communicating with an infusion source between the cassette and the pressure roller to infuse the infusion, and a detector that detects the rotation of the drum of the infusion pump. The present invention is characterized in that the infusion amount is detected by the detection signal of the detection means.

Figure 1 is a schematic explanatory diagram showing an embodiment of the present invention.
The figure is (B) a sectional view taken along the line A-A in figure (B), and (A)
A sectional view taken along line B-B in the figure is shown, and in the figure, 1 is a base, 2 is a casing fixed to the base 1, and has a cavity 26 bored in the center. Reference numeral 3 denotes a drum shaped like a pincushion with an annular groove 31 formed therein, and the motor shaft 10 of the motor 9 is fitted around the shaft center. 4 is a pressure roller, which presses the motor shaft 1 in the annular groove 31.
They are of equal size and are rotatably supported on a shaft 5 fixed to the drum 3, equally distributed on the circumference coaxial with the drum 3, and six of them are arranged in the figure. Reference numeral 7 denotes a cassette fixed to the casing by fixing means such as bolts 71. When fixed, the cassette has a pressing cylindrical surface 72 that is concentric with the motor shaft 10 and slightly separated from the pressing roller 4. Surface 72
The infusion tube 11 is pressed by placing the infusion tube 11 on the pressing roller 4 and then fixing the cassette. Reference numeral 6 denotes a transmitting magnet embedded on the circumference of one end surface 32 of the drum 3 in the same phase as the shaft 5, and transmits a flow pulse in response to the magnetic sensor 12 according to the interval at which the pressing roller 4 presses the infusion tube 11. .

The magnetic sensor 12 is a highly sensitive magnetic sensor such as a Hall element,
It is buried in the casing 2 at a position facing the magnetic sensor 12. Reference numeral 14 denotes a fixed ring, which holds the infusion tube 11 between the rotation detection shaft 15 pressed by a spring 16. The rotation detection shaft 15 detects the amount of movement of the infusion tube 11, and the amount of movement is detected by a detector 25 that responds to a magnet 24 fixed to the tip of a shaft 22 supported by a bearing 23. Reference numeral 17 denotes a fixed guide that works with a pressing piece 18 fixed to the shaft end of the solenoid 21 to clamp and lock or release the infusion tube 11. During infusion, the solenoid 21 and the collar 19 are connected to each other. The infusion tube 11 is locked by being pressed and clamped by a spring 20 extending between the drums, and when the solenoid 21 is sucked, it is released and the infusion tube 11 can be moved by a force acting in the axial direction of the tube as the drum 3 rotates. do. In the above-described infusion pump, when the infusion tube 11 is press-sealed between the pressing rollers 4-4 separated by the corner 0 between the pressing cylindrical surfaces 72,
The liquid volume within the infusion tube 11 is α·r·θ·A.

α is the volumetric efficiency including the influence of the circumferential part on the sealing action of the pressure roller 4, and r is the motor shaft 1.
A is the radius of the center of the infusion tube 11 from the axis 0, and A is the cross-sectional area of the infusion tube 11, and a flow rate pulse having a volume weight corresponding to α, r, θ, and A is transmitted. If this fluid layer pulse is pressed by one pressing roller 4 without any change in the elastic modulus of the infusion tube 11, and is completely restored and the cross-sectional area A is maintained during the period when it is pressed again by the next pressing roller 4. A flow pulse with constant weight is transmitted. However, according to the inventors' experiments, the circumferential speed was 300 cm/
The infusion volume changes approximately linearly by about 6% in minutes.

Figure 2A shows the change in the amount of infusion, and shows the change in the amount of infusion over time T.
It decreases almost linearly until □, and suddenly decreases at T2.

That is, from time T□, the infusion tube receives repeated compressive stress, fatigue progresses, the restoring force deteriorates, and the cross-sectional area decreases accordingly, and at time T2, the restoring force disappears, the cross-sectional area suddenly decreases, and it breaks (point P). This is to reach the following. As a result, the weight of the flow rate of the flow rate pulse becomes small, and the metering pump becomes meaningless. To address this problem, attempts are made to make corrections based on experimental results on points. The first method of this correction is to subtract and correct the decrease in the weight of the flow rate predicted by experimental results according to the number of flow pulses transmitted each time the flow pulse is transmitted, and then integrate the corrected flow pulses. Second, there is a method in which the flow rate pulses are first integrated, and when the total amount of change in the integrated value for each flow rate pulse reaches the amount of the initial flow rate pulse, the flow rate pulse that should be integrated is removed without being integrated. In the first method, the amount of correction for each flow pulse is extremely small, so the second method is effective.

FIG. 3 shows a block diagram of the second method. In the figure, A is an integration correction circuit that integrates the flow rate pulses transmitted from input I, and subtracts it from the input pulse when the total correction amount of the integration value reaches 1 pulse according to a command from calculation circuit B below, and B 1 is an arithmetic circuit that sends a subtraction pulse to subtract from the integrated value of the integration correction circuit A when the input pulse setting reaches a set value; If the correction amount is to be increased sequentially at the rate of 1 pulse at 104, the setting unit will output 0.9999 as the correction coefficient corresponding to 1 pulse at 104. When the integrated value of the calculation circuit B reaches 9999, one pulse is subtracted from the integrated value of the integrated correction circuit A. Next 1
04 corrects 2 pulses, so the setting value is 0.99.
98, and arithmetic circuit B is set to 5×103, followed by <
A subtraction command of 1 pulse each is output to the integration correction circuit A in the form of 5 x 10'. Furthermore, in the next step 104, the setting device is set to 0.
9997 is set, and the calculation circuit B performs subtraction correction three times every 3333 pulses. The above-mentioned subtraction correction is performed by changing the setting every 104 times, and subtracting it every time the amount to be corrected reaches one pulse, and the relationship between the integrated value and the correction coefficient is stored in advance in the setting device. During this period, the infusion tube 11
The period during which recovery due to fatigue is stably performed is defined as, for example, the time when a flow pulse corresponding to the T□ waiting time in FIG. 2 is transmitted. As shown in FIG. 2B, an integrated flow rate value with an accuracy of one pulse can be obtained for each correction command during the correction period of the T working time by operating on the points. Furthermore, as explained in the configuration of FIG. 1, the infusion tube 11 was injected by being elastically pressed and locked by the spring 20 by the pressing piece 18 and the fixed guide 17. By repeating suction, releasing the lock, moving the infusion tube 11 of the length detected by the rotation detector 15, and starting pressing again in a new section of the infusion tube 11, the infusion tube 11 may break due to fatigue. The applicant previously proposed that the point correction mechanism could be used over the period from the start of the infusion to the end of the infusion and the release of the lock. By applying the present invention, it is possible to provide a new metering pump that can obtain highly accurate correction results over a long period of time.

Gai---Izumi According to the metering pump of the present invention, it is possible to transmit flow rate pulses from an infusion pump that could not transmit them, and further,
This makes it possible to accurately correct the inability to measure accurately due to the reduction in the amount of infusion in the pressing section due to compression fatigue of the infusion tube, thereby providing a new metering pump.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a diagram for explaining the outline of the metering pump of the present invention. B) The figure is a sectional view taken along the line B-B in figure (A), Figure 2 is the test value showing the operation time of the infusion tube and the rate of change in the infusion volume, and Figure 3 is a block diagram of the circuit that corrects the infusion volume. Show the diagram. 1... Base, 2... Casing, 3... Drum,
4... Press roller, 6... Transmission magnet, 7... Cassette, 9... Motor, 11... Infusion tube, 12
...Magnetic sensor. Figure 1 Figure 2 (B)

Claims (1)

[Scope of Claims] 1. A pressing drive unit including a plurality of pressure rollers of the same size that are rotatably supported on a coaxial circumference on a pincushion-shaped drum that rotates at a constant speed; a cassette to be attached, a cassette that is removably interposed in the casing and has a cylindrical surface that is coaxial with the drum shaft and faces at least two pressure rollers, and an infusion tube communicating with an infusion source that is connected to the cassette and the pressure roller. 1. A metering pump comprising: an infusion pump inserted between the infusion pumps for infusing fluid; and a detection means for detecting rotation of a drum of the infusion pump, the metering pump being characterized in that the amount of infusion is detected by a detection signal from the detection means. 2. The detection means is composed of a transmitting magnet embedded at the pressure roller position on the outer periphery of one end surface of the pincushion drum, and a magnetic sensor embedded in a base close to the transmitting magnet, and the transmitting magnet is detected from the magnetic sensor. 2. The metering pump according to claim 1, wherein the metering pump emits a flow rate pulse each time it passes. 3. The weight of the flow rate of the flow rate pulse is corrected according to the number of flow rate pulses transmitted after the infusion tube is newly inserted into the infusion pump and infusion is started. Metering pump as described. 4. When starting infusion with a new infusion tube, in the flow rate totalizer that integrates the flow rate pulses, the sum of the volume changes for each flow rate pulse of the total value of the total value becomes one flow rate pulse. 3. The metering pump according to claim 1, wherein the metering pump corrects the flow rate by subtracting the flow rate pulse when the flow rate pulse is reached. 5. During infusion, the infusion tube is locked, the infusion is started, the lock is released after the predetermined amount has been infused, and the infusion is started again when a new infusion tube is transferred to the press area of the infusion pump. Infusion tube transfer. and a correction means for subtracting a number corresponding to the integrated value from the integrated value of the flow rate pulse during the period from when the infusion tube is locked to when the infusion tube is transferred. A metering pump that is characterized by being carried out every period.