JPH0441983A - Method and device for detecting blocking state of liquid transmitting pipe in cylinder - Google Patents

Abstract

PURPOSE:To certainly and speedily detect the blocking state of a liquid transmitting pipe with a simple and inexpensive electric mechanism by generating an alarm when a measured load current exceeds a set overload reference value. CONSTITUTION:A drive current supplied from a motor drive circuit 12 to a drive motor 10 is measured by a current measuring circuit 14, and the measured value is inputted into an arithmetric control unit 24. In a ROM 27 of the arithmetic control unit 24, an overload reference value for a blocking state is stored. A detected data from cylinder diameter judging means 16 is inputted into the arithmetric control unit 24 through a cylinder diameter input circuit 18, and another overload reference value is set in the RAM 28. The set comparative data is compared with the measured drive current in the arithmetric control unit 24. As a result, when the drive current exceeds the overload reference value, the liquid transmitting pipe is judged to be in a blocking state, thus inputting an alarm signal in an alarm circuit 22 to actuate alarm means 20.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention uses a syringe with a pumping action to
The present invention relates to a method and apparatus for detecting a blockage state of an infusion pipe connected to a syringe pump configured to infuse fluid by moving the sucker of the syringe with a slider.

[Conventional technology]

Generally, in this type of syringe pump, when a blockage occurs in a portion of the infusion tube connected to the pump, the internal pressure of the syringe increases abnormally. Therefore, various means have been conventionally employed to quickly detect such a state and stop the pump operation.

For example, when a syringe sucker is operated by a pushing head that is moved by a feed screw as a pump operation means, the feed screw and a drive motor are connected via a gear train, and this gear train is a drive motor. A drive gear connected to the motor and a driven gear connected to the feed screw are configured to mesh with each other via an intermediate gear, and further, this intermediate gear is supported by a rocking plate held by a spring elasticity and is close to the rocking plate. A detection device having a configuration in which a microswitch is provided has been proposed (Japanese Unexamined Patent Publication No. 59-97671).

The detection device configured in this manner detects that when the internal pressure of the syringe abnormally increases as described above, the load acting on the pushing head reaches a predetermined value or more, and the driven gear stops or decelerates to below a predetermined moving speed. When this state is reached, the intermediate gear, which continues to rotate at a predetermined rotational speed due to meshing with the driving gear, revolves around the driven gear along with its rotation. Accordingly, the rocking plate moves against the spring force, and a portion of the rocking plate moves to actuate the microswitch. By operating this microswitch, it is possible to detect an overload condition acting on the pushing head, that is, a blockage condition of the infusion tube that is the cause thereof.

In addition, in a separate room, a pressure sensor using a strain gauge that detects the fluid pressure inside the syringe is installed in the pressing part that presses the sucker of the syringe, and the detected value of this pressure sensor is compared with the pressure reference value that indicates an abnormal state. A detection device configured to detect an overload condition (a blocked condition of an infusion tube) acting on a pressing portion has also been proposed (Japanese Patent Laid-Open No. 59-228852).

[Problem to be solved by the invention]

However, since all of the conventional detection devices described above use mechanical mechanisms, they have a complicated structure, are prone to failure, and have low detection accuracy despite increased manufacturing costs.

For example, in the former type of detection device that operates a microswitch, the overload condition to be detected is set by adjusting the elasticity of the spring, so there is a limit to improving detection accuracy. be. In addition, when using multiple types of syringes, the cross-sectional area of the outer cylinder is different for each syringe, and the pressure at the syringe outlet greatly depends on the cross-sectional area of the syringe. Detecting overload conditions is problematic in terms of accuracy. By the way, the cross-sectional area of a 50 ml syringe is approximately 6
．． 6cnf, and the cross-sectional area of the 20mA' syringe is approximately 3d, so in this case there will be a difference of approximately 2.2 times in the detected pressure.

In addition, in the latter detection device that uses a pressure sensor, the pressure sensor is built into the pressing part that presses the sucker of the syringe, so the configuration is complicated and not only is it time-consuming to manufacture, but the pressure sensor is also expensive. Therefore, manufacturing costs also increase significantly.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to be able to manufacture the product with a simple structure and low cost using an electrical mechanism without employing a mechanical mechanism, and to maintain appropriate overload conditions for various types of syringes. It is an object of the present invention to provide a method and device for detecting a blocked state of an infusion tube in a syringe pump, which can realize accurate detection and quickly and reliably detect a blocked state of an infusion tube.

[Means to solve the problem]

A method for detecting a blockage state of an infusion tube in a syringe pump according to the present invention is a syringe pump configured to hold a syringe on a syringe fixing member and move a sucker of the syringe by the action of a drive motor, the diameter of the syringe used is Correspondingly, an overload reference value corresponding to a blocked state of the infusion tube is set based on the data regarding this, the load current of the drive motor that drives the feed screw is measured, and this measured load current is applied to the set overload reference value. When the measured load current value is larger than a set overload reference value, an alarm command output is generated.

Further, the apparatus for carrying out the method for detecting the blocked state of an infusion tube includes: a syringe is detachably held on a syringe fixing member, an end of the sucker of the syringe is held by a holder, and the holder is engaged with a feed screw. A syringe pump coupled to a slider member and configured to move the sucker along a feed screw, comprising: a data input means for inputting data regarding the diameter of the syringe to be used; and a drive motor for driving the feed screw. A current measuring circuit for measuring a load current, an alarm means for indicating a blocked state of the infusion tube, and an overload reference value corresponding to a blocked state of the infusion tube corresponding to the syringe diameter are stored, and the overload reference value is stored from the data input means. A predetermined overload reference value is set as comparison data based on the input syringe diameter, and the alarm means is activated when the measured load current is larger than the comparison data by comparing it with the load current measured by the current measurement circuit. This can be achieved by providing an arithmetic control means configured to generate an output.

In addition, as a determination means for determining the syringe diameter, a lever member that comes into contact with the syringe held on the syringe fixing surface so as to clamp the syringe is provided, and the opening degree between this lever member and the syringe fixing surface is determined. Alternatively, it can be configured to detect separation distance.

[Effect]

According to the method for detecting the blockage state of the infusion tube in a syringe pump according to the present invention, first, an overload reference value corresponding to the blockage state of the infusion tube is set in accordance with the diameter of the syringe to be used,
Next, the load current of the drive motor that drives the feed screw for driving the syringe pump is measured, and by comparing this measured load current with the set overload reference value, the drive of the feed screw of the syringe pump is stopped or When the measured load current increases and becomes larger than the set overload reference value when the load current is significantly reduced, an alarm command output is immediately generated to confirm an abnormal state of the syringe pump.

〔Example〕

Next, a method for detecting a blocked state of an infusion tube in a syringe pump according to the present invention will be described below in relation to an apparatus for implementing this method.

FIG. 1 shows a drive control system of a syringe pump to which the infusion tube occlusion state detection device according to the present invention is applied. In this drive control system, reference numeral 10 is a syringe pump drive motor, 12 is a motor drive circuit, 14 is a current measurement circuit,
16 is a syringe diameter determining means, 18 is a syringe diameter input circuit, 20 is an alarm means, 22 is an alarm circuit, and 24 is an arithmetic control section. However, the calculation control unit 24 includes an I10 boat 25 connected to each of the motor drive circuits 12, the current measurement circuit 14, the syringe diameter input circuit 18, and the alarm circuit 22, and also has a bus connection with the I10 boat 25. Connected CPU26, ROM27,
It is composed of computer components such as RAM 28.

Therefore, the drive motor 10 of the syringe pump is configured as a syringe sucker moving device, and for example, the end of the sucker of the syringe is held by a holder, and the holder is attached to a slider member meshed with a feed screw. In a configuration in which the sucker is coupled to move the sucker along the feed screw, it is used as a means for rotationally driving the feed screw.

The syringe diameter determining means 16 is provided in relation to a lever member for removably fixing the syringe to the casing of the syringe pump. By detecting the distance, etc., it is possible to determine the diameter of the syringe to be applied. Further, the syringe diameter can also be determined by artificially determining the dimensions of the ready-made product and manually inputting the data to the calculation control unit 24 via the syringe diameter input circuit 18.

In the present invention, the drive current supplied to the drive motor 10 for the motor drive circuit 12 is measured by the current measurement circuit 14.
and inputs this measured value to the calculation control section 24. However, in the ROM 27 of the arithmetic and control unit 24, preset various syringe diameters and corresponding overload reference values for the occlusion state are set and stored. Therefore, the diameter of the set syringe is detected by the syringe diameter determining means 16, and this detected data is inputted to the arithmetic control section 24 via the syringe diameter input circuit 18, and the occlusion corresponding to the set syringe diameter is detected. The state overload reference value is set in the RAM 28 as comparison data. Therefore, the comparison data thus set and the drive current of the drive motor 10 measured by the current measurement circuit 14 are compared by the arithmetic control section 24, and for example, the drive current is determined as the comparison data. If it is larger than the overload reference value, it is determined that the infusion tube is in a blocked state, and an alarm signal is output to the alarm circuit 22 to cause the alarm means 20 to perform an alarm operation. Note that as the alarm means 20, an alarm lamp or an alarm buzzer can be adopted.

An example of the processing operations in the arithmetic control section 24 described above is as shown in the flowchart of FIG. That is, according to the flowchart shown in FIG. 2, by inputting data regarding the diameter of the set syringe in the arithmetic control unit 24, a preset overload reference value for the corresponding syringe diameter is selected. and set this as comparison data.

Next, the current value of the drive current of the drive motor 10 inputted from the current measurement circuit 14 is compared with the set value, and if the current current value is less than or equal to the set value, the comparison process is repeated at a predetermined cycle; An alarm will be activated when the current current value is greater than the set value.

Next, a specific example of the configuration of a syringe pump to which the infusion tube occlusion state detection method of the present invention is applied will be described with reference to FIGS. 3 to 6.

FIG. 3 is a cutaway side view of a main part of the syringe pump, and reference numeral 30 indicates a casing of the syringe pump, and a syringe fixing member 32 is provided in a part of the casing 30.

The syringe fixing member 32 is provided with a groove portion 38 for fitting and locking the flange portion 36 of the syringe 34, and a lever member 40 for detachably fixing the syringe 34. Therefore, in the present invention, in relation to this lever member 40, for example, a means for detecting the opening degree or separation distance between the lever member 40 and the casing fixing surface of the syringe 34 is provided, and thereby the syringe diameter can be determined. Configure it to do so.

Further, inside the casing 30, there is provided a sucker moving device 44 for moving and operating the sucker 42 of the y-shape 34.
A drive mechanism section 46 is provided. On the other hand, a holder 5o is provided which engages and holds the end flange 48 of the sucker 42 and moves the sucker 42 back and forth.
0 is combined with the drive mechanism section 56 to form the sucker moving device 44.

FIG. 4 shows a schematic configuration of the drive mechanism section 46 of the sucker moving device 44. As shown in FIG. That is, the drive mechanism section 46 includes a drive motor 52, a speed reduction mechanism 54, a feed screw 56, a guide shaft 58, and a slider member 60. Therefore, in the present invention, a current measurement circuit for detecting the load current of the drive motor 52 is provided in the drive current supply circuit of the drive motor 52, and the measured current is transferred to the preset blocked state of the infusion tube. and a corresponding overload reference value.

In addition, as a specific means for coupling the slider member 60 and the holder 5°, as shown in FIGS. A coupling shaft member 62 is provided, and the holder 50 is removably coupled to one end of the coupling shaft member 62, and the other end is fitted into the inside of the slider member 60 and partially engages with the feed screw 56. half nut 6
4. In this case, the coupling shaft member 62
A compression coil spring 66 having a resilient action is installed at the other end so that the half nut 64 always meshes with the feed screw 56. Further, the holder 50 is provided with a holding portion 68 that moves from the side with respect to the end flange 48 of the sucker 42 and fits and locks with the outer peripheral edge of approximately half of the end flange 48 .

Next, regarding the operation of the syringe pump having the above configuration,
This will be explained with reference to FIGS. 5 and 6.

FIG. 5 shows the holder 50 and slider member 60 in a steady state. That is, in this state, the spring elasticity of the compression coil spring 66 acts on the other end of the coupling shaft member 62 fitted to the slider member 6o, and holds the coupling shaft member 62 in a substantially vertical state. half nut 64
is engaged with the feed screw 56.

Therefore, the holder 5o holds the sucker 42 in its holding portion 68.
The slider member 60 can move the sucker 42 in its axial direction by rotationally driving the feed screw 56.

Next, when exchanging the syringe, as shown in FIG. 6, by manually pressing the holder 5o in the direction of the arrow, the holder 5° resists the spring elasticity of the compression coil spring 66 and aligns with the coupling shaft. It can be tilted together with the member 62 up to a predetermined angle. At this time, the half nut 64 disengages from the feed screw 66 at the other end of the coupling shaft member 62, and the holding portion 68 of the holder 5o also separates from the end flange 48 of the sucker 42, and the slider member 6o Guide shaft 58
It is possible to freely slide it in any direction along the . Therefore, in this case, the removal of a used syringe and the setting of a new syringe can be accomplished simply and quickly with a one-touch operation.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the method for detecting the blocked state of an infusion tube according to the present invention, an overload reference value corresponding to the blocked state of the infusion tube is set in accordance with the diameter of the syringe used, By measuring the load current of the drive motor that drives the feed screw for driving the syringe pump, and comparing this measured load current with the set overload reference value,
When the drive of the feed screw of the syringe pump stops or is significantly reduced, the measured load current increases to a value greater than the set overload reference value (if the current exceeds the set overload reference value), an alarm command output is immediately generated. Because it is an infusion tube 4, it has a simpler configuration than conventional mechanical configurations, reduces malfunctions, and always has high precision.
occlusion state detection of ° can be achieved.

In particular, the apparatus for implementing the method of the present invention includes a data input means for inputting data regarding the diameter of the syringe, a current measuring circuit for measuring the load current of the drive motor that drives the feed screw, and a current measuring circuit for measuring the occlusion state of the infusion tube. and an arithmetic control means that sets the above-mentioned overload reference value, compares this set value with the load current measured by the current measuring circuit, and generates an alarm command output. The present invention has many advantages, such as being able to be manufactured with a simple structure and at low cost, and being able to be easily implemented without making any major modifications to existing syringe pumps.

Although preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. .

[Brief explanation of drawings]

FIG. 1 is a system diagram of a drive control system of a syringe pump to which a device for implementing the method for detecting a blockage state of an infusion tube according to the present invention is applied, and FIG. 2 is a system diagram for implementing the method for detecting a blockage state of an infusion tube according to the present invention. FIG. 1 is a flowchart showing an example of processing operations in the arithmetic control unit of the device, and FIG. 3 is a side view showing an incision of a main part of an embodiment of a syringe pump implementing the method for detecting a blocked state of an infusion tube according to the present invention. Figures 4 and 4 are plan views of essential parts of the syringe pump shown in Figure 3, and Figures 5 and 6 show the arrangement and operating states of the slider member and holder of the syringe pump shown in Figure 3, respectively. FIG. 3 is a sectional side view of a main part. 10... Drive motor 12... Motor drive circuit 1
4... Current measuring circuit 16... Syringe diameter determining means 18... Syringe diameter input circuit 20... Alarm means 22... Alarm circuit 24...
・Calculation control unit 25...I10 boat 26...C
PU27...ROM 28...RAM 30...Casing 32
...Syringe fixing member 34...Syringe 36...Flange portion 38.
...Groove portion 40...Lever member 42...Sucker 44...Socket moving device 46...Drive mechanism section 48...End flange 50...Holder
52... Drive motor 54... Reduction mechanism 5
6...Feed screw 58...Guide shaft 60...
Slider member 62...Connection shaft part 64...Half nut 66...Compression coil spring 68...Holding part

Claims (3)

[Claims] (1) In a syringe pump configured to hold a syringe on a syringe fixing member and move the sucker of the syringe by the action of a drive motor, the occlusion state of the infusion tube is determined based on data regarding the diameter of the syringe used. setting an overload reference value corresponding to the set overload reference value, measuring the load current of the drive motor that drives the feed screw, comparing this measured load current with the set overload reference value, and determining whether the measured load current value is over the set value. A method for detecting a blockage state of an infusion tube in a syringe pump, characterized by generating an alarm command output when the load is greater than a reference load value. (2) The syringe is detachably held on a syringe fixing member, the end of the sucker of the syringe is held in a holder, and the holder is coupled to a slider member that meshes with the feed screw, and the sucker is attached to the feed screw. A syringe pump configured to move along the infusion tube, comprising: a data input means for inputting data regarding the diameter of the syringe to be used; a current measurement circuit for measuring the load current of the drive motor that drives the feed screw; An alarm means indicating a blockage state and an overload reference value corresponding to a blockage state of the infusion tube are stored in correspondence with the syringe diameter, and a predetermined overload reference value is set based on the syringe diameter input from the data input means. arithmetic control means configured to set the value as comparison data, compare it with the load current measured by the current measuring circuit, and generate an output that activates the alarm means when the measured load current is larger than the comparison data; A device for detecting a blockage state of an infusion tube in a syringe pump. (3) A lever member is provided that comes into contact with the syringe held on the syringe fixing surface, and the syringe is fixed by detecting the opening degree or separation distance between the lever member and the syringe fixing surface. 3. The device for detecting a blocked state of an infusion tube in a syringe pump according to claim 2, further comprising a determining means for determining the diameter.