JPH03247348A - Apparatus for detecting abnormality of syringe pump - Google Patents

Abstract

PURPOSE:To detect the abnormality of a syringe pump by extremely simple and inexpensive constitution by allowing a piston to advance to a press member against the energizing force holding a nut at a non-operative position when the advance of a press member is stopped and detecting the same by a detector. CONSTITUTION:At the time of normal operation, a half nut 21 is held at a non-operative position with respect to a press member 6 by a spring 34 but, when the advance of a piston 5 is stopped by the clogging of a tube, since a screw shaft 15 is continuously rotated, the half nut 21 engaged with the screw shaft 15 is advanced against the elastic force of the spring 34 with respect to the press member 6 and a movable block 17 stopped with the stop of the piston 5. When the half nut 21 is advanced with respect to the press member 6 and the movable block 17, a cylindrical member 33 and a rod 35 are advanced with respect to the detector 36 provided to the movable block 17 and, therefore, the detector 36 detects this state to stop a motor 16 or to emit an alarm.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a syringe pump that discharges a medicinal liquid in a cylinder by advancing a piston relative to the cylinder. The present invention relates to a syringe pump abnormality detection device that detects when it becomes impossible or difficult for a syringe pump to eject a medical solution.

"Prior Art" Conventionally, a syringe pump has a fixing means for fixing a syringe cylinder to a base, and a syringe fixed to the base, which is arranged parallel to the axial direction and rotatably supported on the base. The screw shaft includes a screw shaft, a motor that rotationally drives the screw shaft, a pressing member that engages with the piston of the syringe, and a nut that is provided on the pressing member and screws into the screw shaft. It is known that the piston is moved forward via the nut and the pressing member (
Japanese Unexamined Patent Publication No. 59-97671, Publication No. 61-2259
Publication No. 9).

This type of syringe pump is used to inject medicine directly into a patient's body or into an intravenous drip container. If this becomes difficult, the drug solution cannot be fed normally, and the pressure inside the syringe increases, causing problems such as the tube coming off.

``Problems to be Solved by the Invention'' For this reason, as disclosed in the above-mentioned publication, a system has been proposed in which an abnormality detection device for a syringe pump consisting of a gear mechanism is provided between a motor and a screw shaft. Since the gear mechanism requires at least three gears, its structure is complicated and expensive.

In view of such circumstances, the present invention is designed to detect abnormalities in a syringe pump using an extremely simple and inexpensive configuration without using a gear mechanism.

"Means for Solving the Problems" That is, the present invention provides a fixing means for fixing the above-described conventional syringe pump, that is, a syringe cylinder to a base;
A screw shaft arranged parallel to the axial direction of the syringe fixed to the base and rotatably supported on the base, a motor that rotationally drives the screw shaft, and a pressing member that engages with the piston of the syringe. and a nut provided on the pressing member and screwed onto the screw shaft, the syringe pump having a piston that advances through the nut and the pressing member by rotation of the screw shaft, the nut being pressed. The nut is provided on the member so as to be non-rotatable in the circumferential direction of the screw shaft and displaceable in the axial direction of the screw shaft, and the nut is biased in the backward direction opposite to the forward direction to cause a predetermined deactivation of the pressing member. The nut is held in position and is provided with a detector for detecting that the nut has moved forward from the non-operating position relative to the pressing member.

"Operation" According to the above configuration, under normal conditions, the nut is always held in the non-operating position of the pressing member, and the piston can be advanced through the nut and the pressing member by rotation of the screw shaft. .

On the other hand, when it becomes impossible to inject the chemical solution and the forward movement of the pressing member is stopped, the nut screwed onto the screw shaft is rotated by the continued rotation of the screw shaft by the motor. If the nut is moved forward relative to the pressing member against the urging force that holds the nut in the non-operating position, and the nut is advanced from the non-actuating position relative to the pressing member, the detection is performed. can be detected by a device.

Embodiment J The present invention will be described below with reference to an illustrated embodiment. In FIG. 1, a syringe pump is provided with a fixing means 4 for fixing a cylinder 3 of a syringe 2 at a predetermined position on a base 1,
By engaging the pressing member 6 with the piston 5 of the syringe 2 fixed by the fixing means 4 and moving the pressing member 6 forward by the drive mechanism 7 to advance the piston 5, the medicinal liquid in the cylinder 3 is discharged. It is now possible to do so.

The fixing means 4 for the syringe 2 includes a lower support member 11 that supports the lower part of the outer peripheral surface of the cylinder 3 and an upper support member 12 that supports the upper part of the outer peripheral surface of the cylinder 3.
The cylinder 3 can be supported horizontally by a plurality of triangular support surfaces 11a (FIG. 3) arranged in parallel. Further, the lower support member 11 is connected to the cylinder 3.
The cylinder 3 is provided with a recess 11b into which the end flange 3a is inserted, and by engaging the flange 3a with the recess 11b, the cylinder 3 can be prevented from moving in the axial direction. .

The drive mechanism 7 for advancing the pressing member 6 includes a screw shaft 15 disposed on the lower surface side of the base 1 in parallel with the axial direction of the syringe 2 and rotatably supported, and a screw shaft 15 for rotationally driving the screw shaft 15. A motor 16 is provided. A movable block 17 is slidably fitted around the outer periphery of the screw shaft 15, and this movable block 17 is arranged parallel to the screw shaft 15 and slides onto a guide rod 18 fixed to the base 1. The movable block 17 is prevented from rotating around the screw shaft 15 by allowing the movable block 17 to engage.

The pressing member 6 is provided on the movable block 17 so as to be able to move forward and backward in the vertical direction.The pressing member 6 is provided with a half nut 21, and the screw shaft 15 is passed through the half nut 21. The half nut 21 has a female thread screwed into the inner surface of a relatively thick cylindrical member to be screwed into the threaded shaft 15, and the upper part of the cylindrical member is cut out to a width equal to the outer diameter of the threaded shaft 15. As a result, when the pressing member 6 is moved upward, the half nut 21
is engaged with the screw shaft 15, and when the pressing member 6 is pressed down, the half nut 21 and the screw shaft 15 can be disengaged from each other.

A bushing rod 2 is attached to the lower part of the movable block 17.
2 is provided slidably in the same direction as the pressing member 6, and the upper end of the bushing rod 22 is connected to the pressing member 6.
The pressing member 6 is brought into contact with the lower end of the pressing member 6, and a spring 23 is elastically mounted between the bushing rod 22 and the movable block 17.
Normally, the half nut 21 is engaged with the screw shaft 15 by forcing the half nut 21 upward.

The upper end of the pressing member 6 is made to protrude upward through a slit 24 formed in the base 1 along the axial direction of the screw shaft 15, and a flange formed at the end of the piston 5 is formed on the upper front side of the slit 24. An engaging portion 6A is formed with which the portion 5a is engaged. In the illustrated embodiment, the engaging portion 6A is the piston 5.
a pressing surface 6a that comes into contact with the end surface of the pressing surface 6a, and a hooking portion 6b that projects forward from the lower part of the pressing surface 6a and extends upward.
The flange portion 5a of the piston 5 is inserted between the pressing surface 6a and the locking portion 6b so that they can be engaged with each other. At this time, as shown in FIG. 2, a triangular recess is formed on the upper surface of the above-mentioned latching portion 6b, so that the main body portion of the piston 5 can pass through the recess.

Further, the movable block 17 is provided with a positioning means 27 for stopping the pressing member 6 at three vertical positions. Holes 28a, 28b, 28
c, the movable tab 117 is provided on the lever 17 and is biased toward the left in FIG.
, 28c.

As shown in FIG. 2, by positioning the pressing member 6 at the uppermost engagement position A, the engagement portion 6A is engaged with the flange portion 5a of the piston 5, and at the same time the half nut 21 is screwed into the screw shaft. 15. In addition, the pressing member 6 is moved to the middle position B.
By positioning the half nut 21 at the screw shaft 15 while maintaining the engaged state between the engaging portion 6A and the flange portion 5a, and further positioning the pressing member 6 at the lowermost detached position C, , the above half nut 2
1 from the screw shaft 15, the engaging portion 6A and the flange portion 5a can be disengaged from each other at the same time.

Next, the half nut 21 is provided so as to be movable in the axial direction of the screw shaft 15 with respect to the pressing member 6, and as shown in FIG. The half nut 21 is prevented from rotating in the circumferential direction of the screw shaft 15 by forming a flat lower surface and slidably engaging the flat surface with the upper end surface of the bushing rod 22. . Further, as described in 7 above, since the half nut 21 is made by cutting off the "" part of a relatively thick cylindrical member with a width equal to the outer diameter of the screw shaft 15, the half nut 21 is Although it is possible to move in the axial direction, it is prevented from moving in the radial direction.

Further, a cylindrical member 33 is fitted on the outer periphery of the screw shaft 15 on the left side of the half nut 21, and this cylindrical member 33 is slid in the axial direction of the screw shaft 15 with respect to the screw shaft 15 and the movable block 17. It is free to move. A spring 34 is elastically mounted between the cylindrical member 33 and the movable block 17, and the right end surface of the cylindrical member 33 is brought into elastic contact with the left end surface of the half oak 21. 33 and the half nut 21 are held in the non-operating position shown relative to the pressing member 6.

A rod 35 is attached to the left end of the cylindrical member 33.
is brought into contact with a detector 36 such as a limit switch attached to the movable block 17, and the cylindrical member 33 is brought into contact with the spring 34.
When it is displaced to the left against the force, it can be detected by the detector 36.

In the above configuration, when setting the syringe 2 on the base 1, first push down the pressing member 6 to position it at the lowest disengagement position C, detach the half nut 21 from the screw shaft 15, and release the half nut 21 from the screw shaft 15. The joint portion 6A is located at a position where it does not engage with the flange portion 5a. In this state, when the pressing member 6 is moved to the far right position in FIG. 1, the cylinder 3 of the syringe 2 is fixed to the base 1 by the fixing means 4.

After fixing the cylinder 3 to the base 1, the pressing member 6
If the engaging portion 6A is moved to the left to a position where it can engage with the flange portion 5a, and at that position the pressing member 6 is pulled up to the uppermost position and positioned at the engaging position A, the engaging portion 6A is moved to the left. 6
A can be engaged with the flange portion 5a of the piston 5 and the half nut 21 can be engaged with the screw shaft 15 at the same time.

Therefore, if the motor 16 is started in this state, the piston 5 is moved forward via the half nut 21 and the pressing member 6 as the screw shaft 15 rotates, so that the chemical liquid in the cylinder 2 can be discharged.

Furthermore, when the pressing member 6 is located at the intermediate position B, the half nut 21 can be separated from the screw shaft 15 while maintaining the engaged state between the engaging portion 6A and the flange portion 5a. The syringe 2 can be freely operated while manually moving the piston 5' integrally with the pressing member 6.

During normal operation, the half nut 21 is held in a non-operating position relative to the pressing member 6 by the spring 34, but if the forward movement of the piston 5 is stopped due to a blockage in the tube, the screw shaft 15 continues to rotate. Therefore, the half nut 21 that engages with the screw shaft 15 is moved forward against the elastic force of the spring 34 with respect to the pressing member 6 and movable block 17 that stop when the piston 5 stops. Become.

When the half nut 21 is advanced relative to the pressing member 6 and the movable block 17, the cylindrical member 33 and the rod 35 are advanced relative to the detector 36 provided on the movable block 17. This is detected and the motor 16 is stopped or an alarm is issued.

Next, FIGS. 5 and 6 show another embodiment of the present invention. In this embodiment, a pair of guide rails 41 are fixed to the lower surface of the base 1 along the axial direction of the syringe 2. A movable block 42 is slidably attached to this guide rail 41.

A motor 44 constituting a drive mechanism 43 is attached to this movable block 42, and an elongated drive gear 45 attached to the drive shaft of this motor 44 is meshed with a pinion 46 provided on the pressing member 6. Syringe 2
It is meshed with a rack 47 fixed to the base l along the axial direction.

The pinion 46 provided on the pressing member 6 is
When the pressing member 6 is positioned at the uppermost engagement position A, the engaging portion 6A of the pressing member 6 is connected to the flange portion 5a of the piston 5. At the same time, the pinion 46 is engaged with the drive gear 45 and the rack 47 at the same time to establish the drive mechanism 43, so that the movable block 42 and the pressing member 6 can be moved by the motor 44. .

When the pressing member 6 is lowered to the middle position B, the pinion 46 is lowered along the drive gear 45 while maintaining its meshing state, and the pinion 46 is removed from the rack 47. make them leave. As a result, the interlocking relationship of the drive mechanism 43 is interrupted at the pinion 46, so that the movable block 42 and the pressing member 6 can freely move along the guide rail 41. However, at this time, the engaging portion 6A of the pressing member 6 maintains the engaged state with the flange portion 5a.

Further, when the pressing member 6 is located at the lowest disengagement position C, the interlocking relationship of the drive mechanism 43 is interrupted, and the engagement between the engagement portion 6A and the flange portion 5a is further disengaged. I can do it.

In addition, although the half nut 21 is used in the above embodiment, it goes without saying that a normal nut can be used.

"Effects of the Invention" As described above, according to the present invention, the nut that is threaded onto the screw shaft is provided so as to be able to slide only on the pressing member, and the nut biasing means and the detector are added to detect abnormalities. Since the detection device can be configured, the effect can be obtained that the configuration can be made simpler and cheaper than a conventional device using a gear mechanism.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is an explanatory view illustrating the state of engagement between the engaging portion 6A and the flange portion 5a, and FIG. 3 is a line m-■ in FIG. 1. FIG. 4 is a cross-sectional view taken along the TV--TV line in FIG. 1. 1... Base 2... Syringe 3... Cylinder 4... Fixing means 5... Piston
6...Press member 15...Screw shaft 16...Motor 21...Half nut 34...Spring 36...Detector

Claims (1)

[Claims] Fixing means for fixing the cylinder of the syringe to the base; a screw shaft disposed parallel to the axial direction of the syringe fixed to the base and rotatably supported on the base; It includes a motor that rotationally drives a screw shaft, a pressing member that engages with the piston of the syringe, and a nut that is provided on the pressing member and screws into the screw shaft. In a syringe pump in which a piston is moved forward through a member, the nut is provided on the pressing member so as to be non-rotatable in the circumferential direction of the screw shaft and displaceable in the axial direction of the screw shaft,
A detector that biases the nut in a backward direction opposite to the forward direction to hold it in a predetermined non-operating position with respect to the pressing member, and detects that the nut has moved forward from the non-operating position with respect to the pressing member. An abnormality detection device for a syringe pump, characterized by comprising: