JP6659209B2 - Automatic clamping device and clamping method in automatic clamping device - Google Patents

Description

  The present invention relates to an automatic clamping device and a clamping method in the automatic clamping device. More specifically, the present invention relates to an automatic clamp device that clamps a flexible tube constituting a fluid circuit to block the flow of fluid in the tube.

  In some cases, a flexible tube made of plastic or rubber is used as a conduit for flowing a fluid. In particular, a conduit used for medical purposes such as a blood circuit is installed around a patient, so it is difficult to provide a fixed conduit, and it is not used for a plurality of patients. For this reason, flexible tubes are widely used.

  In addition, when handling corrosive or toxic liquid chemicals in chemical product manufacturing factories, etc., adopting fixed pipes and valves will shorten the life of pipes and valves and reduce maintenance. Often becomes troublesome. Therefore, a flexible tube having high corrosion resistance is often used.

  It is often difficult to fixedly provide a valve or the like in a conduit using the flexible tube. For example, in a flexible tube used for a medical device, in order to stop the flow of a flowing fluid, a manual clamp that cuts off the tube to shut off the internal flow is often used.

JP 2010-279495A

  The manual clamp is often used in artificial dialysis tubes and infusion tubes. Before the treatment is started or after the treatment is completed, the tube is squeezed by using elasticity or the like to remove the fluid inside the tube. It is configured to block the flow of water. Since the tube and the infusion tube used for the artificial dialysis have a small diameter, the clamp is configured so that a nurse or the like can easily operate it with fingers.

  On the other hand, a flexible tube is used also in the heart-lung machine, but a tube having a flow rate of blood of 5 · / min or more and a diameter larger than a tube used for the infusion or the like is used. For this reason, it is impossible to interrupt the flow in the tube using the above-described infusion clamp or the like.

  In order to block the flow in the tube, an electromagnetic valve having a drive mechanism such as a solenoid can be adopted. However, since the conduit used in the heart-lung machine is often configured according to the patient, if the electromagnetic valve or the like is fixedly provided, not only the work of assembling the blood circuit becomes troublesome, but also There is a problem that sanitary management becomes troublesome when reused. On the other hand, it can be used only once, but there is a problem that the cost increases. In addition, if an electromagnetic valve or the like having a complicated flow path is used in the blood circuit, blood may coagulate while the flow is stopped, and a problem such as thrombus may occur.

  During use of a heart-lung machine, it may be necessary to immediately block flow in the blood circuit for a variety of reasons. For example, when air bubbles are mixed in blood, if the air is returned to the body as it is, there is a problem that the life of the patient is affected. Further, when a power failure occurs, the operation can be performed by the auxiliary power supply for a short time. However, there is a case where it is necessary to temporarily stop the heart-lung machine for safety. In such a case, it is necessary to quickly stop the flow of blood in the blood circuit.

  However, in the case of an artificial heart-lung machine, the flow rate of blood is large. Therefore, in order to squeeze the flexible tube using a solenoid or the like, it is necessary to employ a large-output device, which causes a problem that the device becomes large. Occurs. In addition, when a solenoid is used, a pipe line is rapidly cut off, and a water hammer phenomenon occurs. In addition, since the flexible tube is employed, the water hammer easily causes the flexible tube to vibrate or swing greatly. This may affect other devices and patients. In addition, elasticity may be accumulated in the flexible tube, which may cause a backflow phenomenon of blood after the blood circuit is cut off.

  Further, since power is required to operate the solenoid, it cannot be used in the event of a power failure or the like. For this reason, there is a problem in using it as an emergency safety device. On the other hand, air pressure or hydraulic pressure can be used, but a circuit for flowing these fluids is required, which complicates the configuration of the device and increases the size of the device. Electric power is also required when using the above air pressure or hydraulic pressure.

  The above problem is also a problem that occurs when a flexible tube is used in a device for handling a highly reactive liquid chemical or in a biodevice.

  It is an object of the present invention to provide an automatic clamp device capable of clamping a flexible tube and interrupting the flow of a fluid in the tube without causing the conventional problem.

  The present invention relates to an automatic clamping device that presses a flexible tube constituting a fluid circuit to cut off the flow of fluid in the tube, and includes a pressing member provided with a pressing member for pressing the tube to press the tube. A moving member, a screw mechanism for moving the pushing member toward and away from the tube, a driving motor capable of driving the screw mechanism to separate the pushing member in the axial direction, An elastic member that elastically urges the member toward the tube, and an elastic member that can squeeze the tube via the squeezing member; and a pushing member holding unit that can hold the pushing member at a position separated from the tube. A tube holding portion that can position and hold the tube and squeeze the tube with the squeezing member is provided, and the pushing member, the screw mechanism, the drive motor, and the elastic member include Constructed and a location structure member.

  The screw mechanism is rotatably held by the structural member, and includes a pushing shaft rotated by the drive motor, and a nut member provided on the pushing member and meshed with the pushing shaft. It is configured. Various commercially available screw units can be employed as the screw mechanism constituting the screw mechanism. The pushing member is meshed with a pushing shaft constituting the screw mechanism, and is held so as to be axially movable and non-rotatable with respect to the structural member.

In the automatic clamping device, by releasing the holding of the pushing member holding means, allowing the rotation of the pushing shaft by the elastic force of the elastic member, bringing the pushing member close to the tube, The squeezing member is configured to squeeze the tube and block the flow of the fluid. The tube holding section includes a pair of roller-shaped pressing sections, and a pair of plate-shaped holding sections capable of positioning and holding the tube between the pressing sections, and the pair of pressing sections. By pushing the distal end of the pressing member in between, the tubes on both sides of the pressing member can be pressed in a posture bent along the curved surface of the pressing portion, and can be pressed so as to be crushed.

  In the clamp device according to the present invention, the pushing member is moved in the axial direction using the screw mechanism, the drive motor, and the elastic member. The drive motor is used in a case where at least the pushing member is separated from the flexible tube. On the other hand, the elastic member is used as a drive source for pressing the flexible tube, and presses the pressing member to squeeze the flexible tube via a squeezing member. It is configured to block the flow of the fluid inside.

  The screw mechanism includes a pushing shaft. By rotating the pushing shaft by the driving motor, the pushing member can be moved toward and away from the flexible tube. The drive motor is configured to be able to move at least the pressing member to a position separated from the flexible tube against the elasticity of the elastic member.

  The above screw mechanism and various types of screw mechanisms can be adopted. The lead angle of the screw is set so that the pushing shaft can be rotated by the pushing force of the pushing member. In order to gradually reduce the frictional force, it is preferable to employ a ball screw mechanism. The ball screw mechanism is configured to rotatably hold a ball member between a spiral groove provided on an outer periphery of the pushing shaft and a spiral groove of a nut member, and the ball is configured such that the pushing shaft and the nut It is configured to be rotated by the relative rotation of the member and circulated through a circulation hole provided in the nut member. For this reason, it is possible to reduce the frictional resistance between the pushing member and the nut member.

  The tube can be squeezed by the force of the drive motor. However, in order to squeeze the tube and block the flow in the tube, a drive motor with a large output is required, and the size of the apparatus is increased. On the other hand, in order to exert a large force by a small output drive motor, a speed reduction mechanism is required, but if a speed reduction mechanism is provided, the axial speed of the pushing member becomes small, and the tube is quickly pinched in an emergency, It becomes difficult to block the flow of the fluid in the tube.

  In the present invention, in order to avoid the inconvenience, the elastic tube is used to press the flexible tube. The elastic member is configured to exert an axial force on the pressing member to rotate the pressing shaft to exert an elastic force capable of pressing the flexible tube via the pressing member. Various elastic members such as a coil spring and an air spring can be used as the elastic member.

  By squeezing the flexible tube using the elasticity of the elastic member, the drive motor itself does not require an axial output or pushing speed capable of squeezing the tube. It is also possible to adopt with.

  On the other hand, since the tube can be squeezed using the elasticity of the elastic member, the flexible tube can be quickly squeezed, and the flow of the fluid in the tube can be quickly shut off in an emergency.

  In addition, the above-described shutoff operation can be performed without using electric power, and it is possible to easily cope with an emergency operation in a medical device or the like.

  In addition, in the event of an emergency, the elastic tube is used to quickly press the flexible tube to shut off the flow, and when no emergency is required, the drive motor causes the flexible tube to be turned off. May be configured to be pinched.

  The configuration of the pushing member holding means is not particularly limited. For example, the pushing member can be directly held at a predetermined position by using an electromagnetic actuator or various clutch mechanisms. Further, the pushing member holding means may be configured to indirectly hold the pushing member at a predetermined position by preventing rotation of the pushing shaft using the shaft holding torque of the drive motor. it can. When the pushing member is held by the shaft holding torque, it is preferable to use a stepping motor.

  The configuration and form of the structural member are not particularly limited, and a tube holding portion capable of positioning and holding the flexible tube and squeezing the flexible tube with the squeezing member is provided. May be configured to be integrally connected so that required functions can be exhibited. For example, the above-mentioned structural member can be constituted using a plate-like member or a rod-like member, and the above-mentioned respective members can be organically connected.

  As a structure for holding the pushing member so as to be axially movable and non-rotatable with respect to the structural member in the axial direction of the pushing shaft, for example, provided so as to penetrate the pushing member, A guide member that slides in the axial direction can be employed. For example, one or two or more rod-shaped guide shafts can be provided in parallel with the pushing shaft.

  In the present invention, by releasing the holding of the pushing member holding means, the pushing member is pressed in the direction approaching the flexible tube by the elastic force of the elastic member, thereby rotating the pushing shaft. Can be With the rotation of the pushing shaft, the pushing member approaches the tube, and the pressing member presses the tube and shuts off the flow of the fluid.

  The method of releasing the holding of the pushing member holding means is not particularly limited. For example, the holding may be released when the power is turned off. For example, when the power supplied to the drive motor and the pushing member holding unit is turned off, the holding of the pushing member holding unit can be released. Further, the configuration may be such that the holding is released when a predetermined release signal is input. When the pushing member holding means is configured using the shaft holding torque of the drive motor, or when a shaft holding force is generated in the drive motor, the elastic holding force is released by releasing the shaft holding torque. , The rotation of the pushing shaft is allowed, and the pushing member is brought closer to the tube.

  In the present invention, when the pushing member is moved toward the flexible tube by the elastic member, the pushing shaft is rotated by the pushing member. Therefore, the screw mechanism can act as a damper when the pushing member is moved toward the tube by the elastic force of the elastic member. That is, the elasticity from the elastic member is converted into the rotational movement of the pushing shaft by the screw mechanism, and the axial speed at which the pushing member approaches the flexible tube can be adjusted. Accordingly, the pressing member does not squeeze the flexible tube so as to collide with the structural member, and the occurrence of water hammer due to the sudden pressing of the flexible tube is suppressed. Becomes possible. As a result, it is possible to prevent the flexible tube from vibrating or swinging. Further, it is possible to prevent a device provided in the fluid circuit from being adversely affected by a mechanical impact or the water hammer. Furthermore, in medical equipment such as a heart-lung machine, it is possible to prevent adverse effects on the human body.

The axial speed of the pushing member by the elastic member is preferably set, for example, to 5 msec to 500 msec (5 mm / msec to 0.05 mm / msec) for a movement distance of 25 mm. Thus, the flexible tube can be quickly pressed to block the flow of the fluid, and the occurrence of water hammer can be effectively prevented .

  The automatic clamp device according to the present invention can be applied to various fields using a flexible tube. In the field of medical equipment, it can be adopted, for example, as a safety device such as a heart-lung machine. Further, it can be adopted as a shut-off valve or a safety device of a plant such as a chemical factory using a liquid chemical.

  The flexible tube can be quickly squeezed to block the flow of fluid, and the device can be downsized.

It is a figure showing an example of the artificial heart-lung machine circuit provided with the automatic clamp device concerning the present invention. 1 is an overall perspective view showing an example of an automatic clamping device according to the present invention. FIG. 3 is a plan view showing a state where a flexible tube is attached to the automatic clamp device shown in FIG. 2. It is a front view of the automatic clamp apparatus shown in FIG. FIG. 3 is a plan view showing a state in which a flexible tube is pressed by the automatic clamping device shown in FIG. 2. FIG. 6 is a sectional view taken along the line VI-VI in FIG. 3.

  An embodiment according to the present invention will be described below with reference to the drawings. The present embodiment is an example in which the automatic clamp device according to the present invention is applied to a heart-lung machine.

  As shown in FIG. 1, the heart-lung machine 100 is configured to take over the functions of the heart and lungs. The artificial heart-lung machine 100 includes a blood reservoir 102 that adds and stores a replacement fluid supplied from a replacement fluid tank 107 to blood collected from the heart 101 or the like, and a blood pump 103 that circulates the blood stored in the blood reservoir 102. And an artificial lung 105 for adding oxygen sent from an oxygen blender 108 to blood flowed by the blood pump, a blood feed filter 106 for filtering blood returned to the human body, and the like. The blood circuit 115 is configured by connecting the devices by a conduit configured by the flexible tube 20, and is connected to the patient's heart 101 via the blood supply unit 116 and the blood removal unit 117.

  When air bubbles or the like are generated in the blood circuit 115 or abnormal pressure in the pipeline occurs, the life of the patient is affected. For this reason, the blood circuit 115 is provided with a gas monitor 111 and pressure gauges 109, 110, and 113. When an abnormality occurs, an emergency alarm is issued or the operation of the heart-lung machine 100 is temporarily stopped. It is configured to stop. Also, when a power failure occurs, the blood pump 103 and the like are stopped, so that an emergency power supply (not shown), a manual pump, and the like are often provided.

  In the artificial heart-lung machine 100 configured as described above, when the blood pump 103 stops, the blood flow in the blood circuit 115 stops. However, in many cases, the flow of blood in the blood circuit 115 cannot be completely shut off due to the action of gravity or the elasticity of the flexible tube. For example, when a centrifugal pump is used as the blood pump 103, there is a gap between the impeller and the casing, so that blood flows when pressure is applied. In particular, when air bubbles are generated in blood, unless the blood supply to the patient is stopped immediately, the life of the patient is jeopardized.

  The automatic clamp device 1 according to the present invention is arranged in the blood circuit 115 upstream of the blood feeding unit 116 so that the blood feeding to the patient can be immediately stopped when the above situation occurs. The automatic clamp device 1 flows through the blood circuit 115 when a signal from a control device (not shown) or the control device 104 of the blood pump 103 or the power supply to the automatic clamp device 1 is turned off. It is configured to stop blood flow.

  As shown in FIGS. 2 and 3, the automatic clamping device 1 includes a pressing member 2 provided with a pressing member 3 for pressing the flexible tube 20 to press the flexible tube 20, and A screw mechanism 8 for moving toward and away from the conductive tube 20, a drive motor 4 for driving the screw mechanism 8 to separate the pushing member 2 in the axial direction, and the pushing member 2 An elastic member 5 that elastically urges the flexible tube 20 and can squeeze the flexible tube via the squeezing member 3 is provided. In addition, a tube holding portion 7 that can position and hold the flexible tube 20 and squeeze between the squeezing member 3 is provided, and the pushing member 2, the screw mechanism 8, the driving motor 4 and a structural member 10 on which the elastic member 5 is disposed.

The flexible tube 20 used in the blood circuit 115 of the heart-lung machine 100 often has an outer diameter of 10 mm to 15 mm, and the flow of blood is controlled by a manual clamp used in an infusion device or a dialysis device. It is difficult to shut off. In addition, those having an inner diameter of 6 to 10 mm are often adopted, and the flow rate of blood reaches 5 to 10 L / mm . For this reason, the flow velocity of blood and the static pressure acting on the wall surface of the flexible tube 20 are larger than those of the infusion device and the like.

  A wedge-shaped pressing member for pressing the flexible tube 20 is provided on the distal end side in the axial direction of the pressing member 2. A nut member 8b is incorporated inside the pushing member 2, and a pushing shaft 8a constituting the screw mechanism 8 is provided so as to penetrate the nut member 8b.

  A ball screw mechanism is employed as the screw mechanism 8 according to the present embodiment. The ball screw mechanism includes a ball that is rotatably held between the pushing shaft 8a and a spiral groove formed on the outer periphery of the pushing shaft 8a and an inner peripheral portion of the nut member 8b. It is provided with a member 8c and a circulation groove 8d for circulating the ball member 8c. By employing the ball screw mechanism 8, the frictional force due to the rotation of the pushing shaft 8a can be reduced. It should be noted that any screw mechanism that can rotate the pushing shaft 8a by the elastic force of the elastic member 5 may be used, and a conventional screw mechanism having a large lead angle may be employed.

  In the present embodiment, a coil spring is employed as the elastic member 5. The coil spring is provided between the pushing member 2 and the driving motor 4 so as to surround the pushing shaft 8a. The coil spring presses the flexible tube 20 so as to block the flow of the fluid inside. It is configured so that it can exert its power. In the present embodiment, the flexible tube is set so that it can be pressed with a force of about 100 N (10 kgF).

  As the drive motor 4 according to the present embodiment, a stepping motor is employed. As the stepping motor, one capable of moving the pushing member 2 to a position separated from the flexible tube 20 at least against the elasticity of the elastic member 5 is adopted. The drive shaft 16 of the drive motor 4 and the pushing shaft 8a are connected to rotate integrally using various connection means.

  In the present embodiment, the pushing member holding means 6 is configured by using the shaft holding torque of the stepping motor. That is, by supplying power to the stepping motor from a control device (not shown) or the like, a required shaft holding torque (rotation preventing force) is generated on the motor rotation shaft. The rotation of the pushing shaft 8a is prevented, so that the pushing member 2 can be held at a predetermined axial position.

  Each of the above members is disposed on the structural member 10. The structural member 10 according to the present embodiment is configured by combining a plate-like material and a rod-like material, and can position and hold the flexible tube 20 and squeeze between the flexible tube 20 and the squeezing member 3. A first plate-shaped member 10a provided with a holding portion 7, a second plate-shaped member 10c provided with a motor holding portion 17 for holding the drive motor 4, a first plate-shaped member 10a and a second A third plate-like member for rotatably holding the pushing shaft 8a between a pair of bar-like members 10d, 10d connecting the plate-like member 10c in a bridging manner and the second plate-like member 10c. And a member 10b. Further, between the third plate-like member 10b and the second plate-like member 10c, the pushing member 2 is slid in the axial direction of the pushing shaft 8a, and is made unrotatable. A pair of guide shafts 11 and 11 for holding are provided. The guide shafts 11 are arranged so as to penetrate guide portions 2 a and 2 b provided on both sides of the pushing member 2.

The tube holding section 7 is a pair of roller-shaped pressing sections 7b provided on the first plate-shaped member 10a side, and a pair of positioning sections that can sandwich the flexible tube 20 between the pressing sections 7b. And a plate-shaped holding member 7a. As shown in FIG. 5, the flexible tubes 20 on both sides of the pressing member 3 are moved into the respective pressing portions by causing the distal end of the pressing member 3 to protrude between the pair of pressing portions 7 b. The flexible tube 20 is configured to be able to be squeezed in a posture bent along the curved surface 7b .

In the present embodiment, first, as shown in FIGS. 1 and 3, the drive motor 4 rotates the pressing shaft 8a, against the elastic force of the elastic member 5, the pressing member 2, the A squeezing member retreating step of moving to a position separated from the flexible tube 20 is performed.

  Since the pushing member 2 can be moved using the screw mechanism 8, even if the driving motor 4 having a small output is used, the pressing member retreating step is performed against the elasticity of the elastic member 5. It can be carried out.

  By holding the pushing member 2 at the axial position separated from the flexible tube 20 by the pushing member holding means 6, a standby step is performed. In the present embodiment, the rotation of the push shaft 8a is prevented by using the shaft holding torque of the drive motor 4, so that the push member 2 can be held via the screw mechanism 8. Specifically, by supplying electric power to the stepping motor from a motor control device (not shown) or the like, a shaft holding torque is generated, and the rotation of the pushing shaft 8a by the elastic member 5 is prevented, whereby the standby state is reduced. A process is performed.

  After the waiting step, a tube mounting step of mounting the flexible tube 20 is performed. In the present embodiment, the tube mounting step is performed by fitting the flexible tube 20 between the pressing portion 7b and the plate-shaped holding portion 7a of the tube holding portion 7. In addition, it is also possible to configure so that the pressing portion 7b and the plate-shaped holding portion 7a of the tube holding portion 7 can be separated from each other when the tube is mounted. The tube mounting step is performed as a part of the installation step of the blood circuit 15. After the standby step, the flexible tube 20 is not pressed, and is placed in a state where the flow of blood inside is allowed.

  After completing the step of installing the cardiopulmonary bypass circuit including the step of installing the tube, a predetermined disinfection step or the like is performed, and the blood sending section 116 and the blood removing section 117 are connected to the heart 101 of the patient, and the heart-lung machine 100 Is activated.

  The automatic clamping device 1 having the above configuration is configured such that the standby step is performed by supplying power from a power supply device (not shown).

  In the present embodiment, when the power supply is turned off, the shaft holding torque constituting the pushing member holding means 6 of the drive motor 4 disappears or is reduced. Therefore, the rotation of the pushing shaft 8a is allowed, and the pushing shaft 8a is rotated by the elastic force acting on the pressing member 2 from the elastic member 5. As a result, the pushing member 2 is brought close to the flexible tube 20, and the clamping member 3 clamps the flexible tube 20 between the flexible tube 20 and the tube holding portion 7, and the blood A flow blocking step of blocking the flow is performed.

  In the flow blocking step, the pushing shaft 8 a is rotated by the pushing member 2. For this reason, the screw mechanism 8 can act as a damper when the pushing member 2 is moved toward the flexible tube 20 by the elastic force of the elastic member 5. That is, the elasticity from the elastic member 5 is converted into the rotational movement of the pushing shaft 8 a by the screw mechanism 8, and the pushing member 2 adjusts the axial speed approaching the flexible tube 20. Becomes possible. Thus, the pressing member 3 does not squeeze the flexible tube 20 so as to collide with the structural member 10. Further, it is possible to suppress the occurrence of water hammer due to the sudden pressing of the flexible tube 20. As a result, it is possible to prevent the flexible tube 20 and other devices from vibrating and rocking. Further, it is possible to prevent other devices provided in the fluid circuit 115 from being adversely affected by the mechanical impact or the water hammer. Further, adverse effects on the human body can be prevented.

  It is preferable that the axial speed of the pushing member 2 by the elastic member 5 is set to, for example, 5 msec to 500 msec (5 mm / msec to 0.05 mm / msec) for a movement distance of 25 mm. Thereby, the flexible tube 20 can be quickly pressed to block the blood flow, and the occurrence of water hammer can be effectively prevented.

  In the present embodiment, the screw mechanism 8 functions as the damper. However, the axial speed of the pushing member 2 may be adjusted by combining a damper function by adjusting the shaft holding torque of the drive motor 4. Can also.

  Note that the flow blocking step is configured to be performed when the power of the drive motor 4 is turned off, but may be configured to be performed in synchronization with the stop of the blood pump 103. Further, the flow shut-off step can be performed in conjunction with an abnormality alarm from the gas monitor 111 or the like.

  On the other hand, when performing the flow blocking step in performing priming of a blood circuit or the like, the flexible tube may be configured to be pressed by the drive motor 4 without using the elasticity of the elastic member 5.

  In the above embodiment, the automatic clamp device according to the present invention is applied to a blood circuit of a heart-lung machine, but the automatic clamp device according to the present invention can be applied to other medical devices using a flexible tube. In addition, it is configured using a flexible tube, and can be applied to another mechanical device that processes a highly reactive liquid medicine or the like.

  The scope of the present invention is not limited to the above embodiments. The embodiments disclosed this time are examples in all respects, and should be considered not to be restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  It is possible to provide an automatic clamping device that can use a small drive motor for output and can prevent the occurrence of water hammer.

DESCRIPTION OF SYMBOLS 1 Automatic clamp apparatus 2 Pushing member 3 Nipping member 4 Drive motor 5 Elastic member 6 Pushing member holding means 7 Tube holding part 8 Screw mechanism 8a Pushing shaft 8b Nut member 10 Structural member 20 Flexible tube 115 Fluid circuit

Claims (10)

An automatic clamp device for clamping a flexible tube constituting a fluid circuit to cut off the flow of fluid in the tube,
A pushing member provided with a squeezing member for pressing the tube to squeeze it,
A screw mechanism for retracting the pushing member close to the tube,
A drive motor that drives the screw mechanism to separate the pushing member in the axial direction;
An elastic member that elastically urges the pushing member toward the tube, and can squeeze the tube via the squeezing member;
Pushing member holding means capable of holding the pushing member at a predetermined position against the elasticity of the elastic member;
A structure in which a tube holding portion capable of positioning and holding the tube and squeezing between the squeezing member and the pressing member, the screw mechanism, the driving motor, and the elastic member are provided. And a member,
The screw mechanism includes a pushing shaft rotatably held by the structural member and rotated by the drive motor, and a nut member provided on the pushing member and meshed with the pushing shaft. Is composed of
The pushing member is held movably in the axial direction of the pushing shaft and non-rotatably with respect to the structural member,
By releasing the holding of the pressing member holding means, the rotation of the pressing shaft due to the elastic force of the elastic member is allowed, the pressing member is brought close to the tube, and the pressing member is The tube holding portion is configured to pinch a tube and cut off the flow of the fluid, and the tube holding portion has a pair of roller-shaped pressing portions, and a pair of positioning and holding members capable of holding the tube between the pressing portions. Plate-like holding portion, and the tube on both sides of the pressing member is pushed along the curved surface of the pressing portion by making the tip of the pressing member protrude between the pair of pressing portions. Automatic clamping device configured to pinch in a bent position .   2. The screw mechanism according to claim 1, wherein the screw mechanism and / or the drive motor are configured to act as a damper when the pushing member is moved toward the tube by the elastic force of the elastic member. 3. Automatic clamping device.   The automatic clamping device according to claim 1, wherein the screw mechanism is a ball screw mechanism including a ball member rotatably held between the pushing shaft and the nut member. 4. The pushing member holding means is configured to hold the pushing member at a predetermined position by preventing rotation of the pushing shaft using a shaft holding torque of the drive motor,
The structure according to claim 1, wherein by releasing the shaft holding torque, rotation of the pushing shaft due to elasticity of the elastic member is allowed, and the pushing member is brought closer to the tube. Item 4. The automatic clamping device according to any one of Items 3. The structural member is
A tube holding unit for holding the tube,
A motor holding unit that holds the drive motor,
The automatic clamping device according to any one of claims 1 to 4, further comprising a guide member that holds the pushing member so as to be movable in the axial direction and not to rotate.   The said pushing member holding means and the said drive motor are comprised so that rotation of the said pushing shaft may be permitted, when a power supply is turned off. Automatic clamping device.   7. The automatic clamping device according to claim 1, wherein the driving motor is a stepping motor, and the pushing member holding unit is configured using a shaft holding torque of the stepping motor. 8.   The automatic clamp device according to any one of claims 1 to 7, wherein the fluid circuit is a blood circuit. A clamping method in an automatic clamp device for compressing a flexible tube constituting a fluid circuit to cut off the flow of fluid in the tube,
The above clamping device,
A pushing member provided with a squeezing member pressed against the tube to squeeze it,
A screw mechanism for retracting the pushing member close to the tube,
A drive motor that drives the screw mechanism to separate the pinching member in the axial direction;
An elastic member that elastically urges the pushing member toward the tube, and can press the tube;
Pushing member holding means capable of holding the pushing member at a predetermined position against the elasticity of the elastic member;
It has a pair of roller-shaped pressing portions, and a pair of plate-shaped holding portions capable of positioning and holding the tube between the pressing portions, and positioning and holding the tube to hold the tube between the pressing members. With a tube holding part that can be pressed,
A squeezing member retreating step in which the drive motor and the screw mechanism move the pushing member to a position separated from the tube against the elasticity of the elastic member;
A pushing member holding means for holding the pushing member at a predetermined position to allow the flow of the fluid; and
When a predetermined operation signal is input, or when power to the drive motor and the pushing member holding mechanism is turned off, the pushing member holding means releases the holding of the pushing member, and By allowing the axial movement of the pushing member by the elasticity of the elastic member, the pressing member presses the tube to cut off the flow of fluid,
The flow shut-off step is performed by squeezing the tube on both sides of the squeezing member along the curved surface of the squeezing portion by squeezing the tip of the squeezing member between the pair of pressing portions. The clamping method in the automatic clamping device. The clamping method according to claim 9, wherein in the flow blocking step, the screw mechanism and / or the drive motor functions as a damper for the axial movement of the pushing member.

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