Tube pump

Abstract

To restrain pulsation from occurring in an elastic tube.SOLUTION: A tube pump 2 comprises a housing 11 in which a large-diameter tube 1a (elastic tube) is arranged along a side wall 11a formed in a nearly horseshoe shape, and a roller 13 to be moved along the side wall 11a of the housing 11. The side wall 11a is provided with a pressure relief section C having an arc with a larger radius than that of a blockage section A in which the large-diameter tube 1a is pressed and blocked, between the blockage section, and a separation section B having a shape gradually separating from a rotation center. While the roller 13 moves in the pressure relief section C, a communication port for establishing communication between a portion on the upstream side of the roller 13 and a portion on the downstream side is formed in the large-diameter tube 1a pressed by the roller 13, and the size of the communication port is kept constant.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tube pump, and more particularly to a tube pump that performs liquid feeding while moving an elastic tube while pressing it with a roller.

Background Art

[0002] Conventionally, for example, in a dialysis apparatus used for dialysis treatment, a tube pump is used as a blood pump for feeding a patient's blood. Such a tube pump includes a housing in which an elastic tube is disposed along a side wall formed in a substantially U-shape, a rotor rotatably provided inside the side wall of the housing, and a roller provided on the rotor and moving along the side wall. When the rotor is rotated, the roller moves while compressing the elastic tube, so that the liquid in the elastic tube is fed (Patent Document 1). On the side wall of the housing of such a tube pump, there are formed an occlusion section that compresses and completely occludes the elastic tube between the roller and the side wall, and a separation section that is continuously provided on the downstream side of the occlusion section and has a shape that gradually separates from the rotation center of the rotor. In the separation section, since the compression of the tube by the roller is released, the elastic tube tries to return to its original shape by elastic force, and the volume of the portion pressed by the roller increases. At this time, if the roller suddenly detaches from the side wall, the volume of the compressed portion suddenly expands and the nearby liquid is drawn in. In particular, when the liquid located on the downstream side of the rotor is drawn in, there is a problem that pulsation is generated in the circuit due to the backflow of the liquid. In order to address such a problem, in the tube pump described in Patent Document 2, in the separation section, the roller is gradually separated from the side wall so that the volume of the portion pressed by the roller does not suddenly expand, and an attempt is made to suppress the backflow of the liquid.

Prior Art Documents

Patent Documents

[0003] [Patent Document 1] Patent No. 5397747 [Patent Document 2] Japanese Patent Application Publication No. 6-17769 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, even with such a tube pump, if a device that creates resistance to the flow of liquid, such as a dialyzer, is installed downstream of the tube pump, the liquid flowing between the tube pump and the device will be subjected to both the pressure from the tube pump and the pressure from the resistance of the device. As a result, the pressure of the liquid located downstream of the roller moving through the aforementioned blocked section becomes higher than the pressure of the liquid located upstream of the roller, creating a pressure difference between them. As a result, when the rotor separates from the side wall in the aforementioned separation section, and a communication port is formed in the elastic tube connecting the upstream and downstream sides of the rotor, a problem arises in which backflow of liquid passing through the communication port occurs in an attempt to eliminate the differential pressure, causing pulsation. In view of these problems, the present invention provides a tube pump that can more effectively suppress the pulsation of liquid within an elastic tube. [Means for solving the problem]

[0005] In other words, the tube pump according to claim 1 is A tubular pump for the blood circuit of a dialysis machine, The device comprises a housing in which an elastic tube is disposed along a side wall formed in a roughly horseshoe shape, a rotor rotatably mounted inside the side wall of the housing, and a roller provided on the rotor that moves along the side wall. In a tube pump, the above-mentioned side wall has an arc of a predetermined radius centered on the rotation center of the rotor, and comprises a closing section that compresses and closes the elastic tube between the roller and the side wall, and a release section provided downstream of the closing section and having a shape that gradually moves away from the rotation center, The above-mentioned side wall includes a pressure relief section between the above-mentioned closed section and the above-mentioned detached section, which has a circular arc with a larger radius than the above-mentioned closed section, centered on the rotational center of the rotor. While the roller moves through the pressure relief section, the elastic tube compressed by the roller is connected to the upstream and downstream portions of the roller. tiny It is characterized by the formation of a communication opening, while maintaining a constant size for the said communication opening. [Effects of the Invention]

[0006] According to the above invention, by providing a pressure relief section between the closed section and the released section, a minute communication opening is formed between the upstream and downstream sides of the roller in the compressed elastic tube, and the size of the communication opening is kept constant while the roller passes through the pressure relief section. This creates a small flow from the downstream side to the upstream side of the roller through the communication port, thereby eliminating the pressure difference between the space upstream and downstream of the roller. Consequently, even if the roller subsequently moves to the aforementioned detachment section and detaches from the elastic tube, backflow of liquid due to the pressure difference is suppressed, making it possible to suppress the generation of pulsation. We can provide a tube pump for the blood circuit of a dialysis machine. [Brief explanation of the drawing]

[0007] [Figure 1] Plan view of a tube pump [Figure 2] Diagram illustrating the movement of the roller [Figure 3] Enlarged view of Part III in Figure 1 and Figure 2 [Modes for carrying out the invention]

[0008] The following describes an illustrated embodiment. Figure 1 shows a tube pump 2 provided in a blood circuit 1 that constitutes a dialysis machine. The blood circuit 1 is provided with a dialyzer 3 for performing hemodialysis and a drip chamber 4. The blood circuit 1 described above is composed of an arterial blood circuit and a venous blood circuit, with the ends of the arterial and venous blood circuits connected to the patient's blood vessels. The blood flowing in from the artery is then dialyzed with the dialysate in the dialyzer 3 and then discharged to the venous side. In this embodiment, the tube pump 2 is located upstream of the dialyzer 3, i.e., on the arterial side, and the drip chamber 4 is located between the tube pump 2 and the dialyzer 3. The drip chamber 4 described above comprises a cap 4a with an elastic tube for the tube pump 2 attached to the center, and a case 4b with an elastic tube for the dialyzer 3 attached to its lower end, and the cap 4a and case 4b are sealed together in an airtight manner. The elastic tube attached to the cap 4a has its tip located inside the case 4b. The blood pumped from the tube pump 2 falls into the case 4b from the tip of the elastic tube connected above the drip chamber 4, and is then pumped to the dialyzer 3 from the elastic tube connected below the case 4b.

[0009] The tube pump 2 described above comprises a housing 11 on which an elastic tube is arranged along a substantially horseshoe-shaped side wall 11a, a rotor 12 rotatably mounted inside the side wall 11a of the housing 11, and rollers 13 provided on the rotor 12 that move along the side wall 11a, and the rotor 12 is driven by a motor (not shown). Of the elastic tubes constituting the blood circuit 1 described above, a large-diameter tube 1a is used in the portion attached to the tube pump 2, and small-diameter tubes 1b are connected to both ends of the large-diameter tube 1a via connectors 1c. In this embodiment, the small-diameter tube 1b connected to the lower end of the large-diameter tube 1a is attached to the patient's artery side, and the small-diameter tube 1b connected to the upper end is connected to the patient's venous side, i.e., the dialyzer 3. In this embodiment, the large-diameter tube 1a had an outer diameter of 12 mm and an inner diameter of 8 mm, while the small-diameter tube 1b had an outer diameter of 6.6 mm and an inner diameter of 4.4 mm.

[0010] As shown in Figure 2, the substantially horseshoe-shaped side wall 11a formed in the housing 11 has a closed section A having a circular arc with radius r1 centered on the rotation center C1 of the rotor 12, and a detached section B provided adjacent to the closed section A on the upstream and downstream sides in the rotational direction of the rotor 12. The shape of the detachment section B will be described in detail later, but a part of it has a support section B2 in which the side walls 11a constituting the detachment section B are parallel to each other, and when the large-diameter tube 1a is attached to the housing 11, the upstream and downstream ends of the large-diameter tube 1a are positioned in these support sections B2.

[0011] As shown in Figure 1, between the two side walls 11a that constitute the support section B2, there is a retaining block 14 for holding the large-diameter tube 1a in the housing 11, and a gripping piece 14a provided on the retaining block 14. Furthermore, engagement portions are formed at the end of the detachment section B in the housing 11 and at the end of the retaining block 14, respectively, for engaging the connectors 1c at both ends of the large-diameter tube 1a. With such a configuration, when mounting the large-diameter tube 1a on the tube pump 2, first, with the connector 1c engaged with the engagement portion, the large-diameter tube 1a is arranged along the side wall 11a, and then the holding block 14 is fixed to the housing 11, so that the end of the large-diameter tube 1a is held by the gripping piece 14a.

[0012] In this embodiment, the rotor 12 is configured to rotate in the clockwise direction as shown in the figure, and two rollers 13 are provided at positions facing each other across the rotation center C1 of the rotor 12. Each roller 13 is maintained in a state of being biased outward by a spring (not shown). Also, guide pins 12a are provided at positions adjacent to the upstream and downstream sides in the rotation direction of the rotor 12 across the roller 13, so as to prevent the large-diameter tube 1a from falling off during the rotation of the rotor 12. In this embodiment, the diameter of each roller 13 is 18 mm, and the center of the roller 13 is moved to a position with a radius of 30.3 mm with respect to the rotation center C1 of the rotor 12 by being biased outward by the spring. On the other hand, Laura 13 When the large-diameter tube 1a is compressed by the above, the roller 13 moves toward the rotation center C1 against the force of the spring, and the center of the roller 13 moves to a position with a radius of 30 mm with respect to the rotation center C1 of the rotor 12. That is, the roller 13 is movable 0.3 mm in the radial direction.

[0013] Next, the closed section A set on the side wall 11a of the housing 11 has an arc shape with a radius r1 centered on the rotation center C1 of the rotor 12. In this embodiment, the radius r1 is set to 42.5 mm. While the roller 13 moves in this closed section A, the roller 13 compresses the large-diameter tube 1a between it and the side wall 11a, so as to block the space located upstream of the position of the roller 13 and the space adjacent to the downstream side. As a result, when the roller 13 moves through the blocked section A, the portion compressed by the roller 13 also moves, causing the liquid located downstream of the compressed portion to be sent towards the downstream dialyzer 3. Furthermore, in this embodiment, the blocked section A is formed in a range of at least 180° as shown in Figure 2, and so when the two rollers 13 are simultaneously located in the blocked section A (state X shown in Figure), the large-diameter tube 1a between the two rollers 13 is two Laura 13 This creates a sealed state.

[0014] Figure 3 shows an enlarged view of section III in Figures 1 and 2. The detachment section B is provided downstream of the rotor 12 in the rotational direction relative to the closure section A. The tube pump 2 of this embodiment is characterized by having a pressure relief section C between the closure section A and the detachment section B. To begin with, the pressure relief section C is composed of an arcuate surface 21 with radius r2, and a connecting section D consisting of an inclined surface 22 is formed between the closed section A and the pressure relief section C. The arcuate surface 21 has a radius r2 that is larger than the radius of the side wall 11a that constitutes the closed section A, and in this embodiment, the radius r2 of the arcuate surface 21 is set to 43.1 mm. Here, when the radius r1 of the occluded section A is set to 100, the ratio of the radius r2 of the arcuate surface 21 should preferably be set in the range of 101.4 to 101.7%, taking into consideration the size of the opening formed in the large-diameter tube 1a, which will be explained below. The inclined surface 22 is formed between the closed section A and the arcuate surface 21, and the boundary between the closed section A and the inclined surface 22, as well as the boundary between the inclined surface 22 and the arcuate surface 21, are smoothly connected.

[0015] With this configuration, when the roller 13 moves onto the arcuate surface 21 of the pressure relief section C, the pressure on the large-diameter tube 1a by the roller 13 is reduced. As a result, the large-diameter tube 1a attempts to return to its original shape due to elastic force, and a communication opening is formed in the portion that was previously blocked by the roller 13, connecting the space upstream of the roller 13 with the space downstream of the roller 13. The size of the above-mentioned communication opening is preferably in the range of 0.1 to 0.2 mm, or in the range of 1.3 to 2.5% of the inner diameter of the large-diameter tube 1a. If the size of the above-mentioned communication opening is less than 1.3% of the inner diameter of the large-diameter tube 1a, liquid will hardly flow between the upstream and downstream spaces of the roller 13, and therefore the effects described below may not be fully obtained. On the other hand, if the size of the communication opening exceeds 2.5% of the inner diameter of the large-diameter tube 1a, the communication opening becomes too large, allowing a large amount of liquid to flow between the upstream and downstream spaces of the roller 13, making it impossible to suppress pulsation. Furthermore, the size of the communication opening formed in the large-diameter tube 1a can also be adjusted by the difference between the radius r1 of the closed section A and the radius r2 of the arcuate surface 21 of the pressure relief section C, the biasing force of the spring that biases the roller 13, and the amount of radial movement of the roller 13.

[0016] The above-mentioned detachment section B comprises a compression amount change section B1 formed such that the side wall 11a gradually moves away from the rotation center C1 of the rotor 12, and the support section B2 formed in the illustrated horizontal direction for supporting the end of the large-diameter tube 1a that the rotor 12 has detached from the elastic tube. The shape of the side wall 11a in the compression amount change section B1 is set so that the pressure on the large-diameter tube 1a gradually decreases as the roller 13 moves. Specifically, it is set so that the volume Vin of the liquid delivered by the roller 13 does not fall below the volume Vout that increases when the roller 13 detaches from the large-diameter tube 1a and the large-diameter tube 1a returns to its original state (volume Vin - volume Vout > 0). First, the volume Vout mentioned above represents the amount of expansion of the internal volume of the large-diameter tube 1a as the pressure on the large-diameter tube 1a by the roller 13 is released and the large-diameter tube 1a returns to its original position due to elastic force while the roller 13 moves through the compression amount change section B1. In contrast, volume Vin is the amount of liquid delivered to the downstream side of the portion compressed by the roller 13 when the roller 13 moves through the occluded section A by the same distance that the roller 13 moves through the compression amount change section B1. Thus, the side wall 11a in the above compression amount change section B1 is such that the relationship volume Vin - volume Vout > 0 holds true. Laura 13 Although it is set to be separated from the center, in this embodiment, as shown in Figure 2, the crushing amount change section B1 has an arc shape with radius r3, with center C2 being offset from the rotation center C1 of the rotor 12.

[0017] The operation of the tube pump 2 having the above configuration will be described below. First, the tube pump 2 is attached to the blood circuit 1 of the dialysis machine, and the large-diameter tube 1a is attached to the housing 11 as shown in Figure 1. Subsequently, once the blood circuit 1 is ready for priming and dialysis treatment by the dialysis machine is started, the rotor 12 of the tube pump 2 rotates, and the tube pump 2 draws blood from the patient's blood vessels (arteries) and sends the blood toward the dialyzer 3. In dialyzer 3, the blood passes through a blood chamber formed in dialyzer 3, undergoing dialysis with the dialysate circulating in the dialysate chamber. After passing through the blood chamber, the blood is returned to the patient's blood vessels (veins).

[0018] In the tube pump 2, as the rotor 12 rotates, the roller 13 moves through the occluded section A, causing the portion of the large-diameter tube 1a that is compressed by the roller 13 to move, and the blood located downstream of the roller 13 is pushed out towards the dialyzer 3. Here, when the tube pump 2 pumps blood toward the dialyzer 3, resistance is generated as the blood passes through the dialyzer 3. As a result, the pressure inside the elastic tube between the tube pump 2 and the dialyzer 3 becomes positive due to the pressure pumped by the tube pump 2 and the resistance as the blood passes through the dialyzer 3. On the other hand, in the blocked section A, the large-diameter tube 1a is compressed by the roller 13, so the spaces located upstream and downstream of the roller 13 are blocked off, which creates a pressure difference between the space upstream and downstream of the roller 13.

[0019] Next, when the roller 13 moves from the blocked section A to the pressure relief section C, the side wall 11a is separated from the rotation center C1 of the rotor 12, so the pressure on the large-diameter tube 1a by the roller 13 decreases, and a small communication opening is formed in the large-diameter tube 1a that connects the space upstream and the space downstream of the roller 13. As a result, the pressure in the space downstream of roller 13 is higher than the pressure in the space upstream of roller 13, causing the blood that was previously located downstream of roller 13 to flow backward towards the space upstream. However, in this embodiment, since the pressure relief section C has an arc shape that is spaced away from the rotation center C1 of the rotor 12 within the range described above, the communication port is smaller than the original inner diameter of the large-diameter tube 1a, and the size of the communication port is as described above Laura 13 The pressure is kept constant until it passes through the pressure relief section C. As a result, while the roller 13 passes through the pressure relief section C, small amounts of blood flow from the space upstream of the roller 13 to the space downstream of the roller 13, and the differential pressure between the space upstream and the space downstream of the roller 13 is gradually eliminated or reduced. In other words, since the blood located downstream of the roller 13 is prevented from rapidly flowing back into the space upstream, blood pulsation can be prevented downstream of the tube pump 2.

[0020] Next, as the roller 13 moves from the pressure relief section C to the compression amount change section B1 of the departure section B, the side wall 11a gradually separates from the rotation center C1 of the rotor 12, and the communication opening that connects the space on the upstream side of the roller 13 and the space on the downstream side expands. As the communication opening expands in this way, the large-diameter tube 1a in the portion compressed by the roller 13 attempts to return to its original shape due to elastic force, and the volume of the portion compressed by the roller 13 gradually expands. As the volume expands, blood located near the area that was being compressed by the roller 13 is drawn into the expanded area, and in particular, blood that was previously located downstream of the roller 13 tends to flow backward. However, as described above, the compression amount change section B1 in this embodiment is set so that the volume Vin of the liquid delivered by the roller 13 does not fall below the volume Vout that increases due to the restoration of the elastic tube. As a result, while the roller 13 moves through the compression change section B1, the volume Vout of the portion of the large-diameter tube 1a that is compressed by the roller 13 gradually expands. However, since the volume Vin of the delivered fluid is larger, backflow of blood located downstream of the roller 13 is suppressed, and blood pulsation in the blood circuit 1 is suppressed.

[0021] Next, the effect of the tube pump 2 provided with the pressure relief section C according to this embodiment on suppressing blood backflow was evaluated. In this evaluation, a tube pump 2 was used as a comparison target, with the location where the pressure relief section C is formed designated as occluded section A, and the rest of the tube pump 2 being the same dimensions. First, as in the case of dialysis treatment, the elastic tubes constituting the blood circuit 1 were attached to the tube pump 2, and the dialyzer 3 and drip chamber 4 were connected to the elastic tubes. Then, just like in dialysis treatment, the tube pump 2 was activated, and blood (in this case, water) was delivered from the tube pump 2 to the dialyzer 3 via the drip chamber 4, and the tip of the elastic tube facing the inside of the drip chamber 4 was observed. As described above, since the tip of the elastic tube provided on the tube pump 2 is located inside the case 4b from the cap 4a of the drip chamber 4, if backflow of liquid occurs in the tube pump 2, the liquid that has been delivered to the tip of the elastic tube will recede, and air from inside the drip chamber 4 will enter the tip of the tube. Therefore, in this evaluation, when liquid was pumped by the tube pump 2 described above, the magnitude of the backflow was evaluated by measuring the maximum distance (maximum receding amount) from the tip of the elastic tube to the tip of the liquid when the liquid that reached the tip of the elastic tube backflowed. The experimental results showed that the maximum retraction distance when using the tube pump 2 according to this embodiment was 14 mm on average, while the maximum retraction distance when using a conventional tube pump 2 without a pressure relief section C was 43 mm on average. From the above, it was confirmed that by using a tube pump 2 equipped with a pressure relief section C as in this embodiment, the backflow of blood can be suppressed as much as possible. And by suppressing this backflow of blood, the pulsation of blood associated with backflow is suppressed. Ra, Do This eliminates problems such as air bubbles forming in the lip chamber 4 and reduced effectiveness of anticoagulants.

[0022] In the above embodiment, a configuration in which a dialyzer 3 is provided downstream of the tube pump 2 was described. However, the tube pump 2 according to the present invention is suitable not only for cases where a device that resists the flow of liquid is provided downstream of the tube pump 2, but also for cases where a device that resists the flow of liquid is provided downstream of the tube pump 2. [Explanation of Symbols]

[0023] 1a Large diameter tube (elastic tube) 2 Tube pump 3 Dialyzer 4 Drip Chamber 11 Housing 11a Side wall 12 Rotor 13 Roller A Blocked section B Departure section B1 Section where the amount of compression changes B2 Support section

Claims

[Claim 1] A tube pump for the blood circuit of a dialysis machine, comprising: a housing on which an elastic tube is disposed along a substantially horseshoe-shaped side wall; a rotor rotatably provided inside the side wall of the housing; and a roller provided on the rotor that moves along the side wall, In a tube pump, the above-mentioned side wall has an arc of a predetermined radius centered on the rotation center of the rotor, and comprises a closing section that compresses and closes the elastic tube between the roller and the side wall, and a release section provided downstream of the closing section and having a shape that gradually moves away from the rotation center, The above-mentioned side wall includes a pressure relief section between the above-mentioned closed section and the above-mentioned detached section, which has a circular arc with a larger radius than the above-mentioned closed section, centered on the rotational center of the rotor. A tube pump characterized in that, while the roller moves through the pressure relief section, a tiny communication opening is formed in the elastic tube compressed by the roller, connecting the upstream and downstream portions of the roller, and the size of the communication opening is kept constant.

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