Patent ID: 12203466

DESCRIPTION OF EMBODIMENTS

Embodiment

An embodiment of the invention will be described below in conjunction with the appended drawings.

(Blood Purification Apparatus)

Firstly, a blood purification apparatus in which a diaphragm pump of the present embodiment is used will be described.FIG.1is a schematic configuration diagram illustrating a blood purification apparatus in the present embodiment.

As shown inFIG.1, a blood purification apparatus10includes a liquid supply flow path13to supply a supply liquid to a blood circuit11extracorporeally circulating blood of a patient or to a blood purifier12provided on the blood circuit11, and a waste liquid flow path14to discharge a waste liquid from the blood purifier12.FIG.1shows an example in which the liquid supply flow path13is a dialysate flow path13ato supply a dialysate to the blood purifier12. However, it is not limited thereto, and the liquid supply flow path13may be a replenishing liquid flow path to supply a replenishing liquid directly to the blood circuit11, or may include both the dialysate flow path13aand the replenishing liquid flow path.

The blood circuit11is composed of, e.g., a flexible tube, etc. A blood pump111, the blood purifier12and a gas-liquid separator112are sequentially provided on the blood circuit11from the upstream to the downstream of a blood flow. The blood pump111is a liquid feed pump to send blood. The gas-liquid separator112is a device to remove air bubbles from the blood.

From a RO (Reverse Osmosis) device (not shown) which produces clean water (referred to as dialysis water) using a reverse osmosis membrane (RO membrane), dialysis water is supplied to the dialysate flow path13a. Two types of undiluted dialysate fluids, an undiluted fluid A and an undiluted fluid B, are also supplied to the dialysate flow path13a. The two undiluted fluids are respectively stored in undiluted fluid storage tanks151, and the undiluted fluid A and the undiluted fluid B are supplied to the dialysate flow path13arespectively from the undiluted fluid storage tanks151via undiluted fluid flow paths152. Undiluted fluid injection pumps153, which are liquid feed pumps pumping out the undiluted fluid A or the undiluted fluid B, are respectively provided on the two undiluted fluid flow paths152. The undiluted fluid A and the undiluted fluid B are mixed with the dialysis water in the dialysate flow path13aand the dialysate is thereby prepared. The prepared dialysate is introduced into the blood purifier12via a duplex pump16.

The waste liquid from the blood purifier12is discharged through the waste liquid flow path14. The duplex pump16is provided over the dialysate flow path13aand the waste liquid flow path14and performs pump operation so that an amount of the dialysate introduced into the blood purifier12is equal to an amount of the waste liquid discharged from the blood purifier12. In addition, a water removal flow path14ais provided on the waste liquid flow path14so as to bypass the dual pump16, and a water removal pump17is provided on the water removal flow path14a. When the water removal pump17is driven, the amount of the waste liquid discharged from the blood purifier12becomes larger than the amount of the dialysate introduced into the blood purifier12and water is removed from the blood. It is possible to adjust the amount of water removed from the blood by adjusting the amount of liquid sent by the water removal pump17.

In the blood purification apparatus10of the present embodiment, a diaphragm pump1of the invention is used as at least one of liquid feed pumps provided on the blood circuit11, the liquid supply flow path13(the dialysate flow path13ain this example) and the waste liquid flow path14. AlthoughFIG.1shows an example in which the diaphragm pump1is used as the water removal pump17, it is not limited thereto. The diaphragm pump1can be used as the other liquid feed pump such as the blood pump111, the undiluted fluid injection pump153or the duplex pump16.

The configuration ofFIG.1is only an example and a specific configuration of the blood purification apparatus10can be changed appropriately.

(Diaphragm Pump1)

FIG.2Ais a schematic configuration diagram illustrating the diaphragm pump1in the present embodiment,FIG.2Bis a cross-sectional view showing a case, andFIG.2Cis a schematic configuration diagram illustrating a reciprocating pump. As shown inFIGS.2A to2C, the diaphragm pump1includes a case2, a diaphragm3dividing a space in the case2into a first space2aand a second space2b, a liquid feed flow path4having an inflow path4ato introduce a liquid to be fed (the waste liquid in case of the water removal pump17) into the first space and a outflow path4bto discharge the liquid to be fed from the first space2a, a drive unit5to repeatedly cause displacement of the diaphragm3by repeating compression and decompression of a driving fluid filling the second space2b, a valve mechanism6capable of opening and closing the inflow path4aand the outflow path4b, and a control unit7.

The case2is composed of a hard resin molded article, etc. The case2integrally includes a first connection part21being in communication with the first space2aand connected to the inflow path4aand a second connection part22being in communication with the first space2aand connected to the outflow path4b. The case2also integrally includes a protruding part23that is in communication with the second space2band protrudes outward. The diaphragm pump1also includes a socket part24which is provided separately from the case2and into which the protruding part23is inserted and connected. Although it is not shown, a driving flow path53(described later) is connected to the socket part24, and the driving flow path53is communicated with the second space2bby inserting and connecting the protruding part23to the socket part24. The case2is configured to be removable from the socket part24by detaching the protruding part23from the socket part24, which allows the case2to be disposable. In this regard, the case2does not need to be entirely disposable and may be configured to be splittable on, e.g., the second space2bside relative to the diaphragm3so that only a portion of the case2including the first space2acan be disposable. It is not necessary to separately form the case2and the socket part24, and the case2may be integrally formed with the socket part24.

The diaphragm3is a flexible membrane and is provided in the case2so as to divide an internal space of the case2into two spaces, the first space2aand the second space2b. Materials of the case2and the diaphragm3are not specifically limited.

The inflow path4aand the outflow path4bare in communication with the first space2aof the case2. However, it is not limited thereto. It may be configured such that the inflow path4aand the outflow path4bare connected and a connection flow path extending from the connected portion therebetween is in communication with the first space2aof the case2. In this case, the case2needs to have only one connection port to the first space2aand it is thus possible to reduce the number of components such as sealing member and to reduce the cost.

An inflow-side solenoid valve6acapable of opening and closing the inflow path4ais provided on the inflow path4a. An outflow-side solenoid valve6bis provided on the outflow path4b. The inflow-side solenoid valve6aand the outflow-side solenoid valve6bconstitute the valve mechanism6and are controlled to be opened and closed by the control unit7.

The valve mechanism6is controlled by the control unit7to open and close the inflow path4aand the outflow path4baccording to displacement of the diaphragm3. In more detail, by opening the inflow-side solenoid valve6aand closing the outflow-side solenoid valve6bin a decompression step and a compression relief step described later, the liquid to be fed is introduced (sucked) into the first space2afrom the inflow path4a. On the other hand, by closing the inflow-side solenoid valve6aand opening the outflow-side solenoid valve6bin a compression step and a decompression relief step described later, the liquid to be fed is sent out from the first space2ato the outflow path4b. The liquid is fed by repeating this operation.

The drive unit5has a compression/decompression device51and a pressure release mechanism52. The compression/decompression device51repeatedly causes displacement of the diaphragm3by repeating compression and decompression of the driving fluid filling the second space2b. In the present embodiment, a reciprocating pump51ais used as the compression/decompression device51.

The reciprocating pump51ais also called a plunger pump or a piston pump, and has a cylinder511in communication with the second space2bvia the driving flow path53, a plunger512(or a piston) provided so as to be able to advance and retract within the cylinder511, and a plunger driving part513to advance and retract the plunger512.

A positive and negative pressure source such as compressor or vacuum generator can be used as the compression/decompression device51, but in this case, a regulator to control the pressure or a flow path switching mechanism needs to be provided and the system configuration thus becomes complicated and large and operating sound is also loud. Meanwhile, a peristaltic pump configured to squeeze a tube can be also used as the compression/decompression device51, but as compared to the reciprocating pump51awhich is used as the compression/decompression device51in the present embodiment, a worn part needs to be replaced since the squeezed tube deteriorates over time or operating sound from the squeezed part is loud. By using the reciprocating pump51aas the compression/decompression device51, the size can be small with a simple system configuration and the operating noise can also be reduced.

The second space2b, the driving flow path53and the cylinder511are filled with the driving fluid and it is possible to compress/decompress the driving fluid by advancing/retracting the plunger512within the cylinder511by the plunger driving part513of the reciprocating pump51a. In the present embodiment, air is used as the driving fluid. As the plunger driving part513, it is possible to use, e.g., a stepping motor.

The pressure release mechanism52is to release pressure of the driving fluid (to bring the pressure closer to the atmospheric pressure) after the driving fluid is compressed or decompressed by the reciprocating pump51aas the compression/decompression device51. The pressure release mechanism52has a pressure release flow path521with one end in communication with the second space2band the other end opened to the atmosphere, and a pressure release valve522provided on the pressure release flow path521to open/close the pressure release flow path521. In the example shown in the drawing, the pressure release flow path521is connected at one end to the driving flow path53and is in communication with the second space2bvia the driving flow path53.

In the present embodiment, the other end of the pressure release flow path521is opened to the atmosphere since air is used as the driving fluid. In this regard, when a liquid is used as the driving fluid, the other end of the pressure release flow path521should be connected to a container for storing this liquid. The container for storing the liquid may be opened to the atmosphere or may be, e.g., expandable and contractable in a balloon like manner. However, since use of a liquid as the driving fluid makes handling difficult, it is more desirable to use the air as the driving fluid. In addition, the pressure to which the driving fluid is released is the atmospheric pressure in the present embodiment, but it is not limited thereto. The pressure to which the driving fluid is released may not be the atmospheric pressure.

An air filter531is provided in the driving flow path53. The air filter531is a so-called hydrophobic filter, and is configured to allow gases to pass therethrough but to not allow liquids to pass therethrough (very high resistance to the passage of liquids). Furthermore, a pressure sensor532to measure the pressure of the driving fluid is provided on the driving flow path53on the reciprocating pump51aside relative to the air filter531. In the event that, e.g., the liquid to be fed leaks to the second space2bdue to damage on the diaphragm3, etc., the air filter531gets wet and pressure of the driving fluid when performing compression by the reciprocating pump51abecomes higher. Thus, the control unit7can detect failure of the diaphragm pump1by determining whether an output value of the pressure sensor532is more than a predetermined threshold.

In addition to the failure detection mentioned above, the control unit7controls opening and closing of the valve mechanism6, driving of the reciprocating pump51aas the compression/decompression device51, and opening and closing of the pressure release valve522of the pressure release mechanism52. The control unit7is realized by appropriately combining an arithmetic element such as CPU, a storage device such as memory, a software, and an interface, etc.

Next, the drive control of the reciprocating pump51aand the opening/closing control of the pressure release valve522by the control unit7will be described. As shown inFIG.3, the control unit7sequentially and repeatedly performs a decompression step (Step S1), a decompression relief step (Step S2), a compression step (Step S3), a compression relief step (Step S4), and a plunger position adjustment step (Step S5).

In the decompression step of Step S1, the plunger512is firstly retracted from a reference position in Step S11, and whether a predetermined time has elapsed is determined in Step S12. When the determination made in Step S12is No, the process returns to Step S11. When the determination made in Step S12is Yes, the plunger512is stopped in Step S13. The reference position in the present embodiment is a position of the plunger512when fully pushed (the most advanced position). By performing the decompression step, the driving fluid is decompressed and the diaphragm3is displaced such that the volume of the first space2aincreases. At this time, the control unit7opens the inflow-side solenoid valve6aand closes the outflow-side solenoid valve6b, and the liquid to be fed is thereby introduced (sucked) into the first space2afrom the inflow path4a.

In the decompression relief step of Step S2, after the driving fluid is released to the atmospheric pressure by opening the pressure release valve522in Step S21, the pressure release valve522is closed in Step S22. Since pressure of the driving fluid becomes the atmospheric pressure by performing the decompression relief step, the diaphragm3returns to a no-load position. Before opening the pressure release valve522in Step S21, the control unit7closes the inflow-side solenoid valve6aand opens the outflow-side solenoid valve6bso that the liquid to be fed does not flow back. In this regard, the outflow-side solenoid valve6bmay be closed.

In the compression step of Step S3, the plunger512is advanced in Step S31, and whether a predetermined time has elapsed is determined in Step S32. When the determination made in Step S32is No, the process returns to Step S31. When the determination made in Step S32is Yes, the plunger512is stopped in Step S33. By performing the compression step, the driving fluid is compressed and the diaphragm3is displaced such that the volume of the first space2adecreases. At this time, the control unit7maintains the state in which the inflow-side solenoid valve6ais close and the outflow-side solenoid valve6bis open, and the liquid to be fed is thereby sent out from the first space2ato the outflow path4b.

Since the air is sucked from the outside by the decompression relief step of Step S2, the volume of the driving fluid filling the second space2b, the driving flow path53and the cylinder511is larger at the time of the compression step than at the time of the decompression step. Thus, if, e.g., the plunger512is advanced to the reference position in the compression step, the driving fluid may be excessively compressed, causing problems such as damage on the diaphragm3. Therefore, in case that pressure (absolute value) at the time of compression and pressure (absolute value) at the time of decompression are set to approximately the same, a travel distance of the plunger512needs to be smaller at the time of the compression step than at the time of the decompression step. In the present embodiment, the travel distance of the plunger512at the time of the compression step is smaller than that at the time of the decompression step.

In the compression relief step of Step S4, the driving fluid is released to the atmospheric pressure by opening the pressure release valve522in Step S41. Since pressure of the driving fluid becomes the atmospheric pressure by performing the compression relief step, the diaphragm3returns to the no-load position. At this time, the control unit7opens the inflow-side solenoid valve6aand closes the outflow-side solenoid valve6bso that the liquid to be fed does not flow back. In this regard, the inflow-side solenoid valve6amay be closed. Then, the inflow-side solenoid valve6amay be opened after driving the plunger512in the plunger position adjustment step of Step S5in a closed state of the both solenoid valves6aand6bwhich are closed in the compression relief step of Step S4, or in case of repeating Step S1again after Step S5, the inflow-side solenoid valve6amay be opened after driving the plunger512in Step S1.

In the plunger position adjustment step of Step S5, the plunger512is advanced to the reference position (in this example, the position of the plunger512when fully pushed) in Step S51and the plunger512is stopped in Step S52, and after that, the pressure release valve522is closed in Step S53. In the present embodiment, since the travel distance of the plunger512at the time of the compression step is smaller than that at the time of the decompression step as described above, it is necessary to return the plunger512to the reference position by the plunger position adjustment step. In case that pressure (absolute value) at the time of compression is set to higher than pressure (absolute value) at the time of decompression, the plunger512can be moved to the reference position in the compression step and the plunger position adjustment step of Step S5can be omitted. In case that the plunger512is advanced beyond the reference position in the compression step, the plunger512should be retracted and returned to the reference position in the plunger position adjustment step.

After that, in Step S6, the control unit7determines whether to end the pump operation. When the determination made in Step S6is No, the process returns to the decompression process of Step S1. When the determination made in Step S6is Yes, the process ends. The pump operation is ended when, e.g., the output value of the pressure sensor532exceeds a predetermined threshold or when a termination command by an operation of a user or a program, etc., is input to the control unit7.

In the diaphragm pump1of the present embodiment, after the plunger512is retracted in the decompression step, it is opened to atmosphere and the plunger512is then advanced in the compression step, hence, a travel region of the plunger512in the cylinder511when decompressing and that when compressing can be the same, as shown inFIG.4A. Therefore, the travel distance (stroke distance) of the plunger512can be reduced, which contributes to size reduction of the reciprocating pump51aand size reduction of the entire diaphragm pump1.

In contrast to this, in a conventional diaphragm pump which does not include the pressure release mechanism52, after retracting the plunger512in the decompression step, pressure of the fluid to be fed and pressure of the driving fluid are balanced by advancing the plunger512in the compression step, and after that, the plunger512needs to be further advanced to compress the driving fluid, hence, the travel region of the plunger512in the cylinder511when decompressing is different from that when compressing, as shown inFIG.4B. Therefore, in the conventional structure, the travel distance (stroke distance) of the plunger512is long and the size of the reciprocating pump51ais thus large. In this regard, it is conceivable to increase a cross-sectional area of the cylinder511to reduce the travel distance (stroke distance) of the plunger512, but in this case, a pressure-receiving area of the plunger512increases and the plunger driving part513which drives the plunger512is thus increased in size.FIGS.4A and4Bshow that the diaphragm3at the time of decompression moves toward a broken line and how the diaphragm3at the time of compression moves toward a dash-dot line.

When the diaphragm pump1is used as, e.g., a blood pump, blood flows through the liquid feed flow path4and the first space2a, hence, it is desirable that the liquid feed flow path4and the case2be removable from the driving flow path53and be disposable. Even when the diaphragm pump1is used as another liquid feed pump, configuring the liquid feed flow path4and the case2to be removable from the driving flow path53and to be disposable eliminates time and effort for cleaning and improves the convenience. Furthermore, by configuring the liquid feed flow path4and the case2to be disposable, it is also possible to suppress a decrease in discharge accuracy due to deterioration over time, precipitation of calcium carbonate in the dialysate or adhesion of proteins contained in the waste dialysate. In this regard, the case2does not need to be entirely disposable and may be configured to be splittable on, e.g., the second space2bside relative to the diaphragm3so that only a portion of the case2including the first space2acan be disposable.

(Modification) Although the position of the plunger512when fully pushed is set as the reference position in the present embodiment, the reference position can be appropriately set. In this case, however, to return the plunger512to the reference position, it is necessary to provide a plunger position detection unit514capable of detecting that the plunger512is located at the reference position. As the plunger position detection unit,514it is possible to use, e.g., an encoder that detects a rotational speed of a motor used for the plunger driving part513, etc., or a linear potentiometer that directly detects the position of the plunger512, etc. In addition, when using a stepping motor (pulse motor) as the plunger driving part513, it is possible to detect the position of the plunger512also based on a driving amount (a number of output pulses) of the stepping motor. Furthermore, as the plunger position detection unit,514it also possible to use a contact type sensor such as limit switch, strain gauge or piezoelectric element sensor and it is also possible to use a non-contact sensor such as photoelectric sensor or pressure sensor.

A diaphragm position detection unit19to detect a position of the diaphragm3may be further provided. The diaphragm position detection unit19may be configured to detect the position of the diaphragm3using, e.g., a sensor or the like such as photoelectric sensor. It is also possible to estimate the position of the diaphragm3by using the detection result of the encoder or linear potentiometer mentioned above, or the driving amount of the stepping motor, or an output of the pressure sensor532. In case that the diaphragm position detection unit19is provided, the control unit7ends the decompression step when the position of the diaphragm3reaches a predetermined decompression position in the decompression step, and ends the compression step when the position of the diaphragm3reaches a predetermined compression position in the compression step.

FIG.5shows a control flow when the plunger position detection unit514and the diaphragm position detection unit19are provided.FIG.5is a modification of the control flow ofFIG.3in which Step S12in the decompression step of Step S1, Step S32in the compression step of Step S3and Step S51of the plunger position adjustment step of Step S5in are changed.

In case that the diaphragm position detection unit19is provided, in the decompression step of Step S1, the plunger512is retracted from the reference position in step S11, and whether the diaphragm3has reached a predetermined decompression position is determined in Step S12based on the detection result or estimation result of the diaphragm position detection unit19. When the determination made in Step S12is No, the process returns to Step S11. When the determination made in Step S12is Yes, the plunger512is stopped in Step S13.

Meanwhile, in the compression step of Step S3, the plunger512is advanced in Step S31, and whether the diaphragm3has reached a predetermined compression position is determined in Step S32based on the detection result or estimation result of the diaphragm position detection unit19. When the determination made in Step S32is No, the process returns to Step S31. When the determination made in Step S32is Yes, the plunger512is stopped in Step S33.

Furthermore, in the plunger position adjustment step of Step S5, the plunger512is advanced in Step S511, and whether the plunger512is located at the reference position is determined in Step S512. When the determination made in Step S512is No, the process returns to Step S511. When the determination made in Step S512is Yes, the plunger512is stopped in Step S52and the pressure release valve522is then closed in Step S53.

Since the travel distance of the plunger512can be controlled more accurately by having the plunger position detection unit,514the discharge amount of the reciprocating pump51acan be controlled with high repetition accuracy. In addition, by using the stepping motor for the plunger driving part513, it is possible to realize the plunger position detection unit514without separately adding a sensor, etc., thereby contributing to the reduction in the number of components, cost reduction, and size reduction. Furthermore, when stopping the reciprocating pump51a, the stopping process can be performed without via a sensor or the like, hence, it is possible to accurately stop the plunger512at a desired position without being affected by a time lag, and the discharge amount and the introduction amount of the reciprocating pump51acan be arbitrarily set with higher accuracy.

In addition, by having the diaphragm position detection unit19and configuring to switch between compression and decompression according to the position of the diaphragm3, it is possible to suppress excessive load on the diaphragm3, to further increase safety by suppressing problems such as damage on the diaphragm3, and to suppress deterioration of the diaphragm3.

Furthermore, the diaphragm3may be configured to be naturally displaced such that the volume of the first space2ais increased by liquid pressure of the liquid to be fed. In this case, by using, e.g., a predetermined liquid feed drive source provided on the upstream side of the inflow-side solenoid valve6ain a state in which the pressure release valve522is opened, the diaphragm3is displaced such that the volume of the first space2ais increased by the liquid pressure of the liquid to be fed, and the liquid to be fed thereby flows into the first space2a. Then, by driving the compression/decompression device51(the reciprocating pump51a) in a state in which the pressure release valve522is closed, the driving fluid is compressed and this causes the diaphragm3to be displaced such that the volume of the second space2bincreases, and the liquid to be fed thereby flows out of the first space2a.

Functions and Effects of the Embodiment

As described above, in the diaphragm pump1of the present embodiment, the drive unit5has the pressure release mechanism52to release pressure of the driving fluid after the driving fluid is compressed or decompressed by the compression/decompression device51(the reciprocating pump51a).

By having the pressure release mechanism52, it is possible to release pressure of the driving fluid after compressing (or decompressing) the driving fluid and then quickly compress (or decompress) the driving fluid. As a result, the cycle time to decompress and compress the driving fluid, i.e., a cycle of displacement of the diaphragm3can be shortened, and the diaphragm pump1having a high flow rate can be realized.

When the pressure release mechanism52is not provided, the diaphragm3gradually returns to the no-load position with the movement of the plunger512after decompression or compression of the driving fluid, and the length of time that a load (tension) is applied to the diaphragm3is longer. By having the pressure release mechanism52as in the present embodiment and releasing the pressure after decompression or compression of the driving fluid, it is possible to reduce the length of time that a load (tension) is applied to the diaphragm3since the diaphragm3instantaneously returns to the no-load position. That is, according to the present embodiment, it is possible to reduce damage on the diaphragm3and possible to realize a long-life diaphragm pump1.

Furthermore, when the pressure release mechanism52is not provided, the driving fluid is sealed in. Therefore, in case that air is used as the driving fluid, the air expands or contracts due to an influence of temperature, and intended displacement of the diaphragm3may not be obtained even if the plunger512is operated with the same stroke, resulting in variation in the liquid feed amount. In addition, when the driving fluid becomes hot and expands, a large load may be applied to the diaphragm3, causing damage on the diaphragm3. According to the present embodiment, by releasing the pressure every time the driving fluid is compressed or decompressed, it is possible to eliminate the influence of temperature of the driving fluid, to suppress problems such as damage on the diaphragm3, and to accurately control the liquid feed amount.

Furthermore, in the present embodiment, when the reciprocating pump51ais used as the compression/decompression device51, the compression/decompression device51can be reduced in size by reducing the travel distance (stroke distance) of the plunger512. In addition, by using the reciprocating pump51aas the compression/decompression device51, it is possible to realize the diaphragm pump1with less vibration and less operating sound than general compressors, etc.

SUMMARY OF THE EMBODIMENT

Technical ideas understood from the embodiment will be described below citing the reference numerals, etc., used for the embodiment. However, each reference numeral, etc., described below is not intended to limit the constituent elements in the claims to the members, etc., specifically described in the embodiment.

[1] A diaphragm pump (1) comprising: a case (2); a diaphragm (3) dividing a space in the case (2) into a first space (2a) and a second space (2b); a liquid feed flow path (4) comprising an inflow path (4a) to introduce a liquid to be fed into the first space (2a) and an outflow path (4b) to discharge the liquid to be fed from the first space (2a); a drive unit (5) comprising a compression/decompression device (51) that repeatedly causes displacement of the diaphragm (3) by repeating compression and decompression of a driving fluid filling the second space (2b); and a valve mechanism (6) to open and close the inflow path (4a) and the outflow path (4b), wherein the drive unit (5) comprises a pressure release mechanism (52) to release pressure of the driving fluid after the driving fluid is compressed or decompressed by the compression/decompression device (51).

[2] The diaphragm pump (1) described in [1], comprising: a control unit (7) that controls the compression/decompression device (51) and the pressure release mechanism (52), wherein the control unit (7) repeatedly performs a decompression step of decompressing the driving fluid by the compression/decompression device (51), a decompression relief step of releasing the pressure of the driving fluid by the pressure release mechanism (52), a compression step of compressing the driving fluid by the compression/decompression device (51), and a compression relief step of releasing the pressure of the driving fluid by the pressure release mechanism (52).

[3] The diaphragm pump (1) described in [2], wherein the compression/decompression device (51) comprises a reciprocating pump (51a) that comprises a cylinder (511) in communication with the second space (2b), a plunger (512) provided so as to be able to advance and retract within the cylinder (511), and a plunger driving part (513) to advance and retract the plunger (512), and compresses and decompresses the driving fluid by advancing and retracting the plunger (512) within the cylinder (511) by the plunger driving part (513).

[4] The diaphragm pump (1) described in [3], wherein the control unit (7) is configured to decompress the driving fluid by retracting the plunger (512) from a reference position in the decompression step, and performs a plunger position adjustment step of moving the plunger (512) to the reference position after the compression relief step.

[5] The diaphragm pump (1) described in [4], comprising: a plunger position detection unit capable of detecting that the plunger (512) is located at the reference position.

[6] The diaphragm pump (1) described in any one of [2] to [5], comprising: a diaphragm position detection unit19to detect a position of the diaphragm (3), wherein the control unit (7) ends the decompression step when the position of the diaphragm (3) reaches a predetermined decompression position in the decompression step, and ends the compression step when the position of the diaphragm (3) reaches a predetermined compression position in the compression step.

[7] The diaphragm pump (1) described in any one of [1] to [6], wherein the driving fluid comprises air, and wherein the pressure release mechanism (52) comprises a pressure release flow path (521) with one end in communication with the second space (2b) and the other end opened to the atmosphere, and a pressure release valve (522) provided on the pressure release flow path (521) to open/close the pressure release flow path (521).

[8] The diaphragm pump (1) described in any one of [1] to [7], comprising: a socket part (24) to which the drive unit (5) is connected, wherein the case (2) and the diaphragm (3) are provided so as to be removable from the socket part (24).

[9] A blood purification apparatus (10), comprising: the diaphragm pump (1) described in any one of [1] to [7] as at least one of liquid feed pumps provided on a blood circuit (11) to extracorporeally circulate blood of a patient, a liquid supply flow path (13) to supply a supply liquid to the blood circuit (11) or to a blood purifier (12) provided on the blood circuit (11), and a waste liquid flow path (14) to discharge a waste liquid from the blood purifier (12).

Although the embodiment of the invention has been described, the invention according to claims is not to be limited to the embodiment described above. In addition, not all combinations of the features described in the embodiment are necessary to solve the problem of the invention.

The invention can be appropriately modified and implemented without departing from the gist thereof. For example, although the example in which the valve mechanism6is composed of a solenoid valve has been described in the embodiment, the valve mechanism6may be composed of a check valve.

REFERENCE SIGNS LIST

1diaphragm pump2case2afirst space2bsecond space3diaphragm4liquid feed flow path4ainflow path4boutflow path5drive unit51compression/decompression device51areciprocating pump511cylinder512plunger513plunger driving part52pressure release mechanism521pressure release flow path522pressure release valve53driving flow path531air filter532pressure sensor6valve mechanism6ainflow-side solenoid valve6boutflow-side solenoid valve7control unit10blood purification apparatus11blood circuit111blood pump112gas-liquid separator12blood purifier13liquid supply flow path13adialysate flow path14waste liquid flow path14awater removal flow path151undiluted fluid storage tank152undiluted fluid flow path153undiluted fluid injection pump16duplex pump17water removal pump19diaphragm position detection unit514plunger position detection unit