JP2006063850A - Reversible valveless pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reversible valveless pump with a simple structure, capable of transferring constant amount of fluid and easily changing the transferring direction of the fluid. <P>SOLUTION: This reversible valveless pump is provided with a cylinder 3; a piston 7 inserted into inside of the cylinder 3 and partitioning a volume variable chamber 5 between a cylinder head 32 of the cylinder 3 and the piston 7 and into which fluid flows; two fluid ports 50, 52 arranged around the periphery of the chamber 5 separated from each other; a drive source 9 arranged in the rear end side of the cylinder 3 and normally or reversely rotating the piston 7; a crank mechanism 11 connected with the drive source 9 and holding the piston 7 so as to allow rotation and reciprocation of the piston 7; and cooperation mechanisms 15a, 15b arranged inside the cylinder 3 and promoting the reciprocation of the piston 7. A tip face of the piston 7 is constituted as an inclined face 7c inclined to a central axis L of the cylinder 3. Thus, when the piston 7 reciprocates while rotating, one of the fluid ports 50, 52 is opened/closed and the other of the fluid ports 50, 52 is closed/opened in accordance with the rotational direction of the piston 7. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an improvement of a piston-type pump that is used in fields such as artificial dialysis, biotechnology, or a fuel cell, and enables fluid to be aspirated and discharged.

  Conventionally, as a piston type fluid pump, a suction port and a discharge port are provided in a chamber of a cylinder into which fluid flows, and a negative pressure relief valve that is driven to open the suction port by a backward movement of the cylinder is provided in the suction port. It is known that a positive pressure relief valve that is driven to open the discharge port by a forward movement of a cylinder is provided at the discharge port.

  Such a piston type fluid pump sucks and discharges fluid by opening and closing a negative pressure relief valve or a positive pressure relief valve by changing the internal pressure in the cylinder chamber to negative pressure or positive pressure by reciprocating movement of the piston. Therefore, the fluid can be sucked and discharged quantitatively.

  However, since this piston type fluid pump is provided with a valve that is driven by a change in the internal pressure in the chamber, not only the structure becomes complicated, but also the valve is driven by a number of times of driving of the valve due to a change in the internal pressure in the chamber. Could break down.

  Thus, conventionally, a so-called valveless pump having no valve has been proposed. Examples of the valveless pump include those described in Patent Document 1 listed below.

  This valveless pump has a cylinder having a fluid suction port and a fluid discharge port, and a piston that is fitted into the cylinder and has a notch on the outer peripheral surface. The piston is connected to the motor via a rotating block so as to be able to rotate and reciprocate. When the piston reciprocates while rotating, the notch of the piston is deflected with respect to each port, and a fixed amount of fluid flows into the inflow chamber through the suction port and is discharged through the discharge port. It is configured.

  Incidentally, in recent years, in the fields of biotechnology, medicine, pharmaceuticals, fuel cells, and the like, there is an increasing need for a pump that can switch the direction of fluid transfer. Particularly in the fields of biotechnology and pharmaceuticals, a plurality of microcircuits having a diameter of several microns are assembled or branched, and a plurality of types of liquids are transferred to a plurality of microcircuits while being controlled in flow rate, and mixed in the microcircuits. After that, there is an increasing need for a small pump that can reversely transfer liquid toward the supply source.

  However, the conventional pumps including the pump described in Patent Document 1 cannot meet the above-mentioned social demands.

In the valveless pump disclosed in Patent Document 1, the fluid discharge port and the fluid suction port are specified, and the top dead center position and the bottom dead center position of the piston are configured to be 180 ° opposite to the cylinder. In addition, a fluid discharge port and a fluid suction port are provided at a position corresponding to the top dead center position of the piston and a position corresponding to the bottom dead center position of the piston, respectively. Therefore, the suction port and the discharge port cannot be reversed, and the fluid transfer direction cannot be changed.
JP-A-11-132140

  The present invention provides a reversible rotary valveless pump capable of quantitatively transferring a fluid with a simple structure and capable of easily changing the direction of fluid transfer in view of the above-described social demands. The task is to do.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a cylinder, a piston that is fitted in the cylinder, and defines a variable volume chamber into which a fluid flows into a cylinder head of the cylinder, and a chamber Two fluid inlets and outlets that are spaced apart from each other around the circumference of the cylinder, a drive source that is arranged on the rear end side of the cylinder to rotate the piston forward or backward, and connected to the drive source to rotate and reciprocate the piston. In a reversible rotary valveless pump having a crank mechanism for holding a piston so as to allow and a cooperating mechanism that is disposed in the cylinder and promotes the reciprocating movement of the piston, the front end surface of the piston is placed on the central axis of the cylinder. By configuring as an inclined surface that is inclined with respect to the piston, when the piston reciprocates while rotating, one of the fluid inlets and outlets is opened according to the direction of rotation of the piston. Characterized by being configured as the other of the fluid inlet and outlet can be made closed opening causes made.

  In addition to the structure described in claim 1, the invention described in claim 2 is configured such that when the piston reaches top dead center, the inclined surface of the piston can be brought into full contact with the top inner surface of the cylinder head. The top inner surface of the cylinder head is configured as an inclined surface inclined with respect to the central axis of the cylinder.

  According to a third aspect of the present invention, in addition to the configuration according to the first or second aspect, the cooperating mechanism is configured so that either one of the inner peripheral surface of the cylinder and the outer peripheral surface of the piston is located on the central axis of the cylinder. An annular cam groove formed so as to be inclined, and a cam protrusion provided on either the inner peripheral surface of the cylinder or the outer peripheral surface of the piston and slidably fitted in the annular cam groove. Features.

  According to a fourth aspect of the present invention, in addition to the configuration according to any one of the first to third aspects, the piston extends linearly along the longitudinal direction of the piston, respectively, at the opposed portions of the outer periphery of the rear end portion. A crank mechanism having a straight groove and a crank mechanism having a base connected to a drive source and a pair of clamping pieces extending forward in parallel with each other from the base, and a rear end portion of the piston between the clamping pieces And a stylus is passed through each of the pair of clamping pieces from the direction intersecting the central axis of the piston, and is slidably engaged in the linear groove.

  According to the first aspect of the present invention, two fluid inlets and outlets are provided in the variable volume chamber defined between the cylinder head and the piston, and the tip end surface of the piston is inclined with respect to the central axis of the cylinder. By configuring as a surface, when the piston reciprocates while rotating, one of the two fluid inlets and outlets can be opened and closed and the other of the two fluid inlets can be opened and closed according to the direction of rotation of the piston. Therefore, not only can the direction of fluid transfer be changed easily, but also a simple structure that does not require a negative pressure relief valve and a positive pressure relief valve can be constructed, and the pump can be downsized accordingly. be able to.

  According to the invention described in claim 2, when the piston reaches the top dead center, the top inner surface of the cylinder head can be in contact with the top inner surface of the cylinder head over the entire inclined surface of the piston. Since it is configured as an inclined surface inclined with respect to the central axis of the cylinder, when the piston reaches the top dead center, the fluid can be discharged from the chamber without remaining in the chamber.

  According to the invention described in claim 3, the cooperative mechanism includes an annular cam groove formed on one of the inner peripheral surface of the cylinder and the outer peripheral surface of the piston so as to be inclined with respect to the central axis of the cylinder; Since it is composed of a cam projection that is slidably fitted into the annular cam groove, provided on either the inner peripheral surface of the cylinder or the outer peripheral surface of the piston, the piston can be smoothly moved with an extremely simple structure. It can be reciprocated.

  According to the fourth aspect of the present invention, the linear groove extending linearly along the longitudinal direction of the piston is formed in the opposed portion of the outer periphery of the rear end portion of the piston, and the crank mechanism is used as a drive source. It is composed of a connected base portion and a pair of sandwiching pieces extending forward in parallel with each other from the base portion, and a rear end portion of the piston is arranged between the sandwiching pieces and intersects with the central axis of the piston. Since the stylus is passed through the pair of sandwiching pieces from the direction and slidably engaged in the linear groove, the piston can be held so as to allow the piston to rotate and reciprocate with a very simple configuration. A possible crank mechanism is obtained.

  Hereinafter, a reversible rotary valveless pump according to the best mode of the present invention will be described with reference to the accompanying drawings.

  As shown in FIGS. 1 to 6, the reversible rotary valveless pump 1 according to the present invention is inserted into the cylinder 3 and inserted into the cylinder 3, and the variable volume chamber 5 between the inner surface of the front end of the cylinder 3. And a reversible motor 9 disposed on the rear end side of the cylinder 3. The reversible motor 9 and the piston 7 are connected to each other via a crank mechanism 11.

  The cylinder 3 includes a cylindrical housing portion 30 and a cylinder head 32 that is detachably connected to the front end portion of the housing portion 30. The cylinder head 32 includes a cylindrical portion 32a having an outer diameter substantially the same as the outer diameter of the cylindrical housing portion 30, and a connecting portion 32b protruding rearward from the cylindrical portion 32a. The connecting portion 32 b of the cylinder head 32 has an outer diameter that is slightly smaller than the inner diameter of the housing portion 30. The housing portion 30 and the cylinder head 32 are integrally connected by fitting the connecting portion 32b of the cylinder head 32 into the front end portion of the housing portion 30 and tightening the screw 34 penetrating the side peripheral portion of the housing portion 30. The cylinder 3 is configured. In this way, if the cylinder 3 is configured as an integral cylinder 3 by detachably connecting the housing part 30 and the cylinder head 32 formed separately from each other, the cylinder head 32 is removed from the housing 30, The cylinder head 32, the housing 30, and the piston 7 can be easily cleaned. In addition, you may shape | mold the housing part 30 and the cylinder head 32 as an integral thing.

  The front end portion of the cylinder head 32 is closed, and the chamber 5 into which fluid is sucked is defined by the cylinder head 32 and the front end portion of the piston 7 fitted in the cylinder 3. As shown in FIG. 2, around the chamber 5, there are provided two fluid inlets 50 and 52 that are spaced apart from each other with a predetermined angle in the circumferential direction. Joints 50a and 52a, to which predetermined fluid transfer pipes are connected, are screwed into the fluid ports 50 and 52, respectively. In the illustrated embodiment, the two fluid inlets and outlets 50 and 52 are provided around the circumference of the chamber 5 at a distance of approximately 90 ° from each other.

  As shown in FIGS. 1 and 5, the inner side surface of the top of the cylinder head 32 forms an internal inclined surface 32 c that is inclined at a predetermined angle with respect to the center axis L of the cylinder.

  The piston 7 can be rotated by a reversible motor 9 and is held by a crank mechanism 11 so as to be able to reciprocate along with the rotation. More specifically, as shown in FIG. 4, the crank mechanism 11 includes a base portion 11 a connected to the rotation shaft 9 a of the reversible motor 9 and a pair of sandwiching pieces 11 b extending forward from the base portion 11 a in parallel to each other. , 11b. In this connection, as shown in FIG. 4 and FIG. 6, linear grooves 7 a and 7 a that extend linearly along the longitudinal direction of the piston 7 are formed in the opposed portions of the outer periphery of the rear end of the piston 7. Is formed. The rear end of the piston 7 is loosely inserted between the pair of clamping pieces 11b, 11b of the crank mechanism 11, and the styluses 14, 14 penetrating the clamping pieces 11b, 11b from the direction intersecting the central axis of the piston 7 are inserted. By engaging with the linear grooves 7a and 7a of the piston 7 so as to be relatively movable, the piston 7 is rotated by the reversible motor 9 and is held by the crank mechanism 11 so as to be able to reciprocate while being guided by the styluses 14 and 14. Has been.

  The reversible rotary valveless pump 1 according to the present invention further includes a cooperative mechanism for promoting the reciprocating motion of the piston 7. This cooperating mechanism has an annular cam groove 15a inclined with respect to the center axis L of the cylinder on the outer peripheral surface of a substantially central portion of the piston 7 in the longitudinal direction, and an annular cam projecting inward from a connecting portion 32b of the cylinder head 32. And a cam projection 15b loosely fitted in the groove 15a. The piston 7 is guided to the cam projection 15b by the engagement of the cam projection 15b and the annular cam groove 15a by loosely fitting the cam projection 15b provided on the cylinder head 32 into the annular cam groove 15a formed on the piston 7. While being able to reciprocate smoothly. Since the annular cam groove 15 a is formed to be inclined with respect to the center axis L of the cylinder and is a continuous annular groove, the rotational movement of the piston 7 by the reversible motor 9 can be converted into the reciprocating movement of the piston 7. it can. In the course of the reciprocating motion of the piston 7, when the rearmost portion of the inclined annular cam groove 15a is engaged with the cam projection 15b, the forward movement is switched to the backward movement.

  In the illustrated embodiment, the annular cam groove 15a of the cooperating mechanism is provided in the piston 7 and the cam protrusion 15b of the cooperating mechanism is provided in the cylinder 3. Conversely, the cam protrusion is provided on the outer peripheral surface of the piston 7. An annular cam groove may be provided on the inner peripheral surface of the cylinder 3.

  An annular groove is further provided on the outer peripheral surface of the piston 7, and an annular packing 17 such as an O-ring is fitted in the annular groove in order to prevent fluid leakage. As shown in FIGS. 1 and 5, the tip surface of the piston 7 forms an inclined surface 7c that is inclined at a predetermined angle with respect to the central axis L of the cylinder. Thus, since the tip surface of the piston 7 forms the inclined surface 7c, when the piston 7 reciprocates while rotating, one of the pair of fluid inlets / outlets 50, 52 provided in the chamber 5 is opened. On the other hand, the other of the fluid outlets 50 and 52 is closed on the peripheral surface of the piston 7. The inclination angle of the inclined surface 7c of the piston 7 with respect to the center axis L of the cylinder can be appropriately selected depending on the positional relationship between the pair of fluid inlets / outlets 50 and 52 arranged at a predetermined angle around the circumference of the chamber 5. Is preferably in the range of 60 ° to less than 90 °, most preferably about 60 °.

  The internal inclined surface 32c of the cylinder head 32 is inclined at an angle such that the inclined surface 7c of the piston 7 is in contact with the internal inclined surface 32c of the cylinder head 32 when the piston 7 is located at the top dead center. is doing. When configured in this manner, the fluid can be discharged through one of the fluid inlets 50 and 52 opened without causing the fluid to remain in the chamber 5.

  In the reversible rotary valveless pump 1 according to the present invention configured as described above, the tip surface of the piston 7 forms an inclined surface 7c inclined with respect to the center axis L of the cylinder at a predetermined angle. By reciprocating while rotating, the pair of fluid outlets 50 and 52 formed in the chamber 5 are alternately opened and closed. More specifically, during the 180 ° rotation process of the piston 7, one of the fluid outlets 50 and 52 is opened and the other is closed by the peripheral surface of the piston 7. Furthermore, in the process in which the piston 7 rotates to 360 °, one of the fluid inlets / outlets 50 and 52 is closed by the peripheral surface of the piston 7 and the other is opened. In this way, in the course of one rotation of the piston 7, the fluid inlets and outlets 50 and 52 are alternately opened and closed. As a result, the intake and discharge of a fixed amount of fluid into the chamber 5 are alternately performed in the course of one rotation of the piston 7. Further, by rotating the piston 7 in the reverse direction, the fluid inlet / outlet used as the fluid suction side in the fluid inlet / outlet 50, 52 is used as the fluid outlet, and the fluid inlet / outlet used as the fluid outlet in the fluid inlet / outlet 50, 52 is used. It can be used as a fluid suction port, whereby the direction of fluid transfer can be switched.

  Here, the operation of the reversible rotary valveless pump according to the present invention will be described in more detail with reference to FIGS. In addition, in order to be able to grasp | ascertain clearly the rotation state of piston 7, the vertex of the inclined surface 7c of piston 7 was displayed with the dot in FIGS.

  FIG. 7A shows a state in which the inclined surface 7c of the piston 7 is in contact with the inner inclined surface 32c at the top of the cylinder head 32, that is, the piston 7 is located at the top dead center. FIG. FIG.7 (b) is a DD line end view of the pump in the state shown to Fig.7 (a). In the state shown in FIGS. 7A and 7B, the fluid outlets 50 and 52 are closed by the peripheral surface of the piston 7. In this state, when the piston 7 is rotated by the reversible motor 9 in the direction in which the piston 7 moves backward (counterclockwise direction indicated by an arrow in FIG. 7B), the process until the piston 7 rotates 90 ° 7 (c) to (e), one of the fluid inlets 50, 52 is opened, and the chamber 5 is gradually formed, and the fluid is generated by the negative pressure generated in the chamber 5. Flows into the chamber 5 through the opened one 50 of the fluid inlet / outlet.

  FIG. 8A shows a state in which the piston 7 rotates 90 degrees and moves backward, and the chamber 5 having a substantially half volume is formed between the inclined surface 7 c of the piston 7 and the cylinder head 32. It is. FIG. 8B is an end view taken along line EE of the pump in the state shown in FIG. In the process until the piston 7 is rotated 180 °, as shown in FIGS. 8C to 8E, the volume of the chamber 5 is further increased while the fluid is opened in the fluid inlets 50 and 52. It flows further into the chamber 5 through 50.

  FIG. 9A is a diagram showing a state in which the piston 7 has rotated 180 °, that is, a state in which the piston 7 has reached bottom dead center. FIG. 9B is an end view taken along the line FF of the pump in the state shown in FIG. In this state, the chamber volume between the inclined surface 7c of the piston 7 and the cylinder head 32 is maximized, and the suction operation of the fluid into the chamber is completed. When the piston 7 is rotated 180 °, both the fluid inlets 50 and 52 are opened as shown in FIG. 9B. However, the opening of both the fluid inlets 50 and 52 is instantaneous, and At that moment, since the negative pressure in the chamber 5 is larger than the external pressure, the fluid that has flowed into the chamber 5 does not flow out of the fluid outlets 50 and 52. In the process in which the piston 7 rotates 270 °, the piston 7 moves in the direction of the top dead center, and as shown in FIGS. 9C to 9E, the fluid inlet / outlet 50 that has been opened is closed. At the same time, the volume of the chamber 5 gradually decreases, and the positive pressure generated in the chamber 5 causes the fluid to be discharged out of the chamber 5 through the other fluid inlet / outlet 52.

  FIG. 10A is a view showing a state where the piston 7 is rotated by 270 ° and the volume of the chamber is reduced to approximately half. FIG.10 (b) is the GG line | wire end view of the pump in the state shown to Fig.10 (a). In the process until the piston 7 rotates 360 °, the volume of the chamber 5 is further reduced as shown in FIGS. 10C to 10E, and the fluid is further discharged out of the chamber 5 through the fluid inlet / outlet 52. Will come to be. When the piston 7 rotates 360 °, the inclined surface 7c of the piston 7 is in contact with the inner inclined surface 32c of the cylinder head 32 over the entire surface, and the volume of the chamber is completely eliminated. As a result, all the fluid in the chamber 5 is discharged out of the chamber 5 through the fluid inlet / outlet port 52 and returns to the state shown in FIGS. 7 (a) and 7 (b). In this way, fluid is sucked and discharged by one rotation of the piston 7 at 360 °.

  7A and 7B, the piston 7 rotates counterclockwise when the piston 7 rotates 180 ° in the opposite direction, that is, clockwise. In contrast, the other of the fluid ports 50 and 52 is first opened, and the fluid port 52 used as a fluid suction port remains closed when the piston 7 is rotated counterclockwise. It becomes. The opening of the fluid inlet / outlet 52 allows the fluid to flow into the chamber 5 through the fluid inlet / outlet 52. Thereafter, in the process in which the piston 7 rotates from 180 ° to 360 °, the fluid inlet / outlet port 50 is opened and the fluid inlet / outlet port 52 is closed, so that the fluid flowing into the chamber 5 passes through the fluid inlet / outlet port 50. It will be discharged outside.

  In this way, by appropriately changing the rotation direction of the piston 7, the fluid can be sucked or discharged quantitatively from both the fluid inlets / outlets 50 and 52, and the fluid transfer direction can be changed.

  As described above, the interval between the two fluid inlets and outlets 50 and 52 formed around the circumference of the chamber 5 is set to approximately 90 ° around the circumference of the chamber 5, but the interval between the fluid inlets and outlets 50 and 52 is substantially 90. If the angle is larger than 0 °, the opening time of the fluid inlet / outlet ports 50 and 52 when the piston 7 reaches the top dead center and the bottom dead center becomes long, and the pump does not function. On the other hand, if the angle is smaller than about 90 °, the fluid inlets and outlets 50 and 52 are opened at the time when the suction and discharge of the fluid are not completed, and thus the pump does not function as well. Further, as described above, the inclination angle of the inclined surface 7c of the piston 7 is set to a range of approximately 60 ° to less than 90 ° with respect to the central axis L of the cylinder 3, but if this inclination angle is less than 60 °, the fluid Since the fluid inlet / outlet ports 50 and 52 are opened at the time when the suction and discharge are not completed, the pump does not function as well.

  In this way, by setting the separation angle between the fluid inlets and outlets 50 and 52 and the inclination angle of the inclined surface 7c of the piston 7 to the predetermined angles described above, the fluid inlet / outlet until the piston 7 reaches the top dead center and the bottom dead center. 50 and 52 are not opened, and when the piston 7 reaches the top dead center and the bottom dead center, the fluid ports 50 and 52 are opened instantly. As described above, the inclination angle of the inclined surface 7c of the piston 7 is most preferably about 60 ° with respect to the central axis of the cylinder 3, but the inclination angle of the inclined surface 7c of the piston 7 is about 60 °. Then, the volume of the chamber 5 can be secured to the maximum, and a large amount of fluid can be transferred.

  The terms and expressions used in this specification are merely used for convenience to describe the present invention, and do not limit the contents of the present invention. The use of such terms and expressions is not intended to exclude equivalents or portions of the above-described embodiments of the present invention. Obviously, various modifications may be made within the scope of the claimed invention.

It is a front view of a reversible rotation type valveless pump concerning an embodiment of the present invention. It is a left view of the reversible rotation type valveless pump shown in FIG. It is a top view of the reversible rotation type valveless pump shown in FIG. It is the AA line longitudinal cross-sectional view of FIG. It is a BB line longitudinal cross-sectional view of FIG. It is the CC sectional view taken on the line of FIG. (A) is the longitudinal cross-sectional view which showed the state which the piston of the fluid pump shown in FIG. 1 exists in a top dead center position, (b) is the DD sectional view taken on the line of FIG. 7 (a), (b) -(E) is an end elevation for demonstrating the process until a piston rotates 90 degrees. (A) is the longitudinal cross-sectional view which showed the state which the piston shown in FIG. 7 rotated 90 degrees, (b) is the EE sectional end view of FIG. 8 (a), (b)-(e). FIG. 5 is an end view for explaining the process until the piston rotates 180 °. (A) is the longitudinal cross-sectional view which showed the state which the piston shown in FIG. 7 rotated 180 degrees, (b) is the FF line | wire end view of FIG. 9 (a), (b)-(e) is. FIG. 5 is an end view for explaining the process until the piston rotates 270 °. (A) is the longitudinal cross-sectional view which showed the state which the piston shown in FIG. 7 rotated 270 degrees, (b) is the GG end view of FIG. 9 (a), (b)-(e) FIG. 5 is an end view for explaining the process until the piston rotates 360 °.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reversible rotation type valveless pump 3 Cylinder 5 Volume variable chamber 7 Piston 7c Inclined surface of piston 9 Reversible motor 11 Crank mechanism L Center axis of cylinder

Claims (4)

A cylinder,
A piston that is inserted into the cylinder and defines a variable volume chamber into which a fluid flows into and from a cylinder head of the cylinder;
Two fluid inlets and outlets spaced apart from each other around the circumference of the chamber;
A drive source disposed on the rear end side of the cylinder for rotating the piston forward or backward;
A crank mechanism connected to the drive source and holding the piston so as to allow rotation and reciprocation of the piston;
A cooperating mechanism disposed in the cylinder for promoting reciprocation of the piston;
By configuring the front end surface of the piston as an inclined surface that is inclined with respect to the central axis of the cylinder, when the piston reciprocates while rotating, the two fluid inlet / outlet ports are arranged according to the direction of rotation of the piston. A reversible rotary valveless pump characterized in that one can be opened and closed and the other of the two fluid inlets and outlets can be closed and opened.   When the piston reaches top dead center, the top inner surface of the cylinder head is in contact with the central axis of the cylinder so that the inclined surface of the piston can come into full contact with the top inner surface of the cylinder head. The reversible rotary valveless pump according to claim 1, wherein the reversible rotary valveless pump is configured as an inclined surface inclined with respect to the axis.   The cooperative mechanism includes an annular cam groove formed on either the inner peripheral surface of the cylinder or the outer peripheral surface of the piston so as to be inclined with respect to the central axis of the cylinder, and the inner peripheral surface of the cylinder 3. The reversible rotation according to claim 1, further comprising a cam protrusion provided on either one of the piston and the outer peripheral surface of the piston and slidably fitted in the annular cam groove. Type valveless pump. The piston has linear grooves extending linearly along the longitudinal direction of the piston at opposing portions of the outer periphery of the rear end portion, and the crank mechanism has a base portion connected to the drive source, and A pair of sandwiching pieces extending forward in parallel with each other from the base, the rear end portion of the piston being disposed between the sandwiching pieces, and the pair of the pair from the direction intersecting the central axis of the piston The reversible rotary valveless pump according to any one of claims 1 to 3, wherein a stylus is passed through each of the holding pieces and engaged with the linear groove so as to be relatively movable.

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