JP6364649B2 - pump - Google Patents

Description

  The present invention relates to a pump that performs suction and discharge by rotating and reciprocating.

Conventionally, in this kind of invention, for example, as described in Patent Document 1, a cylindrical cylinder (32) having suction ports and discharge ports on peripheral walls on both sides in the radial direction, and in the cylinder (32) A plunger (33) that is inserted to reciprocate and rotate, a spherical ball bearing (11) that is supported by projecting radially from the rear end side of the plunger (33), and the spherical ball bearing (11). There is a plunger pump that includes a cylindrical drive joint (5) that is rotatably supported on a peripheral surface and that is inclined with respect to the plunger (33).
According to this prior art, when the drive joint (5) is rotated, the position in the front-rear direction of the portion of the plunger (33) in front of the spherical ball bearing (11) changes with respect to the drive joint (5). Therefore, the plunger (33) can be moved back and forth while rotating, and the plunger (33) is rotated and moved back and forth by the cut surface (35) on the tip side of the plunger (33) and the inner surface of the cylinder (32). The fluid sucked in between can be moved from the suction port side to the discharge port side.

  By the way, according to the pump having the conventional structure, since the plunger (33) is rotated with respect to the drive joint (5), vibration of a complicated directional component is generated or a spherical ball bearing is provided. There may be a problem of operability, such as the friction of the support portion of (11) and the support portion of the plunger (33) becoming uneven.

JP 2001-248543 A

  The present invention has been made in view of the above-described conventional circumstances, and a problem to be solved by the present invention is to provide a pump having low vibration and sliding resistance and good operability.

  One means for solving the above problems is a rod that is supported so as to reciprocate in the axial direction while rotating, and a drive that fits the rod in a concave-convex shape from one side in the axial direction and transmits rotational force. And a pump that discharges fluid flowing into the suction port by rotation and reciprocation of the rod from the discharge port, and is arranged so that the rod is parallel to the drive joint at an eccentric position. A projection extending in the radial direction is provided on one of the rod and the drive joint in the portion that fits in the concavo-convex shape, and an inclined elongated hole that fits on the projection and extends at an angle with respect to the axial direction on the other By rotating the drive joint, the protrusion reciprocates along the inclined elongated hole, and the rod reciprocates in the axial direction while rotating with the reciprocation. And said that there was Unishi.

  Since the present invention is configured as described above, it is not necessary to incline the rod with respect to the drive joint, and a pump with good vibration and sliding resistance and good operability can be provided.

FIG. 3 is a perspective view showing an example of the main configuration of the pump according to the present invention in a state in which the rod is positioned near the front end and the protrusions are substantially parallel. It is a perspective view which shows the state which the rod was located in the intermediate vicinity of the front-back direction about the main structures of the pump, and the protrusion faced up and down. It is a perspective view which shows the state with which the rod was located near the rear end and the protrusion was substantially parallel about main components of the pump. It is a perspective view which shows the state which the rod was located in the intermediate vicinity of the front-back direction about the main structures of the pump, and the protrusion faced up and down. It is a perspective view which shows an example of a drive coupling. (A) It is the front view and side view of the drive joint. (B) It is a longitudinal cross-sectional view of the drive joint. (C) It is a structural diagram which shows the state which integrated the drive coupling into the said pump. The suction steps of the pump are shown sequentially, (a1) to (d1) are transverse sectional views mainly showing the rotation state of the notch, and (a2) to (d2) are mainly showing the rotation state of the protrusions. (A3)-(d3) is a longitudinal cross-sectional view which shows the rotation state of the whole pump. The discharge process of the pump is shown sequentially, (e1) to (h1) are cross-sectional views mainly showing the rotation state of the notch, and (e2) to (h2) are mainly the rotation state of the protrusions. (E3)-(h3) is a longitudinal cross-sectional view which shows the rotation state of the whole pump. It is a graph which shows the relationship between the amount of eccentricity, the angle of an inclined long hole, and the maximum stroke about the said pump.

The first feature of the present embodiment is that a rod that is supported so as to reciprocate in the axial direction while rotating, and a drive that fits the rod in a concave-convex shape from one side in the axial direction and transmits rotational force. And a pump that discharges fluid flowing into the suction port by rotation and reciprocation of the rod from the discharge port, and is arranged so that the rod is parallel to the drive joint at an eccentric position. A projection extending in the radial direction is provided on one of the rod and the drive joint in the portion that fits in the concavo-convex shape, and an inclined elongated hole that fits on the projection and extends at an angle with respect to the axial direction on the other By rotating the drive joint, the protrusion reciprocates along the inclined elongated hole, and the rod reciprocates in the axial direction while rotating with the reciprocation. It was.
Here, in the configuration of “fitting in an uneven shape from one side in the axial direction with respect to the rod”, there is an aspect in which a drive joint is fitted in an annular shape around the rod, and a hollow shape with an open rear end side. A mode in which a drive joint is inserted from the rear side of the rod is included.
The inclined long hole is preferably a through hole, but can also be a bottomed hole.
The pump preferably constitutes a plunger pump that reciprocates while rotating the rod as a plunger in the cylinder, and discharges fluid flowing into the suction port by rotation and reciprocation of the rod from the discharge port. If so, other pump structures may be used.
According to the above configuration, when the drive joint is rotated, the protrusion moves in one direction along the inclined long hole, and when the drive joint rotates 180 degrees, the protrusion moves in a direction opposite to the one direction. Therefore, if the rotation of the drive joint is continued, the rod reciprocates in the axial direction while rotating, and fluid flowing into the suction port is discharged from the discharge port by these rotation and reciprocation.
Therefore, it is not necessary to incline the rod with respect to the drive joint, vibration and sliding resistance are small, and operability is good.

As a second feature, the protrusion and the inclined elongated hole are provided on both sides in the radial direction, respectively, and the two inclined elongated holes are provided so as to overlap each other when viewed from the radial direction of the drive joint.
According to this structure, since the part which transmits a rotational force is arrange | positioned at the both sides of radial direction, operativity can be made more favorable.

As a third feature, at least the front end side of the drive joint is formed in a cylindrical shape covering the rod from the rear side, the protrusion protrudes from the outer peripheral surface of the rod, and the inclined elongated hole is formed in the drive joint. Provided on the peripheral wall of the tubular portion.
According to this structure, it can be set as the specific aspect with favorable productivity.

As a fourth feature, the inclined long hole penetrates the peripheral wall of the drive joint and extends to the front end of the drive joint and opens forward.
According to this configuration, when the rod is assembled to the drive joint, the protrusion can be inserted from the front side of the opening at the front end of the inclined long hole, so that workability is good.

It should be noted that the embodiments described later also disclose an invention that does not include a part of the above-described features and that only requires the following constituent elements.
That is, the present invention includes a rod that is supported so as to reciprocate in the axial direction while rotating, and a drive joint that fits the rod in a concave-convex shape from one side in the axial direction and transmits rotational force. A rotary reciprocating device, wherein the rod is arranged so as to be parallel to an eccentric position with respect to the drive joint, and is radially arranged on one of the rod and the drive joint at a portion where the concave and convex portions are fitted. An extending projection is provided, and the other is provided with an inclined elongated hole that fits into the protruding portion and extends obliquely with respect to the axial direction. By rotating the drive joint, the protruding portion reciprocates along the inclined elongated hole. The rotary reciprocating device is characterized in that the rod reciprocates in the axial direction while rotating in accordance with the reciprocating motion.
According to this rotary reciprocating device, when the drive joint is rotated, the protrusion moves in one direction along the inclined oblong hole, and when the drive joint rotates 180 degrees, the protrusion moves in the opposite direction to the one direction. Moving. Therefore, if the drive joint continues to rotate, the rod reciprocates in the axial direction while rotating.
Therefore, it is not necessary to incline the rod with respect to the drive joint, and it is possible to provide a rotary reciprocating device having low vibration and sliding resistance and good operability.

  Next, a preferred embodiment having the above features will be described in detail with reference to the drawings.

  The pump 1 includes a rod 10 that is supported so as to reciprocate in the axial direction while rotating, a drive joint 20 that fits the rod 10 in a concavo-convex shape from the rear side and transmits rotational force, and the drive joint. And a pump unit 40 that discharges fluid flowing into the suction port by rotation and reciprocation of the rod 10 from the discharge port (FIGS. 1 to 4, FIG. 6). C) and FIGS. 7 to 8).

  The rod 10 is a substantially cylindrical plunger that reciprocates in the axial direction while rotating, and is inserted into a cylinder 42 (see FIG. 7) of the pump unit 40 described later.

On the front end side of the rod 10, a notch portion 11 for creating a space for sucking fluid is provided. The notch 11 is formed so that the outer peripheral portion on the front end side of the rod 10 is notched by a plane parallel to the center line of the rod 10.
The notch 11 is appropriately set in the circumferential position so that the rod 10 advances and retreats every time the rod 10 rotates 180 degrees and repeats the suction process and the discharge process (see FIGS. 7 to 8).

Further, on the rear end side of the rod 10, projections 12 and 13 are provided that protrude from the outer peripheral surface of the rod 10 to both sides in the radial direction (see FIG. 7). These protrusions 12 and 13 are located at positions shifted from each other by 180 degrees in the circumferential direction of the rod 10, and these two center lines coincide with each other.
According to the illustrated example, the two protrusions 12 and 13 are both end portions of one columnar member, but separate members may be fixed to the outer peripheral surface of the rod 10.
The protrusion amount of each protrusion 12 (13) is appropriately set so as to maintain the fitted state with the inclined long holes 21 and 22 of the peripheral wall of the drive joint 20 during rotation of the drive joint 20.

The rod 10 in the illustrated example has a step portion between the front half portion and the rear half portion, and the front side of the step portion is formed narrower than the rear side. It is possible to make an appropriate shape in consideration of strength and the like, such as omitting it and forming it into the same diameter shaft shape over the entire length.
Further, according to the present embodiment, the material of the rod 10 is ceramic on the front half side and metal on the rear half side and the projections 12 and 13, but it can be made of other hard material having wear resistance. is there.

The drive joint 20 will be described with reference to FIGS. FIG. 5 is a perspective view of the drive joint 20. FIG. 6A is a front view and a side view of the drive joint. FIG. 6B is a longitudinal sectional view of the surface indicated by AA in the front view of FIG. FIG. 6C is a structural diagram showing a state in which the drive joint is incorporated in the pump.
The drive joint 20 is a member whose front end side is formed in a cylindrical shape so as to cover the rod 10 from the rear side. Two inclined long holes 21 and 22 are provided on both sides in the radial direction on the peripheral wall of the cylindrical portion of the drive joint 20 so as to fit into the protrusions 12 and 13 of the rod 10, respectively.
Each inclined elongated hole 21 (22) is inclined by a predetermined angle α (FIG. 7) with respect to the circumferential direction of the drive joint 20 (in other words, the outer circumferential direction of a circle orthogonal to the axis of the drive joint 20). It extends in the inclination direction. The inclined long hole 21 (22) penetrates the peripheral wall of the drive joint 20 in the radial direction, extends to the front end of the drive joint 20, and opens forward. This opening facilitates the operation of fitting the protrusions 12 and 13 into the inclined long holes 21 and 22 when the pump 1 is manufactured.
In FIG. 6, reference numeral 23 denotes a fitting hole for coaxially inserting the output shaft 31 of the rotational drive source 30. Reference numeral 24 denotes a screw hole for screwing a screw for fixing the output shaft 31.

The two inclined long holes 21 and 22 are arranged on one side and the other side in the radial direction of the drive joint 20, and the inclination directions are reversed so as to overlap when viewed from the radial direction of the drive joint 20.
That is, one inclined long hole 21 extends obliquely rearward so as to incline in one circumferential direction of the drive joint 20 (clockwise as viewed from the front according to FIG. 1). The other inclined long hole 22 extends rearward so as to incline in the other circumferential direction of the drive joint 20 (according to FIG. 1, counterclockwise as viewed from the front).
The inclination angle α (see FIG. 7) in the circumferential direction of each inclined long hole 21 (22) is set within a range larger than 0 degree and smaller than 90 degrees.

  Further, the length of each inclined long hole 21 (22) is appropriately set so that at least the maximum stroke of the rod 10 can be secured. In addition, since the movement distance of the protrusions 12 and 13 in the inclined long holes 21 and 22 is not limited to the length of the inclined long holes 21 and 22, the length of the inclined long holes 21 and 22 is set to the rod 10. However, the length may be longer than the length for securing the maximum stroke.

  According to the present embodiment, the material of the drive joint 20 is a hard synthetic resin material, but it may be a metal or other hard material.

The rotation drive source 30 is an electric motor such as a brushless DC motor or a stepping motor, for example, and projects the output shaft 31 forward. The output shaft 31 is coaxially connected to the rear end portion of the drive joint 20.
As other examples of the rotation drive source 30, a brush motor, other electric motors, air motors, hydraulic motors, manual rotation mechanisms, and the like can be used.

  The pump unit 40 includes a pump case 41 and a cylinder 42 fixed in the pump case 41, and is supported by a support bracket 50 on a portion (stator) that does not move with respect to the output shaft 31 of the rotary drive source 30. (See FIG. 7).

  The pump case 41 has a suction port 40a on one side in a direction orthogonal to the central axis of the rod 10, and has a discharge port 40b on the other side. The cylinder 42 is accommodated between the suction port 40a and the discharge port 40b. A cylinder storage portion 41c.

The suction port 40a and the discharge port 40b communicate linearly.
The cylinder storage part 41c is a bottomed cylindrical space with the front end as the bottom, and the cylinder 42 is fixed near the bottom of the inside (see FIG. 7). Moreover, the rear end side of this cylinder accommodating part 41c is opened so that the rod 10 may be inserted.

  The cylinder 42 is formed in a cylindrical shape by a hard material having wear resistance, and has through holes 42 a and 42 a (see FIG. 7) communicating with the suction port 40 a and the discharge port 40 b on the peripheral wall thereof. In the cylinder 42, the front end side of the rod 10 is inserted. The inner diameter of the cylinder 42 is appropriately set so that the rod 10 advances and retreats while rotating in sliding contact.

  In the illustrated example, a pump case 41 made of a hard synthetic resin material is integrally formed around a ceramic cylinder 42. However, the pump case 41 and the cylinder 42 may be made of other hard resin materials. Is possible.

  The support bracket 50 is a cylindrical member made of a hard material, and is arranged so as to cover the periphery of the drive joint 20. The rear end portion is connected to the stator of the rotary drive source 30, and the front end portion is The pump case 41 is fixed by being connected to the pump unit 40 (see FIG. 7).

The rod 10 supported by the pump unit 40 as described above and the drive joint 20 fixed to the output shaft 31 of the rotary drive source 30 are arranged so as to be parallel at a position eccentric by an eccentric amount s. (See FIG. 7).
More specifically, the central axis of the rod 10 is shifted by an eccentric amount s in one of the radial directions (in the direction of the discharge port 40b according to FIG. 7) with respect to the central axis of the drive joint 20. In position, these two central axes are parallel.
The eccentric amount s is appropriately set according to the stroke of the reciprocating motion of the rod 10 as will be described in detail later. That is, when the stroke of the rod 10 is increased, the eccentric amount s is set larger, and when the rod 10 is decreased, the eccentric amount s is set smaller.

Next, the characteristic effect of the pump 1 having the above-described configuration will be described in detail.
7 (a1), (b1), (c1), (d1) and FIGS. 8 (e1), (f1), (g1), and (h1) are positions indicated by BB in FIG. 6 (C). The cross section of the cylinder 42 in FIG.
7 (a2), (b2), (c2), (d2) and FIGS. 8 (e2), (f2), (g2), (h2) are indication surfaces passing through the centers of the cylindrical projections 12, 13. 2 shows the positional relationship between the cross section of the drive joint 20 and the protrusions 12 and 13. For example, FIG. 7A2 shows the positional relationship between the protrusions 12 and 13 and the cross section of the drive joint 20 at the position indicated by CC in FIG.
First, when the state where the rod 10 is positioned at the foremost end of the advance / retreat range is set to the initial position, the projections 12 and 13 are substantially horizontal as shown in FIGS. 1 and 7 (a1 to a3). And located in the middle of the long direction of the inclined long holes 21 and 22. Moreover, in this initial position, the pump part 40 has closed the space enclosed by the cylinder 42 inner surface, the notch part 11, etc., and has not sucked in the fluid (refer FIG. 7 (a1)).

When the drive joint 20 rotates in one direction from the initial state, the central axis of the drive joint 20 and the central axis of the rod 10 are eccentric, so that the protrusions 12 and 13 are along the inclined long holes 21 and 22 that rotate. Move diagonally backward.
That is, when the drive joint 20 is rotated, the protrusions 12 and 13 slide in the inclined long holes 21 and 22 in a direction in which the eccentric amount s between the rod 10 and the drive joint 20 is to be maintained. For this reason, the rod 10 moves to one side in the axial direction while rotating.

  7 (b1 to b3), when the rod 10 is rotated about 45 degrees from the initial state, the protrusions 12 and 13 are positioned in the middle of the inclined long holes 21 and 22 in the longitudinal direction. At this position, the pump unit 40 communicates the space surrounded by the inner surface of the cylinder 42, the notch 11 and the front end surface of the rod 10 to the suction port 40a, the fluid flows into the space, and the suction process is started.

  When the drive joint 20 further rotates in one direction, the protrusions 12 and 13 further move obliquely rearward along the inclined long holes 21 and 22 that rotate. And in the state rotated about 90 degree | times from the initial position as shown in FIG. 7 (c1-c3), the processus | protrusions 12 and 13 are located in the approximate center of the longitudinal direction of the inclination long holes 21 and 22. FIG. At this position, the pump unit 40 expands the space surrounded by the inner surface of the cylinder 42, the notch 11 and the front end surface of the rod 10 to the rear side in the axial direction of the rod 10, and further sucks fluid into the space.

  Subsequently, when the drive joint 20 further rotates in one direction, the protrusions 12 and 13 further move obliquely rearward along the inclined long holes 21 and 22. And in the state rotated about 135 degree | times from the initial position as shown in FIG. 7 (d1-d3), the protrusions 12 and 13 are located in the middle part near the rearmost end part of the longitudinal direction in the inclined long holes 21 and 22. . At this position, the pump unit 40 further expands the space surrounded by the inner surface of the cylinder 42, the notch 11 and the front end surface of the rod 10 in the axial direction of the rod 10, and further sucks fluid into the space.

  Subsequently, when the drive joint 20 further rotates in one direction, the protrusions 12 and 13 also move further obliquely rearward along the inclined elongated holes 21 and 22. And in the state rotated about 180 degree | times from the initial position as shown in FIG. 8 (e1-e3), the processus | protrusions 12 and 13 are located in the approximate last end part of the longitudinal direction of the inclined long holes 21 and 22, and the rod 10 The backward stroke of is maximized. In this 180 degree position, the pump part 40 seals the space enclosed by the cylinder 42 inner surface, the notch part 11, the rod 10 front end surface, etc. (refer FIG. 8 (e1)).

  When the amount of rotation of the drive joint 20 from the initial position exceeds 180, the protrusions 12 and 13 that have moved diagonally backward move in the reverse direction (obliquely forward) along the inclined long holes 21 and 22 that rotate. Begin to. With this rotation and obliquely forward movement, the pump unit 40 communicates a space surrounded by the inner surface of the cylinder 42, the notch 11 and the front end surface of the rod 10 to the discharge port 40b, and discharges the fluid in the space to the discharge port. A discharge process of discharging from 40b to the outside is started (see FIG. 8 (f1 to f3)).

  Subsequently, when the rotation amount of the drive joint 20 further advances, the protrusions 12 and 13 further move obliquely forward along the inclined long holes 21 and 22 that rotate. Along with this rotation and oblique forward movement, the pump unit 40 narrows the space surrounded by the inner surface of the cylinder 42, the notch 11 and the front end surface of the rod 10, and further discharges the fluid in the space from the discharge port 40b to the outside. (Refer to FIG. 8 (g1 to g3, h1 to h3)).

When the rotation amount of the drive joint 20 reaches 360 degrees, the drive joint 20 returns to the initial position (FIG. 7 (a1 to a3)), and the discharge process is completed.
Therefore, when the rotation of the drive joint 20 by the rotation drive source 30 continues, the rod 10 rotates and repeats a reciprocating motion that changes the advancing and retracting direction every time the rotation amount exceeds 180 degrees. The suction process and the discharge process by the pump unit 40 are also repeated.

Next, how the maximum stroke of the rod 10 changes when the magnitude of the eccentricity (offset) s and the inclination angle of the inclined long holes 21 and 22 are changed for the pump 1 having the above-described configuration. The result of computer simulation will be described (see FIG. 9).
In the graph of FIG. 9, the horizontal axis indicates the amount of eccentricity s between the central axis of the rod 10 and the central axis of the drive joint 20, and the vertical axis indicates the maximum stroke of the rod 10.
Further, a circle mark indicates a case where the inclination angle of the inclined long holes 21 and 22 with respect to the circumferential direction is 30 degrees, a square mark indicates a case where the inclination angle is 45 degrees, and a circle mark indicates that the inclination angle is 60 degrees. Degree case.
From this graph, it can be said that the maximum stroke increases as the eccentric amount s between the rod 10 and the drive joint 20 increases. Further, it can be said that the maximum stroke increases as the inclination angle of the inclined long holes 21 and 22 increases.
Further, it can be seen from the graph that when the eccentric amount s of the rod 10 and the drive joint 20 is 0, the maximum stroke is also 0.

Therefore, according to the pump 1 of the present embodiment, the rod 10 can be reciprocated while smoothly rotating, and the suction process and the discharge process of the pump unit 40 can be repeated along with these movements.
In addition, unlike the conventional structure in which power is transmitted to the plunger that is inclined with respect to the drive joint, the power is transmitted in a state where the rod 10 and the drive joint 20 are parallel to each other. Resistance and the like can be significantly reduced. As a result, wear of each sliding portion can be reduced, and the life of the pump 1 can be made relatively long.
Further, the maximum stroke of the rod 10 can be easily changed by adjusting the eccentric amount s and / or adjusting the inclination angle of the inclined long holes 21 and 22.

  In addition, according to the said Example, while making the rear-end side of the rod 10 into a convex part and making the front-end side of the drive coupling 20 into a recessed part, these rods 10 and the drive coupling 20 were fitted in uneven | corrugated shape, As another example, the concavo-convex relationship can be reversed. That is, in this other example, the rear end side of the rod 10 is formed in a cylindrical shape, the front end side of the drive joint 20 is formed in an axial shape, the inclined long holes 21 and 22 are provided in the peripheral wall of the rod 10, and the drive joint 20 Protrusions 12 and 13 are provided on the outer peripheral portion of each. Then, the rod 10 and the drive joint 20 are fitted back and forth in a concavo-convex shape, and the protrusions 12 and 13 on the outer periphery of the drive joint 20 are fitted into the inclined long holes 21 and 22 on the peripheral wall of the rod 10.

  Further, according to the above embodiment, the protrusions 12 and 13 are provided on the outer peripheral surface of the rod 10, and the inclined long holes 21 and 22 are provided on the peripheral wall of the drive joint 20. It is also possible to provide a structure in which protrusions protruding radially inward are provided on the surface, inclined long holes that can be guided by inserting the protrusions are provided on the outer peripheral surface of the rod 10, and the protrusions and the inclined long holes are fitted together. It is.

  Moreover, according to the said Example, although the pump part 40 was comprised as a plunger pump, as another example of the pump part 40, it can also be set as the pump of aspects other than the example of illustration using the rotation and reciprocation of the rod 10. Is possible.

  Moreover, according to the said Example, although the rod 10 was decentered to the discharge port 40b direction with respect to the drive coupling 20, as another example, the suction port 40a direction with respect to the drive coupling 20 and the fluid conveyance direction It is possible to adopt a mode in which it is decentered in other directions such as a crossing direction with respect to.

  Moreover, it is also possible to constitute a rotary reciprocating device that reciprocates while rotating the rod 10 by omitting the pump portion 40 and the cutout portion 11 from the pump 1 of the above embodiment. This rotary reciprocating device can be effectively used as an actuator for all industrial equipment such as robots and medical machines.

1: Pump 10: Rod (plunger)
DESCRIPTION OF SYMBOLS 11: Notch part 12, 13: Protrusion 20: Drive joint 21, 22: Inclined long hole 30: Rotation drive source 40: Pump part 40a: Suction port 40b: Discharge port 41: Pump case 42: Cylinder

Claims (4)

A rod supported to reciprocate in the axial direction while rotating; and a drive joint that fits in an irregular shape from one side in the axial direction to the rod and transmits a rotational force, and rotates and reciprocates the rod. A pump that discharges fluid flowing into the suction port by movement from the discharge port,
The rod is arranged so as to be parallel at an eccentric position with respect to the drive joint, and a protrusion extending in the radial direction is provided on one of the rod and the drive joint at the portion fitting in the uneven shape, and the other is provided on the other It is provided with an inclined elongated hole that fits on the protrusion and extends inclined with respect to the axial direction,
A pump characterized in that by rotating a drive joint, the protrusion reciprocates along the inclined elongated hole, and the rod reciprocates in the axial direction while rotating along with the reciprocation. The protrusion and the inclined long hole are respectively provided on both sides in the radial direction,
The pump according to claim 1, wherein the two inclined long holes are provided so as to overlap each other when viewed from a radial direction of the drive joint.   The drive joint is formed in a cylindrical shape covering at least the front end side from the rear side with respect to the rod, the protrusion is protruded from the outer peripheral surface of the rod, and the inclined elongated hole is formed on the cylindrical portion of the drive joint. The pump according to claim 1, wherein the pump is provided on a peripheral wall.   4. The pump according to claim 3, wherein the inclined long hole penetrates the peripheral wall of the drive joint and extends to the front end of the drive joint and opens forward.

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