Joint device for reciprocating pump

Abstract

To provide a joint device for a reciprocation pump which can allow (absorb) not only relative inclination between a driving shaft and a driven shaft but also eccentricity between the driving shaft and the driven shaft.SOLUTION: A joint device 1 for connecting a driving source with a reciprocating pump includes: a first thrust member 3 having a first recessed surface 3a; a second thrust member 5 having a second recessed surface 5a; a spherical object 7 sandwiched between the first recessed surface 3a and the second recessed surface 5a; and a housing 11 having an internal space 10 which houses the first thrust member 3, the second thrust member 5, and the spherical object 7. The first thrust member 3 and the second thrust member 5 are arranged along a center axis CL of the housing 11. A width of the internal space 10 is larger than widths of the first thrust member 3, the second thrust member 5, and the spherical object 7.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a coupling device used for driving reciprocating pumps such as plunger pumps and piston pumps.

Background Art

[0002] A reciprocating pump is connected to a drive source (for example, an air cylinder or a hydraulic cylinder) via a coupling device. The reciprocating motion of the drive source is transmitted to the piston of the reciprocating pump via the coupling device, and the piston reciprocates. It is ideal for the drive shaft on the drive source side and the driven shaft on the reciprocating pump side to be aligned in a straight line in order to prevent mechanical damage and extend the lifespan. This is because there is less performance loss in this case, while misalignment can easily cause unintended contact, friction, wear, and galling of parts.

[0003] However, in order to align the drive shaft and the driven shaft in a straight line, high machining accuracy and great effort in assembling the device are required, and equipment and man-hours for this purpose are necessary. Therefore, the coupling device used for a reciprocating pump needs to have a structure that can absorb the eccentricity (that is, the difference in the relative axial center positions between the drive shaft and the driven shaft) and the angular deviation (that is, the relative inclination between the drive shaft and the driven shaft) between the drive shaft and the driven shaft.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As an example of a coupling device that can tolerate the angular deviation between a driving shaft and a driven shaft, a universal joint can be cited. However, a universal joint does not have a structure that can withstand the high thrust load transmitted from the driving shaft to the driven shaft. For this reason, if a reciprocating pump is operated for a long time, the universal joint may be damaged.

[0006] Furthermore, in addition to the angular deviation between the driving shaft and the driven shaft, there may be an eccentricity between the driving shaft and the driven shaft. Such eccentricity is caused by the relative displacement of the driving source and the reciprocating pump. Conventional coupling devices such as universal joints could not tolerate (absorb) such eccentricity.

[0007] Patent Document 1 discloses a coupling device corresponding to the angular deviation and eccentricity between a driving shaft and a driven shaft. In order to provide a margin for angular deviation and eccentricity, this coupling device has a gap provided vertically. However, as a result, the stroke length of the driven shaft becomes shorter than that of the driving shaft by the amount of the gap, and the volume on the pump side decreases, resulting in poor pump efficiency. Moreover, every time there is a reciprocating motion in the axial direction, the members adjacent to each other in the axial direction repeatedly collide, generating vibration and noise, and conversely, wear and fatigue failure are likely to occur at the collision points of the members.

[0008] The present invention provides a coupling device for a reciprocating pump that can tolerate (absorb) not only the angular deviation between a driving shaft and a driven shaft but also the eccentricity between the driving shaft and the driven shaft, and can further improve the pump efficiency.

Means for Solving the Problems

[0009] In one aspect, there is a coupling device for connecting a drive source and a reciprocating pump, comprising a first thrust member having a first concave surface, a second thrust member having a second concave surface, a sphere sandwiched between the first concave surface and the second concave surface, and a housing having an internal space for accommodating the first thrust member, the second thrust member, and the sphere. The first thrust member and the second thrust member are arranged along the central axis of the housing, and the width of the internal space is larger than the widths of the first thrust member, the second thrust member, and the sphere. A coupling device is provided.

[0010] In one aspect, the first concave surface and the second concave surface are concave spherical surfaces having the same radius of curvature as the outer surface of the sphere. In one aspect, the first thrust member, the second thrust member, and the sphere are eccentric with respect to the central axis of the housing. In one aspect, the second thrust member has a second flat surface, and the housing has a flat seat that is in surface contact with the second flat surface. In one aspect, the housing is fixed to a first shaft extending from one of the drive source and the reciprocating pump, and the sphere is fixed to a second shaft extending from the other of the drive source and the reciprocating pump. In one aspect, the housing has a threaded hole communicating with the internal space, and an external thread portion formed on the outer peripheral surface of the first shaft is screwed into the threaded hole. In one aspect, the first thrust member has a first flat surface, and the first flat surface is in contact with the end surface of the first shaft. In one aspect, the second thrust member has a structure divided into a plurality of members.

Advantages of the Invention

[0011] According to the present invention, although there is a margin in the range of correspondence to the declination angle and eccentricity, structurally, there is no gap in the axial direction, so the efficiency of the pump increases. Moreover, not only that, but since there is no repeated collision between the members adjacent in the axial direction, vibration and noise do not occur, wear at the collision points of the members and fatigue failure are less likely to occur, and mechanical damage can be prevented and the life can be extended. In addition, the first thrust member and the second thrust member that contact the sphere can be inclined relative to each other. Furthermore, since the width of the internal space is larger than the widths of the first thrust member, the second thrust member, and the sphere, the first thrust member, the second thrust member, and the sphere can be eccentric with respect to the housing. Therefore, when a first shaft (for example, a drive shaft) is fixed to the housing and a second shaft (for example, a driven shaft) is fixed to the sphere, the coupling device can allow (absorb) both the declination angle and the eccentricity between the first shaft and the second shaft.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of a joint device for connecting a drive source and a reciprocating pump. The joint device 1 includes a first thrust member 3 having a first concave surface 3a, a second thrust member 5 having a second concave surface 5a, a sphere 7 sandwiched between the first concave surface 3a and the second concave surface 5a, and a housing 11 having an internal space 10 for accommodating the first thrust member 3, the second thrust member 5, and the sphere 7.

[0014] The first thrust member 3 and the second thrust member 5 are arranged along the central axis CL of the housing 11. More specifically, the first thrust member 3, the sphere 7, and the second thrust member 5 are arranged in a line along the central axis CL of the housing 11. The first thrust member 3, the sphere 7, and the second thrust member 5 are made of a hard material such as metal or ceramic.

[0015] The housing 11 is fixed to a first shaft 15 extending from one of a drive source (for example, an air cylinder or a hydraulic cylinder) and a reciprocating pump (for example, a plunger pump or a piston pump), and the sphere 7 is fixed to a second shaft 16 extending from the other of the drive source and the reciprocating pump. The sphere 7 has a shaft portion 7b extending from its spherical outer surface 7a, and this shaft portion 7b extends through the second thrust member 5 to the second shaft 16. The housing 11 has a through hole 11a for passing the shaft portion 7b and the second shaft 16. The width of the through hole 11a is larger than the width (diameter) of the second shaft 16.

[0016] The housing 11 has a threaded hole 19 that communicates with the internal space 10. The male thread portion 20 formed on the outer peripheral surface of the first shaft 15 is screwed into the threaded hole 19. The first thrust member 3 has a first flat surface 3b, and the first flat surface 3b is always in contact with the end surface of the first shaft 15. The end surface of the first shaft 15 is perpendicular to the central axis CL, and the first flat surface 3b is perpendicular to the central axis CL of the housing 11 while being in contact with the end surface of the first shaft 15. In order to adjust the distance between the drive shaft and the piston of the reciprocating pump, a shim (or spacer) may be sandwiched between the first flat surface 3b of the first thrust member 3 and the end surface of the first shaft 15.

[0017] The first concave surface 3a and the second concave surface 5a are sunken spherical surfaces having the same radius of curvature as the outer surface 7a of the sphere 7. The first concave surface 3a is circular, and the second concave surface 5a is an annular shape with a hole in the approximate center. The sphere 7 is slidably supported by both the first concave surface 3a of the first thrust member 3 and the second concave surface 5a of the second thrust member 5. The first concave surface 3a and the second concave surface 5a are always in surface contact with the outer surface 7a of the sphere 7 during the reciprocating motion. Therefore, the sphere 7 can tilt with respect to the housing 11, the first thrust member 3, and the second thrust member 5 while maintaining its relative position with respect to the housing 11. As a result, as shown in FIG. 2, the second shaft 16 fixed to the sphere 7 can tilt with respect to the first shaft 15 fixed to the housing 11.

[0018] In particular, according to the present embodiment, since the entire first concave surface 3a and the entire second concave surface 5a are always in contact with the spherical outer surface 7a of the sphere 7, the joint device 1 can withstand the high load applied to the joint device 1 during the reciprocating motion, and the sphere 7 can tilt smoothly with respect to the first thrust member 3 and the second thrust member 5. Further, since the first concave surface 3a and the second concave surface 5a are arranged so as to sandwich the sphere 7 along the direction of the central axis CL of the housing 11 (i.e., along the reciprocating movement direction), the sphere 7 is supported by both the first concave surface 3a and the second concave surface 5a regardless of the direction of the reciprocating movement in which the joint device 1 is moving, and the sphere 7 can tilt smoothly with respect to the first thrust member 3 and the second thrust member 5. As a result, during the reciprocating motion, the second shaft 16 fixed to the sphere 7 can tilt smoothly with respect to the first shaft 15 fixed to the housing 11.

[0019] The width of the internal space 10 of the housing 11 is larger than the widths of the first thrust member 3, the second thrust member 5, and the sphere 7. Here, the "width" refers to the dimension in the direction perpendicular to the central axis CL of the housing 11. As shown in FIG. 3, the first thrust member 3, the second thrust member 5, and the sphere 7 can be integrally eccentric with respect to the central axis CL of the housing 11. That is, the positions of the first thrust member 3, the second thrust member 5, and the sphere 7 in the direction perpendicular to the central axis CL are variable within the internal space 10 of the housing 11. As a result, the second shaft 16 fixed to the sphere 7 can be eccentric with respect to the first shaft 15 fixed to the housing 11.

[0020] The second thrust member 5 has a second flat surface 5b, and the housing 11 has a flat seat 24 that is in surface contact with the second flat surface 5b. The second flat surface 5b is an annular surface. The second flat surface 5b and the seat 24 are perpendicular to the central axis CL of the housing 11. The second flat surface 5b and the seat 24 are always in contact. The seat 24 only supports the second flat surface 5b and does not prevent displacement or movement of the second thrust member 5 in a direction perpendicular to the central axis CL of the housing 11. The first flat surface 3b of the first thrust member 3 and the second flat surface 5b of the second thrust member 5 are both perpendicular to the central axis CL of the housing 11. As described above, the end face of the first shaft 15, the first flat surface 3b, the first concave surface 3a, the sphere 7, the second concave surface 5a, the second flat surface 5b, and the seat 24 are always in contact with adjacent members in the direction of the central axis CL. Therefore, the first flat surface 3b and the second flat surface 5b can guide displacement or movement of the first thrust member 3, the sphere 7, and the second thrust member 5 in a direction perpendicular to the central axis CL.

[0021] FIG. 4 is a schematic diagram showing the state when the joint device 1 and the first shaft 15 and the second shaft 16 connected thereto reciprocate. In FIG. 4, the joint device 1 is schematically drawn. In the example shown in FIG. 4, the first shaft 15 is a drive shaft connected to the drive source 31, and the second shaft 16 is a driven shaft connected to the reciprocating pump 32, but the present invention is not limited to the example of FIG. 4.

[0022] As shown in FIG. 4, when the drive source 31 and the reciprocating pump 32 are inclined with respect to each other, during the reciprocating motion, the second shaft 16 can be inclined with respect to the first shaft 15 by the joint device 1. Therefore, the movement of the second shaft 16 is not restricted by the reciprocating pump 32, and as a result, the stroke of the reciprocating pump 32 can be increased.

[0023] Returning to FIG. 1, in the present embodiment, an annular latch 27 is fitted on the upper portion of the second thrust member 5. The second thrust member 5 of the present embodiment has a structure divided into a plurality of members, and the latch 27 is for fixing the relative positions of these plurality of members. In one example, the second thrust member 5 has a two-piece structure composed of two semi-annular members, and the relative positions of these two semi-annular members are fixed by the latch 27. The second thrust member 5 may be divided into three or more members.

[0024] The housing 11 has an opening 11b formed in its side wall. This opening 11b is used during maintenance and / or assembly of the first thrust member 3 and the second thrust member 5.

[0025] Next, an embodiment of a method for assembling the coupling device 1 configured as described above will be described. First, with the first shaft 15, the first thrust member 3, and the second thrust member 5 removed from the housing 11, the sphere 7 fixed to the second shaft 16 is inserted into the internal space 10 through the through hole 11a of the housing 11. The two semi-annular members constituting the second thrust member 5 are inserted into the internal space 10 through the opening 11b of the housing 11, and further, the latch 27 is fitted onto the two semi-annular members from above the sphere 7, thereby fixing the relative positions of the two semi-annular members to form the second thrust member 5. Next, the first thrust member 3 is inserted into the internal space 10 through the opening 11b or the screw hole 19 of the housing 11 and placed on the sphere 7. Further, the entire housing 11 is rotated about its central axis CL, and the screw hole 19 of the housing 11 is screwed onto the male screw portion 20 of the first shaft 15 until the first flat surface 3b of the first thrust member 3 contacts the end surface of the first shaft 15. With the first flat surface 3b of the first thrust member 3 in contact with the end surface of the first shaft 15, the set screw 35 is screwed into the second screw hole 11c formed in the side wall of the housing 11 to fix the relative positions of the housing 11 and the first shaft 15. Thereby, the assembly of the coupling device 1 is completed.

[0026] When replacing the first thrust member 3 and / or the second thrust member 5, first rotate the entire housing 11 in the opposite direction to separate the first flat surface 3b of the first thrust member 3 from the end face of the first shaft 15. The first thrust member 3 can be removed from the opening 11b of the housing 11. When removing the second thrust member 5, first remove the latch 27 from the second thrust member 5. Then, the two semi-annular members constituting the second thrust member 5 can be removed from the opening 11b of the housing 11.

[0027] FIG. 5 is a cross-sectional view showing another embodiment of the joint device 1. The configuration and operation of this embodiment not specifically described are the same as those of the embodiment described with reference to FIGS. 1 to 4, so the overlapping description is omitted.

[0028] As shown in FIG. 5, in this embodiment, the sphere 7 is detachably fixed to the second shaft 16 by a screw structure. More specifically, a male screw 40 is formed on the shaft portion 7b of the sphere 7, and a screw hole 42 is formed on the end face of the second shaft 16. By screwing the male screw 40 of the sphere 7 into the screw hole 42 of the second shaft 16, the sphere 7 can be fixed to the second shaft 16. Further, by removing the male screw 40 of the sphere 7 from the screw hole 42 of the second shaft 16, the sphere 7 can be separated from the second shaft 16.

[0029] In the embodiment shown in FIG. 5, the second thrust member 5 is composed of a single annular member and does not have two semi-annular members. Further, the latch 27 shown in FIG. 1 is not provided either.

[0030] An embodiment of a method for assembling the joint device 1 according to the embodiment shown in FIG. 5 will be described. First, with the first shaft 15, the first thrust member 3, and the second thrust member 5 removed from the housing 11 and the sphere 7 removed from the second shaft 16, the second thrust member 5 and the sphere 7 are placed into the internal space 10 of the housing 11. Next, with the second thrust member 5 positioned between the sphere 7 and the second shaft 16, the male thread 40 of the sphere 7 is screwed into the threaded hole 42 of the second shaft 16 to fix the sphere 7 to the second shaft 16. The first thrust member 3 is placed into the internal space 10 through the opening 11b or the threaded hole 19 of the housing 11 and placed on the sphere 7. Further, the entire housing 11 is rotated about its central axis CL, and the threaded hole 19 of the housing 11 is screwed onto the male threaded portion 20 of the first shaft 15 until the first flat surface 3b of the first thrust member 3 contacts the end surface of the first shaft 15. With the first flat surface 3b of the first thrust member 3 in contact with the end surface of the first shaft 15, a locking screw 35 is screwed into the second threaded hole 11c formed in the side wall of the housing 11 to fix the relative position between the housing 11 and the first shaft 15. Thereby, the assembly of the joint device 1 is completed.

[0031] When replacing the first thrust member 3 and / or the second thrust member 5, first, the entire housing 11 is rotated in the opposite direction to disconnect the housing 11 from the first shaft 15. The first thrust member 3 can be taken out from the opening 11b or the threaded hole 19 of the housing 11. When removing the second thrust member 5, the male thread 40 of the sphere 7 is removed from the threaded hole 42 of the second shaft 16 to separate the sphere 7 from the second shaft 16. Then, the sphere 7 is taken out from the housing 11, and further the second thrust member 5 is removed from the housing 11.

[0032] Each of the above-described embodiments of the joint device 1 is suitable for use in connecting a reciprocating pump for transferring liquefied gas such as liquid hydrogen, liquefied natural gas, liquefied ammonia, liquid nitrogen, liquefied ethylene gas, and liquefied petroleum gas, and a drive source. In particular, as shown in FIG. 4, since the joint device 1 is arranged between the drive source 31 and the reciprocating pump 32, it is possible to prevent the cryogenic liquefied gas in the reciprocating pump 32 from cooling (freezing) the drive source 31.

[0033] The above-described embodiments are described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention pertains to implement the present invention. Various modifications of the above embodiments can be naturally made by those skilled in the art, and the technical idea of the present invention can also be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is construed in the broadest scope in accordance with the technical idea defined by the claims.

Explanation of Reference Numerals

[0034] 1 Joint device 3 First thrust member 3a First concave surface 3b First flat surface 5 Second thrust member 5a Second concave surface 5b Second flat surface 7 Sphere 7a Outer surface 10 Internal space 11 Housing 11a Through hole 11b Opening 11c Second threaded hole 15 First shaft 16 Second shaft 19 Threaded hole 20 Male threaded portion 24 Seat 27 Catch 31 Drive source 32 Reciprocating pump 35 Locking screw 40 Male thread 42 Threaded hole

Claims

1. A coupling device for connecting a drive source and a reciprocating pump, comprising: a first thrust member having a first concave surface; a second thrust member having a second concave surface; a sphere sandwiched between the first concave surface and the second concave surface; a housing having an internal space for accommodating the first thrust member, the second thrust member, and the sphere; the first thrust member and the second thrust member are arranged along the central axis of the housing; the width of the internal space is larger than the widths of the first thrust member, the second thrust member, and the sphere; the housing is fixed to a first shaft extending from one of the drive source and the reciprocating pump; the sphere is fixed to a second shaft extending from the other of the drive source and the reciprocating pump; the housing has a threaded hole communicating with the internal space; a male thread portion formed on the outer peripheral surface of the first shaft is screwed into the threaded hole. A coupling device.

2. The coupling device according to claim 1, wherein the first concave surface and the second concave surface are sunken spherical surfaces having the same radius of curvature as the outer surface of the sphere.

3. The coupling device according to claim 1 or 2, wherein the first thrust member, the second thrust member, and the sphere are eccentric with respect to the central axis of the housing.

4. The coupling device according to any one of claims 1 to 3, wherein the second thrust member has a second flat surface, and the housing has a flat seat that is in surface contact with the second flat surface.

5. The coupling device according to claim 1, wherein the first thrust member has a first flat surface, and the first flat surface is in contact with the end surface of the first shaft.

6. The coupling device according to any one of claims 1 to 5, wherein the second thrust member has a structure divided into a plurality of members.

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