Reciprocating pump

Abstract

A reciprocating pump includes a first manifold which includes a pump chamber, a second manifold which is connected to the first manifold, and a seal which is disposed inside the second manifold and comes into slidable contact with a plunger. A communication pipe which extends across an inside of the first manifold and an inside of the second manifold comes into contact with the seal. Additionally, the reciprocating pump includes a collar which is disposed inside the first manifold and comes into contact with the communication pipe through which the plunger is inserted. The collar, the communication pipe, and the seal are sandwiched between the inside of the first manifold and the inside of the second manifold.

Claims

1. A reciprocating pump comprising: a first manifold which includes a pump chamber fluidly coupled to at least one discharge passage; a second manifold connected to the first manifold and which includes a cylinder portion fluidly coupled to the pump chamber; a plunger configured to reciprocate inside the cylinder portion in an axial direction of the cylinder portion, wherein a front end of the plunger includes an outer peripheral edge that extends into the pump chamber during a forward limiting stroke of the plunger, and wherein the at least one discharge passage of the first manifold extends from the pump chamber in a radial direction with respect to the axial direction of the cylinder portion; a seal which is disposed inside the second manifold and comes into slidable contact with the plunger; a communication pipe which extends across an inside of the first manifold and an inside of the second manifold and comes into contact with the seal; and a collar which is disposed inside the first manifold and comes into contact with the communication pipe, wherein a front end of the collar includes a cylindrical end surface which protrudes in the axial direction of the cylinder portion and which terminates between the discharge passage and the outer peripheral edge of the plunger in the axial direction of the cylinder portion during the forward limiting stroke of the plunger, and wherein the collar, the communication pipe, and the seal are sandwiched between the first manifold and the second manifold.

2. The reciprocating pump according to claim 1, wherein the collar includes a first outer diameter portion having the cylindrical end surface which is located near the pump chamber and a second outer diameter portion which is located next to the first outer diameter portion to form a step, and wherein the second outer diameter portion has a larger outer diameter as compared to the first outer diameter portion.

3. The reciprocating pump according to claim 1, wherein the cylindrical end surface of the collar extends at least as far or further into the pump chamber as compared to the outer peripheral edge of the front end of the plunger when the plunger is located at the forward limiting stroke.

4. The reciprocating pump according to claim 3, wherein a gap having a substantially uniform width is formed between an inner surface of the communication pipe and the plunger, and wherein an inner peripheral surface of the collar is spaced apart from the plunger by an amount of clearance that is approximately equal to the uniform width of the gap.

5. The reciprocating pump according to claim 4, wherein the uniform width gap extends continuously along a partial length of the plunger from the communication pipe to the outer peripheral edge of the front end of the plunger.

6. The reciprocating pump according to claim 5, wherein the uniform width gap extends continuously along the partial length of the plunger from at least a portion of the seal to the outer peripheral edge of the front end of the plunger.

7. The reciprocating pump according to claim 4, wherein the uniform width of the gap is approximately 2 mm or less.

8. The reciprocating pump according to claim 1, wherein the collar comprises a resin material which is softer than the plunger.

9. The reciprocating pump of claim 1, wherein an inner peripheral surface of the front end of the collar forms a cylindrical shaped opening of the collar that opens into the pump chamber in the axial direction of the cylinder portion.

10. A reciprocating pump comprising: a pump chamber; a cylinder portion fluidly coupled to the pump chamber; a plunger configured to reciprocate inside the cylinder portion in an axial direction of the cylinder portion, wherein the plunger comprises a front end having an outer peripheral edge that extends into the pump chamber during a forward limiting stroke of the plunger; at least one discharge passage fluidly coupled to the pump chamber and extending in a radial direction with respect to the axial direction of the cylinder portion; a seal located proximate to the cylinder portion; a communication pipe which operably connects the pump chamber to the cylinder portion; and a collar located proximate to the pump chamber, wherein a front end of the collar includes a cylindrical end surface which protrudes in the axial direction of the cylinder portion and which terminates between the discharge passage and the outer peripheral edge of the plunger in the axial direction of the cylinder portion during the forward limiting stroke of the plunger, wherein the communication pipe is located between the collar and the seal, and wherein the outer peripheral edge of the plunger reciprocates within the collar during operation of the reciprocating pump.

11. The reciprocating pump of claim 10, wherein the communication pipe and the collar form a substantially uniform gap along a partial length of the plunger.

12. The reciprocating pump of claim 11, wherein the uniform gap extends along the partial length of the plunger from the communication pipe to the outer peripheral edge of the plunger during both the forward limiting stroke and a backward limiting stroke of the plunger.

13. The reciprocating pump of claim 12, wherein the uniform gap continues along the partial length of the plunger into a space formed between the seal and the plunger.

14. The reciprocating pump according to claim 11, wherein a width of the uniform gap is approximately 2 mm or less.

15. The reciprocating pump of claim 10, wherein the collar comprises a second end that contacts the communication pipe, and wherein at both the forward limiting stroke and a backward limiting stroke of the plunger during the operation of the reciprocating pump, the outer peripheral edge of the plunger remains located between the front end and the second end of the collar.

16. The reciprocating pump of claim 10, wherein the collar, the communication pipe, and the seal are sandwiched together as a result of operably connecting the pump chamber to the cylinder portion.

17. A reciprocating pump comprising: a pump chamber; a cylinder portion fluidly coupled to the pump chamber; a plunger configured to reciprocate inside the cylinder portion in an axial direction of the cylinder portion, wherein a front end of the plunger comprises an outer peripheral edge that extends into the pump chamber during a forward limiting stroke of the plunger; at least one discharge passage extending from the pump chamber in a radial direction with respect to the axial direction of the cylinder portion; seal means located proximate to the cylinder portion; means for connecting the pump chamber to the cylinder portion; and a collar located proximate to the pump chamber, wherein a front end of the collar includes a cylindrical end surface which protrudes in the axial direction of the cylinder portion and which terminates between the discharge passage and the outer peripheral edge of the plunger in the axial direction of the cylinder portion during the forward limiting stroke of the plunger, wherein the means for connecting is located between the collar and the seal means, and wherein the outer peripheral edge of the plunger reciprocates within the collar during operation of the reciprocating pump.

18. The reciprocating pump of claim 17, wherein the collar and the means for connecting form a uniform gap along at least a partial length of the plunger that extends from the seal means to the outer peripheral edge of the plunger.

19. The reciprocating pump of claim 18, wherein the collar comprises a second end that contacts the means for connecting, and wherein at both the forward limiting stroke and a backward limiting stroke of the plunger during the operation of the reciprocating pump, the outer peripheral edge of the plunger remains located between the front end and the second end of the collar.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 illustrates a cross-sectional view of an example reciprocating pump.

(2) FIG. 2 illustrates an enlarged view of a front end of the example reciprocating pump of FIG. 1.

DETAILED DESCRIPTION

(3) Hereinafter, a preferred embodiment of a reciprocating pump according to the disclosure will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of an example reciprocating pump 100 and FIG. 2 is an enlarged view of a front end of the example reciprocating pump of FIG. 1.

(4) As shown in FIG. 1, the reciprocating pump 100 may comprise a plunger-type pump in which a reciprocating member 1 having a plunger 1a formed at a front half of the reciprocating member and a plunger rod 1b formed at a rear half of the reciprocating member moves inside the cylinder portion 2 in a reciprocating manner to perform a pumping action in cooperation with a pump chamber 3 located at a front end of the cylinder portion 2. The plunger pump 100 may comprise a first manifold 4 which includes the pump chamber 3, a second manifold 5 which includes the cylinder portion 2 in fluid communication with the pump chamber 3, and a crank casing 6. The second manifold 5 may be connected and/or fluidly coupled to both the first manifold 4 and the crank casing 6. In some examples, the first manifold 4 may comprise a discharge manifold and the second manifold 5 may comprise a water absorption manifold.

(5) The crank casing 6 may be formed in a hollow shape. A crank shaft 7, a connecting rod 8 rotatably connected to the crank shaft 7, and a piston pin 9 rotatably connecting the plunger rod 1b to the connecting rod 8 are disposed in the crank casing 6. A drive unit 10 comprising the crank casing 6, the crank shaft 7, the connect rod 8, and the piston pin 9 may be configured to drive the reciprocating member 1 in a reciprocating manner. The crank casing 6 is filled with oil for lubricating and cooling the drive unit 10. An oil seal 11 which provides a water-tight seal comes into slidable contact with the outer peripheral surface of the plunger rod 1b at the rear half of the reciprocating member 1 is disposed on the side of the second manifold 5 in the crank casing 6 in order to prevent the leakage of the oil inside the crank casing 6. Then, when the crank shaft 7 rotates, the reciprocating member 1 moves in a reciprocating manner in the axial direction of the reciprocating pump (the horizontal direction of the drawing) through actuation of the connecting rod 8 and the piston pin 9.

(6) The second manifold 5 which comes into contact with the crank casing 6 is provided with an intake port 12 which introduces, for example, a working liquid such as water into the pump chamber 3. The first manifold 4 which comes into contact with the second manifold 5 is provided with a discharge port 13 which discharges the working liquid compressed in the pump chamber 3. An intake valve 14 is provided in a passage 16 that fluidly couples the intake port 12 with the pump chamber 3. A discharge valve 15 is provided in a passage 17 that fluidly couples the pump chamber 3 with the discharge port 13.

(7) The first manifold 4 and the second manifold 5 are connected and/or fluidly coupled to each other through a collar 18, a communication pipe 19, and a high-pressure seal (seal means) 20. The collar 18, the communication pipe 19, and the high-pressure seal 20 are sequentially provided in the cylinder portion 2 (e.g., in parallel) from the pump chamber 3 toward the crank casing 6.

(8) The high-pressure seal 20 located at the front half of the reciprocating member 1 prevents the leakage of the working liquid from the pump chamber 3 toward the crank casing 6 through the cylinder portion 2. The high-pressure seal 20 is accommodated in the second manifold 5. The high-pressure seal 20 includes, as shown in FIG. 2, a V-packing 21 which is laminated in the axial direction and has an annular shape. The high-pressure seal 20 further comprises a male adapter 22 and a female adapter (a backup ring) 23 which sandwich the laminated V-packing 21 from both sides. In some examples, the high-pressure seal 20 has an annular shape. The male adapter 22 is disposed near the pump chamber 3 and the female adapter 23 is provided near the crank casing 6.

(9) The V-packing 21 may be formed of, for example, an elastic body such as rubber and comes into slidable contact with the plunger 1a to form a water-tight seal. The male adapter 22 may be formed of, for example, resin or the like. The male adapter 22 has a gap formed between the inner peripheral surface of the male adapter 22 and the outer peripheral surface of the plunger 1a so that the plunger 1a is inserted therethrough. The female adapter 23 may be formed of, for example, resin or the like. The female adapter 23 has a slight gap formed between the inner peripheral surface of the female adapter 23 and the outer peripheral surface of the plunger 1a. The female adapter 23 comes into contact with a step 24 formed inside the second manifold 5.

(10) In addition, for example, a low-pressure seal 25 may be disposed at a position separated from the high-pressure seal 20 toward the crank casing 6 in the second manifold 5 to come into slidable contact with the outer peripheral surface of the plunger 1a and to form a water-tight seal. In some examples, the low-pressure seal 25 may comprise U-packing which prevents the leakage of the working liquid toward the crank casing 6 in the event of any leakage of the working fluid from the high-pressure seal 20.

(11) The communication pipe 19 may be formed of, for example, metal or the like and is formed in a cylindrical shape so that the outer diameter is substantially the same as the outer diameter of the high-pressure seal 20. The communication pipe 19 extends across the inside of the first manifold 4 and the inside of the second manifold 5 and comes into contact with the male adapter 22. An annular gap is formed between the inner peripheral surface of the communication pipe 19 and the outer peripheral surface of the plunger 1a when the plunger 1a is inserted through the communication pipe 19. A first O-ring 26 is disposed between the first manifold 4 and the outer peripheral surface of the communication pipe 19 and a second O-ring 27 is disposed between the second manifold 5 and the outer peripheral surface of the communication pipe 19. These O-rings 26 and 27 are configured to prevent the leakage of the working liquid along the outer peripheral surface of the communication pipe 19.

(12) The collar 18 may be formed of, for example, resin or the like and is formed in a stepped cylindrical shape. The collar 18 includes a first outer diameter portion 28 which is located near the pump chamber 3 and a second outer diameter portion 29 which is located next to the first outer diameter portion 28 and forms a step 30. In some examples, the second outer diameter portion 29 has an outer diameter that is larger than the outer diameter of the first outer diameter portion 28. Additionally, the second outer diameter portion 29 may comprise an inner diameter equal to the inner diameter of the smaller first outer diameter portion 28. The collar 18 is accommodated in the first manifold 4. The outer diameter of the larger second outer diameter portion 29 is smaller than the outer diameter of the communication pipe 19 and is larger than the inner diameter of the communication pipe 19. The step 30 of the collar 18 comes into contact with an adjacent step 31 formed in the first manifold 4 and the larger second outer diameter portion 29 comes into contact with the communication pipe 19. In some examples, the smaller first outer diameter portion 28 of the collar 18 extends toward the pump chamber 3 in the first manifold 4. Further, the outer peripheral surfaces of the smaller first outer diameter portion 28 and the larger second outer diameter portion 29 of the collar 18 come into close contact with the inner surface of the first manifold 4. The collar 18 has a clearance or gap S formed between the inner peripheral surface thereof and the outer peripheral surface of the plunger 1a so that the plunger 1a is inserted therethrough.

(13) When the plunger 1a is located at the forward limiting stroke (e.g., at the top dead center rotation of the crank shaft 7), an outer peripheral edge 1c of the front end of the plunger 1a is located in the vicinity of edges P and Q of the second manifold 5 near to the passages 16 and 17. In this way, in a state where the plunger 1a is located at the forward limiting stroke, an end surface 32 of the smaller first outer diameter portion 28 of the collar 18 is disposed to slightly protrude in the axial direction toward the pump chamber 3. The end surface 32 of the first outer diameter portion 28 may extend as far or further into the pump chamber 3 as compared to the outer peripheral edge 1c of the front end of the plunger 1a. The first end 32 of the collar 18 projects into the pump chamber 3. An end surface 33 of the second outer diameter portion 29, or the second end 33 of the collar 18, contacts the communication pipe 19. In some examples, at both the forward limiting stroke and the backward limiting stroke of the plunger during operation of the reciprocating pump 100, the outer peripheral edge 1c of the plunger 1a continuously remains located between the first end 32 and the second end 33 of the collar 18.

(14) The first manifold 4 may be fixed to the crank casing 6 through the second manifold 5 by, for example, bolts which are a plurality of fastening means so that the first and second manifolds 4 and 5 are integrally connected to the crank casing 6. Accordingly, the collar 18, the communication pipe 19, and the high-pressure seal 20 are sandwiched between the first step 31 located inside the first manifold 4 and the second step 24 located inside the second manifold.

(15) In some examples, a difference in inner diameter between the collar 18 and the male adapter 22 may be 1 mm or less. Further, i a difference between the outer diameter of the plunger 1a and the inner diameter of each of the collar 18, the communication pipe 19, and the male adapter 22 may be 2 mm or less. In some examples, the differences in diameter are made relatively small in order to minimize leakage and/or to help ensure a proper alignment between the plunger 1a and the surrounding components during operation of the plunger pump 100.

(16) Then, in such a plunger pump 100, the crank shaft 7 rotates so that the reciprocating member 1 connected to the crank shaft 7 through the connecting rod 8 and the piston pin 9 moves in a reciprocating manner. Since the reciprocating member 1 retreats toward the drive unit 10 in the water charging step, the pump chamber 3 is depressurized. Then, the intake valve 14 and the discharge valve 15 of the manifolds 4 and 5 are respectively opened and closed and the working liquid is sucked into the pump chamber 3 through the intake port 12 and the intake valve 14. Following the water charging step, the reciprocating member 1 advances in the opposite direction in the discharge step, and the pump chamber 3 is pressurized. Then, the intake valve 14 and the discharge valve 15 are respectively closed and opened so that the working liquid of the pump chamber 3 is discharged to the discharge port 13 through the discharge valve 15. In this way, a pumping action is performed in the plunger pump 100.

(17) In the related art, the collar 18 is not provided. For illustrative purposes only, and not to suggest that the prior art necessarily includes the additional features or combinations of features illustrated in the present drawings, the prior art may be distinguished with respect to the plunger pump 100 by way of reference to FIG. 2. In the prior art, a comparatively large gap is formed between the outer peripheral surface of the plunger 1a and the inner peripheral surface R (see FIG. 2) of the first manifold 4. Since the comparatively large gap is connected to the pump chamber 3 with a uniform width from the communication pipe 19, a negative pressure is formed inside the pump chamber 3 when the plunger 1a retreats toward the backward limiting stroke (e.g., at the bottom dead center rotation of the crank shaft 7) in the water charging step and thus air is separated from the working liquid. For this reason, there is concern that a cavitation may be formed due to a large gap in the prior art pump systems.

(18) However, in the example embodiment illustrated by FIG. 2, the collar 18 through which the plunger 1a is inserted extends as far or further into the pump chamber 3 as compared to to the communication pipe 19 of the first manifold 4. Accordingly, the gap S formed between the inner peripheral surface of the collar 18 and the outer peripheral surface of the plunger 1a can be set to be smaller than the gap of the related art. In some examples, the width of the gap S may be approximately 2 mm or less. For this reason, since it is possible to reduce a volume of the gap S where the working liquid enters, it is possible to suppress the amount of the air coming out of the working liquid and to prevent the cavitation affecting the pump. As a result, since it is possible to eliminate the excessive wear and/or deterioration of the plunger 1a, the pump chamber 3, and the inner peripheral surface of the communication pipe 19, durability of the plunger pump 100 can be improved. Since the occurrence of the cavitation can be prevented or minimized in this way, the pumping efficiency can be improved. Further, since the gap S formed at the outer peripheral side of the plunger 1a is small, the compression ratio is increased and thus the water charging performance can be improved.

(19) Further, in some examples, the collar 18 includes the smaller first outer diameter portion 28 which is located near the pump chamber 3 and the larger second outer diameter portion 29 which extends to the first outer diameter portion 28 through the step 30 and has an outer diameter which is larger than the outer diameter of the first outer diameter portion 28. The step 30 of the collar 18 comes into contact with the step 31 formed inside the first manifold 4 and the first outer diameter portion 28 extends toward the pump chamber 3. Accordingly, in the embodiment, since it is possible to reduce a volume of the gap S where the working liquid enters, it is possible to further suppress the occurrence of the cavitation. Further, assembly of the plunger pump 100 may be facilitated by bringing the step 30 of the collar 18 into contact with the step 31 of the first manifold 4.

(20) Further, in a state where the plunger 1a is located at the forward limiting stroke, the end surface 32 of the collar 18 that protrudes in the axial direction may extend as far or further into the pump chamber 3 as compared to the outer peripheral edge 1c of the front end of the plunger 1a. For this reason, since the small gap S formed at the outer peripheral side of the plunger 1a starts from the outer peripheral edge 1c of the front end of the plunger 1a, it is possible to further reduce the volume of the gap S where the working liquid enters and thus to further prevent the occurrence of the cavitation.

(21) Further, in example embodiments in which the material of the collar 18 is resin, damage to the plunger 1a may be prevented even when the plunger 1a is vibrated to contact the collar 18 during an operation of the plunger pump 100. In some examples, the resin may comprise a softer material as compared to the material used in the fabrication of the plunger 1a. Further, the collar 18 may be configured to decrease the amount or distance of vibration of the plunger 1a as a result of contact between the plunger 1a and the collar 18.

(22) In example embodiments in which the collar 18 and the male adapter 22 are formed of resin and sandwich the communication pipe 19, the amount of vibration of the plunger 1a may be minimized according to the width of the gap S. Additionally, damage to the plunger 1a may be prevented even when the plunger 1a is vibrated to contact the male adapter 22 similarly to the collar 18.

(23) Further, the materials of the collar 18 and the male adapter 22 are not limited to resin and may be a material which does not damage the plunger 1a even when contacting the plunger 1a.

(24) It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example embodiment. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail.

(25) For example, in the above-described embodiments, the high-pressure seal (seal means) 20 is formed as the seal having the V-packing 21, but other packings or seal members may be used. Further, the disclosure can be applied to the reciprocating pump of which the plunger 1a moves in a reciprocating manner by the driving of the drive unit 10 to perform a pumping action in the pump chamber 3.

(26) We claim all modifications and variations coming within the spirit and scope of the subject matter claimed herein.