JP2004251243A - Plunger pump for feeding liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plunger pump for feeding liquid capable of preventing air from mixing in feeding liquid. <P>SOLUTION: A channel part 36 is provided along the peripheral direction on an inner peripheral face of a packing 28. A communicating pipe 34 communicating with a storage part 30 is stored in the channel part 36. A plurality of small holes are provided in the communicating pipe 34. The small holes are plugged by an outer peripheral face of a plunger rod 12. When a clearance occurs between the plunger rod 12 and the packing 28, liquid in the storage part 30 flows out into the clearance through the small holes in the communicating pipe 34. For this reason, if the plunger rod 12 is worn, and amount of liquid in the storage part 30 is reduced. That is, a wear condition of the plunger rod 12 is informed by the amount of liquid in the storage part 30 to prevent air bubbles from being mixed in feeding liquid by replacing the plunger rod 12 before air is mixed in a flow passage 40. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plunger pump for feeding a liquid that sucks and discharges liquid by reciprocating movement of a plunger rod.
[0002]
[Prior art]
A coating layer made of an organic polymer compound (hereinafter referred to as “backcoat layer”) is formed on the surface opposite to the coating film of the lithographic printing plate to prevent the coating film from being damaged when the lithographic printing plates are stacked. Has been.
[0003]
This backcoat layer is formed by curing the backcoat solution, but the backcoat solution is sent to the coating device by a plunger pump and applied to the opposite surface of the lithographic printing plate coating film by the coating device. The
[0004]
Here, the backcoat liquid has high curability, and the scale of the backcoat liquid is formed in the cylinder of the plunger pump. When the plunger rod is reciprocated in the cylinder in such a state, the surface of the plunger rod comes into contact with the scale and is worn by the scale.
[0005]
When the surface of the plunger rod is worn, a gap is formed between the packing provided between the plunger rod and the cylinder and the plunger rod, and the backcoat liquid is discharged from the gap when the plunger rod moves forward and backward. Leaks into the cylinder.
[0006]
Further, in the backward movement of the plunger rod, air inside the cylinder is sucked and air is mixed into the backcoat liquid, and bubbles are generated. As described above, when the backcoat liquid containing bubbles is applied to the planographic printing plate, repelling occurs.
[0007]
Further, as shown in FIG. 5, as a mechanism for preventing the plunger rod 112 from being worn, it is located at the upper end of a suction tube 102 provided in a plunger pump 100 for slurry coating pressure feeding that pressurizes and pumps slurry coating. There is one in which a leakage paint passage 106 is provided in the upper part of the discharge port 104 (Patent Document 1).
[0008]
Then, the suction part packing 110 is arranged in the plunger rod support cylinder 108, and the paint leaked between the suction part packing 110 and the rod support part 114 above the suction part packing 110 flows into the leakage paint passage 106. I am doing so.
[0009]
In addition, the plunger rod support cylinder 108 is provided with a bypass 116 communicating with the leaking paint passage 106 so that the leaked paint can be discharged, and a cleaning water port 118 is provided so that the leaking paint passage 106 can be cleaned and leaked. Wear of the plunger rod 112 due to the paint is prevented.
[0010]
However, the air sucked from the gap between the suction part packing 110 and the rod support part 114 during the backward movement of the plunger rod 112 is not considered, and air is mixed into the slurry paint to generate bubbles. Resulting in.
[0011]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-329079 (second page, FIG. 1)
[0012]
[Problems to be solved by the invention]
An object of the present invention is to provide a plunger pump for liquid feeding in which air is not mixed in the liquid feeding in consideration of the above facts.
[0013]
[Means for Solving the Problems]
The invention according to claim 1 is a flow path switching member having a cylinder in which a plunger rod can reciprocate and a flow path that is attached to the mouth of the cylinder and in which the tip of the plunger rod can reciprocate. A suction port valve that is provided in the suction port of the flow path switching member and communicates or closes the flow path and the suction port by the reciprocating movement of the plunger rod; and a discharge port of the flow path switching member. An outlet seal that closes or communicates with the flow path and the outlet by the reciprocating movement of the plunger rod, and an annular seal that is disposed between the cylinder and the plunger rod and that slides the plunger rod And a wear detecting means for detecting a gap generated between the seal member and the plunger rod and notifying the wear state of the plunger rod. It is characterized in.
[0014]
In the first aspect of the invention, the flow path switching member is attached to the mouth of the cylinder in which the plunger rod can reciprocate. The flow path switching member is provided with a flow path so that the distal end portion of the plunger rod can be reciprocated.
[0015]
In addition, the suction port of the flow path switching member is provided with a suction port valve element that allows the flow path and the suction port to communicate or close by reciprocating movement of the plunger rod. A discharge valve body that closes or communicates the flow path and the discharge port by reciprocating movement of the rod is provided.
[0016]
Thereby, when the plunger rod is moved forward, the flow channel and the suction port communicate with each other in a state where the discharge port is closed, and the liquid is sucked into the flow channel. Then, when the plunger rod is moved backward, the flow path and the discharge port communicate with each other with the suction port closed, and the liquid is discharged from the cylinder. By repeating this reciprocating movement of the plunger rod, the liquid can be flowed from the suction port to the discharge port.
[0017]
Here, an annular seal member is disposed between the plunger rod and the cylinder so that the plunger rod can slide. On the other hand, the liquid delivery plunger pump is provided with wear detection means, and when a gap is generated between the seal member and the plunger rod, the gap is detected and the plunger rod is worn. Announce.
[0018]
With the above configuration, the tip of the plunger rod reciprocates in the flow path, so that the tip of the plunger rod is worn by the scale of the liquid formed on the inner peripheral wall of the flow path, and the seal member and the plan A gap is created between the jar rods. Thus, when a gap is generated between the seal member and the plunger rod, air is sucked into the flow path through the gap.
[0019]
However, when the wear detection means detects a gap between the seal member and the plunger rod, the wear detection means notifies that the plunger rod has a lifetime. And it can prevent that a bubble mixes in liquid feeding by replacing | exchanging a plunger rod before air mixes in a flow path.
[0020]
According to a second aspect of the present invention, the wear detecting means is provided on the sliding portion where the liquid is stored, the sliding portion communicating with the storing portion and the seal member and the plunger rod, the seal member and the plan. And a communication portion for allowing the liquid to flow into a gap generated between the jar rod and the jar rod.
[0021]
According to the second aspect of the present invention, a communication portion that communicates with the storage portion in which the liquid is stored is provided on the sliding surfaces of the seal member and the plunger rod. This communication part is plugged by a plunger rod.
[0022]
For this reason, when the plunger rod is not worn, the liquid stored in the reservoir does not leak, but when the plunger rod is worn, the communicating portion is opened, and the gap between the plunger rod and the seal member is released. Then, the liquid in the storage part flows out from the communication part.
[0023]
Therefore, even if a gap is generated between the seal member and the plunger rod, it is liquid that is sucked from the gap when the plunger rod moves back in the cylinder. Will not be mixed.
[0024]
In the invention of claim 3, the surface of the plunger rod is ceramic coated. Thereby, compared with the case where the surface of the plunger rod is hard chrome plated, for example, the wear resistance is high and the life of the plunger rod can be extended.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
The plunger pump for liquid feeding which concerns on embodiment of this invention is demonstrated.
[0026]
As shown in FIG. 1, the plunger pump 10 includes a plunger rod 12 that can be inserted into the cylinder 14. Here, the surface of the plunger rod 12 is provided with a ceramic (SiC) coating having a thickness of 0.01 mm to improve the wear resistance.
[0027]
A shaft 18 is connected to one end of the plunger rod 12 via a coupling 16. A link 20 is connected to the shaft 18, and rotation from the motor 22 is performed by a so-called slider crank mechanism. The force is transmitted to the link 20 through the shaft 24 and the link 26, and converted into power for reciprocating the shaft 18. Thereby, the plunger rod 12 integrally connected with the shaft 18 can reciprocate in the cylinder 14 along the axial direction of the cylinder 14.
[0028]
On the other hand, a cylindrical packing 28 is disposed on the inner peripheral wall on one end side of the cylinder 14 so that the outer peripheral surface of the distal end portion of the plunger rod 12 can slide. In addition, a storage portion 30 formed in a substantially conical shape can be disposed on the upper portion of the cylinder 14 so as to store the liquid.
[0029]
Here, the liquid stored in the storage unit 30 differs depending on the liquid fed by the plunger pump 10. For example, a backcoat liquid for applying the opposite surface of the coating film of the planographic printing plate is planned. When liquid is fed by the jar pump 10, methyl ethyl ketone (MEK), which is the main solvent of the backcoat liquid, is selected.
[0030]
FIG. 3 shows the reservoir 30 attached to the cylinder 14. A pipe part 32 hangs down from the storage part 30 and can be inserted into a hole part 34 penetrating through the upper part of the cylinder 14. An annular communication tube 34 having a substantially semicircular cross section can be attached to the distal end portion of the tube portion 32 in a state where the tube portion 32 communicates with the tube portion 32.
[0031]
The communication pipe 34 is formed in the inner circumferential surface of the packing 28 along the circumferential direction and can be accommodated in a groove 36 having a substantially semicircular cross section. In a state where the communication pipe 34 is accommodated in the groove portion 36, the inner peripheral surface of the communication pipe 34 is substantially flush with the inner peripheral face of the packing 28, and is substantially flush with the outer peripheral face of the plunger rod 12. It is trying to be in a state.
[0032]
A plurality of small holes (not shown) are formed on the inner peripheral surface of the communication pipe 34, and the inner peripheral surface of the communication pipe 34 is substantially flush with the outer peripheral surface of the plunger rod 12. The small hole is plugged by the outer peripheral surface of the plunger rod 12.
[0033]
On the other hand, a through-hole 17 into which the bolt 15 can be screwed is formed in the lower portion of the cylinder 14, and the front end surface of the bolt 15 with the head of the bolt 15 in contact with the counterbore portion 19 (see FIG. 1). Thus, the communication pipe 34 is supported and the communication pipe 34 is positioned.
[0034]
By the way, as shown in FIGS. 1 and 2, a flow path switching member 38 is attached to the mouth portion of the cylinder 14 located on the distal end side of the plunger rod 12. The part is formed with a flow path 40 in which the tip of the plunger rod 12 can reciprocate.
[0035]
The flow path 40 communicates with a suction flow path 42 and a discharge flow path 44 provided in the flow path switching member 38, and liquid is sucked from a suction port 46 formed in the suction flow path 42. Then, the liquid can be discharged from the discharge port 48 formed in the discharge channel 44.
[0036]
Here, balls 50 and 52 as valve bodies are accommodated in the suction flow path 42 and the discharge flow path 44 so that the suction opening 46 and the discharge opening 48 can be closed. In addition, coil springs 54 and 56 are disposed in the suction flow path 42 and the discharge flow path 44, respectively, and urge the balls 50 and 52 toward the suction port 46 and the discharge port 48, respectively.
[0037]
With the above configuration, as shown in FIG. 1, when the shaft 18 is drawn toward the motor 22 through the shaft 24 and the links 20 and 26 by the rotation of the motor 22, the tip of the plunger rod 12 is Then, it moves in the direction of being pulled out from the flow path 40 (forward movement). At this time, a suction force is generated in the flow path 40, and the balls 50 and 52 disposed in the suction flow path 42 and the discharge flow path 44 move toward the flow path 40, respectively.
[0038]
For this reason, the ball 50 in the suction flow path 42 floats in a direction against the urging force of the coil spring 54, the suction flow path 42 and the suction port 46 communicate with each other, and the ball 52 in the discharge flow path 44. Is drawn to the discharge port 48 and the discharge port 48 is closed.
[0039]
That is, when the distal end portion of the plunger rod 12 moves in the direction of being pulled out from the flow path 40, the liquid flows into the flow path 40 through the suction port 46 and the suction flow path 42.
[0040]
On the other hand, as shown in FIG. 2, when the shaft 18 is pushed out from the motor 22 side through the shaft 24 and the links 20 and 26 due to the rotation of the motor 22, the distal end portion of the plunger rod 12 enters the flow path 40. Move in the direction to be pushed in (reverse movement). At this time, a pressing force is generated in the flow path 40, and the balls 50 and 52 disposed in the suction flow path 42 and the discharge flow path 44 move in directions away from the flow path 40, respectively.
[0041]
For this reason, the ball 50 in the suction channel 42 is pressed toward the suction port 46, the suction port 46 is closed, and the ball 52 in the discharge channel 44 resists the urging force of the coil spring 54. The discharge channel 44 and the discharge port 48 communicate with each other.
[0042]
That is, when the distal end portion of the plunger rod 12 moves in a direction to be pushed into the flow path 40, the liquid that has flowed into the flow path 40 is discharged through the discharge flow path 44 and the discharge port 48.
[0043]
Next, the gist of the plunger pump according to the embodiment of the present invention will be described.
[0044]
As shown in FIG. 3, a groove portion 36 is formed along the circumferential direction on the inner peripheral surface of the packing 28, and a communication pipe 34 communicating with the storage portion 30 in which the liquid is stored is accommodated in the groove portion 36. A plurality of small pipes formed on the inner peripheral surface of the communication tube 34 on the outer peripheral surface of the plunger rod 12 so that the inner peripheral surface of the communication tube 34 is substantially flush with the outer peripheral surface of the plunger rod 12. A hole (not shown) is plugged.
[0045]
Thus, when the plunger rod 12 is not worn, the plunger rod 12 and the cylinder 14 are sealed by the packing 28, and no gap is generated between the plunger rod 12 and the packing 28. Therefore, there is no movement of air around the small hole of the communication pipe 34, and the liquid in the communication pipe 34 does not flow out from the small hole of the communication pipe 34.
[0046]
However, as shown in FIG. 4, when the outer peripheral surface of the plunger rod 12 is worn by the scale solidified in the flow path 40, a gap is formed between the plunger rod 12 and the packing 28, and the small holes are Opened, the liquid in the reservoir 30 flows out into the gap through the small hole.
[0047]
Next, the operation of the plunger rod according to the present embodiment will be described.
[0048]
As shown in FIGS. 1 and 3, a groove portion 36 is provided along the circumferential direction on the inner peripheral surface of the packing 28, and the communication pipe 34 communicating with the storage portion 30 is accommodated in the groove section 36, and a plurality of communication pipes 34 are provided in the communication pipe 34. The small hole (not shown) is provided and the small hole is plugged on the outer peripheral surface of the plunger rod 12, so that a gap is generated between the plunger rod 12 and the packing 28 due to wear of the plunger rod 12. In this case, the liquid in the storage unit 30 can flow out into the gap through the small hole of the communication pipe 34.
[0049]
Therefore, when the plunger rod 12 is worn, as shown in FIG. 4, the liquid stored in the storage unit 30 flows out into the flow path 40 through the gap, so that the amount of liquid in the storage unit 30 is Will decrease.
[0050]
That is, the wear state of the plunger rod 12 is notified by the amount of the liquid in the reservoir 30, and when the amount of the liquid in the reservoir 30 decreases, the plunger rod before the air enters the flow path 40. By exchanging 12, bubbles can be prevented from being mixed into the liquid feeding.
[0051]
In addition, when a gap is generated between the plunger rod 12 and the packing 28, the liquid in the storage unit 30 is allowed to flow into the gap through the small hole of the communication pipe 34, so that The liquid in the reservoir 30 is sucked instead of air.
[0052]
For this reason, even if a gap is generated between the plunger rod 12 and the packing 28, air is not mixed into the liquid to be fed, and bubbles are not generated. Here, by using the liquid stored in the storage unit 30 as the main solvent of the backcoat liquid, no problem occurs even if the liquid in the storage unit 30 is mixed into the liquid to be fed.
[0053]
In this embodiment, a ceramic coating is applied to the surface of the plunger rod 12 to increase the wear resistance compared to the case where the surface of the plunger rod 12 is hard chrome (HCr) plated. Can extend the lifetime of
[0054]
Specifically, when 0.5 mm hard chrome plating is applied to the surface of the plunger rod 12, it has been used for 24 hours a day and has a life of 6 months. When a ceramic coating of 0.01 mm was applied to the surface, it could be used for 24 hours × 300 days per year with a lifetime of about 2 years. Moreover, although the film thickness of the ceramic coating was 0.01 mm, it is suitable if it is in the range of 0.03 to 1.0 mm.
[0055]
Here, if the amount of liquid in the reservoir 30 decreases, the plunger rod 12 is assumed to have reached the end of its life, and the plunger rod 12 is replaced. However, the amount of liquid in the reservoir 30 decreases by a predetermined amount. At this stage, the plunger rod 12 may be replaced.
[0056]
Furthermore, in this embodiment, when the groove portion 36 is provided in the packing 28 and the communication pipe 34 communicating with the storage portion 30 is accommodated in the groove portion 36, a gap is generated between the plunger rod 12 and the packing 28. Although the liquid in the storage unit 30 is allowed to flow out through the small holes formed in the pipe 34, the liquid is only required to be sucked into the flow path 40 instead of the air, and is not limited thereto.
[0057]
【The invention's effect】
Since the present invention is configured as described above, in the first aspect of the present invention, when a gap is detected between the seal member and the plunger rod, the plunger rod has a life span. By exchanging the plunger rod before air is mixed in, air bubbles can be prevented from being mixed in the liquid feeding.
[0058]
In the invention according to claim 2, even if a gap is generated between the seal member and the plunger rod, it is liquid that is sucked from the gap when the plunger rod moves back in the cylinder. Therefore, air is not mixed in the liquid feeding.
[0059]
In invention of Claim 3, compared with the case where the surface of a plunger rod is hard-chrome plated, abrasion resistance is high, and the lifetime of a plunger rod can be lengthened.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a liquid-feeding plunger pump according to an embodiment of the present invention, showing a state of forward movement of a plunger rod.
FIG. 2 is a cross-sectional view showing a liquid-feeding plunger pump according to an embodiment of the present invention, showing a state in which a plunger rod is moved backward.
FIG. 3 is a perspective view showing an arrangement of a storage portion, packing, and the like provided in the liquid-feeding plunger pump according to the embodiment of the present invention.
FIG. 4 is a cross-sectional view showing a liquid-feeding plunger pump according to an embodiment of the present invention, showing a state where a plunger rod is worn.
FIG. 5 is a sectional view showing a conventional plunger pump for liquid feeding.
[Explanation of symbols]
10 Plunger pump (plunger pump for liquid feeding)
12 Plunger rod 14 Cylinder 28 Packing (seal member)
30 Reservoir (wear detection means)
32 Pipe (wear detection means)
34 Communication pipe (communication part, wear detection means)
38 Channel switching member 50 Ball (suction port valve element)
52 balls (Discharge port valve)

Claims (3)

A cylinder in which the plunger rod can reciprocate;
A flow path switching member attached to the mouth of the cylinder and having a flow path in which the tip of the plunger rod can reciprocate; and
A suction port valve body provided at a suction port of the flow path switching member, and communicating or closing the flow path and the suction port by reciprocating movement of the plunger rod;
A discharge port valve body provided at a discharge port of the flow path switching member, and closing or communicating the flow path and the discharge port by reciprocating movement of the plunger rod;
An annular seal member disposed between the cylinder and the plunger rod, on which the plunger rod slides;
A wear detecting means for detecting a gap generated between the seal member and the plunger rod and notifying a wear state of the plunger rod;
A plunger pump for feeding a liquid characterized by comprising: Wear detection means
A reservoir in which liquid is stored;
A communicating portion that communicates with the storage portion, is provided on a sliding surface of the seal member and the plunger rod, and that causes the liquid to flow into a gap formed between the seal member and the plunger rod;
The plunger pump for liquid feeding according to claim 1, comprising: The plunger pump for liquid feeding according to claim 1 or 2, wherein the surface of said plunger rod is ceramic coated.

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