High Viscosity Fluid Pump

Abstract

To prevent the hardening of high-viscosity fluids, especially UV ink, in sliding parts of a pump designed for such fluids.SOLUTION: A plunger 40 is connected to an upper reciprocating drive part 20, and a piston valve 62 into which a piston 66 is fitted is connected to the plunger 40. A foot valve part 80 is provided below the piston valve 62 and a fluid suction port 100 is provided below the foot valve part 80. A diaphragm 44, partially folded and fixed at both ends, is provided at a clearance 43 between the plunger 40 and a ground retainer 42 which covers the plunger 40 when the fluid is supplied from a fluid discharge port 110 to outside by vertical movement of the piston 66 and the piston valve 62. A partially spherical part 66S is provided at the piston 66, and an inner peripheral surface of a suction tube 68 located outside the partially spherical part 66S is slid thereon. A circular ball receiving base 84 is provided at a lower side of a foot valve housing 82 of the foot valve part 80 to sandwich a ball 86.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an improvement in the sliding parts of a pump for high-viscosity fluids, particularly UV inks, and more particularly to a pump that can prevent UV inks from hardening. [Background technology]

[0002] Patent Document 1 discloses a high-viscosity pump, the pump body of which is composed of an upper body, a suction tube, a valve housing, and a chute, with a high-viscosity material suction port provided at the bottom. A high-viscosity material discharge port is opened on the side of the upper body. A plunger is fitted to the upper body via a seal member so as to be movable up and down, and the upper end of the plunger is attached to the drive shaft of a reciprocating drive unit.

[0003] A gland retainer screwed into the upper body holds a packing and a throat bearing as a sealing member fitted to the plunger. The upper part of a rod is screwed into the lower part of the plunger, and a piston that slides inside the suction tube is fitted onto the outer periphery of the rod through an annular gap, and the upper end of the annular gap communicates with the inside of the suction tube through a through hole.

[0004] The plunger, rod and piston move in the axial direction to open and close the lower end opening of the annular gap at a seat portion formed on the rod. The rod is connected to a shovel rod, and a shovel plate for raking up high-viscosity materials is provided at the bottom of the shovel rod.

[0005] When the plunger rises, the seat portion of the rod engages and closes the lower end opening of the annular gap, and the piston rises, causing the high-viscosity material above the piston to be discharged from the high-viscosity material discharge port, and at the same time, the high-viscosity material that has been scooped up into the high-viscosity material suction port is sucked up by the shovel plate.

[0006] Furthermore, when the plunger is lowered, the seat portion separates from the lower end opening of the annular gap, so that the high-viscosity material in the space below the piston, which is lowered together with the plunger, moves through the annular gap and the through hole to the space above the piston. In this high-viscosity pump, a gasket serving as a sealing member is used to wipe off the high-viscosity material adhering to the circumferential surface of the plunger when the plunger rises, thereby minimizing leakage of the high-viscosity material carried to the outside by the plunger. However, this gasket cannot completely remove the high-viscosity material that is firmly attached to the circumferential surface of the plunger, and there is a problem in that the high-viscosity material leaks to the outside through the gap between the plunger 17 and the gland retainer 33.

[0007] This invention solves the problem of high viscosity material leaking out of the pump body by automatically returning the high viscosity material adhering to the circumferential surface of the plunger from inside the sealed body through a circulation passage to the high viscosity material suction port.

[0008] Patent Document 2 discloses a pump that reliably prevents leakage of the fluid inside the pump without a complex seal structure, can be used for internal fluids with higher discharge pressures than reciprocating pumps with normal bellows seals, and is used as a pump that handles fluids containing harmful or flammable substances. A piston ring or packing is provided on the piston, an auxiliary seal is provided on the piston shaft, and a shaft seal is provided on the piston shaft on the atmospheric side of the auxiliary seal, using a flexible member to seal the cylinder chamber side from the atmospheric side.

[0009] Patent document 3 describes an ink pump device whose main body comprises a cylinder having an ink intake port and an ink discharge port, a reciprocating body that reciprocates within the cylinder, and a disk-shaped pumping plate that is attached to the tip of the reciprocating body and pumps up the ink.

[0010] A trip rod is connected to an operating rod that operates the piston, and a switching claw is provided on the other end of the trip rod that engages with a switching slider block to reciprocate the switching slider block based on the reciprocating motion of the trip rod. The switching claw is for switching the supply of a driving fluid, such as hydraulic oil.

[0011] Patent Document 4 discloses a plunger pump used for pumping highly viscous fluids such as ultraviolet-curable ink, in which a predetermined clearance is provided between the piston body and the cylinder to reduce the contact area with the cylinder, and a groove is provided on the outer peripheral surface of the piston body 30 to form a seal between the piston body and the cylinder, thereby preventing ink from flowing in. A clearance is provided between the seal housing portion and the plunger, and multiple grooves are provided on the inner peripheral surface of the seal housing portion. The seal housing portion is provided with a combination seal consisting of an O-ring portion that provides sealing and a low-friction portion with which the plunger comes into contact, and a drain port is provided in the gland retainer portion.

[0012] All of the above known documents use sealing members for sealing, but with such a sealing structure, there is a problem that when a high-viscosity fluid slides between the members of the sealing portion, the high-viscosity fluid sticks together, reducing the operating efficiency of the sliding parts. [Prior art documents] [Patent documents]

[0013] [Patent Document 1] Japanese Patent Application Publication No. 3-246380 [Patent Document 2] JP 2006-144741 A [Patent Document 3] JP2003-286968A [Patent Document 4] Patent No. 5196324 Summary of the Invention [Problem to be solved by the invention]

[0014] An object of the present invention is to provide a non-contact sliding seal structure in a sealing portion of a high-viscosity fluid pump, which eliminates sliding as much as possible.

[0015] Conventionally, high-viscosity fluid pumps have been used to handle fluids, particularly ultraviolet-curable ink (UV ink), which can harden due to ultraviolet light, and sending the hardened ink to the printing press can lead to printing problems. When using a pump for oil-based inks, which uses sliding packing, UV ink can stick to the sliding packing, which creates resistance and causes the pump to stop working, resulting in a malfunction. [Means for solving the problem]

[0016] To solve the above problem, since avoiding the use of sliding packing when using an oil-based ink pump can prevent the ink from hardening, a sealing structure using a diaphragm that does not use a sliding packing is provided in the gap between the plunger and the gland retainer that covers the plunger, thereby preventing the ink from solidifying.

[0017] No packing is used in the sliding area between the piston and the suction tube, and instead the outer diameter of the piston is given a partially spherical shape to reduce the area of ​​the sliding area, or a clearance is provided between the piston and the inner diameter of the suction tube, resulting in a seal structure where metal parts slide without contact.

[0018] The foot valve has a valve opening and closing structure that uses the floating and sinking of a ball, eliminating any sliding parts.

[0019] Claims 1 to 4 of the present invention 4The described invention is a high-viscosity fluid pump in which a plunger is connected to an upper reciprocating drive section, a piston valve with a piston fitted in it is connected to the plunger, a foot valve section is provided below that, and a fluid intake port is provided further below that, and the fluid is fed to the outside from a fluid discharge port by the up and down movement of the piston and piston valve, the piston is fitted in a suction tube, and a partial spherical section is provided on the piston to slide on the inner surface of the suction tube, or a clearance is provided between the partial spherical section of the piston and the inner surface of the suction tube to form a non-contact sliding seal structure.

[0020] Claims of the invention to 5 The described invention is a high-viscosity fluid pump in which a plunger is connected to an upper reciprocating drive section, a piston valve with a piston fitted in it is connected to the plunger, a foot valve section is provided below that, and a fluid intake port is provided further below that, and the fluid is supplied to the outside from the fluid discharge port by the up and down movement of the piston and piston valve.The foot valve section has a circular ball receiving base provided at the bottom of the foot valve housing to hold a ball. Effect of the Invention

[0021] Claims 1 to 4 In the invention, the piston is fitted into the suction tube, and a partial spherical portion is provided on the piston to slide on the inner peripheral surface of the suction tube, limiting the sliding area and limiting adhesion of the high-viscosity fluid. Alternatively, a clearance is provided between the partial spherical portion of the piston and the inner peripheral surface of the suction tube to form a non-contact sliding seal structure, preventing adhesion of the high-viscosity fluid.

[0022] Claim 5In this invention, the foot valve portion has a circular ball receiving base provided at the bottom of the foot valve housing, the inside of which is hollowed out in a circular shape and the upper part is tapered, with the ball being held in place by the lower end of the taper. As a result, the valve opens and closes by the floating and sinking of the ball, there are no sliding parts and therefore no problems with solidification of high viscosity fluids. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a front view of a UV ink pump 10 for high viscosity fluid according to the present invention. [Diagram 2] 2 is a left side view of the upper reciprocating drive unit 20 in FIG. 1. FIG. [Diagram 3] 2 is a schematic diagram showing the inside of the UV ink pump 10 below the plunger 40 of FIG. 1, which is a high-viscosity fluid. [Figure 4] 4A is a schematic diagram showing the state of the UV ink pump 10 of FIG. 3, which is a high-viscosity fluid, at the bottom dead center, and FIG. [Diagram 5] 5 is a schematic diagram showing a state of the UV ink pump 10 of FIG. 4, which is a high-viscosity fluid, at the top dead center. [Figure 6] FIG. 2 is a front view showing an example of a diaphragm of the present invention. [Figure 7] The figures show the shape of the diaphragm in Figure 6, where (A) is a schematic diagram showing the state at top dead center and (C) is a schematic diagram showing the state at bottom dead center, (B) is an enlarged view of the circled part in (A), and (D) is an enlarged view of the circled part in (C). [Figure 8] FIG. 2A is a perspective view showing the shape of a piston of the present invention, and FIG. 2B is a top perspective view showing the state from above of FIG. [Figure 9] FIG. 2 is a schematic diagram showing a piston and a diaphragm of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The high-viscosity fluid pump 10 (particularly a UV ink pump) of the present invention comprises an upper reciprocating drive unit 20, a plunger 40, a piston valve unit 60, a foot valve unit 80, a fluid intake port 100, and a fluid discharge port 110.

[0025] (Upper reciprocating drive unit 20) As shown in Fig. 1, the upper reciprocating drive unit 20 has an air motor 22 at the top, which drives a cylinder 32 and a drive shaft 24 connected below up and down. A silencer 26 connects the upper part of the air motor 22 to the lower part of the air motor 22 with a tube 28, and silences the exhaust noise of the air exhausted from the air motor 22. Reference numeral 30 denotes an air inlet. A tube 36 connects the cylinder 32 to an ejector 34, and pressurized air supplied from the air inlet 30 generates negative pressure by the action of the ejector 34. The ejector 34 operates by pressing a gap between a plunger 40 and a gland retainer 42, which will be described later. It is connected to 43.

[0026] (plunger and gland retainer) As shown in Fig. 2, the upper end of a plunger 40 is connected to the drive shaft 24 so as to be movable up and down. The plunger 40 is made up of an upper long diameter portion 40L and a short diameter portion 40S below it, and the outside of the long diameter portion 40L of the plunger 40 is fitted with a gland retainer 42 as shown in Fig. 3. A gap 43 is formed between the plunger 40 and the gland retainer 42, and a diaphragm 44 is fitted as a sealing member described later from the long diameter portion 40L to the short diameter portion 40S of the plunger. To prevent damage to the diaphragm 44 when the high-viscosity fluid pump 10 is disassembled and assembled, both the plunger 40 and the gland retainer 42 are sealed. A bracket 48 is provided so that the following can be fixed.

[0027] (Piston valve) A connecting rod 62R extending from an upper end 62H of a piston valve 62 of a piston valve portion 60 is fitted to the lower part of the short diameter portion 40S of the plunger 40. This allows the plunger 40 and the piston valve 62 to reciprocate up and down in unison.

[0028] A pumping disk 62L is provided at the lower end of the piston valve 62, and the pumping disk 62L has a trumpet shape with the central outer diameter of the piston valve 62 widening toward the end, and the lower end is disk-shaped. A split pin 64 is annularly fitted and fixed around the periphery of the piston valve 62 at the portion where the connecting rod 62R at the upper end of the piston valve 62 fits into the lower part of the short diameter portion 40S of the plunger 40. A piston valve cylindrical portion 62C is formed between the upper end of the piston valve 62 and the lower pumping disk 62L.

[0029] (Piston and piston valve) A piston 66 is fitted in the piston valve 62. The piston 66 is free from the piston valve 62, and a piston valve cylindrical portion 62C passes through a through hole 66P in the upper part of the piston 66.

[0030] As shown in Figures 8 and 9, the piston 66 is hollow and consists of an upper gate-shaped handle portion 66G and a lower partial spherical portion 66S. The lower part of the upper gate-shaped handle portion 66G is a cylindrical ring-shaped portion 66R, and the partial spherical portion 66S is connected to the ring-shaped portion 66R.

[0031] The piston 66 is fitted in a suction tube 68 and reciprocates up and down. The suction tube 68 is connected to the gland retainer 42 via a truncated cone tube 70 that is tapered upward.

[0032] The piston 66 is structured such that when the piston valve 62 rises, the upper portion of the pumping disc 62L and the lower end portion of the partial spherical portion 66S come into contact with each other.

[0033] (Foot valve part 80) The foot valve portion 80 is covered by a foot valve housing 82, and the lower end of the suction tube 68 fits into and is connected to the upper end of the foot valve housing 82. A ball receiving stand 84 is provided at the lower part of the foot valve housing 82, and the inside of the ball receiving stand 84 is hollowed out in a circular shape with a tapered section 84T at its upper part, which is structured to hold a ball 86 between its tapered lower end 84L (see FIG. 4(B)). A stopper 88 is provided above the ball at the lower end of the suction tube 68 (see FIG. 3), which acts as a stopper for the ball that floats up due to the inflow of fluid from below.

[0034] The lower part of the foot valve portion 80 is a plate 90, and the plate 90 is provided with a fluid intake port 100 in the center.

[0035] (Fluid outlet) The truncated cone tube 70 above the suction tube 68 has a fluid discharge port 110 provided on the side thereof, and the portion opposite the fluid discharge port 110 is an exhaust port 112 used for cleaning the fluid, etc.

[0036] (Bottom dead center of high viscosity fluid pump) The operation of the high-viscosity fluid pump 10 of the present invention will now be described. Fig. 4 shows the state in which the air motor 22, the drive shaft 24, the plunger 40 and the piston valve 62 have descended, and are at bottom dead center. The lower end of the short diameter portion 40S of the plunger 40 is in contact with the upper end portion of the gate-shaped handle portion 66G of the piston 66, and has descended from above the suction tube 68. The partially spherical portion 66S of the piston 66 is hollow, and the pumping disk body 62L of the piston valve 62 has further descended, leaving a gap between the piston 66 and the piston valve 62. As the piston valve 62 descends from above in this way, In this state, if a gap is created between the piston 66 and the piston valve 62, the fluid is pushed upward as shown by the flow L1, and is supplied to the outside from the fluid discharge port 110. As the pumping plate 62L of the piston valve 62 descends, the distance between the pumping plate 62L and the ball is shortened, so that the ball 86 is pushed toward the ball receiving base 84, and the fluid from the fluid intake port 100 cannot flow back.

[0037] (Top dead center of high viscosity fluid pump) FIG. 5 shows the state in which the drive shaft 24, plunger 40 and piston valve 62 from the air motor 22 have risen to the top dead center.

[0038] When the piston valve 62 rises from the bottom dead center, the contact state between the lower end of the short diameter portion 40S of the plunger 40 and the upper end of the gate-shaped handle portion 66G of the piston 66 is released, and the pumping disk body 62L of the piston valve 62 rises and comes into contact with the lower end of the partial spherical portion 66S of the piston 66. As the pumping disk body 62L of the piston valve 62 rises thereafter, the partial spherical portion 66S of the piston 66 is also pushed from below and rises. During this time, there is no gap between the pumping disk body 62L of the piston valve 62 and the partial spherical portion 66S of the piston 66, so that the fluid does not enter from below the pumping disk body 62L of the piston valve 62, but the fluid above the piston 66 rises and is pushed upward as the fluid flow L2, and is supplied to the outside from the fluid discharge port 110.

[0039] As the pumping plate 62L of the piston valve 62 rises, the distance between the pumping plate 62L and the ball increases, causing the ball 86 to rise and come into contact with the stopper 88. This creates a space between the ball receiving base 84 and the ball 86, and fluid from the fluid intake port 100 enters as flow L3, causing new fluid to flow into the space created by the rise of the pumping plate 62L.

[0040] (Characteristics of high viscosity fluids, especially UV inks) The high-viscosity fluids to which this invention is applicable, particularly UV inks, are inks that harden when exposed to ultraviolet light. However, this hardening can be triggered (gelled) if (i) heat above a certain temperature is applied to the UV ink, (ii) pressure is applied to the UV ink, or (iii) the UV ink comes into contact with aluminum or zinc. If the hardened ink is sent to the printing press as a result of these events, it can lead to printing defects.

[0041] In particular, when using a pump for oil-based ink to transport UV ink, which normally uses sliding packing, we have seen cases where the ink itself adheres to the sliding packing and other parts, and this adhesion creates resistance, causing the pump to stop working.

[0042] (Diaphragm) In particular, UV ink can seep into the gap 43 between the plunger 40 and the gland retainer 42. If a sliding packing is used for the sealing structure of this part, the ink may adhere thereto, adversely affecting the operation of the pump.

[0043] Therefore, in the present invention, a diaphragm 44 is adopted as the sealing member. As shown in Fig. 6, the diaphragm 44 is made of a flexible material, that is, a rubber outer cover and a polyester fiber base fabric. As shown in Fig. 6, the shape of the diaphragm 44 is generally cylindrical, with a tapered body 44B in the center, a raised portion 44P protruding in the width direction on the upper end side, a bottom 44L on the lower end side, and a hollow portion 44H that is hollow at the bottom. The diaphragm 44 itself may be made of a material that is flexible and can be fitted closely to the portion where the plunger 40 is attached.

[0044] When assembling the plunger 40, the diaphragm 44 is fixed by clamping the raised portion 44P to the lower end portion 42P of the gland retainer 42. The plunger 40 is fixed by fitting the body portion 44B from the long diameter portion 40L to the flange surface 40F, and fitting the bottom portion 44L to the bottom portion 40LB of the long diameter portion 40L of the plunger 40. As for the bottom portion 44L, as shown in FIG. 7(B), a key-shaped retainer 50 holds the bottom portion 44L of the diaphragm 44 and fastens it with a nut 52.

[0045] The diaphragm 44 is made of a flexible material, with an outer cover made of rubber and a base fabric made of polyester fiber, and is therefore attached in close contact with the outside of the plunger 40. The material of the diaphragm may be any flexible material, and may be rubber alone. In addition, when the outer cover is made of rubber and the base fabric is made of a different material, the material is not particularly limited, and may be aramid fiber, polyphenylene sulfide resin (PPS), nylon, glass fiber, cotton, etc.

[0046] When the high-viscosity fluid pump 10 reaches the top dead center, the diaphragm 44 is folded back (44U) in an inverted U shape vertically or in the vertical movement direction of the pump at the lower part of the body 44B and in the gap 43 between the plunger 40 and the gland retainer 42. Fluid, particularly UV ink, enters inside this folded back part, forming a sealed structure (see FIG. 7(A)).

[0047] As described above, in order to prevent damage to the diaphragm 44 when the high-viscosity fluid pump 10 is disassembled and assembled, the bracket 48 is provided so that both the plunger 40 and the gland retainer 42 can be fixed.

[0048] As shown in Figure 7(C), at the bottom dead center of the high-viscosity fluid pump 10, a portion of the diaphragm 44 adjacent to the raised portion 44P of the body 44B is folded back in a U-shape (44U) vertically or in the direction of up-down movement of the pump at the bottom of the gap 43 between the plunger 40 and the gland retainer 42. The inside of this fold back is gap 44S, into which the fluid, particularly UV ink, enters, forming a seal structure (see Figures 7(C) and (D)).

[0049] In this way, the diaphragm 44 serves to seal the gap 43 between the plunger 40 and the gland retainer 42. Moreover, since high-viscosity fluids, particularly UV ink, enter the inner gap 44S that is folded back in a U-shape vertically to the diaphragm 44 or in the direction of the up and down movement of the pump, the diaphragms 44 themselves do not come into direct contact with each other and have no sliding parts, so the UV ink does not stick in this area.

[0050] (Modified diaphragm example) The method of mounting the diaphragm 44 to the plunger 40 and the gland retainer 42 is not limited to the above mounting method. The raised portion 44P of the diaphragm 44 does not have to be a particular raised shape, and may be fixed with a retainer or nut, as in the fixing method of the bottom portion 44L of the diaphragm 44 described above. Conversely, the bottom portion 44L of the diaphragm 44 described above may be shaped similarly to the raised portion 44P, and may be fixed by dividing the long diameter portion 40L and the short diameter portion 40S of the plunger 40 and sandwiching it between them. When mounted on the plunger 40 and the gland retainer 42, the overall shape is cylindrical, with a tapered body portion 44B in the center. If such a structure exists, and if it can be folded back vertically or in an inverted U-shape in the up and down movement direction of the pump in the gap 43 between the plunger 40 and the gland retainer 42 described above, it can be used sufficiently as a sealing structure.

[0051] (Diaphragm and Ejector) Since the diaphragm 44 is used in the folded shape as described above, if this shape is not maintained, the diaphragm 44 itself may come into contact with the sliding parts, which may lead to the solidification of the UV ink, which is a highly viscous fluid. Therefore, the ejector 34 makes it possible to create a negative pressure in the gap 43 between the plunger 40 and the gland retainer 42. This eliminates the air layer in the parts of the diaphragm 44 that are not in contact with the UV ink, which is a highly viscous fluid, but are in contact with the outside of the plunger 40 and the inside of the gland retainer 42, and thus the outside of the plunger 40 and the diaphragm 44, and the inside of the gland retainer 42 and the diaphragm 44 can be solidified. The diaphragm 44 is in a state where it is glued, preventing it from falling off, and the UV ink, which is a high-viscosity fluid, enters the gap 44S, which is an inverted U-shaped space formed by the body parts of the folded diaphragm, eliminating the direct sliding state described above and eliminating the phenomenon in which the UV ink, which is a high-viscosity fluid, comes into contact with the sliding parts and solidifies. With this configuration, there are no more sliding parts as in the past, and this eliminates the condition in which the UV ink, which is a high-viscosity fluid, solidifies and adheres to the surface, preventing the pump from moving up and down smoothly.

[0052] (Partial spherical part of piston) 8 and 9, the partially spherical portion 66S at the bottom of the piston 66 is a part of a sphere, and even if the piston is tilted from the vertical line, the outside diameter of the part of the piston 66 that comes into contact with the suction tube 68 remains the same. Therefore, the structure is such that some tilt does not cause a problem. In this way, the piston 66 is fitted into the suction tube 68 and reciprocates up and down. The piston 66 can also reduce the area of ​​the sliding part of the suction tube 68, which has the effect of making it less likely for material to stick due to sliding.

[0053] In the conventional case, the sliding portion between the piston 66 and the suction tube 68 is in contact with a surface, and the sliding surface is large. In that sense, when the partial spherical portion 66S of the present invention is used, the sliding portion is in contact with a line, and the sliding portion is narrowed, which is advantageous. If the sliding area is reduced, the amount of contact with the UV ink, which is a high-viscosity fluid, is reduced, and hardening of the ink can be prevented.

[0054] Furthermore, if a clearance is provided between the partial spherical portion 66S of the piston 66 and the inner diameter of the suction tube 68, the sliding parts mentioned above will be eliminated and the partial spherical portion 66S and the suction tube 68 will not come into direct contact with each other, resulting in a non-contact sliding seal structure.

[0055] The clearance between the outer surface of the partial spherical portion 66S and the inner surface of the suction tube 68 is preferably 0.1 mm to 0.2 mm. The outer surface of the partial spherical portion 66S and the inner surface of the suction tube 68 are structured so that UV ink, which is a highly viscous fluid, penetrates and plays a role in sealing. UV ink has a viscosity several times higher than oil-based ink, so with a moderate clearance there is little internal leakage and no significant adverse effect on pump performance.

[0056] The partially spherical part of the piston is preferably a part of a sphere, but the same effect can be expected from an elliptical sphere. If the spherical part is, for example, a thin disk, it has the effect of reducing the sliding area. It can also be replaced by a truncated cone shape, combining an upward truncated cone with a downward truncated cone, with the pointed part in the center being circular.

[0057] The above configuration is an invention that narrows or eliminates the sliding parts, but the sliding properties of such sliding parts can be improved by applying a surface treatment to the sliding parts. For example, applying a fluorine-based surface treatment to the outer periphery of the piston 66 and the inner periphery of the suction tube makes the sliding surfaces highly lubricating, thereby reducing the friction areas and the risk of ink adhesion.

[0058] (Metal material of wetted parts) As for the metal material of the liquid-contacting parts, steel (electroless nickel plating) or stainless steel is used, and materials that may cause the ink to harden (gel) (aluminum alloy, electrolytic zinc plating, etc.) are not used, thereby preventing hardening of UV ink, which is a high-viscosity fluid. Examples of the liquid-contacting parts include the outer peripheral surface of plunger 40, the outer peripheral surface of piston 66, the inner peripheral surface of suction tube 68, the inner peripheral surface of foot valve housing 82, the outer peripheral surface of ball receiver 84, and the outer surface of ball 86.

[0059] (Foot valve) The foot valve of the present invention has a ball receiving base 84 provided at the bottom of a foot valve housing 82, the inside of which is hollowed out in a circular shape and the upper part of which is tapered section 84T, with the tapered lower end 84L holding the ball 86. As a result, the valve opens and closes by the floating and sinking of the ball, and as there are no sliding parts compared to the conventional cylindrical trapezoidal shape, there is no problem with UV ink solidifying. [Industrial Applicability]

[0060] In the above-described embodiment, a non-contact sliding seal structure is proposed as a sealing method for packings and the like used in high-viscosity fluid pumps, and this is a revolutionary improvement in the sealing method for high-viscosity fluid pumps, which has previously been considered difficult.

[0061] Although the present invention relates to a seal structure used in high-viscosity fluid pumps, particularly UV ink pumps, it can be widely applied to high-viscosity fluids. [Explanation of symbols]

[0062] 10 UV ink pump for high viscosity fluid 20 Upper reciprocating drive unit 22 Air Motor 24 Drive shaft 32 cylinders 34 Ejector 40 Plunger 42 Grand Retainer 43 Gap 44 Diaphragm 48 Bracket 50 Key-shaped retainer 52 Nut 60 Piston valve section 62 Piston valve 62L pumping plate 66 Piston 66S Partial Spherical Part 66G Gate-shaped handle 68 Suction tube 80 Foot valve section 82 Foot valve housing 84 Ball Stand 84T Tapered section 84L Taper bottom 86 Ball 90 Plate 100 Fluid inlet 110 Fluid outlet L1, L2, L3 flows

Claims

1. 1. A high-viscosity fluid pump in which a plunger is connected to an upper reciprocating drive section, a piston valve with a piston fitted therein is connected to the plunger, a foot valve section is provided below the foot valve section, and a fluid intake port is provided further below that, and in which fluid is supplied to the outside from a fluid discharge port by the up and down movement of the piston and the piston valve, the piston is fitted into a suction tube, a partial spherical section is provided on the piston and slides on an inner circumferential surface of the suction tube, the partial spherical section of the piston is a part of a circular sphere, and the piston is provided with one partial spherical section.

2. 2. The high-viscosity fluid pump according to claim 1, wherein a clearance is provided between an outer surface of said partial spherical portion and an inner surface of said suction tube.

3. 3. The high viscosity fluid pump according to claim 2, wherein the clearance is between 0.1 mm and 0.2 mm.

4. 4. The high-viscosity fluid pump according to claim 3, wherein a UV ink, which is a high-viscosity fluid, is allowed to penetrate into the clearance, and a non-contact sliding seal structure is formed between the partial spherical portion of the piston and the inner surface of the suction tube.

5. The foot valve portion has a structure in which a circular ball receiving base is provided at the bottom of the foot valve housing to hold the ball, A stopper is provided at the lower end of the suction tube to hold down the ball that has floated up, and the valve opens and closes according to the floating and sinking of the ball.

2. The high-viscosity fluid pump according to claim 1, wherein an upper portion of said circular ball receiving base is tapered, and said ball can be sandwiched by a lower end of said tapered portion.

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